JPH10130503A - Flame retardant silicone rubber composition and silicon rubber glass using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the new subject composition capable of expressing excellent characteristics such as flame retardance, electrical arc resistance, electrical insulation properties after curing, etc., by blending a specific silicon-containing phosphorus compound, a platinum (compound) and aluminum oxide or hydroxide to a polyorganosiloxane. SOLUTION: This flame retardant silicon rubber composition is obtained by bringing 100 pts.wt. of (A) a polyorganosiloxane having 3,000-20,000 average degree of polymerization of an average unit formula expressed by formula I [R<1> is a monovalent (substituted) hydrocarbon group; (q) is 1.98-2.02] to be blended with 0.01-10 pts.wt. of (B) a compound expressed by formula II [R<2> and R<3> are each R<1> ; X is H, R<1> , a group of the formula: SiR<4> 3 (R<4> is R<1> ), a group of the formula: (R<2> O)b (POc ) (0<=b<3; 0<=c<=1); 0<=d<=100; b+e=3; when d=0, X is a group of the formula: SiR<4> 3 ], 1-3000ppm of (C) platinum based on the component A as a (platinum) compound, 1-300 pts.wt. of (D) aluminum oxide or hydroxide and 0.1-10 pts.wt. of (E) a curing agent agernt (e.g. an organic peroxide vulcanizer).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant silicone rubber composition and an insulator obtained by curing this composition. More specifically, the present invention relates to a flame-retardant silicone rubber composition which is colorable and has excellent arc resistance and tracking resistance. The present invention relates to a flame-retardant silicone rubber composition that is effective as a high-voltage insulator.

[0002]

Technical background of the invention and its problems Silicone rubber is
It has excellent electrical insulation, heat resistance, weather resistance, and flame retardancy, and has been used as a wire covering material and a material for electric parts. In particular, regarding the flame retardancy, even if it does not contain a halogen compound such as another organic rubber, it can be made flame retardant by the method of Japanese Patent Publication No. 44-2591, etc. Has been used for various purposes such as cathode ray tubes and anode caps. However, in order to satisfy the standard such as UL94V-0 is, JP-B 47-16546 and JP-like carbon black or Fe ₃ O ₄ of JP-B 47-21826 JP and Sho 51-35501 JP This is not achieved without the addition of a strong black additive or an additive having a strong hiding power such as TiO ₂ , so that there is a limit to flame retardancy in a transparent or vivid color. Also,
When a flame retardant filler conventionally used in other organic rubbers such as aluminum hydroxide or magnesium hydroxide is blended with silicone rubber, or when aluminum oxide is blended to improve thermal conductivity However, there has been a problem that not only sufficient flame retardancy is not necessarily obtained but also the heat resistance of the silicone rubber is greatly reduced. As described in JP-A-8-41348, JP-A-8-41347, JP-A-7-133431 and JP-A-7-57574, aluminum hydroxide is used as a silicone rubber composition for insulators. Although the composition to be contained has been studied, sufficient characteristics such as arc resistance cannot be obtained. In Japanese Patent Publication No. 54-38628, the use of an organic phosphite is exemplified.
The arc resistance was insufficient, and when used in combination with aluminum hydroxide or the like, no improvement in flame retardancy was observed, resulting in a significant decrease in heat resistance.

[0003]

SUMMARY OF THE INVENTION The present invention has been intensively studied to provide a flame-retardant silicone rubber composition and a silicone rubber insulator using the same, and as a result, phosphoric acid or phosphorous acid having a specific silicon atom has been obtained. By blending the compound with polyorganosiloxane in combination with platinum or a platinum compound, aluminum oxide and / or aluminum hydroxide, a flame-retardant silicone rubber composition having excellent flame retardancy and arc resistance can be obtained. Further, the silicone rubber insulator obtained by curing the silicone rubber insulator has been found to be an insulator having a long-term stable insulation as an insulator for electric insulation due to its excellent electric insulation and arc resistance. Was completed. That is, the present invention provides: (A) an average unit formula: R ¹ _a SiO _{(4-a) / 2} (wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group,
a represents a number in the range of 1.98 to 2.02) 100 parts by weight of a polyorganosiloxane having an average degree of polymerization of 3000 to 20000 (B) Average unit formula: (R ² O) _b (PO _c ) (O (SiR ³ ₂ O) _d X) _e (wherein, R ² represents a substituted or unsubstituted monovalent hydrocarbon group or a hydrogen atom, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group, and X represents a substituted or unsubstituted monovalent hydrocarbon group. ⁽⁴ ₃ SiR) (wherein, R ⁴ is. a substituted or unsubstituted monovalent hydrocarbon group) hydrocarbon group or a hydrogen atom or a formula of unsubstituted mono- or (R ² O) _b ( A group represented by PO _c ), b, c, d and e are b + e = 3, 0 ≦ b
<3,0 <e ≦ 3,0 ≦ c ≦ 1,0 ≦ d ≦ 100. However, when the d = 0, X is a group represented by the formula (SiR ⁴ _3). (C) a platinum or platinum compound in an amount of 1 to 3000 ppm as a platinum atom with respect to the component (A) (D) 1 to 300 parts by weight of aluminum oxide and / or aluminum hydroxide (E) A flame-retardant silicone rubber composition comprising 0.1 to 10 parts by weight of a curing agent, and an insulator obtained by curing the flame-retardant silicone rubber composition. .

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Average unit formula of component (A) used in the present invention: R ¹ _a S
The polyorganosiloxane represented by iO _{(4-a) / 2} (wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group and a represents a number in the range of 1.98 to 2.02) It is used as a base polymer of a product, and a linear polymer is mainly used, but a part of the polymer may be a branched or three-dimensional structure, or a homopolymer or a copolymer may be used. Or a mixture thereof may be used. The substituted or unsubstituted monovalent hydrocarbon group bonded to the silicon atom of the polyorganosiloxane includes, for example, an alkyl group such as a methyl group, an ethyl group and a propyl group; a vinyl group, an allyl group and a butadienyl group. Alkenyl group; phenyl group, xenyl group,
Cycloalkenyl groups such as naphthyl groups; arylaryl groups such as benzyl groups; unsubstituted hydrocarbon groups such as alkylaryl groups such as tolyl and xylyl groups, chloromethyl groups, and 3,3,3-trialkyl groups. A substituted hydrocarbon group such as a fluoropropyl group is exemplified. As the monovalent hydrocarbon group bonded to these silicon atoms, a methyl group is mainly used.For example, in the case of a vinyl group, from the viewpoint of mechanical strength and crosslinkability, 0.001 to 5% may be contained, and a range of 0.05 to 3% is particularly preferable. In addition, as a molecular chain terminal of the polyorganosiloxane, a hydroxyl group, an alkoxy group, or a triorganosilyl group is exemplified, and a triorganosilyl group is more preferable. Examples of the triorganosilyl group include a trimethylsilyl group, a dimethylvinylsilyl group, a methylphenylvinylsilyl group, and a methyldiphenylsilyl group. The average polymerization degree of the component (A) is in the range of 3,000 to 20,000, preferably 5,000 to 10,000, particularly preferably 6,000 to 7,000. If the degree of polymerization is too small, it is difficult to obtain a sufficient mechanical strength, while if it is too large, it is difficult to mix the compound into the system.

The average unit formula of the component (B) is: (R ² O) _b (PO _c ) (O (SiR ³ ₂ O) _d X) _e [wherein R ² is a substituted or unsubstituted monovalent carbonized hydrogen group or a hydrogen atom, R ³ is a substituted or unsubstituted monovalent hydrocarbon group, X is a hydrocarbon radical or a hydrogen atom or formula for a substituted or unsubstituted monovalent (SiR ⁴ ₃₎ (in the formula, R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group.) Or a group represented by (R ² O) _b (PO _c ), and b, c, d, and e each represent b + e = 3. 0 ≦
b <3, 0 <e ≦ 3, 0 ≦ c ≦ 1, 0 ≦ d ≦ 100. However, when the d = 0, X is a group represented by the formula (SiR ⁴ _3). Is a phosphoric acid or phosphorous acid compound having a silicon atom, the component (C) or (D)
Interaction with components improves flame retardancy and arc resistance. The phosphoric acid compound having a silicon atom as the component (B) can be obtained, for example, by mixing a cyclic or linear alkylpolysiloxane with phosphoric acid and then reacting the mixture at a temperature of 100 to 200 ° C. Further, a phosphorous acid compound having a silicon atom can also be obtained by directly reacting phosphorus trichloride with a siloxane or silane having a silanol group at a terminal. The amount of the component (B) is
0.01 to 10 parts by weight per 100 parts by weight is effective. If the amount is less than 0.01 part by weight, the effect cannot be obtained.

The platinum compound as the component (C) may be the same as a platinum compound which is generally used as a curing catalyst in an addition reaction of an organopolysiloxane. For example, chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum and Olefin complex, platinum and vinyl siloxane complex, platinum carbon,
Platinum-based compounds such as platinum-triphenylphosphine complex, those in which platinum is supported on a carrier such as alumina or silica; examples thereof include tetrakis (triphenylphosphine) palladium, and a mixture of palladium black and triphenylphosphine. Palladium compounds and the like are exemplified. The amount of component (C) is in the range of 1 to 3000 ppm, preferably 5 to 200 ppm, in terms of platinum atomic weight, based on the organopolysiloxane base polymer (silicone base polymer) of component (A). If the amount of the curing catalyst is less than 1 ppm in terms of platinum atoms, the effect of imparting flame retardancy is not remarkable, and if it exceeds 3000 ppm, the properties of the silicone rubber, such as heat resistance, are significantly reduced.

The component (D), aluminum oxide and / or aluminum hydroxide, is an essential component for enhancing the flame retardancy by acting synergistically with the components (B) and (C). This aluminum oxide is Al ₂ O ₃ , and aluminum hydroxide is A
It is represented by l ₂ O ₃ .3H ₂ O and has an average particle size of 30 μm or less, preferably 0.5 to 20 μm. The aluminum oxide and / or aluminum hydroxide may be used as it is, but may be used after surface treatment with a silane-based or titanate-based coupling agent, dimethylpolysiloxane oil, stearic acid, or the like. Either aluminum oxide or aluminum hydroxide as the component (D) may be used alone, or may be used as a mixture. The amount of the component (D) is preferably 1 to 300 parts by weight, more preferably 50 to 250 parts by weight, per 100 parts by weight of the polyorganosiloxane of the component (A). If the compounding amount of the component (D) is less than 1 part, sufficient flame retardancy cannot be obtained, and if it exceeds 300 parts by weight, the processability of the obtained silicone rubber is remarkably reduced, and a good molded product is obtained. It is difficult to obtain.

[0008] The organic peroxide which is a curing agent of the component (E) is
The silicone rubber composition of the present invention is cured to form a rubber elastic body. As the curing agent of the component (E), conventionally known dicumyl peroxide, cumyl-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, benzoyl peroxide, 2 Organic peroxide vulcanizing agents such as 1,4-dichlorobenzoyl peroxide, monochlorobenzoyl peroxide and t-butylperoxybenzoate are used. The amount of the organic peroxide is 0.1 to 100 parts by weight of the polyorganosiloxane.
A range of 10 parts by weight is preferred. The amount of organic peroxide
If it is less than 0.1, it will not cure sufficiently, and if it exceeds 10 parts by weight, not only will there be no special effect, but it may also adversely affect the properties of the obtained silicone rubber. These organic peroxides may be used alone or in combination of two or more.

The composition of the present invention contains, in addition to the above components, conventionally used fumed silica depending on the purpose.
Wet silica, crushed quartz, silica-based fillers such as diatomaceous earth and various additives, for example, titanium oxide, iron oxide, cerium oxide, vanadium oxide, metal oxides such as chromium oxide,
Pigments, heat-resistant agents, flame-retardant-imparting agents and the like can be added as long as the properties of the composition of the present invention are not impaired.

The silicone rubber composition of the present invention can be obtained by uniformly mixing the above-mentioned components at room temperature. If necessary, components other than the organic peroxide are first mixed with a planetary mixer or kneader. After a heat treatment at a temperature in the range of -200 ° C for 1-4 hours, an organic peroxide may be added and mixed.

[0011]

Since the silicone rubber composition of the present invention has excellent flame retardancy, arc resistance and heat resistance, it can be effectively used as a heat dissipation sheet provided with thermal conductivity or a silicone rubber insulator as a high-voltage electrical insulator. Can be used.

[0012]

EXAMPLES Hereinafter, the present invention will be described more specifically by way of Examples.
Although described, the present invention is not limited to these. In the following examples, parts are parts by weight. Example 1 (CH ₃ ) ₂ SiO unit 99.9 mol%, (CH ₃ ) (CH ₂ = CH) SiO unit 0.12
100 parts by weight of a polyorganosiloxane having a degree of polymerization of 6000 and containing 5 parts of a polydiorganosiloxane having a capped end with a silanol group and having a viscosity of 90 cSt at 25 ° C. Dosilica (AEROSIL 130) 45 parts, aluminum hydroxide 1
50 parts were kneaded with a kneader mixer until uniform. Then, after heating at 150 ° C. for 2 hours, 0.1 part of chloroplatinic acid (5% as platinum element amount) as a platinum compound and 3 parts of a phosphoric acid compound having a silicon atom represented by the following formula are blended. A silicone rubber composition was obtained.

[0013]

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The silicone rubber composition was mixed with 0.8 parts of dicumyl peroxide as a curing agent with a two-roll mill until uniform, to obtain a silicone rubber base polymer.
This silicone rubber base polymer was press-vulcanized at 170 ° C. for 10 minutes to obtain a cured silicone rubber sheet. This silicone rubber sheet was evaluated for physical properties and heat resistance according to JIS K6301. Furthermore, in accordance with the standard of ASTM D-2303-64T, when the contaminated liquid (0.
Aqueous solution of 1% NH ₄ Cl and 0.02% nonionic surfactant)
Was dropped from the upper electrode at a rate of 0.6 ml / min, and the time until the track was generated and turned on and the erosion weight loss caused thereby were measured. The results are shown in Table 1.

Example 2 A sample was prepared and evaluated in the same manner as in Example 1 except that the aluminum hydroxide in the silicone rubber compound was changed to aluminum oxide.

Example 3 A sample was prepared and evaluated in the same manner as in Example 1 except that the silicone rubber compound was changed to a mixture of 150 parts of aluminum hydroxide and 50 parts of aluminum hydroxide and 100 parts of aluminum oxide. Was.

Example 4 Instead of the phosphoric acid compound having a silicon atom of the silicone rubber compound of Example 1, one part of a phosphorous compound having a silicon atom represented by the following formula is blended to prepare a silicone rubber composition. Obtained and evaluated.

[0018]

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Comparative Example 1 A sample was prepared and evaluated in the same manner as in Example 1 except that no phosphoric acid compound was added.

Comparative Example 2 In place of the phosphoric acid compound of Example 1, 0.5 part of triphenyl phosphite was added, and a sample was prepared and evaluated in the same manner.

Comparative Example 3 A sample was prepared and evaluated in the same manner as in Example 1 except that aluminum hydroxide was not blended. These results are summarized in Table 1.

[0022]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01B 3/46 H01B 3/46 Z 17/00 17/00 B

Claims (2)

[Claims] (A) Average unit formula: R ¹ _a SiO _{(4-a) / 2} (where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group,
a represents a number in the range of 1.98 to 2.02) 100 parts by weight of a polyorganosiloxane having an average degree of polymerization of 3000 to 20000 (B) Average unit formula: (R ² O) _b (PO _c ) (O (SiR ³ ₂ O) _d X) _e (wherein, R ² represents a substituted or unsubstituted monovalent hydrocarbon group or a hydrogen atom, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group, and X represents a substituted or unsubstituted monovalent hydrocarbon group. ⁽⁴ ₃ SiR) (wherein, R ⁴ is. a substituted or unsubstituted monovalent hydrocarbon group) hydrocarbon group or a hydrogen atom or a formula of unsubstituted mono- or (R ² O) _b ( A group represented by PO _c ), b, c, d and e are b + e = 3, 0 ≦ b
<3,0 <e ≦ 3,0 ≦ c ≦ 1,0 ≦ d ≦ 100. However, when the d = 0, X is a group represented by the formula (SiR ⁴ _3). (C) a platinum or platinum compound in an amount of 1 to 3000 ppm as a platinum atom with respect to the component (A) (D) 1 to 300 parts by weight of aluminum oxide and / or aluminum hydroxide (E) A flame-retardant silicone rubber composition comprising 0.1 to 10 parts by weight of a curing agent. 2. An insulator obtained by curing the flame-retardant silicone rubber composition according to claim 1.