JPH11349738A - Rubber composition and rubber processing aid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition composed of rubber reinforced with silica and/or carbon black, improved in processability without damaging other properties by adding a fatty acid ester of polypentaerythritol. SOLUTION: This rubber composition is composed of (A) 100 pts.wt. of natural and/or synthetic rubber reinforced with silica and/or carbon black, and (B) 1 to 10 pts.wt. of a fatty acid ester of polypentaerythritol added to the component A. The rubber composition is processed by adding a fatty acid ester of polypentaerythritol to the composition composed of rubber and silica and/or carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition comprising a natural rubber and / or a synthetic rubber, a reinforcing agent, and a fatty acid ester of polypentaerythritol. More specifically, the present invention relates to a rubber composition containing silica and / or carbon black as a reinforcing agent. The present invention relates to a finished rubber composition and a method for processing the rubber. And, a rubber composition containing vulcanizable silica and / or carbon black for the purpose of shortening the rubber kneading time when not vulcanized / energy saving and improving the rubber processability, specifically, increasing the extrusion speed. About.

[0002]

2. Description of the Related Art In recent years, tires containing silica as a reinforcing agent have been used in automobile tires, for example, in order to improve fuel efficiency and braking performance, silica-containing tires in which part of carbon black is replaced with silica have begun to be used. The composition is increasing. However, silica has a strong self-aggregating property, and when added to rubber, the viscosity of the rubber increases, and the processability deteriorates significantly, which is a problem.

[0003] In order to solve such a problem, improvement by addition of a processing aid has been studied, but the effect is not sufficient. For example, a method of adding a polyhydric alcohol or a fatty acid, or performing a surface treatment with a silicone oil (for example,
Introduction to New Rubber Technology, pp. 180-181 Japan Rubber Association /
1975). In addition, a method of adding a silane coupling agent (for example,
mistry and Technology, (Rubber Chemistry and Technology) 55, 877, 1982)
However, since the silane coupling agent itself is expensive, it is not preferable because the material cost is increased.

Japanese Patent Application Laid-Open No. 10-29963 discloses a fatty acid ester of polypentaerythritol, and describes that it can be used as a processing aid for rubber. However, this publication does not disclose any actual rubber compounding. Moreover, there is no description focusing on the fact that the fatty acid ester of polypentaerythritol is particularly effective in the presence of a reinforcing agent.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have made intensive studies on silica and / or carbon black, particularly rubber containing silica as a reinforcing agent, for the purpose of improving the processability. By adding a fatty acid ester of erythritol, it was discovered that the processability was significantly improved without lowering the physical properties,
The present invention has been completed.

That is, the present invention is characterized in that 1 to 10 parts by weight of a polypentaerythritol fatty acid ester is added to 100 parts by weight of a natural rubber and / or a synthetic rubber containing silica and / or carbon black as a reinforcing agent. The present invention relates to a rubber composition and a method for processing the rubber composition obtained by adding a fatty acid ester of polypentaerythritol to a rubber composition comprising a natural rubber and / or a synthetic rubber and silica and / or carbon black.

Further, the present invention relates to a processing aid for rubber containing the above-mentioned polypentaerythritol fatty acid ester as a main component. An object of the present invention is to provide a rubber containing a reinforcing agent such as silica or carbon black in a system in which the rubber physical properties are improved. It is a processing aid that significantly improves the processability of the rubber itself without lowering it. The “silica” in the present invention means hydrous silicic acid, and includes wet-process silica and dry-process silica.

The fatty acid ester of polypentaerythritol of the present invention is, specifically, a saturated or unsaturated fatty acid having 10 to 24 carbon atoms, for example, lauric acid, palmitic acid, stearic acid, oleic acid, elaidic acid, elca An ester compound obtained by a dehydration condensation reaction of polypentaerythritol with an acid, linoleic acid, linolenic acid or the like or a mixed fatty acid thereof.

Specifically, for example, Japanese Patent Application Laid-Open No. 10-299
No. 63, the above ester mixture of polypentaerythritol containing a polymer of pentaerythritol as a main component, more specifically, the mixture contains 60% by weight or more of polypentaerythritol,
Esterification of a mixture of pentaerythritol and higher fatty acid reacted so that 50% by weight or more of polypentaerythritol is tripentaerythritol, and a hydroxyl group content of the esterification reaction product becomes 3 to 7%. It is a reaction product.

[0010]

The amount of the fatty acid ester of polypentaerythritol used is 1 to 10 parts by weight, more preferably 2 to 5 parts by weight, per 100 parts by weight of the rubber. If the amount is less than 1 part by weight, the effect of improving the workability is insufficient and is not effective. Addition of an amount exceeding 10 parts by weight is not preferable because the effect of improving processability is not improved as compared with the addition amount, and it is not economical.

The rubber to which the present invention can be applied is arbitrary, for example, natural rubber, styrene-butadiene rubber,
Examples thereof include butyl rubber, isoprene rubber, polybutadiene rubber, ethylene-propylene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, and chlorinated butyl rubber.

The rubber composition containing silica and / or carbon black of the present invention is prepared by a conventional rubber kneading method, that is, by mixing with a mixer such as an open roll, a Banbury mixer, or a pressure kneader. During the kneading, additives used in the ordinary rubber industry, for example, vulcanizing agents, vulcanization accelerators, metal oxides, fillers, softeners, antioxidants and the like are further compounded. Things are not particularly limited.

[0013]

EXAMPLES Examples will be described below in detail, but the present invention is not limited to these examples. Example 1 According to the compounding recipes shown in Tables 1 and 2, mixing was carried out by a conventional method to obtain a silica compounded rubber composition. JI compounded rubber
According to SK6300 (Unvulcanized rubber physical test method), it was measured by the Mooney viscosity test method. Also, JIS
The tensile test was measured in accordance with K6301 (Vulcanized rubber physical test method). The workability was determined by the flowability of the mold, and those that flowed easily were evaluated as ○, and those that did not flow were evaluated as x. Table 2 also shows the measured results.

The ozonone 6C in Tables 1 and 2
Is N-phenyl-N '-(1,3-dimethylbutyl) -p-
Product name of phenylenediamine (manufactured by Seiko Chemical Co., Ltd.)
Suncellar NS-G is a trade name of N-tert-butylbenzothiazyl-2-sulfenamide (manufactured by Sanshin Chemical Industry Co., Ltd.), and Nipsil VN-3 is a trade name of wet process silica (Nippon Silica Industry Co., Ltd.) Made).

[0015]

[Table 1]

[0016]

[Table 2]

Example 2 According to the compounding recipe shown in Tables 3 and 4 in accordance with Example 1, a silica compounded rubber composition was obtained and the rubber properties were measured.
Table 4 also summarizes the determination results of the workability.
In addition, Suncellar F in Table 3 is a trade name (made by Sanshin Chemical Industry Co., Ltd.) of the mixing accelerator.

[0018]

[Table 3]

[0019]

[Table 4]

Example 3 According to the compounding recipe shown in Tables 5 and 6 according to Example 1, a carbon black compounded rubber composition was obtained, and the rubber properties were measured. Table 6 summarizes the workability determination results and summarizes the results.
It was shown to. In addition, Suncellar CM-G in Table 5 is a trade name of N-cyclohexylbenzothiazyl-2-sulfenamide (manufactured by Sanshin Chemical Industry Co., Ltd.).

[0021]

[Table 5]

[0022]

[Table 6]

[0023]

As is apparent from the above examples, the addition of a fatty acid ester of polypentaerythritol to a natural rubber or a synthetic rubber containing silica and / or carbon black as a reinforcing agent, and a blend rubber thereof. In addition, workability is remarkably improved without deteriorating physical properties. Therefore, the rubber composition of the present invention is useful, for example, as a rubber compound for a tire tread. It is also understood that the fatty acid ester of polypentaerythritol of the present invention is a useful rubber processing aid in the presence of a rubber reinforcing agent.

Claims (7)

[Claims] 1. A rubber composition comprising a natural rubber and / or a synthetic rubber, a reinforcing agent, and a fatty acid ester of polypentaerythritol. 2. The rubber composition according to claim 1, wherein the reinforcing agent is silica and / or carbon black. 3. The rubber composition according to claim 1, wherein 1 to 10 parts by weight of a fatty acid ester of polypentaerythritol is added to 100 parts by weight of the rubber. 4. A method for processing a rubber composition comprising a natural rubber and / or a synthetic rubber and silica and / or carbon black to which a fatty acid ester of polypentaerythritol is added. 5. The method according to claim 4, wherein 1.0 to 10 parts by weight of a fatty acid ester of polypentaerythritol is added to 100 parts by weight of the rubber. 6. A rubber processing aid comprising a fatty acid ester of polypentaerythritol as a main component. 7. A rubber processing aid containing silica as a main component and comprising a fatty acid ester of polypentaerythritol.