JPS6011753B2 - Anti-vibration rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration-damping rubber composition mainly composed of silicone rubber, and particularly aims to provide a rubber composition having excellent vibration-damping action over a wide temperature range.

BACKGROUND ART Various vibration-proofing materials using polymeric materials have been developed in the past, and their applications are wide-ranging, including home appliances, electronic computers, transportation such as automobiles and airplanes, and factory machinery.

Most of these anti-vibration materials using polymeric materials utilize the viscoelastic properties of polymers, particularly the phenomenon of increase in loss coefficient near the glass transition point of the material.

Therefore, the temperature range in which the vibration-proofing effect can be exhibited is limited to a narrow temperature range near the glass transition point of the material used.
Furthermore, considering the paper elasticity of the polymeric material, there is a correspondence between temperature and vibration frequency, so the frequency is also limited to a narrow range. As a result, its uses were extremely limited. An object of the present invention is to provide a vibration-isolating rubber composition that can maintain excellent vibration-isolating effects over a wide temperature and wide frequency range not found in conventional vibration-isolating rubbers.

Since silicone rubber generally has a glass transition point in an extremely low temperature range, it maintains stable viscoelastic properties over a wide temperature range near room temperature.

However, its loss coefficient is small and its anti-vibration effect is poor. The present inventors focused on the stable characteristics of this silicone rubber and studied a method of increasing the loss coefficient near room temperature without changing the glass transition temperature of L rubber.
They found that the objective could be achieved by blending polyisobutylene with silicone rubber.

That is, the present invention relates to a rubber composition for vibration isolation, which is characterized by blending polyisobutylene with silicone rubber and vulcanizing the mixture. To further explain the present invention in detail, the silicone rubber used in the present invention is:
Methyl silicone, methyl phenyl silicone, methyl phenyl vinyl silicone, methyl vinyl silicone,
Raw rubber made of fluorosilicone polymers, or products based on these polymers, to which reinforcing fillers and the like are appropriately added.

Next, the polyisobutylene used in the present invention has a viscosity average molecular weight of about 50 as measured by the Staudinger method.
A value in the range of 00 to 50,000 is preferred.

If the average molecular weight is less than about 5,000, the affinity with silicone rubber will be extremely reduced and it will be easy to seep out onto the surface of silicone rubber. On the other hand, the average molecular weight is about 5000
If it is larger than 0, it becomes extremely difficult to mix into silicone rubber, and the glass transition of silicone rubber shifts to the high temperature side due to the addition of polyisobutylene.
As a result, the temperature dependence of the loss coefficient becomes large near room temperature. The vibration-proofing effect of a vibration-proofing rubber made by blending the polyisobutylene with silicone rubber increases in proportion to the amount of polyisobutylene blended, but the preferred blending ratio is 20 to 6 parts by weight per 10 parts by weight of silicone raw rubber. Parts by weight range.

If more than this is added, polyisobutylene will leach onto the surface when heated to high temperatures, causing problems. A vulcanizing agent for silicone rubber is added to the above compounding composition, and fillers and extenders are added if necessary, mixed in the usual manner using a roll machine, etc., and then vulcanized. shall be.

The rubber obtained by the above method exhibits a substantially constant vibration-proofing effect over a wide temperature range centered on room temperature, making it an extremely effective material.

In particular, it is effectively used as a component material for audio equipment that requires vibration-proofing effects over a wide temperature range and wide frequency range. This will be explained in more detail in Examples below.

Example 1 To 10 parts by weight of methylphenyl vinyl polysiloxane raw rubber, 5 parts by weight of reinforcing silica and 1 part by weight of thinner
The parts by weight are common, and the viscosity average molecular weight is about 10.
000 polyisoptylene was blended in the proportions shown in Table 1, kneaded with a roll for 15 minutes, and then vulcanized under heat and pressure at 170 qo for 10 minutes to prepare test pieces. The anti-vibration effect is
Evaluation was made by measuring impact resilience, which is related to loss coefficient.

This rebound resilience (%) means the ratio of the recovery energy to the deformation energy when a test piece is deformed by applying an impact.The smaller the value, the larger the loss coefficient, and the vibration The effect is shown to be good. Note that the measurement of impact resilience was in accordance with JIS-K6301. Table 1 The figure shows the impact resilience results of the rubbers having the compounding compositions shown in Table 1 in the range of -20°C to 40°C.

As can be seen from the figure, by blending polyisobutylene, the vibration damping effect is significantly improved while maintaining the temperature characteristics of silicone rubber. Example 2 Polyisobutylene having a viscosity average molecular weight of about 20,000 was blended with methylvinylpolysiloxane raw rubber and tripropropylmethylvinylsiloxane raw rubber with the composition shown in Table 2, and mixed and added in the same manner as in Example 1. A test piece was prepared by sulfurization.

The impact resilience of these test pieces was measured in the same manner as in Example 1, and the results were as shown in Table 2. No.
2 As shown in Table 2, the rubber made by blending polyisobutylene with silicone raw rubber and vulcanizing this has significantly lower impact resilience than the rubber made of silicone rubber alone. It can be seen that the vibration isolation effect was improved over a wide temperature range.

[Brief explanation of drawings]

The figure is a curve diagram showing the anti-vibration effect of the anti-vibration rubber composition of the present invention in Example 1.

Claims (1)

[Claims] 1. Polyisobutylene having an average viscosity and molecular weight in the range of 5,000 to 50,000 is blended and dispersed in an amount of 20 to 60 parts by weight to 100 parts by weight of silicone raw rubber, and then vulcanized. A vibration-proof rubber composition characterized by: 2. The vibration-damping rubber composition according to claim 1, wherein the silicone raw rubber is methyl silicone, methyl phenyl silicone, methyl vinyl silicone, methyl phenyl vinyl silicone, or fluorosilicone polymer.