JP2005336291A - Rubber composition for sealing electric/electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition having not only strength characteristics and operability, but also excellent electric insulation and sealing properties, and suitable as a sealing material for electric/electronic parts. <P>SOLUTION: The rubber composition comprises (A) an ethylene-α-olefin-nonconjugated polyene random copolymer rubber, (B) optionally an organopolysiloxane, (C) an SiH group-containing compound having two or more SiH groups in one molecule, (D) 0-300 pts. wt. carbon black based on 100 pts. wt. total of the components (A) and (B), and (E) 1-300 pts. wt. inorganic filler except wet-process silica. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition suitable for sealing electric / electronic parts. More specifically, the present invention relates to a rubber composition suitable for sealing electrical / electronic parts, comprising an ethylene / α-olefin / non-conjugated polyene copolymer.

  For sealing parts such as electric and electronic parts, low-cost materials with excellent heat resistance, acid resistance, gas permeability and high-speed moldability are required. At present, fluorine is used for heat resistance and acid resistance. For rubber, butyl rubber is used for gas permeation resistance, and silicone rubber is used for heat resistance and moldability. However, ordinary materials are not sufficient for high speed moldability requirements. A method using liquid silicone rubber and applying LIM (Liquid Injection Molding) has been considered. However, although silicone rubber is excellent in heat resistance and high-speed moldability, it is inferior in acid resistance and gas permeation resistance (see, for example, Patent Document 1).

  In addition to workability, the sealing material for electric / electronic parts is required to have strength characteristics, body electrical insulation and sealing resistance. Electrical / electronic parts with further improved strength and sealing performance of conventionally known sealing materials There was a need for sealing materials.

The inventors of the present invention have arrived at the present invention as a result of diligently developing a material having performance as a sealing material for electric / electronic parts.
JP 2003-257456 A

  The present invention provides a rubber composition suitable for a sealing material for electric / electronic parts, which has excellent strength characteristics and sealing properties in addition to workability and electrical insulation resistance.

  The present invention also provides an electrical / electronic component sealing material comprising a rubber composition suitable for electrical / electronic component sealing material having excellent strength characteristics and sealing properties in addition to workability and electrical insulation resistance. .

  The present invention relates to an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), an organopolysiloxane (B) if necessary, and an SiH group-containing compound having at least two SiH groups in one molecule. (C) and 0 to 300 parts by weight of carbon black (D) and 1 to 300 parts by weight of an inorganic filler (E) other than wet silica with respect to 100 parts by weight of the total amount of (A) and (B). A rubber composition is provided.

  The rubber composition as described above, wherein the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) has a structural unit derived from at least one norbornene compound represented by the following general formula [I] or [II]: Is a preferred embodiment of the present invention.

（式［Ｉ］中、ｎは０ないし１０の整数であり、 Ｒ^１は水素原子または炭素原子数１〜１０のアルキル基であり、Ｒ^２は水素原子または炭素原子数１〜５のアルキル基である。）

(In the formula [I], 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. .)

（式［II］中、Ｒ^３は水素原子または炭素原子数１〜１０のアルキル基である。）

(In the formula [II], R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)

  The rubber composition described above in which the rubber composition further contains a catalyst (F) is a preferred embodiment of the present invention.

  The rubber composition described above in which the rubber composition further contains a reaction inhibitor (G) is a preferred embodiment of the present invention.

The rubber composition described above in which the volume specific resistance of the sheet obtained by crosslinking the composition is 1 × 10 ¹⁰ or more is a preferred embodiment of the present invention.
The rubber composition of the present invention is preferably used for a sealing material for electric / electronic parts.
The present invention also provides a sealing material for electric / electronic parts comprising a crosslinked product of the rubber composition described above.
The sealing material for electric / electronic parts of the present invention preferably has a volume resistivity of 1 × 10 ¹⁰ or more.

ADVANTAGE OF THE INVENTION According to this invention, in addition to an intensity | strength characteristic and workability | operativity, the rubber composition suitable for the sealing material for electrical / electronic components excellent in electrical insulation resistance and sealing resistance is provided.
Further, according to the present invention, in addition to strength characteristics and workability, a seal for electrical / electronic parts comprising a crosslinked rubber composition suitable for a sealing material for electrical / electronic parts having excellent electrical insulation resistance and sealing resistance. Material is provided.

  The present invention relates to an ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), an organopolysiloxane (B) if necessary, and an SiH group-containing compound having at least two SiH groups in one molecule. (C) and 0 to 300 parts by weight of carbon black (D) and 1 to 300 parts by weight of an inorganic filler (E) other than wet silica with respect to 100 parts by weight of the total amount of (A) and (B). A rubber composition containing the same is provided. Furthermore, this invention provides the sealing material for electrical / electronic components which consists of a crosslinked body of this rubber composition.

The rubber composition of the present invention is a low-cost crosslinked rubber molded product having a high crosslinking rate and excellent productivity of a crosslinked rubber molded product, and having excellent weather resistance, ozone resistance, heat aging resistance, and compression set resistance. In addition to workability and electrical insulation, it has properties suitable for electrical and electronic parts sealing materials that are excellent in strength and sealing properties.

Ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A)
The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) used in the present invention is preferably a random copolymer of ethylene, α-olefin and non-conjugated polyene.

  The α-olefin is preferably an α-olefin having 3 to 20 carbon atoms, specifically, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1 -Nonene, 1-decene, 1-undecene, 1-dodecene and the like. Among these, α-olefins having 3 to 10 carbon atoms are preferable, and propylene, 1-butene, 1-hexene, 1-octene and the like are particularly preferably used.

These α-olefins may be used alone or in combination of two or more.
The non-conjugated polyene used in the present invention can be appropriately selected from conventionally known ones. Among them, non-conjugated dienes are preferable.
Examples of preferable non-conjugated dienes are terminal vinyl group-containing norbornene compounds represented by the following general formula [I] or [II].

In the general formula [I], 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. It is.

R ¹ is an alkyl group having 1 to 10 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, Examples include n-pentyl group, isopentyl group, t-pentyl group, neopentyl group, hexyl group, isohexyl group, heptyl group, octyl group, nonyl group, decyl group and the like.
Specific examples of the alkyl group having 1 to 5 carbon atoms of R ² include alkyl groups having 1 to 5 carbon atoms among the specific examples of R ¹ described above.

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 for R ³ include the same alkyl groups as the specific examples of the alkyl group for R ¹ .

Specific examples of the norbornene compound represented by the general formula [I] or [II] include 5-methylene-2-norbornene, 5-vinyl-2-norbornene, and 5- (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- F Pthenyl) -2-norbornene, 5- (1,2-dimethyl-5-hexesyl) -2-norbornene, 5- (5-ethyl-5-hexenyl) -2-norbornene, 5- (1,2,3- And trimethyl-4-pentenyl) -2-norbornene. Among these, 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. These norbornene compounds can be used alone or in combination of two or more. 5-vinyl-2-norbornene is particularly preferable.

  In addition to the norbornene compound such as 5-vinyl-2-norbornene, the following non-conjugated polyene can be used in combination as long as the physical properties of the present invention are not impaired.

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

The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A)
The unit derived from (a) ethylene and the unit derived from (b) α-olefin are usually 40/60 to 95/5, preferably 50/50 to 90/10, more preferably 55/45 to 85 /. 15 and particularly preferably 60/40 to 80/20 in molar ratio [(a) / (b)]. Within this range, the balance of processability, strength characteristics, and cold resistance is excellent.

  The iodine value of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) of the present invention is usually 0.5 to 50 (g / 100 g), preferably 0.8 to 40 (g / 100 g). ), More preferably 1 to 30 (g / 100 g), particularly preferably 1.5 to 25 (g / 100 g), further preferably 5 to 15 (g / 100 g), more preferably 8 to 12 (g / 100 g). ), Most preferably 9 to 11 (g / 100 g). Within this range, the balance between sealing properties and heat aging resistance is excellent.

  The intrinsic viscosity [η] of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) of the present invention measured in decalin at 135 ° C. is usually 0.01 to 2 dl / g, preferably 0.8. 02 to 1.8 dl / g, more preferably 0.05 to 1.5 dl / g, particularly preferably 0.1 to 1.4 dl / g, still more preferably 0.2 to 1.0 dl / g, more preferably 0.2 to 0.5 dl / g, most preferably 0.2 to 0.35 dl / g. Within this range, the workability and strength characteristics are excellently balanced.

G of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) of the present invention
The molecular weight distribution (Mw / Mn) measured by PC is usually 2 to 100, preferably 2.0 to 75, more preferably 2.0 to 50, more preferably 2.0 to 10, and particularly preferably 2.0. ~ 5, most preferably 2.5-3.5.

The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) of the present invention comprises ethylene, α-olefin and non-conjugated polyene, VO (OR) _n X _3-n (wherein R is a hydrocarbon) X is a halogen atom, n is an integer of 0 or 1 to 3), or a vanadium compound represented by VX ₄ (X is a halogen atom); It can be obtained by copolymerization by a conventionally known method using a metallocene catalyst described in JP-A-9-40586. For a specific production method, International Publication WO 03/057777 can also be referred to.

  The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) used in the present invention is graft-modified with a polar monomer such as an unsaturated carboxylic acid or a derivative thereof (for example, an acid anhydride or ester). Also good.

Organopolysiloxane (B)
The organopolysiloxane [B] used as necessary in the present invention is represented by the following average composition formula (III).
R ¹ _t SiO _{(4-t) / 2} (・ ・ ・ ・ ・ III)
R ¹ in the above formula [III] represents an unsubstituted or substituted monovalent hydrocarbon group, usually having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, or a propyl group. Alkyl groups such as butyl group, hexyl group and octyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group and propenyl group; aryl such as cycloalkenyl group, phenyl group and tolyl group An aralkyl group such as a benzyl group or a phenylethyl group; or a halogenated hydrocarbon group in which part or all of the hydrogen atoms of these groups are substituted with an organic group such as a chlorine atom, a fluorine atom or a cyano group; A hydrocarbon group; and the like.

  In particular, a diphenylsiloxane unit in which the main chain of the organopolysiloxane is composed of dimethylsiloxane units or a part of the main chain of the dimethylpolysiloxane has a phenyl group, a vinyl group, a 3,3,3-trifluoropropyl group, or the like. , Methyl vinyl siloxane units, methyl-3,3,3-trifluoropropyl siloxane units and the like are suitable.

In this case, the organopolysiloxane [B] preferably has an aliphatic unsaturated group such as two or more alkenyl groups and cycloalkenyl groups in one molecule, preferably 0.01 to 20 mol% in R ¹ , particularly It is preferable that 0.02 to 10 mol% is an aliphatic unsaturated group, particularly a vinyl group.

  The aliphatic unsaturated group may be at the molecular chain end, in the middle of the molecular chain, or both, but is preferably at least at the molecular chain end.

In the formula [III], t is a positive number of 1.9 to 2.1.
Examples of the organopolysiloxane used in the present invention include those whose molecular chain ends are blocked with a trimethylsilyl group, a dimethylphenylsilyl group, a dimethylhydroxysilyl group, a dimethylvinylsilyl group, a trivinylsilyl group, or the like.

Particularly preferable examples of the organopolysiloxane used in the present invention include methyl vinyl polysiloxane, methyl phenyl vinyl polysiloxane, and methyl trifluoropropyl vinyl polysiloxane.

  Such an organopolysiloxane can be obtained by, for example, subjecting one or more organohalogenosilanes to (co) hydrolysis condensation, or cyclic polysiloxanes (such as siloxane trimers or tetramers) with alkalinity or It can be obtained by ring-opening polymerization using an acidic catalyst. These are basically linear diorganopolysiloxanes, but they may be a mixture of two or three or more different molecular structures.

The viscosity of the organopolysiloxane is preferably 100 centistokes (cSt) or more at 25 ° C., particularly preferably 100,000 to 100,000,000 cSt.
The degree of polymerization of the organopolysiloxane is preferably 100 or more, particularly preferably 3,000 to 20,000.

  In the present invention, the weight ratio of the (A) ethylene / α-olefin / non-conjugated polyene copolymer and (B) organopolysiloxane is usually 100: 0 to 5:95, preferably 100: 0 to 60. : 40, more preferably 100: 0 to 70:30. In the present invention, an embodiment in which the weight ratio of (A) the ethylene / α-olefin / non-conjugated polyene copolymer and (B) the organopolysiloxane is 100: 0 is also an embodiment.

SiH group-containing compound (C)
The SiH group-containing compound (C) used in the present invention reacts with the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) to act as a crosslinking agent. The molecular structure of this SiH group-containing compound (C) is not particularly limited, and it can be used in a conventionally produced resinous material such as a linear, cyclic, branched structure or three-dimensional network structure. It is necessary that one molecule contains at least 2, preferably 3 or more hydrogen atoms directly bonded to silicon atoms, that is, SiH groups.

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

In the above general composition 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 the valent 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 R ¹ . Of these, a methyl group, an ethyl group, a propyl group, a phenyl group, and a trifluoropropyl group are preferable, and a methyl group and a phenyl group are particularly preferable.

  Further, 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.

This SiH group-containing compound (B) is an organohydrogenpolysiloxane having preferably 2 to 1000, particularly preferably 2 to 300, and most preferably 4 to 200 silicon atoms in one molecule. Siloxane oligomers such as 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyltetracyclosiloxane, 1,3,5,7,8-pentamethylpentacyclosiloxane Molecular chain both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, molecular chain both ends trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both ends silanol group-blocked methylhydrogenpolysiloxane, both molecular chains End silanol-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends of molecular chain Methyl hydrogen siloxy group-blocked dimethylpolysiloxane with both molecular chain terminals with dimethylhydrogensiloxy groups methylhydrogenpolysiloxane capped at both molecular chain terminals blocked with dimethylhydrogensiloxy groups dimethylsiloxane-methylhydrogensiloxane copolymer, R ⁴ ₂ (H) consists of SiO _1/2 units and SiO _4/2 units, optionally R ⁴ ₂ SiO _1/2 units, R ⁴ ₂ SiO _2/2 units, R ⁴ (H) SiO _2/2 units, Mention may be made, for example, of silicone resins which may contain H) SiO _3/2 or R ⁴ SiO _3/3 units.

Examples of the methyl hydrogen polysiloxane blocked with trimethylsiloxy group at both ends of the molecular chain include, for example, a compound represented by the following formula, and further, in the following formula, a part or all of the methyl group is ethyl group, propyl group, phenyl group, trifluoropropyl group. And the like.
(CH ₃ ) ₃ SiO — (— SiH (CH ₃ ) —O—) _d —Si (CH ₃ ) ₃
[D in the formula is an integer of 2 or more. ]

As the dimethylsiloxane / methylhydrogensiloxane copolymer blocked with trimethylsiloxy group at both ends of the molecular chain, a compound represented by the following formula, and further, in the following formula, part or all of the methyl group is ethyl group, propyl group, phenyl group, Examples include compounds substituted with a trifluoropropyl group and the like.
(CH ₃ ) ₃ SiO — (— Si (CH ₃ ) ₂ —O—) _e — (— SiH (CH ₃ ) —O—) _f —Si (CH ₃ ) ₃
[In the formula, e is an integer of 1 or more, and f is an integer of 2 or more. ]

Examples of the methyl hydrogen polysiloxane blocked with silanol groups at both ends of the molecular chain include, for example, a compound represented by the following formula, and a part or all of the methyl group in the following formula: ethyl group, propyl group, phenyl group, trifluoropropyl group, etc. And the like.
HOSi (CH ₃ ) ₂ O — (— SiH (CH ₃ ) —O—) ₂ —Si (CH ₃ ) ₂ OH

Examples of the dimethylsiloxane / methylhydrogensiloxane copolymer blocked with silanol groups at both ends of the molecular chain include, for example, a compound represented by the following formula, and further a part or all of the methyl group in the following formula: an ethyl group, a propyl group, a phenyl group, Examples include compounds substituted with a trifluoropropyl group and the like.
HOSi (CH ₃ ) ₂ O — (— Si (CH ₃ ) ₂ —O—) _e — (— SiH (CH ₃ ) —O—) _f —Si (CH ₃ ) ₂ OH
[In the formula, e is an integer of 1 or more, and f is an integer of 2 or more. ]

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

Examples of the dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane having both ends of the molecular chain include, for example, compounds represented by the following formula, and further, in the following formula, a part or all of the methyl groups are ethyl, propyl, phenyl, trifluoro Examples thereof include compounds substituted with a propyl group or the like.
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 dimethylhydrogensiloxy group-blocked dimethyl siloxane / methyl hydrogen siloxane copolymer having both ends of the molecular chain include, for example, a compound represented by the following formula, and further a part or all of the methyl group in the following formula: ethyl group, propyl group, And compounds substituted with a phenyl group, a trifluoropropyl group, and 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 in the formula are each an integer of 1 or more. ]

  Such a compound can be produced by a known method, for example, octamethylcyclotetrasiloxane and / or tetramethylcyclotetrasiloxane and hexamethyldisiloxane or 1,3-dihydro-1,1 which can be a terminal group. And a compound containing a triorganosilyl group or a diorganohydrogensiloxy group, such as 1,3,3-tetramethyldisiloxane, in the presence of a catalyst such as sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid, etc. It can be easily obtained by equilibrating at a temperature of about ~ 40 ° C.

As said SiH containing compound, the compound represented by the following general formula is mentioned as a particularly preferable compound.
_{^{(R 4) m -Si - [}} - O- (Si (CH 3) 2 -O-) n -Si (CH 3) 2 H] 4-m
In the above general formula, R ⁴ has the same meaning as R ⁴ described above. M is 0 or 1, and n is an integer of 0-10. Further it can be mentioned the general formulas ethyl group some or all of the CH ₃ group in, a propyl group, a phenyl group, and compounds obtained by replacing a trifluoropropyl group.

  The SiH group-containing compound (C) of the present invention has SiH groups at both ends of the molecule among the above, or when branched, SiH groups are present at two or more of the molecular ends including the branched ends. What has is preferable. In this case, the strength characteristics and sealing properties of the cured product are particularly excellent.

  The SiH group-containing compound (C) is usually 0 with respect to a total of 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and the organopolysiloxane (B) used as necessary. 0.1 to 100 parts by weight, preferably 0.1 to 75 parts by weight, more preferably 0.1 to 50 parts by weight, still more preferably 0.2 to 30 parts by weight, still more preferably 0.2 to 20 parts by weight, More preferably 0.5 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, particularly preferably 2 to 5 parts by weight, and most preferably 3 to 5 parts by weight. When the SiH group-containing compound (B) is used in a proportion within the above range, a rubber composition capable of forming a crosslinked rubber molded article having excellent compression set resistance, moderate crosslinking density and excellent strength characteristics and elongation characteristics. can get.

  The ratio of SiH groups to aliphatic unsaturated groups involved in crosslinking of the ethylene / α-olefin / nonconjugated polyene random copolymer rubber (A) (SiH group / aliphatic unsaturated group) is usually 0.2. -20, preferably 0.5-10, more preferably 0.7-5, particularly preferably 0.8-1.5, most preferably 0.8-1.1.

Carbon black (D)
The carbon black (D) used in the present invention can be appropriately selected from conventionally known carbon blacks. As carbon black, those produced by a channel method, a furnace method, or other methods can be used, and the carbon black may be powdery or granular. There is no particular limitation on the particle size and specific surface area.

In the rubber composition of the present invention, the amount of carbon black used is 100 parts by weight based on the total amount of ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and organopolysiloxane (B). 0 to 300 parts by weight is desirable.

  In the rubber composition of the present invention, even if the use of carbon black is omitted, a rubber composition capable of providing a sealing material excellent in strength and sealing properties can be obtained. However, the improvement was further improved by adding carbon black. Strength is obtained. When carbon black is used, it is preferably 1 to 300 parts by weight with respect to 100 parts by weight of the total amount of (A) and (B). Even if carbon black is blended, the composition of the present invention can maintain suitable electrical insulation.

The amount of carbon black used in the present invention is more preferably in the following range expressed in parts by weight.
0 ≦ [(D) / [(A) + (B) + (D) + (E)] × 100 ≦ 20,
Preferably 0 ≦ [(D) / [(A) + (B) + (D) + (E)] × 100 ≦ 15
In the present invention, when (D) carbon black is used, the relationship between (D) carbon black and (E) inorganic filler (E) other than wet silica is such that (D) / (E) (mass ratio) is Preferably it is 0.05-2, More preferably, it is 0.1-1, More preferably, it is 0.2-0.7. Within this range, the balance of strength characteristics, electrical insulation and workability is excellent.

Inorganic fillers other than wet silica (E)
Examples of the inorganic filler include light calcium carbonate, heavy calcium carbonate, talc, clay, diatomaceous earth, and the like.
The type and blending amount of these inorganic fillers can be appropriately selected depending on the application, but the blending amount of the inorganic filler is usually ethylene / α-olefin / nonconjugated polyene random copolymer rubber (A) and polyolefins. It is 1-300 weight part with respect to 100 weight part of total amounts of (B), Preferably it is 1-200 weight part.
When wet silica is used as the inorganic filler, foaming occurs when heated and crosslinked, which is not preferable because strength characteristics and sealing properties are impaired.

Catalyst (F)
If desired, the rubber composition of the present invention may contain a catalyst (F). The catalyst (F) used as an optional component is an addition reaction catalyst, and the alkenyl group of the ethylene / α-olefin / nonconjugated polyene random copolymer rubber (A) component and the SiH group-containing compound (C) SiH. There is no particular limitation as long as it promotes an addition reaction with a group (hydrosilylation reaction of an alkene). For example, an addition reaction catalyst (periodic table) composed of a platinum group element such as a platinum-based catalyst, a palladium-based catalyst, or a rhodium-based catalyst. Group 8 metal catalysts such as Group 8 metals, Group 8 metal complexes, and Group 8 metal compounds), among which platinum catalysts are preferred from the standpoint of activity.

  The platinum-based catalyst may be a known one that is usually used for addition-curing type curing, such as a finely powdered platinum metal catalyst described in US Pat. No. 2,970,150, US Pat. No. 2,823, No. 218, chloroplatinic acid catalyst, U.S. Pat. No. 3,159,601 and U.S. Pat. No. 159,662, complex compounds of platinum and hydrocarbons, U.S. Pat. Complex of chloroplatinic acid and olefin described in US Pat. No. 5,516,946, platinum and vinylsiloxane described in US Pat. No. 3,775,452 and US Pat. No. 3,814,780 And complex compounds. More specifically, platinum alone (platinum black), chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, platinum-siloxane complex, or a carrier in which platinum carrier is supported on alumina, silica, etc. Is mentioned.

The palladium-based catalyst is composed of palladium, a palladium compound, palladium chloride acid, and the like, and the rhodium-based catalyst is composed of rhodium, rhodium compound, rhodium chloride acid, and the like.
Examples of the catalyst (F) other than the above include Lewis acid and cobalt carbonyl.

  The amount of chlorine contained in the catalyst (F) used in the present invention is preferably 1000 ppm or less. More preferably, it is 500 ppm or less, More preferably, it is 100 ppm or less, Most preferably, it is 10 ppm or less. When the catalyst (F) having a chlorine content within this range is used, a rubber composition having excellent metal corrosion resistance can be obtained.

  The amount of the catalyst (F) used is, for example, 0.1 to 100 with respect to the total amount of ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and organopolysiloxane (B) as Pt metal. 1,000 ppm by weight, preferably 0.1 to 10,000 ppm by weight, more preferably 1 to 5,000 ppm by weight, and particularly preferably 5 to 1,000 ppm by weight.

  When the catalyst (F) is used in a proportion within the above range, a rubber composition capable of forming a crosslinked rubber molded article having excellent curing speed, moderate crosslinking density and excellent strength properties and elongation properties can be obtained. If it is 100,000 ppm by weight or less, the cost is also advantageous.

  In the present invention, an uncrosslinked rubber molded article of the rubber composition not containing the catalyst (F) can be irradiated with light, γ rays, electron beams, etc. to obtain a crosslinked rubber molded article.

Reaction inhibitor (G)
The rubber composition of the present invention may contain a reaction inhibitor (G) as desired. Examples of the reaction inhibitor (G) used as an optional component in the present invention include benzotriazole, ethynyl group-containing alcohol (such as ethynylcyclohexanol), acrylonitrile, amide compound (such as N, N-diallylacetamide, N, N-diallyl). Benzamide, 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 and the like), sulfur, phosphorus, nitrogen, amine compounds, sulfur compounds, phosphorus compounds, tin, tin compounds, tetramethyltetravinylcyclotetrasiloxane, organic peroxides such as hydroperoxide, and the like.

  The reaction inhibitor (G) is 0 to 50 parts by weight with respect to a total of 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and the organopolysiloxane (B), usually 0. 0001-50 parts by weight, preferably 0.001-30 parts by weight, more preferably 0.005-20 parts by weight, still more preferably 0.01-10 parts by weight, particularly preferably 0.05-5 parts by weight, The amount is preferably 0.1 to 1 part by weight, particularly preferably 0.1 to 0.5 part by weight. If it is this range, it will be excellent in the balance of a crosslinking speed and scratch resistance.

Other Components Although the rubber composition of the present invention can be used as it is uncrosslinked, when it is used as a crosslinked product such as a crosslinked rubber molded product or a crosslinked rubber foam molded product, it can exhibit its characteristics most. it can.

  In the crosslinkable rubber composition of the present invention, a conventionally known rubber reinforcing agent, inorganic filler, anti-aging agent, processing aid, vulcanization accelerator, organic peroxidation, depending on the intended use of the cross-linked product. Additives such as products, crosslinking aids, foaming agents, foaming aids, colorants, dispersants, flame retardants, and the like can be blended within a range that does not impair the object of the present invention.

  The rubber reinforcing agent has an effect of improving mechanical properties such as tensile strength, tear strength, and wear resistance of the crosslinked rubber. Specific examples of such rubber reinforcing agents include carbons such as SRF, GPF, FEF, HAF, ISAF, SAF, FT, and MT, and those carbons that have been surface-treated with a silane coupling agent. Examples thereof include black, finely divided silicic acid, and silica.

Specific examples of silica include fumed silica and precipitated silica. These silicas may be surface-treated with a reactive silane such as hexamethyldisilazane, chlorosilane, or 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 blending amount of these rubber reinforcing agents can be appropriately selected depending on the application, but the blending amount of the rubber reinforcing agent is usually ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and organopolysiloxane. The maximum is 300 parts by weight, preferably 200 parts by weight at the maximum for 100 parts by weight of (B).

  Specific examples of the inorganic filler include light calcium carbonate, heavy calcium carbonate, talc, and clay.

  The type and blending amount of these inorganic fillers can be appropriately selected depending on the application, but the blending amount of the inorganic filler is usually ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and organopolysiloxane. The maximum is 300 parts by weight, preferably 200 parts by weight at the maximum for 100 parts by weight of (B).

  As the softener, a softener usually used for rubber can be used.

Specifically, petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and petroleum jelly;
Coal tar softeners such as coal tar and coal tar pitch;
Fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, coconut oil;
Tall oil;
sub;
Waxes such as beeswax, carnauba wax, lanolin;
Fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, barium stearate, calcium stearate, zinc laurate;
Examples thereof include synthetic polymer substances such as petroleum resins, atactic polypropylene, ethylene / α-olefin copolymers, and coumarone indene resins. Of these, petroleum softeners are preferably used, and process oil is particularly preferably used.

The blending 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, and sulfur-based anti-aging agents. These anti-aging agents are used within the range not impairing the object of the present invention as described above. It is done.
Examples of amine-based antioxidants used in the present invention include diphenylamines and phenylenediamines.

There are no particular restrictions on the type of amine-based antioxidant used, but 4,4 ′-(α, α-dimethylbenzyl) diphenylamine and N, N′-di-2-naphthyl-p-phenylenediamine are preferred.
These compounds can be used alone or in combination of two or more.

The hindered phenol-based anti-aging agent used in the present invention is not particularly limited, and for example, (1) tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′- Hydroxyphenyl) propionate methane,
(2) 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4-8,10- Tetraoxaspiro [5,5] undecane (3) 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol)
Etc. can be mentioned preferably.

As the sulfur-based anti-aging agent used in the present invention, a sulfur-based anti-aging agent usually used for rubber is used.
There are no particular restrictions on the sulfur-based antioxidant used, but in particular 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptomethylbenzimidazole, pentaerythritol- Tetrakis- (β-lauryl-thiopropionate) is preferred.

  As said processing aid, the compound used for processing of a normal rubber 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 aid is usually 10 parts by weight or less, preferably 100 parts by weight or less, preferably 100 parts by weight in total of ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and organopolysiloxane (B). Although it is used at a ratio of 5 parts by weight or less, it is desirable to appropriately determine the optimum amount according to the required physical property value.

  In the present invention, in addition to the catalyst (C) described above, an organic peroxide may be used to perform both addition crosslinking and radical crosslinking. The organic peroxide is used at a ratio of about 0.1 to 10 parts by weight with respect to 100 parts by weight in total of the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) and the organopolysiloxane (B). It is done. As the organic peroxide, a conventionally known organic peroxide that is usually used in crosslinking of rubber can be used.

  Moreover, when using an organic peroxide, it is preferable to use a crosslinking aid in combination. Specific examples of the crosslinking aid include 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 such as divinylbenzene. Such a crosslinking aid is used in an amount of 0.5 to 2 mol, preferably about equimolar to 1 mol of the organic peroxide used.

  In addition, the rubber composition according to the present invention can be used by blending with other known rubbers within a range that does not impair the object of the present invention. Examples of such other rubber include natural rubber (NR) and isoprene rubber (IR), isoprene-based rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and chloroprene rubber. Mention may be made of conjugated diene rubbers such as (CR).

Further, conventionally known ethylene / α-olefin copolymer rubbers can also be used. For example, ethylene / propylene random copolymer (EPR), ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A). Other ethylene / α-olefin / polyene copolymers (for example, EPDM) can be used.

  In the rubber composition according to the present invention, the (A) ethylene / α-olefin / non-conjugated polyene random copolymer rubber, (B) an organopolysiloxane used as necessary, (C) a SiH group-containing compound And (D) carbon black used as necessary, and (E) a total of 20 wt% or more of inorganic fillers other than wet silica, and preferably 30 wt% to 99.9 wt%, more preferably Is contained in an amount of 50 to 99.9% by weight, particularly preferably 70 to 99.9% by weight. The remaining components are optional components as described above.

Preparation of Rubber Composition and Crosslinked Rubber Molded Article As described above, the rubber composition of the present invention can be used without being cross-linked, but exhibits its characteristics most when used as a crosslinked rubber molded article. be able to.

In order to produce a crosslinked product from the rubber composition of the present invention, crosslinking can be carried out by a generally known crosslinking method.
Similar to general liquid rubbers, conventionally known rubber reinforcing agents, inorganic fillers, anti-aging agents, processing aids, vulcanization accelerators may be added to the rubber composition of the present invention depending on the intended use of the crosslinked product. , Organic peroxides, cross-linking aids, colorants, dispersants, flame retardants, and other additives are mixed together, and then this compounded rubber is molded into the intended shape (filled in the gaps or between objects) After coating, coating on an object, or potting an object), it is allowed to stand at room temperature for crosslinking (vulcanization). Moreover, you may heat in order to accelerate | stimulate a crosslinking reaction.

  That is, the rubber composition of the present invention can be prepared by mixing each component with a kneading apparatus such as a planetary mixer or a kneader.

  In the present invention, the ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) can be kneaded with the rubber reinforcing agent, the inorganic filler, etc. at a high temperature, but the SiH group-containing compound (B) When the SiH group-containing compound (B) and the catalyst (C) are added at the same time, the catalyst and the catalyst (C) may be cross-linked (scorched) when kneaded at a high temperature at the same time. It is preferable to knead. When one component is added among the SiH group-containing compound (C) and the catalyst (F), they can be kneaded even at a high temperature exceeding 80 ° C. In some cases, it is preferable to use cooling water against heat generated by kneading.

  Further, as a preferred method for preparing the rubber composition, an ethylene / α-olefin / non-conjugated polyene random copolymer (A), an inorganic filler (E), and optionally carbon black (D) and a SiH group-containing compound are used. A mixture obtained by kneading (C) or the like with a planetary mixer or the like is designated as A liquid. On the other hand, similarly, an ethylene / α-olefin / non-conjugated polyene random copolymer (A) component, an inorganic filler (E), and optionally a carbon black (D) and a catalyst (F) react as necessary. What added the inhibitor (G) is set as B liquid. An embodiment in which the composition is prepared by LIM molding the A liquid and the B liquid is preferable.

  The rubber composition of the present invention prepared as described above is filled in a gap, coated between objects, coated on an object, an extruder, a calender roll, a press, By various molding methods using an injection molding machine, a LIM molding machine, a transfer molding machine, etc., it is molded into the intended shape, and then allowed to stand at room temperature, whereby the crosslinking reaction proceeds and the desired crosslinked product can be obtained. . Moreover, in order to accelerate | stimulate a crosslinking reaction, it is preferable to bridge | crosslink by heating with various shaping | molding methods.

The rubber composition of the present invention has a volume resistivity of 1 × 10 ¹⁰ or more, preferably 1 for a sheet having a thickness of 1 mm obtained by press-crosslinking the composition at a pressure of 40 kgf / cm ² at 150 ° C. for 10 minutes. If it is × 10 ¹² or more, it shows preferable performance as a sealing material for electric / electronic parts, which is preferable.

The rubber composition of the present invention is a rubber composition particularly suitable for a sealing material for electric / electronic parts. Moreover, the sealing material for electrical / electronic parts made of the crosslinked body is a sealing material having excellent performance. Moreover, the sealing material for electrical and electronic parts of the present invention is preferable when the volume resistivity is 1 × 10 ¹⁰ or more, preferably 1 × 10 ¹² or more, since it shows suitable performance as a sealing material for electrical / electronic parts. In this case, the volume resistivity can be measured in accordance with SRIS 2301-1969 as in the examples described later after cutting a section from the sealing material.

Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples.
The physical property test in the present invention was performed according to the following method.

(1) Composition of copolymer (A) The composition of copolymer (A) was measured by ¹³ C-NMR method.
(2) Iodine value of copolymer (A) The iodine value of copolymer (A) was determined by a titration method.
(3) Intrinsic viscosity [η]
The intrinsic viscosity [η] of the copolymer (A) was measured at 135 ° C. in decalin.

According (4) Tensile test JIS K6251, measurement temperature 23 ° C., subjected to tensile test at a tensile rate of 500 mm / min condition was measured tensile strength _{T B} and elongation _{E B} at break of the crosslinked sheet.

(5) Metal corrosion resistance A contamination test was performed according to JIS K6267 (1996). As a material to be contaminated, steel F25C was used. The test was performed under the following conditions using a xenon arc lamp type weather resistance tester.
Thermostatic bath temperature: 70 ° C, irradiation time: 24 hours, irradiation method: continuous,
Surface temperature: 55 ° C at black panel temperature
Irradiance on surface of contaminated material: 550 w / m ² at wavelength of 300 to 800 nm
After the test, the degree of contamination was evaluated according to the following three levels.
A: The sheet metal was not contaminated B: The sheet metal was slightly contaminated C: The sheet metal was contaminated

(6) Acid resistance According to JIS K6258, after performing an immersion test in an acidic solution under the following conditions, tensile elongation, strength, and volume change rate were measured, and each change rate (hardness was changed) was obtained. .
(Immersion conditions)
25 ° C., 168 hours.
(Acid solution)
Hydrochloric acid 35% strength by weight solution.
(7) Electrical insulation The specific volume resistance of a sheet of 1 mm thickness obtained by press-crosslinking the composition at a pressure of 40 kgf / cm ² at 150 ° C. for 10 minutes was measured according to SRIS2301-1969.
(8) Compression set According to JIS K6262, a 2 mm sheet was laminated and compression set was measured.
Measurement conditions: 150 ° C x 72H

(Production Example 1) Production of ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) Stainless steel polymerizer having a stirring capacity of 100 liters and having a stirring volume (stirring speed = 250 rpm) Was used to continuously carry out terpolymerization of ethylene, propylene and 5-vinyl-2-norbornene. From the side of the polymerization vessel to the liquid phase, 60 liters of hexane per hour, 2.4 kg of ethylene, 2.5 kg of propylene, 230 g of 5-vinyl-2-norbornene, 230 liters of hydrogen, VOCl ₃ as a catalyst At a rate of 85 mmol, Al (Et) ₂ Cl at 255 mmol, and Al (Et) _1.5 Cl _1.5 at a rate of 255 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 is added to the polymerization solution continuously withdrawn from the lower part of the polymerization vessel to stop the polymerization reaction, and the polymer is separated from the solvent by a steam stripping treatment, followed by vacuum drying at 55 ° C. for 48 hours. Was done.

The ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) obtained as described above has an ethylene content of 58% by mass and a 5-vinyl-2-norbornene content of 4.7% by mass. %, Iodine value was 10 g / 100 g, and intrinsic viscosity [η] was 0.27 dl / g. The ethylene / propylene molar ratio was 68/32.
Table 1 shows the polymerization conditions and results.

100 parts by weight of the ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) produced above and 20 parts by weight of carbon black [Asahi Carbon Co., Ltd., trade name: Asahi 50HG] and the surface 40 parts by weight of treated clay [made by Tsuchiya Kaolin Co., Ltd., trade name: Translink 37] was kneaded with a 2 liter planetary mixer [trade name: PLM-2 type, manufactured by Inoue Seisakusho Co., Ltd.] (1) was obtained.
About the obtained compound (1), the viscosity was measured under the following conditions, and the LIM moldability was determined from the viscosity value according to the following criteria.

(A) Viscosity measurement Viscometer: Brookfield rotational viscometer Temperature: Room temperature Rotational speed: 1 rpm
Spongle: No. 6
(B) LIM moldability criteria ○: Viscosity is 1000 to 5000 PaS
Δ: Viscosity is more than 5000 to 10000 PaS
X: Viscosity exceeds 10,000 PaS

Next, 160 parts by weight of the compound (1) is expressed as SiH group-containing compound (C) (SiH group-containing compound (1)) represented by C ₆ H ₅ —Si (OSi (CH ₃ ) ₂ H) _3. 5 parts by weight, 0.4 part by weight of 1-ethynyl-1-cyclohexanol as reaction inhibitor (G), 1,3,5,7-tetravinyl-1,3,5,7 as catalyst (F) -Tetramethylcyclotetrasiloxane-platinum complex (2% platinum catalyst) [manufactured by Shin-Etsu Chemical Co., Ltd., trade name X-93-1410] 0.2 parts by weight is added, and 3 rolls of 3 inches φ After kneading 3 times by [manufactured by Kodaira Seisakusho Co., Ltd., trade name: 3 roll mill], it was pressed at 150 ° C. for 10 minutes using a 50-ton press molding machine to prepare a crosslinked rubber sheet having a thickness of 2 mm. The crosslinked rubber sheet was cut and the foamed state was observed.

  The sheet obtained as described above was subjected to a tensile test, compression set, metal corrosion, volume resistivity, and acid resistance test by the above methods. The results are shown in Table 1.

(Example 2)
In Example 1, it replaced with SiH group containing compound (1), and performed similarly to Example 1 except using the SiH group containing compound (henceforth SiH group containing compound (2)) represented by the following. It was.

  The obtained crosslinked rubber sheet was subjected to a tensile test, compression set, metal corrosivity, volume resistivity, and acid resistance test. The results are shown in Table 1.

(Example 3)
A crosslinked rubber sheet was obtained in the same manner as in Example 1 except that the catalyst was changed to a 2% chloroplatinic acid IPA solution in Example 1. The obtained crosslinked rubber sheet was subjected to a tensile test, compression set, metal corrosivity, volume resistivity, and acid resistance test. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, in place of 20 parts by weight of carbon black and 40 parts by weight of the surface treatment clay used in Example 1, except that 30 parts by weight of carbon black was used, the same as in Example 1, A crosslinked rubber sheet was obtained.
The obtained crosslinked rubber sheet was subjected to a tensile test, compression set, metal corrosivity, volume resistivity, and acid resistance test. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, in place of 20 parts by weight of carbon black and 40 parts by weight of the surface treatment clay used in Example 1, 30 parts by weight of silica [trade name Nipsil VN3, manufactured by Nippon Silica Industry Co., Ltd.] was used. Obtained a crosslinked rubber sheet in the same manner as in Example 1.
The obtained crosslinked rubber sheet was subjected to a tensile test, compression set, metal corrosivity, volume resistivity, and acid resistance test. The results are shown in Table 1.

(Comparative Example 3)
100 parts by weight of the ethylene / propylene / 5-vinyl-2-norbornene random copolymer rubber (A-1) obtained above and 20 parts by weight of carbon black [Asahi Carbon Co., Ltd., trade name: Asahi 50HG] 40 parts by weight of surface treatment clay [trade name: Translink 37, manufactured by Tsuchiya Kaolin Co., Ltd.] was kneaded with a 2 liter planetary mixer [trade name: PLM-2 type, manufactured by Inoue Seisakusho Co., Ltd.] Obtained.

  Next, 160 parts by weight of this blend, 1.5 parts by weight of sulfur, 2-mercaptobenzothiazole as a vulcanization accelerator [trade name Sunceller M] (accelerator 1) by Accelerator 1 5 parts by weight, tetramethylthiuram disulfide [manufactured by Sanshin Chemical Industry Co., Ltd., trade name Sunceller TT] (accelerator 2) 1.0 part by weight, zinc white 5 parts by weight and stearic acid 1 part by weight were added. After kneading three times with three rolls of inch φ (trade name, three rolls manufactured by Kodaira Seisakusho Co., Ltd.), pressurizing for 10 minutes at 150 ° C. using a 50-ton press molding machine and crosslinking with a thickness of 2 mm An attempt was made to prepare a rubber sheet, but a vulcanized rubber sheet capable of measuring physical properties was not obtained.

ADVANTAGE OF THE INVENTION According to this invention, in addition to an intensity | strength characteristic and workability | operativity, the rubber composition suitable for the sealing material for electrical / electronic components excellent in body electrical insulation and sealing resistance is provided.
Further, according to the present invention, in addition to strength characteristics and workability, a seal for electrical / electronic parts comprising a crosslinked rubber composition suitable for a sealing material for electrical / electronic parts having excellent electrical insulation resistance and sealing resistance. Material is provided.

Claims (9)

  An ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A), an organopolysiloxane (B) if necessary, and a SiH group-containing compound (C) having at least two SiH groups in one molecule; A rubber composition containing 0 to 300 parts by weight of carbon black (D) and 1 to 300 parts by weight of an inorganic filler (E) other than wet silica with respect to 100 parts by weight of the total amount of (A) and (B). Stuff. The ethylene / α-olefin / non-conjugated polyene random copolymer rubber (A) has a structural unit derived from at least one norbornene compound represented by the following general formula [I] or [II]. The rubber composition according to claim 1.

(In the formula [I], 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. .)

(In the formula [II], R ³ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)   The rubber according to claim 1 or 2, wherein the carbon black (E) is contained in an amount of 1 to 300 parts by weight with respect to 100 parts by weight of the total amount of (A) and (B). Composition.   The rubber composition according to any one of claims 1 to 3, wherein the rubber composition further contains a catalyst (F).   The rubber composition according to any one of claims 1 to 4, wherein the rubber composition further contains a reaction inhibitor (G). The rubber composition according to claim 1, wherein the sheet has a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more obtained by crosslinking the composition. 7. The rubber composition according to claim 1, wherein the rubber composition is used for a sealing material for electric / electronic parts.   A sealing material for electrical / electronic parts, comprising a crosslinked product of the rubber composition according to claim 1. 9. The sealing material for electrical / electronic parts according to claim 8, wherein the sealing material has a volume resistivity of 1 × 10 ¹⁰ or more.