Golf ball layers having improved barrier properties

Abstract

A golf ball comprising a core having an outer diameter of about 1.50 inches to about 1.62 inches; a cover comprising polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, or a combination thereof; and an intermediate layer disposed between the core and the cover, the intermediate layer having a thickness of about 0.005 inches to about 0.030 inches and comprising a matrix polymer and a barrier component comprising a physical barrier to moisture transmission and a chemical barrier to moisture transmission.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional utility patent application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/083,453, filed Mar. 18, 2005, which is a continuation of U.S. patent application Ser. No. 10/754,781, filed Jan. 9, 2004, now U.S. Pat. No. 6,932,720, which is a continuation of U.S. patent application Ser. No. 10/103,414, filed Mar. 21, 2002, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 09/973,342, filed Oct. 9, 2001, now U.S. Pat. No. 6,632,147. This non-provisional utility patent application is also a continuation-in-part of co-pending U.S. patent application Ser. No. 10/789,252, filed Feb. 27, 2004, which is a continuation of U.S. patent application Ser. No. 10/157,521, filed May 29, 2002, now U.S. Pat. No. 6,802,784. These parent applications and patents are each hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to golf balls and golf ball layers having improved moisture and/or oxygen barrier properties resulting from relatively low transmission/permeation rates. In particular, these improved barrier properties can be obtained by utilizing functionalized platelets that can simultaneously act as physical and chemical obstacles for moisture and/or oxygen transmission.

BACKGROUND OF THE INVENTION

Solid core golf balls are well known in the art. Typically, the core is made from polybutadiene rubber material, which provides the primary source of resiliency for the golf ball. U.S. Pat. Nos. 3,241,834 and 3,313,545 disclose the early work in polybutadiene chemistry. It is also known in the art that increasing the cross-link density of polybutadiene can increase the resiliency of the core. The core is typically protected by a cover from repeated impacts from the golf clubs. The golf ball may comprise additional layers, which can be an outer core or an inner cover layer. One or more of these additional layers may be a wound layer of stretched elastic windings to increase the ball's resiliency.

A known drawback of polybutadiene cores cross-linked with peroxide and/or zinc diacrylate is that this material is adversely affected by moisture. Water moisture vapor reduces the resiliency of the cores and degrades its properties. A polybutadiene core will absorb water and loose its resilience. Thus, these cores must be covered quickly to maintain optimum ball properties. The cover is typically made from ionomer resins, balata, and urethane, among other materials. The ionomer covers, particularly the harder ionomers, offer some protection against the penetration of water vapor. However, it is more difficult to control or impart spin to balls with hard covers. Conventional urethane covers, on the other hand, while providing better ball control, offer less resistance to water vapor than ionomer covers.

Prolonged exposure to high humidity and elevated temperature may be sufficient to allow water vapor to invade the cores of some commercially available golf balls. For example at 110° F. and 90% humidity for a sixty day period, significant amounts of moisture enter the cores and reduce the initial velocity of the balls by 1.8 ft/s to 4.0 ft/s or greater. The change in Atti compression may vary from about 5 to about 10, or greater. The absorbed water vapor also reduces the coefficient of restitution (“COR”) of the ball.

Several prior patents have addressed the water vapor absorption problem. U.S. Pat. No. 5,820,488 discloses a golf ball with a solid inner core, an outer core, and a water vapor barrier layer disposed therebetween. The water vapor barrier layer preferably has a water vapor transmission rate lower than that of the cover layer. The water vapor barrier layer can be a polyvinylidene chloride layer. It can also be formed by an in situ reaction between a barrier-forming material and the outer surface of the core. Alternatively, the water vapor barrier layer can be a vermiculite layer. U.S. Patent Nos. 5,885,172 and 6,132,324 disclose, among other things, a golf ball with a polybutadiene or wound core with an ionomer resin inner cover and a relatively soft outer cover. The hard ionomer inner cover offers some resistance to water vapor penetration and the soft outer cover provides the desirable ball control. It is also desirable to minimize the water vapor barrier layer such that other properties of the ball are unaffected. Additionally, U.S. Pat. No. 5,875,891 discloses an impermeable packaging for golf balls. The impermeable packaging acts as a moisture barrier limiting moisture absorption by golf balls during storage.

Generally, the addition of platelet particles, derived from certain clays, to polymers to improve the physical barrier properties of a polymer has also been taught. These so-called nanocomposites are formed by dispersing the platelet particles in a matrix polymer. To effectively improve the gas barrier properties as well as to produce an adequate level of clarity in the matrix polymer, the platelet particles should be partially or fully exfoliated. To achieve this exfoliation, tether molecules are contacted onto the clay. The use of a variety of possible tether molecules has been taught. The tethers are generally organic cations, such as quaternary ammonium salts, phosphonium salts, and sulfonium salts. These nanocomposite materials have been used in packaging and container applications as monolayers or as one or more layers of a multilayer structure.

Oxygen transmission is another potential, though less addressed, problem in golf balls. To extend the lifetime of oxygen sensitive products (e.g., beer and fruit drinks), there are many commercial containers that incorporate physical oxygen barriers (passive barrier) and/or oxygen absorbers (active chemical barrier). In these packages, a physical oxygen barrier is used to effectively reduce the permeation of oxygen into the package, while a separate oxygen absorber is used to chemically react with oxygen permeating into or trapped in the package.

Similarly, chemical scavengers incorporated into packaging materials such as polyester polymers are known. For instance, International Publication Nos. WO 98/12127 and WO 98/12244 disclose the preparation of blends of PET containing either oxidizable metals or modified polybutadienes. However, these materials offer only chemical scavenging and no passive (physical) barrier. In addition, these materials have not heretofore been contemplated for use in golf balls.

Hence, there remains a need for golf balls with improved water vapor and/or oxygen barrier layers and improved methods for applying water vapor/oxygen barrier layers over the center or core of the golf ball.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball including a core having an outer diameter of about 1.50 inches to about 1.62 inches; a cover including polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, or a combination thereof; and an intermediate layer disposed between the core and the cover, the intermediate layer having a thickness of about 0.005 inches to about 0.030 inches and including a matrix polymer and a barrier component comprising a physical barrier to moisture transmission and a chemical barrier to moisture transmission.

The intermediate layer should have a moisture vapor transmission rate that is lower than that of the cover. The matrix polymer preferably includes polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, ionomers, or a combination thereof. The core can include a center and an outer core layer. Preferably, the outer core layer has a thickness of about 0.05 inches to about 0.15 inches, the intermediate layer has a thickness of about 0.010 inches to about 0.025 inches, and the cover has a thickness of about 0.010 inches to about 0.050 inches.

The barrier component preferably includes an intercalated organoclay chemically-modified with an ammonium compound, a phosphonium compound, a sulfonium compound, or a combination thereof to provide the chemical barrier to moisture transmission. In a preferred embodiment, the barrier component includes a compound having the formula:
where M comprises nitrogen, phosphorous, or sulfur; where X⁻ comprises an anionic counterion;
and where R₁, R₂, R₃, and R₄ comprise hydrogen, an organic moiety, or an oligomeric organic moiety. Ideally, the intermediate layer has a moisture vapor transmission rate of less than about 0.4 g·mm/m²·day.

The present invention is also directed to a golf ball including a core; a cover; and an intermediate layer disposed between the core and the cover, the intermediate layer having a thickness of about 0.005 inches to about 0.030 inches and being formed from a matrix polymer and a barrier component, the barrier component including a physical barrier to moisture transmission, and being chemically-modified with an ammonium compound, a phosphonium compound, a sulfonium compound, or a combination thereof to provide a chemical barrier to moisture transmission.

The present invention is further directed to a golf ball including a core having an outer diameter of about 1.50 inches to about 1.62 inches, the core including a center and an outer core layer; a cover including polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, or a combination thereof; and an intermediate layer having a thickness of about 0.005 inches to about 0.030 inches disposed between the core and the cover, the intermediate layer including a matrix polymer selected from the group consisting of polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, and ionomers; and a barrier component comprising a physical barrier to moisture transmission and a chemical barrier to moisture transmission, wherein the barrier component comprises a compound having the formula:
where M comprises nitrogen, phosphorous, or sulfur; where X⁻ comprises an anionic counterion;
and where R₁, R₂, R₃, and R₄ comprise hydrogen, an organic moiety, or an oligomeric organic moiety.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present invention involves a golf ball containing, in one or more core, cover or intermediate layers, a single composite component that provides both physical and chemical obstacles for moisture and/or oxygen transmission. In a preferred embodiment, the single composite component comprises a first element capable of providing a physical barrier to moisture and/or oxygen transmission and a second element, attached to the first element, and capable of providing a chemical barrier to moisture and/or oxygen transmission.

In some embodiments, the single component is present in one layer. In other embodiments, the single component is present in more than one layer. In one embodiment, one or more of the layers of the golf ball contains at least about 0.1% of the single component, based on the weight of each layer. The single component is preferably present in one or more intermediate layers between the one or more core layers and the one or more cover layers.

In one embodiment, the single composite component includes platelet particles having attached thereto at least one moisture and/or oxygen scavenging moiety. In this embodiment, the platelet particles themselves can provide the physical obstacles to moisture and/or oxygen transmission, while the at least one moisture and/or oxygen scavenging moiety can provide a chemically reactive trap for moisture and/or oxygen, thus reducing, inhibiting, and/or preventing moisture and/or oxygen transmission. Preferably, in this embodiment, the moisture and/or oxygen scavenging moiety can be an organic cation, so that the platelets have attached thereto at least one moisture and/or oxygen scavenging organic cation, such as those disclosed in U.S. Pat. No. 6,610,772, which is incorporated herein by express reference thereto.

In another embodiment, the platelet particles are intercalated and/or layered platelet particles made using techniques known in the art, e.g., by reaction of an organic cation salt with a swellable layered platelet particle precursor material. In this embodiment, the cation salt of the present invention can advantageously serve the dual purpose of aiding the exfoliation of the swellable layered platelet precursor and imparting a moisture- and/or oxygen-scavenging capability to the platelet particles (e.g., which may be activated by an oxidation catalyst). It should be understood that one, or more than one, organic salt may be used to treat the swellable layered platelet particle precursor material, and that each organic salt need not necessarily serve both purposes of exfoliating and scavenging. For example, two distinct organic salts may be used, of which one would predominantly impart the exfoliation properties while the second would predominantly serve to impart the scavenging capability. In addition, some organic salts may serve the purpose of binding the oxidation catalyst, if present, near the platelet particles.

The swellable layered platelet particle material can be a silicate material that is a-free flowing powder having a cation exchange capacity of between about 0.3-3.0 mEq/g of mineral. The platelet material may have a wide variety of exchangeable cations present in the galleries between the layers of the silicate material, including, but not limited to, cations comprising the alkaline metals (group IA), the alkaline earth metals (group IIA), and their mixtures. A preferred cation is sodium; however, any cation or combination of cations may be used, provided that most of the cations are exchanged for onium ions in the process of forming the composite component. Preferably, the individual layers of the platelet particles should have a thickness of less than about 2 nm and a diameter in the range from about 10 nm to about 1000 nm. Useful swellable layered silicate materials include natural, synthetic, and modified phyllosilicates. Examples of such silicates include, but are not limited to, smectite clays, such as montmorillonite, saponite, hectorite, mica, vermiculite, bentonite, nontronite, beidellite, volkonskoite, sauconite, magadiite, kenyaite, and the like; synthetic silicates, such as synthetic mica, synthetic saponite, and synthetic hectorite; modified silicates, such as fluorinated montmorillonite; and the like; and combinations thereof. Other platelet- or layered-type materials such as chalcogens may also or alternately be used. Suitable silicate materials are commercially available from various companies, including, but not limited to, Southern Clay Products of Gonzalez, Tex., and Nanocor, Inc., of Arlington Heights, Ill. Generally, the silicate materials are an agglomeration of platelet particles, called tactoids, which are closely stacked together like cards. Methods to modify layered particles with organic cations are known, and any of these may be used in the process of forming the composite component.

Modified layered platelet particles with one or more organic cations, at least one of which can scavenge moisture and/or oxygen, may be prepared, for example, by the processes of dispersing the platelet particles in water, adding the organic cation salt(s) (neat or dissolved in water or alcohol) with agitation, then blending for a period of time sufficient for the organic cations to exchange most of the metal cations in the galleries between the layers of the clay material. Then, the organically modified layered particle material can be isolated by methods know in the art including, but not limited to, filtration, centrifugation, spray drying, and the like, and combinations thereof. It is desirable to use a sufficient amount of the organic salt to permit the exchange of most of the metal cations in the galleries of the layered particles for organic cations. The particle size of the resulting organoclay can advantageously be reduced in size by methods known in the art, including, but not limited to, grinding, pulverizing, hammer-milling, jet milling, and their combinations. It is preferred that the average particle size be reduced to less than about 100 μm in diameter.

Useful organic cation salts for the purposes of this invention are capable of hydrogen bonding with the selected matrix polymer, binding water vapor and/or free oxygen and can be represented as follows:
where M represents nitrogen, phosphorous, or less preferably sulfur, and where X⁻ represents an anion, usually selected from the group of halogen, hydroxide, and acetate anions. The R groups (R₁, R₂, R₃, and R₄) are each independently selected from organic or oligomeric organic moieties. In the case of M being sulfur, one of R₁, R₂, R₃, and R₄ represents a lone pair of electrons. Some, but not all, of the R groups may be hydrogen. At least one of R₁, R₂, R₃, and R₄ should be an organic moiety capable of scavenging moisture/oxygen. Oxygen scavenging moieties may be any organic moiety containing an easily abstractable hydrogen atom or one or more olefinic unsaturations. Examples of suitable oxygen scavenging moieties include, but are not limited to, benzylic groups, allylic groups, ether groups, poly(alkylene glycol)s, molecules with tertiary hydrogens, polyolefins with some level of remaining unsaturation, amines, amides, poly(amine)s, poly(amide)s, and any other molecules containing a C—H linkage with a homolytic bond strength of less than or equal to about 93 kcal/mol. Specific examples of such R groups include, but are not limited to, benzyl groups, allyl groups, poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol), poly(pentamethylene glycol), poly(hexamethylene glycol), poly(heptamethylene glycol), poly(octamethylene glycol), polystyrene, poly(propylene), poly(butadiene), and combinations thereof. Individual R groups may also contain more than one different alkylene repeat unit as part of the poly(alkylene glycol) chain, in random or non-random order. The poly(alkylene glycol) units may be linear or branched. The number of alkylene glycol units in the poly(alkylene glycol) may range from only two to very large numbers, but in general may be in the range from about 2 to about 20. Similarly, the number of repeat units in other polymeric R groups (such as polystyrene, poly(propylene), poly(butadiene), and the like) may range from single digit to very large numbers and preferably from about 2 to about 20. Additional examples of useful cation salts with poly(alkylene oxide) groups can be derived from poly(ethylene oxide) amines and poly(propylene oxide) amines that are commercially available form Huntsman Corp. as JEFFAMINES®. To be useful, these amines could be converted to their conjugate acid salt, such as a JEFFAMINE® hydrochloride, or be quaternized by standard alkylation techniques, such as reaction with alkyl halides, dimethyl sulfate, or the like.

As used herein, the term “monomer” means any unit that is polymerized to form a polymer and includes, but is not limited to, monomers, dimers, oligomers, and/or macromonomers. As used herein, the terms “polymer,” “polymers,” and “polymeric” are generic to macromolecules containing monomer repeat units and include, but are not limited to, oligomers, homopolymers, copolymers, including random copolymers, statistical copolymers, alternating copolymers, periodic copolymer, bipolymers, terpolymers, quaterpolymers, and other forms of copolymers, as well as adducts thereof, substituted derivatives thereof, and combinations thereof. Such polymers can be linear, branched, hyper-branched, crosslinked, block, di-block, multi-block, graft, isotactic, syndiotactic, stereoregular, atactic, gradient, multi-arm star, comb, dendritic, and/or any combination thereof.

Other possible organic cations may have a structure in which two of the R substituents on the M atom are covalently bonded to each other to form a cyclic structure. Such structures may be advantageous for oxygen scavenging, since oxidative cleavage of a bond in the backbone of such a ring would result in fragments that are still attached to the platelet material. In this way, the possibility of forming low molecular weight extractable species as a result of the oxidation process is reduced. In more complex structures, more than two of the R groups may be covalently bonded to form multiple ring structures.

In still other structures, one or more of the R groups may be simultaneously bonded to more than one M atom. An example of one such structure might be represented by:
where the M atoms, M₁ and M₂, each individually represent nitrogen, phosphorous, or less preferably sulfur, and where R₅, R₇, R₈, R₉, R₁₀, and R₁₁ are selected from the same group as R₁, R₂, R₃, and R₄ and may or may not serve a moisture/oxygen scavenging role. In the case of M₁ being sulfur, one of R₅, R₈, and R₁₀ represents a pair of electrons, and in the case of M₂ being sulfur, one of R₇, R₉, and R₁₁ represents a pair of electrons. The linking group R₆ can be selected from moieties similar to those of the singly attached R groups, R₁, R₂, R₃, and R₄, but differs from them in that R₆ is doubly attached to both M₁ and M₂. It should be understood that other structures with more than one linking group between the nitrogen, phosphorous, and/or sulfur centers are also possible.

Additional structures might involve more than two nitrogen, phosphorous, and/or sulfur atoms linked into the same molecule. An example of such a structure may be derived from calixarenes, which have the general structure:
where n is a number between about 3 and about 9. These calixarenes may be modified by attaching various groups at some position on the phenyl rings, at the oxygen of the phenolic OHs, and/or at the R″s. One, some, or all of these groups could, in turn, be attached to ammonium, phosphonium, and/or sulfonium centers. In such a way, a calixarene attached to a platelet particle by one or more ammonium, phosphonium, or sulfonium centers could be created. The links in the backbone of the calixarene ring contain benzylic hydrogens and may therefore serve as oxygen scavengers. Additionally, the calixarene may be further modified by attaching additional oxygen scavenging groups to it. For all such structures, it would generally be advantageous to derivatize at least some of the phenolic OH groups in some way, such as functionalization into an ether, since phenolic OH groups can act as antioxidants. However, some level of antioxidant activity may be desirable. Likewise, deprotonation of the calixarene could form a molecular structure in which the charge of multivalent cations could become more balanced between the clay and calixarene.

Additionally, calixresorcinarenes, molecules similar to calixarenes, but based on substituted resorcinol instead of substituted phenols, may be useful in the same manner as calixarenes.

In addition to poly(alkylene glycol)s, cyclic polyethers or oligomers can be used as the oxidizable component of the R group. For example, poly(2,3-dihydrofurandiyl) polymers, e.g., prepared by cationic polymerization of 2,3-dihydrofuran, could be incorporated into an oxygen scavenging R group in the same fashion as the above-mentioned poly(alkylene glycol)s. Additional examples include polymers derived from monomers of structure I or II below, where n+m can be an integer between about 3 and about 10, and R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, and R₁₇ are each independently a hydrogen atom, a lower alkyl group of 1 to 4 carbons, or a halogen:
The lower alkyl represented by R₁₂, R₁₃, R₁₄, R₁₅, R₁₆, and R₁₇ in the monomer units I and II, may be the same or different, and can independently be alkyls having 1-4 carbon atoms, e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, or the like.

In addition to the at least one moisture/oxygen scavenging substituent in the R groups attached to the M atom(s), the other R groups in the organic cation can be selected from a much broader set of molecules, which may or may not be known to possess an oxygen scavenging ability. Examples of useful organic groups can include, but are not limited to, linear or branched alkyl groups having from about 1 to about 22 carbon atoms, aralkyl groups, which are benzyl or substituted benzyl moieties including fused ring moieties having linear chains or branches of about 1 to about 22 carbon atoms in the alkyl portion of the structure, aryl groups such as phenyl and substituted phenyl including fused ring aromatic substituents, beta and gamma unsaturated groups having about six or less carbon atoms, and alkyleneoxide groups having from about 2 to about 6 carbon atoms. Examples of useful oligomeric or polymeric organic groups can include, but are not limited to, poly(alkylene oxide)s, polystyrene, polyacrylates, polycaprolactones, and the like. Additionally, one or more, but not all, of the R substituents may be hydrogen.

Examples of oxygen-scavenging organic cations that may be used as a component in a layer of a golf ball according to the present invention can include, but are not limited to, bis(2-hydroxylethyl)octadecyl methyl ammonium; various alkyl benzyl dimethyl ammonium cations, where alkyl is a linear or branched alkyl group having from about 3 to about 30 carbon atoms, such as octadecyl benzyl dimethyl ammonium, tallow benzyl dimethyl ammonium, ditallow benzyl methyl ammonium, and the like; alkyl phosphonium ions such as trioctyl benzyl phosphonium, triethyl vinylbenzyl phosphonium, dibutyl dodecyl allyl phosphonium, and the like; and mixtures thereof. Illustrative examples of suitable polyalkoxylated ammonium compounds can include those available under the tradenames ETHOQUAD® or ETHOMEEN® from Akzo Chemie America, namely, ETHOQUAD® 18/25 which is octadecyl methyl bis(polyoxyethylene[15]) ammonium chloride and ETHOMEEN® 18/25 which is octadecyl bis(polyoxyethylene[15]) amine, where the brackets refer to the total number of alkylene oxide units. Examples of organoclays suitable for use in the single component include, but are not limited to, CLAYTONE® APA and CLAYTONE® EM (commercially available from Southern Clay Products), and the like.

More than one organic cation salt may be used in the process of preparing a nanocomposite material according to the present invention. In such a case, some of the organic cation salts need only have exfoliating capabilities and limited or no moisture/oxygen scavenging capabilities. For these exfoliating organic cation salts, all of the R groups can be selected from the broader set of molecules that do not necessarily posses an oxygen scavenging capability. Examples of useful organic groups again include, but are not limited to, linear or branched alkyl groups having from about 1 to about 22 carbon atoms, aralkyl groups, which are benzyl or substituted benzyl moieties including fused ring moieties having linear chains or branches from about 1 to about 22 carbon atoms in the alkyl portion of the structure, aryl groups such as phenyls and substituted phenyls including fused ring aromatic substituents, beta- and gamma-unsaturated groups having about six or less carbon atoms, and alkylene oxide groups having from about 2 to about 6 carbon atoms. Examples of useful oligomeric organic groups can include, but are not limited to, poly(alkylene oxide)s, polystyrenes, polyacrylates, polycaprolactones, and the like. For polyamides, hydroxyl and ether moieties can provide potential interaction sites with the hydrogens on the polyamide. Such interactions can advantageously allow greater intercalation of the organoclay by the oligomeric compounds.

Examples of useful exfoliating organic cations that may be used in conjunction with one or more moisture/oxygen scavenging organic cations can include, but are not limited to, alkyl ammonium ions such as dodecyl ammonium, octadecyl ammonium, bis(2-hydroxylethyl) octadecyl methyl ammonium, octadecyl benzyl dimethyl ammonium, tetramethyl ammonium, and the like; alkyl phosphonium ions such as tetrabutyl phosphonium, trioctyl octadecyl phosphonium, tetraoctyl phosphonium, octadecyl triphenyl phosphonium, as well as others well known in the art, such as those disclosed in U.S. Pat. No. 4,136,103, and the like; and mixtures thereof. Illustrative examples of suitable polyalkoxylated ammonium compounds can include those available under the tradenames ETHOQUAD® or ETHOMEEN® from Akzo Chemie America, namely, ETHOQUAD® 18/25 which is octadecyl methyl bis(polyoxyethylene[15]) ammonium chloride and ETHOMEEN® 18/25 which is octadecyl bis(polyoxyethylene[15]) amine, where the brackets refer to the total number of alkylene oxide units.

The moisture/oxygen scavenging organic cation of the present invention may be attached to the platelet particles ionically, covalently or by any other form of chemical, physical, or physico-chemical attachment, including by van der Waals forces. Any type of bonding or attraction is suitable so long as the cations stay bound/associated with the platelet particles throughout processing, incorporation, and use. Specifically, each moisture/oxygen scavenging cation(s) may be attached or associated as a separate cation or may be attached/associated with one or more exfoliating organic cations.

Although the single component according to the invention for providing both physical and chemical obstacles for moisture and/or oxygen transmission has been described as including a scavenging organic cation attached to/associated with organoclay platelet particles, the attachment/association of the scavenging organic cation to other physical moisture/oxygen barrier materials is additionally contemplated herein. Thus, in some embodiments, the scavenging organic cation can be attached to/associated with a moisture vapor and/or oxygen barrier substrate-like material including, but not limited to, exfoliated graphite; compressed exfoliated graphite; flaked and/or exfoliated mica; flaked metals and/or metal oxides/hydroxides such as aluminum, aluminofluorosilicates, iron oxides, and the like; hybrid materials such as glass ionomers, ormocers, and the like; polysulfides and/or copolymers thereof, poly(vinyl halide)s such as poly(vinyl chloride), poly(vinyl fluoride), and the like, and copolymers thereof; poly(vinylidene halide)s such as poly(vinylidene chloride)s, poly(vinylidene fluoride)s, and the like, and copolymers thereof; nanostructured colloidal silicas; and the like; and combinations thereof. Additionally or alternately, examples of physical barrier materials can be found in commonly-assigned patents, publications, and applications, such as in U.S. Pat. Nos. 6,632,147, 6,786,838, 6,793,592, 6,802,784, 6,838,028, 6,919,395, and 6,932,720.

In one embodiment, the moisture vapor transmission rate of the at least one layer is less than that of SURLYN® ionomers, commercially available from DuPont. SURLYN® ionomers can have moisture vapor transmission rates in the range from about 0.45 to about 0.9 g·mm/m²·day. In another embodiment, the moisture vapor transmission rate of the at least one layer is less than about 1 gram·mm/m²·day, preferably less than about 0.6 g·mm/m²·day, for example less than about 0.4 g·mm/m²·day. In another embodiment, the moisture vapor transmission rate of the at least one layer is from about 0.001 to about 0.100 g·mm/m²·day.

Antioxidants and/or desiccants may be used with this invention to control scavenging initiation. Typically, antioxidants and/or desiccants can be added to facilitate the processing of polymeric materials (such as those used in golf ball layers) and/or to prolong their useful lifetime. In relation to this invention, such additives can prolong the induction period for moisture/oxygen scavenging.

Examples of antioxidants can include, but are not limited to, 2,6-di-(t-butyl)-4-methylphenol, 2,2′-methylene-bis(6-t-butyl-p-cresol), triphenylphosphite, tris-(nonylphenyl)phosphate, dilaurylthiodipropionate, pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), those compounds commercially available from Ciba Chemicals under the tradenames IRGANOX® and/or TINUVIN®, and the like, and combinations thereof.

Examples of desiccants can include, but are not limited to, calcium chloride, carbonate salts of calcium and/or sodium, bicarbonate salts of sodium and/or potassium, diphosphorus pentoxide, magnesium sulfate, magnesium chloride, barium sulfate, silica gel, poly(vinyl alcohol), and the like, and combinations thereof.

The core layer(s) of the golf ball according to the invention may comprise thermosetting or thermoplastic materials such as polyurethane, polyurea, partially or fully neutralized ionomers, thermosetting polydiene rubber such as polybutadiene, polyisoprene, ethylene propylene diene monomer rubber, ethylene propylene rubber, natural rubber, balata, butyl rubber, halobutyl rubber, styrene butadiene rubber, or any styrenic block copolymer such as styrene ethylene butadiene styrene rubber, etc., metallocene or other single site catalyzed polyolefin, polyurethane copolymers, e.g. with silicone, and the like, and combinations, blends, and/or copolymers thereof.

In addition to the materials discussed above, compositions within the scope of the present invention can incorporate one or more polymers. Examples of suitable additional polymers for use in the present invention include, but are not limited to, the following: thermoplastic elastomer, thermoset elastomer, synthetic rubber, thermoplastic vulcanizate, copolymeric ionomer, terpolymeric ionomer, polycarbonate, polyolefin, polyamide, copolymeric polyamide, polyesters, polyvinyl alcohols, acrylonitrile-butadiene-styrene copolymers, polyarylate, polyacrylate, polyphenylene ether, impact-modified polyphenylene ether, high impact polystyrene, diallyl phthalate polymer, metallocene catalyzed polymers, styrene-acrylonitrile (SAN) copolymers (including olefin-modified SAN and acrylonitrile-styrene-acrylonitrile), styrene-maleic anhydride (S/MA) polymer, styrenic copolymer, functionalized styrenic copolymer, functionalized styrenic terpolymer, styrenic terpolymer, cellulose polymer, liquid crystal polymer (LCP), ethylene-propylene-diene terpolymer (EPDM), ethylene-vinyl acetate copolymers (EVA), ethylene-propylene copolymer, ethylene vinyl acetate, polyurea, and polysiloxane or any metallocene-catalyzed polymers of these species. Suitable polyamides for use as an additional material in compositions within the scope of the present invention also include resins obtained by: (1) polycondensation of (a) a dicarboxylic acid such as oxalic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid or 1,4-cyclohexane-dicarboxylic acid, with (b) a diamine such as ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine or decamethylenediamine, 1,4-cyclohexyldiamine, or m-xylylenediamine; (2) a ring-opening polymerization of cyclic lactam such as F-caprolactam or ω-laurolactam; (3) polycondensation of an aminocarboxylic acid such as 6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, or 12-aminododecanoic acid; or (4) copolymerization of a cyclic lactam with a dicarboxylic acid and a diamine. Specific examples of suitable polyamides include, but are not limited to, Nylon 6, Nylon 6,6, Nylon 6,10, Nylon 11, Nylon 12, copolymerized Nylons, Nylon MXD6, and Nylon 4,6.

Other preferred materials suitable for use as an additional material in compositions within the scope of the present invention include polyester elastomers marketed under the tradename SKYPEL® by SK Chemicals of South Korea, or diblock or triblock copolymers marketed under the tradename SEPTON® by Kuraray Corporation of Kurashiki, Japan, and KRATON® by Kraton Polymers Group of Companies of Chester, United Kingdom. All of the materials listed above can provide for particular enhancements to ball layers prepared within the scope of the present invention.

Materials for solid cores typically include compositions having a base rubber, a filler, an initiator agent, and a crosslinking agent. The base rubber typically includes natural or synthetic rubber, such as polybutadiene rubber. A preferred base rubber is 1,4-polybutadiene having a cis-structure of at least 40%. Most preferably, however, the solid core is formed of a resilient rubber-based component comprising a high-Mooney-viscosity rubber and a crosslinking agent.

Another suitable rubber from which to form cores of the present invention is trans-polybutadiene. This polybutadiene isomer is formed by converting the cis-isomer of the polybutadiene to the trans-isomer during a molding cycle. Various combinations of polymers, cis-to-trans catalysts, fillers, crosslinkers, and a source of free radicals, may be used. A variety of methods and materials for performing the cis-to-trans conversion have been disclosed in U.S. Pat. Nos. 6,162,135; 6,465,578; 6,291,592; and 6,458,895, each of which are incorporated herein, in their entirety, by reference.

Additionally, without wishing to be bound by any particular theory, it is believed that a low amount of 1,2-polybutadiene isomer (“vinyl-polybutadiene”) is preferable in the initial polybutadiene to be converted to the trans-isomer. Typically, the vinyl polybutadiene isomer content is less than about 7%, more preferably less than about 4%, and most preferably, less than about 2%.

Fillers added to one or more portions of the golf ball typically include processing aids or compounds to affect rheological and mixing properties, the specific gravity (i.e., density-modifying fillers), the modulus, the tear strength, reinforcement, and the like. The fillers are generally inorganic, and suitable fillers include numerous metals or metal oxides, such as zinc oxide and tin oxide, as well as barium sulfate, zinc sulfate, calcium carbonate, barium carbonate, clay, tungsten, tungsten carbide, an array of silicas, and mixtures thereof. Fillers may also include various foaming agents or blowing agents, zinc carbonate, regrind (recycled core material typically ground to about 30 mesh or less particle size), high-Mooney-viscosity rubber regrind, and the like. Polymeric, ceramic, metal, and glass microspheres may be solid or hollow, and filled or unfilled. Fillers are typically also added to one or more portions of the golf ball to modify the density thereof to conform to uniform golf ball standards. Fillers may also be used to modify the weight of the center or any or all core and/or cover layers, if present.

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

Crosslinkers can advantageously be included to increase the hardness and resilience of the reaction product. 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 about 3 to about 8 carbon atoms such as acrylic and/or methacrylic acid. Suitable crosslinking agents include metal salt diacrylates, dimethacrylates, and monomethacrylates, in which the metal is magnesium, calcium, zinc, aluminum, sodium, lithium, or nickel. Preferred acrylates include zinc acrylate, zinc diacrylate, zinc methacrylate, zinc dimethacrylate, and mixtures thereof.

The crosslinking agent must be present in an amount sufficient to crosslink a portion of the chains of polymers in the resilient polymer component. This may be achieved, for example, by altering the type and amount of crosslinking agent, a method well-known to those of ordinary skill in the art.

In another embodiment of the present invention, the core comprises a solid center and at least one outer core layer. When the optional outer core layer is present, the center preferably comprises a high-Mooney-viscosity rubber and a crosslinking agent present in an amount from about 10 to about 30 parts per hundred (“pph”) of the rubber, preferably from about 19 to about 25 pph of the rubber, and most preferably from about 20 to about 24 pph crosslinking agent per hundred of rubber.

The core composition should comprise at least one rubber material having a resilience index of at least about 40. Preferably, the resilience index is at least about 50. Polymers that produce resilient golf balls and, therefore, are suitable for the present invention, include but are not limited to CB23, CB22, BR60, and 1207G.

Additionally, the unvulcanized rubber, such as polybutadiene, in golf balls prepared according to the invention typically has a Mooney viscosity of between about 40 and about 80, more preferably, between about 45 and about 60, and most preferably, between about 45 and about 55. Mooney viscosity is typically measured according to ASTM D-1646.

The polymers, free-radical initiators, filler, crosslinking agents, and any other materials used in forming either the golf ball center or any portion of the core, in accordance with invention, may be combined to form a mixture by any type of mixing known to one of ordinary skill in the art. Suitable types of mixing include single pass and multi-pass mixing, and the like. The crosslinking agent, and any other optional additives used to modify the characteristics of the golf ball center or additional layer(s), may similarly be combined by any type of mixing. A single-pass mixing process where ingredients are added sequentially is preferred, as this type of mixing tends to increase efficiency and reduce costs for the process. The preferred mixing cycle is single step wherein the polymer, cis-to-trans catalyst, filler, zinc diacrylate, and peroxide are added sequentially.

Suitable mixing equipment is well known to those of ordinary skill in the art, and such equipment may include a Banbury mixer, a two-roll mill, or a twin screw extruder. Conventional mixing speeds for combining polymers are typically used, although the speed must be high enough to impart substantially uniform dispersion of the constituents. On the other hand, the speed should not be too high, as high mixing speeds tend to break down the polymers being mixed and particularly may undesirably decrease the molecular weight of the resilient polymer component. The speed should thus be low enough to avoid high shear, which may result in loss of desirably high molecular weight portions of the polymer component. Also, too high a mixing speed may undesirably result in creation of enough heat to initiate the crosslinking before the preforms are shaped and assembled around a core. The mixing temperature depends upon the type of polymer components, and more importantly, on the type of free-radical initiator. Additionally, it is important to maintain a mixing temperature below the peroxide decomposition temperature. Suitable mixing speeds and temperatures are well-known to those of ordinary skill in the art, or may be readily determined without undue experimentation.

The mixture can be subjected to compression or injection molding processes, for example, to obtain solid spheres for the core or hemispherical shells for forming an intermediate layer, such as an outer core layer or an inner cover layer. The polymer mixture is subjected to a molding cycle in which heat and pressure are applied while the mixture is confined within a mold. The cavity shape depends on the portion of the golf ball being formed. The molding cycle may have a single step of molding the mixture at a single temperature for a fixed time duration. The molding cycle may also include a two-step process, in which the polymer mixture is held in the mold at an initial temperature for an initial duration of time, followed by holding at a second, typically higher temperature for a second duration of time. In a preferred embodiment, a single-step cure cycle is employed. Single-step processes are effective and efficient, reducing the time and cost of a two-step process.

Further, the core and layers of the present invention may be reaction injection molded (“RIM”), liquid injection molded, or injection molded. In the RIM process, at least two or more reactive low viscosity liquid components are mixed by impingement and injected under high pressure (1200 psi or higher) into an open or closed mold. The reaction times for the RIM systems are much faster than the low pressure mixing and metered machines and, consequently, the raw materials used for the RIM process are generally much lower in viscosity to allow intimate mixing. A RIM machine can process fast reacting materials having viscosities up to about 2,000 cP and a pot life of less than about 5 seconds. Because low viscosity materials are used in the RIM process, the components are capable of being mixed by impingement in less than a second before injecting the mixed material into the closed mold at about 2,000 to about 2,500 psi. With a conventional castable urethane process, materials having viscosities greater than about 3,500 are required and also require a pot life of greater than about 35 seconds.

The polybutadiene, cis-to-trans conversion catalyst, if present, additional polymers, free-radical initiator, filler, and any other materials used in forming any portion of the golf ball core, in accordance with the invention, may be combined to form a golf ball layer by an injection molding process, which is also well-known to one of ordinary skill in the art. Although the curing time depends on the various materials selected, those of ordinary skill in the art will be readily able to adjust the curing time upward or downward based on the particular materials used and the discussion herein.

The golf ball according to the invention typically has at least two cover layers, thus including at least an inner/innermost cover layer and an outer/outermost cover layer. In these golf balls, the inner/innermost cover layer can include one or more polymeric 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 terephthalate), and elastomers sold under the trademarks HYTREL® by E.I. DuPont de Nemours & Co. of Wilmington, Del., and LOMOD® by General Electric Company;
  • (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.

In one embodiment, the inner/innermost cover layer includes polymers such as ethylene, propylene, 1-butene or 1-hexane 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 and copolymers thereof. Suitable cover compositions can additionally or alternately include a polyether or polyester thermoplastic urethane, a thermoset polyurethane, a low modulus ionomer such as an acid-containing ethylene copolymer ionomer, including E/X/Y terpolymers where E is ethylene, X is an acrylate and/or methacrylate-based softening comonomer present in about 0 to 50 weight percent, and Y is acrylic and/or methacrylic acid present in about 5 to 35 weight percent. In a low spin rate embodiment designed for maximum distance, the acrylic and/or methacrylic acid can preferably be present in about 16 to 35 weight percent, making the ionomer a high modulus ionomer. In a higher spin embodiment, the inner cover layer can advantageously include an ionomer where an acid is present in about 10 to 15 weight percent and includes a softening comonomer. Additionally, high-density polyethylene, low-density polyethylene, LLDPE, and polyolefin polymers are suitable for a variety of golf ball layers.

Any cover layer, but preferably the outer/outermost cover layer, may include 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; p-phenylene diisocyanate (“PPDI”); toluene diisocyanate (“TDI”); 3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate; naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylene diisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; 1,6-hexamethylene-diisocyanate; 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; tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; and mixtures thereof.

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.

In a preferred embodiment, 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, 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. 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-chloroaaniline); 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline); polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenyl methane; p,p′-methylene dianiline; m-phenylenediamine; 4,4′-methylene-bis-(2-chloroaniline); 4,4′-methylene-bis-(2,6-diethylaniline); 4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane; 2,2′, 3,3′-tetrachloro diamino diphenylmethane; 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline); trimethylene glycol di-p-aminobenzoate; and mixtures thereof. Preferably, the curing agent 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 can include, but are not limited to, 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 ethylene glycol; diethylene glycol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol, trimethylol propane, and mixtures thereof. Preferably, the hydroxy-terminated curatives have molecular weights ranging from about 48 to about 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-terrninated 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.

It should also be understood that slow-reacting amine curatives, such as VERSALINK® P-250, VERSALINK® P-650, and POLAMINE®, and fast-reacting curatives, such as ETHACURE 100® and ETHACURE 300®, may be used individually or as mixtures. Further, blending of these curatives, and/or varying the mixing temperature and speed, for example, can adjust the cure rate as desired. Light stable polyurethanes, such as those disclosed in U.S. Pat. No. 6,506,851 which is incorporated herein in its entirety by express reference hereto.

Any method known to one of ordinary skill in the art may be used to combine the polyisocyanate, polyol, and curing agent. 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 can be inhomogenous (more random) and can afford 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 can afford a more homogeneous mixture resulting in a more consistent polymer composition.

Optionally, in addition to the cover and core layers, the golf ball according to the invention can contain one or more barrier layers. The one or more barrier layers, when present, can advantageously prevent or minimize the penetration of moisture, typically water vapor, into the core layer(s) of the golf ball. In one embodiment, the one or more barrier layers is/are a moisture vapor barrier, preferably disposed immediately around the core layer(s) of the golf ball. Also when present, the moisture vapor barrier layer(s) preferably has(have) a moisture vapor transmission rate that is lower than that of the cover layer(s), and also preferably less than the moisture vapor transmission rate of an ionomer resin such as SURLYN®, which is in the range of about 0.45 to about 0.95 g·mm/m²·day (i.e., such as less than 0.4 g·mm/m²·day). The moisture vapor transmission rate is defined as the mass of moisture vapor that diffuses into a material of a given thickness per unit area per unit time. The preferred standards of measuring the moisture vapor transmission rate include ASTM F1249-90 and ASTM F372-99, among others.

In some embodiments, the one or more barrier layers can include a multi-layer thermoplastic film, a blend comprising ionomers, polyvinyl alcohol copolymer and polyamides, or a dispersion of acid salts of polyetheramines. Additionally or alternately, the one or more barrier layers can include nano-particles, flaked metals such as mica, iron oxide, and aluminum, or ceramic particles disposed in the film to resist the transmission of moisture.

Additionally or alternately, the one or more barrier layers can be made from extremely thin layer of compressed exfoliated graphite having a thickness from about 0.1 μm to about 600 μm. Compressed exfoliated graphite has been shown to be impermeable to helium at a pressure of 10⁻⁵ mm Hg, which essentially is a vacuum. Compressed exfoliated graphite layers are disclosed in commonly-assigned U.S. Pat. No. 6,802,784, the entire disclosure of which is hereby incorporated by reference in its entirety.

Any of the core, barrier, or cover layers, as well as any other portions of the golf balls according to the invention, may be formed from or include a hybrid material. Components include golf ball centers, cores, layers, covers, and coating materials and/or blends. The hybrid materials include, but are not limited to, glass ionomers, ormocers, and other inorganic-organic materials. Ormocers are composite materials formed of ceramic and polymer networks that combine and interpenetrate with one another. Ormocers may be generally classified as one, either organic- or inorganic-doped systems typically based on one major phase containing a second one in a relatively low amount; and two, either organic- or inorganic-doped systems in which the fraction of each component in the system is of the same order of magnitude. The different organic-inorganic hybrids can be further classified into two broad families: one, where one of the hybrid components can be molecules, oligomers, polymers entrapped within a network of the other component (where weak interactions between the hosting “network” and the entrapped species, such as hydrogen-bonding, electrostatic, or van der Waals forces, predominate); and two, wherein the organic-inorganic parts are chemically bonded by covalent or ionic bonds. Preferably, when hybrid materials are present, the golf ball components comprise this second class of hybrid materials.

The hybrid materials may be described by a number of lexicons including, but not limited to, glass ionomers, resin-modified glass ionomers, fatty acid-modified glass ionomers, silicon ionomers, dental cements or restorative compositions, polymerizable cements, metal-oxide polymer composites, and ionomer cements. One advantage of these materials is their ability to cure in the presence of moisture and their moisture resistance in the cured state. Additionally, blends of these materials, including blends of polyolefinic ionomers (undried) and glass ionomers offer desirable characteristics for the golf ball components, such as toughness, stiffness, and high density.

Compositions comprising a liquid material and a powder material, wherein the liquid material comprises 4-methacryloxyethyl trimellitic acid and water and the powder material comprises a powdered fluoroaluminosilicate glass or a powdered metal oxide containing zinc oxide as the major component are also suitable. Other suitable materials include aluminofluorosilicate glasses having the following features: a) a ratio of Al (calculated as Al₂O₃) to Si (calculated as SiO₂) of 0.57-1.12 by mass; b) a total content of Mg (calculated as MgO) and Ba (calculated as BaO) of 29-36% by mass; c) a ratio of Mg (calculated as MgO) to Ba (calculated as BaO) of 0.028-0.32 by mass; and d) a content of P (calculated as P₂0₅) of 2-10% by mass. The glass can have a high radioopacity, and the refractive index, n_D, for visible light can be adjusted by varying the phosphorus content.

Fluoroaluminosilicate glass powders having a specific gravity of 2.4 to about 4.0, a mean particle size of 0.02 to about 4 μm, and a BET specific surface area of 2.5 to about 6.0 m²/g are also suitable. When utilized, they preferably have a maximum particle size of less than 4 μm and contain 10 to about 21% by weight of Al³⁺, about 21% by weight of Si⁴⁺, about 20% by weight of F⁻, and about 34% by weight in total of Sr²⁺ and/or Ca²⁺ in its components.

Glass powders for glass ionomer cements are also suitable hybrid materials. These powders have a shape in which a major axis length is from about 3 to about 1,000 times a minor axis length, in a glass powder for glass ionomer cement. The glass powder for glass ionomer cement having a shape in which a major axis length is from about 3 to about 1,000 times a minor axis length can be a fibrous glass having a minor axis length of from 0.1 to 100 μm and a major axis length of 500 μm or less, and its content within a layer typically ranges from about 0.1% to about 80% by weight.

Other acceptable hybrid materials include a polymerizable composition comprising a polymerizable resin composition; and a filler composition comprising a bound, nanostructured colloidal silica. These composites can comprise a resin composition and a filler composition, in which the filler composition comprises a nanostructured, bound silica, preferably in the form of nanosized particles having their largest dimensions in the range from about 10 nm to about 50 nm. Silica particles are preferably bound so as to result in chains lengths from about 50 nm to about 400 nm. Resin compositions are well known in the art, generally comprising viscous acrylate or methacrylate monomers.

When present, ideal hybrid materials are comprised of about 22% by weight alumina, about 78% by weight silica, about 2% by weight silicon carbide, and about 2.85% by weight boron nitride with less than 1% cristobalite contamination. One preferred embodiment is comprised of a binder and a filler wherein said filler is comprised of about 1% to about 50% by weight alumina, from about 50% by weight to about 98% by weight silica, and boron. Another preferred embodiment is comprised of: (1) from about 15% to about 30% by weight alumina fiber; (2) from about 65% to about 85% by weight silica fiber; (3) from about 1% to about 3% by weight silicon carbide; and (4) from about 1% to about 5% by weight boron nitride. Another more preferred fused-fibrous composition for the filler is as follows: (1) about 21% by weight alumina fiber; (2) about 74% by weight silica fiber; (3) about 2% by weight silicon carbide; and (4) about 2.85% by weight boron nitride. Preferably, the hybrid materials are comprised of alumina and silica fibers in a ratio of 22:78.

Flexible composite hybrid compositions can include (a) about 2 to 15 weight percent of a flexible monomer portion comprising one or more flexible co-monomers of the general formula R¹—O—[(CH—R²)_n—O—]—R³, where R¹ and R³ are acrylate or methacrylate functional groups, where R² is selected from the group of hydrogen, methyl and ethyl, where n is from 3 to 5 and z is from about 3 to about 20, and where the monomers have average molecular weights from at least about 300 or higher, (b) about 30 to about 80 weight percent of a filler portion, (c) about 18 to 60 weight percent of a comonomer portion comprising one or more co-monomers capable of polymerizing with the flexible monomer portion, and (d) a polymerization catalyst system for polymerizing and hardening the composition.

Suitable glass ionomer cements are generally comprised of a powder component containing aluminosilicate and a liquid portion. Often the liquid portion is expressed as containing polyacrylic acid, polymaleic acid, polyitaconic acid, or a copolymer of at least two of the acids. The liquid portion may also comprise carboxylate polymers or carboxylic acid polymeric structures, such as those including acrylic acid, maleic acid, crotonic acid, isocrotonic acid, methacrylic acid, sorbic acid, cinnamic acid, fumaric acids, and the like. In most glass ionomer cements, the primary reactions causing the glass ionomer cement to harden are crosslinking, i.e., the crosslinking of polycarboxylate chains by metal ions from the glass. Also, during setting, the acids of the glass ionomer cement dissolve the glass structure to release metal constituents of the glass. Metal carboxylates are formed during the setting process and may be distinguished from the primary acrylic cement setting reactions that are other forms of polymerization reactions. Though other forms of polymerization reactions may occur in glass ionomer cements, these reactions are generally secondary.

Glass-ionomer cements are acid-base reaction cements that typically set by the interaction of an aqueous solution of a polymeric acid with an acid-degradable glass. The principal setting reaction is the slow neutralization of the acidic polymer solution to form a polysalt matrix. The acid is typically a polycarboxylic acid (often polyacrylic acid) and the glass is typically a fluoroaluminosilicate. The setting reaction typically begins as soon as the components are mixed, and the set material tends to have residual glass particles embedded in interconnected polysalt and silica matrices. Resin-modified glass-ionomer cements were introduced with the intention of overcoming the problems associated with the conventional glass-ionomer, e.g., uncontrolled chemical set and tendency towards brittle fracture, whilst still retaining its advantages, e.g., fluoride release and adhesion. One attempt to achieve this advocated simply replacing some of the water in a conventional glass-ionomer cement with a hydrophilic monomer. Another approach also replaced some of the water in the formulation, but in addition modified the polymeric acid so that some of the acid groups were replaced with unsaturated species, so that the polymeric acid could also take part in the polymerization reaction.

Resin-modified glass-ionomers can have two setting reactions: the acid-base reaction of the glass-ionomer; and the polymerization of the composite resin. The monomer systems used in resin-modified glass-ionomers are not generally the same as those in composite resins. This is because the monomer must be compatible with the aqueous acid-base reaction of the glass-monomer components.

In one embodiment, the water vapor barrier layer(s) contain polysulfide rubber. Polysulfide rubber typically has a high sulfur content, which makes the material resistant to hydrocarbons, gasoline, diluted acids, alkaline, water, alcohol, acetone, esters, among other things. Polysulfide is also highly resistant to diffusion of gases. According to one estimate, polysulfide is 40 times less permeable to vapor than natural rubber. The water vapor transmission rate for polysulfide is typically in the range of about 0.01 g·mm/m²·day to about 0.50 g·mm/m²·day. The water vapor transmission rate depends on the particular composition of the polysulfide compound, including functionality, molecular weight, curatives, and fillers, among other things. For example, an isocyanate-functionalized polysulfide generally has higher water vapor transmission rate and a relatively purer, high molecular weight polysulfide generally has lower water vapor transmission rate.

A variety of conventional components can be added to the different layer compositions of the present invention. These can include, but are not limited to, white pigments such as TiO₂, ZnO, optical brighteners, surfactants, processing aids, foaming agents, density-controlling fillers, UV absorbers/stabilizers, and light stabilizers. Suitable UV absorbers and light stabilizers can include, but are not limited to, TINUVIN® 328, TINUVIN® 213, TINUVIN® 765, TINUVIN® 770, and TINUVIN® 622. A preferred UV absorber is TINUVIN® 328, and a preferred light stabilizer is TINUVIN® 765. TINUVIN® products are commercially available from Ciba-Geigy. Dyes, as well as optical brighteners and fluorescent pigments may also be included in the golf ball cover layers according to the present invention. Such additional ingredients may be added in any amounts that will achieve their desired purpose.

Depending on the desired properties, balls prepared according to the invention can exhibit substantially the same or higher resilience, or coefficient of restitution (“COR”), with a decrease in compression or modulus, compared to balls of conventional construction. Additionally, balls prepared according to the invention can also exhibit substantially higher resilience, or COR, without an increase in compression, compared to balls of conventional construction. Another measure of this resilience is the “loss tangent,” or tan δ, which is obtained when measuring the dynamic stiffness of an object. Loss tangent and terminology relating to such dynamic properties is typically described according to ASTM D4092-90. Thus, a lower loss tangent indicates a higher resiliency, thereby indicating a higher rebound capacity. Low loss tangent indicates that most of the energy imparted to a golf ball from the club is converted to dynamic energy, i.e., launch velocity and resulting longer distance. The rigidity or compressive stiffness of a golf ball may be measured, for example, by the dynamic stiffness. A higher dynamic stiffness indicates a higher compressive stiffness. To produce golf balls having a desirable compressive stiffness, the dynamic stiffness of the layers should be less than about 50,000 N/m at about −50° C.; preferably, the dynamic stiffness should be between about 10,000 and 40,000 N/m at about −50° C.; more preferably, the dynamic stiffness should be between about 20,000 and about 30,000 N/m at about −50° C.

The resultant golf balls typically have a COR of greater than about 0.75, preferably greater than about 0.8, and more preferably greater than about 0.81. The golf balls also typically have an Atti compression of at least about 40, preferably from about 50 to 120, and more preferably from about 60 to 100.

When golf balls are prepared according to the invention, they typically will have dimple coverage greater than about 60 percent, preferably greater than about 65 percent, and more preferably greater than about 75 percent. The flexural modulus of the cover on the golf balls, as measured by ASTM method D6272-98, Procedure B, is typically greater than about 500 psi, and is preferably from about 500 psi to 150,000 psi. In one embodiment, the material of the outer cover layer has a material hardness of less than about 45 Shore D, preferably less than about 40 Shore D, more preferably between about 25 and about 40 Shore D, and most preferably between about 30 and about 40 Shore D.

The golf ball layers, according to the invention, can generally exhibit a flexural modulus from about 10,000 psi to about 100,000 psi, preferably from about 20,000 psi to about 75,000 psi, or also preferably from about 25,000 psi to about 65,000 psi. Additionally or alternately, the core layers, collectively and/or individually, can exhibit a flexural modulus from about 20,000 psi to about 35,000 psi and/or a hardness from about 45 to about 55 Shore D. Additionally or alternately, the cover layers, collectively and/or individually, can advantageously exhibit a flexural modulus from about 50,000 psi to about 80,000 psi.

Hardness is preferably measured pursuant to ASTM D-2240 in either button or slab form on the Shore D scale. More specifically, Shore D scale measures the indentation hardness of a polymer. The higher Shore D value indicates higher hardness of the polymer. Compression is measured by applying a spring-loaded force to the golf ball center, golf ball core or the golf ball to be examined, with a manual instrument (an “Atti gauge”) manufactured by the Atti Engineering Company of Union City, N.J. This machine, equipped with a Federal Dial Gauge, Model D81-C, employs a calibrated spring under a known load. The sphere to be tested is forced a distance of 0.2 inches (5 mm) against this spring. If the spring, in turn, compresses 0.2 inches, the compression is rated at 100; if the spring compresses 0.1 inches, the compression value is rated as 0. Thus softer, more compressible materials will have lower Atti gauge values than harder, less compressible materials. The approximate relationship that exists between Atti compression and Riehle compression can be expressed as: Atti compression=(160−Riehle Compression).

The present golf ball can have an overall diameter of any size. Preferably, the diameter of the present golf balls is from about 1.680 inches to about 1.800 inches, more preferably the diameter is about 1.680 inches. The cover thickness (single or multi-layer) is preferably 0.01 inches to 0.05 inches, more preferably 0.02 to 0.04 inches, most preferably 0.03 to 0.035 inches. The moisture barrier intermediate layer of the present invention preferably has a thickness of 0.005 inches to 0.030 inches, more preferably 0.01 inches to 0.025 inches. The outer core layer, if present, should have a thickness of 0.05 inches to 0.15 inches. Preferably, the core (single or dual core) has a thickness of 1.5 inches to 1.62 inches, more preferably 1.55 inches to 1.6 inches.

Unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages, such as those for amounts of materials and others in the specification, may be read as if prefaced by the word “about”, even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth herein are reported as precisely as possible. Any numerical value, however, may inherently contain certain errors resulting from the standard deviation found in measurements obtained from their respective testing methods. Furthermore, where numerical ranges of varying scope are set forth herein, it is contemplated that any combination of the values that is inclusive of the recited values may be used.

While the illustrative embodiments of the invention disclosed herein can fulfill any objectives stated above, it should be appreciated by those of skill in the art that numerous modifications and other embodiments may be devised. Therefore, it should be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.

Claims

1. A golf ball comprising:

a core having an outer diameter of about 1.50 inches to about 1.62 inches;

a cover comprising polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, or a combination thereof; and

an intermediate layer disposed between the core and the cover, the intermediate layer having a thickness of about 0.005 inches to about 0.030 inches and comprising a matrix polymer and a barrier component comprising a physical barrier to moisture transmission and a chemical barrier to moisture transmission.

2. The golf ball of claim 1, wherein the intermediate layer has a moisture vapor transmission rate that is lower than that of the cover.

3. The golf ball of claim 1, wherein the matrix polymer comprises polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, ionomers, polyethylene acrylic or methacrylic acid copolymers, or a combination thereof.

4. The golf ball of claim 1, wherein the core comprises a center and an outer core layer.

5. The golf ball of claim 4, wherein the outer core layer has a thickness of about 0.05 inches to about 0.15 inches.

6. The golf ball of claim 1, wherein the intermediate layer has a thickness of about 0.010 inches to about 0.025 inches.

7. The golf ball of claim 1, wherein the cover has a thickness of about 0.010 inches to about 0.050 inches.

8. The golf ball of claim 1, wherein the barrier component comprises an intercalated organoclay chemically-modified with an ammonium compound, a phosphonium compound, a sulfonium compound, or a combination thereof to provide the chemical barrier to moisture transmission.

10. The golf ball of claim 1, wherein the barrier component comprises a compound having the formula:

where M comprises nitrogen, phosphorous, or sulfur;

where X− comprises an anionic counterion; and

where R1, R2, R3, and R4 comprise hydrogen, an organic moiety, or an oligomeric organic moiety.

11. The golf ball of claim 1, wherein the intermediate layer has a moisture vapor transmission rate of less than about 0.4 g·mm/m2·day.

12. A golf ball comprising:

a core;

a cover; and

an intermediate layer disposed between the core and the cover, the intermediate layer having a thickness of about 0.005 inches to about 0.030 inches and being formed from a matrix polymer and a barrier component, the barrier component comprising a physical barrier to moisture transmission, and being chemically-modified with an ammonium compound, a phosphonium compound, a sulfonium compound, or a combination thereof to provide a chemical barrier to moisture transmission.

13. A golf ball comprising:

a core having an outer diameter of about 1.50 inches to about 1.62 inches, the core comprising a center and an outer core layer;

a cover comprising polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, or a combination thereof; and

an intermediate layer having a thickness of about 0.005 inches to about 0.030 inches disposed between the core and the cover, the intermediate layer comprising: a matrix polymer selected from the group consisting of polyurethanes, polyureas, polyurea-urethanes, polyurethane-ureas, and ionomers; and a barrier component comprising a physical barrier to moisture transmission and a chemical barrier to moisture transmission, wherein the barrier component comprises a compound having the formula:

where M comprises nitrogen, phosphorous, or sulfur;

where X− comprises an anionic counterion; and

where R1, R2, R3, and R4 comprise hydrogen, an organic moiety, or an oligomeric organic moiety.