JPH0423841A - Composition for rubber vibration insulator - Google Patents

Abstract

PURPOSE:To obtain a composition having excellent heat resistance, fatigue resistance and endurance and used for a rubber vibration insulator of car component such as engine mount by blending a rubber component consisting of a natural rubber, etc., and ethylene-alpha-olefin copolymer rubber, etc., with an organic peroxide. CONSTITUTION:The objective composition obtained by blending a rubber component consisting of (A) 50-90wt.% natural rubber and/or polyisoprene rubber and (B) 10-50wt.% ethylene-alpha-olefin nonconjugated-diene copolymer rubber and/or ethylene-alpha-olefin copolymer rubber with an organic peroxide as a crosslinking agent at a ratio of 2-7 pts.wt., based on 100 pts.wt. rubber component. The weight ratio of the component A to the component B is preferably (80/20) to (60/40). 3-12Calpha-Olefin, especially propylene is preferably used as the alpha-olefin of the component B.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to the use of natural rubber and/or polyisoprene rubber, which have excellent heat resistance and durability, and ethylene-α-olefin-nonconjugated diene copolymer rubber and/or ethylene - It relates to a composition for vibration-proof rubber using an organic peroxide as a crosslinking agent in an α-olefin copolymer rubber.

[Conventional technology] Anti-vibration rubber is used in automobiles, railway vehicles, construction vehicles, industrial machinery,
Furthermore, they are used in many applications where vibration is a problem, such as office automation equipment.

Among these, in automobiles, the engine room becomes considerably hot due to the higher output of engines such as turbo engines and the increased density of the engine room due to an increase in the number of parts, so anti-vibration rubber products are required to cope with this. It is being

However, in these fields, natural rubber has conventionally been mainly used from the viewpoint of dynamic properties and durability.

[Problems to be Solved by the Invention] However, natural rubber has problems such as insufficient heat resistance and problems such as cracks and so-called heat set. To this end, although the problems of natural rubber have been improved by adding a small amount of sulfur vulcanization, the heat resistance and setting resistance have not yet reached a satisfactory level.

Under these circumstances, there is a strong desire for rubber products with even better heat resistance and durability under high temperatures.

[Means for Solving the Problems] As a result of intensive studies to achieve the above object, it was found that in a vibration-proof rubber composition, 50 to 90% by weight of natural rubber and/or polyisoprene rubber and ethylene-α-olefin- Non-conjugated diene copolymer rubber and/or ethylene-
By using an organic peroxide as a crosslinking agent for a rubber component containing 10 to 50% by weight of α-olefin copolymer rubber, we have achieved levels of heat resistance, durability, and resistance to set that were previously unobtainable. The inventors have discovered that an excellent rubber composition can be obtained, and have completed the present invention.

The present invention will be explained in detail below.

The weight ratio of natural rubber and/or polyisoprene rubber to ethylene-α-olefin-nonconjugated diene copolymer rubber and/or ethylene-α-olefin copolymer rubber used in the present invention is 90/10 to 50,150. ,
Preferably it is 80/20 to 60/40. Within this range, an excellent anti-vibration rubber product that satisfies the object of the present invention can be obtained. On the other hand, if the weight ratio exceeds 90, the heat resistance of the obtained rubber product will be poor, while if the weight ratio is less than 50, the durability of the obtained rubber product will fall below the practical range. becomes.

The ethylene-α-olefin non-conjugated diene copolymer rubber and ethylene-α-olefin copolymer rubber used in the present invention are rubbers in which ethylene, α-olefin, and optionally a non-conjugated diene are copolymerized, The α-olefin is preferably an α-olefin having 3 to 12 carbon atoms, such as propylene, butene-1,4-methylpentene-1
, hexene-1, etc. can be used. Particularly preferred is propylene. Two or more of these α-olefins may be used in combination.

As the non-conjugated diene, ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, etc. are used.

In the copolymer rubber, its Mooney viscosity (ML
, 120° C.) and ethylene-α-olefin (1+8° C.) is not particularly limited, but the Mooney viscosity is preferably 30 to 300, and the ratio of ethylene to α-olefin is preferably 75/25 to 50,150. Additionally, if the Mooney viscosity is high, it can also be used as an oil-extended rubber.

In the present invention, by using an organic peroxide instead of sulfur as a crosslinking agent, the resistance to settling and heat resistance is significantly improved.

The amount of organic peroxide used in the present invention is rubber component 10
The amount is preferably 1 to 10 parts by weight, more preferably 2 to 7 parts by weight relative to 0 parts by weight. If the amount of organic peroxide is less than 1 part by weight, crosslinking will not be sufficient and the resulting rubber product will have low mechanical strength, and if it exceeds 10 parts by weight, the durability will fall below the practical range.

Specific examples of organic peroxides include 1,1-di(tert-butylperoxy)-3,5,5-trimethylcyclohexane, di-tert-butylperoxide,
Examples include dicumyl peroxide, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and 1,3-di(tert-butylperoxyisopropyl)benzene.

Among these, 1,1-di(tert-butylperoxy')-3,3,5-trimethylcyclohexane ζ dicumyl peroxide and 1,3-di(tert-butylperoxy-isopropyl)benzene are preferred.

In the anti-vibration rubber composition of the present invention, a specific proportion of carbon black and, if necessary, a specific proportion of extender oil can be used together with rubber.

The amount of carbon black to be blended is preferably 10 to 100 parts by weight, and preferably 20 to 70 parts by weight, based on 100 parts by weight of the rubber component.

When the amount of carbon black is within this range, a vibration-proof rubber composition that provides a rubber product with excellent high-temperature durability can be obtained.

The amount of extender oil blended is preferably 0 to 50 parts by weight per 100 parts by weight of the rubber component. When the amount of extender oil is within this range, a vibration-proof rubber composition that provides a rubber product with excellent processability and high-temperature durability can be obtained. Specific examples of extender oils include aromatic oils commonly used for rubber, so-called process oils such as naphthenic oils and paraffin oils, and vegetable oils such as coconut oil. Among these, process oil is preferred, and paraffin oil is particularly preferred.

In the anti-vibration rubber composition of the present invention, other additives may be blended as necessary.

When using organic peroxides as a crosslinking agent, sulfur,
p-quinonedioxime, p,p-dibenzoylquinonedioxime, lauryl methacrylate, ethylene glycol acrylate, trimethylolpropene trimethacrylate, diallyl butarate, triallyl cyanurate, etc. may be blended as a crosslinking aid.

Further, the anti-vibration rubber composition of the present invention may contain an anti-aging agent, if necessary. By adding an anti-aging agent, a vibration-proof rubber composition with even better heat resistance and durability can be obtained.

Anti-aging agents include p-(p-)luenesulfonylamide)-diphenylamine, N,N'diphenylethylenediamine, octylated diphenylamine, substituted diphenylamine, diphenylamines such as diphenylamide derivatives, N-isopropyl-N'-phenyl- p-
phenylenediamine, N,N'-di-2-naphthyl-
p-phenylenediamine, p-phenylenediamines such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 2.2.4-)rifthyl-1,2-dihydroquinoline, 6 -Nitoxie 2.2.
Quinolines of 4-trimethyl-1,2-dihydroquinoline, 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(4'-hydroxy-3'-5'-di-tert. -butylphenyl)
Monophenols such as propionate, styrenated phenol, 2,2'-methylene-bis-(4-methyl-
Bisphenols such as 6-tert-butylphenol), hindered bisphenol, polyphenols such as tetrabis-methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, 2 -Mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 2
-Mercaptobenzimidazole Imidazoles such as zinc, phosphites such as tri(nonylphenyl)phosphite, etc. can be used. These anti-aging agents may be used in combination of two or more. The blending amount of the anti-aging agent is 0.00 parts by weight per 100 parts by weight of the rubber component.
The amount is 5 to 7 parts by weight, preferably 1 to 5 parts by weight.

Further, the rubber composition for vibration damping of the present invention may contain a crosslinking accelerator, if necessary. Examples of such crosslinking accelerators include metal oxides such as zinc white, magnesium oxide, litharge, red lead, white lead, and calcium hydroxide;
Fatty acids and derivatives thereof such as stearic acid, oleic acid, zinc stearate, and sodium stearate can be used. The blending amount of these crosslinking accelerators is 0.1 to 10 parts by weight per 100 parts by weight of the rubber component.

In the production of the anti-vibration rubber composition of the present invention, the blending ratio, blending method, and blending order of various additives and other rubbers used as necessary are not particularly limited.

In one example, natural rubber and/or copolymer rubber, their compounding ingredients excluding a low crosslinking agent, etc. are mixed using an internal kneading machine such as a Banbury mixer, and then a crosslinking agent is added using an open roll or the like. There is a way to add it.

The anti-vibration rubber composition of the present invention prepared as described above is crosslinked in accordance with the usual production of vulcanized rubber and molded into a rubber product of a desired shape.

[Example] The present invention will be described in detail below, but the embodiments of the present invention are not limited thereto.

Examples 1 to 7 and Comparative Examples 1 to 8 In each of the Examples and Comparative Examples, the anti-vibration rubber composition of the present invention and a comparative rubber composition were manufactured using the formulation shown in Table 1 below.

[Evaluation] The vibration-proof rubber composition obtained as described above.

Rubber products were produced by crosslinking each product according to a conventional method for producing vulcanized rubber. The physical properties of these rubber products are shown in Table 2 below. The tensile properties, elongation fatigue test, and compression set of the rubber products shown in Table 2 below were measured as follows.

(1) Tensile properties Measured according to JIS K6301.

(2) Extensional fatigue test Using an extensional fatigue tester (manufactured by Iwamoto Seisakusho), the occurrence test was conducted using J
15 in an atmosphere of 100℃ using a No. I83 dumbbell.
A test was conducted in which 0% elongation was repeated, followed by elongation and bending, and the number of times it took for the rubber product to crack was evaluated.

In addition, the growth test used a dumbbell with a width of 7m++a, made a 0°5+nm scratch in the center, and repeated 110% elongation.
It was evaluated in the same way as the development test. It has good durability under high temperature conditions. This was used as an index for durability evaluation.

(3) Compression set The compression set was measured after 70 hours in a 120°C atmosphere according to JIS K6301. This was used as an index for evaluating wear resistance.

As can be understood from the results shown in Table 2 above, the rubber products obtained by crosslinking the anti-vibration rubber compositions of the examples of the present invention have excellent heat resistance, durability at high temperatures, and resistance to set. (compression set) is significantly superior.

On the other hand, Comparative Example 1 has poor heat resistance. Moreover, Comparative Examples 2 to 3 and Comparative Examples 5 to 8 are inferior in heat resistance and fatigue resistance, and Comparative Example 4 is inferior in durability, and is therefore unsuitable for the anti-vibration rubber targeted by the present invention. .

[Effects of the Invention] As explained above, according to the anti-vibration rubber composition of the present invention, it is possible to obtain a rubber product with excellent heat resistance, fatigue resistance, and durability. Therefore, it is suitable for use as anti-vibration rubber for automobiles such as engine mounts, strut mounts, suspension bushes, and exhaust mounts, as well as anti-vibration rubber for railway vehicles, construction vehicles, ships, industrial machinery, and OA equipment.

Patent applicant: Japan Synthetic Rubber Co., Ltd. hand Continued Supplementary Positive book (spontaneous) June 12, 1990 l.Indication of incident 1990 Patent Application No. 126312 name of invention Composition for vibration-proof rubber 3. Person who makes corrections Relationship with the incident

Claims (1)

[Claims] Natural rubber and/or polyisoprene rubber 50-90
An organic peroxide was used as a crosslinking agent for a rubber component containing 10 to 50% by weight of ethylene-α-olefin-nonconjugated diene copolymer rubber and/or ethylene-α-olefin copolymer rubber. A vibration-proof rubber composition with excellent heat resistance and durability.