JPH1060199A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition comprising an isomonoolefin-p- alkylstyrene copolymer which is greatly improved with respect to S-S characteristics and has excellent tensile strength. SOLUTION: This composition comprises 100 pts.wt. of a halogenated copolymer of a 4-7C isomonoolefin and a p-alkyl styrene, 0.5 to 10 pts.wt. of a compound having, in one molecule thereof, two or more of chemical structure units represented by the formula, and 1 to 10 pts.wt. of at least one crosslinking component selected from among zinc salts of 12-22C saturated and unsaturated fatty acids and zinc oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a halogenated isomonoolefin-p-alkylstyrene copolymer containing a specific thiol compound and a fatty acid zinc and / or zinc oxide. The present invention relates to a rubber composition which can be suitably used for hoses, tire inner liners, and the like.

[0002]

2. Description of the Related Art European Patent Application No. 89305395 discloses a copolymer of isomonoolefin and paramethylstyrene and a bromide thereof.
JP-A-508435 discloses the use of the above copolymer in a rubber composition for a tire inner liner, and Japanese Patent Application Laid-Open (JP-A) No. 5-50730.
No. 3 discloses the use of the above copolymer in a hose composition.

[0003] Butyl rubber is generally used for hoses such as freon hoses and steam hoses, which are required to have water or water vapor permeation resistance, and have good water permeation resistance and heat resistance. However, butyl rubber has a problem that although it is extremely excellent in moisture permeability, it is inferior in weather resistance. To solve this problem, paramethylstyrene (PMS) -based butyl rubber having both properties has been studied, but its breaking strength has not yet reached a level that is sufficiently satisfactory for practical use. Also, tire inner liners, sidewalls, cap treads, etc. are being studied for typical tire materials,
Again, improvement of the breaking strength was a problem. Furthermore, para-methylstyrene-based butyl rubber having excellent heat resistance is considered to be suitable as a bladder material for tire vulcanization, but improvement in breaking strength has also been required.

[0004]

Accordingly, the present invention solves the above-mentioned problems of the prior art and provides halogenated isomonoolefin-p- excellent in tensile properties such as tensile strength.
An object is to provide a rubber composition containing an alkylstyrene copolymer.

[0005]

According to the present invention, (i)
100 parts by weight of a halogen-containing copolymer of a C ₄ -C ₇ isomonoolefin and p-alkylstyrene, (ii) a formula (I):

[0006]

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[0007] Compounds having two or more chemical structural units in the molecule represented by 0.5 to 10.0 parts by weight and (iii) C ₁₂
-C ₂₂ saturated or unsaturated fatty acid zinc salt and a rubber composition comprising at least one cross-linking compounding agent for 1 to 10 parts by weight selected from zinc oxide is provided.

[0008]

According to the present invention, as described above, a specific mercapto group-containing compound represented by the formula (I) is used as a crosslinking agent for a halogen-containing isomonoolefin-p-alkylstyrene copolymer as a fatty acid. By blending and crosslinking with zinc and / or zinc oxide, the SS characteristics can be significantly improved.

The rubber composition according to the present invention contains a C ₄ -C ₇ isomonoolefin (eg, isobutene, isoprene, isohexene, etc.) and a p-alkylstyrene (eg, p-alkylstyrene).
(Eg, methyl styrene). This copolymer is a known copolymer, as described in, for example, Japanese Patent Publication No. Hei 5-508435, and is also commercially available from Exxon Chemical. In the present invention, such commercially available products can be used. The content of the halogen atom is not particularly limited, but is preferably 0.3
10 to 10% by weight, more preferably 0.5 to 5% by weight. If the content of halogen atoms is less than 0.3% by weight, a sufficient crosslinking point cannot be obtained, so that the breaking strength is low, which causes a problem in practical use. Is undesirably caused.

According to the present invention, the compound having at least two structural units (I) in a molecule is preferably 0.5 to 10 parts by weight, more preferably 1.10 parts by weight, based on 100 parts by weight of the copolymer.
0 to 8.0 parts by weight. When the compounding amount of this compound is 0.
If the amount is less than 5 parts by weight, the desired improvement effect cannot be obtained, so that it is not preferable.

In general, it is known that a dithiol compound can be used as a crosslinking agent for a diene rubber because it undergoes an addition reaction to a double bond, and is also known to be a crosslinking agent for chloroprene rubber. Further, mercapto compounds have been used as curing agents for epoxy resins. However, as in the present invention, the halogen-containing copolymer of C ₄ -C ₇ isomonoolefin and p-alkylstyrene is used in the presence of at least one crosslinking compound selected from the group consisting of fatty acid zinc salt and zinc oxide. It is completely unexpected that the crosslinking properties of the obtained rubber composition are improved by blending a thiol compound having two or more chemical structural units represented by the formula (I) in a molecule.

The compound having the unit of the formula (I) is not particularly limited as long as it has two or more units of the formula (I) in its chemical structure. Specific examples include polyoxypropylene glycerin. Ether tristhioglycolate, pentaerythritol tetrakisthioglycolate, trimethylolpropane tristhioglycolate,
Examples include ethylene glycol bismercaptopropionate and pentaerythritol tetrakismercaptopropionate.

According to the present invention, the copolymer rubber 100
1-10 parts by weight per part by weight, preferably a C ₁₂ -C ₂₂ saturated or unsaturated fatty acid zinc salts and / or zinc oxide from 1.5 to 8 parts by weight, for use as a crosslinking compounding agent. If the amount of the cross-linking compounding agent is too small, the cross-linking reaction does not proceed sufficiently and the rubber elasticity required for practical use as a rubber material cannot be obtained. It is not preferable because it becomes high. Specific examples of the saturated or unsaturated fatty acids include, for example, stearic acid, palmitic acid, oleic acid, lauric acid, myristic acid,
Alternatively, a mixture of two or more of these can be used.

In the rubber composition according to the present invention, in addition to the above-mentioned essential components, carbon black, a vulcanizing or crosslinking agent,
Vulcanization or crosslinking accelerators, various oils, anti-aging agents, fillers, tires such as plasticizers, can be blended with various additives that are generally blended for other general rubber,
Such a composition can be kneaded and vulcanized in a conventional manner into a composition, which can be used for vulcanization or crosslinking. The compounding amounts of these additives can also be conventional general compounding amounts as long as they do not contradict the object of the present invention.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but it goes without saying that the technical scope of the present invention is not limited to these Examples. Standard Examples, Examples 1 to 8 and Comparative Examples 1 to 9 In the composition (parts by weight) shown in Table I, a crosslinking agent 1 was added to a bromide of an isobutylene-paramethylstyrene copolymer (bromine content = 1.2% by weight). 5 and zinc oxide or zinc stearate, and if necessary, carbon black and a vulcanization accelerator, and mixed with a 1.8 liter closed mixer at 45 rpm.
For 3 minutes, and sulfur was kneaded with an 8-inch oven roll to obtain a rubber composition. The obtained rubber composition was press-vulcanized in a 15 × 15 × 0.2 cm mold at 160 ° C. for 45 minutes to prepare a test piece (rubber sheet), and the vulcanization properties were evaluated. The vulcanization properties were measured by a tensile test according to JIS K6301. The results are shown in Table I.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

As described above, according to the present invention,
Since the problem of low tensile strength and elongation, which were the weak points of the copolymer rubber of isomonoolefin such as butyl rubber, can be solved, it is possible to obtain a rubber composition that can be suitably used for hoses, tire inner liners, and the like. it can.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08K 5/36 C08K 5/36 C08L 25/08 KGA C08L 25/08 KGA

Claims (1)

[Claims] 1. (i) Halogen-containing copolymer 100 of C ₄ -C ₇ isomonoolefin and p-alkylstyrene
Parts by weight, (ii) Formula (I): Compounds 0.5 to 10.0 parts by weight having two or more chemical structural units represented in the molecule and (iii) C ₁₂ ~C ₂₂ saturated or unsaturated fatty acid zinc salt and at least one selected from zinc oxide A rubber composition comprising 1 to 10 parts by weight of a cross-linking compounding agent.