JPH08134269A - Vibration-insulating rubber composition - Google Patents

Abstract

PURPOSE: To obtain a vibration-insulating rubber compsn. which has a high tan δ value and a low dynamic-to-static modulus ratio by using a coplymer of isobutylene with a partially brominated p-methylstyrene. CONSTITUTION: Isobutylene is coplymerized with a partially brominated p- methylstyrene to give a coplymer having a bromine content of 0.8-2wt.%. The copolymer is blended with a diene rubber in a wt. ratio of (10:90)-(100:0).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber anti-vibration rubber composition for preventing various vibrations and noises.

[0002]

2. Description of the Related Art Conventionally, anti-vibration rubber has been used to prevent vibration and noise, and anti-vibration effects have been achieved in various places.
The properties required for most anti-vibration rubber are:
Ideally, tan δ is large in the low-frequency and high-strain region, and the dynamic magnification (ratio of the dynamic elastic modulus and the static elastic modulus) is low in the high-frequency and low-strain region. Therefore, a rubber material having a large tan δ and a low dynamic magnification is also required as a rubber material for the anti-vibration rubber, but a large tan δ and a low dynamic magnification are in a trade-off relationship, and either characteristic is prioritized. ,
Alternatively, a balanced rubber material is currently used as a vibration-proof rubber. In order to obtain such ideal characteristics, a structure is devised such as enclosing a liquid such as ethylene glycol.

The anti-vibration rubber which is filled with a liquid and has the above-mentioned ideal characteristics is complicated because of its complicated structure, which is troublesome to manufacture, and the number of parts increases, which makes it very expensive. In addition, in the liquid-filled anti-vibration rubber, ta
Since nδ is obtained, there is a disadvantage that a high tanδ characteristic can be obtained only in the direction in which the liquid resonance appears.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above problems and provide a rubber material having ideal directional characteristics for a vibration-proof rubber having a large tan δ and a low dynamic magnification.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a part of paramethylstyrene is brominated with a copolymer of isobutylene and paramethylstyrene. By using the above copolymer, the anti-vibration rubber composition for the above purpose was successfully obtained, and the present invention was completed. That is, the anti-vibration rubber composition of the present invention is a copolymer of isobutylene and paramethylstyrene, and is characterized by using a copolymer obtained by brominated a part of paramethylstyrene. Incidentally, the copolymer brominated part of the para-methylstyrene,
Usually, the weight% of bromine is 100% by weight of the whole polymer.
The content of brominated is about 0.8 to 2% by weight.

The polymer of the present invention is effective alone or in a blend with a diene rubber. As the rubber to be blended, all diene rubbers such as natural rubber, IR, SBR and BR can be used. The blending ratio is not particularly limited, but if it is less than 10 parts by weight, the characteristics of the present polymer (high loss and low dynamic ratio) will not be clearly exhibited. Further, it is desired that the anti-vibration rubber has good fatigue property, but the fatigue property can be maintained by applying natural rubber or isoprene rubber as the diene-based blend rubber.

In the present invention, in addition to the above polymers, it is usually used as a compounding agent for anti-vibration rubber. For example, a reinforcing agent, a softening agent, an antiaging agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, a dispersant, a processing aid and the like can be appropriately added.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0009]

[Table 1]

[Table 2]

[Table 3]

[Table 4] (Note) Polymer: "XP-50 grade 89-1" (manufactured by Exxon Chemical Co.)

Blend composition of Tables 1 and 3 (blending unit: parts by weight)
The anti-vibration rubber composition was prepared according to. Hardness of rubber after vulcanization of this anti-vibration rubber composition, high elongation, static elastic modulus,
Tables 2 and 4 show the results of measuring the loss coefficient, the dynamic magnification, and the fatigue resistance.

The hardness, the strength and elongation, the static elastic modulus, the loss coefficient, the dynamic ratio, and the fatigue resistance were measured by the following methods. (1) Hardness and strong elongation Measured according to JIS K6301. (2) Static elastic modulus, loss coefficient, dynamic ratio. The measurement is performed using a sample having a thickness of 2 mm and a width of 5 mm. The static elastic modulus was calculated from the stress when stretched by 15%. The ratio of dynamic elastic modulus and static elastic modulus calculated from the stress when the dynamic magnification is 15%, the frequency is 15 Hz, the amplitude is 2% and the frequency is 100 Hz, the amplitude is 0.2%, and the respective sinusoidal amplitudes are applied. I asked more. The loss coefficient was calculated from the stress and the lag angle when the sinusoidal amplitude of 15 Hz, the amplitude of 2%, and the sinusoidal amplitude of 100 Hz and the amplitude of 0.2% were applied in the state of being extended by 15%. (3) Fatigue test, the test sample is adhered to the anti-vibration rubber fitting 1 (material: SPCC-SD) shown in FIG. 2 (after blasting, both the undercoat Chemlock 205 and the overcoat Chemlock 220 are loaded as an adhesive. Manufactured by the company) was applied, and a standard shape vibration-proof rubber A (length 40 mm, diameter 36 mm) was vulcanized using each rubber composition. The sample was subjected to 0 ± 5 in the shearing direction at 25 ° C. as shown in FIG.
A constant strain repetitive amplitude of 0% (3 Hz) was given, and the number of times until a crack of 1 cm was generated was evaluated.

[Examples] In Examples 1 to 5, the blending ratio of the natural rubber and the copolymer was changed. Comparative Example 1
Is a compounded rubber in which the polymer is 100. Comparative Examples 2 to 6 are general formulations used for anti-vibration rubbers as shown in Table 1. The properties of each rubber are shown in Table 2. Also, the dynamic magnification and tan of each rubber material
The relationship with δ is shown in FIG.

As the vibration-proof rubber material, a material having a large tan δ and a low dynamic magnification, that is, a material in the lower right direction in FIG. 1, is ideal. By blending the above-mentioned copolymer, tan δ is large and ideal dynamic characteristics are low. This characteristic becomes more remarkable as the blending ratio of the copolymer is increased, and the blending of only the copolymer has the largest tan δ and the low dynamic magnification. In Comparative Examples 7 and 8, S was used as a diene blend rubber.
It is a blend of BR and BR. Dynamic characteristics are tan
Although it is an ideal one with a large δ and a low dynamic magnification,
Fatigue is inferior to the NR blended system (Example 3). Therefore, the NR blend is suitable for application to the anti-vibration rubber used in a place where fatigue is severe.

[0014]

As described above, the use of a copolymer of isobutylene and paramethylstyrene in which a part of paramethylstyrene is brominated as the anti-vibration rubber makes it possible to obtain t
An anti-vibration rubber composition having a large an δ and a low dynamic magnification is provided.

[Brief description of drawings]

FIG. 1 is a relational diagram showing dynamic magnification / tan δ (examples and comparative examples) of various anti-vibration rubber compositions according to the present invention.

FIG. 2 is a schematic cross-sectional view of anti-vibration rubbers showing a fatigue resistance measurement test sample of each anti-vibration rubber composition.

FIG. 3 is a schematic diagram showing a fatigue test method.

[Explanation of symbols]

 1 Anti-vibration rubber fittings 2 Anti-vibration rubber

Claims (4)

[Claims] 1. An anti-vibration rubber composition comprising a copolymer of isobutylene and paramethylstyrene, wherein a part of paramethylstyrene is brominated. 2. The anti-vibration rubber composition according to claim 1, wherein the polymer and the diene rubber are blended. 3. The blend ratio of the polymer and the diene rubber is the polymer / diene rubber = 10/90 to 100.
The anti-vibration rubber composition according to claim 1 or 2, wherein the anti-vibration rubber composition is / 0. 4. The natural rubber (N
R) or isoprene rubber (IR) is blended, The composition for antivibration rubbers of Claim 2 thru | or 3 characterized by the above-mentioned.