JPH09225065A - Resin composition for golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for golf balls which is flexible and superior in repulsion and durability. SOLUTION: Golf balls which are flexible and superior in repulsion and durability are provided by forming the covers of golf balls by a composition made of a fused mixture of an ionomer resin, a partial saponified substance of an ethylene/unsaturated carboxyic ester copolymer and a polymer having a maleic anhydride group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for golf balls which is flexible and has excellent resilience and durability.

[0002]

2. Description of the Related Art Conventionally, an ionomer resin has been widely used as a golf ball cover material because it has excellent resilience and durability. But,
A golf ball using this ionomer resin as a cover material has drawbacks that it has a hard hitting feel and poor controllability. Therefore, there is a demand for a golf ball having improved impact feel and controllability without impairing the advantages of the ionomer resin-covered golf ball.

So far, for example, a mixture of a conventional ionomer resin and a soft ionomer resin which is a sodium salt or a zinc salt of an ethylene / (meth) acrylic acid / (meth) acrylic acid ester terpolymer. (JP-A-1-808577, JP-A-5-3931), a mixture of an ionomer resin and a partially saponified ethylene / unsaturated carboxylic acid ester copolymer (JP-A-5-345051, Kaihei 6-313075
It has been attempted to soften the cover and improve the feel of hitting and the controllability.

[0004]

However, when a cover material mixed with a soft ionomer resin is used, the resilience is lowered due to the softening of the cover. Further, since the compatibility between the conventional ionomer resin and the soft ionomer resin is not good, there is a problem that the durability is lowered and the cover surface of the golf ball is fluffed to cause poor appearance.

Even when a cover material mixed with a partially saponified ethylene / unsaturated carboxylic acid ester copolymer is used, the compatibility between the ionomer resin and the partially saponified ethylene / unsaturated carboxylic acid ester copolymer. Is not good, there are problems such as deterioration of durability and occurrence of defective appearance.

The present invention has been made in order to solve the above problems, and a phase of an ionomer resin and a partially saponified ethylene / unsaturated carboxylic acid ester copolymer is formed by a polymer having a maleic anhydride group. It is an object of the present invention to provide a golf ball resin composition having improved solubility, flexibility, and excellent resilience and durability.

[0007]

To solve the above problems, the present invention provides an ionomer resin, a partially saponified ethylene / unsaturated carboxylic acid ester copolymer, and a polymer having a maleic anhydride group. And a molten mixture of

In the present invention, the ionomer resin is preferably a resin obtained by neutralizing a part of the carboxyl groups of the ethylene / (meth) acrylic acid copolymer with a metal ion or a mixture thereof.

As the ionomer resin, a mixture of an ionomer resin neutralized with an alkali metal ion such as lithium, sodium and potassium and an ionomer resin neutralized with a divalent metal ion such as zinc, magnesium and calcium is combined. It is preferable to use. Examples are combinations of at least one alkali metal ion and at least one divalent metal ion such as lithium / zinc, sodium / zinc, potassium / magnesium, lithium / sodium / zinc, etc. Mix two or more different ionomer resins,
Combinations of two or more metal ions can be obtained.

As the ionomer resin, "SURLYN" (trade name) manufactured by DuPont, USA, and "HIMILAN" manufactured by DuPont Mitsui Polychemical Co., Ltd.
) ”(Brand name),“ IOTEK (IOTEK
) ”(Trade name) is commercially available. “Surrin” and “Himilan” are ionomer resins of ethylene / methacrylic acid copolymer system, and “IOTEC”
Is an ionomer resin of ethylene-acrylic acid copolymer system.

Such an ionomer resin has a Shore D hardness of 60 or more in order not to reduce the resilience, and it does not deteriorate the moldability.
It is preferable that the MFR under g load is 0.7 dg / min or more.

The partially saponified ethylene / unsaturated carboxylic acid ester copolymer is generally obtained by saponifying part of the ester component of the ethylene / unsaturated carboxylic acid ester copolymer with caustic alkali. As the unsaturated carboxylic acid ester in the saturated carboxylic acid ester copolymer, acrylic acid or methacrylic acid methyl,
Esters such as ethyl, n-butyl and isobutyl are exemplified.

The partially saponified ethylene / unsaturated carboxylic acid ester copolymer is for obtaining flexibility without lowering the resilience and has a Shore D hardness of 1
It is preferably 5 to 45.

The polymer having a maleic anhydride group is a copolymer having maleic anhydride as a copolymerization component, a polymer modified with maleic anhydride, and the like, and includes olefins such as ethylene, propylene, 1-butene and isobutylene. Olefin-based polymer as a component is preferable, ethylene / ethyl acrylate / maleic anhydride terpolymer,
Examples thereof include maleic anhydride-modified ethylene-propylene copolymer, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene and the like.

The maleic anhydride group-containing polymer is used to improve the compatibility between the ionomer resin and the partially saponified ethylene / unsaturated carboxylic acid ester copolymer by the maleic anhydride group. .

In the present invention, the amount of the ionomer resin and the partially saponified ethylene / unsaturated carboxylic acid ester copolymer is 100 parts by weight, and the ionomer resin 40 is used.
The mixing ratio is preferably in the range of ˜90 parts by weight, 10 to 60 parts by weight of partially saponified ethylene / unsaturated carboxylic acid ester copolymer, and 1 to 30 parts by weight of the polymer having a maleic anhydride group. If the mixing ratio of the ionomer resin is low and the mixing ratio of the partially saponified ethylene / unsaturated carboxylic acid ester copolymer is high, the resilience and durability are lowered.
On the other hand, the mixing ratio of ionomer resin is high,
When the mixing ratio of the partially saponified unsaturated carboxylic acid ester copolymer is small, flexibility cannot be obtained. Further, when the mixing ratio of the polymer having a maleic anhydride group is low, the effect of improving the compatibility cannot be obtained, and when the mixing ratio is high,
Repulsion is reduced.

The golf ball resin composition of the present invention is generally produced by melting and mixing the three components using a Banbury mixer for thermoplastic resin, an extruder or the like, but the effects of the present invention are impaired. In addition to the three components, other polymers can be mixed as long as they are within the range, and if necessary, colorants, optical brighteners, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, dispersants, etc. Additives can be mixed. It should be noted that the molten mixture means that it is produced by melt mixing, and does not mean that it is a molten mixture.

The resin composition of the present invention can be used as a material for a cover of a corfu ball, an intermediate layer of a solid golf ball having three or more layers, and the like.

[0019]

Example A rubber composition having the composition shown in Table 1 was heated and pressed in a core mold to produce a solid core having a diameter of 38.3 mm.

Next, the solid core was coated with a resin composition having the composition shown in Table 2 by an injection molding method, and after molding the cover, polishing and coating were performed to obtain a two-piece solid golf ball having a diameter of 42.7 mm. . The results of measuring and evaluating the characteristics of each golf ball obtained are shown in Table 2.

As a result of the evaluation, in Example 1, by adding the polymer having a maleic anhydride group (Umex 2000), higher durability than Comparative Examples 1 and 2 was obtained.
In Examples 2 to 4, partially saponified products of the above-mentioned polymer and ethylene / unsaturated carboxylic acid ester copolymer (SA4
By increasing the mixing ratio of 20) as compared with Example 1,
The cover was made softer than Comparative Examples 1 and 2, and the durability was further improved. In Example 5, by increasing the mixing ratio of the partially saponified product as compared with Examples 1 to 4 and using Modiper A8200 as a polymer, Example 2 was used.
It was possible to make the cover more flexible than in Examples 1 to 4 while maintaining the same durability. In Example 6, by increasing the amount of the partially saponified product and the polymer (Modiper A8200) as compared with Example 5, it was possible to further improve the flexibility and durability of the cover.

[0022]

[Table 1]

[0023]

[Table 2]

* 1: Trade name, sodium ion neutralization type ionomer resin manufactured by Mitsui DuPont Polychemical Co., Ltd., Shore D hardness 65, MFR 2.8 dg / mi
n. * 2: Trade name, zinc ion neutralized type ionomer resin manufactured by Mitsui DuPont Polychemical Co., Ltd., Shore D hardness 64, MFR 0.7 dg / min. * 3: Trade name, sodium ion partially saponified ethylene-ethyl acrylate copolymer manufactured by Mitsui DuPont Polychemical Co., Ltd., Shore D hardness 28. * 4: Brand name, maleic anhydride-modified polyethylene manufactured by Sanyo Kasei Co., Ltd. * 5: A polymer obtained by graft-polymerizing methyl methacrylate onto an ethylene / ethyl acrylate / maleic anhydride terpolymer manufactured by NOF CORPORATION. * 6: Swing robot device is used, wood 1
The initial speed of the golf ball when hit by the No. club (# 1), which is an index with Comparative Example 1 being 100. * 7: Index where durability of the golf ball of Comparative Example 1 is 100. * 8: A cover surface after surface grinding was visually evaluated at the time of manufacturing a golf ball, and “⊚: extremely good,
◯: good, Δ: somewhat bad, x: bad ”.

[0025]

According to the present invention, the maleic anhydride group of the polymer having a maleic anhydride group improves the compatibility between the ionomer resin and the partially saponified ethylene / unsaturated carboxylic acid ester copolymer. A resin composition for a golf ball that is flexible, and has excellent resilience and durability can be provided. Further, when used as a cover material for a golf ball, it is possible to provide a golf ball resin composition which does not cause a defective appearance due to fluffing on the cover surface.

Claims (9)

[Claims] 1. A resin composition for a golf ball, which is a melt mixture of an ionomer resin, a partially saponified ethylene / unsaturated carboxylic acid ester copolymer, and a polymer having a maleic anhydride group. . 2. The golf ball resin composition according to claim 1, wherein the ionomer resin is a resin obtained by neutralizing a part of carboxyl groups of an ethylene / (meth) acrylic acid copolymer with metal ions, or A resin composition for a golf ball, which is a mixture thereof. 3. The golf ball resin composition according to claim 1, wherein the ionomer resin is an ionomer resin neutralized with an alkali metal ion such as lithium, sodium, or potassium, and a divalent zinc, magnesium, calcium, or the like. A resin composition for a golf ball, which is a mixture with an ionomer resin neutralized with a metal ion. 4. The golf ball resin composition according to claim 1, wherein the ionomer resin has a Shore D hardness of 60 or more, and an MFR of 0.7 at 190 ° C. and a load of 2160 g.
A resin composition for a golf ball, which has a dg / min or more. 5. The golf ball resin composition according to claim 1, wherein the unsaturated carboxylic acid ester in the ethylene / unsaturated carboxylic acid ester copolymer is acrylic acid or methacrylic acid methyl, ethyl, n-butyl or A resin composition for a golf ball, which is an ester such as isobutyl. 6. The golf ball resin composition according to claim 1, wherein the partially saponified ethylene / unsaturated carboxylic acid ester copolymer has a Shore D hardness of 15 to 45. Resin composition. 7. The golf ball resin composition according to claim 1, wherein the polymer having a maleic anhydride group is an olefin polymer containing an olefin such as ethylene, propylene, 1-butene or isobutylene. A resin composition for golf balls, comprising: 8. The golf ball resin composition according to claim 1, wherein the polymer having a maleic anhydride group is an ethylene / ethyl acrylate / maleic anhydride terpolymer, a maleic anhydride-modified ethylene propylene copolymer. A resin composition for a golf ball, which is a coalesced product, a maleic anhydride-modified polyethylene, or a maleic anhydride-modified polypropylene. 9. The golf ball resin composition according to claim 1, wherein the total amount of the ionomer resin and the partially saponified ethylene / unsaturated carboxylic acid ester copolymer is 100 parts by weight, and 40 to 90 parts by weight of the ionomer resin. , Partially saponified ethylene / unsaturated carboxylic acid ester copolymer 10
60 parts by weight, polymers 1 to 3 having maleic anhydride groups
A golf ball resin composition, wherein the mixing ratio is in the range of 0 parts by weight.