JPH0912793A - Flame retardant ethylene-alpha-olefin copolymer rubber composition and vulcanized rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition containing a specific copolymer rubber and a softening agent in a specific ratio, excellent in flame retardance, ignition resistance and processability and useful for automotive parts, industrial rubber parts, etc. SOLUTION: This copolymer rubber composition contains (A) 100 pts.wt. ethylene-alpha-olefin copolymer rubber [e.g. having (50/50) to (95/5) molar ratio of ethylene unit (A1 ) to alpha-olefin unit (A2 )] and (B) 10-150 pts.wt. softening agent (e.g. a high-molecular weight hydrocarbon-based synthetic oil or chlorinated paraffin having 0.07-0.7dl/g intrinsic viscosity measured at 135 deg.C in decalin) having >=4l0 deg.C ignition temperature measured according to ASTM D2155-63.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to flame-retardant ethylene.
The present invention relates to an α-olefin copolymer rubber composition and a vulcanized rubber thereof, and more particularly to a flame-retardant rubber composition and a vulcanized rubber thereof which give a vulcanized rubber excellent in ignition resistance in a high temperature atmosphere.

[0002]

2. Description of the Related Art Ethylene / α-olefin copolymer rubbers represented by ethylene / propylene / diene copolymer rubbers are excellent in strength properties, heat resistance and weather resistance.
It is widely used for automotive parts, industrial rubber parts, electrical insulation materials, civil engineering building materials and other applications. Normal ethylene / α
-The olefin copolymer rubber is blended with a softening agent in order to impart processability and obtain a product having an intended hardness. However, the ethylene / α-olefin copolymer rubber has a high self-ignition temperature by itself, but the self-ignition temperature of the softening agent usually mixed with the rubber is low, so that the ignition temperature of the vulcanized rubber is lowered.

On the other hand, due to the recent high performance of automobiles and the like, the environmental conditions under which rubber products such as anti-vibration rubber are used are becoming more and more severe. Even in these use environments, the temperature of the atmosphere rises remarkably, and further improvement in flame retardancy during use in a high temperature atmosphere is required. Conventionally, in order to impart flame retardancy to a rubber composition, a halogen rubber represented by chloroprene rubber is used as a raw material rubber, or a method of adding an additive such as a halogen flame retardant is used. However, all of these methods generate a large amount of halogen-based toxic gas at high temperatures, which causes environmental hygiene problems and also reduces rubber strength.

[0004]

An object of the present invention is to provide a vulcanized rubber which is excellent in flame retardancy (ignition resistance) in a high temperature atmosphere and which does not generate a halogen-based toxic gas. An object is to provide an α-olefin copolymer rubber composition. Another object of the present invention is to provide a vulcanized rubber having a low hardness and a high strength, and an ethylene / α excellent in processability.
-To provide an olefin copolymer rubber composition.
Still another object of the present invention is flame retardancy (ignition resistance) obtained from the ethylene / α-olefin copolymer rubber composition.
It is to provide an excellent vulcanized rubber.

[0005]

The above-mentioned objects and advantages of the present invention are achieved by ASTM D2155-based on ethylene / α-olefin copolymer rubber and 100 parts by weight of the copolymer rubber.
A flame-retardant ethylene / α-olefin copolymer rubber composition containing 10 to 150 parts by weight of a softening agent having an ignition temperature of 410 ° C. or higher measured according to 63 and a vulcanized rubber of this rubber composition. Therefore, it is achieved by a vulcanized rubber in which the time required for ignition in an air atmosphere at 450 ° C. is 4 minutes or more.

Hereinafter, the present invention will be described in detail, which will make clear the objects, configurations, advantages and effects of the present invention.

The ethylene / α-olefin copolymer rubber used in the rubber composition of the present invention basically comprises ethylene units and α-olefin units, and further contains a non-conjugated polyene component unit as a constituent component. You may.
The α-olefin is a linear α-olefin having 3 to 20 carbon atoms, and specifically, propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene. -1, octene-1, nonene-1,
Decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, nonadecene-1, eicosene-1,9-methyl-decene-1,11- Methyl-
Dodecene-1, 12-ethyl-tetradecene-1 and the like are mentioned, and among them, propylene and 1-butene are preferably used.

Ethylene / α used in the composition of the present invention
-Ethylene units constituting the olefin copolymer rubber and α-
The molar ratio with the olefin unit (ethylene / α-olefin) is 50/50 to 95/5, preferably 55/45.
To 93/7, and more preferably 60/40 to 91/9.

Specific examples of the non-conjugated polyene component include 1,4-hexadiene, 1,6-octadiene and 2
-Methyl-1,5-hexadiene, 6-methyl-1,5-
Heptadiene, chain non-conjugated dienes such as 7-methyl-1,6-octadiene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene, 5-methylene-2. Examples include cyclic non-conjugated dienes such as -norbornene, 5-isopropylidene-2-norbornene, dicyclopentadiene, cyclohexadiene, and methyltetrahydroindene. Among them, 5-ethylidene-2-norbornene and dicyclopentadiene are preferably used.

The content of these non-conjugated polyene component units is 1 to 50, preferably 4 to 40, more preferably 6 to 30 in terms of iodine value, and is 0.1 in terms of mol%.
It is 1 to 10 mol%, preferably 0.5 to 7 mol%, and more preferably 1 to 5 mol%. From the balance of the processability of the composition of the present invention and the strength of the vulcanized rubber, the intrinsic viscosity [η] of the ethylene / α-olefin copolymer rubber of the present invention measured at 135 ° C. in a decalin solvent is 0.8 to 5dl /
g, preferably 0.9 to 4 dl / g, and more preferably 1.0 to 3 dl / g. The ethylene / α-olefin copolymer rubber is produced by a method known per se.

Ethylene / α used in the composition of the present invention
-Olefin copolymer rubber is a natural rubber (N
R), styrene / butadiene copolymer rubber (SBR), chloroprene rubber (CR), acrylonitrile / butadiene copolymer rubber (NBR), chlorosulfonated polyethylene, chlorinated ethylene / α-olefin copolymer rubber, and other rubber components. It can also be used in combination with resin components such as polyethylene, polyethylene (PE) and polypropylene (PP). In this case, the proportion of these components in the total rubber and resin components is preferably 0 to 50% by weight, more preferably 0 to 30% by weight.

The ignition temperature used in the composition of the present invention is 4
Examples of the softening agent at 10 ° C. or higher include high-viscosity paraffin oil, high-viscosity ethylene / α-olefin copolymerized oil, high-viscosity hydrocarbon synthetic oil such as high-viscosity polybutene. High-viscosity paraffin oil and high-viscosity ethylene / α-olefin copolymerized oil are preferably used. These may be used alone or in combination of two or more as required.

Further, a softening agent having an ignition temperature of 410 ° C. or higher, which is different from the above-mentioned high molecular weight hydrocarbon synthetic oil, can be used in combination within the range not impairing the achievement of the object of the invention. Examples of such softening agents include paraffin-based process oil and naphthene-based process oil.

However, it is preferable that the high molecular weight hydrocarbon-based synthetic oil accounts for 70 to 100% by weight of the total amount of the softening agent used.

Considering a good balance between the plasticizing effect as a softening agent and the flame retardancy, the intrinsic viscosity [η] of a high molecular weight hydrocarbon synthetic oil measured in a decalin solvent at 135 ° C.
Is 0.07 to 0.7 dl / g, preferably 0.1 to 0.5
dl / g.

The α-olefin of the high-viscosity ethylene / α-olefin copolymerized oil is a linear α-olefin having 3 to 8 carbon atoms.
-Olefin, and specific examples thereof include propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1 and the like.
Of these, propylene and 1-butene are preferably used.

The amount ratio of the ethylene / α-olefin copolymer rubber and the softening agent contained in the rubber composition of the present invention is 10 to 150 parts by weight of the softener per 100 parts by weight of the ethylene / α-olefin copolymer rubber. , Preferably 10 to 80 parts by weight. By satisfying the above amount ratio, the vulcanized rubber of the composition of the present invention is excellent in flame retardancy in a high temperature atmosphere, maintains an appropriate hardness and high strength, and also appropriately maintains the processability of the composition itself. To be done.

The flame-retardant rubber composition of the present invention includes an ethylene / α-olefin copolymer rubber, a softening agent having an ignition temperature of 410 ° C. or higher, a vulcanizing agent and a vulcanization aid known per se. Reinforcing agent, filler, metal activator, anti-scorch agent,
A rubber compounding agent such as an antiaging agent or a processing aid can be compounded within a range not impairing the achievement of the object of the present invention.

The rubber composition of the present invention may contain a small amount of a softening agent having an ignition temperature of less than 410 ° C., but the proportion of the softening agent in the composition is 5 parts by weight per 100 parts by weight of the composition. Parts, and it is preferable not to mix them for the purpose of exhibiting a flame retardant effect.

As the reinforcing agent, SRF, GPF, FE
Carbon black such as F, HAF, ISAF, SAF, FT and MT; other finely powdered silicic acid and the like, as fillers, light calcium carbonate, heavy calcium carbonate, talc,
Examples include clay and silica. The types and blending amounts of these rubber reinforcing agents and fillers can be appropriately selected according to their applications. The compounding amount is usually 300 parts by weight at the maximum, preferably 200 parts by weight at the maximum, based on 100 parts by weight of the ethylene / α-olefin copolymer rubber.

The rubber composition of the present invention can be used as it is in an unvulcanized state, but when it is used as a vulcanized product, its characteristics can be most exerted. That is, vulcanization improves the flame retardancy in the original high temperature atmosphere,
It is possible to obtain a vulcanized rubber excellent in original strength characteristics and dynamic fatigue resistance.

When a vulcanized rubber is obtained from the rubber composition of the present invention, depending on the intended use and performance of the vulcanized rubber, the type of ethylene / α-olefin copolymer rubber and the softening agent and other rubber compounding agents and The blending amount and the step of producing the vulcanized rubber can be appropriately selected.

Crosslinked ethylene / α in vulcanized rubber
The total amount of the olefin copolymer rubber and the softening agent having an ignition point of 410 ° C. or higher can be appropriately selected according to the intended performance of the vulcanized rubber and the intended use, but is usually 20% by weight or more, preferably 2%.
5% by weight or more.

In order to produce a vulcanized rubber from the rubber composition of the present invention, an unvulcanized compounded rubber is once prepared and then this compounded rubber is intended, as in the case of vulcanizing a general rubber. Vulcanization may be performed after molding into a desired shape. As the vulcanization method, either a method of heating using a vulcanizing agent or a method of irradiating an electron beam may be adopted.

Examples of the vulcanizing agent used during vulcanization include sulfur compounds and organic peroxides. In particular, when the sulfur compound is used, the performance of the rubber composition of the present invention can be best exhibited. Specific examples of the sulfur compound include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, and the like. Of these, sulfur is preferably used. The sulfur compound is usually 0.1 to 10 parts by weight, and preferably 0.5 to 100 parts by weight of the ethylene / α-olefin copolymer rubber of the present invention.
It is used in an amount ratio of 5 parts by weight.

When a sulfur compound is used as a vulcanizing agent, it is preferable to use a vulcanization accelerator together. Specific examples of the vulcanization accelerator include N-cyclohexyl-2-
Benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N, N
-Diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, 2- (2,4
-Dinitrophenyl) mercaptobenzothiazole, 2
Thiazole compounds such as (2,6-diethyl-4-morpholinothio) benzothiazole and dibenzothiazyl disulfide; guanidines such as diphenylguanidine, triphenylguanidine, diorsonitrile guanidine, orthonitrile biguanide and diphenylguanidine phthalate Compound;

Acetaldehyde-aniline reaction products, butyraldehyde-aniline condensates, aldehyde amines such as hexamethylenetetramine, acetaldehyde ammonia, or aldehyde-ammonia compounds; imidazoline compounds such as 2-mercaptoimidazoline; thiocarbanilide, diethylthiourea, dibutyl. Thiourea compounds such as thiourea, trimethylthiourea and diorthotolylthiourea; thiuram compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide; dimethyl Zinc dithiocarbamate, zinc diethyldithiocarbamate, di-n-butyldithiocarba Dithioate compounds such as zinc acidate, zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, selenium dimethyldithiocarbamate, tellurium dimethyldithiocarbamate; xanthate compounds such as zinc dibutylxanthate; zinc white And the like. These vulcanization accelerators are usually used in an amount ratio of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the ethylene / α-olefin copolymer rubber.

The organic peroxide may be any of those normally used for peroxide vulcanization of rubber. For example, dicumyl peroxide, di-t-butyl peroxide,
Di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylhydroperoxide, t-butylcumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di (t-butyl) Peroxine) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,
5-mono (t-butylperoxy) -hexane, α,
Examples include α′-bis (t-butylperoxy-m-isopropyl) benzene and the like. Among them, dicumyl peroxide, di-t-butyl peroxide, di-t
-Butylperoxy-3,3,5-trimethylcyclohexane is preferably used. These organic peroxides are 1
Used according to the present invention, or two or more kinds of the ethylene / α-
Normally 0.000 per 100 g of olefin copolymer rubber
It is used in the range of 3 to 0.05 mol, preferably 0.001 to 0.03 mol, but it is desirable to appropriately determine the optimum amount according to the required physical properties.

When an organic peroxide is used as a vulcanizing agent, it is preferable to use a vulcanizing auxiliary together. Specific examples of the vulcanization aid include sulfur; quinone dioxime compounds such as p-quinone dioxime; methacrylate compounds such as polyethylene glycol dimethacrylate; allyl compounds such as diallyl phthalate and triallyl cyanurate; Other examples include maleimide compounds; divinylbenzene and the like. Such a vulcanization aid is usually used in an amount ratio of 0.5 to 2 mol, preferably about equimolar to 1 mol of the organic peroxide used.

When an electron beam is used as a vulcanizing method without using a vulcanizing agent, 0.1 to 10 MeV (megaelectron volt), preferably 0.3, is applied to a molded unvulcanized compounded rubber described later. An electron with an energy of ~ 2 MeV and an absorbed dose of 0.5-35 Mrad,
Irradiation may be performed preferably at 0.5 to 10 Mrad.

The unvulcanized compounded rubber is prepared, for example, by the following method. That is, after mixing the ethylene / α-olefin copolymer rubber, the softening agent, the filler and the like with a mixer exemplified by a Banbury mixer at a temperature of 80 to 170 ° C. for 3 to 10 minutes, rolls exemplified by an open roll are mixed. A vulcanizing agent and, if necessary, a vulcanization accelerator and / or a vulcanization aid are additionally mixed, and a roll temperature of 40 is used.
After kneading at -80 ° C for 5 to 30 minutes, the mixture is dispensed to prepare a ribbon-shaped or sheet-shaped compounded rubber.

The unvulcanized compounded rubber thus prepared is molded into an intended shape by an injection molding machine, a transfer molding machine, an extrusion molding machine, a calender roll, or a press, and at the same time as molding or a molded product is obtained. The vulcanized rubber is obtained by introducing it into a vulcanization tank and heating it at a temperature of 150 to 270 ° C. for 1 to 30 minutes, or by irradiating it with an electron beam by the method described above. A mold may be used in this vulcanization step, or vulcanization may be performed without using a mold. When a mold is not used, the steps of molding and vulcanization are usually performed continuously. The heating method in the vulcanization tank is hot air, a fluidized bed of glass beads, UHF (ultra high frequency electromagnetic wave),
A heating tank such as steam can be used. Of course, when vulcanization is performed by electron beam irradiation, a compounded rubber containing no compounding agent is used.

The vulcanized rubber of the present invention produced as described above has a hardness (JIS A) of usually 35 to 75, which is measured according to the method described in the section of Examples below.
It is preferably 50 to 70, and the time required for ignition in an air atmosphere at 450 ° C. is usually 4 minutes or longer, preferably 4.5 minutes or longer.

Therefore, the vulcanized rubber of the present invention is suitable for use as a material for rubber products which are required to have flame retardancy, low hardness and high strength, such as vibration-proof rubber for automobiles.
Furthermore, the vulcanized rubber of the present invention can also be used as a material for industrial rubber products such as rubber rolls and belts, electrical insulating materials, civil engineering building materials, and rubberized cloth.

In addition, in the case of producing a foam from the rubber composition according to the present invention, a foaming agent usually used for rubber and a foaming auxiliary agent can be blended if necessary, and the resulting foaming is obtained. The material can be used as a heat insulating material, a cushioning material, a sealing material and the like. These foaming agents are used in an amount ratio of 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, relative to 100 parts by weight of the ethylene / α-olefin copolymer rubber of the present invention, and an apparent specific gravity of 0.03. Foams up to 0.7 can be produced.

[0036]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, each physical property was measured according to the following methods. Ignition temperature of softening agent: measured according to ASTM D2155-63. Kinematic viscosity of softening agent: measured according to JIS K2280. Intrinsic viscosity [η] of softening agent: measured in decalin solvent at 135 ° C. Tensile strength at break of vulcanized rubber: Measured according to JIS K6301. Elongation at break of vulcanized rubber: Measured according to JIS K6301.

Ignition time of vulcanized rubber: The temperature in a combustion furnace (muffle furnace) capable of circulating internal and external air is 450 ° C.
The test piece was suspended in the center of the furnace and the time until the test piece ignited was measured. The shape of the test piece is JIS
The shape was the same as the shape of the test piece for compression set test described in K6301 (columnar shape having a diameter of 29 mm and a thickness of 12.7 mm).

Example 1 A vulcanized rubber was prepared and tested by the following procedure. An unvulcanized compounded rubber having the composition shown in Table 1 was prepared. When blending,
The ethylene / α-olefin copolymer rubber, the softening agent, the zinc white, the stearic acid and the filler were kneaded with a 4.3 liter Banbury mixer (manufactured by Kobe Steel) for 4 minutes and then left at room temperature for 1 day. A foaming agent, a foaming auxiliary agent, sulfur, and a vulcanization accelerator were added to the kneaded product thus obtained with a 14-inch open roll (front roll / rear roll: surface temperature 50/60 ° C., rotation speed 16/18 rpm). To obtain an unvulcanized compounded rubber which was kneaded and molded into a ribbon shape. Next, this unvulcanized rubber was subjected to 160 t using a 100 t press (manufactured by Kotaki Co.)
Vulcanization was performed at 30 ° C. for 30 minutes to obtain a test piece having a predetermined shape for various tests, and the test was performed. The results are shown in Table 2.

[0039]

[Table 1]

Example 2 Example 1 was repeated except that the following softener was used in Example 1. The results are shown in Table 2. High-viscosity hydrocarbon synthetic oil (Lucanto HC-20
00 Mitsui Petrochemical Co., Ltd.) Ignition point: 420 ° C or higher Intrinsic viscosity [η]: 0.2 dl / g Kinematic viscosity: 2100 cSt (100 ° C)

Example 3 Example 1 was repeated except that the following softener was used in Example 1. The results are shown in Table 2. High viscosity hydrocarbon synthetic oil (Lucant HC-15
0 Mitsui Petrochemical Co., Ltd.) Ignition point: 415 ° C. Intrinsic viscosity [η]: 0.09 dl / g Kinematic viscosity: 150 cSt (100 ° C.)

Example 4 Example 1 was repeated except that 20 parts by weight of the softening agent and 30 parts by weight of FEF carbon black were used in Example 1. The results are shown in Table 2.

Example 5 Example 1 was repeated except that in Example 1 80 parts by weight of the softening agent and 90 parts by weight of FEF carbon black were used. The results are shown in Table 2.

Example 6 Example 1 was repeated except that the following ethylene / α-olefin copolymer rubber and softening agent were used. The results are shown in Table 2. Ethylene / α-olefin / 5-ethylidene norbornene copolymer rubber (EPDM) Ethylene / propylene (molar ratio): 78/22 Iodine value: 15 Intrinsic viscosity [η]: 3.3 dl / g ML1 + 4 (160 ° C): 41 High-viscosity hydrocarbon synthetic oil (Lucanto HC-20
00 Mitsui Petrochemical Co., Ltd.) Ignition point: 420 ° C or higher Intrinsic viscosity [η]: 0.2 dl / g Kinematic viscosity: 2100 cSt (100 ° C)

Comparative Example 1 Example 1 was repeated except that the naphthenic process oil having the following properties was used as the softening agent of Example 1. The results are shown in Table 2. Naphthenic process oil Ignition point: 370 ° C Kinematic viscosity: 340cSt (40 ° C) [η]: about 0.04dl / g

Comparative Example 2 Example 1 was repeated, except that the softening agent of Example 1 was replaced with a paraffinic process oil having the following properties. Table 2 shows the results
It was shown to. Paraffin-based process oil Ignition point: 350 ° C Kinematic viscosity: 410 cSt (40 ° C) [η]: About 0.04 dl / g

[0047]

[Table 2]

[0048]

INDUSTRIAL APPLICABILITY The rubber composition of the present invention has strength characteristics, heat resistance, weather resistance, vibration damping property, in addition to flame retardancy in a high temperature atmosphere.
It is possible to provide a vulcanized product having excellent vibration damping properties and dynamic fatigue resistance. The vulcanized product obtained from the rubber composition of the present invention has the excellent physical properties as described above, and therefore, the anti-vibration rubber,
It is widely used for automobile parts such as tire vibration cover materials, industrial rubber products such as rubber rolls, belts and hoses, electrical insulation materials, civil engineering building materials, rubberized cloth, etc. In particular, it can be suitably used for applications where vibration damping and dynamic fatigue resistance are required, for example, anti-vibration rubber for automobiles, rubber rolls, belts and the like. Further, the foam produced from the rubber composition of the present invention is a heat insulating material, a cushioning material,
It can be used for applications such as sealing materials.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C08L 23/18 C08L 23/18 (72) Inventor Norihiro Harada 330 Naganuma-cho, Inage-ku, Chiba Prefecture Kinugawa Gum Industry Co., Ltd. (72) Inventor Satoshi Nomura 330 Naganuma-cho, Inage-ku, Chiba-shi, Chiba Kinugawa Gum Industry Co., Ltd.

Claims (8)

[Claims] 1. An ethylene / α-olefin copolymer rubber and ASTM D21 per 100 parts by weight of the copolymer rubber.
A flame-retardant ethylene / α-olefin copolymer rubber composition comprising 10 to 150 parts by weight of a softening agent having an ignition temperature of 410 ° C. or higher measured according to 55-63. 2. The rubber composition according to claim 1, wherein the ethylene / α-olefin copolymer rubber has a molar ratio of ethylene units and α-olefin units (ethylene / α-olefin) of 50/50 to 95/5. . 3. The α-olefin is propylene or 1-
The rubber composition according to claim 1 or 2, which is butene. 4. The rubber composition according to claim 1, wherein the ethylene / α-olefin copolymer rubber contains 1 to 50 non-conjugated polyene component units in iodine value notation. 5. The rubber composition according to claim 1, wherein the softening agent having an ignition temperature of 410 ° C. or higher is at least one selected from high molecular weight hydrocarbon synthetic oils and chlorinated paraffins. 6. The rubber composition according to claim 1, wherein the softening agent has an intrinsic viscosity [η] (decalin solvent, measured at 135 ° C.) of 0.07 to 0.7 dl / g. 7. The rubber composition according to claim 1, wherein a time required for ignition in an air atmosphere at 450 ° C. is 4 minutes or more, and a hardness (JIS A) is 35 to 75. Vulcanized rubber. 8. The use as an anti-vibration rubber for automobiles.
Vulcanized rubber described in.