JP5758845B2 - Silicone rubber composition - Google Patents

Description

  The present invention relates to a silicone rubber composition.

  Silicone rubber has excellent weather resistance, electrical properties, low compression set, heat resistance, cold resistance, and other properties, so it can be used in various fields including electrical equipment, automobiles, architecture, medical care, and foods. Widely used. For example, remote controllers, typewriters, word processors, computer terminals, keypads used as rubber contacts for musical instruments, etc., rubber gaskets for architectural gaskets, audio equipment, etc .; automotive parts such as connector seals, spark plug boots, etc. Uses such as packing for compact discs, bread and cake molds to be used.

  These silicone rubbers are generally supplied in the form of a composition containing a highly polymerized organopolysiloxane and a reinforcing filler. This composition is prepared by mixing a reinforcing filler and various dispersants with a raw material polymer using a mixing apparatus such as a dough mixer and a two-roller. Reinforcing fillers such as organopolysiloxane and silica are electrically insulating materials, and the silicone rubber composition obtained by blending them and the cured silicone rubber are charged by contact with various substances, resulting in static electricity. There are problems such as generation of dust and adsorption of dust in the air.

  Conventionally, antistatic rubbers use polyether (Patent Document 1) or carbon black (Patent Document 2, Patent Document 3) as an antistatic agent. When a polyether type is used, there is a problem that the polyether is decomposed at a high temperature and a sufficient antistatic effect is not exhibited. When carbon black is used, there has been a problem that it is difficult to maintain electrical insulation or it is limited to black. Moreover, although the resin composition which added ion conductive compounds, such as lithium salt, is also proposed (patent documents 4-15), in antistatic performance in an insulating resin composition, it was not fully satisfactory. .

Special table 2002-500237 Special table 2002-507240 JP 2002-327122 A JP 2003-82232 A JP 07-188455 A JP 09-302232 A JP 2001-164118 A JP 2003-307895 A JP 2004-331786 A JP 2006-225422 A JP 2008-266212 A JP 2008-291122 A JP 2009-221364 A JP 2011-201951 A WO2009 / 084733

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an insulating silicone rubber composition excellent in antistatic performance.

  In order to achieve the above object, the present invention contains 0.0001 to 5 parts by mass of an ion conductive antistatic agent selected from silicone-modified zwitterionic compounds with respect to 100 parts by mass of the thermosetting silicone rubber composition. An insulating silicone rubber composition is provided.

  Such an insulating silicone rubber composition can have excellent antistatic performance.

  In this case, the thermosetting silicone rubber composition is preferably an addition reaction curable type or an organic peroxide curable type.

［式中Ｒ^１、Ｒ^２、Ｒ^３は、同一でも異なっていてもよい炭素数１から６のアルキル基、アリール基、及びフッ素置換アルキル基、水酸基含有ヒドロキシアルキル基及び下記式（２）で表わされるウレタン結合を有するオルガノポリシロキサン構造のいずれかを示し、Ｒ^１、Ｒ^２、Ｒ^３のうち２つは環を形成してもよく、その場合はアルキレン基を表わす。Ｒ^１、Ｒ^２、Ｒ^３のうち少なくとも１つは下記式（２）の構造を示す。ｌは３から６の整数である。

（式中Ｒ^４は炭素数１から８の１価の有機基またはシロキサン結合を有する基であり、Ｒ^５、Ｒ^６、Ｒ^７は各々炭素数１から８の１価の有機基、シロキサン結合を有する基、及び−ＯＳｉＲ^８Ｒ^９Ｒ^１０で示されるシロキシ基（Ｒ^８、Ｒ^９、Ｒ^１０は各々炭素数１から８の１価の有機基）のいずれかである。ｍは１から４の整数、ｎは１から１０の整数、ａは０から２の整数である。）］ Furthermore, the silicone-modified zwitterionic compound represented by the following formula (1) is a silicone-modified zwitterionic compound having a quaternary ammonium cation moiety and a sulfonate ion anion moiety in the same molecule. An insulating silicone rubber composition is provided.

[Wherein R ¹ , R ² , R ³ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms, an aryl group, a fluorine-substituted alkyl group, a hydroxyl group-containing hydroxyalkyl group, and the following formula (2): One of the organopolysiloxane structures having a urethane bond represented is shown, and ^{two of} R ¹ , R ² and R ³ may form a ring, in which case they represent an alkylene group. At least one of R ¹ , R ² and R ³ has the structure of the following formula (2). l is an integer of 3 to 6.

(In the formula, R ⁴ is a monovalent organic group having 1 to 8 carbon atoms or a group having a siloxane bond, and R ⁵ , R ⁶ and R ⁷ are each a monovalent organic group having 1 to 8 carbon atoms and a siloxane bond. And a siloxy group represented by -OSiR ⁸ R ⁹ R ¹⁰ (R ⁸ , R ⁹ and R ¹⁰ are each a monovalent organic group having 1 to 8 carbon atoms), m is 1 4 is an integer, n is an integer from 1 to 10, and a is an integer from 0 to 2.)]

  If such a silicone-modified zwitterionic compound is used, it can have further excellent antistatic performance.

In particular, if the silicone-modified zwitterionic compound is a silicone-modified zwitterionic compound in which n is 3, R ⁴ , R ⁵ , R ⁶ is a methyl group and a is 0 in the formula (2), Furthermore, it can have excellent antistatic performance.

  An insulating silicone rubber composition is provided wherein the silicone-modified zwitterionic compound is pasted with an organopolysiloxane.

  In such an insulating silicone rubber composition, the silicone-modified zwitterionic compound previously kneaded with the organopolysiloxane improves the dispersibility in the silicone rubber composition and has a more stable effect. By exhibiting it, it can have further excellent antistatic performance.

  As described above, according to the insulating silicone rubber composition of the present invention, it has excellent antistatic performance and can ensure sufficient insulation.

As a result of intensive studies, the inventors have found that an insulating silicone rubber composition excellent in antistatic performance can be obtained by adding a silicone-modified zwitterionic compound to a thermosetting silicone rubber composition. And found the present invention. That is, the present invention is an insulating silicone rubber composition characterized by containing 0.0001 to 5 parts by mass of a silicone-modified zwitterionic compound with respect to 100 parts by mass of a thermosetting silicone rubber composition.
The present invention will be described in detail below.

[Thermosetting silicone rubber composition]
The thermosetting silicone rubber composition is not particularly limited as long as it is a silicone rubber composition that is cured by heating. However, if necessary, organopolysiloxane having at least two alkenyl groups in the molecule as a base polymer, reinforcing silica, etc. It is preferable to use an addition reaction type curing agent, an organic peroxide curing agent, or both of them as a curing agent. The shape may be a millable type or a liquid type.

<(A): Organopolysiloxane having at least two alkenyl groups in the molecule>
As the base polymer of the thermosetting silicone rubber composition, (A): organopolysiloxane having at least two alkenyl groups in the molecule can be used. Here, what is shown by the following average compositional formula (I) can be used as organopolysiloxane of (A) component.
RaSiO _{(4-a) / 2} (I)
(Wherein R is the same or different from each other, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is a positive number of 1.8 to 2.3.)

  Here, R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms which is the same or different from each other as described above, preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms. . Specifically, carbon such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. C1-C10 aryl groups such as alkyl groups, phenyl groups, tolyl groups, xylyl groups, naphthyl groups, aralkyl groups such as benzyl groups, phenylethyl groups, phenylpropyl groups, vinyl groups, allyl groups , A propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, a cyclohexenyl group, an octenyl group, etc., and an alkenyl group having 2 to 10 carbon atoms, or a part or all of the hydrogen atoms of these groups may be fluorine, bromine, chlorine Substituted with a halogen atom, a cyano group, etc., such as a chloromethyl group, a chloropropyl group, a bromoethyl group, Li fluoropropyl group, cyanoethyl group and the like. Among these, a methyl group, a vinyl group, a phenyl group, and a trifluoropropyl group are preferable, and it is preferable that at least 50 mol%, particularly 80 mol% or more of R is a methyl group. In this case, at least two of R must be alkenyl groups (preferably those having 2 to 8 carbon atoms, more preferably 2 to 6, particularly preferably vinyl groups). The alkenyl group content in R is preferably 0.0001 to 20 mol%, particularly 0.001 to 10 mol%. The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both.

  a is a positive number of 1.8 to 2.3, preferably 1.9 to 2.1, and the organopolysiloxane of the component (A) is basically linear but impairs rubber elasticity. There may be partial branching within the range. The molecular weight is not particularly limited and can be used from a low-viscosity liquid to a high-viscosity raw rubber-like one. However, in order to cure and become a rubber-like elastic body, the degree of polymerization is 100 to 100,000, especially It is preferable that it is 150-20,000.

  Moreover, you may contain the organopolysiloxane of said (A) component individually by 1 type or in mixture of 2 or more types from which molecular structure and a polymerization degree differ.

  The organopolysiloxane of component (A) can be opened by a known method, for example, by (co) hydrolytic condensation of one or more organohalogenosilanes, or by using a cyclic polysiloxane with an alkaline or acidic catalyst. It can be obtained by ring polymerization.

<Reinforcing silica>
The thermosetting silicone rubber composition preferably contains (B): reinforcing silica as a filler in the organopolysiloxane as the component (A) in order to impart mechanical strength and the like.
(B): Examples of reinforcing silica include fumed silica and precipitated (wet) silica. Preferably these silicas have BET specific surface area is ^{50 m} 2 / g or more, it is preferred in particular 100 to 400 m ² / g.

The blending of the reinforcing silica of the component (B) is optional, and may be 0 to 100 parts by mass, preferably 1 to 80 parts by mass, particularly preferably 5 to 100 parts by mass of the organopolysiloxane of the component (A). -50 mass parts.
If the blending amount of the reinforcing silica of the component (B) is too small, the reinforcing effect may be insufficient, and if it is too large, the workability may be reduced or the rubber elasticity of the cured product may be reduced.

Such reinforcing silica of component (B) may be used after surface treatment with a surface treating agent such as organopolysiloxane, silazane, chlorosilane, alkoxysilane, etc., if necessary.
Further, when the reinforcing silica of the component (B) is blended with the organopolysiloxane of the component (A), the surface treatment agent may be blended.

  In addition to the organopolysiloxane of the component (A) and the reinforcing silica of the component (B), the thermosetting silicone rubber composition includes fillers such as pulverized quartz, crystalline silica, diatomaceous earth, and calcium carbonate as necessary. Colorants, tear strength improvers, heat resistance improvers such as iron oxide and cerium oxide, flame retardant improvers such as titanium oxide and platinum compounds, acid acceptors, thermal conductivity improvers such as alumina and boron nitride, release agents Thermosetting types such as various alkoxysilanes, especially phenyl group-containing alkoxysilanes and hydrolysates thereof, diphenylsilanediol, carbon functional silane, silano-group-containing low molecular siloxane, etc. It is optional to add known fillers and additives in the silicone rubber composition. Further, an antistatic agent such as an ion conductive compound such as a lithium salt or a polyether compound may be added.

  The thermosetting silicone rubber composition is preferably an addition reaction curable type or an organic peroxide curable type.

<(C): Curing agent>
(C): As described above, it is preferable to use (C-1) addition reaction type curing agent or (C-2) organic peroxide curing agent as described above.

  (C-1) As the addition reaction type curing agent, an organohydrogenpolysiloxane and a hydrosilylation catalyst can be used in combination.

The organohydrogenpolysiloxane may be linear, cyclic or branched as long as it contains 2 or more, preferably 3 or more, SiH groups in one molecule. As a crosslinking agent for the addition reaction curable silicone rubber composition, a known organohydrogenpolysiloxane, for example, an organohydrogenpolysiloxane represented by the following average composition formula (II) can be used.
R ¹¹ _{pH q} SiO _{(4-pq) / 2} (II)
In the above average composition formula (II), R ¹¹ represents an unsubstituted or substituted monovalent hydrocarbon group, which may be the same or different, and excludes an aliphatic unsaturated bond. preferable. Usually, those having 1 to 12 carbon atoms, particularly 1 to 8 carbon atoms are preferred. Specifically, alkyl groups such as methyl group, ethyl group and propyl group, cycloalkyl groups such as cyclohexyl group, vinyl group, allyl group and butenyl. Groups, alkenyl groups such as hexenyl groups, aryl groups such as phenyl groups and tolyl groups, aralkyl groups such as benzyl groups, 2-phenylethyl groups and 2-phenylpropyl groups, and some or all of the hydrogen atoms of these groups Is a group substituted with a halogen atom or the like, for example, a 3,3,3-trifluoropropyl group. Note that p and q are 0 ≦ p <3, preferably 1 ≦ p ≦ 2.2, 0 <q ≦ 3, preferably 0.002 ≦ q ≦ 1, 0 <p + q ≦ 3, preferably 1.002 ≦. It is a positive number satisfying p + q ≦ 3.

  The organohydrogenpolysiloxane has 2 or more, preferably 3 or more SiH groups in one molecule. This SiH group may be at the end of the molecular chain, in the middle of the molecular chain, or both.

  The organohydrogenpolysiloxane preferably has a kinematic viscosity at 25 ° C. of 0.5 to 10,000 cSt, particularly 1 to 300 cSt.

（式中、ｋは２〜１０の整数、ｓ及びｔは０〜１０の整数である。） Specific examples of such organohydrogenpolysiloxanes include compounds having the following structural formula.

(In the formula, k is an integer of 2 to 10, and s and t are integers of 0 to 10.)

  As for the compounding quantity of the said organohydrogenpolysiloxane, 0.1-40 mass parts is preferable with respect to 100 mass parts of (A) component organopolysiloxane. In addition, the ratio of hydrogen atoms bonded to silicon atoms (SiH groups) with respect to one aliphatic unsaturated bond (alkenyl group, etc.) of the organopolysiloxane of component (A) is suitably in the range of 0.5-10. A range of 0.7 to 5 is preferable. If it is 0.5 or more, crosslinking is sufficient and sufficient mechanical strength can be obtained. If it is 10 or less, physical properties after curing do not deteriorate, and particularly, heat resistance and compression set properties are obtained. It is good.

  The hydrosilylation catalyst is a catalyst that causes an addition reaction between the alkenyl group of the organopolysiloxane (A) and the silicon atom-bonded hydrogen atom (SiH group) of the organohydrogenpolysiloxane.

  Examples of the hydrosilylation catalyst include a platinum group metal catalyst, which includes a platinum group metal element and a compound thereof, and conventionally known catalysts for addition reaction curable silicone rubber compositions can be used. For example, particulate platinum metal adsorbed on a carrier such as silica, alumina or silica gel, platinum chloride, chloroplatinic acid, chloroplatinic acid hexahydrate alcohol solution, palladium catalyst, rhodium catalyst, etc. Platinum or platinum compounds are preferred. The addition amount of the catalyst may be a catalyst amount that can promote the addition reaction, and is usually used in the range of 1 ppm to 1% by mass with respect to the organopolysiloxane of the component (A) in terms of the platinum-based metal amount. A range of 10 to 500 ppm is preferred. If the addition amount is 1 ppm or more, the addition reaction is sufficiently accelerated and the curing is sufficient. On the other hand, if 1% by weight is added, sufficient reactivity can be obtained, which is economical.

  In addition to the hydrosilylation catalyst, an addition crosslinking controller may be used for the purpose of adjusting the curing rate. Specific examples include acetylene alcohol-based control agents such as ethynylcyclohexanol and tetracyclomethylvinylpolysiloxane.

  (C-2) Examples of the organic peroxide include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dicumyl peroxide, 2 , 5-dimethyl-bis (2,5-t-butylperoxy) hexane, di-t-butylperoxide, t-butylperbenzoate, 1,6-hexanediol-bis-t-butylperoxycarbonate, etc. Can be mentioned.

  (C-2) 0.1-10 mass parts is preferable with respect to 100 mass parts of (A) component organopolysiloxane, and, as for the addition amount of an organic peroxide, 0.2-5 mass parts is more preferable.

  The thermosetting silicone rubber composition is a kneader, a Banbury mixer, a two-roll kneading, etc., containing the organopolysiloxane as the component (A), the reinforcing silica as the component (B), and the curing agent as the component (C). However, it is preferable to add the curing agent of component (C) after mixing the organopolysiloxane of component (A) and the reinforcing silica of component (B).

  A commercially available thermosetting silicone rubber composition may be used.

[Silicone-modified zwitterionic compound]
The silicone-modified zwitterionic compound added to the thermosetting silicone rubber composition is a silicone-modified zwitterionic compound that is not an electronically conductive material such as carbon black.

［式中Ｒ^１、Ｒ^２、Ｒ^３は、同一でも異なっていてもよい炭素数１から６のアルキル基、アリール基、及びフッ素置換アルキル基、水酸基含有ヒドロキシアルキル基及び下記式（２）で表わされるウレタン結合を有するオルガノポリシロキサン構造のいずれかを示し、Ｒ^１、Ｒ^２、Ｒ^３のうち２つは環を形成してもよく、その場合はアルキレン基を表わす。Ｒ^１、Ｒ^２、Ｒ^３のうち少なくとも１つは下記式（２）の構造を示す。ｌは３から６の整数である。

（式中Ｒ^４は炭素数１から８の１価の有機基またはシロキサン結合を有する基であり、Ｒ^５、Ｒ^６、Ｒ^７は各々炭素数１から８の１価の有機基、シロキサン結合を有する基、及び−ＯＳｉＲ^８Ｒ^９Ｒ^１０で示されるシロキシ基（Ｒ^８、Ｒ^９、Ｒ^１０は各々炭素数１から８の１価の有機基）のいずれかである。ｍは１から４の整数、ｎは１から１０の整数、ａは０から２の整数である。）］ The silicone-modified zwitterionic compound is not particularly limited as long as it is a zwitterionic compound modified with silicone, but the quaternary ammonium cation moiety and the sulfonate ion in the same molecule represented by the following formula (1): A silicone-modified zwitterionic compound having an anion moiety is preferred.

[Wherein R ¹ , R ² , R ³ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms, an aryl group, a fluorine-substituted alkyl group, a hydroxyl group-containing hydroxyalkyl group, and the following formula (2): One of the organopolysiloxane structures having a urethane bond represented is shown, and ^{two of} R ¹ , R ² and R ³ may form a ring, in which case they represent an alkylene group. At least one of R ¹ , R ² and R ³ has the structure of the following formula (2). l is an integer of 3 to 6.

(In the formula, R ⁴ is a monovalent organic group having 1 to 8 carbon atoms or a group having a siloxane bond, and R ⁵ , R ⁶ and R ⁷ are each a monovalent organic group having 1 to 8 carbon atoms and a siloxane bond. And a siloxy group represented by -OSiR ⁸ R ⁹ R ¹⁰ (R ⁸ , R ⁹ and R ¹⁰ are each a monovalent organic group having 1 to 8 carbon atoms), m is 1 4 is an integer, n is an integer from 1 to 10, and a is an integer from 0 to 2.)]

When ^two of R ¹ , R ² and R ^{3 in} the formula (1) form a ring, those derived from amines such as pyrrolidine and piperidine are used, and specific examples thereof include 1- (2- Hydroxyethyl) pyrrolidine, 4-hydroxypiperidine, 1-piperidineethanol.

  If such a silicone-modified zwitterionic compound is used, it can have further excellent antistatic performance.

などが例示される。これらは、１種単独で用いてもよく、あるいは２種以上を併用してもよい。
（上記式中、Ｍｅはメチル基、Ｂｕはブチル基である。） In particular, if the silicone-modified zwitterionic compound is a silicone-modified zwitterionic compound in which n is 3, R ⁴ , R ⁵ , R ⁶ is a methyl group and a is 0 in the formula (2), Furthermore, it can have excellent antistatic performance.
In particular,

Etc. are exemplified. These may be used alone or in combination of two or more.
(In the above formula, Me is a methyl group and Bu is a butyl group.)

  The silicone-modified zwitterionic compound may be used alone or in combination of two or more.

  The addition amount of the silicone-modified zwitterionic compound is 0.0001 to 5 parts by mass with respect to 100 parts by mass of the thermosetting silicone rubber composition. Preferably, it is 0.0005-3 mass parts, More preferably, it is 0.001-1 mass part, Most preferably, it is 0.001-0.5 mass part. When the addition amount of the silicone-modified zwitterionic compound is less than 0.0001 parts by mass, the antistatic effect is insufficient, and when it is more than 5 parts by mass, the insulation is not maintained or the physical properties and heat resistance of the silicone rubber are not maintained. Adversely affects

  In the production of the insulating silicone rubber composition of the present invention, the silicone-modified zwitterionic compound may be added to the thermosetting silicone rubber composition or may be added during the production of the thermosetting silicone rubber composition. Good.

  The silicone-modified zwitterionic compound is preferably pasted with an organopolysiloxane, and more preferably mixed using a three-roll.

Thus, when the silicone-modified zwitterionic compound is kneaded with organopolysiloxane in advance to form a paste, the silicone-modified zwitterionic compound improves dispersibility in the silicone rubber composition and is more stable. The effect can be demonstrated.
The organopolysiloxane to be pasted may be raw rubber or oil, but dimethylpolysiloxane and methylvinylpolysiloxane are preferred. At this time, a part of the organopolysiloxane of the component (A) can be used as the organopolysiloxane.

  The insulating silicone rubber composition of the present invention becomes a silicone rubber having excellent insulating properties by heat curing. As a molding method, a known molding method can be selected according to the shape and size of the target molded product. For example, methods such as injection molding, compression molding, injection molding, calendar molding, extrusion molding, coating, and screen printing are exemplified.

  The curing conditions may be known conditions in the molding method, and are generally about several seconds to one day at a temperature of 60 ° C. to 450 ° C. Further, for the purpose of reducing the compression set of the cured product, reducing the low-molecular siloxane component remaining in the silicone rubber, or removing the decomposition product of the organic peroxide, it is preferably 200 ° C. or higher. May be post-cured (secondary cured) in an oven at 200 ° C. to 250 ° C. for 1 hour or longer, preferably 1 hour to 70 hours, more preferably 1 hour to 10 hours.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

[Charge measurement]
The charge amount was measured by the following method.
Using a static ones meter (manufactured by Sisid Electrostatic Co., Ltd.), the surface of the molded product was charged with static electricity by corona discharge, and then the time (half-life) when the charged voltage was halved was measured.

An antistatic paste was prepared as follows.
[Adjustment of antistatic paste]
42 parts by mass of dimethylpolysiloxane raw rubber blocked with dimethylvinylsiloxy groups at the end, 8 parts by mass of hydrophobized fumed silica (R-972, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 110 m ² / g Then, 50 parts by mass of adipic acid ester containing 20% by mass of the silicone-modified zwitterionic compound having the following structure was kneaded to prepare an antistatic paste 1.

As an antistatic agent, 42 parts by mass of dimethylpolysiloxane raw rubber whose ends are blocked with dimethylvinylsiloxy groups, and hydrophobized fumed silica having a specific surface area of 110 m ² / g (R-972, manufactured by Nippon Aerosil Co., Ltd.) 50 parts by mass of adipic acid ester containing 8 parts by mass and 20% by mass of the silicone-modified zwitterionic compound having the following structure was kneaded to prepare an antistatic agent paste 2.

As an antistatic agent, 42 parts by mass of dimethylpolysiloxane raw rubber whose ends are blocked with dimethylvinylsiloxy groups, and hydrophobized fumed silica having a specific surface area of 110 m ² / g (R-972, manufactured by Nippon Aerosil Co., Ltd.) ) 8 parts by mass of a polyether-modified silicone oil (KF351F manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 75 cs at 25 ° C. was kneaded to prepare an antistatic paste 3.

As an antistatic agent, 42 parts by mass of dimethylpolysiloxane raw rubber whose ends are blocked with dimethylvinylsiloxy groups, and hydrophobized fumed silica having a specific surface area of 110 m ² / g (R-972, manufactured by Nippon Aerosil Co., Ltd.) ) 8 parts by mass and 50 parts by mass of adipic acid ester containing 20% by mass of LiCF ₃ SO ₃ were mixed to prepare an antistatic agent paste 4.

Example 1
100 parts by mass of organopolysiloxane having 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxane units and having an average degree of polymerization of about 6000, specific surface area by BET method dimethyl have a group, a viscosity in the average degree of polymerization of 15, 25 ° C. is 30Cs - but 200 meters ² / g fumed silica (Aerosil 200 by Nippon Aerosil Co.) 45 parts by mass, both ends silanolate as a dispersant 10 parts by mass of polysiloxane was added, kneaded with a kneader, and heat-treated at 170 ° C. for 2 hours to prepare a composition.

0.04 parts by mass of the antistatic paste 1 and two 0.4 parts by mass of 2,5-dimethyl-2,5-bis (tbutylperoxy) hexane as a crosslinking agent for 100 parts by mass of the composition. After adding with a roll and mixing uniformly, press curing was performed for 10 minutes under the conditions of 165 ° C. and 70 kgf / cm ² to prepare a 2 mm thick sheet, and the charge amount was measured. The results are shown in Table 1.

(Example 2)
The charge amount was measured in the same manner as in Example 1 except that the antistatic agent used in Example 1 was changed to antistatic agent paste 2. The results are shown in Table 1.

(Comparative Example 1)
The charge amount was measured in the same manner as in Example 1 except that no antistatic agent was added. The results are shown in Table 1.

(Comparative Example 2)
The charge amount was measured in the same manner as in Example 1 except that the antistatic agent used in Example 1 was changed to antistatic agent paste 3. The results are shown in Table 1.

(Comparative Example 3)
The charge amount was measured in the same manner as in Example 1 except that the antistatic agent used in Example 1 was changed to antistatic agent paste 4. The results are shown in Table 1.

  From the results of Table 1, the time (half-life) when the charged voltage of the silicone rubber composition to which the silicone-modified zwitterionic compound of Examples 1 and 2 was added is halved compared with Comparative Examples 1, 2 and 3. It is clear that the insulating silicone rubber composition of the present invention is excellent in antistatic performance.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. It is contained in the technical range.

Claims (4)

0.0001 to 5 parts by mass of an ionic conductive antistatic agent selected from silicone-modified zwitterionic compounds per 100 parts by mass of the thermosetting silicone rubber composition , and the silicone-modified zwitterionic compound Is a silicone-modified zwitterionic compound having a quaternary ammonium cation moiety and a sulfonate ion anion moiety in the same molecule represented by the following formula (1) : .

[Wherein R ¹ , R ² , R ³ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms, an aryl group, a fluorine-substituted alkyl group, a hydroxyl group-containing hydroxyalkyl group, and the following formula (2): One of the organopolysiloxane structures having a urethane bond represented is shown, and ^{two of} R ¹ , R ² and R ³ may form a ring, in which case they represent an alkylene group. At least one of R ¹ , R ² and R ³ has the structure of the following formula (2). l is an integer of 3 to 6.

(In the formula, R ⁴ is a monovalent organic group having 1 to 8 carbon atoms or a group having a siloxane bond, and R ⁵ , R ⁶ and R ⁷ are each a monovalent organic group having 1 to 8 carbon atoms and a siloxane bond. And a siloxy group represented by -OSiR ⁸ R ⁹ R ¹⁰ (R ⁸ , R ⁹ and R ¹⁰ are each a monovalent organic group having 1 to 8 carbon atoms), m is 1 4 is an integer, n is an integer from 1 to 10, and a is an integer from 0 to 2.)]   2. The insulating silicone rubber composition according to claim 1, wherein the thermosetting silicone rubber composition is an addition reaction curable type or an organic peroxide curable type. The silicone-modified zwitterionic compound is a silicone-modified zwitterionic compound in which n is 3, R ⁴ , R ⁵ , R ⁶ are methyl groups and a is 0 in the formula (2) The insulating silicone rubber composition according to claim 1 or 2 . The insulating silicone rubber composition according to any one of claims 1 to 3 , wherein the silicone-modified zwitterionic compound is pasted with an organopolysiloxane.