JPS63212377A - 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] (Industrial application field) The present invention relates to a novel solid golf ball.

(Prior art and its problems) A solid golf ball refers to a golf ball that is not a so-called thread-wound ball, in which a thread rubber elastic body is wound around the center, and is a two-piece golf ball consisting of a completely integrally molded one-piece golf ball, a solid inner core, and a cover. This includes golf balls, and includes balls with three or more pieces other than wound balls. These solid golf balls have an elastic portion obtained by vulcanization molding of a rubber composition in part (for example, a solid inner core) or in all (one-piece golf ball). In addition to the base rubber, the rubber composition for forming the elastic part contains additives such as metal salts of α,β-ethylenically unsaturated carboxylic acids in order to improve the restitution coefficient and impact resistance of the ball. A monomer having saturated bonds is blended as a co-crosslinking agent.

This co-crosslinking agent is grafted or crosslinked to the polybutadiene main chain by the action of a peroxide-based polymerization initiator, forming a three-dimensional crosslinked polymer of polybutadiene and the monomer,
It is believed that this imparts appropriate hardness and durability to the golf ball.

Although the above-mentioned solid golf balls themselves have fairly excellent performance, there is a need for ones with even better restitution coefficients and durability.

Conventionally, in order to satisfy the above requirements, attempts have been made to adjust the amount of co-crosslinking agent, amount of peroxide, vulcanization temperature, vulcanization pressure, etc., but nothing that fully satisfies the results has been achieved.

(Means to Solve the Problem) The present inventors have discovered that when a diuroethylenically unsaturated carboxylic acid ester having a hindered phenol group is blended into a rubber composition, the co-crosslinking reaction can be moderately controlled, and three-dimensional crosslinking can be achieved. It has been found that it imparts appropriate hardness and durability to the polymer, and at the same time significantly improves rebound properties. It was completed based on the above findings.

That is, the present invention provides an elastic rubber composition formed from a rubber composition containing a base rubber, an α,β-ethylenically unsaturated carboxylic acid metal salt, an ethylenically unsaturated carboxylic acid ester having a hindered phenol group, and a peroxide. To provide a solid golf ball having at least a portion thereof.

The base rubber in the rubber composition for obtaining the golf ball of the present invention has a 1,4-
Polybutadiene rubber is particularly preferred, and it is preferred that the base rubber contains 80% by weight or more of polybutadiene rubber. If the weight is less than 80 heavy foil, the rebound resilience will be impaired. Further, if desired, natural rubber, polyisoprene rubber, styrene-butadiene rubber, etc. may be appropriately blended with the polybutadiene.

A metal salt of α,β-ethylenically unsaturated carboxylic acid is blended into the rubber composition as a co-crosslinking agent.

Examples of metal salts of α,β-ethylenically unsaturated carboxylic acids include zinc salts and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms (eg, acrylic acid, methacrylic acid, etc.). You can also mix a metal salt that has been formed in advance (
, also α in rubber.

It may also be created by reacting a β-unsaturated carboxylic acid with a metal oxide, hydroxide, or the like. Particularly preferred are zinc acrylate and zinc methacrylate. The amount of the co-crosslinking agent blended is preferably 25 to 40 parts by weight based on 100 parts by weight of the polybutadiene rubber.

Examples of peroxides include organic peroxides such as dicumyl peroxide, t-butyl peroxybenzoate, and di-monobutyl peroxide, with dicumyl peroxide being particularly preferred. The amount of peroxide blended is 100 parts by weight of the base rubber + #I' + - 111 - ~) 7 ± 1 or 1, 0 to 2.5 parts by weight.

Examples of ethylenically unsaturated carboxylic acid esters having a hindered phenol group include 2-t-butyl-6-(
Examples include 3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate.

The amount of this compound added is based on 100 parts by weight of the base rubber.
The amount is 0.1 to 3.0 parts by weight, preferably 0.5 to 2.0 parts by weight. If it is less than 0.1 part by weight, the effect will not be sufficiently exhibited, and if it is more than 3.0 parts by weight, vulcanization will be extremely slow and uneconomical.

Golf balls meet the standard value of JIS S-7005-1955, that is, diameter 42.67 x m or more (large size)
, 45.9g for 41.15mm or more (small size)
The following is determined, and the specific gravity of the ball is necessarily determined. Therefore, in order to meet these values, inert fillers are usually added to the rubber composition. Examples of inert fillers include barium sulfate, zinc oxide, and the like.

In addition, if necessary, the performance of the Gol 7 ball may be improved.

The rubber composition of the present invention is obtained by kneading the above-mentioned components using a roll or a niegu. The kneading time, temperature, etc. are determined within commonly used ranges.

A solid golf ball has a part or all of the rubbery portion obtained by vulcanization molding the above-mentioned rubber composition in a predetermined mold. If necessary, the crosslinked rubbery portion may be covered with a cover such as a resin. Vulcanization is usually carried out at a temperature of 140-170°C for 20-40 minutes. The solid golf balls of the present invention have low vulcanization temperatures, e.g.
More excellent effects can be obtained at 40-150°C.

(Effects of the Invention) The solid golf ball obtained by the present invention may be a one-piece golf ball, a two-piece golf ball, or a multilayer golf ball, and in any of them, α,
It exhibits significantly superior repulsion performance, durability, and flight performance compared to when β-ethylenically unsaturated carboxylic acid metal salt is used alone.

(Example) The present invention will be explained in more detail with reference to Examples.

Examples 1 to 3 and Comparative Example 1.2 A rubber composition was obtained by mixing the formulations shown in Table 1 in a Nigu, and the degree of vulcanization at 145°C was measured using a curelastometer (Arc 1 °). The results are shown in Figure 1.

As is clear from FIG. 1, the vulcanization speed (torque) in the example exhibits the appearance of two-stage vulcanization, but in the case of the comparative example, such a phenomenon is not observed.

In particular, in Comparative Example 1, the reaction at the initial stage of vulcanization progresses easily, and in the case of spherical objects, the reaction inside progresses more markedly, resulting in the appearance of a runaway reaction.

Next, the above composition was vulcanized and molded at 145° C. for 40 minutes to obtain an inner core for a two-piece ball having a diameter of 38.5 mm. This inner core is coated with a commercially available ionomer resin (Himilan 1707) from Mitsui Polychemical Co., Ltd.
A two-piece golf ball with a diameter of 42.8+ m was obtained, and its composite gin, restitution coefficient, and durability index were measured. The results are shown in Table-1.

Table-1 1 2-t-Butyl-6-(3-t
-butyl-2-hydroxy-5-methylbenzyl)-4
-Methylphenyl acrylate.

2 Anti-aging agent commercially available as Yoshinox 425 from Yoshitomi Pharmaceutical.

3. PGA compression.

-Lu Mezo Liao Uri Denden 1-? -Cill11U4r 9
Q ”M5 Durability index Impact index of ball at 45/as speed.

The golf balls of Examples exhibit high values for both the coefficient of restitution and durability.

Example 4.5 and Comparative Examples 3 to 5 The formulations shown in Table 2 were thoroughly mixed using a niegu to form a rubber composition. The obtained rubber composition was vulcanized in a mold at 150° C. for 30 minutes to obtain an inner core with a diameter of 38.4 zm, which was covered with an ionomer cover (Himilan 1707 manufactured by DuPont Mitsui Polychemicals) to form an inner core with a diameter of 42.4 zm.
I got an 8JIN two-piece golf ball.

Compression of the resulting two-piece golf ball,
The repulsion coefficient, durability, and flight distance were evaluated.

The results are shown in Table-2.

Table-2 1 Penwaltol Sidol (Penwalt-L
1,1-di(t-butylperoxy)-3,3,5-)dimethylcyclohexane 2, commercially available from Ucfdol)
α,α°-bis(t-butylperoxy)diisopropylbenzene commercially available from NOF Corporation.

The golf ball of the present invention has a high coefficient of restitution, high durability, and a long flight distance.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between curing time and torque obtained with the curelastometer of Examples 1 to 3 and Comparative Examples 1 and 2.

Claims (1)

[Scope of Claims] 1. Formed from a rubber composition containing a base rubber, an α,β-ethylenically unsaturated carboxylic acid metal salt, an ethylenically unsaturated carboxylic acid ester having a hindered phenol group, and a peroxide. A solid golf ball having at least a portion of the elastic portion. 2. The rubber composition has α, β based on 100 parts by weight of the base rubber.
- 25 to 40 parts by weight of ethylenically unsaturated carboxylic acid metal salt, 0.1 to 3.0 parts by weight of ethylenically unsaturated carboxylic acid ester having a hindered phenol group, and 0.0 parts by weight of peroxide.
The solid golf ball according to item 1, containing 5 to 3.0 parts by weight. 3. The base rubber is cis-1,4-polybutadiene rubber.
2. The solid golf ball according to item 1, containing 0% by weight or more. 4. The solid golf ball according to item 1, wherein the α,β-ethylenically unsaturated carboxylic acid metal salt is zinc acrylate. 5. Ethylenically unsaturated carboxylic acid ester having a hindered phenol group is 2-t-butyl-6-(3-t-
Butyl-2-hydroxy-5-methylbenzyl)-4-
2. The solid golf ball of item 1, which is methyl phenyl acrylate. 6. The solid golf ball according to item 1, wherein the peroxide is dicumyl peroxide.