US20120309562A1

US20120309562A1 - Multi-layered cores for golf balls containing ionomer and non-ionomer layers

Info

Publication number: US20120309562A1
Application number: US13/152,598
Authority: US
Inventors: Michael J. Sullivan; Mark I. Binette
Original assignee: Individual
Current assignee: Acushnet Co
Priority date: 2011-06-03
Filing date: 2011-06-03
Publication date: 2012-12-06

Abstract

Multi-piece golf balls having a solid core of at least one layer and cover of at least one layer are provided. At least one of the core layers comprises a thermoplastic ionomer composition and at least one of the core layers comprises a thermoplastic non-ionomer composition. Preferably, the ionomer composition is a highly neutralized ethylene acid copolymer. Preferably, the non-ionomer composition is a thermoplastic elastomer selected from polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof. The resulting ball has high resiliency and rebounding properties.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to multi-piece golf balls having a solid core of at least one layer and cover of at least one layer. At least one of the core layers comprises a thermoplastic ionomer composition and at least one of the core layers comprises a thermoplastic non-ionomer composition. Preferably, the ball contains a dual-core having an inner core and surrounding outer core layer or a multi-layered core having an inner core, intermediate core layer, and outer core layer. Low modulus and high modulus compositions may be used in the core structure.
2. Brief Review of the Related Art
Multi-piece, solid golf balls are used today by recreational and professional golfers. Basically, these golf balls contain an inner core protected by a durable cover. The core and cover may be single or multi-layered. For example, three-piece golf balls having an inner core, an inner cover layer, and an outer cover layer may be used. In other instances, golfers will use a four-piece ball containing a dual-core (inner core and surrounding outer-core layer) and dual-cover (inner cover layer and surrounding outer cover layer). Intermediate (casing) layer(s) may be disposed between the core and cover layers to impart various properties and form five-piece balls and the like. Normally, the core layers are made of a natural or synthetic rubber material such as, for example, styrene butadiene, polybutadiene, poly(cis-isoprene), or poly(trans-isoprene); and the cover layers are made of a durable material such as, for example, ethylene acid copolymer ionomer resins, polyamides, polyesters, polyurethanes, or polyureas. Today, the industry is interested, among other things, in making balls that can rebound faster, retain more total energy when struck with a club, and have longer flight distance.
In general, the rebounding performance of a golf ball is based on its initial velocity after being struck by the face of a golf club and its outgoing velocity after making impact with a hard surface. More particularly, the “coefficient of restitution” or “COR” of a golf ball refers to the ratio of a ball's rebound velocity to its initial incoming velocity when the ball is fired out of an air cannon into a rigid vertical plate. The COR for a golf ball is written as a decimal value between zero and one. A golf ball may have different COR values at different initial velocities. The United States Golf Association (USGA) sets limits on the initial velocity of the ball so one objective of golf ball manufacturers is to maximize COR under these conditions. Balls with a higher rebound velocity have a higher COR value. To improve the resiliency and rebounding performance of the golf ball, the industry has focused primarily on the material and construction of the ball's core.
Golf balls having single-layered and multi-layered cores have been developed. For example, Bulpett et al, US Patent Application Publication US 2009/0227394 discloses multi-layered core construction comprising: a) an inner core formed from a first thermoset rubber composition; b) an intermediate core layer formed from a partially-neutralized or highly-neutralized ionomer composition; and c) an outer core formed from a second thermoset rubber composition. A cover layer having a thickness of about 0.01 to 0.05 inches and a surface hardness of about 60 Shore D or less is formed around the core.
Sullivan et al., US Patent Application Publication No. US 2009/0017940 discloses golf balls having a dual-core and a single-layered cover. The dual-core includes an inner core formed from a rubber composition and an outer core layer formed from a highly neutralized polymer (HNP) composition comprising an ethylene acid copolymer. In the HNP composition, at least 80% of all acid groups are neutralized. The inner core has an outer surface hardness of less than 80 Shore C; the outer core layer has an outer surface hardness of 56 Shore D or greater; and the cover layer has a material hardness of 60 Shore D or less.
Sullivan et al., U.S. Pat. Nos. 7,357,736 and 7,211,008 disclose golf balls comprising: a) an inner core layer formed from a diene rubber composition; (b) an outer core layer formed from a high modulus highly neutralized polymer (HNP) comprising a highly neutralized ethylene/(meth)acrylic acid copolymer having a modulus of from 45,000 psi to 150,000 psi; (c) an intermediate core layer disposed between the inner core layer and the outer core layer and formed from a low modulus HNP composition comprising a highly neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer having a modulus of from 1,000 psi to 50,000 psi. In the HNP compositions, at least 80% of all acid groups are neutralized.
Nesbitt et al., U.S. Pat. No. 7,147,578 discloses golf balls containing a dual-core. The inner core (center) and outer core layer may be formed from a thermoset material or a thermoplastic material. The '578 patent discloses suitable thermoset materials as including polybutadiene or any natural or synthetic elastomer, metallocene polyolefins, polyurethanes, silicones, polyamides, and polyureas. Suitable thermoplastic materials are described as including ionomers, polyurethane elastomers, and combinations thereof. In particular, the '578 patent discloses the following commercially available thermoplastic resins are preferred for use in the dual-cores: Capron® 8351 (Allied Signal Plastics), Lexan® ML5776 (General Electric), Pebax® 3533 (Elf Atochem), and Hytrel® G4074 (DuPont).
Although some conventional multi-layered core constructions are generally effective in providing high resiliency golf balls, there is a continuing need for improved core constructions in golf balls. Particularly, it would be desirable to have multi-layered core constructions that could be manufactured efficiently, have relatively low material costs, and provide the ball with high quality and performance properties. In particular, the core should provide the ball with good flight distance along with a comfortable and soft feel. The present invention provides core constructions and resulting golf balls having such properties as well as other advantageous features, and benefits.

SUMMARY OF THE INVENTION

The present invention provides a multi-piece golf ball comprising a solid core having at least one layer and a cover having at least one layer. The golf ball may have different constructions. For instance, in one version, a golf ball having a dual-core is made; while in another version, a golf ball having a three-layered core is made. In preferred embodiment “A”, two different compositions are used to form the dual-core. A non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of: polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof is used to form the inner core; and an ionomer composition comprising an ethylene acid copolymer and containing acid groups such that greater than 70% of the acid groups are neutralized, preferably 90% or greater, is used to form the outer core layer.
Different materials can be used as the neutralizing agent in the ionomer composition. For example, the neutralizing agent can be a metal cation salt, wherein the metal cation is selected preferably from Zn, Na, Li, K, Ca, Mg, Ni, Mn, Cu, Ti, and Al, and mixtures thereof. In one preferred version, the ionomer composition contains a fatty acid or salt thereof, such as, for example, behenic acid, erucic acid, oleic acid, linoelic acid, and dimerized derivatives and mixtures thereof, preferably oleic acid and/or erucic acid.
In one version, the thermoplastic elastomer composition may have a flex modulus of 1,000 to 50,000 psi and the ionomer composition may have a flex modulus of 40,000 to 150,000 psi, wherein the modulus of the thermoplastic elastomer composition is preferably at least 10% less than the modulus of the ionomer composition. Alternatively, the thermoplastic elastomer composition may have a flex modulus of 40,000 to 150,000 psi and the ionomer composition may have a flex modulus of 1,000 to 50,000 psi, wherein the modulus of the thermoplastic elastomer composition is preferably at least 10% greater than the modulus of the ionomer composition. The center of the inner core and surface of the outer core each has a hardness and preferably the surface hardness of the outer core layer (for example, 45 Shore D or greater) is greater than the center hardness of the inner core (for example, 25 Shore D or greater). In alternative versions, the center hardness of the inner core is greater than the surface hardness of the outer core layer.
The cover may be single or multi-layered. For example, a single-layered cover having a thickness of about 0.015 to about 0.090 inches may be made from a thermoplastic or thermoset polymer material. In another instance, a dual-cover having inner and outer layers, wherein the hardness of the outer cover layer (for example, 65 Shore D or less) is less than the hardness of the inner cover layer may be prepared. The dual-core normally has an overall compression in the range of about 50 to about 130, preferably about 70 to about 110.
In preferred embodiment “B”, a highly neutralized ionomer composition (containing acid groups neutralized to greater than 70%) is used to form the inner core, while the thermoplastic elastomer composition (comprising polyester-polyether block copolymers or polyether-amide block copolymers or blends thereof) is used to form the outer core layer. In one version, the ionomer composition has a flex modulus of 20,000 to 150,000 psi and the thermoplastic elastomer composition has a flex modulus of 1,000 to 50,000 psi. In one preferred embodiment, the flex modulus of the ionomer composition is at least 10% greater than the thermoplastic elastomer composition. For example, the flex modulus of the ionomer composition may be 40,000 or greater, while the flex modulus of the thermoplastic elastomer may be 30,000 or less. In an alternative version, the ionomer composition has a flex modulus of 1,000 to 50,000 psi and the thermoplastic elastomer composition has a flex modulus of 20,000 to 150,000 psi, wherein the modulus of the ionomer composition is preferably at least 10% less than the thermoplastic elastomer material. For example, the flex modulus of the ionomer composition may be 30,000 or less, while the flex modulus of the thermoplastic elastomer may be 40,000 or greater.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features that are characteristic of the present invention are set forth in the appended claims. However, the preferred embodiments of the invention, together with further objects and attendant advantages, are best understood by reference to the following detailed description in connection with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a three-piece golf ball having a dual-core comprising an inner core/outer core, and a cover layer made in accordance with the present invention;

FIG. 2 is a cross-sectional view of another three-piece golf ball having a dual-core made in accordance with the present invention;

FIG. 3 is a cross-sectional view of a four-piece golf ball having a dual-core comprising an inner core/outer core; an inner cover layer; and an outer cover layer made in accordance with the present invention; and

FIG. 4 is a cross-sectional view of another four-piece golf ball having a dual-core made in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to golf balls containing at least one component made from a thermoplastic non-ionomer composition and at least one component made from a thermoplastic ionomer composition. In one preferred version, a non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of: polyester-polyether block copolymers, polyether-polyamide block copolymers, and blends thereof is used to faun an inner core, and an ionomer composition comprising an ethylene acid copolymer, wherein the composition contains acid groups such that greater than 70%, preferably 90% or greater, of the acid groups are neutralized is used to form an outer core layer. In a second preferred version, the ionomer composition is used to form the inner core, while the non-ionomer composition is used to form the outer core layer.
Golf balls having various constructions may be made in accordance with this invention. For example, golf balls having three-piece, four-piece, and five-piece constructions with single or multi-layered cover materials may be made The term, “layer” as used herein means generally any spherical portion of the golf ball. More particularly, in one version, a three-piece golf ball having a dual-core and a cover is made. The dual-core includes an inner core (center) and surrounding outer core layer. In another version, a four-piece golf ball comprising a dual-core and dual-cover comprising an inner cover and outer cover is made. In yet another construction, a four-piece or five-piece golf ball having a multi-layered core comprising an inner core (center), intermediate core layer, and outer core layer, may be made. The golf balls of this invention may further contain an intermediate layer(s). As used herein, the term, “intermediate layer” means a layer of the ball disposed between the core and cover. The intermediate layer also may be referred to as a casing or mantle layer. The diameter and thickness of the different layers along with properties such as hardness and compression may vary depending upon the construction and desired playing performance properties of the golf ball.
Low Modulus and High Modulus Core Layers
As discussed above, in one preferred version, the golf ball of the present invention comprises an inner core made from a thermoplastic elastomer composition and an outer core made from an ionomer composition comprising an ethylene acid copolymer containing acid groups neutralized to greater than 70%. In a second preferred version, the ionomer composition is used to form the inner core, while the thermoplastic elastomer is used to form the outer core
In some versions, the thermoplastic elastomer composition is relatively flexible having a relatively low flex modulus of 1,000 to 50,000 psi and the ionomer composition is relatively stiff having a relatively high flex modulus of 20,000 to 150,000 psi. That is, in this version, the modulus of the thermoplastic elastomer composition is less than the modulus of the ionomer composition. In alternative versions, the thermoplastic elastomer composition has a relatively high flex modulus of 20,000 to 150,000 psi and the ionomer composition has a relatively low flex modulus of 1,000 to 50,000 psi. That is, in this version, the modulus of the thermoplastic elastomer composition is greater than the modulus of the ionomer composition. More particularly, the low modulus materials may have a modulus with a lower limit of 1,000 or 5,000 or 10,000 or 15,000 psi and an upper limit of 17,000 or 25,000 or 28,000 or 30,000 or 35,000 or 45,000 or 50,000. The hardness of the low modulus material is generally 30 Shore C or greater; or 40 Shore C or greater; or 50 Shore C or greater, or preferably within a range having a lower limit of 30 or 40 or 50 Shore C and an upper limit of 60 or 70 or 80 or 87 Shore C. On the other hand, the high modulus materials preferably may have a modulus within the range having a lower limit of 20,000 or 30,000 or 40,000 or 45,000 or 50,000 or 55,000 or 60,000 psi and an upper limit of 72,000 or 75,000 or 100,000 or 150,000 and a hardness of 80 Shore C or greater, or 87 Shore C or greater, or 90 Shore C or greater, or within a range having a lower limit of 80 or 87 or 90 Shore C and an upper limit of 90 or 95 or 100 Shore C. In a preferred embodiment, the modulus of the relatively low modulus material is at least 10% less, or at least 20% less, or at least 30% less than the modulus of the relatively high modulus material.
By the term, “modulus” as used herein, it is meant flexural modulus which is the ratio of stress to strain within the elastic limit (when measured in the flexural mode) and is similar to tensile modulus. This property is used to indicate the bending stiffness of a material. The flexural modulus, which is a modulus of elasticity, is determined by calculating the slope of the linear portion of the stress-strain curve during the bending test. The formula used to calculate the flexural modulus from the recorded load (F) and deflection (D) is:
$E_{B} = \frac{3}{4} \frac{{FL}^{3}}{{bd}^{3} D}$ $wherein, L = span of specimen between supports (m);$ $b = width (m); and$ $d = thickness (m)$
If the slope of the stress-strain curve is relatively steep, the material has a relatively high flexural modulus meaning the material resists deformation. The material is more rigid. If the slope is relatively flat, the material has a relatively low flexural modulus meaning the material is more easily deformed. The material is more flexible. Flexural modulus can be determined in accordance with ASTM D790 standard among other testing procedures.
Thermoplastic Elastomers
As discussed above, thermoplastic elastomers may be used to form the compositions of this invention. In general, thermoplastic elastomers refer to a class of polymers having thermoplastic-like (softens when exposed to heat and returns to original condition when cooled) properties and elastomeric-like (can be stretched and then returns to original condition when released) properties. In thermoplastic elastomer block copolymers, there are some blocks having thermoplastic-like properties and these blocks may be referred to as “hard” segments. Also, there are some blocks having elastomeric-like properties and these blocks may be referred to as “soft” segments. The ratio of hard to soft segments and the composition of the segments are significant factors in determining the properties of the resulting thermoplastic elastomer.
One example of a suitable thermoplastic elastomer that can be used to form the compositions of this invention is polyester-polyether block copolymers. In general, these block copolymers contain hard and soft segments having various lengths and sequences. The hard, crystalline polyester segments are normally derived from reacting an aromatic-containing dicarboxylic acid or diester such as, for example, terephthalic acid, dimethyl terephthalate, and the like with a diol containing about 2 to about 10 carbon atoms. For example, the hard segments may constitute butylene terephthalate, tetramethylene terephthalate, or ethylene terephthalate units. The soft, elastomeric segments are normally derived from long or short-chain poly(alkylene oxide) glycols containing a total of about 3 to about 12 carbon atoms including up to 3 or 4 oxygen atoms with the remaining atoms being hydrocarbon atoms. Useful poly(alkylene oxide) glycols include, for example, poly(oxyethylene)diol, poly(oxypropylene)diol, and poly(oxytetramethylene)diols. More particularly, the polyether polyols have been based on polymers derived from cyclic ethers such as ethylene oxide, 1,2-propylene oxide and tetrahydrofuran. When these cyclic ethers are subjected to ring opening polymerization, they provide the corresponding polyether glycol, for example, polyethylene ether glycol (PEG), poly(1,2-propylene) glycol (PPG), and polytetramethylene ether glycol (PO4G, also referred to as PTMEG).
A preferred polyester-polyether block copolymer is commercially-available under the trademark, Hytrel®, from DuPont. These block copolymers are available in different grades and contain hard (crystalline) segments of polybutylene terephthalate and soft (amorphous) segments based on long-chain polyether glycols. These and other examples of polyester-polyether block copolymers which can be used in accordance with the present invention are disclosed in U.S. Pat. Nos. 2,623,031; 3,651,014; 3,763,109; and 3,896,078, the disclosures of which are hereby incorporated by reference. Different grades of Hytrel® polyester-polyether block copolymers and their respective properties, which may be used in accordance with this invention, are described in the following Tables I and II.

TABLE I

Hytrel ® Polyester-polyether block copolymers

Test

HYTREL Grade

Property	Method	Units	F3548L	G4074	G4778	G5544	4056

Hardness, durometer D	D 2240	D	35	40	47	55	40
Flexural Modulus	D790	Ksi
at −40	method I		9	30	47	123	22.5
At 73 F.	Proc B		4.7	9.5	17	28	9
At 212 F.			1	4.75	10	18	3.9
Tensile stress at	D 638	ksi	1.49	2	3	4.5	4.05
break
Elongation at break	D638	%	200	230	300	375	550
Izod impact	D256	ft lb/in
at −40	method A		no	0.5	3.1	2.5	no
			break				break
At 73 F.			no	no	no	no	no
			break	break	break	break	break
Melt flow rate	D1238	g/10 min	10	5.2	13	10	5.3
Temp ° F. at 2.16 kg load			374	374	446	446	374
Melting point	D3418	° F.	312	338	406	419	302
Vicat softening point	D1526	° F.	171	233	347	385	226
	Rate B
Specific Gravity	D792		1.15	1.18	1.2	1.22	1.17

TABLE II

Hytrel ® Polyester-polyether block copolymers

Test

HYTREL Grade

Property	Method	Units	4556	6356	7246	8238	3078

Hardness, durometer D	D 2240	D	45	63	72	82	30
Flexural Modulus	D790	Ksi
at −40	method I		33	260	350	440	21
At 73 F.	Proc B			14	48	83	175	4
At 212 F.			6.4	22	30	37	2
Tensile stress at	D 638	Ksi	4.5	6	6.6	7	5.8
break
Elongation at break	D638	%	600	420	360	350	450
Izod impact	D256	ft lb/in
at −40	method A		no	0.9	0.8	0.5	No
			break				break
At 73 F.			no	no	3.9	0.8	No
			break	break			break
Melt flow rate	D1238	g/10 min	8.5	8.5	12.5	12.5	5
Temp ° F. at 2.16 kg load			428	446	464	464	374
Melting point	D3418	° F.	379	412	424	433	338
Vicat softening point	D1526	° F.	171	383	405	414	181
	Rate B
Specific Gravity	D792		1.14	1.22	1.25	1.28	1.07

As shown in above Tables I and II, the flex modulus of some Hytrel® polyester-polyether block copolymers may fall within the range of about 1,000 to about 150,000 psi (or greater). Such block copolymers may be used to form a low modulus (or high modulus) core layer in accordance with this invention.
Other examples of suitable thermoplastic elastomers that can be used to form the compositions of this invention are polyether-amide block copolymers, which are commonly known as Pebax® resins, and are available from Arkema, Inc. (Columbs, France).
In general, polyether amide block copolymers may be prepared by polycondensation of a polyamide with carboxyl end-groups with a polyether glycol. These block copolymers have been prepared using polyethylene glycol, polypropylene glycol, polytetramethylene glycol, copolyethers derived therefrom, and copolymers of THF and 3-alkylTHF as shown by U.S. Pat. Nos. 4,230,838, 4,252,920, 4,349,661, 4,331,786 and 6,300,463, the disclosures of which are hereby incorporated by reference. The general structure of the polyether amide block copolymer may be represented by the following formula (I):
represents a polyamide segment containing terminal carboxyl groups or acid equivalents thereof (for example, diacid anhydrides, diacid chlorides or diesters) and
—O-G-O—
is a polyether segment.
Different grades of Pebax® polyether amide block copolymers and their respective properties, which may be used in accordance with this invention, are described in the following Tables III and IV.

TABLE III

Pebax ® Polyether-amide block copolymers

Test

PEBAX Grade

Property	Method	Units	7233	7033	6333	5533

Hardness, durometer D	D 2240	D	72	69	63	55
Flexural Modulus	D790	psi	107,000	67,000	49,000	29,000
Tensile Strength,	D 638	psi	9210	8300	8100	7300
Ultimate
Elongation, Ultimate	D638	%	360	400	300	430
Izod impact	D256	ft lb/in
at 20 F.			1.4	no	no	no
				break	break	break
at −40 F.			1.4	0.95	1.5	no
						break
Melting point	D3418	° F.	348	345	342	334
Vicat softening point	D1525	° F.	327	329	322	291
Specific Gravity	D792		1.02	1.02	1.01	1.01

TABLE IV

Pebax ® Polyether-amide block copolymers

	Test		PEBAX	PEBAX	PEBAX
Property	Method	Units	4033	3533	2533

Hardness,	D 2240	D	40	35	25
durometer D
Flexural Modulus	D790	psi	13,000	2,800	2,100
Tensile Strength,	D 638	psi	5700	5600	4950
Ultimate
Elongation,	D638	%	390	580	640
Ultimate
Izod impact	D256	ft lb/in
at 20 F.			no	no	no
			break	break	break
at −40 F.			no	no	no
			break	break	break
Melting point	D3418	° F.	334	306	298
Vicat softening	D1525	° F.	270	165	140
point
Specific Gravity	D792		1.01	1.01	1.01

As shown in above Tables III and IV, the flex modulus of some Pebax® polyester-polyether block copolymers may fall within the range of about 20,000 to about 150,000 psi, preferably 25,000 to 75,000. While, other Pebax® polyester-polyether block copolymers may fall within the range of about 1,000 to about 50,000 psi, preferably 2,000 to 15,000. Such block copolymers may be used to form a low modulus (or high modulus) core layer in accordance with this invention.
Ethylene Acid Copolymers
Suitable ethylene acid copolymers that may be used to form the compositions of this invention are generally referred to as copolymers of ethylene; C₃to C₈α,β-ethylenically unsaturated mono- or dicarboxylic acid; and optional softening monomer. Copolymers may include, without limitation, ethylene acid copolymers, such as ethylene/(meth)acrylic acid, ethylene/(meth)acrylic acid/maleic anhydride, ethylene/(meth)acrylic acid/maleic acid mono-ester, ethylene/maleic acid, ethylene/maleic acid mono-ester, ethylene/(meth)acrylic acid/n-butyl (meth)acrylate, ethylene/(meth)acrylic acid/iso-butyl (meth)acrylate, ethylene/(meth)acrylic acid/methyl (meth)acrylate, ethylene/(meth)acrylic acid/ethyl (meth)acrylate terpolymers, and the like. The teem, “copolymer,” as used herein, includes polymers having two types of monomers, those having three types of monomers, and those having more than three types of monomers. Preferred α,β-ethylenically unsaturated mono- or dicarboxylic acids are (meth) acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fumaric acid, itaconic acid. (Meth) acrylic acid is most preferred. As used herein, “(meth) acrylic acid” means methacrylic acid and/or acrylic acid. Likewise, “(meth)acrylate” means methacrylate and/or acrylate.
When a softening monomer is included, such copolymers are referred to herein as E/X/Y-type copolymers, wherein E is ethylene; X is a C₃to C₈α,β-ethylenically unsaturated mono- or dicarboxylic acid; and Y is a softening monomer. The softening monomer is typically an alkyl (meth)acrylate, wherein the alkyl groups have from 1 to 8 carbon atoms. Preferred E/X/Y-type copolymers are those wherein X is (meth) acrylic acid and/or Y is selected from (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, methyl (meth)acrylate, and ethyl (meth) acrylate. More preferred E/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butyl acrylate, ethylene/(meth) acrylic acid/methyl acrylate, and ethylene/(meth) acrylic acid/ethyl acrylate.
The amount of ethylene in the acid copolymer is typically at least 15 wt. %, preferably at least 25 wt. %, more preferably least 40 wt. %, and even more preferably at least 60 wt. %, based on total weight of the copolymer. The amount of C₃to C₈α,β-ethylenically unsaturated mono- or dicarboxylic acid in the acid copolymer is typically from 1 wt. % to 35 wt. %, preferably from 5 wt. % to 30 wt. %, more preferably from 5 wt. % to 25 wt. %, and even more preferably from 10 wt. % to 20 wt. %, based on total weight of the copolymer. The amount of optional softening comonomer in the acid copolymer is typically from 0 wt. % to 50 wt. %, preferably from 5 wt. % to 40 wt. %, more preferably from 10 wt. % to 35 wt. %, and even more preferably from 20 wt. % to 30 wt. %, based on total weight of the copolymer. “Low acid” and “high acid” ionomeric polymers, as well as blends of such ionomers, may be used. In general, low acid ionomers are considered to be those containing 16 wt. % or less of acid moieties, whereas high acid ionomers are considered to be those containing greater than 16 wt. % of acid moieties.
The acidic groups in the copolymeric ionomers are partially or totally neutralized with a cation source. Suitable cation sources include metal cations and salts thereof, organic amine compounds, ammonium, and combinations thereof. Preferred cation sources are metal cations and salts thereof, wherein the metal is preferably lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, manganese, nickel, chromium, copper, or a combination thereof. The metal cation salts provide the cations capable of neutralizing (at varying levels) the carboxylic acids of the ethylene acid copolymer and fatty acids, if present, as discussed further below. These include, for example, the sulfate, carbonate, acetate, oxide, or hydroxide salts of lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, manganese, nickel, chromium, copper, or a combination thereof. Preferred metal cation salts are calcium and magnesium-based salts. High surface area cation particles such as micro and nano-scale cation particles are preferred. The amount of cation used in the composition is readily determined based on desired level of neutralization.
In the present invention, the ionomer resins have acid groups that are neutralized greater than about 70 percent, preferably at least 80%, more preferably at least 90% and even more preferably at least 100%. In another embodiment, an excess amount of neutralizing agent, that is, an amount greater than the stoichiometric amount needed to neutralize the acid groups, may be used. That is, the acid groups may be neutralized to 100% or greater, for example 110% or 120% or greater. In one preferred embodiment, a high acid ethylene acid copolymer containing about 19 to 20 wt. % methacrylic or acrylic acid is neutralized with magnesium cations to a 100% or greater neutralization level.
As discussed above, ethylene acid copolymer ionomer resins, which are highly neutralized, may be used in accordance with this invention and suitable examples of these highly neutralized polymers (HNPs) are described in the following Table V (dipolymers) and Tables VI and VII (terpolymers).

TABLE V

Ethylene Acid Dipolymers Neutralized to Different Levels

Base Resin Props.

HNP Properties

% Acid/

% Fatty/

%

Atti

Sphere

Shore D

Flex

Melt

Ex #	Resin	Type	Type*	Neut.	Comp.	CoR	Sphere	Plaque	Mod.	Index

1	R-17	21% AA	36.8% Ol	125%	129	0.884	58.7	—	—	0.03
2	R-14	20% MAA	35.9% Ol	139%	130	0.864	56.0	60	24.5	0.63
3	R-14	20% MAA	36.7% Ol	162%	128	0.862	50.6	57	20.9	0.45
4	R-14	20% MAA	38.3% Ol	170%	120	0.866	52.0	57	21.5	0.59
5	R-14	20% MAA	39.9% Ol	178%	119	0.867	48.5	55	20.4	0.72
6	R-15	19% MAA	41% Ol	134%	115	0.868	48.0	54	16.8	1.2
7	R-15	19% MAA	41% Ol	134%	116	0.866	51.3	57	20	0.6
8	R-15	19% MAA	36.9% Ol	146%	119	0.863	49.6	57	21.5	0.5
9	R-15	19% MAA	39% Ol	160%	128	0.865	51.0	57	20.9	0.61
10	R-15	19% MAA	46% Ol	160%	115	0.862	49.2	54	18.3	0.62
11	R-15	19% MAA	41.4% Ol	174%	116	0.867	47.1	56	20.1	0.75
12	R-16	19% MAA	35% Ol	126%	96	0.860	53.0	57	20.8	1.2
13	R-16	19% MAA	39.9% Ol	174%	109	0.862	47.4	56	17.2	0.96
14	R-18	18% AA	36% Ol	81%	122	0.819	—	57	20.6	0.8
15	R-18	18% AA	40% Ol	97%	125	0.818	—	—	—	0.75
16	R-18	18% AA	34.8% Ol	150%	108	0.867	55.9	—	—	0.22
17	R-18	18% AA	40.4% Er	153%	97	0.872	50.1	—	—	0.46
18	R-19	15.4% AA	40% Ol	98%	115	0.821	—	—	—	0.38

R-14: An ethylene methacrylic acid (MAA) dipolymer with 20 weight % of MAA, and a Melt Index of 500.
R-15: An ethylene methacrylic acid (MAA) dipolymer with 19 weight % of MAA, and a Melt Index of 305.
R-16: An ethylene methacrylic acid (MAA) dipolymer with 19 weight % of MAA, and a Melt Index of 250.
R-17: An ethylene acrylic acid (AA) dipolymer with 21 weight % of AA, and a Melt Index of 300.
R-18: An ethylene acrylic acid (AA) dipolymer with 18 weight % of AA, and a Melt Index of 60.
R-19: An ethylene acrylic acid (AA) dipolymer with 15.4 weight % of AA, and a Melt Index of 80.
*Fatty Acid Type: Ol—Oleic acid and Er—Erucic Acid

As shown in above Table V, the flex modulus of some relatively highly neutralized ethylene acid copolymers may fall within the range of about 10,000 to about 40,000 psi, preferably 15,000 to 35,000 psi, in some instances. Such ionomer compositions may be used to form a low modulus (or high modulus) core layer in accordance with this invention.

TABLE VI

Ethylene Acid Terpolymers Neutralized to Different Levels

Base Resin Properties

HNP Properties

% Acid/

% Fatty/

%

Atti

Sphere

Shore D

HNP

Ex #	Resin	Type/% Ester	Type	Neut.	Comp	CoR	Sphere	Plaque	MI

19	R-11	21.3% AA/2% nBA	40.5% 50/50	103%	124	0.886	55.3	—	0.29
			O/E
20	R-11	21.3% AA/2% nBA	44% 50/50	123%	118	0.889	51.5	—	0.34
			O/E
21	R-11	21.3% AA/2% nBA	30.7% oleic	105%	141	0.884	58.1	—	0.01
22	R-11	21.3% AA/2% nBA	42.6% oleic	105%	131	0.889	54.5	—	0.37
23	R-12	21.4% AA/4% nBA	31.6% oleic	99%	140	0.866	59.1	—	0.17
24	R-12	21.4% AA/4% nBA	41.9% oleic	105%	127	0.888	53.3	—	0.48
25	R-12	21.4% AA/4% nBA	34.3% oleic	134%	131	0.872	57	—	0.06
26	R-12	21.4% AA/4% nBA	39.3% 50/50	102%	123	0.884	55.1	—	0.25
			O/E
27	R-2	20.8% AA/2% nBA	36.7 oleic	124%	127	0.880	59.6	—	0.06
28	R-7	19.5% MAA/4% nBA	29.5% oleic	150%	122	0.835	53.6	—	0.31
29	R-7	19.5% MAA/4% nBA	32.1% oleic	142%	115	0.835	52.6	—	0.89
30	R-7	19.5% MAA/4% nBA	38.7% oleic	143%	111	0.853	49.7	—	2.58
31	R-7	19.5% MAA/4% nBA	38% oleic	195%	112	0.853	48.2	—	0.93
32	R-9	17.6% AA/4% nBA	30.5% oleic	122%	123	0.865	54.2	—	0.16
33	R-9	17.6% AA/4% nBA	32.1% oleic	104%	125	0.866	52.7	—	0.46
34	R-9	17.6% AA/4% nBA	40% oleic	104%	116	0.882	49.5	—	1.12
35	R-9	17.6% AA/4% nBA	31% oleic	154%	121	0.862	58.1	—	0.01
36	R-9	17.6% AA/4% nBA	39.6% oleic	135%	120	0.880	50.7	—	0.35
37	R-8	17.5% MAA/8% nBA	30.8% oleic	138%	107	0.828	47.3	—	2.21
38	R-8	17.5% MAA/8% nBA	29.4% oleic	152%	112	0.842	51.1	—	0.01
39	R-8	17.5% MAA/8% nBA	36.8% oleic	160%	102	0.844	46.8	—	6.85
40	R-8	17.5% MAA/8% nBA	38.2% oleic	215%	104	0.847	47	—	4.55
41	R-6	15.7% MAA/7.8%	40% oleic	153%	97	0.868	47.8	—	0.95
		nBA
42	R-6	15.7% MAA/7.8%	37.5% oleic	129%	97	0.866	48.6	—	1.05
		nBA

R-2: A 50/50 blend by weight of the following: i) an ethylene/acrylic acid (AA)/n-butyl acrylate (nBA) terpolymer with 20.5 weight % of AA and 4.0 weight % of nBA, and a Melt Index of about 750; and ii) an ethylene/AA copolymer with 21.0 weight % of AA and a Melt Index of 300.
R-6: An ethylene/methacrylic acid (MAA)/nBA terpolymer with 15.7 weight % of MAA and 7.8 weight % of nBA, and a Melt Index of 122.
R-7: An ethylene/MAA/nBA terpolymer with 19.5 weight % of MAA and 4.0 weight % of nBA, and a Melt Index of 265.
R-8: An ethylene/MAA/nBA terpolymer with 17.5 weight % of MAA and 8.0 weight % of nBA, and a Melt Index of 280.
R-9: An ethylene/AA/nBA terpolymer with 17.6 weight % of AA and 4.0 weight % of nBA, and a Melt Index of 285.
R-11: An ethylene/AA/nBA terpolymer with 21.3 weight % of AA and 2.0 weight % of nBA, and a Melt Index of 275.
R-12: An ethylene/AA/nBA terpolymer with 21.4 weight % of AA and 4.0 weight % of nBA, and a Melt Index of 275.
*Fatty Acid Type: Oleic Acid and Erucic Acid
O—Oleic acid and
E—Erucic Acid.

TABLE VII

Ethylene Acid Terpolymers Neutralized to Different Levels

Base Resin Properties

HNP Properties

% Acid/

% Fatty/

%

Atti

Sphere

Shore D

HNP

Ex #	Resin	Type/% Ester	Type	Neut.	Comp	CoR	Sphere	Plaque	MI

43	R-10	15.4% AA/8% nBA	30% oleic	114%	117	0.870	53.6	—	0.29
44	R-10	15.4% AA/8% nBA	39.8% oleic	138%	111	0.875	48.3	—	0.75
45	R-10	15.4% AA/8% nBA	36.5% oleic	142%	101	0.875	49.6	—	0.21
46	R-1	12% AA/17.6% nBA	36.5% oleic	135%	118	0.868	47.7	—	0.35
47	R-3	10.5% AA/15.5%	35% oleic	102%	101	0.859	45.8	—	1
		nBA
48	R-3	10.5% AA/15.5%	34.9% oleic	124%	82	0.850	47.8	—	0.91
		nBA
49	R-3	10.5% AA/15.5%	37.5% oleic	127%	75	0.850	48.6	—	1.05
		nBA
50	R-13	9% MAA/15.5% nBA	35.1% oleic	120%	62	0.817	39.2	—	3.68
51	R-13	9% MAA/15.5% nBA	38.7% erucic	125%	57	0.817	36.4	—	7.74
52	R-4	6.2% AA/28% nBA	35% oleic	145%	75	0.826	41.8	—	1
53	R-4	6.2% AA/28% nBA	35% oleic	124%	51	0.807	35.8	—	2.63
54	R-4	6.2% AA/28% nBA	39.8% erucic	121%	41	0.805	33.6	—	5.94
55	R-5	6.2% AA/28% nBA	35% oleic	115%	NA	NA	NA	NA	NA

HPF 1000	9% AA/15.5% nBA	~40% St.A	~100	110	0.833	55	52	—
HPF 2000	10.5% AA/15.5%	~40% oleic acid	~100	123	0.863	47	—	—
	nBA
AD 1030	NA	NA	~100	73	0.824	—	—	—
AD 1035	NA	NA	~100	66	0.826	—	—	—
AD 1040	NA	NA	~100	123	0.852	—	—	—

R-1: An ethylene/acrylic acid (AA)/n-butyl acrylate (nBA) terpolymer with 12 weight % of AA and 17.6 weight % of nBA, and a Melt Index of 95.
R-3: An ethylene/AA/nBA terpolymer with 10.5 weight % of AA and 15.5 weight % of nBA, and a Melt Index of 60.
R-4: An ethylene/AA/nBA terpolymer with 6.2 weight % of AA and 28.0 weight % of nBA, and a Melt Index of 60.
R-5: An ethylene/AA/nBA terpolymer with 6.2 weight % of AA and 28.0 weight % of nBA, and a Melt Index of 300.
R-10: An ethylene/AA/nBA terpolymer with 15.4 weight % of AA and 8.0 weight % of nBA, and a Melt Index of 300.
R-13: An ethylene/MAA/nBA terpolymer with 9.0 weight % of MAA and 15.5 weight % of nBA, and a Melt Index of 60.
HPF-1000, HPF-2000, AD-1030, AD-1035, and AD-1040: compositions unavailable - materials commercially available from DuPont.

The above-described ethylene acid copolymer compositions in Tables V-VII were prepared according to the following general procedure. The organic acid, ethylene acid copolymer, and neutralizing agent (Mg(OH)₂concentrate) were melt-blended in a Werner & Pfleiderer twin screw extruder. The amounts of the acid and copolymer were added so that the resulting blend contained 25 to 45 weight % of the organic acid. The blend was treated with sufficient neutralizing agent so that the acid moieties of the organic acid and the acid copolymer were nominally neutralized to the level indicated in above Tables V-VII.
The highly neutralized ethylene acid copolymer compositions described in Tables VI-VII have other physical properties, some of which are described below in Table VIII. In particular, the flex modulus of some relatively highly neutralized ethylene acid copolymers may fall within the range of about 1,000 to about 20,000 psi, preferably 3,000 to 10,000, in some instances. Such ionomer compositions may be used to form a low modulus (or high modulus) core layer in accordance with this invention.

TABLE VIII

Properties of Highly Neutralized Ethylene Acid
Copolymers (Flex Modulus of 5,000 PSI or Less)

	Tensile	Elongation	Shore D	Flex Modulus
Resin	Strength (psi)*	(%)*	Hardness	(psi)**

HPF 1000	2,600	430%	55	31,000
HPF 2000	1,800	330%	47	12,000

Tensile Strength and Elongation were measured according to ASTM D638. *Flex Modulus was measured according to ASTM D790.

Other highly neutralized ethylene acid copolymer compositions, examples of which are described below in Table IX, may be used in accordance with this invention. In particular, the flex modulus of the relatively highly neutralized ethylene acid copolymers may fall within the range of about 10,000 to about 80,000 psi, preferably 20,000 to 70,000 in some instances. Such ionomer compositions may be used to form a low modulus (or high modulus) core layer.

TABLE IX

Properties of Highly Neutralized Ethylene Acid Copolymers
(Flex Modulus of 10,000 PSI or Greater)

				Flex
Exam-		Cation	Fatty	Modulus**	Shore D
ple	Copolymer*	Source	Acid	(psi)	Hardness***

56	dipolymer	Ca/Mg	Stearic	71,600	57
57	dipolymer	Ca/Li	Stearic	70,300	58
58	dipolymer	Ca	Stearic	70,100	60
59	dipolymer	Ca/Zn	Stearic	60,400	58
60	terpolymer	Mg	Stearic	38,300	52
61	dipolymer	Mg	Oleic	27,600	52
62	terpolymer	Mg	Oleic	16,300	45
63	Terpolymer	Mg	Oleic	10,600	40
64	terpolymer	Mg	Oleic	10,400	39
65	dipolymer	Ca	Stearic	60,300	37
66	dipolymer	Ca	Stearic	69,300	60
67	terpolymer	Mg	Erucic	7,300	37

*Copolymer Type: dipolymer—poly(ethylene-acrylic acid)
terpolymer—Poly(ethylene-n-butyl acrylate-acrylic acid)
**Flex Modulus was measured according to ASTM D790-03, Procedure B.
***Hardness was measured according to ASTM D-2240.

Additional Materials in Ionomer Compositions
In the present invention, it is not necessary that any “ionic plasticizer” such as organic acids or salts of organic acids, particularly fatty acids, be added to the ionomer resin. Such ionic plasticizers are used to make conventional ionomer composition more processable as described in Rajagopalan et al., U.S. Pat. No. 6,756,436, the disclosure of which is hereby incorporated by reference. In the present invention such ionic plasticizers are optional. In one preferred embodiment, the thermoplastic ionomer composition, containing acid groups neutralized to greater than 70%, includes an ionic plasticizer, particularly a fatty acid or salt thereof while, the ionomer composition that contains acid groups neutralized to 70% or less does not contain a fatty acid or salt thereof. The ionic plasticizer may be added in an amount of 0.5 to 10 pph, more preferably 1 to 5 pph. The organic acids may be aliphatic, mono- or multi-functional (saturated, unsaturated, or multi-unsaturated) organic acids. Suitable fatty acids include behenic acid, erucic acid, oleic acid, linoelic acid, and dimerized derivatives and mixtures thereof. Preferably, erucic acid and/or oleic acid is used. Salts of these organic acids may also be employed. Suitable fatty acid salts include, for example, metal stearates, laureates, oleates, palmitates, pelargonates, and the like. For example, fatty acid salts such as zinc stearate, calcium stearate, magnesium stearate, barium stearate, and the like can be used. The salts of fatty acids are generally fatty acids neutralized with metal ions. The metal cation salts provide the cations capable of neutralizing (at varying levels) the carboxylic acid groups of the fatty acids. Examples include the sulfate, carbonate, acetate and hydroxide salts of metals such as barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, or calcium, and blends thereof. It is preferred the organic acids and salts be relatively non-migratory (they do not bloom to the surface of the polymer under ambient temperatures) and non-volatile (they do not volatilize at temperatures required for melt-blending).
The final thermoplastic ionomer compositions of this invention may contain additional materials such as, for example, a small amount of ionic plasticizer, which is particularly effective at improving the processability of the highly-neutralized ionomer. For example, the ionic plasticizer may be added in an amount of 0.5 to 10 pph, more preferably 1 to 5 pph. In addition to the fatty acids and salts of fatty acids discussed above, other suitable ionic plasticizers include, for example, polyethylene glycols, waxes, bis-stearamides, minerals, and phthalates. In another embodiment, an amine or pyridine compound is used, preferably in addition to a metal cation. Suitable examples include, for example, ethylamine, methylamine, diethylamine, tert-butylamine, dodecylamine, and the like.
Fillers, fibers, flakes also may be included in the final ionomer composition. Particularly preferred additives of this nature include, but are not limited to, very-high-surface-area fillers that have an affinity for the acid groups in ionomer. In particular, fillers, fibers or flakes having cationic nature such that they may also contribute to the neutralization of the ionomer are suitable. Aluminum oxide comprising fillers are preferred. Also, silica, fumed silica, or precipitated silica, such as those sold under the tradename HISIL from PPG Industries, or carbon black. Nano-scale materials are also preferred and include, but are not limited to, nanotubes, nanoflakes, nanofillers, or nanoclays.
Other additives and fillers include, but are not limited to, chemical blowing and foaming agents, optical brighteners, coloring agents, fluorescent agents, whitening agents, UV absorbers, light stabilizers, defoaming agents, processing aids, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, titanium dioxide, acid copolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide, barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinc carbonate, barium carbonate, tungsten, tungsten carbide, silica, lead silicate, regrind (recycled material), clay, mica, talc, nano-fillers, carbon black, glass flake, milled glass, and mixtures thereof. Suitable additives are more fully described in, for example, Rajagopalan et al., U.S. Patent Application Publication No. 2003/0225197, the entire disclosure of which is hereby incorporated herein by reference. In a particular embodiment, the total amount of additive(s) and filler(s) present in the final thermoplastic ionomer composition is 15 wt % or less, or 12 wt % or less, or 10 wt % or less, or 9 wt % or less, or 6 wt % or less, or 5 wt % or less, or 4 wt % or less, or 3 wt % or less, based on the total weight of the ionomer composition. In a particular aspect of this embodiment, the final thermoplastic ionomer composition includes filler(s) selected from carbon black, nanoclays (e.g., Cloisite® and Nanofil® nanoclays, commercially available from Southern Clay Products, Inc., and Nanomax® and Nanomer® nanoclays, commercially available from Nanocor, Inc.), talc (e.g., Luzenac HAR® high aspect ratio talcs, commercially available from Luzenac America, Inc.), glass (e.g., glass flake, milled glass, and microglass), mica and mica-based pigments (e.g., Iriodin® pearl luster pigments, commercially available from The Merck Group), and combinations thereof. In a particular embodiment, the final thermoplastic ionomeric composition is modified with organic fiber micropulp, as disclosed, for example, in Chen, U.S. Pat. No. 7,504,448, the entire disclosure of which is hereby incorporated herein by reference. In another version, the ionomer (or thermoplastic elastomer) compositions may contain carbon fibers or carbon fiber sheets comprising a weave of thin carbon fibers held together in a resin. In yet another version, the ionomer compositions may contain forged composite material composed of bundles of microscopic carbon fibers held together in a resin. These turbostratic carbon fibers are randomly dispersed in the resin. The structure of the forged composite material differs over traditional carbon fiber sheets. The forged composite material contains discontinuous fibers intertwined in the resin; while ordinary carbon fiber sheets are woven—they contain a weave of fibers. As a result, the forged composite material is very lightweight and has high mechanical strength.
Other suitable thermoplastic polymers that may be included in the non-Ionomer (thermoplastic elastomer) and ionomer compositions of this invention include, but are not limited to, the following polymers (including homopolymers, copolymers, and derivatives thereof.)
(a) polyesters, particularly those modified with a compatibilizing group such as sulfonate or phosphonate, including modified poly(ethylene terephthalate), modified poly(butylene terephthalate), modified polypropylene terephthalate), modified poly(trimethylene terephthalate), modified poly(ethylene naphthenate), and those disclosed in U.S. Pat. Nos. 6,353,050, 6,274,298, and 6,001,930, the entire disclosures of which are hereby incorporated herein by reference, and blends of two or more thereof;
(b) polyamides, polyamide-ethers, and polyamide-esters, and those disclosed in U.S. Pat. Nos. 6,187,864, 6,001,930, and 5,981,654, the entire disclosures of which are hereby incorporated herein by reference, and blends of two or more thereof;
(c) polyurethanes, polyureas, polyurethane-polyurea hybrids, and blends of two or more thereof;
(d) fluoropolymers, such as those disclosed in U.S. Pat. Nos. 5,691,066, 6,747,110 and 7,009,002, the entire disclosures of which are hereby incorporated herein by reference, and blends of two or more thereof;
(e) polystyrenes, such as poly(styrene-co-maleic anhydride), acrylonitrile-butadiene-styrene, poly(styrene sulfonate), polyethylene styrene, and blends of two or more thereof;
(f) polyvinyl chlorides and grafted polyvinyl chlorides, and blends of two or more thereof;
(g) polycarbonates, blends of polycarbonate/acrylonitrile-butadiene-styrene, blends of polycarbonate/polyurethane, blends of polycarbonate/polyester, and blends of two or more thereof;
(h) polyethers, such as polyarylene ethers, polyphenylene oxides, block copolymers of alkenyl aromatics with vinyl aromatics and polyamicesters, and blends of two or more thereof;
(i) polyimides, polyetherketones, polyamideimides, and blends of two or more thereof; and
(j) polycarbonate/polyester copolymers and blends.
Furthermore, the resulting thermoplastic compositions may contain natural and synthetic rubbers such as, for example, polybutadiene, polyisoprene, ethylene propylene rubber (EPR), ethylene propylene diene rubber (EPDM), styrene-butadiene rubber, styrenic block copolymer rubbers (such as “SI”, “SIS”, “SB”, “SBS”, “SIBS”, and the like, where “S” is styrene, “I” is isobutylene, and “B” is butadiene), polyalkenamers such as, for example, polyoctenamer, butyl rubber, halobutyl rubber, and polystyrene elastomers.
The ionomer compositions may contain a blend of two or more ionomers. For example, the composition may contain a 50/50 wt. % blend of two different highly-neutralized ethylene/methacrylic acid copolymers. In another version, the composition may contain a blend of one or more ionomers and a maleic anhydride-grafted non-ionomeric polymer. The non-ionomeric polymer may be a metallocene-catalyzed polymer. In another version, the composition contains a blend of a highly-neutralized ethylene/methacrylic acid copolymer and a maleic anhydride-grafted metallocene-catalyzed polyethylene. In yet another version, the composition contains a material selected from the group consisting of highly-neutralized ionomers optionally blended with a maleic anhydride-grafted non-ionomeric polymer; polyester elastomers; polyamide elastomers; and combinations of two or more thereof.
In accordance with the present invention, golf balls containing dual-cores formed from thermoplastic non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of: polyester-polyether block copolymers, polyether-polyamide block copolymers, and blends thereof and thermoplastic ionomer compositions containing acid groups neutralized to greater than 70% have several advantageous properties. For example, the compositions can be used to make a dual-core that provides the golf ball with good rebounding properties (distance) without sacrificing a nice feel to the ball. The resulting ball has a relatively high COR allowing it to reach high velocity when struck by a golf club. Thus, the ball tends to travel a greater distance which is particularly important for driver shots off the tee. At the same time, the compositions are not excessively hard and they help provide the ball with a soft and comfortable feel. The golf player experiences a better sense of control and natural feeling ball when making the shot. In general, the cores of this invention typically have a COR of about 0.76 or greater; and preferably about 0.80 or greater. The compression of the core preferably is about 50 to about 130, and more preferably in the range of about 70 to about 110.
Core Structure
As discussed above, the core is preferably a dual-core comprising an inner core (center) and surrounding outer core layer. In one preferred embodiment, the inner core is farmed from a thermoplastic elastomer composition, the thermoplastic elastomer being selected from the group consisting of: polyester-polyether block copolymers, polyether-polyamide block copolymers, and blends thereof; and an outer core comprising an ionomer composition comprising an ethylene acid copolymer containing acid groups neutralized to greater than 70%. In a second preferred version, the ionomer composition is used to form the inner core, while the thermoplastic elastomer is used to form the outer core. Preferably, the inner core has a center hardness (CH) within a range having a lower limit of 20 or 25 or 30 or 35 or 40 or 45 or 50 or 55 Shore D and an upper limit of 60 or 65 or 70 or 75 or 80 or 85 or 90 Shore D. The inner core (center) also preferably has a surface hardness (ICSH) within a range having a lower limit of 20 or 25 or 30 or 35 or 40 or 45 or 50 or 55 Shore D and an upper limit of 60 or 65 or 70 or 75 or 80 or 85 or 90 Shore D. Meanwhile, the outer core layer preferably has a surface hardness (OCLSH) within a range having a lower limit of 20 or 25 or 30 or 35 or 40 or 45 or 50 or 55 Shore D and an upper limit of 60 or 65 or 70 or 75 or 80 or 85 or 90 Shore D. In one embodiment, the surface hardness of the outer core layer is greater than the center hardness of the inner core. In an alternative embodiment, the center hardness of the inner core is greater than the surface hardness of the outer core layer.
Particularly, in one preferred instance, the center hardness of the inner core is in the range of about 25 to about 82 Shore D units and the surface hardness of the outer core is in the range of about 30 to about 87 Shore C units. More particularly, the center hardness of the inner core is about 25 Shore D units or greater and the surface hardness of the outer core is about 45 Shore D units or greater. In these instances, the surface hardness (outer core) is preferably at least 5 Shore D units greater than the center hardness (inner core).
In another instance, the center hardness of the inner core is about 45 Shore D units or greater and the surface hardness of the outer core is about 25 Shore D units or greater. In these instances, the center hardness (inner core) is preferably at least 5 Shore D units greater than the surface hardness (outer core).
In one preferred golf ball, the inner core (center) has a “positive” hardness gradient (that is, the outer surface of the inner core is harder than its geometric center) and the outer core layer has a “positive” hardness gradient (that is, the outer surface of the outer core layer is harder than the inner surface of the outer core layer.) In cases where both the inner core and outer core layer have “positive” hardness gradients, the outer surface hardness of the outer core layer is still preferably greater than the material hardness of the inner core (center).
In another version, the inner core (center) has a positive hardness gradient, while the outer core layer has a “negative” hardness gradient (that is, the outer surface of the outer core layer is softer than the inner surface of the outer core layer.) In yet another version, the outer core layer may have a “zero” hardness gradient. (That is, the hardness values of the outer surface of the outer core layer and the inner surface of the outer core layer are substantially the same.) Particularly, the term, “zero hardness gradient” as used herein, means a surface to center (or second surface) Shore C hardness gradient of less than 8, preferably less than 5 and most preferably less than 3 and may have a value of zero or negative 1 to negative 25. The term, “negative hardness gradient” as used herein, means a surface to center (or second surface) Shore C hardness gradient of less than zero. The terms, “zero hardness gradient” and “negative hardness gradient,” may be used herein interchangeably to refer to hardness gradients of negative 1 to negative 25. The term, “positive hardness gradient” as used herein, means a surface to center (or second surface) Shore C hardness gradient of 8 or greater, preferably 10 or greater, and most preferably 20 or greater. By the term, “steep positive hardness gradient” as used herein, it is meant surface to center (or second surface) Shore C hardness gradient of 20 or greater, more preferably 25 or greater, and most preferably 30 or greater. For example, the core may have a steep positive hardness gradient of 35, 40, or 45 Shore C or greater.
Preferably, the hardness gradient from geometric center of the inner core to the surface of the outer core layer is a positive hardness gradient. That is, the outer surface of the outer core layer is harder than the center of the inner core. Methods for measuring the hardness of the core and cover layers and determining the hardness gradients are discussed in further detail below.
As discussed above, the dual-core constitutes an inner core (center) and an outer core layer. The inner core preferably has a diameter within a range having a lower limit of 0.45 or 0.50 or 0.60 or 0.75 or 0.85 or 0.875 inches and an upper limit of 1.125 or 1.15 or 1.39 or 1.55 inches. The outer core layer encloses the inner core such that the two-layered core has an overall diameter within a range having a lower limit of 1.20 or 1.30 or 1.40 or 1.50 or 1.51 or 1.52 or 1.525 inches and an upper limit of 1.54 or 1.55 or 1.555 or 1.56 or 1.59 or 1.62 or 1.64 inches.
The inner core (center) preferably has a compression within a range having a lower limit of 10 or less, 20 or less, 30 or less, 40 or less, 50 or less; and an upper limit of 55 or greater, 65 or greater, 75 or greater, 80 or greater, 90 or greater, 100 or greater, 110 or greater, 120 or greater, 130 or greater, or 150 or greater.
Cover Structure
The golf ball cores of this invention may be enclosed with one or more cover layers. A wide variety of materials may be used for forming the outer cover including, for example, polyurethanes; polyureas; copolymers, blends and hybrids of polyurethane and polyurea; ethylene acid copolymer ionomer resins (for example, Surlyn® ionomer resins and HPF® 1000 and HPF® 2000, commercially available from DuPont; Iotek® ionomers, commercially available from ExxonMobil Chemical Company; Amplify® JO ionomers of ethylene acrylic acid copolymers, commercially available from The Dow Chemical Company; and Clarix® ionomer resins, commercially available from A. Schulman Inc.); polyethylene, including, for example, low density polyethylene, linear low density polyethylene, and high density polyethylene; polypropylene; rubber-toughened olefin polymers; acid copolymers, for example, poly(meth)acrylic acid, which do not become part of an ionomeric copolymer; plastomers; flexomers; styrene/butadiene/styrene block copolymers; styrene/ethylene-butylene/styrene block copolymers; dynamically vulcanized elastomers; copolymers of ethylene and vinyl acetates; copolymers of ethylene and methyl acrylates; polyvinyl chloride resins; polyamides, poly(amide-ester) elastomers, and graft copolymers of ionomer and polyamide including, for example, Pebax® thermoplastic polyether block amides, commercially available from Arkema Inc; cross-linked trans-polyisoprene and blends thereof; polyester-based thermoplastic elastomers, such as Hytrel®, commercially available from DuPont; polyurethane-based thermoplastic elastomers, such as Elastollan®, commercially available from BASF; synthetic or natural vulcanized rubber; and combinations thereof. Castable polyurethanes, polyureas, and hybrids of polyurethanes-polyureas are particularly desirable because these materials can be used to help make a golf ball having high resiliency and a soft feel. By the term, “hybrids of polyurethane and polyurea,” it is meant to include copolymers and blends thereof.
Polyurethanes, polyureas, and blends, copolymers, and hybrids of polyurethane/polyurea are also particularly suitable for forming cover layers. When used as cover layer materials, polyurethanes and polyureas can be thermoset or thermoplastic. Thermoset materials can be formed into golf ball layers by conventional casting or reaction injection molding techniques. Thermoplastic materials can be formed into golf ball layers by conventional compression or injection molding techniques.
In one preferred embodiment, the ball includes a dual-cover comprising inner and outer cover layers. The inner cover layer is preferably foamed from a composition comprising an ionomer or a blend of two or more ionomers that helps impart hardness to the ball. The inner cover layer preferably has a material hardness of 95 Shore C or less, or less than 95 Shore C, or 92 Shore C or less, or 90 Shore C or less, or a material hardness within a range having a lower limit of 60 or 65 or 70 or 75 or 80 or 84 or 85 Shore C and an upper limit of 90 or 92 or 95 Shore C. The thickness of the inner cover layer is preferably within a range having a lower limit of 0.010 or 0.015 or 0.020 or 0.030 inches and an upper limit of 0.035 or 0.045 or 0.080 or 0.120 inches. The outer cover layer preferably has a material hardness of 85 Shore C or less. The thickness of the outer cover layer is preferably within a range having a lower limit of 0.010 or 0.015 or 0.025 inches and an upper limit of 0.035 or 0.040 or 0.055 or 0.080 inches.
In a particular embodiment, the inner cover layer is formed from a composition comprising a high acid ionomer. A particularly suitable high acid ionomer is Surlyn 8150® (DuPont). Surlyn 8150® is a copolymer of ethylene and methacrylic acid, having an acid content of 19 wt %, which is 45% neutralized with sodium. In another particular embodiment, the inner cover layer is formed from a composition comprising a high acid ionomer and a maleic anhydride-grafted non-ionomeric polymer. A particularly suitable maleic anhydride-grafted polymer is Fusabond 525D® (DuPont), which is a maleic anhydride-grafted, metallocene-catalyzed ethylene-butene copolymer having about 0.9 wt % maleic anhydride grafted onto the copolymer. A particularly preferred blend of high acid ionomer and maleic anhydride-grafted polymer is a 84 wt %/16 wt % blend of Surlyn 8150® and Fusabond 525D®. Blends of high acid ionomers with maleic anhydride-grafted polymers are further disclosed, for example, in U.S. Pat. Nos. 6,992,135 and 6,677,401, the entire disclosures of which are hereby incorporated herein by reference.
In one embodiment, the inner cover layer is formed from a composition comprising a 50/45/5 blend of Surlyn® 8940/Surlyn® 9650/Nucrel® 960, and, in a particularly preferred embodiment, has a material hardness of from 80 to 85 Shore C. In another particular embodiment, the inner cover layer is formed from a composition comprising a 50/25/25 blend of Surlyn® 8940/Surlyn® 9650/Surlyn® 9910, preferably having a material hardness of about 90 Shore C. In another version, a blend of 50% Surlyn® 7940 and 50% Surlyn® 8940 is used to form the inner cover. In yet another particular embodiment, the inner cover layer is preferably formed from a composition comprising a 50/50 blend of Surlyn® 8940/Surlyn® 9650, preferably having a material hardness of about 86 Shore C. Surlyn® 8940 is an ethylene/methacrylic acid copolymer in which the MAA acid groups have been partially neutralized with sodium ions. Surlyn® 9650 and Surlyn® 9910 are two different grades of ethylene/methacrylic acid copolymer in which the MAA acid groups have been partially neutralized with zinc ions. Surlyn® 7940 is a copolymer of about 85% ethylene and 15% methacrylic acid that has been neutralized with lithium ions. Nucrel® 960 is an ethylene/methacrylic acid copolymer resin nominally made with 15 wt % methacrylic acid, and available from DuPont.
As discussed above, the dual-core of the golf ball may be enclosed with a single-layered or multi-layered covers. In one embodiment, a single-layered cover having a thickness in the range of about 0.015 to about 0.090 inches, more preferably about 0.030 to about 0.070 inches, is formed. The cover has a hardness of about Shore D 80 or less, more preferably 70 or less, and most preferably about 60 or less. In another embodiment, a multi-layered cover comprising inner and outer cover layers is formed, where the inner cover layer has a thickness of about 0.01 inches to about 0.06 inches, more preferably about 0.015 inches to about 0.040 inches, and most preferably about 0.02 inches to about 0.035 inches. In this version, the inner cover layer is formed from a partially- or fully-neutralized ionomer having a Shore D hardness of greater than about 55, more preferably greater than about 60, and most preferably greater than about 65. The outer cover layer, in this embodiment, preferably has a thickness of about 0.015 inches to about 0.055 inches, more preferably about 0.02 inches to about 0.04 inches, and most preferably about 0.025 inches to about 0.035 inches, with a hardness of about Shore D 80 or less, more preferably 70 or less, and most preferably about 60 or less. The inner cover layer is harder than the outer cover layer in this version. A preferred outer cover layer is a castable or reaction injection molded polyurethane, polyurea or copolymer, blend, or hybrid thereof having a Shore D hardness of about 40 to about 50. In another multi-layer cover, dual-core embodiment, the outer cover and inner cover layer materials and thickness are the same but, the hardness range is reversed, that is, the outer cover layer is harder than the inner cover layer.
Golf Ball Constructions
As discussed above, the thermoplastic non-ionomer and ionomer compositions of this invention may be used to form a core for any suitable ball construction, including, for example, three-piece, four-piece, and five-piece designs.
The core and cover compositions may be prepared using conventional mixing techniques. The core composition can be formed into an inner core structure by ordinary techniques such as, for example, injection or compression molding. After molding, the core structure is removed from the mold and its surface may be treated using techniques such as corona discharge, sand blasting, or grinding to improve adhesion of the surrounding layers. Injection molding or compression molding can be used to form an outer core layer and inner cover layer about the inner core to produce an intermediate golf ball. The cover layer(s) is subsequently molded over the inner/outer core to produce a final golf ball.
In compression molding, the outer core and/or inner cover composition is formed into smooth surfaced hemispherical shells which are then positioned around the inner core in a mold having the desired inner cover thickness and subjected to compression molding under heat followed by cooling. This process fuses the shells together to form a unitary intermediate ball. Alternatively, the intermediate balls may be produced by injection molding, wherein the outer core and/or inner cover layer is injected directly around the core placed at the center of an intermediate ball mold under heat and pressure. After molding, the golf balls produced may undergo various further processing steps such as buffing, painting and marking using conventional techniques to produce a finished ball.
Referring to FIG. 1, one version of a golf ball that can be made in accordance with this invention is generally indicated at (6). The ball (6) contains a dual-core (8) having an inner core (center) (8 a) and outer core layer (8 b) surrounded by a single-layered cover (10). The center (8 a) is formed from a thermoplastic elastomer composition. The outer core layer (8 b) is formed from an ethylene acid copolymer ionomer composition containing acid groups neutralized to greater than 70%. In FIG. 2, a golf ball (11) containing the above-described dual-core (8) is surrounded by a dual-cover (12) having an inner cover layer (12 a) and outer cover layer (12 b), which may be formed from any of the cover materials described above. Referring to FIG. 3, in another version, the golf ball (14) contains a dual-core (16) having an inner core (center) (16 a) and outer core layer (16 b) surrounded by a single-layered cover (18). The center (16 a) is formed from an ethylene acid copolymer ionomer composition containing acid groups neutralized to greater than 70%. The outer core layer (16 b) is formed from a thermoplastic elastomer composition. In FIG. 4, a golf ball (19) containing the above-described dual-core (16) is surrounded by a dual-cover (20) having an inner cover layer (20 a) and outer cover layer (20 b),
The surfaces of the golf balls shown in FIGS. 1-4 may have various dimple patterns to modify the aerodynamic properties of the ball. It should be understood the golf balls shown in FIGS. 1-4 are for illustrative purposes only and not meant to be restrictive. Other golf ball constructions can be made in accordance with this invention.
For example, a golf ball containing an inner core (center); an intermediate core layer; and an outer core layer may be made. The center preferably has a diameter within a range having a lower limit of 0.100 or 0.125 or 0.250 inches and an upper limit of 0.375 or 0.500 or 0.750 or 1.00 inches. The intermediate core layer preferably has a thickness within a range having a lower limit of 0.050 or 0.100 or 0.150 or 0.200 inches and an upper limit of 0.300 or 0.350 or 0.400 or 0.500 inches. The outer core layer encloses the center and intermediate core layer structure such that the multi-layer core has an overall diameter within a range having a lower limit of 1.40 or 1.45 or 1.50 or 1.55 inches and an upper limit of 1.58 or 1.60 or 1.62 or 1.66 inches.
In one embodiment, the center is made of a rubber material such as, for example, polybutadiene, polyisoprene, ethylene propylene rubber (EPR), ethylene propylene diene rubber (EPDM), styrene-butadiene rubber, styrenic block copolymer rubbers (such as “SI”, “SIS”, “SB”, “SBS”, “SIBS”, and the like, where “S” is styrene, “I” is isobutylene, and “B” is butadiene), polyalkenamers such as, for example, polyoctenamer, butyl rubber, halobutyl rubber, and polystyrene elastomers. Meanwhile; the intermediate core layer is made of a non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of polyester-polyether block copolymers and polyether-amide block copolymers and mixtures thereof. Finally, the outer core layer is made of an ethylene acid copolymer ionomer composition containing acid groups neutralized to greater than 70%.
In one embodiment, the center has an outer surface hardness of 70 Shore C or greater, more preferably a surface hardness of 80 Shore C or greater, and most preferably a surface hardness of 85 Shore C or greater. For example, the center may have an outer surface hardness within a range having a lower limit of 70 or 75 or 80 Shore C and an upper limit of 90 or 95 Shore C. The outer core layer may have an outer surface hardness that is less than that of the center and is preferably 50 Shore C or less; or 60 Shore C or less; or 70 Shore C or less; or 75 Shore C or less; or 80 Shore C or less. The intermediate layer preferably has an outer surface greater than that of the center and outer core layer. Preferably, the intermediate layer has a surface hardness of 80 Shore C or greater.
In another embodiment, the center is made of a rubber material as described above; the intermediate core layer is made of the ionomer composition containing acid groups neutralized to greater than 70%; and the outer core layer is made of thermoplastic elastomer composition as described above.
It is recognized that additional golf ball constructions can be made without departing from the spirit and scope of the present invention. For example, in one version, the inner core is made of a non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of polyester-polyether block copolymers and polyether-amide block copolymers and mixtures thereof. The intermediate core layer is made of an ethylene acid copolymer ionomer composition containing acid groups neutralized to greater than 70%; and the outer core layer is made of a rubber material as described above. In yet another version, the inner core is made of the above-mentioned ethylene acid copolymer ionomer composition; the intermediate core layer is made of the foregoing thermoplastic elastomer composition; and the outer core layer is made of a rubber material as described above.
Test Methods
Hardness.
The center hardness of a core is obtained according to the following procedure. The core is gently pressed into a hemispherical holder having an internal diameter approximately slightly smaller than the diameter of the core, such that the core is held in place in the hemispherical portion of the holder while concurrently leaving the geometric central plane of the core exposed. The core is secured in the holder by friction, such that it will not move during the cutting and grinding steps, but the friction is not so excessive that distortion of the natural shape of the core would result. The core is secured such that the parting line of the core is roughly parallel to the top of the holder. The diameter of the core is measured 90 degrees to this orientation prior to securing. A measurement is also made from the bottom of the holder to the top of the core to provide a reference point for future calculations. A rough cut is made slightly above the exposed geometric center of the core using a band saw or other appropriate cutting tool, making sure that the core does not move in the holder during this step. The remainder of the core, still in the holder, is secured to the base plate of a surface grinding machine. The exposed ‘rough’ surface is ground to a smooth, flat surface, revealing the geometric center of the core, which can be verified by measuring the height from the bottom of the holder to the exposed surface of the core, making sure that exactly half of the original height of the core, as measured above, has been removed to within 0.004 inches. Leaving the core in the holder, the center of the core is found with a center square and carefully marked and the hardness is measured at the center mark according to ASTM D-2240. Additional hardness measurements at any distance from the center of the core can then be made by drawing a line radially outward from the center mark, and measuring the hardness at any given distance along the line, typically in 2 mm increments from the center. The hardness at a particular distance from the center should be measured along at least two, preferably four, radial arms located 180° apart, or 90° apart, respectively, and then averaged. All hardness measurements performed on a plane passing through the geometric center are performed while the core is still in the holder and without having disturbed its orientation, such that the test surface is constantly parallel to the bottom of the holder, and thus also parallel to the properly aligned foot of the durometer.
The outer surface hardness of a golf ball layer is measured on the actual outer surface of the layer and is obtained from the average of a number of measurements taken from opposing hemispheres, taking care to avoid making measurements on the parting line of the core or on surface defects, such as holes or protrusions. Hardness measurements are made pursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plastic by Means of a Durometer.” Because of the curved surface, care must be taken to ensure that the golf ball or golf ball subassembly is centered under the durometer indenter before a surface hardness reading is obtained. A calibrated, digital durometer, capable of reading to 0.1 hardness units is used for the hardness measurements. The digital durometer must be attached to, and its foot made parallel to, the base of an automatic stand. The weight on the durometer and attack rate conforms to ASTM D-2240.
In certain embodiments, a point or plurality of points measured along the “positive” or “negative” gradients may be above or below a line fit through the gradient and its outermost and innermost hardness values. In an alternative preferred embodiment, the hardest point along a particular steep “positive” or “negative” gradient may be higher than the value at the innermost portion of the inner core (the geometric center) or outer core layer (the inner surface)—as long as the outermost point (i.e., the outer surface of the inner core) is greater than (for “positive”) or lower than (for “negative”) the innermost point (i.e., the geometric center of the inner core or the inner surface of the outer core layer), such that the “positive” and “negative” gradients remain intact.
As discussed above, the direction of the hardness gradient of a golf ball layer is defined by the difference in hardness measurements taken at the outer and inner surfaces of a particular layer. The center hardness of an inner core and hardness of the outer surface of an inner core in a single-core ball or outer core layer are readily determined according to the test procedures provided above. The outer surface of the inner core layer (or other optional intermediate core layers) in a dual-core ball are also readily determined according to the procedures given herein for measuring the outer surface hardness of a golf ball layer, if the measurement is made prior to surrounding the layer with an additional core layer. Once an additional core layer surrounds a layer of interest, the hardness of the inner and outer surfaces of any inner or intermediate layers can be difficult to determine. Therefore, for purposes of the present invention, when the hardness of the inner or outer surface of a core layer is needed after the inner layer has been surrounded with another core layer, the test procedure described above for measuring a point located 1 mm from an interface is used.
Also, it should be understood that there is a fundamental difference between “material hardness” and “hardness as measured directly on a golf ball.” For purposes of the present invention, material hardness is measured according to ASTM D2240 and generally involves measuring the hardness of a flat “slab” or “button” formed of the material. Surface hardness as measured directly on a golf ball (or other spherical surface) typically results in a different hardness value. The difference in “surface hardness” and “material hardness” values is due to several factors including, but not limited to, ball construction (that is, core type, number of cores and/or cover layers, and the like); ball (or sphere) diameter; and the material composition of adjacent layers. It also should be understood that the two measurement techniques are not linearly related and, therefore, one hardness value cannot easily be correlated to the other. Shore hardness (for example, Shore C or Shore D hardness) was measured according to the test method ASTM D-2240.
Compression. As disclosed in Jeff Dalton's Compression by Any Other Name, Science and Golf IV, Proceedings of the World Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) (“J. Dalton”), several different methods can be used to measure compression, including Atti compression, Riehle compression, load/deflection measurements at a variety of fixed loads and offsets, and effective modulus. For purposes of the present invention, “compression” refers to Atti compression and is measured according to a known procedure, using an Atti compression test device, wherein a piston is used to compress a ball against a spring. The travel of the piston is fixed and the deflection of the spring is measured. The measurement of the deflection of the spring does not begin with its contact with the ball; rather, there is an offset of approximately the first 1.25 mm (0.05 inches) of the spring's deflection. Very low stiffness cores will not cause the spring to deflect by more than 1.25 mm and therefore have a zero compression measurement. The Atti compression tester is designed to measure objects having a diameter of 42.7 mm (1.68 inches); thus, smaller objects, such as golf ball cores, must be shimmed to a total height of 42.7 mm to obtain an accurate reading. Conversion from Atti compression to Riehle (cores), Riehle (balls), 100 kg deflection, 130-10 kg deflection or effective modulus can be carried out according to the formulas given in J. Dalton. Compression may be measured as described in McNamara et al., U.S. Pat. No. 7,777,871, the disclosure of which is hereby incorporated by reference.
Coefficient of Restitution (“COR”).
The COR is determined according to a known procedure, wherein a golf ball or golf ball subassembly (for example, a golf ball core) is fired from an air cannon at two given velocities and a velocity of 125 ft/s is used for the calculations. Ballistic light screens are located between the air cannon and steel plate at a fixed distance to measure ball velocity. As the ball travels toward the steel plate, it activates each light screen and the ball's time period at each light screen is measured. This provides an incoming transit time period which is inversely proportional to the ball's incoming velocity. The ball makes impact with the steel plate and rebounds so it passes again through the light screens. As the rebounding ball activates each light screen, the ball's time period at each screen is measured. This provides an outgoing transit time period which is inversely proportional to the ball's outgoing velocity. The COR is then calculated as the ratio of the ball's outgoing transit time period to the ball's incoming transit time period (COR=V_out/V_in=T_in/T_out).
When numerical lower limits and numerical upper limits are set forth herein, it is contemplated that any combination of these values may be used. Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials and others in the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention.
All patents, publications, test procedures, and other references cited herein, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.
It is understood that the compositions and golf ball products described and illustrated herein represent only some embodiments of the invention. It is appreciated by those skilled in the art that various changes and additions can be made to compositions and products without departing from the spirit and scope of this invention. It is intended that all such embodiments be covered by the appended claims.

Claims

1. A golf ball, comprising:

a) an inner core layer formed from a non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of: polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof;

b) an outer core layer formed from an ionomer composition comprising an ethylene acid copolymer and containing acid groups such that greater than 70% of the acid groups are neutralized; and

c) a cover having at least one layer.

2. The golf ball of claim 1, wherein the non-ionomer composition is relatively flexible having a flex modulus of 1,000 to 50,000 psi and the ionomer composition is relatively stiff having a flex modulus of 20,000 psi to 150,000 psi, the flex modulus of the non-ionomer composition being less than the flex modulus of the ionomer composition.

3. The golf ball of claim 2, wherein the modulus of the non-ionomer elastomer composition is at least 10% less than the modulus of the ionomer composition.

4. The golf ball of claim 1, wherein the non-ionomer composition is relatively stiff having a flex modulus of 20,000 psi to 150,000 psi and the ionomer composition is relatively flexible having a flex modulus of 1,000 to 50,000 psi, the flex modulus of the non-ionomer composition being greater than the flex modulus of the ionomer composition.

5. The golf ball of claim 4, wherein the modulus of the non-ionomer composition is at least 10% greater than the modulus of the ionomer composition.

6. The golf ball of claim 1, wherein the center of the inner core and surface of the outer core layer each has a hardness, and the surface hardness of the outer core layer is greater than the center hardness of the inner core.

7. The golf ball of claim 6, wherein the center hardness of the inner core is about 25 Shore D units or greater and the surface hardness of the outer core is about 45 Shore D units or greater.

8. The golf ball of claim 6, wherein the center hardness of the inner core is in the range of about 25 to about 82 Shore D units and the surface hardness of the outer core is in the range of about 30 to about 87 Shore C units.

9. The golf ball of claim 1, wherein the center of the inner core and surface of the outer core layer each has a hardness, and the center hardness of the inner core is greater than the surface hardness of the outer core layer.

10. The golf ball of claim 1, wherein the cover is a single layer having a thickness of about 0.015 to about 0.090 inches and is formed from a thermoplastic or thermoset material.

11. The golf ball of claim 1, wherein the cover comprises two or more layers and has an overall thickness of about 0.020 to about 0.110 inches and wherein each cover layer is formed from a thermoplastic or thermoset material.

12. The golf ball of claim 1, wherein the cover comprises an inner cover layer and outer cover layer, the outer cover having a Shore D hardness of less than 65, the hardness of the outer cover being less than the hardness of the inner cover.

13. The golf ball of claim 1, wherein the cover is formed from a composition comprising a polymer selected from the group consisting of ethylene acid copolymer ionomers; polyesters; polyamides; polyamide-ethers, polyamide-esters; polyurethanes, polyureas; fluoropolymers; polystyrenes; polypropylenes and polyethylenes; polyvinyl chlorides; polyvinyl acetates; polycarbonates; polyvinyl alcohols; polyethers; polyimides, polyetherketones, polyamideimides; and mixtures thereof.

14. The golf ball of claim 1, wherein the inner core has a diameter in the range of about 0.050 to about 1.40 inches.

15. The golf ball of claim 1, wherein the outer core layer has a thickness in the range of about 0.020 to about 0.560 inches.

16. The golf ball of claim 1, wherein the dual-core core has an overall compression in the range of about 50 to about 130.

17. The golf ball of claim 16, wherein the dual-core has an overall compression in the range of about 70 to about 110.

18. A golf ball, comprising:

a) an inner core layer formed from an ionomer composition comprising an ethylene acid copolymer and containing acid groups such that greater than 70% of the acid groups are neutralized;

b) an outer core layer formed from a non-ionomer composition comprising a thermoplastic elastomer selected from the group consisting of polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof; and

c) a cover having at least one layer.

19. The golf ball of claim 18, wherein the ionomer composition is relatively stiff having a flex modulus of 20,000 psi to 150,000 psi and the non-ionomer composition is relatively flexible having s a flex modulus of 1,000 to 50,000 psi.

20. The golf ball of claim 19, wherein the modulus of the ionomer composition is at least 10% greater than the modulus of the non-ionomer composition.

21. The golf ball of claim 18, wherein the ionomer composition is relatively flexible having a flex modulus of 1,000 to 50,000 psi and the non-ionomer composition is relatively stiff having a flex modulus of 20,000 to 150,000 psi.

22. The golf ball of claim 21, wherein the modulus of the ionomer composition is at least 10% less than the modulus of the non-ionomer composition.

23. The golf ball of claim 18, wherein the center of the inner core and surface of the outer core layer each has a hardness, and the surface hardness of the outer core layer is greater than the center hardness of the inner core.

24. The golf ball of claim 23, wherein the center hardness of the inner core is about 20 Shore D units or greater and the surface hardness of the outer core is about 25 Shore D units or greater.

25. The golf ball of claim 23, wherein the center hardness of the inner core is in the range of about 20 to about 82 Shore D units and the surface hardness of the outer core is in the range of about 25 to about 87 Shore C units.

26. The golf ball of claim 18, wherein the center of the inner core and surface of the outer core layer each has a hardness, and the center hardness of the inner core is greater than the surface hardness of the outer core layer.

27. The golf ball of claim 18, wherein the cover is a single layer having a thickness of about 0.015 to about 0.090 inches and is formed from a thermoplastic or thermoset material.

28. The golf ball of claim 18, wherein the cover comprises two or more layers and has an overall thickness of about 0.020 to about 0.110 inches and wherein each cover layer is formed from a thermoplastic or thermoset material.

29. The golf ball of claim 18, wherein the dual-core core has an overall compression in the range of about 50 to about 130.

30. The golf ball of claim 29, wherein the dual-core has an overall compression in the range of about 70 to about 110.