Recherche Images Maps Play YouTube Actualités Gmail Drive Plus »
Connexion
Les utilisateurs de lecteurs d'écran peuvent cliquer sur ce lien pour activer le mode d'accessibilité. Celui-ci propose les mêmes fonctionnalités principales, mais il est optimisé pour votre lecteur d'écran.

Brevets

  1. Recherche avancée dans les brevets
Numéro de publicationWO2000040305 A1
Type de publicationDemande
Numéro de demandePCT/US1999/031172
Date de publication13 juil. 2000
Date de dépôt29 déc. 1999
Date de priorité6 janv. 1999
Numéro de publicationPCT/1999/31172, PCT/US/1999/031172, PCT/US/1999/31172, PCT/US/99/031172, PCT/US/99/31172, PCT/US1999/031172, PCT/US1999/31172, PCT/US1999031172, PCT/US199931172, PCT/US99/031172, PCT/US99/31172, PCT/US99031172, PCT/US9931172, WO 0040305 A1, WO 0040305A1, WO 2000/040305 A1, WO 2000040305 A1, WO 2000040305A1, WO-A1-0040305, WO-A1-2000040305, WO0040305 A1, WO0040305A1, WO2000/040305A1, WO2000040305 A1, WO2000040305A1
InventeursHyun Kim, Dean A. Snell
DéposantTaylor Made Golf Company, Inc.
Exporter la citationBiBTeX, EndNote, RefMan
Liens externes:  Patentscope, Espacenet
Toughness-enhanced golf ball covers using organic compounds
WO 2000040305 A1
Résumé
A material for use in golf balls (1) comprising elastomeric base material with 1-40 phr of at least one toughness-enhancing polymer. Preferred base materials are elastomers of moderate hardness, preferably about 40 Shore D, such as Pebax 1205. Preferred toughness-enhancing polymers include polyolefins, preferably terpolymers of ethylene, acrylic esters and maleic anhydride. Golf ball (1) having cover (2) made of the composition of the present invention have improved rheological and mechanical properties and improved durability during repeated hitting.
Revendications  (Le texte OCR peut contenir des erreurs.)
WHAT IS CLAIMED IS:
1. A golf ball cover or mantle, comprising a composition formed into said golf ball cover or mantle, said composition comprising:
100 parts by weight of elastomeric base material, wherein said base material is a thermoplastic elastomer or blend of thermoplastic elastomers selected from the group consisting of elastomers, copolyetherester elastomers, copolyetheramide elastomers, olefmic elastomers, and polyurethanes; and about 1-40 phr of at least one toughness-enhancing polymer.
2. The golf ball cover or mantle of Claim 1, wherein said composition comprises about 5 -30 phr toughness-enhancing polymer.
3. The golf ball cover or mantle of Claim 1, wherein said composition comprises about 10-20 phr toughness-enhancing polymer.
4. The golf ball cover or mantle of Claim 1, wherein said toughness-enhancing polymer is selected from the group consisting of functional polyolefins, grafted polyolefins, styrenic elastomers, and functional styrenic elastomers.
5. The golf ball cover or mantle of Claim 1, wherein said toughness-enhancing polymer comprises a terpolymer of ethylene-acrylic ester-maleic anhydride.
6. The golf ball cover or mantle of Claim 1, wherein said toughness-enhancing polymer comprises a terpolymer of ethylene-acrylic ester-glycidyl methacrylate.
7. The golf ball cover or mantle of Claim 1, wherein said elastomeric base material comprises copolyetheramide.
8. The golf ball cover or mantle of Claim 1, wherein said elastomeric base material comprises copolyetherester.
9. A golf ball comprising a core; and a cover, wherein said cover comprises 100 parts by weight of elastomeric base material, wherein said base material is a thermoplastic elastomer or blend of thermoplastic elastomers selected from the group consisting of elastomers, copolyetherester elastomers, copolyetheramide elastomers, olefinic elastomers, and polyurethanes; and about 1 -40 phr of at least one toughness-enhancing polymer.
10. The golf ball of Claim 9, further comprising a mantle.
11. The golf ball of Claim 10, wherein said mantle comprises more than one layer.
12. The golf ball of Claim 10, wherein said mantle comprises 100 parts by weight of elastomeric base material, wherein said base material is a thermoplastic elastomer or blend of thermoplastic elastomers selected from the group consisting of elastomers, copolyetherester elastomers, copolyetheramide elastomers, olefinic elastomers, and polyurethanes; and about 1 -40 phr of at least one toughness-enhancing polymer.
13. The golf ball of Claim 10, wherein said mantle comprises wound thread.
14. The golf ball of Claim 13, wherein said core comprises liquid or paste.
15. The golf ball of Claim 9, wherein said cover comprises more than one layer.
16. The golf ball of Claim 9, wherein said cover comprises about 5-30 phr of at least one toughness-enhancing polymer.
17. The golf ball of Claim 9, wherein said cover comprises about 10-20 phr of at least one toughness-enhancing polymer.
18. The golf ball of Claim 9, wherein said toughness-enhancing polymer is selected from the group consisting of functional polyolefins, grafted polyolefins, styrenic elastomers, and functional styrenic elastomers.
19. The golf ball of Claim 9, wherein said toughness-enhancing polymer comprises a terpolymer of ethylene, acrylic ester, and maleic anhydride.
20. The golf ball of Claim 9, wherein said toughness-enhancing polymer comprises a terpolymer of ethylene-acrylic ester-glycidyl methacrylate.
21. The golf ball of Claim 9, wherein said elastomeric base material comprises copolyetheramide.
22. The golf ball of Claim 9, wherein said elastomeric base material comprises copolyetherester.
23. A method of making a golf ball cover, comprising the steps of: combining 100 parts by weight of base material with about 1-40 phr of toughness-enhancing polymer to form a golf ball cover composition, wherein said base material is a thermoplastic elastomer or blend of elastomers selected from the group consisting of elastomers, copolyetherester elastomers, copolyetheramide elastomers, olefinic elastomers, and polyurethanes; mixing said golf ball cover composition; and molding said golf ball cover composition to form a golf ball cover.
24. The method of Claim 23, wherein said golf ball cover composition comprises about 5-30 phr of toughness-enhancing polymer.
25. The method of Claim 23, wherein said golf ball cover composition comprises about 10-20 phr of toughness-enhancing polymer.
26. The method of Claim 23, wherein said base material comprises a copolyetheramide.
27. The method of Claim 23, wherein said base material comprises a copolyetherester.
28. The method of Claim 23, wherein said toughness-enhancing polymer is selected from the group consisting of functional polyolefins, grafted polyolefins, styrenic elastomers, and functional styrenic elastomers.
29. The method of Claim 23, wherein said toughness-enhancing polymer comprises a terpolymer of ethylene-acrylic ester-maleic anhydride.
30. The method of Claim 23, wherein said toughness-enhancing polymer comprises a terpolymer of ethylene-acrylic ester-glycidyl methacrylate.
Description  (Le texte OCR peut contenir des erreurs.)

TOUGHNESS-ENHANCED GOLF BALL COVERS USING ORGANIC COMPOUNDS

Field of the Invention

The present invention relates generally to golf balls, more particularly to the use of organic compounds to improve the rheological and mechanical properties of polymer blends used to make golf ball covers. The improvement which results from the use of the organic compounds is directly related to the improved durability of a golf ball during repeated hitting and an improved shear resistance.

Background of the Invention Modern golf balls are of multi-piece design and may comprise any of a multitude of different materials. Two-piece golf balls consist of a cover and a core, whereas three-piece golf balls consist of a cover, mantle and core. The core may be solid, liquid-filled, paste-filled, or some combination thereof. Mantles are generally solids and may comprise a mass of wound thread or one or more pieces of solid molded material. Covers may be made from a number of different materials and are preferably finished with a plurality of dimples which affect the flight characteristics of the ball.

One important class of materials in general use for golf ball covers are elastomers. Elastomers include both thermoplastic and thermoset elastomers of several different compositions. Some commonly used thermoplastic elastomers are polyester elastomers, polyamide elastomers, and polyurethane elastomers.

One family of thermoplastic elastomers which is useful for golf ball covers is that sold as Pebax by Elf Atochem (France). Pebax is an amide block copolyether, the performance characteristics of which can vary widely with the particular grade used. Pebax comes in a wide variety of hardnesses, ranging from 25 Shore D to 72 Shore D. The softer Pebax materials, those with a hardness of 25 Shore D to 45 Shore D, exhibit excellent rebound properties and outstanding spin properties when used as a golf ball cover. When the hardness of the Pebax materials is above about 50 Shore D, the material begins to have a hard feel and does not have the excellent resiliency properties of the softer Pebax grades.

The softest grades of Pebax, those having a hardness of 25 Shore D, have a drawback in that, when formed into a golf ball cover, they impart too much spin to the ball for short iron shots. The grades of Pebax having a hardness around 40 Shore D, Pebax 1205 and Pebax 4033, produce ideal spin characteristics while having the soft cover feel. Although the 40D grades of Pebax have good feel and excellent rebound and spin properties, they have very poor durability. Impact durability testing has found that driver failures occur after fewer than 50 hits. The shear resistance is equally as bad, being worse than balata covered golf balls, which are known to have poor shear durability despite their good performance characteristics. Therefore, because of the poor durability and shear resistance, golf balls having covers made of pure Pebax 1205 or Pebax

4033 are unacceptable.

Thus, it would be desirable to find a way to improve the durability of medium-softness elastomer cover materials while retaining the soft feel, good spin and excellent C.O.R. of the materials. Other materials have been proposed for use in golf ball covers, but as with those listed above, it is difficult to find a single material which will form a golf ball cover which has durability, a soft feel, and good spin characteristics while retaining high resilience and good cut and shear resistance.

Summary of the Invention In accordance with the present invention there is provided a golf ball cover or mantle, comprising a composition formed into said golf ball cover or mantle, said composition comprising 100 parts by weight of base material and 1-40 phr of at least one toughness- enhancing polymeric material. The base material is a thermoplastic elastomer or blend of thermoplastic elastomers selected from the group consisting of elastomers, copolyetherester elastomers, copolyetheramide elastomers, olefinic elastomers, polyurethanes. In one preferred embodiment, the golf ball cover or mantle comprises about 5-30 phr of at least one toughness-enhancing polymer. In an especially preferred embodiment, the golf ball cover or mantle comprises about 10-20 phr of at least one toughness-enhancing polymer..

In a preferred embodiment, the toughness-enhancing polymer is selected from the group consisting of functional polyolefms, grafted polyolefins, styrenic elastomers and functionalized styrenic elastomers. In especially preferred embodiments, the toughness-enhancing polymer is a functional polyolefm.

In accordance with the present invention there is also provided a golf ball comprising a core and a cover, wherein the cover comprises 100 parts by weight of base material and about 1 -40 phr of at least one toughness-enhancing polymer. In a preferred embodiment, the golf ball further comprises a mantle.

In accordance with the present invention there is further provided a method of making a golf ball cover, comprising the steps of combining 100 parts by weight of at least one base material and 1-40 phr of at least one toughness-enhancing polymer to form a golf ball cover composition, mixing the golf ball cover composition and molding the composition to form a golf ball cover.

Brief Description of the Drawings Figure 1 is a cross-section of a golf ball of two-piece construction, comprising a core and a cover.

Figure 2 is a cross-section of a golf ball of three-piece construction, comprising a core, mantle and cover.

Detailed Description of the Preferred Embodiment Most modern golf balls are of two- or three-piece design. A two-piece golf ball 1 is pictured in Figure 1. It comprises a core 3 and a cover 2, upon the surface of which is a plurality of dimples. An example of a three-piece golf ball 5 is shown in Figure 2. The three- piece ball comprises a core 3, a mantle 4, and a cover 2. The core 3 may be solid liquid-filled, or paste filled, the mantle 4 may be solid or comprised of one or more layers or made of wound thread, and the surface of the cover 2 generally has a plurality of dimples thereupon. The golf ball cover compositions of the present invention are suitable for use as a cover material in either type of ball or as a mantle material in a 3 piece ball.

Furthermore, a golf ball cover or mantle may comprise one or more layers as is known in the art. A single golf ball may have both a multi-layer mantle and a multi-layer cover. If there is more than one layer in a cover or mantle, different layers may comprise the same material or different materials, including the compounds of the present invention.

To improve the control and the feeling of a golf ball, it is desirable to use a soft cover material or to somehow decrease the hardness of a relatively hard cover material to a hardness of less than about 55 Shore D. At the same time, the cover material must have a high coefficient of restitution (C.O.R.) and demonstrate good resistance to damage such as cutting when it is hit by a golf club. It is extremely difficult to satisfy all of these requirements.

Oftentimes, when a material has the right softness and high C.O.R., the durability is not adequate or when the durability and the softness are achieved, the coefficient of restitution is not high enough. Addition of a toughness-enhancing polymer can improve the mechanical properties and/or rheological properties of a polymeric material. For example, addition of a toughness-enhancing polymer to a composition having good softness and resiliency allows for the durability of that material to be improved without losing the good properties of that composition. Thus, when a toughness-enhancing polymer is added to a golf ball cover composition having good softness, resiliency and spin characteristics, the durability and sjiear resistance of the golf ball cover is improved without having an adverse effect on the other properties of the golf ball.

The golf ball cover compositions of the present invention comprise at least one toughness-enhancing polymer and an elastomeric base material, which comprises one or more polymeric elastomeric materials or resins. The compositions may further comprise, in suitable amounts, one or more additional compounds as are commonly used in golf ball cover compositions, including UV stabilizers, photostabilizers, antioxidants, pigments, dispersants, mold release agents, processing aids and other additives.

Toughness-enhancing Polymeric Compounds

The materials named below may are referred to herein as toughness-enhancing polymers or as toughness-enhancing compounds because addition of these compounds to base materials increases the durability of the blend compared to the base material without such compounds. In certain circumstances, these compounds may also be used as base materials, per se.

Preferred toughness-enhancing polymers include elastomers having a functional or polar group, such as carboxylic acid, maleic anhydride, glycidyl, norbornene, norbornadiene, epoxy monomer, oxazoline, and hydroxyl group. When one or more toughness-enhancing polymers are blended with an elastomer they modify the properties of the polymeric system to provide improved durability without having an adverse impact on other properties of the polymer.

One preferred type of toughness-enhancing polymer for use in the golf ball cover compositions of the present invention are functional polyolefins. These include ethylene- vinyl acetate copolymers and maleic anhydride modified ethylene-vinyl acetate copolymer such as Fusabond by Du Pont; ethylene-acrylic ester copolymers; ethylene-vinyl acetate-maleic anhydride terpolymers; ethylene-acrylic ester-maleic anhydride terpolymers such as Bondine resins by Sumitomo Chemical Industries Co. including Bondine AX8390 and Bondine AX8060 and Lotader resins by Elf Atochem, with Lotader 4700 being most preferred; ethylene-acrylic ester-glycidyl methacrylate terpolymer such as Lotader resins by Elf Atochem; ethylene-isobutyl acrylate-methacrylic acid terpolymer such as Nucrel by Du Pont; and the mixtures of the above resins. Examples of structures of some of the compounds listed above are shown below.

Ethylene- Vinyl Acetate Copolymers

Ethylene- Acrylic Ester Copolymers

Ethylene- Vinyl Acetate-Maleic Anhydride Terpolymers

CH2 CH2 hCH2 CH-j (cH2 CH2j — CH CH-j-

o

R

Ethylene- Acrylic Ester-Maleic Anhydride Terpolymers

Ethylene- Acrylic Ester-Glycidyl Methacrylate Terpolymers

Another preferred type of toughness-enhancing polymer for use in the golf ball cover compositions of the present invention are grafted polyolefms, i.e. polyolefins having functional monomers grafted thereon. The amount of grafted monomer relative to the amount of polyolefin is preferably about 0.01 to 10%, more preferably about 0.1 to 5% by weight. The grafting can be performed by heating the polyolefins at a high temperature, about 150°C to 300°C, optionally in the presence of a solvent and with or without free radicals. Suitable free radicals include t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumylperoxide, l,3-bis(t-butylperoxyisopropyl)benzene, acetyl peroxide, benzoyl peroxide, isobutyryl peroxide, bis-3,5,5-trirnethylhexanoyl peroxide, and methylethylketone peroxide. Suitable solvents for the reaction include benzene, toluene, xylene, chlorobenzene, and cumene. Preferred grafted polyolefins include grafted polyethylene, grafted ethylene vinyl acetate (EVA), and grafted polypropylene, as shown below.

Grafted Polyethylene

Grafted Ethylene Vinyl Acetate

Grafted Polypropylene

Another preferred type of toughness-enhancing polymer are styrenic elastomers. These may be linear A-B-A type such as styrene-butadiene-styrene (S-B-S), styrene-isoprene-styrene

(S-I-S), styrene-ethylene/butylene-styrene (S-EB-S) and, styrene-ethylene/propylene-styrene; radial (A-B)n type such as (styrene-butadiene). and (styrene-isoprene)n; or diblock type such as styrene-butadiene (S-B), styrene-ethylene/propylene (S-EP), and styrene ethylene/butylene (S- EB). Commercially available examples of these compounds include Kraton D-type or Kraton G-type resins from Shell Chemical Company.

Another preferred type of toughness-enhancing polymer are functionalized styrenic elastomers, such as functionalized styrene-butadiene-styrene, functionalized styrene-isoprene- styrene, and functionalized styrene-ethylene/butylene-styrene. Functional groups include those listed at the beginning of this section. Commercially available examples of these compounds include Kraton G-type from Shell Chemical Co. including maleic anhydride functionalized triblock copolymer consisting of polystyrene end blocks and poly(ethylene/butylene) (Kraton FG 1901X), ESBS A1005, A1010, A1020, AT018, and AT019 from Daicel Chemical Industries, Ltd. and brominated styrene-isobutylene copolymers such as Bromo XP-50, by Exxon. Other preferred types of toughness-enhancing polymers include metallocene-catalyzed ethylene copolymers including ethylene-octene elastomers such as Engage from Dupont Dow Elastomers; methacrylate-butadiene-styrene (MBS) such as Metablen from Elf Atochem and the Paraloid series from Rohm and Haas Co.; ethylene propylene rubber (EPR), ethylene propylene terpolymer rubber (EPDM), modified EPDM, and functionalized EPDM, such as Keltan from DSM Copolymer, Inc. and Royaltuf from Uniroyal Chemical Co.

Still other suitable toughness-enhancing polymers include polybutenes from Amoco Polymers; acrylonitrile butadiene styrene (ABS) powders such as Baymod from Bayer Corp.; acrylics such as Durastrength from Elf Atochem and Paraloid from Rohm and Haas Co.; alphamethystyrene ABS modifier such as Blendex from GE Specialty Chemicals; poly(alphamethylstyrene-styrene acrylonitrile) modifier such as Blendex from GE Specialty Chemicals; thermoplastic vulcanizate; nitrile rubber including Xealloy from Zeon Chemicals, Inc.; hydrogenated nitrile rubber such as Zetpol from Zeon Chemicals, Inc.; polynorbornene such as Norsorex from Zeon Chemicals, Inc.; polymers containing oxazoline group such as several grades of EPICROSS resins including RAS1001, RPSIOOI, and RPS1005 (polystyrene with oxazoline groups) from Nippon Shokubai Kagaku Kogyo K.K.; maleinized polybutadienes such as Ricobond from Ricon Resins Inc.; liquid 1 ,2-polybutadienes and 1,2- polybutadiene/styrene copolymers from Ricon resins Inc.; acrylated and methacrylated polybutadienes from Ricon Resins Inc.; expandable thermoplastic microspheres such as Expancel from Expancel Inc.; and fluoroelastomer such as Viton from Dupont Dow elastomers.

Elastomeric Base Materials

Preferred elastomeric base materials for use in the golf ball cover compositions of the present invention are homopolymers, copolymers, terpolymers, and blends of elastomer resins. Examples of preferred elastomers are: thermoplastic elastomer, thermoplastic rubber, thermoset rubber, thermoset elastomer, dynamically vulcanized thermoplastic elastomers, metallocene polymer or blends of thereof. Elastomers include polyetherester elastomers, polyetheramide elastomers, propylenebutadiene copolymers, dynamically vulcanized PP/EPDM, polyether or polyester thermoplastic urethanes as well as thermoset polyurethanes. The elastomeric base material used in the golf ball covers of the present invention preferably have a hardness less than about 55 Shore D, more preferably less than about 50 Shore D according to ASTM D-

2240.

The most preferred type of elastomers are the copolyetheramide elastomers, such as thermoplastic polyetheramides. One suitable family of such resins is the Pebax family available from Elf Atochem. Pebax has the unusual and likely unique property of increasing in resilience while decreasing in hardness. Preferred members of the Pebax family include Pebax 2533,

Pebax 3533, Pebax 5533, Pebax 6533, Pebax 1205, and Pebax 4033. Pebax 1205 and Pebax 4033 are especially preferred for use in the golf ball cover compositions of the present invention. Pebax 1205 has a hardness of about 40 Shore D, and a flexural modulus of 1.13 Kpsi (ASTM D-790), while Pebax 4033 has a hardness of about 40 Shore D, a flexural modulus of 1.3 Kpsi, and a Bayshore resilience of about 51% (ASTM D-2632). Blends or combinations of these and other members of the Pebax family may be prepared as well. Pebax 2533 is a softer material, having a hardness of about 25 Shore D, a flexural modulus of 2.1 Kpsi, and a Bayshore resilience of about 62%. Pebax 3533 has a hardness of about 35 Shore D, a flexural modulus of 2.8 Kpsi, and a Bayshore resilience of about 59%. Pebax 5533 (55 Shore D) and Pebax 6533 (63 Shore D) are harder grades of Pebax which may be used, but are preferably used as blends with softer grades to keep the total hardness within the preferred limits. Although the hardness values listed herein are determined at room temperature, about 18°C - 23°C, the Shore D hardness of Pebax resins varies little with temperature within the range of -40°C to 80°C.

Other preferred elastomers include the copolyetherester elastomers, examples of which are: polyetherester block copolymers, polylactone ester block copolymers, aliphatic and aromatic dicarboxylic acid copolymerized polyesters, and the like. Polyetherester block copolymers are copolymers comprising polyester hard segments polymerized form a dicarboxylic acid and a low molecular weight diol and polyether soft segment polymerized from an alkylene glycol having 2 to 10 carbon atoms. The polylactone ester block copolymers are copolymers with polylactone chains for the polyether as the soft segments in the above mentioned polyether ester block copolymer structures. The aliphatic and aromatic dicarboxylic acid copolymerized polyesters are generally copolymers of an acid component selected from aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid and aliphatic dicarboxylic 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 although blends of an aromatic polyester and an aliphatic polyester may be equally used here. Some commercially available copolyetherester elastomers are SKYPEL G130D, G135D, and G140D resins from SK Chemicals Co.; Hytrel G3078, G3548, G4074 resins from E.I. DuPont de Nemours & Company.

Another suitable type of elastomer are olefmic thermoplastic elastomers, such as blends of polyolefins with ethyl-propylene-nonconjugated diene terpolymer, block copolymers of styrene and butadiene, or isoprene or ethylene-butylene elastomer. Examples of such resins are those sold under the names Santoprene, Dytron, Vistaflex, Sarlink, and Vyram, which are dynamically vulcanized thermoplastic elastomers.

Yet another suitable type of elastomer are polyurethanes, including thermosets as well as thermoplastic polyurethanes. Examples of thermoplastic polyurethane resins are sold under the name Estane resin, such as Estane 58133, Estane 58134, and Estane 58144, Estane 58285 produced by B.F. Goodrich Co.

Making the Toughness-enhanced Golf Ball Cover Compositions and Golf Balls

To make the golf ball cover composition of the present invention, the base material and one or more toughness-enhancing polymer are mixed together. The toughness-enhancing polymer compounds can be in any form which allows for mixing and measuring, including solids such as powders and pellets, and liquids either with or without solvent added. Preferably, the toughness-enhancing polymer is a solid. The quantity of toughness-enhancing polymer used is preferably about 1 - 40 phr, more preferably about 5 - 30 phr, most preferably about 10-20 phr. The unit "phr" designates parts by weight of toughness-enhancing polymer per hundred parts of base material by weight. In other words, a composition containing 40g toughness-enhancing polymer in 200g of base material could be described as 20 phr of toughness-enhancing polymer in base material. The cover composition of the invention can also include, in suitable amounts, one or more additional ingredients generally employed in golf ball cover compositions. Agents provided to achieve specific functions, such as additives, stabilizers, and reinforcing materials such as inorganic fibers and/or organic fibers can be present. Suitable additional ingredients include UV stabilizers, photo stabilizers, fillers, antioxidants, pigments, dispersants, mold release agents, and processing aids. Examples of fillers include one or more organic or inorganic fillers. For example, inorganic fillers can be added such as titanium dioxide (TiO2), calcium carbonate, zinc sulfide, zinc oxide, or glass beads. Additional fillers can be chosen to impart additional density to blends of the cover, such as zinc oxide, barium sulfate, tungsten carbite, or lead powder.

Once the components are chosen and the quantities for use measured, the golf ball cover composition of the present invention can be blended by an apparatus capable of mixing materials, such as a dry mixer, Banbury type mixer, two-roll mill, or single screw or twin screw extruder.

The compositions of the present invention may be formed into golf ball covers by conventional techniques as are known in the art. The cover may be placed directly over the core of the ball to form a two-piece ball, or it may be used for covering the core which itself is already covered with an intermediate layer or layers of mantle materials to form a three-piece golf ball.

One technique known in the art is injection molding. In this technique, the cover can be directly applied by injection molding over a core or mantle layer or layers. The inner portion of the ball, comprising a core, mantle, or both, is placed into a mold and a melt of the cover material is injected into the mold. The melt of cover material fills the mold, surrounding the core or mantle and taking its shape from the shape of the mold. When the cover material has cooled sufficiently as not to be damaged by handling, the mold is opened and the newly formed golf ball is removed. Another method comprises forming the material into half-cups, preferably by injection molding into a half-shell mold, positioning the two half-cups around the core or the mantle in a conventional compression molding device, and then applying pressure and heat for a predetermined time to allow the two halves to unite to form a single cover. The ball is allowed to cool in the mold until the cover is hard and solid enough to be removed from the mold without deforming. In the case of a wound mantle or core, this method is preferred over injection molding because the heat of the injection molding around a wound core or mantle may cause the thread to snap during molding.

Once the cover is made the golf ball undergoes other operations such as buffing, painting, and stamping. In order to facilitate the buffing, the golf ball can be prefrozen.

Although termed golf ball cover compositions, the compositions of the elastomer base resins and toughness-enhancing polymers of the present invention may also be used in the mantle of a golf ball. The quantity of toughness-enhancing polymer used is preferably about 1-40 phr, more preferably about 5-30 phr, most preferably about 10-20 phr. The materials and mixed and formed, such as by the methods described above. The mantle material may be injection molded around a solid core, or two halves may be made by injection molding and then assembled around the core and compression molded, or the two halves may be compression molded with a void therebetween and filled afterwards with a liquid or paste if a core of such composition is desired.

Testing and Results

Three different golf ball compositions of the present invention were made and formed into golf ball covers for testing in the form of golf balls. The three compositions tested, TM-1, TM-2, and TM-3 had 5 phr, 10 phr, and 20 phr of toughness-enhancing polymer respectively in a base material containing a single elastomeric resin. The toughness-enhancing polymer used was Lotader 4700 (random ethylene-ethyl acrylate-maleic anhydride terpolymer, Elf Atochem) and the base material was Pebax 1205 (thermoplastic polyetheramide, Elf Atochem) having a hardness of about 40 Shore D. Quantities of Pebax 1205 and Lotader 4700 were weighed according to the formulation and the batch was dry blended in a tumbler mixer for 30 minutes at room temperature. The batch of dry blended resins were then compounded by a 35 mm twin screw extruder. The processing conditions were as follows: from the feeder to die, Tl = 80°C,

T2 = 185°C, T3 = 205°C, T4 = 210°C, T5 = 210°C, T6 = 195°C, Tdie = 195°C, and screw speed = 150 rpm. Those extruded resins were made into a golf ball cover by injection molding. A control golf ball having a cover of Pebax 1205 was also made by the same process. The balls having golf ball cover compositions of the present invention as well as the control ball were_of three piece construction, with solid mantles. Balls having the three compositions of the present invention and the control ball made up the set of test golf balls.

To test the cut resistance of the covers, a shear test was done on the set of test golf balls. In the test, two golf balls of each cover composition were shot twice at 80 mph with a Taylor

Made Tour 55 sand wedge-type golf club having the following physical characteristics: lie: 64°; loft: 55°; bounce: 8°; club length: 35 inches. A visual evaluation was made after the ball was struck, and each ball was given a score from 1 to 5, depending on the degree of damage to the ball. The criteria for the scores were as follows: 1 = excellent (no paint or cover damage); 2 = good (paint damage only); 3 = average (minor cover damage); 4 = fair (moderate cover damage, slight material removed); 5 = poor (major cover damage, moderate material removed). An average was taken of the scores for each golf ball cover composition to get a final score for that composition. These results appear in Table 1 below.

To test the durability of the golf ball covers, a test was done to simulate the effect of being struck repeatedly with a driver. In the durability test, the golf balls were fired out of the cylinder of a testing machine of the type used for conventional coefficient of restitution testing. The balls were fired out of the cylinder at 125 ft/sec onto a stationary steel plate, and periodically checked for cracks. The set of test golf balls (12 of each) were conditioned at room temperature for a period of two weeks prior to the test. The test for each set of 12 balls consisted of up to 6 cycles of 50 hits(firings) for each ball in the set. The test for a set of balls ceased when 50%) of the balls in the set had crack failures (50% failure). If 50% failure was not reached, the test was stopped after 6 cycles (300 hits). The number of hits for the first failure and the number of hits for the 50% failure were recorded for each set of test balls. The results of this test are shown in Table 1 below. It can be seen from the data in Table 1 that when the toughness-enhancing polymer is added to the base material to form the golf ball cover compositions of the present invention, the performance of the balls with covers made therefrom is greatly improved. Even with as little as 5 phr of toughness-enhancing polymer, the number of hits required to get the first failure in the durability test nearly doubled. With 20 phr of toughness-enhancing polymer, the number of hits for 50% failure more than doubled. In the shear test, the balls having 20 phr of the toughness- enhancing polymer scored "good" on the shear test, having on average only paint damage compared to the "poor" score received by the control golf balls. Furthermore, the increased durability and shear resistance was not achieved at the expense of other important ball characteristics. The coefficient of restitution and 8-iron spin for the golf balls having toughness- enhancing polymer were either unchanged or slightly improved when compared to the control balls.

Table 1 Ball Composition and Test Results

Although the present invention has been described in terms of certain preferred embodiments, it is to be understood that the scope of the invention is not to be limited thereby. Instead, the inventor intends that the scope of the invention be limited solely by reference to the attached claims, and that variations on the materials and formulations disclosed herein which are apparent to those of skill in the art will fall within the scope of the invention.

Citations de brevets
Brevet cité Date de dépôt Date de publication Déposant Titre
US5759676 *16 févr. 19962 juin 1998Acushnet CompanyMultilayer golf ball
US5947842 *13 mars 19987 sept. 1999Acushnet CompanyMulti-layer low-spin golf ball
US5948864 *11 févr. 19987 sept. 1999Acushnet CompanyGolf ball incorporating liquid crystalline polymers
Classifications
Classification internationaleC08L23/08, C08L101/00, A63B37/00
Classification coopérativeA63B37/0024, C08L101/00, C08L23/08, A63B37/0003
Classification européenneC08L101/00, A63B37/00G
Événements juridiques
DateCodeÉvénementDescription
13 juil. 2000AKDesignated states
Kind code of ref document: A1
Designated state(s): GB JP
19 oct. 2000DFPERequest for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)