Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-05-30
2003-09-23
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S322000, C524S394000, C524S398000, C524S399000, C524S400000, C473S351000, C473S365000, C473S376000, C473S377000, C473S378000, C473S379000, C473S380000, C473S381000, C473S382000, C473S383000, C473S384000
Reexamination Certificate
active
06624221
ABSTRACT:
This invention relates to resin compositions for golf balls having good flow characteristics and moldability and heat resistance. It also relates to high-performance golf balls formed thereof and endowed with outstanding rebound energy.
BACKGROUND OF THE INVENTION
Over the past few years, wide use has been made of ionomer resins in golf ball cover materials. Ionomer resins are ionic copolymers composed of an olefin such as ethylene in combination with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid, wherein the acidic groups are partially neutralized with metal ions such as sodium, lithium, zinc or magnesium ions. They have excellent characteristics such as durability, rebound and scuff resistance, making them highly suitable as the base resin in golf ball cover material.
Ionomer resins account for most of the cover stock resin in current use and enable the production of golf balls having the above properties. However, golfers are always on the lookout for golf balls having a high rebound and excellent flight characteristics.
Related improvements taught by the prior art (see U.S. Pat. No. 5,312,857, U.S. Pat. No. 5,306,760, and International Application WO 98/46671) include cover stock in which a large amount of metallic soap is added to the ionomer resin to improve the cost and rebound characteristics of the ionomer cover stock. Such modifications have indeed resulted in better rebound than earlier golf balls with ionomer covers.
However, because a large amount of metallic soap is added to the ionomer resin in this prior-art cover stock, the fatty acids that form due to decomposition of the metallic soap vaporize during injection molding, generating a large amount of gas. The formation of a large amount of gas during injection molding causes molding defects. In addition, gas constituents settle on the surface of the molded article and greatly lower the paintability of the molded article. Moreover, although such cover stock in which a large amount of metallic soap has been added to the ionomer resin does exhibit a rebound which is about the same as or better than that of ionomer having the same degree of hardness, the improvement in rebound is not all that large. Indeed, depending on the type of metallic soap used, the moldability and rebound may in fact be severely compromised and fall far short of practical levels.
To prevent gas evolution during injection molding from an ionomer resin based cover material having magnesium stearate added thereto, the use of low molecular weight polyethylene wax as the dispersant is considered (Japanese Patent No. 2,712,740). Using polyethylene wax instead of magnesium stearate as the dispersant for ionomer resin cover material, the cover material is allegedly improved in molding and the ball produced therefrom is improved in durability. This cover material, however, has the problem that the cover material loses resilience and hardness as the amount of polyethylene wax blended increases. It is desired to overcome this problem.
It was recently proposed to use thermoplastic resins alone or in blend with ionomer resins as the cover inner or outer layer material for producing golf balls with a pleasant feel. The thermoplastic elastomers proposed thus far are polyolefin elastomers (Japanese Patent No. 2,924,706), polyester elastomers (Japanese Patent No. 2,570,587), urethane elastomers (JP-A 9-271538), styrene elastomers (JP-A 8-182776), polyamide elastomers (JP-A 8-155053), and polyolefin (JP-A 9-117532).
Nevertheless, a need exists for resin compositions for golf balls having heat resistance, flow and moldability. In the above-referenced patents, the dispersant that is compliant with a particular resin and allows a golf ball cover material to exhibit excellent physical properties is not under consideration, and problems are left with respect to pigment dispersion.
SUMMARY OF THE INVENTION
An object of the invention is to provide a resin composition for a golf ball which has good flow, moldability and heat resistance and is improved in pigment dispersion and surface preparation after curing so that it is best suited as cover material. Another object of the invention is to provide a high-performance golf ball formed thereof and having improved rebound.
The above and other objects are achieved by the resin composition for the golf ball and the golf ball defined below.
In one aspect, the invention provides a resin composition for a golf ball comprising, in admixture,
(A) 100 parts by weight of at least one thermoplastic resin component selected from the group consisting of (a-1) an olefin-unsaturated carboxylic acid random copolymer and/or an olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary copolymer, (a-2) a metal ion-neutralized product of an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion-neutralized product of an olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary copolymer, and (a-3) a thermoplastic elastomer, and
(B) 0.1 to 10 parts by weight of at least one wax component selected from the group consisting of (b-1) a fatty acid having 20 to 80 carbon atoms and/or a derivative thereof, and (b-2) an oxidized natural wax and/or natural wax derivative having a neutralization value of 60 to 190 mg KOH/g.
In preferred embodiments, the resin composition has a melt index of at least 0.5 dg/min; component (b-1) is behenic acid and/or a derivative thereof; component (b-2) is oxidized montan wax and/or montan wax derivative; component (a-3) is polyolefin, an olefin elastomer, a urethane elastomer, a polyester elastomer, a styrene elastomer, a polyamide elastomer or a mixture of any.
In one preferred embodiment, component (A) contains at least one thermoplastic resin selected from the group consisting of (a-1) an olefin-unsaturated carboxylic acid random copolymer and an olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary copolymer, and (a-2) a metal ion-neutralized product of an olefin-unsaturated carboxylic acid random copolymer and a metal ion-neutralized product of an olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary copolymer. In this embodiment, wax component (B) is preferably selected from among a fatty acid, a metal soap, oxidized natural wax and saponified natural wax.
In another preferred embodiment, component (A) contains (a-3) the thermoplastic elastomer. In this embodiment, wax component (B) is preferably selected from among fatty acid, oxidized natural wax, esterified fatty acid, esterified natural wax, amidated fatty acid and amidated natural wax.
In another aspect, the invention provides a resin composition for a golf ball comprising, in admixture,
(A) 100 parts by weight of at least one thermoplastic resin component selected from the group consisting of (a-1) an olefin-unsaturated carboxylic acid random copolymer and/or an olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary copolymer, (a-2) a metal ion-neutralized product of an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion-neutralized product of an olefin-unsaturated carboxylic acid-unsaturated carboxylate ternary copolymer, and (a-3) a thermoplastic elastomer,
(B) 5 to 35 parts by weight of at least one wax component selected from the group consisting of (b-1) a fatty acid having 20 to 80 carbon atoms and/or a derivative thereof, and (b-2) an oxidized natural wax and/or natural wax derivative having a neutralization value of 60 to 190 mg KOH/g, and
(C) 0.1 to 10 parts by weight of a basic inorganic metal compound capable of neutralizing acid groups in said thermoplastic resin component (A) and/or said wax component (B).
In preferred embodiments, the resin composition has a melt index of at least 0.5 dg/min; component (b-1) is behenic acid and/or a derivative thereof; component (b-2) is oxidized montan wax and/or montan wax derivative; wax component (B) is a fatty acid, a metal soap, oxidized natural wax, saponified natural wax or a mixture of any; the basic inorganic metal compound (C) is calcium hydroxide or magnesium oxide
Ichikawa Yasushi
Takesue Rinya
Bridgestone Sports Co. Ltd.
Sughrue & Mion, PLLC
Szekely Peter
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