Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-07-29
2004-11-23
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S252000, C525S127000, C525S130000, C473S378000, C473S385000
Reexamination Certificate
active
06822028
ABSTRACT:
The present invention relates to golf ball materials based on polyurethane/ionomer resin blends which have good heat resistance, moldability and film adhesion and which are capable of providing high-performance golf balls endowed with outstanding rebound energy and a good feel. The invention relates also to golf balls made with such golf ball materials.
BACKGROUND OF THE INVENTION
In the past, wide use was made of ionomer resins in golf ball cover materials, also referred to hereinafter as “cover stock”. Ionomer resins are ionic copolymers composed of an olefin such as ethylene in combination with a metal salt of an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid. Specifically the acidic groups are partially neutralized with metal ions such as sodium or zinc ions. These resins have excellent characteristics such as durability and resilience and are suited as the base resin in the golf ball cover stock.
Golf ball cover stocks based on ionomer resins are generally very hard and lack a sufficient flexibility to impart a spin rate necessary to control the ball in flight. Also golf balls using such hard ionomer resins as the cover stock lack a “feel” when hit.
To overcome the drawbacks of ionomer resins, cover stocks using thermoplastic polyurethane elastomers were proposed as disclosed in U.S. Pat. Nos. 3,395,109, 4,248,432, and 4,442,282. The cover stocks using thermoplastic polyurethane elastomers are improved in feel and ball controllability over the cover stocks using ionomer resins.
Recently, the cover stock which found a good compromise between the resilience of ionomer resin-base cover stocks and the feel of polyurethane elastomer-base cover stocks was proposed in U.S. Pat. No. 4,674,751 as comprising a blend of an ionomer resin with a polyurethane elastomer.
However, the ionomer resin and the polyurethane elastomer have such properties that they form chemical bonds when heat mixed. When the cover stock composition is kept heated, it gels to inhibit subsequent molding, which is impractical.
SUMMARY OF THE INVENTION
Therefore, one object of the invention is to provide golf ball materials based on polyurethane/ionomer resin blends which have good heat resistance, moldability and film adhesion and which are capable of providing golf balls endowed with outstanding rebound energy and a good feel. Another object of the invention is to provide golf balls made using such golf ball materials.
It has been found that the addition of organic or inorganic basic compounds to polyurethane/ionomer resin blends is effective for preventing the polyurethane/ionomer resin blends from gelling when kept hot. The material thus obtained does not gel upon molding, and a golf ball manufactured using the material is endowed with good rebound energy.
The present invention provides a golf ball material comprising a heated mixture of (A) an olefin-unsaturated carboxylic acid copolymer, an olefin-unsaturated carboxylic acid-unsaturated carboxylate copolymer, a metal ion neutralized product thereof, or a mixture thereof, (B) a polyurethane elastomer, and (C) an organic or inorganic basic compound.
Preferably, a weight ratio of components (A):(B):(C) is 50-99.9:0.1-50:0.1-20, alternatively, a weight ratio of components (A):(B):(C) is 0.1-50:50-99.9:0.1-20. The polyurethane elastomer (B) is typically a thermoplastic polyurethane elastomer or a polyurethane powder. The organic or inorganic basic compound (C) is preferably selected from among an amine, amide, imine, nitrile, phenol, thiol, alcohol, inorganic metal compound and metal soap.
Also contemplated herein is a solid golf ball comprising a solid core and a cover including one or more layers wherein at least one layer of the cover is formed of the golf ball material defined above.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Component (A) in the golf ball material of the present invention is an olefin-unsaturated carboxylic acid copolymer, a metal ion neutralized product of olefin-unsaturated carboxylic acid copolymer, an olefin-unsaturated carboxylic acid-unsaturated carboxylate copolymer, a metal ion neutralized product of olefin-unsaturated carboxylic acid-unsaturated carboxylate copolymer, or a mixture of any.
The olefin generally has at least 2 carbon atoms, but not more than 8 carbon atoms, and preferably not more than 6 carbon atoms. Illustrative examples include ethylene, propylene, butene, pentene, hexene, heptene and octene. Ethylene is especially preferred.
Suitable examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid and fumaric acid. Of these, acrylic acid and methacrylic acid are especially preferred.
The unsaturated carboxylate is preferably a lower alkyl ester of the foregoing unsaturated carboxylic acid. Illustrative examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate. Butyl acrylate (n-butyl acrylate, i-butyl acrylate) is especially preferred.
The copolymer (A) may be prepared by furnishing the above ingredients and carrying out random copolymerization in a well-known manner.
It is recommended that the unsaturated carboxylic acid content (simply referred to as acid content) within the olefin-unsaturated carboxylic acid copolymer be at least 4%, preferably at least 6%, more preferably at least 8%, and most preferably at least 10% by weight, but not more than 30%, preferably not more than 20%, more preferably not more than 18%, and most preferably not more than 15% by weight. Outside the range, a lower acid content may lower resilience whereas a higher acid content may lower processability. For the olefin-unsaturated carboxylic acid-unsaturated carboxylate copolymer, an appropriate acid content is at least 4%, preferably at least 6%, and more preferably at least 8% by weight, but not more than 15%, preferably not more than 12%, and more preferably not more than 10% by weight. Outside the range, a lower acid content may lower resilience whereas a higher acid content may lower processability.
The metal ion-neutralized product of the copolymer may be prepared by partially neutralizing acid groups in the above-mentioned olefin-unsaturated carboxylic acid(-unsaturated carboxylate) copolymer with metal ions.
Examples of the metal ions for neutralizing acid groups include Na
+
, K
+
, Li
+
, Zn
2+
, Cu
2+
, Mg
2+
, Ca
2+
, Co
2+
, Ni
2+
and Pb
2+
. The use of ions such as Na
+
, Li
+
, Zn
2+
, Mg
2+
and Ca
2+
is preferred. The degree of neutralization of the copolymers with metal ions is not critical. The neutralized products may be obtained by any well-known method. For example, the copolymers can be neutralized using formates, acetates, nitrates, carbonates, hydrogencarbonates, oxides, hydroxides or alkoxides of the metal ions.
The copolymers and neutralized products thereof serving as component (A) are available in the marketplace. The olefin-unsaturated carboxylic acid copolymer is commercially available, for example, under the trade name of Nucrel 1560, 1214 and 1035 from DuPont-Mitsui Polychemicals Co., Ltd. and ESCOR 5200, 5100 and 5000 from EXXONMOBIL Chemical. The olefin-unsaturated carboxylic acid-unsaturated carboxylate copolymer is commercially available, for example, under the trade name of Nucrel AN4311 and AN4318 from DuPont-Mitsui Polychemicals Co., Ltd. and ESCOR ATX325, ATX320 and ATX310 from EXXONMOBIL Chemical. Also the metal-neutralized olefin-unsaturated carboxylic acid copolymer is commercially available, for example, under the trade name of Himilan 1554, 1557, 1601, 1605, 1706 and AM7311 from DuPont-Mitsui Polychemicals Co., Ltd., and Surlyn 7930 from E. I. Dupont. The metal-neutralized olefin-unsaturated carboxylic acid-unsaturated carboxylate copolymer is commercially available, for example, under the trade name of Himilan 1855, 1856, and AM7316 from DuPont-Mitsui Polychemicals Co., Ltd., Surlyn 6320, 8320, 9320 and 8120 from E. I. Dupont, and Iotek 7510 an
Ichikawa Yasushi
Takesue Rinya
LandOfFree
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