JP6248777B2 - Rubber composition for anti-vibration rubber and anti-vibration rubber - Google Patents

Description

  The present invention relates to a rubber composition for an anti-vibration rubber that can be suitably used for an anti-vibration rubber used in a high-temperature environment such as an automobile torsional damper, an engine mount, and a muffler hanger, and an anti-vibration rubber obtained by vulcanizing and curing the rubber composition. Related to rubber.

  Conventionally, in various vehicles such as automobiles, in order to improve the comfort of passengers, various anti-vibration materials have been arranged at sites that are sources of vibration and noise to reduce the intrusion of vibration and noise into the room. Attempts have been made. For example, for engines that are the main sources of vibration and noise, vibrations during engine operation are absorbed by using anti-vibration rubber for components such as torsional dampers and engine mounts. Intrusion and noise spread to the surrounding environment.

  As a basic characteristic of such an anti-vibration rubber, a strength characteristic that supports a heavy object such as an engine and an anti-vibration performance that absorbs and suppresses the vibration are required. Furthermore, when used in a high temperature environment such as an engine room, it has excellent strength characteristics, low dynamic magnification and excellent vibration proofing performance, as well as high heat resistance, durability, and resistance to settling. Is required. In particular, in recent years, the engine room temperature tends to rise as the engine output is increased and the space in the engine room is reduced due to the expansion of the indoor space, etc., and it is often used in more severe environments. Therefore, the requirements for heat resistance and the like of the vibration-proof rubber for automobiles are becoming more severe.

  In general, in order to improve the heat resistance and settling resistance of rubber, it is effective to reduce the amount of sulfur, but the dynamic magnification, which is an important characteristic as a vibration-proof rubber, tends to increase. In response to this, Japanese Patent Laid-Open No. 3-258840 (Patent Document 1) proposes adding a bismaleimide compound to a rubber composition, but still has a problem in durability. In addition, the applicant disclosed in Japanese Patent Application Laid-Open No. 2006-131871 (Patent Document 2) by blending a rubber composition with a specific bismaleimide compound, silica gel, and a silane coupling agent, thereby preventing the vibration-proof rubber member. We are proposing a technology to further improve vibration performance and heat resistance. Furthermore, in JP2009-96981A (Patent Document 3), a halogenated butyl rubber and a diene rubber are mixed and used, and two types of carbon black are separately dispersed in each of the halogenated butyl rubber and the diene rubber. Thus, it has been proposed to achieve both a low dynamic magnification and high damping in a vibration-proof rubber. As described above, various techniques for improving the performance of the anti-vibration rubber have been proposed. However, in the market, higher performance is required due to the above-described circumstances.

JP-A-3-258840 JP 2006-131871 A JP 2009-96981 A

  The present invention has been made in view of the above circumstances, and can effectively reduce compression set while maintaining good damping performance as a vibration-proof rubber, and has excellent heat resistance, torsional dampers for automobiles, An object of the present invention is to provide a rubber composition for a vibration-proof rubber that is suitably used as a vibration-proof rubber used in high-temperature environments such as engine mounts and muffler hangers.

  As a result of diligent study to solve the above-mentioned problems, the present inventor mixed and used natural rubber and butyl rubber as a rubber component, and blended with sulfur, alkylphenol disulfide, and a bismaleimide compound. By adjusting the rubber composition for anti-vibration rubber and, at that time, by optimizing the blending ratio of the bismaleimide compound to the alkylphenol disulfide, sufficient damping performance as an anti-vibration rubber can be obtained, and compression set The present invention has been completed by finding that it is possible to effectively improve the heat resistance and to effectively suppress the decrease in the rate of change in elongation during heat resistance and achieve good heat resistance.

Accordingly, the present invention provides the following rubber composition for vibration-proof rubber.
[Claim 1] A rubber component containing natural rubber and butyl rubber, sulfur, alkylphenol disulfide, N, N'-o-phenylene bismaleimide, N, N'-m-phenylene bismaleimide, N, N′-p-phenylenebismaleimide, N, N ′-(4,4′-diphenylmethane) bismaleimide, 2,2-bis [4- (4-maleimidophenoxy) phenyl] propane and bis (3-ethyl-5 -Methyl-4-maleimidophenyl) containing one or more bismaleimide compounds selected from methane , and the blending ratio of alkylphenol disulfide with respect to the total amount of the bismaleimide compound and alkylphenol disulfide is mass A rubber composition for vibration-proof rubber, characterized in that the ratio is 0.08 to 0.8.
[2] The rubber composition for vibration-proof rubber according to [1], wherein the total amount of the alkylphenol disulfide and the bismaleimide compound is 0.4 to 3.5 phr.
[3] The rubber composition for vibration-proof rubber according to [1] or [2], wherein the mixing ratio of natural rubber and butyl rubber is natural rubber / butyl rubber = 20/80 to 80/20 by mass ratio. .
[4] The rubber composition for vibration-proof rubber according to any one of [1] to [3], containing 0.3 to 10 phr of a thiuram vulcanization accelerator.
[5] A vibration-proof rubber obtained by crosslinking and curing the rubber composition according to any one of [1] to [4].

  The rubber composition for an anti-vibration rubber of the present invention has a good damping performance, a small compression set, and excellent heat resistance, under a high temperature environment such as an automobile torsional damper, an engine mount, and a muffler hanger. It is suitably used as a vibration-proof rubber to be used.

  As described above, the rubber composition for an anti-vibration rubber of the present invention contains a mixed rubber containing a natural rubber and a butyl rubber as a rubber component, and a combination of sulfur, an alkylphenol disulfide, and a bismaleimide compound. The blending ratio is optimized.

  Examples of the butyl rubber include butyl rubber, halogenated butyl rubber such as brominated butyl rubber and chlorinated butyl rubber, and one or more of these can be used in combination. The mixing ratio of the natural rubber and the butyl rubber is not particularly limited, but can be natural rubber / butyl rubber = 10/90 to 90/10 by mass ratio, and particularly 40/60 to 80 / 20, more preferably 50/50 to 70/30. If the content of natural rubber is too high, the content of butyl rubber will be relatively low, and the effect of improving the damping performance due to butyl rubber may not be fully demonstrated, while the content of natural rubber is too low. In some cases, the rubber strength and durability are lowered, and the rubber physical properties required as a vibration-proof rubber cannot be secured.

  In the rubber composition of the present invention, sulfur, an alkylphenol disulfide, and a bismaleimide compound are blended with the rubber component as a crosslinking agent. In this case, examples of the alkyl group of the alkylphenol disulfide include an amyl group. As the alkylphenol disulfide, for example, a commercial product such as a trade name “Vultac5” manufactured by ATOFINA can be used.

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, and one of these Or 2 or more types can be used. Although not particularly limited, N, N′-m-phenylenebismaleimide and N, N ′-(4,4′-diphenylmethane) bismaleimide are particularly preferably used among them.

  The amount of sulfur is not particularly limited, but is preferably 0.1 to 10 phr, particularly preferably 0.2 to 5 phr. If the amount of sulfur is less than 0.1 phr, the crosslink density of the vibration-proof rubber obtained may be low, and rubber properties sufficient as a vibration-proof rubber may not be obtained. On the other hand, if it exceeds 10 phr, the heat resistance may decrease and the object of the present invention may not be achieved.

  The blending amount of the alkylphenol disulfide is not particularly limited, but is preferably 0.25 to 4 phr, particularly 0.5 to 2 phr, and the blending ratio of the bismaleimide compound is not particularly limited, but is 0.15 to 5 phr. It is preferably 3 phr, particularly 0.3 to 1.5 phr. Further, although not particularly limited, it is preferable to adjust the blending amount so that the total amount of the alkylphenol disulfide and the bismaleimide compound is 0.4 to 3.5 phr, particularly 1 to 3 phr.

  Here, in the present invention, the ratio of the bismaleimide compound and the alkylphenol disulfide is such that the mixing ratio of the alkylphenol disulfide to the total amount of the bismaleimide compound and the alkylphenol disulfide is 0.08 to 0.8 in mass ratio. Adjusted to. Preferably the same ratio is 0.4-0.75 by mass ratio, more preferably 0.5-0.7. If the blending ratio is less than 0.08, the amount of alkylphenol disulfide used is too small, and the decrease in elongation at break increases. On the other hand, if it exceeds 0.8, the heat resistance and compression set decrease, and the present invention. Cannot achieve the goal.

  Here, the compounding of the alkylphenol disulfide with the mixed rubber of natural rubber and butyl rubber contributes to increase the crosslink density and improve the support performance as a vibration proof rubber, but on the other hand, the compression set becomes large, In particular, it is not preferable as a vibration-proof rubber that requires good low compression set. Therefore, in the present invention, the bismaleimide compound is used in combination with the alkylphenol disulfide, and the compression set performance is improved while maintaining good damping performance by optimizing the blending amount and blending ratio as described above. In addition, it is possible to effectively suppress performance degradation (for example, change in elongation performance during heat resistance) in a heat resistant environment.

  The rubber composition for anti-vibration rubber of the present invention may contain a known filler, for example, inorganic filler such as carbon black, silica, fine particle magnesium silicate, heavy calcium carbonate, magnesium carbonate, clay and talc. Examples thereof include organic fillers such as an agent, high styrene resin, coumarone indene resin, phenol resin, lignin, modified melamine resin, and petroleum resin. These can be used individually by 1 type or in combination of 2 or more types. In the present invention, it is possible to improve the durability and reduce the dynamic magnification of the vibration-proof rubber, and it is also possible to improve the adhesion to the metal member, so that carbon black can be particularly preferably used.

  The carbon black is preferably a large particle size carbon black such as N550, N762, and N880, and the blending amount can be 10 to 80 phr, particularly 20 to 60 phr. If the blending amount is less than 10 phr, it is not sufficient for the purpose of imparting reinforcement, while if it exceeds 80 phr, poor dispersion in rubber may occur.

  In addition to the rubber component, sulfur, alkylphenol disulfide, bismaleimide compound and the filler, a known additive can be blended in the rubber composition for vibration-proof rubber of the present invention. For example, if necessary, Vulcanization accelerator, zinc white (ZnO), oil, waxes, anti-aging agent, antioxidant, plasticizer, lubricant, tackifier, petroleum resin, UV absorber, dispersant, compatibilizer, homogenization An appropriate amount of a known additive such as an agent can be blended.

  Examples of the vulcanization accelerator include thiuram vulcanization accelerators such as TT (tetramethylthiuram disulfide), TBTD (tetrabutylthiuram disulfide), TBZTD (tetrabenzylthiuram disulfide), and CZ (N-cyclohexyl-2-benzothiazole). Sulfenamide), CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), TBSI (Nt-butyl-2-benzo Sulfenamide-based vulcanization accelerators such as thiazylsulfenimide), guanidine-based vulcanization accelerators such as DPG (diphenylguanidine), TMTD (tetramethyldisulfide), TETD (tetraethylthiuram disulfide), dialkyldithiophosphoric acid Zinc and the like are exemplified, It can be used alone or in combination of these. The compounding quantity of a vulcanization accelerator can be 0.1-10 phr, especially 0.3-5 phr. Here, although not particularly limited, among these vulcanization accelerators, it is particularly preferable to use a thiuram vulcanization accelerator alone or in combination with other accelerators, in which case the thiuram vulcanization accelerator Is preferably 0.3 to 10 phr, particularly preferably 0.5 to 2.0 phr.

  In the present invention, from the viewpoint of promoting vulcanization, a vulcanization acceleration aid such as zinc white (ZnO) or a fatty acid can be blended. Specific examples other than zinc white include naphthenic acid such as cyclohexane acid (cyclohexanecarboxylic acid), alkylcyclopentane having a side chain, hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acid such as neodecanoic acid), Saturated fatty acids such as dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid (stearic acid), unsaturated fatty acids such as methacrylic acid, oleic acid, linoleic acid, linolenic acid, resin acids such as rosin, tall oil acid, abietic acid, etc. Is exemplified. These may be used alone or in combination of two or more. In the present invention, although not particularly limited, zinc white and stearic acid can be suitably used. These compounding amounts are preferably 0.5 to 10 parts by mass, and more preferably 1 to 6 parts by mass.

  Examples of oils include process oils such as aroma oils, naphthenic oils, paraffin oils, vegetable oils such as palm oil, and synthetic oils such as alkylbenzene oils. An appropriate amount may be blended. The amount used can be 0.5-30 phr, in particular 1-20 phr.

  Examples of waxes include waxes such as known paraffin wax and microcrystalline wax, and amide compounds such as stearic acid amide, oleic acid amide, and erucic acid amide, which may be used alone or in combination of two or more. it can. In particular, in the present invention, paraffin wax and microcrystalline wax can be preferably used. By these blending, molding workability can be improved.

  Anti-aging agents include p, p′-dioctyldiphenylamine, p, p′-dicumyldiphenylamine, N, N′-diphenyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine, N -Phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-2,2,4-trimethyl-1, Amine-based antioxidants such as 2-dihydroquinoline; 2,6-di-tert-butyl-4-methylphenol, 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid stearate 2,2′-methylenebis (4-methyl-6-tert-butylphenol), tetrakis (methylene-3- (3,5-di-tert-butyl-4-hydride) Xylphenyl) propionate) methane, 4,4′-thiobis (3-methyl-6-tert-butylphenol), phenol-based antioxidants such as 2,5-di-tert-butylhydroquinone; 2-mercaptobenzimidazole, Examples include imidazole anti-aging agents such as tributylthiourea, 2-mercaptobenzimidazole zinc salt, and 2-mercaptomethylbenzimidazole zinc salt. The blending amount is not particularly limited, but can usually be 0.1 to 10 phr and 0.3 to 5 phr.

  The rubber composition for an anti-vibration rubber of the present invention is obtained by kneading the rubber component, sulfur, alkylphenol disulfide, bismaleimide compound, and the optional additive using a kneader such as a roll or an internal mixer. Further, it can be formed into a desired shape and heat vulcanized to obtain a vibration-proof rubber. In this case, at the time of the kneading, first, the components other than the vulcanizing agent (sulfur, alkylphenol disulfide, bismaleimide compound) and the vulcanization accelerator are kneaded with the rubber component (A kneading), and then the vulcanizing agent is added thereto. It is preferable to add a vulcanization accelerator and knead (B kneading), and knead in two stages. The conditions for the vulcanization operation are appropriately set according to the prescription of the rubber composition and the shape and size of the anti-vibration rubber, but are usually 100 to 200 ° C., particularly 110 to 180 ° C. It can be 0.5 to 20 minutes, especially 1 to 5 minutes.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example.

[Examples 1-8, Comparative Examples 1-3]
A rubber composition was prepared by kneading the rubber composition with the formulation shown in Table 1. The kneading operation was performed in two stages of A-kneading and B-kneading. The obtained rubber composition was heated and vulcanized at 160 ° C. for 20 minutes to obtain a vibration-proof rubber. The obtained anti-vibration rubber was measured and evaluated for hardness (Hd), tensile properties (Eb, Tb), heat resistance (ΔEb), and compression set according to the following methods. The results are shown in Table 1.

[Hardness (Hd)]
Conforms to JIS K 6253 (Type A) [Tensile elongation (Eb)]
JIS K 6251 compliant [Tensile strength (Tb)]
Conforms to JIS K 6251 [Heat resistance (ΔEb)]
The anti-vibration rubber was allowed to stand for 96 hours under heating at 100 ° C., and then the tensile elongation Eb was measured. The change rate ΔEb of the tensile elongation Eb was calculated by the following equation.
Elongation change rate ΔEb = Eb (after heat aging) / Eb (before heat aging)
[Compression set]
Conforms to JIS K 6262

Details of the above formulation are as follows.
Natural rubber: RSS # 1
Carbon black: FEF grade carbon black, "N550" manufactured by Asahi Carbon Co., Ltd.
Aroma oil: “Diana Process Oil AH-58” manufactured by Idemitsu Kosan Co., Ltd.
Wax: “Antilux 654” manufactured by Rhein Chemie
Anti-aging agent RD: 2,2,4-trimethyl-1,2-dihydroquinoline polymer, “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Anti-aging agent 6C: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine, “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
N, N'-m-phenylene bismaleimide: "Barunok PM" manufactured by Ouchi Shinsei Chemical
Alkylphenol disulfide: “Vultac5” manufactured by ATOFINA
Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazylsulfenamide (CBS), “Noxeller CZ” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator TT: tetramethylthiuram disulfide (TMTD), Ouchi Shinko Chemical Industrial Co., Ltd. "Nocceler TT"

  As shown in Table 1 above, the rubber compositions for anti-vibration rubbers of Examples 1 to 8 according to the present invention, to which N, N′-m-phenylenebismaleimide and alkylphenol disulfide were added in appropriate amounts at predetermined ratios, As a result, it was confirmed that the compression set can be effectively reduced while maintaining good damping performance, and the heat resistance is also excellent. On the other hand, Comparative Examples 1 and 2 to which only alkylphenol disulfide was added, and Comparative Example 3 in which the blending ratio of N, N′-m-phenylenebismaleimide and alkylphenol disulfide was inappropriate were heat resistance and compression set performance. It was inferior to.

Claims (5)

Rubber component containing natural rubber and butyl rubber, sulfur, alkylphenol disulfide, 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 and bis (3-ethyl-5-methyl-4- Maleimidophenyl) containing one or more bismaleimide compounds selected from methane , and the blending ratio of the alkylphenol disulfide to the total amount of the bismaleimide compound and the alkylphenol disulfide is 0.08 by mass ratio. A rubber composition for an anti-vibration rubber, characterized by being -0.8.   The rubber composition for vibration-proof rubber according to claim 1, wherein the total amount of the alkylphenol disulfide and the bismaleimide compound is 0.4 to 3.5 phr.   The rubber composition for vibration-proof rubber according to claim 1 or 2, wherein a mixing ratio of the natural rubber and the butyl rubber is natural rubber / butyl rubber = 20/80 to 80/20 in mass ratio.   The rubber composition for anti-vibration rubber according to any one of claims 1 to 3, comprising a thiuram vulcanization accelerator in an amount of 0.3 to 10 phr.   An anti-vibration rubber obtained by crosslinking and curing the rubber composition according to any one of claims 1 to 4.