JP2000344979A - High hardness vulcanized rubber composition - Google Patents

Abstract

(57) [Problem] To provide a high hardness vulcanized rubber composition having excellent processability, high hardness, low rigidity temperature dependency, and excellent sealing properties. A high hardness vulcanized rubber composition obtained by vulcanizing a rubber composition containing a reinforcing agent such as carbon black, a softening agent such as paraffinic oil, and a vulcanizing agent such as sulfur, JIS A EPD with hardness of 65 to 80
A high hardness vulcanized rubber composition is obtained in which vulcanized rubber particles composed of a diene rubber such as modified acrylonitrile / butadiene rubber are dispersed in an ethylene / α-olefin / diene vulcanized rubber phase such as M. In particular, it is more preferable to use an ethylene / α-olefin / diene rubber having an iodine value of 25 or less, more preferably 20 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for producing a high-strength and softening agent which has good workability, is sufficiently cured with a small amount of sulfur, has high hardness, has required physical properties, and has a high level of reinforcer and softener. The present invention relates to a high-hardness vulcanized rubber composition (hereinafter, referred to as “high-hardness rubber”) having a small temperature dependency of rigidity, a small compression set, and excellent sealing properties. The high hardness rubber of the present invention can be used in a wide range of applications such as automobile parts, industrial parts, building materials, and the like.

[0002]

2. Description of the Related Art A technique for obtaining a high hardness rubber by blending an ethylene / α-olefin rubber and a diene rubber has been known. For example, number average molecular weight 700-4
000 liquid diene rubber and a large amount of sulfur have been proposed (JP-B 2-1).
9854, JP-A-62-135552, U.S. Pat. No. 4,708,992). Further, a high-hardness rubber comprising ethylene / α-olefin rubber, solid diene rubber and a large amount of sulfur is also known (Japanese Patent No. 2773194). However, in these high-hardness rubbers, the use of a large amount of sulfur greatly reduces the elongation, and in any of the examples, the elongation is 220% or less, which is a problem in practical use.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a vulcanized rubber having good processability and sufficient hardness with a small amount of sulfur. An object of the present invention is to provide a high-hardness rubber which is excellent in physical properties such as tensile strength and elongation, has small temperature dependence of rigidity, and has a small compression set, and thus has excellent sealing properties.

[0004]

SUMMARY OF THE INVENTION The high hardness rubber of the present invention comprises:
A vulcanized ethylene / α-olefin / diene-based vulcanized rubber phase appropriately vulcanized to such an extent that the required physical properties are not impaired. Rubber particles are dispersed and contained, and have excellent processability and sufficient hardness. The present invention has been made based on the finding that the balance of the vulcanization densities of an ethylene / α-olefin / diene-based rubber and a diene-based rubber is important for obtaining such a high hardness rubber. is there.

[0005] The high-hardness rubber of the first invention is ethylene-α-
An olefin / diene rubber (a), a rubber composition (c) containing a diene rubber (b) having a solubility parameter difference of 1.5 or more from the rubber (a), a reinforcing agent, a softener, and sulfur A vulcanized high-hardness rubber (C) comprising an ethylene / α-olefin / diene-based vulcanized rubber phase (A),
It is characterized in that vulcanized rubber particles (B) composed of a diene rubber are dispersed and satisfy the above conditions.

The rubber (a) and the rubber (b) have a solubility parameter [hereinafter referred to as “SP value”. This SP value can be obtained from the Japan Adhesion Society, vol. 22, p. 566 (1986), "F
edors method ". ] Are used in combination. This SP value is usually larger in rubber (b), and the vulcanization accelerator having polarity tends to be unevenly distributed in rubber (b), and vulcanized rubber particles (B) having high hardness can be easily generated. . If the difference in SP value is less than 1.5, the vulcanized rubber phase (A) is appropriately vulcanized, but the vulcanized rubber particles (B) are insufficiently vulcanized, and the high hardness rubber (C) ) Hardness is reduced.

The rubber (b) having a SP value difference of 1.5 or more with respect to the rubber (a) is modified by copolymerization of a specific monomer described below, has a low conjugated diene content, and has a vulcanization reaction. Α, β-unsaturated nitrile / conjugated diene rubbers whose properties are adjusted are preferred. Even if the rubbers have the same SP value, when the conjugated diene content is high, the conjugated diene consumes a large amount of sulfur, so that the rubber (a) is not sufficiently vulcanized and the high hardness rubber is used. There is a problem that physical properties such as tensile strength of (C) are reduced.

The amount ratio of rubber (a) to rubber (b) is 3 to 100 parts by weight of rubber (a) (hereinafter, “parts” are all parts by weight). 40 parts. The rubber (b) is preferably 5 to 40 parts, more preferably 8 to 20 parts. When the compounding amount of the rubber (b) is less than 3 parts, even if the hardness of the vulcanized rubber particles (B) is sufficiently large,
The hardness of the high hardness rubber (C) becomes insufficient. On the other hand, if it exceeds 40 parts, the compression set of the high-hardness rubber (C) becomes large, the sealability is impaired, and the tensile strength and the like also decrease.

In the high hardness rubber of the first invention, the JIS A hardness of the vulcanized rubber phase (A) is 65 to 80, and the JIS A hardness of the high hardness rubber (C) is
3 or more larger than the JIS A hardness. When the hardness of the vulcanized rubber phase (A) and the hardness of the high-hardness rubber (C) are respectively within the above ranges, the high-hardness rubber has sufficient hardness and is similar to the case where an olefin resin is compounded. In addition, there is no problem that the temperature dependence of the rigidity is large, the compression set is large, and the sealing performance is poor.

The vulcanized rubber phase (A) has a JIS A hardness of 6
If it is less than 5, high hardness rubber (C) having a predetermined hardness
Can not be. On the other hand, when the hardness of the vulcanized rubber phase (A) exceeds 80, the JIS A
The hardness exceeds the upper limit and becomes too large. Further, the JIS A hardness of the high hardness rubber (C) is preferably at least 3 and more preferably 5 to 15 over the JIS A hardness of the vulcanized rubber phase (A). High hardness rubber (C) having excellent characteristics.

Further, JIS D of the vulcanized rubber particles (B)
The hardness is preferably 40 or more as in the second invention. If the hardness is less than 40, the vulcanized rubber phase (A)
JIS A of high hardness rubber (C) even if the hardness of
Hardness may not be high enough. Further, the JIS A hardness of the high hardness rubber (C) is higher than that of the vulcanized rubber phase (A).
The hardness is not more than 3 or more than the IS A hardness, and it may not be possible to obtain a high hardness rubber (C) having sufficient physical properties such as sufficient hardness and tensile strength.

The "ethylene / α-olefin / diene rubber (a)" is a rubber comprising ethylene, one or more α-olefins and a non-conjugated diene. As the α-olefin, propylene, 1-butene, 1-pentene, 1
-Hexene and the like. As the non-conjugated diene, dicyclopentadiene, ethylidene norbornene,
Examples thereof include 1,4-hexadiene, methyltetrahydroindene, and methylnorbornene. As the α-olefin and the non-conjugated diene, only one kind may be used, or two or more kinds may be used in combination. As the rubber (a), an ethylene / propylene / diene rubber is frequently used.

As the rubber (a), those having an iodine value of about 0 to 50 can be used. This iodine value is preferably 25 or less, particularly 15 to 20, as in the third invention. However, rubber (a) having a low iodine value generally has lower reactivity than rubber (b). Therefore, when these rubbers are mixed and vulcanized, the rubber (a) is not sufficiently vulcanized, and the tensile strength of the high hardness rubber (C) decreases. In order to reduce such a difference in the rate of the vulcanization reaction, a modified α, β-unsaturated nitrile / conjugated diene system in which a specific monomer described below is copolymerized to suppress the reactivity is used as the rubber (b). It is preferred to use rubber. The diene content of the rubber (a) having an iodine value specified in the third invention is usually 8% by weight [hereinafter, “%” indicates the case of the elongation and compression set of the high hardness rubber (C). All are by weight except for the above. ) Degree.

The "diene rubber (b)" is a rubber comprising a conjugated diene and another monomer. Examples of the conjugated diene include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene, and 1,3-butadiene and isoprene are particularly preferable. Examples of other monomers include α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, and styrene, and acrylonitrile is particularly preferred. Conjugated dienes and other monomers are
One kind may be used alone, or two or more kinds may be used in combination. This rubber (b) may be liquid or solid.

As the rubber (b), acrylonitrile
Α, such as butadiene rubber (hereinafter referred to as “NBR”);
β-unsaturated nitrile / conjugated diene rubbers and modified products thereof, and styrene / conjugated diene rubber modified products such as styrene / butadiene rubber (hereinafter, referred to as “SBR”) can be used.

As the rubber (b), as in the fourth invention, NBR, modified NBR and modified SBR are preferred, and modified NBR having a conjugated diene content as small as 10 to 50% is more preferred. The α, β-unsaturated nitrile contained in NBR and modified NBR contains 2
Preferably it is 0-45%. If the content of α, β-unsaturated nitrile is less than 20% or more than 45%, physical properties such as tensile strength of the high-hardness rubber (C) are reduced, and compression set may be increased. .

The modified NBR is used in combination particularly when the rubber (a) has a low iodine value. This modified NB
In R, the specific monomer copolymerized with the α, β-unsaturated nitrile and the conjugated diene is 1 to 60%, especially 5 to 60%.
It is preferably 60%, more preferably 10 to 60%. If the content of the monomer is less than 1%, the vulcanization of the modified NBR is prioritized, the rubber (a) is not sufficiently vulcanized, and the physical properties such as the tensile strength of the high hardness rubber (C) are reduced. . In addition, the compression set becomes large and the sealing property becomes insufficient. on the other hand,
When this content exceeds 60%, the rubber (b) is not sufficiently vulcanized, and the hardness of the high hardness rubber (C) tends to be insufficient.

Hereinafter, the compounding agent added to the rubber (a) and the rubber (b) will be described in detail. Examples of the above-mentioned "reinforcing agent" include carbon black, anhydrous silica, hydrated silica, surface-treated calcium carbonate, heavy calcium carbonate, calcium carbonate, magnesium carbonate, surface-treated clay, clay, and talc. Can also.
Carbon black is frequently used as a reinforcing agent, and can be selected from many types depending on the physical properties, application, and the like of the vulcanized rubber. The reinforcing agent is rubber (a) 10
60 to 200 parts can be blended and used for 0 part.

Examples of the "softening agent" include aromatic process oils, naphthene process oils, and paraffinic process oils. In consideration of the contamination of the high hardness rubber, a naphthenic process oil and a paraffinic process oil are preferred. Further, a plasticizer such as dioctyl phthalate or dioctyl sebacate can be used as the softener. The softener is rubber (a) 1
Up to about 100 parts can be blended and used with respect to 00 parts.

As the vulcanizing agent, the above-mentioned "sulfur" is used.
Both powdered sulfur and insoluble sulfur can be used. Further, a compound capable of releasing sulfur, such as 4,4'-dithio-bis-dimorpholine, may be used in combination.
The sulfur is mixed with a vulcanization accelerator such as thiurams, thiazoles and dithiocarbamates, and a vulcanization accelerator such as a metal oxide such as zinc white and a higher fatty acid such as stearic acid. In addition to these compounding agents, the rubber composition (c) includes a filler, an antioxidant, a plasticizer, a processing aid,
Antifoaming agents, anti-scorch agents, blowing agents, flame retardants, tackifiers, lubricants, pigments, and the like can be added in required amounts.

It is preferable that the amount of sulfur compounded as the vulcanizing agent is less than 4 parts based on 100 parts of the rubber (a) as in the sixth invention. This sulfur is 0.5 to 3 parts, especially 1
It is preferably from 2.5 to 2.5 parts, more preferably from 1 to 2 parts. If the compounding amount of sulfur is less than 0.5 part, the high hardness rubber (C)
Does not improve sufficiently. On the other hand, if it exceeds 4 parts, the elongation of the high-hardness rubber (C) decreases, the compression set increases, and the sealability decreases. In addition, this compounding amount of sulfur means an effective sulfur amount.

By vulcanizing the rubber composition (c),
High hardness rubber (C) is produced. This high hardness rubber (C)
Is composed of a vulcanized rubber phase (A) and vulcanized rubber particles (B) dispersed in the vulcanized rubber phase (A). The vulcanized rubber phase (A) comprises a vulcanized rubber obtained by vulcanizing the rubber (a),
And a reinforcing agent. The vulcanized rubber particles (B) include a vulcanized rubber obtained by vulcanizing the rubber (b), a reinforcing agent, and the like. The number average particle diameter of the vulcanized rubber particles (B) is 20 μm.
m or less, particularly preferably 5 μm or less. If the number average particle diameter exceeds 20 μm, the tensile strength, elongation, etc. of the high hardness rubber (C) may decrease.

The high hardness rubber (C) is, as in the seventh invention,
The tensile strength is 10 MPa or more, and the relationship between JIS A hardness (x) and elongation (y) satisfies the following expression (1). y ≧ −3.5x + 540 (1) The tensile strength of the high-hardness rubber (C) can be 10 to 17 MPa, particularly 12 MPa or more, and more preferably 13 MPa or more. Further, the hardness can be set as wide as 70 to 95.

Hereinafter, in the modified NBR, α, β
-The monomer having a specific functional group to be subjected to copolymerization with the unsaturated nitrile and the conjugated diene will be described in detail. (1) a monomer having an epoxy group; (meth) allyl glycidyl ether, glycidyl (meth) acrylate,
3,4-oxycyclohexyl (meth) acrylate and the like,

(2) a monomer having a carboxyl group; a) unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, tetraconic acid and cinnamic acid; b) phthalic acid and amber Free carboxyl group-containing esters such as monoesters of non-polymerizable polycarboxylic acids such as acid and adipic acid with hydroxyl group-containing unsaturated compounds such as (meth) allyl alcohol and 2-hydroxyethyl (meth) acrylate;

(3) Monomers having a hydroxyl group: a) 2-hydroxyethyl (meth) acrylate, 2-
Hydroxyalkyl (meth) acrylates such as hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate B) mono (meth) acrylates of polyalkylene glycol (the number of alkylene glycol units is, for example, 2 to 23) such as polyethylene glycol and polypropylene glycol;

C) N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N, N-bis (2-hydroxyethyl)
Hydroxyl-containing unsaturated amides such as (meth) acrylamide d) o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, o-hydroxy-α-methylstyrene, m-hydroxy-α-methylstyrene,
hydroxyl-containing vinyl aromatic compounds such as p-hydroxy-α-methylstyrene and p-vinylbenzyl alcohol; e) (meth) allyl alcohol;

(4) Monomers having an amino group: a) dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, 2- (di-n-propylamino) ethyl (meth) acrylate, 2-dimethylaminopropyl (meth) acrylate, 2-diethylaminopropyl (meth) acrylate, 2- (di-n-propylamino) propyl (meth) acrylate 3-dimethylaminopropyl (meth) acrylate, 3-diethylaminopropyl (meth) acrylate, 3- (di-
dialkylaminoalkyl (meth) acrylates such as n-propylamino) propyl (meth) acrylate;

B) N-dimethylaminomethyl (meth) acrylamide, N-diethylaminomethyl (meth) acrylamide, N- (2-dimethylaminoethyl) (meth) acrylamide, N- (2-diethylaminoethyl) (meth) acrylamide N- (2-dimethylaminopropyl) (meth) acrylamide, N- (2-diethylaminopropyl) (meth) acrylamide, N-
N-dialkylaminoalkyl group-containing unsaturated amides such as (3-dimethylaminopropyl) (meth) acrylamide, N- (3-diethylaminopropyl) (meth) acrylamide c) N, N-dimethyl-p-aminostyrene, N, N-
As such a monomer having an amino group, such as a tertiary amino group-containing vinyl aromatic compound such as diethyl-p-aminostyrene and vinylpyridine, a monomer having a tertiary amino group is particularly preferred.

(5) a monomer having a sulfonic acid group; a) 2- (meth) acrylamidoethanesulfonic acid;
-(Meth) acrylamidopropanesulfonic acid, 3-
(Meth) acrylamidopropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid,
(Meth) acrylamides such as 3- (meth) acrylamide-2-methylpropanesulfonic acid; b) ethyl 2-sulfonate (meth) acrylate;
(Meth) acrylates such as propyl sulfonic acid (meth) acrylate, propyl 3-sulfonic acid (meth) acrylate, and ethyl 1,1-dimethyl-2-sulfonate (meth) acrylate; c) p-vinylbenzene sulfonic acid; vinyl aromatic compounds such as p-isopropenyl benzene sulfonic acid,

(6) Monomers having a phosphate group: ethylene (meth) acrylate phosphate, trimethylene (meth) acrylate phosphate, tetramethylene (meth) acrylate phosphate, propylene (meth) acrylate phosphate, phosphoric acid Bis [ethylene (meth) acrylate], bis [trimethylene (meth) acrylate] phosphate, bis [tetramethylene (meth) acrylate] phosphate, diethylene glycol (meth) acrylate phosphate, triethylene glycol (meth) acrylate phosphate, Polyethylene glycol phosphate (meth) acrylate, bis [diethylene glycol (meth) acrylate] phosphate, bis [triethylene glycol (meth) acrylate] phosphate, bis [polyethylene glycol (meth) acrylate], etc.

(7) Monomers having a carboxylic acid ester group: a) Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso
-Propyl (meth) acrylate, n-butyl (meth)
Acrylate, iso-butyl (meth) acrylate,
sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth)
Alkyl (meth) acrylates such as acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate;

B) 2,2-trifluoroethyl (meth)
Acrylate, 3,3,3,2,2-pentafluoropropyl (meth) acrylate, 4,4,4,3,3
Fluoroalkyl (meth) acrylates such as 2,2-heptafluorobutyl (meth) acrylate;

C) 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-
Methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth)
Alkoxyalkyl (meth) acrylates such as acrylates; d) (meth) acrylates of alkoxypolyalkylene glycols (the number of alkylene glycol units is, for example, 2 to 23) such as methoxypolyethylene glycol, ethoxypolyethylene glycol, methoxypolypropylene glycol, and ethoxypolypropylene glycol Kind,

E) aryloxyalkyl (meth) acrylates such as 2-phenoxyethyl (meth) acrylate, 2-phenoxypropyl (meth) acrylate and 3-phenoxypropyl (meth) acrylate; f) phenoxy polyethylene glycol, phenoxy polypropylene Mono (meth) acrylates of aryloxypolyalkylene glycol (the number of alkylene glycol units is, for example, 2 to 23) such as glycol; g) 2-cyanoethyl (meth) acrylate, 2-cyanopropyl (meth) acrylate, 3- Cyanoalkyl (meth) acrylates such as cyanopropyl (meth) acrylate;

H) Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 3-chloro-
1,2-propanediol, 1,2-butanediol,
1,3-butanediol, 1,4-butanediol,
Mono- or di- (meth) acrylates of alkylene glycols such as 1,5-pentanediol and 1,6-hexanediol;

I) mono- or di- (meth) acrylates of polyalkylene glycol (for example, having 2 to 23 alkylene glycol units) such as polyethylene glycol and polypropylene glycol; j) glycerin, 1,2,4-butane Mono or oligo tri- or higher polyhydric alcohols such as triol, pentaerythritol, trimethylolalkane (alkane has 1 to 3 carbon atoms) and tetramethylolalkane (alkane has 1 to 3 carbon atoms). Meth) acrylates,

K) mono- or oligo- (meth) acrylates of the polyalkylene glycol adduct of the above-mentioned trihydric or higher polyhydric alcohol (alkylene glycol unit number is, for example, 2 to 23); 1) 4-cyclohexanediol; Mono- or oligo- (meth) acrylates of cyclic polyols such as 4-benzenediol, 1,4-di- (2-hydroxyethyl) benzene,

M) (Dialkylaminoalkoxy) alkyl (meth) acrylates such as 2- (dimethylaminoethoxy) ethyl (meth) acrylate and 2- (diethylaminoethoxy) ethyl (meth) acrylate; n) lactone-modified (meth) Acrylates and the like. Among these monomers having a carboxylic acid ester group, alkoxyalkyl (meth) acrylates having an alkoxyl group having 1 to 4 carbon atoms and alkyl (meth) acrylates having 2 to 6 carbon atoms are preferable, and 2 to 2 carbon atoms are preferable. 6 alkyl (meth) acrylates are particularly preferred. One of these various monomers (1) to (7) may be used alone, or two or more of them may be used in combination.

The rubber (a), the rubber (b) and the compounding agent can be mixed by the following method. The rubber (a) and compounding agents such as a reinforcing agent and a softening agent are kneaded by a closed kneader or a mixing roll or the like, and the obtained rubber composition is taken out from the kneader or the like. And kneading again with a closed kneader or mixing roll, without removing the rubber composition containing the rubber (a) kneaded with a closed kneader or mixing roll from the kneader or the like without removing the rubber composition. To continue the kneading,

The rubber (a) and the rubber (b) are preliminarily mixed by a closed kneader or a mixing roll.
A method in which a reinforcing agent and a softening agent are compounded and kneaded with a closed kneader or a mixing roll, etc. The rubber (b) is mixed with a compounding agent such as a reinforcing agent and a softening agent by a closed kneader or a mixing roll. , And the obtained rubber composition is taken out from a kneader or the like, and the rubber composition and the rubber (a) are kneaded again by a closed kneader or a mixing roll.

The sulfur can be mixed with the rubber (b) and kneaded. However, considering the scorch property of the rubber composition (c), after mixing the rubber (a) and the rubber (b), It is preferable to knead the rubber mixture at a relatively low temperature with a closed kneader or a mixing roll. Upon kneading, a reinforcing agent, a softening agent, and the like can be additionally compounded, and in addition, a vulcanizing agent, a vulcanization accelerator, a filler, a processing aid, a defoaming agent, and a vulcanizing agent generally used in a rubber composition. An anti-aging agent and the like can be additionally added.

The high hardness rubber (C) of the present invention is obtained by subjecting the rubber composition (c) to press vulcanization, can vulcanization, injection molding, hot air vulcanization, UHF vulcanization, LCM vulcanization and PCM vulcanization. , Or by combining these vulcanization methods, by continuous vulcanization.
The resulting high hardness rubber (C) can be used in a wide range of applications such as automobile parts, industrial parts, and building materials. More specifically, for example, used for sponges, packings, hoses, draining rubber, glass run rubber, weather strip, a hard solid rubber portion of a composite of soft solid rubber and hard solid rubber, a door seal, a trunk seal, etc. For example, there are applications of automobile parts such as a sponge rubber portion and a solid rubber portion of a composite of a sponge rubber and a solid rubber to be obtained, and mudguard. In addition, it can be used for industrial parts such as rubber rolls, sealing materials, packings, etc., and for building materials such as setting blocks, rubber tiles and gaskets.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples. The following were used as the rubber (a) and the rubber (b) and the compounding agents. The SP values were all calculated by the above-mentioned Fedors method. (1) Rubber (a) EPDM 1: ethylene / propylene / ethylidene norbornene copolymer rubber [Mooney viscosity (ML1 + 4 10
0, 105), ethylene content; 60.5%, ethylidene norbornene content; 4.5%, iodine value; 15, SP
8.49] EPDM 2: Ethylene / propylene / ethylidene norbornene copolymer rubber [Mooney viscosity (ML1 + 4 10
0 ° C.); 42, ethylene content; 56.5%, ethylidene norbornene content; 4.5%, iodine value; 15, SP
Value; 8.42]

(2) Rubber (b) NBR (NBR 1-3) having the composition shown in Table 1,
Modified NBR (NBR 4-8) and modified SBR (SBR 1
2) Table 1 also shows Mooney viscosity and SP value. Liquid PB: Nippon Oil Corporation, trade name "B300
0 "[number-average molecular weight; 3000, 1,2-vinyl bond amount;
70%, SP value: 8.46] SBR 3: Mooney viscosity (ML1 + 4 100 ° C.);
70, butadiene content; 63%, 1,2 vinyl bond amount;
50%, SP value: 9.26 (3) Other resins, etc. used in Comparative Examples TPO (thermoplastic olefin-based elastomer);
01-73 "

[0046]

[Table 1]

(4) Compounding agent 1) Reinforcing agent (carbon black) SRF carbon black; Asahi Carbon Co., Ltd., trade name "Asahi 50HG" FEF carbon black; Asahi Carbon Co., Ltd., trade name "Asahi 60" 2) Softener Paraffin oil; trade name "P" manufactured by Idemitsu Kosan Co., Ltd.
W380 "3) Filler heavy calcium carbonate; trade name" Super S "manufactured by Maruo Calcium Co., Ltd. 4) Dehydrating agent calcium oxide; trade name" Vesta PP "manufactured by Inoue Lime Co., Ltd.

5) Vulcanization accelerator: Tetramethylthiuram disulfide; manufactured by Ouchi Shinko Chemical Co., Ltd., trade name "Noxeller TT" N-cyclohexyl-2-benzothiazole sulfamide; manufactured by Ouchi Shinko Chemical Co., Ltd. Product name “NOXELLER CZ” Zinc dimethyl dithiocarbamate; manufactured by Ouchi Shinko Chemical Co., Ltd., product name “NOXELLER PZ”

6) Vulcanization Accelerator Auxiliary Zinc Flower; trade name "Zinc Flower 1" manufactured by Mitsui Kinzoku Mining Co., Ltd.
No. ”Stearic acid; manufactured by Kao Corporation 7) Vulcanizing agent Sulfur; manufactured by Tsurumi Chemical Co., Ltd. manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name“ Valnock R ”Rubber (a) and rubber (b) and compounding agents Table 2 (Comparative Examples 1 to 7) shows other compounding compositions of the rubber composition (c) consisting of
And Table 3 (Examples 1 to 7) and Table 4 (Examples 8 to 1)
See 4).

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

The Mooney test and Mooney scorch test of the rubber compositions of Comparative Examples 1 to 7 shown in Table 2 and Examples 1 to 7 shown in Table 3 and Examples 8 to 14 shown in Table 4 were conducted as follows. Performed by method. Further, these rubber compositions were hot-press vulcanized at 170 ° C. for 10 minutes (a sample for a compression set test was 15 minutes) to obtain a vulcanized rubber sheet having a thickness of 2 mm, and the physical properties were measured by the following methods. . The results are shown in Table 5 (Comparative Examples 1 to 7), Table 6 (Examples 1 to 7), and Table 7 (Examples 8 to 14).

(1) Mooney test and Mooney scorch test; JIS K 6300 (2) Tensile test; JIS K 6301 (3) Hardness test; JIS K 6253 [The hardness of the vulcanized rubber phase (a) is rubber This is the hardness of the vulcanized rubber when (b) is not added. ) (4) Aging test; JIS K 6301, measurement of change in hardness (A _H ) due to aging (5) Compression set test; JI
SK6301 (6) Temperature dependency test: Tensile tests were performed at 0 ° C. and 80 ° C., the elastic modulus at 30% elongation was measured, and the temperature dependency of rigidity was evaluated by a numerical value calculated by the following equation. Temperature dependence of rigidity (%) = [(elastic modulus at 30 ° elongation at 0 ° C.−elastic modulus at 30% elongation at 80 ° C.) /
Modulus at 30% elongation at 0 ° C.] × 100

[0055]

[Table 5]

[0056]

[Table 6]

[0057]

[Table 7]

According to the results in Table 5, in Comparative Example 1 where the amount ratio of NBR was too high, the hardness difference between the vulcanized rubber phase (A) and the high hardness rubber (C) was small, the tensile strength was low, and the temperature was low. It is inferred that it is inferior in dependence, easily aging, has a large compression set, and is inferior in sealing performance. In Comparative Example 2 in which the amount ratio of NBR is too low, there is no difference in hardness between the vulcanized rubber phase (A) and the high-hardness rubber (C), and a reinforcing agent, a softening agent, etc., having an excellent balance between hardness and workability. Cannot be blended at a high level.

Further, even in Comparative Example 3 in which the difference in SP value is small because the content of acrylonitrile in NBR is too small, there is no difference in hardness between the vulcanized rubber phase (A) and the high hardness rubber (C). It is not possible to use a highly filled blend of a reinforcing agent, a softening agent, etc., which has an excellent balance of workability. Comparative Example 4 in which the difference in SP value between the rubber (a) and the rubber (b) was small,
In Nos. 5 and 6, the elongation of the high hardness rubber (C) is greatly reduced. Furthermore, in Comparative Example 7 using a thermoplastic olefin-based elastomer, it is inferred that the compression set is large, the sealing property is inferior, and the temperature dependence of rigidity is also inferior.

On the other hand, according to the results in Tables 6 and 7, in Examples 1 to 14, workability, tensile strength, elongation, hardness,
It can be seen that a high-hardness rubber having excellent compression set and the like, small temperature dependency of rigidity, and having required performance has been obtained.

[0061]

According to the first aspect of the present invention, two types of rubber having different SP values are used at a predetermined quantitative ratio, and the vulcanization density of each rubber is adjusted to obtain a vulcanizate having a specific hardness. A high-hardness rubber in which vulcanized rubber particles having particularly high hardness are dispersed in the vulcanized rubber phase can be obtained, and a high-hardness rubber having small temperature dependence of rigidity and excellent sealing properties can be obtained. In particular, by using the specific rubber of the second to fifth inventions and using a specific amount of sulfur of the sixth invention, particularly excellent properties having a correlation between tensile strength and hardness and elongation of the seventh invention are obtained. High hardness rubber having

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hidetoshi Goto 2-11-24 Tsukiji, Chuo-ku, Tokyo FSR term in JSR Corporation (reference) 4J002 AC072 AC082 AC092 AE053 BB051 BB101 BB151 BC052 BG102 DA036 DA048 DE206 DE236 DJ016 DJ036 DJ046 EH147 FB006 FD016 FD023 FD027 FD148 GL00 GM00 GN00

Claims (7)

[Claims] 1. An ethylene / α-olefin / diene rubber (a), a diene rubber (b) having a solubility parameter difference of 1.5 or more from the rubber (a), a reinforcing agent, a softener and sulfur. A high-hardness vulcanized rubber composition (C) obtained by vulcanizing a rubber composition (c) to be contained, comprising a diene rubber in an ethylene / α-olefin / diene vulcanized rubber phase (A). A vulcanized rubber composition having high hardness, wherein the vulcanized rubber particles (B) are dispersed and satisfy the following conditions. 100 parts by weight of the rubber (a) and the rubber (b)
Is 3 to 40 parts by weight, and the JIS A hardness of the vulcanized rubber phase (A) is 65 to 8
0, The JIS A hardness of the high hardness vulcanized rubber composition (C) is 3 or more larger than the JIS A hardness of the vulcanized rubber phase (A). 2. JIS D of said vulcanized rubber particles (B)
The high hardness vulcanized rubber composition according to claim 1, having a hardness of 40 or more. 3. The high hardness vulcanized rubber composition according to claim 1, wherein the rubber (a) has an iodine value of 25 or less. 4. The rubber (b) comprises at least one of an α, β-unsaturated nitrile / conjugated diene rubber, a modified α, β-unsaturated nitrile / conjugated diene rubber and a modified styrene / conjugated diene rubber. The high hardness vulcanized rubber composition according to any one of claims 1 to 3, which is one kind. 5. The α, β-unsaturated nitrile / conjugated diene rubber and the modified α, β-unsaturated nitrile / conjugated diene rubber having an α, β-unsaturated nitrile content of 20 to 45.
The high-hardness vulcanized rubber composition according to claim 4, which is contained in a weight percent. 6. The high hardness vulcanized rubber composition according to claim 1, wherein the sulfur is less than 4 parts by weight based on 100 parts by weight of the rubber (a). 7. The method according to claim 1, wherein the tensile strength is 10 MPa or more, and the relationship between JIS A hardness (x) and elongation (y) satisfies the following expression (1). The high hardness vulcanized rubber composition according to the above. y ≧ −3.5x + 540 (1)