JP2001176330A - Silicone rubber composition for electric wire and silicone rubber-coated electric wire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone rubber composition for an electric wire with a good safety, that can be continuously vulcanized at atmospheric pressure with no voids or surface tacks at the time of extrusion vulcanization. SOLUTION: The silicone rubber composition for an electric wire consisting of (A) Organopolysiloxane containing 0.02 to 2.0 mol% of alkenyl group in a molecule, represented by an average composition formula (I) Formula 1 where, R1 represents a same or different type of unsubstituted or substituted monovalent hydrocarbon group and a represents a positive number ranging from 1.95 to 2.05. (B) Finely powdered silica with a specific surface area of not less than 50 m2/g: 20 to 100 weight part by BET method. (C) Diatomaceous earth and/or quartz powder: 5 to 200 weight part. (D) Fatty acid or aliphatic series derivatives and/or their metallic salt: 0.01 to 5 weight part. (E) Mixture of particular bis-methylbenzoylperoxide (E-1) and peroxydicarbonates that are solids at room temperature (E-2): 0.1 to 10 weight part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a silicone rubber composition for electric wires, and in particular, has excellent safety and hygiene properties, and can be converted into a silicone rubber by continuous normal-pressure hot air vulcanization without generation of voids or surface tack during vulcanization of electric wires. A silicone rubber composition for an electric wire which can be suitably used for the production of a silicone-coated electric wire, and a silicone obtained by vulcanizing and molding the silicone rubber composition for an electric wire around a core wire made of a copper wire or a tin-plated copper wire. The present invention relates to a rubber-coated electric wire.

[0002]

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION Silicone rubber is widely used in various fields such as wire coating, tubes, anode caps, rolls and sponges because of its excellent heat resistance, cold resistance and electrical properties. Various methods have been implemented for the processing process according to the application.

Various methods of vulcanizing the silicone rubber composition for electric wires are carried out in accordance with the type of silicone rubber and the physical properties required for a cured product thereof. In general, vulcanization is carried out in the presence of an organic peroxide. Heat treatment is widely used, and benzoyl peroxide, p-
Chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-
Examples include t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butyl-perbenzoate, t-butylcumyl peroxide, and the like. Accordingly, 2,4-dichlorobenzoyl peroxide was the only vulcanizing agent for obtaining a silicone rubber wire molded article having good characteristics and an economically advantageous product.

However, recently, since 2,4-dichlorobenzoyl peroxide contains a chlorine atom, it has been pointed out that polychloride which is a by-product of decomposition during vulcanization has safety and health. In addition, the silicone rubber-coated electric wire obtained by the normal pressure hot air vulcanization (hereinafter referred to as HAV) is obtained by putting the silicone rubber composition discharged from the extruder into a high-temperature vulcanizing furnace at 300 to 500 ° C. Since siloxane and other volatile substances are gasified and expanded, microvoids which are not observed with the naked eye are generated in the vulcanized silicone rubber-coated electric wire. This phenomenon is conspicuous in the currently used 4-methylbenzoyl peroxides, and one of the causes is that the vulcanization rate is lower than that of 2,4-dichlorobenzoyl peroxide.

In order to improve the vulcanization characteristics, Japanese Patent Application Laid-Open
In Japanese Patent No. 228650, the vulcanization rate is improved by using 4-methylbenzoyl peroxide as a vulcanizing agent and making the base siloxane a trivinylsiloxy terminal. However, its vulcanization properties are inferior to those of 2,4-dichlorobenzoyl peroxide. Japanese Patent Application Laid-Open No. Sho 62-36462 discloses a vulcanization rate which is higher than that of benzoyl peroxide alone by using two types of peroxides. However, when used for silicone rubber-coated electric wires, their core wire adhesion (separable properties with time of the rubber part of the molded electric wire) and cut-strip property (stripping of the rubber part of the electric wire end after silicone rubber coating) Sex) is not enough.
Improvements in core wire adhesion are disclosed in JP-A-11-140321, JP-A-64-43563, JP-A-57-159850, and JP-A-57-59851. In these, stearic acid esters, N, N'-alkylenebisimide compounds, stearic acid amides, and the like are used to improve core wire adhesion resistance. However, vulcanization of only 4-methylbenzoyl peroxides is required. This has a great effect on the vulcanization speed, and the vulcanization speed is reduced. Further, Japanese Patent Application Laid-Open No. H11-246763 discloses an improvement in the breakdown voltage (hereinafter, referred to as BDV) of a coated electric wire by controlling the average primary particle size and the maximum particle size of 4-methylbenzoyl peroxides. This improved the incidence of microvoids, but was still inadequate, and the level of 2,4-dichlorobenzoyl peroxide needed to be improved. Further, there is no disclosure of a silicone rubber composition for electric wires which can be continuously vulcanized under normal pressure and hot air in combination with two kinds of organic peroxides. There is no disclosure of solid peroxydicarbonate which is one component of two kinds of organic peroxides. BDV of coated electric wire by particle size control
No improvement was disclosed.

[0006] As described above, the vulcanization characteristics, core wire adhesion resistance, and cut-stripability are important characteristics in terms of productivity, use environment, and work, and are characteristics that greatly affect maintenance of quality, work efficiency, and the like.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems, and is excellent in safety and capable of continuous normal-pressure hot air vulcanization without causing voids or surface tack during extrusion vulcanization. It is an object of the present invention to provide a composition and a molded article using the same, particularly a molded article of a silicone rubber electric wire having no microvoids, and a silicone rubber-coated electric wire which is extremely excellent in core wire adhesion resistance and cut stripping property.

[0008]

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, added the inorganic fillers (B), (C) and (D) to the organopolysiloxane (A). A silicone rubber composition which is used in combination with two types of organic peroxides as component (E) is excellent in safety, has no voids or surface tack during extrusion vulcanization, and therefore has excellent voltage resistance and continuous normal operation. Silicone rubber-coated electric wires coated with a cured product of this composition have no tack even without secondary vulcanization, so there is no need for powdering, and they have excellent core wire adhesion and cut stripping properties. And completed the present invention.

That is, the present invention provides: (A) an average composition formula (I) R ¹ _a SiO _{(4-a) / 2} ... (I) (wherein R ¹ is the same or different unsubstituted or substituted (A) is a positive number of 1.95 to 2.05), and 100 parts by weight of an organopolysiloxane containing 0.02 to 2.0 mol% of alkenyl groups in one molecule. (B) Specific surface area by BET method is 50 m. ² / g or more finely divided silica
20 to 100 parts by weight (C) Diatomaceous earth and / or quartz powder 5 to 200 parts by weight (D) Fatty acid or aliphatic derivative and / or metal salt thereof 0.01 to 5 parts by weight (E) Formula (II) below

[0010]

Embedded image

Wherein X is an alkyl group having 1 to 4 carbon atoms;
C1-C4 alkoxy group, formula -SiR^Two _Three, -CH_TwoSiR^Two _Three(R
^TwoIs a hydrogen atom, a methyl group or an alkoxy group).
Wherein n is 1 or 2), an organic peroxide (E-
1) and peroxydicarbonates (E
-2) a mixture comprising 0.1 to 10 parts by weight
Silicone rubber composition for electric wires,
A core made of a silicone rubber composition or a copper wire or a tin-plated copper wire
Providing silicone rubber-coated wires vulcanized around wires
Is what you do.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The organopolysiloxane of the component (A) is represented by the above average composition formula (I) and contains 0.02 to 2.0 mol% of an alkenyl group in one molecule including a terminal vinyl group.

In the average composition formula (I), R ¹ is
Methyl group, ethyl group, propyl group, butyl group, hexyl group, alkyl group such as dodecyl group, cycloalkyl group such as cyclohexyl group, alkenyl group such as vinyl group, allyl group, butenyl group, hexenyl group, phenyl group, tolyl An aryl group such as a group, an aralkyl group such as a β-phenylpropyl group, or a chloromethyl group in which part or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with a halogen atom, a cyano group, or the like, trifluoropropyl Group, a cyanoethyl group, or the like, the same or different, preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably a methyl group , A vinyl group, a phenyl group, and a trifluoropropyl group. Among these it is preferable more than 80 mol% of R ¹ is a methyl group. A is a positive number from 1.95 to 2.05, and is basically a linear diorganopolysiloxane, but may be partially branched. Further, a mixture of two or more kinds having different molecular structures may be used.

The degree of polymerization of this component may be in the range referred to in the art as an organosiloxane raw rubber, and usually has a viscosity at 25 ° C. of at least 10 ⁶ centistokes and an average molecular weight of 25. More than ten thousand are used.

The organopolysiloxane contains 0.02 to 2.0 mol% in one molecule, including a vinyl group at a molecular end.
It is necessary to contain preferably 0.05 to 0.5 mol% of alkenyl groups, preferably vinyl groups. If the amount is less than 0.02 mol%, the vulcanization properties deteriorate, and if it exceeds 2.0 mol%, the elasticity of the cured silicone rubber is impaired.

The finely divided silica (B) is a component that imparts mechanical strength to silicone rubber and excellent extrusion characteristics to the silicone rubber composition, and has a BET specific surface area of 50%.
m ² / g or more, preferably 100 to 400 m ² / g. Further, the average particle diameter is preferably 1 to 20 μm. Representative examples of the finely divided silica include fumed silica, precipitated silica, and silica obtained by hydrophobizing the surface thereof with organopolysiloxane, organopolysilazane, chlorosilane, alkoxysilane, or the like. These silicas may be used alone or in combination of two or more. The amount of the finely divided silica (B) is 20 to 100 parts by weight, preferably 30 to 80 parts by weight, per 100 parts by weight of the organopolysiloxane (A).

The diatomaceous earth and / or quartz powder of the component (C)
It is an important component that improves the core wire adhesion resistance and the cut stripping property of the silicone-coated electric wire by a synergistic effect with the effect of improving the vulcanization rate of the organic peroxide (E). Commercially available diatomaceous earth and quartz powder can also be used. Component (C) is added in an amount of 5 to 200 parts by weight, preferably 100 parts by weight of organopolysiloxane (A).
10 to 100 parts by weight. If the amount is less than 5 parts by weight, the cut stripping property is insufficiently improved, and if it exceeds 200 parts by weight, the physical properties of the obtained silicone rubber deteriorate.

The fatty acid or aliphatic derivative of the component (D) and / or the metal salt thereof is used in combination with the effect of improving the vulcanization rate of the organic peroxide of the component (E) to improve the core adhesion of the silicone-coated electric wire. It is an important component for improving cut strip properties. This can also use a commercial thing.
Component (D) is added in an amount of 0.01 to 5 parts by weight, and preferably 0.0 to 5 parts by weight, per 100 parts by weight of the organopolysiloxane of component (A).
It is 5 to 1 part by weight. If the amount is less than 0.05 parts by weight, the improvement in core wire adhesion is insufficient, and if it exceeds 2 parts by weight, the physical properties of the obtained silicone rubber deteriorate. The fatty acid or the aliphatic derivative and / or the metal salt thereof preferably have 8 or more carbon atoms, and the hydrocarbon may be composed of a normal moiety as well as an isomer, an unsaturated group and a substituent having a substituent. The melting point is 40-150 ° C at normal pressure, especially 40
~ 100 ° C is preferred. If it exceeds 150 ° C., the dispersibility in the silicone compound will be reduced.

Specific examples of fatty acids include caprylic acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, araginic acid,
Examples include lignoceric acid, serotin, melisic acid, myristolic acid, oleic acid, linoleic acid, linolenic acid, and the like.

Examples of the aliphatic derivatives include fatty acid esters, fatty alcohol esters, fatty acid amides, and alkylene fatty acid amides. Examples of the fatty acid ester include the above fatty acids and polyhydric alcohol esters such as C _{1 to} C ₅ lower alcohol esters, sorbitan esters and glycerin esters. The esters of aliphatic alcohols, caprylyl alcohol, capryl alcohol, lauryl alcohol, isomyristyl alcohol, stearyl alcohol, saturated alcohols of C ₈ -C ₂₀ etc., oleyl alcohol, linoleyl alcohol, and unsaturated alcohols such as linolenic alcohol And dibasic acid esters such as glutaric acid esters and suberic acid esters of aliphatic alcohols, and tribasic acid esters such as citric acid esters. Of these, esters of aliphatic alcohols are preferred, and citrate esters are most preferred. The aliphatic amides, lauric acid amides of C ₁₀ -C _20, palmitic acid amide, stearic acid amide, such as oleic acid amide and the like. Among them, stearic acid amide is preferable. Examples of the alkylene fatty acid amide include methylene fatty acid amides such as methylene bisstearic acid amide, methylene bisbehenic acid amide, methylene bismyristinic acid amide, methylene biscaproic acid amide, and methylene bisbehenic acid amide; , Ethylene bisbehenic acid amide, ethylene bis myristic acid amide, ethylene bis caproic acid amide,
Examples include ethylene fatty acid amides such as ethylene bisbehenic acid amide.

The organic peroxide benzoyl peroxide (E-1), which is one component of the component (E), is usually solid at room temperature and has the following formula (II):

[0022]

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## EQU2 ## Wherein, X is a methyl group, an ethyl group, an alkyl group having 1 to 4 carbon atoms such as a propyl group, a methoxy group, an ethoxy group, an alkoxy group having 1 to 4 carbon atoms such as a propoxy group, the formula -SiR ² _3, - CH ₂ SiR ² ₃ (R ² is a hydrogen atom, a methyl group or an alkoxy group such as a methoxy group or an ethoxy group), and n is 1 or 2.

Specifically, bis (o-methylbenzoyl) peroxide, bis (p-methylbenzoyl) peroxide, bis (2,4-dimethylbenzoyl) peroxide, bis (orthoethylbenzoyl) peroxide, (Orthomethoxybenzoyl) peroxide, bis (orthoethoxybenzoyl) peroxide and the like are exemplified. Among them, bis (p-methylbenzoyl) peroxide is preferred.

On the other hand, peroxydicarbonates (E-2) which are solid at room temperature include, for example, bis (4-t-butylcyclohexyl) peroxydicarbonate, di (2-phenoxyethyl) -Oxydicarbonate, dicetyl peroxydicarbonate, dimilstilperoxydicarbonate, dibenzylperoxydicarbonate and the like. Among them, screw (4-
(t-Butylcyclohexyl) peroxydicarbonate is preferred.

The component (E) is used in an amount of 0.1 to 10 parts by weight, preferably 100 parts by weight, based on 100 parts by weight of the organopolysiloxane of the component (A).
0.6 to 4.0 parts by weight are blended. If the amount is less than 0.1 part by weight, the composition may not be sufficiently vulcanized, and if it exceeds 10 parts by weight, the physical properties of the obtained silicone rubber may be adversely affected. When the component (E) is used in combination with the components (C) and (D), the microvoids generated during the molding of the electric wire are reduced. The above may adversely affect the physical properties of the obtained silicone rubber. Also, the addition amount of the benzoyl peroxide (E-1) component and peroxydicarbonate solid at room temperature is an important factor for having both fast vulcanization characteristics and HAV properties, and considering the balance, benzoyl peroxide ( E-1) is preferably 0.5 to 2.0 parts by weight based on 100 parts by weight of the mixture of the components (A) to (D). Similarly, the amount of peroxydicarbonate (E-2) which is solid at room temperature is preferably 0.1 to 2.0 parts by weight is preferred. The blending amount of (E-1) and (E-2) can be changed according to vulcanization conditions and the like. For example, when HAV is more important than vulcanization, benzoyl peroxide is used. It is improved by adding a large amount of class (E-1), and when vulcanization is important, it can be improved by increasing the amount of solid peroxydicarbonate (E-2) added. . The mixing ratio (E-1) / (E-2) is 0.5
It is preferably in the range of 20 to 20.

Further, in order to reduce the generated microvoids, two organic peroxides (E-1) as the component (E),
It is preferable that both (E-2) have an average primary particle diameter of 5 to 20 microns and a maximum particle diameter of 50 microns or less. When the average primary particle size is less than 5 microns, secondary aggregation is likely. When the average primary particle size exceeds 20 microns, and when the maximum primary particle size exceeds 50 microns, honeycomb-like or There is a possibility that a large-diameter void may be generated, which may lead to spark-out and a decrease in insulation voltage breakdown. In addition, voids are generated even when the dispersion state of the component (E) in the composition is poor. Therefore, when the component (E) is blended, the component (E) is mixed with the organopolysiloxane in advance and dispersed well. Then, for example, the component (E) is 50%
It is preferable to prepare a paste-like material and mix it.

The silicone rubber composition for electric wires of the present invention can be obtained by uniformly mixing predetermined amounts of the above-mentioned components (A) to (E). In addition, finely divided silica, diatomaceous earth and / or quartz powder, and fatty acids as components (B), (C) and (D) are mixed, and if necessary, heated to form a silicone rubber compound. ) An organic peroxide as a component may be added and kneaded with a two-roll, kneader, Banbury mixer or the like.

At this time, it is preferable to add a silane containing a hydroxyl group or an alkoxy group or an organopolysiloxane having a polymerization degree of 100 or less as a processing aid. The amount of this addition
The organopolysiloxane of component (A) is selected depending on the amount of component (B), component (C), and component (D).
0.1 to 20 parts by weight, preferably 0.5 to 8 parts by weight per 100 parts by weight
Parts by weight. In addition, known additives usually added to the silicone rubber composition, such as an organohydrogenpolysiloxane and a colorant, a heat resistance improver, a flame retardant,
A release agent or the like may be added.

The silicone rubber composition for an electric wire of the present invention comprises:
Silicone rubber can be obtained by heat vulcanization, and in particular, this composition can be continuously vulcanized by hot air vulcanization under normal pressure. In order to obtain a silicone rubber-coated electric wire, the above composition may be continuously supplied onto a copper wire or a tin-plated copper wire serving as a core wire using an extruder, and vulcanized at normal pressure in a hot air vulcanizing furnace. If the vulcanization temperature is below 200 ° C, vulcanization may be delayed and microvoids may be generated.If the vulcanization temperature is above 550 ° C, overvulcanization may occur and surface cracks may occur. C., and the residence time in the furnace is preferably in the range of 1 to 300 seconds, particularly 5 to 50 seconds. According to this, a molded product which does not contain microvoids and thus has excellent withstand voltage properties, and further has no surface tack and thus does not require dusting can be easily obtained. The silicone rubber-coated electric wire molded in this way has excellent core wire adhesion resistance and cut-strip property required at the time of electric wire terminal treatment. Further, a radiation vulcanizing furnace such as a high frequency (UHF) vulcanizing furnace or an electron beam vulcanizing furnace may be used in combination with the hot air vulcanizing furnace.

[0031]

〔Measuring method〕

(Vulcanization characteristics) The measured values of torque at 110 ° C. and a deflection angle of ± 3 ° using a curast meter are shown. (Presence / absence of microvoids) The silicone rubber composition as a sample was molded into a rod having a diameter of 6 mm using an extruder having a diameter of 40 mm, and passed through a vulcanizing furnace at 300 ° C for a residence time of 13 seconds to perform normal pressure hot air heating. After vulcanization, the cross section of the obtained cured product was magnified 100 times with an optical microscope to check for the presence of microvoids. (Dielectric breakdown strength) A silicone rubber composition as a sample was coated on a tin-plated annealed copper wire having a diameter of 0.6 mm using an extruder having a diameter of 40 mm to form an electric wire having an outer diameter of 1.2 mm. Under normal pressure and hot air vulcanization under the conditions, ten samples were prepared from these and subjected to a withstand voltage test in water according to the method of JIS C-3004. (Core wire adhesion) The presence or absence of rubber residue after a 4 hour test of the molded electric wires in ovens at 200 ° C and 250 ° C was confirmed.
No residual rubber: O, trace of residual rubber: Δ, residual rubber: X (Cut stripping property) A silicone rubber composition as a sample was coated on a tin-plated annealed copper wire having a diameter of 0.6 mm using an extruder having a diameter of 40 mm to form an electric wire having an outer diameter of 1.2 mm.
Samples were prepared from this under normal pressure hot air vulcanization under the conditions of 30 seconds, and the stripping properties (cut strip properties) of the rubber covering the ends of the electric wires were examined for these samples. The cut strip jig is a dedicated jig with a blade for cutting the covering rubber into a pliers-like clipping tool.A round hole with the same diameter as the core wire is opened at the portion where the wire is sandwiched so that the core wire is not cut. Was used. Using this jig, a cut rubber strip test was conducted manually. The observation was made by visually observing the state of the rubber remaining on the surface of the stripped core wire. Good: O, small amount of rubber remaining: Δ, rubber remaining: X Examples 1 to 3 100 parts of an organopolysiloxane having a degree of polymerization of 8,000 and containing 99.85% of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units and having a molecular chain terminal blocked by a dimethylvinyl group has a BET specific surface area of 200 m ² / g. Fumed silica Aerosil 200 (Nippon Aerosil Co., Ltd.) 40 parts, diatomaceous earth 3
0 parts, 0.1 part of zinc stearate, 3 parts of diphenylsilanediol, and 6 parts of α, ω-dimethylpolysiloxanediol having a viscosity of 20 centistokes are added, and the mixture is uniformly kneaded with a kneader and then heat-treated at 160 ° C. for 3 hours. To make a silicone rubber compound, then compound 10
50 parts of bis (p-methylbenzoyl) peroxide (average primary particle diameter 10 microns, maximum particle diameter 20 microns)
% Silicone oil paste (hereinafter referred to as organic peroxide) 1.5 parts and bis (4-t-butylcyclohexyl)
Peroxydicarbonate (average primary particle size 15 microns,
50% silicone paste (maximum particle size 30 microns)
0.5 part of organic peroxide) was added and kneaded with two rolls to prepare a silicone rubber composition 1.

A silicone rubber composition 2 was prepared by treating the diatomaceous earth in the same manner as above except that quartz powder (crystallite VXS, manufactured by Tatsumori Co., Ltd.) was used. Similarly, a silicone rubber composition 3 was prepared by treating the same composition except that zinc stearate in the composition 1 was changed to distearate citrate. Comparative Examples 1 to 4 Silicone rubber composition 4 was prepared by treating silicone composition 1 of Example 1 with the same composition except that no organic peroxide was added, and treating the same as described above. Similarly, a silicone rubber composition 5 was prepared by treating the same composition as described above except that diatomaceous earth was not added to the silicone composition 1. Similarly, a silicone rubber composition 6 was prepared by treating the same composition as above except that zinc stearate was not blended in the silicone composition 1. Similarly, a silicone rubber composition 7 was prepared by treating the same composition except that diatomaceous earth and zinc stearate were not mixed in the silicone composition 1 in the same manner as described above. Example 4 The silicone rubber composition 1 of Example 1 was replaced with a 50% silicone paste of bis (4-t-butylcyclohexyl) peroxydicarbonate, which is an organic peroxide, and had an average primary particle size of 50 microns. A silicone rubber composition 8 was prepared by treating the same composition except that the one having a maximum particle size of 100 microns (organic peroxide ') was used. Comparative Example 5 Silicone rubber composition 9 was prepared by treating silicone composition 1 of Example 1 with the same composition except that no organic peroxide was added, and treating the same as described above.

Next, these silicone rubber compositions 1 to
9 was formed into a rod having a diameter of 6 mm using an extruder having a diameter of 6 mm, and was subjected to normal-pressure hot air vulcanization at 300 ° C. for 13 seconds to obtain a cured product. The vulcanization characteristics and the presence or absence of microvoids were examined. Further, the silicone rubber compositions 1 to 9 were added in a thickness of 40 mm.
Using a φ extruder, a tin-plated annealed copper wire with a diameter of 0.6 mm was coated and molded to produce an electric wire with an outer diameter of 1.2 mm.Then, the vulcanization temperature was 350 ° C and the residence time was 30 seconds. The electric wire was subjected to a withstand voltage test and a cut strip property test.
The results are summarized in Tables 1 to 3. It was confirmed that the product obtained from the silicone rubber composition of the present invention exhibited higher withstand voltage, better core wire adhesion, and cut stripping properties than those of the comparative example.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

Note) Tackability ○: No tack ×: Tack

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 83/07 C08L 83/07 H01B 3/28 H01B 3/28 7/02 7/02 FF term (reference) 4J002 CP031 DJ016 DJ037 EF029 EF059 EH029 EK048 EK088 EP019 FD016 FD017 FD148 FD209 GQ01 5G305 AA02 AA14 AB34 AB36 AB40 BA15 BA22 BA26 CA26 CB13 CB14 CC02 CD01 CD05 5G309 RA11 RA12

Claims (4)

[Claims] (A) An average composition formula (I) R¹ _aSiO_{(4-a) / 2} ... (I) (where R¹Are the same or different unsubstituted or substituted monovalent hydrocarbons
Prime group, a is a positive number between 1.95 and 2.05)
Containing an alkenyl group in an amount of 0.02 to 2.0 mol%
Nopolysiloxane 100 parts by weight (B) BET specific surface area is 50m^Two/ g or more finely divided silica
20 to 100 parts by weight (C) Diatomaceous earth and / or quartz powder 5 to 200 parts by weight (D) Fatty acid or aliphatic derivative and / or metal thereof
Salt 0.01 to 5 parts by weight (E) The following formula (II)(Wherein X is an alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms)
An alkoxy group of the formula -SiR^Two _Three, -CH_TwoSiR^Two _Three(R^TwoIs hydrogen field
N, a methyl group or an alkoxy group), n
Is an organic peroxide (E-1) represented by 1 or 2) and
Mixing of Peroxydicarbonates (E-2) Solid at Temperature
For electric wires characterized by comprising 0.1 to 10 parts by weight of compound
Silicone rubber composition. 2. The organic peroxide (E-1) and the peroxydicarbonates (E-2) are each solid at room temperature, have an average primary particle size of 5 to 20 microns, and have a maximum The silicone rubber composition for an electric wire according to claim 1, wherein the particle size is 50 microns or less. 3. The organic peroxide (E-1) is bis (4-methylbenzoyl) peroxide, and the peroxydicarbonates (E-2) are bis (4-t-butylcyclohexyl) peroxydioxide. 3. The silicone rubber composition for an electric wire according to claim 1, wherein the composition is a carbonate. 4. A silicone rubber-coated electric wire obtained by vulcanizing the silicone rubber composition for an electric wire according to any one of claims 1 to 3 around a core wire made of a copper wire or a tin-plated copper wire. .