JP2897836B2 - Rubber composition for anti-vibration rubber - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a rubber composition for a vibration-proof rubber, and is a rubber composition mainly used for engine mounts having good heat resistance, low dynamic magnification and good adhesion.

(Prior Art) A so-called engine mount, which is a kind of anti-vibration rubber, is widely used to prevent the vibration of an automobile engine from being transmitted to a vehicle body.

This engine mount is in contact with and directly supports the engine.In recent years, the engine mount is used in a high-temperature range due to the recent increase in the output of the engine. ℃.

Therefore, heat resistance has been required for the engine mount itself.

In response to such demands, a compounding system using a reduced amount of sulfur in a rubber composition for an engine mount and using a large amount of a vulcanization accelerator has been frequently used.

However, there is a case where the heat resistance of the rubber, such as heat aging resistance and heat resistance, is not so improved because of the sulfur cross-linking and the required level cannot be satisfied.

Also, in this system, the dynamic elastic modulus Ed is higher than the static elastic modulus Es, so that the so-called dynamic magnification Ed / Es increases, and as a result, the vibration of the engine is transmitted to the vehicle body. That is, the original function of the vibration-proof rubber is reduced. The dynamic magnification is limited to about 1.4.

Further, in this system, the adhesion between the metal and the rubber is deteriorated, so that the metal and the rubber are apt to be separated from each other, which leads to a serious accident.

Generally, in order to lower the dynamic magnification Ed / Es, it is good to use carbon black having a relatively large particle size in the rubber compounding system, but in this case, the adhesion between the rubber and the metal is not sufficient and improvement is required. .

(Purpose) The present invention has made an effort to solve such a trade-off problem, and as a result, a compounding system using sulfur and bismaleimide having a specific chemical structure as a cross-linking agent has reduced the amount of sulfur and increased the amount of accelerator. It is based on two new findings that the dynamic elastic modulus rises less and the adhesiveness of rubber to metal is higher than that of the system. An object of the present invention is to provide a rubber composition for vibration-proof rubber having good adhesiveness.

(Constitution) The present invention is intended to achieve the above object, and is intended to achieve the object by using a specific vulcanization system and a specific particle size and carbon black as a filler. It is intended to provide a rubber composition for vibration-isolating rubber having heat resistance, low dynamic magnification characteristics, and good adhesion to metal, comprising natural rubber and diene-based synthetic rubber as main components. When sulfur and N, N'-m-phenylenebismaleimide are used as a sulfurizing agent and the particle size of carbon black is X (mμ) as a rubber reinforcing agent, the compounding amount Y (PHR) is 0.8X
+ 15 ≧ Y (however, when the calculated value exceeds 80, Y is set to 80).

Here, N, N'-m-phenylenebismaleimide used together with sulfur has the following chemical structure.

The amount used is 0.5 to 5 parts (PHR). In relation to the sulfur used in combination, the sulfur ratio is 0.5 to 10 parts.
Degree is used.

Since sulfur acts as an activator of N, N'-m-phenylenebismaleimide, it is necessary to use a small amount of sulfur, but if the amount is large (2PHR or more), the heat resistance of the rubber material decreases. There is a limit.

On the other hand, when N, N'-m-phenylenebismaleimide exceeds 5 parts, the vulcanization becomes extremely slow, and the dispersion in rubber becomes difficult. When the amount is less than 0.5 part, the effect of improving heat resistance is recognized. I can't.

On the other hand, as an anti-vibration rubber material for an engine mount, a material having a dynamic elastic modulus as low as possible to prevent transmission of engine vibration to a vehicle body is preferable. Specifically, a static elastic modulus Es of the rubber material and 100 Hz are preferable. The ratio (Ed / Es) of the dynamic elastic modulus Ed at 1.
Rubber of about 4 or less is often used.

In order to keep the dynamic magnification low, it has been found that it is preferable to use carbon black (35 mμ or more) having a relatively large particle size, such as FEF, SRF, or FT, within the above range.

The amount of use is limited to 80 parts (PHR). The limiting reason for this compounding amount is that, in order to keep the dynamic magnification low, it is preferable that the addition amount of carbon black is small, and that the low reinforcing carbon black having a large particle size is two. If the added amount exceeds 80 PHR, the kneading workability is deteriorated.

In addition, two or more types of carbon black may be used in combination. In this case, the particle size X of the carbon black is an average value according to the used weight of the carbon black particle size.

That is, the particle size X ₁ of the carbon black a ₁ PHR, particle size X ₂ of carbon black a ₂ PHR, if carbon black ...... particle diameter X ₁ to a combination of a _i PHR, represented by the following formula The Y value is calculated using the average particle size X.

In addition, regarding the particle size of carbon black, as described in the carbon black yearbook (1989),
T: 150 mμ (= nm), SRF: 65 mμ, FEF: 38 mμ, etc.

(Example) Experiment 1 N, N'-m-phenylenebismaleimide was added to a rubber compounding system together with sulfur as a vulcanizing agent, and heat resistance was evaluated. The rubber compounding system is as shown in Table 1, and the test results are shown in Table 2. The compounding agents and amounts of the vulcanizing system are shown in Table 2.

 Among the test items, the test after heat aging was performed as follows.

Eb retention: 100% × 24Hs with respect to the elongation at break in the tensile test before thermal aging expressed as a percentage of the elongation at break in the tensile test after heat aging. Compression set: The heat treatment condition during compression was 100%.
℃ × 22Hs Tensile test was conducted according to JIS K6301 (3) (dumbbell shape is JIS No. 3), compression set was JIS K6
Based on the 301 (10) compression set test.

As can be seen from these results, when N, N'-m-phenylenebismaleimide is added to the rubber compounding system together with sulfur as a vulcanizing agent, the heat aging resistance is excellent and the dynamic magnification (Ed / Es) is relatively high. It was found to be small and suitable as an anti-vibration rubber compound.

Experiment 2 In general, it is known that when sulfur as a vulcanizing agent is reduced, the adhesion between rubber and metal is deteriorated. When black is used as a reinforcing agent, a decrease in adhesion becomes apparent.

However, it was found that when N, N'-m-phenylenebismaleimide was used together with sulfur as a vulcanizing agent, a compound for a vibration-proof rubber excellent in vulcanization adhesiveness with a metal was obtained.
Here, an adhesion test between the rubber and the metal was performed according to the formulations shown in Table 3, and the results are shown in Table 4.

 Table 4 shows the amounts of the vulcanizing system.

In addition, the method of the adhesion test was measured by a test in which the rubber adhered to the JIS K6301 (8.3) metal piece was peeled in a direction of 90 degrees.

As can be seen from the test results, N, N'-m
-The compounding system using phenylene bismaleimide as a vulcanizing agent has excellent adhesive strength, and the state at the time of the peeling test shows that the adhesive layer does not peel and the rubber layer is the peeled surface, and The strength was revealed.

Experiment 3 As described above, as the vibration-proof rubber material for the engine mount, a material having as low a dynamic elastic modulus as possible is preferable in order to prevent transmission of engine vibration to the vehicle body. Specifically, as described above, it is desired to set the dynamic magnification to about 1.4 or less.

Here, the following experiment was conducted in order to optimize carbon black.

That is, the dynamic magnification was measured for each example according to the composition shown in Table 5. Table 6 shows the measurement results. The types and amounts of the carbon blacks used are as shown in Table 6.

The test results are shown in the table with the judgment of Δ ×. Even if the properties after heat aging were fairly good, sulfur and N, N′-m-phenylenebismaleimide were used as vulcanizing agents. Except for carbon black as a reinforcing agent having a predetermined particle size and a predetermined compounding amount, the dynamic magnification, which is the mission as an anti-vibration rubber, is increased to 1.4 or more, and is not usable. On the other hand, those in the range of the present invention can maintain the dynamic magnification at 1.4 or less, and can be said to be a good rubber composition for vibration-proof rubber.

(Effects) As described above, the present invention relates to a rubber compound mainly composed of natural rubber or gen-based synthetic rubber and N, N'-m together with sulfur.
-By using phenylene bismaleimide as a vulcanizing agent and compounding carbon black with a specific particle size and specific compounding amount as a reinforcing agent, low dynamic magnification, high heat resistance and adhesion to metals required for engine mounts All three conditions could be satisfied.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3:06 5: 3415)

Claims (1)

(57) [Claims] 1. A rubber composition for vibration-proof rubber comprising natural rubber or natural rubber and a diene-based synthetic rubber as main components, wherein sulfur and N, N'-m-phenylenebismaleimide are used as a vulcanizing agent for the rubber. When the particle size of carbon black is X (mμ) as a rubber reinforcing agent, its compounding amount Y (PHR)
, 0.8X + 15 ≧ Y (However, when the calculated value exceeds 80, Y
= 80). The rubber composition for an anti-vibration rubber according to the formula,