JPS6264378A - Cover composition for 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 (Field of Industrial Application) The present invention relates to a golf ball cover composition, and particularly to a golf ball cover composition using balata (transpolyisoprene).

(Prior Art) Components used in golf pole covers generally include ionomer resins and balata.

Golf balls using ionomer resin for the cover are strong and have high cut resistance (difficulty in cutting when you miss a shot), but the impact when hit is large and the feel of the ball is poor.

On the other hand, golf poles for use with balata covers generally have a good feel when hit, have a larger deformation of the pole when hit, and have a longer contact time than golf balls using ionomer resin covers.

In addition, it has the advantage that the impact force when hitting the ball is small, and furthermore, it has good spin performance, and because it generates a lot of backspin when hitting the ball, it is easy to stop the pole on the green. Therefore, Balata cover golf poles are considered as the highest quality golf poles.
It is mainly used by advanced professional golfers and amateur golfers.

(Problems to be Solved by the Invention) However, since balata softens slightly at temperatures above 30°C, when the balls of the balata cover are used during high temperatures in summer, the cut resistance of the cover is further reduced.

In order to solve this drawback, it has been proposed, for example, to add high-styrene resin, white carbon, etc. to the balata cover as a reinforcing material to increase hardness and cut resistance ("Introduction to New Rubber Technology" p. 238 or Tokuko Sho 5).
7-31744).

However, although the cut resistance is improved by blending these, the repulsion characteristics of the ball are reduced.

In addition, ionomer resin (
In particular, it has been proposed to blend a copolymer of ethylene and methacrylic acid (neutralized with a metal salt) into balata (Japanese Patent Laid-Open No. 115334/1983). However, due to the poor compatibility of the ionomer resin with the balata, the mechanical strength is reduced. In addition, the melt viscosity of the resin increases during ball manufacture, requiring pressing at high temperatures, which results in deterioration of the thread rubber layer and a decline in ball hardness and rebound performance.

Furthermore, it is possible to add calcium carbonate, heart clay, hydrated licorice, magnesium silicate, stinrite mica, etc. to balata as an inorganic reinforcing material, but if the hli strength is high, the Mooney viscosity will become too high, making it difficult to process. If the Mooney viscosity is not increased significantly, a large amount must be added, and the repulsion characteristics of the golf ball are deteriorated.

Therefore, there are no defects during manufacturing, and the repulsion characteristics are good.
There is a strong desire to develop a balata cover with excellent spin performance and cut resistance.

(Means for Solving the Problems) The present inventors have discovered that a cover material that solves the above problems can be obtained by mixing fine fibers having an amide group into a balata cover material.

That is, the present invention provides a golf ball cover composition comprising a cover material containing transpolyisoprene as a main component and fine fibers having an amide group.

As the balata, a natural or synthetic trans-1,4-polyisoprene cover material conventionally used in golf balls is used.

In the present invention, fine fibers having an amide group are blended into the balata material. Examples of fine fibers having an amide group include nylon fibers (nylon 6, nylon 61
0, nylon +2, nylon 6+1. Melting point of nylon 612 etc. 190-225°C, preferably 200-220°C
Norano), or block copolymers of nylon and other polymers (for example, block copolymers of nylon and liquid diene rubber). Fine fibers have an average diameter of 0.
05 to 0.8μ, and the shortest fiber length in a circular cross section is preferably 1μ or more, preferably 8μ or more.

The fine fibers are generally incorporated into the balata cover material in a premixed mixture with other rubber components that are compatible with the transpolyisoprene. Examples of other rubber components that are compatible with trans-polyisoprene include natural rubber, styrene-butadiene rubber, 1.4-polybutadiene, and trans-polyisoprene.
1,11-polybutadiene, 1,2-polybutadiene,
EPDM.

Examples include Nl3R. Among these, natural rubber is most preferred because of its extremely good processability.

The amount of fine fibers to be blended is 2 to 20 parts by weight, preferably 6 to 12 parts by weight, per 100 parts by weight of transpolyisoprene. If it is less than 2 parts by weight, cut resistance will not improve, and if it exceeds 20 parts by weight, impact resistance will deteriorate. Also,
It has disadvantages such as the hardness of the cover is too high and the feeling when hitting the ball is poor.

Preferably, the fine fibers are grafted with other rubber components that are compatible with the transpolyisoprene.

The graft bonding may be carried out, for example, via an initial condensate of an alkylphenol formaldehyde resin or a novolac type phenol formaldehyde resin.

The alkylphenol formaldehyde resin includes, for example, a resol-type initial condensate obtained by reacting an algylphenol such as cresol with formaldehyde or acetaldehyde in the presence of an alkali solvent, and modifications thereof.

In particular, alkylphenol formaldehyde resins having two or more methylol groups in the molecule can be suitably used. As the alkylphenol formaldehyde resin, for example, Sumilight Resin PR-22193
, Sumilight Resin PR-50994, Sumilight Resin PR-175, Sumilight Resin PR-50530
, Sumilight Resin PR-50530, Sumilight Resin PR-51466, Sumilight Resin PR-221
93, Sumilight Resin PR-213633 (manufactured by Sumitomo Durez Co., Ltd.), Takki Roll 2011 Takki Roll 2
50-I, Takki Roll 250-II, Takki Roll 2
50-III (manufactured by Sumitomo Chemical Co., Ltd.), PR-450
7 (manufactured by Gunei Chemical Industry Co., Ltd.), Tamanol 521 (manufactured by Arayo Chemical Industry Co., Ltd.), Schenectady (Sche-ne
ctady) SP 1059, Schenectady SP
1055 (manufactured by Schenectady Chemical Company) CRR-
0803 (manufactured by Union Carbide), Shinholm C1
000, C100I (AnchorC
Commercially available resin cross-linking materials such as (manufactured by Hem) Co., Ltd.

The initial condensate of novolac-type phenol-formaldehyde resin is a soluble and fusible resin obtained by condensing phenols such as phenol and bisphenols with formaldehyde (also varapormaldehyde), and its modified products. As the novolak, for example, a novolak-type phenol-formaldehyde initial condensate, a novolak-type lactam-bisphenol F-formaldehyde initial condensate, a novolak-type styrenated phenol-phenol-formaldehyde initial condensate, etc. are suitably used.

When using the above-mentioned phenol formaldehyde resin, the graft bond is between the hydrogen atom of the methylene group in the polymer molecule of the other rubber component and the methylol in the phenol formaldehyde resin molecule. It is thought that it is produced by a dehydration reaction with a hydroxyl group and a dehydration reaction between the hydrogen atom of the amide group of the amide group-containing fine fiber and the remaining methylol hydroxyl group of the phenol formaldehyde resin bonded to the other rubber component.

Further, in the case of a polymer obtained by block polymerizing the above-mentioned nylon and liquid diene-based rubber, the graft bonding may be carried out by reaction of the remaining ethylenically unsaturated groups between the liquid diene-based rubber portion and the other rubber.

Methods for producing mixtures of such other rubbers and fine fibers having amide groups are disclosed in JP-A-5El-79037, JP-A-59-3041, JP-A-58-19343, and JP-A-Sho 58-19343. It is described in detail in Japanese Patent No. 58-19342. Such a mixture is preferably available from Ube Kosan Co., Ltd. under the name FRH.

Other additives may be present in the cover composition of the present invention, such as fillers (zinc oxide, titane oxide, stearic acid, red iron, etc.).
Vulcanization accelerators (eg, secondary amines), sulfur, and the like may be added.

Conventionally known manufacturing methods are used to manufacture golf balls using the golf ball cover composition described above.

For example, by wrapping a rubber thread around a rubber ball called a center or a rubber ball filled with liquid, the outside is covered with a cover mainly composed of natural balata or synthetic balata (transpolyisoprene), and then vulcanized. can get.

(Effects of the Invention) The golf ball using the cover material of the present invention has high repulsion performance and cut resistance, and has excellent performance that cannot be obtained with conventional balata cover materials, and also has other properties such as mechanical strength and A cover material with no deterioration in workability etc. can be obtained. The cover material of the present invention is mainly used for thread-wound golf balls, but may also be used as a cover material for two-piece golf balls or three-piece golf balls.

(Example) The present invention will be explained in more detail with reference to Examples. Examples and percentages are by weight unless otherwise indicated.

Example I The compositions shown in Table 1 were thoroughly mixed using an oven roll. In addition to the ingredients shown in Table 1, 5 parts by weight of zinc oxide, 1.2 parts by weight of secondary amine, and 1.5 parts by weight of sulfur, taking the weight of trans-1,4-polyisoprene plus natural rubber as 100. In addition, the mixture was thoroughly kneaded. The obtained rubber composition was heated to 130
A slab with a thickness of 2 mx was prepared by pressing at ℃. The slab was gas vulcanized using carbon disulfide for 48 hours.

A tensile test and tear strength were measured using the obtained slab piece. The results are shown in Table-1.

For comparison, similar tests were conducted on products in which high styrene resin was blended instead of nylon@fine fibers and those in which a large amount of nylon fine fibers were blended. The results are shown in Table-1.

When a suitable amount of nylon fiber is blended with 100 parts by weight of transpolyisoprene, the reinforcing effect is much greater than when a high-styrene resin is blended, and the modulus and identification strength are improved. Furthermore, when a large amount of nylon fine fibers was blended (Comparative Example 4, 33.3 parts by weight of nylon fine fibers), the elongation was poor.

Example (2) (Ball test) A cover composition was obtained in the same manner as in Example f using the ingredients shown in Table-2. The compounded chemicals were almost the same as in Example 2, but 13-layer titanium oxide was newly added. This rubber composition was vulcanized under the same conditions as in Example I to prepare a slab, and the same tests as in Example I were conducted. A tensile test and tear strength were measured using this slab. The results are shown in Table-2.

Table 2 is placed on a standard thread-wound core ball with a shoulder diameter of approximately 39.5π.
A pair of hemispherical core bodies molded from a cover material of about 85 mm
After pressing at ℃ to form a large ball, vulcanization was performed in the same manner as in Example f. The performance of the resulting golf ball was examined. The results are shown in Table-2.

For comparison, Bonyl was prepared in the same manner and tested without containing nylon fine fibers.

The results are shown in Table-2.

1 Hardness display using combination PGA method.

'Coefficient of restitution: 45x/198.49 cylindrical object on the ball
It was calculated from the ball speed when colliding at a speed of sec.

3 spins: Measured using a photographic method when measuring flight distance.

4. Flying distance: Flying distance (carry) data with a No. 1 wood club at a head speed of 45x/sec using a swing robot made by Tsuru Temper.

5 Cut resistance index: No. 9 iron attached to Tsuru Temper swing robot, head speed 1911/s
I hit the top of the ball with an ec and checked how well the cover was cut. A score of 5 was given if there was almost no damage, and a score of 0 was given if the thread rubber layer was cut.

The average value of just the eight balls is shown as an average value.

Balls that did not contain nylon fine fibers (comparative example) had a low cut index of 2.3, while balls containing nylon fine fibers had high cut index values of 2.7.2 and 6.2.8. . In addition, the coefficient of repulsion has improved and the carry distance is 2j.
It grew around I.

Claims (1)

[Scope of Claims] 1. A golf ball cover composition comprising a cover material containing transpolyisoprene as a main component and fine fibers having an amide group. 2. The cover composition according to item 1, wherein the fine fibers are blended in an amount of 2 to 20 parts by weight based on 100 parts by weight of transpolyisoprene. 3. The cover composition according to item 1, wherein the fine fibers have an average diameter of 0.05 to 0.8 μ and a shortest fiber length of 1 μ or more. 4. The cover composition according to item 1, wherein the fine fibers are blended into the cover material in the form of a kneaded product of transpolyisoprene and other compatible rubber components. 5. The cover composition according to item 3, wherein the fine fibers are graft-bonded with other rubber components in the kneaded product.