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
  • C08L23/025—Copolymers of unspecified olefins with monomers other than olefins
• • 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
  • A63B37/12—Special coverings, i.e. outer layer material
• • 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
  • 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
  • A63B37/005—Cores
  • A63B37/006—Physical properties
  • A63B37/0061—Coefficient of restitution
• • 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
  • A63B37/005—Cores
  • A63B37/006—Physical properties
  • A63B37/0065—Deflection or compression
• • 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
• • 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
  • A63B37/0076—Multi-piece balls, i.e. having two or more intermediate layers
• • 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 atoms other than carbon or hydrogen
  • C08L23/0869—Copolymers of ethene with unsaturated hydrocarbons containing atoms other than carbon or hydrogen with unsaturated acids, e.g. [meth]acrylic acid; with unsaturated esters, e.g. [meth]acrylic acid esters
  • C08L23/0876—Salts thereof, i.e. ionomers

Definitions

• the present invention relates generally to golf balls, and more particularly to golf balls having relatively thick multi-layer covers that are durable and resistant to cracks and fractures.
• the present invention relates to golf balls having multi-layer covers in which each of the individual cover layers have the same, or similar, hardness.
• the present invention relates to golf balls exhibiting particular PGA compression values.
• the present invention relates to golf balls having cores with certain coefficient of restitution values that are matched with such values of other components in the balls such that the difference between the overall coefficient of restitution of the ball and the coefficient of restitution of the core is relatively small.
• Top grade golf balls sold in the United States generally comprise a central core with one or more cover layers formed thereover.
• a golf ball cover is particularly influential in effecting the compression (feel) and durability (i.e., impact resistance, etc.) of the resulting ball.
• Various cover compositions have been developed in order to optimize desired properties of the resulting golf balls.
• Figs. 1 and 2 illustrate a conventional golf ball 1 0 having a single cover layer 1 4 molded about a golf ball core 1 6.
• Fig. 2 illustrates (in an exaggerated view) stress lines 1 2 extending partially, or entirely across the thickness of the cover layer 1 4. Stress lines 1 2 typically result in a crack or fracture across the thickness of the golf ball cover.
• Figs. 1 and 2 illustrate one problem that may occur when a very thick, single layer cover is formed about a golf ball core.
• each cover layer traditionally has had a significantly different Shore D hardness than an adjacent cover layer in order to impart to the golf ball a particular desired combination of spin and distance characteristics.
• a multi-layer cover configuration reduces the tendency of stress lines, and thus cracks and fractures, propagating across the entire thickness of the cover
• such multi-layer arrangement of cover materials, each having its own particular set of properties and characteristics has associated design and manufacturing problems. For instance, in order to produce a multiple cover layer golf ball that exhibits a desired set of performance characteristics, it is necessary to design and anticipate an overall performance profile for the set of cover layers. This involves analyzing each of the individual cover layers and any and all effects between the individual cover layers.
• an object of the present invention is to provide a multi-layer golf ball with a durable, and preferably thick, cover
• the multi-layers provide better durability by minimizing crack initiation or propagation through the formation of knit-lines
• the cover layers may be of the same or different composition, but of similar hardness
• Another object of the invention is to provide a multi-layer golf ball having thick cover layers (i.e. overall cover thickness of at least 3.6 mm, 0 1 42 inches) exhibiting similar hardnesses
• the multi-layer cover functions in a manner to produce superior durability.
• the cores of the golf ball can be solid, can be comprised of two or more layers, and can consist of thermoset or thermoplastic materials. Alternatively, cores can be wound, consisting of solid or liquid centers.
• One or more of the core and/or cover layers can contain a density reducing or increasing filler material.
• a further object of the invention is to provide a golf ball having improved distance than conventional golf balls with a comparable coefficient of restitution (i.e. , C.O. R.) .
• Yet another object of the present invention is to provide a golf ball having a low spin rate and excellent distance on full shots, combined with a soft feel when the ball is used for chipping and putting.
• Yet a further object of the invention is to provide methods of making golf balls of the type described above.
• the present invention provides a golf ball including a solid core having a coefficient of restitution of at least about 0.650, and a multi-layer cover having a thickness of at least about 3.6 mm (0. 142 inches) and a Shore D hardness of at least about 60.
• the present invention golf ball includes a core comprising one or both polybutadiene and natural rubber, such that the core has a coefficient of restitution of at least about 0.650.
• the golf ball also comprises a cover including an ionomer and having a thickness of at least 3.8 mm (0.1 50 inches) and a Shore D hardness of at least 60, such that the ball exhibits a coefficient of restitution of at least 0.770.
• the present invention in a preferred form provides a golf ball comprising a core and a first cover layer comprising a resin composition and at least one part by weight of a filler material.
• the first cover layer surrounds the core.
• the golf ball further comprises a second cover layer comprising a resin composition surrounding the first cover layer, the second cover layer having a different overall composition than the first cover layer.
• the difference between the Shore D hardness of the first cover layer and the Shore D hardness of the second cover layer is 2 or less.
• Another preferred form of the invention is a method of making a golf ball. The method comprises the steps of obtaining a golf ball core, forming a first cover layer over the core, and forming a second cover layer around and in contact with the first cover layer.
• the cover materials are selected and layers formed such that the difference between the Shore D hardness of the first cover layer and the Shore D hardness of the second cover layer is 2 or less.
• Figure 1 is a perspective view of a conventional single cover layer golf ball.
• Figure 2 is a partial cross sectional view of the golf ball depicted in Figure 1 , taken across line 2-2, illustrating stress lines extending partially or entirely across the thickness of the golf ball cover.
• Figure 3 is a partial cross section of a solid golf ball with a dual layer cover according to the present invention.
• Figure 4 is a partial cross section of a solid golf ball with a three layer cover according to an alternative embodiment of the present invention.
• the present invention generally provides a golf ball having a multiple layer cover in which one or more properties of each of the individual cover layers are matched so that certain desired properties are the same, or substantially so.
• the individual cover layers all have the same, or nearly the same, Shore D hardness.
• the present invention includes matching of one or more further properties or characteristics of individual cover layers in a multiple cover layer assembly utilized in a golf ball.
• the present invention is embodied in golf balls having multi-layer cover assemblies comprising two, three, or more cover layers.
• the golf ball of the present invention has a solid core having a coefficient of restitution (COR) of at least about 0.650 in combination with a thick, relatively hard cover assembly which is formed from two or more layers.
• Each cover layer has a Shore D hardness within 5 points, and preferably within 2 points, of the Shore D hardness of all other cover layers.
• the golf ball 20 has a core 26.
• the core 26 can consist of a solid or wound core and can consist of one or more layers.
• a multi-layer cover surrounds the core 26.
• the multi-layer cover includes a non-dimpled inner cover layer 24 and a dimpled outer cover layer 22.
• the outer cover layer 22 defines a plurality of dimples 27 and an outer surface 28 to form an unfinished golf ball.
• a thin primer coat (not shown) is applied to the outer surface of cover layer 22.
• a thin top coat (not shown) surrounds the primer coat to form a finished ball.
• one or more pigmented paint coat(s) can be substituted for the primer coat and/or top coat.
• the core 26 is relatively soft, with a PGA compression of about 85 or less, preferably about 20 to 85, and more preferably about 40 to 60.
• PGA compression is described and defined herein below.
• the multi-layer cover has a thickness of at least about 3.6 mm (0.142 inches) . It is particularly preferred that the cover thickness be at least 3.8 mm (0.1 50 inches) . Particularly good results are obtained when the cover has a thickness of at least 4.0 mm (0.1 57 inches) . In certain circumstances, such as when a harder compression and harder feel may be desired, it is useful to employ a cover having a thickness of at least 4.5 mm (0. 1 77 inches) .
• the thickness of the individual cover layers may vary depending upon the thicknesses of the other cover layers and the desired overall cover layer thickness. It may, in some applications, be desirable to form the outermost cover layer to be relatively thick due to the presence of the dimples.
• all cover thickness is the thickness of the multi-layer cover as measured from the inner diameter of the innermost cover to the outer surface of the outermost or exterior cover at a land (i.e. non-dimpled) area.
• cover layer thickness of any particular cover layer is the thickness of the layer from its inner diameter to its outer surface. If the outer surface of the layer is dimpled, the measurement is made to a land area of the cover layer.
• the preferred golf ball of the present invention preferably exhibits a difference between the coefficient of restitution of the ball and the coefficient of restitution of the core of at least about 0.025, preferably at least 0.035, and more preferably at least 0.045.
• the golf balls exhibit an unexpectedly long distance upon impact or drives given their coefficient of restitution.
• each layer of the multi-layer cover assembly has a Shore D hardness of 60 to 80, more preferably 62 to 75, and most preferably 65 to 70.
• the golf balls of the present invention can be produced by molding processes currently well known in the golf ball art. Specifically, the golf balls can be produced by injection molding or compression molding the novel cover compositions about wound or solid molded cores to produce a golf ball having a diameter of about 1 .680 to about 1 .800 inches and weighing about 1 .620 ounces.
• the standards for both the minimum diameter and maximum weight of the balls have been established by the United States Golf Association (U.S.G.A.) .
• solid cores refers not only to one piece cores but also to those cores having a separate solid layer beneath the cover and above the core as in U.S. Patent No. 4,431 , 1 93, and other multi-layer and/or non-wound cores.
• suitable cores that can be incorporated into the present invention are presented in more detail below.
• the layers of the multi-layer cover may be formed from generally the same resin composition, or may be formed from different resin compositions with similar hardnesses.
• one cover layer may be formed from an ionomeric resin of ethylene and methacryiic acid, while another layer is formed from an ionomer of ethylene and acrylic acid.
• One or more cover layers may contain polyamides or polyamide- nylon copolymers or intimate blends thereof.
• polyurethanes, Pebax, Hytrel, and/or thermosetting polyurethanes can be used.
• various colorants, metallic flakes, phosphorous, florescent dyes, florescent pigments, etc. can be incorporated in the resin.
• the various cover layers are made of at least 50 weight % ionomer based upon 1 00 parts by weight of resin composition, and more preferably 75 or more weight % ionomer. Additional description and details of suitable materials for cover layers are provided herein.
• cover materials for use as inner or outer cover layers include, for example, zinc, sodium and lithium ionomers, and blends of ionomers with harder non-ionic polymers such as nylon, polyphenylene oxide, metallocene catalyzed polyolefins, and other compatible thermoplastics.
• ionomers such as nylon, polyphenylene oxide, metallocene catalyzed polyolefins, and other compatible thermoplastics.
• nylon materials or blends thereof can be incorporated in the present invention golf ball covers. This is described in greater detail herein.
• various suitable ionomers are further described below.
• cover compositions which may be used are set forth in detail in copending U.S. Application Serial No. 08/596,690, which is a continuation of U.S. Application Serial No. 08/1 74,765, which in turn is a continuation of U.S.
• FIG. 4 A further embodiment of a golf ball according to the present invention is shown in Fig. 4, and is designated as golf ball 30
• the ball 30 has a core 38, as is illustrated in Fig. 3.
• the core 38 preferably has a PGA compression of about 85 or less, preferably 20 to 85, and more preferably 40 to 60.
• a multi-layer cover having three layers is formed over the core 38 to produce an unfinished golf ball.
• the cover includes an inner cover layer 36, an intermediate inner cover layer 34 and an outer cover layer 32.
• further finished coat(s) can be included to produce a finished golf bail.
• the inner, intermediate, and outer cover layers 36, 34 and 32 respectively preferably exhibit substantially the same Shore D hardness. Restated, the difference between the Shore D hardness of any two of these cover layers is preferably 5 or less, and most preferably is 2 or less.
• each of the cover layers 36, 34 and 32 has a Shore D hardness of 60 to 80, more preferably 62 to 75, and most preferably 65 to 70.
• the overall thickness of the multi-layer cover assembly shown in Fig 4 can be the same as the thickness of the multi-layer cover assembly of the embodiment of Fig. 3.
• the thickness of the individual cover layers may vary depending upon the thicknesses of the other cover layers and the desired overall cover layer thickness. It may, in some applications, be desirable to form the outermost cover layer to be relatively thick due to the presence of the dimples
• the three cover layers 36, 34 and 32 can be formed from the same or different resin compositions, and preferably comprise ionomer, ionomer blends, etc.
• Shore D hardness of a cover is measured generally in accordance with ASTM D-2240, except the measurements are made on the curved surface of a molded cover, rather than on a plaque. Furthermore, the Shore D hardness of the cover is measured while the cover remains over the core. When a hardness measurement is made on a dimpled cover, Shore D hardness is measured at a land area of the dimpled cover.
• C.O. R. Resilience
• club head speed and the angle of trajectory are factors not easily controllable by a manufacturer, factors of concern among manufacturers are the coefficient of restitution (C.O. R.) and the surface configuration of the ball.
• 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 center and cover, but also the composition and tension of the elastomeric windings.
• the coefficient of restitution is the ratio of the outgoing velocity to the incoming velocity.
• the coefficient of restitution of a golf ball was measured by propelling a ball horizontally at a speed of 1 25 ⁇ 1 feet per second (fps) against a generally vertical, hard, flat steel plate and measuring the ball's incoming and outgoing velocity electronically. Speeds were measured with a pair of Ohler Mark 55 ballistic screens, which provide a timing pulse when an object passes through them. The screens are separated by 36" and are located 25.25" and 61 .25" from the rebound wall.
• the ball speed was measured by timing the pulses from screen 1 to screen 2 on the way into the rebound wall (as the average speed of the ball over 36"), and then the exit speed was timed from screen 2 to screen 1 over the same distance.
• the rebound wall was tilted 2 degrees from a vertical plane to allow the ball to rebound slightly downward in order to miss the edge of the cannon that fired it.
• the incoming speed should be 1 25 + /- 1 fps. Furthermore, the correlation between COR and forward or incoming speed has been studied and a correction has been made over the + /- 1 fps range so that the COR is reported as if the ball had an incoming speed of exactly 1 25.0 fps.
• the coefficient of restitution must be carefully controlled in all commercial golf balls if the ball is 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 in an atmosphere of 75 ° F when tested on a U.S.G.A. machine. Since the coefficient of restitution of a ball is related to the ball's initial velocity, it is highly desirable to produce a ball having sufficiently high coefficient of restitution to closely approach the U.S.G.A. limit on initial velocity, while having an ample degree of softness (i.e. , hardness) to produce enhanced playabi ty (i.e. , spin, etc.)
• PGA compression is another important property involved in the performance of a golf ball.
• the compression of the ball can affect the playabihty of the ball on striking and the sound or "click” produced Similarly, compression can effect the "feel” of the ball (i.e., hard or soft responsive feel), particularly in chipping and putting.
• compression utilized in the golf ball trade generally defines the overall deflection that a golf ball undergoes when subjected to a compressive load .
• PGA compression indicates the amount of change in golf ball's shape upon striking
• PGA compression related to a scale of from 0 to 200 given to a golf ball.
• tournament quality balls have compression ratings around 70 to 1 1 0, and preferably around 80 to 1 00
• PGA compression In determining PGA compression using the 0 to 200 scale, a standard force is applied to the external surface of the ball. A ball which exhibits no deflection (0.0 inches in deflection) is rated 200 and a bail which deflects 2/1 Oth of an inch (0.2 inches) is rated 0 Every change of 0.001 of an inch in deflection represents a 1 point drop in compression Consequently, a ball which deflects 0.1 inches (100 x 0.001 inches) has a PGA compression value of 100 (i.e., 200 to 1 00) and a ball which deflects 0.1 1 0 inches ( 1 1 0 x 0.001 inches) has a PGA compression of 90
• PGA compression is determined by an apparatus fashioned in the form of a small press with an upper and lower anvil.
• the upper anvil is at rest against a 200-pound die spring, and the lower anvil is movable through 0.300 inches by means of a crank mechanism In its open position the gap between the anvils is 1 .780 inches allowing a clearance of 0.1 00 inches for insertion of the ball.
• the lower anvil is raised by the crank, it compresses the ball against the upper anvil, such compression occurring during the last 0.200 inches of stroke of the lower anvil, the ball then loading the upper anvil which in turn loads the spring.
• the equilibrium point of the upper anvil is measured by a dial micrometer if the anvil is deflected by the ball more than 0.1 00 inches (less deflection is simply regarded as zero compression) and the reading on the micrometer dial is referred to as the compression of the ball.
• tournament quality balls have compression ratings around 80 to 100 which means that the upper anvil was deflected a total of 0.1 20 to 0.1 00 inches.
• An example to determine PGA compression can be shown by utilizing a golf ball compression tester produced by Atti Engineering Corporation of Newark, N.J.
• the value obtained by this tester relates to an arbitrary value expressed by a number which may range from 0 to 1 00, although a value of 200 can be measured as indicated by two revolutions of the dial indicator on the apparatus.
• the value obtained defines the deflection that a golf ball undergoes when subjected to compressive loading.
• the Atti test apparatus consists of a lower movable platform and an upper movable spring-loaded anvil.
• the dial indicator is mounted such that it measures the upward movement of the spring- loaded anvil.
• the golf ball to be tested is placed in the lower platform, which is then raised a fixed distance.
• the upper portion of the golf ball comes in contact with and exerts a pressure on the spring-loaded anvil. Depending upon the distance of the golf ball to be compressed, the upper anvil is forced upward against the spring.
• Applicant also utilizes a modified Riehle Compression Machine originally produced by Riehle Bros. Testing Machine Company, Philadelphia, Pennsylvania to evaluate compression of the various components (i.e. , cores, mantle cover balls, finished balls, etc.) of the golf balls.
• the Riehle compression device determines deformation in thousandths of an inch under a fixed initialized load of 200 pounds. Using such a device, a Riehle compression of 61 corresponds to a deflection under load of 0.061 inches. Additionally, an approximate relationship between Riehle compression and PGA compression exists for balls of the same size.
• Riehle compression corresponds to PGA compression by the general formula PGA compression equals 1 60 minus Riehle compression. Consequently, 80 Riehle compression corresponds to 80 PGA compression, 70 Riehle compression corresponds to 90 PGA compression, and 60 Riehle compression corresponds to 100 PGA compression.
• Applicant's compression values are usually measured as Riehle compression and converted to PGA compression.
• additional compression devices may also be utilized to monitor golf ball compression so long as the correlation to PGA compression is known. These devices have been designed, such as a
• Whitney Tester to correlate or correspond to PGA compression through a set relationship or formula.
• the core which is used to form the golf balls of the present invention can be solid, foamed, wound, hollow or liquid
• the core can be unitary, or can have two or more core layers.
• a solid core or solid layer of a multi-layer core can be thermosetting or thermoplastic.
• the core is solid and is formed from a thermoset material
• Solid cores of the more preferred embodiment of the present invention can be manufactured using relatively conventional techniques.
• the core compositions of the invention may be based on polybutadiene, natural rubber, metallocene catalyzed polyolefins such as EXACT (Exxon Chem. Co.) and ENGAGE (Dow Chem.
• the core may be formed from a uniform composition or may be a dual or multi-layer core.
• the core may be foamed or unfoamed.
• the base elastomer have a relatively high molecular weight.
• Polybutadiene has been found to be particularly useful because it imparts to the golf balls a relatively high coefficient of restitution Polybutadiene can be cured using a free radical initiator such as a peroxide, or can be sulfur cured.
• a broad range for the molecular weight of preferred base elastomers is from about 50,000 to about 500,000 A more preferred range for the molecular weight of the base elastomer is from about 1 00,000 to about 500,000.
• c ⁇ s- 1 -4-polybutad ⁇ ene is preferably employed, or a blend of c ⁇ s- 1 -4-polybutad ⁇ ene with other elastomers may also be utilized.
• c ⁇ s-1 -4-polybutad ⁇ ene having a weight-average molecular weight of from about 1 00,000 to about 500,000 is employed.
• the core may be comprised of a crosslinked natural rubber, EPDM, metallocene catalyzed polyolefm, or another crosshnkable elastomer.
• the unsaturated carboxyiic acid component of the core composition typically is the reaction product of the selected carboxyiic acid or acids and an oxide or carbonate of a metal such as zinc, magnesium, barium, calcium, lithium, sodium, potassium, cadmium, lead, tin, and the like.
• a metal such as zinc, magnesium, barium, calcium, lithium, sodium, potassium, cadmium, lead, tin, and the like.
• the oxides of polyvalent metals such as zinc, magnesium and cadmium are used, and most preferably, the oxide is zinc oxide.
• the unsaturated carboxyiic acids which find utility in the core compositions are acrylic acid, methacryhc acid, itaconic acid, crotonic acid, sorbic acid, and the like, and mixtures thereof.
• the acid component is either acrylic or methacryhc acid.
• the carboxyiic acid salt such as zinc diacrylate.
• the unsaturated carboxyiic acids and metal salts thereof are generally soluble in the elastomeric base, or are readily dispersible.
• the free radical initiator included in the core composition is any known polymerization initiator (a co-crosshnking agent) which decomposes during the cure cycle.
• the term "free radical initiator” as used herein refers to a chemical which, when added to a mixture of the elastomeric blend and a metal salt of an unsaturated, carboxyiic acid, promotes crosshnking of the elastomers by the metal salt of the unsaturated carboxyiic acid.
• the amount of the selected initiator present is dictated only by the requirements of catalytic activity as a polymerization initiator. Suitable initiators include peroxides, persulfates, azo compounds and hydrazides.
• Peroxides which are readily commercially available are conveniently used in the present invention, generally in amounts of from about 0. 1 to about 1 0.0 and preferably in amounts of from about 0.3 to about 3.0 parts by weight per each 1 00 parts of elastomer.
• exemplary of suitable peroxides for the purposes of the present invention are dicumyl peroxide, n-butyl 4,4'-b ⁇ s (butylperoxy) valerate, 1 , 1 -b ⁇ s(t-butylperoxy)-3,3,5-tr ⁇ methyl cyclohexane, di-t-butyl peroxide and 2,5-d ⁇ -(t-butylperoxy)-2, 5 dimethyl hexane and the like, as well as mixtures thereof. It will be understood that the total amount of initiators used will vary depending on the specific end product desired and the particular initiators employed.
• Luperco 230 or 231 XL sold by Atochem, Lucidol Division, Buffalo, N.Y., and T ⁇ gonox 1 7/40 or 29/40 sold by Akzo Chemicals, America, Chicago, III.
• Luperco 230 XL and T ⁇ gonox 29/40 are comprised of
• the core compositions of the present invention may additionally contain any other suitable and compatible modifying ingredients including, but not limited to, metal oxides, fatty acids, and dnsocyanates and polypropylene powder resin.
• suitable and compatible modifying ingredients including, but not limited to, metal oxides, fatty acids, and dnsocyanates and polypropylene powder resin.
• Papi 94 a polymeric dnsocyanate, commonly available from Dow Chemical Co., Midland, Mich., is an optional component in the rubber compositions. It can range from about 0 to 5 parts by weight per 1 00 parts by weight rubber (phr) component, and acts as a moisture scavenger.
• phr a polypropylene powder resin results in a core which is hard (i.e. exhibits high PGA compression) and thus allows for a reduction in the amount of crosshnking co-agent utilized to soften the core to a normal or below normal compression.
• polypropylene powder resin can be added to a core composition without an increase in weight of the molded core upon curing, the addition of the polypropylene powder allows for the addition of higher specific gravity fillers, such as mineral fillers Since the crosshnking agents utilized in the polybutadiene core compositions are expensive and/or the higher specific gravity fillers are relatively inexpensive, the addition of the polypropylene powder resin substantially lowers the cost of the golf ball cores while maintaining, or lowering, weight and compression.
• the polypropylene (C 3 H 5 ) powder suitable for use in the present invention has a specific gravity of about 0.90 g/cm 3 , a melt flow rate of about 4 to about 1 2 and a particle size distribution of greater than 99% through a 20 mesh screen.
• polypropylene powder resins include those sold by the Amoco Chemical Co., Chicago, III., under the designations "6400 P", "7000 P” and "7200 P” .
• polypropylene powder resins include those sold by the Amoco Chemical Co., Chicago, III., under the designations "6400 P", "7000 P” and "7200 P” .
• polypropylene powder resins include those sold by the Amoco Chemical Co., Chicago, III., under the designations "6400 P", "7000 P” and "7200 P” .
• polypropylene powder resins include those sold by the Amoco Chemical Co., Chicago, III., under the designations "6400 P", "7000 P” and "7200 P”
• activators may also be included in the compositions of the present invention.
• zinc oxide and/or magnesium oxide are activators for the polybutadiene
• the activator can range from about 2 to about 30 parts by weight per 100 parts by weight of the rubbers (phr) component.
• reinforcement agents may be added to the core compositions of the present invention. Since the specific gravity of polypropylene powder is very low, and when compounded, the polypropylene powder produces a lighter molded core, when polypropylene is incorporated in the core compositions, relatively large amounts of higher specific gravity fillers may be added so long as the specific core weight limitations are met. As indicated above, additional benefits may be obtained by the incorporation of relatively large amounts of higher specific gravity, inexpensive mineral fillers such as calcium carbonate. Such fillers as are incorporated into the core compositions should be in finely divided form, as for example, in a size generally less than about 30 mesh and preferably less than about 1 00 mesh U.S.
• the amount of additional filler included in the core composition is primarily dictated by weight restrictions and preferably is included in amounts of from about 1 0 to about 1 00 parts by weight per 1 00 parts rubber.
• the preferred fillers are relatively inexpensive and heavy and serve to lower the cost of the ball and to increase the weight of the ball to closely approach the U.S.G.A. weight limit of 1 .620 ounces.
• thicker cover compositions are to be applied to the core to produce larger than normal (i.e. greater than 1 .680 inches in diameter) balls, use of such fillers and modifying agents will be limited in order to meet the U.S.G.A. maximum weight limitations of 1 .620 ounces.
• Limestone is ground calcium/magnesium carbonate and is used because it is an inexpensive, heavy filler.
• Ground flash filler may be incorporated and is preferably 20 mesh ground up center stock from the excess flash from compression molding. It lowers the cost and may increase the hardness of the ball.
• Fatty acids or metallic salts of fatty acids may also be included in the compositions, functioning to improve moldabihty and processing.
• free fatty acids having from abut 1 0 to about 40 carbon atoms, and preferably having from about 1 5 to about 1 0 carbon atoms, are used.
• suitable fatty acids are stearic acid and noleic acids, as well as mixtures thereof.
• An example of a suitable metallic salt of a fatty acid is zinc stearate.
• the metallic salts of fatty acids are present in amounts of from about 1 to about 25, preferably in amounts from about 2 to about 1 5 parts by weight based on 1 00 parts rubber (elastomer) It is preferred that the core compositions include stearic acid as the fatty acid adjunct in an amount of from about 2 to about 5 parts by weight per 100 parts of rubber
• Dnsocyanates may also be optionally included in the core compositions. When utilized, the dnsocyanates are included in amounts of from about 0.2 to about 5.0 parts by weight based on 1 00 parts rubber. Exemplary of suitable dnsocyanates is 4,4'-d ⁇ phenyimethane dnsocyanate and other polyfunctional isocyanates known in the art
• dialkyl tin difatty acids set forth in U.S. Patent No. 4,844,471
• dispensing agents disclosed in U.S. Patent No 4,838, 556 and the dithiocarbamates set forth in U.S. Patent No
• the core compositions of the invention which contain polybutadiene are generally comprised of 1 00 parts by weight of a base elastomer (or rubber) selected from polybutadiene and mixtures of polybutadiene with other elastomers, 1 5 to 25 parts by weight of at least one metallic salt of an unsaturated carboxyiic acid, and 0.5 to 1 0 parts by weight of a free radical initiator
• additional suitable and compatible modifying agents such as particulate polypropylene resin, fatty acids, and secondary additives such as pecan shell flour, ground flash (i.e. grindings from previously manufactured cores of substantially identical construction), barium sulfate, zinc oxide, etc. may be added to the core compositions to adjust the weight of the ball as necessary in order to have the finished molded ball (core, cover and coatings) to closely approach the U.S.G.A. weight limit of 1 .620 ounces.
• the ingredients may be intimately mixed using, for example, two roll mills or an internal mixer until the composition is uniform, usually over a period of from about 5 to about 20 minutes.
• the sequence of addition of components is not critical.
• a preferred blending sequence is as follows. The elastomer, polypropylene powder resin (if desired), fillers, zinc salt, metal oxide, fatty acid, and the metallic dithiocarbamate (if desired) , surfactant (if desired), and tin difatty acid (if desired), are blended for about 7 minutes in an internal mixer such as a Banbury ® (Farrel Corp.) mixer. As a result of shear during mixing, the temperature rises to about 200 ° F. The initiator and diisocyanate are then added and the mixing continued until the temperature reaches about 220 ° F whereupon the batch is discharged onto a two roll mill, mixed for about one minute and sheeted out.
• the sheet is rolled into a "pig” and then placed in a Barwell performer and slugs are produced.
• the slugs are then subjected to compression molding at about 320 ° F for about 14 minutes.
• the molded cores are cooled, the cooling effected at room temperature for about 4 hours or in cold water for about one hour.
• the molded cores can be subjected to a centerless grinding operation whereby a thin layer of the molded core is removed to produce a round core having a diameter of 1 .2 to 1 .5 inches.
• the cores are used in the as-molded state with no grinding needed to achieve roundness.
• the mixing is desirably conducted in such a manner that the composition does not reach incipient polymerization temperatures during the blending of the various components.
• the curable component of the composition will be cured by heating the composition at elevated temperatures on the order of from about 275 ° F to about 350 ° F, preferably and usually from about 290 ° F to about 325 ° F, with molding of the composition effected simultaneously with the curing thereof.
• the composition can be formed into a core structure by any one of a variety of molding techniques, e.g. injection, compression, or transfer molding.
• the time required for heating will normally be short, generally from about 1 0 to about 20 minutes, depending upon the particular curing agent used Those of ordinary skill in the art relating to free radical curing agents for polymers are conversant with adjustments of cure times and temperatures required to effect optimum results with any specific free radical agent.
• the core is removed from the mold and the surface thereof optionally is treated to facilitate adhesion thereof to the covering materials.
• Surface treatment can be effected by any of the several techniques known in the art, such as corona discharge, ozone treatment, sand blasting, and the like.
• surface treatment is effected by grinding with an abrasive wheel.
• wound cores may also be incorporated in the golf balls of the present invention.
• wound covers would include a generally spherical center and a rubber thread layer, or windings, enclosing the outer surface of the center.
• the generally spherical center of the wound cores may be a solid center or a liquid center.
• the solid center can consist of one or more layers.
• the solid center can comprise a molded polybutadiene rubber sphere which, although smaller in size, is of similar construction to the molded cores in the two-piece molded golf balls described above.
• Suitable solid centers used in the invention are not particularly limited to, but include those made of vulcanized rubber. Such solid centers may be prepared by adding to butadiene rubber, additives such as vulcanizing agents, accelerators, activating agents, fillers, modifiers and aids and then subjecting the mixture to vulcanization and molding
• the solid center (whether of single unitary construction or of multilayers) generally is from 1 to 1 .5 inches in diameter, preferably 1 0625 to 1 .42 inches, with a weight of 1 5 grams to 36 grams, preferably 1 6.5 to 30 grams.
• a liquid center can be incorporated into the wound core of the present invention.
• the liquid center consists of a hollow spherical bag or sack of conventional vulcanized rubber filled with a liquid, paste or gel.
• a liquid include water, glycerin, sugar-water solutions, corn-syrup, saline solutions, oils, etc. and/or combinations thereof.
• pastes can be produced by adding clay, sodium sulfate, barytes, barium sulfate to a minor amount of ethylene glycol in water.
• suitable gels include hydrogels, cellulose gels, water gels, etc.
• the specific gravity of the liquid is, in general, .6 to 3 and the specific gravity of the paste is from .6 to 3 and the gels from .6 to 3.
• the bag or sack is, in general, from 1.05" to .1 50" in thickness, preferably 0.08 to .1 05 inches in thickness.
• the liquid center generally is from 1 to 1 .25 inches in diameter, preferably 1 .0625 to 1 . 1 4 inches, with a weight of 5.5 to 25.5 grams, preferably 1 5 to 21 grams.
• the wound core is formed by winding conventional thread rubber around the outer periphery of the solid or liquid center.
• the thread rubber may include, for example, those prepared by subjecting natural rubber, or a blend of natural rubber and polyisoprene rubber to vulcanization and molding. The winding process is under high tension to produce a threaded layer over the solid or liquid center. Conventional techniques may be employed in winding the thread rubber and known compositions may be used.
• the thread rubber is not limited with respect to specific gravity, dimension and gage, it usually has a specific gravity of .9 to 1 . 1 , a width of .047 to .094 and a gage of .01 2 to .026.
• the rubber thread layer has a radial thickness of 0. 1 0 to .31 5 inches and comprises a wound core having an outer diameter of 1 .52 to 1 .63 inches.
• the overall weight of the wound core is 33 to 44 grams, preferably 35 to 39 grams.
• cover layers of the present invention golf ball preferably but not necessarily comprise an ionomer resin.
• High or low acid ionomers, or ionomer blends can be used.
• the high acid ionomers which may be suitable for use in formulating the cover compositions are ionic copolymers which are the metal, i.e., sodium, zinc, magnesium, lithium, etc., salts of the reaction product of an olefin having from about 2 to 8 carbon atoms and an unsaturated monocarboxyhc acid having from about 3 to 8 carbon atoms.
• the lonome ⁇ c resins are copolymers of ethylene and either acrylic or methacryhc 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 carboxyiic acid groups of the copolymer are at least partially neutralized (i.e. , approximately 1 0% to 100%, and preferably 30% to 70%) by the metal ions.
• Each of the high acid ionomer resins contains greater than about 1 6% by weight of a carboxyiic acid, and preferably from about 1 7% to about 25% by weight of a carboxyiic acid, and more preferably from about 1 8.5% to about 21 .5% by weight of a carboxyiic acid.
• the high acid lonome ⁇ c resins available from Exxon under the designation " lotek” are somewhat similar to the high acid lonome ⁇ c resins available under the "Surlyn ® " trademark. However, since the lotek lonome ⁇ c resins are sodium, lithium or zinc salts of poly(ethylene-acryhc acid) and the “Surlyn ® " resins are zinc, sodium, lithium, etc. salts of poly(ethylene-methacryhc acid), distinct differences in properties exist
• Non-limiting examples of the high acid methacryhc acid based ionomers suitable for use in accordance with this invention include Surlyn ® 8140 (Na), 8220 (Na), 8240 (Na), 91 20 (Zn), 9220 (Zn), AD81 81 (Li), AD8530 (Zn) , AD8531 (Na) and SEP 671 (Li) .
• Table 1 set forth below, lists properties for two of these materials.
• high acid acrylic acid based ionomers suitable for use in the present invention also include lotek high acid ethylene acrylic acid ionomers produced by Exxon such as 1 001 , 1 002, 959, 960, 989, 990, 1003, 1 004, 993, and 994.
• lotek 959 is a sodium ion neutralized ethylene-acryhc acid copolymer.
• loteks 959 and 960 contain from about 1 9.0 to about 21 .0% by weight acrylic acid with approximately 30 to about 70 percent of the acid groups neutralized with sodium and zinc ions, respectively.
• Table 2 The physical properties of these and other high acid acrylic acid based ionomers are set forth in Table 2 as follows:
• new metal cation neutralized high acid ionomer resins have been produced by the inventor by neutralizing, to various extents, high acid copolymers of an alpha-olefin and an alpha, beta-unsaturated carboxyiic acid with a wide variety of different metal cation salts. It has been found that numerous new metal cation neutralized high acid ionomer resins can be obtained by reacting a high acid copolymer (i.e. a copolymer containing greater than 1 6% by weight acid, preferably from about 1 7 to about 25 weight percent acid, and more preferably about 20 weight percent acid), with a metal cation salt capable of ionizing or neutralizing the copolymer to the extent desired (i.e. from about 10% to 90%) .
• a high acid copolymer i.e. a copolymer containing greater than 1 6% by weight acid, preferably from about 1 7 to about 25 weight percent acid, and more preferably about 20 weight percent acid
• the base copolymer is made up of greater than 1 6% by weight of an alpha, beta-unsaturated carboxyiic acid and an alpha-olefin.
• a softening comonomer can be included in the copolymer.
• the alpha-olefin has from 2 to 1 0 carbon atoms and is preferably ethylene
• the unsaturated carboxyiic acid is a carboxyiic acid having from about 3 to 8 carbons.
• acids include acrylic acid, methacryhc 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 carboxyiic acids wherein the acids have 2 to 1 0 carbon atoms, vinyl ethers wherein the alkyl groups contains 1 to 1 0 carbon atoms, and alkyl acrylates or methacrylates wherein the alkyl group contains 1 to 1 0 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 1 6% by weight unsaturated carboxyiic 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 carboxyiic acid and about 80% by weight ethylene. Most preferably, 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 "P ⁇ macor" designation These high acid base copolymers exhibit the typical properties set forth below in Table 3
• this copolymer is the more preferred grade utilized in the invention.
• the metal cation salts utilized in the present invention are those salts which provide the metal cations capable of neutralizing, to various extents, the carboxyiic 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 zinc acetate dihydrate and zinc acetate, a blend of zinc 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 1 0 psi to 1 0,000 psi. Other 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 carboxyiic acid groups in the high acid copolymer.
• the extent of neutralization is generally from about 1 0% to about 90%.
• the acid groups of copolymers of acrylic acid and ethylene sold by The Dow Chemical Co. (Midland, Ml) and designated as "Primacor 5981 " were neutralized to various weight percentages using a number of different cations, a number of different high acid ionomer resins were produced. Due to differences in the nature of the cation salts, the amount of cation salts utilized, etc. , the new high acid ionomer resins produced differed substantially in the extent of neutralization and in melt indices, as well as in resilience (i.e. C.O.R.) and hardness values.
• NaOH refers to sodium hydroxide (formula weight of 40) .
• MnAc manganese acetate tetrahydrate having a formula weight of 245.
• the specific cation salts were added in differing amounts with the 20 weight percent acrylic acid/ethylene copolymer (i.e. the Primacor 5981 ) to an internal mixer (Banbury type) for the neutralization reaction.
• the only exception was calcium acetate, which, due to problems encountered in solid form, was added as a 30 wt % solution in water.
• the new metal cation neutralized high acid ionomer resins exhibit enhanced hardness, modulus and resilience characteristics. These are properties that are particularly desirable in a number of thermoplastic fields, including the field of golf ball manufacturing.
• either or both high and low acid ionomer resins may be used in the cover compositions so long as the molded cover layers have a Shore D hardness of 60 or more, and more preferably 60 or more.
• one or more low acid (i.e. 1 6 weight % and/or less) hard ionomers may be included in the present invention.
• the hard (high modulus) ionomers suitable for use in the present invention include those ionomers having a hardness greater than 50 on the Shore D scale as measured in accordance with ASTM method D-2240, and a flexural modulus from about 1 5,000 to about 70,000 psi as measured in accordance with ASTM method D-790.
• the hard ionomer resins utilized to produce the cover compositions are ionic copolymers which are the sodium, zinc, magnesium or lithium 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 carboxyiic acid groups of the copolymer may be totally or partially (i.e. approximately 1 5-75 percent) neutralized.
• the hard lonomeric resins are copolymers of ethylene and either acrylic and/or methacryhc acid, with copolymers of ethylene and acrylic acid the most preferred.
• two or more types of hard lonomeric resins may be blended into the cover compositions in order to produce the desired properties of the resulting golf balls.
• Examples of commercially available hard ionomeric resins which may be utilized in the present invention 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 methacryhc acid with about 1 5 weight percent acid which is about 29% neutralized with sodium ions. This resin has an average melt flow index of about 2.8.
• Surlyn ® 991 0 is a copolymer of ethylene and methacryhc acid with about 1 5 weight percent acid which is about 58% neutralized with zinc ions.
• the average melt flow index of Surlyn ® 991 0 is about 0.7.
• the typical properties of Surlyn ® 991 0 and 8940 are set forth below.
• Examples of the more pertinent acrylic acid based hard ionomer resins suitable for use in the present invention sold under the " lotek” tradename by the Exxon Corporation include “ lotek 4000” (formerly “Escor 4000"), “ lotek 401 0", “ lotek 8000” (formerly Escor 900), “ lotek 8020", and “ lotek 8030” .
• the typical properties of the lotek hard ionomers are set forth below in Table 5.
• non-ionomeric materials can also be blended with the ionomers, or used separately, to produce the cover layer of the invention.
• materials that can be utilized include ethylene-ethyl acrylate, ethylene-methyl acrylate, ethylene-vinyl acetate, low density polyethylene, linear low density polyethylene, metallocene catalyzed polyolefins such as ENGAGE polyolefins available from Dow Chemical and EXACT polyolefins available from Exxon, non-ionomeric acid copolymers such as PRIMACOR, available from Dow Chemical, and NUCREL, available from DuPont, and a variety of thermoplastic elastomers, including KRATON, available from Shell, SANTOPRENE, available from Monsanto, and HYTREL, available from DuPont, etc.
• nylon-containing or nylon-based materials may be incorporated into the various cover layers of the present invention golf ball .
• Preferred nylon materials for utilizing in the present invention golf ball are described in U.S. Patent No. 5,886, 1 03 herein incorporated by reference.
• the layers of the cover may be formed from generally the same resin composition, or may be formed from different resin compositions with similar hardnesses.
• one cover layer may be formed from an ionomeric resin of ethylene and methacryhc acid, while another layer is formed from an ionomer of ethylene and acrylic acid.
• One or more cover layers may contain polyamides or polyamide-nylon copolymers or intimate blends.
• polyurethanes, pebax, or thermosetting polyurethane can be used.
• agents such as phosphorous, florescent dies, florescent pigments, etc. can be used.
• cover (or inner and outer cover layers) of the present invention may also be added to the cover (or inner and outer cover layers) of the present invention as long as they do not substantially reduce the playabihty properties of the ball.
• materials include dyes (for example, Ultramarine Blue sold by Whitaker, Clark, and Daniels of South Plainsfield, N.J.) (see U.S. Patent No. 4,679,795), optical brighteners, pigments such as titanium dioxide, zinc oxide, barium sulfate and zinc sulfate; UV absorbers; antioxidants; antistatic agents; and stabilizers
• the cover compositions of the present invention may also contain softening agents such as those disclosed in U . S. Patent Nos. 5,31 2,857 and 5,306,760, both of which are herein incorporated by reference, including plasticizers, metal stearates, processing acids, etc. , as long as the desired properties produced by the golf ball covers of the invention are not impaired.
• cover compositions of this invention may also contain softening agents, such as plasticizers, 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 inner cover layer or inner cover layers contain filler materials. More particularly, filler materials are included in order to affect moment of inertia and spin of the golf ball, for example.
• suitable filler materials for the inner cover layer or layers of the golf ball include, but are not limited to, clay, talc, asbestos, graphite, glass, mica, calcium metal silicate, barium sulfate, zinc sulfide, aluminum hydroxide, silicates, diatomaceous earth, carbonates such as calcium carbonate, magnesium carbonate and the like, metals such as titanium, tungsten, aluminum, bismuth, nickel, molybdenum, iron, copper, brass, boron, bronze, cobalt and beryllium, and alloys of the above metals, metal oxides such as zinc oxide, iron oxide, aluminum oxide, titanium oxide, magnesium oxide, zirconium oxide and the like, particulate synthetic plastic such as high molecular weight polyethylene, polystryene, polyethylene ionomer resins and the
• the amount of filler employed is primarily a function of weight restrictions. For example, weight may be removed from the core and placed in the inner and/or outer cover. This added weight will change the moment of inertia of the ball thereby potentially altering performance. Whereas typically the specific gravity of the cover layer or layers is about 0.95 - 1.00, it may be desirable to increase the specific gravity of one or more of the cover layers to greater than 1.0, preferably 1.1 - 2.0.
• optical brighteners such as those disclosed in U.S. Patent No. 4,679,795, herein incorporated by reference, may also be included in the cover composition of the invention.
• suitable optical brighteners which can be used in accordance with this invention are Uvitex OB as sold by the Ciba-Geigy Chemical Company, Ardsley, N . Y . Uvitex O B thought to be
• Phorwhite K-20G2 is sold by Mobay Chemical Corporation, P.O. Box 385, Union Metro Park, Union, N.J. 07083, and is thought to be a pyrazoline derivative.
• Eastobrite OB-1 is 2,2'(1 ,2-ethenediyldi-4, 1-phenylene)bisbenzoxazole and is available from Eastman Chemical Company.
• optical brighteners since many optical brighteners are colored, the percentage of optical brighteners utilized must not be excessive in order to prevent the optical b ⁇ ghtener from functioning as a pigment or dye in its own right.
• the percentage of optical brighteners which can be used in accordance with this invention is from about 0 01 % to about 0 5% as based on the weight of the polymer used as a cover stock.
• a more preferred range is from about 0.05% to about 0.25% with the most preferred range from about 0.1 0% to about 0.20% depending on the optical properties of the particular optical b ⁇ ghtener used and the polymeric environment in which it is a part
• the additives are admixed with a ionomer to be used in the cover composition to provide a masterbatch (M.B.) of desired concentration and an amount of the masterbatch sufficient to provide the desired amounts of additive is then admixed with the copolymer blends
• cover layer compositions when combined with soft cores at the cover layer thicknesses described herein, produce golf balls having a relatively low spin in combination with good click and feel
• the cover compositions and molded balls of the present invention may be produced according to conventional melt blending procedures.
• the ionomeric resins are blended along with the masterbatch containing the desired additives in a Banbury ® type mixer, two-roil mill, or extruded prior to molding.
• the blended composition is then formed into slabs or pellets, etc. and maintained in such a state until molding is desired.
• a simple dry blend of the pelletized or granulated resins and color masterbatch may be prepared and fed directly into the injection molding machine where homogemzation occurs in the mixing section of the barrel prior to injection into the mold.
• Additives such as the fillers, etc. , are added and uniformly mixed before initiation of the molding process
• the golf balls of the present invention can be produced by molding processes currently well known in the golf ball art.
• the golf balls can be produced by conventional molding techniques, such as by injection molding or compression molding the novel cover compositions over the soft polybutadiene cores to produce a golf ball having a diameter of about 1 .680 inches or greater, preferably at least 1 .70 inches, and weighing about 1 .620 ounces. Larger molds are utilized to produce the thicker covered oversized golf balls.
• For injection-molded cover layers having a thickness of up to about 3.0 mm it may be preferable to mold the cover in a single step.
• covers and for cover layers of 3.0 mm or more it generally is preferable for reasons of both processability and uniformity to mold the cover in two layers.
• the 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 dimpled golf ball mold and subjected to compression molding at 200 to 300 F ° for 2 to 1 0 minutes, followed by cooling at 50 to about 70 ° F. for 2 to 10 minutes, to fuse the shells together to form an unitary ball.
• the golf balls may be produced by injection molding, wherein the cover composition is injected directly around the core placed in the center of a golf ball mold for a period of time at a mold temperature of from 50 to about 1 00 ° F. After molding the golf balls produced may undergo various further finishing steps such as flash trimming, priming, marking, finish coating and the like as is well known and is disclosed, for example in U.S. Patent No. 4,91 1 ,451 , herein incorporated by reference.
• Example 1 Thick, Single Cover Oversize Balls A number of golf ball cores having Formulation A, shown below, were prepared. Core Formulation A
• Red pigment 10 3.00 Sulfur (insol) 1 1 3.1 4
• Example 1 -1 One to two dozen cores were made having an average diameter of 36.3 mm ( 1 .430 inches) (Example 1 -1 ) .
• Example 1 -1 One to two dozen cores having an average diameter of 37.3 mm ( 1 .470 inches) also were made (Example 1 -2) .
• the 36.3 mm diameter cores were cured at 320 ° F for 1 2 minutes, followed by six minutes of cooling using cold water.
• the cores having a 37.3 mm diameter were cured at 320 ° F for 1 2 minutes, followed by six minutes of cooling using cold water.
• the cores were covered with a thick, single layer of an ionomeric cover material to produce an unfinished golf ball 43.7 mm ( 1 .72 inches) in diameter.
• the ionomeric cover material consisted of Cover Formulation W, shown below:
• the golf balls with a 36.3 mm average core diameter had an overall average weight of 43.5 grams, an average cover thickness of 3.68 mm (0. 145 inches), an average PGA compression of 78, and an average coefficient of restitution (C.O.R.) of 0.744 (Example 1 - 1 ) .
• the golf balls with 37.3 mm ( 1 .470 inch) average core diameters had an average weight of 44.4 grams, an average cover thickness of 3.1 8 mm (0.1 25 inches), an average PGA compression of 48, and an average coefficient of restitution of 0.732 (Example 1 -2).
• Example 1-3 The cores were cured for 15 minutes at 310°F followed by 7 minutes of cooling using cooling water. Cores having average diameters of 36.3 mm (1.430 inches) (Example 1-4) and of 37.3 mm (1.470 inches) were formed (Example 1-3).
• Example 1-C1 Cores having an average diameter of 39.2 mm (1.545 inches) also were formed (Example 1-C1) as a control. These cores are representative of the size of cores in standard size, oversized golf balls.
• the cores of Examples 1-3, 1-4 and 1-C1 were covered with a single layer of the same ionomeric cover material as was used in Examples 1-1 and 1-2.
• the 36.3 mm and 37.3 mm diameter cores resulted in thick covered, oversized golf balls having an overall diameter of 43.7 mm (1.72 inches) (Examples 1-3 and 1-4).
• the 39.2 mm cores were used to form golf balls having a diameter of 43.8 mm (1.725 inches) (Example 1-C1).
• the golf balls made from 36.3 mm cores had a final weight of 44.5 grams, a cover thickness of 3.68 mm (0.145 inches), a PGA compression of 112 and a coefficient of restitution of 0.811.
• the balls made from 37.3 mm cores had a weight of 45.1 grams, a cover thickness of 3.18 mm (0.124 inches), a PGA compression of 105, and a coefficient of restitution of 0.809.
• the normal cover thickness control balls having 39.2 mm cores (Example 1-C1) had an overall weight of 46.0 grams, a cover thickness of 2.29 mm (0.090 inches), a PGA compression of 93, and a coefficient of restitution of 0.812.
• a number of 32.8 mm ( 1 .29 inch) average diameter golf ball cores were made using Core Formulation C, shown below.
• the curing process was the same as the sulfur curing process described above in Example 1 .
• the cores were used to make four different types of golf balls having the cover compositions and thicknesses shown in Table 6 as Examples 2- 1 to 2-4.
• the lotek 959/960 cover formulation (Cover Formulation X utilized) also is shown below.
• the resulting average PGA compression and coefficient of restitution of the golf balls also is shown in Table 6.
• the physical properties of the resulting balls are shown in Table 6 as 2-C 1 .
• the very thick covered balls (2- 1 to 2-4) had the same, or substantially the same, overall compression (i.e. 1 05-1 1 6 PGA) as the thin covered control (i.e., 2-C1 , 1 05 PGA) even though the thick covers were more than double, and in some instances nearly triple, the thickness of the control.
• the cores were cured for 1 2 minutes at 320 " F, followed by cooling for six minutes with cooling water.
• the sulfur-cured cores (Examples 3-3, 3-4, 3-7 and 3-8) had an average surface Shore A hardness of 71 , an average surface Shore C hardness of 35 and an average surface Shore D hardness of 21 .
• a number of peroxide-cured cores having an average diameter of 32.5 mm ( 1 .28 inches) and Core Formulation B, shown above were formed.
• the cores were cured for 1 5 minutes at 310 ° F, followed by cooling for seven minutes using cooling water.
• the cores (Examples 3- 1 , 3-2, 3-5 and 3-6) had the PGA compression and COR values shown in Table 6.
• a number of standard size "control" cores were made having a diameter of 39.2 mm ( 1 .545 inches) and having Core Formulation F, shown below, were formed (Examples 3-C 1 and 3-C2) .
• control cores having a diameter of 39.2 mm ( 1 .545 inches) and having Core Formulation G, shown below, were formed (Examples 3-C3 and 3-C4).
• the 32.5 mm cores were covered with a thick multi-layer cover, i.e. 3.35 mm (0. 1 32 inch) thick layer of ionomer followed by a 1 .78 mm (0.070 inch) thick layer of the same or a different ionomer.
• the covers had a "422 tn" dimple pattern, which is the same dimple pattern as is used on the Top-F te Hot XL ( 1 995), tour trajectory ball
• the control cores were covered with a single layer of ionomer having a thickness of 1 .78 mm (0.070 inches). The results demonstrate that thick covered multi-layer golf balls can be produced having comparable compression and C.O.R. values as existing multi-layer golf balls.
• thermoplastic golf ball cores containing 100 parts by weight EXACT 4049 (Exxon Chemical Co.) , a metallocene catalyzed polyolefim and 60 parts by weight of tungsten powder were formed (Core Formulation H, Examples 4- 1 , 4-2, 4-5 and 4-6) .
• the cores were cured for 5 minutes at 320 ° F followed by cooling using cooling water for 7 minutes.
• the cores had an average weight of 23.3 grams and an average diameter of 32.5 mm ( 1 .28 inches) .
• Cover formulation Y is as follows: Cover Formulation Y
• Cover formulation Z is as follows:
• a number of crosslinked cores were made using 1 00 parts by weight of EXACT 4049 (Exxon Chemical Co. , Houston, Texas), which is a metallocene catalyzed polyolefim, 60 parts by weight of tungsten powder and 5 parts by weight Trigonox 1 7/40 (Core Formulation J, Examples 4-3, 4-4 and 4-7) .
• the cores were cured for 14 minutes at 320 ° F followed by cooling with cooling water for 7 minutes.
• the cores had a weight of 23.6 grams.
• the cores had a diameter of 32.5 mm ( 1 .28 inches), and were covered with the same types and thicknesses of cover materials as were used for the thermoplastic cores.
• the cover materials are shown in Table 6.
• the outer covers of Example 4 employed a "422 Hex" dimple pattern, which is the same dimple pattern as is used on the Top-Flite XL ( 1 996), regular trajectory ball.
• the compression and coefficient values for the balls having a single cover layer, both cover layers, and finished products were determined and are shown in Table 6.
• the thick covered balls, having metallocene catalyzed polylefin cores give relatively soft compression versus the thick covered balls having polybutadiene cores, and demonstrate the variety of properties which are possible with the novel constructions of the invention.
• the balls of this Example which have cores made of metallocene catalyzed polyolefin would be useful as range or practice balls, as they have a soft feel and high spin, as well as a very durable, hard cover.
• the balls of Examples 3-1 , 3-2, 3-7, 4-5 and 4-6 were distance tested and were compared with the 1995 Top-Flite ® Hot XL golf balls The distance test conditions are provided below
• Example 3-1 The longest ball is that of Example 3-1. This result is surprising, particularly in view of the fact that this ball has a COR of 0 806, while the 1995 Top-Flite ® Hot XL ball has a COR of 0.812 ⁇ 0.003
• Example 3-2 also had a surprisingly long total distance given its low COR of
• Example 3-1 is the longest
• the ball of Example 3-2 again had a surprisingly long total distance given its low COR
• control golf ball cores having an average diameter of 39 2 mm (1 545 inches) and a weight of 36 7g were formed using Core Formulation K, shown below
• the cores were cured for 11 1 / 2 minutes at 320°F, and were then cooled using cooling water for about 7 minutes
• the cores had a PGA compression of 95 and a COR of 0 770
• a number of golf ball cores having Core Formulation L (shown below) and average diameters of 34 8 mm (1 37 inches) and 39 9 mm (1 57 inches) were formed The cores were cured for 12 minutes at 320°F, followed by cooling using cooling water for about 6 minutes Core Formulation L
• control Examples 6-C1 , 6-C2 and 6-C3 were covered with a single cover layer having a thickness of 1 78 mm (0 07 inches)
• the control cores were covered with the cover formulations shown in Table 9, which are the same as cover formulations W-Z in Examples 1-4
• the cores of Examples 6-1 through 6-10 were covered with inner and outer covers having the cover formulations and thicknesses shown in Table 9. All of the balls of the present invention and the control balls were distance tested using a 5-iron at 128 feet per second and a driver at 160 feet per second.
• the thick covered balls of the present invention had substantially lower coefficients of restitution than the control balls, their distance was only slightly shorter.
• the golf balls of the invention provide a greater distance per point of COR as compared to the control balls.

Landscapes

• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Physical Education & Sports Medicine (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=23311193

Family Applications (1)

Country Status (6)

Families Citing this family (69)

Citations (2)

Family Cites Families (37)

• 1999
  • 1999-06-17 US US09/335,302 patent/US6220972B1/en not_active Expired - Fee Related
• 2000
  • 2000-06-16 CA CA002338357A patent/CA2338357C/en not_active Expired - Fee Related
  • 2000-06-16 JP JP2001504465A patent/JP2003502123A/ja active Pending
  • 2000-06-16 WO PCT/US2000/017089 patent/WO2000078408A1/en not_active Ceased
  • 2000-06-16 GB GB0101939A patent/GB2354715A/en not_active Withdrawn
  • 2000-06-16 AU AU58823/00A patent/AU5882300A/en not_active Abandoned
• 2001
  • 2001-04-20 US US09/839,816 patent/US6561928B2/en not_active Expired - Fee Related

Patent Citations (2)

Also Published As

Similar Documents

Legal Events