JP2010209285A - Rubber composition for vibration-damping rubber and vibration-damping rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for vibration-dumping rubber, which shows both improvement of tensile properties and durability and reduction in a dynamic to static modulus ratio; and to provide a vibration-dumping rubber. <P>SOLUTION: The rubber composition for vibration-dumping rubber comprises: a rubber constituent comprising a natural rubber, or a blend of a natural rubber and a diene-based synthetic rubber; aluminum hydroxide; and a coupling agent, wherein the content of aluminum hydroxide based on 100 pts.wt. of the rubber constituent is not less than 3 pts.wt. and less than 20 pts.wt., and the content of the coupling agent is not less than 0.1 pts.wt. and less than 5 pts.wt. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an anti-vibration rubber composition and an anti-vibration rubber containing a natural rubber or a rubber component mainly composed of a blend of natural rubber and a diene synthetic rubber, an aluminum hydroxide, and a coupling agent. Related to rubber.

  In general, an anti-vibration rubber is used for an automobile to absorb vibrations of an engine and a vehicle body to improve riding comfort and prevent noise. The rubber composition for anti-vibration rubber, which is the raw material of this anti-vibration rubber, has a variety of formulations. Carbon rubber, sulfur, zinc white, anti-aging agent, vulcanization accelerator, etc. are added to rubber components such as natural rubber. Is generally used. In general, carbon black having a large particle size such as FEF or FT carbon is often used. By using such a large particle size carbon black, the dynamic magnification of the vibration-proof rubber (dynamic spring) is obtained. Many examples have been reported so far to reduce the (constant / static spring constant).

  However, when the content of the large particle size carbon black in the rubber composition is increased in order to further increase the elastic modulus (static spring constant) of the anti-vibration rubber, the dynamic ratio of the anti-vibration rubber tends to increase greatly. . For this reason, when a vibration-proof rubber made from such a rubber composition is used in, for example, an automobile, there is a problem that the ride comfort deteriorates.

  In the following Patent Document 1, in order to solve the above-described problem, the dynamic ratio of the vibration-proof rubber is reduced by using a rubber composition for vibration-proof rubber containing hydrophobized silica instead of carbon black as a raw material. It is described. As described in this patent document, when compared with carbon black, it is possible to reduce the dynamic magnification of silica-containing vibration-proof rubber. However, in order to further increase the static spring constant of the anti-vibration rubber described in this patent document, when the silica content in the rubber composition is increased, the silica aggregates in the rubber composition, so that the Mooney viscosity is increased. As a result, the processability of the rubber composition deteriorated.

  In Patent Document 2 below, for the purpose of improving the flame retardancy of the vibration-proof rubber, magnesium hydroxide having an average particle size of 15 μm or less and water having an average particle size of 15 μm or less with respect to 100 parts by weight of the diene rubber. A rubber composition for flame retardant and vibration-proof rubber containing 20 to 300 parts by weight of at least one of aluminum oxide is described. However, the anti-vibration rubber obtained by vulcanizing and molding such a rubber composition for anti-vibration anti-vibration rubber is excellent in flame retardancy, but the rubber properties such as tensile properties are deteriorated and used repeatedly. In some cases, the durability deteriorated.

JP 2006-37002 A JP 2005-248155 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber composition for a vibration-proof rubber and a vibration-proof rubber that achieve both improved tensile physical properties and durability and reduced dynamic magnification. There is.

  In order to solve the above-mentioned problems, the inventors of the present invention are concerned with the relationship between the tensile properties and durability of the vibration-proof rubber and the dynamic magnification, and the contents of aluminum oxide and coupling agent in the rubber composition for vibration-proof rubber. A number of experiments were conducted while varying. As a result, it has been found that when the contents of the aluminum hydroxide and the coupling agent are within a specific range, it is possible to achieve both improvement in tensile properties and durability of the vibration-proof rubber and reduction in dynamic magnification. The present invention has been made as a result of the above-described studies, and achieves the above-described object with the following configuration.

  That is, the rubber composition for vibration-proof rubber according to the present invention contains natural rubber or a rubber component mainly composed of a blend of natural rubber and a diene synthetic rubber, aluminum hydroxide, and a coupling agent. In the rubber composition for vibration-proof rubber, the content of the aluminum hydroxide with respect to 100 parts by weight of the rubber component is 3 parts by weight or more and less than 20 parts by weight, and the content of the coupling agent is 0.1 parts by weight. Part or more and less than 5 parts by weight.

  In the rubber composition for vibration-proof rubber according to the present invention, it is essential that the content of aluminum hydroxide and the content of the coupling agent are within the above ranges with respect to 100 parts by weight of the rubber component. Thereby, the improvement of the tensile physical property and durability of the vibration-proof rubber obtained and the reduction of dynamic magnification can be made compatible. In addition, when the content of aluminum hydroxide relative to 100 parts by weight of the rubber component is within the above range, aggregation of aluminum hydroxide in the rubber composition can be almost suppressed, so that the Mooney viscosity of the rubber composition is reduced. As a result, good processability of the rubber composition is ensured.

  The anti-vibration rubber according to the present invention is obtained by vulcanization and molding using the rubber composition for anti-vibration rubber described above. As described above, since the vibration-proof rubber has both improved tensile properties and durability, and reduced dynamic magnification, engine mount, torsional damper, body mount, cap mount, member mount In addition to anti-vibration rubber for automobiles such as strut mounts and muffler mounts, anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machinery, seismic isolation rubber for construction, seismic isolation rubber support, etc. It can be used suitably.

  In the rubber composition for vibration-proof rubber according to the present invention, natural rubber alone or a blend of natural rubber and diene synthetic rubber is used as the rubber component. When natural rubber and diene synthetic rubber are blended, the diene synthetic rubber includes polyisoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), butyl rubber (IIR), acrylonitrile butadiene rubber ( NBR). The polymerization method and microstructure of the diene-based synthetic rubber are not limited, and one or more of these can be used by blending with natural rubber.

  The blend ratio of the natural rubber and the diene-based synthetic rubber is not particularly limited, but in order to maintain the fatigue resistance performance of the natural rubber, the natural rubber is preferably contained in the rubber component in an amount of 50% by weight or more. It is more preferable to contain 90% by weight or more.

  In the rubber composition for vibration-proof rubber according to the present invention, the content of aluminum hydroxide with respect to 100 parts by weight of the rubber component is 3 parts by weight or more and less than 20 parts by weight. When the content of aluminum hydroxide with respect to 100 parts by weight of the rubber component is less than 3 parts by weight, the dynamic ratio of the vibration-proof rubber is increased, and when it exceeds 20 parts by weight, the flame retardancy of the vibration-proof rubber is improved. Its tensile properties and durability deteriorate. In order to achieve particularly good balance between improvement in tensile properties and durability of the vibration-proof rubber and reduction in dynamic magnification, the content of aluminum hydroxide with respect to 100 parts by weight of the rubber component is 5 parts by weight or more and 19 parts by weight. It is preferable to make it less than.

  The coupling agent is not particularly limited as long as it is used in the normal rubber industry. For example, a vinyl silane coupling agent, a titanate coupling agent, an epoxy silane coupling agent, or an acrylic silane coupling agent. A coupling agent etc. are mentioned. Moreover, in this invention, in order to improve the dispersibility of the aluminum hydroxide in a rubber composition, you may surface-treat aluminum hydroxide with a coupling agent.

  In the rubber composition for vibration-proof rubber according to the present invention, the content of the coupling agent with respect to 100 parts by weight of the rubber component is 0.1 parts by weight or more and less than 5 parts by weight. When the content of the coupling agent with respect to 100 parts by weight of the rubber component is outside the above range, the tensile properties and durability of the vibration-proof rubber are deteriorated. In order to improve the tensile properties and durability while reducing the dynamic ratio of the vibration-proof rubber, it is preferably 0.2 parts by weight or more and less than 1 part by weight, and 0.3 parts by weight or more and 0.8 parts by weight. It is particularly preferred that the amount be less than parts.

  The rubber composition for vibration-proof rubber of the present invention comprises sulfur, carbon black, silica, zinc oxide, stearic acid, a vulcanization accelerator, a vulcanization accelerator, a vulcanization accelerator together with the rubber component, aluminum hydroxide and a coupling agent. Additives usually used in the rubber industry, such as sulfur retarders, organic peroxides, anti-aging agents, softeners such as waxes and oils, processing aids, etc. are used as long as the effects of the present invention are not impaired. be able to.

  Sulfur should just be normal sulfur for rubber | gum, For example, powder sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur etc. can be used. The sulfur content in the rubber composition for vibration-proof rubber according to the present invention is preferably 0.2 to 1.5 parts by weight with respect to 100 parts by weight of the rubber component. If the sulfur content is less than 0.2 parts by weight, the crosslinking density of the vulcanized rubber may be insufficient and the rubber strength and the like may be reduced. If the sulfur content exceeds 1.5 parts by weight, the heat resistance and the settling resistance may be reduced. Both can get worse. In order to ensure good rubber strength of the vulcanized rubber and to further improve heat resistance and sag resistance, the sulfur content is 0.3 to 1.3 parts by weight with respect to 100 parts by weight of the rubber component. More preferably, it is more preferably 0.5 to 1.2 parts by weight.

  Examples of carbon black include SAF, ISAF, HAF, FEF, and GPF. Carbon black can be used within a range in which rubber properties such as hardness, reinforcement and low heat build-up of the rubber after vulcanization can be adjusted. In the present invention, the carbon black content is preferably in the range of 20 to 120 parts by weight, more preferably 30 to 100 parts by weight, and particularly preferably 30 to 60 parts by weight with respect to 100 parts by weight of the rubber component. Parts by weight. If this blending amount is less than 20 parts by weight, the reinforcing effect of carbon black may not be sufficiently obtained. If it exceeds 120 parts by weight, exothermic property, rubber mixing property, workability during processing, etc. may deteriorate. is there.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators may be used alone or in admixture as appropriate.

  As an anti-aging agent, an aromatic amine-based anti-aging agent, an amine-ketone-based anti-aging agent, a monophenol-based anti-aging agent, a bisphenol-based anti-aging agent, a polyphenol-based anti-aging agent, dithiocarbamic acid, which are usually used for rubber Anti-aging agents such as a salt-based anti-aging agent and a thiourea-based anti-aging agent may be used alone or in an appropriate mixture.

  The rubber composition for an anti-vibration rubber of the present invention comprises a rubber component, aluminum hydroxide, a coupling agent, and sulfur, carbon black, silica, zinc oxide, stearic acid, a vulcanization accelerator, and a vulcanization acceleration aid as necessary. Agent, vulcanization retarder, organic peroxide, anti-aging agent, softener such as wax and oil, processing aid, etc., using kneading machines used in normal rubber industry such as Banbury mixer, kneader, roll And kneading.

  In addition, the blending method of each of the above components is not particularly limited, and a blending component other than a vulcanizing component such as sulfur and a vulcanization accelerator is previously kneaded to obtain a master batch, and the remaining components are added and further kneaded. Any of a method of adding and kneading the components in an arbitrary order, a method of adding all of the components simultaneously and kneading may be used.

  By using the rubber composition for vibration-proof rubber, vulcanization and molding, the vibration-proof rubber according to the present invention can be produced. As described above, since the vibration-proof rubber has both improved tensile properties and durability, and reduced dynamic magnification, engine mount, torsional damper, body mount, cap mount, member mount In addition to anti-vibration rubber for automobiles such as strut mounts and muffler mounts, anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machinery, seismic isolation rubber for construction, seismic isolation rubber support, etc. It can be used suitably.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described.

(Preparation of rubber composition)
The rubber compositions of Examples 1 to 5 and Comparative Examples 1 to 6 were blended with 100 parts by weight of natural rubber in accordance with the blending formulation of Table 1, and kneaded using a normal Banbury mixer to adjust the rubber composition did. Each compounding agent described in Table 1 is shown below.

a) Natural rubber RSS # 3
b) Aluminum hydroxide product with an average particle size of 1 μm (“Hijilite H-42M” manufactured by Showa Denko KK), product with an average particle size of 8 μm (“Heidilite H-32” manufactured by Showa Denko KK)
c) Coupling agent Vinylsilane coupling agent ("KBM-1003", manufactured by Shin-Etsu Chemical Co., Ltd.), titanate coupling agent ("KR TTS", manufactured by Ajinomoto Fine Techno)
d) Zinc oxide ("Zinc Hua 1", manufactured by Mitsui Mining & Smelting Co., Ltd.)
e) Stearic acid ("Lunac S-20", manufactured by Kao Corporation)
f) Carbon Black GPF ("Seast V", manufactured by Tokai Carbon Co., Ltd.)
g) Sulfur ("Sulfur powder for rubber 150 mesh", manufactured by Hosoi Chemical Co., Ltd.)
h) Vulcanization accelerator N-Cyclohexyl 2-benzothiazolylsulfenamide ("Noxeller CZ-G (CZ)", manufactured by Ouchi Shinsei Chemical Co., Ltd.)

  About each rubber composition, each vulcanized rubber was produced and the characteristic evaluation was performed.

(Evaluation)
The evaluation was performed on a rubber obtained by using a predetermined mold and heating and vulcanizing each rubber composition at 150 ° C. for 25 minutes.

<Tensile property / Tear property>
Based on JIS K6251, the tensile physical property (MPa) of the vulcanized rubber sample produced using the JIS3 dumbbell was measured. Moreover, based on JIS K6252, the tearing physical property (N / mm) of the sample produced using the JIS3 dumbbell was measured. If the measured tensile property value is 17 (MPa) or more and the tear property value is 35 (N / mm) or more, it is less than the above value in either the tensile property value or the tear property value. X. The evaluation results are shown in Table 1.

<Dynamic magnification>
The dynamic magnification (dynamic spring constant / static spring constant) was calculated by measuring the dynamic spring constant and the static spring constant.

(1) Dynamic spring constant “Dynamic Servo” manufactured by Kinomiya Seisakusho Co., Ltd. was used as a measuring instrument, and the initial strain was 10%, the frequency was 100 Hz, and the amplitude was ± 0.05 mm.

(2) Static spring constant "Tensilon" manufactured by Orientec Co., Ltd. is used as a measuring instrument, and compression between 0 and 5 mm is performed twice on a vulcanized rubber test piece of 50 mmφ x 25 mm at a crosshead speed of 10 mm / min. Repeatedly, a second load-deflection diagram was drawn and calculated based on the following formula (1).
(Static spring constant (N / mm)) = (w2-w1) / (δ2-δ1) (1)
(In the above formula (1), w1; load (N) when the deflection amount δ1 is 1.3 mm, w2; load (N) when the deflection amount δ2 is 3.8 mm)

  Based on the calculated dynamic spring constant and the static spring constant, the dynamic magnification was calculated. The evaluation results are shown in Table 1.

<Durability>
Durability was evaluated by a dumbbell fatigue test. Based on JIS K 6260, the dumbbell fatigue test of the vulcanized rubber sample produced using the JIS No. 3 dumbbell was performed. In the evaluation, the case where the sample broke after a repeated fatigue test of 100,000 times or more was evaluated as x, and the case where the sample was broken in a repeated fatigue test of less than 100,000 times was evaluated as x. The evaluation results are shown in Table 1.

  As shown in Table 1, the anti-vibration rubber obtained by vulcanizing and molding the anti-vibration rubber compositions according to Examples 1 to 5 has improved tensile properties, tearing properties and durability, and reduced dynamic magnification. It can be seen that both are compatible. In particular, in Example 2 and Example 4, although the content of the coupling agent with respect to 100 parts by weight of the rubber component was less than 1 part by weight, improvement in tensile properties, tearing properties and durability, and dynamic magnification It can be seen that the reduction and the balance are balanced.

  On the other hand, the anti-vibration rubber obtained in Comparative Example 1 and Comparative Example 3 does not contain aluminum hydroxide or the content thereof is small, so the dynamic ratio is high, and the anti-vibration rubber obtained in Comparative Example 2 is Since it does not contain a coupling agent, the tensile and tear properties deteriorated. Moreover, since the anti-vibration rubbers obtained in Comparative Examples 4 to 6 all have a high aluminum hydroxide content, all of the tensile properties, tear properties and durability deteriorated.

Claims (2)

In a rubber composition for vibration-proof rubber, comprising natural rubber, or a rubber component mainly composed of a blend of natural rubber and a diene synthetic rubber, aluminum hydroxide, and a coupling agent,
The content of the aluminum hydroxide with respect to 100 parts by weight of the rubber component is 3 parts by weight or more and less than 20 parts by weight, and the content of the coupling agent is 0.1 parts by weight or more and less than 5 parts by weight. A rubber composition for an anti-vibration rubber.   An anti-vibration rubber obtained by vulcanization and molding using the rubber composition for anti-vibration rubber according to claim 1.