Highly-neutralized thermoplastic copolymer center for improved multi-layer core golf ball   

This application is a continuation of co-pending U.S. patent application Ser. No. 11/347,456, filed Feb. 3, 2006, which is a continuation-in-part of U.S. Pat. No. 7,230,045, filed Oct. 24, 2002, which is a continuation-in-part of co-pending U.S. Pat. No. 6,939,907, filed Feb. 6, 2003, which is a continuation-in-part of U.S. Pat. No. 6,756,436, filed Apr. 9, 2002, which claims priority to U.S. Provisional Patent Application No. 60/301,046, filed Jun. 26, 2001, now abandoned, the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to golf ball compositions and, in particular, polymer compositions including highly-neutralized polymers and blends thereof.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solid and wound. Solid golf balls include one-piece, two-piece (i.e., solid core and a cover), and multi-layer (i.e., solid core of one or more layers and/or a cover of one or more layers) golf balls. Wound golf balls typically include a solid, hollow, or fluid-filled center, surrounded by a tensioned elastomeric material, and a cover. It is also possible to surround a hollow or fluid-filled center with a plurality of solid layers. Solid balls have traditionally been considered longer and more durable than wound balls, but many solid constructions lack the “feel” provided by the wound construction.

More recently, by altering ball construction and composition, manufacturers have been able to vary a wide range of playing characteristics, such as compression, velocity, “feel,” and spin, optimizing each or all for various playing abilities. In particular, a variety of core and cover layer(s) constructions, such as multi-layer balls having dual cover layers and/or dual core layers, have been investigated and now allow many non-wound balls to exhibit characteristics previously maintainable in a solid-construction golf ball. These golf ball layers are typically constructed with a number of polymeric compositions and blends, including polybutadiene rubber, polyurethanes, polyamides, and ethylene-based ionomers.

Ionomers, and in particular ethylene α,β-ethylenically unsaturated carboxylic acid copolymers or a melt processible ionomer thereof, are a preferred polymer for many golf ball layers. One problem encountered with the use of ionomers as stiff layers, however, is the unprocessability of the material as the percent of neutralization of the acid group increases. Ionomers are stiffened by increasing the amount of neutralization by a metal cation or a salt thereof. Once the percent of neutralization is greater than about 60% (depending on metal cation selected), the melt flow of the ionomer becomes too low and the ease of processablilty decreases or disappears altogether.

There is a need, therefore, for ionomer compositions that are neutralized at high percentages, but in a manner that still allows resultant polymer compositions to be processible. The present invention describes such compositions and there use in a variety of golf ball core and cover layers.

SUMMARY

The present invention is directed to a golf ball comprising a center comprising a highly-neutralized thermoplastic copolymer of ethylene and an α,β-unsaturated carboxylic acid, the acid being 100% neutralized by a salt of an organic acid, a cation source, or a suitable base of the organic acid; a cover; and an intermediate layer disposed between the center and the cover; wherein the golf ball has a first coefficient of restitution of 0.81 or greater when measured at an incoming velocity of 125 ft/s; and a sphere resulting from a combination of the center and the intermediate layer has a compression of 60 or greater.

The cation source is typically a metal cation of lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, and aluminum. Ideally, the salt of an organic acid includes an organic acid, such as aliphatic organic acids, aromatic organic acids, saturated mono- or multi-functional organic acids, unsaturated mono- or multi-functional organic acids, and multi-unsaturated mono- or multi-functional organic acids. The salt of an organic acid may include stearic acid, behenic acid, erucic acid, oleic acid, linoelic acid or dimerized derivatives thereof. The salt of an organic acid includes a cation, such as barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, and calcium.

The thermoplastic polymer comprises ionomeric copolymers and terpolymers, ionomer precursors, grafted metallocene-catalyzed polymers, high-crystalline acid polymers and their ionomers, or cationic ionomers. Preferably, the cover is injection molded, cast, reaction injection molded, or compression molded over the core. In one embodiment, the cover comprises an inner cover layer and an outer cover layer, at least one which comprises a polyurethane material, a polyurea material, a polyurethane-urea hybrid material, or a polyurea-urethane hybrid material.

The center typically has a diameter of 1.50 inches or less and the the intermediate layer has a thickness of 0.090 inches or greater, preferably between 0.090 inches and 0.180 inches. The compression can be 80 or greater. Additionally, the golf ball should concurrently have a second coefficient of restitution of 0.76 or greater when measured at an incoming velocity of 160 ft/s.

The present invention is also directed to a golf ball comprising an innermost core, a cover, and an intermediate layer disposed between the innermost core and the cover, wherein the intermediate layer comprises a highly-neutralized thermoplastic copolymer of ethylene and an α,β-unsaturated carboxylic acid, the acid being 100% neutralized by a salt of an organic acid, a cation source, or a suitable base of the organic acid, and wherein a sphere resulting from a combination of the center and the intermediate layer has a compression of 60 or greater.

The intermediate layer should have a flexural modulus of 50,000 psi or greater, preferably from 60,000 psi to 150,000 psi. In one embodiment, the center has a diameter of from 0.80 inches to 1.40 inches and a compression of 30 or less, and the intermediate layer has flexural modulus of 50,000 psi to 70,000 psi and a thickness of 0.110 inches or greater, and the cover comprises thermoset polymer having a hardness of from 45 Shore D to 60 Shore D and a thickness from 0.020 inches to 0.040 inches. Additionally, the golf ball should concurrently have a coefficient of restitution of 0.76 or greater when measured at an incoming velocity of 160 ft/s.

Additionally, the present invention is also directed to a golf ball comprising an innermost core, a cover, and an intermediate layer disposed between the innermost core and the cover, wherein the core comprises a highly-neutralized thermoplastic copolymer of ethylene and an α,β-unsaturated carboxylic acid, the acid being 100% neutralized by a salt of an organic acid, a cation source, or a suitable base of the organic acid, and wherein a sphere resulting from a combination of the center and the intermediate layer has a compression of 60 or greater.

Preferably, the compression is 80 or greater. In one embodiment, the golf ball has a coefficient of restitution of 0.80 or greater when measured at an incoming velocity of 125 ft/s. The core should have a diameter of 1.500 inches or less and/or an intermediate layer having a thickness of 0.090 inches or greater. Preferably, the intermediate layer thickness is between 0.090 inches and 0.180 inches. In an alternative embodiment, the core has a compression of 60 or less. The intermediate layer should have a flexural modulus of 50,000 psi or greater. Also, the cover can be injection molded, cast, reaction injection molded, or compression molded over the core.

DETAILED DESCRIPTION

The present invention is directed to highly-neutralized polymers and blends thereof (“HNP”) for the use in golf equipment, preferably in ball cores, intermediate layers, and/or covers. The acid moieties of the HNP\'s, typically ethylene-based ionomers, are preferably neutralized greater than about 70%, more preferably greater than about 90%, and most preferably at least about 100%. The HNP\'s can be also be blended with a second polymer component, which, if containing an acid group, may be neutralized in a conventional manner, by the organic fatty acids of the present invention, or both. The second polymer component, which may be partially or fully neutralized, preferably comprises ionomeric copolymers and terpolymers, ionomer precursors, thermoplastics, polyamides, polycarbonates, polyesters, polyurethanes, polyureas, thermoplastic elastomers, polybutadiene rubber, balata, metallocene-catalyzed polymers (grafted and non-grafted), single-site polymers, high-crystalline acid polymers, cationic ionomers, and the like. HNP polymers typically have a material hardness of between about 20 and about 80 Shore D, and a flexural modulus of between about 3,000 psi and about 200,000 psi.

In one embodiment of the present invention the HNP\'s are ionomers and/or their acid precursors that are preferably neutralized, either filly or partially, with organic acid copolymers or the salts thereof. The acid copolymers are preferably α-olefin, such as ethylene, C3-8 α,β-ethylenically unsaturated carboxylic acid, such as acrylic and methacrylic acid, copolymers. They may optionally contain a softening monomer, such as alkyl acrylate and alkyl methacrylate, wherein the alkyl groups have from 1 to 8 carbon atoms.

The acid copolymers can be described as E/X/Y copolymers where E is ethylene, X is an α,β-ethylenically unsaturated carboxylic acid, and Y is a softening comonomer. In a preferred embodiment, X is acrylic or methacrylic acid and Y is a C1-8 alkyl acrylate or methacrylate ester. X is preferably present in an amount from about 1 to about 35 weight percent of the polymer, more preferably from about 5 to about 30 weight percent of the polymer, and most preferably from about 10 to about 20 weight percent of the polymer. Y is preferably present in an amount from about 0 to about 50 weight percent of the polymer, more preferably from about 5 to about 25 weight percent of the polymer, and most preferably from about 10 to about 20 weight percent of the polymer.

Specific acid-containing ethylene copolymers include, but are not limited to, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylic acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl methacrylate. Preferred acid-containing ethylene copolymers include, ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate, ethylene/acrylic acid/ethyl acrylate, ethylene/methacrylic acid/ethyl acrylate, and ethylene/acrylic acid/methyl acrylate copolymers. The most preferred acid-containing ethylene copolymers are, ethylene/(meth) acrylic acid/n-butyl, acrylate, ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth) acrylic acid/methyl acrylate copolymers.

Ionomers are typically neutralized with a metal cation, such as Li, Na, Mg, or Zn. It has been found that by adding sufficient organic acid or salt of organic acid, along with a suitable base, to the acid copolymer or ionomer, the ionomer can be neutralized without losing processability to a level much greater than for a metal cation alone. Preferably, the acid moieties are neutralized greater than about 80%, preferably from 90-100%, most preferably 100% without losing processability. This accomplished by melt-blending an ethylene α,β-ethylenically unsaturated carboxylic acid copolymer, for example, with an organic acid or a salt of organic acid, and adding a sufficient amount of a cation source to increase the level of neutralization of all the acid moieties (including those in the acid copolymer and in the organic acid) to greater than 90%, (preferably greater than 100%).

The organic acids of the present invention are aliphatic, mono- or multi-functional (saturated, unsaturated, or multi-unsaturated) organic acids. Salts of these organic acids may also be employed. 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, bebenic, erucic, oleic, linoelic or dimerized derivatives thereof. It is preferred that the organic acids and salts of the present invention 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 ionomers of the invention may also be partially neutralized with metal cations. The acid moiety in the acid copolymer is neutralized about 1 to about 100%, preferably at least about 40 to about 100%, and more preferably at least about 90 to about 100%, to form an ionomer by a cation such as lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, or a mixture thereof.

The acid copolymers of the present invention are prepared from ‘direct’ acid copolymers, copolymers polymerized by adding all monomers simultaneously, or by grafting of at least one acid-containing monomer onto an existing polymer. Other suitable highly-neutralized acid polymer compositions are disclosed in U.S. Patent Publication Nos. 2003/0114565 and 2005/0267240, and in U.S. patent application Ser. No. 11/270,066, which are incorporated herein, in their entirety, by reference.

Thermoplastic polymer components, such as copolyetheresters, copolyesteresters, copolyetheramides, elastomeric polyolefins, styrene diene block copolymers and their hydrogenated derivatives, copolyesteramides, thermoplastic polyurethanes, such as copolyetherurethanes, copolyesterurethanes, copolyureaurethanes, epoxy-based polyurethanes, polycaprolactone-based polyurethanes, polyureas, and polycarbonate-based polyurethanes fillers, and other ingredients, if included, can be blended in either before, during, or after the acid moieties are neutralized, thermoplastic polyurethanes.

The copolyetheresters are comprised of a multiplicity of recurring long chain units and short chain units joined head-to-tail through ester linkages, the long chain units being represented by the formula:

and the short chain units being represented by the formula:

where G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly (alkylene oxide) glycol having a molecular weight of about 400-8000 and a carbon to oxygen ratio of about 2.0-4.3; R is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250; provided said short chain ester units amount to about 15-95 percent by weight of said copolyetherester. The preferred copolyetherester polymers are those where the polyether segment is obtained by polymerization of tetrahydrofuran and the polyester segment is obtained by polymerization of tetramethylene glycol and phthalic acid. For purposes of the invention, the molar ether:ester ratio can vary from 90:10 to 10:80; preferably 80:20 to 60:40; and the Shore D hardness is less than 70; preferably less than about 40.

The copolyetheramides are comprised of a linear and regular chain of rigid polyamide segments and flexible polyether segments, as represented by the general formula:

wherein PA is a linear saturated aliphatic polyamide sequence formed from a lactam or amino acid having a hydrocarbon chain containing 4 to 14 carbon atoms or from an aliphatic C6-C8 diamine, in the presence of a chain-limiting aliphatic carboxylic diacid having 4-20 carbon atoms; said polyamide having an average molecular weight between 300 and 15,000; and PB is a polyoxyalkylene sequence formed from linear or branched aliphatic polyoxyalkylene glycols, mixtures thereof or copolyethers derived therefrom, said polyoxyalkylene glycols having a molecular weight of less than or equal to 6000; and n indicates a sufficient number of repeating units so that said polyetheramide copolymer has an intrinsic viscosity of from about 0.6 to about 2.05. The preparation of these polyetheramides comprises the step of reacting a dicarboxylic polyamide, the COOH groups of which are located at the chain ends, with a polyoxyalkylene glycol hydroxylated at the chain ends, in the presence of a catalyst such as a tetra-alkyl ortho titanate having the general formula Ti(OR)x wherein R is a linear branched aliphatic hydrocarbon radical having 1 to 24 carbon atoms. Again, the more polyether units incorporated into the copolyetheramide, the softer the polymer. The ether:amide ratios are as described above for the ether:ester ratios, as is the Shore D hardness.

The elastomeric polyolefins are polymers composed of ethylene and higher primary olefins such as propylene, hexene, octene, and optionally 1,4-hexadiene and or ethylidene norbornene or norbomadiene. The elastomeric polyolefins can be optionally functionalized with maleic anhydride, epoxy, hydroxy, amine, carboxylic acid, sulfonic acid, or thiol groups.

Thermoplastic polyurethanes are linear or slightly chain branched polymers consisting of hard blocks and soft elastomeric blocks. They are produced by reacting soft hydroxy terminated elastomeric polyethers or polyesters with diisocyanates, such as methylene diisocyanate (“MDI”), p-phenylene diisocyanate (“PPDI”), or toluene diisocyanate (“TDI”). These polymers can be chain extended with glycols, secondary diamines, diacids, or amino alcohols. The reaction products of the isocyanates and the alcohols are called urethanes and these blocks are relatively hard and high melting. These hard high melting blocks are responsible for the thermoplastic nature of the polyurethanes.

Block styrene diene copolymers and their hydrogenated derivatives are composed of polystyrene units and polydiene units. They may also be functionalized with moieties such as OH, NH2, epoxy, COOH, and anhydride groups. The polydiene units are derived from polybutadiene, polyisoprene units or copolymers of these two. In the case of the copolymer it is possible to hydrogenate the polyolefin to give a saturated rubbery backbone segments. These materials are usually referred to as SBS, SIS, or SEBS thermoplastic elastomers and they can also be functionalized with maleic anhydride.

Grafted metallocene-catalyzed polymers are also useful for blending with the HNP\'s of the present invention. The grafted metallocene-catalyzed polymers, while conventionally neutralized with metal cations, may also be neutralized, either partially for fully, with organic acids or salts thereof and an appropriate base. Grafted metallocene-catalyzed polymers useful, such as those disclosed in U.S. Pat. Nos. 5,703,166; 5,824,746; 5,981,658; and 6,025,442, which are incorporated herein by reference, in the golf balls of the invention are available in experimental quantities from DuPont under the tradenames SURLYN® NMO 525D, SURLYN® NMO 524D, and SURLYN® NMO 499D, all formerly known as the FUSABOND® family of polymers, or may be obtained by subjecting a non-grafted metallocene-catalyzed polymer to a post-polymerization reaction to provide a grafted metallocene-catalyzed polymer with the desired pendant group or groups. Examples of metallocene-catalyzed polymers to which functional groups may be grafted for use in the invention include, but are not limited to, homopolymers of ethylene and copolymers of ethylene and a second olefin, preferably, propylene, butene, pentene, hexene, heptene, octene, and norbornene. Generally, the invention includes golf balls having at least one layer comprising at least one grafted metallocene-catalyzed polymer or polymer blend, where the grafted metallocene-catalyzed polymer is produced by grafting a functional group onto a metallocene-catalyzed polymer having the formula:

wherein R1 is hydrogen, branched or straight chain alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl, carbocyclic, or aromatic; R2 is hydrogen, lower alkyl including C1-C5; carbocyclic, or aromatic; R3 is hydrogen, lower alkyl including C1-C5, carbocyclic, or aromatic; R4 is selected from the group consisting of H, CnH2n+1, where n=1 to 18, and phenyl, in which from 0 to 5 H within R4 can be replaced by substituents COOH, SO3H, NH2, F, Cl, Br, I, OH, SH, silicone, lower alkyl esters and lower alkyl ethers, with the proviso that R3 and R4 can be combined to form a bicyclic ring; R5 is hydrogen, lower alkyl including C1-C5, carbocyclic, or aromatic; R6 is hydrogen, lower alkyl including C1-C5, carbocyclic, or aromatic; and wherein x, y and z are the relative percentages of each co-monomer. X can range from about 1 to 99 percent or more preferably from about 10 to about 70 percent and most preferred, from about 10 to 50 percent. Y can be from 99 to 1 percent, preferably, from 90 to30 percent, or most preferably, 90 to 50 percent. Z can range from about 0 to about 49 percent. One of ordinary skill in the art would understand that if an acid moiety is present as a ligand in the above polymer that it may be neutralized up to 100% with an organic fatty acid as described above.

Metallocene-catalyzed copolymers or terpolymers can be random or block and may be isotactic, syndiotactic, or atactic. The pendant groups creating the isotactic, syndiotactic, or atactic polymers are chosen to determine the interactions between the different polymer chains making up the resin to control the final properties of the resins used in golf ball covers, centers, or intermediate layers. As will be clear to those skilled in the art, grafted metallocene-catalyzed polymers useful in the invention that are formed from metallocene-catalyzed random or block copolymers or terpolymers will also be random or block copolymers or terpolymers, and will have the same tacticity of the metallocene-catalyzed polymer backbone.

As used herein, the term “phrase branched or straight chain alkyl” means any substituted or unsubstituted acyclic carbon-containing compounds. Examples of alkyl groups include lower alkyl, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or t-butyl; upper alkyl, for example, octyl, nonyl, decyl, and the like; and lower alkylene, for example, ethylene, propylene, butylene, pentene, hexene, octene, norbornene, nonene, decene, and the like.

In addition, such alkyl groups may also contain various substituents in which one or more hydrogen atoms has been replaced by a functional group. Functional groups include, but are not limited to hydroxyl, amino, carboxyl, sulfonic amide, ester, ether, phosphates, thiol, nitro, silane and halogen (fluorine, chlorine, bromine and iodine), to mention but a few.

As used herein, the term “substituted and unsubstituted carbocyclic” means cyclic carbon-containing compounds, including, but not limited to cyclopentyl, cyclohexyl, cycloheptyl, and the like. Such cyclic groups may also contain various substituents in which one or more hydrogen atoms has been replaced by a functional group. Such functional groups include those described above, and lower alkyl groups having from 1-28 carbon atoms. The cyclic groups of the invention may further comprise a heteroatom.

As mentioned above, R1 and R2 can also represent any combination of alkyl, carbocyclic or aryl groups, for example, 1-cyclohexylpropyl, benzyl cyclohexylmethyl, 2-cyclohexylpropyl, 2,2-methylcyclohexylpropyl, 2,2-methylphenylpropyl, and 2,2-methylphenylbutyl.

Non-grafted metallocene-catalyzed polymers useful in the present invention are commercially available under the trade name AFFINITY® polyolefin plastomers and ENGAGE® polyolefin elastomers commercially available from Dow Chemical Company and DuPont-Dow. Other commercially available metallocene-catalyzed polymers can be used, such as EXACT®, commercially available from Exxon and INSIGHT®, commercially available from Dow. The EXACT® and INSIGHT® line of polymers also have novel Theological behavior in addition to their other properties as a result of using a metallocene catalyst technology. Metallocene-catalyzed polymers are also readily available from Sentinel Products Corporation of Hyannis, Mass., as foamed sheets for compression molding.

Monomers useful in the present invention include, but are not limited to, olefinic monomers having, as a functional group, sulfonic acid, sulfonic acid derivatives, such as chlorosulfonic acid, vinyl ethers, vinyl esters, primary, secondary, and tertiary amines, mono-carboxylic acids, dicarboxylic acids, partially or fully ester-derivatized mono-carboxylic and dicarboxylic acids, anhydrides of dicarboxylic acids, and cyclic imides of dicarboxylic acids.

In addition, metallocene-catalyzed polymers may also be functionalized by sulfonation, carboxylation, or the addition of an amine or hydroxy group. Metallocene-catalyzed polymers functionalized by sulfonation, carboxylation, or the addition of a hydroxy group may be converted to anionic ionomers by treatment with a base. Similarly, metallocene-catalyzed polymers functionalized by the addition of an amine may be converted to cationic ionomers by treatment with an alkyl halide, acid, or acid derivative.

The most preferred monomer is maleic anhydride, which, once attached to the metallocene-catalyzed polymer by the post-polymerization reaction, may be further subjected to a reaction to form a grafted metallocene-catalyzed polymer containing other pendant or functional groups. For example, reaction with water will convert the anhydride to a dicarboxylic acid; reaction with ammonia, alkyl, or aromatic amine forms an amide; reaction with an alcohol results in the formation of an ester; and reaction with base results in the formation of an anionic ionomer.

The HNP\'s of the present invention may also be blended with single-site and metallocene catalysts and polymers formed therefrom. As used herein, the term “single-site catalyst,” such as those disclosed in U.S. Pat. No. 6,150,462 which is incorporated herein by reference, refers to a catalyst that contains an ancillary ligand that influences the stearic and electronic characteristics of the polymerizing site in a manner that prevents formation of secondary polymerizing species. The term “metallocene catalyst” refers to a single-site catalyst wherein the ancillary ligands are comprising substituted or unsubstituted cyclopentadienyl groups, and the term “non-metallocene catalyst” refers to a single-site catalyst other than a metallocene catalyst.

Non-metallocene single-site catalysts include, but are not limited to, the Brookhart catalyst, which has the following structure:

wherein M is nickel or palladium; R and R′ are independently hydrogen, hydrocarbyl, or substituted hydrocarbyl; Ar is (CF3)2C6H3, and X is alkyl, methyl, hydride, or halide; the McConville catalyst, which has the structure:

wherein M is titanium or zirconium. Iron (II) and cobalt (II) complexes with 2,6-bis(imino) pyridyl ligands, which have the structure:

where M is the metal, and R is hydrogen, alkyl, or hydrocarbyl. Titanium or zirconium complexes with pyrroles as ligands also serve as single-site catalysts. These complexes have the structure:

where M is the metal atom; m and n are independently 1 to 4, and indicate the number of substituent groups attached to the aromatic rings; Rm and Rn are independently hydrogen or alkyl; and X is halide or alkyl. Other examples include diimide complexes of nickel and palladium, which have the structure:

where Ar is aromatic, M is the metal, and X is halide or alkyl. Boratabenzene complexes of the Group IV or V metals also function as single-site catalysts. These complexes have the structure:

where B is boron and M is the metal atom.

As used herein, the term “single-site catalyzed polymer” refers to any polymer, copolymer, or terpolymer, and, in particular, any polyolefin polymerized using a single-site catalyst. The term “non-metallocene single-site catalyzed polymer” refers to any polymer, copolymer, or terpolymer, and, in particular, any polyolefin polymerized using a single-site catalyst other than a metallocene-catalyst. The catalysts discussed above are examples of non-metallocene single-site catalysts. The term “metallocene catalyzed polymer” refers to any polymer, copolymer, or terpolymer, and, in particular, any polyolefin, polymerized using a metallocene catalyst.

As used herein, the term “single-site catalyzed polymer blend” refers to any blend of a single-site catalyzed polymer and any other type of polymer, preferably an ionomer, as well as any blend of a single-site catalyzed polymer with another single-site catalyzed polymer, including, but not limited to, a metallocene-catalyzed polymer.

The terms “grafted single-site catalyzed polymer” and “grafted single-site catalyzed polymer blend” refer to any single-site catalyzed polymer or single-site catalyzed polymer blend in which the single-site catalyzed polymer has been subjected to a post-polymerization reaction to graft at least one functional group onto the single-site catalyzed polymer. A “post-polymerization reaction” is any reaction that occurs after the formation of the polymer by a polymerization reaction.

The single-site catalyzed polymer, which may be grafted, may also be blended with polymers, such as non-grafted single-site catalyzed polymers, grafted single-site catalyzed polymers, ionomers, and thermoplastic elastomers. Preferably, the single-site catalyzed polymer is blended with at least one ionomer of the preset invention.

Grafted single-site catalyzed polymers useful in the golf balls of the invention may be obtained by subjecting a non-grafted single-site catalyzed polymer to a post-polymerization reaction to provide a grafted single-site catalyzed polymer with the desired pendant group or groups. Examples of single-site catalyzed polymers to which functional groups may be grafted for use in the invention include, but are not limited to, homopolymers of ethylene and propylene and copolymers of ethylene and a second olefin, preferably, propylene, butene, pentene, hexene, heptene, octene, and norbornene. Monomers useful in the present invention include, but are not limited to olefinic monomers having as a functional group sulfonic acid, sulfonic acid derivatives, such as chlorosulfonic acid, vinyl ethers, vinyl esters, primary, secondary, and tertiary amines, epoxies, isocyanates, mono-carboxylic acids, dicarboxylic acids, partially or fully ester derivatized mono-carboxylic and dicarboxylic acids, anhydrides of dicarboxylic acids, and cyclic imides of dicarboxylic acids. Generally, this embodiment of the invention includes golf balls having at least one layer comprising at least one grafted single-site catalyzed polymer or polymer blend, where the grafted single-site catalyzed polymer is produced by grafting a functional group onto a single-site catalyzed polymer having the formula:

where R1 is hydrogen, branched or straight chain alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl, carbocyclic, aromatic or heterocyclic; R2, R3, R5, and R6 are hydrogen, lower alkyl including C1-C5, carbocyclic, aromatic or heterocyclic; R4 is H, CnH2n+1, where n=1 to 18, and phenyl, in which from 0 to 5 H within R4 can be replaced by substituents such as COOH, SO3H, NH2, F, Cl, Br, I, OH, SH, epoxy, isocyanate, silicone, lower alkyl esters and lower alkyl ethers; also, R3 and R4 can be combined to form a bicyclic ring; and x, y and z are the relative percentages of each co-monomer. X can range from about 1 to about 100 percent or more preferably from 1 to 70 percent and most preferred, from about 1 to about 50 percent. Y can be from about 99 to about 0 percent, preferably, from about 9 to about 30 percent, or most preferably, about 9 to about 50 percent. Z can range from about 0 to about 50 percent. One of ordinary skill in the art would also understand that if an acid group is selected as a ligand in the above structure that it too could be neutralized with the organic fatty acids described above.

The HNP\'s of the present invention may also be blended with high crystalline acid copolymers and their ionomer derivatives (which may be neutralized with conventional metal cations or the organic fatty acids and salts thereof) or a blend of a high crystalline acid copolymer and its ionomer derivatives and at least one additional material, preferably an acid copolymer and its ionomer derivatives. As used herein, the term “high crystalline acid copolymer” is defined as a “product-by-process” in which an acid copolymer or its ionomer derivatives formed from a ethylene/carboxylic acid copolymer comprising about 5 to about 35 percent by weight acrylic or methacrylic acid, wherein the copolymer is polymerized at a temperature of about 130° C. to 200° C., at pressures greater than about 20,000 psi preferably greater than about 25,000 psi, more pref. from about 25,000 psi to about 50,000 psi, wherein up to about 70 percent, preferably 100 percent, of the acid groups are neutralized with a metal ion, organic fatty acids and salts thereof, or a mixture thereof. The copolymer can have a melt index (“MI”) of from about 20 to about 300 g/10 min, preferably about 20 to about 200 g/10 min, and upon neutralization of the copolymer, the resulting acid copolymer and its ionomer derivatives should have an MI of from about 0.1 to about 30.0 g/10 min.

Suitable high crystalline acid copolymer and its ionomer derivatives compositions and methods for making them are disclosed in U.S. Pat. No. 5,580,927, the disclosure of which is hereby incorporated by reference in its entirety.

The high crystalline acid copolymer or its ionomer derivatives employed in the present invention are preferably formed from a copolymer containing about 5 to about 35 percent, more preferably from about 9 to about 18, most preferably about 10 to about 13 percent, by weight of acrylic acid, wherein up to about 75 percent, most preferably about 60 percent, of the acid groups are neutralized with an organic fatty acid, salt thereof, or a metal ion, such as sodium, lithium, magnesium, or zinc ion.

Generally speaking, high crystalline acid copolymer and its ionomer derivatives are formed by polymerization of their base copolymers at lower temperatures, but at equivalent pressures to those used for forming a conventional acid copolymer and its ionomer derivatives. Conventional acid copolymers are typically polymerized at a polymerization temperature of from at least about 200° C. to about 270° C., preferably about 220° C., and at pressures of from about 23,000 to about 30,000 psi. In comparison, the high crystalline acid copolymer and its ionomer derivatives employed in the present invention are produced from acid copolymers that are polymerized at a polymerization temperature of less than 200° C., and preferably from about 130° C. to about 200° C., and at pressures from about 20,000 to about 50,000 psi.

The HNP\'s of the present invention may also be blended with cationic ionomers, such as those disclosed in U.S. Pat. No. 6,193,619 which is incorporated herein by reference. In particular, cationic ionomers have a structure according to the formula:

or the formula:

wherein R1-R9 are organic moieties of linear or branched chain alkyl, carbocyclic, or aryl; and Z is the negatively charged conjugate ion produced following alkylation and/or quaternization. The cationic polymers may also be quarternized up to 100% by the organic fatty acids described above.

In addition, such alkyl group may also contain various substituents in which one or more hydrogen atoms has been replaced by a functional group. Functional groups include but are not limited to hydroxyl, amino, carboxyl, amide, ester, ether, sulfonic, siloxane, siloxyl, silanes, sulfonyl, and halogen.

As used herein, substituted and unsubstituted carbocyclic groups of up to about 20 carbon atoms means cyclic carbon-containing compounds, including but not limited to cyclopentyl, cyclohexyl, cycloheptyl, and the like. Such cyclic groups may also contain various substituents in which one or more hydrogen atoms has been replaced by a functional group. Such functional groups include those described above, and lower alkyl groups as described above. The cyclic groups of the invention may further comprise a heteroatom.

The HNP\'s of the present invention may also be blended with polyurethane and polyurea ionomers which include anionic moieties or groups, such as those disclosed in U.S. Pat. No. 6,207,784 which is incorporated herein by reference. Typically, such groups are incorporated onto the diisocyanate or diisocyanate component of the polyurethane or polyurea ionomers. The anionic group can also be attached to the polyol or amine component of the polyurethane or polyurea, respectively. Preferably, the anionic group is based on a sulfonic, carboxylic or phosphoric acid group. Also, more than one type of anionic group can be incorporated into the polyurethane or polyurea. Examples of anionic polyurethane ionomers with anionic groups attached to the diisocyanate moiety can have a chemical structure according to the following formula:

where A=R-Z−M+x; R is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; Z=SO3−, CO2− or HPO3−; M is a group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIB metal; x=1 to 5; B is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; and n=1 to 100. Preferably, M+x is one of the following: Li+, Na+, K+, Mg+2, Zn+2, Ca+2, Mn+2, Al+3, Ti+x, Zr+x, W+x or Hf+x.

Exemplary anionic polyurethane ionomers with anionic groups attached to the polyol component of the polyurethane are characterized by the above chemical structure where A is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; B=R-Z−M+x; R is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; Z=SO3−, CO2− or HPO3−; M is a group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIB metal; x=1 to 5; and n=1 to 100. Preferably, M+x is one of the following: Li+, Na+, K+, Mg+2, Zn+2, Ca+2, Mn+2, Al+3, Ti+x, Zr+x, W+x or Hf+x.

Examples of suitable anionic polyurea ionomers with anionic groups attached to the diisocyanate component have a chemical structure according to the following chemical structure:

where A=R-Z−M+x; R is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; Z=SO3−, CO2− or HPO3−; M is a group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIB metal; x=1 to 5; and B is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group. Preferably, M+x is one of the following: Li+, Na+, K+, Mg+2, Zn+2, Ca+2, Mn+2, Al+3, Ti+x, Zr+x, W+x, or Hf30 x.

Suitable anionic polyurea ionomers with anionic groups attached to the amine component of the polyurea are characterized by the above chemical structure where A is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; B=R-Z-M+x; R is a straight chain or branched aliphatic group, a substituted straight chain or branched aliphatic group, or an aromatic or substituted aromatic group; Z=SO3−, CO2−, or HPO3−; M is a group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIB metal; and x=1 to 5. Preferably, M+x is one of the following: Li+, Na+, K+, Mg+2, Zn+2, Ca+2, Mn+2, Al+3, Ti+x, Zr+x, W+x, or Hf+x. The anionic polyurethane and polyurea ionomers may also be neutralized up to 100% by the organic fatty acids described above.

The anionic polymers useful in the present invention, such as those disclosed in U.S. Pat. No. 6,221,960 which is incorporated herein by reference, include any homopolymer, copolymer or terpolymer having neutralizable hydroxyl and/or dealkylable ether groups, and in which at least a portion of the neutralizable or dealkylable groups are neutralized or dealkylated with a metal ion.

As used herein “neutralizable” or “dealkylable” groups refer to a hydroxyl or ether group pendent from the polymer chain and capable of being neutralized or dealkylated by a metal ion, preferably a metal ion base. These neutralized polymers have improved properties critical to golf ball performance, such as resiliency, impact strength and toughness and abrasion resistance. Suitable metal bases are ionic compounds comprising a metal cation and a basic anion. Examples of such bases include hydroxides, carbonates, acetates, oxides, sulfides, and the like.

The particular base to be used depends upon the nature of the hydroxyl or ether compound to be neutralized or dealkylated, and is readily determined by one skilled in the art. Preferred anionic bases include hydroxides, carbonates, oxides and acetates.

The metal ion can be any metal ion which forms an ionic compound with the anionic base. The metal is not particularly limited, and includes alkali metals, preferably lithium, sodium or potassium; alkaline earth metals, preferably magnesium or calcium; transition metals, preferably titanium, zirconium, or zinc; and Group III and IV metals. The metal ion can have a +1 to +5 charge. Most preferably, the metal is lithium, sodium, potassium, zinc, magnesium, titanium, tungsten, or calcium, and the base is hydroxide, carbonate or acetate.

The anionic polymers useful in the present invention include those which contain neutralizable hydroxyl and/or dealkylable ether groups. Exemplary polymers include ethylene vinyl alcohol copolymers, polyvinyl alcohol, polyvinyl acetate, poly(p-hydroxymethylene styrene), and p-methoxy styrene, to name but a few. It will be apparent to one skilled in the art that many such polymers exist and thus can be used in the compositions of the invention. In general, the anionic polymer can be described by the chemical structure:

where R1 is OH, OC(O)Ra, O-M+V, (CH2)nRb, (CHRz)nRb, or aryl, wherein n is at least 1, Ra is a 1, Ra is a lower alkyl, M is a metal ion, V is an integer from 1 to 5, Rb is OH, OC(O)Ra, O-M+V, and Rz is a lower alkyl or aryl, and R2, R3 and R4 are each independently hydrogen, straight-chain or branched-chain lower alkyl. R2, R3 and R4 may also be similarly substituted. Preferably n is from 1 to 12, more preferably 1 to 4.

The term “substituted,” as used herein, means one or more hydrogen atoms has been replaced by a functional group. Functional groups include, but are not limited to, hydroxyl, amino, carboxyl, sulfonic, amide, ether, ether, phosphates, thiol, nitro, silane, and halogen, as well as many others which are quite familiar to those of ordinary skill in this art.

The terms “alkyl” or “lower alkyl,” as used herein, includes a group of from about 1 to 30 carbon atoms, preferably 1 to 10 carbon atoms.

In the anionic polymers useful in the present invention, at least a portion of the neutralizable or dealkylable groups of R1 are neutralized or dealkylated by an organic fatty acid, a salt thereof, a metal base, or a mixture thereof to form the corresponding anionic moiety. The portion of the neutralizable or dealkylable groups which are neutralized or dealkylated can be between about 1 to about 100 weight percent, preferably between about 50 to about 100 weight percent, more preferably before about 90 to about 100.

Neutralization or dealkylation may be performed by melting the polymer first, then adding a metal ion in an extruder. The degree of neutralization or dealkylation is controlled by varying the amount of metal ion added. Any method of neutralization or dealkylation available to those of ordinary skill in the art may also be suitably employed.

In one embodiment, the anionic polymer is repeating units any one of the three homopolymer units in the chemical structure above. In a preferred embodiment, R2, R3 and R4 are hydrogen, and R1 is hydroxyl, i.e., the anionic polymer is a polyvinyl alcohol homopolymer in which a portion of the hydroxyl groups have been neutralized with a metal base. In another preferred embodiment, R2, R3 and R4 are hydrogen, R1 is OC(O)Ra, and Ra is methyl, i.e., the anionic polymer is a polyvinyl acetate homopolymer in which a portion of the methyl ether groups have been dealkylated with a metal ion.

The anionic polymer can also be a copolymer of two different repeating units having different substituents, or a terpolymer of three different repeating units described in the above formula. In this embodiment, the polymer can be a random copolymer, an alternating copolymer, or a block copolymer, where the term “copolymer” includes terpolymers.

In another embodiment, the anionic polymer is a copolymer, wherein R5, R6, R7 and R8 are each independently selected from the group defined above for R2. The first unit of the copolymer can comprise from about 1 to 99 percent weight percent of the polymer, preferably from about 5 to 50 weight percent, and the second unit of the copolymer can comprise from about 99 to 1 weight percent, preferably from about 95 to 50 weight percent. In one preferred embodiment, the anionic polymer is a random, alternating or block copolymer of units (Ia) and (Ib) wherein R1 is hydroxyl, and each of the remaining R groups is hydrogen, i.e., the polymer is a copolymer of ethylene and vinyl alcohol. In another preferred embodiment, the anionic polymer is a random, alternating or block copolymer of units (Ia) and (Ib) wherein R1 is OC(O)R5, where R5 is methyl, and each of the remaining R groups is hydrogen, i.e., the polymer is a copolymer of ethylene and vinyl acetate.

In another embodiment, the anionic polymer is an anionic polymer having neutralizable hydroxyl and/or dealkylable ether groups of as in the above chemical structure wherein R1-9 and Rb and Rz are as defined above; R10-11 are each independently selected from the group as defined above for R2; and R12 is OH or OC(O)R13, where R13 is a lower alkyl; wherein x, y and z indicate relative weight percent of the different units. X can be from about 99 to about 50 weight percent of the polymer, y can be from about 1 to about 50 weight percent of the polymer, and z ranges from about 0 to about 50 weight percent of the polymer. At least a portion of the neutralizable groups R1 are neutralized. When the amount of z is greater than zero, a portion of the groups R10 can also be fully or partially neutralized, as desired.

In particular, the anionic polymers and blends thereof can comprise compatible blends of anionic polymers and ionomers, such as the ionomers described above, and ethylene acrylic methacrylic acid ionomers, and their terpolymers, sold commercially under the trade names SURLYN® and IOTEK® by DuPont and Exxon respectively. The anionic polymer blends useful in the golf balls of the invention can also include other polymers, such as polyvinylalcohol, copolymers of ethylene and vinyl alcohol, poly(ethylethylene), poly(heptylethylene), poly(hexyldecylethylene), poly(isopentylethylene), poly(butyl acrylate), acrylate), poly(2-ethylbutyl acrylate), poly(heptyl acrylate), poly(2-methylbutyl acrylate), poly(3-methylbutyl acrylate), poly(N-octadecylacrylamide), poly(octadecyl methacrylate), poly(butoxyethylene), poly(methoxyethylene), poly(pentyloxyethylene), poly(1,1-dichloroethylene), poly(4-[(2-butoxyethoxy)methyl]styrene), poly[oxy(ethoxymethyl)ethylene], poly(oxyethylethylene), poly(oxytetramethylene), poly(oxytrimethylene), poly(silanes) and poly(silazanes), polyamides, polycarbonates, polyesters, styrene block copolymers, polyetheramides, polyurethanes, main-chain heterocyclic polymers and poly(furan tetracarboxylic acid diimides), as well as the classes of polymers to which they belong.

The anionic polymer compositions of the present invention typically have a flexural modulus of from about 500 psi to about 300,000 psi, preferably from about 2000 to about 200,000 psi. The anionic polymer compositions typically have a material hardness of at least about 15 Shore A, preferably between about 30 Shore A and 80 Shore D, more preferably between about 50 Shore A and 60 Shore D. The loss tangent, or dissipation factor, is a ratio of the loss modulus over the dynamic shear storage modulus, and is typically less than about 1, preferably less than about 0.01, and more preferably less than about 0.001 for the anionic polymer compositions measured at about 23° C. The specific gravity is typically greater than about 0.7, preferably greater than about 1, for the anionic polymer compositions. The dynamic shear storage modulus, or storage modulus, of the anionic polymer compositions at about 23° C. is typically at least about 10,000 dyn/cm2.

The golf balls of the present invention may comprise a variety of constructions. In one embodiment of the present invention, golf ball includes a core, an inner cover layer surrounding the core, and an outer cover layer. Preferably, the core is solid. More preferably, the core is a solid, single-layer core. In a preferred embodiment, the solid core comprises the HNP\'s of the present invention. In an alternative embodiment, the solid core may include compositions having a base rubber, a crosslinking agent, a filler, and a co-crosslinking or initiator agent, and the inner cover layer comprises the HNP\'s of the present invention.

The base rubber typically includes natural or synthetic rubbers. A preferred base rubber is 1,4-polybutadiene having a cis-structure of at least 40%. More preferably, the base rubber comprises high-Mooney-viscosity rubber. If desired, the polybutadiene can also be mixed with other elastomers known in the art such as natural rubber, polyisoprene rubber and/or styrene-butadiene rubber in order to modify the properties of the core.

The crosslinking agent includes a metal salt of an unsaturated fatty acid such as a zinc salt or a magnesium salt of an unsaturated fatty acid having 3 to 8 carbon atoms such as acrylic or methacrylic acid. Suitable cross linking agents include metal salt diacrylates, dimethacrylates and monomethacrylates wherein the metal is magnesium, calcium, zinc, aluminum, sodium, lithium or nickel. The crosslinking agent is present in an amount from about 15 to about 40 parts per hundred of the rubber, preferably in an amount from about 19 to about 25 parts per hundred of the rubber and most preferably having about 20 to 24 parts crosslinking agent per hundred of rubber. The core compositions of the present invention may also include at least one organic or inorganic cis-trans catalyst to convert a portion of the cis-isomer of polybutadiene to the trans-isomer, as desired.

The initiator agent can be any known polymerization initiator which decomposes during the cure cycle. Suitable initiators include peroxide compounds such as dicumyl peroxide, 1,1-di-(t-butylperoxy)3,3,5-trimethyl cyclohexane, a-a bis-(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5di-(t-butylperoxy)hexane or di-t-butyl peroxide and mixtures thereof.

Fillers, any compound or composition that can be used to vary the density and other properties of the core, typically include materials such as tungsten, zinc oxide, barium sulfate, silica, calcium carbonate, zinc carbonate, metals, metal oxides and salts, regrind (recycled core material typically ground to about 30 mesh particle), high-Mooney-viscosity rubber regrind, and the like.

The golf ball cores of the present invention may also comprise a variety of constructions. For example, the core may comprise a single layer or a plurality of layers. The core may also comprise a layer of tensioned elastomeric material. In another embodiment of the present invention, golf ball comprises a solid center surrounded by at least one additional solid outer core layer. The “dual” core is surrounded by a “double” cover comprising an inner cover layer and an outer cover layer.

Preferably, the solid center comprises the HNP\'s of the present invention. In another embodiment, the inner cover layer comprises the highly-neutralized acid copolymers of the present invention. In an alternative embodiment, the outer core layer comprises the highly-neutralized acid copolymers of the present invention.

At least one of the outer core layers is formed of a resilient rubber-based component comprising a high-Mooney-viscosity rubber, and a crosslinking agent present in an amount from about 20 to about 40 parts per hundred, from about 30 to about 38 parts per hundred, and most preferably about 37 parts per hundred. It should be understood that the term “parts per hundred” is with reference to the rubber by weight.

When the golf ball of the present invention includes an intermediate layer, such as an outer core layer or an inner cover layer, any or all of these layer(s) may comprise thermoplastic and thermosetting material, but preferably the intermediate layer(s), if present, comprise any suitable material, such as ionic copolymers of ethylene and an unsaturated monocarboxylic acid which are available under the trademark SURLYN® of E.I. DuPont de Nemours & Co., of Wilmington, Del., or IOTEK® or ESCOR® of Exxon. These are copolymers or terpolymers of ethylene and methacrylic acid or acrylic acid partially neutralized with salts of zinc, sodium, lithium, magnesium, potassium, calcium, manganese, nickel or the like, in which the salts are the reaction product of an olefin having from 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having 3 to 8 carbon atoms. The carboxylic acid groups of the copolymer may be totally or partially neutralized and might include methacrylic, crotonic, maleic, fumaric or itaconic acid.

This golf ball can likewise include one or more homopolymeric or copolymeric inner cover materials, such as: (1) Vinyl resins, such as those formed by the polymerization of vinyl chloride, or by the copolymerization of vinyl chloride with vinyl acetate, acrylic esters or vinylidene chloride; (2) Polyolefins, such as polyethylene, polypropylene, polybutylene and copolymers such as ethylene methylacrylate, ethylene ethylacrylate, ethylene vinyl acetate, ethylene methacrylic or ethylene acrylic acid or propylene acrylic acid and copolymers and homopolymers produced using a single-site catalyst or a metallocene catalyst; (3) Polyurethanes, such as those prepared from polyols and diisocyanates or polyisocyanates, in particular PPDI-based thermoplastic polyurethanes, and those disclosed in U.S. Pat. No. 5,334,673; (4) Polyureas, such as those disclosed in U.S. Pat. No. 5,484,870; (5) Polyamides, such as poly(hexamethylene adipamide) and others prepared from diamines and dibasic acids, as well as those from amino acids such as poly(caprolactam), and blends of polyamides with SURLYN®, polyethylene, ethylene copolymers, ethylene-propylene-non-conjugated diene terpolymer, and the like; (6) Acrylic resins and blends of these resins with poly vinyl chloride, elastomers, and the like; (7) Thermoplastics, such as urethane; olefinic thermoplastic rubbers, such as blends of polyolefins with ethylene-propylene-non-conjugated diene terpolymer; block copolymers of styrene and butadiene, isoprene or ethylene-butylene rubber; or copoly(ether-amide), such as PEBAX®, sold by ELF Atochem of Philadelphia, Pa.; (8) Polyphenylene oxide resins or blends of polyphenylene oxide with high impact polystyrene as sold under the trademark NORYL® by General Electric Company of Pittsfield, Mass.; (9) Thermoplastic polyesters, such as polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate/glycol modified, poly(trimethylene terepthalate), and elastomers sold under the trademarks HYTREL® by E.I. DuPont de Nemours & Co. of Wilmington, Del., and LOMOD® by General Electric Company of Pittsfield, Mass.; (10) Blends and alloys, including polycarbonate with acrylonitrile butadiene styrene, polybutylene terephthalate, polyethylene terephthalate, styrene maleic anhydride, polyethylene, elastomers, and the like, and polyvinyl chloride with acrylonitrile butadiene styrene or ethylene vinyl acetate or other elastomers; and ( 11) Blends of thermoplastic rubbers with polyethylene, propylene, polyacetal, nylon, polyesters, cellulose esters, and the like.

Preferably, the inner cover includes polymers, such as ethylene, propylene, butene-1 or hexane-1 based homopolymers or copolymers including functional monomers, such as acrylic and methacrylic acid and fully or partially neutralized ionomer resins and their blends, methyl acrylate, methyl methacrylate homopolymers and copolymers, imidized, amino group containing polymers, polycarbonate, reinforced polyamides, polyphenylene oxide, high impact polystyrene, polyether ketone, polysulfone, poly(phenylene sulfide), acrylonitrile-butadiene, acrylic-styrene-acrylonitrile, poly(ethylene terephthalate), poly(butylene terephthalate), poly(vinyl alcohol), poly(tetrafluoroethylene) and their copolymers including functional comonomers, and blends thereof. Suitable cover compositions also include a polyether or polyester thermoplastic urethane, a thermoset polyurethane, a low modulus ionomer, such as acid-containing ethylene copolymer ionomers, including E/X/Y terpolymers where E is ethylene, X is an acrylate or methacrylate-based softening comonomer present in about 0 to 50 weight percent and Y is acrylic or methacrylic acid present in about 5 to 35 weight percent. More preferably, in a low spin rate embodiment designed for maximum distance, the acrylic or methacrylic acid is present in about 16 to 35 weight percent, making the ionomer a high modulus ionomer. In a higher spin embodiment, the inner cover layer includes an ionomer where an acid is present in about 10 to 15 weight percent and includes a softening comonomer. Additionally, high-density polyethylene (“HDPE”), low-density polyethylene (“LDPE”), LLDPE, and homo- and co-polymers of polyolefin are suitable for a variety of golf ball layers.

In one embodiment, the outer cover preferably includes a polyurethane composition comprising the reaction product of at least one polyisocyanate, polyol, and at least one curing agent. Any polyisocyanate available to one of ordinary skill in the art is suitable for use according to the invention. Exemplary polyisocyanates include, but are not limited to, 4,4′-diphenylmethane diisocyanate (“MDI”); polymeric MDI; carbodiimide-modified liquid MDI; 4,4′-dicyclohexylmethane diisocyanate (“H12MD I”); p-phenylene diisocyanate (“PPDI”); m-phenylene diisocyanate (“MPDI”); toluene diisocyanate (“TDI”); 3,3′-dimethyl-4,4′-biphenylene diisocyanate (“TODI”); isophoronediisocyanate (“IPDI”); hexamethylene diisocyanate (“HDI”); naphthalene diisocyanate (“NDI”); xylene diisocyanate (“XDI”); p-tetramethylxylene diisocyanate (“p-TMXDI”); m-tetramethylxylene diisocyanate (“m-TMXDI”); ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”); dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of 2,4,4-trimethyl-1,6-hexane diisocyanate (“TMDI”); tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; isocyanurate of toluene diisocyanate; uretdione of hexamethylene diisocyanate; and mixtures thereof. Polyisocyanates are known to those of ordinary skill in the art as having more than one isocyanate group, e.g., di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably, the polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, and more preferably, the polyisocyanate includes MDI. It should be understood that, as used herein, the term “MDI” includes 4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified liquid MDI, and mixtures thereof and, additionally, that the diisocyanate employed may be “low free monomer,” understood by one of ordinary skill in the art to have lower levels of “free” monomer isocyanate groups, typically less than about 0.1% free monomer groups. Examples of “low free monomer” diisocyanates include, but are not limited to Low Free Monomer MDI, Low Free Monomer TDI, and Low Free Monomer PPDI.

The at least one polyisocyanate should have less than about 14% unreacted NCO groups. Preferably, the at least one polyisocyanate has no greater than about 7.5% NCO, and more preferably, less than about 7.0%.

Any polyol available to one of ordinary skill in the art is suitable for use according to the invention. Exemplary polyols include, but are not limited to, polyether polyols, hydroxy-terminated polybutadiene (including partially/fully hydrogenated derivatives), polyester polyols, polycaprolactone polyols, and polycarbonate polyols. In one preferred embodiment, the polyol includes polyether polyol. Examples include, but are not limited to, polytetramethylene ether glycol (“PTMEG”), polyethylene propylene glycol, polyoxypropylene glycol, and mixtures thereof. The hydrocarbon chain can have saturated or unsaturated bonds and substituted or unsubstituted aromatic and cyclic groups. Preferably, the polyol of the present invention includes PTMEG.

In another embodiment, polyester polyols are included in the polyurethane material of the invention. Suitable polyester polyols include, but are not limited to, polyethylene adipate glycol; polybutylene adipate glycol; polyethylene propylene adipate glycol; o-phthalate-1,6-hexanediol; poly(hexamethylene adipate)glycol; and mixtures thereof. The hydrocarbon chain can have saturated or unsaturated bonds, or substituted or unsubstituted aromatic and cyclic groups.

In another embodiment, polycaprolactone polyols are included in the materials of the invention. Suitable polycaprolactone polyols include, but are not limited to, 1,6-hexanediol-initiated polycaprolactone, diethylene glycol initiated polycaprolactone, trimethylol propane initiated polycaprolactone, neopentyl glycol initiated polycaprolactone, 1,4-butanediol-initiated polycaprolactone, and mixtures thereof. The hydrocarbon chain can have saturated or unsaturated bonds, or substituted or unsubstituted aromatic and cyclic groups.

In yet another embodiment, the polycarbonate polyols are included in the polyurethane material of the invention. Suitable polycarbonates include, but are not limited to, polyphthalate carbonate and poly(hexamethylene carbonate)glycol. The hydrocarbon chain can have saturated or unsaturated bonds, or substituted or unsubstituted aromatic and cyclic groups. In one embodiment, the molecular weight of the polyol is from about 200 to about 4000.

Polyamine curatives are also suitable for use in the polyurethane composition of the invention and have been found to improve cut, shear, and impact resistance of the resultant balls. Preferred polyamine curatives include, but are not limited to, 3,5-dimethylthio-2,4-toluenediamine and isomers thereof; 3,5-diethyltoluene-2,4-diamine and isomers thereof, such as 3,5-diethyltoluene-2,6-diamine; 4,4′-bis-(sec-butylamino)-diphenylmethane; 1,4-bis-(sec-butylamino)-benzene, 4,4′-methylene-bis-(2-chloroaniline); 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline) (“MCDEA”); polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenyl methane; p,p′-methylene dianiline (“MDA”); m-phenylenediamine (“MPDA”); 4,4′-methylene-bis-(2-chloroaniline) (“MOCA”); 4,4′-methylene-bis-(2,6-diethylaniline) (“MDEA”); 4,4′-methylene-bis-(2,3-dichloroaniline) (“MDCA”); 4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane; 2,2′,3,3′-tetrachloro diamino diphenylmethane; trimethylene glycol di-p-aminobenzoate; and mixtures thereof. Preferably, the curing agent of the present invention includes 3,5-dimethylthio-2,4-toluenediamine and isomers thereof, such as ETHACURE 300, commercially available from Albermarle Corporation of Baton Rouge, La. Suitable polyamine curatives, which include both primary and secondary amines, preferably have molecular weights ranging from about 64 to about 2000.

At least one of a diol, triol, tetraol, or hydroxy-terminated curatives may be added to the aforementioned polyurethane composition. Suitable diol, triol, and tetraol groups include ethylene glycol; diethylene glycol; polyethylene glycol; propylene glycol; polypropylene glycol; lower molecular weight polytetramethylene ether glycol; 1,3-bis(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; resorcinol-di-(β-hydroxyethyl)ether; hydroquinone-di-(β-hydroxyethyl)ether; and mixtures thereof. Preferred hydroxy-terminated curatives include 1,3-bis(2-hydroxyethoxy)benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene; 1,4-butanediol, and mixtures thereof. Preferably, the hydroxy-terminated curatives have molecular weights ranging from about 48 to 2000. It should be understood that molecular weight, as used herein, is the absolute weight average molecular weight and would be understood as such by one of ordinary skill in the art.

Both the hydroxy-terminated and amine curatives can include one or more saturated, unsaturated, aromatic, and cyclic groups. Additionally, the hydroxy-terminated and amine curatives can include one or more halogen groups. The polyurethane composition can be formed with a blend or mixture of curing agents. If desired, however, the polyurethane composition may be formed with a single curing agent.

In a preferred embodiment of the present invention, saturated polyurethanes used to form cover layers, preferably the outer cover layer, and may be selected from among both castable thermoset and thermoplastic polyurethanes.

In this embodiment, the saturated polyurethanes of the present invention are substantially free of aromatic groups or moieties. Saturated polyurethanes suitable for use in the invention are a product of a reaction between at least one polyurethane prepolymer and at least one saturated curing agent. The polyurethane prepolymer is a product formed by a reaction between at least one saturated polyol and at least one saturated diisocyanate. As is well known in the art, a catalyst may be employed to promote the reaction between the curing agent and the isocyanate and polyol.

Saturated diisocyanates which can be used include, without limitation, ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”); 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; dodecane-1,12-diisocyanate; dicyclohexylmethane diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; isophorone diisocyanate (“IPDI”); methyl cyclohexylene diisocyanate ; triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane diisocyanate (“TMDI”). The most preferred saturated diisocyanates are 4,4′-dicyclohexylmethane diisocyanate (“HMDI”) and isophorone diisocyanate (“IPDI”).

Saturated polyols which are appropriate for use in this invention include without limitation polyether polyols such as polytetramethylene ether glycol and poly(oxypropylene) glycol. Suitable saturated polyester polyols include polyethylene adipate glycol, polyethylene propylene adipate glycol, polybutylene adipate glycol, polycarbonate polyol and ethylene oxide-capped polyoxypropylene diols. Saturated polycaprolactone polyols which are useful in the invention include diethylene glycol-initiated polycaprolactone, 1,4-butanediol-initiated polycaprolactone, 1,6-hexanediol-initiated polycaprolactone; trimethylol propane-initiated polycaprolactone, neopentyl glycol initiated polycaprolactone, and polytetramethylene ether glycol-initiated polycaprolactone. The most preferred saturated polyols are polytetramethylene ether glycol and PTMEG-initiated polycaprolactone.

Suitable saturated curatives include 1,4-butanediol, ethylene glycol, diethylene glycol, polytetramethylene ether glycol, propylene glycol; trimethanolpropane; tetra-(2-hydroxypropyl)-ethylenediamine; isomers and mixtures of isomers of cyclohexyldimethylol, isomers and mixtures of isomers of cyclohexane bis(methylamine); triisopropanolamine; ethylene diamine; diethylene triamine; triethylene tetramine; tetraethylene pentamine; 4,4′-dicyclohexylmethane diamine; 2,2,4-trimethyl-1,6-hexanediamine; 2,4,4-trimethyl-1,6-hexanediamine; diethyleneglycol di-(aminopropyl)ether; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,2-bis-(sec-butylamino)cyclohexane; 1,4-bis-(sec-butylamino)cyclohexane; isophorone diamine; hexamethylene diamine; propylene diamine; 1-methyl-2,4-cyclohexyl diamine; 1-methyl-2,6-cyclohexyl diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; imido-bis-propylamine; isomers and mixtures of isomers of diaminocyclohexane; monoethanolamine; diethanolamine; triethanolamine; monoisopropanolamine; and diisopropanolamine. The most preferred saturated curatives are 1,4-butanediol, 1,4-cyclohexyldimethylol and 4,4′-bis-(sec-butylamino)-dicyclohexylmethane.

The compositions of the invention may also be polyurea-based, which are distinctly different from polyurethane compositions, but also result in desirable aerodynamic and aesthetic characteristics when used in golf ball components. The polyurea-based compositions are preferably saturated in nature.

Without being bound to any particular theory, it is now believed that substitution of the long chain polyol segment in the polyurethane prepolymer with a long chain polyamine oligomer soft segment to form a polyurea prepolymer, improves shear, cut, and resiliency, as well as adhesion to other components. Thus, the polyurea compositions of this invention may be formed from the reaction product of an isocyanate and polyamine prepolymer crosslinked with a curing agent. For example, polyurea-based compositions of the invention may be prepared from at least one isocyanate, at least one polyether amine, and at least one diol curing agent or at least one diamine curing agent.

Any polyamine available to one of ordinary skill in the art is suitable for use in the polyurea prepolymer. Polyether amines are particularly suitable for use in the prepolymer. As used herein, “polyether amines” refer to at least polyoxyalkyleneamines containing primary amino groups attached to the terminus of a polyether backbone. Due to the rapid reaction of isocyanate and amine, and the insolubility of many urea products, however, the selection of diamines and polyether amines is limited to those allowing the successful formation of the polyurea prepolymers. In one embodiment, the polyether backbone is based on tetramethylene, propylene, ethylene, trimethylolpropane, glycerin, and mixtures thereof.

Suitable polyether amines include, but are not limited to, methyldiethanolamine; polyoxyalkylenediamines such as, polytetramethylene ether diamines, polyoxypropylenetriamine, and polyoxypropylene diamines; poly(ethylene oxide capped oxypropylene)ether diamines; propylene oxide-based triamines; triethyleneglycoldiamines; trimethylolpropane-based triamines; glycerin-based triamines; and mixtures thereof. In one embodiment, the polyether amine used to form the prepolymer is JEFFAMINE® D2000 (manufactured by Huntsman Chemical Co. of Austin, Tex.).

The molecular weight of the polyether amine for use in the polyurea prepolymer may range from about 100 to about 5000. As used herein, the term “about” is used in connection with one or more numbers or numerical ranges, should be understood to refer to all such numbers, including all numbers in a range. In one embodiment, the polyether amine molecular weight is about 200 or greater, preferably about 230 or greater. In another embodiment, the molecular weight of the polyether amine is about 4000 or less. In yet another embodiment, the molecular weight of the polyether amine is about 600 or greater. In still another embodiment, the molecular weight of the polyether amine is about 3000 or less. In yet another embodiment, the molecular weight of the polyether amine is between about 1000 and about 3000, and more preferably is between about 1500 to about 2500. Because lower molecular weight polyether amines may be prone to forming solid polyureas, a higher molecular weight oligomer, such as Jeffamine D2000, is preferred.

In one embodiment, the polyether amine has the generic structure:

wherein the repeating unit x has a value ranging from about 1 to about 70. Even more preferably, the repeating unit may be from about 5 to about 50, and even more preferably is from about 12 to about 35.

In another embodiment, the polyether amine has the generic structure:

wherein the repeating units x and z have combined values from about 3.6 to about 8 and the repeating unit y has a value ranging from about 9 to about 50, and wherein R is —(CH2)a—, where “a” may be a repeating unit ranging from about 1 to about 10.

In yet another embodiment, the polyether amine has the generic structure:

H2N—(R)—O—(R)—O—(R)—NH2

wherein R is —(CH2)a—, and “a” may be a repeating unit ranging from about 1 to about 10.

As briefly discussed above, some amines may be unsuitable for reaction with the isocyanate because of the rapid reaction between the two components. In particular, shorter chain amines are fast reacting. In one embodiment, however, a hindered secondary diamine may be suitable for use in the prepolymer. Without being bound to any particular theory, it is believed that an amine with a high level of stearic hindrance, e.g., a tertiary butyl group on the nitrogen atom, has a slower reaction rate than an amine with no hindrance or a low level of hindrance. For example, 4,4′-bis-(sec-butylamino)-dicyclohexylmethane (CLEARLINK® 1000) may be suitable for use in combination with an isocyanate to form the polyurea prepolymer.

Any isocyanate available to one of ordinary skill in the art is suitable for use in the polyurea prepolymer. Isocyanates for use with the present invention include aliphatic, cycloaliphatic, araliphatic, aromatic, any derivatives thereof, and combinations of these compounds having two or more isocyanate (NCO) groups per molecule. The isocyanates may be organic polyisocyanate-terminated prepolymers. The isocyanate-containing reactable component may also include any isocyanate-functional monomer, dimer, trimer, or multimeric adduct thereof, prepolymer, quasi-prepolymer, or mixtures thereof. Isocyanate-functional compounds may include monoisocyanates or polyisocyanates that include any isocyanate functionality of two or more.

Suitable isocyanate-containing components include diisocyanates having the generic structure: O═C═N—R—N═C═O, where R is preferably a cyclic, aromatic, or linear or branched hydrocarbon moiety containing from about 1 to about 20 carbon atoms. The diisocyanate may also contain one or more cyclic groups or one or more phenyl groups. When multiple cyclic or aromatic groups are present, linear and/or branched hydrocarbons containing from about 1 to about 10 carbon atoms can be present as spacers between the cyclic or aromatic groups. In some cases, the cyclic or aromatic group(s) may be substituted at the 2-, 3-, and/or 4-positions, or at the ortho-, meta-, and/or para-positions, respectively. Substituted groups may include, but are not limited to, halogens, primary, secondary, or tertiary hydrocarbon groups, or a mixture thereof.

Examples of diisocyanates that can be used with the present invention include, but are not limited to, substituted and isomeric mixtures including 2,2′-, 2,4′-, and 4,4′-diphenylmethane diisocyanate (MDI); 3,3′-dimethyl-4,4′-biphenylene diisocyanate (TODI); toluene diisocyanate (TDI); polymeric MDI; carbodiimide-modified liquid 4,4′-diphenylmethane diisocyanate; para-phenylene diisocyanate (PPDI); meta-phenylene diisocyanate (MPDI); triphenyl methane-4,4′- and triphenyl methane-4,4′-triisocyanate; naphthylene-1,5-diisocyanate; 2,4′-, 4,4′-, and 2,2-biphenyl diisocyanate; polyphenyl polymethylene polyisocyanate (PMDI); mixtures of MDI and PMDI; mixtures of PMDI and TDI; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,2-diisocyanate; tetramethylene-1,3-diisocyanate; tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate (HDI); octamethylene diisocyanate; decamethylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate (HTDI); 2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane diisocyanate; 4,4′-dicyclohexyl diisocyanate; 2,4′-dicyclohexyl diisocyanate; 1,3,5-cyclohexane triisocyanate; isocyanatomethylcyclohexane isocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; isocyanatoethylcyclohexane isocyanate; bis(isocyanatomethyl)-cyclohexane diisocyanate; 4,4′-bis(isocyanatomethyl)dicyclohexane; 2,4′-bis(isocyanatomethyl) dicyclohexane; isophorone diisocyanate (IPDI); triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane diisocyanate (TMDI); 4,4′-dicyclohexylmethane diisocyanate (H12MDI); 2,4-hexahydrotoluene diisocyanate; 2,6-hexahydrotoluene diisocyanate; 1,2-, 1,3-, and 1,4-phenylene diisocyanate; aromatic aliphatic isocyanate, such as 1,2-, 1,3-, and 1,4-xylene diisocyanate; meta-tetramethylxylene diisocyanate (m-TMXDI); para-tetramethylxylene diisocyanate (p-TMXDI); trimerized isocyanurate of any polyisocyanate, such as isocyanurate of toluene diisocyanate, trimer of diphenylmethane diisocyanate, trimer of tetramethylxylene diisocyanate, isocyanurate of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate, and mixtures thereof; dimerized uredione of any polyisocyanate, such as uretdione of toluene diisocyanate, uretdione of hexamethylene diisocyanate, and mixtures thereof; modified polyisocyanate derived from the above isocyanates and polyisocyanates; and mixtures thereof.

Examples of saturated diisocyanates that can be used with the present invention include, but are not limited to, ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene diisocyanate; tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate (HDI); octamethylene diisocyanate; decamethylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; methyl-cyclohexylene diisocyanate (HTDI); 2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane diisocyanate; 4,4′-dicyclohexyl diisocyanate; 2,4′-dicyclohexyl diisocyanate; 1,3,5-cyclohexane triisocyanate; isocyanatomethylcyclohexane isocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; isocyanatoethylcyclohexane isocyanate; bis(isocyanatomethyl)-cyclohexane diisocyanate; 4,4′-bis(isocyanatomethyl)dicyclohexane; 2,4′-bis(isocyanatomethyl)dicyclohexane; isophorone diisocyanate (IPDI); triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane diisocyanate (TMDI); 4,4′-dicyclohexylmethane diisocyanate (H12MDI); 2,4-hexahydrotoluene diisocyanate; 2,6-hexahydrotoluene diisocyanate; and mixtures thereof. Aromatic aliphatic isocyanates may also be used to form light stable materials. Examples of such isocyanates include 1,2-, 1,3-, and 1,4-xylene diisocyanate; meta-tetramethylxylene diisocyanate (m-TMXDI); para-tetramethylxylene diisocyanate (p-TMXDI); trimerized isocyanurate of any polyisocyanate, such as isocyanurate of toluene diisocyanate, trimer of diphenylmethane diisocyanate, trimer of tetramethylxylene diisocyanate, isocyanurate of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate, and mixtures thereof; dimerized uredione of any polyisocyanate, such as uretdione of toluene diisocyanate, uretdione of hexamethylene diisocyanate, and mixtures thereof; modified polyisocyanate derived from the above isocyanates and polyisocyanates; and mixtures thereof. In addition, the aromatic aliphatic isocyanates may be mixed with any of the saturated isocyanates listed above for the purposes of this invention.

The number of unreacted NCO groups in the polyurea prepolymer of isocyanate and polyether amine may be varied to control such factors as the speed of the reaction, the resultant hardness of the composition, and the like. For instance, the number of unreacted NCO groups in the polyurea prepolymer of isocyanate and polyether amine may be less than about 14 percent. In one embodiment, the polyurea prepolymer has from about 5 percent to about 11 percent unreacted NCO groups, and even more preferably has from about 6 to about 9.5 percent unreacted NCO groups. In one embodiment, the percentage of unreacted NCO groups is about 3 percent to about 9 percent. Alternatively, the percentage of unreacted NCO groups in the polyurea prepolymer may be about 7.5 percent or less, and more preferably, about 7 percent or less. In another embodiment, the unreacted NCO content is from about 2.5 percent to about 7.5 percent, and more preferably from about 4 percent to about 6.5 percent.

When formed, polyurea prepolymers may contain about 10 percent to about 20 percent by weight of the prepolymer of free isocyanate monomer. Thus, in one embodiment, the polyurea prepolymer may be stripped of the free isocyanate monomer. For example, after stripping, the prepolymer may contain about 1 percent or less free isocyanate monomer. In another embodiment, the prepolymer contains about 0.5 percent by weight or less of free isocyanate monomer.

The polyether amine may be blended with additional polyols to formulate copolymers that are reacted with excess isocyanate to form the polyurea prepolymer. In one embodiment, less than about 30 percent polyol by weight of the copolymer is blended with the saturated polyether amine. In another embodiment, less than about 20 percent polyol by weight of the copolymer, preferably less than about 15 percent by weight of the copolymer, is blended with the polyether amine. The polyols listed above with respect to the polyurethane prepolymer, e.g., polyether polyols, polycaprolactone polyols, polyester polyols, polycarbonate polyols, hydrocarbon polyols, other polyols, and mixtures thereof, are also suitable for blending with the polyether amine. The molecular weight of these polymers may be from about 200 to about 4000, but also may be from about 1000 to about 3000, and more preferably are from about 1500 to about 2500.

The polyurea composition can be formed by crosslinking the polyurea prepolymer with a single curing agent or a blend of curing agents. The curing agent of the invention is preferably an amine-terminated curing agent, more preferably a secondary diamine curing agent so that the composition contains only urea linkages. In one embodiment, the amine-terminated curing agent may have a molecular weight of about 64 or greater. In another embodiment, the molecular weight of the amine-curing agent is about 2000 or less. As discussed above, certain amine-terminated curing agents may be modified with a compatible amine-terminated freezing point depressing agent or mixture of compatible freezing point depressing agents.

Suitable amine-terminated curing agents include, but are not limited to, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,4-bis-(sec-butylamino)-cyclohexane; 1,2-bis-(sec-butylamino)-cyclohexane; derivatives of 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethane diamine; 1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine); diethylene glycol di-(aminopropyl) ether; 2-methylpentamethylene-diamine; diaminocyclohexane; diethylene triamine; triethylene tetramine; tetraethylene pentamine; propylene diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; dipropylene triamine; imido-bis-propylamine; monoethanolamine, diethanolamine; triethanolamine; monoisopropanolamine, diisopropanolamine; isophoronediamine; 4,4′-methylenebis-(2-chloroaniline); 3,5;dimethylthio-2,4-toluenediamine; 3,5-dimethylthio-2,6-toluenediamine; 3,5-diethylthio-2,4-toluenediamine; 3,5;diethylthio-2,6-toluenediamine; 4,4′-bis-(sec-butylamino)-diphenylmethane and derivatives thereof; 1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene; N,N′-dialkylamino-diphenylmethane; N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylene diamine; trimethyleneglycol-di-p-aminobenzoate; polytetramethyleneoxide-di-p-aminobenzoate; 4,4′-methylenebis-(3-chloro-2,6-diethyleneaniline); 4,4′-methylenebis-(2,6-diethylaniline); meta-phenylenediamine; paraphenylenediamine; and mixtures thereof. In one embodiment, the amine-terminated curing agent is 4,4′-bis-(sec-butylamino)-dicyclohexylmethane.

Suitable saturated amine-terminated curing agents include, but are not limited to, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene di amine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,4-bis-(sec-butylamino)-cyclohexane; 1,2-bis-(sec-butylamino)-cyclohexane; derivatives of 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethane diamine; 4,4′-methylenebis-(2,6-diethylaminocyclohexane; 1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine); diethylene glycol di-(aminopropyl)ether; 2-methylpentamethylene-diamine; diaminocyclohexane; diethylene triamine; triethylene tetramine; tetraethylene pentamine; propylene diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; imido-bis-propylamine; monoethanolamine, diethanolamine; triethanolamine; monoisopropanolamine, diisopropanolamine; isophoronediamine; triisopropanolamine; and mixtures thereof. In addition, any of the polyether amines listed above may be used as curing agents to react with the polyurea prepolymers.

Suitable catalysts include, but are not limited to bismuth catalyst, oleic acid, triethylenediamine (DABCO®-33LV), di-butyltin dilaurate (DABCO®-T12) and acetic acid. The most preferred catalyst is di-butyltin dilaurate (DABCO®-T12). DABCO® materials are manufactured by Air Products and Chemicals, Inc.

Thermoplastic materials may be blended with other thermoplastic materials, but thermosetting materials are difficult if not impossible to blend homogeneously after the thermosetting materials are formed. Preferably, the saturated polyurethane comprises from about 1% to about 100%, more preferably from about 10% to about 75% of the cover composition and/or the intermediate layer composition. About 90% to about 10%, more preferably from about 90% to about 25% of the cover and/or the intermediate layer composition is comprised of one or more other polymers and/or other materials as described below. Such polymers include, but are not limited to polyurethane/polyurea ionomers, polyurethanes or polyureas, epoxy resins, polyethylenes, polyamides and polyesters, polycarbonates and polyacrylin. Unless otherwise stated herein, all percentages are given in percent by weight of the total composition of the golf ball layer in question.

Polyurethane prepolymers are produced by combining at least one polyol, such as a polyether, polycaprolactone, polycarbonate or a polyester, and at least one isocyanate. Thermosetting polyurethanes are obtained by curing at least one polyurethane prepolymer with a curing agent selected from a polyamine, triol or tetraol. Thermoplastic polyurethanes are obtained by curing at least one polyurethane prepolymer with a diol curing agent. The choice of the curatives is critical because some urethane elastomers that are cured with a diol and/or blends of diols do not produce urethane elastomers with the impact resistance required in a golf ball cover. Blending the polyamine curatives with diol cured urethane elastomeric formulations leads to the production of thermoset urethanes with improved impact and cut resistance.

Thermoplastic polyurethanes may be blended with suitable materials to produce a thermoplastic end product. Examples of such additional materials may include ionomers such as the SURLYN®, ESCOR® and IOTEK® copolymers described above.

Other suitable materials which may be combined with the saturated polyurethanes in forming the cover and/or intermediate layer(s) of the golf balls of the invention include ionic or non-ionic polyurethanes and polyureas, epoxy resins, polyethylenes, polyamides and polyesters. For example, the cover and/or intermediate layer may be formed from a blend of at least one saturated polyurethane and thermoplastic or thermoset ionic and non-ionic urethanes and polyurethanes, cationic urethane ionomers and urethane epoxies, ionic and non-ionic polyureas and blends thereof. Examples of suitable urethane ionomers are disclosed in U.S. Pat. No. 5,692,974 entitled “Golf Ball Covers”, the disclosure of which is hereby incorporated by reference in its entirety. Other examples of suitable polyurethanes are described in U.S. Pat. No. 5,334,673. Examples of appropriate polyureas are discussed in U.S. Pat. No. 5,484,870 and examples of suitable polyurethanes cured with epoxy group containing curing agents are disclosed in U.S. Pat. No. 5,908,358, the disclosures of which are hereby incorporated herein by reference in their entirety.

A variety of conventional components can be added to the cover compositions of the present invention. These include, but are not limited to, white pigment such as TiO2, ZnO, optical brighteners, surfactants, processing aids, foaming agents, density-controlling fillers, UV stabilizers and light stabilizers. Saturated polyurethanes are resistant to discoloration. However, they are not immune to deterioration in their mechanical properties upon weathering. Addition of UV absorbers and light stabilizers therefore helps to maintain the tensile strength and elongation of the saturated polyurethane elastomers. Suitable UV absorbers and light stabilizers include TINUVIN® 328, TINUVIN® 213, TINUVIN® 765, TINUVIN® 770 and TINUVIN® 622. The preferred UV absorber is TINUVIN® 328, and the preferred light stabilizer is TINUVIN® 765. TINUVIN® products are available from Ciba-Geigy. Dyes, as well as optical brighteners and fluorescent pigments may also be included in the golf ball covers produced with polymers formed according to the present invention. Such additional ingredients may be added in any amounts that will achieve their desired purpose.

Any method known to one of ordinary skill in the art may be used to polyurethanes of the present invention. One commonly employed method, known in the art as a one-shot method, involves concurrent mixing of the polyisocyanate, polyol, and curing agent. This method results in a mixture that is inhomogenous (more random) and affords the manufacturer less control over the molecular structure of the resultant composition. A preferred method of mixing is known as a prepolymer method. In this method, the polyisocyanate and the polyol are mixed separately prior to addition of the curing agent. This method affords a more homogeneous mixture resulting in a more consistent polymer composition. Other methods suitable for forming the layers of the present invention include reaction injection molding (“RIM”), liquid injection molding (“LIM”), and pre-reacting the components to form an injection moldable thermoplastic polyurethane and then injection molding, all of which are known to one of ordinary skill in the art.

Additional components which can be added to the polyurethane composition include UV stabilizers and other dyes, as well as optical brighteners and fluorescent pigments and dyes. Such additional ingredients may be added in any amounts that will achieve their desired purpose. It has been found by the present invention that the use of a castable, reactive material, which is applied in a fluid form, makes it possible to obtain very thin outer cover layers on golf balls. Specifically, it has been found that castable, reactive liquids, which react to form a urethane elastomer material, provide desirable very thin outer cover layers.

The castable, reactive liquid employed to form the urethane elastomer material can be applied over the core using a variety of application techniques such as spraying, dipping, spin coating, or flow coating methods which are well known in the art. An example of a suitable coating technique is that which is disclosed in U.S. Pat. No. 5,733,428, the disclosure of which is hereby incorporated by reference in its entirety.

The outer cover is preferably formed around the inner cover by mixing and introducing the material in the mold halves. It is important that the viscosity be measured over time, so that the subsequent steps of filling each mold half, introducing the core into one half and closing the mold can be properly timed for accomplishing centering of the core cover halves fusion and achieving overall uniformity. Suitable viscosity range of the curing urethane mix for introducing cores into the mold halves is determined to be approximately between about 2,000 cP and about 30,000 cP, with the preferred range of about 8,000 cP to about 15,000 cP.

To start the cover formation, mixing of the prepolymer and curative is accomplished in motorized mixer including mixing head by feeding through lines metered amounts of curative and prepolymer. Top preheated mold halves are filled and placed in fixture units using centering pins moving into holes in each mold. At a later time, a bottom mold half or a series of bottom mold halves have similar mixture amounts introduced into the cavity. After the reacting materials have resided in top mold halves for about 40 to about 80 seconds, a core is lowered at a controlled speed into the gelling reacting mixture.