JP2007314697A - Vibration-proof rubber composition and rubber vibration isolator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition suitable for a rubber vibration insulator, improving heat-resistant properties while retaining excellent vibration-proof properties and fatigue resistance, which a diene-based rubber has. <P>SOLUTION: In the vibration-proof rubber composition containing 20-80 pts.wt. carbon black on the basis of 100 pts.wt. diene-based rubber, 0.5-5.0 pts.wt. unsaturated fatty acid amide expressed by formula (1): RCONH<SB>2</SB>(R is a ≥11C unsaturated fatty acid alkyl group), and 0.1-1.5 pts.wt. sulfur are included. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an anti-vibration rubber composition, and more particularly to an anti-vibration rubber composition suitable as an anti-vibration member for an automobile engine mount and the like, and an anti-vibration rubber using the same.

  In general, an anti-vibration rubber such as an engine mount is used for automobiles and various vehicles in order to absorb vibrations of the engine and the vehicle body and improve riding comfort and reduce noise generation.

  The rubber composition used for the anti-vibration rubber has an excellent anti-vibration performance in which the value of the dynamic magnification (dynamic spring constant (Kd) / static spring constant (Ks)) is sufficiently small, and exhibits high damping properties. It is important to provide mechanical rubber properties such as elastic modulus and fatigue resistance, and diene rubbers such as natural rubber and styrene butadiene rubber have been generally used as the rubber component.

  By the way, in recent years, with the improvement in performance and output of automobiles, the use conditions of anti-vibration rubber used in engine mounts have become severe such as high temperature and high load. Improvement of the heat resistance performance is required for vibration-proof rubber compositions.

  Conventionally, a rubber composition comprising a diene rubber as a rubber component has an increased polysulfide bond between rubber molecules due to sulfur vulcanization, resulting in deterioration of heat resistance. In order to improve this heat resistance, EV in which the amount of sulfur added is reduced. Vulcanization is known, but if the amount of sulfur is reduced, the number of sulfide bonds at the cross-linked site decreases, rubber elasticity and flexibility are lost, and the durability of the rubber composition tends to deteriorate.

In addition, among the anti-vibration rubbers, anti-vibration rubbers that are used with metal parts (stabilizer bars) such as stabilizer bushes fitted between the stabilizer bar and the inner surface of the bore of the stabilizer bushes when starting, sudden braking, or turning. It has been proposed to add unsaturated fatty acid amide that can reduce the friction coefficient of the rubber surface as a countermeasure against abnormal noise due to stick-slip phenomenon due to rotational force and twisting force at the contact part. Yes. In combination with unsaturated fatty acid amides and polyethylene glycol type surfactants, these components work as a self-lubricant that gradually blooms on the rubber surface, solving the problem of abnormal noise by greatly reducing the coefficient of friction. However, there is no description regarding improvement of heat resistance. (Patent Documents 1, 2, etc.).
JP-A-6-234886 JP 2004-292678 A

  The present invention is a rubber composition suitable for a vibration-proof rubber capable of improving the heat resistance by maintaining the excellent vibration resistance and fatigue resistance of the diene rubber by improving the heat resistance of the diene rubber. Is intended to provide.

  As a result of intensive studies to solve the above-mentioned problem of improving heat resistance, the present inventor blended the above-mentioned unsaturated fatty acid amide into a rubber composition and vulcanized it in an EV to semi-EV vulcanization system. It has been found that heat resistance is greatly improved.

  That is, the anti-vibration rubber composition of the present invention is an unsaturated rubber compound represented by the following general formula (1) in an anti-vibration rubber composition containing 20 to 80 parts by weight of carbon black with respect to 100 parts by weight of the diene rubber. It contains 0.5 to 5.0 parts by weight of fatty acid amide and 0.1 to 1.5 parts by weight of sulfur.

RCONH ₂ (1)
(R is an unsaturated fatty acid alkyl group having 11 or more carbon atoms)
The vibration-proof rubber of the present invention is characterized by using the vibration-proof rubber composition as a vibration-proof member.

  According to the present invention, a diene rubber is used as a rubber component, and an anti-vibration rubber composition capable of significantly improving heat resistance while maintaining its excellent anti-vibration performance and fatigue resistance, and an anti-vibration excellent in durability. A vibration rubber can be provided.

  Hereinafter, although embodiment of this invention is described, this invention is not limited by these.

  In the vibration-proof rubber composition of the present invention, a diene rubber is used as a rubber component. Diene rubbers include diene rubbers such as natural rubber (NR) and styrene butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Is mentioned. These diene rubbers may be used alone or in combination of two or more.

  Among these, from the viewpoint of low dynamic magnification and fatigue resistance, NR alone or a blend of NR and BR or SBR is preferable. Moreover, a part of ethylene-α-olefin-based ethylene-propylene rubber (EPM, EPDM) excellent in heat resistance characteristics may be included.

  In the vibration-proof rubber composition of the present invention, 0.5 to 5.0 parts by weight of an unsaturated fatty acid amide represented by the following general formula (1) is blended and used.

RCONH ₂ (1)
R represents an unsaturated fatty acid alkyl group having 11 or more carbon atoms, preferably one having 16 to 22 carbon atoms.

  Examples of the unsaturated fatty acid amide represented by the general formula (1) include undecylenic acid amide, oleic acid amide, elaidic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, and arachidonic acid amide. In particular, oleic acid amide and erucic acid amide are preferable. As a commercial product of this unsaturated fatty acid amide, "Netron" series of Nippon Seika Co., Ltd. can be used. These unsaturated fatty acid amides may be used alone or in combination.

  The amount of the unsaturated fatty acid amide is preferably 0.5 to 5.0 parts by weight, particularly 1.0 to 4.5 parts by weight, based on 100 parts by weight of the rubber component. If the blending amount of the unsaturated fatty acid amide is less than 0.5 parts by weight, the effect of improving the heat resistance is insufficient, and if it exceeds 5.0 parts by weight, it tends to cause bloom, and the elasticity and hardness of the rubber Mechanical properties are reduced.

  Although the effect of the unsaturated fatty acid amide is not clear, it is considered that the effect of anti-aging agent is exhibited in the EV to semi-EV vulcanization system, and the effect of improving the heat resistance is particularly exhibited.

The type of carbon black used in the present invention is not particularly limited, and the nitrogen adsorption specific surface area (N ₂ SA) is 30 to 140 m ² / g, and the dibutyl phthalate (DBP) oil absorption is 60 to 140 ml / g. A general-purpose carbon black of 100 g can be used, and specific examples include GPF, FEF, HAF, ISAF, and SAF grade carbon black.

The carbon black having a relatively large particle size, particularly N ₂ SA of 90 m ² / g or less, more preferably 60 m ² / g or less, improves dispersibility in rubber and lowers the dynamic spring constant. It is preferable because the dynamic magnification can be lowered. Specifically, GPF and FEF are preferable.

  In the present invention, the compounding amount of carbon black is 20 to 80 parts by weight, preferably 20 to 60 parts by weight with respect to 100 parts by weight of the diene rubber component. If the carbon black is less than 20 parts by weight, reinforcing properties cannot be obtained, and rubber properties such as strength and elastic modulus cannot be secured. If it exceeds 80 parts by weight, the static spring constant increases, and heat resistance and sag resistance are increased. This is because it shows a worsening tendency.

  Further, as the vulcanizing agent of the rubber composition composition of the present invention, sulfur such as powdered sulfur, oil-treated sulfur and colloidal sulfur is generally used.

  The compounding amount of sulfur is 0.1 to 1.5 parts by weight, preferably 0.1 to 1.2 parts by weight with respect to 100 parts by weight of the rubber component. If sulfur is less than 0.1 part by weight, it is difficult to generate a crosslinking reaction, and if it exceeds 1.5 parts by weight, polysulfide bonds in the crosslinked part increase and heat resistance cannot be obtained.

  The type of vulcanization accelerator used in combination with the vulcanizing agent is not particularly limited, and thiurams such as tetramethylthiuram monosulfide (TS), tetramethylthiuram disulfide (TT), tetraethylthiuram disulfide (TBT), etc. , Aldehydes / amines such as hexamethylenetetramine, guanidines such as diphenylguanidine (D), thiazoles such as dibenzothiazyl disulfide (DM), sulfenamides such as cyclohexylbenzothiazylsulfenamide (CZ) However, thiuram vulcanization accelerators such as TS, TT and TBT are preferable because they improve heat resistance.

  The vulcanization accelerator is usually used in an amount of about 1 to 5 parts by weight with respect to 100 parts by weight of the rubber component, but when the sulfur is less than 1 part by weight, it is preferable to contain 2.5 parts by weight or more.

  As an anti-aging agent, for example, an anti-aging agent such as an amine-ketone type, an aromatic secondary amine type, a phenol type or a benzimidazole type can be used. Of these, diphenylamine and p-phenylenediamine are preferred because of their good heat resistance.

  Examples of the diphenylamine-based antiaging agent include 4,4 ′-(α-methylbenzyl) diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, and p- (p-toluenesulfonylamide) diphenylamine. In addition, examples of the p-phenylenediamine-based antioxidant include N, N′-diphenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine, and N, N′-di- 2-naphthyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, and the like. Among these, N- (1 , 3-Dimethylbutyl) -N′-phenyl-p-phenylenediamine (6C) is preferred.

  The anti-aging agent can be used alone or in combination of two or more thereof, and these are used in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the rubber component.

  In the anti-vibration rubber composition of the present invention, various known compounding ingredients that are compounded in ordinary anti-vibration rubber compositions, that is, silica and other reinforcing fillers, oil, zinc white, stearic acid, wax, resin In the range which does not impair the objective of this invention, an effect, a processing aid, etc. can be mix | blended suitably.

  The anti-vibration rubber composition of the present invention is prepared by kneading using a conventional method, for example, a Banbury mixer or kneader, and molded and vulcanized according to a conventional method for various automobiles such as engine mounts, strut mounts, torsional dampers, Anti-vibration rubber, anti-vibration rubber for railway vehicles, and other various industrial equipment can be manufactured. The anti-vibration rubber has both excellent anti-vibration performance and durability.

  Hereinafter, the vibration-insulating rubber composition according to the present invention will be described in detail with reference to examples.

[Preparation of anti-vibration rubber composition]
Table 1 shows the anti-vibration rubber compositions of Examples and Comparative Examples. The rubber components and compounding components used are as follows.

[component]
・ Rubber component: Natural rubber RSS # 3
・ Carbon black GPF: Tokai Carbon Co., Ltd. “Seast V”
・ Oil: Japan Energy Co., Ltd. “Process X-140”
・ Zinc flower: Mitsui Metal Mining Co., Ltd. “Zinc flower 1”
Anti-aging agent 6C: Ouchi Shinsei Chemical Co., Ltd. “NOCRACK 6C”
・ Sulfur: Hosoi Chemical Co., Ltd. “Powder sulfur 150 mesh for rubber”
・ Vulcanization accelerator TT: Ouchi Shinsei Chemical Co., Ltd. “Noxeller TT-P”
Unsaturated fatty acid amide; Oleic acid amide: Nippon Seika Co., Ltd. “Nutron P”

  Using a sealed banbury mixer with a capacity of 20 liters, an anti-vibration rubber composition was prepared according to the formulation shown in Table 1 below, and the following evaluation was performed. The results are shown in Table 1.

[Evaluation]
About each obtained vibration-proof rubber composition, hardness was evaluated as heat resistance (cut elongation and compression set after heat aging) and rubber physical properties. Each evaluation method is as follows.

[Cutting elongation retention]
According to JIS K6251, the elongation at the time of cutting of a tensile test specimen (using No. 3 dumbbell) after thermal aging was measured under two conditions of (1) 100 ° C./500 hours and (2) 100 ° C./1000 hours. The cut elongation retention rate (%) relative to the unaged elongation was determined. The higher the value, the better.

[Compression set]
According to JIS K6262, the compression set (%) of the test piece after heat aging at 100 ° C. for 500 hours was measured to evaluate sag resistance. The smaller the value, the better.

[hardness]
The spring hardness (A method, 22 ° C.) was measured according to JIS K6253.

  As shown in Table 1, the anti-vibration rubber compositions of Examples 1 and 2 blended with the unsaturated fatty acid amide according to the present invention greatly improved heat resistance compared to Comparative Example 2 of the sulfur vulcanization system, In addition, the heat resistance in the EV vulcanization system (Comparative Example 2) can be further improved and the hardness (rubber physical properties) can be maintained. On the other hand, in Comparative Example 3 in which the unsaturated fatty acid amide was 10 parts by weight, rubber softening and bloom occurred, and in Comparative Example 4 in which the amount of sulfur was 3 parts by weight, the heat resistance was not improved, and EV-based addition The effect of improving the heat resistance of unsaturated fatty acid amides in sulfur is clear.

The anti-vibration rubber composition of the present invention is particularly suitable for anti-vibration members for various industrial equipment, including various anti-vibration rubbers such as engine mounts, strut mounts, torsional dampers, muffler hangers, and body mounts for automobiles. Can be used.

Claims (2)

In the vibration-proof rubber composition containing 20 to 80 parts by weight of carbon black with respect to 100 parts by weight of the diene rubber,
An anti-vibration rubber composition comprising 0.5 to 5.0 parts by weight of an unsaturated fatty acid amide represented by the following general formula (1) and 0.1 to 1.5 parts by weight of sulfur.
RCONH ₂ (1)
(R is an unsaturated fatty acid alkyl group having 11 or more carbon atoms) An anti-vibration rubber comprising the anti-vibration rubber composition according to claim 1.