JP2003292703A - Rubber composition for anti-vibration rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for an anti-vibration rubber comprising an ethylene-α-olefin-non-conjugated diene copolymer rubber as a main component, having excellent heat resistance and durability and low dynamic magnification. . SOLUTION: The following conditions (a) to (c) are satisfied.
The nitrogen adsorption specific surface area is 15 to 30 m ² / g and the dibutyl phthalate adsorption amount is 10 per 100 parts by weight of one or more kinds of ethylene-α-olefin-nonconjugated diene copolymers
A rubber composition for an anti-vibration rubber comprising 0 to 140 ml / 100 g or less of carbon black, and an anti-vibration rubber obtained by vulcanizing the rubber composition. (A): The weight ratio of ethylene / α-olefin is 80/2.
0-40 / 60 (b): Mooney viscosity (ML _{1 + 4} 121 ° C.) is 100
(C) The content of the non-conjugated diene is 8 to 36 in iodine value.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ethylene-α-olefin-nonconjugated diene copolymer rubber composition. More specifically, the present invention is excellent in heat resistance and durability, and has a small dynamic ratio.
The present invention relates to an olefin-non-conjugated diene copolymer rubber composition. The rubber composition of the present invention can be optimally used as a vibration-proof rubber for automobiles and industrial equipment such as engine mounts, muffler hangers, strut mounts, and the like.

[0002]

2. Description of the Related Art Generally, a wide variety of anti-vibration rubbers are used to prevent noise and vibration in transportation means such as automobiles and motorcycles, as well as in industrial machines, OA equipment, household electric appliances and the like. Particularly in the field of automobiles, in recent years, as the engine performance is improved, the bonnet is reduced, and noise regulation measures are taken, there is an increasing demand for anti-vibration rubber that is excellent in heat resistance and durability and can prevent noise and vibration.

The properties that such a vibration-proof rubber should have are excellent heat resistance. Excellent durability against repeated external force over a long period of time. Low dynamic ratio (dynamic elastic modulus / static elastic modulus) to prevent noise and vibration during high-speed driving. And so on.

Here, the dynamic magnification is the degree of change of the elastic modulus (dynamic elastic modulus) at the time of vibration input in a high frequency range, and is represented by the ratio of the dynamic elastic modulus to the static elastic modulus. is there. For the purpose of vibration isolation, a low dynamic magnification is required.

In addition, it is important that static rubber characteristics such as tensile strength and compression set are not inferior to those of ordinary rubber.

As conventional vibration-proof rubber, natural rubber (NR) and styrene-butadiene copolymer rubber (S) are mainly used.
Highly unsaturated rubber such as BR) is used. that is,
This is because highly unsaturated rubbers such as NR and SBR have the advantage that they are superior in durability and dynamic ratio to low unsaturated rubbers. On the other hand, these unsaturated rubbers are, for example, ethylene-α- It is known that it is inferior in heat resistance as compared with a low unsaturated rubber such as an olefin-non-conjugated diene copolymer rubber, and therefore, the use of a high unsaturated rubber tends to be limited to a relatively low temperature. (See, for example, Patent Document 1).

On the other hand, low unsaturated rubbers such as ethylene-α-olefin-non-conjugated diene copolymer rubbers show excellent heat resistance, but have a drawback that they are inferior in durability against repeated external force for a long period of time. In order to improve the durability of the ethylene-α-olefin-non-conjugated diene copolymer rubber, a higher molecular weight ethylene-α-olefin-non-conjugated diene copolymer rubber is used. Increase the ethylene content in the rubber. The structure of carbon black used in the rubber composition is increased to enhance the reinforcing property. Etc. are generally well known.

The Mooney viscosity (here, the measured value of ML _{1 + 4} 121 ° C. is used) is generally used as an index of the molecular weight, but in applications requiring durability, the Mooney viscosity is 100 or more. It has been known that ethylene-α-olefin-non-conjugated diene copolymer rubbers have been used. However, it was still insufficient in terms of durability as compared with the highly unsaturated rubber.

Therefore, when an ethylene-α-olefin-non-conjugated diene copolymer rubber having a high molecular weight and a high ethylene content is used, a specific example thereof is that the weight ratio of ethylene / α-olefin in the rubber component is 85. / 15 or more. However, when such an ethylene-α-olefin-non-conjugated diene copolymer rubber having a high ethylene content is blended, the durability is improved, but the cold resistance of the rubber composition is extremely deteriorated, so that the dynamic ratio is increased. The temperature dependence of No. 1 became significantly large, and there was a problem that the vibration isolation performance at room temperature could not be exhibited in winter or in cold regions.

It is well known from the viewpoint of compounding that the structure of the carbon black used is increased to improve the durability, but in this case, the dynamic elastic modulus of the rubber composition is static. There is a drawback that the dynamic magnification becomes higher because the dynamic elastic modulus becomes higher than the increase.

[0011]

[Patent Document 1] Japanese Patent Laid-Open No. 3-227343 (second
page)

[0012]

Under these circumstances, the problem to be solved by the present invention is to use ethylene-α-olefin-non-conjugated diene copolymer rubber as a main component,
The purpose of the present invention is to provide a rubber composition for anti-vibration rubber which has excellent durability and low dynamic ratio.

[0013]

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems. That is, the first invention of the present invention is the following condition (a)
~ One or more ethylene-α-satisfying (c)
Rubber for anti-vibration rubber obtained by blending 100 parts by weight of olefin-non-conjugated diene copolymer with carbon black having a nitrogen adsorption specific surface area of 15 to 30 m ² / g and an adsorption amount of dibutyl phthalate of 100 to 140 ml / 100 g. It relates to the composition. (A): The weight ratio of ethylene / α-olefin is 80/2.
0 to 40/60 (b): Mooney viscosity (ML _{1 + 4} 121 ° C.) is 100
As described above, (c) the content of the non-conjugated diene is 8 to 36 in terms of iodine value, and the second invention of the present invention relates to an anti-vibration rubber obtained by vulcanizing the above rubber composition. Is. Furthermore, the third invention of the present invention relates to an engine mount or a muffler manger using the above-mentioned vibration-proof rubber.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the α-olefin of the ethylene-α-olefin-non-conjugated diene copolymer include:
Examples thereof include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene, and among them, propylene and 1-butene are preferable.

The ethylene / α-olefin / non-conjugated diene copolymer has a weight ratio of ethylene / α-olefin of 80.
/ 20 to 40/60, preferably 65/35 to 4
It is 5/55. If the ethylene ratio is too high, the cold resistance of the rubber composition will be extremely deteriorated, and the temperature dependence of the dynamic ratio will be remarkably large, and the vibration isolation performance at room temperature will not be exhibited in winter or cold regions It will be On the other hand, if the ethylene ratio is too small, the durability will be poor and it will be unsuitable.

The ethylene-α-olefin-non-conjugated diene copolymer has a Mooney viscosity (ML _{1 + 4} 121 ° C.) of 100.
That is all. If the Mooney viscosity is less than 100, the durability is extremely poor and it is unsuitable.

The term "diene" in the non-conjugated dienes of the present invention is a term that includes polyenes of triene and higher in addition to diene, such as 1,4-hexadiene and 1,6-.
Octadiene, 2-methyl-1,5-hexadiene, 6
-Methyl-1,5-heptadiene, 7-methyl-1,6
-Chain non-conjugated dienes such as octadiene; cyclohexadiene, dicyclopentadiene, methyltetraindene, 5-vinylnorbornene, 5-ethylidene-2
-Norbornene, cyclic non-conjugated dienes such as 6-chloromethyl-5-isopropenyl-2-norbornene; 2,
3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2
-Propenyl-2,2-norbornadiene, 1,3,7
Examples thereof include trienes such as -octatriene and 1,4,9-decatriene, which may be used alone or in combination of two or more. In addition, 5-ethylidene-2-norbornene and / or dicyclopentadiene are preferable. Furthermore, 5-vinyl-2-norbornene,
5- (2-propenyl) -2-norbornene, 5- (3
-Butenyl) -2-norbornene, 5- (4-pentenyl) -2-norbornene, 5- (5-hexenyl) -2
-Norbornene, 5- (5-heptenyl) -2-norbornene, 5- (7-octenyl) -2-norbornene,
5-methylene-2-norbornene, 6,10-dimethyl-1,5,9-undecatriene, 5,9-dimethyl-
1,4,8-decatriene, 4-ethylidene-8-methyl-1,7-nonadiene, 13-ethyl-9-methyl-
1,9,12-pentadecatriene, 5,9,13-trimethyl-1,4,8,12-tetradecadiene, 8,
Examples are 14,16-trimethyl-1,7,14-hexadecatriene and 4-ethylidene-12-methyl-1,11-pentadecadiene.

The content of the non-conjugated diene in the ethylene-α-olefin-non-conjugated diene copolymer is 8 to 10 in terms of iodine value.
36, preferably 10-30. If the iodine value is too small, sufficient crosslink density cannot be obtained, resulting in poor durability and unsuitability. On the other hand, if the iodine value is too large, the dynamic ratio becomes high, which is inappropriate.

As the rubber component used in the present invention, the above-mentioned ethylene-α-olefin-non-conjugated diene copolymer may be used alone or by blending two or more kinds thereof with the above ethylene / α-olefin ratio and Mooney. Those having a viscosity and a non-conjugated diene content are used. An oil-extended rubber containing an extender oil may be used as the ethylene-α-olefin-non-conjugated diene copolymer of the present invention.

The carbon black used in the present invention has a nitrogen adsorption specific surface area of 15 to 30 m ² / g and an adsorption amount of dibutyl phthalate of 100 to less than 140 ml / 100 g. The nitrogen adsorption specific surface area is an index of the particle size of carbon black, and the smaller the value, the larger the particle size. The amount of dibutyl phthalate adsorbed is an index of the structure chain of carbon black. The structure indicates the degree of connection of particles generated by the entanglement of particles, and the larger the value, the longer the connection of particles. If the nitrogen adsorption specific surface area is too large, the dynamic magnification becomes high, which is inappropriate. On the other hand, if the nitrogen adsorption specific surface area is too small, the durability is poor and it is inappropriate. On the other hand, if the amount of adsorbed dibutyl phthalate is too large, the dynamic ratio becomes high, which is unsuitable. On the contrary, if the amount of adsorbed dibutyl phthalate is too small, the durability is poor and it is inappropriate.

The amount of carbon black used in the present invention is 20 to 150 parts by weight, preferably 30 to 1 part.
It is 00 parts by weight. If the blending amount of carbon black is less than 20 parts by weight, the durability may be insufficient, while if the blending amount of carbon black exceeds 150 parts by weight, the dynamic ratio may be insufficient.

The vulcanized rubber obtained by vulcanizing the rubber composition of the present invention is optimally used as a vibration isolating rubber for engine mounts, muffler hangers and the like.

If desired, various additives such as plasticizers, vulcanizing agents, vulcanization accelerators, vulcanization aids, fillers, and resins such as polyethylene and polypropylene are added to the rubber composition of the present invention. Be compounded. As the plasticizer, a plasticizer usually used for rubber is used, and examples thereof include process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum, coal tar pitch, castor oil, linseed oil, sub, Beeswax, ricinoleic acid, palmitic acid,
Examples thereof include barium stearate, calcium stearate, zinc laurate, atactic polypropylene and coumarone indene resin. Among them, process oil is particularly preferably used. These plasticizers are ethylene-α-olefin-non-conjugated diene copolymers 10
20 to 150 parts by weight, preferably 30 to 0 parts by weight
~ 100 parts by weight are used. By using the plasticizer in such a range, a rubber composition having desired softness can be obtained.

As the vulcanizing agent used in the present invention, sulfur, sulfur chloride, sulfur dichloride, 4,4'-dithiodimorpholine, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide,
Selenium dimethyldithiocarbamate, dicumyl peroxide, 2,5-dimethyl-2,5-di (tertiary butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl −
2,5- (tert-butylperoxy) hexyne-3, di-tert-butyl peroxide, di-tert-butyl peroxide-
Examples thereof include organic peroxides such as 3,3,5-trimethylcyclohexane and tert-butyl hydroperoxide. In particular, sulfur, dicumyl peroxide, ditertiary butyl peroxide, ditertiary butyl peroxide-3,
3,5-trimethylcyclohexane is preferred.

Sulfur is usually 0.1 per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer.
It is used in a proportion of from 10 to 10 parts by weight, preferably from 0.5 to 5 parts by weight. The organic peroxide is usually ethylene-α.
It is used in an amount of 0.1 to 15 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the olefin-non-conjugated diene copolymer.

If necessary, a vulcanization accelerator and a vulcanization aid are used together with the vulcanizing agent. As a vulcanization accelerator, N
-Cyclohexyl-2-benzothiazole-sulfenamide, N-oxydiethylene-2-benzothiazole-sulfenamide, N, N-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) ) Mercaptobenzothiazole, 2- (2,6-diethyl-4)
-Morpholinothio) benzothiazole, dibenzothiazyl-disulfide, diphenyl guanidine, triphenyl guanidine, diorthotolyl guanidine, orthotolyl-by-guanide, diphenyl guanidine-phthalate, acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate , Hexamethylenetetramine,
Acetaldehyde ammonia, 2-mercaptoimidazoline, thiocarbanilide, diethyl thiourea, dibutyl thiourea, trimethyl thiourea, diorsotolyl thiourea, tetramethyl thiuram monosulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetra Butyl thiuram disulfide,
Dipentamethylene thiuram tetrasulfide, zinc dimethyldithiocarbamate, zinc diethylthiocarbamate, zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, dimethyldithiocarbamate Examples thereof include selenium acid, tellurium diethyldithiocarbamate, zinc dibutylxanthate, and ethylenethiourea. These vulcanization accelerators are used in a proportion 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-nonconjugated diene copolymer.

Examples of the vulcanization aid include metal oxides such as magnesium oxide and zinc oxide, but zinc oxide is preferably used. Usually, these vulcanization aids are used in an amount of 3 to 20 parts by weight based on 100 parts by weight of the ethylene-α-olefin-nonconjugated diene copolymer.

In crosslinking with a peroxide, sulfur, a quinone dioxime such as P-quinone dioxime,
A crosslinking aid such as polyethylene glycol dimethacrylate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, ethylene dimethacrylate or divinylbenzene may be used.

The filler used in the present invention is SR
F, GPF, FEF, HAF, ISAF, SAF, F
Inorganic fillers such as carbon black commonly used in rubbers such as T and MT, finely divided silicic acid, calcium carbonate, talc, and clay are preferably used.

Further, as the rubber component of the rubber vulcanizate, other kinds of rubber may be mixed and used with the ethylene-α-olefin-non-conjugated diene copolymer of the present invention.

To obtain a vulcanized rubber composition using the rubber composition of the present invention, for example, ethylene-α-olefin-non-conjugated diene copolymer, carbon black and, if necessary, an antioxidant may be used. A vulcanizable rubber composition is obtained by mixing a vulcanization accelerator, a processing aid, a stearic acid, a filler, a plasticizer, a softening agent, etc. using an ordinary kneader such as a roll, Banbury, or a kneader. , Usually 120 ° C
Above, preferably about 1-6 at a temperature of 140 ℃ -220 ℃
It may be vulcanized in 0 minutes. For vulcanization, any of a hot press, an injection molding machine, a compression molding machine and the like can be applied.

The vulcanized rubber composition obtained from the rubber composition of the present invention can be processed as an engine mount or a muffler hanger by a conventional method, and these products have the characteristics as already described, and are extremely excellent. It is a thing.

[0033]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Comparative Examples 1 to 4 and Example 1 EPDM (ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber, ethylene / propylene weight) as ethylene-α-olefin-non-conjugated diene copolymer component Ratio 70/30, Mooney viscosity ML _{1 + 4} 1
21 ° C 60 (ML _{1 + 4} 1 after adding 40 PHR of extension oil)
21 ° C. 60), 5-ethylidene-2-norbornene content iodine value 10, 40 PHR oil extended product) 140 parts by weight, in addition to the compounds described in the column of “added compound” in Table 1,
Zinc oxide 2 kinds 5 parts by weight, stearic acid 1 part by weight and Diana PW90 (paraffin oil from Idemitsu Kosan Co., Ltd.) 2
The starting temperature was adjusted to 80 ° C. by adding 0 part by weight 17
Using a 00 ml Banbury mixer, kneading was carried out for 5 minutes at a rotor rotation speed of 60 rpm. Then, using an 8-inch open roll, 8 parts by weight of Perkmill D (40) (dicumyl peroxide (40% product) manufactured by NOF CORPORATION) and 2 parts by weight of Acryester ED (ethylene glycol dimethacrylate manufactured by Mitsubishi Rayon Co., Ltd.) Was added and kneaded to obtain a rubber composition. Next, the rubber composition was treated at 170 ° C. × 15
Press vulcanization was carried out for a minute to obtain a vulcanized rubber composition. For the evaluation of the vulcanized rubber composition, the dynamic magnification and the durability were evaluated. The dynamic magnification (dynamic elastic modulus / static elastic modulus) was measured as follows. J
The value obtained by multiplying the static shear elastic modulus measured according to IS K 6254 by 3 was taken as the static elastic modulus. The dynamic elastic modulus was measured at a temperature of 23
It was measured at a vibration frequency of 100 Hz and an amplitude of ± 0.1%. The dynamic magnification was expressed as the ratio of the static elastic modulus and the dynamic elastic modulus measured under the temperature condition of 23 ° C. (dynamic elastic modulus / static elastic modulus). For the durability, a constant load fatigue tester NRF-08S (manufactured by Yoshimizu Co., Ltd.) was used, and a dumbbell-shaped type 3 test piece described in JIS K 6251 was used in an atmosphere of 80 ° C. and a load value of 0.
It was repeatedly stretched at a frequency of 1 to 1.9 kg and a frequency of 300 cpm, and the number of times of stretching until breaking was measured. The evaluation results are shown in Table 1.

[0035]

[Table 1]

* 1 compound added CB1 carbon black nitrogen adsorption specific surface area 23 (m ² / g) dibutyl phthalate adsorption amount 137 (ml / 100g) CB2 carbon black nitrogen adsorption specific surface area 42 (m ² / g) dibutyl phthalate Adsorption amount 115 (ml / 100 g) -CB3 carbon black nitrogen adsorption specific surface area 16 (m ² / g) Dibutyl phthalate adsorption amount 90 (ml / 100 g) -CB4 carbon black nitrogen adsorption specific surface area 13 (m ² / g) Dibutyl phthalate Adsorption amount 30 (ml / 100 g) -CB5 carbon black nitrogen adsorption specific surface area 43 (m ² / g) Dibutyl phthalate adsorption amount 143 (ml / 100 g) -Amount of compound added: ethylene excluding extending oil-α-olefin- Per 100 parts by weight of the non-conjugated diene copolymer component Parts by weight

Example 1 satisfying the requirements of the present invention has good dynamic magnification and durability. On the other hand, in Comparative Example 1 in which the nitrogen adsorption specific surface area of carbon black is out of the specified range of the present invention, both the dynamic ratio and the durability are unsatisfactory.
Further, in Comparative Example 2 in which the oil absorption of dibutyl phthalate is out of the specified range of the present invention, the durability is unsatisfactory.
Further, in Comparative Example 3 and Comparative Example 4 in which the nitrogen adsorption specific surface area of carbon black and the dibutyl phthalate oil absorption amount are out of the specified ranges of the present invention, Comparative Example 3 is unsatisfactory in durability, and Comparative Example 4 is unsatisfactory in dynamic magnification. Is.

[0038]

As described above, according to the present invention, a rubber for an anti-vibration rubber containing an ethylene-α-olefin-non-conjugated diene copolymer rubber as a main component, having excellent heat resistance and durability and having a low dynamic ratio. A composition could be provided.

Claims (3)

[Claims] 1. A condition 1) which satisfies the following conditions (a) to (c):
Nitrogen adsorption specific surface area of 15 to 30 m ² / g and dibutyl phthalate adsorption amount of 10 with respect to 100 parts by weight of ethylene-α-olefin-non-conjugated diene copolymer of one kind or two or more kinds.
A rubber composition for anti-vibration rubber, which comprises 0 to 140 ml / less than 100 g of carbon black. (A): The weight ratio of ethylene / α-olefin is 80/2.
0 to 40/60 (b): Mooney viscosity (ML _{1 + 4} 121 ° C.) is 100
Above (c) The content of the non-conjugated diene is 8 to 36 in iodine value 2. An anti-vibration rubber obtained by vulcanizing the rubber composition according to claim 1. 3. An engine mount or muffler hanger using the vibration-proof rubber according to claim 2.