JPH055048A - Anti-vibration rubber composition - Google Patents

Abstract

(57) [Summary] [Purpose] Achieving a low kinetic magnification with an appropriate vulcanization rate and metal adhesion. [Constitution] 0.5 parts by weight or more of a sulfur or thiuram compound or thiazole compound and 0.3 parts by weight or more of a peroxide compound are used together as a vulcanizing agent with respect to 100 parts by weight of a raw rubber. .. Then, with the above composition, the static spring constant is large, the dynamic spring constant is small, and the dynamic magnification is low. Using 60 parts by weight or more of the raw rubber as natural rubber or isoprene rubber is advantageous from the viewpoints of cost reduction and ensuring vibration damping performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration rubber composition, particularly an anti-vibration rubber composition used for automobiles.

[0002]

2. Description of the Related Art Conventionally, in an automobile, for example, various vibrations and noises generated from an engine, a power transmission unit, a rotation of an undercarriage, and a drive unit are absorbed or reduced to keep each unit at a predetermined position. BACKGROUND ART Antivibration rubbers of various shapes and performances are used in each part in order to fully exert their functions and to remove unpleasant vibrations and noises to improve the riding comfort of automobiles. For these anti-vibration rubbers, conventionally, a vulcanized rubber composition using natural rubber or natural rubber and another diene rubber as a raw material rubber has been mainly used (see, for example, JP-A-1-207338). ..

In recent years, the temperature inside the engine room has tended to rise due to trends such as high power output, high speed operation, and restriction of air inflow into the engine room to reduce air resistance. Therefore, anti-vibration rubbers such as engine mounts used in the engine room are used under higher temperature conditions than before, and due to space saving and increase of various parts around the engine, anti-vibration rubbers are With a smaller shape than before, it is now in a situation where it is necessary to bear a load equal to or greater than that of the past, and anti-vibration rubber for automobiles has a high elastic modulus (high elastic modulus) under extremely severe conditions and Dynamic ratio, which is the ratio of the dynamic spring constant to the dynamic spring constant, is low (low dynamic ratio) and is required to have durability.

Conventionally, as this type of anti-vibration rubber, a natural rubber is mixed with a diene rubber such as butadiene rubber, and further zinc white, stearic acid, carbon black, a vulcanizing agent, a vulcanization accelerator, etc. A blended product is used, and by increasing the addition amount of the vulcanizing agent, the high elastic modulus and the low dynamic ratio are achieved.

[0005]

However, in the method of increasing the amount of the vulcanizing agent added, not only the heat aging resistance deteriorates and the durability is problematic, but also the vulcanization rate increases and the molding processability increases. Also becomes significantly worse. In addition, there is room for improvement in terms of dynamic adhesiveness with applicable metals.

The present invention has been made in view of the above points, and provides a vibration-proof rubber composition having an appropriate vulcanization rate and adhesiveness to a metal and capable of achieving a low dynamic magnification. The purpose is to do.

[0007]

According to the invention of claim 1, 0.5 part by weight or more of sulfur, thiuram compound or thiazole compound and 0.3 part by weight of peroxide compound are used with respect to 100 parts by weight of raw material rubber. The above parts are used together. Further, in the invention of claim 2, the raw material rubber comprises 60 parts by weight or more of natural rubber or isoprene rubber. If necessary, short fibers may be mixed and dispersed.

[0008]

According to the inventions of claims 1 and 2, by using a sulfur, a thiuram compound or a thiazole compound and a peroxide compound in combination as a vulcanizing agent,
A low dynamic magnification can be realized, a mechanical loss (loss factor) increases, and vibration damping performance improves.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The anti-vibration rubber composition according to the present invention comprises a raw rubber 1 containing 60 parts by weight or more of natural rubber or isoprene rubber.
0.5 parts by weight or more of sulfur, thiuram-based vulcanization accelerator or thiazole-based vulcanization accelerator, and 0.3 parts by weight or more of peroxide-based vulcanizing agent are used in combination with respect to 00 parts by weight, It has a large static spring constant and a small dynamic spring constant.

The raw material rubber is natural rubber, styrene butadiene rubber, chloroprene rubber, isoprene rubber, ethylene propylene rubber, butyl rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, fluorine rubber, which have been conventionally used for vibration proof rubber. Halogenated butyl rubber, hydrogenated NBR, crosslinked rubber such as chlorosulfonated polyethylene, and polyolefin-based, polyester-based,
It is appropriately selected from thermoplastic elastomers such as polyether type polyamide type, polyurethane type and the like, but it is preferable to use 60 parts by weight or more of natural rubber or isoprene rubber from the viewpoint of cost reduction and ensuring vibration damping performance.

The vulcanizing agent may be sulfur, a thiuram compound such as tetramethylthiuram disulfide, tetramethylthiuram monosulfide, or 2- (4morphonolinodithio).
Thiazol-based compounds such as benizothiazole, dicumyl peroxide, 2,5-dimethyl-2,5 (di-tobutyltylperoxy) hexane, 1,1 di-tert-butylperoxy-3,3,5-trimethylcyclohexane It has been confirmed that the use of such a peroxide compound in combination has a low dynamic ratio and does not deteriorate the moldability. Further, reinforcing agents such as carbon black and inorganic fillers such as silica, calcium carbonate, talc and clay can be arbitrarily selected.

Further, in the above-mentioned rubber composition, extender oil for rubber, chemicals for rubber, and additives for rubber are blended, if necessary. And as the extender oil, aromatic type,
Naphthene-based and paraffin-based extenders for rubber are typical and preferable. Further, as a rubber chemical and an additive for rubber, vulcanization accelerators such as zinc white and stearic acid, sulfenamide-based, thiuram-based, thiazole-based, guanidine-based vulcanization accelerators, amine-based, pheno-based, etc. -Aluminum-based, sulfur-based, phosphorus-based anti-aging agents or antioxidants, ultraviolet absorbers, ozone deterioration inhibitors, tackifiers, plasticizers, etc. are used depending on the intended use of the anti-vibration rubber composition. It

According to the above constitution, 0.5 parts by weight or more of sulfur, thiuram compound or thiazole compound as a vulcanizing agent and 100 parts by weight of raw material rubber having a predetermined composition, and a peroxide compound. By using together with 0.3 parts by weight or more, it is possible to realize a low dynamic magnification, increase the mechanical loss (loss factor), and improve the vibration isolation performance. Further, the conventional method of increasing the amount of the vulcanizing agent was, the vulcanization rate was increased, the processability was deteriorated, the heat aging resistance was lowered, and the durability was deteriorated.
There is no such drawback.

The anti-vibration rubber composition has a large static spring constant, a small dynamic spring constant, and a small dynamic magnification due to the above-mentioned composition. Therefore, when applied to support center-support type propeller shafts for front-engine / rear-drive vehicles, the static spring constant becomes large in a static state such as when the vehicle starts, and dynamic statics such as during high-speed running. In this state, the dynamic spring constant becomes small, so that the vibration of the propeller shaft is effectively suppressed.

Next, a test conducted on the performance of the above-mentioned vibration damping rubber composition will be described.

After kneading at a compounding ratio (weight ratio) as shown in Table 1, the kneaded product was rolled by a roll and vulcanized, and then vulcanization characteristics in a grain direction, vibration characteristics, and heat aging. The sex was measured. The results are shown in Table 2.

The vulcanization characteristics were measured at a measurement temperature of 150 ° C. using a rheometer manufactured by Monisant. Further, as shown in FIG. 1, the vibration characteristics were measured by using a rectangular vibration-proof rubber test piece 11 formed in a cubic shape with a side of 50 mm, and the static spring constant was measured in the compression direction between 2 and 4 mm. Also, the dynamic spring constant was measured at 3 mm compression ± 1 mm at 10 Hz, and 10
It was measured at 3 mm compression ± 0.05 mm at 0 Hz. The anti-vibration rubber test piece 11 has a flange 14 in which screw rods 13a and 13b are erected above and below a rubber portion 12 having a cubic shape.
a and 14b are fixed.

[0019]

[Table 1]

[0020]

[Table 2]

From the above results, it was confirmed that the invention examples 1 and 2 have a smaller dynamic magnification and a larger loss factor than the comparative examples 1, 2 and 3. Comparative Example 1
With such a sulfur-based vulcanizing agent increasing method, t ₁₀ is short, processability during vulcanization is poor, and heat aging resistance is also poor. In addition, as in Comparative Example 2, dicumyl peroxide (peroxide-based vulcanizate)
Is less than 0.3 parts by weight, the effect of small dynamic ratio and large loss factor is small. Further, as in Comparative Example 3, when the sulfur content is 0.5 parts by weight or less, the adhesiveness with a metal, which is an essential performance requirement of the vibration-proof rubber, deteriorates.

Although short fibers are not mixed in the above embodiment, short fibers may be mixed. As short fibers,
The fiber length L is 10 mm or less, the ratio L / D of the fiber length L and the fiber diameter D is 40 or more, and the initial elastic modulus is 40 g / d or more. Examples of the short fiber having an initial elastic modulus of 40 g / d or more include Kevlar manufactured by DuPont Co., Ltd., para-aramid fiber such as Technora manufactured by Teijin Ltd., Nomex manufactured by DuPont Co., Ltd. Meta-aramid fibers such as Connex manufactured by Teijin Limited, aromatic fibers such as Vectra manufactured by Kuraray Co., Ltd., vinylon, polyester, polypropylene, nylon 6, nylon 6,6, cotton, manufactured by Mosant Co., Ltd. Synthesis of cellulose fiber such as Santoweb of
It is appropriately selected from natural and semi-synthetic fibers, glass, carbon, ceramics, Tyranno fibers manufactured by Ube Industries, Ltd., inorganic fibers such as boron, and metal fibers such as steel, stainless steel, and copper. From the viewpoint of increasing the elastic modulus, it is desirable to use short fibers having a high initial elastic modulus, and the fiber length L and the fiber diameter D are used.
It is better that the ratio L / D is larger. It is desirable that the fiber length L is also long, but if it exceeds 10 mm, the workability is significantly impaired, so it is necessary to set it to 10 mm or less. Further, short fibers having a ratio L / D of the fiber length L and the fiber diameter D of less than 40,
It has been confirmed that short fibers having an initial elastic modulus of less than 40 g / d are less effective for the purpose of increasing hardness (increasing elastic modulus) and lowering dynamic magnification. The mixing amount of the short fibers is not particularly limited, but from the viewpoint of improving the elastic modulus and ensuring processability, it is 3 to
30% by volume is desirable.

[0023]

According to the inventions of claim 1 and claim 2,
As a vulcanizing agent, sulfur, thiuram-based compound or thiazole-based compound, and peroxide-based compound are used in combination, so that a low dynamic magnification can be realized and mechanical loss (loss factor) becomes large. , The anti-vibration performance is improved. In particular, the invention of claim 2 uses 60 parts by weight or more of natural rubber or isoprene rubber as the raw material rubber, and is therefore advantageous in terms of cost reduction and ensuring vibration damping performance.

[Brief description of drawings]

FIG. 1 is a perspective view of a square anti-vibration test piece used in a test for evaluating various performances of an anti-vibration rubber composition.

[Explanation of symbols]

 11 test pieces

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Claims (1)

1. A combination of 0.5 part by weight or more of a sulfur, thiuram compound or thiazole compound and 0.3 part by weight or more of a peroxide compound with respect to 100 parts by weight of a raw material rubber. An anti-vibration rubber composition, which is used as 2. The anti-vibration rubber composition according to claim 1, wherein the raw rubber is 60 parts by weight or more of natural rubber or isoprene rubber.