JP2001031811A - Crosslinkable rubber composition for hydraulic cylinder sealing and use of the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having a high crosslinking rate and productivity, capable of hot-air crosslinking in a hot-air valcanization tank or the like, and useful in the automotive industry by specifying the properties of the hot-air crosslinked rubber sheet obtained therefrom. SOLUTION: This composition crosslinkable by hot air or hot press is such that a crosslinked rubber sheet obtained by molding this composition into a sheet-like form followed by hot-air crosslinking of the sheet-like form has the following properties: the surface cannot be scratched at all when subjected to a pencil hardness test using a pencil with a hardness rank of HB, and furthermore, a crosslinked rubber sheet obtained by molding this composition into a sheet-like form followed by hot-press crosslinking of the sheet-like form has the following properties: (1) compression set after heat-treated at 150 deg.C for 22 h is <=70%, (2) the rate of volume change after immersed in a DOT-3 brake fluid at 150 deg.C for 70 h is -10 to +50%, (3) tensile strength retention and elongation retention are 50-150% and >=50% after heat-deteriorated at 150 deg.C for 70 h, respectively, and (4) tensile strength as a normal-state physical property is 3-25 Mpa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a hydraulic cylinder seal such as an aster cylinder of an automotive hydraulic brake and hydraulic clutch system, a rubber cup in a wheel cylinder, and a disk seal of a disk brake system. More specifically, the crosslinking speed is high and the productivity is excellent, and hot-air crosslinking such as HAV (hot air vulcanizing tank) and UHF (ultra-high frequency electromagnetic wave) is possible. The present invention relates to a rubber composition for a crosslinkable hydraulic cylinder seal having excellent properties such as properties, strength properties, and crosslinking speed, and uses thereof.

[0002]

BACKGROUND OF THE INVENTION Ethylene / α-olefin / non-conjugated polyene random copolymer rubbers such as EPDM are excellent in heat aging resistance, low-temperature properties, weather resistance, water resistance, chemical resistance and flexibility. It is used for sealing parts such as sealing materials for automotive window frames. In recent years, it has been known that it is used as a hydraulic cylinder seal material for a master cylinder of an automobile hydraulic brake and hydraulic clutch system, a rubber cup in a wheel cylinder, and a disk brake of a disk brake system.

Conventionally, in order to improve the heat aging resistance of an ethylene / α-olefin / non-conjugated polyene random copolymer rubber, organic peroxide crosslinking is generally performed.
However, this organic peroxide crosslinking has a problem that the crosslinking speed is slow, the productivity is deteriorated, and the mold contamination resistance is also deteriorated. In the future, the production style for the same application will be from batch type such as press to continuous type vulcanization type (HAV, UHF)
May be replaced. Moreover, although the method of converting from sulfur vulcanization to peroxide cross-linking is effective, this method of peroxide cross-linking involves hot air cross-linking such as HAV (hot air vulcanization tank) and UHF (ultra-high frequency electromagnetic wave). There is a drawback that the rubber surface does not crosslink or collapses (degradation), resulting in markedly poor scratch resistance. The reason for this is that peroxide does not participate in crosslinking and the rubber surface comes into contact with oxygen and the collapse progresses.If the rubber surface is cross-linked by steam cross-linking to cut off oxygen, cross-linking with lead, etc., the scratch resistance of the rubber surface will be reduced. Although improved, it is disadvantageous in terms of production costs.

Japanese Patent Application Laid-Open No. 4-154855 discloses an HA
Rubber composition comprising ethylene-propylene-diene copolymer rubber capable of hot-air crosslinking with V, organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, and a platinum catalyst It is described that by using a rubber, hot air crosslinking is possible and a rubber excellent in scratch resistance can be obtained.

[0005] However, the inventors of the present application have re-examined the invention described in this publication, and as a result, the scratch resistance and the compression set resistance were not sufficiently satisfactory. JP-A-7-33924 discloses that at least one ethylene-propylene-diene copolymer rubber is used.
It is described that by performing peroxide crosslinking of a rubber composition obtained by adding a polysiloxane having two reactive groups, hot air crosslinking is possible and a rubber excellent in scratch resistance can be obtained.

[0006] However, the inventors of the present application have re-examined the invention described in this publication, and as a result, although the crosslinking efficiency has been increased by adding peroxide to the rubber composition, the peroxide has been improved. Since the radicals cause the addition reaction of the siloxane and the polymer radicals at the same time, it has been confirmed that the scratch resistance of the rubber product surface after crosslinking is not practical.

Therefore, the inventors of the present application have proposed ethylene · α-
The olefin / non-conjugated polyene random copolymer rubber composition has been studied extensively, and specific ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), Si
A rubber composition comprising a SiH group-containing compound (B) having at least two H groups in one molecule, and optionally a catalyst (C) and a reaction inhibitor (D), has a hot-air crosslink ( HAV, UHF, etc.)
Moreover, scratch resistance, heat aging resistance, compression set resistance,
The present inventors have found that it is possible to produce a rubber molded body having excellent liquid resistance (ΔV) and strength properties, and that it is suitable for use in hydraulic cylinder parts, and have completed the present invention.

[0008]

An object of the present invention is to solve the problems associated with the prior art as described above, and has a high cross-linking speed and excellent productivity, and has a HAV (hot air vulcanizing tank), UHF
(Ultra-high-frequency electromagnetic waves) can be crosslinked with hot air, and furthermore, heat aging resistance, compression set resistance, and liquid resistance (Δ
V) An object of the present invention is to provide a crosslinkable rubber composition for a hydraulic cylinder seal and a hydraulic cylinder component, which can prepare a crosslinked rubber molded article having excellent strength properties and the like.

[0009]

SUMMARY OF THE INVENTION The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention is a rubber composition which can be crosslinked by hot air and hot press. The resulting hot-air crosslinked rubber sheet has no scratches on its surface in a pencil hardness test with a HB pencil, and
A hot-pressed crosslinked rubber sheet obtained by forming the rubber composition into a sheet and then hot-pressing and crosslinking is obtained by:
Compression set (CS) after heat treatment for 2 hours is 70% or less, (2) Volume change rate (ΔV) after immersion in DOT-3 brake fluid at 150 ° C. for 70 hours is -10 to + 50%
(3) Tensile strength retention after heat aging at 150 ° C. for 70 hours is 50 to 150%, elongation retention is 50% or more, and (4) Tensile strength of normal physical properties is 3 to 25 MPa. It is characterized by:

The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention having the above-mentioned physical properties is characterized in that the non-conjugated polyene has at least one kind of vinyl group having a terminal vinyl group represented by the following general formula [I] or [II]. Ethylene and α-olefins having structural units derived from norbornene compounds
Non-conjugated polyene random copolymer rubber (A) and SiH
And a SiH group-containing compound (B) having at least two groups in one molecule, and the rubber composition has a crosslinking rate (t _c (90)) at 160 ° C. of 15 minutes or less.

[0011]

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Wherein n is an integer of 0 to 10,
R ¹ is a hydrogen atom 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. ]

[0013]

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Wherein R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) comprises (i) a molar ratio of ethylene to an α-olefin having 3 to 20 carbon atoms (ethylene / α-olefin).
Olefin) is in the range of 50/50 to 75/25,
(Ii) the iodine value is in the range of 1 to 30, and (iii) 13
The intrinsic viscosity [η] measured with a decalin solution at 5 ° C. is 0.3
２．５2.5 dl / g, and (iv) the branching index determined by a dynamic viscoelasticity meter is 5 or more.

This rubber composition is required in addition to the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and the SiH group-containing compound (B) having at least two SiH groups in one molecule. , A catalyst (C) and further a reaction inhibitor (D).

As the catalyst (C), a platinum-based catalyst is preferably used. The hydraulic cylinder component according to the present invention is characterized by comprising the above-described rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention.

The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention is used for producing an aster cylinder of a hydraulic brake and hydraulic clutch system for automobiles, a rubber cup in a wheel cylinder, a disk seal of a disk brake system, and the like. It is preferably used at the time of.

[0018]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, crosslinking (vulcanization) according to the present invention will be described.
A possible rubber composition for a hydraulic cylinder seal and its use will be specifically described.

Crosslinkable Rubber Composition The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention is a rubber composition which can be crosslinked by hot air and hot press, and the hot air crosslinked rubber sheet is made of HB pencil. No scratches on the surface in pencil hardness test

A hot-pressed crosslinked rubber sheet comprising the rubber composition for a crosslinkable hydraulic cylinder according to the present invention comprises:
(1) Compression set after heat treatment at 150 ° C for 22 hours (C
S) is 70% or less, and (2) DO at 150 ° C. for 70 hours
Volume change rate after immersion in T-3 brake fluid (ΔV)
(3) Tensile strength retention after heat aging at 150 ° C. for 70 hours is 50-150%, elongation retention is 50% or more, and (4) Tensile strength of normal physical properties Is 3 to 2
5 MPa.

The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention, which exhibits the above-mentioned physical properties, is composed of an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) having one SiH group. It contains a compound (B) having at least two SiH groups in the molecule, and optionally a catalyst (C) and a reaction inhibitor (D), and has a crosslinking rate (t _c (90)) at 160 ° C. 15 minutes or less.

[Ethylene / α-olefin / non-conjugated poly
Enrandom copolymer rubber (A)] The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) used in the present invention comprises ethylene and
It is a random copolymer of an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene.

Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene,
4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene,
Examples thereof include 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. Among them, α-olefins having 3 to 10 carbon atoms are preferable, and propylene, 1-butene, 1-hexene, 1-octene and the like are particularly preferably carried.

These α-olefins may be used alone or in combination of two or more. The non-conjugated polyene used in the present invention has the following general formula [I] or [I
I] is a norbornene compound having a vinyl group at the terminal.

[0025]

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In the general formula [I], n is 0 to 10
R ¹ is a hydrogen atom or a carbon atom having 1 to 1
0 alkyl group, and as the alkyl group having 1 to 10 carbon atoms for R ¹ , specifically, a methyl group, an ethyl group,
Propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, isopentyl, t-pentyl, neopentyl, hexyl, isohexyl, heptyl, Examples include an octyl group, a nonyl group, and a decyl group.

R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Specific examples of the alkyl group having 1 to 5 carbon atoms of R ² include the alkyl groups having 1 to 5 carbon atoms among the specific examples of the above R ¹ .

[0028]

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In the general formula [II], R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Specific examples of the alkyl group of R ³ include the same alkyl groups as the specific examples of the alkyl group of R ¹ .

Examples of the norbornene compound represented by the above general formula [I] or [II] include 5-methylene-2-norbornene, 5-vinyl-2-norbornene, and 5-vinyl-2-norbornene.
(2-propenyl) -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- (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, 5- (3-methyl-5-hexenyl) -2-norbornene,
5- (3,4-dimethyl-4-pentenyl) -2-norbornene,
5- (3-ethyl-4-pentenyl) -2-norbornene, 5-
(7-octenyl) -2-norbornene, 5- (2-methyl-6-
Heptenyl) -2-norbornene, 5- (1,2-dimethyl-5-
Hexecil) -2-norbornene, 5- (5-ethyl-5-hexenyl) -2-norbornene, 5- (1,2,3-trimethyl-4-
Pentenyl) -2-norbornene. Among them, 5-vinyl-2-norbornene, 5-methylene-2-norbornene, 5- (2-propenyl) -2-norbornene,
(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. These norbornene compounds can be used alone or in combination of two or more.

The above norbornene compound such as 5-vinyl
In addition to 2-norbornene, the following non-conjugated polyenes can be used in combination as long as the physical properties aimed at by the present invention are not impaired.

Specific examples of such a non-conjugated polyene include 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4 -Hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl
Chain non-conjugated dienes such as -1,6-octadiene; methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-
Cyclic non-conjugated dienes such as methylene-2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene and dicyclopentadiene; 2,3 And trienes such as -diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene and 2-propenyl-2,2-norbornadiene.

Ethylene / α comprising the above-mentioned components
-Olefin / non-conjugated polyene random copolymer (A)
Has the following characteristics. (I) Molar ratio of ethylene to α-olefin having 3 to 20 carbon atoms (ethylene / α-olefin) The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) is obtained by (a) ethylene A unit derived from (b) a unit derived from an α-olefin having 3 to 20 carbon atoms (hereinafter sometimes simply referred to as an α-olefin) is 50/50 to 75/25, preferably 55/45 to 55/25.
75/25, more preferably 60/40 to 75/25
At a molar ratio [(a) / (b)].

When the molar ratio is within the above range, a rubber composition capable of providing a crosslinked rubber molded article having excellent heat aging resistance, strength characteristics and rubber elasticity is obtained. (Ii) Iodine value The iodine value of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) is 1 to 30 (g / 100 g), preferably 1 to 25 (g / 100 g), and more preferably 1-20
(g / 100 g), particularly preferably 1 to 18 (g / 100 g).

When the iodine value is within the above range, a rubber composition having a high crosslinking efficiency can be obtained, and a crosslinked rubber molding having excellent compression set resistance and environmental deterioration resistance (= heat aging resistance). A rubber composition that can provide a body is obtained. If the iodine value exceeds 30, it is not preferable because it is disadvantageous in terms of cost. (Iii) Intrinsic Viscosity The intrinsic viscosity [η] of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) measured in decalin at 135 ° C. is 0.3 to 2.5 dl / g, preferably 0 to 2.5 dl / g. 0.5 to 2.4 dl / g, more preferably 0.5 to 2.4 dl / g
2.3 dl / g, particularly preferably 0.5 to 2.2 dl / g
g is desirable.

When the intrinsic viscosity [η] is in the above range, a rubber composition which is excellent in strength properties and compression set resistance and can provide a crosslinked rubber molded article excellent in processability is obtained. (Iv) Branching index The branching index of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) determined by a dynamic viscoelasticity analyzer is 5 or more, preferably 7 or more, and more preferably 7 or more.
Above, more preferably 9 or more, particularly preferably 10 or more. If the value of the branching index is less than 5, the viscosity in the high shear rate region increases, and the fluidity deteriorates.
Roll processability and extrusion processability deteriorate.

The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) used in the present invention is:
It preferably has the following physical properties (v) to (vii) in addition to the physical properties of (i), (ii), (iii) and (iv). (V) Molecular weight distribution (Mw / Mn) The molecular weight distribution (Mw / Mn) of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) measured by GPC is from 2 to 200, preferably from 2.5 to 2.5. ~ 1
50, more preferably 3 to 120, particularly preferably 5
Desirably, it is 100.

When the molecular weight distribution (Mw / Mn) is within the above range, a rubber composition which is excellent in processability and can provide a crosslinked rubber molded article having excellent strength properties is obtained. (Vi) Effective network chain density (ν) [index of crosslink density] Using 100 moles of ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), 0.01 mol of dicumyl peroxide was used at 170 ° C. The effective network chain density (ν) after press-crosslinking for 10 minutes at 1.5 × 10 ²⁰
Number / cm ³ or more, preferably 1.8 × 10 ²⁰ / cm ³ or more, more preferably 2.0 × 10 ²⁰ / cm ³ or more.

The effective network chain density (ν) is 1.5 × 10
^{When the} number is ²⁰ / cm ³ or more, a rubber composition capable of providing a crosslinked rubber molded article having excellent compression set resistance is obtained. (Vii) Log (γ ₂ / γ ₁ ) / ν Ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) has a shear stress of 0.4 × 10 obtained from a melt flow curve at 100 ° C. Shear speed γ ₁ and shear stress 2.4 × 10 ⁶ dy when showing ⁶ dyn / cm ²
Ratio γ ₂ / γ with shear rate γ ₂ when indicating n / cm ²
₁ and the effective network chain density (ν) are represented by the general formula [II
I] 0.04 × 10 ⁻¹⁹ ≦ Log (γ ₂ / γ ₁ ) /ν≦0.20×10
^-19 It is preferable to satisfy the relationship represented by [III].

Ethylene / α-olefin / non-conjugated polyether
The random copolymer rubber (A) has a Log (γ)_Two/ Γ₁) When
Ratio to effective network chain density (ν) [Log (γ_Two/ Γ₁) /
ν] is 0.04 × 10^-19~ 0.20 × 10^-19, Preferred
0.042 × 10^-19 ~ 0.19 × 10^-19 ,
More preferably 0.050 × 10^-19~ 0.18 × 10
^-19It is desirable that

When the ratio [Log (γ ₂ / γ ₁ ) / ν] is within the above range, a rubber which can provide a crosslinked rubber molded article which is excellent in workability, strength properties and compression set resistance is provided. A composition is obtained.

The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) used in the present invention comprises:
"Polymer Manufacturing Process (Industry Research Institute, Inc., p.30)
9-330) or Japanese Patent Application Laid-Open No. 9-7, filed by the present applicant.
Nos. 1617, 9-71618, 9-208615, 10-67823, 10-67824, and 10-11
It can be prepared by a conventionally known method as described in JP-A-0054 or the like.

The olefin polymerization catalyst used in the production of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) used in the present invention includes vanadium (V), zirconium (Zr) and titanium. A Ziegler catalyst comprising a transition metal compound such as (Ti) and an organoaluminum compound (organoaluminum oxy compound), or a transition metal metallocene compound selected from Group IVB of the Periodic Table of the Elements, and an organoaluminum oxy compound or ionized A metallocene catalyst comprising an ionic compound is particularly preferably used.

When an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) is prepared using a catalyst containing the following compounds (H) and (I) as main components, boiling xylene insoluble It is preferable because an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) having a content of 1% or less can be obtained.

That is, the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) having a xylene insoluble content of 1% or less is a catalyst containing the following compounds (H) and (I) as main components. In the presence, the polymerization temperature is from 30 to
60 ° C., especially 30-59 ° C., polymerization pressure 4-12 kgf /
cm ² , especially 5 to 8 kgf / cm ² , and ethylene and non-conjugated polyene / ethylene molar ratio (non-conjugated polyene / ethylene) of 0.01 to 0.2 under the conditions of ethylene and 3 to 20 carbon atoms. And a norbornene compound having a vinyl group at the terminal represented by the above general formula [I] or [II] by random copolymerization. The copolymerization is preferably carried out in a hydrocarbon medium. (H) a soluble vanadium compound represented by VO (OR) _n X _3-n (where R is a hydrocarbon group, X is a halogen atom, and n is an integer of 0 or 1 to 3), Or a vanadium compound represented by VX ₄ (X is a halogen atom).

The above-mentioned soluble vanadium compound (H) is a component soluble in a hydrocarbon medium of a polymerization reaction system, and specifically, has the general formula VO (OR) aXb or V (OR) c
Xd (where R is a hydrocarbon group, 0 ≦ a ≦ 3, 0 ≦
b ≦ 3, 2 ≦ a + b ≦ 3, 0 ≦ c ≦ 4, 0 ≦ d ≦ 4, 3
.Ltoreq.c + d.ltoreq.4) and vanadium compounds represented by the following formulas, or electron-donor adducts thereof.

More specifically, VOCl ₃ , VO (OC
_{2 H 5) Cl 2, VO} (OC 2 H 5) 2 Cl, VO (O-iso
_{-C 3 H 7) Cl 2,} VO (O-n-C 4 H 9) Cl 2, VO
(OC ₂ H ₅ ) ₃ , VOBr ₃ , VCl ₄ , VOCl ₃ , VO
(On-C ₄ H ₉ ) ₃ and VCl ₃ .2OC ₆ H ₁₂ OH. (I) R ′ _m AlX ′ _3-m (R ′ is a hydrocarbon group,
X 'is a halogen atom, and m is an integer of 1 to 3.)
An organoaluminum compound represented by the formula:

Specific examples of the organoaluminum compound (I) include trialkylaluminums such as triethylaluminum, tributylaluminum and triisopropylaluminum; dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide; ethoxide, alkyl sesquichloride alkoxides such as butyl sesquichloride butoxide; R ¹ _0.5 Al
(OR ¹ ) a partially alkoxylated alkylaluminum having an average composition represented by _0.5 or the like; a dialkylaluminum halide such as diethylaluminum chloride, dibutylaluminum chloride and diethylaluminum bromide; ethylaluminum sesquichloride, butylaluminum sesquichloride; Partially halogenated alkylaluminums such as alkylaluminum sesquihalides such as ethylaluminum sesquibromide, alkylaluminum dihalides such as ethylaluminum dichloride, propylaluminum dichloride and butylaluminum dibromide; diethylaluminum hydride, dibutylaluminum hydride and the like Dialkyl aluminum hydride, ethyl aluminum dihydride, propyl alcohol Partially hydrogenated alkyl aluminum such as alkylaluminum dihydride such as ruminium dihydride; partially alkoxylated and halogenated alkylaluminum such as ethylaluminum ethoxycyclolide, butylaluminum butoxycyclolide, and ethylaluminum ethoxybromide Can be mentioned.

In the present invention, a soluble vanadium compound represented by VOCl ₃ among the above compound (H) and Al (OC ₂ H ₅ ) ₂ Cl among the above compound (I)
/ Al ₂ (OC ₂ H ₅ ) ₃ Cl ₃ (a blend ratio of 1/5 or more) is used as a catalyst component, soxhlet extraction (solvent: boiling xylene, extraction time: 3 hours,
It is preferable because an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) having an insoluble content of 1% or less after the mesh: 325) can be obtained.

Further, the ethylene-α-
The olefin / non-conjugated polyene random copolymer rubber (A) may be graft-modified with a polar monomer such as an unsaturated carboxylic acid or a derivative thereof (eg, acid anhydride, ester).

Specific examples of such unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, and bicyclo (2,2,1) hept- 2-ene-5,6-dicarboxylic acid and the like.

Specific examples of the unsaturated carboxylic acid anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo (2,2,
1) Hept-2-ene-5,6-dicarboxylic anhydride and the like. Among these, maleic anhydride is preferred.

Specific examples of the unsaturated carboxylic acid esters include methyl acrylate, methyl methacrylate, dimethyl maleate, monomethyl maleate, dimethyl fumarate, dimethyl itaconate, diethyl citrate, dimethyl tetrahydrophthalate, and bicyclo. (2,2,1) Dimethyl hept-2-ene-5,6-dicarboxylate and the like. Among these, methyl acrylate and ethyl acrylate are preferred.

The above-mentioned graft modifiers (unsaturated carboxylic acids) such as unsaturated carboxylic acids may be used alone or in combination of two or more. In any case, the above-mentioned ethylene-α-olefin before graft modification is used. The graft amount is preferably 0.1 mol or less per 100 g of the non-conjugated polyene copolymer rubber.

When the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) having the graft amount in the above range is used, a crosslinked rubber molded article excellent in cold resistance can be provided. A rubber composition having excellent properties (moldability) can be obtained.

The graft-modified ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) is obtained by mixing the above-mentioned unmodified ethylene / α-olefin / non-conjugated polyene copolymer rubber with an unsaturated carboxylic acid or its unsaturated carboxylic acid. It can be obtained by reacting with a derivative in the presence of a radical initiator.

This grafting reaction can be carried out in a solution or in a molten state. When the graft reaction is carried out in a molten state, it is most efficient and preferable to carry out the graft reaction continuously in an extruder.

Specific examples of the radical initiator used in the graft reaction include 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-butylperoxin) hexyne-3 , 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, α, α'-bis (t-
Dialkyl peroxides such as butylperoxy-m-isopropyl) benzene; t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-butylperoxymaleic acid, t-butylperoxypivalate
Peroxyesters such as butylperoxyneodecanoate, t-butylperoxybenzoate, and di-t-butylperoxyphthalate; ketone peroxides such as dicyclohexanone peroxide; and mixtures thereof. Among them, an organic peroxide having a temperature giving a half-life of 1 minute in the range of 130 to 200 ° C. is preferable, and in particular, dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3 , 5-trimethylcyclohexane, t-butylcumyl peroxide,
Organic peroxides such as -t-amyl peroxide and t-butyl hydroperoxide are preferred.

The polar monomer other than the unsaturated carboxylic acid or its derivative (eg, acid anhydride or ester) includes a hydroxyl group-containing ethylenically unsaturated compound, an amino group-containing ethylenically unsaturated compound, and an epoxy group-containing ethylenically unsaturated compound. Examples include a saturated compound, an aromatic vinyl compound, a vinyl ester compound, and vinyl chloride.

[SiH Group-Containing Compound (B)] The SiH group-containing compound (B) used in the present invention is ethylene • α-
Reacts with the olefin / non-conjugated polyene random copolymer rubber (A) and acts as a crosslinking agent. The molecular structure of the SiH group-containing compound (B) is not particularly limited.
Conventionally manufactured resinous materials having, for example, a linear, cyclic, branched or three-dimensional network structure can be used, but are directly bonded to at least two, preferably three or more silicon atoms in one molecule. It is necessary to contain a hydrogen atom, that is, a SiH group.

As such a SiH group-containing compound (B), a compound represented by the following general composition formula R ⁴ _b H _c SiO _{(4-bc) / 2} can be usually used.

In the above general formula, R ⁴ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms, excluding an aliphatic unsaturated bond;
Examples of such a monovalent hydrocarbon group include a phenyl group and a halogen-substituted alkyl group such as a trifluoropropyl group, in addition to the alkyl group exemplified for the aforementioned R ¹ . Among them, methyl group, ethyl group, propyl group,
A phenyl group and a trifluoropropyl group are preferred, and a methyl group and a phenyl group are particularly preferred.

B is 0 ≦ b <3, preferably 0.
6 <b <2.2, particularly preferably 1.5 ≦ b ≦ 2, and c is 0 <c ≦ 3, preferably 0.002 ≦ c <
2, particularly preferably 0.01 ≦ c ≦ 1, and b
+ C is 0 <b + c ≦ 3, preferably 1.5 <b + c ≦
2.7.

The compound (B) containing SiH group has one molecule
The number of silicon atoms is preferably 2 to 1000, and
Preferably between 2 and 300, most preferably between 4 and 200
An organohydrogenpolysiloxane, specifically
Include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-
Tramethyltetracyclosiloxane, 1,3,5,7,8-penta
Siloxane oligomers such as methylpentacyclosiloxane
-: Methyl high with trimethylsiloxy group at both ends of molecular chain
Drogen polysiloxane, molecular chain
Roxy-blocked dimethylsiloxane / methylhydrogen
Siloxane copolymer, silanol group at both ends of molecular chain
Methyl hydrogen polysiloxane, both ends of molecular chain
Lanol group-blocked dimethyl siloxane / methyl hydrogen
Siloxane copolymer, dimethyl hydride at both ends of molecular chain
Dimethylsiloxy-blocked dimethylpolysiloxane, molecule
Dimethyl hydrogensiloxy group-blocked methyl at both ends of chain
Hydrogen polysiloxane, both ends of molecular chain dimethyl
Hydrogensiloxy group-blocked dimethylsiloxane
Tyl hydrogen siloxane copolymer, R^Four _Two(H) S
iO_1/2 Unit and SiO_4/2Consisting of units and optionally R^Four
_ThreeSiO_1/2 Unit, R^Four _TwoSiO_2/2 Unit, R^Four(H) Si
O_2/2Unit, (H) SiO_{Three / 2} Or R^FourSiO_3/2Units
Examples thereof include silicone resins that can be included.

Examples of the methylhydrogenpolysiloxane having a trimethylsiloxy group at both ends of the molecular chain include a compound represented by the following formula, and in the following formula, a part or all of a methyl group is an ethyl group, a propyl group, a phenyl group or a trimethylsiloxy group. Compounds substituted with a fluoropropyl group and the like can be mentioned.

(CH ₃ ) ₃ SiO — (— SiH (CH ₃ ) —O—) _d —Si (CH ₃ ) ₃ [where d is an integer of 2 or more. As the dimethylsiloxane / methylhydrogensiloxane copolymer having a trimethylsiloxy group at both ends of the molecular chain, a compound represented by the following formula, and further, in the following formula, a part or all of a methyl group is an ethyl group, a propyl group, or a phenyl group And compounds substituted with a trifluoropropyl group or the like.

(CH ₃ ) ₃ SiO-(-Si (CH ₃ ) ₂ -O-) _e -(-
SiH (CH ₃ ) —O—) _f —Si (CH ₃ ) _{3 wherein} e is an integer of 1 or more, and f is an integer of 2 or more. Examples of the methyl hydrogen polysiloxane having silanol groups at both ends of the molecular chain include compounds represented by the following formula, and further, in the following formula, a part or all of a methyl group is an ethyl group, a propyl group, a phenyl group, and a trifluoropropyl group. And the like.

HOSi (CH ₃ ) ₂ O — (— SiH (CH ₃ ) —O
-) ₂ -Si (CH ₃ ) ₂ OH As a dimethylsiloxane / methylhydrogensiloxane copolymer having silanol groups at both ends of a molecular chain, for example, a compound represented by the following formula, and further a part of a methyl group or Compounds in which all are substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group and the like can be mentioned.

HOSi (CH ₃ ) ₂ O-(-Si (CH ₃ ) ₂ -O-)
_{e - (- SiH (CH 3} ) -O-) f - -Si (CH 3) 2 OH [e in the formula is an integer of 1 or more, f is an integer of 2 or more. Examples of the dimethylpolysiloxane having a dimethylhydrogensiloxy group blocked at both ends of a molecular chain include a compound represented by the following formula, and further, in the following formula, a part or all of a methyl group is ethyl group, propyl group, phenyl group, trifluoropropyl And a compound substituted with a group.

HSi (CH ₃ ) ₂ O-(-Si (CH ₃ ) ₂ -O-) _e-
Si (CH ₃ ) ₂ H wherein e is an integer of 1 or more. Examples of the methylhydrogenpolysiloxane having a dimethylhydrogensiloxy group at both ends of the molecular chain include a compound represented by the following formula, and further, in the following formula, a part or all of a methyl group is an ethyl group, a propyl group, a phenyl group or a trimethyl group. Compounds substituted with a fluoropropyl group and the like can be mentioned.

HSi (CH ₃ ) ₂ O — (— SiH (CH ₃ ) —O—) _e
—Si (CH ₃ ) ₂ H [E in the formula is an integer of 1 or more. Examples of the dimethylsiloxane / methylhydrogensiloxane copolymer having a dimethylhydrogensiloxy group blocked at both ends of a molecular chain include a compound represented by the following formula, and further, in the following formula, part or all of a methyl group is an ethyl group or a propyl group. And a compound substituted with a phenyl group, a trifluoropropyl group or the like.

HSi (CH ₃ ) ₂ O-(-Si (CH ₃ ) ₂ -O-) _e-
(—SiH (CH ₃ ) —O—) _h —Si (CH ₃ ) ₂ H [E and h are each an integer of 1 or more. Such a compound can be produced by a known method, for example, octamethylcyclotetrasiloxane and / or tetramethylcyclotetrasiloxane,
Hexamethyldisiloxane or 1,1, which can be a terminal group
A compound containing a triorganosilyl group or a diorganohydrogensiloxy group, such as 3-dihydro-1,1,3,3-tetramethyldisiloxane, is reacted with a catalyst such as sulfuric acid, trifluoromethanesulfonic acid, or methanesulfonic acid. It can be easily obtained by equilibrating at a temperature of about −10 ° C. to + 40 ° C. in the presence.

The SiH group-containing compound (B) is an ethylene.
0.1 to 100 parts by weight, based on 100 parts by weight of the α-olefin / non-conjugated polyene random copolymer rubber (A),
Preferably 0.1 to 75 parts by weight, more preferably 0.1
To 50 parts by weight, more preferably 0.2 to 30 parts by weight,
Even more preferably, it is used in a proportion of 0.2 to 20 parts by weight, particularly preferably 0.5 to 10 parts by weight, most preferably 0.5 to 5 parts by weight. When the SiH group-containing compound (B) is used in a proportion within the above range, a rubber composition that can form a crosslinked rubber molded article having excellent compression set resistance, moderate crosslink density, and excellent strength and elongation properties is obtained. can get. It is not preferable to use the SiH group-containing compound (B) in a proportion exceeding 100 parts by weight, because it is disadvantageous in terms of cost.

[Catalyst (C)] The catalyst (C) used as an optional component in the present invention is an addition reaction catalyst, and the alkenyl of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) component There is no particular limitation as long as the group promotes an addition reaction (hydrosilylation reaction of alkene) between the group and the SiH group of the SiH group-containing compound (B).
For example, an addition reaction catalyst composed of a platinum group element such as a platinum-based catalyst, a palladium-based catalyst, and a rhodium-based catalyst (a Group 8 metal-based catalyst such as a Group 8 metal, a Group 8 metal complex, or a Group 8 metal compound). Among them, a platinum-based catalyst is preferable.

The platinum-based catalyst may be a known catalyst usually used for addition-curing type curing. For example, US Pat.
No. 970,150, a finely powdered metal platinum catalyst,
The chloroplatinic acid catalyst described in U.S. Pat. No. 2,823,218 and the platinum-hydrocarbon catalyst described in U.S. Pat. No. 3,159,601 and U.S. Pat. No. 159,662. Complex compounds, US Pat. No. 3,516,94
6, a complex compound of chloroplatinic acid and an olefin, and a complex of platinum and vinyl siloxane described in U.S. Pat. No. 3,775,452 and U.S. Pat. No. 3,814,780. And the like. More specifically, examples thereof include a simple substance of platinum (platinum black), chloroplatinic acid, a platinum-olefin complex, a platinum-alcohol complex, and a carrier in which a platinum carrier is supported on a carrier such as alumina or silica.

The palladium-based catalyst comprises palladium, a palladium compound, palladium chloride or the like.
The rhodium-based catalyst comprises rhodium, a rhodium compound, rhodium chlorate and the like.

Examples of the catalyst (C) other than those described above include Lewis acids and cobalt carbonyl. Catalyst (C)
Is 0.1 to 100,00 with respect to the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A).
0 ppm by weight, preferably 0.1 to 10,000 weight p
pm, more preferably 1 to 5,000 ppm by weight, particularly preferably 5 to 1,000 ppm by weight.

When the catalyst (C) is used at a ratio within the above range, a rubber composition capable of forming a crosslinked rubber molded article having an appropriate crosslinking density and excellent strength and elongation characteristics is obtained. 1
It is not preferable to use the catalyst (C) at a ratio exceeding 0.00000 ppm by weight, because it is disadvantageous in terms of cost.

In the present invention, the catalyst (C)
To a non-crosslinked rubber molded article of a rubber composition containing no
A crosslinked rubber molded article can be obtained by irradiating a beam, an electron beam or the like. [Reaction inhibitor (D)] The reaction inhibitor (D) used as an optional component together with the catalyst (C) in the present invention includes benzotriazole, an ethynyl group-containing alcohol (eg, ethynylcyclohexanol), acrylonitrile,
Amide compounds (eg, N, N-diallylacetamide, N,
N-diallylbenzamide, N, N, N ', N'-tetraallyl-o-
Phthalic acid diamide, N, N, N ', N'-tetraallyl-m-phthalic acid diamide, N, N, N', N'-tetraallyl-p-phthalic acid diamide, etc.), sulfur, phosphorus, nitrogen, amine compounds And organic peroxides such as sulfur compounds, phosphorus compounds, tin, tin compounds, tetramethyltetravinylcyclotetrasiloxane, and hydroperoxide.

The reaction inhibitor (D) is an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) 1
0 to 50 parts by weight, usually 0.000 parts by weight to 00 parts by weight
1 to 50 parts by weight, preferably 0.0001 to 30 parts by weight, more preferably 0.0001 to 20 parts by weight, further preferably 0.0001 to 10 parts by weight, particularly preferably 0.0001 to 5 parts by weight. Used in

The reaction inhibitor (D) is used in an amount of 50 parts by weight or less.
When a rubber composition is used, a rubber composition having a high crosslinking speed and excellent productivity of a crosslinked rubber molded article can be obtained. It is not preferable to use the reaction inhibitor (D) in a proportion exceeding 50 parts by weight, because it is disadvantageous in terms of cost.

[Other Components] The rubber composition for a hydraulic cylinder seal that can be crosslinked according to the present invention can be used without being crosslinked, but it can be used as a crosslinked rubber molded article or a crosslinked rubber foamed molded article such as a crosslinked rubber foam molded article. The characteristics can be exhibited most when used as a product.

In the rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention, conventionally known rubber reinforcing agents, inorganic fillers, softeners, antioxidants, Additives such as processing aids, vulcanization accelerators, organic peroxides, crosslinking aids, foaming agents, foaming aids, coloring agents, dispersants, and flame retardants are blended within a range that does not impair the purpose of the present invention. be able to.

The rubber reinforcing agent has the effect of improving mechanical properties such as tensile strength, tear strength and abrasion resistance of the crosslinked (vulcanized) rubber. Specific examples of such a rubber reinforcing agent include SRF, GPF, FEF, HAF, ISAF,
Examples thereof include carbon blacks such as SAF, FT, and MT, and carbon blacks that have been surface-treated with a silane coupling agent, finely divided silica, silica, and the like.

Specific examples of silica include fumed silica,
Precipitated silica and the like. These silicas may be surface-treated with a reactive silane such as hexamethyldisilazane, chlorosilane, alkoxysilane, or a low-molecular-weight siloxane. The specific surface area of silica (BED method) is preferably 50 m ² / g or more, more preferably 100 to 400 m ² / g.

The type and amount of the rubber reinforcing agent can be appropriately selected depending on the application, but the amount of the rubber reinforcing agent is usually the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) 100 For parts by weight,
Up to 300 parts by weight, preferably up to 200 parts by weight.

Specific examples of the above-mentioned inorganic filler include light calcium carbonate, heavy calcium carbonate, talc, clay and the like. The type and amount of these inorganic fillers can be appropriately selected depending on the application, but the amount of the inorganic filler is usually 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A). In contrast, it is at most 300 parts by weight, preferably at most 200 parts by weight.

As the softening agent, a softening agent usually used for rubber can be used. Specifically, petroleum softening agents such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum; coal tar softening agents such as coal tar and coal tar pitch; castor oil, linseed oil, rapeseed oil, Fatty oil-based softeners such as coconut oil; tall oil; sub; waxes such as beeswax, carnauba wax and lanolin; fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, barium stearate, calcium stearate, zinc laurate; Synthetic polymer substances such as resin, atactic polypropylene, and coumarone indene resin can be used. Among them, a petroleum softener is preferably used, and particularly, a process oil is preferably used.

The mixing amount of these softeners is appropriately selected depending on the use of the crosslinked product. Examples of the anti-aging agent include amine-based, hindered phenol-based, or sulfur-based anti-aging agents, and as described above, these anti-aging agents are used within a range that does not impair the object of the present invention. Can be

The amine antioxidants used in the present invention include diphenylamines and phenylenediamines. Specific examples of the diphenylamines include p- (p-toluenesulfonylamide) -diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, 4,4′-dioctyl diphenylamine,
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,
p, p'-Dioctyl diphenylamine, alkylated diphenylamine and the like.

Specific examples of phenylenediamines include 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 '-(-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, N N, N'-bis (1-methylheptyl) -p-phenylenediamine, N, N'-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N'-bis (1-ethyl-3- P- such as methylpentyl) -p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, phenylhexyl-p-phenylenediamine, and phenyloctyl-p-phenylenediamine
And phenylenediamines.

Of these, 4,4 '-(α, α-dimethylbenzyl) diphenylamine and N, N'-di-2-naphthyl-p-phenylenediamine are particularly preferred. These compounds can be used alone or in combination of two or more.

The hindered phenolic antioxidants used in the present invention include (1) 1,1,3-tris
-(2-methyl-4-hydroxy-5-t-butylphenylbutane, (2) 4,4'-butylidenebis- (3-methyl-6-t-butylphenol), (3) 2,2-thiobis (4 -Methyl-6-t
-Butylphenol), (4) 7-octadecyl-3- (4'-
Hydroxy-3 ', 5'-di-t-butylphenyl) propionate, (5) tetrakis- [methylene-3- (3', 5'-di-t
-Butyl-4'-hydroxyphenyl) propionate methane, (6) pentaerythritol-tetrakis [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate], (7) triethylene glycol-bis [3- (3-t-
Butyl-5-methyl-4-hydroxyphenyl) propionate], (8) 1,6-hexanediol-bis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate], (9) 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3, 5-triazine, (10) tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, (11) 2,2-thio-diethylenebis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate], (12) N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy) -hydrocinnamide, (13) 2,4- Bis [(octylthio) methyl]
-o-cresol, (14) 3,5-di-t-butyl-4-hydroxybenzyl-phosphonate-diethyl ester, (15)
Tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, (16) octadecyl
3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, (17) 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5- Methylphenyl) propionyloxy {-1,1-dimethylethyl] -2,4-8,10-tetraoxaspiro [5,5] undecane.
Among them, the phenol compounds (5) and (17) are particularly preferred.

As the sulfur-based anti-aging agent used in the present invention, a sulfur-based anti-aging agent usually used for rubber is used. Specifically, imidazole-based aging such as 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptomethylbenzimidazole, and zinc salt of 2-mercaptomethylimidazole Inhibitors: dimyristyl thiodipropionate, dilauryl thiodipropionate, distearyl thiodipropionate, ditridecyl thiodipropionate, pentaerythritol
-Tetrakis- (β-lauryl-thiopropionate)
And other aliphatic thioether-based antioxidants. Among these, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptomethylbenzimidazole, pentaerythritol-tetrakis- (β-lauryl-thiopropio Is preferred.

As the processing aids described above, compounds used in ordinary rubber processing can be used. Specifically, higher fatty acids such as ricinoleic acid, stearic acid, palmitic acid and lauric acid; salts of higher fatty acids such as barium stearate, zinc stearate and calcium stearate; ricinoleic acid, stearic acid, palmitic acid and lauric acid And higher fatty acid esters.

Such processing aids are usually ethylene
It is used in an amount of 10 parts by weight or less, preferably 5 parts by weight or less based on 100 parts by weight of the α-olefin / non-conjugated polyene random copolymer rubber (A), but is appropriately optimized according to required physical properties. It is desirable to determine the amount.

In the present invention, an organic peroxide may be used in addition to the above-mentioned catalyst (C) to perform both addition crosslinking and radical crosslinking. Organic peroxide is ethylene
It is used in an amount of about 0.1 to 10 parts by weight based on 100 parts by weight of the α-olefin / non-conjugated polyene random copolymer rubber (A). As the organic peroxide, a conventionally known organic peroxide that is usually used at the time of rubber crosslinking can be used.

When an organic peroxide is used, it is preferable to use a crosslinking assistant together. As a crosslinking aid,
Specifically, sulfur; quinone dioxime compounds such as p-quinone dioxime; methacrylate compounds such as polyethylene glycol dimethacrylate; allyl compounds such as diallyl phthalate and triallyl cyanurate; maleimide compounds; Is mentioned. Such a crosslinking assistant is used in an amount of 0.5 to 2 mol, preferably about equimolar, based on 1 mol of the organic peroxide used.

Specific examples of the foaming agent include sodium bicarbonate, sodium carbonate, ammonium bicarbonate,
Inorganic blowing agents such as ammonium carbonate and ammonium nitrite; nitroso compounds such as N, N'-dimethyl-N, N'-dinitrosoterephthalamide, N, N'-dinitrosopentamethylenetetramine; azodicarbonamide, azobisiso Azo compounds such as butyronitrile, azocyclohexylnitrile, azodiaminobenzene, and barium azodicarboxylate; benzenesulfonylhydrazide, toluenesulfonylhydrazide, p, p'-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3'- Sulfonyl hydrazide compounds such as disulfonyl hydrazide; calcium azide, 4,4-diphenyldisulfonyl azide,
and azide compounds such as p-toluenesulfonyl azide.

These foaming agents are ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) 10
0.5 to 30 parts by weight, preferably 1 to 0 parts by weight
It is used in a proportion of up to 20 parts by weight. When the foaming agent is used in the above ratio, a foam having a specific gravity of 0.03 to 0.8 g / cm ³ can be produced. However, it is possible to appropriately determine an optimal amount according to required physical properties. desirable.

Further, if necessary, in combination with a foaming agent,
A foaming aid may be used. The foaming aid acts to lower the decomposition temperature of the foaming agent, promote the decomposition, and make the air bubbles uniform. Examples of such a foaming aid include organic acids such as salicylic acid, phthalic acid, stearic acid and oxalic acid, urea and derivatives thereof.

These foaming assistants are ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) 1
It is used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight with respect to 00 parts by weight, but it is desirable to appropriately determine an optimum amount according to required physical properties.

In the crosslinkable rubber composition according to the present invention, it can be blended with other known rubbers as long as the object of the present invention is not impaired. Such other rubbers include natural rubber (NR) and isoprene rubber (I
R), butadiene rubber (B)
R), conjugated diene rubbers such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and chloroprene rubber (CR).

Further, conventionally known ethylene / α-olefin-based copolymer rubbers can also be used, for example, ethylene / propylene random copolymer (EPR), the aforementioned ethylene / α-olefin / non-conjugated polyene random copolymer rubber. Ethylene / α-olefin / polyene copolymers other than (A) (for example, EPDM) can be used.

Hydraulic Cylinder Part The hydraulic cylinder part according to the present invention comprises the aforementioned rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention.

The hydraulic cylinder part according to the present invention may be composed of a non-crosslinked material such as a non-crosslinked rubber molded product or a non-crosslinked foamed molded product. The rubber composition for a hydraulic cylinder seal according to the present invention can exhibit the best characteristics when it is composed of such a crosslinked product.

The rubber composition for sealing a hydraulic cylinder which can be crosslinked according to the present invention is suitably used in the production of cup seal materials for automobiles, seal materials for industrial machines, seal sponges for construction, and the like.

As the above-mentioned automobile cup sealing material,
For example, master cylinder piston cup, wheel cylinder piston cup, constant velocity joint boot, pin boot, cast cover, piston seal, packing, O
A ring, a diaphragm, and the like can be given.

Preparation of Rubber Composition and Its Crosslinked Rubber Molded Article
As manufactured above, crosslinkable hydraulic cylinder seal rubber composition according to the present invention can be used even while uncrosslinked, as cross-linked product, such as cross-linked rubber molded product or crosslinked rubber foam molded body The characteristics can be exhibited most when used.

In order to produce a crosslinked product from the rubber composition for a hydraulic cylinder seal capable of being crosslinked according to the present invention, an uncrosslinked compounded rubber is once prepared in the same manner as when vulcanizing (crosslinking) a general rubber. It may be prepared, and then the compounded rubber may be molded into an intended shape and then crosslinked.

As a crosslinking method, a method using a crosslinking agent (SiH group-containing compound (B)) for heating, light, γ
Either of a method by irradiation with an electron beam and an electron beam may be adopted.
First, the rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention is prepared, for example, by the following method.

That is, the rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention comprises a Banbury mixer,
Addition of ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), rubber reinforcing agent, inorganic filler, softener, etc. by internal mixer (closed mixer) such as kneader and intermix 80-1
After kneading at a temperature of 70 ° C. for 3 to 10 minutes, using a roll such as an open roll or a kneader,
The iH group-containing compound (B) and, if necessary, a catalyst (C), a reaction inhibitor (D), a vulcanization accelerator, a crosslinking assistant, a foaming agent, and a foaming assistant are additionally mixed, and the roll temperature is 80 ° C. or lower. And then kneading for 1 to 30 minutes, followed by dispensing.

When the kneading temperature in the internal mixers is low, the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), the SiH group-containing compound (B), the rubber reinforcing agent, An antioxidant, a colorant, a dispersant, a flame retardant, a foaming agent, and the like may be simultaneously kneaded together with a filler, a softener, and the like.

The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention prepared as described above can be prepared by various methods using an extruder, a calender roll, a press, an injection molding machine, a transfer molding machine and the like. According to the molding method, it is formed into an intended shape, and can be cross-linked simultaneously with molding or by introducing the molded product into a vulcanization tank.
A crosslinked product can be obtained by heating at a temperature of 80 to 270 ° C. for 1 to 30 minutes, or by irradiating light, γ-ray or electron beam by the method described above. In addition, crosslinking can be performed at room temperature.

In this crosslinking step, a mold may be used,
Crosslinking may be performed without using a mold. When a mold is not used, the steps of molding and crosslinking are usually performed continuously. As a heating method in the vulcanization tank, a heating tank such as hot air, a fluidized bed of glass beads, UHF (ultra-high frequency electromagnetic wave), and steam can be used.

[0116]

The rubber composition for a crosslinkable hydraulic cylinder seal according to the present invention has a high crosslinking speed and excellent productivity.
Hot air vulcanization such as HAV (hot air vulcanizing tank) and UHF (ultra-high frequency electromagnetic wave) are possible, and properties such as scratch resistance, compression set resistance, heat aging resistance, liquid resistance, and strength properties It is possible to provide a crosslinked rubber molded product (including a foamed product) for a hydraulic cylinder component, which is excellent in quality.

Since the hydraulic cylinder component according to the present invention is made of a crosslinked rubber molded article having the above-mentioned effects, it is widely used for applications such as cup seal materials for automobiles and seal materials for industrial machinery.

[0118]

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

The composition, iodine value, intrinsic viscosity [η], molecular weight distribution (M
w / Mn), γ ₂ / γ ₁ , effective network chain density (ν), γ ₂ /
relationship between the gamma ₁ effective network chain density (index of crosslinking density), branching index, was determined by measurement or calculation by the following method. (1) Composition of copolymer rubber The composition of the copolymer rubber was measured by ¹³ C-NMR method. (2) Iodine value of copolymer rubber The iodine value of the copolymer rubber was determined by a titration method. (3) Intrinsic viscosity [η] The intrinsic viscosity [η] of the copolymer rubber was measured in 135 ° C decalin. (4) Molecular Weight Distribution (Mw / Mn) The molecular weight distribution of the copolymer rubber was determined by the ratio (Mw) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by GPC.
w / Mn). For GPC, GMH-HT and GMH-HTL manufactured by Tosoh Corporation were used for the column, and orthodichlorobenzene was used for the solvent. (5) The melt flow curve at 100 ° C. of the γ ₂ / γ ₁ copolymer rubber was determined, and the shear rate γ ₁ and the shear stress 2.4 × when the shear stress was 0.4 × 10 ⁶ dyn / cm ² were obtained. The ratio (γ ₂ / γ ₁ ) to the shear rate γ ₂ when indicating 10 ⁶ dyn / cm ² was determined.

L / D = 60 mm / 3 mm (6) Effective mesh chain density (ν) According to JIS K 6258 (1993), the polymer was immersed in toluene at 37 ° C. for 72 hours, and the effective mesh chain density was calculated from the Flory-Rehner equation. Calculated.

[0121]

(Equation 1)

[0122] upsilon _R: volume fraction of pure rubber relative to the swollen vulcanized rubber pure rubber volume swollen in the (pure rubber volume + absorbed volume of solvent) mu: Rubber - interaction constant between the solvent = 0. 49 V ₀ : molecular volume of solvent ν (number / cm ³ ): effective network chain concentration. Number of effective mesh chains in 1 cm ^{3 of} pure rubber.

Preparation of sample: 0.01 g of dicumyl peroxide was added to 100 g of the copolymer rubber.
Kneading is performed at a kneading temperature of 50 ° C. using an 8-inch roll open roll according to the method described in the Japan Rubber Association Standard (SRIS), and the obtained kneaded material is press-vulcanized at 170 ° C. for 10 minutes to produce a sample. did. (7) Relationship between γ ₂ / γ ₁ and effective network chain density (index of crosslinking density) Log (γ ₂ / γ ₁ ) / ν was determined by calculation. (8) Branching index Complex viscosity η ^{* of} EPR having no long-chain branching (4 samples having different molecular weights) using a dynamic viscoelasticity tester ^.
Was measured.

0.01 rad / sec and 8 rad / sec
The complex viscosity η ^* at the time of c is obtained, and the complex viscosity η
_The vertical axis is _1L ^* (0.01 rad / sec), and the complex viscosity η
_2L ^* (8 rad / sec) is plotted on the horizontal axis, a reference line is created, and η _2L ^* = 1 on an extension of the line
Η _1L0 ^* at × 10 ³ / Pa · s was measured.

Next, similarly for the target sample,
The complex viscosity η ^* at 0.01 rad / sec and 8 rad / sec is determined, and the complex viscosity η _1B ^* (0.01ra
d / sec) on the vertical axis, the complex viscosity η _2B ^* (8 rad / s
ec) is plotted on the horizontal axis. This plot has a value larger than that of the reference line, and the longer the long-chain branching, the greater the distance from the reference line.

Next, the reference line is translated so as to pass over this plot, and the complex viscosity η ₂ ^* = 1 × 10 ³ / P
The intersection η _1B0 ^* with a · s was measured. The values of η _1L0 ^* and η _1B0 ^* measured as described above were applied to the following equation to calculate the branching index.

Branching index = (log η _1L0 ^* _−log η _1B0 ^* ) × 10 The above measurement conditions are as follows. -Reference samples: 4 types of EPR manufactured by Mitsui Chemicals, Inc., Tuffmer P-0280, P-048
0, P-0680, P-0880 (trade name) ・ Dynamic Viscoelasticity Tester (RDS): Rheometric
Company s Sample: A 2 mm sheet is punched out into a circle with a diameter of 25 mm for use.・ Temperature: 190 ° C ・ Strain rate: 1% ・ Frequency dependence: 0.001 to 500 rad / sec

[0128]

[Production Example 1] [Production of ethylene-propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1)] A stainless steel polymerization vessel having a substantial inner volume of 100 liters equipped with stirring blades (stirring speed = Using 250 rpm), terpolymerization of ethylene, propylene and 5-vinyl-2-norbornene was continuously performed. 60 liters of hexane, 3.7 kg of ethylene, 8.0 kg of propylene, and 48 parts of 5-vinyl-2-norbornene per hour were added to the liquid phase from the side of the polymerization vessel.
At a rate of 0 g, 50 liters of hydrogen, 48 mmol of VOCl ₃ as catalyst and 240 mmol of Al (Et) ₂ Cl.
Mmol, Al (Et) _1.5 Cl _1.5 was continuously fed at a rate of 48 mmol.

When the copolymerization reaction was carried out under the conditions described above, an ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) was obtained in a uniform solution state.

Thereafter, a small amount of methanol was added to the polymerization solution continuously withdrawn from the lower portion of the polymerization vessel to stop the polymerization reaction, and the polymer was separated from the solvent by steam stripping. Vacuum drying was performed for hours.

Table 1 shows the physical properties of the ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) obtained as described above.

[0132]

Preparation Examples 2 to 3 In Preparation Example 1, by changing the polymerization conditions as shown in Table 1, ethylene-propylene / 5-ethylidene-2-norbornene random copolymer rubber (A-2) having different properties was prepared. -Propylene dicyclopentadiene random copolymer rubber (A-3) was obtained. Table 1 shows the physical properties of the obtained copolymer rubbers (A-2) and (A-3).

[0133]

[Table 1]

[0134]

[Embodiment 1] First, ethylene-propylene-
5-vinyl-2-norbornene random copolymer rubber (A-
1) 100 parts by weight, 5 parts by weight of zinc oxide [Zinchua No. 1 manufactured by Sakai Chemical Industry Co., Ltd.], 1 part by weight of stearic acid [Tsubaki (trademark) manufactured by NOF CORPORATION], and carbon black [ 45 parts by weight of Seast 116G (trade name, manufactured by Tokai Carbon Co., Ltd .; arithmetic mean particle size: 38 mm) was kneaded using a Banbury mixer having a capacity of 1.7 liters.

The kneading method is as follows.
5-vinyl-2-norbornene random copolymer rubber (A-
1) was masticated for 30 seconds, and then Zinhua No. 1, stearic acid and carbon black were added and kneaded for 2 minutes. Thereafter, the ram is lifted and cleaned, and further kneaded for 1 minute, discharged at about 150 ° C., and the rubber compound (I-1)
I got This kneading was performed at a filling rate of 70%.

Next, 151 parts by weight of the compound (I-1) were added to an 8 inch roll (front roll surface temperature 30 ° C., rear roll surface temperature 30 ° C., front roll rotation speed 16 rpm,
C ₆ H ₅ −
2 parts by weight of a SiH group-containing compound (crosslinking agent) represented by Si (OSi (CH ₃ ) ₂ H) ₃ and 0.2 parts by weight of ethynylcyclohexanol as a reaction control agent were added and kneaded for 10 minutes. After adding 0.5 parts by weight of an isopropyl alcohol solution having a platinic acid concentration of 5% by weight and kneading for 5 minutes, the kneaded material (1) is separated into a sheet and heated at 40 ° C. for 6 minutes using a 50-ton press molding machine. By pressing, an uncrosslinked rubber sheet (I) having a thickness of 2 mm was prepared.

For the kneaded material containing a crosslinking agent before the heat curing, “t _c (90)” was used as a measure of the crosslinking rate at 160 ° C. using a JSR Curastometer type 3 (manufactured by Nippon Synthetic Rubber Co., Ltd.). It measured on condition of. The difference between the minimum value ML and the maximum value MH of the torque obtained from the crosslinking (vulcanization) curve is expressed by ME
(= MH−ML), and the time to reach 90% ME is t
_c (90) ".

Next, the above kneaded material (1) was heated and pressed at a mold temperature of 140 ° C. for 10 minutes using a 150-ton press molding machine (manufactured by Kotaki Seiki Co., Ltd.) to prepare a 2 mm-thick crosslinked sheet, which was then stretched. The properties, hardness test, heat aging characteristics, and liquid resistance were measured. The compression set is determined by the mold temperature 140
C. for 15 minutes, diameter 29.0 mm, thickness 12.7
mm was prepared using a block of a right cylindrical shape. These tests were performed according to the following methods. According (1) Tensile test JIS K6251, measurement temperature 23 ° C., subjected to tensile test at a tensile rate of 500 mm / min conditions to measure the intensity T _B and elongation E _B at break of the crosslinked sheet. (2) Hardness test According to JIS K6253, a durometer hardness test (type A) was performed at a measurement temperature of 23 ° C., and the hardness was calculated. (3) Heat aging test A heat aging test was performed in accordance with JIS K6257. That is, the crosslinked sheet is placed in an oven at 150 ° C. for 7 minutes.
After aging for 2 hours, a tensile test was performed at a measurement temperature of 23 ° C. and a tensile speed of 500 mm / min, and the elongation and strength at break of the crosslinked sheet were measured.
_R (T _B ) and elongation retention A _R (E _B ) were calculated. Also,
After aging the crosslinked sheet in an oven at 150 ° C. for 72 hours, the measurement temperature was 2 in accordance with JIS K6253.
Perform a durometer hardness test (type A) at 3 ° C.
The hardness after aging is calculated, and the hardness change A before aging and after aging A
_H was calculated. (4) Liquid resistance test According to JIS K6253, the crosslinked rubber sheet was heated at 150 ° C.
Was immersed in the DOT-3 brake fluid for 70 hours, and the degree of swelling of the crosslinked rubber sheet was calculated. (5) Compression set test A compression set test was performed according to JIS K6262 (1993). This test condition is 150 ° C. × 22 hrs
It is.

Next, the uncrosslinked rubber sheet (I) was
It was left in a 0 ° C. atmosphere HAV (hot air vulcanizing tank) for 5 minutes to produce a crosslinked sheet without pressure. The obtained crosslinked sheet was subjected to a scratch resistance test according to the following method. [Scratch resistance test] The surface of the crosslinked sheet immediately after being taken out from HAV (hot air vulcanizing tank) was scratched with a pencil of HB, the scratched state was visually observed, and the scratch resistance was evaluated in four steps. . <Four-step evaluation of scratch resistance> A: No scratch on the surface B: Slight scratch on the surface C: Scratched D: Extremely severe scratch The results are shown in Table 2. .

[0140]

[Comparative Example 1] In Example 1, ethylene-propylene-5-vinyl as shown in Table 1 was used in place of the ethylene-propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) used in Example 1. Mold temperature during hot pressing was 170 ° C using -ethylidene-2-norbornene copolymer rubber (A-2)
The procedure was performed in the same manner as in Example 1 except for changing to. In addition,
The temperature of the kneaded material when discharged from the Banbury mixer is 1
34 ° C.

Table 2 shows the results.

[0142]

COMPARATIVE EXAMPLE 2 In Example 1, the ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) used in Example 1 was replaced with an ethylene / propylene / diethylene copolymer shown in Table 1. Using cyclopentadiene random copolymer rubber (A-3), mold temperature during hot pressing is 170 ° C
The procedure was performed in the same manner as in Example 1 except for changing to. In addition,
The temperature of the kneaded material when discharged from the Banbury mixer is 1
32 ° C.

Table 2 shows the results.

[0144]

Comparative Example 3 In Comparative Example 1, C ₆ H ₅ —Si (OSi
Instead of 2 parts by weight of a compound containing a SiH group represented by (CH ₃ ) ₂ H) ₃ , 0.2 parts by weight of ethynylcyclohexanol and 0.5 parts by weight of an isopropyl alcohol solution having a chloroplatinic acid concentration of 5% by weight, dicumyl was used. Peroxide (D
CP) The same procedure as in Comparative Example 1 was carried out except that 1.7% by weight of a 100% concentration product was used and the mold temperature during hot pressing was changed to 170 ° C.

Table 2 shows the results.

[0146]

Comparative Example 4 In Example 1, ethylene-propylene-dicyclopentadiene random copolymer rubber shown in Table 1 was used instead of the ethylene-propylene / 5-ethylidene-2-norbornene random copolymer rubber (A-2). (A-
3) used, _{and, C 6 H 5 -Si (OSi} (CH 3)
SiH group-containing compound 2 parts by weight represented by ₂ H) _3, in place of the isopropyl alcohol solution 0.5 parts by weight of ethynyl cyclohexanol, 0.2 part by weight and chloroplatinic acid concentration of 5 wt%, CBS as vulcanization accelerator [Product name: Suncellar CM, manufactured by Sanshin Chemical Industry Co., Ltd.] 0.5 parts by weight, Z
nBDC [trade name: Suncellar BZ, manufactured by Sanshin Chemical Industry Co., Ltd.] 0.7 parts by weight, TMTD [tradename: Suncellar TT, Sanshin Chemical Industry Co., Ltd.] 0.7 parts by weight, DPT
T [Product name: Sun Cellar TRA, Sanshin Chemical Industry Co., Ltd.
0.5 parts by weight, TeEDC [Product name: Suncellar E
Z, manufactured by Sanshin Chemical Industry Co., Ltd.], and 0.5 parts by weight and 1.0 part by weight of sulfur were used.

Table 2 shows the results.

[0148]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08F 210/02 F04B 21/00 R (72) Inventor Takashi Shirata 3rd Chigusa Beach, Ichihara-shi, Chiba Mitsui Chemicals Co., Ltd. (72) Inventor Masaaki Kawasaki, Chiba Pref. 3 Chizukaigan, Ichihara-shi, Chiba Mitsui Chemicals Co., Ltd. (72) Inventor: Yasushi Arino, 3rd Chigusa Coast, Ichihara City, Chiba Prefecture, Mitsui Chemicals Co., Ltd. (72) Inventor Satao Hirabayashi 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Inside Shin-Etsu Chemical Co., Ltd. (72) Inventor Takeo Yoshida Dai-jito, Matsuida-machi, Usui-gun, Gunma Prefecture 1F 10 Shin-Etsu Chemical Co., Ltd. F-term (reference) 3H071 AA03 BB01 CC26 DD51 EE08 4J002 BB101 BB151 CP042 DA008 DA048 DA058 DA117 DD077 DE197 DG018 EC038 EC077 EK018 EP018 ET008 EU178 EX036 EZ007 FD010 FD 020 FD 020 FD 020 FD 020 FD 020 AA12 AA28 AA59 AB01 AC13 AD01 AE15 AF18 4J100 AA02P AA03Q AA04Q AA15Q AA16Q AA17Q AA19Q AA21Q AS15R AU21R CA05 DA09 DA19 DA31 FA09 FA10 JA28

Claims (7)

[Claims] 1. A rubber composition which can be cross-linked by hot air and hot press. A hot air cross-linked rubber sheet obtained by forming the rubber composition into a sheet and then cross-linking with hot air is subjected to a surface hardness test by a pencil hardness test using an HB pencil. A hot-pressed crosslinked rubber sheet obtained by forming the rubber composition into a sheet and then hot-pressing and crosslinking is obtained by (1) 150 ° C.
Compression set (CS) after heat treatment for 2 hours is 70% or less, (2) Volume change rate (ΔV) after immersion in DOT-3 brake fluid at 150 ° C. for 70 hours is -10 to + 50%
(3) Tensile strength retention after heat aging at 150 ° C. for 70 hours is 50 to 150%, elongation retention is 50% or more, and (4) Tensile strength of normal physical properties is 3 to 25 MPa. A rubber composition for a crosslinkable hydraulic cylinder seal, characterized by comprising: 2. The rubber composition according to claim 1, wherein the non-conjugated polyene has a constitutional unit derived from at least one norbornene compound having a terminal vinyl group represented by the following general formula [I] or [II]. It comprises a non-conjugated polyene random copolymer rubber (A) and a SiH group-containing compound (B) having at least two SiH groups in one molecule, and a crosslinking rate of the rubber composition at 160 ° C ( 2. The rubber composition for a hydraulic cylinder seal according to claim 1, wherein t _c (90)) is 15 minutes or less; Wherein n is an integer of 0 to 10, R ¹ is a hydrogen atom 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 ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) comprises (i) a molar ratio of ethylene to an α-olefin having 3 to 20 carbon atoms (ethylene / α-olefin). ) Is in the range of 50/50 to 75/25, (ii) the iodine value is in the range of 1 to 30,
(Iii) the intrinsic viscosity [η] measured with a decalin solution at 135 ° C. is in the range of 0.3 to 2.5 dl / g, and (iv)
The rubber composition for a hydraulic cylinder seal according to claim 2, wherein a branching index determined by a dynamic viscoelasticity measuring device is 5 or more. 4. The rubber composition according to claim 1, further comprising an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and a SiH group-containing compound (B) having at least two SiH groups in one molecule. The rubber composition for a hydraulic cylinder seal according to claim 2, further comprising a catalyst (C). 5. The rubber composition according to claim 1, wherein the rubber composition is an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A),
In addition to the SiH group-containing compound (B) having at least two iH groups in one molecule and the catalyst (C), a reaction inhibitor (D)
The rubber composition for a hydraulic cylinder seal according to claim 4, comprising: 6. The rubber composition for a hydraulic cylinder seal according to claim 4, wherein the catalyst (C) is a platinum-based catalyst. 7. A hydraulic cylinder part comprising the rubber composition according to claim 1.