JPH10265626A - Rubber composition for sealing hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which exhibits very high efficiency of crosslinking by an organic peroxide, can be molded at high speed, and is excellent in heat resistance, by blending essential constituents comprising an ethylene/α-olefin/nonconjugated polyene copolymer rubber having a specified composition and specified properties and an organic peroxide. SOLUTION: The copolymer rubber (A) used as the essential constituent is obtained from ethylene, a 3-20C α-olefin, the molar ratio of ethylene to the α-olefin being (40:60) to (90:10), and nonconjugated polyene (s) comprising norbornene compound(s) represented by formula I (n is 0 to 10; R<1> is H or a 1-10C alkyl; and R<2> is H or a 1-5C alkyl) and/or formula II (R<3> is H or a 1-10C alkyl) and having an iodine value of 1 or more to less than 20 (g/100 g), and it has a Mooney viscosity at 100 deg.C of 10 to 120. The amount of an organic peroxide (B) blended as the essential constituent is 0.001-0.05 mol based on 100 pts.wt. component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a master cylinder of a hydraulic brake and a hydraulic clutch system for an automobile, a rubber cup in a wheel cylinder, a disk seal of a disk brake system, and the like. The present invention relates to a rubber composition for a hydraulic cylinder seal which is excellent in efficiency and can be molded at high speed.

[0002]

2. Description of the Related Art It has been known that styrene-butadiene rubber is mainly used as a sealing material for a hydraulic cylinder. However, in recent years, as the performance of automobiles has become higher, the temperature in the engine room tends to increase, and styrene-butadiene rubber is thermally degraded and cannot be said to be a preferable seal material. Therefore, instead of styrene / butadiene rubber, recently, ethylene / propylene / non-conjugated polyene copolymer rubber (hereinafter referred to as E
(Sometimes referred to as PDM or EPT).

[0003] Vulcanizates of ethylene / propylene / non-conjugated polyene copolymer rubbers are excellent in heat aging resistance, weather resistance, water resistance, chemical resistance, low-temperature properties and flexibility.
It is used for sealing parts such as household jar packing, sealing material at the joint between glass and sash, and sealing material for automotive window frames. In addition, it has recently been known to be used as a hydraulic cylinder seal material for a master cylinder of a vehicle hydraulic brake and hydraulic clutch system, a rubber cup in a wheel cylinder, and a disk brake of a disk brake system.

In order to improve the heat aging resistance of the ethylene / propylene copolymer rubber, organic peroxide crosslinking is generally performed. When organic peroxide is used, ethylene
Propylene copolymer rubber (hereinafter sometimes referred to as EPM or EPR) has low crosslinking efficiency and slow vulcanization. In order to increase the crosslinking efficiency, non-conjugated polyenes such as dicyclopentadiene (DCPD) and 5-ethylidene-2-
An ethylene / propylene / non-conjugated polyene copolymer rubber obtained by copolymerizing norbornene (ENB) is used.

[0005]

However, the demand for heat aging resistance is becoming more severe year by year, and the conventional ethylene / α-olefin / dicyclopentadiene copolymer rubber or ethylene / α-olefin / 5-ethylidene-2-norbornene When using a polymerized rubber, it is necessary to reduce the content of diene to be copolymerized in order to improve the heat aging resistance. on the other hand,
If the diene content is reduced, the desired crosslinking efficiency cannot be obtained.

Further, in the conventional ethylene / propylene / non-conjugated polyene copolymer rubber, the vulcanization time can be reduced in order to reduce the cost of the product, the secondary vulcanization step can be eliminated, or the compounded organic polymer can be reduced. Reducing the amount of oxide has not been achievable to ensure product performance.

Accordingly, there has been a strong demand in the art for a rubber composition for a hydraulic cylinder seal that can be molded at high speed and has excellent heat aging resistance and organic peroxide crosslinking efficiency.

The present invention is to improve the above-mentioned disadvantages in the prior art, that is, to use an ethylene / α-olefin / non-conjugated polyene copolymer rubber having a high crosslinking efficiency when crosslinked with an organic peroxide, and to improve the heat aging resistance. The object of the present invention is to obtain a rubber composition for a hydraulic cylinder seal which is excellent in organic peroxide crosslinking efficiency and can be molded at high speed.

[0009]

SUMMARY OF THE INVENTION A rubber composition for a hydraulic cylinder seal according to the present invention comprises ethylene and C3 to C2.
A rubber composition comprising a copolymer comprising an α-olefin of 0 and a non-conjugated polyene, [I] (1) a molar ratio of ethylene and an α-olefin having 3 to 20 carbon atoms in the copolymer. The ratio is in the range of 40/60 to 90/10, and (2) the non-conjugated polyene in the copolymer has the following general formula [A] and / or [B]

Embedded image [Wherein, n is an integer of 0 to 10, R ¹ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]

Embedded image Wherein R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. (3) The non-conjugated polyene in the copolymer has an iodine value of 1 (g / g (4) ethylene / α in which the Mooney viscosity at 100 ° C. of the copolymer is in the range of 10 to 120 and less than 20 (g / 100 g).
-An olefin / non-conjugated polyene copolymer rubber (A) and [I
[I] Organic peroxide (B) is characterized as being blended as an essential component.

In the rubber composition for a hydraulic cylinder seal according to the present invention, the compounding amount of the organically modified oxide (B) is based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A). It is characterized by being 0.001 to 0.05 mol with respect to.

The preferred rubber composition for hydraulic cylinder seals according to the present invention comprises [I] the above-mentioned ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) and [II] the above-mentioned ethylene / α- 0.001-0.05 mol of organic peroxide (B) per 100 parts by weight of olefin / non-conjugated polyene copolymer rubber (A), and [III] carbon black (C)
Are blended as essential components.

In the rubber composition for a hydraulic cylinder seal according to the present invention, 1. The arithmetic average particle diameter (d _av ) of the carbon black (C) is in the range of 20 to 50 millimicrons; The compounding amount of the carbon black (C) is ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) 1
2. 30 to 100 parts by weight with respect to 00 parts by weight; Further, the relationship between the arithmetic average particle diameter (d _av ) of the carbon black (C) and the compounding amount (X _CB ) with respect to 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) is as follows. It is preferable that 25 ≦ (d _av ) / (X _CB ) ≦ 1.0.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber composition of the present invention comprises an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A).
And an organic peroxide (B) or, furthermore, carbon black (C). The copolymer rubber that satisfies the conditions (1) to (4) at the same time is used. First, in the present invention, regarding the use as a hydraulic cylinder seal, the fact that the molar ratio of ethylene / α-olefin is in the range of the above (1) is basically from the viewpoint of elasticity, cushioning property, and low permanent set. is important. Further, as described in the above condition (2), it is also important to select a norbornene compound represented by the general formula [A] or [B] as the non-conjugated polyene constituting the copolymer rubber. That is, the copolymer rubber derived from the norbornene compound is remarkably excellent in the crosslinking efficiency of the organic peroxide crosslinking. Referring to Tables 3 and 4 described below, the copolymer rubber used in the present invention is a conventional ethylene / α-olefin / dicyclopentadiene copolymer rubber or ethylene / α-olefin / 5-
Compare the ethylidene-2-norbornene copolymer rubber with the iodine value at the same level to determine the crosslink density (effective network chain density).
The surprising fact that is almost doubled becomes apparent. For this reason, according to the present invention, vulcanization molding can be performed at high speed within a short time, and the iodine value of the copolymer rubber is reduced to a small value of 1 or more and less than 20 as described in the above condition (3). This makes it possible to significantly improve the heat aging resistance and reduce the cost of the copolymer rubber. Further, by setting the Mooney viscosity of the copolymer rubber in the range of the above condition (4), excellent physical properties and processability as a rubber can be obtained.
The crosslinked rubber formed from the copolymer rubber (A) and the organic peroxide (B) is excellent in normal physical properties such as tensile strength, elongation and hardness, heat aging resistance and compression set. It will be apparent from the following Tables 3 and 4 that the combination is excellent in combination with the liquid resistance.

The rubber composition for sealing a hydraulic cylinder according to the present invention will be specifically described below.

The rubber composition for a hydraulic cylinder seal according to the present invention comprises a specific ethylene / α-olefin / non-conjugated polyene copolymer rubber (A), a specific organic peroxide (B), and And carbon black (C).

First, these components will be described. Ethylene / α-olefin / non-conjugated polyene copolymer rubber
(A) The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention comprises ethylene, an α-olefin having 3 to 20 carbon atoms, and the following general formulas [I] and / or
Or [b]

Embedded image [Wherein, n is an integer of 0 to 10, R ¹ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]

Embedded image [Wherein R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms].

As the α-olefin having 3 to 20 carbon atoms, specifically, propylene, butene-1, 4
-Methylpentene-1, hexene-1, heptene-1,
Octene-1, nonene-1, decene-1, undecene
1, dodecene-1, tridecene-1, tetradecene-
1, pentadecene-1, hexadecene-1, heptadecene-1, nonadecene-1, eicosene-1, 9-methyl-decene-1, 11-methyl-dodecene-1, 12-ethyl-tetradecene-1, and the like. These α
-The olefin is used alone or in combination of two or more. Of these, propylene, butene-1, and octene-1 are particularly preferably used.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention has a molar ratio of ethylene to an α-olefin having 3 to 20 carbon atoms (ethylene / α-olefin). 40 / 60-90 / 10,
Preferably, it is 50/50 to 90/10, more preferably 55/45 to 85/15, and particularly preferably 60/40.
８０80/20.

In the above general formula [A], n is 0 to 10
Is an integer. In the above general formula [A],-(CH ₂ ) _n-
Represents, for example, a single bond (direct bond) or
10, especially 1 to 6 alkylene groups, and specific examples include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylidene (amylene) group, a hexylene group, an octylene group, a nonylene group, and a decylene group.

The group R ¹ of the non-conjugated polyene represented by the general formula [A] is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and specific examples of the alkyl group include a methyl group and an ethyl group. Group, n-propyl group, isopropyl group, n
-Butyl, isobutyl, t-butyl, n-pentyl, isopentyl, t-pentyl, neopentyl, hexyl, isohexyl, heptyl, octyl, nonyl, decyl and the like. Further, the group R ² in the general formula [A] is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and examples of the alkyl group of R ² include, among the alkyl groups exemplified as the above R ¹ , Those having 1 to 5 carbon atoms are exemplified.

Specific examples of the alkyl group of R ^{3 in} the above general formula [II] include the same alkyl groups as the specific examples of the alkyl group of R ¹ .

As the non-conjugated polyene represented by the general formula [I] or [II], specifically, 5-methylene-
2-norbornene, 5-vinyl-2-norbornene, 5
-(2-propenyl) -2-norbornene, 5-isopropenyl-2-norbornene, 5- (1-butenyl)-
2-norbornene, 5- (3-butenyl) -2-norbornene, 5- (1-methyl-2-propenyl) -2-norbornene, 5- (4-pentenyl) -2-norbornene, 5- (1-methyl -3-butenyl) -2-norbornene, 5- (1-hexenyl) -2-norbornene,
-(5-hexenyl) -2-norbornene, 5- (1-
Methyl-4-pentenyl) -2-norbornene, 5-
(2,3-dimethyl-3-butenyl) -2-norbornene, 5- (2-ethyl-3-butenyl) -2-norbornene, 5- (6-heptenyl) -2-norbornene,
-(3-methyl-5-hexenyl) -2-norbornene, 5- (3,4-dimethyl-4-pentenyl) -2-
Norbornene, 5- (3-ethyl-4-pentenyl),
5- (1-octenyl) -2-norbornene, 5- (7
-Octenyl) -2-norbornene, 5- (2-methyl-6-heptenyl) -2-norbornene, 5- (1,2
-Dimethyl-5-hexenyl) -2-norbornene, 5
-(5-ethyl-5-hexenyl) -2-norbornene, 5- (1,2,3-trimethyl-4-pentenyl)
-2-norbornene, 4-methyl-5-vinyl-2-norbornene, 4-ethyl-5-vinyl-2-norbornene and the like. Among them, 5-vinyl-2-
Norbornene, 5-methylene-2-norbornene, 5-
(2-propenyl) -2-norbornene, 5- (3-butenyl) -2-norbornene, 5- (4-pentenyl)
2-norbornene, 5- (5-hexenyl) -2-norbornene, 5- (6-heptenyl) -2-norbornene and 5- (7-octenyl) -2-norbornene are preferred.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention comprises, in addition to the non-conjugated polyene represented by the general formula [A] or [B],
It can be used by mixing with other non-conjugated polyenes as long as the desired physical properties are not impaired. Specifically, as other non-conjugated polyenes, 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,4 5
-Dimethyl-1,4-hexadiene, 7-methyl-1,
Chain non-conjugated dienes such as 6-octadiene, dicyclopentadiene, methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 5-
Vinylidene-2-norbornene, 6-chloromethyl-5
Cyclic unconjugated dienes such as -isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene Such a triene can be exemplified.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention has an iodine value of 1 (g / 100 g) or more and less than 20 (g / 100 g), preferably 1 to 19 (g / 100 g). (G / 100 g). If this characteristic value is much smaller than the above range and is too small, the crosslinking efficiency is small, and if it is too large, environmental degradation resistance is deteriorated,
Further, it is not preferable because it is disadvantageous in terms of cost.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention has a temperature of 100 ° C.
It is preferable to use a copolymer rubber having a Mooney viscosity of 10 to 120, preferably 20 to 100.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention is produced by a known method as shown in a polymer production process (published by the Industrial Research Association).

Organic peroxide (B) The organic peroxide (B) used in the present invention includes, for example, dicumyl peroxide, di-t-
Butyl peroxide, di-t-butylperoxy-
3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, di-t-amyl peroxide,
t-butyl hydroperoxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexyne-3,
2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t-
Butylperoxy) -hexane, α, α'-bis (t-
Dialkyl peroxides such as butylperoxy-m-isopropyl) benzene, t-butylperoxyacetate, t-butylperoxyisobutyrate,
Butyl peroxybivalate, t-butyl peroxymaleic acid, t-butyl peroxy neodecanoate, t
Peroxyesters such as -butylperoxybenzoate and di-t-butylperoxyphthalate; ketone peroxides such as dicyclohexanone peroxide; and mixtures thereof. Among them, it is preferable to use an organic peroxide having a temperature for giving a half-life of 1 minute in the range of 130 ° C. to 200 ° C., and in particular, dicumyl peroxide, di-t-butyl peroxide, di-t-butyl peroxy- Organic peroxides such as 3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, di-t-amyl peroxide, and t-butyl hydroperoxide can be preferably used. These organic peroxides are used alone or in combination of two or more.

The organic peroxide of the present invention is ethylene • α-
It is used in an amount of 0.001 to 0.05 mol, preferably 0.001 to 0.03 mol, per 100 parts by weight of the olefin / non-conjugated polyene copolymer rubber (A). It is desirable to determine the optimum amount appropriately.

When an organic peroxide is used, a vulcanization aid may be used in combination. Specific examples of the vulcanization aid include sulfur; quinone dioxime compounds such as p-quinone dioxime; methacrylate compounds such as polyethylene glycol dimethacrylate; diallyl phthalate and triallyl cyanurate. And maleimide compounds; divinylbenzene and the like. These crosslinking aids are used alone or in combination of two or more. The vulcanization aid is used in an amount of 0.1 to 2 mol, preferably about equimolar, per 1 mol of the organic peroxide used.

Carbon Black (C) Next, the carbon black (C) used in the present invention has an arithmetic mean particle size (d _av ) in the range of 20 to 50 mm, more preferably 25 to 45 mm. Are used. Also carbon black (C)
Are used alone or in combination of two or more.

The compounding amount of these carbon blacks (C)
Is ethylene / α-olefin / non-conjugated polyene copolymer
30 to 100 parts by weight per 100 parts by weight of rubber (A)
is there. Furthermore, the arithmetic average particle size of carbon black (C)
(D_av) And ethylene / α-olefin / non-conjugated polyether
Amount based on 100 parts by weight of copolymer rubber (A)
(X _CB) Is 0.25 ≦ (d_av) / (X_CB) ≤
A value of 1.0 is preferred in terms of rubber reinforcement.

The rubber composition of the present invention may be appropriately compounded with a compounding agent known per se, for example, a rubber filler, a softener, and the like, depending on the intended use of the vulcanized product.

In this case, the total amount of the component (A) occupying the composition is generally 20% by weight or more, particularly preferably 25% by weight or more, though it varies depending on the use and the like.

The rubber filler that can be used can increase the hardness of a rubber product without significantly affecting physical properties,
Used to reduce costs. Specific examples of such a filler include light calcium carbonate, heavy calcium carbonate, talc, clay and the like.

These rubber fillers can be appropriately selected according to the application, but the total amount of the above-mentioned component (A) is 100%.
It is preferable that the amount be 200 parts by weight or less, particularly 100 parts by weight or less, per part by weight.

As the softening agent usable in the present invention, a softening agent usually used for rubber is sufficient, but specific examples include process oils, lubricating oils, paraffins, liquid paraffins, petroleum asphalts, petrolatums such as petrolatum, etc. Softeners, cold tar softeners such as cold tar, cold tar pitch, etc .; fatty oil softeners such as castor oil, linseed oil, rapeseed oil, coconut oil, etc .; , Beeswax, carnauba wax, waxes such as lanolin, ricinoleic acid, palmitic acid, barium stearate, calcium stearate,
Examples thereof include fatty acids and fatty acid salts such as zinc laurate, synthetic polymer substances such as petroleum resins, atactic polypropylene, and coumarone indene resins. Among them, a petroleum softener is preferably used, and particularly, a process oil is preferably used.

The amount of these softeners can be appropriately selected depending on the use of the vulcanized product. The amount of the softener is 100 parts by weight or less, particularly 80 parts by weight or less, per 100 parts by weight of the component (A). It is preferred that there be.

Further, the composition of the present invention may optionally contain a processing aid, an antioxidant, a dispersant, and a flame retardant.

As the processing aid, compounds used in ordinary rubber processing can be used. In particular,
Higher fatty acids such as ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate, esters of the above acids, salts thereof, and esters thereof can be given.

Such processing aids are usually ethylene / α
-Olefin / non-conjugated polyene copolymer rubber (A) 100
It is used in a proportion of 10 parts by weight or less, preferably 5 parts by weight or less with respect to parts by weight, but it is desirable to determine an optimal amount appropriately according to required physical properties.

Although the rubber composition and rubber of the present invention exhibit excellent heat resistance and durability without using an anti-aging agent, the use of an anti-aging agent can further extend the product life. become. Examples of the antioxidant used in this case include naphthylamine-based antioxidants such as phenyl-α-naphthylamine and phenyl-β-naphthylamine; p- (p-toluenesulfonylamide) -diphenylamine; (Α-α-dimethylbenzyl) diphenylamine, 4,4′-dioctyldiphenylamine, a high-temperature reaction product of diphenylamine and acetone,
Low-temperature reaction product of diphenylamine and acetone, low-temperature reaction product of diphenylamine and aniline and acetone, reaction product of diphenylamine and diisobutylene, octylated diphenylamine, dioctylated diphenylamine,
diphenylamine-based antioxidants such as p, p'-dioctyldiphenylamine, alkylated diphenylamine; N, N'-diphenyl-P-phenylenediamine;
N-isopropyl-N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-
Phenylenediamine, N-phenyl-N '-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, N, N'-bis (1-methylheptyl) -p-phenylenediamine, N, N'- Screw (1,
4-dimethylpentyl) -p-phenylenediamine,
N, N'-bis (1-ethyl-3-methylpentyl)-
p-phenylenediamine, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, phenyl, hexyl-p-phenylenediamine, phenyl,
P-phenylenediamine-based anti-aging agents such as octyl-p-phenylenediamine; amine-based anti-aging agents such as;
Styrenated phenol, 2,6-di-t-butylpheno-butyl-4-methylfur, 2,6-di-t-butyl-
4-methylphenol, 2,6-di-t-butyl-p-
Ethylphenol, 2,4,6-tri-t-butylphenol, butylhydroxyanisole, 1-hydroxy-3-methyl-4-isopropylbenzene, mono-t-
Butyl-p-cresol, mono-tert-butyl-m-cresol, 2,4-dimethyl-6-tert-butylphenol
, Butylated bisphenol A, 2,2'-methylene-
Bis- (4-methyl-6-t-butylphenol),
2,2'-methylene-bis- (4-ethyl-6-t-butylphenol), 2,2'-methylene-bis- (4-
Methyl-6-t-nonylphenol), 2,2′-isobutylidene-bis- (4,6-dimethylphenol),
4,4'-butylidene-bis- (3-methyl-6-t-
Butylphenol), 4,4'-methylene-bis-
(2,6-di-t-butylphenol), 2,2′-thio-bis- (4-methyl-6-t-butylphenol)
), 4,4'-thio-bis- (3-methyl-6-t-
Butylphenol), 4,4'-thio-bis- (2-methyl-6-butylphenol), 4,4'-thio-bis- (6-t-butyl-3-methylphenol), bis (3-methyl-4-hydroxy-5-t-butylbenzene) sulfide, 2,2-thio [diethyl-bis-3-
(3,5-di-t-butyl-4-hydroxypheno-
L) propionate], bis [3,3-bis (4'-hydroxy-3'-tert-butylphenol) butyric acid] glycol ester, bis [2- (2-hydroxy-5-methyl- 3-tert-butylbenzene) -4-methyl-6-tert-butylphenyl] terephthalate, 1,
3,5-tris (3 ′, 5′-di-t-butyl-4′-
(Hydroxybenzyl) isocyanurate, N, N'-hexamethylene-bis (3,5-di-t-butyl-4-hydroxy-hydrosamide), N-octadecyl-3-
(4'-hydroxy-3 ', 5'-di-t-butylphenol) propionate, tetrakis [methylene-
(3 ', 5'-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 1,1'-bis (4-hydroxyphenyl) cyclohexane, mono (α-methylbenzene) phenol, (Α-methylbenzyl) phenol, tri (α-methylbenzyl) phenol, bis (2′-hydroxy-3′-t-butyl-5′-methylbenzyl) 4-methyl-phenol, , 5-di-t-
Amylhydroquinone, 2,6-di-butyl-α-dimethylamino-p-cresol, 2,5-di-t-butylhydroquinone, diethyl of 3,5-di-t-butyl-4hydroxybenzyl phosphate Phenolic antioxidants such as esters, catechols and hydroquinones, 2-mercaptobenzimidazole, zinc salts of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 2-mercaptomethyl Zinc salt of benzimidazole, zinc salt of 2-mercaptomethylimidazole,
Dimistilthiodipropionate, dilaurylthiodipropionate, distearylthiodipropionate, ditridecylthiodipropionate, pentaerythritol
Le-tetrakis- (β-lauryl-thiopropione-
G) and other sulfur-based anti-aging agents.

These are used alone or in combination of two or more. The compounding amount of such an antioxidant is as follows: ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) 1
The amount is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight with respect to 00 parts by weight.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber composition of the present invention can be prepared, for example, by the following method. That is, an ethylene / α-olefin / non-conjugated polyene copolymer (A) and a carbon black (C) and, if necessary, a filler, by internal mixers such as Banbury mixer, kneader and intermix. After kneading additives such as a softener and an antioxidant at a temperature of 80 to 170 ° C. for 3 to 10 minutes,
Using a roll such as pun roll, or a kneader, an organic peroxide (B) and a crosslinking assistant are additionally mixed as necessary, and a roll surface temperature of 40 to 80 ° C and 5 to 5 ° C. It can be prepared by kneading for 30 minutes and then dispensing. When the kneading temperature in the internal mixer is low, the organic peroxide (B), the crosslinking assistant, and the like may be kneaded together with the polymer, the filler, the softening agent, the antioxidant, and the like.

The rubber composition thus prepared is vulcanized at 130 to 210 ° C. for 60 seconds to 1 hour by a vulcanizing apparatus such as a compression molding machine, an injection molding machine, and an injection molding machine. A vulcanized molded product is manufactured.

[0045]

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 First, the ingredients shown in Table 1 were kneaded for 5 minutes at a temperature of 140 ° C. to 150 ° C. using a 1.7-liter Banbury mixer to obtain a composition.

[0047]

[Table 1] * 1 Ethylene propylene / 5-vinyl-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 65
/ 35ML (1 + 4) 100 ° C = 42 Iodine value = 5.3
All iodine values were determined by titration. * 2 Sakai Chemical Industry Co., Ltd. * 3 Nippon Oil & Fats Co., Ltd., Tsubaki, trademark * 4 Tokai Carbon Co., Ltd., Seast 116G, trademark arithmetic mean particle size: 38 mm

Next, a rubber composition containing the above compound was added to 8
Wound around an inch open roll (Nippon Koki Co., Ltd.)
A compounding agent was added on this open roll so as to have a compounding formulation shown in Table 2, and the mixture was kneaded for 5 minutes, and then a sheet having a thickness of 3 mm was formed. At this time, the roll surface temperature was 50 ° C. for the front roll and 50 ° C. for the rear roll.

[0049]

[Table 2] * 5 Mitsui Petrochemical Industries, Ltd., Mitsui DCP-40
C, trademark

The above mixture was heated for 10 minutes at a mold temperature of 170 ° C. using a press molding machine (manufactured by Kotaki Seiki Co., Ltd.).
An m-thick vulcanized sheet was obtained and subjected to measurement of modulus, tensile properties, aging properties, and liquid resistance. The compression set was measured by heating at the same temperature for 15 minutes, the diameter was 29.0 mm, and the thickness was 12.7.
mm was obtained and measured using this block.

[Tensile properties] JIS K6251 (19
1993). Measurement temperature 25 ° C., subjected to tensile test at a tensile rate of 500 mm / min condition was measured elongation E _B and strength T _B at break.

[Aging Test] JIS K 6257 (19
After aging in an oven at 150 ° C. for 70 hours, a tensile test was conducted at a measuring temperature of 25 ° C. and a tensile speed of 500 mm / min, and the elongation and strength at break were measured.
Tensile strength retention A _C (T _B ), elongation retention A _C (E _B )
Was calculated. The hardness change A _H was also calculated.

[Compression permanent set] JIS K 6301 (1
975), at 25 ° C. for 22 hours at 25 ° C., and the residual strain was measured.

[Effective network chain density] JIS K 6258
According to (1993), the vulcanized rubber sheet was immersed in cyclohexane at 25 ° C. for 72 hours, and then calculated by the Flory-Rehner equation.

(Equation 1) vγ: Volume fraction of pure rubber to volume of swollen pure rubber (volume of pure rubber + volume of solvent absorbed) in swollen vulcanized rubber μ: interaction coefficient between rubber and solvent (0.35) V ₀ : molecular volume of the solvent ν: effective network chain density (number of effective network chains per cc of pure rubber)

[Liquid resistance test] JIS K 6258 (19
93) at 150 ° C in DOT-3 brake fluid.
After immersion for 0 hour, measurement temperature 25 ° C, tensile speed 500
A tensile test was performed under the conditions of mm / min, and the elongation and strength at break were measured, and the tensile strength retention S _C (T _B ) and elongation retention S
_C (E _B ) was calculated. The hardness change S _H and the volume change rate ΔV were also measured.

The results are shown in Table 3.

[0057]

[Table 3]

Example 2 Example 1 was repeated except that the following rubber was used as the ethylene / α-olefin / non-conjugated polyene copolymer rubber.
And went exactly the same. Ethylene / propylene / 5-vinyl-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 66/34 ML (1 + 4) 100 ° C. = 39 Iodine value = 10.7 The results obtained are shown in Table 3.

Example 3 Example 1 was repeated except that the following rubber was used as the ethylene / α-olefin / non-conjugated polyene copolymer rubber.
And went exactly the same. Ethylene / propylene / 5-vinyl-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 65/25 ML (1 + 4) 100 ° C. = 34 Iodine value = 18.8 The results obtained are shown in Table 3.

Example 4 Example 1 was repeated except that the following rubber was used as the ethylene / α-olefin / non-conjugated polyene copolymer rubber.
And went exactly the same. Ethylene / propylene / 5-vinyl-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 71/29 ML (1 + 4) 100 ° C. = 85 Iodine value = 4.9 The results obtained are shown in Table 3.

Example 5 Example 1 was repeated except that the following rubber was used as the ethylene / α-olefin / non-conjugated polyene copolymer rubber.
And went exactly the same. Ethylene / butene / 5-vinyl-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 78/22 ML (1 + 4) 100 ° C. = 45 Iodine value = 6.1 The results obtained are shown in Table 3.

Example 6 Example 1 was repeated except that the following ethylene / α-olefin / non-conjugated polyene copolymer rubber was used.
And went exactly the same. Ethylene propylene 5- (2-propenyl) -2-
Norbornene copolymer rubber Ethylene / propylene molar ratio = 68/32 ML (1 + 4) 100 ° C. = 38 Iodine value = 7.1 The results obtained are shown in Table 3.

Example 7 In Example 1, the carbon black was changed to Asahi # 60G (Asahi Carbon Co., Ltd., arithmetic average particle size: 45 mm).
The procedure was exactly the same as in Example 1, except that 60 parts by weight were added. Table 3 shows the obtained results.

Example 8 The same procedure as in Example 1 was carried out except that carbon black was changed to Seast 600 (manufactured by Tokai Carbon Co., Ltd., arithmetic average particle size: 23 mm) and 75 parts by weight were added. went. Table 3 shows the obtained results.

Example 9 The procedure of Example 3 was repeated except that the amount of the organic peroxide was reduced to 0.005 mol. Table 3 shows the obtained results.

Comparative Example 1 Example 1 was repeated except that the following ethylene / α-olefin / non-conjugated polyene copolymer rubber was used.
And went exactly the same. Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 65/35 ML (1 + 4) 100 ° C. = 30 Iodine value = 22.5 The results obtained are shown in Table 4.

Comparative Example 2 Example 1 was repeated except that the following rubber was used as the ethylene / α-olefin / non-conjugated polyene copolymer rubber.
And went exactly the same. Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber Ethylene / propylene molar ratio = 68/32 ML (1 + 4) 100 ° C. = 45 Iodine value = 13.0 The results obtained are shown in Table 4.

Comparative Example 3 Example 1 was repeated except that the following rubber was used as the ethylene / α-olefin / non-conjugated polyene copolymer rubber.
And went exactly the same. Ethylene / propylene copolymer rubber Ethylene / propylene molar ratio = 70/30 ML (1 + 4) 100 ° C. = 70 Iodine value = 0.3 The results obtained are shown in Table 4.

Comparative Example 4 Example 1 was repeated except that the following ethylene / α-olefin / non-conjugated polyene copolymer rubber was used.
And went exactly the same. Ethylene / propylene / dicyclopentadiene copolymer rubber Ethylene / propylene molar ratio = 68/32 ML (1 + 4) 100 ° C. = 68 Iodine value = 13.2 The results obtained are shown in Table 4.

As can be seen from these results, the rubber composition for a hydraulic cylinder seal of the present invention has a significantly higher organic peroxide crosslinking efficiency than conventional EPR and EPDM, and is intended to reduce the cost of products. Shortening the vulcanization time,
It is possible to eliminate the secondary vulcanization step or to reduce the amount of the organic peroxide to be blended. In addition, conventional EPR, ethylene / propylene / 5-ethylidene-2-
It has better heat aging resistance than a rubber composition using a norbornene copolymer rubber or an ethylene / propylene / dicyclopentadiene copolymer rubber.

[0071]

[Table 4]

[0072]

The rubber composition of the present invention thus produced is, as shown in the above-mentioned Examples, a conventional EPR and EPD.
The crosslinking efficiency when organic peroxide crosslinking is higher than that of M, and the scratch resistance is excellent. In addition, high-speed molding is possible, and products can be manufactured at low cost by shortening the vulcanization time, eliminating the secondary vulcanization process, and reducing the amount of organic peroxide used. Further, it has better heat aging resistance than conventional EPR and EPDM.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 47/00 C08L 47/00 (72) Inventor Tetsuo Tojo 3 Chigusa Kaigan, Ichihara-shi, Chiba Prefecture Mitsui Chemicals, Inc.

Claims (6)

[Claims] 1. A rubber composition comprising a copolymer comprising ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene, wherein [I] (1) ethylene and carbon in the copolymer (2) the molar ratio with the α-olefin of the formulas 3 to 20 is in the range of 40/60 to 90/10;
The non-conjugated polyene in the copolymer has the following general formula [I]
And / or [b] Wherein n is an integer of 0 to 10, R ¹ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ] Wherein R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. (3) The non-conjugated polyene in the copolymer has an iodine value of 1 (g / g 100 g) or more and less than 20 (g / 100 g) and (4) the copolymer has a Mooney viscosity at 100 ° C. of 10 to 120.
α-olefin / non-conjugated polyene copolymer rubber (A),
[II] A rubber composition for a hydraulic cylinder seal, comprising an organic peroxide (B) as an essential component. 2. The compounding amount of the organically modified oxide (B) according to claim 1 is 0.001 to 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A).
A rubber composition for a hydraulic cylinder seal, wherein the rubber composition is 0.05 mol. 3. [I] Ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) according to claim 1 and [II] Ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) 100 A liquid pressure characterized in that an organic peroxide (B) in a blending amount of 0.001 to 0.05 mol per part by weight and [III] carbon black (C) are blended as essential components. Cylinder seal rubber composition. 4. The hydraulic cylinder seal according to claim 3, wherein the arithmetic average particle diameter (d _av ) of the carbon black (C) according to claim 3 is in a range of 20 to 50 millimicrons. Rubber composition. 5. The compounding amount (X _CB ) of the carbon black (C) according to claim 4 is 30 to 100 parts by weight based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A). 5. A unit according to claim 4, wherein
5. The rubber composition for a hydraulic cylinder seal according to item 1. 6. An arithmetic average particle diameter (d _av ) of the carbon black (C) according to claim 4 and a compounding amount (X) based on 100 parts by weight of an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A). _{5. The} rubber composition for a hydraulic cylinder seal according to claim 4, wherein the relationship of ( _CB ) _satisfies 0.25 ≦ (d _av ) / (X _CB ) ≦ 1.0.