JPS5937961A - Two-piece solid 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 relates to two-piece solid golf balls.

A two-piece solid golf ball developed to improve the poor durability of thread-wound golf balls, that is, a solid golf ball consisting of an integrally molded solid core with high repulsion and a cover with excellent cut resistance, is also expected. Rebound elasticity (large initial ball velocity at impact)
Not only does it not show durability, but also the feel when hitting (
The impact feel is also poor, and it has not yet become fully popular.

- The present invention provides a two-piece non-solid golf ball that has excellent rebound properties comparable to those of a golf ball, and has extremely good durability and feel when hit.

That is, in the present invention, a composition containing 100 parts by weight of base rubber, 25 to 40 parts by weight of a metal or unsaturated fatty acid, 15 to 25 parts by weight of zinc oxide, and 1 to 5 parts by weight of peroxide is heated. A two-pis made by covering a hardened solid core with a diameter of 37.9 to 38.5 mm with a cover of 2.10 to 2.4 Qtttm in thickness, which is mainly made of ionomer resin with a Shore D hardness of 65 or more. Regarding solid golf balls.

The base rubber used in the present invention is polybutadiene rubber,
Examples include styrene-butadiene rubber, natural comb, high styrene resin, etc. Polybutadiene rubber, especially cis-1,
4-polybutadiene rubber is preferred.

Examples of metal salts of unsaturated fatty acids used in the present invention include zinc salts and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms, such as acrylic acid and methacrylic acid, with zinc acrylate being particularly preferred.

The metal salt of unsaturated fatty acid is used in an amount of 25 to 40 parts by weight per 100 parts by weight of the base rubber. If the amount of the metal salt is less than 25 parts by weight, sufficient hardness cannot be obtained and the initial velocity of the ball at impact will be low, and if it is more than 40 parts by weight, the ball will be too hard to be practical. .

Zinc oxide is used as a weight adjuster, and its amount is usually 15 to 25 parts by weight per 100 parts by weight of the base rubber.

Other conventional fillers, such as barium sulfate, calcium carbonate, silica, etc., may be used as appropriate weight regulators.

Examples of crosslinking agents used to impart optimum hardness to the solid core include peroxides such as dicumyl peroxide and azo compounds such as azobisisobutylnitrile, with dicumyl peroxide being particularly preferred.

The amount of peroxide compounded is usually 1 to 5 parts by weight per 100 parts by weight of the base rubber, and if a crosslinking agent outside this range is used, it will be difficult to obtain a core with optimum hardness.

The core composition obtained by blending the above components is kneaded using a conventional mixer, such as a Banbury mixer or a roll, and then press-molded in a conventional manner at -C approximately 140 to 170°C to meet the specifications. It is an integrally molded solid core.

The present invention was made primarily for large-sized golf balls (diameter: approximately 42.7 mm), and the size of the solid core obtained as described above depends on the composition, hardness, thickness, etc. of the cover described below. The diameter is 37.
The cover covering the O solid core, which is a sphere of 9 to 38.5 mm, is mainly made of ionomer resin, and may also contain an inorganic filler such as titanium dioxide, zinc oxide, etc. for the purpose of coloring if necessary. .Preferred ionomer □−
Ct monoolefins and unsaturated mono- or dicarboxylic acids having 3 to 8 carbon atoms and their esters)
It is a thermoplastic resin in which a crossmetal bond is imparted to a polymer (containing 4 to 30% by weight of unsaturated mono- or dicarboxylic acids and/or their esters) with at least one member selected from the group consisting of: The optimum hardness for such an ionomer resin is a Shore D hardness of 65 or more.

The thickness of the cup made mainly of ionomer resin (Shore D hardness 65 or more) is set to 2.10 to 2.40 mm in consideration of the diameter of the solenoid core described above. When the thickness of the cover is 2.10 to 2.40 on, the initial velocity of the resulting ball is significantly improved.

The method of coating the solid core with the cover is special! Although not limited to this, usually the solid core is wrapped with two covers that have been formed into hemispherical shells 3b in advance, and pressure molded at about 170° C. for 2 minutes. Alternatively, the cover composition may be injection molded to enclose the solid core.

The two-piece solid golf ball obtained as described above is a golf ball that has improved rebound resilience (initial velocity) and durability, as well as poor feel when hitting, which were insufficient in conventional products of the same type. It is.

Hereinafter, the present invention will be explained by examples.

Examples 1 to 5 and Comparative Examples 1 to 4 Cis-1,4-polybutadiene, zinc acrylate, zinc oxide, and dicumyl peroxide were kneaded using a mixed wire roll according to the formulation shown in Table 1, and the mixture was kneaded at 150°C for 30 minutes. A solid core was prepared by pressure molding for minutes.

On the other hand, a cover made of ionomer resin mixed with titanium dioxide was molded into a hemispherical shell shape.

The above solid core is wrapped with two hemispherical shell-like covers, and approximately 1
Pressure molded at 70℃ for 2 minutes to form a two-piece with a diameter of approximately 42.7cm.
Peace Solid golf balls were manufactured.

Table 1 shows the physical properties of the golf ball obtained.

Table-1 1) BRQI manufactured by Japan Synthetic Rubber Company 2) Surlyn 1707 manufactured by DuPont Company 3) Surlyn 1605 manufactured by DuPont Company 4) Surlyn 1706 manufactured by DuPont Company 5) Surlyn l601 manufactured by DuPont Company 6) Surlyn 1557 manufactured by DuPont Company 7) True Temper Measured using a swing robot made by the company (head speed 45.1±0.2 m7 seconds, ball temperature 25°C).

8) The impact resistance of the ball obtained in Comparative Example 1 is 1
Relative value when set to 00.

As is clear from Table 1, the two-piece solid golf ball according to the present invention is a well-balanced golf ball with a high initial velocity and excellent durability.

As shown in Comparative Examples 1 and 2, even if the cover hardness is high, if the diameter of the solid core is not appropriate, the initial velocity of the ball will be low.

Furthermore, as shown in Comparative Examples 3 and 4, even if the diameter of the solid core is appropriate, if the cover hardness is low, the initial velocity of the ball will be significantly low.

Patent applicant: Sumitomo Rubber Industries, Ltd. Representative Patent Attorney Hao Aoyama and 1 other person

Claims (1)

[Claims] 1. 100 parts by weight of base rubber, 25 parts by weight of metal salt of unsaturated fatty acid
A solid core with a diameter of 37.9 to 38.5 mm obtained by heating and curing a composition containing ~40 parts by weight, 15 to 25 parts by weight of zinc oxide, and 1 to 5 parts by weight of peroxide was A two-piece solid golf ball covered with a cover having a thickness of 2.10 to 2.40 mm and mainly made of an ionomer resin of 65 or higher. 2. The solid golf ball according to item 1, wherein the base rubber is cis-1,4-polybutadiene rubber. 3. The first metal salt of unsaturated fatty acid is zinc acrylate
The solid golf ball described in Section 1. 4. The solid golf ball according to item 1, wherein the crosslinking agent is dicumyl peroxide.