JPS5933337A - Rubber composition for solid golf ball - Google Patents

Abstract

PURPOSE:To provide the titled rubber compsn. having high resilience and hardness, consisting of a replasticized product of a polysulfide-crosslinked vulcanized rubber and a high-cis polybutadiene rubber. CONSTITUTION:1-10pts.wt. reclaiming oil such as pine tar and 75-25pts.wt. high-cis polybutadiene rubber are added to 25-75pts.wt. polysulfide-crosslinked vulcanized rubber having a crosslinking density of 0.5X10<-5>-20.0X10<-5> mol/cc and the average sulfur number of at least 1.5 per crosslinked unit. The mixture is heated and kneaded to obtain a replasticized product, which is then blended with high-cis polybutadiene in an amount of 5-15wt% in terms of polysulfide- crosslinked vulcanized rubber.

Description

[Detailed description of the invention] The present invention relates to a rubber composition for solid golf balls.

Solid golf balls have the advantage of being integrally molded.
Particularly high resilience and hardness are required. Conventional research to meet these demands has focused on fixing high-cis polybutadiene rubber as the base rubber and focusing exclusively on improving additives such as co-crosslinking agents, but there are still unsatisfactory results. A solid golf ball with high resilience and hardness has not been developed.

Contrary to previous research trends, the present inventors have discovered that a rubber composition suitable for solid golf balls can be obtained by making improvements to the base rubber, and have completed the present invention.

That is, the present invention provides a solid golf product characterized by containing a replasticized product obtained by heating and kneading polysulfide crosslinked vulcanized rubber with high-cis polybutadiene rubber in the presence of reclaiming oil, and high-cis polybutadiene rubber. This invention relates to a rubber set for balls.

The formulation of the replasticized product used in the present invention 1 is not particularly limited, but is usually polysulfide cross-linked vulcanized:
5 to 75 parts by weight of high-cis polybutadiene rubber in the presence of 1 to 10 parts by weight of reclaiming oil,
It is prepared by heating and kneading together with the mixing part.

The formulation of polysulfide crosslinked vulcanized rubber is not particularly limited, and natural rubber and/or synthetic combs, such as high-cis polybutadiene rubber, cis-1,4-polyisoprene rubber, styrene-butadiene rubber, ethylene - Propylene rubber or other base rubber prepared by a conventional method may be used. Particularly suitable polysulfide crosslinked vulcanized rubber has a crosslinking density of 0.5X105 to 20. O
X 10-5 moe/cc, and the average number of bonded sulfurs per crosslink is 1.5 or more.

The high-cis polybutadiene rubber may be one conventionally used as l-rubber for solid golf balls, such as 1,4-polybutadiene BROI (commercially available from Japan Synthetic Rubber Co., Ltd.) having a cis structure of 98%.

Examples of the flaming oil used in the present invention include pine tar, tall oil, and dipentene, with pine cool being particularly preferred.

In addition to the above-mentioned components, other additives, such as zinc white, may be appropriately blended during replasticization.

A solid golf ball according to the present invention is produced by kneading the replasticized product prepared as described above with high-cis polybutadiene rubber together with conventional additives such as a crosslinking agent, a polymerization initiator, a filler, an anti-aging agent, etc. A rubber composition for use is obtained.

The blending ratio of the replasticized product and the high-cis polybutadiene rubber is usually 5 to 15% by weight of the former in terms of polysulfide crosslinked vulcanized rubber.

If the amount of the replasticized product is less than 5% by weight in terms of vulcanized rubber, it is difficult to obtain the effects of the present invention, and if it is more than 15% by weight, the effect of additives such as reclaiming oil and sulfur contained in the replasticized product This is not preferred because the action of a polymerization initiator such as peroxide is inhibited.

The rubber composition according to the present invention is uniformly kneaded according to a conventional method,
By heat-vulcanizing and integrally molding under pressure, a solid golf ball with excellent properties, particularly high resilience and hardness without sacrificing durability, can be obtained.

The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 Vulcanized rubber A (crosslinking density: 6, OX 1) using a 1:1 blend of natural rubber and synthetic natural rubber latex as the base rubber
0"moj?/cc, average number of bonded sulfurs per crosslink: 2.2).

71 isis polybutadiene rubber (Japan Synthetic Rubber Co., Ltd. commercial product, JSRBROI') in the 31 internal mixer
1000g, vulcanized rubber A1100 crushed in a roll mill
g, Zinc White No. 1, 704 g, and Pine Cool 88 g were mixed uniformly at 120° C. for 30 minutes to prepare a replasticized product C.

A mixture according to the formulation in Table 1 was heated at 160°C for 18 minutes using a conventional method to form a small size (diameter 41.15 mm).
) An integrally molded solid golf ball I was manufactured.

Table 2 shows the physical properties of solid golf ball (1).

Example 2 A small-sized integrally molded solid golf ball (2) was produced in the same manner as in Example 1 except that the amount of replasticized product C was changed as shown in Table 1, and its physical properties are shown in Table 2.

A small-sized integrally molded solid golf ball (2) was produced in the same manner as in Example 1, and its physical properties are shown in Table 2.

Example 4 Vulcanized comb B (crosslinking density: 4.OXl, 0
”mol/cc,] Average number of bonded sulfur per crosslink:
2.5) was prepared.

Into a 3I internal mixer, 1000 g of high-cis polybutadiene rubber (JSkBROI), vulcanized rubber B1], OOg, Zinc White No. 1, 704 g, and 88 g of Pine Cool were charged.
A replasticized material was prepared by uniformly mixing and masticating at 0°C for 30 minutes.

The mixture according to the formulation shown in Table 1 was heated to 160°C in a conventional manner.
The ball was heated for 18 minutes to produce a small-sized integrally molded solid golf ball (2), whose physical properties are shown in Table 2.

Comparative Example 1 A mixture according to the formulation shown in Table 1 was heated at 160°C in a conventional manner.
A small-sized integrally molded solid golf ball (2) was produced by heating for 18 minutes, and its physical properties are shown in Table 2.

Comparative Example 2 In a 3e internal mixer, 2000 g of vulcanized rubber 1-A ground with a roll mill and a remachi plasticizer (Z-0-benzamidophenyl disulfide Noctizer S,
S; 80 g of Daien Shinko Kagaku Kogyo Co., Ltd. (commercial product) was charged and uniformly mixed and masticated at 120°C for 25 minutes to prepare replasticized product E.

The mixture according to the formulation shown in Table 1 was heated to 160°C in a conventional manner.
A small-sized integrally molded solid golf ball (2) was produced by heating for 18 minutes, and its physical properties are shown in Table 2.

Comparative Example 3 A mixture according to the formulation shown in Table 1 was heated at 160°C in a conventional manner.
A small-sized integrally molded solid golf ball (2) was produced by heating for 18 minutes, and its physical properties are shown in Table 2.

Comparative Example 4 A mixture according to the formulation shown in Table 1 was heated at 160°C in a conventional manner.
A small-sized integrally molded solid golf ball (2) was produced by heating for 18 minutes, and its physical properties are shown in Table 2.

Table-1 ■) Converted to vulcanized rubber A2) Converted to vulcanized rubber B3) 4,4-thiobis(6-tert-butyl-
3-Methylphenol Table-2 Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Hao Aoyama and 1 other person)

Claims (1)

[Claims] 1. A replasticized product obtained by heating and kneading polysulfide crosslinked vulcanized rubber with 71 isis borobutadiene rubber in the presence of reclaiming oil, and 1 isis borobutadiene rubber. Rubber composition for solid golf balls. 2. The replasticized product is polysulfide crosslinked vulcanized rubber 25
2. The rubber composition according to item 1, wherein ~75 parts by weight are heat-kneaded with 75 to 25 parts by weight of isis-bolybutadiene rubber in the presence of 1 to 10 parts by weight of reclaiming oil. 3. The rubber composition according to item 1, wherein the replasticized product is contained in a weight range of 5 to 15% by weight in terms of polysulfide crosslinked vulcanized rubber based on 71 isis borobutadiene. 4. Polysulfide crosslinked vulcanized rubber has a crosslinking density of 0.5
X 10' ~ 20. OX 10” moe/c
c, average number of bonded sulfurs per crosslink t51? 2. The rubber composition according to claim 1, which is a comb having J, j-. 5. The rubber composition according to item 1, wherein the base rubber of the polysulfide crosslinked vulcanized rubber is natural rubber and/or synthetic rubber.