US20100317462A1

US20100317462A1 - GOLF BALLS COMPRISING IONOMERS FORMED FROM POST-NEUTRALIZATION OF IN SITU Na/Zn IONOMERS WITH Li OR Ca CATIONS

Info

Publication number: US20100317462A1
Application number: US12/481,619
Authority: US
Inventors: Murali Rajagopalan; Michael J. Sullivan
Original assignee: Acushnet Co
Current assignee: Acushnet Co
Priority date: 2009-06-10
Filing date: 2009-06-10
Publication date: 2010-12-16

Abstract

The present invention is directed to compositions and methods relating to golf balls. In one embodiment, a golf ball can include a core and/or intermediate layer formed from a partially-neutralized in situ ionomer that is neutralized to a first level by a first cation, and is subsequently neutralized by a second, different cation to produce a further, more highly-neutralized ionomer. The further-neutralized ionomer exhibits decreased compression (softer) and/or increased COR (faster) compared to a comparative golf ball that contains a core or layer that is formed from an ionomer that is not subsequently neutralized with a second cation.

Description

BACKGROUND OF THE INVENTION

Golf ball core and cover layers are typically constructed with polymer compositions including, for example, polybutadiene rubber, polyurethanes, polyamides, ionomers, and blends thereof. Ionomers, particularly ethylene-based ionomers, have become a common choice of polymers for golf ball layers because of their toughness, durability, and wide range of hardness values. Conventional ionomers, which are typically formed, for example, from a copolymer of ethylene and an α,β-ethylenically unsaturated mono- or dicarboxylic acid, involve partial (<70 wt %) neutralization of at least one of the acid groups present in an acid copolymer. Higher neutralization (>70 wt %) has been generally considered impractical for use in golf balls, without the addition of long chain fatty acids or their salts as flow modifiers and cation sources, because of difficulties in melt processing. There remains a need, therefore, for developing novel ionomeric compositions that are suitable for use in golf ball layers and, in particular, at higher neutralizations.

SUMMARY OF THE INVENTION

The present invention is directed to golf ball comprising a core; a cover; and optionally, an intermediate layer disposed between the core and the cover. The core or intermediate layer may be formed from a further-neutralized ionomer having a neutralization greater than 70 wt % that is formed from a reaction product of a partially-neutralized in situ ionomer neutralized to less than 70% by a first and second cation and a sufficient amount of a third cation and, optionally, a suitable amount of fatty acid or a salt thereof, the third cation being different from the first and second cations.
Incorporation of the further-neutralized core and/or layers produces a golf ball has a decreased compression (softer), increased COR (faster), or both, compared to a golf ball including layers formed from a conventional ionomer. The compression is preferably decreased by at least about 2 Atti points, more preferably at least about 4 Atti points, most preferably at least about 6 Atti points. Concurrently or alternatively, the COR of the golf ball, when measured at an incoming velocity of 125 ft/s, is increased by at least about 0.004, more preferably at least about 0.006, most preferably at least about 0.010.
A precursor to the further-neutralized, the partially-neutralized in situ ionomer preferably includes a copolymer of ethylene and an α,β-ethylenically unsaturated mono- or dicarboxylic acid. The first and second cations are typically lithium, sodium, potassium, magnesium, calcium, barium, zinc, bismuth, chromium, cobalt, copper, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, or tin. The third cation includes calcium or lithium and is different from the first and/or second cation. In a preferred embodiment, the first and second cations comprise zinc or sodium and the third cation comprises calcium or lithium. The in situ ionomer can include an acrylic acid that is partially neutralized by Na or Zn cations.
In one embodiment, a ratio of a melt flow index of the in situ ionomer to a melt flow index of the further-neutralized ionomer is 1 to 20 g/10 min at 190° C. using a 2.16-kg load, preferably 2 to 10 g/10 min. Alternatively, a ratio of a flexural modulus of the in situ ionomer to a flexural modulus of the further-neutralized ionomer is 0.43 to 0.75, preferably 0.45 to 0.7. Still further, the further-neutralized ionomer composition may have a flexural modulus of 65,000 to 90,000 psi. A ratio of the neutralization level of the in situ ionomer to the neutralization level of the further-neutralized ionomer is typically 0.3 to 0.9, more preferably 0.31 to 0.85, most preferably 0.33 to 0.8. The further-neutralized ionomer is preferably neutralized by at least 80 wt %, more preferably greater than 90 wt %, most preferably from 95 to 100 wt %.
The present invention is also directed to a method for manufacturing a golf ball having decreased compression, increased COR, or both, comprising the steps of first, providing a partially-neutralized in situ ionomer neutralized to less than about 70% by a first cation and a second cation; and second, further neutralizing the partially-neutralized in situ ionomer with a third cation, different from the first and second cations, to produce a further-neutralized ionomer, where the first and second cations comprise Na or Zn and the third cation comprises Ca or Li, and the further-neutralized ionomer provides decreased compression of at least 2 Atti points, increased COR of at least 0.004, or both, compared to a golf ball comprising a layer formed from a conventional ionomer. The further-neutralized ionomer can provide decreased compression, increased COR, or a combination thereof, compared to a comparative golf ball that is not further neutralized with the third cation. Thus the golf balls made from a present invention produce soft and resilient golf balls.
There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying claims, or may be learned by the practice of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular process steps and materials disclosed herein because such process steps and materials may vary somewhat. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only. The terms are not intended to be limiting because the scope of the present invention is intended to be limited only by the appended claims and equivalents thereof.
It has been recognized that it would be advantageous to develop a golf ball comprising partially-neutralized in situ ionomers that are further neutralized. As such, a golf ball comprising a core and a cover and, optionally, an intermediate layer where the core and/or intermediate layer is formed from a further-neutralized ionomer formed from a reaction product of a partially-neutralized in situ ionomer having a first and second cation, a sufficient amount of a third cation and optionally a suitable amount of fatty acid or their salt. The further-neutralized ionomer can provide decreased compression, increased COR, or combinations thereof, compared to a comparative golf ball that is not subsequently neutralized with the third cation.
In another embodiment, a method for manufacturing a golf ball having decreased compression, increased COR, or combinations thereof, can comprise providing a partially-neutralized in situ ionomer neutralized by a first and second cation, and further neutralizing the partially neutralized in situ ionomer with a third cation to produce a further-neutralized ionomer. The further-neutralized ionomer can provide decreased compression, increased COR, or combinations thereof, compared to a comparative golf ball that is not further neutralized with the third cation.
It is noted that when discussing a partially-neutralized in situ ionomer, a further-neutralized ionomer, or a method of making such an ionomer, each of these discussions can be considered applicable to each of these embodiments, whether or not they are explicitly discussed in the context of that embodiment. Thus, for example, in discussing a polymer used in a partially-neutralized in situ ionomer, such a polymer can also be used in a further-neutralized ionomer, or a method for making such an ionomer, and vice versa.
The present golf balls can provide superior characteristics over a comparable golf ball that has not been further neutralized by the present methods. For example, it is believed that the present method of further neutralizing a partially-neutralized in situ monomer can provide an unexpected decrease in compression, increase in COR, or combinations thereof, over a comparative ball that has not been further neutralized. In one embodiment, the further neutralization can be performed with a third cation selected from the group consisting of calcium, lithium, and combinations thereof. As such, the first cation and the second cation and the third cation can have at least one different cation. Alternately, the first or second cation and the third cation cannot have a cation in common. In one embodiment, the first and the second cation can be selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, barium, zinc, bismuth, chromium, cobalt, copper, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, and mixtures thereof. In another embodiment, the first and the second cation can be zinc and/or sodium. In still another embodiment, the third cation can be calcium and/or lithium. In another embodiment, the third cation can be calcium. In yet another embodiment, the third cation can be lithium. Suitable cation sources include metal cations and salts thereof, organic amine compounds, ammonium, and combinations thereof. The amount of cation used in the composition can be readily determined by those skilled in the art based on the desired level of neutralization.
In one embodiment, the further-neutralized ionomer can provide decreased compression. The decreased compression can provide at least a 4 unit decrease in Atti compression over a comparative 1.0″ in diameter solid sphere. In yet another embodiment, the further-neutralized ionomer can provide increased COR. The increased COR can provide at least a 0.01 unit increase in COR over a comparative 1.0″ in diameter solid sphere. In still another embodiment, the further-neutralized ionomer can provide the decreased compression of at least a 4 unit in Atti compression over a comparative 1.0″ in diameter solid sphere, and the increased COR of at least a 0.04 unit over a comparative 1.0″ in diameter solid sphere.
In another embodiment, the ratio of the melt flow index of the in situ ionomer to the melt flow index of the further-neutralized ionomer is 0.5 to 50 g/10 min, preferably 1 to 20 g/10 min, more preferably 2 to 10 g/10 min, where the melt flow index of the samples were measured at 190° C. using a 2.16-kg load (ASTM D-1238). In another embodiment, the further-neutralized ionomer composition has a second melt flow index of 0.1 to 10 g/10 min, preferably 0.5 to 8.0 g/10 min, and more preferably 0.9 to 4.5 g/10 min, measured at 190° C. using a 2.16-kg load.
In an alternative embodiment, the ratio of the material hardness (in Shore D) of the in situ ionomer to the material hardness (in Shore D) of the further-neutralized ionomer is 0.4 to 1.5, preferably 0.5 to 1.3, more preferably 0.6 to 1.2, where the Shore D hardness of the samples were measured on compression molded plaques using ASTM D-2240. In another embodiment, the further-neutralized ionomer composition has a material hardness of 45 to 75 Shore D, preferably 55 to 70 Shore D, and more preferably 60 to 69 Shore D.
In another embodiment, the ratio of the flexural modulus of the in situ ionomer to the flexural modulus of the further-neutralized ionomer is 0.4 to 0.85, preferably 0.43 to 0.75, more preferably 0.45 to 0.7, where the flexural modulus of the samples were measured on compression molded plaques using ASTM D-790. In another embodiment, the further-neutralized ionomer composition has a flexural modulus of 60,000 to 100,000 psi, preferably 65,000 to 90,000 psi, and more preferably 65,000 to 75,000 psi.
In another embodiment, the ratio of the neutralization level of the in situ ionomer to the neutralization level of the further-neutralized ionomer is 0.3 to 0.9, preferably 0.31 to 0.85, more preferably 0.33 to 0.8. In another embodiment, the acid groups in the further-neutralized ionomer composition are neutralized by at least 80 wt %, preferably 85 wt %, more preferably 90 wt %, and most preferably 95 to 100 wt %.
The golf balls of the present invention comprise acid polymers that have been at least partially neutralized in situ to form partially-neutralized in situ ionomers before being further neutralized. Additionally, the partially-neutralized in situ ionomers can include an ionic plasticizer as described herein. The partially-neutralized in situ ionomers or acid polymers can generally be homopolymers or copolymers of α,β-ethylenically unsaturated mono- or dicarboxylic acids, including combinations thereof. Non-limiting examples of 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 currently most common. In one embodiment, the partially neurtralized ionomer can be in-situ neutralized by Na/Zn cations such as Exxon Mobil's EX5402.
U.S. Patent Application Publication No. 2003/0114565 and U.S. Patent Application Publication No. 2003/0050373, which are each incorporated by reference herein in their entireties, discuss soft, high resilient ionomers, which can be prepared from neutralizing the acid copolymer(s) of at least one E/X/Y copolymer, where E can be ethylene, X is the α,β-ethylenically unsaturated carboxylic acid, and Y can be a softening co-monomer. X can be present in 2-30 (preferably 4-20, most preferably 5-15) wt % of the polymer, and Y can be present in 17-40 (preferably 20-40, and more preferably 24-35) wt % of the polymer. The melt index (“MI”) of the base resin can be at least 20, at least 40, at least 75, or even at least 150. Particular soft, resilient ionomers included in this disclosure can be partially-neutralized ethylene/(meth)acrylic acid/butyl(meth)acrylate copolymers having an MI and level of neutralization that results in a melt processible polymer that has useful physical properties. When used, a softening monomer can typically be an alkyl (meth) acrylate, wherein the alkyl groups have from 1 to 8 carbon atoms. Specific non-limiting examples of E/X/Y-type copolymers are those where 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. Particularly suitable 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. In another aspect, the acid polymer can be ethylene-acrylic or (meth) acrylic copolymers or terpolymers (e.g., an alkyl ester such as butyl acrylate).
As mentioned, the copolymers can be partially neutralized, and then further neutralized in accordance with embodiments of the present disclosure. In one embodiment, the acid copolymers can be partially neutralized by at least 40%, at least 55%, or even at least 65% before being further neutralized. Additionally, the partially-neutralized in situ ionomers can be further neutralized to at least 70%, at least 80%, at least 95%, or even about 100%. As such, the partially-neutralized in situ ionomers can be further neutralized from partially-neutralized to highly-neutralized ionomers. In one embodiment, about 100% of the acid moiety of the acid copolymer can be neutralized by one or more alkali metal, transition metal, or alkaline earth metal cations.
Further examples of suitable ionomers that can be used include SURLYN® ionomers, from DuPont, DE; ACLYN® ionomers, from Honeywell International Inc, NJ.; IOTEK® ionomers, from Exxon Mobil Chemical Company, TX; CLARIX® ionomers, from A. Schulman, OH. Also, included are the acid copolymers described in U.S. Pat. No. 6,953,820, which is hereby incorporated herein by reference. Polymer or ionomer types include those known in the art, e.g., block copolymers, random copolymers, alternate copolymers, graft polymers, etc.
Additionally, the compositions described herein may contain fatty acids or salts thereof, polyhydric alcohols, or other plasticizers, which can improve processability, though these materials may also be processible without them. If used, organic acids can be blended or melt-blended with other ionomers or polymers as an unmodified or modified organic acid or salt thereof. Typically, the organic acids or salts thereof can be aliphatic, monofunctional organic acids having from 6 to 36 carbon atoms per molecule. These organic acids can be partially neutralized or fully neutralized. The organic acids can typically also be non-volatile and non-migratory. Non-limiting examples of suitable fatty acid as the organic acid can include caproic acid, caprylic acid, capric acid, lauric acid, palmitic acid, stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid, and salts thereof. The salts of organic acids of the present invention include the salts of barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, or calcium, salts of fatty acids, particularly stearic, behenic, erucic, oleic, linoelic or dimerized derivatives thereof, and mixtures thereof. In one embodiment of the present disclosure, the composition can be substantially free of fatty acids and their salts. However, fatty acids and salts thereof may be used in the composition without departing from the spirit of the invention. As such, in one embodiment, the composition can comprise a fatty acid, or salt thereof, in an amount of about 10 wt % to about 50 wt %. In another embodiment, the organic acid can be selected from the group consisting of aliphatic organic acids, aromatic organic acids, saturated mono-functional organic acids, unsaturated mono-functional organic acids, and multi-unsaturated mono-functional organic acids.
Additionally, the golf balls of the present invention can comprises ionomeric copolymers and terpolymers, ionomer precursors, thermoplastics, thermoplastic elastomers, polybutadiene rubber, balata, grafted metallocene-catalyzed polymers, non-grafted metallocene-catalyzed polymers, single-site polymers, high-crystalline acid polymers and their ionomers, anionic ionomers, cationic ionomers, and mixtures thereof.
Golf balls of the present invention can include one-piece, two-piece, multi-layer, and wound golf balls having a variety of core structures, intermediate layers, covers, and coatings. Golf ball cores may comprise a single, unitary layer, comprising the entire core from the center of the core to its outer periphery. Alternatively, the cores may consist of a center surrounded by at least one outer core layer. The center, innermost portion of such multi-layer cores is most often solid, but may be hollow or liquid-, gel-, or gas-filled. The outer core layer may be solid, or it may be a wound layer formed of a tensioned elastomeric material. Golf ball covers may also include one or more layers, such as a double cover having an inner and outer cover layer. Optionally, additional intermediate layers may be disposed between the core and cover. In one embodiment of the present invention, golf ball includes a core and a cover layer. In another embodiment, the golf ball includes a core, an intermediate layer, and a cover layer. The golf balls can include those materials and constructions as described in U.S. Patent Application Publication No. 2007/0232414 and U.S. Pat. No. 6,939,907, each of which is incorporated herein by reference in their entireties.
As discussed herein, the present further-neutralized ionomers can comprise, consist essentially of, or consist of any layer of the golf ball. As such, in one embodiment, the further-neutralized ionomers can be in the core. In another embodiment, the further-neutralized ionomers can be in the cover. In still another embodiment, the further-neutralized ionomers can be in an intermediate layer, e.g., outer core layer or inner cover layer.
Additionally, the copolymers/ionomers described herein can have a melt flow index of at least 0.5 g/10 min at 190° C. using an ASTM D-1238 method. More particularly, the melt flow index of the copolymers described herein can be from 0.5 g/10 min to 10.0 g/10 min, such as from 1.0 g/10 min to 5.0 g/10 min, and in some cases from 1.0 g/10 min to 4.0 g/10 min.
The cover layer, or any layer of a multiple layer cover, can be formed of suitable polymers such as the copolymers described herein, polyurethanes, or polyureas. The outer cover layer and/or the inner cover layer can comprise a light stable polyurethane, polyurea, and/or the copolymers described herein.
In one embodiment, golf balls of the present invention can be multi-layer balls having a compression or injection molded rubber or thermoplastic material such as a highly neutralized polymer core, at least one injection or compression molded intermediate layer which comprises a further-neutralized ionomer, and a cast or reaction injection molded polyurethane or polyurea outer cover layer. The rubber core composition comprises a base rubber, a crosslinking agent, a filler, and a co-crosslinking or initiator agent. Typical base rubber materials include natural and synthetic rubbers, including, but not limited to, polybutadiene and styrene-butadiene. The crosslinking agent typically includes a metal salt, such as a zinc salt or magnesium salt, of an acid having from 3 to 8 carbon atoms, such as (meth) acrylic acid. The initiator agent can be any known polymerization initiator which decomposes during the cure cycle, including, but not limited to, dicumyl peroxide, 1,1-di-(t-butylperoxy) 3,3,5-trimethyl cyclohexane, a-a bis-(t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5 di-(t-butylperoxy) hexane or di-t-butyl peroxide, and mixtures thereof. Suitable types and amounts of base rubber, crosslinking agent, filler, co-crosslinking agent, and initiator agent are more fully described in, for example, U.S. Pat. No. 6,939,907, the entire disclosure of which is hereby incorporated herein by reference. Reference is also made to U.S. Pat. No. 6,939,907 for additional ball constructions and materials that can be used in golf ball core, intermediate, and cover layers of the present invention.
The 1.0″ in diameter solid spheres of the present disclosure can have a coefficient of restitution (“COR”) of at least 0.700, such as at least 0.740, in some cases at least 0.760, and even other cases at least 0.800. COR is defined as the ratio of the rebound velocity to the inbound velocity when balls are fired into a rigid plate. In determining COR, the inbound velocity is understood to be 125 ft/s.
Various properties of the golf ball can dramatically affect performance. These properties can be a result of the particular materials and golf ball design chosen. Accordingly, the present disclosure can have a center having a diameter of from 1.00 inches to 1.63 inches and an Atti compression of from 40 to 160. Most often, the center has a surface hardness of from 20 Shore D to 70 Shore D. When present, the intermediate layer can generally have a material hardness of from 30 Shore D to 80 Shore D. Although other dimensions can be used, the intermediate layer typically has a thickness of from 0.02 inches to 0.09 inches, more often from 0.01 in to.0.06 inches.
The present golf balls of the present invention typically have a flexural modulus of from 3,000 psi to 200,000 psi, such as from 5,000 psi to 150,000 psi, in some cases from 10,000 psi to 125,000 psi, and in other cases from 10,000 psi to 100,000 psi and in some cases from 25,000 to 80,000 psi and in some cases from 45,000 to 70,000 psi. The material hardness of the present compositions can generally be from 30 Shore D to 80 Shore D, more often from 40 Shore D to 75 Shore D, and in some cases from 45 Shore D to 70 Shore D and in some cases from 55 to 68 Shore D.
The golf balls of the present invention can also include one or more other additives. Suitable additives 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, mica, talc, nano-fillers, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, TiO₂, acid copolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide, barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinc carbonate, barium carbonate, clay, tungsten, tungsten carbide, silica, lead silicate, regrind (recycled material), and mixtures thereof. Suitable additives are more fully described in, for example, U.S. Pat. No. 7,041,721, the entire disclosure of which is hereby incorporated herein by reference. Other optional additives can include fibers, flakes, particulates, microspheres, pre-expanded beads of glass, ceramic, metal or polymer, and the like which may be optionally foamed. If present, such additives can be included in an amount of from 0.01 wt % to 60 wt %, based on the total weight of the composition.
The foregoing detailed description describes the invention with reference to specific exemplary embodiments. However, it will be appreciated that various modifications and changes can be made without departing from the scope of the present invention as set forth in the appended claims. The detailed description is to be regarded as merely illustrative, rather than as restrictive, and all such modifications or changes, if any, are intended to fall within the scope of the present invention as described and set forth herein.

EXAMPLES

The following examples illustrate embodiments of the invention that are presently known. Thus, these examples should not be considered as limitations of the present invention, but are merely in place to teach how to make compositions of the present invention. As such, a representative number of compositions and their method of manufacture are disclosed herein.

Example 1

Preparation of Further-Neutralized Ionomer and Comparative Ionomer: an in situ ionomer, such as IOTEK® EX5402 from Exxon (a partially-neutralized ethylene-acrylic acid ionomer with Zn/Na counter cations) was fed into a twin-screw extruder followed by the addition of a sufficient amount of lithium hydroxide monohydrate and stearic acid as a melt flow modifier. The composition was mixed well in the extruder with the use of 2- and 3-lobe kneading mixing elements, achieving about 90 to 100% neutralization.
The resulting further-neutralized pellets were molded into a 1.0-inch-diameter solid sphere (i.e., a golf ball core) for comparative testing to a conventional partially-neutralized (<70 wt %) ionomer. The results of this comparison test (for 2-week-aged samples) are presented in Table 1, below.

TABLE 1

	Comparative	Further-Neutralized
Characteristic	Ionomer	Ionomer

Compression (Atti)	138	134
COR (at 125 ft/s	0.743	0.753
incoming velocity)

The further-neutralized ionomer exhibited a decrease in compression (making it a softer core) and a concurrent increase in COR (making it a faster core). For many golf ball constructions, solely a decrease in compression (without loss in COR) or an increase in COR (with an increase in compression) is desirable - achieving both a softer and faster core is obviously preferred.

Example 2

Preparation of Further-Neutralized Ionomers: an in situ ionomer, such as IOTEK® EX5402 from Exxon (a partially-neutralized ethylene-acrylic acid ionomer with Zn/Na counter cations) was fed into a twin-screw extruder followed by the addition of a suitable amount of calcium hydroxide and zinc stearate (a melt flow modifier). The composition was mixed well in the extruder with the use of 2 and 3 lobe kneading mixing elements, achieving about 90 to 100% neutralization.
The resulting further-neutralized pellets were molded into a 1.0-inch-diameter solid sphere for a comparative testing along with a partially-neutralized in situ ionomer. Test results for each composition is presented in Table 2, below.

TABLE 2

		Further-
	Comparative	Neutralized		Further-
	Ionomer 1	Ionomer 1	Comparative	Neutralized
Characteristic	(IOTEK ®)	(IOTEK ®)	Ionomer 2	Ionomer 2

Compression	154	139	156	141
(Atti)
COR (at	0.741	0.763	0.746	0.784
125 ft/s
incoming
velocity)

As in Table 1 above, the further-neutralized ionomers in Table 2 also exhibited a decrease in compression (making it a softer core) with a concurrent increase in COR (making it a faster core).
The golf ball of the invention also has a cover formed over the core (single or multi-layer core). The cover may be a single outer cover layer or a multi-layer cover, such as one having an inner cover layer and an outer cover layer. Suitable cover layer materials include, but are not limited to, ionomer resins and blends thereof (e.g., SURLYN® ionomer resins and DuPont HPF 1000 and HPF 2000; IOTEK® ionomers from Exxon Mobil; AMPLIFY® IO ionomers of ethylene acrylic acid copolymers from Dow; and CLARIX® ionomer resins from Schulman); polyurethanes; polyureas; copolymers and hybrids of polyurethane and polyurea; polyethylene, including, for example, low density polyethylene, linear low density polyethylene, and high density polyethylene; polypropylene; rubber-toughened olefin polymers; acid copolymers, e.g., (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; ethylene vinyl acetates; ethylene methyl acrylates; polyvinyl chloride resins; polyamides, amide-ester elastomers, and graft copolymers of ionomer and polyamide, including, for example, PEBAX® thermoplastic polyether block amides from Arkema, Inc.; crosslinked trans-polyisoprene and blends thereof; polyester-based thermoplastic elastomers, such as HYTREL® from DuPont; polyurethane-based thermoplastic elastomers, such as ELASTOLLAN® from BASF; synthetic or natural vulcanized rubber; and combinations thereof. In a particular embodiment, the cover is a single layer formed from a composition selected from the group consisting of ionomers, polyester elastomers, polyamide elastomers, and combinations of two or more thereof.
Compositions comprising an ionomer or a blend of two or more ionomers are particularly suitable cover materials. Preferred ionomeric outer cover compositions include, but are not limited to:

- (a) a composition comprising a “high acid ionomer” (i.e., having an acid content of greater than 16 wt %), such as SURLYN® 8150;
- (b) a composition comprising a high acid ionomer and a maleic anhydride-grafted non-ionomeric polymer (e.g., FUSABOND® functionalized polymers). 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®;
- (c) a composition comprising a 50/45/5 blend of SURLYN® 8940/SURLYN® 9650/NUCREL® 960, preferably having a material hardness of from 80 to 85 Shore C;
- (d) 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;
- (e) a composition comprising a 50/50 blend of SURLYN® 8940/SURLYN® 9650, preferably having a material hardness of about 86 Shore C;
- (f) a composition comprising a blend of SURLYN® 7940/SURLYN® 8940, optionally including a melt flow modifier;
- (g) a composition comprising a blend of a first high acid ionomer and a second high acid ionomer, wherein the first high acid ionomer is neutralized with a different cation than the second high acid ionomer (e.g., 50/50 blend of SURLYN 8150 and SURLYN® 9150), optionally including one or more melt flow modifiers such as an ionomer, ethylene-acid copolymer or ester terpolymer; and
- (h) a composition comprising a blend of a first high acid ionomer and a second high acid ionomer, wherein the first high acid ionomer is neutralized with a different cation than the second high acid ionomer, and from 0 to 10 wt % of an ethylene/acid/ester ionomer wherein the ethylene/acid/ester ionomer is neutralized with the same cation as either the first high acid ionomer or the second high acid ionomer or a different cation than the first and second high acid ionomers (e.g., a blend of 40-50 wt % SURLYN® 8140, 40-50 wt % SURLYN® 9120, and 0-10 wt % SURLYN® 6320).

Ionomeric outer cover compositions can be blended with non-ionic thermoplastic resins, particularly to manipulate product properties. Examples of suitable non-ionic thermoplastic resins include, but are not limited to, polyurethane, poly-ether-ester, poly-amide-ether, polyether-urea, thermoplastic polyether block amides (e.g., PEBAX® block copolymers from Arkema, Inc.), styrene-butadiene-styrene block copolymers, styrene(ethylene-butylene)-styrene block copolymers, polyamides, polyesters, polyolefins (e.g., polyethylene, polypropylene, ethylene-propylene copolymers, polyethylene-(meth)acrylate, plyethylene-(meth)acrylic acid, functionalized polymers with maleic anhydride grafting, FUSABOND® functionalized polymers from DuPont, functionalized polymers with epoxidation, elastomers (e.g., ethylene propylene diene monomer rubber, metallocene-catalyzed polyolefin) and ground powders of thermoset elastomers. Ionomer golf ball cover compositions may include a flow modifier, such as, but not limited to, NUCREL® acid copolymer resins, and particularly NUCREL® 960, from DuPont.
Polyurethanes, polyureas, and blends 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.
While the inventive golf ball may be formed from a variety of differing cover materials, preferred outer cover layer materials include, but are not limited to, (1) polyurethanes, such as those prepared from polyols or polyamines and diisocyanates or polyisocyanates and/or their prepolymers, and those disclosed in U.S. Pat. Nos. 5,334,673 and 6,506,851; (2) polyureas, such as those disclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794; (3) polyurethane-urea hybrids, blends or copolymers comprising urethane or urea segments; and (4) other suitable polyurethane compositions comprising a reaction product of at least one polyisocyanate and at least one curing agent are disclosed in U.S. Pat. Nos. 7,105,610 and 7,491,787, all of which are incorporated herein by reference.
It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
As used herein, the term “neutralized,” and any derivatives of the term, refer to the removal of an acidic proton from an acid functional group. Additionally, “neutralized” can include the exchange of one ion for another ion by ion-hopping. The degree to which a polymer is neutralized is measured as a weight percentage of total acid groups present within the polymer that have had their acidic proton removed.
As used herein, the term “partially neutralized” refers to a polymer that has at least one acid functional group neutralized and less than 70% of such acid functional groups neutralized.
As used herein, the term “highly neutralized” refers to a polymer that has at least 80% and preferably 90% and most preferably 95% of its acid functional groups neutralized.
As used herein, the term “subsequently neutralized” refers to polymer that is partially neutralized, and after at least some neutralization occurs (not necessarily all neutralization provided by a particular cation) additional neutralization is brought about using at least one different cation so that the polymer becomes highly neutralized, as defined herein.
As used herein, the term “polymer” generally refers to any polymer including homopolymers, copolymers, terpolymers, ionomers, etc., and may refer to any structure including block, alternate, random, graft, etc. unless the context dictates otherwise.
As used herein, the term “copolymer” includes polymers copolymerized using at least two types of monomers, e.g., two monomer types, three monomer types, more than three monomer types, etc.
As used herein, the term “ionomer” refers to an acid polymer or copolymer that has at least one acid group neutralized. As such, when discussing ionomers and acid polymers/copolymers, such discussions are generally interchangeable with the understanding that the ionomer contains at least one neutralized acid group.
As used herein, the term “Atti compression” or “compression” can be used interchangeably and is defined as the deflection of an object or material relative to the deflection of a calibrated spring, as measured with an Atti Compression Gauge, which is commercially available from Atti Engineering Corp. of Union City, N.J. Such a method is known in the golf ball arts.
As used herein, the term “(meth) acrylic acid” refers to methacrylic acid and/or acrylic acid. Likewise, “(meth) acrylate” refers to methacrylate and/or acrylate.
As used herein, the term “about” is used to provide flexibility to a numerical range endpoint by providing that a given value may be “a little above” or “a little below” the endpoint. The degree of flexibility of this term can be dictated by the particular variable and would be within the knowledge of those skilled in the art to determine based on experience and the associated description herein.
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.
As used herein, the term “substantially” or “substantial” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking, the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of action, characteristic, property, state, structure, item, or result. For example, a composition that is “substantially free of” particles would either completely lack particles, or so nearly completely lack particles that the effect would be the same as if it completely lacked particles. In other words, a composition that is “substantially free of” an ingredient or element may still contain such an item as long as there is no measurable effect thereof.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a defacto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.
Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of “about 1 wt % to about 5 wt %” should be interpreted to include not only the explicitly recited values of about 1 wt % to about 5 wt %, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3.5, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same principle applies to ranges reciting only one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.
In the present disclosure, any steps recited in any method or process claims may be executed in any order and are not limited to the order presented unless specified.
While the invention has been described with reference to certain preferred embodiments, those skilled in the art will appreciate that various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the invention. It is intended, therefore, that the invention be limited only by the scope of the following claims.

Claims

1. A golf ball comprising:

a core;

a cover; and

optionally, an intermediate layer disposed between the core and the cover,

wherein the core or the optional intermediate layer comprises a further-neutralized ionomer having a neutralization greater than 70 wt % formed from a reaction product of:

a partially-neutralized in situ ionomer neutralized to less than 70% by a first and second cation; and

a sufficient amount of a third cation and, optionally, a suitable amount of fatty acid or a salt thereof, the third cation being different from the first and second cations.

2. The golf ball of claim 1, wherein the golf ball has a decreased compression, increased COR, or both, compared to a golf ball comprising a conventional ionomer.

3. The golf ball of claim 2, wherein the compression is decreased by at least about 2 Atti points.

4. The golf ball of claim 2, wherein the COR, when measured at an incoming velocity of 125 ft/s, is increased by at least about 0.004.

5. The golf ball of claim 1, wherein the partially-neutralized in situ ionomer comprises a copolymer of ethylene and an α,β-ethylenically unsaturated mono- or dicarboxylic acid.

6. The golf ball of claim 1, wherein the first and second cations comprise lithium, sodium, potassium, magnesium, calcium, barium, zinc, bismuth, chromium, cobalt, copper, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, or tin.

7. The golf ball of claim 1, wherein the third cation comprises calcium or lithium.

8. The golf ball of claim 1, wherein the first and second cations comprise zinc or sodium and the third cation comprises calcium or lithium.

9. The golf ball of claim 1, wherein the in situ ionomer comprises an acrylic acid that is partially neutralized by Na or Zn cations.

10. The golf ball of claim 1, wherein a ratio of a melt flow index of the in situ ionomer to a melt flow index of the further-neutralized ionomer is 1 to 20 g/10 min at 190° C. using a 2.16-kg load.

11. The golf ball of claim 10, wherein the ratio is 2 to 10 g/10 min.

12. The golf ball of claim 1, wherein a ratio of a flexural modulus of the in situ ionomer to a flexural modulus of the further-neutralized ionomer is 0.43 to 0.75.

13. The golf ball of claim 12, wherein the ratio is 0.45 to 0.7.

14. The golf ball of claim 1, wherein the further-neutralized ionomer composition has a flexural modulus of 65,000 to 90,000 psi.

15. The golf ball of claim 1, wherein a ratio of the neutralization level of the in situ ionomer to the neutralization level of the further-neutralized ionomer is 0.3 to 0.9.

16. The golf ball of claim 15, wherein the ratio is 0.31 to 0.85.

17. The golf ball of claim 16, wherein the ratio is 0.33 to 0.8.

18. The golf ball of claim 1, wherein the further-neutralized ionomer is neutralized by at least 80 wt %.

19. The golf ball of claim 18, wherein the further-neutralized ionomer is neutralized to 90 to 100 wt %.

20. A method for manufacturing a golf ball having decreased compression, increased COR, or both, comprising the steps of:

providing a partially-neutralized in situ ionomer neutralized to less than about 70% by a first cation and a second cation; and

further neutralizing the partially-neutralized in situ ionomer with a third cation, different from the first and second cations, to produce a further-neutralized ionomer,

wherein the first and second cations comprise Na or Zn and the third cation comprises Ca or Li, and the further-neutralized ionomer provides decreased compression of at least 2 Atti points, increased COR of at least 0.004, or both, compared to a golf ball comprising a layer formed from a conventional ionomer.