JPH061891A - Rubber composition for heat-resistant vibration-damping rubber - Google Patents

Abstract

PURPOSE:To obtain a rubber compsn. which gives an automotive heat-resistant vibration-damping rubber excellent in heat resistance by using a specific ethylene/alpha-olefin/nonconiugated diene copolymer rubber compsn. as the main component. CONSTITUTION:The title compsn. contains as the main component an ethylene/alpha- olefin/nonconjugated diene copolymer rubber compsn. which comprises 99-60 wt.% ethylene/a-olefin/nonconjugated diene copolymer rubber which has a molar ratio of the ethylene units to the 3-20C alpha-olefin units of (60/40)-(73/27), a mol.wt. distribution (Mw/Mn, Q value) lower than 4, an intrinsic viscosity [eta] of 2.7-5.0dl/g, and an iodine value of 10-40 and of which the nonconjugated diene units are 5-ethylidene-2-norbornene units and 1-40wt.% liq. ethylene/alpha-olefin copolymer which has a molar ratio of ethylene units to 3-20C alpha-olefin units of (50/50)-(78/22) and an intrinsic viscosity [eta] of 0.2-0.4dl/g. The title compsn. gives a vulcanizate having a loss tangent (tan delta) measured by a dynamic viscoelasticity test of 0.15-0.35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat and vibration resistant rubber composition, and more particularly to an anti-vibration rubber composition for automobile engine mount insulators, center bearing insulators, rack and pinion type steering device insulators, etc. The present invention relates to a heat-resistant vibration-proof rubber composition that can be suitably used as a vibration-rubber material.

[0002]

BACKGROUND OF THE INVENTION In recent years, various anti-vibration rubbers used in automobiles have become particularly severe in heat resistance and anti-vibration properties. That is, in recent years, as a result of the reduction of the heat radiation space in the engine room and the increase in the output of the engine in automobiles, the atmospheric temperature in the engine room tends to rise, and the thermal environment of various anti-vibration rubbers is It's getting tougher. Examples of various anti-vibration rubbers include rubbers used for engine mount insulators, center bearing insulators, rack and pinion type steering device insulators (hereinafter sometimes referred to as rack mount insulators), and the like. Hereinafter, each of these insulators will be described.

First, in the engine mount insulator, in addition to the function of supporting most of the load of the engine and the function of supporting the torque reaction force generated by the engine, it is required to satisfy good soundproofing and antivibration characteristics. It Conventionally, engine mount insulators have been mainly made of natural rubber having appropriate vibration damping performance and excellent fatigue resistance (durability). In some cases, butadiene rubber, styrene-butadiene rubber, chloroprene rubber are used. , Butyl rubber, etc. are used alone or in many cases blended with natural rubber (hereinafter,
Natural rubber-based material).

However, as described above, at present, the heat environment in the engine room is deteriorated, in terms of heat resistance,
Natural rubber materials are reaching their limits. On the other hand, butadiene rubber and styrene-butadiene rubber alone have problems that durability is inferior to natural rubber and heat resistance is not sufficient. Further, chloroprene rubber is inferior in low-temperature flexibility, and is therefore unsuitable for vibration-proof rubber applications. Although butyl rubber is excellent in damping performance, it has a fundamental problem of extremely high dynamic magnification and also has a problem of inferior durability to natural rubber. Although conventional ethylene / propylene rubber has excellent heat resistance, it has a drawback that durability is inferior to that of natural rubber.

Also in the center bearing insulator of the automobile, the thermal environment is deteriorated as in the case of the engine mount insulator described above, and the conventional center bearing insulator cannot satisfy the heat resistance. This center bearing insulator is located at the center of the propeller shaft of FR and 4WD vehicles and is used for the joint between the propeller shaft and the center bearing. Vibration from the propeller shaft is directly transmitted to the chassis via the center bearing. It also plays a role in controlling and supporting the behavior of the propeller shaft. Conventionally, since the center bearing insulator is required to have high strength and low fatigue strength, a natural rubber material has been used. Since the conventional center bearing insulator is a natural rubber-based material, it suffers from severe heat aging in a heat environment exceeding 100 ° C and cannot be put to practical use. Further, as a method of improving the heat resistance of the natural rubber material, there is a method called semi-effective vulcanization or effective vulcanization in which the amount of sulfur as a vulcanizing agent is reduced to perform vulcanization. However, although such a method improves the heat resistance of the natural rubber-based material, the improvement effect is about 10 ° C. and there is a drawback that the durability is deteriorated, so that the required quality cannot be satisfied. There wasn't.

[0006] Chloroprene rubber, ethylene-propylene rubber, butyl rubber and the like have been conventionally known as raw material rubbers having heat resistance superior to that of natural rubber materials, but these rubbers have the above-mentioned problems. There is no fault.

Further, in the rack mount insulator of the automobile, the thermal environment is deteriorated as in the case of the engine mount insulator and the center bearing insulator described above, and the heat resistance of the conventional rack mount insulator cannot be satisfied. There is.

The rack mount insulator is used for a fastening portion between the steering wheel and the rack and prevents vibrations from the tires from being directly transmitted to the steering wheel through the rack, and also has a good effect on the sensitivity of the steering wheel. Is responsible for Therefore, rack mount insulators are required to have appropriate vibration damping performance and excellent fatigue resistance (durability). Conventionally, natural rubber materials have been used as materials for rack mount insulators that meet these requirements. Has been done.

However, as described above, due to the deterioration of the thermal environment in the engine room, natural rubber materials have reached the limit in terms of heat resistance. On the other hand, EP with excellent heat resistance
DM has a drawback that its durability is inferior to that of a natural rubber material.

Therefore, the appearance of a rubber composition for heat-resistant anti-vibration rubber, which has the same level of anti-vibration properties and durability as the natural rubber-based anti-vibration rubber, and has heat resistance superior to that of the natural rubber-based material, has been developed. Was wanted.

[0011]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and has the same level of vibration damping characteristics and durability as natural rubber vibration damping rubber.
An object of the present invention is to provide a rubber composition for a heat and vibration resistant rubber, which can provide a vibration resistant rubber having heat resistance superior to that of a natural rubber material.

[0012]

SUMMARY OF THE INVENTION A rubber composition for a heat and vibration resistant rubber according to the present invention comprises [I] ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated diene, and ethylene and α-
The molar ratio with olefin is 60/40 to 73/27, and the molecular weight distribution (Mw /
Mn) Q value is less than 4, and the intrinsic viscosity [η] measured in decalin at 135 ° C. is 2.7 to 5.0 dl / g,
Ethylene / α-olefin / non-conjugated diene copolymer rubber (A) having an iodine value of 10 to 40 and a non-conjugated diene of 5-ethylidene-2-norbornene: 99 to 60% by weight, and ethylene and carbon atoms It is composed of α-olefin of several 3 to 20, the molar ratio of ethylene to α-olefin is 50/50 to 78/22, and the intrinsic viscosity [η] measured in decalin at 135 ° C. is 0.2. ~ 0.4dl
A liquid ethylene / α-olefin copolymer (B): 1/40% by weight of an ethylene / α-olefin / non-conjugated diene copolymer rubber composition as a main component. The loss tangent (tan δ) obtained by the dynamic viscoelasticity test after vulcanization is 0.15 to 0.35.

This rubber composition for heat-resistant and vibration-proof rubber is prepared by mixing sulfur [II] 0.1 to 100 parts by weight of ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I].
10 parts by weight and carbon black [III] 40-12
0 parts by weight may be contained.

The rubber composition for heat-resistant and vibration-proof rubber of the present invention is a rubber composition for automobile engine mount insulators,
It is preferably used as a rubber composition for an automobile center bearing insulator or a rubber composition for an insulator of an automobile rack and pinion type steering device.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The rubber composition for heat and vibration resistant rubber according to the present invention will be specifically described below. The rubber composition for heat-resistant and vibration-proof rubber according to the present invention comprises [I] specific ethylene
An unvulcanized rubber composition composed of an α-olefin / non-conjugated diene copolymer rubber composition, in which a loss tangent (tan δ) determined by a dynamic viscoelasticity test after vulcanization falls within a specific range. It is in. Further, the rubber composition for heat and vibration resistant rubber according to the present invention, in addition to the ethylene / α-olefin / non-conjugated diene copolymer rubber composition, [II] sulfur,
[III] Carbon black may be contained. This rubber composition can be vulcanized and molded to be used as an insulator (vulcanized rubber). Examples of the insulator include the engine mount insulator, the center bearing insulator, and the rack mount insulator as described above.

[I] Ethylene / α-olefin / non-conjugated
Diene Copolymer Rubber Composition The ethylene / α-olefin / non-conjugated diene copolymer rubber composition used in the present invention comprises a specific ethylene / α-olefin / non-conjugated diene copolymer rubber (A) and a specific ethylene / α-olefin / non-conjugated diene copolymer rubber (A). Liquid ethylene / α-olefin copolymer (B).

Ethylene / α-olefin / non-conjugated diene
Copolymer Rubber (A) The ethylene / α-olefin / non-conjugated diene copolymer rubber (A) is a high molecular weight rubber composed of ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated diene. is there.

This ethylene / α-olefin / non-conjugated diene copolymer rubber (A) has a molar ratio [ethylene / α-olefin] of ethylene and α-olefin of 60/40.
73/27, preferably 65/35 to 70/30. When the above molar ratio is less than 60/40, the strength of the vulcanized rubber of the obtained rubber composition tends to decrease. On the other hand, when the molar ratio exceeds 73/27, the low temperature flexibility of the vulcanized rubber of the obtained rubber composition tends to decrease.

Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, butene-1, hexene-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, octadecene-
1, nonadecene-1, eicosene-1 and the like. These α-olefins are used alone or in combination. Of these, propylene is particularly preferable.

As the above-mentioned non-conjugated diene, specifically, 5-ethylidene-2-norbornene is used. The ethylene / α-olefin / non-conjugated diene copolymer rubber (A) has an iodine value of 10 to 40, which is one index of the content of non-conjugated diene, preferably 15 to 25. When the iodine value is less than 10, the rubber composition obtained tends to have a slow vulcanization rate. On the other hand, when the iodine value exceeds 40, the vulcanized rubber of the obtained rubber composition tends to have low heat resistance.

The ethylene / α-olefin / non-conjugated diene copolymer rubber has a molecular weight distribution (Mw / Mn) Q value determined by GPC measurement of less than 4, preferably 3 or less. To provide a vulcanized rubber excellent in mechanical strength characteristics and dynamic fatigue resistance by using a high molecular weight ethylene / α-olefin / non-conjugated diene copolymer rubber (A) having such a molecular weight distribution. It is possible to obtain a rubber composition capable of

The ethylene / α-olefin / non-conjugated diene copolymer rubber (A) has an intrinsic viscosity [η] measured in decalin of 135 ° C. of 2.7 to 5.0 dl / g,
It is preferably 3.5 to 4.5 dl / g. When the intrinsic viscosity [η] is less than 2.7 dl / g, the durability tends to decrease. On the other hand, the intrinsic viscosity [η] is 5.0 dl /
If it exceeds g, the productivity of polymer synthesis tends to decrease. When an ethylene / α-olefin / non-conjugated diene copolymer rubber having an intrinsic viscosity [η] in the above range is used, a rubber composition having excellent dynamic fatigue resistance can be obtained.

The above-mentioned ethylene / α-olefin /
Non-conjugated diene copolymer rubbers are, for example, Japanese Patent Publication No. 59-1.
It can be manufactured by the method described in Japanese Patent No. 4497. That is, in the presence of a Ziegler catalyst, hydrogen is used as a molecular weight regulator, and ethylene and C 3 are used.
An ethylene / α-olefin / non-conjugated diene copolymer rubber can be obtained by copolymerizing an α-olefin of about 20 to a diene.

Liquid ethylene / α-olefin copolymer (B) The liquid ethylene / α-olefin copolymer (B) is
It is a low molecular weight copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms and does not contain a diene component.

The above-mentioned liquid ethylene / α-olefin copolymer is a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. 3 to 3 carbon atoms
Specific examples of the α-olefin of 20 include 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, octadecene-1, nonadecene-1, eicosene-1 and the like. These α-olefins are used alone or in combination. Of these, propylene is particularly preferable.

In the present invention, the above-mentioned high molecular weight ethylene / α-olefin / non-conjugated diene copolymer rubber (A) is used.
To improve the heat resistance, mechanical strength characteristics, and dynamic fatigue resistance. On the other hand, the low molecular weight liquid ethylene / α-olefin copolymer (B) has excellent heat aging resistance and processability (fluidity). The quality was designed so that it could play an improving effect.

However, in an ethylene / α-olefin / non-conjugated diene copolymer rubber composition consisting of a high molecular weight component and a low molecular weight component, which is simply bimodal, that is, exhibits a molecular weight distribution having two modes, the high molecular weight Because of the tug-of-war relationship between the rate of improvement in physical properties such as heat resistance, mechanical strength characteristics, and dynamic fatigue resistance due to the components, and the rate of improvement in processability (flowability) due to the low molecular weight components, Even if the amount of low molecular weight components is increased and the processability is excellent, a vulcanized rubber having dramatically improved physical properties such as fatigue resistance cannot be provided.

Therefore, the inventors of the present invention have further studied this low molecular weight component. As a result, a vulcanized rubber was obtained from an ethylene / α-olefin / non-conjugated diene copolymer rubber composition showing a bimodal molecular weight distribution. At the time of obtaining, it was found that it is necessary that the low molecular weight component constituting the vulcanized rubber is not crosslinked as a polymer. That is, in the present invention, a liquid ethylene / α-olefin copolymer containing no diene is used as the low molecular weight component.

The liquid ethylene / α-olefin copolymer (B) used in the present invention has a molar ratio of ethylene / α-olefin of 50/50 to 78/22 mol%, preferably 50/50 to 70/30. , And more preferably 50/50
Within the range of 60/40. Since the liquid ethylene / α-olefin copolymer having the above molar ratio in the above range has good thermal stability, the high molecular weight ethylene / α-olefin / non-conjugated diene copolymer as described above is used. The amount does not decrease during the kneading operation with the rubber (A), and it does not carbonize during molding to contaminate the molded product.

The liquid ethylene / α-olefin copolymer (B) has an intrinsic viscosity [η] measured in decalin at 135 ° C. of 0.2 to 0.4 dl / g, preferably 0.24.
~ 0.4 dl / g. The intrinsic viscosity [η] is 0.2
When it is less than dl / g, the processability (fluidity) of the obtained ethylene / α-olefin / non-conjugated diene copolymer rubber composition tends to be lowered. On the other hand, when the intrinsic viscosity [η] exceeds 0.4 dl / g, the vulcanized rubber of the obtained ethylene / α-olefin / non-conjugated diene copolymer rubber composition has a large dynamic ratio as tan δ increases. , The ability to suppress vibrations in the high frequency range tends to decrease.

The liquid ethylene / α-olefin copolymer as described above can be produced, for example, by the method described in Japanese Patent Publication No. 2-1163. That is, in the presence of a Ziegler catalyst, hydrogen is used as a molecular weight modifier, and ethylene is randomly copolymerized with an α-olefin having 3 to 20 carbon atoms to obtain a liquid ethylene / α-olefin copolymer. You can

Ethylene / α-olefin / non-conjugated diene
Production of Copolymer Rubber Composition In the ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I] used in the present invention, the high molecular weight ethylene / α-olefin / non-conjugated diene copolymer rubber ( A) is 99 to 6 with respect to 100% by weight of the total amount of the ethylene / α-olefin / non-conjugated diene copolymer rubber (A) and the liquid ethylene / α-olefin copolymer (B).
It exists in a proportion of 0% by weight, and has low molecular weight liquid ethylene / α
-The olefin copolymer (B) is present in a ratio of 1 to 40% by weight based on 100% by weight of the total amount of the above (A) and (B).

The above-mentioned ethylene / α-olefin /
The non-conjugated diene copolymer rubber composition [I] has a Mooney viscosity ML _{1 + 4} (100 ° C.) of usually 20 to 150, preferably 30 to 135, and a molecular weight of 3,000 to 1.
Iodine number (IV ₁ ) and molecular weight 8 of 5,000 ethylene / α-olefin / non-conjugated diene copolymer rubber composition
The iodine value (IV) of the ethylene / α-olefin / non-conjugated diene copolymer rubber composition of 10,000 to 120,000 (IV
₂₎ and the ratio (IV ₁ / IV ₂₎ is usually 0.1 or less, preferably 0. The ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I having the Mooney viscosity ML _{1 + 4} (100 ° C.) and the above iodine value ratio (IV ₁ / IV ₂ ) within the above range [I ] Is excellent in kneading ability with a Banbury mixer or the like.

The ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I] used in the present invention is a solution or suspension of ethylene / α-olefin / non-conjugated diene copolymer rubber (A). And a solution or suspension of liquid ethylene / α-olefin, and then a solid substance is recovered. Further, first, either ethylene / α-olefin / non-conjugated diene copolymer rubber (A) or liquid ethylene / α-olefin copolymer (B) is obtained by polymerization, and in the presence of the polymer, The ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I] of the present invention can also be obtained by a so-called multistage polymerization method in which other components are obtained by polymerization.

[II] Sulfur The sulfur is used as a vulcanizing agent. Sulfur is used in a proportion of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I]. To be In the present invention, sulfur is present in the unvulcanized rubber composition, but it may be used when vulcanizing the above ethylene / α-olefin / non-conjugated diene copolymer rubber composition.

[III] Carbon Black The type of carbon black is not particularly limited as long as it is carbon black for rubber, and particularly HAF and MA.
Furnace carbon black such as F, FEF and GPF is preferred.

In the rubber composition for heat and vibration resistant rubber according to the present invention, carbon black is the above-mentioned ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I] 10
It is used in the range of 40 to 120 parts by weight with respect to 0 parts by weight. When the blending amount of carbon black is less than 40 parts by weight, the vulcanized rubber of the obtained rubber composition tends to have reduced hardness and strength. On the other hand, if the blending amount of carbon black exceeds 120 parts by weight, the resulting rubber composition tends to have poor processability, resulting in poor carbon black dispersion and the like. In the present invention, carbon black is
Although it is present in the unvulcanized rubber composition, it may be used when vulcanizing the ethylene / α-olefin / non-conjugated diene copolymer rubber composition.

Other compounding agents In the rubber composition for heat and vibration resistant rubber of the present invention, the above-mentioned ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I], sulfur [II] and carbon black [II] are added.
I] in addition to the compounding agents of the present invention, such as vulcanization accelerators, vulcanization aids, and softeners, which have been widely used conventionally in the production of vulcanized rubber moldings made of ethylene / propylene rubber or the like. It can be used within a range that does not impair the purpose.

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,
Thiazole compounds such as 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazole, dibenzothiazyl-disulfide; diphenylguanidine, triphenylguanidine, di Guanidine compounds such as orthotolyl guanidine, orthotolyl by guanide, diphenylguanidine phthalate; aldehydes such as acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reaction product-amine or aldehyde- Ammonia-based compounds; 2-mercaptoimidazoline and other imidazoline-based compounds; Thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea, etc. System compound; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide, thiuram-based compounds such as pentamethylene thiuram tetrasulfide; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate,
Zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate,
Dithioate-based compounds such as selenium dimethyldithiocarbamate and tellurium diethyldithiocarbamate; xanthate-based compounds such as zinc dibutylxanthate; and other compounds such as zinc white.

These vulcanization accelerators are the above-mentioned ethylene / α
-Olefin / non-conjugated diene copolymer rubber composition [I]
It is used in a proportion of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, relative to 100 parts by weight.

As the above-mentioned softening agent, a softening agent generally used for rubber is used. Specifically, petroleum-based softening agents such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and petrolatum; coal. Coal tar type softeners such as tar and coal tar pitch; Fat oil type softeners such as castor oil, linseed oil, rapeseed oil and coconut oil;
Tall oil; sub; waxes such as beeswax, carnauba wax, lanolin; fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, barium stearate, calcium stearate, zinc laurate; petroleum resin, atactic polypropylene, coumarone indene resin Synthetic polymer substances such as are used. Of these, petroleum-based softeners are preferably used, and process oils are particularly preferably used.

The rubber composition for heat-resistant and vibration-proof rubber (unvulcanized compounded rubber) according to the present invention is prepared, for example, by the following method. That is, using a mixer such as a Banbury mixer, the ethylene / α-olefin / non-conjugated diene copolymer rubber composition and the softening agent are added at 80 to 170.
Kneading at a temperature of ℃ for 3 to 10 minutes, and then using rolls such as an open roll, sulfur and carbon black as a vulcanizing agent, and optionally a vulcanization accelerator or vulcanization aid are additionally mixed. , 5 to 3 at a roll temperature of 40 to 80 ° C
After kneading for 0 minutes, the kneaded product is extruded to prepare a ribbon-shaped or sheet-shaped compounded rubber.

The rubber composition for heat and vibration resistant rubber of the present invention has a loss tangent (tan) determined by a dynamic viscoelasticity test after vulcanization.
It has a composition such that δ) is 0.15 to 0.35. That is, the rubber composition for an automobile engine mount insulator, the rubber composition for an automobile center bearing insulator, and the rubber composition for an automobile rack and pinion steering device insulator of the present invention are obtained by a dynamic viscoelasticity test after vulcanization. The composition has a loss tangent (tan δ) of 0.15 to 0.35. When this tan δ becomes less than 0.15,
Since the amount of the auxiliary material that affects the dynamic characteristics (tan δ) cannot be set to an appropriate amount, the reinforcing effect of the auxiliary material is reduced, and the strength characteristics required for the anti-vibration rubber may not be satisfied. There is.

Production of Vulcanized Rubber To obtain a vulcanized rubber from the rubber composition for heat-resistant and vibration-proof rubber according to the present invention, the above-mentioned unvulcanized rubber may be molded into an intended shape and then vulcanized. .

That is, the above-mentioned unvulcanized compounded rubber is molded into an intended shape by an extruder, calender roll, or press. Simultaneously with molding or by introducing the molded product into a vulcanization tank, the temperature is 130 to 270 ° C. It is heated at a temperature of 1 to 30 minutes to obtain a vulcanized rubber. When performing such vulcanization,
A mold may or may not be used.

[0046]

The rubber composition according to the present invention comprises a specific ethylene / α-olefin / non-conjugated diene copolymer rubber composition as a main component and is obtained by a dynamic viscoelasticity test after vulcanization. Since the loss tangent (tan δ) is in a certain range,
An anti-vibration rubber for automobiles that has the same level of anti-vibration properties and durability as a natural rubber-based anti-vibration rubber, has better heat resistance than natural rubber-based materials, and has excellent low-temperature flexibility. Can be provided.

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. The ethylene / α-olefin / non-conjugated diene copolymer rubbers in Examples and Comparative Examples, a rubber composition comprising the copolymer rubber and a liquid ethylene / α-olefin copolymer, and an insulator (vulcanized rubber) The test method for () is as follows.

[1] Molecular weight distribution (Mw / Mn) Q value The molecular weight distribution (Mw / Mn) Q value was measured according to "Gel Permeation Chromatography" published by Maruzen Co., Ltd. by Takeuchi. It was (1) Using standard polystyrene of known molecular weight (monodisperse polystyrene manufactured by Tosoh Corporation), molecular weight M and its GPC
(Gel Permeation Chromatog
Raphy) count, molecular weight M and elution volume E
A correlation diagram calibration curve with V (Elution Vlume) is created. The polystyrene concentration at this time is 0.02% by weight. (2) The GPC pattern of the sample is taken by the GPC measurement method, and the molecular weight M is known from the above (1). The sample preparation conditions and GPC measurement conditions in that case are as follows.

Sample preparation conditions (a) Samples are collected together with an o-dichlorobenzene solvent in an Erlenmeyer flask so that the concentration thereof will be 0.04% by weight. (B) Anti-aging agent 2,6-in the Erlenmeyer flask containing the sample
Di-tert-butyl-p-cresol is added at 0.1% by weight with respect to the polymer solution. (C) The Erlenmeyer flask is heated to 140 ° C. and stirred for about 30 minutes to dissolve the sample. (D) Thereafter, while maintaining the Erlenmeyer flask at 135 to 140 ° C., filtration is performed with a pore filter having a diameter of 1 μm. (E) The filtrate is subjected to GPC analysis.

GPC measurement conditions (a) Device: Waters type 200 (b) Column: Tosoh Corp. S-type (Mix type) (c) Sample amount: 2 ml (d) Temperature: 135 ° C. (e) Flow rate: 1 ml / mm (he) Total theoretical plate number of the column: 2 × 10 ⁴ to 4 × 10 ⁴ (measured value with acetone) [2] Processability The processability of the rubber composition is ○, △, A three-level evaluation of × was performed.

◯: The workability is excellent. Δ: Workability is good. X: Poor workability.

[3] Hardness Test The hardness test was carried out according to JIS K 6301 (1989), and the spring hardness (JIS A hardness) was measured.

[4] Gehmann low temperature torsion test The Gehmann low temperature torsion test is conducted according to JIS K 6301 (19).
1989), T ₂ [unit: ° C], T
₁₀ [Unit: ° C] was determined.

[5] Product durability test of engine mount insulator In the product durability test, an initial load of 90 kg in the P direction was applied to the insulator 2 of the automobile engine mount 1 shown in FIGS. 1 to 3 which was heat aged under the following conditions. After loading, the insulator 2 under the condition of a constant load of ± 180kg
The number of times of rupture was measured by repeating the process until rupture. The ambient temperature for this test was room temperature. Other test conditions are as follows.

Heat aging conditions: 120 ° C., 72 hours, Excitation frequency: 5 Hz, 2 Hz The number of breaks is 6, and the average of four breaks excluding the minimum and maximum values of these breaks. It is a value.

[6] Product durability test of center bearing insulators The product durability test is shown in FIG.
Propeller shaft 3 fastened with is ± 10mm in Q direction
While moving, it was performed at 120 ° C. and 140 ° C. at a vibration frequency of 7 Hz until the insulator 5 was broken, and the number of times of breaking was measured. The ambient temperature of this test is
The number of breaks is 100 ° C., the number of breaks is 6, and the average value of four breaks excluding the minimum and maximum values of these breaks.

[7] Product fatigue test of center bearing insulator In the product fatigue test, the amount of fatigue of the insulator 5 heat-aged at 100 ° C. for 300 hours under a load of 7 kg in FIG. The amount of settling of the insulator 5 heat-aged for 1,000 hours was measured. The atmospheric temperature of this test is 100 ° C.

[8] Product durability test of rack mount insulator In the product durability test, the rack mount insulator 6 shown in FIGS. 5 and 6 is attached with jigs 7 and 8 as shown in FIG. 7, and the temperature is room temperature and 120 ° C. ± 600 in P direction under atmosphere
After applying a constant load of kg or ± 1,005 kg and vibrating 100,000 times at a vibration frequency of 3 Hz, the rate of change of the static spring constant was measured.

[9] Dynamic Viscoelasticity Test The dynamic viscoelasticity test was performed using a rheometric viscoelasticity tester (model RDS-2) at a measurement temperature of 25 ° C., a frequency of 10 Hz and a strain rate of 1%. Dynamic shear modulus (kg / cm ² ) and dynamic loss modulus (kg / cm ² )
Then, the loss tangent tan δ (index of vibration damping) was calculated by the following formula.

G _s = G '+ ιG "(G _s : static shear modulus, real number G': dynamic shear modulus,
Imaginary number G ″: dynamic loss elastic modulus) tan δ = G ″ / G ′ [Examples and comparative examples of rubber compositions for engine mount insulators]

[0061]

Comparative Example 1 70 parts by weight of natural rubber (NR) [RSS No. 1], 30 parts by weight of styrene-butadiene rubber (SBR) [manufactured by Nippon Zeon Co., Ltd., trade name: Nipol 1502], and sulfur 1.5. Parts by weight and carbon black [N
550] 70 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, and aroma process oil (softening agent) 2
5 parts by weight, 5 parts by weight of antioxidants, 1.5 parts by weight of vulcanization accelerator (1), and 0.3 parts by weight of vulcanization accelerator (3) were added to a 4.3 liter capacity Banbury. It was kneaded with a mixer [Kobe Steel Co., Ltd.].

From the kneaded product thus obtained, test pieces for the above various tests were prepared and tested. The results are shown in Table 1.

[0063]

Comparative Examples 2 to 3 100 parts by weight of EPDM shown in Table 1, 0.5 parts by weight of sulfur and carbon black [N55
0] 70 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, and paraffinic process oil (softening agent) 5
0 parts by weight, vulcanization accelerator (1) 3.0 parts by weight, vulcanization accelerator (2) 1.5 parts by weight, vulcanization accelerator (3) 0.75
The parts by weight were kneaded with a Banbury mixer with a capacity of 4.3 liters (manufactured by Kobe Steel, Ltd.).

From the kneaded material thus obtained, test pieces for the above various tests were prepared and tested. The results are shown in Table 1.

[0065]

Comparative Example 4 and Examples 1 to 3 EPDM shown in Table 1
100 parts by weight of composition, 0.5 parts by weight of sulfur, 70 parts by weight of carbon black [N550], 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, and 50 parts by weight of paraffinic process oil (softening agent). And vulcanization accelerator (1) 3.
0 parts by weight, 1.5 parts by weight of the vulcanization accelerator (2) and 0.75 parts by weight of the vulcanization accelerator (3) were added to a 4.3 liter capacity Banbury mixer [Kobe Steel Works, Ltd.]. ] And kneaded.

From the kneaded product thus obtained, test pieces for the above various tests were prepared and tested. The results are shown in Table 1.

[0067]

[Table 1]

From Table 1, the following can be understood. Comparative Example 1 is an example of the NR / SBR material currently used, and this material has poor heat resistance and therefore has particularly poor fatigue resistance after heat aging.

In Comparative Example 2, EP having a low intrinsic viscosity [η] was used.
Since DM is used, fatigue resistance is poor. In Comparative Example 3, the workability was so poor that it could not be commercialized, and it could not be evaluated.

In Comparative Example 4, the processability was good due to the presence of the low molecular weight component (liquid ethylene / propylene copolymer), but the blend ratio of EPDM and liquid ethylene / propylene copolymer was 1: 1. In addition, when the ratio of the low molecular weight component is large, tan δ becomes too high and the vibration damping property and fatigue resistance of the engine mount deteriorate.

According to Examples 1 to 3, the rubber composition of the present invention has excellent workability and fatigue resistance, and particularly the fatigue resistance after heat treatment is much better than that of Comparative Example 1. is there. [Examples and Comparative Examples of Rubber Composition for Center Bearing Insulator]

[0072]

Comparative Example 5 70 parts by weight of natural rubber (NR) [RSS No. 1], 30 parts by weight of styrene-butadiene rubber (SBR) [manufactured by Nippon Zeon Co., Ltd., trade name: Nipol 1502], and sulfur 1.5 Parts by weight and carbon black [N
550] 70 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, aroma process oil 10 parts by weight, antioxidants 5 parts by weight, vulcanization accelerator (1) 1.5
4.3 parts by weight and vulcanization accelerator (3) 0.3 parts by weight
Liter capacity Banbury mixer [Kobe Steel Co., Ltd.
Manufactured].

From the kneaded product thus obtained, test pieces for the above various tests were prepared and tested. The results are shown in Table 2.

[0074]

Comparative Examples 6 to 7 100 parts by weight of EPDM shown in Table 2, 0.5 parts by weight of sulfur, and carbon black [N55
0] 70 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, paraffinic process oil 40 parts by weight, vulcanization accelerator (1) 3.0 parts by weight, vulcanization accelerator (2 ) 1.5 parts by weight and 0.75 parts by weight of the vulcanization accelerator (3) were kneaded with a Banbury mixer having a capacity of 4.3 liters (manufactured by Kobe Steel Ltd.).

From the kneaded product thus obtained, test pieces for the above-mentioned various tests were prepared and subjected to the above-mentioned various tests.
The results are shown in Table 2.

[0076]

[Comparative Example 8 and Examples 4 to 6] EPDM shown in Table 2
100 parts by weight of composition, 0.5 parts by weight of sulfur, 70 parts by weight of carbon black [N550], 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, 40 parts by weight of paraffinic process oil, and vulcanized. 3.0 parts by weight of accelerator (1), 1.5 parts by weight of vulcanization accelerator (2), and 0.75 parts by weight of vulcanization accelerator (3) were added to a Banbury mixer having a capacity of 4.3 liters. Kobe Steel Co., Ltd.].

From the kneaded product thus obtained, test pieces for the above-mentioned various tests were prepared and subjected to the above-mentioned various tests.
The results are shown in Table 2.

[0078]

[Table 2]

From Table 2, the following can be understood. Comparative Example 5 is an example of the NR / SBR material that is currently used, and this material has poor heat resistance and therefore has particularly poor fatigue resistance after heat aging.

In Comparative Example 6, EP having a low intrinsic viscosity [η] was used.
Since DM is used, fatigue resistance is poor. In Comparative Example 7, the workability was so poor that it could not be commercialized, and it could not be evaluated.

In Comparative Example 8, the processability was good due to the presence of the low molecular weight component (liquid ethylene / propylene copolymer), but the blend ratio of EPDM and liquid ethylene / propylene copolymer was 1: 1. In addition, when the ratio of the low molecular weight component is large, tan δ becomes too high, and the vibration damping characteristics and fatigue resistance of the center bearing deteriorate.

According to Examples 4 to 6, the rubber composition of the present invention has excellent processability, and the amount of settling after the thermal settling test is significantly smaller than that of Comparative Example 5. [Examples and Comparative Examples of Rubber Composition for Rack Mount Insulator]

[0083]

Comparative Example 9 70 parts by weight of natural rubber (NR) [RSS No. 1], 30 parts by weight of styrene-butadiene rubber (SBR) [Nihon Zeon Co., Ltd., trade name: Nipol 1502], and sulfur 1.5 Parts by weight and carbon black [N
550] 60 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, aroma process oil 25 parts by weight, vulcanization accelerator (1) 1.5 parts by weight, vulcanization accelerator (3 ) 0.3 parts by weight and 5 parts by weight of antioxidants,
The mixture was kneaded with a Banbury mixer (manufactured by Kobe Steel, Ltd.) having a capacity of 4.3 liters.

From the kneaded product thus obtained, test pieces for the above-mentioned vulcanized rubber hardness test, Gehman low temperature twist test and product durability test were prepared and tested. The results are shown in Table 3.

[0085]

Comparative Examples 10 to 13 100 parts by weight of EPDM shown in Table 3, 0.5 parts by weight of sulfur, and carbon black [N5
50] The amount shown in Table 3, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, the amount shown in Table 3 of paraffinic process oil, and 3.0 parts by weight of vulcanization accelerator (1), Vulcanization accelerator (3) 0.75 parts by weight and vulcanization accelerator (2) 1.5
The parts by weight were kneaded with a Banbury mixer with a capacity of 4.3 liters (manufactured by Kobe Steel, Ltd.).

From the kneaded product thus obtained, test pieces for the above-mentioned vulcanized rubber hardness test, Gehman low temperature twist test and product durability test were prepared and tested. The results are shown in Table 3.

In Comparative Example 12, the EPDM composition of the present invention was used as the raw material rubber and the amount of carbon black was set to 20 parts by weight. However, the kneading operation became impossible and the subsequent experiments could not be performed.

[0088]

Examples 7 to 8 100 parts by weight of the EPDM composition shown in Table 3, 0.5 parts by weight of sulfur and carbon black [N
550] The amount shown in Table 3, zinc oxide 5 parts by weight, stearic acid 1 part by weight, and paraffinic process oil No. 3
The amounts shown in the table, vulcanization accelerator (1) 3.0 parts by weight, vulcanization accelerator (3) 0.75 parts by weight, vulcanization accelerator (2) 1.
5 parts by weight were kneaded with a 4.3 liter Banbury mixer [Kobe Steel Co., Ltd.].

From the kneaded product thus obtained, test pieces for the above-mentioned vulcanized rubber hardness test, Gehman low temperature twist test and product durability test were prepared and tested. The results are shown in Table 3.

[0090]

Comparative Example 14 Natural Rubber (NR) [RSS No. 1] 50
Parts by weight and styrene-butadiene rubber (SBR) [manufactured by Nippon Zeon Co., Ltd., trade name: Nipol 1502] 50
Parts by weight, sulfur 1.5 parts by weight, carbon black [N550] 90 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, aroma-based process oil 20 parts by weight, and a vulcanization accelerator ( 1) 1.5 parts by weight, vulcanization accelerator (3) 0.2 parts by weight, and antioxidants 5 parts by weight,
The mixture was kneaded with a Banbury mixer (manufactured by Kobe Steel, Ltd.) having a capacity of 4.3 liters.

From the kneaded product thus obtained, test pieces for the above-mentioned vulcanized rubber hardness test, Gehman low temperature twist test and product durability test were prepared and tested. The results are shown in Table 3.

[0092]

COMPARATIVE EXAMPLE 15 100 parts by weight of EPDM shown in Table 3,
0.5 parts by weight of sulfur and carbon black [N550]
95 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, paraffinic process oil 50 parts by weight, vulcanization accelerator (1) 3.0 parts by weight, vulcanization accelerator (3) 0 ．
75 parts by weight and 1.5 parts by weight of the vulcanization accelerator (2),
The mixture was kneaded with a Banbury mixer (manufactured by Kobe Steel, Ltd.) having a capacity of 4.3 liters.

From the kneaded product thus obtained, test pieces for the above-mentioned vulcanized rubber hardness test, Gehman low temperature twist test and product durability test were prepared and tested. The results are shown in Table 3.

Comparative Example 15 is an example in which EPDM containing no liquid ethylene / propylene copolymer was used as the raw material rubber. In this case, the kneading operation was impossible and the subsequent experiments could not be performed.

[0095]

Comparative Example 16 and Examples 9 to 10 EP shown in Table 3
DM composition 100 parts by weight, sulfur 0.5 parts by weight, carbon black [N550] shown in Table 3, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, and vulcanization accelerator (1) 3.0 parts by weight, 0.75 parts by weight of the vulcanization accelerator (3) and 1.5 parts by weight of the vulcanization accelerator (2) were added to a 4.3 liter capacity Banbury mixer [Kobe Steel Works Ltd. ) Made]
Kneaded in.

From the kneaded material thus obtained, test pieces for the above-mentioned vulcanized rubber hardness test, Gehman low temperature twist test and product durability test were prepared and tested. The results are shown in Table 3.

[0097]

[Table 3]

[0098]

[Table 4]

From Table 3, the following can be understood. In Comparative Examples 9, 11 and 13, the rate of change of the static spring constant is large and the product durability is insufficient.

In Comparative Example 10, low temperature flexibility is insufficient. In Comparative Example 12, as described above, the kneading operation is impossible and cannot be put to practical use.

In contrast to the above Comparative Example, Examples 7 and 8 showed satisfactory performance in workability, low temperature flexibility and product durability. In Comparative Example 14, the change rate of the static spring constant is large and the product durability is insufficient.

In Comparative Example 15, as described above, the kneading operation is impossible and cannot be put to practical use. In Comparative Example 16, the workability is excellent, but the rate of change of the static spring constant is large and the product durability is insufficient.

In Example 9, the workability was excellent, and the product durability was significantly improved as compared with the prior art. In Example 10, workability and product durability were improved.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a state in which an automobile engine mount insulator manufactured in Examples and Comparative Examples is incorporated in an engine mount.

FIG. 2 is a plan view of the engine mount of FIG.

3 is a view of the engine mount A- in FIG.
FIG.

FIG. 4 is a schematic cross-sectional view showing a state where the automobile center bearing insulator manufactured in Examples and Comparative Examples is used for fastening a propeller shaft and a center bearing.

FIG. 5 is a schematic perspective view showing an insulator of an automobile rack-and-pinion steering device manufactured in Examples and Comparative Examples.

FIG. 6 is a front view of the insulator of FIG.

FIG. 7 is a schematic cross-sectional view showing a state of a durability test of the insulator shown in FIGS. 5 and 6.

[Explanation of symbols]

 1 ... Engine mount 2 ... Engine mount insulator 3 ... Propeller shaft 4 ... Center bearing 5 ... Center bearing insulator 6 ... Rack mount insulator 7, 8 ... Jig

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0067

[Correction method] Change

[Correction content]

[0067]

[Table 1]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0078

[Correction method] Change

[Correction content]

[0078]

[Table 2]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0087

[Correction method] Change

[Correction content]

In Comparative Example 12, EPDM (A) of the present invention was used as the raw material rubber, and the amount of carbon black was set to 20 parts by weight, but the kneading operation became impossible and the subsequent experiments could not be conducted. .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0097

[Correction method] Change

[Correction content]

[0097]

[Table 3]

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0098

[Correction method] Change

[Correction content]

[0098]

[Table 4]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Norihiro Harada 330 Naganuma-cho, Inage-ku, Chiba-shi, Chiba Kinugawa Rubber Industry Co., Ltd. (72) Hiroshi Toriyabe 330 Naganuma-cho, Inage-ku, Chiba, Chiba Kinugawa Rubber Industry Co., Ltd.

Claims (5)

[Claims] 1. [I] ethylene and α having 3 to 20 carbon atoms
-Consisting of olefin and non-conjugated diene, and the molar ratio of ethylene and α-olefin is 60/40 to 73/2
7, the molecular weight distribution (Mw / Mn) Q value determined by GPC method was less than 4, and the intrinsic viscosity [η] measured in decalin at 135 ° C. was 2.7 to 5.0 dl / g.
And the iodine value is 10 to 40, and the non-conjugated diene is 5-ethylidene-2-norbornene ethylene.α-
Olefin / non-conjugated diene copolymer rubber (A): 99-
60% by weight, and ethylene and α having 3 to 20 carbon atoms
-Olefin, and the molar ratio of ethylene and α-olefin is 50/50 to 7
Liquid ethylene / α-olefin copolymer (B) having a viscosity of 8/22 and an intrinsic viscosity [η] measured in decalin of 135 ° C. of 0.2 to 0.4 dl / g: 1 to 40% by weight A rubber composition comprising an ethylene / α-olefin / non-conjugated diene copolymer rubber composition as a main component, which has a loss tangent (tan) determined by a dynamic viscoelasticity test after vulcanization.
δ) is 0.15 to 0.35, a rubber composition for a heat and vibration resistant rubber. 2. Sulfur [II] 0.1 to 10 parts by weight, and carbon black [III] 40 to 100 parts by weight of the ethylene / α-olefin / non-conjugated diene copolymer rubber composition [I]. The rubber composition for a heat and vibration resistant rubber according to claim 1, wherein the rubber composition comprises 100 to 120 parts by weight. 3. The rubber composition for a heat and vibration resistant rubber according to claim 1 or 2, wherein the rubber composition for a heat and vibration resistant rubber is a rubber composition for an automobile engine mount insulator. 4. The rubber composition for a heat and vibration resistant rubber according to claim 1, wherein the rubber composition for a heat and vibration resistant rubber is a rubber composition for an automobile center bearing insulator. 5. The rubber composition for heat and vibration resistant rubber as claimed in claim 1 or 2, wherein the rubber composition for heat and vibration resistant rubber is a rubber composition for an insulator of an automobile rack and pinion type steering device. Composition.