Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-05-06
2004-10-05
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S432000, C528S335000, C473S371000, C473S374000, C473S378000, C473S385000
Reexamination Certificate
active
06800690
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to golf balls having at least one layer formed from compositions including at least one of a polyamide, in the form of a homopolymer, a copolymer or mixtures thereof, or an olefinic polymer produced using a single-site metallocene catalyst in the polymerization process, to which at least one pendant functional group has been grafted by a post-polymerization reaction. The polyamide compositions may be mixed with ionomers or non-ionomers, including grafted or non-grafted metallocene catalyzed polymers. The grafted metallocene catalyzed polymer compositions may be mixed with at least one of an ionomer, a non-grafted or unfunctionalized metallocene catalyzed polymer, polyamide, or other non-ionomeric polymer to form a blend. The compositions may be used in any layer of a golf ball, may be foamed or unfoamed, and may include at least one density-adjusting filler.
BACKGROUND OF THE INVENTION
Golf ball manufacturers are constantly attempting to construct golf balls having a desirable combination of good “feel,” distance, and durability. One way in which the properties of a golf ball may be adjusted is through the cover composition and construction of the ball. Traditionally, softer feeling golf balls were obtained by providing an outer cover formed with natural or synthetic balata over a liquid center surrounded by a tensioned elastomeric wound layer. Because of its softness, however, balata is susceptible to cuts or other damage to the cover, and, thus, lacks the durability required to withstand the numerous mis-hits produced by the average golfer.
For this reason, amateur golfers typically prefer a golf ball constructed with a harder, more durable cover material, such as an ionomer or ionomer blend. Covers formed of ionomeric materials generally provide a good combination of distance and durability. Because of the hard ionomer cover, these balls are difficult to cut, but have a very hard “feel”, and a lower spin rate, making these balls more difficult to draw or fade. The differences in the spin rate can be attributed to the differences in the composition and construction of both the cover and the core.
Many attempts have been made to produce a golf ball with the control and feel of a wound balata ball and the durability of a solid, two-piece ionomer-covered ball, but none have succeeded totally. U.S. Pat. Nos. 4,884,814, 5,120,791, 5,324,783 and 5,492,972 are examples of such attempts through blends of high hardness and low hardness ionomers. None of the disclosed ionomer blends, however, have resulted in the ideal balance of carrying distance, coefficient of restitution, spin rate and initial velocity that would approach the highly-desirable playability of a balata covered golf ball. In addition, blends of more than one variety of polymer, e.g., ionomer and balata or ionomer and a non-ionic polymer, have also not successfully been used or have not been disclosed in the prior art for use in golf ball components to achieve a combination of feel and durability.
For example, golf ball components formed of unique blends of ionomers and nonionomers, such as metallocene catalyzed polymers, are absent from the prior art. While blends of ionomers and metallocene catalyzed polymers are not disclosed in the prior art, processes for grafting monomers onto polymers, and, in particular, polyolefins, however, are disclosed in European Patent No. 266994 and U.S. Pat. No. 5,106,916. European Patent No. 266994 discloses a method of admixing a metallocene catalyzed polymer with a monomer capable of bonding to the metallocene catalyzed polymer and an organic peroxide, and mixing the admixture at a temperature greater than the melting point of the metallocene catalyzed polymer for a time sufficient for the post-polymerization reaction to occur. Typically, the mixing is continued for at least four times the half-life of the organic peroxide. Although the monomer, metallocene catalyzed polymer, and the peroxide may be added in any order, preferably, the metallocene catalyzed polymer and monomer are thoroughly mixed before the peroxide is added.
Grafted metallocene catalyzed polymers share the advantages of non-grafted metallocene catalyzed polymers including a narrow molecular weight distribution and uniform molecular architecture. These features provide metallocene catalyzed polymers with properties that are not available with conventional polymers, and allow polymers to be produced having unique properties that are specifically tailored to a particular application. The desired molecular weight distribution and the molecular architecture are obtained by the selection of the appropriate metallocene catalyst and polymerization conditions.
Because the prior art blended compositions lack the combination of durability and distance provided by two-piece golf balls with ionomer covers and the high spin rate and control that is available with three-piece, wound golf balls having balata covers, there remains a need in the art for a golf ball that possesses these characteristics. In particular, there is a need in the art for a golf ball incorporating non-ionomers, such as non-grafted and grafted metallocene catalyzed polymers, and other polymers, such as ionomers and polyamides. The inclusion of foamed and unfoamed grafted metallocene catalyzed polymers and grafted metallocene catalyzed polymer blends will allow highly durable golf balls to be produced with improved performance and virtually any combination of feel and spin rate.
SUMMARY OF THE INVENTION
The present invention is directed to a golf ball comprising a layer formed from a composition including at least one polyamide formed from at least one dibasic acid and at least one diamine and at least one metallocene catalyzed polymer, wherein the metallocene catalyzed polymer has been functionalized by sulfonation, carboxylation, addition of an amine or hydroxy, or by grafting an ethylenically unsaturated monomer onto the at least one metallocene catalyzed polymer using a post-polymerization reaction.
The present invention is also directed to a golf ball having a core and a cover, wherein at least a portion of the cover is formed from a composition including a polyamide copolymer formed from at least one dibasic acid and at least one diamine, wherein the at least one dibasic acid comprises about 14 carbons to about 40 carbons, and wherein the polyamide copolymer lacks affinity for water.
The present invention is further directed to a golf ball having a layer formed from a composition including at least one polyamide formed from at least one dibasic acid and at least one diamine and a metallocene catalyzed polymer comprising a copolymer of ethylene or propylene with butene, hexene, or octene.
In one embodiment, the polyamide has a flexural modulus of about 5,000 psi to about 500,000 psi and the metallocene catalyzed polymer has a flexural modulus of about 500 psi to about 200,000 psi. The ethylenically unsaturated monomer may be an olefinic monomer having a functional group selected from the group consisting of sulfonic acid, sulfonic acid derivatives, chlorosulfonic acid, vinyl ethers, vinyl esters, primary amines, secondary amines, tertiary amines, mono-carboxylic acids, dicarboxylic acids, partially or fully ester derivatized mono-carboxylic acids, partially or fully ester derivatized dicarboxylic acids, anhydrides of dicarboxylic acids, cyclic imides of dicarboxylic acids, and ionomeric derivatives thereof. In one embodiment, the ethylenically unsaturated monomer is maleic anhydride.
The composition may further include at least one additional agent selected from the group consisting of coloring agents, reaction enhancers, crosslinking agents, whitening agents, UV absorbers, processing aids, antioxidants, stabilizers, softening agents, plasticizers, impact modifiers, density-adjusting fillers, foaming agents, excipients, reinforcing materials, compatibilizers, and mixtures thereof.
In one embodiment, the layer has a foamed structure.
In another embodiment, the layer has a thickness of about 0.1 inches o
Harris Kevin M.
Rajagopalan Murali
Acushnet Company
Buttner David J.
Swidler Berlin Shereff & Friedman, LLP
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