JP2001011263A - Vibrationproof rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition which gives a vulcanizate having specified hardness and dynamic-to-static modulus ratio and suitable as a vibrationproof material by incorporating butyl rubber, EPDM having a specified Mooney viscosity, and a sulfur-base vulcanization accelerator into the same. SOLUTION: Based on 100 pts.wt, butyl rubber, this composition contains 20-100 pts.wt. EPDM having a mooney viscosity ML1+8 (100 deg.C) of about 50-100 and a sulfur-base vulcanization accelerator, Preferably, up to 200 pts.wt. plasticizer comprising a diester of an aliphatic or aromatic dicarboxylic acid is incorporated into the composition. The composition further contains carbon black, an acid acceptor (e.g. hydrotalcite or a divalent metal oxide or hydroxide), a process aid, and other necessary additives. The composition is vulcanized with a vulcanizing agent (e.g. zinc oxide) and a sulfur-base vulcanization accelerator to give a vulcanizate having a JIS A hardness of 17 or lower and a dynamic-to-static moldulus ratio kd(50 Hz)/kst of 2.0 or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a vibration-proof rubber composition. More specifically, the present invention relates to an anti-vibration rubber composition capable of providing a vulcanizate having a hardness and a dynamic magnification of a certain value or less.

[0002]

2. Description of the Related Art Butyl rubber (isobutylene-isoprene copolymer rubber) is widely used as an anti-vibration rubber material because of its excellent shock absorption and vibration damping properties. When used in such an application, a low spring constant is required for a product (mount) with a further reduction in the weight of the support component, and therefore, the hardness of the vulcanized product is required to be low.

[0003] The lowering of the hardness of butyl rubber is generally carried out by adding a plasticizer, but the upper limit of the amount added is about 50 phr from the viewpoint of processability. Is seen. In addition, when the hardness is reduced by adding a plasticizer, the dynamic magnification of the vulcanized product exceeds 2.0, and the product function as a vibration damping material cannot be satisfied.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vibration-insulating rubber composition having a hardness and a dynamic magnification of not more than a certain value and capable of providing a vulcanized product suitably used as a vibration-proof material. Is to do.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
Butyl rubber, Mooney viscosity ML _{1 + 8} (100 ° C) E of about 50-100
This is achieved by an anti-vibration rubber composition containing PDM and a sulfur-based vulcanization accelerator.

[0006]

DETAILED DESCRIPTION OF THE INVENTION A rubber composition obtained by blending carbon black with an EPDM-rich blend rubber comprising EPDM (about 90 to 50 parts by weight) and butyl rubber (about 10 to 50 parts by weight) is known. Although it is known that sulphate is used as a radiator packing or the like (JP-A-63-68684),
Its vulcanization is done with organic peroxide, partly due to its EPDM richness.

In the present invention, butyl rubber 100 is generally used.
EPDM with a specific Mooney viscosity of about 20 parts by weight
It is used as a butyl rubber-rich blend rubber of about 100 parts by weight, preferably about 20 to 60 parts by weight, and its vulcanization is also carried out using a sulfur-based vulcanization accelerator.

EP used by blending with butyl rubber
As DM, Mooney viscosity ML _{1 + 8} (100 ° C) is about 50-100,
Preferably about 50 to 60 are used. If the Mooney viscosity is less than this, the workability becomes defective,
On the other hand, if a material having a Mooney viscosity higher than this is used, the compatibility with butyl rubber will be lacking.

In order to reduce the viscosity of the vulcanizate, a plasticizer of about 200 parts by weight or less, preferably about 20 to 100 parts by weight, is added to 100 parts by weight of butyl rubber. Preferably, it is used. As a plasticizer,
Diesters of aliphatic dicarboxylic acids such as sebacic acid, azelaic acid and adipic acid or aromatic dicarboxylic acids such as phthalic acid such as butyl, 2-ethylbutyl, 2-ethylhexyl, octyl, isooctyl and isodecyl are used.

A composition containing, in addition to the above components, an acid acceptor such as carbon black, an oxide or hydroxide of a divalent metal or hydrotalcite, a processing aid, and other necessary additives. The vulcanization is carried out using a vulcanizing agent such as zinc oxide and a sulfur-based vulcanization accelerator, more specifically a thiuram-based or thiazole-based vulcanization accelerator.

The following thiuram-based or thiazole-based vulcanization accelerators are used. Thiuram vulcanization accelerator: R ₁ R ₂ : the same or different C ₃ -C ₈ alkyl groups x: 1-4 y: 1-2 M: metals such as Zn, Cu, Fe, Te with valence n R: alkyl group of _{C 3 ~C 8 M: Zn,} Cu, Fe, 2 -valent metal such as Te X: a hydrogen atom cyclohexyl, which is substituted by an alkyl group
N-monosubstituted amino group, dicyclohexyl group, oxydiethylene group,
N-disubstituted amino group substituted by dialkyl group etc.
(-NR ₁ R ₂ ) a thiocarbamoyl group N-disubstituted by an alkyl group, an alkylphenyl group, an alkylbenzyl group (-CS-N
R ₃ R ₄ )

[0012] In the case of a closed type using an intermix, a kneader, or the like, the composition using these components is prepared by simultaneously charging each component other than the vulcanizing agent and the vulcanization accelerator, and adding about 10%. After kneading for about 20 minutes, a vulcanizing agent and a vulcanization accelerator are charged and discharged after about 3 minutes.If an open roll is used, the blended rubber is wound around a roll, and the vulcanizing agent and the vulcanizing agent are vulcanized. After adding each component other than a sulfur accelerator, it is performed by finally adding a vulcanizing agent and a vulcanization accelerator.

The vulcanization of the composition thus prepared is carried out by press vulcanization performed at about 150 to 200 ° C. for about 5 to 20 minutes.

[0014]

According to the present invention, when a plasticizer is blended with butyl rubber, the limit of the hardness (JIS A) of the vulcanized product is limited to about 20, but the butyl rubber has a specific Mooney viscosity. EPDM is blended, and more preferably, by adding a plasticizer thereto and vulcanizing using a sulfur-based vulcanization accelerator, the hardness is reduced to 17 or less, and a vulcanizate having a dynamic magnification of 2.0 or less is obtained. Will be obtained.

As described above, the anti-vibration rubber composition of the present invention, which provides a vulcanizate having a low hardness and low dynamic magnification, can be effectively used as a molding material for anti-vibration rubber materials such as CD-ROM mounts and DVD-ROM mounts. Can be used.

[0016]

Next, the present invention will be described with reference to examples.

Example 1 Butyl Rubber (HT10-66 manufactured by Exxon) 100 parts by weight EPDM (Keltan 314 manufactured by DMS Japan) 20 20 [ML _{1 + 8} (100 ° C) 53] di (2-ethylhexyl) sebacate 60〃 HAF carbon Black 10 ス テ Stearic acid 1 〃 Tetramethylthiuram disulfide accelerator 1 〃 Dibenzothiazyl disulfide accelerator 1 マ グ ネ シ ウ ム Magnesium oxide 0.5 亜 鉛 Zinc oxide 5 〃 Knead the above ingredients with a kneader and mix at 180 ° C for 6 minutes. Press vulcanization was performed. Regarding the vulcanized product, normal physical properties (JIS K-6
301) and dynamic magnification Kd (50 Hz) / Kst.

Example 2 In Example 1, DMS Japan product Keltan was used as EPDM.
4703 [ML _{1 + 8} (100 ° C) 95] was used in the same amount.

Example 3 In Example 2, the amount of EPDM was changed to 50 parts by weight, and the amount of plasticizer was changed to 100 parts by weight.

Example 4 In Example 2, the amount of EPDM was changed to 100 parts by weight and the amount of plasticizer was changed to 200 parts by weight.

Comparative Example In Example 1, the amount of the plasticizer was changed to 40 parts by weight without using EPDM.

The measurement results in the above Examples and Comparative Examples are shown in the following table. Table Measurement Items Actual-1 Actual-2 Actual-3 Actual-4 Comparative Example [Physical Properties] Hardness (JIS A) 16 16 10 4 18 Tensile Strength (MPa) 4.1 4.2 2.5 1.3 3.3 Elongation (%) 800 780 870 950 600 100% modulus (MPa) 0.30 0.29 0.25 0.20 0.10 [Dynamic magnification] Kd (50Hz) / Kst 1.62 1.60 1.70 1.40 2.20

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F16F 1/36 F16F 1/36 E 15/08 15/08 DF Term (Reference) 3J048 AA01 BB10 3J059 AA10 BC06 BC19 GA50 4J002 BB152 BB181 EH097 EH147 EV166 EV326 FD027 FD156 GM00

Claims (3)

[Claims] 1. A butyl rubber, Mooney viscosity ML _{1 + 8} (100 ° C.)
A rubber composition comprising about 50 to 100 EPDM and a sulfur-based vulcanization accelerator. 2. The anti-vibration rubber composition according to claim 1, further comprising a plasticizer. 3. The hardness (JIS A) is 17 or less, and the dynamic magnification Kd
3. The vibration-insulating rubber composition according to claim 1, which gives a vulcanizate having (50 Hz) / Kst of 2.0 or less.