JP2009019076A - Vibration-proof rubber composition and vibration-proof rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration-proof rubber composition and a vibration-proof rubber that can combine both a big loss and a low dynamic-to-static modulus ratio without reducing rubber properties. <P>SOLUTION: The vibration-proof rubber composition comprises a rubber component formed by combining a diene-based rubber with an epoxidized natural rubber and has a content of the epoxidized natural rubber in the rubber component of ≥10 mass%. The vibration-proof rubber comprises the vulcanized product of the vibration-proof rubber composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an anti-vibration rubber composition and an anti-vibration rubber using the same.

  Conventionally, in order to prevent vibration and noise, anti-vibration rubber has been used in various vehicles such as automobiles and railways, various machines such as industrial machines and household appliances. The performance required for the vibration-proof rubber includes a low dynamic magnification and a large hysteresis loss (hereinafter simply referred to as “loss”). That is, it is ideal that a loss is large in a low frequency and high strain region, and a dynamic magnification (ratio of dynamic elastic modulus and static elastic modulus) is low in a high frequency and low strain region.

  In order to increase the loss and reduce the dynamic ratio, a method has been proposed in which a part of natural rubber, which is a rubber component of a vibration-proof rubber, is replaced with a functional group vulcanizable rubber (halobutyl) (for example, patent document). 1). However, this method has a problem that the physical properties and durability of the rubber are lowered.

  In order to increase the loss, methods such as adding oil or resin to the anti-vibration rubber composition or using carbon with high reinforcing properties are generally adopted. There was a problem that would be high.

  A rubber composition for anti-vibration rubber is required to have a large loss and a low dynamic magnification. However, there is a trade-off between large loss and low dynamic magnification. It is very difficult to do.

JP 2001-302846 A

  An object of the present invention is to provide an anti-vibration rubber composition capable of achieving both a large loss and a low dynamic magnification without deteriorating rubber physical properties, and an anti-vibration rubber using the same. .

  As a result of intensive studies to achieve the above object, the present inventors have achieved the above object with a rubber composition comprising a rubber component in which a diene rubber and an epoxidized natural rubber are combined in a specific ratio. Found to get.

That is, the present invention
(1) An anti-vibration rubber composition comprising a rubber component comprising a combination of a diene rubber and an epoxidized natural rubber, wherein the content of the epoxidized natural rubber in the rubber component is 10% by mass or more,
(2) The anti-vibration rubber composition according to (1), wherein the content of the epoxidized natural rubber in the rubber component is 30 to 70% by mass,
(3) The anti-vibration rubber composition according to (1) or (2), wherein the diene rubber is natural rubber,
(4) The anti-vibration rubber composition according to any one of (1) to (3), wherein the epoxidized natural rubber blended as the rubber component has an epoxidation rate of 10 to 60 mol%.
(5) Carbon black having an iodine adsorption amount of 10 to 70 g / kg and a DBP oil absorption amount of 30 to 180 ml / 100 g as a filler, and / or silica having a BET specific surface area of 70 to 230 m ² / g A vibration-insulating rubber composition according to any one of (1) to (4),
(6) Anti-vibration rubber comprising a vulcanized product of the anti-vibration rubber composition according to any one of (1) to (5),
Is to provide.

  According to the present invention, it is possible to provide an anti-vibration rubber composition capable of achieving both a large loss and a low dynamic magnification without deteriorating rubber physical properties and an anti-vibration rubber using the same.

[Vibration-proof rubber composition]
The anti-vibration rubber composition of the present invention includes a rubber component composed of a combination of a diene rubber and an epoxidized natural rubber. The content of the epoxidized natural rubber in the rubber component is required to be 10% by mass or more, and preferably 30 to 70% by mass. If the epoxidized natural rubber is less than 10% by mass, the large loss characteristic of the epoxidized natural rubber cannot be fully utilized. In particular, since the content of the epoxidized natural rubber is 30 to 70% by mass, both large loss and low dynamic ratio can be achieved without hindering excellent rubber properties such as destructive properties of diene rubber. Can be realized more efficiently.

  If the said rubber component becomes a main component, the rubber composition of this invention may contain other rubber components other than the said rubber component. Moreover, various additives, such as a filler, a vulcanizing agent, and a silane coupling agent, can also be included. Hereinafter, the rubber component and the additive will be described.

(Diene rubber)
The diene rubber has excellent rubber characteristics such as fracture characteristics and hardness, and contributes to obtaining a low dynamic magnification.

  The diene rubber used as the first material of the rubber component is not particularly limited, and any of natural rubber and diene synthetic rubber can be used. Examples of the diene-based synthetic rubber include styrene-butadiene copolymer (SBR), polybutadiene (BR), polyisoprene (IR), and styrene-isoprene copolymer (SIR).

  In this invention, the said diene rubber may be used individually by 1 type, and may be used in combination of 2 or more type. Natural rubber is particularly preferred from the viewpoint of obtaining good rubber properties and low dynamic magnification.

(Epoxidized natural rubber)
The epoxidized natural rubber is contained in a predetermined amount in the vibration-proof rubber composition, thereby contributing to the improvement of the loss.

  Epoxidized natural rubber is not compatible with diene rubber (for example, natural rubber). Therefore, when the diene rubber and the epoxidized natural rubber are combined, it is considered that the diene rubber and the epoxidized natural rubber in the vibration-proof rubber composition are separated from each other (sea island state). By being in such a separated state, it is considered that the low dynamic magnification and good rubber physical properties possessed by the diene rubber are exhibited, and at the same time the high loss characteristics possessed by the epoxidized natural rubber are also efficiently exhibited. .

  The epoxidation rate of the epoxidized natural rubber to be compounded is preferably 10 to 60 mol% in consideration of low temperature characteristics while exhibiting the large loss characteristics of the epoxidized natural rubber more efficiently. More preferably, it is 50 mol%. The epoxidized natural rubber is considered to exist in a state of being separated from the diene rubber in the vibration-proof rubber composition. That is, by setting the epoxidation rate at the time of blending within the above range, the epoxidation rate in the domain made of epoxidized natural rubber can be made substantially equal to the above range. For this reason, it is possible to efficiently form a state where epoxy groups are densely packed, and a large loss is considered to be obtained.

  Epoxidized natural rubber having an epoxidation rate in the above range can be easily obtained by a conventionally known production method. Moreover, in this invention, a commercial item can be used.

  Here, the “epoxidation rate” refers to the ratio of the portion in which the double bond portion of the main chain is cyclized with oxygen with respect to the ratio of all the double bond portions of the resin before epoxidation. The epoxidation rate can be determined from, for example, NMR measurement data. That is, the area intensity A of the methine proton derived from natural rubber near 5.10 ppm and the area intensity B of the proton derived from epoxy group near 2.7 ppm were determined, and the formula “epoxidation rate (%) = B / (A + B) × 100 Can be obtained.

(Carbon black and / or silica)
In the vibration-proof rubber composition of the present invention, carbon black and / or silica may be contained as a filler. As carbon black, those having an iodine adsorption amount of 10 to 70 g / kg and a DBP oil absorption amount of 30 to 180 ml / 100 g are preferably used. Examples of such carbon black include SRF grade, GPF grade, and FEF grade. The nitrogen adsorption specific surface area (N ₂ SA) is about 10 to 75 m ² / g.

  When carbon black having a particle size smaller than that of the above carbon black is used, the dynamic ratio of the obtained vibration-proof rubber may be increased, while carbon black having a particle size larger than that of the carbon black is used. And there exists a possibility that the reinforcement property of the vibration-proof rubber obtained may fall. By using carbon black having the above properties, it is possible to obtain a rubber composition that provides a vibration-proof rubber having a balance between reinforcement and low dynamic magnification.

A more preferable range of the iodine adsorption amount is 12 to 60 g / kg, and a more preferable range of the DBP oil absorption amount is 60 to 180 ml / 100 g.
In addition, said iodine adsorption amount is a value measured based on JIS K 6217-1: 2001, and DBP oil absorption is a value measured based on JIS K 6217-4: 2001. Further, the nitrogen adsorption specific surface area (N ₂ SA) is a value measured in accordance with ASTM D3037.

  In the present invention, as carbon black, one kind may be used alone, or two or more kinds may be used in combination.

On the other hand, silica having a BET specific surface area in the range of 70 to 230 m ² / g is preferably used. If this BET specific surface area is 70 m ² / g or more, a good reinforcing effect can be obtained, and deterioration of rubber physical properties and durability can be suppressed. Further, if the BET specific surface area is 230 m ² / g or less, it is possible to suppress poor dispersion of silica in the rubber composition, and as a result, it is possible to suppress deterioration in durability and deterioration of dynamic magnification due to poor dispersion. it can. A more preferable range of this BET specific surface area is 80 to ²⁰⁰ m ² / g.

  The BET specific surface area is measured by the Brunauer, Emmett and Teller (“BET”) method described in “Journal of American Chemical Society (J. Am. Chem. Soc.)”, Volume 60, page 309. Is the value to be

As the said silica, the various commercially available thing whose BET specific surface area is 70-230 m < ² > / g can be 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 which is anhydrous silicic acid has the above-mentioned effects. In particular, silica produced by a wet method such as silica gel is preferred. As the silica as described above, one kind may be used alone, or two or more kinds may be used in combination.

  In the present invention, as the filler, only the above-described carbon black may be used, only silica may be used, or carbon black and silica may be used in combination.

  In the vibration-proof rubber composition of the present invention, the content of carbon black and / or silica in the filler is about 10 to 80 parts by weight, preferably 15 to 60 parts by weight with respect to 100 parts by weight of the rubber component described above. It is. If the content of the filler is 10 parts by mass or more, the fracture characteristics of the vibration-proof rubber obtained will be good, and the dynamic magnification will be low. Can be suppressed. Moreover, when carbon black and silica are compared with the same dynamic magnification, the reinforcing property of silica is higher.

  In the present invention, when silica is used as the filler, it is preferable to contain a silane coupling agent in the rubber composition in order to improve the dispersibility of the silica in the rubber composition.

(Vulcanizing agent)
In the vibration-proof rubber composition of the present invention, it is preferable to contain sulfur as a vulcanizing agent at a ratio of 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component according to the present invention. If the sulfur content is 0.1 parts by mass or more, the vulcanized rubber can maintain good fracture characteristics. On the other hand, if it is 3.0 parts by mass or less, desired heat resistance and compression permanent Distortion can be obtained.

(Silane coupling agent)
Examples of the silane coupling agent contained in the rubber composition of the present invention together with the silica include vinyltriethoxysilane, vinyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltri Methoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ -Aminopropyltrie Xysilane, and γ-trimethoxysilylpropyldimethylthiocarbamyl tetrasulfide, γ-trimethoxysilylpropylbenzothiazyl tetrasulfide, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (triethoxysilyl) And tetrasulfides such as propyl) tetrasulfide.

  This silane coupling agent may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, 1-10 mass% of the silica to be used is preferable, and 5-10 mass% is more preferable. If the blending amount of the silane coupling agent is 1% by mass or more, the blending effect will be exhibited, and the dynamic ratio of the resulting vibration-proof rubber will be good, and even if blending more than 10% by mass, the amount will be However, the improvement of the effect is not recognized so much and it is disadvantageous economically.

(Other additives)
In addition to the rubber component according to the present invention, sulfur as a vulcanizing agent, carbon black and / or silica as a filler, and a silane coupling agent, various additives, for example, Vulcanization accelerators, anti-aging agents, softeners, plasticizers, processing aids, and the like can be included.

  Examples of the vulcanization accelerator that can be used in the present invention include those effective for diene rubbers and chloroprene rubbers, for example, one or a mixture of two or more selected from guanidine, thiazole, thiuram, and the like. be able to. The amount of the vulcanization accelerator used is about 0.1 to 3.0 parts by mass, preferably 0.5 to 2.0 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the anti-aging agent include 4,4′-bis (α, α-dimethylbenzyl) diphenylamine, octylated diphenylamine, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (RD), N— 1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (6C) or the like can be used. The usage-amount of this anti-aging agent is about 0.5-10 mass parts with respect to 100 mass parts of rubber components, Preferably it is 1-5 mass parts.

  Examples of the softener that can be used in the present invention include petroleum-based softeners such as process oil, paraffin, liquid paraffin, petroleum jelly and petroleum asphalt, and general softeners such as rapeseed oil, linseed oil, castor oil, and palm oil. Can be mentioned. As the plasticizer, general ester plasticizers such as dioctyl phthalate and dioctyl adipate, ether / thioether plasticizers, ether / ester plasticizers, and the like can be used.

(Preparation of anti-vibration rubber composition)
Although there is no restriction | limiting in particular as a preparation method of the vibration-proof rubber composition of this invention, For example, it can prepare by the method shown below. That is, a rubber component comprising a combination of a diene rubber and an epoxidized natural rubber, sulfur as a vulcanizing agent, carbon black and / or silica as a filler, and, if necessary, a silane coupling agent And the above-mentioned other additives are kneaded at a temperature lower than the vulcanization temperature by a kneading machine such as a Banbury mixer, a kneader, a roll, or an internal mixer to prepare the vibration-proof rubber composition of the present invention. be able to.

[Anti-vibration rubber]
The anti-vibration rubber of the present invention is composed of a vulcanized product of the above-described anti-vibration rubber composition of the present invention, and after the anti-vibration rubber composition of the present invention is molded into a predetermined shape, usually 140 to 180 ° C. It can be produced by vulcanization at a temperature of about 150 ° C to 170 ° C. The anti-vibration rubber of the present invention can achieve both a large loss and a low dynamic ratio while maintaining rubber properties equivalent to those of conventional anti-vibration rubbers, and can be used for anti-vibration members in various fields.

  Although there is no restriction | limiting in particular in the said vibration-proof member, For example, it is suitable for the vibration-proof of various apparatuses, such as various vehicles, such as a motor vehicle and a railway, an industrial machine, and household appliances.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 7 and Comparative Examples 1 and 2)
The components shown in Table 1 below were kneaded using a Banbury mixer to prepare nine types of vibration-proof rubber compositions.

  In addition, about the anti-vibration rubber composition obtained in each case, the said rubber composition was vulcanized at 160 degreeC for 10 minutes, and each evaluation was performed by the following test method. The results are shown in Table 1 below.

(1) Rubber physical properties / breaking strength Tb: measured according to JIS K 6251.
-Elongation at break Eb: Measured according to JIS K 6251.
Rubber hardness Hs: measured according to JIS K 6253 (type A).
As an evaluation index of rubber physical properties in Table 1, “◯” means that Tb is 20 MPa or more, and “x” means that Tb is less than 20 MPa.

(2) Durability Elongation fatigue resistance was evaluated by repeatedly inputting 0 to 200% strain into a dumbbell-shaped test piece and testing the number of times until breakage.
In addition, as a durability evaluation index in Table 1, “◯” means that durability evaluation has no practical problem, and “×” means that durability evaluation may cause a practical problem. .

(3) Dynamic characteristics / static spring constant Ks: Measured according to JIS K 6385 (compression method).
Loss coefficient (loss) tan δ: measured in accordance with JIS K 6385 (15 Hz).
-Dynamic spring constant Kd: Measured according to JIS K 6385 (100 Hz).
- dynamic factor Kd ₁₀₀ / Ks: was measured in accordance with JIS K 6385.
As an index for evaluation of dynamic characteristics (high loss and low dynamic ratio) in Table 1, “◯” means that tan δ is 0.1 or more and the dynamic magnification is not a problem in practice, and “×” means tan δ. Means less than 0.1 and the loss is small.

Moreover, when all of rubber physical properties, durability and dynamic characteristics were “◯”, the overall evaluation was “◯” because it was practically excellent as a vibration-proof rubber. On the other hand, when the evaluation of at least one of the physical properties, durability, and dynamic characteristics of the rubber is “x”, the overall evaluation is “x” because it may cause a practical problem as an anti-vibration rubber.

The details of each component in Table 1 are as follows.
・ Natural rubber: “RSS # 1”
-Epoxidized natural rubber (25% mol): “Epoxyprene 25” manufactured by Muang Mai Guthrie Public Company Limited
Epoxidized natural rubber (50% mol): “Epoxyprene 50” manufactured by Muang Mai Guthrie Public Company Limited
Chlorinated butyl rubber: “Chlorobutyl 1066” manufactured by ExxonMobil
N550 (carbon black): FEF; iodine adsorption amount = 43 g / kg, DBP oil absorption amount = 121 ml / 100 g, N ₂ SA (nitrogen adsorption specific surface area) = 42 m ² / g, “Asahi #” manufactured by Asahi Carbon Co., Ltd. 65 "
・ Silica: “NIPSIL VN3” manufactured by Tosoh Silica Co., Ltd.
Silane coupling agent: “Si69” manufactured by DEGUSSA
CBS: Vulcanization accelerator (N-cyclohexyl-2-benzothiazylsulfenamide)

  Comparative Example 1 was unsuitable because of good rubber properties but low loss. In Comparative Example 2, both large loss and low dynamic ratio are compatible, but durability and rubber physical properties are inferior, and it is inappropriate as a vibration-proof rubber. On the other hand, in Examples 1-7, it was found that good rubber physical properties were exhibited, and both large loss and low dynamic ratio were achieved, and the rubber was extremely excellent as a vibration-proof rubber.

  The anti-vibration rubber composition of the present invention can achieve both a large loss and a low dynamic ratio while maintaining rubber properties equivalent to those of conventional anti-vibration rubbers, and can be used for anti-vibration members in various fields. it can. This anti-vibration rubber is suitable for anti-vibration of various devices such as various vehicles such as automobiles and railways, industrial machines and household appliances.

Claims (6)

  An anti-vibration rubber composition comprising a rubber component comprising a combination of a diene rubber and an epoxidized natural rubber, wherein the content of the epoxidized natural rubber in the rubber component is 10% by mass or more.   The anti-vibration rubber composition according to claim 1, wherein a content of the epoxidized natural rubber in the rubber component is 30 to 70% by mass.   The anti-vibration rubber composition according to claim 1 or 2, wherein the diene rubber is natural rubber.   The anti-vibration rubber composition according to any one of claims 1 to 3, wherein the epoxidized natural rubber blended as the rubber component has an epoxidation rate of 10 to 60 mol%. The filler includes carbon black having an iodine adsorption amount of 10 to 70 g / kg and a DBP oil absorption amount of 30 to 180 ml / 100 g, and / or silica having a BET specific surface area of 70 to 230 m ² / g. Item 5. The anti-vibration rubber composition according to any one of items 1 to 4.   Anti-vibration rubber comprising a vulcanized product of the anti-vibration rubber composition according to any one of claims 1 to 5.