JPS61143458A - High hardness rubber composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition of high processability suitable for packings, hydro-extracting rubber, etc., by incorporating each specified amount of specific diene rubber and sulfur in ethylene-alpha-olefin rubber and/or isobutylene- isoprene rubber. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts by wt of isobutylene-isoprene rubber and/or ethylene-alpha-olefin rubber from ethylene, alpha-olefin (e.g., propylene) and at least one sort of nonconjugated diene (e.g., dicyclopentadiene) with (B) 10-60 (pref. 15-60) pts by wt of diene rubber with a Mooney viscosity <=80 and (C) 3-35pts by wt of sulfur. This composition has high processability at kneading, rolling, extrusion, etc. during uncured state, being capable of curing under atmospheric pressure, giving a hardness >=85.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a high-hardness rubber composition, particularly a high-hardness rubber composition based on ethylene/d-olefin rubber and/or isobutylene/isoprene rubber, which has excellent cross-wire processability, roll processability, and extrusion processability. This invention relates to a hard rubber composition.

Conventionally, ethylene/d-olefin rubber and/or isobutylene/isoprene rubber have excellent heat resistance, weather resistance, etc., and are therefore widely used in automobile parts, building materials, and the like.

However, the hardness of these rubbers can be a problem depending on the purpose of use, and for this reason, JI8 has a 6301 hardness tester A.
Many efforts have been made to increase the hardness of the mold to a hardness of 85 or higher. Methods of blending resin are known.

However, when the former method is used, the viscosity of the unwashed rubber composition C (hereinafter simply referred to as compound) increases significantly, resulting in poor kneading processability, roll processability, feedability to an extruder (extrusion processability), etc. On the other hand, when using the latter method, the above-mentioned processability is good, but normal pressure vulcanization is not possible, and physical properties such as snappy properties of the vulcanized rubber composition are inferior. There is a problem, and it cannot be said that it is practically sufficient.

Under these circumstances, the present inventors conducted intensive studies to develop a high hardness rubber composition free from such problems, and as a result, completed the present invention.

That is, the present invention provides an ethylene/α-olefin rubber and/or an isobutylene/isoprene rubber, and a diene rubber that is solid at room temperature in an amount of more than 10 parts by weight and 60 parts by weight or less per 100 parts of the rubber, and 3 to 3 parts by weight. The present invention provides a high-hardness rubber composition with a hardness of 85 or higher (same as in the description), which is characterized by containing 35 parts by weight of sulfur, and such a high-hardness rubber composition has no cross-contamination when unvulcanized. It has excellent processability such as processability, roll processability, and extrusion processability, can be vulcanized under normal pressure, and has high hardness.

In the present invention, the ethylene/d-olefin rubber refers to a copolymer consisting of ethylene, an α-olefin, and one or more nonconjugated dienes, and examples of the α-olefin include propylene, 1-butene, and 1-pentene. , l-hexene, and examples of non-conjugated dienes include dicyclopentadiene, ethylidenenorbornene, 4-hexadiene, methyltetrahydroindenemethylnorbornene, and the like.

In addition, isobutylene/isoprene rubber means a copolymer of isobutylene and isoprene, or a chlorinated or brominated product thereof.

The ethylene/d-olefin rubber and the isobutylene/isoprene rubber may be used alone or as a mixture in any proportion.

Diene rubbers that can be blended into such rubbers include natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), and styrene-butadiene rubber (8BK).
), acrylonitrile butadiene rubber (NBR) and other diene rubbers that are solid at room temperature.
Synthetic rubber is manufactured by emulsion polymerization, solution polymerization, etc., but the manufacturing method is not particularly limited.

Regarding 8BR and NBR, the content of styrene or acrylonitrile is not particularly limited, but
A small content is preferable because the vulcanized rubber composition has excellent physical properties.

Furthermore, there are no restrictions on the binding mode of BR and IR, and any binding mode may be used.

Such diene rubbers may be used alone or in combination of two or more, but the Mooney viscosity of the diene rubber is preferably 80 or less from the viewpoint of the Mooney viscosity of the unvulcanized rubber composition. A diene rubber that is liquid or starch syrup-like at room temperature may be used in combination within a range that maintains the solid state.

In the present invention, the compounding amount of diene rubber is ethylene・d
- Exceeding 6 parts by weight of olefin rubber and/or isobutylene/isoprene rubber relative to the toot position
0i1i? If it is less than 10 Mgk parts, the desired hardness cannot be obtained, and if it exceeds 60 parts by weight, the elongation of the vulcanized rubber etc. Physical properties deteriorate.

The amount of sulfur added is 8 to 100 parts by weight of ethylene/α-olefin rubber and/or diene rubber.
The amount is preferably in the range of 35 molar parts; if it is less than this range, sufficient hardness will not be obtained, and if it exceeds this range, other properties such as heat aging resistance will deteriorate.

The rubber composition of the present invention basically consists of the above-mentioned ethylene and
It consists of d-olefin rubber and/or isobutylene/isoprene rubber, diene rubber, and sulfur, and if necessary, various types of M well known in the rubber industry may be added.
II materials such as reinforcing agents, fillers, softeners, processing aids, defoamers, zinc leather, stearic acid, vulcanization accelerators, vulcanizing agents other than sulfur, anti-aging agents, etc. can be blended.

The rubber composition of the present invention can be cured by various vulcanization methods well known in the rubber industry, such as press vulcanization, can vulcanization, injection molding, and UHF vulcanization.
Normal pressure continuous vulcanization consisting of vulcanization, manual vulcanization, PCM vulcanization, LOW vulcanization, etc., and a combination thereof can be applied, and by this, the target JI8 can be achieved with a hardness of 85 as measured by a 6801 hardness tester type A. A rubber composition with the above-mentioned high hardness can be obtained.

Such a rubber composition of the present invention is sp,;! E: Due to its excellent properties, it is used in packings, draining rubber,
Glass run rubber, weather strips, hard rubber materials that are composites of soft rubber materials that are applied to these materials, solid rubber materials that are composites of sponge rubber and solid rubber that are applied to door seals, toke seals, and mudguards. It can be suitably used for automobile parts such as rubber rolls, various sealing materials, industrial parts such as packings, and building materials such as setting blocks, rubber tiles, and gaskets.

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

Example 1 Each component of compounding agent (1) shown in Table 1 was mixed in the amount shown in the same table (
(parts by weight) in a Banbury mixer, and each component of compounding agent (2) is added and mixed on a roll to obtain a rubber composition.

Each of the obtained rubber compositions was vulcanized to 160% by press vulcanization.
Vulcanization was performed at °C for 120 minutes.

Table 2 shows the physical properties of the obtained vulcanized rubber.

*1 Ethylene or propylene/ethylidene norbornene copolymer rubber (manufactured by Sumitomo Chemical Co., Ltd.) *2 Ethylene/l-butene/ethylidene norbornene copolymer rubber (manufactured by Mitsui Petrochemicals Co., Ltd.) *3 Emulsion polymerization type 8BR (manufactured by Sumitomo Chemical Co., Ltd.) *4 Polybutadiene (manufactured by Nippon Synthetic Rubber Industries, Ltd.) *5 NBR (manufactured by Nippon Zeon Co., Ltd.) *7 Solution polymerization type polybutadiene 1.2 bond 7
5 1.4 Bonds 1,000 ML Aya 100°C60 1su4 *8 Liquid polybutadiene (manufactured by Nippon Soda Co., Ltd.) *9 Thermosetting alkylphenol resin (manufactured by Sumitomo Bakelite Co., Ltd.) *10 FEF blank (manufactured by Tokai Carbon Industries Co., Ltd.) )*
11 Par 7 fine process oil (manufactured by Idemitsu Kou II Co., Ltd.)

Claims (1)

[Claims] (1) Ethylene/α-olefin rubber and/or isobutylene/isoprene rubber, and more than 10 parts by weight but not more than 60 parts by weight of diene rubber that is solid at room temperature and 3 to 35 parts by weight per 100 parts by weight of the rubber. A high hardness rubber composition having a hardness of 85 or more, characterized in that it contains sulfur.