Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/0023—Covers
  • A63B37/0029—Physical properties
  • A63B37/0031—Hardness
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/0023—Covers
  • A63B37/0029—Physical properties
  • A63B37/0033—Thickness
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/0023—Covers
  • A63B37/0029—Physical properties
  • A63B37/0037—Flexural modulus; Bending stiffness
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B37/00—Solid balls; Rigid hollow balls; Marbles
  • A63B37/0003—Golf balls
  • A63B37/007—Characteristics of the ball as a whole
  • A63B37/0072—Characteristics of the ball as a whole with a specified number of layers
  • A63B37/0075—Three piece balls, i.e. cover, intermediate layer and core
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C08L23/0869—Acids or derivatives thereof
  • C08L23/0876—Neutralised polymers, i.e. ionomers

Definitions

• the present invention relates to golf balls and, more particularly, to improved gold balls comprising multi- layer covers which have a comparatively hard inner layer and a relatively soft outer layer, and a unique dual core configuration.
• the improved multilayer golf balls provide for enhanced distance and durability properties over single layer cover golf balls while at the same time offering enhanced "feel" and spin characteristics generally associated with soft balata and balata-like covers of the prior art.
• Traditional golf ball covers have been comprised of balata or blends of balata with elastomeric or plastic materials.
• the traditional balata covers are relatively soft and flexible. Upon impact, the soft balata covers compress against the surface of the club producing high spin. consequently, the soft and flexible balata covers provide an experienced golfer with the ability to apply a spin to control the ball in flight in order to produce a draw or a fade, or a backspin which causes the ball to "bite" or stop abruptly on contact with the green.
• the soft balata covers produce a soft "feel" to the low handicap player.
• Such playability properties are particularly important in short iron play with low swing speeds and are exploited significantly by relatively skilled players.
• balata covered golf balls are easily cut and/or damaged if mis- hit. Golf balls produced with balata or balata- containing cover compositions therefore have a relatively short lifespan.
• Ionomeric resins are generally ionic copolymers of an olefin, such as ethylene, and a metal salt of an unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, or maleic acid.
• Metal ions such as sodium or zinc, are used to neutralize some portion of the acidic group in the copoly er resulting in a thermoplastic elastomer exhibiting enhanced properties, i.e. durability, etc., for golf ball cover construction over balata.
• some of the advantages gained in increased durability have been offset to some degree by the decreases produced in playability.
• the ionomeric resins are very durable, they tend to be very hard when utilized for golf ball cover construction, and thus lack the degree of softness required to impart the spin necessary to control the ball in flight. Since the ionomeric resins are harder than balata, the ionomeric resin covers do not compress as much against the face of the club upon impact, thereby producing less spin. In addition, the harder and more durable ionomeric resins lack the "feel" characteristic associated with the softer balata related covers.
• a multi-layered golf ball is produced by initially molding a first cover layer on a spherical core and then adding a second layer.
• the first layer is comprised of a hard, high flexural modulus resinous material such as type 1605
• Surlyn ® (now designated Surlyn ® 8940) .
• type 1605 Surlyn (Surlyn ® 8940) is a sodium ion based low acid (less than or equal to 15 weight percent methacrylic acid) ionomer resin having a flexural modulus of about 51,000 psi.
• An outer layer of a comparatively soft, low flexural modulus resinous material such as type 1855 Surlyn ® (now designated Surlyn ® 9020) is molded over the inner cover layer.
• Type 1855 Surlyn ® (Surlyn ® 9020) is a zinc ion based low acid (10 weight percent methacrylic acid) ionomer resin having a flexural modulus of about 14,000 psi .
• the '193 patent teaches that the hard, high flexural modulus resin which comprises the first layer provides for a gain in coefficient of restitution over the coefficient of restitution of the core. The increase in the coefficient of restitution provides a ball which serves to attain or approach the maximum initial velocity limit of 255 feet per second as provided by the United States Golf Association (U.S.G.A.) rules.
• the relatively soft, low flexural modulus outer layer provides for the advantageous "feel" and playing characteristics of a balata covered golf ball.
• U.S. Patent Nos . 4884,814 and 5,120,791 are directed to cover compositions containing blends of hard and soft ionomeric resins.
• the hard copolymers typically are made from an olefin and an unsaturated carboxylic acid.
• the present invention provides a golf ball comprising a dual core comprising a center component and a core layer disposed about the center component .
• the golf ball further comprises an inner cover layer molded on the inner cover layer.
• the inner cover layer is formed from a high acid ionomer including at least 16% by weight of an alpha, beta-unsaturated carboxylic acid.
• the outer cover layer is formed from a relatively soft polymeric material such as low flexural modulus ionomer resins and non-ionomeric thermoplastic elastomers.
• the present invention provides a multi -layer golf ball comprising a dual core component that includes an interior spherical center component and a core layer disposed about the spherical center component.
• the golf ball further comprises an inner cover layer molded over the core layer of the dual core, and an outer cover layer molded over the inner cover layer.
• the inner and outer cover layers have particular properties.
• the inner cover layer comprises an ionomeric resin including at least 16% by weight of an alpha, beta-unsaturated carboxylic acid and has a modulus of from about 15,000 to about 70,000 psi.
• the outer cover layer comprises a blend of a sodium or zinc salt of a particular copolymer and a particular unsaturated monocarboxylic acid, and a sodium or zinc salt of a certain terpolymer, acrylic acid and a particular unsaturated monomer of the acrylate ester class .
• the outer cover layer has a modulus of from about 1,000 to about 30,000 psi.
• the present invention provides a multi-layer golf ball comprising a spherical dual core, an inner cover layer molded over the dual core, and an outer cover layer molded over the inner cover layer.
• the inner cover layer comprises an ionomeric resin including 17% to 25% of an alpha, beta- unsaturated carboxylic acid, and has a modulus of from about 15,000 to about 70,000 psi.
• the outer cover layer comprises a non-ionomeric thermoplastic selected from the group consisting of polyester elastomer, polyester urethane, and polyester amide.
• the outer cover layer has a modulus in the range of 1,000 to 30,000 psi.
• the present invention also provides a golf ball comprising a dual core, an inner cover layer molded on the dual core, an outer cover layer molded on the inner cover layer, and at least one outer core layer disposed about the dual core.
• the inner cover layer comprises a high acid ionomer including at least 16% of an alpha, beta-unsaturated carboxylic acid.
• the outer cover layer comprises a relatively soft polymeric material of low flexural modulus ionomer resins and non-ionomeric thermoplastic elastomers .
• the present invention provides a multi-layer golf ball comprising a spherical dual core including an interior spherical center and a core layer disposed about the center.
• the golf ball further comprises an inner cover layer molded over the spherical dual core, an outer cover layer molded over the inner cover layer, and at least one inner core layer disposed between the dual core and the inner cover layer.
• the inner cover layer comprises an ionomeric resin including at least 16% of an alpha, beta- unsaturated carboxylic acid, and has a modulus of from 15,000 to 70,000 psi.
• the outer cover layer comprises a particular blend of a sodium or zinc salt of a certain copolymer and a sodium or zinc salt of a terpolymer.
• the outer cover layer has a modulus of 1,000 to 30,000 psi .
• the present invention provides a multi-layer golf ball comprising a dual core component, an inner cover molded over the dual core, an outer core layer molded over the inner cover, and at least one outer core layer disposed between the dual core and the inner cover layer.
• the inner cover layer comprises an ionomeric resin including 17% to 25% of an alpha, beta- unsaturated carboxylic acid and has a modulus of 15,000 to 70,000 psi.
• the outer cover layer comprises a non- ionomeric thermoplastic of a polyester elastomer, a polyester polyurethane and a polyester amide.
• the outer cover has a modulus in the range of 1,000 to 3,000 psi.
• FIGURE 1 is a cross-sectional view of a preferred embodiment golf ball in accordance with the present invention illustrating a core and a cover comprising an inner layer and an outer dimpled layer;
• FIGURE 2 is a diametrical cross-sectional view of the preferred embodiment golf ball depicted in FIGURE 1 having a core and a cover comprising an inner layer surrounding the core and an outer layer having a plurality of dimples;
• FIGURE 3 is a cross-sectional view of another preferred embodiment golf ball in accordance with the present invention comprising a dual core component;
• FIGURE 4 is a cross-sectional view of yet another preferred embodiment golf ball in accordance with the present invention comprising a dual core component
• FIGURE 5 is a cross-sectional view of another preferred embodiment golf ball in accordance with the present invention comprising a dual core component and an outer cover layer;
• FIGURE 6 is a cross-sectional view of yet another preferred embodiment golf ball in accordance with the present invention comprising a dual core component and an outer core layer;
• FIGURE 7 is a schematic view of an assembly used for molding a preferred embodiment golf ball in accordance with the present invention.
• the present invention is directed to a golf ball comprising a dual-core component and a multi-layer cover.
• the novel multi -layer golf ball covers of the present invention include a first or inner layer or ply of a high acid (greater than 16 weight percent acid) ionomer blend or, more preferably, a low acid (16 weight percent acid or less) ionomer blend and second or outer layer or ply comprised of a comparatively softer, low modulus ionomer, ionomer blend or other non- ionomeric thermoplastic or thermosetting elastomer such as polyurethane or polyester elastomer.
• the multi -layer golf balls of the present invention can be of standard or enlarged size.
• the inner layer or ply includes a blend of low acid ionomers and has a Shore D hardness of 70 or greater and the outer cover layer comprised of polyurethane and has a Shore D hardness of about 45 (i.e., Shore C hardness of about 65).
• the present invention golf balls utilize a unique dual-core configuration.
• the cores comprise (i) an interior spherical center component formed from a thermoset material, a thermoplastic material, or combinations thereof; and (ii) a core layer disposed about the spherical center component, the core layer formed from a thermoset material, a thermoplastic material, or combinations thereof.
• the cores may further comprise (iii) an optional outer core layer disposed about the core layer.
• the outer core layer may be formed from a thermoset material, a thermoplastic material, or combinations thereof.
• the present invention is primarily directed to golf balls comprising a dual core component and a multi-layer cover as described herein, the present invention also includes golf balls having a dual core component and conventional covers comprising balata, various thermoplastic materials, cast polyurethanes, or any other known cover materials .
• multi-layer golf balls having inner and outer cover layers exhibit higher C.O.R. values and have greater travel distance in comparison with balls made from a single cover layer.
• use of an inner cover layer constructed of a blend of low acid (i.e., 16 weight percent acid or less) ionomer resins produces softer compression and higher spin rates than inner cover layers constructed of high acid ionomer resins.
• the soft outer layer allows the cover to deform more during impact and increases the area of contact between the club face and the cover, thereby imparting more spin on the ball.
• the soft polyurethane cover provides the ball with a balata- like feel and playability characteristics with improved distance and durability.
• the overall combination of the unique dual core configuration, described in greater detail herein, and the multi -layer cover construction of inner and outer cover layers made, for example, from blends of low acid ionomer resins and polyurethane results in a standard size or oversized golf ball having enhanced resilience (improved travel distance) and durability (i.e. cut resistance, etc.) characteristics while maintaining and in many instances, improving the ball's playability properties.
• the combination of a low acid ionomer blend inner cover layer with a soft, relatively low modulus ionomer, polyurethane based elastomer outer cover layer provides for good overall coefficient of restitution (i.e., enhanced resilience) while at the same time demonstrating improved compression and spin.
• the outer cover layer generally contributes to a more desirable feel and spin, particularly at lower swing speeds with highly lofted clubs such as half wedge shots.
• the present invention is directed to a golf ball comprising a dual-core configuration and an improved multi- layer cover which produces, upon molding each layer around a core to formulate a multilayer cover, a golf ball exhibiting enhanced distance (i.e., resilience) without adversely affecting, and in many instances, improving the ball's playability (hardness/softness) and/or durability (i.e., cut resistance, fatigue resistance, etc.) characteristics.
• FIGS 1 and 2 illustrate a preferred embodiment golf ball 5 in accordance with the present invention. It will be understood that none of the referenced figures are to scale. And so, the thicknesses and proportions of the various layers and the diameter of the various core components are not necessarily as depicted.
• the golf ball 5 comprises a multi-layered cover 12 disposed about a core 10.
• the core 10 of the golf ball can be formed of a solid, a liquid, or any other substances that may be utilized to form the novel dual core described herein.
• the multi - layered cover 12 comprises two layers: a first or inner layer or ply 14 and a second or outer layer or ply 16.
• the inner layer 14 can be ionomer, ionomer blends, non- ionomer, non- ionomer blends, or blends of ionomer and non- ionomer.
• the outer layer 16 is softer than the inner layer and can be ionomer, ionomer blends, non- ionomer, non- ionomer blends or blends of ionomer and non- ionomer .
• the inner layer 14 is comprised of a high acid (i.e. greater than 16 weight percent acid) ionomer resin or high acid ionomer blend.
• the inner layer is comprised of a blend of two or more high acid (i.e., at least 16 weight percent acid) ionomer resins neutralized to various extents by different metal cations.
• the inner cover layer may or may not include a metal stearate (e.g., zinc stearate) or other metal fatty acid salt. The purpose of the metal stearate or other metal fatty acid salt is to lower the cost of production without affecting the overall performance of the finished golf ball.
• the inner layer 14 is comprised of a low acid (i.e., 16 weight percent acid or less) ionomer blend.
• the inner layer is comprised of a blend of two or more low acid (i.e., 16 weight percent acid or less) ionomer resins neutralized to various extents by different metal cations .
• the inner cover layer may or may not include a metal stearate (e.g., zinc stearate) or other metal fatty acid salt. The purpose of the metal stearate or other metal fatty acid salt is to lower the cost of production without affecting the overall performance of the finished golf ball.
• Resilience is determined by the coefficient of restitution (C.O.R.), the constant "e” which is the ratio of the relative velocity of two elastic spheres after direct impact to that before impact.
• C.O.R. coefficient of restitution
• e the coefficient of restitution
• Resilience (C.O.R.) along with additional factors such as club head speed, angle of trajectory and ball configuration (i.e., dimple pattern) generally determine the distance a ball will travel when hit.
• the coefficient of restitution (C.O.R.) in solid core balls is a function of the composition of the molded core and of the cover.
• the coefficient of restitution is a function of not only the composition of the cover, but also the composition and physical characteristics of the interior spherical center component and core layer. Both the dual core and the cover contribute to the coefficient of restitution in the golf balls of the present invention.
• the coefficient of restitution of a golf ball is generally measured by propelling a ball at a given speed against a hard surface and measuring the ball's incoming and outgoing velocity electronically.
• the coefficient of restitution is the ratio of the outgoing velocity to the incoming velocity.
• the coefficient of restitution must be carefully controlled in all commercial golf balls in order for the ball to be within the specifications regulated by the United States Golf Association (U.S.G.A.)
• U.S.G.A. United States Golf Association
• the U.S.G.A. standards indicate that a "regulation" ball cannot have an initial velocity (i.e., the speed off the club) exceeding 255 feet per second.
• the hardness of the ball is the second principal property involved m the performance of a golf ball.
• the hardness of the ball can affect the playability of the ball on striking and the sound or "click" produced. Hardness is determined by the deformation (i.e., compression) of the ball under various load conditions applied across the ball's diameter (i.e., the lower the compression value, the harder the material) .
• softer covers permit the accomplished golfer to impart proper spin. This is because the softer covers deform on impact significantly more than balls having "harder" ionomeric resin covers. As a result, the better player is allowed to impart fade, draw or backspm to the ball thereby enhancing playability. Such properties may be determined by various spin rate tests .
• a hard inner layer provides for a substantial increase m resilience (i.e., enhanced distance) over known multi-layer covered balls
• the softer outer layer provides for desirable "feel" and high spin rate while maintaining respectable resiliency
• the soft outer layer allows the cover to deform more during impact and increases the area of contact between the club face and the cover, thereby imparting more spin on the ball.
• the soft cover provides the ball with a balata-like feel and playability characteristics with improved distance and durability. Consequently, the overall combination of the inner and outer cover layers results m a golf ball having enhanced resilience (improved travel distance) and durability (i.e., cut resistance, etc.) characteristics while maintaining and m many instances, improving the playability properties of the ball.
• a hard inner cover layer with a soft, relatively low modulus ionomer, ionomer blend or other non-ionomeric thermoplastic elastomer outer cover layer provides for excellent overall coefficient of restitution (i.e., excellent resilience) because of the improved resiliency produced by the inner cover layer. While some improvement m resiliency is also produced by the outer cover layer, the outer cover layer generally provides for a more desirable feel and high spin, particularly at lower swing speeds with highly lofted clubs such as half wedge shots.
• the inner cover layer is harder than the outer cover layer and generally has a thickness m the range of 0.01 to 0.10 inches, preferably 0.03 to 0.07 inches for a 1.68 inch ball and 0.05 to 0.10 inches for a 1.72 inch (or more) ball.
• the core and inner cover layer together form an inner ball having a coefficient of restitution of 0.780 or more and more preferably 0.790 or more, and a diameter m the range of 1.48 - 1.66 inches for a 1.68 inch ball and 1.50 - 1.70 inches for a 1.72 inch (or more) ball.
• the inner cover layer has a Shore D hardness of 60 or more.
• the golf balls of the invention have an inner layer with a Shore D hardness of 65 or more
• the above-described characteristics of the inner cover layer provide an inner ball having a PGA compression of 100 or less. It is found that when the inner ball has a PGA compression of 90 or less, excellent playability results .
• the inner layer compositions include the high acid lonomers such as those developed by E.I. DuPont de Nemours & Company under the trademark “Surlyn ® " and by Exxon Corporation under the trademark “Escor ® “ or trade name “Iotek”, or blends thereof.
• Examples of compositions which may be used as the inner layer herein are set forth m detail m a continuation of U.S. Application Serial No. 08/174,765, which is a continuation of U.S. Application Serial No. 07/776,803 filed October 15, 1991, and Serial No. 08/493,089, which is a continuation of 07/981,751, which m turn is a continuation of Serial No. 07/901,660 filed June 19, 1992, all of which are incorporated herein by reference.
• the inner layer high acid ionomer compositions are not limited m any way to those compositions set forth m said applications.
• the high acid lonomers which may be suitable for use m formulating the inner layer compositions are ionic copolymers which are the metal, i.e., sodium, zmc, magnesium, etc., salts of the reaction product of an olefin having from about 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having from about 3 to 8 carbon atoms.
• the ionomeric resins are copolymers of ethylene and either acrylic or methacrylic acid.
• an additional comonomer such as an acrylate ester (i.e., iso- or n- butylacrylate , etc.) can also be included to produce a softer terpolymer.
• the carboxylic acid groups of the copolymer are partially neutralized (i.e., approximately 10-100%, preferably 30-70%) by the metal ions
• Each of the high acid ionomer resins which may be included m the inner layer cover compositions of the invention contains greater than about 16% by weight of a carboxylic acid, preferably from about 17% to about 25% by weight of a carboxylic acid, more preferably from about 18.5% to about 21.5% by weight of a carboxylic acid.
• the inner layer cover composition of several embodiments of the present invention preferably includes a high acid ionomeric resin
• the scope of the patent embraces all known high acid ionomeric resins falling within the parameters set forth above, only a relatively limited number of these high acid ionomeric resins have recently become commercially available.
• Examples of the high acid methacrylic acid based ionomers found suitable for use in accordance with this invention include Surlyn ® 8220 and 8240 (both formerly known as forms of Surlyn AD-8422) , Surlyn ® 9220 (zinc cation) , Surlyn ® SEP-503 -1 (zinc cation) , and Surlyn ® SEP-503-2 (magnesium cation) . According to DuPont, all of these ionomers contain from about 18.5 to about 21.5% by weight methacrylic acid.
• Surlyn ® AD-8422 is currently commercially available from DuPont in a number of different grades (i.e., AD-8422-2, AD-8422-3, AD- 8422-5, etc.) based upon differences in melt index.
• Surlyn ® 8422 which is believed recently to have been redesignated as 8220 and 8240, offers the following general properties when compared to Surlyn ® 8920, the stiffest, hardest of all on the low acid grades (referred to as "hard” ionomers in U.S. Patent No. 4,884,814): - IS
• Surlyn ® 8920 contains 15 weight percent methacrylic acid and is 59% neutralized with sodium.
• Surlyn ® SEP-503-l zinc cation
• Surlyn ® SEP-503 -2 magnesium cation
• the Surlyn ® SEP-503-1 and SEP-503-2 ionomers can be defined as follows: Surlyn ® Ionomer Ion Melt Index Neutralization
• Surlyn ® 8162 is a zinc cation ionomer resin containing approximately 20% by weight (i.e., 18.5 - 21.5% weight) methacrylic acid copolymer that has been 30 - 70% neutralized.
• Surlyn ® 8162 is currently commercially available from DuPont.
• Examples of the high acid acrylic acid based ionomers suitable for use in the present invention also include the Escor ® or lotek high acid ethylene acrylic acid ionomers produced by Exxon such as Ex 1001, 1002, 959, 960, 989, 990, 1003, 1004, 993, 994.
• Escor ® or lotek 959 is a sodium ion neutralized ethylene-acrylic neutralized ethylene-acrylic acid copolymer.
• Ioteks 959 and 960 contain from about 19.0 to 21.0% by weight acrylic acid with approximately 30 to about 70 percent of the acid groups neutralized with sodium and zinc ions, respectively.
• the physical properties of these high acid acrylic acid based ionomers are set forth in Tables 1 and 2 as follows :
• a high acid copolymer i.e., a copolymer containing greater than 16% by weight acid, preferably from about 17 to about 25 weight percent acid, and more preferably about 20 weight percent acid
• a metal cation salt capable of ionizing or neutralizing the copolymer to the extent desired (i.e., from about 10% to 90%).
• the base copolymer is made up of greater than 16% by weight of an alpha, beta-unsaturated carboxylic acid and an alpha-olefin.
• a softening comonomer can be included in the copolymer.
• the alpha-olefin has from 2 to 10 carbon atoms and is preferably ethylene
• the unsaturated carboxylic acid is a carboxylic acid having from about 3 to 8 carbons. Examples of such acids include acrylic acid, methacrylic acid, ethacrylic acid, chloroacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, with acrylic acid being preferred.
• the softening comonomer that can be optionally included in the inner cover layer for the golf ball of the invention may be selected from the group consisting of vinyl esters of aliphatic carboxylic acids wherein the acids have 2 to 10 carb/n atoms, vinyl ethers wherein the alkyl groups contains 1 to 10 carbon atoms, and alkyl acrylates or methacrylates wherein the alkyl group contains 1 to 10 carbon atoms.
• Suitable softening comonomers include vinyl acetate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, or the like.
• examples of a number of copolymers suitable for use to produce the high acid ionomers included in the present invention include, but are not limited to, high acid embodiments of an ethylene/acrylic acid copolymer, an ethylene/methacrylic acid copolymer, an ethylene/itaconic acid copolymer, an ethylene/maleic acid copolymer, an ethylene/methacrylic acid/vinyl acetate copolymer, an ethylene/acrylic acid/vinyl alcohol copolymer, etc.
• the base copolymer broadly contains greater than 16% by weight unsaturated carboxylic acid, from about 39 to about 83% by weight ethylene and from 0 to about 40% by weight of a softening comonomer.
• the copolymer contains about 20% by weight unsaturated carboxylic acid and about 80% by weight ethylene.
• the copolymer contains about 20% acrylic acid with the remainder being ethylene .
• examples of the preferred high acid base copolymers which fulfill the criteria set forth above are a series of ethylene-acrylic copolymers which are commercially available from The Dow Chemical Company, Midland, Michigan, under the "Primacor" designation. These high acid base copolymers exhibit the typical properties set forth below m Table 3.
• this copolymer is the more preferred grade utilized m the invention.
• the metal cation salts utilized in the invention are those salts which provide the metal cations capable of neutralizing, to various extents, the carboxylic acid groups of the high acid copolymer. These include acetate, oxide or hydroxide salts of lithium, calcium, zinc, sodium, potassium, nickel, magnesium, and manganese.
• lithium ion sources are lithium hydroxide monohydrate, lithium hydroxide, lithium oxide and lithium acetate.
• Sources for the calcium ion include calcium hydroxide, calcium acetate and calcium oxide.
• suitable zinc ion sources are zmc acetate dihydrate and zmc acetate, a blend of zmc oxide and acetic acid.
• Examples of sodium ion sources are sodium hydroxide and sodium acetate.
• Sources for the potassium ion include potassium hydroxide and potassium acetate.
• Suitable nickel ion sources are nickel acetate, nickel oxide and nickel hydroxide.
• Sources of magnesium include magnesium oxide, magnesium hydroxide, magnesium acetate.
• Sources of manganese include manganese acetate and manganese oxide.
• the new metal cation neutralized high acid ionomer resins are produced by reacting the high acid base copolymer with various amounts of the metal cation salts above the crystalline melting point of the copolymer, such as at a temperature from about 200 °F to about 500°F, preferably from about 250 °F to about 350°F under high shear conditions at a pressure of from about 10 psi to 10,000 psi. Other well known blending techniques may also be used.
• the amount of metal cation salt utilized to produce the new metal cation neutralized high acid based ionomer resins is the quantity which provides a sufficient amount of the metal cations to neutralize the desired percentage of the carboxylic acid groups in the high acid copolymer.
• the extent of neutralization is generally from about 10% to about 90%.
• Control for Formulations 23-26 is 50/50 lotek 8000/7030
• the new metal cation neutralized high acid ionomer resms exhibit enhanced hardness, modulus and resilience characteristics. These are properties that are particularly desirable m a number of thermoplastic fields, including the field of golf ball manufacturing.
• the new acrylic acid based high acid ionomers extend the range of hardness beyond that previously obtainable while maintaining the beneficial properties (i.e. durability, click, feel, etc.) of the softer low acid ionomer covered balls, such as balls produced utilizing the low acid ionomers disclosed m U.S. Patent Nos. 4,884,814 and 4,911,451.
• the low acid ionomers which may be suitable for use in formulating the inner layer compositions of several of the embodiments of the subject invention are ionic copolymers which are the metal, i.e., sodium, zinc, magnesium, etc., salts of the reaction product of an olefin having from about 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having from about 3 to 8 carbon atoms.
• the ionomeric resins are copolymers of ethylene and either acrylic or methacrylic acid.
• an additional comonomer such as an acrylate ester (i.e., iso- or n- butylacrylate, etc.) can also be included to produce a softer terpolymer.
• the carboxylic acid groups of the copolymer are partially neutralized (i.e., approximately
• each of the low acid ionomer resins which may be included in the inner layer cover compositions of the invention contains 16% by weight of less of a carboxylic acid.
• the inner layer compositions include the low acid ionomers such as those developed and sold by E.I. DuPont de Nemours & Company under the trademark “Surlyn ® " and by Exxon Corporation under the trademark “Escor ® “ or tradename "lotek,” or blends thereof.
• the low acid ionomer resins available from Exxon under the designation "Escor ® " and/or "lotek,” are somewhat similar to the low acid ionomeric resins available under the "Surlyn ® " trademark. However, since the Escor ® /Iotek ionomeric resins are sodium or zinc salts of poly (ethylene-acrylic acid) and the “Surlyn ® " resins are zinc, sodium, magnesium, etc. salts of poly (ethylene-methacrylic acid), distinct differences in properties exist .
• the low acid ionomer blends When utilized in the construction of the inner layer of a multi-layered golf ball, it has been found that the low acid ionomer blends extend the range of compression and spin rates beyond that previously obtainable. More preferably, it has been found that when two or more low acid ionomers, particularly blends of sodium and zinc ionomers, are processed to produce the covers of multi -layered golf balls, (i.e., the inner cover layer herein) the resulting golf balls will travel further and at an enhanced spin rate than previously known multi-layered golf balls. Such an improvement is particularly noticeable in enlarged or oversized golf balls.
• the use of an inner layer formulated from blends of lower acid ionomers produces multi-layer golf balls having enhanced compression and spin rates. These are the properties desired by the more skilled golfer.
• a blend of high and low acid ionomer resins is used. These can be the ionomer resins described above, combined in a weight ratio which preferably is within the range of 10:90 to 90:10 parts of high and low acid ionomer resins.
• a further additional embodiment of the inner cover layer is primarily based upon the use of a fully non-ionomeric thermoplastic material.
• Suitable non- ionomeric materials include metallocene catalyzed polyolefins or polyamides, polyamide/ionomer blends, polyphenylene ether/ionomer blends, etc., which have a shore D hardness of >60 and a flex modulus of greater than about 30,000 psi, or other hardness and flex modulus values which are comparable to the properties of the ionomers described above.
• Other suitable materials include but are not limited to thermoplastic or thermosetting polyurethanes, a polyester elastomer such as that marketed by DuPont under the trademark Hytrel ® , or a polyester amide such as that marketed by Elf Atochem S.A.
• Pebax ® a blend of two or more non-ionomeric thermoplastic elastomers, or a blend of one or more ionomers and one or more non- ionomeric thermoplastic elastomers. These materials can be blended with the ionomers described above in order to reduce cost relative to the use of higher quantities of ionomer.
• Outer Cover Layer 16 While the dual core component described below, and the hard inner cover layer formed thereon, provide the multi -layer golf ball with power and distance, the outer cover layer 16 is comparatively softer than the inner cover layer. The softness provides for the feel and playability characteristics typically associated with balata or balata-blend balls.
• the outer cover layer or ply is comprised of a relatively soft, low modulus (about 1,000 psi to about 10,100 psi) and, in an alternate embodiment, low acid (less than 16 weight percent acid) ionomer, an ionomer blend, a non-ionomeric thermoplastic or thermosetting material such as, but not limited to, a metallocene catalyzed polyolefin such as EXACT material available from EXXON, a polyurethane, a polyester elastomer such as that marketed by DuPont under the trademark Hytrel ® , or a polyester amide such as that marketed by Elf Atochem S.A.
• the outer layer is fairly thin (i.e. from about 0.010 to about 0.10 inches in thickness, more desirably 0.03 to 0.06 inches in thickness for a 1.680 inch ball and 0.04 to 0.07 inches in thickness for a 1.72 inch or more ball) , but thick enough to achieve desired playability characteristics while minimizing expense. Thickness is defined as the average thickness of the non-dimpled areas of the outer cover layer.
• the outer cover layer such as layer 16, 16 has a Shore D hardness of 55 or less, and more preferably 50 or less.
• the outer cover layer preferably is formed from an ionomer which constitutes at least 75 weight % of an acrylate ester-containing ionic copolymer or blend of acrylate ester-containing ionic copolymers .
• This type of outer cover layer in combination with the core and inner cover layer described above results in golf ball covers having a favorable combination of durability and spin rate.
• the one or more acrylate ester-containing ionic copolymers each contain an olefin, an acrylate ester, and an acid.
• each copolymer may contain the same or a different olefin, acrylate ester and acid than are contained in the other copolymers.
• the acrylate ester-containing ionic copolymer or copolymers are terpolymers, but additional monomers can be combined into the copolymers if the monomers do not substantially reduce the scuff resistance or other good playability properties of the cover.
• the olefin is selected from the group consisting of olefins having 2 to 8 carbon atoms, including, as non-limiting examples, ethylene, propylene, butene-1, hexene-1 and the like.
• olefin is ethylene.
• the acrylate ester is an unsaturated monomer having from 1 to 21 carbon atoms which serves as a softening comonomer.
• the acrylate ester preferably is methyl, ethyl, n-propyl, n-butyl, n-octyl, 2-ethylhexyl , or 2-methoxyethyl 1-acrylate, and most preferably is methyl acrylate or n-butyl acrylate .
• Another suitable type of softening comonomer is an alkyl vinyl ether selected from the group consisting of n-butyl, n-hexyl, 2-ethylhexyl , and 2-methoxyethyl vinyl ethers.
• the acid is a mono- or dicarboxylic acid and preferably is selected from the group consisting of methacrylic, acrylic, ethacrylic, ⁇ -chloroacrylic, crotonic, maleic, fumaric, and itaconic acid, or the like, and half esters of maleic, fumaric and itaconic acid, or the like.
• the acid group of the copolymer is 10-100% neutralized with any suitable cation, for example, zinc, sodium, magnesium, lithium, potassium, calcium, manganese, nickel, chromium, tin, aluminum, or the like. It has been found that particularly good results are obtained when the neutralization level is about 50-100%.
• the one or more acrylate ester-containing ionic copolymers each has an individual Shore D hardness of about 5-64.
• the overall Shore D hardness of the outer cover is 55 or less, and generally is 40-55. It is preferred that the overall Shore D hardness of the outer cover is in the range of 40-50 in order to impart particularly good playability characteristics to the ball.
• the outer cover layer of the invention is formed over a core to result in a golf ball having a coefficient of restitution of at least 0.770, more preferably at least 0.780, and most preferably at least 0.790.
• the coefficient of restitution of the ball will depend upon the properties of both the core and the cover.
• the PGA compression of the golf ball is 100 or less, and preferably is 90 or less.
• the acrylate ester-containing ionic copolymer or copolymers used in the outer cover layer can be obtained by neutralizing commercially available acrylate ester-containing acid copolymers such as polyethylene- methyl acrylate-acrylic acid terpolymers, including ESCOR ATX (Exxon Chemical Company) or poly (ethylene- butyl acrylate-methacrylic acid) terpolymers, including NUCREL (DuPont Chemical Company) .
• Particularly preferred commercially available materials include ATX 320, ATX 325, ATX 310, ATX 350, and blends of these materials with NUCREL 010 and NUCREL 035.
• the acid groups of these materials and blends are neutralized with one or more of various cation salts including zinc, sodium, magnesium, lithium, potassium, calcium, manganese, nickel, etc.
• the degree of neutralization ranges from 10-100%. Generally, a higher degree of neutralization results in a harder and tougher cover material.
• the properties of non-limiting examples of commercially available un-neutralized acid terpolymers which can be used to form the golf ball outer cover layers of the invention are provided below in Table 5.
• the ionomer resins used to form the outer cover layers can be produced by reacting the acrylate ester-containing acid copolymer with various amounts of the metal cation salts at a temperature above the crystalline melting point of the copolymer, such as a temperature from about 200 °F to about 500 * F, preferably from about 250 °F to about 350 * F, under high shear conditions at a pressure of from about 100 psi to 10,000 psi .
• Other well known blending techniques may also be used.
• the amount of metal cation salt utilized to produce the neutralized ionic copolymers is the quantity which provides a sufficient amount of the metal cations to neutralize the desired percentage of the carboxylic acid groups in the high acid copolymer. When two or more different copolymers are to be used, the copolymers can be blended before or after neutralization.
• copolymers it is preferable to blend the copolymers before they are neutralized to provide for optimal mixing.
• the compatibility of the acrylate ester- containing copolymers with each other in a copolymer blend produces a golf ball outer cover layer having a surprisingly good scuff resistance for a given hardness of the outer cover layer.
• the golf ball according to the invention has a scuff resistance of no higher than 3.0. It is preferred that the golf ball has a scuff resistance of no higher than about 2.5 to ensure that the golf ball is scuff resistant when used in conjunction with a variety of types of clubs, including sharp-grooved irons, which are particularly inclined to result in scuffing of golf ball covers.
• the best results according to the invention are obtained when the outer cover layer has a scuff resistance of no more than about 2.0.
• Additional materials may also be added to the inner and outer cover layer of the present invention as long as they do not substantially reduce the playability properties of the ball.
• Such materials include dyes
• cover compositions of the present invention may also contain softening agents such as those disclosed in U.S. Patent Nos. 5,312,857 and 5,306,760, including plasticizers, metal stearates, processing acids, etc., and reinforcing materials such as glass fibers and inorganic fillers, as long as the desired properties produced by the golf ball covers of the invention are not impaired.
• the outer layer in another embodiment of the invention includes a blend of a soft (low acid) ionomer resin with a small amount of a hard (high acid) ionomer resin.
• a low modulus ionomer suitable for use in the outer layer blend has a flexural modulus measuring from about 1,000 to about 10,000 psi, with a hardness of about 20 to about 40 on the Shore D scale.
• a high modulus ionomer herein is one which measures from about 15,000 to about 70,000 psi as measured in accordance with ASTM method D-790.
• the hardness may be defined as at least 50 on the Shore D scale as measured in accordance with ASTM method D-2240.
• Soft ionomers primarily are used in formulating the hard/soft blends of the cover compositions. These ionomers include acrylic acid and methacrylic acid based soft ionomers. They are generally characterized as comprising sodium, zinc, or other mono- or divalent metal cation salts of a terpolymer of an olefin having from about 2 to 8 carbon atoms, methacrylic acid, acrylic acid, or another, , ⁇ - unsaturated carboxylic acid, and an unsaturated monomer of the acrylate ester class having from 1 to 21 carbon atoms.
• the soft ionomer is preferably made from an acrylic acid base polymer is an unsaturated monomer of the acrylate ester class.
• Certain ethylene-acrylic acid based soft ionomer resins developed by the Exxon Corporation under the designation "lotek 7520" may be combined with known hard ionomers such as those indicated above to produce the inner and outer cover layers .
• the combination produces higher C.O.R. s at equal or softer hardness, higher melt flow (which corresponds to improved, more efficient molding, i.e., fewer rejects] as well as significant cost savings versus the outer layer of multi-layer balls produced by other known hard- soft ionomer blends as a result of the lower overall raw materials cost and improved yields.
• test data collected by the inventor indicates that lotek 7520 resins have Short D hardnesses of about 32 to 36 (per ASTM D-2240) , melt flow indexes of 3 ⁇ 0.5 g/10 min (at 190 °C. per ASTM D- 1288) , and a flexural modulus of about 2500 - 3500 psi (per ASTM D-790) .
• testing by an independent testing laboratory by pyrolysis mass spectrometry indicates at lotek 7520 resins are generally zinc salts of a terpolymer of ethylene, acrylic acid, and methyl acrylate.
• lotek 7510 has the advantages (i.e. improved flow, higher C.O.R. values at equal hardness, increased clarity, etc.) produced by the lotek 7520 resin when compared to the methacrylic acid base soft ionomers known in the art (such as the Surlyn ® 8625 and Surlyn ® 8629 combinations disclosed in U.S. Patent No. 4,8884,814).
• lotek 7510 when compared to lotek 7520, produces slightly higher C.O.R. values at equal softness/hardness due to the lotek 7510 's higher hardness and neutralization. Similarly, lotek 7510 produces better release properties (from the mold cavities) due to its slightly higher stiffness and lower flow rate than lotek 7520. This is important in production where the soft covered balls tend to have lower yields caused by sticking in the molds and subsequent punched pin marks from the knockouts.
• lotek 7510 is of similar chemical composition as lotek 7520 (i.e. a zinc salt of a terpolymer of ethylene, acrylic acid, and methyl acrylate) but is more highly neutralized. Based upon
• lotek 7520 is estimated to be about 30-40 wt.-% neutralized and lotek 7510 is estimated to be about 40-60 wt.-% neutralized.
• the typical properties of lotek 7510 in comparison of those of lotek 7520 in comparison of those of lotek 7520 are set forth below: TABLE 7
• the hard ionomer resins utilized to produce the outer cover layer composition hard/soft blends include ionic copolymers which are the sodium, zinc, magnesium, lithium, etc. salts of the reaction product of an olefin having from 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having from 3 to 8 carbon atoms.
• the carboxylic acid groups of the copolymer may be totally or partially (i.e. approximately 15-75 percent) neutralized.
• the hard ionomeric resins are likely copolymers of ethylene and acrylic and/or methacrylic acid, with copolymers of ethylene and acrylic acid being the most preferred. Two or more types of hard ionomeric resins may be blended into the outer cover layer compositions in order to produce the desired properties of the resulting golf balls. As discussed earlier herein, the hard ionomeric resins introduced under the designation Escor ® and sold under the designation "lotek" are somewhat similar to the hard ionomeric resins sold under the Surlyn ® trademark.
• the "lotek” ionomeric resins are sodium or zinc salts of poly (ethylene-acrylic acid) and the Surlyn ® resins are zinc or sodium salts of poly (ethylene-methacrylic acid) some distinct differences in properties exist.
• the hard "lotek” resins i.e., the acrylic acid based hard ionomer resins
• the acrylic acid based hard ionomer resins are the more preferred hard resins for use in formulating the outer layer blends for use in the present invention.
• various blends of "lotek” and Surlyn ® hard ionomeric resins, as well as other available ionomeric resins may be utilized in the present invention in a similar manner.
• Examples of commercially available hard ionomeric resins which may be used in the present invention in formulating the outer cover blends include the hard sodium ionic copolymer sold under the trademark Surlyn ® 8940 and the hard zinc ionic copolymer sold under the trademark Surlyn ® 9910.
• Surlyn ® 8940 is a copolymer of ethylene with methacrylic acid and about 15 weight percent acid which is about 29 percent neutralized with sodium ions. this resin has an average melt flow index of about 2.8.
• Surlyn ® 9910 is a copolymer of ethylene and methacrylic acid with about 15 weight percent acid which is about 58 percent neutralized with zinc ions.
• the average melt flow index of Surlyn ® 9910 is about 0.7.
• the typical properties of Surlyn ® 9910 and 8940 are set forth below in Table 8:
• Examples of the more pertinent acrylic acid based hard ionomer resin suitable for use in the present outer cover composition sold under the "lotek" trade name by the Exxon Corporation include lotek 8000, 8010, 8020, 8030, 7030, 7010, 7020, 1002, 1003, 959 and 960.
• the physical properties of lotek 959 and 960 are shown above.
• the typical properties of the remainder of these and other lotek hard ionomers suited for use in formulating the outer layer cover composition are set forth below in Table 9 :
• the outer cover layer formulation may also comprise up to 100 wt % of a soft, low modulus non- ionomeric thermoplastic material including a polyester polyurethane such as B.F. Goodrich Company's Estane ® polyester polyurethane X-4517.
• the non-ionomeric thermoplastic material may be blended with a soft ionomer.
• polyamides blend well with soft ionomer.
• Estane ® X-4517 has the following properties:
• thermoplastic polyurethanes such as Texin thermoplastic polyurethanes from Mobay Chemical Co. and the Pellethane thermoplastic polyurethanes from Dow Chemical Co.
• non- ionomeric thermoset polyurethanes including but not limited to those disclosed in U.S.
• Patent 5,334,673 cross-linked metallocene catalyzed polyolefins; ionomer/rubber blends such as those in Spalding U.S. Patents 4,986,545; 5,098,105 and 5,187,013; and, Hytrel polyester elastomers from DuPont and Pebax polyesteramides from Elf Atochem S.A.
• the present invention golf balls utilize a unique dual core configuration.
• the cores comprise (i) an interior spherical center component formed from a thermoset material, a thermoplastic material, or combinations thereof and (ii) a core layer disposed about the spherical center component, the core layer formed from a thermoset material, a thermoplastic material, or combinations thereof.
• the core layer is disposed immediately adjacent to, and in intimate contact with the center component.
• the cores may further comprise (iii) an optional outer core layer disposed about the core layer.
• the outer core layer is disposed immediately adjacent to, and in intimate contact with the core layer.
• the outer core layer may be formed from a thermoset material, a thermoplastic material, or combinations thereof.
• a preferred embodiment golf ball 35 is illustrated comprising a core 30 formed from a thermoset material surrounded by a core layer 32 formed from a thermoplastic material.
• a multi-layer cover 34 surrounds the core 30 and core layer 32.
• the multilayer cover 34 preferably corresponds to the previously described multi-layer cover 12.
• another preferred embodiment golf ball 45 in accordance with the present invention is illustrated.
• the preferred embodiment golf ball 45 comprises a core 40 formed from a thermoplastic material surrounded by a core layer 42.
• the core layer 42 is formed from a thermoset material.
• a multi-layer cover 44 surrounds the core 40 and the core layer 42. Again, the multi-layer cover 44 preferably corresponds to the previously described multi-layer cover 12.
• FIGURE 5 illustrates yet another preferred embodiment golf ball 55 in accordance with the present invention.
• the preferred embodiment golf ball 55 comprises a core 50 formed from a thermoplastic material.
• a core layer 52 surrounds the core 50.
• the core layer 52 is formed from a thermoplastic material which may be the same as the material utilized with the core 50, or one or more other or different thermoplastic materials.
• the preferred embodiment golf ball 55 utilizes an optional outer core layer 54 that surrounds the core component 50 and the core layer 52.
• the outer core layer 54 is formed from a thermoplastic material which may be the same or different than any of the thermoplastic materials utilized by the core 50 and the core layer 52.
• the golf ball 55 further comprises a multi-layer cover 56 that is preferably similar to the previously described multi-layer cover 12.
• FIGURE 6 illustrates yet another preferred embodiment golf ball 65 in accordance with the present invention.
• the preferred embodiment golf ball 65 comprises a core 60 formed from a thermoplastic, thermoset material, or any combination of a thermoset and thermoplastic material.
• a core layer 62 surrounds the core 60.
• the core layer 62 is formed from a thermoset material.
• the preferred embodiment golf ball 65 also comprises an optional outer core layer 64 formed from a thermoplastic material.
• a multi -layer cover 66 preferably similar to the previously described multilayer cover 12, is disposed about, and generally surrounds, the core 60, the core layer 62 and the outer core 64.
• thermoset materials can be utilized in the present invention dual cores.
• suitable thermoset materials include butadiene or any natural or synthetic elastomer, including metallocene polyolefins, polyurethanes, silicones, polyamides, polyureas, or virtually any irreversibly cross-linked resin system. It is also contemplated that epoxy, phenolic, and an array of unsaturated polyester resins could be utilized.
• thermoplastic material utilized in the present invention golf balls and, particularly their dual cores may be nearly any thermoplastic material.
• typical thermoplastic materials for incorporation in the golf balls of the present invention include, but are not limited to, ionomers, polyurethane thermoplastic elastomers, and combinations thereof.
• thermoplastic materials such as polysulfones, fluoropolymers, polyamide- imides , polyarylates , polyaryletherketones, polyaryl sulfones/polyether sulfones, polybenzimidazoles , polyether- imides, polyimides, liquid crystal polymers, polyphenylene sulfides; and specialty high-performance resins, which would include fluoropolymers, polybenzimidazole, and ultrahigh molecular weight polyethylenes .
• thermoplastics include metallocenes, polyvinyl chlorides, acrylonitrile-butadiene-styrenes, acrylics, styrene- acrylonitriles, styrene-maleic anhydrides, polyamides (nylons), polycarbonates, polybutylene terephthalates, polyethylene terephthalates, polyphenylene ethers/polyphenylene oxides, reinforced polypropylenes , and high-impact polystyrenes.
• the thermoplastic materials have relatively high melting points, such as a melting point of at least about 300°F.
• thermoplastic materials include, but are not limited to, Capron (a blend of nylon and ionomer) , Lexan polycarbonate, Pebax, and Hytrel.
• Capron a blend of nylon and ionomer
• Lexan polycarbonate a polycarbonate
• Pebax a polycarbonate
• Hytrel a polycarbonate
• the polymers or resin system may be cross- linked by a variety of means such as by peroxide agents, sulphur agents, radiation or other cross-linking techniques.
• any or all of the previously described components in the cores of the golf ball of the present invention may be formed in such a manner, or have suitable fillers added, so that their resulting density is decreased or increased.
• any of these components in the dual cores could be formed or otherwise produced to be light in weight.
• the components could be foamed, either separately or in- situ.
• a foamed light weight filler agent may be added.
• any of these components could be mixed with or otherwise receive various high density filler agents or other weighting components such as relatively high density fibers or particulate agents in order to increase their mass or weight.
• thermoplastic resins are particularly preferred for use in the noted dual cores employed in the golf balls of the present invention: Capron 8351 (available from Allied Signal Plastics) , Lexan ML5776 (from General
• the cores of the inventive golf balls typically have a coefficient of restitution of about 0.750 or more, more preferably 0.770 or more and a PGA compression of about 90 or less, and more preferably 70 or less.
• the cores have a weight of 25 -40 grams and preferably 30 - 40 grams.
• the core can be compression molded from a slug of uncured or lightly cured elastomer composition comprising a high cis content polybutadiene and a metal salt of an , ⁇ , ethylenically unsaturated carboxylic acid such as zinc mono- or diacrylate or methacrylate.
• the manufacturer may include a small amount of a metal oxide such as zinc oxide.
• metal oxide than are needed to achieve the desired coefficient may be included in order to increase the core weight so that the finished ball more closely approaches the U.S.G.A. upper weight limit of 1.620 ounces.
• Non-limiting examples of other materials which may be used in the core composition including compatible rubbers or ionomers, and low molecular weight fatty acids such as stearic acid. Free radical initiator catalysts such as peroxides are admixed with the core composition so that on the application of heat and pressure, a curing or cross-linking reaction takes place .
• Wound cores are generally produced by winding a very long elastic thread around a solid or liquid filled balloon center.
• the elastic thread is wound around the center to produce a finished core of about 1.4 to 1.6 inches in diameter, generally.
• the preferred embodiment golf balls of the present invention preferably utilize a solid core, or rather a solid dual core configuration, as opposed to a wound core.
• a hard inner cover layer is molded (by injection molding or by compression molding) about a core (preferably a solid core, and most preferably a dual core) .
• a comparatively softer outer layer is molded over the inner layer.
• the dual cores of the present invention are preferably formed by compression molding techniques.
• a preferred method of making the golf ball 45 depicted in FIGURE 4 is as follows. Specifically, a thermoset material, i.e. a core layer 42, is formed about an inner core component 40 comprising a thermoplastic material as follows: Referring to FIGURE 7, preforms 75 of a thermoset material, i.e. utilized to form the core layer 42, are preheated in an oven for one-half hour at 170°F and placed in the bottom 73 of a molding assembly 70. A Teflon-coated plate 76 with two hemispheres 77 and 78, each about 0.840 inches in diameter, is placed on top of the preforms.
• Additional preforms preheated as described above, are placed in the corresponding cavities of a top mold 72.
• the bottom mold 73 is engaged with the top mold 72 and the assembly flipped or otherwise inverted.
• the bottom one half of the mold assembly 70 then becomes the top one half of the mold assembly.
• the mold assembly 70 is then placed in a press and cold formed at room temperature using approximately 10 tons of pressure in a steam press.
• the molding assembly 70 is closed for approximately two minutes and pressure released.
• the molding assembly 70 is then opened and the Teflon plate 76 is removed thereby leaving one or more essentially perfectly formed one-half shells in cavities in the thermoset material.
• thermoplastic core centers are then placed in the bottom cavities and the top portion 72 of the molding assembly 70 is placed on the bottom 73 and the materials disposed therebetween cured.
• the golf ball produced by this method had an inner core diameter of 0.840 inches in diameter.
• the outer core diameter had a final diameter of 1.470 inches, and a pre-mold diameter of 1.490 inches.
• a relatively hard inner cover layer is then molded about the resulting dual core component.
• the diameter of the inner cover was 1.570 inches.
• a comparatively softer outer cover layer is then molded about the inner cover layer.
• the outer cover diameter was 1.680 inches. Details of molding the inner and outer covers are set forth below.
• Inner Core size (inches) 0.835 0.854 0.840 0.831 — weight (grams) 5.33 6.14 5.08 5.81 rebound %(100") 78 83 65 61
• the inner cover layer which is molded over the core, or preferably a dual core component is about 0.01 inches to about 0.10 inches in thickness, preferably about 0.03-0.07 inches thick.
• the inner ball which includes the core and inner cover layer preferably has a diameter in the range of 1.25 to 1.60 inches.
• the outer cover layer is about 0.01 inches to about 0.10 inches in thickness.
• the resulting golf balls in accordance with the present invention have the following dimensions :
• the golf ball has a dimple pattern which provides coverage of 65% or more.
• the golf ball typically is coated with a durable, abrasion-resistant, relatively non-yellowing finish coat.
• the various cover composition layers of the present invention may be produced according to conventional melt blending procedures.
• the copolymer resins are blended in a Banbury type mixer, two-roll mill, or extruder prior to neutralization. After blending, neutralization then occurs in the melt or molten states in the banbury mixer. Mixing problems are minimal because preferably more than 75 wt %, and more preferably at least 80 wt % of the ionic copolymers in the mixture contain acrylate esters and, in this respect, most of the polymer chains in the mixture are similar to each other.
• the blended composition is then formed into slabs, pellets, etc., and maintained in such a state until molding is desired.
• a simple dry blend of the pelletized or granulated resins which have previously been neutralized to a desired extent and colored masterbatch may be prepared and fed directly into the injection molding machine where homogenization occurs in the mixing section of the barrel prior to injection into the mold. If necessary, further additives such as an inorganic filler, etc., may be added and uniformly mixed before initiation of the molding process.
• a similar process is utilized to formulate the high acid ionomer resin compositions used to produce the inner cover layer.
• a masterbatch of non-acrylate ester-containing ionomer with pigments and other additives incorporated therein is mixed with the acrylate ester-containing copolymers in a ratio of about 1 - 7 weight % masterbatch and 93 - 99 weight % acrylate ester-containing copolymer.
• the golf balls of the present invention can be produced by molding processes which include but are not limited to those which are currently well known in the golf ball art.
• the golf balls can be produced by injection molding or compression molding the novel cover compositions around a wound or solid molded core to produce an inner ball which typically has a diameter of about 1.50 to 1.67 inches.
• the core preferably of a dual core configuration, may be formed as previously described.
• the outer layer is subsequently molded over the inner layer to produce a golf ball having a diameter of 1.620 inches or more, preferably about 1.680 inches or more.
• solid cores or wound cores can be used in the present invention, as a result of their lower cost and superior performance solid molded cores are preferred over wound cores.
• the standards for both the minimum diameter and maximum weight of the balls are established by the United States Golf Association (U.S.G.A.).
• the inner cover composition is formed via injection at about 380°F to about 450°F into smooth surfaced hemispherical shells which are then positioned around the core in a mold having the desired inner cover thickness and subjected to compression molding at 200° to 300°F for about 2 to 10 minutes, followed by cooling at 50° to 70 °F for about 2 to 7 minutes to fuse the shells together to form a unitary intermediate ball.
• the intermediate balls may be produced by injection molding wherein the inner cover layer is injected directly around the core placed at the center of an intermediate ball mold for a period of time in a mold temperature of from 50° to about 100°F. Subsequently, the outer cover layer is molded around the core and the inner layer by similar compression or injection molding techniques to form a dimpled golf ball of a diameter of 1.680 inches or more.
• the golf balls produced may undergo various further processing steps such as buffing, painting and marking as disclosed in U.S. Patent No. 4,911,451.
• the resulting golf ball produced from the hard inner layer and the relatively softer, low flexural modulus outer layer provide for an improved multi-layer golf ball having a unique dual core configuration which provides for desirable coefficient of restitution and durability properties while at the same time offering the feel and spin characteristics associated with soft balata and balata- like covers of the prior art.

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• 1998
  • 1998-03-27 CA CA002283788A patent/CA2283788A1/en not_active Abandoned
  • 1998-03-27 GB GB9922129A patent/GB2338422A/en not_active Withdrawn
  • 1998-03-27 JP JP54187198A patent/JP2002510990A/ja active Pending
  • 1998-03-27 AU AU67840/98A patent/AU730113B2/en not_active Ceased
  • 1998-03-27 WO PCT/US1998/006159 patent/WO1998043709A1/en active IP Right Grant

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