JP2011162585A - Rubber composition for vibration-damping rubber, and vibration-damping rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a vibration-damping rubber which shows both improvement of: tear properties and resistance to settling; and reduction in a dynamic to static modulus ratio, and a vibration-damping rubber. <P>SOLUTION: This rubber composition for a vibration-damping rubber includes: a rubber component as a principal component comprising a natural rubber or a blend of the natural rubber and a diene synthetic rubber; carbon black; sulfur; and a titanate coupling agent, and does not contain any inorganic filler excluding carbon black, wherein based on 100 pts.wt. of the rubber component, a content of the titanate coupling agent is 0.1-5 pts.wt., and a content of carbon black is 20-120 pts.wt. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention contains a rubber component mainly composed of natural rubber or a blend of natural rubber and a diene synthetic rubber, carbon black, sulfur and a titanate coupling agent, and contains no inorganic filler other than carbon black. The present invention relates to an anti-vibration rubber composition and an anti-vibration 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 used as the raw material of the anti-vibration rubber has various blends, and the rubber components such as natural rubber are filled with inorganic materials such as carbon black, silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate. In general, an agent, sulfur, an antioxidant, a vulcanization accelerator and the like are 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, the vibration-proof rubber containing only carbon black has a limit in reducing the dynamic magnification.

  By the way, when an inorganic filler other than the above-described carbon black is blended in the rubber composition, a coupling agent such as a silane coupling agent or a titanate coupling agent is added as described in Non-Patent Document 1 below. In general, the surface of the inorganic filler is modified by these methods.

  For example, Patent Document 1 below describes a vibration-proof rubber composition containing at least one of magnesium hydroxide and aluminum hydroxide and a coupling agent with respect to 100 parts by weight of a diene rubber. Certainly, in the vibration-proof rubber containing magnesium hydroxide and / or aluminum hydroxide, the dynamic ratio can be reduced, but the tearing property tends to deteriorate.

  Moreover, in the following patent document 2, instead of carbon black, by using a rubber composition for an anti-vibration rubber containing a hydrophobized silica and a silane coupling agent as a raw material, the dynamic ratio of the anti-vibration rubber is reduced. Is described. As described in this document, when the blending amount of silica in the rubber composition is increased, the dynamic ratio of the vulcanized rubber can be reduced. On the other hand, the processability of the rubber composition is deteriorated as the silica amount is increased. In addition, as the amount of silica increases, the anti-vibration resistance of the vibration-proof rubber deteriorates.

  As described above, when considering the tear properties and anti-sag properties of the vibration-proof rubber, it is preferable to contain only carbon black as an inorganic filler, but it is difficult to reduce the dynamic magnification in a system containing only carbon black. . Accordingly, it has been very difficult to reduce the dynamic magnification while improving the tearing property and settling resistance of the vibration-proof rubber.

  In the following Patent Documents 3 and 4, in a rubber composition containing a non-adhesive rubber such as fluororubber and carbon black, the addition of a titanate coupling agent allows the rubber to be non-adhesive in a high humidity environment. It is described to improve. However, these documents do not describe or suggest the above-mentioned problem of vibration-proof rubber.

JP 2005-248155 A JP 2006-37002 A JP-A-8-337686 JP-A-8-337689

Japan Rubber Association edited "Rubber Technology Fundamentals" published in 1983

  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 vibration-proof rubber and a vibration-proof rubber that achieve both improvement in tearing properties and sag resistance and reduction in dynamic magnification. There is to do.

  In order to solve the above-mentioned problems, the present inventors have studied to reduce the dynamic ratio of the vibration-proof rubber while using only carbon black as an inorganic filler in consideration of tearing properties and sag resistance. . As a result, it has been found that the above-mentioned problems can be solved by using carbon black and a titanate coupling agent in combination and optimizing the blending amount thereof. 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, carbon black, sulfur, and a titanate coupling agent. A rubber composition for vibration-proof rubber containing no inorganic filler other than carbon black, wherein the titanate coupling agent is contained in an amount of 0.1 to 5 parts by weight relative to 100 parts by weight of the rubber component, The carbon black content is 20 to 120 parts by weight.

  In the rubber composition for vibration-proof rubber according to the present invention, it is important to adjust the blending amount of carbon black and titanate coupling agent as described above. When the blending amount of the carbon black with respect to 100 parts by weight of the rubber component is less than 20 parts by weight, the reinforcing effect of the carbon black cannot be obtained, and the performance of the anti-vibration rubber after vulcanization becomes insufficient. As the dynamic magnification increases, exothermic properties, rubber mixing properties, processability, and the like deteriorate. Moreover, when the compounding amount of the titanate coupling agent with respect to 100 parts by weight of the rubber component is less than 0.1 parts by weight, the dynamic magnification cannot be reduced, and when it exceeds 5 parts by weight, the titanate coupling agent Due to the plasticizing effect, the static spring constant decreases, and as a result, the dynamic magnification increases.

  In the present invention, it is important that the rubber composition for vibration-proof rubber does not contain an inorganic filler other than carbon black. Here, in the present invention, “an inorganic filler other than carbon black” means silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate and the like. When the rubber composition for vibration-proof rubber contains an inorganic filler other than carbon black, there is a tendency that the tearing property or sag resistance of the vibration-proof rubber is deteriorated.

  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 anti-vibration rubber has both improved tearing property and anti-slip property and reduced dynamic magnification, the engine mount, torsional damper, body mount, cap mount, member Anti-vibration rubber for automobiles such as mounts, strut mounts and muffler mounts, anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machinery, seismic isolation rubber for buildings, seismic isolation rubber support, etc. Can be suitably used.

  In the rubber composition for vibration-proof rubber according to the present invention, a natural rubber alone or a diene rubber comprising a blend of natural rubber and a diene synthetic rubber is mainly used as a 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), and acrylonitrile butadiene rubber. (NBR) and the like. 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. In the present invention, a terminal-modified polymer obtained by modifying the terminal of natural rubber and / or diene synthetic rubber may be used.

  When natural rubber and diene synthetic rubber are blended, the blend ratio is not particularly limited, but natural rubber is contained in the rubber component in an amount of 50% by weight or more in order to maintain the fatigue resistance of natural rubber. It is preferable to contain 90% by weight or more. In addition to natural rubber and diene synthetic rubber, examples of rubber that can be used as a rubber component include olefin rubber such as ethylene propylene rubber (EPM) and halogenated butyl rubber such as brominated butyl rubber (Br-IIR). And other synthetic rubbers including polyurethane rubber, acrylic rubber, fluorine rubber, silicon rubber, and chlorosulfonated polyethylene. However, the rubber other than the diene rubber is preferably less than 40% by weight in the rubber component, and more preferably less than 20% by weight.

  The rubber composition for vibration-proof rubber of the present invention contains carbon black, sulfur and a titanate coupling agent together with the rubber component.

  Examples of carbon black include SAF, ISAF, HAF, FEF, and GPF. Considering the tearing properties and settling resistance of the vibration-proof rubber obtained, and the dynamic magnification, the carbon black content is preferably 30 to 100 parts by weight with respect to 100 parts by weight of the rubber component. More preferably, it is 60 parts by weight.

  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 3 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 will be insufficient and the rubber strength and the like will be reduced, and the tearing properties may be deteriorated. Both sag resistance may deteriorate. 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 2 parts by weight with respect to 100 parts by weight of the rubber component. Is more preferably 0.5 to 1.5 parts by weight.

  The titanate coupling agent may be added alone to the rubber composition for vibration-proof rubber, or carbon black may be used in the form of a surface treatment with a titanate coupling agent in advance. In particular, when considering the dynamic magnification, the content of the titanate coupling agent with respect to 100 parts by weight of the rubber component is preferably 0.5 to 3 parts by weight.

  The rubber composition for vibration-proof rubber of the present invention comprises a rubber component, carbon black, sulfur and a titanate coupling agent, as well as zinc oxide, stearic acid, a vulcanization accelerator, a vulcanization accelerator, a vulcanization retarder, an organic Compounding agents usually used in the rubber industry such as peroxides, anti-aging agents, softening agents such as waxes and oils, and processing aids can be appropriately mixed and used within a range not impairing the effects of the present invention.

  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. In consideration of the effect of reducing the dynamic magnification, among the vulcanization accelerators, sulfenamide vulcanization accelerators are preferable.

  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 vibration-proof rubber of the present invention comprises a rubber component, carbon black, sulfur and a titanate coupling agent, and if necessary, zinc oxide, stearic acid, a vulcanization accelerator, a vulcanization accelerator, and a vulcanization Kneading retarders, organic peroxides, antioxidants, softeners such as waxes and oils, processing aids, etc., using kneaders used in the normal rubber industry such as Banbury mixers, kneaders and rolls. Can be obtained.

  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 anti-vibration rubber has both improved tearing property and anti-slip property and reduced dynamic magnification, the engine mount, torsional damper, body mount, cap mount, member Anti-vibration rubber for automobiles such as mounts, strut mounts and muffler mounts, anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machinery, seismic isolation rubber for buildings, seismic isolation rubber support, etc. Can be suitably used.

  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 9 and Comparative Examples 1 to 10 are blended with 100 parts by weight of natural rubber in accordance with the blending formulations of Tables 1 and 2, and kneaded using a normal Banbury mixer, and the rubber composition I adjusted things. Each compounding agent described in Table 1 and Table 2 is shown below.

a) Natural rubber RSS # 3
b) Polybutadiene rubber (A) ("BR01", manufactured by JSR Corporation)
(B) ("BR1250H", manufactured by Zeon Corporation)
c) Carbon Black GPF ("Seast V", manufactured by Tokai Carbon Co., Ltd.)
d) Sulfur ("Powder sulfur for rubber 150 mesh", manufactured by Hosoi Chemical Co., Ltd.)
e) Titanate coupling agent ("Plenact KR TTS", manufactured by Ajinomoto Fine Techno Co., Ltd.)
f) Carbon coupling agent ("Sumifine 1162", manufactured by Sumitomo Chemical Co., Ltd.)
g) Silane coupling agent (“Si69”, manufactured by Degussa)
h) Aluminum hydroxide surface-treated with titanate coupling agent (titanate coupling agent + aluminum hydroxide) (“H-42STV”, Showa Denko)
i) Oil ("NC140", manufactured by JOMO j) Zinc oxide ("Zinc Hana 1", manufactured by Mitsui Mining & Smelting)
k) Stearic acid ("Lunax S-20", manufactured by Kao Corporation)
l) Peroxide ("Park Mill D40", manufactured by NOF Corporation)
m) Vulcanization accelerator
(A) Sulfenamide vulcanization accelerator N-cyclohexyl lu 2-benzothiazolyl sulfenamide ("Noxeller CZ-G (CZ)", manufactured by Ouchi Shinsei Chemical Co., Ltd.)
(B) Thiazole vulcanization accelerator di-2-benzothiazolyl disulfide (“Noxeller DM-P (DM)”)

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

(Evaluation)
<Tear properties>
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. Based on JIS K6252, the tearing property (N / mm) of the vulcanized rubber sample produced using the crescent type dumbbell was measured. The evaluation results are shown in Tables 1 and 2.

<Dynamic magnification>
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. 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)
The dynamic magnification was calculated based on the calculated dynamic spring constant and static spring constant. The evaluation results are shown in Tables 1 and 2.

<Heat resistance>
The evaluation was performed using a test piece obtained by molding into a shape and size conforming to JIS K 6262 using a predetermined mold and press-vulcanizing each rubber composition at 150 ° C. for 30 minutes. . In accordance with JIS K 6262, the sample was fixed to a jig at a temperature of 100 ° C. for 500 hours and a compression rate of 25%, then released from the jig and allowed to stand in a 23 ° C. atmosphere for 30 minutes, and then the compression set was measured. It means that the lower the value of this compression set, the better the settling resistance. The evaluation results are shown in Tables 1 and 2.

<Processability (Scorch time of unvulcanized rubber)>
In accordance with JIS K 6300-1, the blended rubber composition was heated to 125 ° C., and the time (minutes) from the start of preheating until the value rose by 5 units from the minimum value Vm was measured. The longer the scorch time, the better the processability of the rubber composition. The evaluation results are shown in Tables 1 and 2.

  From the results shown in Table 1, in the anti-vibration rubbers obtained using the rubber compositions for anti-vibration rubbers of Examples 1 to 9 as the raw material, both improvement in tearing properties and anti-sag properties and reduction in dynamic magnification were achieved. I understand that. On the other hand, from the results in Table 2, it can be seen that in Comparative Example 1, the rubber composition does not contain a titanate coupling agent, and therefore the dynamic ratio of the vibration-proof rubber increases. Also in Comparative Example 2, it can be seen that the dynamic ratio of the anti-vibration rubber increases because the content of the titanate coupling agent in the rubber composition is too large. Moreover, in Comparative Example 3 (carbon coupling agent) and Comparative Example 4 (silane coupling agent) using a coupling agent other than the titanate coupling agent, it is understood that workability and sag resistance are deteriorated. . Moreover, it turns out that the tear property deteriorates in Comparative Example 5 using an inorganic filler (aluminum hydroxide) other than carbon black. In Comparative Example 6 where no sulfur is used, it can be seen that the dynamic magnification increases and the workability deteriorates.

Claims (2)

  For anti-vibration rubber containing natural rubber or a rubber component mainly composed of a blend of natural rubber and diene synthetic rubber, carbon black, sulfur and titanate coupling agents, and no inorganic filler other than carbon black It is a rubber composition, wherein the titanate coupling agent content is 0.1 to 5 parts by weight and the carbon black content is 20 to 120 parts by weight with respect to 100 parts by weight of the rubber component. 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.