JPS60106469A - Solid state golf ball - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has three-dimensional mesh cross-linked golf balls for use in competitions and practice. Balls) are divided into three types.

In general, balls with a triple structure have poor cut resistance in irons, and balls with a double structure also tend to get scratched easily because the Surlyn resin in the skin is thermoplastic, and the fur tends to break easily. It is a known fact that it was difficult to achieve both distance and durability.

In recent years, solid golf balls have been used for competitions or practice, but these solid golf balls, for example, as disclosed in Japanese Patent Publication No. 55-19615, have improved their impact resistance over time. Its properties had significantly decreased, and cracking had occurred over time. Also, JP-A-54-6
In the 01J88 publication, the impact resistance was improved by a rubber composition, but the present invention is economically unfavorable in the production and kneading of MG rubber. It was invented for the purpose of solving the problem of.

In particular, the drawbacks of cis 1.4 polybutadiene, which deteriorates over time and has poor impact resistance, have been overcome by the combination of natural rubber, ethylene propylene rubber, and ethylene vinyl acetate copolymer, resulting in improved impact resistance. .

The present invention first uses (a) 70 to 90% by weight polybutadiene having at least 85% cis structure, preferably 97% or more cis 1.4 structure, and (b) 8 to 15% by weight natural rubber. %, (C) ethylene propylene rubber 2-5 type open%, Sarani (C1) ethylene vinyl acetate copolymer, preferably! [Total amount of rubber composition composed of 85% or more vinyl content and 5 to 10% by weight (a+b+C+cl, l 100
(e) 20 to 45 parts by weight of a divalent metal oxide, preferably zinc oxide, and zinc oxide other than that used for neutralizing methacrylic acid to adjust the weight of the golf ball. <f) Unsaturated monocarboxylic acids having 8 to 4 carbon atoms, preferably methacrylic acid, used for
By using a compounded composition (a + b + o - 14 + 6 + f 10 g) consisting of 6 to 32 parts by weight and 3 to 5 parts by weight of (g) organic peroxide, excellent impact resistance and ball initial velocity are achieved by crosslinking the two-dimensional network. The invention, which is an improved solid state golf ball with increased flight distance, further comprises (a) 1 having a cis structure of at least 85%;
4 polybutadiene 70-90% by weight, (b) natural rubber 8-15% by weight, (○j ethylene propylene rubber 2-5% by weight)
% by weight, and further (d) ethylene vinyl acetate copolymer 5
~10% by weight of the rubber composition (a
+b+c+a 1100 parts by weight, (032-45 parts by weight of tetravalent metal oxide, (f) 8-4 carbon atoms
26 to 82 parts by weight of an unsaturated monocarboxylic acid having
By using three-dimensional network cross-linking, excellent impact resistance and ball initial velocity are improved, resulting in a flight distance of (4g + h).
) It is a solid state golf ball that has been improved and satisfied in all aspects.

The main configuration and its numerical limitations will now be explained.

If the natural rubber (b) is less than 8% by weight, the impact resistance will be poor, and if it exceeds 15% by weight, it will be too soft to be used. (○) If the ethylene propylene rubber is less than 2% by weight, the impact feel will be poor, and if it exceeds 5% by weight, the impact property will be poor. (d
) If the ethylene vinyl acetate copolymer content is less than 5% by weight, the impact sound will be poor, and if it exceeds 10% by weight, the sound will be too high, which is not preferable.

If the above-mentioned (e) di- to tetravalent metal oxide is less than 20 parts by weight, both hardness and weight will be insufficient, and the ball performance will also deteriorate.
If it exceeds the layered portion, it becomes hard and overweight, both of which are undesirable.

(f) Examples of unsaturated monocarboxylic acids having 8 to 4 carbon atoms include OH and -0ζ products. [Here, R is a hydrogen atom R' is a hydrogen atom or an ethyl group]2
If it is less than 6 parts by weight, an appropriate compression value will not be obtained, and if it exceeds 32 parts by weight, the elasticity will decrease and the impact sound will be low, which is not preferable.

(1,1-bis(t-butylperoxy)3,3,5-)limethylcyclohexane and the like are used as the GL organic peroxide. If it is less than 8 parts by weight, the crosslinking effect will be insufficient;
If it exceeds 5 parts, it becomes brittle and is not preferred, including economical issues.

(hJ organic accelerator thiazole type) If the amount is less than 1 part by weight, no significant effect will be observed, and if it exceeds 5 parts by weight, it will become soft and undesirable. .

The compound composition composed of the above is cross-linked into a three-dimensional network, resulting in extremely high repulsion properties, excellent impact resistance, improved ball initial velocity, increased flight distance, and durability that is especially strong compared to competition balls. It is useful and well received as a practice ball that is in demand.

First, the cis content of the cis-1.4 polybutadiene in the rubber composition is 85% or more, preferably 97% or more, which guarantees high repulsion, but it is not inventive because it has poor impact resistance and cuttability. Cuttability is improved by combining an ethylene vinyl acetate copolymer with a vinyl acetate content of 35% or more. Ethylene-vinyl acetate copolymer increases strength and improves cutability, which causes poor elongation and high-pitched sound, which is corrected with ethylene propylene rubber.

Secondly, the organic accelerator thiazoles in the formulation, especially
2-mercaptobenzothiazole (for example, Sanshin Kagaku (
Co., Ltd. product name Sunseller M, etc. can be used.

), up until now crosslinking was caused by the organic peroxide alone, resulting in variations in hardness and impact resistance, resulting in lack of crosslinking instability, but with the addition of 2-mercaptobenzothiazole, the degree of crosslinking of the crosslinked product has been made uniform. Improvements have been made in hardness, natural rebound and impact properties. 2-Mercaptobenzothiazole M has the characteristic of softening, but it can be corrected with 1,1-bis(t-butylperoxy)a, δ, 5-trimethylcyclohexane, etc.

A solid state golf ball according to the invention is manufactured as follows.

Blend (7) of rubbery composition (a+b+c-+4) (pine) Rubber and zinc oxide adjusted to be continuous are thoroughly kneaded for about 10 minutes at a temperature of 80 to 120°C using a Banbury mixer or mixing roll. Zinc oxide power (a+b+c +a
methacrylic acid is gradually added to the blended rubber in a well-dispersed state, and the zinc oxide and methacrylic acid are reacted in the rubber to form a metal salt.

Then, 1.
Add 1-bis(t-butylperoxy) 3°815 trimethylcyclohexane and 2-mercaptobenzothiazole M and knead for about 5 minutes until uniform.

The rubber composition thus obtained is heated and molded in a desired mold to obtain a solid state golf ball.

The crosslinking temperature is 140°C-180°C and the crosslinking time is 10-8
It is 0 minutes.

Next, examples according to the invention and their physical properties will be shown.

Regarding the crosslinking temperature, the balls were crosslinked at 160° C. for 12 minutes.

(8) Breaking value (impact resistance) is the number of times a 5 kg weight is dropped from a height of 50 cIrL onto a flat golf ball (equivalent to a driver) placed on a flat iron plate until it breaks, indicating the number of test pieces. This is the average value of 20 items. Also, for balls that did not break after 500 runs, the number of drops was 0 until 500 runs.

Repulsion elasticity is expressed as the value (%) of the bounce of a ball dropped from a height of 120 mm onto a 25 mm thick iron plate.

The compression value is determined by a compression meter using the USA established stroke method called (Accu-TEST).

The initial velocity of the ball was expressed in m/sea when the ball was hit at a head speed of 50 m/s using a golf hitting testing machine.

Table ■ Table ■ 2 ( ) ( ] 8 ) That is, the coating 1 is a comparison of polymers, Table M is a comparison of methacrylic acid, and Table V is a comparison of organic accelerator M.

The remarkable effects of the present invention were recognized from the above Examples and Comparative Examples.

Patent applicant: Hayakawa Rubber Co., Ltd.

Claims (1)

[Claims] L (a) 1 having at least 85% cis structure
, 4 polybutadiene 70-90% by weight, (b) natural rubber 8-15% by weight, (O) ethylene propylene rubber 2-5
% by weight, and further (d) ethylene vinyl acetate copolymer 5
~10% by weight of the total rubbery composition (a
-4-b +O+a) For 100 parts by weight, (e)
20-45 parts by weight of di- to tetravalent metal oxide, (f) 26-82 parts of unsaturated monocarboxylic acid having 8-4 carbon atoms;
By using a compounded composition (a+b+c+cl+e+f+g) containing 8 to 5 parts by weight of organic peroxide (g1) and crosslinking the three-dimensional network, excellent impact resistance and ball initial velocity are improved, resulting in increased flight distance. A solid state golf ball characterized in that: (a) 1 having a cis structure of at least 85%;
, 4 polybutadiene 70-90% by weight, (b) natural comb 8-15% by weight, (C) ethylene propylene L/Nco A
2 to 5% by weight, and further 5 to 10% by weight of (d) ethylene vinyl acetate copolymer.
8) 20-45 parts by weight of di- to tetravalent metal oxide, (f)
Unsaturated monocarboxylic acids with 8 to 4 carbon atoms 26 to
82 parts by weight, (g) 8 to 5 parts by weight of an organic peroxide, and (h) 1 to 5 parts by weight of an organic accelerator thiazole are added (a+b+c+4+e+f+g+h) for three-dimensional network crosslinking. A solid-state golf ball that is characterized by increased stickiness and excellent impact resistance, as well as improved ball initial velocity and increased flight distance.