JPH1076606A - Silicone rubber laminate and method for producing the same - Google Patents

Abstract

(57) Abstract: In a silicone rubber laminate obtained by laminating and integrating a conductive silicone rubber cured layer containing carbon black and an insulating silicone rubber cured layer, the insulating silicone rubber cured layer is formed by ( a) an organopolysiloxane represented by the following average composition formula (1): R _a SiO _{(4-a) / 2} (1), which contains two or more alkenyl groups in one molecule and has a degree of polymerization of 200 or more; ,
A silicone rubber formed from a cured body of an insulating silicone rubber composition containing (b) a reinforcing silica and (c) an organic peroxide represented by the following general formula (2). Laminate. Embedded image [Effect] The silicone rubber laminate of the present invention has excellent adhesion between the cured conductive silicone rubber layer and the cured insulating silicone rubber layer.
It is highly reliable as a contact material for electrical and electronic components. Further, according to the production method of the present invention, the silicone rubber laminate can be produced reliably and easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber laminate and a method for producing the same, and more particularly to a silicone rubber laminate comprising a conductive silicone rubber layer containing carbon black and an insulating silicone rubber layer. And a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a laminate composed of a conductive silicone rubber containing carbon black and an insulating silicone rubber has been used for a zebra connector, a contact rubber or the like.
It is widely used as an electrical contact material for electric and electronic parts. Conventionally, various proposals have been made for the composition and production method of the conductive or insulating silicone rubber layer of the silicone rubber laminate comprising the conductive silicone rubber containing carbon black and the insulating silicone rubber. . For example, a method of forming a conductive silicone rubber cured layer containing carbon black using an organic peroxide, laminating an uncured silicone rubber on this, and curing this using an organic peroxide (particularly, Kosho 56-4
No. 1417), 5 to 75% by weight of carbon black
A silicone rubber cured part contained therein, and an organopolysiloxane having at least two alkenyl groups in one molecule, an organohydrogenpolysiloxane, and a reinforcing silica filler as main components, and a SiH group in the organohydrogenpolysiloxane. Silicone rubber having an addition reaction-curable silicone rubber cured part using a platinum-based catalyst containing no carbon black and having a molar ratio of 0.8 / 1 to 6/1 to alkenyl groups in the organopolysiloxane Molded body and method for producing the same (Japanese Patent Publication No. 61-349)
No. 82), an addition-curable conductive silicone rubber cured portion using a platinum-based catalyst containing 5 to 75% by weight of carbon black, and a non-acyl organic peroxide vulcanization type containing substantially no carbon black A silicone rubber molded body in which a cured silicone rubber portion is integrated and a method for producing the same (JP-B-61-39188) have been proposed.

[0003]

However, these silicone rubber laminates are obtained by laminating an uncured insulating silicone rubber layer on a cured portion of a conductive silicone rubber containing carbon black, and curing the layer. , The adhesiveness between the two silicone rubber layers is not sufficient, which may cause a problem in long-term stability. For example, when these laminates are used as electrical contact materials for electronic devices, if the environment in which the electronic devices are used is controlled by air conditioning, the adhesion between the conductive silicone rubber layer and the insulating silicone rubber layer is almost zero. Although this is not a problem, electronic devices are now used in all kinds of environments.In some cases, they are used in high-temperature, high-humidity environments. May cause problems. For this reason, it is desired to improve the adhesiveness between the conductive silicone rubber layer and the insulating silicone rubber layer particularly when these laminates are used as an electrical contact material such as a zebra connector and to improve the reliability thereof. I have.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silicone rubber laminate excellent in adhesion between a conductive silicone rubber layer and an insulating silicone rubber layer and a method for producing the laminate. Aim.

[0005]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that insulating silicone laminated on a cured carbon black-containing conductive silicone rubber layer is obtained. The rubber cured layer is formed by: (a) the following average composition formula (1): R _a SiO _{(4-a) / 2} (1) (wherein R represents a hydroxyl group or a substituted or unsubstituted monovalent hydrocarbon group, , R is an alkenyl group in which 0.0001 to 0.5 mol% is an alkenyl group. A represents a positive number of 1.95 to 2.05), and contains two or more alkenyl groups in one molecule; An insulating silicone rubber composition comprising an organopolysiloxane having a degree of polymerization of 200 or more, (b) reinforcing silica, and (c) an organic peroxide represented by the following general formula (2): Insulation with conductive silicone rubber layer by forming with cured product It found that silicone rubber laminate adhesion to silicone rubber layer is significantly improved. In this case, the insulating silicone rubber cured layer is formed by laminating the insulating silicone rubber composition in an uncured state on a cured conductive silicone rubber containing carbon black, and curing the same to cure the conductive silicone rubber. It is easily performed by a method of forming an insulating silicone rubber cured layer on a silicone rubber cured body, can be vulcanized at a temperature of 150 ° C or less, has excellent adhesion between both layers, and can be used under high temperature and high humidity conditions. It has been found that a silicone rubber laminate in which the risk of peeling between cured silicone rubber layers is prevented can be reliably obtained.

[0006]

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In particular, the present invention is to greatly improve the adhesion between the conductive silicone rubber layer and the insulating silicone rubber layer by using a special organic peroxide. That is, as a prior art using an organic peroxide as a vulcanizing agent, Japanese Patent Publication No. 56-41417 is mentioned, but there is no reference to the special organic peroxide shown in the present invention,
With the exemplified organic peroxide, it is difficult to obtain excellent adhesion at a relatively low temperature. On the other hand, with a low-temperature vulcanizable organic peroxide such as an acyl peroxide, the carbon black-containing silicone rubber composition cannot be vulcanized. On the other hand, the special organic peroxide used in the present invention can be cross-linked at a lower temperature than the conventionally used organic peroxide. It has also been found that there is an advantage that the dimensional accuracy of the above can be easily obtained.

Accordingly, the present invention provides a silicone rubber laminate in which a conductive silicone rubber cured layer containing carbon black and an insulating silicone rubber cured layer are integrated into a laminate, wherein the cured insulating silicone rubber layer comprises the above (a) (A) a cured product of the insulating silicone rubber composition containing the component (c) as described above, and (a) a cured product of the conductive silicone rubber containing carbon black. Laminating an insulating silicone rubber composition containing the components (c) to (c) as described above in an uncured state, and curing this to form a cured insulating silicone rubber layer on the cured conductive silicone rubber. The present invention provides a method for producing a silicone rubber laminate characterized by the following.

Hereinafter, the present invention will be described in more detail.
As described above, the silicone rubber laminate of the present invention is obtained by integrally laminating a conductive silicone rubber cured layer containing carbon black and an insulating silicone rubber cured layer. The adhesiveness between the two silicone rubber layers is greatly improved by being formed from a cured product of a specific silicone rubber composition described later.

Here, the cured insulating silicone rubber layer comprises: (a) the following average composition formula (1): R _a SiO _{(4-a) / 2} (1) (where R is a hydroxyl group or a substituted or unsubstituted A substituted monovalent hydrocarbon group, wherein 0.0001 to 0.5 mol% of R is an alkenyl group; a is a positive number of 1.95 to 2.05); An organopolysiloxane containing at least two alkenyl groups therein and having a degree of polymerization of at least 200; (b) reinforcing silica; and (c) an organic peroxide represented by the general formula (2). And an insulating silicone rubber composition containing no carbon black or any other conductivity-imparting agent.

The above components will be described in detail. The organopolysiloxane of the component (a) is in the form of a liquid or a raw rubber, and is represented by the following average composition formula (1). R _a SiO _{(4-a) / 2} ... (1)

In the formula (1), R represents a hydroxyl group or a substituted or unsubstituted, preferably monovalent hydrocarbon group having 1 to 10, particularly 1 to 6, carbon atoms. Mol%, preferably 0.01 to 0.3 mol% is a vinyl group,
An alkenyl group such as an allyl group, which contains two or more alkenyl groups in one molecule. When the content of the alkenyl group is less than 0.0001 mol%, the curability of the organopolysiloxane becomes insufficient, while when it is more than 0.5 mol%, the properties of the cured product deteriorate. . Examples of R groups other than alkenyl groups include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group and dodecyl group; phenyl group, tolyl group and the like. An aralkyl group such as a β-phenylethyl group; and a group in which part or all of the hydrogen atoms bonded to carbon atoms of these hydrocarbons are substituted with a halogen atom such as fluorine or a cyano group (for example, 3 , 3,3-trifluoropropyl group and cyanoethyl group), but the R group other than the alkenyl group is generally a methyl group. However, when cold resistance, radiation resistance and transparency are required, the R group may have a maximum of 20 mol%, especially 3 to 10 mol%.
It is preferred to include a phenyl group of Further, when oil resistance and gasoline resistance are required, a cyanoethyl group or a 3,3,3-trifluoropropyl group may be used as the R group.
It is preferable that the content is about 99 mol%. In the above formula (1), a is a number of 1.95 to 2.05, preferably 1.98 to 2.02, and the degree of polymerization is 200 or more, preferably 300 to 10,000.

The organopolysiloxane of the component (a) is substantially composed of diorganopolysiloxane units, but may contain small amounts of triorganosiloxane units, monoorganosiloxane units and SiO ₂ units. Further, the terminal of the molecular chain may be blocked with a hydroxyl group or a triorganosiloxy unit.

As the reinforcing silica of the component (b), a specific surface area (BET) is used to impart appropriate hardness to silicone rubber and to improve mechanical strength such as tensile strength.
Law) is 50 m ² / g or more, it is particularly preferred to use a silica of 100 to 400 m ² / g. Specific examples of such silica include fumed silica, calcined silica, and precipitated silica. These can be used alone or in combination of two or more. These silicas may be surface-treated with a reactive silane such as chlorosilane, alkoxysilane, or silane coupling agent, a chain organopolysiloxane, a cyclic organopolysiloxane, or hexamethyldisilazane.

The amount of the reinforcing silica of the component (b) is 5 to 100 parts, preferably 5 to 5 parts, per 100 parts (parts by weight, hereinafter the same) of the organopolysiloxane of the component (a).
0 parts is preferred. If it is less than 5 parts, the reinforcing properties of the silicone rubber will be insufficient, and if it is more than 100 parts, the compounding and workability may be difficult.

The organic peroxide as the component (c) is represented by the general formula (2), and the role of the organic peroxide to greatly improve the adhesion between the conductive silicone rubber layer and the insulating silicone rubber layer. It fulfills.

[0017]

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The monovalent hydrocarbon group having 3 to 10 carbon atoms includes an alkyl group, an alkenyl group, an aryl group, an aralkyl group and the like, and an alkyl group is particularly preferable.

The amount of the component (c) is 0.1 to 100 parts of the organopolysiloxane (a).
If the amount is less than 5 parts, the vulcanization is insufficient, the desired characteristics cannot be obtained, and the material cannot be put to practical use.If the amount exceeds 5 parts, an adverse effect due to an excessive decomposition residue appears or unnecessary cost increases. This is preferably in the range of 0.1 to 5 parts.

In this composition, a dispersant such as a silanol-terminated polysiloxane having a degree of polymerization of 20 or less, a silane containing a silanol group, a silane containing an alkoxy group, a heat-resistant improver such as iron oxide, cerium oxide, iron octylate, and a pigment are used. Such,
Further, it is optional to add other additives that are added to the ordinary silicone rubber composition, but as described above, the conductivity-imparting agent is not substantially added, and the silicone obtained from this composition is not added. Rubber is usually 1 × 10 ¹⁰ Ωcm or more,
Preferably, it is formed to have an insulating property of 1 × 10 ¹³ Ω · cm or more.

The composition is obtained by uniformly mixing the components (a) to (c) and, if necessary, a predetermined amount of optional components. The order of blending these components is not particularly limited. After mixing the organopolysiloxane as the component with the reinforcing silica as the component (b) to form a silicone rubber compound, the organic peroxide as the component (c) is added, and the mixture may be mixed by kneading with a roll or the like. .

On the other hand, the conductive silicone rubber cured layer is obtained by blending carbon black with a silicone rubber composition and imparting conductivity, and is usually adjusted to a conductivity of 10 ⁴ Ω · cm or less. Can be The silicone rubber composition constituting the conductive silicone rubber cured layer may be a silicone rubber curable by any curing method such as an organic peroxide curing type, an addition reaction curing type, and a room temperature curing type.

In particular, as the organic peroxide-curable silicone rubber composition, a liquid or raw rubber-like silicone rubber composition having an average composition formula (1) having at least two alkenyl groups per molecule.
R _a SiO _{(4-a) / 2} (R and a have the same meanings as above)
A compound obtained by mixing 0.01 to 5 parts, especially 0.05 to 3 parts of an organic peroxide per 100 parts of the organopolysiloxane represented by the formula (1) and optionally adding a filler and other components is suitably used. In this case, the organic peroxide can be used without particular limitation as long as it is generally used for curing a peroxide-curable carbon black-containing silicone rubber composition. 6-bis (t-butylperoxycarbonyloxy) hexane, di-t-butyl peroxide, 2,5-dimethyl-di-t
-Butylperoxyhexane, t-butylperbenzoate, t-butylperoxyisopropyl carbonate, dicumyl peroxide and the like. These may be used alone or in combination of two or more. In particular, a percarbonate organic peroxide represented by the above general formula (2) such as 1,6-bis (t-butylperoxycarbonyloxy) hexane is preferable. In addition, this organic peroxide-curable silicone rubber composition is 100%
The composition can be easily cured by heating at a temperature of about 250 ° C. for about 5 minutes to 5 hours.

Further, as the addition reaction-curable silicone rubber composition, at least two, and preferably three or more, SiHs in a molecule are based on 100 parts of the organopolysiloxane represented by the above average composition formula (1). Having a viscosity of 1 to 10,000 cs, preferably 2 to 5,
The organohydrogensiloxane having a molecular weight of 2,000 cs is replaced with an alkenyl group 1 in the organopolysiloxane of the formula (1).
0.5 to 10 moles, particularly 1 to 3 moles of SiH groups
It is possible to use a mixture in which the catalyst is added in a molar amount and a catalytic amount of an addition reaction catalyst such as platinum or a platinum compound.

In this case, examples of the carbon black compounded in the silicone rubber composition include acetylene black, furnace black, channel black, and thermal black. It is desirable to use black and furnace black. The amount of carbon black is not particularly limited.
The conductive silicone rubber cured layer has a conductivity of usually 10 ⁴ Ω · cm or less, preferably 0.01 to 100 Ω.
Cm, especially 0.1 to 10 Ωcm.

The method for forming the cured layer of the conductive silicone rubber can be a conventional method, and specific examples include compression molding, extrusion molding, injection molding, transfer molding and the like.

The silicone rubber compositions constituting the insulating silicone rubber cured layer and the conductive silicone rubber cured layer may be reinforced in addition to the above components, if necessary, to the extent that their properties are not impaired. Alternatively, a filler can be blended for the purpose of increasing the amount. Known fillers are used as the filler, for example, diatomaceous earth, iron oxide, zinc oxide, metal oxides such as titanium oxide, or those whose surfaces have been subjected to hydrophobic treatment with silane, calcium carbonate, magnesium carbonate, Metal carbonates such as zinc carbonate,
Examples include asbestos, glass fiber, carbon black, fine mica, and fused silica powder. Further, in these compositions, if necessary, thixotropic agents such as polyethylene glycol and derivatives thereof, pigments, dyes,
It is optional to add an antioxidant, an antioxidant, an antistatic agent, a flame retardant such as antimony oxide and paraffin chloride, a thermal conductivity improver such as boron nitride and aluminum oxide, and an amino acid as an adhesive agent. Various known organic compounds such as organosilicon compounds having a reactive organic group such as an epoxy group, a mercapto group, a silane coupling agent, a plasticizer, an anti-sagging agent, an antifouling agent, an antiseptic, a bactericide, and a fungicide. Additives may be mixed.

The silicone rubber laminate of the present invention is obtained by laminating the above-mentioned cured conductive silicone rubber layer and cured insulating silicone rubber layer. After forming a cured silicone rubber layer, an insulating silicone rubber composition containing the above components (a) to (c) is compression-molded thereon,
Lamination by extrusion molding, injection molding, transfer molding, and the like, and a method of forming a cured silicone rubber layer by heating and curing can be used. A silicone rubber laminate having excellent adhesion can be easily and reliably obtained. In this case, the molding and curing temperature of the insulating silicone rubber composition is 150 ° C. or less, preferably 10 ° C.
0-150 degreeC is good. Other conditions for forming the insulating silicone rubber cured layer can be ordinary conditions.

The form of the silicone rubber laminate of the present invention is not particularly limited. For example, a plate-like laminate in which a conductive silicone rubber sheet and an insulating silicone rubber sheet are laminated on each other, or a cylindrical conductive silicone rubber cured product A rod-shaped laminate in which the outer peripheral surface of the body is covered with a cured layer of an insulating silicone rubber or the like can be formed into various forms depending on its use and the like. Further, the cured conductive silicone rubber layer and the cured insulating silicone rubber layer are not limited to one layer each, and two or more layers of each layer or one layer may be laminated.

[0030]

The silicone rubber laminate of the present invention has excellent adhesion between the cured conductive silicone rubber layer and the cured insulating silicone rubber layer, and is reliable as a contact material for electric and electronic parts such as zebra connectors and contact rubber. It is highly likely. Further, according to the production method of the present invention, the silicone rubber laminate can be produced reliably and easily.

[0031]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight.

Examples 1 and 2 and Comparative Examples 1 to 5 KE manufactured by Shin-Etsu Chemical Co., Ltd. was used as a conductive silicone rubber composition.
Using 3801 MU, 2.0 parts of C-19A manufactured by Shin-Etsu Chemical Co., Ltd. as an addition-type curing catalyst and 100 parts of C-19B2.
After adding 5 parts and mixing uniformly, press molding (pressure 35 kg / cm ² G) was performed at 165 ° C. for 10 minutes, and 10 cm ×
A carbon black-containing conductive silicone rubber sheet of 10 cm × 1 mm (thickness) was prepared. The conductivity of this silicone rubber sheet was 3.0 Ω · cm.

On the other hand, (CH ₃ ) ₂ SiO unit is 99.76
Mol%, (CH ₃ ) (CH ₂ ＣＨCH) SiO unit is 0.2
(C) having 15 mol% and a molecular chain terminal of 0.025 mol%
A kneader is charged with 100 parts of a methylvinylpolysiloxane raw rubber (component (a)) having a polymerization degree of about 8,000, which is blocked with H ₂ ＝ CH) (CH ₃ ) SiO _1/2 units. (Nipsil Lp manufactured by Nippon Silica Co., Ltd.)
(Component (b)) 45 parts and 5 parts of dimethylpolysiloxane (degree of polymerization: about 10) both ends of which are blocked with a hydroxyl group are charged, uniformly kneaded, and heated at 170 ° C. for 2 hours.
A base compound was prepared. A predetermined amount of each of the vulcanizing agents shown in Table 1 was added to 100 parts of the base compound, and the mixture was uniformly mixed with two rolls to prepare an insulating silicone rubber composition.

Next, the conductive silicone rubber sheet was charged into a mold of 10 cm × 10 cm × 2 mm (thickness), and the insulating silicone rubber composition was press-molded on this sheet under the vulcanization conditions shown in Table 1. Pressure 35kg / cm
² G) to obtain a silicone rubber laminate. At this time, a non-adhesive portion was formed with a Teflon sheet having a thickness of 0.5 mm interposed between the laminated rubbers. The vulcanized state, hardness, tensile strength, elongation and linear shrinkage of the obtained silicone rubber laminate were measured. Table 1 shows the results.

A test piece obtained by cutting this silicone rubber laminate to a width of 1 cm was allowed to stand for 96 hours at a temperature of 50 ° C. and a relative humidity of 90%. Then, as shown in FIG. A 180 ° peel test is performed in which the silicone rubber layers are pulled at a rate of 50 mm / min in directions opposite to each other by 180 ° (in the direction of the arrow in the figure) to measure the adhesive force of the two silicone rubber layers and the peeled state of the two silicone rubber layers. Was observed. Table 1 shows the results. In the figures, 1 is a silicone rubber laminate, 2 is an insulating silicone rubber cured layer, 3 is a conductive silicone rubber cured layer, and 4 is a non-adhesive portion.

From the results shown in Table 1, it was confirmed that the silicone rubber laminate of the present invention had an extremely high adhesive force between the conductive layer and the insulating layer.

[0037]

[Table 1] Vulcanizing agent a: 1,6-bis- (t-butylperoxycarbonyloxy) hexane b: bis (2,4-dichlorobenzoyl) peroxide 50% silicone paste c: 2,5-dimethyl-di-t -Butyl peroxyhexane

Example 3 KE3801MU manufactured by Shin-Etsu Chemical Co., Ltd. was used as a conductive silicone rubber composition, and 1,6-bis- (t-butylperoxy) was used as an organic peroxide in 100 parts of the composition. Carbonyloxy) hexane (1.0 part) was added and mixed uniformly.
Press molding (pressure 35 kg / cm ² G) for 10 minutes
A carbon black-containing conductive silicone rubber sheet of mx 10 cm x 1 mm (thickness) was prepared. The conductivity of this silicone rubber sheet was 3.1 Ω · cm.

On the other hand, as the insulating silicone rubber-based compound, the compound used in Example 1 was used.
Other test methods and conditions were evaluated in the same manner as in Example 1. Table 2 shows the results.

[0040]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an adhesion test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicone rubber laminated body 2 Insulated silicone rubber cured layer 3 Conductive silicone rubber cured layer 4 Non-adhesion part

Claims (5)

[Claims] 1. A silicone rubber laminate obtained by laminating and integrating a conductive silicone rubber cured layer containing carbon black and an insulating silicone rubber cured layer, wherein the cured insulating silicone rubber layer has the following average composition: Formula (1) R _a SiO _{(4-a) / 2} (1) (wherein R represents a hydroxyl group or a substituted or unsubstituted monovalent hydrocarbon group, and 0.0001 to 0.5 mol of R) % Is an alkenyl group, a represents a positive number of 1.95 to 2.05), and an organopolysiloxane containing two or more alkenyl groups in one molecule and having a degree of polymerization of 200 or more. , (B) a reinforcing silica, and (c) an organic peroxide represented by the following general formula (2). A silicone rubber laminate formed from a cured product of an insulating silicone rubber composition containing: 2. The conductive silicone rubber cured layer containing carbon black comprises a cured product of an organic peroxide-curable silicone rubber composition containing an organic peroxide represented by the general formula (2). The laminate according to claim 1. 3. The laminate according to claim 1, wherein the cured conductive silicone rubber layer containing carbon black comprises a cured product of an addition-curable silicone rubber composition. 4. In producing a silicone rubber laminate in which a conductive silicone rubber cured layer containing carbon black and an insulating silicone rubber cured layer are integrally formed, said conductive silicone rubber cured layer is formed on said conductive silicone rubber cured layer. A method for producing a silicone rubber laminate, comprising laminating the insulative silicone rubber composition as described above in an uncured state, and curing the laminate. 5. The production method according to claim 4, wherein the curing temperature of the insulating silicone rubber composition is 150 ° C. or lower.