US20140274470A1

US20140274470A1 - Golf ball compositions

Info

Publication number: US20140274470A1
Application number: US14/214,197
Authority: US
Inventors: Hyun J. Kim; Hong G. Jeon; Gwanghoon Kwag; Jae Yun Kim; Tae Hee Kim
Original assignee: TaylorMade Golf Co Inc
Current assignee: TaylorMade Golf Co Inc
Priority date: 2013-03-14
Filing date: 2014-03-14
Publication date: 2014-09-18

Abstract

The present invention relates to a golf ball including a core, one or more mantle layers and an outer cover layer, and one or more of the core, one or more mantle layers or outer cover layer includes a partially hydrogenated polybutadiene having a viscosity at 200° C. of less than about 5,000 Pa-sec and a storage modulus (G′) at 1 Hz and 25° C. of greater than about 1×10⁷dyn/cm².

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. provisional application 61/785,657, filed Mar. 14, 2013, which is incorporated herein by reference in its entirety.
The application of synthetic polymer chemistry to the field of sports equipment has revolutionized the performance of athletes in many sports. One sport in which this is particularly true is golf, especially as relates to advances in golf ball performance and ease of manufacture. For instance, the earliest golf balls consisted of a leather cover filled with wet feathers. These “feathery” golf balls were subsequently replaced with a single piece golf ball made from “gutta percha,” a naturally occurring rubber-like material. In the early 1900's, the wound rubber ball was introduced, consisting of a solid rubber core around which rubber thread was tightly wound with a gutta percha cover.
More modern golf balls can be classified as one-piece, two-piece, three-piece or multi-layered golf balls. One-piece balls are molded from a homogeneous mass of material with a dimple pattern molded thereon. One-piece balls are inexpensive and very durable, but typically do not provide great distance because of relatively high spin and low velocity. Two-piece balls are made by molding a cover around a solid rubber core. These are the most popular types of balls in use today. In attempts to further modify the ball performance, especially in terms of the distance such balls travel, and the spin and the feel transmitted to the golfer through the club on striking the ball, the basic two piece ball construction has been further modified by the introduction of additional layers between the core and outer cover layer. If one additional layer is introduced between the core and outer cover layer a so called “three-piece ball” results, if two additional layers are introduced between the core and outer cover layer, a so called “four-piece ball” results, and so on.
Golf ball covers were previously made from balata rubber which was favored by some players because the softness of the cover allowed them to achieve spin rates sufficient to allow more precise control of ball direction and distance, particularly on shorter approach shots. However balata-covered balls, although exhibiting high spin and soft feel, were often deficient in terms of the durability of the cover which had a propensity to shear
Accordingly, a variety of golf ball constructions have been developed in an attempt to provide spin rates and a feel approaching those of balata covered balls, while also providing a golf ball with a higher durability and overall distance. This has resulted in the emergence of balls, which have a solid rubber core, an outer cover layer, and one or more so called intermediate layers, as well as the application of new materials to each of these components.
A material which has been often utilized in more modern golf balls includes the various ionomer resins developed in the mid-1960's, by E.I. DuPont de Nemours and Co., and sold under the trademark SURLYN®. These ionomer resins have, to a large extent, replaced balata as a golf ball cover stock material. More recent developments in the field have attempted to utilize the various types of ionomers, both singly and in blend compositions to optimize the often conflicting golf ball performance requirements of high C.O.R. and ball velocity, and cover durability, with the need for a ball to spin and have a so-called soft feel on shorter iron shots. However, the incorporation of more acid in the ionomer and/or increasing its degree of neutralization results in a material with increased polarity, and hence one which is often less compatible with other potential blend materials. Also increasing the acid content of the ionomer while increasing C.O.R. may render the ball too hard and brittle causing a loss of shot feel, control (i.e., the ability to spin the ball) and may render the cover too brittle and prone to premature failure. Finally, the incorporation of more acid in the ionomer and/or increasing its degree of neutralization typically results in an increase in melt viscosity which in turn greatly decreases the processability of these resins. Attempts to mediate these effects by adding softer terpolymeric ionomers to high acid ionomer compositions to adjust the hardness and improve the shot “feel” often result in concomitant loss of C.O.R. and hence distance.
In an attempt to maintain the spin and feel performance of balata covers while improving their durability there has been some use of other synthetic rubber formulations to prepare golf ball cover and mantle layers, however to date most synthetic rubber formulations have been used in golf ball core formulations. Most synthetic rubber formulations used for the core compositions of modern golf balls are based on polybutadiene, especially cis-1,4-polybutadiene. In order to tailor the properties of the core, the polybutadiene is often further formulated with crosslinking agents, such as sulfur or peroxides, or by irradiation, as well as co-crosslinking agents such as zinc diacrylate. In addition, the weight and hardness of the core may be further adjusted by the incorporation of various filler materials in the rubber formulation. Thus, there is a great deal of literature concerning such formulation chemistry and the variation of the rubber composition and degree of cross linking such that cores may be produced with the required compression, resilience, hardness and durability.
However, the use of such formulations in other layers of the golf ball is somewhat limited given the manufacturing methods used in their preparation. After core formation, any intermediate layers and finally the golf ball outer cover and are typically formed over the core using one of three methods: casting, injection molding, or compression molding. Injection molding generally involves using a mold having one or more sets of two hemispherical mold sections that mate to form a spherical cavity during the molding process. The pairs of mold sections are configured to define a spherical cavity in their interior when mated. When used to mold an outer cover layer for a golf ball, the mold sections can be configured so that the inner surfaces that mate to form the spherical cavity include protrusions configured to form dimples on the outer surface of the molded cover layer. When used to mold a layer onto an existing structure, such as a ball core, the mold includes a number of support pins disposed throughout the mold sections. The support pins are configured to be retractable, moving into and out of the cavity perpendicular to the spherical cavity surface. The support pins maintain the position of the core while the molten material flows through the gates into the cavity between the core and the mold sections. The mold itself may be a cold mold or a heated mold.
In contrast, compression molding of a ball cover or intermediate layer typically requires the initial step of making half shells by injection molding the layer material into an injection mold. The half shells then are positioned in a compression mold around a ball core, whereupon heat and pressure are used to mold the half shells into a complete layer over the core, with or without a chemical reaction such as crosslinking. Compression molding also can be used as a curing step after injection molding. In such a process, an outer layer of thermally curable material is injection molded around a core in a cold mold. After the material solidifies, the ball is removed and placed into a mold, in which heat and pressure are applied to the ball to induce curing in the outer layer.
Of the various cover molding processes, injection molding is most preferred, due to the efficiencies gained by its use including a more rapid cycle time, cheaper operating costs and an improved ability to produce thinner layers around the core and closely control any thickness variation. This latter advantage is becoming more important with the developments of multi-layered balls with two or more intermediate layers between the core and cover thus requiring thinner layer formation. Such multilayered golf balls are often fabricated with chemically distinct layers to produce various combinations of hardness, modulus and other properties in order to tailor the resulting principal performance categories, including ball velocity, compression, spin and distance. However, in addition to being time consuming and expensive and imparting additional complexity to golf ball preparation, due to their differing chemical compositions, the individual layers often suffer from delamination often manifested as poor shear performance.
There were a number of early attempts to incorporate synthetic cis 1,4-polybutadiene rubber, as a layer around a central core or as an outer cover layer. For example, U.S. Pat. No. 3,784,209 exemplifies a ball prepared by forming a center of a first cis 1,4-polybutadiene formulation and forming a outer cover layer around it of a second cis 1,4-polybutadiene formulation and finally curing the resulting golf ball precursor in a compression molding step. Also, U.S. Pat. No. 4,625,964 exemplifies a golf ball having a central core made from cis 1,4-polybutadiene around which was compression molded two half shells previously prepared from another cis 1,4-polybutadiene formulation to form a second layer. The ball was completed by injection molding an ionomer outer cover layer. U.S. Pat. No. 4,714,253 exemplifies a golf ball having a central core formed from a first cis 1,4-polybutadiene formulation followed by forming an second layer from another cis 1,4-polybutadiene formulation. Two pre-formed ionomer half shells were then pressure molded around the two piece solid core to form the final golf ball. U.S. Pat. No. 4,848,770 exemplifies a three piece solid golf ball having a center produced from a highly filled cis 1,4-polybutadiene formulation and second layer produced from a second unfilled cis 1,4-polybutadiene formulation, followed by compression molding two ionomer half shells to form the outer cover layer.
However because of the relatively high viscosity of cis 1,4-polybutadiene formulations at normal injection molding temperatures, which becomes even more pronounced if such formulations also include filler, these formulations are not easily adaptable to traditional thin layer-forming injection molding techniques. Thus the current evolution in golf balls technology favors the use of thermoplastic materials such as ionomers or thermoplastic polyurethane in golf ball covers and intermediate layers, which materials are much more amenable to modern thin layer injection molding techniques.
Thus, it would be highly advantageous to have an injection moldable rubber composition with the soft feel of a rubber such as balata, but of sufficiently low viscosity to allow the material to be injection molded. It would also be highly advantageous if the properties of such a rubber composition could be tailored by similar formulation chemistry to that which has evolved through the use of crosslinked filled polybutadiene compositions used in core construction
The present disclosure provides a golf ball comprising one or more layers comprising an injection moldable partially hydrogenated polybutadiene rubber composition.
The present disclosure also provides processes for preparing a golf ball by injection molding layers of a partially hydrogenated polybutadiene rubber compositions with the required curative packages all having a sufficiently low viscosity at and below normal peroxide decomposition temperatures to allow the material to be injection molded to form a golf ball followed by compression molding the resulting golf ball or golf ball precursor to form a region in the golf ball made from a partially hydrogenated polybutadiene rubber.
The present disclosure also provides processes for preparing a golf ball by injection molding half shells of a partially hydrogenated polybutadiene rubber compositions having a sufficiently low viscosity at and below normal peroxide decomposition temperatures to allow the material to be injection molded to form a half shells, followed by combining the half shells around a golf ball core or golf ball precursor and compression molding the resulting golf ball or golf ball precursor to form the golf ball or golf ball layer.

SUMMARY

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a three-piece golf ball 1 comprising a solid center or core 2, a mantle layer 3, and an outer cover layer 4.

FIG. 2 illustrates a four-piece golf ball 1 comprising a core 2, and an outer cover layer 5, an inner mantle layer 3, and an outer mantle layer 4.

FIG. 3 illustrates a five-piece golf ball 1 comprising a core 2, and an outer cover layer 5, an inner mantle layer 3, an outer mantle layer 4, and an intermediate mantle layer 6.

DETAILED DESCRIPTION OF INVENTION

Any numerical values recited herein include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value. As an example, if it is stated that the amount of a component or a value of a process variable is from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. are expressly enumerated in this specification. For values, which have less than one unit difference, one unit is considered to be 0.1, 0.01, 0.001, or 0.0001 as appropriate. Thus all possible combinations of numerical values between the lowest value and the highest value enumerated herein are said to be expressly stated in this application.
The term “bimodal polymer” refers to a polymer comprising two main fractions and more specifically to the form of the polymers molecular weight distribution curve, i.e., the appearance of the graph of the polymer weight fraction as function of its molecular weight. When the molecular weight distribution curves from these fractions are superimposed into the molecular weight distribution curve for the total resulting polymer product, that curve will show two maxima or at least be distinctly broadened in comparison with the curves for the individual fractions. Such a polymer product is called bimodal. It is to be noted here that also the chemical compositions of the two fractions may be different.
As used herein, the term “block copolymer” is intended to mean a polymer comprising two or more homopolymer subunits linked by covalent bonds. The union of the homopolymer subunits may require an intermediate non-repeating subunit, known as a junction block. Block copolymers with two or three distinct blocks are called diblock copolymers and triblock copolymers, respectively.
The term “core” is intended to mean the elastic center of a golf ball. The core maybe a unitary core and also be of a so called “dual core” construction. When the term unitary core is used then it is understood that any adjacent layers to the core are mantle layers and not core layers. A dual core is made of up of (i) an interior spherical center component formed from a thermoset material, preferably polybutadiene and (ii) a second region formed around the interior spherical center component, also formed from a thermoset material, and preferably butadiene. Although the two core regions which constitute the dual core may both be formed from polybutadiene, each region preferably has different physical properties such as resilience, hardness or modulus resulting from the use of different crosslinking packages and/or processing conditions.
The term “outer cover layer” is intended to mean the outermost layer of the golf ball; this is the layer that is directly in contact with paint and/or ink on the surface of the golf ball. If the cover consists of two or more layers, only the outermost layer is designated the outer cover layer, and the next layer inward to the direction of the core is known as the inner cover layer.
The term “fiber” as used herein is a general term for which the definition given in Engineered Materials Handbook, Vol. 2, “Engineering Plastics”, published by A.S.M. International, Metals Park, Ohio, USA, is relied upon to refer to filamentary materials with a finite length that is at least 100 times its diameter, which is typically 0.10 to 0.13 mm (0.004 to 0.005 in.). Fibers can be continuous or specific short lengths (discontinuous), normally no less than 3.2 mm (⅛ in.). Although fibers according to this definition are preferred, fiber segments, i.e., parts of fibers having lengths less than the aforementioned are also considered to be encompassed by the invention. Thus, the terms “fibers” and “fiber segments” are used herein. In the claims appearing at the end of this disclosure in particular, the expression “fibers or fiber segments” and “fiber elements” are used to encompass both fibers and fiber segments.
The term “hydrocarbyl” is intended to mean any aliphatic, cycloaliphatic, aromatic, aryl substituted aliphatic, aryl substituted cycloaliphatic, aliphatic substituted aromatic, or cycloaliphatic substituted aromatic groups. The aliphatic or cycloaliphatic groups are preferably saturated. Likewise, the term “hydrocarbyloxy” means a hydrocarbyl group having an oxygen linkage between it and the carbon atom to which it is attached.
The term “injection moldable” as used herein, and as applied to the rubber compositions used as described herein refers to a material amenable to use in injection molding apparatus designed for use with typical thermoplastic resins. In one example, the term injection moldable composition as applied to the uncrosslinked rubbers used in the present disclosure means compositions having a viscosity using a Dynamic Mechanical Analyzer (DMA) and ASTM D4440 at 200° C. of less than about 5,000 Pa-sec, preferably less than about 3,000 Pa-sec, more preferably less than about 2,000 Pa-sec and even more preferably less than about 1,000 Pa-sec. and a storage modulus (G′) at 1 Hz measured using a Dynamic Mechanical Analyzer (DMA) and ASTM D4065, and ASTM D4440, at 25° C., and 1 Hz of greater than about 1×10⁷dyn/cm², preferably greater than about 1.5×10⁷dyn/cm², more preferably greater than about 1×10⁸dyn/cm², and most preferably greater than about 2×10⁸dyn/cm².
The term “mantle layer” is intended to mean any layer(s) in a golf ball disposed between the core (and any core layers) and the innermost cover layer. Should a ball have three mantle layers, these may be distinguished as “inner mantle layer” which refers to the mantle layer nearest the core and furthest from the outer cover layer, as opposed to the “outer mantle layer” which refers to the mantle layer furthest from the core and closest to the outer cover layer, and as opposed to the “intermediate mantle layer” which refers to the mantle layer between the inner mantle layer and the outer mantle layer. Should a ball have four mantle layers, these may be distinguished as “inner mantle layer” which refers to the mantle layer nearest the core and furthest from the outer cover layer, as opposed to the “outer mantle layer” which refers to the mantle layer furthest from the core and closest to the outer cover layer, and as opposed to the “inner intermediate mantle layer” which refers to the mantle layer immediately adjacent to and outward of the inner mantle layer and as opposed to the “outer intermediate mantle layer” which refers to the mantle layer immediately adjacent to and inward of the outer mantle layer and immediately adjacent to and outward of the inner intermediate mantle layer.
The term “(meth)acrylic acid copolymers” is intended to mean copolymers of methacrylic acid and/or acrylic acid.
The term “(meth)acrylate” is intended to mean an ester of methacrylic acid and/or acrylic acid.
The term “partially neutralized” is intended to mean an ionomer with a degree of neutralization of less than 100 percent. The term “highly neutralized” is intended to mean an ionomer with a degree of neutralization of greater than 50 percent. The term “fully neutralized” is intended to mean an ionomer with a degree of neutralization of 100 percent.
The term “prepolymer” as used herein is intended to mean any polymeric material that can be further processed to form a final polymer material of a manufactured golf ball, such as, by way of example and not limitation, a polymerized or partially polymerized material that can undergo additional processing, such as crosslinking.
The term “sports equipment” refers to any item of sports equipment such as sports clothing, boots, sneakers, clogs, sandals, slip on sandals and shoes, golf shoes, tennis shoes, running shoes, athletic shoes, hiking shoes, skis, ski masks, ski boots, cycling shoes, soccer boots, golf clubs, golf bags, and the like.
The term “thermoplastic” as used herein is intended to mean a material that is capable of softening or melting when heated and of hardening again when cooled. Thermoplastic polymer chains often are not cross-linked or are lightly crosslinked using a chain extender, but the term “thermoplastic” as used herein may refer to materials that initially act as thermoplastics, such as during an initial extrusion process or injection molding process, but which also may be crosslinked, such as during a compression molding step to form a final structure.
The term “thermoset” as used herein is intended to mean a material that crosslinks or cures via interaction with as crosslinking or curing agent. Crosslinking may be induced by energy, such as heat (generally above 200° C.), through a chemical reaction (by reaction with a curing agent), or by irradiation. The resulting composition remains rigid when set, and does not soften with heating. Thermosets have this property because the long-chain polymer molecules cross-link with each other to give a rigid structure. A thermoset material cannot be melted and re-molded after it is cured. Thus thermosets do not lend themselves to recycling unlike thermoplastics, which can be melted and re-molded.
The term “thermoplastic polyurethane” as used herein is intended to mean a material prepared by reaction of a prepared by reaction of a diisocyanate with a polyol, and optionally addition of a chain extender.
The term “thermoplastic polyurea” as used herein is intended to mean a material prepared by reaction of a prepared by reaction of a diisocyanate with a polyamine, with optionally addition of a chain extender.
The term “thermoset polyurethane” as used herein is intended to mean a material prepared by reaction of a diisocyanate with a polyol (or a prepolymer of the two), and a curing agent.
The term “thermoset polyurea” as used herein is intended to mean a material prepared by reaction of a diisocyanate with a polyamine (or a prepolymer of the two) and a curing agent.
The term “unimodal polymer” refers to a polymer comprising one main fraction and more specifically to the form of the polymers molecular weight distribution curve, i.e., the molecular weight distribution curve for the total polymer product shows only a single maximum.
The term “urethane prepolymer” as used herein is intended to mean the reaction product of diisocyanate and a polyol.
The term “urea prepolymer” as used herein is intended to mean the reaction product of a diisocyanate and a polyamine.
The term “zwitterion” as used herein is intended to mean a form of the compound having both an amine group and carboxylic acid group, where both are charged and where the net charge on the compound is neutral.
The present invention can be used in forming golf balls of any desired size. “The Rules of Golf” by the USGA dictate that the size of a competition golf ball must be at least 1.680 inches in diameter; however, golf balls of any size can be used for leisure golf play. The preferred diameter of the golf balls is from about 1.680 inches to about 1.800 inches. The more preferred diameter is from about 1.680 inches to about 1.760 inches. A diameter of from about 1.680 inches to about 1.740 inches is most preferred; however diameters anywhere in the range of from 1.70 to about 2.0 inches can be used. Oversize golf balls with diameters above about 1.760 inches to as big as 2.75 inches are also within the scope of the invention.
The golf balls of the present invention comprise an injection moldable partially hydrogenated polybutadiene (“PHPB”) in one or more of their core, mantle and outer cover layers.

Partially Hydrogenated Polybutadiene (“PHPB”).

In general, 1,3-butadiene can be polymerized to yield cis, trans and vinyl polymers as shown in the composite of each depicted in FIG. 1.
The properties of the resulting isomeric forms of polybutadiene differ as they can result from cis and trans linkages (both resulting from 1,4-addition) as well as linkages resulting from 1,2-addition which results in vinyl group side chains in the polymer. For example, “high cis” polybutadiene is characterized by a high proportion of cis linkages (typically over 92%) and a small proportion of vinyl groups (less than 4%). It typically has high elasticity and thus is often used in typical golf ball core formulations. So-called “low cis” polybutadiene typically contains about 35% cis, 55% trans and 10% vinyl and has a high liquid-glass transition, and can be advantageously used as an additive in plastics due to its low contents of gels. So-called “high trans” polybutadiene is a crystalline polymer (i.e. not an elastomer) which melts at about 80° C. and has been used for golf ball cover layers, due to its similarity in structure to polyisoprene balata rubber. “High-vinyl” polybutadiene typically has over 70% vinyl content resulting from a 1,2-addition mechanism. In addition to these kinds of connectivity, polybutadienes can also differ in terms of their branching their molecular weights and molecular weight distributions.
The polybutadiene to be hydrogenated to form the PHPB for use in the golf ball of the present invention may contain of from about 20 to about 80 preferably of from about 30 to about 70, and more preferably of from about 45 to about 65 mol percent trans 1,4-addition. The polybutadiene to be hydrogenated to form the PHPB for use in the golf ball of the present invention may contain of from about 10 to about 70, preferably of from about 20 to about 60, and more preferably of from about and about 25 to about 45 mole percent cis 1,4-addition. The remainder of the polymer is formed by 1,2-addition of the 1,3-butadiene to give the 1,2 vinyl content. These polymers are prepared by polymerizing butadiene in a suitable solvent (which does not adversely affect the polymerization, for example, a hydrocarbon solvent), in the presence of a suitable organo-metallic catalyst, for example, a hydrocarbyllithium catalyst and preferably in the presence of a Lewis base.
The weight average molecular weight of the polybutadiene to be hydrogenated to form the PHPB product is in the range of from about 50,000 to about 300,000, preferably of from about 75,000 to about 250,000, even more preferably of from about 90,000 to about 200,000.
The lithium-based catalysts employed for the polymerization of 1,3-butadiene may comprise metallic lithium, organolithium compounds, or other compounds of lithium in which lithium can displace hydrogen from water. Organolithium compounds, as used herein, include the various hydrocarbyllithiums, i.e., hydrocarbons in which one or more hydrogen atoms have been replaced by lithium, and adducts of lithium with polycyclic aromatic compounds. Suitable hydrocarbyllithiums include, for instance, alkyllithium compounds, such as methyllithium, ethyllithium, butyllithium, amyllithium, hexyllithium, 2-ethylhexyllithium and n-hexyldecyllithium.
The concentration of the lithium catalyst employed can vary widely depending on the particular catalyst employed, reaction conditions, the product desired, etc. For example, concentrations of catalyst, based on solvent and actual weight of lithium in the catalyst, can vary from about 0.001 to about 10 percent or greater.
Lewis bases which can be employed include ethers, thioethers, tertiary amines and the like, in concentrations of about 0.5 to about 20 percent, based on solvent. The actual concentration of the Lewis base will depend upon the particular Lewis base used and the polymer desired.
The organic ethers that are employed include alkyl, aryl, aralkyl, alkaryl and cyclic ethers such as dioxane and tetrahydrofuran. Ethers of glycols may also be employed, for example, the dimethyl ether of diethylene glycol. The corresponding thioethers and tertiary amines can also be employed.
Aromatic, aliphatic and alicyclic hydrocarbon solvents can be employed. Alicyclic solvents include cyclohexane. Aliphatic solvents include heptane, pentane, butane, hexane and the like. Aromatic solvents include benzene, toluene and xylenes.
Polymerization temperatures in the range of 10°-100° C. can be used. Pressures of atmospheric to ten or twenty atmospheres are employed so as to maintain a high concentration of the reactant in the liquid phase. The concentration of the butadiene in the solvent can vary widely such as from 5 to 75 percent.
The polymerization is carried out in an inert atmosphere, in the absence of air, carbon dioxide, oxygen and the like. It can be carried out under an atmosphere of an inert gas such as pure nitrogen, helium, argon, etc., in vacuum, or under a pressure of inert organic materials.
Hydrogenation to form the PHPB used in the golf balls of the present invention may be accomplished by any of a number of hydrogenation techniques well known in the art. U.S. Pat. No. 4,187,360, the entire contents of which are incorporated by reference herein, discloses a hydrogenated polybutadiene prepared from a polybutadiene prepared using an organolithium-based catalyst system. The patent also discloses that the resulting polybutadiene can be subsequently hydrogenated using a number of hydrogenation catalysts, such as nickel-kieselguhr, Raney nickel, copper chromite, molybdenum sulfide, finely divided platinum, finely divided palladium, platinum oxide, copper chromium oxide, and the like.
In addition, U.S. Pat. No. 3,663,635, DE 3401983, U.S. Pat. No. 5,039,755, U.S. Pat. No. 5,132,372, EP 339986, EP 434469, EP 544304, EP 795564, EP 810231, and WO 9525130 describe catalyst systems for the hydrogenation of olefinically unsaturated compounds, and in particular for the hydrogenation of conjugated diene (co)polymers.
More particularly, U.S. Pat. No. 3,663,635, the entire contents of which are incorporated by reference herein, for instance, describes catalyst systems for the hydrogenation of unsaturated compounds such as olefins based on titanocenes of the formula TiX₂Y₂in which X represents halide, amino, hydrocarbylamino, thio, carboxylate, alkoxide or a hydrogen atom, and Y is cyclopentadienyl, indenyl, fluorenyl or allyl substituted or not, which are reacted with an aluminium hydride.
U.S. Pat. No. 5,039,755, the entire contents of which are incorporated by reference herein describes the hydrogenation of a conjugated diene (co)polymer that is terminated with hydrogen in the presence of a titanocene to which sec-butyllithium is added.
U.S. Pat. No. 5,132,372 concerns the use of methyl benzoate as promoting agent in titanocene-based hydrogenation reactions. Further promoters are disclosed in U.S. Pat. No. 5,173,537 which describes the deactivation of lithium hydride by addition of various reagents prior to hydrogenation and titanium catalyst addition.
In addition, U.S. Pat. No. 6,313,230 and U.S. Pat. No. 6,465,609, the entire contents of each of which are incorporated by reference herein, which disclose the use of a hydrogenation catalyst composition comprising an organotitanium compound.
The polybutadiene prepared above may be directly hydrogenated without separating the polybutadiene from solution or isolated and dissolved prior to hydrogenation. Thereupon the hydrogenated polymer can be separated from solution by standard procedures.
Typically the polybutadiene is diluted with an inert solvent, such as those previously mentioned, or in the original polymerization medium and the polymer solution and hydrogenation catalyst are added to a high pressure autoclave. The autoclave is pressured with hydrogen and then heated, while mixing. The reactor is then depressurized, the catalyst removed by filtering, and the hydrogenated polymer recovered from the solvent by conventional stripping procedures.
The hydrogenation catalyst will generally be used in an amount of 0.1 to 20 weight percent based upon the weight of the polymer to be hydrogenated. The specific amount of catalyst employed depends somewhat upon the specific catalyst used.
The polymers can be recovered by procedures well known in the art. For example, polar materials, such as water or C₁to C₅alkanols can be added to inactivate the catalyst After termination of the reaction, the hydrocarbon solution is washed with water or dilute mineral acid. Alternatively, the active polymer solution can be treated with hydrated clays, such as natural Attapulgus clay, which functions to both inactivate the catalyst and to chemically absorb the lithium component. The polymer may then be recovered by filtering the resultant polymer solution, drying if necessary, and stripping of remaining inert diluent at elevated temperatures. For the isolation of higher molecular weight polymers steam stripping or precipitation with anti-solvents is preferred.
The polymers can be hydrogenated according to the following ranges of reaction conditions. Reaction pressures are preferably in the range of atmospheric to 3,000 psig. The temperature can range from about 25° C. up to the degradation temperature of the polymer. The reaction times can be in the range of 1 to 24 hours. The amount of catalyst required is a function of the temperature of hydrogenation.
The hydrogenation is carried out to such a degree that of from about 25 to about 75, preferably of from about 30 to about 70, more preferably of from about 35 to about 65 and even more preferably of from about 40 to about 60% of double bonds in the original polybutadiene have been hydrogenated and are thus saturated.
Given the unsaturation present in the elastomer backbone the PHPB compositions are also amenable to the various methods used to crosslink elastomeric rubber compositions including vulcanization, and radiation crosslinking. Radiation can be applied to the unsaturated polymer mixture by any known method, including using microwave or gamma radiation, or an electron beam device. Additives may also be used to improve radiation curing of the diene polymer.
Preferably the PHPB composition is crosslinked using the typical peroxide-based crosslinking systems typically used in golf ball core preparation. Suitable cross-linking agents include peroxides, sulfur compounds, or other known chemical cross-linking agents, as well as mixtures of these. Non-limiting examples of suitable cross-linking agents include primary, secondary, or tertiary aliphatic or aromatic organic peroxides. Peroxides containing more than one peroxy group can be used, such as 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 1,4-di-(2-tert-butyl peroxyisopropyl)benzene. Both symmetrical and asymmetrical peroxides can be used, for example, tert-butyl perbenzoate and tert-butyl cumyl peroxide. Peroxides incorporating carboxyl groups also are suitable. The decomposition of peroxides used as cross-linking agents in the present invention can be brought about by applying thermal energy, shear, irradiation, reaction with other chemicals, or any combination of these. Both homolytically and heterolytically decomposed peroxide can be used in the present invention. Non-limiting examples of suitable peroxides include: diaacetyl peroxide; di-tert-butyl peroxide; dibenzoyl peroxide; dicumyl peroxide; 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; 1,4-bis-(t-butylperoxyisopropyl)benzene; t-butylperoxybenzoate; 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, such as Trigonox 145-45B, marketed by Akrochem Corp. of Akron, Ohio; 1,1-bis(t-butylperoxy)-3,3,5 tri-methylcyclohexane, such as Varox 231-XL, marketed by R.T. Vanderbilt Co., Inc. of Norwalk, Conn.; and di-(2,4-dichlorobenzoyl)peroxide. The cross-linking agents can be blended in total amounts of about 0.05 part to about 5 parts, more preferably about 0.2 part to about 3 parts, and most preferably about 0.2 part to about 2 parts, by weight of the cross-linking agents per 100 parts by weight of the unsaturated polymer.
Each cross-linking agent has a characteristic decomposition temperature at which 50% of the cross-linking agent has decomposed when subjected to that temperature for a specified time period (t_1/2). For example, 1,1-bis-(t-butylperoxy)-3,3,5-tri-methylcyclohexane at t_1/2=0.1 hr has a decomposition temperature of 138° C. and 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3 at t_1/2=0.1 hr has a decomposition temperature of 182° C. Two or more cross-linking agents having different characteristic decomposition temperatures at the same t_1/2may be blended in the composition. For example, where at least one cross-linking agent has a first characteristic decomposition temperature less than 150° C., and at least one cross-linking agent has a second characteristic decomposition temperature greater than 150° C., the composition weight ratio of the at least one cross-linking agent having the first characteristic decomposition temperature to the at least one cross-linking agent having the second characteristic decomposition temperature can range from 5:95 to 95:5, or more preferably from 10:90 to 50:50.
Suitable co-cross-linking agents, may be a metal salt of an unsaturated carboxylic acid. Examples of these include zinc and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms, such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid, palmitic acid with the zinc salts of acrylic and methacrylic acid being most preferred. The unsaturated carboxylic acid metal salt can be blended in a rubber either as a preformed metal salt, or by introducing an α,β-unsaturated carboxylic acid and a metal oxide or hydroxide into the rubber composition, and allowing them to react in the rubber composition to form a metal salt. The unsaturated carboxylic acid metal salt can be blended in any desired amount, but preferably in amounts of about 10 parts to about 60 parts by weight of the unsaturated carboxylic acid per 100 parts by weight of the synthetic rubber.
The crosslinking package for the PHPB compositions may also incorporate one or more of the so-called “peptizers”. The peptizer preferably comprises an organic sulfur compound and/or its metal or non-metal salt. Examples of such organic sulfur compounds include thiophenols, such as pentachlorothiophenol, 4-butyl-o-thiocresol, 4 t-butyl-p-thiocresol, and 2-benzamidothiophenol; thiocarboxylic acids, such as thiobenzoic acid; 4,4′ dithio dimorpholine; and, sulfides, such as dixylyl disulfide, dibenzoyl disulfide; dibenzothiazyl disulfide; di(pentachlorophenyl)disulfide; dibenzamido diphenyldisulfide (DBDD), and alkylated phenol sulfides, such as VULTAC marketed by Atofina Chemicals, Inc. of Philadelphia, Pa. Preferred organic sulfur compounds include pentachlorothiophenol, and dibenzamido diphenyldisulfide.
Examples of the metal salt of an organic sulfur compound include sodium, potassium, lithium, magnesium calcium, barium, and cesium and zinc salts of the above-mentioned thiophenols and thiocarboxylic acids, with the zinc salt of pentachlorothiophenol being most preferred.
Examples of the non-metal salt of an organic sulfur compound include ammonium salts of the above-mentioned thiophenols and thiocarboxylic acids wherein the ammonium cation has the general formula [NR¹R²R³R⁴]⁺ where R¹, R², R³and R⁴are selected from the group consisting of hydrogen, a C₁-C₂₀aliphatic, cycloaliphatic or aromatic moiety, and any and all combinations thereof, with the most preferred being the NH₄ ⁺-salt of pentachlorothiophenol.
Additional peptizers include aromatic or conjugated peptizers comprising one or more heteroatoms, such as nitrogen, oxygen and/or sulfur. More typically, such peptizers are heteroaryl or heterocyclic compounds having at least one heteroatom, and potentially plural heteroatoms, where the plural heteroatoms may be the same or different. Such peptizers include peptizers such as an indole peptizer, a quinoline peptizer, an isoquinoline peptizer, a pyridine peptizer, purine peptizer, a pyrimidine peptizer, a diazine peptizer, a pyrazine peptizer, a triazine peptizer, a carbazole peptizer, or combinations of such peptizers.
Suitable peptizers also may include one or more additional functional groups, such as halogens, particularly chlorine; a sulfur-containing moiety exemplified by thiols, where the functional group is sulfhydryl (—SH), thioethers, where the functional group is —SR, disulfides, (R₁S—SR₂), etc.; and combinations of functional groups. Such peptizers are more fully disclosed in U.S. Pat. No. 8,030,411 in the name of Hyun Kim et al, the entire contents of which are herein incorporated by reference. A most preferred example is 2, 3, 5, 6-tetrachloro-4-pyridinethiol (TCPT).
The peptizer, if employed is present in an amount up to about 10, from about 0.01 to about 10, preferably of from about 0.10 to about 7, more preferably of from about 0.15 to about 5 parts by weight per 100 parts by weight of the synthetic rubber component.
The PHPB crosslinking compositions can also comprise one or more accelerators of one or more classes. Accelerators are added to an unsaturated polymer to increase the vulcanization rate and/or decrease the vulcanization temperature. Accelerators can be of any class known for rubber processing including mercapto-, sulfenamide-, thiuram, dithiocarbamate, dithiocarbamyl-sulfenamide, xanthate, guanidine, amine, thiourea, and dithiophosphate accelerators. Specific commercial accelerators include 2-mercaptobenzothiazole and its metal or non-metal salts, such as Vulkacit Mercapto C, Mercapto MGC, Mercapto ZM-5, and ZM marketed by Bayer AG of Leverkusen, Germany, Nocceler M, Nocceler MZ, and Nocceler M-60 marketed by Ouchisinko Chemical Industrial Company, Ltd. of Tokyo, Japan, and MBT and ZMBT marketed by Akrochem Corporation of Akron, Ohio. A more complete list of commercially available accelerators is given in The Vanderbilt Rubber Handbook: 13^thEdition (1990, R.T. Vanderbilt Co.), pp. 296-330, in Encyclopedia of Polymer Science and Technology, Vol. 12 (1970, John Wiley & Sons), pp. 258-259, and in Rubber Technology Handbook (1980, Hanser/Gardner Publications), pp. 234-236. Preferred accelerators include 2-mercaptobenzothiazole (MBT) and its salts. The PHPB composition can further incorporate from about 0.1 part to about 10 parts by weight of the accelerator per 100 parts by weight of the rubber. More preferably, the ball composition can further incorporate from about 0.2 part to about 5 parts, and most preferably from about 0.5 part to about 1.5 parts, by weight of the accelerator per 100 parts by weight of the rubber.

F. Polymer Components

The PHPB compositions may be used directly to prepare the core, outer cover layer and/or one or more intermediate layers of the golf balls of the present invention or they may be further blended with additional polymers prior to or after crosslinking and which additional polymers may also be used as a separate component of the core, cover layer or intermediate layer of the golf balls of the present invention. These additional polymers may include, without limitation, other synthetic and natural rubbers, including the polyalkenamers, cis-1,4-polybutadiene, trans-1,4-polybutadiene, 1,2-polybutadiene, cis-polyisoprene, trans-polyisoprene, polychloroprene, polybutylene, styrene-butadiene rubber, styrene-butadiene-styrene block copolymer and partially and fully hydrogenated equivalents, styrene-isoprene-styrene block copolymer and partially and fully hydrogenated equivalents, nitrile rubber, silicone rubber, and polyurethane, as well as mixtures of these, carboxyl-terminated butadiene (CTBN) and butadiene grafted with maleic anhydride (BMA), thermoset polymers such as thermoset polyurethanes and thermoset polyureas, as well as thermoplastic polymers including thermoplastic elastomers such as unimodal ethylene/carboxylic acid copolymers, unimodal ethylene/carboxylic acid/carboxylate terpolymers, bimodal ethylene/carboxylic acid copolymers, bimodal ethylene/carboxylic acid/carboxylate terpolymers, unimodal ionomers, bimodal ionomers, modified unimodal ionomers, modified bimodal ionomers, thermoplastic polyurethanes, thermoplastic polyureas, polyesters, copolyesters, polyamides, copolyamides, polycarbonates, polyolefins, polyphenylene oxide, polyphenylene sulfide, diallyl phthalate polymer, polyimides, polyvinyl chloride, polyamide-ionomer, polyurethane-ionomer, polyvinyl alcohol, polyarylate, polyacrylate, polyphenylene ether, impact-modified polyphenylene ether, polystyrene, high impact polystyrene, acrylonitrile-butadiene-styrene copolymer styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylonitrile, styrene-maleic anhydride (S/MA) polymer, styrenic copolymer, functionalized styrenic copolymer, functionalized styrenic terpolymer, styrenic terpolymer, cellulose polymer, liquid crystal polymer (LCP), ethylene-propylene-diene terpolymer (EPDM), ethylene-vinyl acetate copolymers (EVA), ethylene-propylene copolymer, ethylene vinyl acetate, polyurea, and polysiloxane and any and all combinations thereof.
The olefinic thermoplastic elastomers include metallocene-catalyzed polyolefins, ethylene-octene copolymer, ethylene-butene copolymer, and ethylene-propylene copolymers all with or without controlled tacticity as well as blends of polyolefins having ethyl-propylene-non-conjugated diene terpolymer, rubber-based copolymer, and dynamically vulcanized rubber-based copolymer. Examples of these include products sold under the trade names SANTOPRENE, DYTRON, VISAFLEX, and VYRAM by Advanced Elastomeric Systems of Houston, Tex., and SARLINK by DSM of Haarlen, the Netherlands.
Examples of rubber-based thermoplastic elastomers include multiblock rubber-based copolymers, particularly those in which the rubber block component is based on butadiene, isoprene, or ethylene/butylene. The non-rubber repeating units of the copolymer may be derived from any suitable monomers, including meth(acrylate) esters, such as methyl methacrylate and cyclohexylmethacrylate, and vinyl arylenes, such as styrene. Examples of styrenic copolymers are resins manufactured by Kraton Polymers (formerly of Shell Chemicals) under the trade names KRATON D (for styrene-butadiene-styrene and styrene-isoprene-styrene types) and KRATON G (for styrene-ethylene-butylene-styrene and styrene-ethylene-propylene-styrene types) and Kuraray under the trade name SEPTON. Examples of randomly distributed styrenic polymers include paramethylstyrene-isobutylene (isobutene) copolymers developed by ExxonMobil Chemical Corporation and styrene-butadiene random copolymers developed by Chevron Phillips Chemical Corp.
The PHPB compositions may also be used in blends with copolyester thermoplastic elastomers which include polyether ester block copolymers, polylactone ester block copolymers, and aliphatic and aromatic dicarboxylic acid copolymerized polyesters. Polyether ester block copolymers are copolymers comprising polyester hard segments polymerized from a dicarboxylic acid and a low molecular weight diol, and polyether soft segments polymerized from an alkylene glycol having 2 to 10 atoms. Polylactone ester block copolymers are copolymers having polylactone chains instead of polyether as the soft segments discussed above for polyether ester block copolymers. Aliphatic and aromatic dicarboxylic copolymerized polyesters are copolymers of an acid component selected from aromatic dicarboxylic acids, such as terephthalic acid and isophthalic acid, and aliphatic acids having 2 to 10 carbon atoms with at least one diol component, selected from aliphatic and alicyclic diols having 2 to 10 carbon atoms. Blends of aromatic polyester and aliphatic polyester also may be used for these. Examples of these include products marketed under the trade names HYTREL by E.I. DuPont de Nemours & Company, and SKYPEL by S.K. Chemicals of Seoul, South Korea.
Examples of other thermoplastic elastomers suitable as additional polymer components include those having functional groups, such as carboxylic acid, maleic anhydride, glycidyl, norbonene, and hydroxyl functionalities. An example of these includes a block polymer having at least one polymer block A comprising an aromatic vinyl compound and at least one polymer block B comprising a conjugated diene compound, and having a hydroxyl group at the terminal block copolymer, or its hydrogenated product. An example of this polymer is sold under the trade name SEPTON HG-252 by Kuraray Company of Kurashiki, Japan. Other examples of these include: maleic anhydride functionalized triblock copolymer consisting of polystyrene end blocks and poly(ethylene/butylene), sold under the trade name KRATON FG 1901X by Shell Chemical Company; maleic anhydride modified ethylene-vinyl acetate copolymer, sold under the trade name FUSABOND by E.I. DuPont de Nemours & Company; ethylene-isobutyl acrylate-methacrylic acid terpolymer, sold under the trade name NUCREL by E.I. DuPont de Nemours & Company; ethylene-ethyl acrylate-methacrylic anhydride terpolymer, sold under the trade name BONDINE AX 8390 and 8060 by Sumitomo Chemical Industries; brominated styrene-isobutylene copolymers sold under the trade name BROMO XP-50 by Exxon Mobil Corporation; and resins having glycidyl or maleic anhydride functional groups sold under the trade name LOTADER by Elf Atochem of Puteaux, France.
The other polymer materials may also include the polyamides. The term “polyamide” as used herein includes both homopolyamides and copolyamides. Illustrative polyamides for use in the polyalkenamer/polyamide compositions include those obtained by: (1) polycondensation of (a) a dicarboxylic acid, such as oxalic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic acid, with (b) a diamine, such as ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, decamethylenediamine, 1,4-cyclohexyldiamine or m-xylylenediamine; (2) a ring-opening polymerization of cyclic lactam, such as ε-caprolactam or ω-laurolactam; (3) polycondensation of an aminocarboxylic acid, such as 6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid or 12-aminododecanoic acid; (4) copolymerization of a cyclic lactam with a dicarboxylic acid and a diamine; or any combination of (1)-(4). In certain examples, the dicarboxylic acid may be an aromatic dicarboxylic acid or a cycloaliphatic dicarboxylic acid. In certain examples, the diamine may be an aromatic diamine or a cycloaliphatic diamine. Specific examples of suitable polyamides include polyamide 6; polyamide 11; polyamide 12; polyamide 4,6; polyamide 6,6; polyamide 6,9; polyamide 6,10; polyamide 6,12; polyamide MXD6; PA12, CX; PA12, IT; PPA; PA6, IT; and PA6/PPE. Also included are the crosslinked polyamide compositions descried in copending application 61/746,540 filed on the 27^thof December 2012 in the name of the Taylor Made Colf Co. Inc and incorporated herein by reference in its entirety.
The polyamide (which may a polyamide as described above) may also be blended with a functional polymer modifier of. The functional polymer modifier of the polyamide can include copolymers or terpolymers having a glycidyl group, hydroxyl group, maleic anhydride group or carboxylic group, collectively referred to as functionalized polymers. These copolymers and terpolymers may comprise an α-olefin. Examples of suitable α-olefins include ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-petene, 3-methyl-1-pentene, 1-octene, 1-decene-, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, 1-dococene, 1-tetracocene, 1-hexacocene, 1-octacocene, and 1-triacontene. One or more of these α-olefins may be used.
Examples of suitable glycidyl groups in copolymers or terpolymers in the polymeric modifier include esters and ethers of aliphatic glycidyl, such as allylglycidylether, vinylglycidylether, glycidyl maleate and itaconatem glycidyl acrylate and methacrylate, and also alicyclic glycidyl esters and ethers, such as 2-cyclohexene-1-glycidylether, cyclohexene-4,5 diglyxidylcarboxylate, cyclohexene-4-glycidyl carboxylate, 5-norboenene-2-methyl-2-glycidyl carboxylate, and endocis-bicyclo(2,2,1)-5-heptene-2,3-diglycidyl dicarboxylate. These polymers having a glycidyl group may comprise other monomers, such as esters of unsaturated carboxylic acid, for example, alkyl(meth)acrylates or vinyl esters of unsaturated carboxylic acids. Polymers having a glycidyl group can be obtained by copolymerization or graft polymerization with homopolymers or copolymers.
Examples of suitable terpolymers having a glycidyl group include LOTADER AX8900 and AX8920, marketed by Atofina Chemicals, ELVALOY marketed by E.I. Du Pont de Nemours & Co., and REXPEARL marketed by Nippon Petrochemicals Co., Ltd. Additional examples of copolymers comprising epoxy monomers and which are suitable for use within the scope of the present invention include styrene-butadiene-styrene block copolymers in which the polybutadiene block contains epoxy group, and styrene-isoprene-styrene block copolymers in which the polyisoprene block contains epoxy. Commercially available examples of these epoxy functional copolymers include ESBS A1005, ESBS A1010, ESBS A1020, ESBS AT018, and ESBS AT019, marketed by Daicel Chemical Industries, Ltd.
Examples of polymers or terpolymers incorporating a maleic anhydride group suitable for use within the scope of the present invention include maleic anhydride-modified ethylene-propylene copolymers, maleic anhydride-modified ethylene-propylene-diene terpolymers, maleic anhydride-modified polyethylenes, maleic anhydride-modified polypropylenes, ethylene-ethylacrylate-maleic anhydride terpolymers, and maleic anhydride-indene-styrene-cumarone polymers. Examples of commercially available copolymers incorporating maleic anhydride include: BONDINE, marketed by Sumitomo Chemical Co., such as BONDINE AX8390, an ethylene-ethyl acrylate-maleic anhydride terpolymer having a combined ethylene acrylate and maleic anhydride content of 32% by weight, and BONDINE TX TX8030, an ethylene-ethyl acrylate-maleic anhydride terpolymer having a combined ethylene acrylate and maleic anhydride content of 15% by weight and a maleic anhydride content of 1% to 4% by weight; maleic anhydride-containing LOTADER 3200, 3210, 6200, 8200, 3300, 3400, 3410, 7500, 5500, 4720, and 4700, marketed by Atofina Chemicals; EXXELOR VA1803, a maleic anyhydride-modified ethylene-propylene copolymer having a maleic anyhydride content of 0.7% by weight, marketed by Exxon Chemical Co.; and KRATON FG 1901×, a maleic anhydride functionalized triblock copolymer having polystyrene endblocks and poly(ethylene/butylene) midblocks, marketed by Shell Chemical.
Preferably the functional polymer component is a maleic anhydride grafted polymers preferably maleic anhydride grafted polyolefins (for example, Exxellor VA1803). Styrenic block copolymers are copolymers of styrene with butadiene, isoprene, or a mixture of the two. Additional unsaturated monomers may be added to the structure of the styrenic block copolymer as needed for property modification of the resulting SBC/urethane copolymer. The styrenic block copolymer can be a diblock or a triblock styrenic polymer. Examples of such styrenic block copolymers are described in, for example, U.S. Pat. No. 5,436,295 to Nishikawa et al. The styrenic block copolymer can have any known molecular weight for such polymers, and it can possess a linear, branched, star, dendrimeric or combination molecular structure. The styrenic block copolymer can be unmodified by functional groups, or it can be modified by hydroxyl group, carboxyl group, or other functional groups, either in its chain structure or at one or more terminus. The styrenic block copolymer can be obtained using any common process for manufacture of such polymers. The styrenic block copolymers also may be hydrogenated using well-known methods to obtain a partially or fully saturated diene monomer block.
Other preferred materials suitable for use as additional polymers in the presently disclosed compositions include polyester thermoplastic elastomers marketed under the tradename SKYPEL™ by SK Chemicals of South Korea, or diblock or triblock copolymers marketed under the tradename SEPTON™ by Kuraray Corporation of Kurashiki, Japan, and KRATON™ by Kraton Polymers Group of Companies of Chester, United Kingdom. For example, SEPTON HG 252 is a triblock copolymer, which has polystyrene end blocks and a hydrogenated polyisoprene midblock and has hydroxyl groups at the end of the polystyrene blocks. HG-252 is commercially available from Kuraray America Inc. (Houston, Tex.).
A further example of a preferred materials suitable for use as additional polymers in the presently disclosed compositions is a specialty propylene elastomer as described, for example, in US 2007/0238552 A1, and incorporated herein by reference in its entirety. A specialty propylene elastomer includes a thermoplastic propylene-ethylene copolymer composed of a majority amount of propylene and a minority amount of ethylene. These copolymers have at least partial crystallinity due to adjacent isotactic propylene units. Although not bound by any theory, it is believed that the crystalline segments are physical crosslinking sites at room temperature, and at high temperature (i.e., about the melting point), the physical crosslinking is removed and the copolymer is easy to process. According to one embodiment, a specialty propylene elastomer includes at least about 50 mole % propylene co-monomer. Specialty propylene elastomers can also include functional groups such as maleic anhydride, glycidyl, hydroxyl, and/or carboxylic acid. Suitable specialty propylene elastomers include propylene-ethylene copolymers produced in the presence of a metallocene catalyst. More specific examples of specialty propylene elastomers are illustrated below. Specialty propylene elastomers are commercially available under the tradename VISTAMAXX from ExxonMobil Chemical.
An especially preferred component suitable for use as additional polymers in the presently disclosed compositions include the polyalkenamers. The term “polyalkenamer” is used interchangeably herein with the term “polyalkenamer rubber” and means a rubbery polymer of one or more cycloalkenes having from 4-20, ring carbon atoms. The polyalkenamers may be prepared by ring opening metathesis polymerization of one or more cycloalkenes in the presence of organometallic catalysts as described in U.S. Pat. Nos. 3,492,245, and 3,804,803, the entire contents of both of which are herein incorporated by reference.
The PHPB compositions used in the golf balls of the present invention may also comprise a synthetic rubber comprising an injection moldable polyalkenamer rubber. Examples of suitable polyalkenamer rubbers are polybutenamer rubber, polypentenamer rubber, polyhexenamer rubber, polyheptenamer rubber, polyoctenamer rubber, polynonenamer rubber, polydecenamer rubber polyundecenamer rubber, polydodecenamer rubber, polytridecenamer rubber. For further details concerning polyalkenamer rubber, see Rubber Chem. & Tech., Vol. 47, page 511-596, 1974, which is incorporated herein by reference. Polyoctenamer rubbers are commercially available from Huls AG of Marl, Germany, and through its distributor in the U.S., Creanova Inc. of Somerset, N.J., and sold under the trademark VESTENAMER®. Two grades of the VESTENAMER® trans-polyoctenamer are commercially available: VESTENAMER 8012 designates a material having a trans-content of approximately 80% (and a cis-content of 20%) with a melting point of approximately 54° C.; and VESTENAMER 6213 designates a material having a trans-content of approximately 60% (cis-content of 40%) with a melting point of approximately 30° C. Both of these polymers have a double bond at every eighth carbon atom in the ring.
The polyalkenamer rubbers used in the present disclosure exhibit excellent melt processability above their sharp melting temperatures and exhibit high miscibility with various rubber additives as a major component without deterioration of crystallinity which in turn facilitates injection molding. Thus, unlike synthetic polybutadiene rubbers typically used in golf ball core preparation, injection molded parts of polyalkenamer-based compounds can be prepared which, in addition, can also be partially or fully crosslinked at elevated temperature. The crosslinked polyalkenamer compounds are highly elastic, and their mechanical and physical properties can be easily modified by adjusting the formulation.
The polyalkenamer composition surprisingly exhibits superior characteristics over a broad spectrum of properties. For example, the compositions exhibit superior impact durability and Coefficient of Restitution (COR) in a pre-determined hardness range (e.g., a hardness Shore D of from about 15 to about 85, preferably from about 40 to about 80, and more preferably from about 40 to about 75. More particularly, the compositions disclosed herein exhibit excellent hardness adjustment without significantly compromising COR or processability.
The polyalkenamer rubbers may also be blended within other polymers. A more complete description of the various polyalkenamer rubber compositions and blends as used in the present invention are disclosed in U.S. Pat. No. 7,528,196 and copending US Pub. No. 2009/0191981A1, U.S. Pat. No. 7,874,940 and copending US Pub. No. 2010/0323818A1 and copending US Pub. No. 2010/0160079A1, all assigned to Taylor Made Golf Co. and all in the name of Hyun Kim at al., the entire contents of each of which are hereby incorporated by reference.
The polyalkenamer rubber preferably contains from about 50 to about 99, preferably from about 60 to about 99, more preferably from about 65 to about 99, even more preferably from about 70 to about 90 percent of its double bonds in the trans-configuration. The preferred form of the polyalkenamer has a trans content of approximately 80%, however, compounds having other ratios of the cis- and trans-isomeric forms of the polyalkenamer can also be obtained by blending available products for use in making the composition.
The polyalkenamer rubber has a molecular weight (as measured by GPC) from about 10,000 to about 300,000, preferably from about 20,000 to about 250,000, more preferably from about 30,000 to about 200,000, even more preferably from about 50,000 to about 150,000.
The polyalkenamer rubber has a degree of crystallization (as measured by DSC secondary fusion) from about 5 to about 70, preferably from about 6 to about 50, more preferably from about from 6.5 to about 50%, even more preferably from about from 7 to about 45%,
More preferably, the polyalkenamer rubber is a polymer prepared by polymerization of cyclooctene to form a trans-polyoctenamer rubber as a mixture of linear and cyclic macromolecules.
Prior to its use in golf balls, the polyalkenamer rubber or other synthetic rubber compositions used in the present invention may be further formulated with one or more of the previously described crosslinking reagents co-crosslinking reagents, peptizers and accelerators described above for use as a component of the crosslinking package for the PHPB.
Another especially preferred component for use as an additional polymer in the presently disclosed compositions include the carboxylated elastomers described in copending application Ser. No. 13/719,060 filed on December 18^th, 2012 in the name of Taylor Made Golf Co., the entire contents of which are herein incorporated by reference. The term carboxylated elastomer (CE) composition as used herein is intended to mean the family of polymers which are long chain elastomeric rubbers containing pendant carboxyl groups at random various points along the chain as may be graphically illustrated below:
The carboxylated elastomer comprises an elastomer backbone and carboxy pendant groups, wherein R may be a hydrogen, a metal (for example, an alkali metal, an alkaline earth metal, or a transition metal), an ammonium or a quaternary ammonium group, an acyl group (for example acetyl(CH₃C(O)) group), an alkyl group (such as an ester), an acid anhydride group, and combinations thereof; and R₁may be a hydrogen, an alkyl, or an aryl group. Although the pendant carboxy groups are depicted as being in interior positions along the elastomer backbone, the carboxylated elastomer may also include terminal carboxy groups occurring at one or more chain ends.
One method of introducing the carboxy groups is by copolymerization of a suitable olefin monomer with a monomer comprising a carboxy group. The first preparation of a carboxylic elastomer was recorded in 1933 and involved the copolymerization of butadiene and acrylic acid. Examples of suitable olefin monomers, include, but are not limited to, styrene, vinyltoluene, alpha-methylestyrene, butadiene, isoprene, hexadiene, dichlorovinylidene, vinylchloride, ethylene, propylene, butylene, and isobutylene. Examples of suitable monomers comprising a carboxy group include, but are not limited to, acrylic acid, alkyacrylate, alkyl alkacrylates, maleic anhydride, maleimide, acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid.
A preferred class of carboxylated elastomers for use in this invention are the carboxylated nitrile rubbers which may be any of those known in the art. These are copolymers of butadiene, acrylonitrile and one or more α,μ-unsaturated carboxylic acids and which have nitrile rubber as the elastomer backbone. A diagram of the backbone is shown below.
The carboxylic acids which are pendant to the above backbone may contain one or more carboxylic groups. Because of cost and availability, it is preferred that the carboxylic acids be selected from acrylic, methacrylic, fumaric, maleic and itaconic acids. The copolymers may be prepared by the well known emulsion free radical process. The acrylonitrile content of the copolymer may be from about 20 to about 40 percent by weight of the copolymer. The total content of carboxylic acid in the copolymer may be from about 0.5 to about 10 percent by weight of the copolymer. Butadiene forms the balance to 100 percent by weight of the copolymer. The viscosity of the copolymer is generally within the Mooney range (ML 1+4 at 100° C.) of from about 40 to about 80. U.S. Pat. Nos. 4,271,052 and 4,525,517 disclose carboxylated nitrile rubbers for use in this invention and such disclosures are incorporated herein by reference. There are a number of carboxylated elastomers that are commercially available from Noveon under the tradename HYCAR including HYCAR CTBN 1300X8 and CTBN 1300X8F which are a carboxyl terminated butadiene-acrylonitrile copolymers. HYCAR VTBNX 1300X33 which is a methacrylate terminated butadiene-acrylonitrile copolymer and HYCAR ATBN 1300X16 is an amine terminated butadiene-acrylonitrile.
Another method for introducing the carboxy groups into the particular elastomer backbone is by grafting carboxy groups onto an elastomer backbone. The elastomers may include styrene butadiene random and block copolymers, hydrogenated styrene butadiene random and block copolymers, acrylonitrile butadiene styrene (“ABS”) copolymers, ethylene-propylene-diene-monomer (EPDM) copolymers, styrene-acrylic copolymers, acrylonitrile butadiene rubber (NBR) polymers, methylmethacrylate butadiene styrene (MBS) rubbers, and styrene-acrynitrile rubbers. Carboxy groups may be grafted onto a hydrophobic particulate elastomer to form a suitable graft particulate elastomer using a variety of suitable carboxylating materials, including, but not limited to, maleic acid, maleic anhydride, and diesters and monoesters of maleic acid, maleimide, fumaric acid and its derivatives, acrylic acid, alkylacrylate, alkylalkacrylates, acrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid and its salts.
Examples of suitable graft particulate elastomers include, but are not limited to, maleated polybutadienes, maleated styrene butadiene rubbers (“SBR”), maleated acrylonitrile-styrene-butadiene (“ABS”) rubbers, maleated nitrile-butadiene rubbers (“NBR”), maleated hydrogenated acrylonitrile butadiene rubbers (“HNBR”), methylmethacrylate butadiene styrene (“MBS”) rubbers, carboxylated ethylene-propylene-diene monomer rubbers, carboxylated styrene-acrynitrile rubbers (“SAN”), carboxylated ethylene propylene diene rubbers (“EPDM”), acrylic grafted silicone rubbers, and combinations thereof. An example of a suitable hydrogenated acrylonitrile butadiene rubber (“HNBR”) that is grafted with carboxylating materials is available from Lanxess Corporation, Leverkusen, Germany, under the trade name THERBAN® XT. An example of a suitable nitrile-butadiene rubbers (“NBR”) that is grafted with carboxylating materials is available from Zeon Chemicals, L.P., Louisville, Ky., under the trade name NIPOL® NBR 1072 CGX. Examples of suitable butadiene based rubbers that are grafted with carboxylating materials are available from Mitsubishi Rayon Company Ltd., Tokyo, Japan, under the trade names METABLENS® C and E. An example of an acrylic rubber that is grafted with carboxylating materials is available from Mitsubishi Rayon Company Limited, Tokyo, Japan, under the trade name METABLEN® W. An example of a suitable silicone based elastomer that is grafted with carboxylating materials is available from Mitsubishi Rayon America Inc., New York, N.Y., under the trade name METABLEN® S. An example of a suitable styrene butadiene particulate elastomer grafted with maleic acid available as an experimental product (Eliokem XPR-100) from Eliokem Corporation.
Most preferred are the grafted polyisoprene compounds including Kurary LIR403 which is a polyisoprene-graft-maleic anhydride having the following chemical structure:
Also included is Kurary LIR410 which is a polyisoprene-graft-maleic anhydride monoester of maleic anhydride having the following chemical structure:
where n is approximately 10, and the material has a weight average molecular weight of about 25,000, and a glass transition temperature of −59° C.
In addition to using directly or in blends with the PHPB to prepare the golf ball components of the present invention, the polyalkenamers or CE compositions may be crosslinked before or after forming into the desired golf ball part. When used in a blend with the PHPB, the crosslinking of each component may occur before or after the blending step. In view of the unsaturation and the pendant carboxylate functionality of the CE's, there are a number of available cross linking mechanisms which may be utilized. Given the unsaturation present in the elastomer backbone the polyalkenamer and CE compositions are also amenable to the various methods used to crosslink elastomeric rubber compositions including vulcanization, and radiation crosslinking using the same crosslinking packages as disclosed above for the PHPB component. Radiation can be applied to the unsaturated polymer mixture by any known method, including using microwave or gamma radiation, or an electron beam device. Additives may also be used to improve radiation curing of the diene polymer. Also given the pendant carboxylate functionality of the CE's they are also amenable to the crosslinking mechanisms typically invoked in ionomers via neutralization and subsequent metal ion clustering.
If a given layer in a golf ball is not the one or more comprising the PHPB composition, the cover layer and/or one or more inner cover layers of the golf ball may comprise one or more thermoplastic or thermoset polyurethanes or polyureas. Polyurethanes or polyureas typically are prepared by reacting a diisocyanate with a polyol (in the case of polyurethanes) or with a polyamine (in the case of a polyurea). Thermoplastic polyurethanes or polyureas may consist solely of this initial mixture or may be further combined with a chain extender to vary properties such as hardness of the thermoplastic. Thermoset polyurethanes or polyureas typically are formed by the reaction of a diisocyanate and a polyol or polyamine respectively, and an additional crosslinking agent to crosslink or cure the material to result in a thermoset.
In what is known as a one-shot process, the three reactants, diisocyanate, polyol or polyamine, and optionally a chain extender or a curing agent, are combined in one step. Alternatively, a two-step process may occur in which the first step involves reacting the diisocyanate and the polyol (in the case of polyurethane) or the polyamine (in the case of a polyurea) to form a so-called prepolymer, to which can then be added either the chain extender or the curing agent. This procedure is known as the prepolymer process.
In addition, although depicted as discrete component packages as above, it is also possible to control the degree of crosslinking, and hence the degree of thermoplastic or thermoset properties in a final composition, by varying the stoichiometry not only of the diisocyanate-to-chain extender or curing agent ratio, but also the initial diisocyanate-to-polyol or polyamine ratio. Of course in the prepolymer process, the initial diisocyanate-to-polyol or polyamine ratio is fixed on selection of the required prepolymer.
Finally, in addition to discrete thermoplastic or thermoset materials, it also is possible to modify a thermoplastic polyurethane or polyurea composition by introducing materials in the composition that undergo subsequent curing after molding the thermoplastic to provide properties similar to those of a thermoset. For example, Kim in U.S. Pat. No. 6,924,337, the entire contents of which are hereby incorporated by reference, discloses a thermoplastic urethane or urea composition optionally comprising chain extenders and further comprising a peroxide or peroxide mixture, which can then undergo post curing to result in a thermoset.
Also, Kim et al. in U.S. Pat. No. 6,939,924, the entire contents of which are hereby incorporated by reference, discloses a thermoplastic urethane or urea composition, optionally also comprising chain extenders, that is prepared from a diisocyanate and a modified or blocked diisocyanate which unblocks and induces further cross linking post extrusion. The modified isocyanate preferably is selected from the group consisting of: isophorone diisocyanate (IPDI)-based uretdione-type crosslinker; a combination of a uretdione adduct of IPDI and a partially e-caprolactam-modified IPDI; a combination of isocyanate adducts modified by e-caprolactam and a carboxylic acid functional group; a caprolactam-modified Desmodur diisocyanate; a Desmodur diisocyanate having a 3,5-dimethylpyrazole modified isocyanate; or mixtures of these.
Finally, Kim et al. in U.S. Pat. No. 7,037,985 B2, the entire contents of which are hereby incorporated by reference, discloses thermoplastic urethane or urea compositions further comprising a reaction product of a nitroso compound and a diisocyanate or a polyisocyanate. The nitroso reaction product has a characteristic temperature at which it decomposes to regenerate the nitroso compound and diisocyanate or polyisocyanate. Thus, by judicious choice of the post-processing temperature, further crosslinking can be induced in the originally thermoplastic composition to provide thermoset-like properties.
In view of the advantages of injection molding versus the more complex casting process, under some circumstances it is advantageous to have formulations capable of curing as a thermoset but only within a specified temperature range above that of the typical injection molding process. This allows parts, such as golf ball cover layers, to be initially injection molded, followed by subsequent processing at higher temperatures and pressures to induce further crosslinking and curing, resulting in thermoset properties in the final part. Such an initially injection moldable composition is thus called a post curable urethane or urea composition.
If a post curable urethane composition is required, a modified or blocked diisocyanate which subsequently unblocks and induces further cross linking post extrusion may be included in the diisocyanate starting material. Modified isocyanates used for making the polyurethanes of the present invention generally are defined as chemical compounds containing isocyanate groups that are not reactive at room temperature, but that become reactive once they reach a characteristic temperature. The resulting isocyanates can act as crosslinking agents or chain extenders to form crosslinked polyurethanes. The degree of crosslinking is governed by type and concentration of modified isocyanate presented in the composition. The modified isocyanate used in the composition preferably is selected, in part, to have a characteristic temperature sufficiently high such that the urethane in the composition will retain its thermoplastic behavior during initial processing (such as injection molding). If a characteristic temperature is too low, the composition crosslinks before processing is completed, leading to process difficulties. The modified isocyanate preferably is selected from isophorone diisocyanate (IPDI)-based uretdione-type crosslinker; a combination of a uretdione adduct of IPDI and a partially e-caprolactam-modified IPDI; a combination of isocyanate adducts modified by e-caprolactam and a carboxylic acid functional group; a caprolactam-modified Desmodur diisocyanate; a Desmodur diisocyanate having a 3,5-dimethylpyrazole modified isocyanate; or mixtures of these. Particular preferred examples of modified isocyanates include those marketed under the trade name CRELAN by Bayer Corporation. Examples of these include: CRELAN TP LS 2147; CRELAN NI 2; isophorone diisocyanate (IPDI)-based uretdione-type crosslinker, such as CRELAN VP LS 2347; a combination of a uretdione adduct of IPDI and a partially e-caprolactam-modified IPDI, such as CRELAN VP LS 2386; a combination of isocyanate adducts modified by e-caprolactam and a carboxylic acid functional group, such as CRELAN VP LS 2181/1; a caprolactam-modified Desmodur diisocyanate, such as CRELAN NW5; and a Desmodur diisocyanate having a 3,5-dimethylpyrazole modified isocyanate, such as CRELAN XP 7180. These modified isocyanates may be used either alone or in combination. Such modified diisocyanates are described in more detail in U.S. Pat. No. 6,939,924, the entire contents of which are hereby incorporated by reference.
As an alternative if a post curable polyurethane or polyurea composition is required, the diisocyanate may further comprise reaction product of a nitroso compound and a diisocyanate or a polyisocyanate. The reaction product has a characteristic temperature at which it decomposes regenerating the nitroso compound and diisocyanate or polyisocyanate, which can, by judicious choice of the post processing temperature, in turn induce further crosslinking in the originally thermoplastic composition resulting in thermoset-like properties. Such nitroso compounds are described in more detail in U.S. Pat. No. 7,037,985 B2, the entire contents of which are hereby incorporated by reference.
If a given layer in a golf ball is not the one or more comprising the PHPB composition, the cover layer and/or one or more inner cover layers of the golf ball may comprise one or more ionomer resins. One family of such resins was developed in the mid-1960's, by E.I. DuPont de Nemours and Co., and sold under the trademark SURLYN®. Preparation of such ionomers is well known, for example see U.S. Pat. No. 3,264,272. Generally speaking, most commercial ionomers are unimodal and consist of a polymer of a mono-olefin, e.g., an alkene, with an unsaturated mono- or dicarboxylic acids having 3 to 12 carbon atoms. An additional monomer in the form of a mono- or dicarboxylic acid ester may also be incorporated in the formulation as a so-called “softening comonomer”. The incorporated carboxylic acid groups are then neutralized by a basic metal ion salt, to form the ionomer. The metal cations of the basic metal ion salt used for neutralization include Li⁺, Na⁺, K⁺, Zn²⁺, Ca²⁺, Co²⁺, Ni²⁺, Cu²⁺, Pb²⁺, and Mg²⁺, with the Li⁺, Na⁺, Ca²⁺, Zn²⁺, and Mg²⁺ being preferred. The basic metal ion salts include those of for example formic acid, acetic acid, nitric acid, and carbonic acid, hydrogen carbonate salts, oxides, hydroxides, and alkoxides.
Today, there are a wide variety of commercially available ionomer resins based both on copolymers of ethylene and (meth)acrylic acid or terpolymers of ethylene and (meth)acrylic acid and (meth)acrylate, all of which can be used as a golf ball component. The properties of these ionomer resins can vary widely due to variations in acid content, softening comonomer content, the degree of neutralization, and the type of metal ion used in the neutralization. The full range commercially available typically includes ionomers of polymers of general formula, E/X/Y polymer, wherein E is ethylene, X is a C₃to C₈α,β ethylenically unsaturated carboxylic acid, such as acrylic or methacrylic acid, and is present in an amount from about 0 wt. % to about 50 wt. %, particularly about 2 to about 30 weight %, of the E/X/Y copolymer, and Y is a softening comonomer selected from the group consisting of alkyl acrylate and alkyl methacrylate, such as methyl acrylate or methyl methacrylate, and wherein the alkyl groups have from 1-8 carbon atoms, Y is in the range of 0 to about 50 weight %, particularly about 5 wt. % to about 35 wt. %, of the E/X/Y copolymer, and wherein the acid groups present in said ionomeric polymer are partially (e.g., about 1% to about 90%) neutralized with a metal selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc or aluminum, or a combination of such cations.
The ionomer may also be a so-called bimodal ionomer as described in U.S. Pat. No. 6,562,906 (the entire contents of which are herein incorporated by reference). These ionomers are bimodal as they are prepared from blends comprising polymers of different molecular weights. Specifically they include bimodal polymer blend compositions comprising:

- a) a high molecular weight component having a molecular weight of about 80,000 to about 500,000 and comprising one or more ethylene/α,β-ethylenically unsaturated C_3-8carboxylic acid copolymers and/or one or more ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said high molecular weight component being partially neutralized with metal ions selected from the group consisting of lithium, sodium, zinc, calcium, magnesium, and a mixture of any these; and
- b) a low molecular weight component having a molecular weight of about from about 2,000 to about 30,000 and comprising one or more ethylene/α,β-ethylenically unsaturated C_3-8carboxylic acid copolymers and/or one or more ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said low molecular weight component being partially neutralized with metal ions selected from the group consisting of lithium, sodium, zinc, calcium, magnesium, and a mixture of any these.

In addition to the unimodal and bimodal ionomers, also included are the so-called “modified ionomers” examples of which are described in U.S. Pat. Nos. 6,100,321, 6,329,458 and 6,616,552 and U.S. Patent Publication No. US 2003/0158312 A1, the entire contents of all of which are herein incorporated by reference.
The modified unimodal ionomers may be prepared by mixing:

- a) an ionomeric polymer comprising ethylene, from 5 to 25 weight percent (meth)acrylic acid, and from 0 to 40 weight percent of a (meth)acrylate monomer, said ionomeric polymer neutralized with metal ions selected from the group consisting of lithium, sodium, zinc, calcium, magnesium, and a mixture of any of these; and
- b) from about 5 to about 40 weight percent (based on the total weight of said modified ionomeric polymer) of one or more fatty acids or metal salts of said fatty acid, the metal selected from the group consisting of calcium, sodium, zinc, potassium, and lithium, barium and magnesium and the fatty acid preferably being stearic acid.

The modified bimodal ionomers, which are ionomers derived from the earlier described bimodal ethylene/carboxylic acid polymers (as described in U.S. Pat. No. 6,562,906, the entire contents of which are herein incorporated by reference), are prepared by mixing;

- a) a high molecular weight component having a weight average molecular weight (Mw) of about 80,000 to about 500,000 and comprising one or more ethylene/α,β-ethylenically unsaturated C_3-8carboxylic acid copolymers and/or one or more ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said high molecular weight component being partially neutralized with metal ions selected from the group consisting of lithium, sodium, zinc, calcium, potassium, magnesium, and a mixture of any of these; and
- b) a low molecular weight component having a weight average molecular weight (Mw) of about from about 2,000 to about 30,000 and comprising one or more ethylene/α,β-ethylenically unsaturated C_3-8carboxylic acid copolymers and/or one or more ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said low molecular weight component being partially neutralized with metal ions selected from the group consisting of lithium, sodium, zinc, calcium, potassium, magnesium, and a mixture of any of these; and
- c) from about 5 to about 40 weight percent (based on the total weight of said modified ionomeric polymer) of one or more fatty acids or metal salts of said fatty acid, the metal selected from the group consisting of calcium, sodium, zinc, potassium and lithium, barium and magnesium and the fatty acid preferably being stearic acid.

The fatty or waxy acid salts utilized in the various modified ionomers are composed of a chain of alkyl groups containing from about 4 to 75 carbon atoms (usually even numbered) and characterized by a —COOH terminal group. The generic formula for all fatty and waxy acids above acetic acid is CH₃(CH₂)_XCOOH, wherein the carbon atom count includes the carboxyl group. The fatty or waxy acids utilized to produce the fatty or waxy acid salts modifiers may be saturated or unsaturated, and they may be present in solid, semi-solid or liquid form.
Examples of suitable saturated fatty acids, i.e., fatty acids in which the carbon atoms of the alkyl chain are connected by single bonds, include but are not limited to stearic acid (C₁₈, i.e., CH₃(CH₂)₁₆COOH), palmitic acid (C₁₆, i.e., CH₃(CH₂)₁₄COOH), pelargonic acid (C₉, i.e., CH₃(CH₂)₇COOH) and lauric acid (C₁₂, i.e., CH₃(CH₂)₁₀OCOOH). Examples of suitable unsaturated fatty acids, i.e., a fatty acid in which there are one or more double bonds between the carbon atoms in the alkyl chain, include but are not limited to oleic acid (C₁₃, i.e., CH₃(CH₂)₇CH:CH(CH₂)₇COOH).
The source of the metal ions used to produce the metal salts of the fatty or waxy acid salts used in the various modified ionomers are generally various metal salts which provide the metal ions capable of neutralizing, to various extents, the carboxylic acid groups of the fatty acids. These include the sulfate, carbonate, acetate and hydroxylate salts of zinc, barium, calcium and magnesium.
Since the fatty acid salts modifiers comprise various combinations of fatty acids neutralized with a large number of different metal ions, several different types of fatty acid salts may be utilized in the invention, including metal stearates, laureates, oleates, and palmitates, with calcium, zinc, sodium, lithium, potassium and magnesium stearate being preferred, and calcium and sodium stearate being most preferred.
The fatty or waxy acid or metal salt of said fatty or waxy acid is present in the modified ionomeric polymers in an amount of from about 5 to about 40, preferably from about 7 to about 35, more preferably from about 8 to about 20 weight percent (based on the total weight of said modified ionomeric polymer).
As a result of the addition of the one or more metal salts of a fatty or waxy acid, from about 40 to 100, preferably from about 50 to 100, more preferably from about 70 to 100 percent of the acidic groups in the final modified ionomeric polymer composition are neutralized by a metal ion. An example of such a modified ionomer polymer is DuPont® HPF-1000 available from E. I. DuPont de Nemours and Co. Inc.
If a given layer in a golf ball is not the one or more comprising the PHPB composition, the cover layer and/or one or more inner cover layers of the golf ball may comprise a blend of an ionomer and a block copolymer. An example of a block copolymer is a functionalized styrenic block copolymer, the block copolymer incorporating a first polymer block having an aromatic vinyl compound, a second polymer block having a conjugated diene compound in which the ratio of block copolymer to ionomer ranges from 5:95 to 95:5 by weight, more preferably from about 10:90 to about 90:10 by weight, more preferably from about 20:80 to about 80:20 by weight, more preferably from about 30:70 to about 70:30 by weight and most preferably from about 35:65 to about 65:35 by weight. A preferred block copolymer is SEPTON HG-252. Such blends are described in more detail in commonly-assigned U.S. Pat. No. 6,861,474 and U.S. Patent Publication No. 2003/0224871 both of which are incorporated herein by reference in their entireties.
Another preferred material to which the PHPB may be added and which also may be used as a separate component of the cover layer or intermediate layer of the golf balls of the present invention is a multi-component blend composition (“MCBC”) prepared by blending together at least three materials, identified as Components A, B, and C, and melt-processing these components to form in-situ, a polymer blend composition incorporating a pseudo-crosslinked polymer network. Such blends are more fully described in U.S. Pat. No. 6,930,150 to H. J. Kim, the entire contents of which are hereby incorporated by reference.
The first of these blend components (blend Component A) include block copolymers including di and triblock copolymers, incorporating a first polymer block having an aromatic vinyl compound, and a second polymer block having an olefinic and/or conjugated diene compound. Preferred aromatic vinyl compounds include styrene, α-methylstyrene, o-, m- or p-methylstyrene, 4-propylstyrene, 1,3-dimethylstyrene, vinylnaphthalene and vinylanthracene. In particular, styrene and α-methylstyrene are preferred. These aromatic vinyl compounds can each be used alone, or can be used in combination of two or more kinds. The aromatic vinyl compound is preferably contained in the block copolymer (b) in an amount of from 5 to 75% by weight, and more preferably from 10 to 65% by weight.
The conjugated diene compound, that constitutes the polymer block B in the block copolymer (b), includes, e.g., 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene. In particular, isoprene and 1,3-butadiene are preferred. These conjugated diene compounds can each be used alone, or can be used in combination of two or more kinds.
Preferred block copolymers include the styrenic block copolymers such as styrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene, (SEBS) and styrene-ethylene-propylene-styrene (SEPS). Commercial examples include SEPTON marketed by Kuraray Company of Kurashiki, Japan; TOPRENE by Kumho Petrochemical Co., Ltd and KRATON marketed by Kraton Polymers.
Also included are functionalized styrenic block copolymers, including those where the block copolymer incorporates a first polymer block having an aromatic vinyl compound, a second polymer block having a conjugated diene compound and a hydroxyl group located at a block copolymer, or its hydrogenation product. A preferred functionalized styrenic block copolymer is SEPTON HG-252.
The second blend component, Component B, is an acidic polymer that incorporates at least one type of an acidic functional group. Examples of such polymers suitable for use as include, but are not limited to, ethylene/(meth)acrylic acid copolymers and ethylene/(meth)acrylic acid/alkyl(meth)acrylate terpolymers, or ethylene and/or propylene maleic anhydride copolymers and terpolymers. Examples of such polymers which are commercially available include, but are not limited to, the Escor® 5000, 5001, 5020, 5050, 5070, 5100, 5110 and 5200 series of ethylene-acrylic acid copolymers sold by Exxon Mobil, the PRIMACOR® 1321, 1410, 1410-XT, 1420, 1430, 2912, 3150, 3330, 3340, 3440, 3460, 4311, 4608 and 5980 series of ethylene-acrylic acid copolymers sold by The Dow Chemical Company, Midland, Mich. and the ethylene-methacrylic acid copolymers such as Nucrel 599, 699, 0903, 0910, 925, 960, 2806, and 2906 commercially available from DuPont
Also included are the so called bimodal ethylene/carboxylic acid polymers as described in U.S. Pat. No. 6,562,906, the contents of which are incorporated herein by reference. These polymers comprise a first component comprising an ethylene/α,β-ethylenically unsaturated C_3-8carboxylic acid high copolymer, particularly ethylene(meth)acrylic acid copolymers and ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers, having a weight average molecular weight, Mw, of about 80,000 to about 500,000, and a second component comprising an ethylene/α,β-ethylenically unsaturated C_3-8carboxylic acid copolymers, particularly ethylene/(meth)acrylic acid copolymers having weight average molecular weight, Mw, of about 2,000 to about 30,000.
Component C is a base capable of neutralizing the acidic functional group of Component B and typically is a base having a metal cation. These metals are from groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB and VIIIB of the periodic table. Examples of these metals include lithium, sodium, magnesium, aluminum, potassium, calcium, manganese, tungsten, titanium, iron, cobalt, nickel, hafnium, copper, zinc, barium, zirconium, and tin. Suitable metal compounds for use as a source of Component C are, for example, metal salts, preferably metal hydroxides, metal oxides, metal carbonates, metal acetates, metal stearates, metal laureates, metal oleates, metal palmitates and the like.
The MCBC composition preferably is prepared by mixing the above materials into each other thoroughly, either by using a dispersive mixing mechanism, a distributive mixing mechanism, or a combination of these. These mixing methods are well known in the manufacture of polymer blends. As a result of this mixing, the acidic functional group of Component B is dispersed evenly throughout the mixture in either their neutralized or non-neutralized state. Most preferably, Components A and B are melt-mixed together without Component C, with or without the premixing discussed above, to produce a melt-mixture of the two components. Then, Component C separately is mixed into the blend of Components A and B. This mixture is melt-mixed to produce the reaction product. This two-step mixing can be performed in a single process, such as, for example, an extrusion process using a proper barrel length or screw configuration, along with a multiple feeding system.
The PHPB and the various other polymer compositions used to prepare core, mantle or outer cove layers of the golf balls of the present invention may also incorporate one or more fillers. Such fillers are typically in a finely divided form, for example, in a size generally less than about 20 mesh, preferably less than about 100 mesh U.S. standard size, except for fibers and flock, which are generally elongated. Flock and fiber sizes should be small enough to facilitate processing. Filler particle size will depend upon desired effect, cost, ease of addition, and dusting considerations. The appropriate amounts of filler required will vary depending on the application but typically can be readily determined without undue experimentation.
The filler preferably is selected from the group consisting of precipitated hydrated silica, limestone, clay, talc, asbestos, barytes, glass fibers, aramid fibers, mica, calcium metasilicate, barium sulfate, zinc sulfide, lithopone, silicates, silicon carbide, diatomaceous earth, carbonates such as calcium or magnesium or barium carbonate, sulfates such as calcium or magnesium or barium sulfate, metals, including tungsten steel copper, cobalt or iron, metal alloys, tungsten carbide, metal oxides, metal stearates, and other particulate carbonaceous materials, and any and all combinations thereof. Preferred examples of fillers include metal oxides, such as zinc oxide and magnesium oxide. In another preferred embodiment the filler comprises a continuous or non-continuous fiber.
In another preferred embodiment the filler comprises one or more so called nanofillers, as described in U.S. Pat. No. 6,794,447 and copending U.S. Publication No. US2004-0092336 filed on Sep. 24, 2003 and U.S. Pat. No. 7,332,533 filed on Aug. 25, 2004, the entire contents of each of which are incorporated herein by reference. Examples of commercial nanofillers are various Cloisite grades including 10A, 15A, 20A, 25A, 30B, and NA+ of Southern Clay Products (Gonzales, Tex.) and the Nanomer grades including 1.24TL and C.30EVA of Nanocor, Inc. (Arlington Heights, Ill.).
Materials incorporating nanofiller materials can provide these property improvements at much lower densities than those incorporating conventional fillers. For example, a nylon-6 nanocomposite material manufactured by RTP Corporation of Wichita, Kans. uses a 3% to 5% clay loading and has a tensile strength of 11,800 psi and a specific gravity of 1.14, while a conventional 30% mineral-filled material has a tensile strength of 8,000 psi and a specific gravity of 1.36. Because use of nanocomposite materials with lower loadings of inorganic materials than conventional fillers provides the same properties, this use allows products to be lighter than those with conventional fillers, while maintaining those same properties.
As used herein, a “nanocomposite” is defined as a polymer matrix having nanofiller intercalated or exfoliated within the matrix. Physical properties of the polymer will change with the addition of nanofiller and the physical properties of the polymer are expected to improve even more as the nanofiller is dispersed into the polymer matrix to form a nanocomposite.
Nanocomposite materials are materials incorporating from about 0.1% to about 20%, preferably from about 0.1% to about 15%, and most preferably from about 0.1% to about 10% of nanofiller reacted into and substantially dispersed through intercalation or exfoliation into the structure of an organic material, such as a polymer, to provide strength, temperature resistance, and other property improvements to the resulting composite. Descriptions of particular nanocomposite materials and their manufacture can be found in U.S. Pat. No. 5,962,553 to Ellsworth, U.S. Pat. No. 5,385,776 to Maxfield et al., and U.S. Pat. No. 4,894,411 to Okada et al. Examples of nanocomposite materials currently marketed include M1030D, manufactured by Unitika Limited, of Osaka, Japan, and 1015C2, manufactured by UBE America of New York, N.Y.
Preferably the nanofiller material is added to the polymeric composition in an amount of from about 0.1% to about 20%, preferably from about 0.1% to about 15%, and most preferably from about 0.1% to about 10% by weight of nanofiller reacted into and substantially dispersed through intercalation or exfoliation into the structure of the polymeric composition.
If desired, the various polymer compositions used to prepare the golf balls can additionally contain other additives such as plasticizers, pigments, antioxidants, U.V. absorbers, optical brighteners, or any other additives generally employed in plastics formulation or the preparation of golf balls.
Another particularly well-suited additive for use in the presently disclosed compositions includes compounds having the general formula:
(R₂N)_m—R′—(X(O)_nOR_y)_m,
where R is hydrogen, or a C1-C20 aliphatic, cycloaliphatic or aromatic systems; R′ is a bridging group comprising one or more C₁-C₂₀straight chain or branched aliphatic or alicyclic groups, or substituted straight chain or branched aliphatic or alicyclic groups, or aromatic group, or an oligomer of up to 12 repeating units including, but not limited to, polypeptides derived from an amino acid sequence of up to 12 amino acids; and X is C or S or P with the proviso that when X=C, n=1 and y=1 and when X=S, n=2 and y=1, and when X=P, n=2 and y=2. Also, m=1-3. These materials are more fully described in copending U.S. Provisional Patent Application No. 60/588,603, filed on Jul. 16, 2004, the entire contents of which are herein incorporated by reference. These materials include caprolactam, oenantholactam, decanolactam, undecanolactam, dodecanolactam, caproic 6-amino acid, 11-aminoundecanoicacid, 12-aminododecanoic acid, diamine hexamethylene salts of adipic acid, azeleic acid, sebacic acid and 1,12-dodecanoic acid and the diamine nonamethylene salt of adipic acid., 2-aminocinnamic acid, L-aspartic acid, 5-aminosalicylic acid, aminobutyric acid; aminocaproic acid; aminocapyryic acid; 1-(aminocarbonyl)-1-cyclopropanecarboxylic acid; aminocephalosporanic acid; aminobenzoic acid; aminochlorobenzoic acid; 2-(3-amino-4-chlorobenzoyl)benzoic acid; aminonaphtoic acid; aminonicotinic acid; aminonorbornanecarboxylic acid; aminoorotic acid; aminopenicillanic acid; aminopentenoic acid; (aminophenyl)butyric acid; aminophenyl propionic acid; aminophthalic acid; aminofolic acid; aminopyrazine carboxylic acid; aminopyrazole carboxylic acid; aminosalicylic acid; aminoterephthalic acid; aminovaleric acid; ammonium hydrogencitrate; anthranillic acid; aminobenzophenone carboxylic acid; aminosuccinamic acid, epsilon-caprolactam; omega-caprolactam, (carbamoylphenoxy)acetic acid, sodium salt; carbobenzyloxy aspartic acid; carbobenzyl glutamine; carbobenzyloxyglycine; 2-aminoethyl hydrogensulfate; aminonaphthalenesulfonic acid; aminotoluene sulfonic acid; 4,4′-methylene-bis-(cyclohexylamine)carbamate and ammonium carbamate.
Most preferably the material is selected from the group consisting of 4,4′-methylene-bis-(cyclohexylamine)carbamate (commercially available from R.T. Vanderbilt Co., Norwalk, Conn. under the tradename Diak® 4), 11-aminoundecanoicacid, 12-aminododecanoic acid, epsilon-caprolactam; omega-caprolactam, and any and all combinations thereof.
In an especially preferred embodiment a nanofiller additive component in the golf ball is surface modified with a compatibilizing agent comprising the earlier described compounds having the general formula:
(R₂N)_m—R′—(X(O)_nOR_y)_m,
A most preferred embodiment would be a filler comprising a nanofiller clay material surface modified with an amino acid including 12-aminododecanoic acid. Such fillers are available from Nanonocor Co. under the tradename Nanomer 1.24TL. Disclosed compositions have sufficient shear-cut resistance and excellent mechanical properties that make them suitable for making sports equipment, such as a recreation ball, a golf club or component thereof, such as a grip, shoes, glove, helmet, protective gears, bicycle, football, soccer, basketball, baseball, volley ball, hockey, ski, skate and the like.
In addition to the PHPB rubber, the cores of the golf balls of the present invention may include the traditional rubber components used in golf ball applications including, both natural and synthetic rubbers, such as cis-1,4-polybutadiene, trans-1,4-polybutadiene, 1,2-polybutadiene, cis-polyisoprene, trans-polyisoprene, polychloroprene, polybutylene, styrene-butadiene rubber, styrene-butadiene-styrene block copolymer and partially and fully hydrogenated equivalents, styrene-isoprene-styrene block copolymer and partially and fully hydrogenated equivalents, nitrile rubber, silicone rubber, and polyurethane, as well as mixtures of these. Polybutadiene rubbers, especially 1,4-polybutadiene rubbers containing at least 40 mol %, and more preferably 80 to 100 mol % of cis-1,4 bonds, are preferred because of their high rebound resilience, moldability, and high strength after vulcanization. The polybutadiene component may be synthesized by using rare earth-based catalysts, nickel-based catalysts, or cobalt-based catalysts, conventionally used in this field. Polybutadiene obtained by using lanthanum rare earth-based catalysts usually employ a combination of a lanthanum rare earth (atomic number of 57 to 71)-compound, but particularly preferred is a neodymium compound.
The 1,4-polybutadiene rubbers have a molecular weight distribution (Mw/Mn) of from about 1.2 to about 4.0, preferably from about 1.7 to about 3.7, even more preferably from about 2.0 to about 3.5, most preferably from about 2.2 to about 3.2. The polybutadiene rubbers have a Mooney viscosity (ML₁₊₄(100° C.)) of from about 20 to about 80, preferably from about 30 to about 70, even more preferably from about 30 to about 60, most preferably from about 35 to about 50. The term “Mooney viscosity” used herein refers in each case to an industrial index of viscosity as measured with a Mooney viscometer, which is a type of rotary plastometer (see JIS K6300). This value is represented by the symbol ML₁₊₄(100° C.), wherein “M” stands for Mooney viscosity, “L” stands for large rotor (L-type), “1+4” stands for a pre-heating time of 1 minute and a rotor rotation time of 4 minutes, and “100° C.” indicates that measurement was carried out at a temperature of 100° C. As readily appreciated by one skilled in the art, blends of polybutadiene rubbers may also be utilized in the golf balls of the present invention, such blends may be prepared with any mixture of rare earth-based catalysts, nickel-based catalysts, or cobalt-based catalysts derived materials, and from materials having different molecular weights, molecular weight distributions and Mooney viscosity.
The cores of the golf balls of the present invention may also include 1,2-polybutadienes having differing tacticity, all of which are suitable as unsaturated polymers for use in the presently disclosed compositions, are atactic 1,2-polybutadiene, isotactic 1,2-polybutadiene, and syndiotactic 1,2-polybutadiene. Syndiotactic 1,2-polybutadiene having crystallinity suitable for use as an unsaturated polymer in the presently disclosed compositions are polymerized from a 1,2-addition of butadiene. The presently disclosed golf balls may include syndiotactic 1,2-polybutadiene having crystallinity and greater than about 70% of 1,2-bonds, more preferably greater than about 80% of 1,2-bonds, and most preferably greater than about 90% of 1,2-bonds. Also, the 1,2-polybutadiene may have a mean molecular weight between about 10,000 and about 350,000, more preferably between about 50,000 and about 300,000, more preferably between about 80,000 and about 200,000, and most preferably between about 10,000 and about 150,000. Examples of suitable syndiotactic 1,2-polybutadienes having crystallinity suitable for use in golf balls are sold under the trade names RB810, RB820, and RB830 by JSR Corporation of Tokyo, Japan.
The cores of the golf balls of the present invention may also include the polyalkenamer rubbers as previously described herein and disclosed in U.S. Pat. No. 7,528,196 in the name of Hyun Kim et al., the entire contents of which are hereby incorporated by reference.
When synthetic rubbers such as the aforementioned polybutadienes or polyalkenamers and their blends are used in the golf balls of the present invention they may contain further materials typically often used in rubber formulations including crosslinking agents, co-crosslinking agents, peptizers and accelerators, all of which methods and amounts are described above for crosslinking the carboxylated elastomers.
Typically the golf ball core is made by mixing together the unsaturated polymer, cross-linking agents, and other additives with or without melting them. Dry blending equipment, such as a tumbler mixer, V blender, ribbon blender, or two-roll mill, can be used to mix the compositions. The golf ball core compositions can also be mixed using a mill, internal mixer such as a Banbury or Farrel continuous mixer, extruder or combinations of these, with or without application of thermal energy to produce melting. The various core components can be mixed together with the cross-linking agents, or each additive can be added in an appropriate sequence to the milled unsaturated polymer. In another method of manufacture the cross-linking agents and other components can be added to the unsaturated polymer as part of a concentrate using dry blending, roll milling, or melt mixing. If radiation is a cross-linking agent, then the mixture comprising the unsaturated polymer and other additives can be irradiated following mixing, during forming into a part such as the core of a ball, or after forming.
The resulting mixture can be subjected to, for example, a compression or injection molding process, to obtain solid spheres for the core. The polymer mixture is subjected to a molding cycle in which heat and pressure are applied while the mixture is confined within a mold. The cavity shape depends on the portion of the golf ball being formed. The compression and heat liberates free radicals by decomposing one or more peroxides, which initiate cross-linking. The temperature and duration of the molding cycle are selected based upon the type of peroxide and peptizer selected. The molding cycle may have a single step of molding the mixture at a single temperature for fixed time duration.
For example, a preferred mode of preparation for the cores used in the present invention is to first mix the core ingredients on a two-roll mill, to form slugs of approximately 30-40 g, and then compression-mold in a single step at a temperature between 150 to 180° C., for a time duration between 5 and 12 minutes.
The various core components may also be combined to form a golf ball by an injection molding process, which is also well known to one of ordinary skill in the art. The curing time depends on the various materials selected, and those of ordinary skill in the art will be readily able to adjust the curing time upward or downward based on the particular materials used and the discussion herein.
The various formulations for the intermediate layer and/or outer cover layer may be produced by any generally known method, such as dry blending, melt-mixing, or combination of those, to achieve a good dispersive mixing, distributive mixing, or both. Examples of melt-mixing are roll-mill; internal mixer, such as injection molding, single-screw extruder, twin-screw extruder; or any combination of those The feed to the injection mold may be blended manually or mechanically prior to the addition to the injection molder feed hopper. Finished golf balls may be prepared by initially positioning the solid, preformed core in an injection-molding cavity, followed by uniform injection of the intermediate layer and/or cover layer composition sequentially over the core. The cover formulations can be injection molded around the cores to produce golf balls of the required diameter.
Alternatively, the intermediate layers and/or outer cover layer may also be formed around the core by first forming half shells by injection molding followed by compression molding the half shells about the core to form the final ball.
The intermediate layers and/or outer cover layer may also be formed around the cores using compression molding. Cover materials for compression molding may also be extruded or blended resins or castable resins such as thermoset polyurethane or thermoset polyurea.
The polybutadiene to be hydrogenated to form the PHPB for use in the golf ball of the present invention may contain of from about 20 to about 80 preferably of from about 30 to about 70, and more preferably of from about 45 to about 65 mol percent trans 1,4-addition. The polybutadiene to be hydrogenated to form the PHPB for use in the golf ball of the present invention may contain of from about 10 to about 70, preferably of from about 20 to about 60, and more preferably of from about and about 25 to about 45 mole percent cis 1,4-addition. The remainder of the polymer is formed by 1,2-addition of the 1,3-butadiene to give the 1,2 vinyl content.
The weight average molecular weight of the polybutadiene to be hydrogenated to form the PHPB product is in the range of from about 50,000 to about 300,000, preferably of from about 75,000 to about 250,000, even more preferably of from about 90,000 to about 200,000.
The degree of hydrogenation of the PHPB is carried out to such a degree that of from about 25 to about 75, preferably of from about 30 to about 70, more preferably of from about 35 to about 65 and even more preferably of from about 40 to about 60% of the double bonds in the original polybutadiene have been hydrogenated and are thus saturated.
In one preferred aspect the PHPB or PHPB-containing blend material used in the present invention may be crosslinked using a composition comprising one or more peroxides in a total amount of from about 0.1 to about 5, preferably of from about 0.5 to about 3, and more preferably of from about 0.75 to about 1.5 pph based on the total weight of PHPB.
The crosslinking composition also comprises at least one zinc or magnesium salt of an unsaturated fatty acids having 3 to 8 carbon atoms selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, stearic acid, fumaric acid, palmitic acid and mixtures thereof present in an amount of from about less than about 150, preferably less than about 125, and more preferably less than about 100 pph and more preferably of from about 5 to about 100 pph based on the total weight of PHPB.
This mechanism is known as free radical crosslinking. When used in a blend composition the PHPB may be crosslinked by this crosslinking package before or after its incorporation into the blend composition
The PHPB compositions or PHPB-containing blend compositions used in the golf balls of the present invention may comprise from about 2 to about 100, preferably from about 5 to about 95 and more preferably from about 10 to about 90 and most preferably from about 20 to about 80 wt % of the PHPB and from about 0 to about 98, preferably from about 5 to about 95 and more preferably from about 10 to about 90 and most preferably from about 20 to about 80 wt % of one or more additional polymer components (all wt % based on the total weight of PHPB and additional polymer component(s)).
The PHPB or PHPB-containing blend material has a Melt Flow Index (MFI) of from about 1 to about 80, preferably of from about 4 to about 60, more preferably of from about 5 to about 50 and most preferably of from about 10 to about 30 g/10 min.
The PHPB or PHPB-containing blend material has a material hardness of from about 20 to about 90, preferably of from about 25 to about 85 more preferably of from about 30 to about 80 and most preferably of from about 35 to about 70 Shore D.
The PHPB or PHPB-containing blend material has a flex modulus of from about 1 to about 120, preferably of from about 2 to about 100, more preferably of from about 3 to about 90 and most preferably of from about 4 to about 70 kpsi.
The golf ball of the present invention comprises a core and may comprise from 0 to 6, preferably from 0 to 5, more preferably from about 1 to about 4, most preferably from about 1 to about 3 intermediate or mantle layer(s).
In one preferred aspect, the golf ball is a two-piece ball with the PHPB or PHPB-containing blend composition used in the outer cover layer.
In one preferred aspect, the golf ball is a multi-piece ball wherein the outer cover comprises the PHPB or PHPB-containing blend material described herein.
In one preferred aspect, the golf ball is a multi-piece ball having at least one intermediate or mantle layer which comprises the PHPB or PHPB-containing blend material described herein.
In another preferred aspect the golf ball is a three-piece ball with a unitary core and the outer cover layer comprises the PHPB or PHPB-containing blend material and the intermediate or mantle layer comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a four-piece ball with a unitary core and the outer cover layer comprises the PHPB or PHPB-containing blend material and one or both of the inner and outer intermediate layers comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a five-piece ball with a unitary core and the outer cover layer comprises the PHPB or PHPB-containing blend material and one or more of the three intermediate or mantle layers comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a six-piece ball with a unitary core and the outer cover layer comprises the PHPB or PHPB-containing blend material and one or more of the four intermediate or mantle layers comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a three-piece ball with the intermediate or mantle layer comprising the PHPB or PHPB-containing blend material and the outer cover layer comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a four-piece ball with a unitary core and one or both of the inner and outer intermediate layer comprises the PHPB or PHPB-containing blend material and the outer cover layer comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a five-piece ball with a unitary core and one or more of the three intermediate or mantle layers comprises the PHPB or PHPB-containing blend material and the outer cover layer comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
In another aspect the golf ball is a six-piece ball with a unitary core and the one or more of the four intermediate or mantle layers comprises the PHPB or PHPB-containing blend material and the outer cover layer comprises a block copolymer, an acidic polymer, a unimodal ionomer, a bimodal ionomer, a modified unimodal ionomer, a modified bimodal ionomer, a polyalkenamer, a polyamide, a thermoplastic or thermoset polyurethane or thermoplastic or thermoset polyurea, or a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B), and any and all combinations thereof.
The one or more intermediate layers of the golf balls may have a thickness of from about 0.010 to about 0.400, preferably from about 0.020 to about 0.200 and most preferably from about 0.030 to about 0.100 inches.
The one or more intermediate layers of the golf balls may also have a Shore D hardness as measured on the ball of greater than about 25, preferably greater than about 40, and most preferably greater than about 50 Shore D units.
The outer cover layer of the balls may have a thickness of from about 0.015 to about 0.100, preferably from about 0.020 to about 0.080, more preferably from about 0.025 to about 0.060 inches.
The outer cover layer the balls may also have a Shore D hardness as measured on the ball of from about 30 to about 75, preferably from 38 to about 68 and most preferably from about 40 to about 65.
The core of the balls also may have a PGA compression of less than about 140, preferably less than about 100, and most preferably less than about 90.
The various core layers (including the center) if present may each exhibit a different hardness. The difference between the center hardness and that of the next adjacent layer, as well as the difference in hardness between the various core layers may be greater than 2, preferably greater than 5, most preferably greater than 10 units of Shore D.
In one preferred aspect, the hardness of the center and each sequential layer increases progressively outwards from the center to outer core layer.
In another preferred aspect, the hardness of the center and each sequential layer decreases progressively inwards from the outer core layer to the center.
The core of the balls may have a diameter of from about 0.5 to about 1.62, preferably from about 0.7 to about 1.60, more preferably from about 0.9 to about 1.58, yet more preferably from about 1.20 to about 1.54, and even more preferably from about 1.40 to about 1.50 in.
More specifically, for a three piece golf ball consisting of a core, a mantle, and a cover, the diameter of the core is most preferably greater than or equal to 1.41 inches in diameter.
More specifically, for a four piece golf ball (consisting of a core, an inner mantle, an outer mantle, and a cover wherein the inner mantle is encased by an outer mantle) the diameter of the core is most preferably greater than or equal to 1.00 inches in diameter.
More specifically, for a five piece golf ball (consisting of an inner core, an outer core, an inner mantle, an outer mantle, and a cover wherein the inner core and inner mantle are encased by outer core and outer mantle, respectively) the diameter of the core is most preferably greater than or equal to 1.00 inches in diameter.
More specifically, for a six piece golf ball (consisting of an inner core, an intermediate core, an outer core, an inner mantle, an outer mantle, and a cover wherein the intermediate core and inner mantle are encased by outer core and outer mantle, respectively) the diameter of the core is most preferably greater than or equal to 1.00 inches in diameter.
More specifically, for a six piece golf ball (consisting of an inner core, an outer core, an inner mantle, an intermediate mantle, an outer mantle, and a cover wherein the intermediate core and inner mantle are encased by outer core and outer mantle, respectively) the diameter of the core is most preferably greater than or equal to 1.00 inches in diameter.
The COR of the golf balls may be greater than about 0.700, preferably greater than about 0.730, more preferably greater than 0.750, most preferably greater than 0.775, and especially greater than 0.800 at 125 ft/sec inbound velocity.
The shear cut resistance of the golf balls of the present invention is less than about 4, preferably less than about 3, even more preferably less than about 2.
These and other aspects of the present invention may be more fully understood by reference to the following examples. While these examples are meant to be illustrative of golf balls and golf ball components made according to the present invention, the present invention is not meant to be limited by the following examples.

EXAMPLES

The various test properties which may be used to measure the properties of the golf balls of the present invention are described below including any test methods as defined below.
Core or ball diameter may be determined by using standard linear calipers or size gauge.
Compression may be measured by applying a spring-loaded force to the golf ball center, golf ball core, or the golf ball to be examined, with a manual instrument (an “Atti gauge”) manufactured by the Atti Engineering Company of Union City, N.J. This machine, equipped with a Federal Dial Gauge, Model D81-C, employs a calibrated spring under a known load. The sphere to be tested is forced a distance of 0.2 inch (5 mm) against this spring. If the spring, in turn, compresses 0.2 inch, the compression is rated at 100; if the spring compresses 0.1 inch, the compression value is rated as 0. Thus more compressible, softer materials will have lower Atti gauge values than harder, less compressible materials. Compression measured with this instrument is also referred to as PGA compression. The approximate relationship that exists between Atti or PGA compression and Riehle compression can be expressed as:
(Atti or PGA compression)=(160−Riehle Compression).
Thus, a Riehle compression of 100 would be the same as an Atti compression of 60.
COR may be measured using a golf ball or golf ball subassembly, air cannon, and a stationary steel plate. The steel plate provides an impact surface weighing about 100 pounds or about 45 kilograms. A pair of ballistic light screens, which measure ball velocity, are spaced apart and located between the air cannon and the steel plate. The ball is fired from the air cannon toward the steel plate over a range of test velocities from 50 ft/s to 180 ft/sec (for the tests used herein the velocity was 125 ft/sec). As the ball travels toward the steel plate, it activates each light screen so that the time at each light screen is measured. This provides an incoming time period proportional to the ball's incoming velocity. The ball impacts the steel plate and rebounds though the light screens, which again measure the time period required to transit between the light screens. This provides an outgoing transit time period proportional to the ball's outgoing velocity. The coefficient of restitution can be calculated by the ratio of the outgoing transit time period to the incoming transit time period, COR=T_out/T_in.
A “Mooney” viscosity is a unit used to measure the plasticity of raw or unvulcanized rubber. The plasticity in a Mooney unit is equal to the torque, measured on an arbitrary scale, on a disk in a vessel that contains rubber at a temperature of 100° C. and rotates at two revolutions per minute. The measurement of Mooney viscosity is defined according to ASTM D-1646.
Shore D hardness may be measured in accordance with ASTM Test D2240.
Melt flow index (MFI, I2) may be measured in accordance with ASTM D-1238, Condition 230° C./2.16 kg.
Tensile Strength and Tensile Elongation were measured with ASTM D-638.
Flexural modulus and flexural strength were measured using ASTM standard D-790.
Shear cut resistance may be determined by examining the balls after they were impacted by a pitching wedge at controlled speed, classifying each numerically from 1 (excellent) to 5 (poor), and averaging the results for a given ball type. Three samples of each Example may be used for this testing. Each ball is hit twice, to collect two impact data points per ball. Then, each ball is assigned two numerical scores-one for each impact—from 1 (no visible damage) to 5 (substantial material displaced). These scores may be then averaged for each Example to produce the shear resistance numbers. These numbers may be then directly compared with the corresponding number for a commercially available ball, having a similar construction including the same core and mantle composition and cover thickness for comparison purposes.
Impact durability may be tested with an endurance test machine. The endurance test machine is designed to impart repetitive deformation to a golf ball similar to a driver impact. The test machine consists of an arm and impact plate or club face that both rotate to a speed that generates ball speeds of approximately 155-160 mph. Ball speed is measured with two light sensors located 15.5″ from impact location and are 11″ apart. The ball is stopped by a net and if a test sample is not cracked will continue to cycle through the machine for additional impacts. For golf balls, if zero failures occur through in excess of 100 impacts per ball than minimal field failures will occur. For layers adjacent to the outer cover, fewer impacts are required since the cover typically “protects” the inner components of the golf ball.
Golf ball Sound Pressure Level, S, in decibels (dB) and Frequency in hertz (Hz) may be measured by dropping the ball from a height of 113 in onto a marble (“starnet crystal pink”) stage of at least 12″ square and 4.25 inches in thickness. The sound of the resulting impact is captured by a microphone positioned at a fixed proximity of 12 inches, and at an angle of 30 degrees from horizontal, from the impact position and resolved by software transformation into an intensity in db and a frequency in Hz. Data collection is done as follows:
Microphone data is collected using a laptop PC with a sound card. An A-weighting filter is applied to the analog signal from the microphone. This signal is then digitally sampled at 44.1 KHz by the laptop data acquisition system for further processing and analysis. Data Analysis was done as follows:
The data analysis is split into two processes:
a. Time series analysis that generates the root mean square (rms) sound pressure level (SPL) for each ball impact sound.

- i. An rms SPL from a reference calibration signal is generated in the same manner as the ball data.
- ii. The overall SPL (in decibels) is calculated from the reference signal for each ball impact sound.
- iii. The median SPL is recorded based on 3 impact tests.

b. Spectral analyses for each ball impact sound

- i. Fourier and Autoregressive spectral estimation techniques are employed to create power spectra.
- ii. The frequencies (in cycles/sec−Hz) from highest level peaks representing the most active sound producing vibration modes of each ball are identified.

Analysis of the cis, trans and vinyl content and degree of hydrogenation was performed using either an FTIR method (and analysis of the absorption intensities at about 740 cm-1 for cis, about 967 cm-1 for trans and about 910 cm-1 for vinyl) or by 1H NMR.
The molecular weight (Mw) and Mw/Mn values for the PHPB compositions were determined by Gel Permeation Chromatography
In view of the many possible embodiments to which the principles of the disclosed compositions and methods, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting the scope of the invention.

Example 1

Synthesis of Partially Hydrogenated Butadiene Rubber

0.24 g of tetrahydrofuran and 4.4 mmol of n-butyl lithium were added to 2,400 g of cyclohexane in a 5 L-autoclave reactor. 400 g of a 1,3-butadiene monomer was added and kept for 60 minutes of polymerization. The active terminal of the living polymer thus obtained was deactivated with 2,6-di-tert-butyl-4-methylphenol added in the same mole as the polymerization initiator, n-butyl lithium. The polymer thus obtained was a polybutadiene rubber of which the 1,2-vinyl bond content of the butadiene unit was 11.9%, and the 1,4-trans content of the butadiene unit was 49.9%, and the 1,4 cis content of the butadiene unit was 38.2%, and the number average molecular weight was about 94,000. The molecular weight (Mw) and % cis, vinyl and trans content are summarized in Table 1.
In order to carry out the hydrogenation, 2,800 g of the polymer solution containing 400 g of the polybutadiene rubber was added to a 5 L-autoclave reactor and then heated to 70° C. 60 ml of a lithium hydride suspension (0.1M in cyclohexane) and 0.2 mmol of bis(cyclopentadienyl) titanium(IV) dichloride were added into the reactor so that the LiH/Ti mole ratio was 30/1. And the hydrogen gas was blown into the reactor. The hydrogenation was performed in the reactor with hydrogen pressure of 10 kgf/cm2 with stifling at 400 rpm. After the completion of the reaction, the reactor was cooled down with the pressure lowered to the ambient pressure. The catalyst was removed by washing with aqueous hydrochloric acid, and the polymer was recovered via steam stripping, under conditions typical for hydrogenated polymers
As also summarized in Table 1, 1H-NMR analysis of the hydrogenated polymer showed that 48% of the double bonds in the polybutadiene starting material was saturated after hydrogenation.

Example 2

Synthesis of Partially Hydrogenated Butadiene Rubber

0.24 g of tetrahydrofuran and 4.1 mmol of n-butyl lithium were added to 2,400 g of cyclohexane in a 5 L-autoclave reactor. 400 g of a 1,3-butadiene monomer was added and kept for 60 minutes of polymerization. The active terminal of the living polymer thus obtained was deactivated with 2,6-di-tert-butyl-4-methylphenol added in the same mole as the polymerization initiator, n-butyl lithium. The polymer thus obtained was a polybutadiene rubber of which the 1,2-vinyl bond content of the butadiene unit was 12.0%, and the 1,4-trans content of the butadiene unit was 49.7%, and the 1,4 cis content of the butadiene unit was 38.3%, and the number average molecular weight was about 105,000. The molecular weight (Mw) and % cis, vinyl and trans content are summarized in Table 1.
In order to carry out the hydrogenation, 2,800 g of the polymer solution containing 400 g of the polybutadiene rubber was added to a 5 L-autoclave reactor and then heated to 70° C. 60 ml of a lithium hydride suspension (0.1M in cyclohexane) and 0.2 mmol of bis(cyclopentadienyl) titanium(IV) dichloride were added into the reactor so that the LiH/Ti mole ratio was 30/1. And the hydrogen gas was blown into the reactor. The hydrogenation was performed in the reactor with hydrogen pressure of 10 kgf/cm2 with stifling at 400 rpm. After the completion of the reaction, the reactor was cooled down with the pressure lowered to the ambient pressure. The catalyst was removed by washing with aqueous hydrochloric acid, and the polymer was recovered via steam stripping, under conditions typical for hydrogenated polymers
As also summarized in Table 1, 1H-NMR analysis of the hydrogenated polymer showed that 47% of the double bonds in the polybutadiene starting material was saturated after hydrogenation.

Example 3

Synthesis of Partially Hydrogenated Butadiene Rubber

0.24 g of tetrahydrofuran and 3.5 mmol of n-butyl lithium were added to 2,400 g of cyclohexane in a 5 L-autoclave reactor. 400 g of a 1,3-butadiene monomer was added and kept for 60 minutes of polymerization. The active terminal of the living polymer thus obtained was deactivated with 2,6-di-tert-butyl-4-methylphenol added in the same mole as the polymerization initiator, n-butyl lithium. The polymer thus obtained was a polybutadiene rubber of which the 1,2-vinyl bond content of the butadiene unit was 12.2%, and the 1,4-trans content of the butadiene unit was 49.6%, and the 1,4 cis content of the butadiene unit was 38.2%, and the number average molecular weight was about 118,000. The molecular weight (Mw) and % cis, vinyl and trans content are summarized in Table 1.
In order to carry out the hydrogenation, 2,800 g of the polymer solution containing 400 g of the polybutadiene rubber was added to a 5 L-autoclave reactor and then heated to 70° C. 60 ml of a lithium hydride suspension (0.1M in cyclohexane) and 0.2 mmol of bis(cyclopentadienyl) titanium(IV) dichloride were added into the reactor so that the LiH/Ti mole ratio was 30/1. And the hydrogen gas was blown into the reactor. The hydrogenation was performed in the reactor with hydrogen pressure of 10 kgf/cm2 with stifling at 400 rpm. After the completion of the reaction, the reactor was cooled down with the pressure lowered to the ambient pressure. The catalyst was removed by washing with aqueous hydrochloric acid, and the polymer was recovered via steam stripping, under conditions typical for hydrogenated polymers
As also summarized in Table 1, 1H-NMR analysis of the hydrogenated polymer showed that 47% of the double bonds in the polybutadiene starting material was saturated after hydrogenation.

TABLE 1

Molecular weight (Mw), % Vinyl, % Trans content of
the Polybutadien Starting Material and Degree of Hydrogenation
of the Exemplified PHPB Compositions

	Ex. 1	Ex. 2	Ex3

Mw	94,000	105,000	118,000
1,2-Vinyl (%)	11.9	12.0	12.2
1,4-Trans (%)	49.9	49.7	49.6
1,4-Cis (%)	38.2	38.3	38.2
Hydrogenation	48%	47%	47%

Claims

What is claimed is:

1. A golf ball comprising;

I. a core;

II. one or more mantle layers; and

III. an outer cover layer, and

wherein one or more of said core, one more mantle layers or outer cover layer comprises a partially hydrogenated polybutadiene having a viscosity at 200° C. of less than about 5,000 Pa-sec and a storage modulus (G′) at 1 Hz and 25° C. of greater than about 1×10⁷dyn/cm².

2. The golf ball of claim 1 wherein said partially hydrogenated polybutadiene is prepared by hydrogenation of a polybutadiene containing of from about 20 to about 80 mol percent trans 1,4-addition, of from about 10 to about 70, preferably of from about 20 to about 60, and more preferably of from about and about 25 to about 45 mole percent cis 1,4-addition and a weight average molecular weight of from about 50,000 to 300,000 and wherein the hydrogenation results in a partially hydrogenated polybutadiene wherein of from about 25 to about 75, % of the double bonds in the original polybutadiene have been hydrogenated and are thus saturated.

3. The golf ball of claim 1 wherein said partially hydrogenate polybutadiene is crosslinked by a crosslinking composition comprising

i) one or more peroxides;

ii) a zinc or magnesium salt of an unsaturated fatty acids having 3 to 8 carbon atoms selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, stearic acid, fumaric acid, palmitic acid and mixtures thereof; and

iii) a peptizer selected from the group consisting of an organic sulfur compound, a metal salt of an organic sulfur compound, a non-metal salt of an organic sulfur compound, and any and all combinations thereof.

4. The golf ball of claim 1 wherein said partially hydrogenated polybutadiene further comprises an additional polymer component selected from the group consisting of;

A. one or more carboxylated elastomers selected from the group consisting of;

a) a copolymer selected from the group consisting of carboxyalted polybutadiene, carboxylated styrene-butadiene copolymer, carboxylated acrylonitrile-butadiene copolymer and mixtures thereof;

b) a grafted elastomer selected from the group consisting of maleated polybutadienes, maleated styrene butadiene rubbers (“SBR”), maleated acrylonitrile-styrene-butadiene (“ABS”) rubbers, maleated nitrile-butadiene rubbers (“NBR”), maleated hydrogenated acrylonitrile butadiene rubbers (“HNBR”), methylmethacrylate butadiene styrene (“MBS”) rubbers, carboxylated ethylene-propylene-diene monomer rubbers, carboxylated styrene-acrynitrile rubbers (“SAN”), carboxylated ethylene propylene diene rubbers (“EPDM”), acrylic grafted silicone rubbers, and combinations thereof; and

c) any and all combinations of i and ii;

B. a polyalkenamer rubber selected from the group consisting of polybutenamer rubber, polypentenamer rubber, polyhexenamer rubber, polyheptenamer rubber, polyoctenamer rubber, polynonenamer rubber, polydecenamer rubber polyundecenamer rubber, polydodecenamer rubber, polytridecenamer rubber and any and all combinations thereof; and

C. any and all combinations of A and B.

5. The golf ball of claim 3 wherein;

A. said carboxylated elastomer composition has;

i) a melt flow index (MFI) of from about 1 to about 80 g/10 min.;

ii) a material hardness of from about 20 to about 90 Shore D;

and

iii) a flex modulus of from about 1 to about 120 kpsi.; and comprises;

a) a carboxylated nitrile rubber which is a copolymer of butadiene, acrylonitrile and one or more α,μ-unsaturated carboxylic acids having an elastomer backbone having the following formula

and which is substituted by one or more carboxy groups selected from the group consisting of those derived from acrylic acid, methacrylic acid, fumaric, acid, maleic acid and itaconic acid; or

b) a grafted polyisoprene selected from the group consisting of

i) a polyisoprene-graft-maleic anhydride having the following chemical structure:

ii) a polyisoprene-graft-maleic anhydride monoester of maleic anhydride having the following chemical structure

and

iii) all mixtures of i and ii.

6. The golf ball of claim 3 wherein said carboxylated elastomer or said polyalkenamer is crosslinked by a crosslinking composition selected from the group consisting of;

a) one or more basic metal salts selected from the group consisting of metal formates, metal acetates, metal nitrates, metal carbonates, metal hydrogen carbonates, metal oxides, metal hydroxides, metal alkoxides, metal stearates and mixtures thereof;

b) a mixture comprising

i) one or more peroxides;

iii) a peptizer selected from the group consisting of an organic sulfur compound, a metal salt of an organic sulfur compound, a non-metal salt of an organic sulfur compound, and

c) any and all combinations of a) and b).

7. The golf ball of claim 1 wherein said core;

a) has a diameter of from about 0.5 to about 1.62 inches;

b) has a PGA compression of less than about 100; and

c) comprises a peptizer selected from the group consisting of an organic sulfur compound, a metal salt of an organic sulfur compound, a non-metal salt of an organic sulfur compound, and any and all combinations thereof.

8. The golf ball of claim 1 wherein said core;

a) has a diameter of from about 0.7 to about 1.60 in;

b) has a PGA compression of less than about 90; and

c) further comprises one or more core layers each exhibiting a different hardness wherein the difference in hardness between each core layer is greater than 5 units of Shore D.

9. The golf ball of claim 8 wherein the hardness of the core center and each sequential core layers increases progressively outwards from the center to the outer core layer.

10. The golf ball of claim 8 wherein the hardness of the core center and each sequential core layers decreases progressively outwards from the center to the outer core layer.

11. The golf ball of claim 1 wherein said cover composition comprises a polymer selected from the group consisting of

a) a thermoset polyurethane;

b) a thermoplastic polyurethane;

c) a thermoset polyurea;

d) a thermoplastic polyurea;

e) a multicomponent blend composition (“MCBC”), the MCBC comprising (A) a block copolymer; and (B) one or more acidic polymers; and (C) one or more basic metal salts present in an amount to neutralize at greater than or equal to about 30 percent of the acid groups of Component (B); and

f) any and all combinations thereof.