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
2001-02-05
2003-06-17
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...
C525S090000, C525S09200D, C473S372000, C473S373000, C473S374000, C473S378000, C473S385000
Reexamination Certificate
active
06579939
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a golf ball which is capable of increasing the flying distance of the ball, improving the ball hitting feeling, and enhancing the durability of the ball.
A polyester block copolymer containing a crystalline aromatic polyester unit such as polybutylene terephthalate, as a hard segment and an aliphatic polyether unit such as poly(alkylene oxide) glycol and/or an aliphatic polyester unit such as polylactone, as a soft segment, is excellent in mechanical properties such as strength, impact resistance, elastic recovery, and flexibility and also excellent in low temperature/high temperature characteristics, and is good in thermoplasticity to be thereby easily moldable. Such a polyester block copolymer has become a focus of attention as a resin for a golf ball, for example, as disclosed in Japanese Patent Laid-open No. Hei 7-24084.
The above-described polyester block copolymer having excellent physical properties, however, is disadvantageous in that as the hardness thereof becomes higher, the mechanical properties such as impact resilience, strength, and impact resistance, and the low temperature characteristics become lower, and therefore, to increase the flying distance of a golf ball formed by using the polyester block copolymer, it has been required to further improve the physical properties of the polyester block copolymer.
On the other hand, an ionomer resin produced by neutralizing a copolymer containing &agr;-olefine and &agr;,&bgr;-unsaturated carboxylic acid with univalent, divalent, or trivalent metal ions is thermoplastic and thereby easily moldable, and further significantly tough to be thereby less broken even if being largely deformed by a high speed impact. The high toughness of the ionomer resin is advantageous in improving the abrasion resistance of a golf ball formed by using the ionomer resin and in enhancing the durability of the golf ball against repeated hitting thereof. In actual, the ionomer resin having the above excellent properties has been used as a cover material for golf balls over the years.
The ionomer resin, however, is insufficient in flexibility, and gives a rigid feeling to a player upon hitting a golf ball using the ionomer resin as a cover material.
To cope with such an inconvenience, there has been proposed a softened ionomer resin suitable as a resin composition for a golf ball, wherein the ionomer resin is provided by neutralizing a copolymer containing &agr;-olefine, &agr;,&bgr;-unsaturated carboxylic acid, and &agr;,&bgr;-unsaturated carboxylate with univalent, divalent, or trivalent metal ions.
The softened ionomer resin, however, is poor in impact resilience and low temperature characteristic, and is therefore required to be further improved.
An attempt has been made to produce a golf ball using a resin composition obtained by mixing a polyester block copolymer with an ionomer resin for compensating the disadvantages of the polyester block copolymer and the ionomer resin with each other. These golf balls, each using a resin composition obtained by mixing a polyester block copolymer and an ionomer resin, has been proposed, for example, in Japanese Patent Laid-open Nos. Sho 56-83367 and Sho 62-275480. According to such a resin composition, since the polyester block copolymer excellent in flexibility and impact resilience is mixed with the ionomer resin poor in flexibility but excellent in toughness and impact resilience, it is possible to make effective use of the excellent performances of both the polyester block copolymer and the ionomer resin, and particularly to improve the impact resilience.
The above-described golf ball material, that is, the mixture of the polyester block copolymer and the ionomer resin, however, has a problem. Namely, since the polyester block copolymer and the ionomer resin are not excellent in compatibility so much, the golf ball material has an uneven morphology, with a result that the resin material is easy to orient upon injection molding thereof, tending to cause laminar peeling and also failing to obtain a sufficient durability of a golf ball formed by using the resin material against repeated hitting of the golf ball.
An attempt has been made to further improve the above-described resin composition. For example, a golf ball core material composed of a resin composition containing a polyester block copolymer, an ionomer resin, and an epoxy-containing compound has been proposed in WO92/12206, and a golf ball using a resin composition containing a polyester block copolymer, an ionomer resin, and an epoxidated diene based block copolymer has been proposed in Japanese Patent Laid-open No. Hei 9-176429.
Each of the resin compositions disclosed in the above-described documents is satisfactory to improve the laminar peeling by enhancing the compatibility of the polyester block copolymer with the ionomer resin, and therefore, becomes a resin composition excellent in flexibility and impact resilience suitable for a golf ball; however, such a resin composition has another problem that since it contains the epoxy-containing copolymer, the melt viscosity of the resin composition becomes higher, with a result that the resin composition is suitable for both extrusion molding and blow molding but unsuitable for injection molding generally used for molding a golf ball.
A thermoplastic polymer composition containing a polyester based resin, an addition polymerization based block copolymer, a polyester based block copolymer, and an ionomer resin, which is usable as a golf ball cover material, has been disclosed in Japanese Patent Laid-open No. Hei 10-147690.
The above-described thermoplastic polymer composition is a hard material being high in tensile strength and bending strength but is very high in stiffness modulus, and therefore, is different from a material having a high flexibility and a high impact resilience, such as rubber. Further, the thermoplastic polymer composition cannot exhibit a sufficient durability of a golf ball formed by using the resin composition against repeated hitting of the ball, which durability is required for a golf ball cover material. Accordingly, the thermoplastic polymer composition is unsuitable as the golf ball material.
A thermoplastic resin composition for a golf ball containing an ionomer resin, a polyester based thermoplastic elastomer, and a styrene based block copolymer has been disclosed in Japanese Patent Laid-open No. Hei 11-342229.
Such a thermoplastic resin composition for a golf ball is excellent in flexibility and elastic recovery; however, it is also insufficient in durability of a golf ball formed by using the thermoplastic resin composition against repeated hitting of the ball, which durability is required for a golf ball cover material.
As described above, at present, there does not exist a resin composition for a golf ball, which has a high flexibility and a high impact resilience, and also has a high toughness, particularly, a high flexural fatigue resistance and a high tear resistance, and which is good in melt flowability and thereby suitable for injection molding with less laminar peeling after molding.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a golf ball which is capable of increasing the flying distance of the ball, improving the ball hitting feeling, and enhancing the durability of the ball.
To achieve the above object, the present inventors have made studies to develop a new thermoplastic resin composition for a golf ball, which is high in rupture strength and impact strength, has properties similar to those of rubber, such as a suitable flexibility and a high impact resilience, and is excellent in durability, particularly, flexural fatigue resistance and tear strength, and which is good in melt flowability and thereby suitable for injection molding with less laminar peeling after molding, by compensating the disadvantages of a polyester block copolymer and an ionomer resin used for a prior art resin composition for a golf ball with each other, and eventually found that a
Furuta Yoko
Ichikawa Yasushi
Takehana Eiji
Takesue Rinya
Bridgestone Sports Co. Ltd.
Buttner David J.
Sughrue & Mion, PLLC
LandOfFree
Golf ball does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Golf ball, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Golf ball will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3088030