JP2006199792A - Rubber composition for vibration-proof rubber and vibration-proof rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for vibration-proof rubber and a vibration-proof rubber, excellent in heat resistance (heat aging characteristics) and endurance, having low dynamic-to-static modulus ratio and excellent also in damping performance. <P>SOLUTION: The rubber composition for vibration-proof rubber comprises a rubber component composed of a blend material of a natural rubber with a butyl-based rubber, silica and a silane coupling agent, sulfur, an alkylphenol disulfide and/or a bismaleimide. In the rubber composition, BET specific surface area of the silica is 70-240 m<SP>2</SP>/g and the compounding amount of the silica in the rubber composition is 10-100 phr. The silane coupling agent has a chemical structure containing a nitrogen and/or sulfur atom and the compounding amount of the silane coupling agent in the rubber composition is 1.0-10 mass% based on silica and the compounding amount of sulfur in the rubber composition is 0.1-1.0 mass% and the compounding amount of the alkylphenol disulfide or bismaleimide compound is 0.5-10 phr. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition for vibration-proof rubber and vibration-proof rubber, and in particular, a rubber component obtained by blending natural rubber and butyl rubber, silica as a filler, and crosslinking agent (vulcanizing agent). A rubber composition for rubber having a high heat resistance, high durability, low dynamic magnification, and high damping anti-vibration rubber, and a rubber member comprising the rubber composition for anti-vibration rubber It is related with the anti-vibration rubber.

  Industrial anti-vibration pads, anti-vibration mats, rail slab mats, pads, automotive engine mounts, strut mounts, bushing and other anti-vibration rubbers, especially automotive anti-vibration rubbers, weights to support A vibration-proof function that absorbs and suppresses vibrations of objects and strength characteristics that support heavy objects are required. In other words, vibration-proof rubber is required to have improved dynamic characteristics, particularly lower dynamic magnification (lower dynamic magnification). On the other hand, in order to support a vibrating body such as an engine, a certain degree of fatigue resistance is required. It is necessary to ensure the property (static elastic modulus).

  Conventional rubber compositions for anti-vibration rubbers have been generally blended with diene rubber components such as natural rubber and carbon black as a filler, which balances the dynamic characteristics and anti-fatigue properties of anti-vibration rubbers. Therefore, it has been proposed to use a large particle size / high structure carbon black having a large particle diameter (small specific surface area) and a developed structure (Japanese Patent Application No. 2004-334785).

  Further, a rubber composition for vibration-proof rubber containing silica as a filler is also known. In this case, a bismaleimide compound is used together (Japanese Patent Application No. 2004-295716) and a silane coupling agent is used together. (Japanese Patent Application No. 2004-221484) has been proposed, but satisfactory results have not been obtained in achieving both high damping performance and low dynamic magnification.

In the anti-vibration rubber, high damping and low dynamic magnification are in a trade-off relationship. In order to overcome this problem, conventionally, a rubber component obtained by blending a diene rubber and an isobutylene-brominated paramethylstyrene copolymer is used (JP-A-8-134269), or a rubber having a low dynamic magnification. Techniques have been proposed in which materials exhibiting high attenuation in a matrix are dispersed in a sea-island structure.
Japanese Patent Application No. 2004-334785 Japanese Patent Application No. 2004-295716 Japanese Patent Application No. 2004-221484 JP-A-8-134269

  As described above, in a rubber vibration isolator, high damping and low dynamic magnification are in a trade-off relationship, and in the past, those that can still be sufficiently satisfied with both high damping and low dynamic magnification are compatible. In particular, a method of dispersing a material exhibiting high attenuation in a rubber matrix having a low dynamic magnification in a state of a sea-island structure in advance creates a master batch of the material exhibiting high attenuation for property development. There is still a production problem that is necessary.

  Also, in recent years, the temperature in the engine room tends to increase with the increase in the output of the automobile and the space saving in the engine room, and the requirements for the heat resistance and heat aging resistance of the anti-vibration rubber for automobiles have become severe. In the prior art, heat aging resistance important as a vibration-proof rubber property is not considered.

  Accordingly, an object of the present invention is to provide a rubber composition for a vibration-proof rubber and a vibration-proof rubber that are excellent in heat resistance (heat aging resistance) and durability, have a low dynamic magnification, and have excellent damping performance.

  The rubber composition for vibration-proof rubber of the present invention (Claim 1) includes a rubber component made of a blend material of natural rubber and butyl rubber, silica and a silane coupling agent, sulfur, alkylphenol disulfide and / or bis. And a maleimide compound.

  The rubber composition for vibration-proof rubber according to claim 2 is characterized in that, in claim 1, natural rubber 80 to 20 phr and butyl rubber 20 to 80 phr are included.

The rubber composition for an anti-vibration rubber according to claim 3 is the rubber composition according to claim 1 or 2, wherein the silica has a BET specific surface area of 70 to 240 m ² / g, and the silica content in the rubber composition is 10 to 100 phr, and The silane coupling agent has a chemical structure containing nitrogen and / or sulfur atoms, and the amount of the silane coupling agent in the rubber composition is 1.0 to 10% by mass relative to silica.

  The rubber composition for an anti-vibration rubber according to claim 4 is the rubber composition according to any one of claims 1 to 3, wherein the amount of sulfur in the rubber composition is 0.1 to 1.0 phr, and the amount of alkylphenol disulfide is 0.00. It is characterized by being 5 to 10 phr.

  The rubber composition for an anti-vibration rubber according to claim 5 is the rubber composition according to any one of claims 1 to 3, wherein the amount of sulfur in the rubber composition is 0.1 to 1.0 phr and the amount of bismaleimide compound is 0. 5 to 10 phr, and the bismaleimide compound is N, N′-m-phenylenebismaleimide and / or N, N ′-(4,4′-diphenylmethane) bismaleimide.

  The anti-vibration rubber of the present invention (Claim 6) is characterized by comprising a rubber member made of the rubber composition for anti-vibration rubber of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the anti-vibration rubber which is excellent in heat resistance (heat aging resistance) and durability, is low dynamic magnification, and is excellent also in damping performance is provided.

  The mechanism of the effect of improving various characteristics in the present invention is as follows.

  That is, in the present invention, silica is used as a filler for reinforcing and reducing the dynamic magnification and a silane coupling agent is blended to improve the dispersibility of silica and to provide dynamic elasticity resulting from the interaction between silicas. It is possible to further increase the strength and reduce the dynamic multiplication by suppressing the increase in the rate. In addition, this sufficiently enhances the rubber strength and improves the durability by increasing the interaction between the silica and the matrix rubber while sufficiently exerting the reinforcement and the low dynamic multiplication by the silica.

  In a system in which silica is added as a filler for low dynamics, the damping performance generally decreases. In the present invention, however, natural rubber is blended with butyl rubber for high damping as a rubber component. By using this, sufficient damping capacity is secured.

  In addition, sulfur is generally used as a rubber cross-linking agent, but in the present invention, by using an alkylphenol disulfide and / or bismaleimide compound together with sulfur as a cross-linking agent, the amount of sulfur is reduced while ensuring the cross-linking density. And heat resistance can be improved.

Hereinafter, embodiments of the rubber composition for vibration-proof rubber and the vibration-proof rubber of the present invention will be described in detail.
[Rubber component]
In the present invention, a natural rubber and a butyl rubber such as butyl rubber or a blend of one or more halogenated butyl rubbers such as brominated butyl rubber and chlorinated butyl rubber are used as the rubber component. If the content of natural rubber in the rubber component is too high, the amount of butyl rubber will be relatively reduced, and the effect of improving the damping performance due to the butyl rubber cannot be obtained sufficiently. As a result, the necessary physical properties of the rubber cannot be ensured, and the rubber strength and durability are poor. Accordingly, it is preferable to mix and use natural rubber at a blending ratio of 80 to 20 phr, particularly 70 to 30 phr, and butyl rubber at a blending ratio of 20 to 80 phr, particularly 30 to 70 phr. If it is this range, the rubber strength and durability improvement effect by natural rubber can be obtained together with the improvement effect of damping performance by butyl rubber, and a good anti-vibration rubber can be obtained.

[Silica and silane coupling agents]
Silica is formulated for low dynamic magnification and the reinforcement, it is preferable that the silica is a BET specific surface area of 70~240m ² / g, in particular 100 to 200 m ² / g, also the amount thereof It is preferably 10 to 100 phr, particularly 20 to 80 phr. When the silica has a large BET specific surface area of less than 70 m ² / g, the reinforcing effect is low, so the rubber properties are deteriorated and the durability is inferior. With a small particle diameter exceeding 240 m ² / g, Further, since dispersion in the rubber composition becomes difficult, the durability is lowered and the dynamic magnification is also deteriorated. In addition, if the blending amount of silica is less than 10 phr, the reinforcement and low dynamic ratio cannot be sufficiently achieved by blending silica, and the physical properties of rubber are deteriorated and the durability is deteriorated. If it exceeds, the dispersion into the rubber composition becomes difficult, and the physical properties and dynamic magnification of the rubber deteriorate.

As silica, various commercially available ones having a BET specific surface area of 70 to 240 m ² / g can be preferably used. The term “silica” in the present invention is a broad concept including silicon dioxide, silicic acid, and silicate containing SiO ₂ in the composition formula, but silicon dioxide that is anhydrous silicic acid has the above-mentioned effects. From the point of view, it is preferable. In addition, two or more types of silica having different types or different BET specific surface areas may be used in combination.

  The silane coupling agent is blended in order to improve the dispersibility of the silica and the affinity with the matrix rubber. It is preferable that When the amount of the silane coupling agent is less than 1.0% by mass with respect to silica, the compounding effect as a coupling agent is not sufficiently exhibited, the dynamic magnification is deteriorated, and even if it is added in excess of 10% by mass, it is effective. There are no differences.

  Examples of the silane coupling agent include vinyltriethoxysilane, vinyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4-epoxycyclohexyl) -ethyltri. Methoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, N- (β-aminoethyl) -γ -Aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, and γ-trimethoxysilyl Propyl di Examples thereof include tetrasulfides such as methylthiocarbamyl tetrasulfide, γ-trimethoxysilylpropylbenzothiazyl tetrasulfide, and bis [3- (triethoxysilyl) propyl] tetrasulfide.

  As the silane coupling agent, those having a chemical structure containing nitrogen and / or sulfur atoms are preferable from the viewpoint of affinity with butyl rubber, and as such silane coupling agents, known commercially available products are used. For example, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane Tetrasulfides such as methoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, bis [3- (triethoxysilyl) propyl] tetrasulfide, γ-trimethoxysilylpropylbenzothiazyltetrasulfide, etc. In particular, bis (3-triethoxysilylpropyl) te Trasulfide (“Si69” manufactured by Degussa) and γ-mercaptopropyltrimethoxysilane (“SH6062” manufactured by Toray Dow Corning) can be preferably used. These may be used alone or in combination of two or more.

  The silane coupling agent may be included in the rubber composition by surface-treating silica with the silane coupling agent and blending the surface-treated silica, or may be blended by adding at the time of preparing the rubber composition. .

[Sulfur and alkylphenol disulfide and / or bismaleimide compounds]
In the present invention, sulfur and an alkylphenol disulfide and / or bismaleimide compound are used in combination as a crosslinking agent (vulcanizing agent).

  Examples of the alkyl group of the alkylphenol disulfide include an amyl group.

  Examples of the bismaleimide compound include N, N′-o-phenylene bismaleimide, N, N′-m-phenylene bismaleimide, N, N′-p-phenylene bismaleimide, N, N ′-(4 , 4′-diphenylmethane) bismaleimide, 2,2-bis [4- (4-maleimidophenoxy) phenyl] propane, bis (3-ethyl-5-methyl-4-maleimidophenyl] methane, and the like. One of these bismaleimide compounds may be used alone, or two or more thereof may be used in combination, and among these bismaleimide compounds, N, N′-m-phenylenebismaleimide and / or N , N ′-(4,4′-diphenylmethane) bismaleimide is particularly preferred because of its remarkable effect.

  In the present invention, when sulfur and alkylphenol disulfide are used in combination, the amount of sulfur in the rubber composition is 0.1 to 1.0 phr, the amount of alkylphenol disulfide is 0.5 to 10 phr, particularly 2.0 to 5 phr. The total amount of sulfur and alkylphenol disulfide is preferably 1.0 to 10 phr, and particularly preferably about 2.0 to 5.0 phr. In either case, the crosslink density of the vibration-proof rubber obtained is less than the lower limit, the rubber physical properties are remarkably deteriorated, and the heat resistance is deteriorated if the upper limit is exceeded.

  Moreover, when using together sulfur and a bismaleimide compound, the compounding quantity of sulfur in a rubber composition is 0.1-1.0 phr, the compounding quantity of a bismaleimide compound is 0.5-10 phr, especially 2.0-5. The total amount of sulfur and the bismaleimide compound is preferably 1.0 to 10 phr, and particularly preferably about 2.0 to 5.0 phr. In either case, the crosslink density of the vibration-proof rubber obtained is less than the lower limit, the rubber physical properties are remarkably deteriorated, and the heat resistance is deteriorated if the upper limit is exceeded.

  Alkylphenol disulfide and bismaleimide compound may be used together with sulfur. In that case, the total of alkylphenol disulfide and bismaleimide compound is 0.5 to 10 phr, particularly 2.0 to 5.0 phr, sulfur and alkylphenol. The total of the disulfide and the bismaleimide compound is preferably about 1.0 to 10 phr, particularly about 2.0 to 5.0 phr.

[Other ingredients]
In addition to the rubber component, silica, silane coupling agent, and sulfur as a crosslinking agent (vulcanizing agent) and an alkylphenol disulfide and / or bismaleimide compound, the rubber composition for vibration-proof rubber of the present invention is necessary. Accordingly, usual rubber additives such as process oil and vulcanization accelerator can be blended.

  Examples of the process oil that can be used in the present invention include paraffinic, naphthenic, and aromatic oils. Aromatic oils are preferred for applications that place importance on durability, and the amount used is 0 to 100 phr, and if it exceeds 100 phr, the durability of the vibration-proof rubber is remarkably deteriorated.

  The vulcanization accelerator that can be used in the present invention is not particularly limited, but preferably CZ (N-cyclohexyl-2-benzothiazolesulfenamide), MBT (2-mercaptobenzothiazole), DM ( Examples include thiazole vulcanization accelerators such as dibenzothiazyl disulfide) and CBS (N-cyclohexyl-2-benzothiazylsulfenamide), and guanidine vulcanization accelerators such as DPG (diphenylguanidine). The amount used is 0.1 to 5 phr, preferably 0.2 to 3 phr.

  In the present invention, besides these, RD (polymerized 2,2,4-trimethyl-1,2-dihydroquinoline), 6C (N-1,3-dimethylbutyl-N′-), which is usually used in the rubber industry. Additives such as anti-aging agents such as phenyl-p-phenylenediamine), zinc white (ZnO), stearic acid, wax, antioxidants, ozone degradation inhibitors, and silane coupling agents can also be blended.

  Furthermore, in this invention, you may mix | blend carbon black as a filler and the effect of an adhesive improvement with a metal member is show | played by mix | blending carbon black. In this case, the carbon black to be used is preferably a carbon black having a large particle size such as N550, N762, and N880, and the blending amount in the rubber composition is 5 to 100 phr, and the total blending amount with silica is 20 in particular. It is preferably ˜80 phr.

[Anti-vibration rubber]
The anti-vibration rubber of the present invention comprises the above rubber component, silica, silane coupling agent, sulfur, alkylphenol disulfide and / or bismaleimide compound, and various additives blended as necessary, such as a roll, an internal mixer, etc. The rubber composition for an anti-vibration rubber of the present invention obtained by kneading using a kneader can be obtained by vulcanization after molding.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

In the following Examples and Comparative Examples, silica, carbon black, silane coupling agent, alkylphenol disulfide, and bismaleimide compound blended in the rubber composition are as follows.
Silica A: trade name “Nipsil AQ” manufactured by Tosoh Silica Co., Ltd. (BET specific surface area = 1)
90m ² / g)
Silica B: Product name “Nipsil ER” manufactured by Tosoh Silica Corporation (BET specific surface area = 1)
00m ² / g)
Silica C: trade name “Nipsil E75” manufactured by Tosoh Silica Corporation (BET specific surface area =
45m ² / g)
Carbon Black: Asahi Carbon Co., Ltd. product name “N550”
Silane coupling agent: Trade name “Si69” manufactured by Degussa
Bis (3-triethoxysilylpropyl) tetrasulfide Alkylphenol disulfide: Trade name “Vultac5” manufactured by ATOFINA
N, N′-m-phenylenebismaleimide: trade name “Barnock P” manufactured by Ouchi Shinsei Chemical Co., Ltd.
M "

Examples 1-7, Comparative Examples 1-4
The rubber composition was kneaded with the formulation shown in Table 1, vulcanized at 150 ° C. for 20 minutes, and then evaluated by the following test method. The results are shown in Table 1.
Mooney viscosity: Conforms to JIS K 6300.
Rubber hardness Hs: Conforms to JIS K 6253 (type A).
Tensile strength Tb: compliant with JIS K 6251.
Tensile elongation Eb: compliant with JIS K 6251.
Heat resistance ΔEb: Under the condition of heat aging at 100 ° C. and 100 hours, the tensile elongation Eb
Change rate of ΔEb ≦ 40%, “◯”,
Evaluated as “x”.
Elongation change rate ΔEb
= {1- (Eb (after heat aging) / Eb (before heat aging))} × 100
Static spring constant Ks: Conforms to JIS K 6385.
Loss coefficient tan δ: Conforms to JIS K 6385. (15Hz)
Dynamic spring constant Kd ₁₀₀ : Conforms to JIS K 6385. (100Hz)
Dynamic magnification Kd ₁₀₀ / Ks: Conforms to JIS K 6385.
Dynamic characteristics: Based on JIS K 6385, dynamic ratio of Ks comparison and dynamic ratio of tan δ comparison
The dynamic characteristics are comprehensively judged from the rate, and rated as “good”, “good”, or “bad”.
I was worth it.

  From Table 1, it is excellent in heat resistance (heat aging resistance) and durability by blending silica, silane coupling agent, and sulfur with alkylphenol disulfide or bismaleimide compound into a blend of natural rubber and butyl rubber. It can be seen that an anti-vibration rubber having a low dynamic magnification and excellent damping performance can be obtained.

Claims (6)

A rubber component made of a blend material of natural rubber and butyl rubber;
Silica and silane coupling agents;
A rubber composition for an anti-vibration rubber, comprising sulfur and an alkylphenol disulfide and / or bismaleimide compound.   The rubber composition for vibration-proof rubber according to claim 1, comprising natural rubber 80 to 20 phr and butyl rubber 20 to 80 phr. In Claim 1 or 2, the BET specific surface area of a silica is 70-240 m < ² > / g, the silica compounding quantity in a rubber composition is 10-100 phr, and a silane coupling agent contains a nitrogen and / or a sulfur atom. A rubber composition for an anti-vibration rubber having a chemical structure, wherein a compounding amount of a silane coupling agent in the rubber composition is 1.0 to 10% by mass with respect to silica.   4. The anti-vibration rubber according to claim 1, wherein the rubber composition has a sulfur content of 0.1 to 1.0 phr and an alkylphenol disulfide content of 0.5 to 10 phr. Rubber composition.   4. The rubber composition according to claim 1, wherein the amount of sulfur in the rubber composition is 0.1 to 1.0 phr, the amount of bismaleimide compound is 0.5 to 10 phr, and the bismaleimide compound is N. , N′-m-phenylene bismaleimide and / or N, N ′-(4,4′-diphenylmethane) bismaleimide, a rubber composition for vibration-proof rubber.   An anti-vibration rubber comprising a rubber member comprising the rubber composition for an anti-vibration rubber according to any one of claims 1 to 5.