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US 2001/0034412 A1Published application
Golf ball core compositions
AssigneeSpalding Sports Worldwide, Inc.
InventorR. Dennis Nesbitt
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AssigneeSpalding Sports Worldwide, Inc.
InventorR. Dennis Nesbitt
Estimating the term…
The present invention is directed to improved polybutadiene compositions suitable for use in molded golf ball core construction. The improved polybutadiene compositions are composed of polypropylene powder resins which have the effect of increasing the hardness of the resulting molded cores without increasing the weight upon curing, thereby allowing for a reduction in the amount of crosslinking agents utilized and increasing the amount of fillers incorporated therein. The addition of the polypropylene powder resins to the core compositions lowers the cost of the molded core, while maintaining the proper weight and compression. The present invention is also directed to golf balls produced utilizing the improved core compositions. Furthermore, the invention is directed to a method for reducing the amount of crosslinking agents utilized to formulate a core composition through the incorporation of polypropylene powder resins. In addition, a method for decreasing the amount of crosslinking agents and increasing the amount of mineral fillers included in a core composition through the incorporation of polypropylene powder resins is also disclosed.
An improved core composition for a golf ball, said composition comprising a base elastomer selected from polybutadiene and mixtures of polybutadiene with other elastomers, said polybutadiene having a molecular weight of from about 50,000 to about 500,000, at least one metallic salt of an α,β-ethylenically unsaturated monocarboxylic acid, a free radical initiator, and a polypropylene powder resin.
In a core composition for a golf ball comprising a base elastomer selected from polybutadiene and mixtures of polybutadiene with other elastomers, at least one metallic salt of an α,β-ethylenically unsaturated monocarboxylic acid, a free radical initiator, and a filler, the improvement comprises adding a low specific weight polypropylene powder resin to increase the hardness without increasing the weight of the core composition thereby reducing the amount of metallic salt of an α,β-ethylenically unsaturated monocarboxylic acid and increasing the amount of filler included in the core composition.
In a core composition for a golf ball comprising a base elastomer selected from polybutadiene and mixtures of polybutadiene with other elastomers, from about 20 to about 50 parts per weight elastomer of at least one metallic salt of an unsaturated carboxylic acid, from about 1 to about 10 parts per weight elastomer of a free radical initiator, and from about 0 to about 50 parts per weight elastomer of a filler additive, the improvement comprises adding from about 10 to about 100 parts per weight elastomer of a low specific weight polypropylene powder resin to increase the hardness of the core composition thereby decreasing the amount of metallic salt of an unsaturated carboxylic acid included in the core composition.
A method of decreasing the amount of a metallic salt of an unsaturated carboxylic acid present in the core composition having a base elastomer selected from polybutadiene and mixtures of polybutadiene with other elastomers, at least one metallic salt of an α,β-ethylenically unsaturate monocarboxylic acid and a free radical initiator, said method comprising the step of adding to the core composition a polypropylene powder resin.
A method for decreasing the amount of a metallic salt of an unsaturated carboxylic acid and increasing the amount of a mineral filler in a core composition having a base elastomer selected from polybutadiene and mixtures of polybutadiene with other elastomers, at least one metallic salt of an unsaturated carboxylic acid, a free radical initiator and a mineral filler, said method comprising the step of adding to the core composition a polypropylene powder resin.
Dependencies are inferred from the claim text.
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Solid balls; Rigid hollow balls; Marbles: golf balls
Physical properties: hardness
Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
Cores: materials other than polybutadienes; Constructional details
Term end not estimated
The present invention is directed to improved polybutadiene compositions for use in molded golf ball core construction. The improved polybutadiene compositions contain polypropylene powder resins, which have the effect of increasing the hardness of the resulting molded cores without increasing the weight and/or substantially reducing the resiliency of the ball. The present invention is also directed to golf balls produced utilizing the improved core compositions.
Moreover, it has been found that the addition of the particulate polypropylene allows for a reduction in the amount of crosslinking agents utilized in the core compositions and/or an increase in the amount of higher specific gravity fillers, thereby dramatically decreasing the cost of the golf ball cores. A method for producing such an effect is also disclosed.
Two of the principal properties involved in the performance of golf balls are resilience and hardness. 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, or more generally, the ratio of the outgoing velocity to incoming velocity of a rebounding ball. As a result, the coefficient of restitution (i.e. “e”) can vary from zero to one, with one being equivalent to an elastic collision and zero being equivalent to an inelastic collision. Hardness is determined as 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).
Using the ingredients tabled below, golf ball cores having a finished diameter of about 1.540 to about 1.545 inches were produced by compression molding and subsequent removal of a surface layer by grinding. Each core was formulated using 100 parts elastomer (rubber). In the formulations, the amounts of remaining ingredients are expressed in parts by weight, and the degrees of coefficient of restitution and compression achieved are set forth below. The data for these examples are the averages for twelve cores which were produced for each example. The properties of the molded cores produced from each formulation were measured according to the following parameters:
Riehle compression is a measurement of the deformation of a golf ball in inches under a fixed static load of 200 pounds.
Coefficient of restitution (C.O.R.) was measured by firing the resulting golf ball in an air cannon at a velocity of 125 feet per second against a steel plate which is positioned 12 feet from the muzzle of the cannon. The rebound velocity was then measured. The rebound velocity was divided by the forward velocity to give the coefficient of restitution. 4 TABLE 1 Effect of the Addition of Polypropylene Powder Resin on the Properties of the Molded Core Formulations 1 2 3 4 5 6 7 8 Ingredients BR-12201 90 90 90 90 90 90 90 90 SKI-352 10 10 10 0 10 10 10 10 ZDA3 31 31 31 31 27 23 23 23 ZnO 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Zinc Stearate 15 15 15 15 15 15 15 15 Limestone 18 18 18 18 18 18 28 38 Grd FLash 20 20 20 20 20 20 20 20 6400 P4 0 20 30 40 30 30 30 30 Trig 17/405 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Papi 946 .5 .5 .5 .5 .5 .5 .5 .5 Total 192.0 212.0 222.0 232.0 218.0 214.0 224.0 234.0 Properties Molded Core Size, inches 1.539 1.539 1.538 1.539 1.540 1.540 1.540 1.540 Wgt., grams 36.5 35.6 35.1 34.8 35.0 34.6 35.6 36.7 Comp. (Riehle) .064 .057 .056 .054 .060 .065 .065 .062 {overscore (e)} (C.O.R.) .796 .783 .773 .763 .767 .760 .752 .747 Molded Ball Size, inches 1.683 1.683 1.682 1.683 1.683 1.683 1.683 1.683 Wgt., grams 45.4 44.5 44.1 43.7 43.3 43.4 44.5 45.4 Comp. (Riehle) .050 .040 .037 .037 .045 .054 .051 .050 {overscore (e)} (C.O.R.) .811 .796 .787 .777 .785 .780 .775 .767 1BR-1220 is polybutadiene manufactured and sold by Shell Chemical Co., Houston, Texas. 2SKI-35 is a polyisoprene available from Muehlstein, H. & Co., Greenwich, Connecticut. 3ZDA is zinc diacrylate. 46400 P is a powdered polypropylene available from Amoco Chemical Co., Chicago, Illinois. 5Trig 17/40 is Trigonex 17/40 manufactured and soLd by Akzo Chemie America, Chicago, Illinois. 6Papi 94 is a polymeric diisocyanate availible from Dow Chemical Co., Midland, Michigan.