Golf Ball Core Compositions with Metamaterial

The present disclosure relates generally to compositions for use in golf balls that produce highly resilient golf balls. More particularly, the present disclosure provides compositions and golf ball components made from such compositions that provide the ability to tailor and/or improve certain ball performance characteristics when such components are used in a golf ball. In some respects, the present disclosure relates to golf ball components with increased resiliency and rebounding that, when used in golf balls, provide the ability to achieve one or more desired performance characteristics including, for example, increased distance on driver and iron shots.

The flight performance of a golf ball is affected by a variety of factors including the materials, weight, size, dimple pattern, and external shape of the golf ball. As a result, golf ball manufacturers are constantly improving or tweaking the performance of golf balls by adjusting the materials and construction of the ball as well as the dimple pattern and dimple shape.

For example, the resiliency and rebounding performance of a golf ball are generally driven by the composition and construction of the core and cover, among other components. The coefficient of restitution (CoR) is a direct measure of the resilience of a golf ball at a particular inbound velocity. A golf ball's CoR is the ratio of the relative velocity of the ball after direct impact to that before impact. One way to measure the CoR is to propel a ball at a given speed against a hard ungiving surface and measure its incoming velocity and outgoing velocity. The CoR is defined as the ratio of the outgoing velocity to the incoming velocity of a rebounding ball and is expressed as a decimal. The CoR can vary from zero to one, with one being equivalent to an elastic collision and zero being equivalent to an inelastic collision. A golf ball with a high CoR value will generally have an increased initial velocity and increased distance on a given shot compared to a golf ball with a low CoR value. A golf ball with a high CoR value may be particularly desirable for less skilled or weaker players, such as recreational players, children, seniors, or disabled players.

Recently, there has been an increased desire to manipulate golf ball cores to produce reduced-flight golf balls (i.e., golf balls that are designed to travel a distance that is shorter than the distance traveled by standard golf balls). Advances in golf ball compositions and dimple designs have caused high-performance golf balls to exceed the maximum distance allowed by the United States Golf Association (USGA). Some industry experts have called for the USGA to roll back the distance standard for golf balls to preserve the game. Thus, it is desirable in some cases to produce a golf ball core with a lower CoR value.

Golf ball resilience is also constrained by the compositions used to form various golf ball components. In particular, golf ball resilience may also be influenced by the ambient environmental conditions during manufacturing and storage. As a result, golf ball manufacturers are constantly monitoring manufacturing conditions and adjusting the compositions of golf ball components to maintain the targeted properties of golf balls, such as the CoR.

Accordingly, there remains a need in the art for compositions that allow formation of golf ball components that can be tailored to produce a finished golf ball having a desired and/or targeted CoR. Particularly, there is a need for compositions and golf ball components made from such compositions that can be tailored to have a desired and/or targeted CoR. In this respect, it would be advantageous to provide a composition for use in golf ball components such that the finished golf ball has the desired CoR for players having different levels of expertise as well as other advantageous properties, features, and benefits. For example, it would be beneficial to tailor the composition used to form a core and/or a cover of a golf ball to increase shot distance for amateur, young, senior, or disabled players. In other cases, it would be advantageous to tailor the composition used to form one or more components of a golf ball such that the finished golf ball has a decreased shot distance to comply with USGA regulations or to preserve the nature of the game. In another aspect, there remains a need for golf ball components that can be tailored to minimize the physical property variation, such as variation in the CoR value of a golf ball, associated with prior art compositions and manufacturing methods. The present disclosure provides compositions for use in golf ball components and golf balls containing such components that allow for controlled manipulation of the CoR and other physical properties of a golf ball, and, thus, manipulation or tailoring of desired performance characteristics.

The problems expounded above, as well as others, are addressed by the following inventions, although it is to be understood that not every embodiment of the inventions described herein will address each of the problems described above.

In some embodiments, the present disclosure provides a golf ball including a core and a cover layer disposed about the core, the core including a core composition including a resiliency additive, wherein the resiliency additive is an elasto-magnetic metamaterial. In another embodiment, the resiliency additive includes a polymeric network and plurality of magnets contained in the polymeric network. In yet another embodiment, the polymeric network includes a plurality of plates including the plurality of magnets and a plurality of pores disposed between the plates. In still another embodiment, the polymeric network includes closed and open phases. In a further embodiment, the polymeric network is configured to transition between the open phase and the closed phase when struck by a golf club.

In one embodiment, the plurality of magnets includes a first magnet and a second magnet, and the first magnet and second magnet are configured to attract each other. In another embodiment, the plurality of magnets includes a first magnet and a second magnet, and the first magnet and second magnet are configured to repel each other. In still another embodiment, each magnet in the plurality of magnets includes a magnetic moment having a direction, and the direction of the magnetic moment of each magnet extends substantially parallel to the magnetic moment of each other magnet. In yet another embodiment, the core includes a geometric center, wherein each magnet in the plurality of magnets includes a magnetic moment having a direction, and wherein the direction of the magnetic moment of each magnet is substantially colinear with a line passing through the geometric center of the core. In a further embodiment, the resiliency additive is included in the core composition of the core in an amount of about 1 to about 50 parts per hundred rubber. In some embodiments, the core has a coefficient of restitution between about 0.700 and about 0.950. In other embodiments, the core has a coefficient of restitution between about 0.500 and about 0.700.

In one embodiment, the plurality of magnets includes neodymium magnets. In another embodiment, the cover layer includes a magnetic shielding agent. In yet another embodiment, the rubber formulation further includes a co-agent, a filler, a radical scavenger, an initiator, or a combination thereof. In still another embodiment, the base rubber is polybutadiene rubber, butyl rubber, or a blend thereof. In a further embodiment, the cover layer includes a material selected from the group consisting of polyurethanes, polyureas, and hybrids, copolymers, and blends thereof.

In other embodiments, the present disclosure provides a golf ball including a dual core and a cover layer disposed about the dual core, the dual core including: an inner core layer having a first core composition, wherein the first core composition includes a first polymeric network, and wherein the first polymeric network includes a first plurality of magnets; and an outer core layer disposed over the inner core layer and including a second core composition, wherein the second core composition includes a second polymeric network, and wherein the second polymeric network includes a second plurality of magnets.

In one embodiment, at least one of the magnets in the first plurality of magnets and at least one of the magnets in the second plurality of magnets are configured to attract each other. In another embodiment, at least one of the magnets in the first plurality of magnets and at least one of the magnets in the second plurality of magnets are configured to repel each other. In still another embodiment, the first polymeric network is integrally formed with the second polymeric network. In a further embodiment, the cover layer includes a magnetic shielding agent. In some embodiments, the core has a coefficient of restitution between about 0.700 and about 0.950. In other embodiments, the core has a coefficient of restitution between about 0.500 and about 0.700.

The present disclosure relates to compositions that may be used to produce golf ball components with a desired Coefficient of Restitution (CoR), components including such compositions, and golf balls including such components. In some respects, tailoring the CoR of a golf ball formed in accordance with the present disclosure provides the ability to increase or decrease shot distance and initial velocity when compared to a conventional golf ball hit under the same conditions. In addition, manipulation of the CoR of a golf ball formed in accordance with the present disclosure may be used to minimize disparities in golf ball performance due to variations in physical properties of the golf ball associated with changes in ambient environmental conditions during manufacturing using standard materials and manufacturing techniques.

While golf ball components generally are functionally different from each other and operate somewhat independently, certain components such as the core and cover of a golf ball greatly influence the overall performance of the finished golf ball including such a core or cover. In this regard and without being bound by any particular theory, the performance characteristics of a finished golf ball that contains a core or cover of the present disclosure may be tailored by changing the composition of the core or cover. For example, altering the core or cover composition and, thus, the CoR of a golf ball including such core or cover, may have a significant effect on both long shots, e.g., shots made with a driver, and approach shots, e.g., shots made with irons and wedges. In fact, adjusting the CoR of golf ball cores or covers made in accordance with this present disclosure, even in relatively small amounts, can significantly affect how a golf ball performs on long- and short-distance shots. Similarly, adjusting the CoR of the core or cover may allow for tailoring of other performance characteristics of the finished golf ball. The inventive compositions, cores or covers made using the compositions, golf balls including such cores or covers, and resulting performance characteristics are discussed in greater detail below.

The compositions of the present disclosure may include a resiliency additive. A resiliency additive may be included in the composition of a golf ball component to manipulate the CoR of that particular golf ball component. For example, compositions of the present disclosure including a resiliency additive may be used to form a golf ball core or cover. As discussed in greater detail below, the effect of the resiliency additive on the CoR may depend on the type and structure of the resiliency additive used and the particular components(s) of the golf ball into which the resiliency additive is incorporated. The resiliency additive may take the form of an elasto-magnetic metamaterial including magnets and/or a polymeric network that includes a plurality of magnets embedded therein. In some embodiments, the resiliency additive may include a plurality of magnets embedded directly in the golf ball component. In other embodiments, the resiliency additive takes the form of a plurality of magnets embedded in one or more polymeric networks in the golf ball component.

In either aspect, the magnets of the resiliency additive may have a north pole, a south pole and a magnetic moment (also referred to as a magnetic dipole moment). The magnetic moment is a vector quantity having a direction pointing from the south pole to the north pole of the magnet and strength determined by the physical properties of the magnet (such as the composition and size). Without being bound to any particular theory, the orientation of the magnets and their poles, and the resulting interaction of the magnetic forces between the magnets may affect the CoR of the golf ball, as discussed in greater detail below.

Magnets suitable for use in accordance with the present disclosure may include permanent magnets, temporary magnets, electromagnets, and combinations thereof. A permanent magnet is a material that is magnetized and creates its own persistent magnetic field. Examples of metals and metal alloys suitable for use as permanent magnets in accordance with the present disclosure include, but are not limited to, neodymium magnets (also referred to as neodymium iron boron or NdFeB magnets), samarium cobalt magnets (also referred to as SmCo magnets), AlNiCo magnets (also referred to as aluminum nickel cobalt magnets), and ceramic magnets (also referred to as ferrite magnets). A temporary magnet is a material that does not possess its own magnetism but becomes magnetized when subjected to a magnetic field. Examples of metals and alloys suitable for use as temporary magnets in accordance with the present disclosure include, but are not limited to, lead, aluminum, iron, nickel, and alloys thereof. Like a temporary magnet, an electromagnet does not possess its own magnetism. An electromagnet becomes magnetized when subjected to an electric current. Examples of metals and metal alloys suitable for use as electromagnets in accordance with the present disclosure include, but are not limited to, copper, iron, steel, and cobalt.

Magnets suitable for use in accordance with the present disclosure may be included in various shapes depending on the desired characteristics of the golf ball component and finished golf ball including such golf ball component. In some embodiments, the magnets may be amorphous, i.e., the magnets do not have a defined shape. In other embodiments, each magnet may have a defined shape. Suitable shapes for magnets include, but are not limited to, spheres, hemispheres, cylinders, discs, cones, square-based pyramids, polyhedrons, prisms, and combinations thereof. In some embodiments, each magnet may be the same shape. In other embodiments, the magnets may vary in shape. Without being bound to any particular theory, the shape of the magnet may affect the magnetic interaction between magnets as well as other properties, such as the weight distribution within the golf ball core or cover. In still other embodiments, the magnets may be a combination of amorphous magnets and magnets with a defined shape. For example, the plurality of magnets that are either embedded directly in the golf ball core or cover or embedded in one or more polymeric networks (depending on the embodiment) may include a mixture of amorphous magnets and defined shape magnets. In some embodiments, the plurality of magnets may include about 10 percent to about 50 percent amorphous magnets and about 50 percent to about 90 percent defined shape magnets. In other embodiments, the plurality of magnets may include about 50 percent to about 90 percent amorphous magnets and about 10 percent to about 50 percent defined shape magnets.

Magnets suitable for use in accordance with the present disclosure may be included in various sizes depending on the desired characteristics of the golf ball core or cover. The magnets may be on the scale of nanoparticles, microparticles, or larger. For example, the magnets may be about 1 nm to about 1 cm in size. In one embodiment, the magnets may be about 1 nm to about 1000 nm in size or about 1 nm to about 500 nm in size or about 500 nm to about 1000 nm in size or about 300 nm to about 700 nm in size. In another embodiment, the magnets may be about 1 m to about 1000 m in size or about 1 m to about 500 m in size or about 500 m to about 1000 m in size or about 300 m to about 700 m in size. In still another embodiment, the magnets may be about 1 mm to about 10 mm in size or about 1 mm to about 5 mm in size or about 5 mm to about 10 mm in size or about 3 mm to about 7 mm in size. In some embodiments, each of the magnets in the plurality of magnets may be approximately the same size. In other embodiments, the magnets in the plurality of magnets may differ in size. For example, the plurality of magnets may include nanoparticles and microparticles.

The polymeric network of an elasto-magnetic metamaterial may be formed from a polymer including, but not limited to, polybutadiene, polyisoprene, ethylene propylene rubber, ethylene-propylene-diene rubber, styrene-butadiene rubber, styrenic block copolymer rubbers, polyalkenamers such as, for example, polyoctenamer, butyl rubber, halobutyl rubber, polystyrene elastomers, polyethylene elastomers, polyurethane elastomers, polyurea elastomers, metallocene-catalyzed elastomers and plastomers, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and blends of two or more thereof. In one embodiment, for example, the polymeric network is composed of polyurethane having a hardness of at least about 40 Shore A. The polymeric network may also include one or more of the co-agents, fillers, radical scavengers, initiators, or other additives discussed herein. The polymer of the polymeric network may be the same as or different from other materials used in the golf ball component in which the polymeric network is included, such as the base rubber of the core composition. For example, when the base rubber of the core is polybutadiene, the polymer of the polymer network included in the core may also be polybutadiene, a blend of base rubbers including polybutadiene, or a different polymer altogether. In some embodiments, the polymer of the polymeric network is blended with the other materials in the golf ball component such that the polymeric network is an integral part of the golf ball component. In other embodiments, the polymer of the polymeric network does not blend with the other materials in the golf ball component such that the polymeric network is a distinct component embedded in the golf ball component.

The polymeric network included in the composition of a golf ball component in accordance with the present disclosure may vary in shape depending on the desired performance characteristics of the golf ball component. More specifically, the polymer network may vary in shape depending on the desired performance characteristics of the golf ball core, if the composition of the present disclosure is used to form one or more portions/layers the golf ball core. In some embodiments, the polymeric network may include a plurality of subunits, referred to herein as plates. The subunits may be arranged to give the polymeric network itself a desired shape. In some embodiments, the polymeric network may be in the shape of a chain. In this aspect, the chain may be one or more units wide. In other embodiments, the polymeric network may be in the shape of a plane formed from a single layer of plates. In further embodiments, a polymeric network may be a three-dimensional shape including, but not limited to, spheres, hemispheres, cylinders, discs, cones, square-based pyramids, polyhedrons, or prisms.

Plates of the polymeric network suitable for use in accordance with the present disclosure may be included in various shapes depending on the desired characteristics of the golf ball component. Suitable shapes for the plates of the polymeric network include, but not limited to, spheres, hemispheres, cylinders, discs, cones, square-based pyramids, polyhedrons, or prisms. The plates forming a polymeric network may all be the same shape or the plates forming a polymeric network may be different in shape. In some embodiments, each plate forming the polymeric network may be connected to one or more other plates by one or more ligaments. In this aspect, each ligament may connect an edge or vertex of one plate to an edge or vertex of another plate. The thickness and position of the ligaments may affect the properties of the polymeric network and, in turn, the properties of the golf ball component.

In other embodiments, the polymeric network may include a plurality of pores to allow for expansion and compression of the polymeric network. The shape and position of the pores may be determined by the shape and position of the plates in the polymeric network. In one embodiment, for example, the polymeric network includes a plurality of rectangular-prism-shaped plates separated by orthogonally aligned pores. In such an embodiment, each plate may be connected to at least two other plates via ligaments. In this aspect, the polymeric network may have an open phase and a closed phase. As used herein, the polymeric network is said to be in an open phase when the pores are open, i.e., when the pores separate the sides of the plates. Also as used herein, the polymeric network is said to be in a closed phase when the pores are closed, i.e., when the pores do not separate the sides of the plates. A polymeric network may be said to be in a transitional phase when some pores of the polymeric network are open and some pores of the polymeric network are closed. In a relaxed state, the polymeric network may be in an open phase, a closed phase, or a combination thereof. The polymeric network may fully or partially transition between the open phase and the closed phase. For example, in some embodiments, a golf ball core or cover formed in accordance with the present disclosure may include a resiliency additive having a polymeric network that is open phase in a relaxed state. During play, the polymeric network of such a golf ball core or cover may fully or partially transition from the open phase to the closed phase when the golf ball is struck by a golf club and may fully or partially transition back from the closed phase to the open phase as the golf ball moves away from the golf club. In some embodiments, the polymeric network of the golf ball core or cover may oscillate between the open phase and the closed phase after the ball is struck by a golf club.

Each plate may also have one or more cavities for receiving and securing magnets. Each cavity may receive one, two, three, or four or more magnets. A cavity may be disposed centric or eccentric within the plate. In embodiments having one or more cavities, the cavities may be disposed in a desired arrangement. For example, in an embodiment having a plate with two cavities, the cavities may be placed adjacent to one another or on opposite ends of the plate. In some embodiments, the cavity may be shaped as the inverse of the shape of the magnet to be received. For example, if the magnet is cylindrical, the cavity may be a hollow cylinder configured to receive the magnet. In one embodiment, the cavity may fully envelop the magnet such that the magnet cannot be removed from the plate. In another embodiment, the plate may include an aperture exposing the cavity and, when present, the magnet, to the surrounding environment. The cavity in each plate may have a flange around the aperture to prevent the magnet from exiting the cavity through the aperture. The magnet may also be press-fit in the cavity to prevent the magnet from exiting the cavity. In one embodiment, a magnet may be secured in a cavity of a plate such that the magnet cannot move or rotate within the cavity. In another embodiment, a magnet may be secured in a cavity of a plate such that the magnet cannot move or rotate within the cavity unless acted on by a force external to the golf ball core or cover, such as an external magnetic force.

The properties of the polymeric network and the magnets embedded therein may affect the phase transitions of the polymeric network. In this regard, properties of the polymeric network that may affect the phase transitions of the polymeric network include, but are not limited to, the composition of the polymeric network, the shape and size of the plates, the shape and size of the pores, and the ligament thickness. Properties of the magnets that may affect the phase transition of the polymeric network include, but are not limited to, the composition, shape, and size of the magnets, and the relative orientation of the magnets (as discussed in greater detail below). Without being bound to any particular theory, the properties of a golf ball core or cover formed in accordance with the present disclosure, e.g., including a base rubber and a resiliency additive, may be affected and/or controlled using the phase transitions of the polymeric network.

A golf ball of the present disclosure may contain a single- or multi-layered core. As discussed in more detail below, one or more of the layers of the core may include a core composition including a base rubber and one or more components. If the core is a multi-layered core, the core composition of different layers may be the same or different. Concentrations of components are in parts per hundred (phr) unless otherwise indicated. As used herein, the term, “parts per hundred,” also known as “phr” or “pph” is defined as the number of parts by weight of a particular component present in a mixture, relative to 100 parts by weight of the polymer component. Mathematically, this can be expressed as the weight of an ingredient divided by the total weight of the polymer, multiplied by a factor of 100.

In some embodiments, the base rubber is included in the core composition in an amount of about 5 percent to 100 percent by weight based on the total weight of the core composition. In one embodiment, the base rubber is included in the core composition in an amount within a range having a lower limit of about 5 percent or 10 percent or 20 percent or 30 percent or 40 percent or 50 percent or 55 percent and an upper limit of about 60 percent or 70 percent or 80 percent or 90 percent or 95 percent or 100 percent. For example, the base rubber may be present in the core composition in an amount of about 30 percent to about 90 percent or about 40 percent to about 80 percent by weight base rubber based on the total weight of the core composition. In another example, the core composition includes about 50 percent to about 70 percent or about 60 percent to about 70 percent by weight base rubber based on the total weight of the core composition.

The base rubber may be polybutadiene, polyisoprene, ethylene propylene rubber, ethylene-propylene-diene rubber, styrene-butadiene rubber, styrenic block copolymer rubbers, polyalkenamers such as, for example, polyoctenamer, butyl rubber, halobutyl rubber, polystyrene elastomers, polyethylene elastomers, polyurethane elastomers, polyurea elastomers, metallocene-catalyzed elastomers and plastomers, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and blends of two or more thereof. In one embodiment, the core composition includes polybutadiene rubber, butyl rubber, or a blend thereof as the base rubber.

For example, the core may be formed from a core composition that includes polybutadiene as the base rubber. Polybutadiene is a homopolymer of 1,3-butadiene. The double bonds in the 1,3-butadiene monomer are attacked by catalysts to grow the polymer chain and form a polybutadiene polymer having a desired molecular weight. Any suitable catalyst may be used to synthesize the polybutadiene rubber depending upon the desired properties. In one embodiment, a transition metal complex (for example, neodymium, nickel, or cobalt) or an alkyl metal such as alkyl lithium is used as a catalyst. Other suitable catalysts include, but are not limited to, aluminum, boron, lithium, titanium, and combinations thereof. As would be appreciated by those of ordinary skill in the art, different catalysts produce polybutadiene rubbers having different chemical structures. In a cis-bond configuration, the main internal polymer chain of the polybutadiene appears on the same side of the carbon-carbon double bond contained in the polybutadiene. In a trans-bond configuration, the main internal polymer chain is on opposite sides of the internal carbon-carbon double bond in the polybutadiene. The polybutadiene rubber used as a base rubber in accordance with the present disclosure can have various combinations of cis- and trans-bond structures. For example, the polybutadiene rubber may have a 1,4 cis-bond content of at least 40 percent. In another embodiment, the polybutadiene rubber has a 1,4 cis-bond content of greater than 60 percent. In yet another embodiment, the polybutadiene rubber has a 1,4 cis-bond content of greater than 80 percent. In still another embodiment, the polybutadiene rubber has a 1,4 cis-bond content of greater than 90 percent. In general, polybutadiene rubbers having a high 1,4 cis-bond content have high tensile strength and rebound.

In some embodiments, the core composition of the present disclosure includes a blend of base rubbers and, more specifically, a blend of two or more polybutadiene rubbers. In this aspect, the core composition may include a blend of a first polybutadiene rubber and a second polybutadiene rubber in a ratio of about 5:95 to about 95:5. For example, the core composition may include a first polybutadiene rubber and a second polybutadiene rubber in a ratio of about 10:90 to about 90:10 or about 15:85 to about 85:15 or about 20:80 to about 80:20 or about 30:70 to about 70:30 or about 40:60 to about 60:40. In other embodiments, the core composition may include a blend of more than two polybutadiene rubbers or a blend of polybutadiene rubbers with any of the other elastomers discussed above.

The polybutadiene rubber may have a relatively high or low Mooney viscosity. Generally, polybutadiene rubbers of higher molecular weight and higher Mooney viscosity have better resiliency than polybutadiene rubbers of lower molecular weight and lower Mooney viscosity.

However, as the Mooney viscosity increases, the milling and processing of the polybutadiene rubber generally becomes more difficult. Blends of high and low Mooney viscosity polybutadiene rubbers may be prepared as is described in U.S. Pat. Nos. 6,982,301 and 6,774,187, the disclosures of which are hereby incorporated by reference, and used in accordance with this invention. In general, the lower limit of Mooney viscosity may be about 30 or 35 or 40 or 45 or 50 or 55 or 60 or 70 or 75 and the upper limit may be about 80 or 85 or 90 or 95 or 100 or 105 or 110 or 115 or 120 or 125 or 130. For example, the polybutadiene used in the core composition has a Mooney viscosity of about 30 to about 130. In some aspects, the polybutadiene used in the core composition may have a Mooney viscosity of about 30 to about 80 or about 75 to about 130.

Examples of commercially available polybutadiene rubbers that can be used in core composition in accordance with this invention, include, but are not limited to, PR-040G, available from CHIMEI Corporation of Tainan City, Taiwan; BR 01 and BR 1220, available from BST Elastomers of Bangkok, Thailand; SE BR 1220LA and SE BR1203, available from DOW Chemical Co of Midland, Mich.; BUDENE 1207, 1207s, 1208, and 1280 available from Goodyear, Inc of Akron, Ohio; BR 01, 51 and 730, available from Japan Synthetic Rubber (JSR) of Tokyo, Japan; BUNA CB 21, CB 22, CB 23, CB 24, CB 25, CB 29 MES, CB 60, CB Nd 60, CB 55 NF, CB 70 B, CB KA 8967, and CB 1221, available from Lanxess Corp. of Pittsburgh, Pa.; BR1208, available from LG Chemical of Seoul, South Korea; UBEPOL BR130B, BR150, BR150B, BR150L, BR230, BR360L, BR710, and VCR617, available from UBE Industries, Ltd. of Tokyo, Japan; EUROPRENE NEOCIS BR 60, INTENE 60 AF and P30AF, and EUROPRENE BR HV80, available from Polimeri Europa of Rome, Italy; KBR 01, NdBr 40, NdBR-45, NdBr 60, KBR 710S, KBR 710H, and KBR 750, available from Kumho Petrochemical Co., Ltd. Of Seoul, South Korea; DIENE 55NF, 70AC, and 320 AC, available from Firestone Polymers of Akron, Ohio; and PBR-Nd Group II and Group III, available from Nizhnekamskneftekhim, Inc. of Nizhnekamsk, Tartarstan Republic.

In another embodiment, the core composition includes butyl rubber. Butyl rubber is synthetic polymer made by polymerizing isobutylene and isoprene. Butyl rubber is an amorphous, non-polar polymer with good oxidative and thermal stability, good permanent flexibility and high moisture and gas resistance. Generally, butyl rubber includes copolymers of about 70 percent to about 99.5 percent by weight of an isoolefin, which has about 4 to 7 carbon atoms, for example, isobutylene, and about 0.5 percent to about 30 percent by weight of a conjugated multiolefin, which has about 4 to 14 carbon atoms, for example, isoprene. The resulting copolymer contains about 85 percent to about 99.8 percent by weight of combined isoolefin and about 0.2 percent to about 15 percent of combined multiolefin. A non-limiting example of a commercially available butyl rubber includes Bayer Butyl 301 manufactured by Bayer AG.

In still another embodiment, the core composition used to form the core includes a blend of polybutadiene and butyl rubber. In this embodiment, the core composition may include a blend of polybutadiene and butyl rubber in a ratio of about 10:90 to about 90:10. For example, the core composition may include a blend of polybutadiene and butyl rubber in a ratio of about 10:90 to about 90:10 or about 20:80 to about 80:20 or about 30:70 to about 70:30 or about 40:60 to about 60:40. In other embodiments, the core composition may include polybutadiene and/or butyl rubber in a blend with any of the other elastomers discussed above.

The resiliency additive discussed above may be included in the core composition in varying amounts depending on the desired characteristics of the golf ball core. Generally, changes to a golf ball core that affect the resiliency of a golf ball core also affect the compression of the golf ball core. For example, changes to the golf ball core that increase the CoR of the golf ball core may also increase the compression of the golf ball core, and changes to the golf ball core that decrease the CoR of the golf ball core may also decrease the compression of the golf ball core. However, a resiliency additive used in accordance with the present disclosure may allow the CoR of the golf ball core to be manipulated independently from the compression of the golf ball core or with minimal effect on the compression of the golf ball core.

In some embodiments, the resiliency additive may be used in an amount of about 1 to about 50 parts by weight per 100 parts of the total rubber. In one embodiment, the core composition of the core includes about 1 to about 25 or about 1 to about 10 or about 5 to about 15 parts by weight resiliency additive per 100 parts of the total rubber. In another embodiment, the resiliency additive is included in the core composition in an amount of about 10 to about 30 or about 13 to about 23 or about 17 to about 27 parts by weight per 100 parts of the total rubber. In yet another embodiment, the core composition includes about 25 to about 45 or about 27 to about 37 or about 33 to about 43 parts by weight resiliency additive per 100 parts of the total rubber.

The core compositions further include a reactive cross-linking co-agent. Suitable co-agents include, but are not limited to, metal salts of unsaturated carboxylic acids having from 3 to 8 carbon atoms; unsaturated vinyl compounds and polyfunctional monomers (e.g., trimethylolpropane trimethacrylate); phenylene bismaleimide; and combinations thereof. In one embodiment, the co-agent is one or more metal salts of acrylates, diacrylates, methacrylates, and dimethacrylates, wherein the metal is selected from magnesium, calcium, zinc, aluminum, lithium, and nickel. In another embodiment, the co-agent includes one or more zinc salts of acrylates, diacrylates, methacrylates, and dimethacrylates. For example, the co-agent may be zinc diacrylate (ZDA). In another embodiment, the co-agent may be zinc dimethacrylate (ZDMA). A non-limiting example of a commercially available zinc diacrylate includes Dymalink® 526 manufactured by Cray Valley.

The co-agent may be included in the core composition in varying amounts depending on the desired characteristics of the golf ball core. For example, the co-agent may be used in an amount of about 10 to about 50 parts by weight per 100 parts of the total rubber. In one embodiment, the core composition includes about 15 to about 40 parts by weight co-agent per 100 parts of the total rubber. In another embodiment, the core composition includes about 20 to about 35 or about 22 to about 30 parts by weight co-agent per 100 parts of total rubber. In still another embodiment, the core composition includes about 23 to about 27 or about 25 to about 29 parts by weight co-agent per 100 parts of the total rubber. Without being bound to any particular theory, increasing the concentration of co-agent in the core composition of a golf ball core increases the compression and CoR of a golf ball core.

Radical scavengers such as a halogenated organosulfur, organic disulfide, or inorganic disulfide compounds may also be added to the core composition. In one embodiment, a halogenated organosulfur compound included in the core composition includes, but is not limited to, pentachlorothiophenol (PCTP) and salts of PCTP such as zinc pentachlorothiophenol (Zn-PCTP). In another embodiment, ditolyl disulfide, diphenyl disulfide, dixylyl disulfide, 2-nitroresorcinol, and combinations thereof are added to the core composition. A non-limiting example of a commercially available radical scavenger includes Rhenogran® Zn-PTCP-72 manufactured by Rheine Chemie. The radical scavenger may be included in the core composition in an amount of about 0.1 to about 1 part by weight per 100 parts of the total rubber. In one embodiment, the core composition may include about 0.3 to about 0.8 parts by weight radical scavenger compound per 100 parts of the total rubber. In another embodiment, the core composition may include about 0.2 to about 0.5 or about 0.4 to about 0.6 or about 0.5 to about 0.8 parts by weight radical scavenger compound per 100 parts of the total rubber.

The core composition may also include filler(s). Suitable non-limiting examples of fillers include carbon black, clay and nanoclay particles, talc, glass (e.g., glass flake, milled glass, and microglass), mica and mica-based pigments (e.g., Iriodin® pearl luster pigments from The Merck Group), and combinations thereof. Metal oxide and metal sulfate fillers are also contemplated for inclusion in the core composition. Suitable metal fillers include, for example, particulate, powders, flakes, and fibers of copper, steel, brass, tungsten, titanium, aluminum, magnesium, molybdenum, cobalt, nickel, iron, lead, tin, zinc, barium, bismuth, bronze, silver, gold, and platinum, and alloys and combinations thereof. Suitable metal oxide fillers include, for example, zinc oxide, iron oxide, aluminum oxide, titanium oxide, magnesium oxide, and zirconium oxide. Suitable metal sulfate fillers include, for example, barium sulfate and strontium sulfate.

When included, the fillers may be in an amount of about 1 to about 40 parts by weight per 100 parts of the total rubber. In one embodiment, the core composition includes at least one filler in an amount of about 1 to about 15 or about 3 to about 10 parts by weight per 100 parts of the total rubber. In another embodiment, the core composition includes at least one filler in an amount of about 3 to about 7 or about 5 to about 9 or about 5 to about 7 parts by weight per 100 parts of the total rubber. In yet another embodiment, the core composition includes at least one filler in an amount of about 1 to about 30 or about 5 to about 25 or about 10 to about 20 parts by weight per 100 parts of the total rubber. In a further embodiment, the core composition includes at least one filler in an amount of about 12 to about 17 or about 13 to about 18 or about 14 to about 16 parts by weight per 100 parts of the total rubber. A non-limiting example of a commercially available filler suitable for use in accordance with the present disclosure includes PolyWate® 325 manufactured by Cimbar Performance Minerals.

In some embodiments, more than one type of filler may be included in the core composition. For example, in one embodiment, the core composition may include a first filler in an amount from about 1 to about 15 or about 2 to about 12 parts by weight per 100 parts total rubber and a second filler in an amount from about 1 to about 30 or about 7 to about 22 parts by weight per 100 parts total rubber. In another embodiment, the core composition may include a first filler in an amount from about 3 to about 10 or about 4 to about 8 parts by weight per 100 parts total rubber and a second filler in an amount from about 11 to about 19 or about 13 to about 17 parts by weight per 100 parts total rubber. In yet another embodiment, the core composition may include a first filler in an amount from about 2 to about 6 or about 4 to about 8 parts by weight per 100 parts total rubber and a second filler in an amount from about 11 to about 16 or about 14 to about 19 parts by weight per 100 parts total rubber.

Antioxidants, processing aids, accelerators (for example, tetra methylthiuram), dyes and pigments, wetting agents, surfactants, plasticizers, coloring agents, fluorescent agents, chemical blowing agents, foaming agents, defoaming agents, stabilizers, softening agents, impact modifiers, antiozonants, as well as other additives known in the art, may also be added to the core composition. Examples of suitable processing aids include, but are not limited to, high molecular weight organic acids and salts thereof. Suitable organic acids are aliphatic organic acids, aromatic organic acids, saturated mono-functional organic acids, unsaturated monofunctional organic acids, multi-unsaturated mono-functional organic acids, and dimerized derivatives thereof. In one embodiment, the organic acids include, but are not limited to, caproic acid, caprylic acid, capric acid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylacetic acid, naphthalenoic acid, and dimerized derivatives thereof. The salts of organic acids include the salts of barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, or calcium, salts of fatty acids, particularly stearic, behenic, erucic, oleic, linoelic or dimerized derivatives thereof.

The core composition may be cured using conventional curing processes. Non-limiting examples of curing processes suitable for use in accordance with the present disclosure include peroxide-curing, sulfur-curing, high-energy radiation, and combinations thereof. In one embodiment, the core composition includes a free-radical initiator selected from organic peroxides, high energy radiation sources capable of generating free-radicals, and combinations thereof. Suitable organic peroxides include, but are not limited to, dicumyl peroxide; n-butyl-4,4-di(t-butylperoxy) valerate; 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane; 2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide; di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide; 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3; di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoyl peroxide; t-butyl hydroperoxide; and combinations thereof. In a particular embodiment, the free radical initiator is dicumyl peroxide, including, but not limited to Perkadox® BC, commercially available from Akzo Nobel. Peroxide free-radical initiators may be present in the core composition in an amount of at least 0.05 parts by weight per 100 parts of the total rubber, or an amount within the range having a lower limit of 0.05 parts or 0.1 parts or 1 part or 1.25 parts or 1.5 parts or 2.5 parts or 5 parts by weight per 100 parts of the total rubber, and an upper limit of 2.5 parts or 3 parts or 5 parts or 6 parts or 10 parts or 15 parts by weight per 100 parts of the total rubber. For example, the core composition may include peroxide free-radical initiators in an amount of about 0.1 to about 2.5 or about 0.3 to about 1.8 or about 0.5 to about 1.2 parts by weight per 100 parts of the total rubber. In another example, the core composition may include peroxide free-radical initiators in an amount of about 0.5 to about 0.9 or about 0.7 to about 1.2 or about 0.6 to about 1.0 or about 0.7 to about 0.9 parts by weight per 100 parts of the total rubber.

In contrast to the core, the cover of a golf ball plays less of a role on shots made with a driver. However, because the cover plays a large role in generating spin on iron and wedge shots, the cover material and properties are still important in determining the performance of the finished golf ball. In this aspect, different materials may be used in the construction of the intermediate and cover layers of golf balls according to the present disclosure. Among other things, the resiliency of conventional golf balls is constrained by available materials typically used in golf ball covers, such as ionomers and polyurethanes. These materials typically have a low CoR and cannot easily be tailored to produce a cover with a desired CoR. As discussed in more detail below, one or more of the layers of the cover may include a cover formed from a composition including a resiliency additive to produce a cover having a tailored or desired CoR.

In some embodiments, the resiliency additive is included in the cover composition in an amount of about 5 percent to 100 percent by weight based on the total weight of the cover composition. In one embodiment, the resiliency additive is included in the cover composition in an amount within a range having a lower limit of about 5 percent or 10 percent or 20 percent or 30 percent or 40 percent or 50 percent and an upper limit of about 50 percent or 60 percent or 70 percent or 80 percent or 90 percent or 95 percent or 100 percent. For example, the resiliency additive may be present in the cover composition in an amount of about 5 percent to about 95 percent or about 10 percent to about 90 percent or about 20 percent to about 80 percent or about 30 percent to about 70 percent or about 40 percent to about 60 percent by weight resiliency additive based on the total weight of the cover composition. In another example, the cover composition includes about 10 percent to about 70 percent or about 20 percent to about 60 percent or about 30 percent to about 50 percent or about 10 percent to about 40 percent or about 40 percent to about 70 percent or about 10 percent to about 30 percent or about 50 percent to about 70 percent by weight resiliency additive based on the total weight of the cover composition. In a further example, the cover composition may include about 30 percent to about 90 percent or about 40 percent to about 80 percent or about 50 percent to about 70 percent or about 30 percent to about 70 percent or about 50 percent to about 90 percent or about 30 percent to about 50 percent or about 70 percent to about 90 percent by weight resiliency additive based on the total weight of the cover composition. In one embodiment, the cover is formed entirely from the resiliency additive.

In other embodiments, the resiliency additive may be included in the cover composition along with one or more other components. For example, the cover composition may also include a base polymer. In some embodiments, the base polymer may be present in the cover composition in an amount of about 5 percent to about 95 percent or about 10 percent to about 90 percent or about 20 percent to about 80 percent or about 30 percent to about 70 percent or about 40 percent to about 60 percent by weight resiliency additive based on the total weight of the cover composition. In another example, the cover composition includes about 10 percent to about 70 percent or about 20 percent to about 60 percent or about 30 percent to about 50 percent or about 10 percent to about 50 percent or about 30 percent to about 70 percent or about 10 percent to about 30 percent or about 50 percent to about 70 percent by weight base polymer based on the total weight of the cover composition. In a further example, the cover composition may include about 30 percent to about 90 percent or about 40 percent to about 80 percent or about 50 percent to about 70 percent or about 60 percent to about 90 percent or about 30 percent to about 60 percent or about 30 percent to about 50 percent or about 70 percent to about 90 percent by weight base polymer based on the total weight of the cover composition. In some embodiments, the cover may include a blend of two or more base polymers.

The base polymer may be a variety of materials depending on the desired characteristics and performance of a golf ball having a cover formed from a cover composition as described herein, e.g., including a base polymer and a resiliency additive. Examples of materials suitable for use as the base polymer include, but are not limited to, polyurethanes; polyureas; copolymers, blends and hybrids of polyurethane and polyurea; olefin-based copolymer ionomer resins; polyethylene, including, for example, low density polyethylene, linear low density polyethylene, and high density polyethylene; polypropylene; rubber-toughened olefin polymers; acid copolymers, for example, poly(meth)acrylic acid, which do not become part of an ionomeric copolymer; plastomers; flexomers; styrene/butadiene/styrene block copolymers; styrene/ethylene-butylene/styrene block copolymers; dynamically vulcanized elastomers; copolymers of ethylene and vinyl acetates; copolymers of ethylene and methyl acrylates; polyvinyl chloride resins; polyamides, poly(amide-ester) elastomers, and graft copolymers of ionomer; cross-linked trans-polyisoprene and blends thereof; polyester-based thermoplastic elastomers; polyurethane-based thermoplastic elastomers; synthetic or natural vulcanized rubber; and combinations thereof.

In other embodiments, the base polymer is a polyurethane, polyurea, or hybrid of polyurethane-polyurea. When used as cover layer materials, polyurethanes and polyureas can be thermoset or thermoplastic. Thermoset materials can be formed into golf ball layers by conventional casting or reaction injection molding techniques. Thermoplastic materials can be formed into golf ball layers by conventional compression or injection molding techniques. Generally, cover layers made from polyurethane, polyurea, or hybrids of polyurethane-polyurea have a low resilience. Without being bound to any particular theory, including the resiliency additive in a cover layer formed from polyurethane, polyurea, or hybrid of polyurethane-polyurea may allow for the resiliency of the cover layer to be increased or tailored to a desired core value.