JP4593592B2 - High temperature compression resistant silicone rubber composition - Google Patents

Description

  The present invention relates to a high temperature compression resistant silicone rubber composition. In detail, it is related with the silicone rubber composition used as the silicone rubber molding which has high resistance with respect to high temperature compression after hardening.

  Addition-curing silicone rubber composition containing vinyl group-containing organopolysiloxane, silicon atom-bonded hydrogen atom-containing organopolysiloxane, inorganic filler, and platinum-based catalyst has excellent heat resistance and electrical insulation after molding. Since it becomes a silicone rubber molded product having properties, it is used in large quantities in fields where these properties are required.

  In recent years, there has been a strong demand for heat resistance for silicone rubber molded products, and in particular, high resistance to compression at high temperatures has become necessary. Conventional high-temperature compression-resistant silicone rubber composition that enables a silicone rubber molded article having high resistance to compression under a temperature exceeding 200 ° C., because the conventional resistance to compression at a high temperature of 150 ° C. to 180 ° C. is insufficient. Development is desired.

  Therefore, in view of such a situation, an object of the present invention is to provide a high-temperature compression-resistant silicone rubber composition that enables a silicone rubber molded article having high resistance to compression under a temperature exceeding 200 ° C. is there.

The present invention provides a means for solving such a problem,
(A) 100 parts by weight of an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in the middle of the molecular chain,
(B) General formula (2):

(式中、R³はアルケニル基を含まない非置換又は置換の1価炭化水素基、Qは正の整数、Pは2以上の整数であり、但し、1＞P/(Q+P)＞0.2である。)
で表されるオルガノハイドロジェンポリシロキサン
(A)成分中のアルケニル基１個当り、ケイ素原子に結合した水素原子の数が0.1〜3.0となる量、
(C)白金系触媒 有効量、及び
(D)無機質充填剤 5〜500重量部
を含有してなる高温圧縮抵抗性シリコーンゴム組成物を提供するものである。

(Wherein R ³ is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, Q is a positive integer, P is an integer of 2 or more, provided that 1> P / (Q + P)> 0.2.)
Organohydrogenpolysiloxane represented by
(A) An amount in which the number of hydrogen atoms bonded to silicon atoms is 0.1 to 3.0 per alkenyl group in component (A),
(C) an effective amount of a platinum-based catalyst, and
(D) A high temperature compression resistant silicone rubber composition comprising 5 to 500 parts by weight of an inorganic filler is provided.

  According to the high temperature compression resistant silicone rubber composition of the present invention, a silicone rubber molded product having a high resistance to compression under a temperature exceeding 200 ° C. can be obtained.

Hereinafter, the present invention will be described in detail, particularly for each component of the composition.
[(A) Alkenyl group-containing organopolysiloxane]
The organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in the middle of the molecular chain as the component (A) used in the present invention is the main component of the present composition, preferably General formula (1):

(式中、Rは非置換又は置換の1価炭化水素基、R¹はアルケニル基を含まない非置換又は置換の1価炭化水素基、R²はアルケニル基 nは2以上の整数、mは0又は1以上の整数)
により表される、基本的に直鎖状のジオルガノポリシロキサンであることが望ましい。

Wherein R is an unsubstituted or substituted monovalent hydrocarbon group, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, R ² is an alkenyl group, n is an integer of 2 or more, and m is (0 or an integer greater than 1)
It is desirable that it is basically a linear diorganopolysiloxane represented by

R in the above formula (1) is an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, cyclohexyl and octyl; an aryl group such as phenyl, tolyl and xylyl; vinyl and allyl An unsubstituted monovalent hydrocarbon group usually having 1 to 10 carbon atoms, preferably about 1 to 8 carbon atoms, such as alkenyl groups such as propenyl, isopropenyl and butenyl groups, aralkyl groups such as benzyl groups, etc. A part of the hydrogen atoms of the unsubstituted monovalent hydrocarbon group is substituted with a halogen atom or the like, for example, a substituted monovalent hydrocarbon group such as a chloromethyl group or a trifluoropropyl group, and R ¹ is a non-substituted monovalent hydrocarbon group. Of substituted or substituted monovalent hydrocarbon groups, an unsubstituted or substituted monovalent hydrocarbon group excluding alkenyl groups such as vinyl and allyl groups. Of these, methyl and phenyl are preferred as R and R ¹ . R ² is an alkenyl group exemplified by vinyl and allyl groups. n is an integer of 2 or more, m is an integer of 0 or 1 and m + n is preferably a value satisfying the viscosity described later.

  The molecular structure of the organopolysiloxane of component (A) is essentially a straight chain in which the main chain is composed of repeating diorganopolysiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. Further, those having a slightly branched molecular structure may be included.

  The viscosity of component (A) at 25 ° C. is preferably 1,000 cP (centipoise) or more, and particularly preferably in the range of 1000 to 1,000,000 cP.

  Specific examples of this component include a trimethylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer at both ends, a dimethylvinylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer at both ends, and a trimethylsiloxy group-capped methylvinylsiloxane at both ends. -Diphenylsiloxane copolymer etc. are mentioned.

[(B) Organohydrogenpolysiloxane]
The (B) component organohydrogenpolysiloxane used in the present invention has at least 2, preferably 3 or more hydrogen atoms bonded to silicon atoms (ie, SiH groups) in one molecule. The alkenyl group in component (A) and the SiH group in component (B) undergo a hydrosilylation addition reaction, work as a crosslinking agent, cure the composition, and become a rubber-like elastic body with excellent high-temperature compression resistance. It is something to squeeze.
This organohydrogenpolysiloxane has the general formula (2):

(式中、R³はアルケニル基を含まない非置換又は置換の1価炭化水素基、Qは正の整数、Pは2以上の整数であり、但し、1＞P/(Q+P)＞0.2であり、Q＋Pは後述する粘度を満足する値となることが好ましい。)
で表される。

(Wherein R ³ is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, Q is a positive integer, P is an integer of 2 or more, provided that 1> P / (Q + P)> It is 0.2, and Q + P is preferably a value that satisfies the viscosity described later.)
It is represented by

In the general formula (2), R ³ may be the same as those exemplified for R ¹ above, and it is essential that 1> P / (Q + P)> 0.2, Is 0.9 ≧ P / (Q + P) ≧ 2.1, more preferably 0.8 ≧ P / (Q + P) ≧ 2.5. When P / (Q + P) ≦ 0.2, it is difficult to obtain high resistance to compression at high temperatures.

  The viscosity of component (B) at 25 ° C. is preferably 3 to 10,000 cP, more preferably 3 to 1,000 cP, and particularly preferably 3 to 300 cP.

  Specific examples of this component include, for example, a trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer with both molecular chain terminals, a trimethylsiloxy group-capped diphenylsiloxane / methylhydrogensiloxane copolymer with both molecular chain terminals, and both molecular chain terminals. Examples thereof include a trimethylsiloxy group-capped dimethylsiloxane / diphenylsiloxane / methylhydrogensiloxane copolymer, a trimethylsiloxy group-capped methylphenylsiloxane / methylhydrogensiloxane copolymer at both molecular chain terminals.

  The amount of component (B) added is such that the number of silicon atom-bonded hydrogen atoms (ie, SiH groups) contained in component (B) is 0.1 to 3.0 per one silicon-bonded alkenyl group contained in (A). It is the quantity which becomes a piece, Preferably, it shall be the range of 0.5-2.0. When the amount is less than 0.1, the composition is often insufficiently cured. When the amount is more than 3.0, the compression resistance at high temperature is deteriorated.

[(C) Platinum-based catalyst]
Examples of the platinum-based catalyst of the component (C) used in the present invention include platinum or a platinum group compound. The component (C) is used as a catalyst for promoting the addition reaction (hydrosilation) between the component (A) and the component (B), and is conventionally used for this type of purpose. Any of those known to those skilled in the art can be used. Specific examples include platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, complexes of chloroplatinic acid and olefins, aldehydes, vinyl siloxanes, acetylene alcohols, and the like.

  The amount of component (C) added may be an effective amount (so-called catalyst amount), and can be appropriately increased or decreased depending on the desired curing rate. Usually, the amount of platinum is 0.1 to 1000 ppm (weight), preferably 1 to 200 ppm relative to component (A).

[(D) Inorganic filler]
Component (D) is for imparting further physical strength to the cured product of the present composition. Examples of such inorganic fillers include reinforcing silica such as crystalline silica, fumed silica, and precipitated silica. Can be mentioned. Examples of crystalline silica (quartz powder) include crystallite, Minusil, and Imisil. Examples of reinforcing silica include hydrophilic silica whose surface is not treated and hydrophobic silica whose surface is treated with an organosilicon compound such as silane or silazane. Examples of hydrophilic silica include Aerosil 130,200,300 (Nippon Aerosil, Degussa), Cabosil MS-5, MS-7 (Cabot), Rheorosil QS-102,103 (Tokuyama Soda) NipsilLP (Nippon Silica), etc. Can be mentioned. Examples of hydrophobic silica include Aerosil R-812, R-812S, R-972, R-974 (manufactured by Degussa), Rheorosil MT-10 (manufactured by Tokuyama Soda), NipsilSS series (manufactured by Nippon Silica), and the like. .
Further, non-reinforcing fillers such as diatomaceous earth and calcium carbonate may be used.

[Other ingredients]
When it is necessary to adjust the curing time in order to put these materials into practical use, vinyl group-containing organopolysiloxanes such as vinylcyclotetrasiloxane, triallyl isocyanurate, alkyl maleates, acetylene alcohols as control agents And compounds selected from the group consisting of silanes, modified silanes, hydroperoxides, tetramethylethylenediamine, benzotriazole, and mixtures thereof may be used.

  Addition of inorganic pigments such as cobalt blue, colorants such as organic dyes, heat resistance and flame retardancy improvers such as cerium oxide, zinc carbonate, manganese carbonate, titanium oxide, carbon black, and iron oxide is also possible.

  Since the high temperature compression resistance silicone rubber composition of the present invention has high resistance to compression at high temperatures after curing, it is useful for applications such as a fixing roll, a fixing belt surface material, a paper feed roll, a cleaning roll, and a transfer roll. .

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
The compression set was measured according to JIS K 6249. The hot air temperature was 180 ° C. and 230 ° C., and the treatment time was 22 hours.
The hardness was measured according to JISK6249.
These test pieces for measuring physical properties were prepared by sandwiching a silicone rubber composition between molds at a temperature of 120 ° C., press-curing for 10 minutes, and post-curing in a dryer at 200 ° C. for 4 hours.

Example 1
Crystals with 100 parts by weight of linear dimethylpolysiloxane (degree of polymerization of about 700) and an average particle size of 5 μm containing both sides of the molecular chain blocked with trimethylsiloxy groups and an average of about 5 side chain vinyl groups as methylvinylsiloxane units. After uniformly mixing 25 parts by weight of functional silica and 2 parts by weight of iron oxide, the viscosity at 25 ° C. is 15 cP, and the trimethylsiloxy group-blocked dimethylsiloxane / methylhydrochloride represented by the following formula (I) Gensiloxane copolymer (corresponding to P / (P + Q) = 0.29 in general formula (2)) 3.0 parts by weight (of SiH groups in organohydrogenpolysiloxane relative to vinyl groups in vinyl group-containing organopolysiloxane) Molar ratio (hereinafter abbreviated as H / Vi: equivalent to 1.0 mol / mol), 5 mol of vinyl group [—Si (CH ₃ ) (CH═CH ₂ ) O—] directly bonded to a silicon atom as a siloxane unit % Vinyl with a viscosity of 1,000 cP at room temperature 4 parts by weight of chilled polysiloxane, 0.1 part by weight of 1-ethynyl-1-cyclohexanol as a reaction control agent, and 50 ppm of platinum vinylsiloxane complex as platinum atoms were mixed well to obtain a silicone rubber composition ( Sample 1).

  Using a test piece obtained by heat-curing the silicone rubber composition under the above conditions, compression set and hardness were measured. The results are shown in Table 1.

-Comparative Example 1-
Except that the amount of the dimethylsiloxane / methylhydrogensiloxane copolymer represented by the formula (I) was changed to 10.0 parts by weight (corresponding to H / Vi: 3.3 mol / mol), the same as in Example 1. A silicone composition (Sample 2) was prepared, and compression set and hardness were measured in the same manner as in Example 1. The results are shown in Table 1.

-Comparative Example 2-
A dimethylsiloxane / methylhydrogensiloxane copolymer represented by the above formula (I) has a viscosity at 25 ° C. of 16 cP and a dimethylhydrogensiloxy group-capped dimethylsiloxane having a molecular chain at both ends represented by the following formula (II): A silicone composition (sample 3) was prepared in the same manner as in Example 1 except that it was changed to 3.5 parts by weight of methyl hydrogen siloxane copolymer (corresponding to H / Vi: 1.5 mol / mol). The hardness was measured in the same manner as in Example 1. The results are shown in Table 1.

-Comparative Example 3-
The dimethylsiloxane / methylhydrogensiloxane copolymer represented by the formula (I) has a viscosity of 10 cP at 25 ° C. and has a trimethylsiloxy group-capped dimethylsiloxane / methyl group represented by the following formula (III): Except for changing to hydrogen siloxane copolymer (corresponding to P / (Q + P) = 0.2 in general formula (2)) to 4.0 parts by weight (H / Vi: equivalent to 1.0 mol / mol). In the same manner as in Example 1, a silicone composition (Sample 4) was prepared, and compression set and hardness were measured in the same manner as in Example 1. The results are shown in Table 1.

-Example 2-
Both ends of the molecular chain are blocked with trimethylsiloxy groups, and 100 parts by weight of a linear dimethylsiloxane polymer (polymerization degree: about 900) containing an average of about 3 side chain vinyl groups as methylvinylsiloxane units, with an average particle size of 1.5 μm After uniformly mixing 25 parts by weight of crystalline silica and 2 parts by weight of iron oxide, the viscosity at 25 ° C. is 15 cP, and the trimethylsiloxy group-capped dimethylsiloxane methyl group is represented by the following formula (IV) Hydrogen siloxane copolymer (corresponding to P / (Q + P) = 0.45 in general formula (2)) 3.0 parts by weight (H / Vi: equivalent to 2.5 mol / mol), vinyl group directly connected to silicon atom 4 parts by weight of vinylmethylpolysiloxane containing 5 mol% of [—Si (CH ₃ ) (CH═CH ₂ ) O—] as siloxane units and having a viscosity at room temperature of 1,000 cP, and 1-ethynyl as a reaction control agent -1-Cyclohexanol 0.1 parts by weight, platinum vinylsiloxane complex It was mixed well until 50ppm uniformly added platinum atom, yielding a silicone rubber composition (Sample 5). Using a test piece obtained by heat-curing the silicone rubber composition under the above conditions, compression set and hardness were measured. The results are shown in Table 2.

-Comparative Example 4-
The molecular chain both ends trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer represented by the formula (IV) is represented by the following formula (V), and both molecular chains having a viscosity at 25 ° C. of 17 cP: A silicone composition (sample 6) was prepared and compressed in the same manner as in Example 2 except that the terminal dimethylhydrogensiloxy group-blocked dimethylpolysiloxane was changed to 12 parts by weight (H / Vi: equivalent to 2.5 mol / mol). Permanent strain and hardness were measured. The results are shown in Table 2.

-Comparative Example 5-
The molecular chain both ends trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer represented by the formula (IV) is represented by the following formula (VI), and both molecular chains having a viscosity at 25 ° C. of 5 cP: A silicone composition (Sample 7) was blended in the same manner as in Example 2 except that 1.0 part by weight of methyl hydrogen polysiloxane with a terminal trimethylsiloxy group blocked (H / Vi: equivalent to 2.2 mol / mol) was used. Compression set and hardness were measured. The results are shown in Table 2.

Example 3
Primer No. 101A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) for addition reaction type liquid silicone rubber was applied to an aluminum shaft.
The aluminum shaft shape was placed inside a roll forming die. The silicone rubber composition obtained in Example 1 was filled in a roll molding die, heated and cured at 150 ° C. for 30 minutes, and further post-cured at 200 ° C. for 4 hours. A silicone rubber coated roll was prepared. Furthermore, when it was incorporated as a fixing roll of a PPC copying machine and 100,000 sheets were copied, no compression set was observed, and the copied image was clear.

Claims (6)

(A) partial child-terminated by at least two chromatic alkenyl groups bonded to triorganosiloxy sequestered along the molecular chain of silicon atoms in groups in a molecule, a viscosity at 25 ℃ 1,000~1,000, linear di organopolysiloxane emissions 100 parts by weight in the range of 000 cP,
(B) General formula (2):

(Wherein R ³ is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, Q is a positive integer, P is an integer of 2 or more, provided that 0.45 ≧ P / (Q + P)> 0.2.)
Organohydrogenpolysiloxane represented by
(A) An amount in which the number of hydrogen atoms bonded to silicon atoms is 0.1 to 3.0 per alkenyl group in component (A),
(C) platinum-based catalyst effective amount,
(D) Inorganic filler 5 to 500 parts by weight
And a high temperature compression resistant silicone rubber composition comprising one or more components selected from a control agent, a colorant, a heat resistance improver, and a flame retardant improver . The high-temperature compression-resistant silicone rubber composition according to claim 1, wherein the organopolysiloxane of component (A) is represented by the following general formula (1).

Wherein R is an unsubstituted or substituted monovalent hydrocarbon group, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, R ² is an alkenyl group, n is an integer of 2 or more, m Is 0 or an integer greater than or equal to 1)   The high-temperature compression-resistant silicone rubber composition according to claim 2, wherein in the general formula (1) representing the component (A), R is a methyl group or a phenyl group.   It is a silicone rubber composition for rolls, The high temperature compression-resistant silicone rubber composition of any one of Claims 1-3.   Hardened | cured material obtained by hardening | curing the composition of any one of Claims 1-4.   The fixing roll which has a silicone rubber coating layer formed by hardening | curing the composition of any one of Claims 1-4.