JP2006225420A - Addition-curable silicone rubber composition and pressure-sensitive adhesive rubber sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an addition-curable silicone rubber composition that is excellent in moldability and gives a cured product having surface tackiness, appropriate rubber hardness and rubber strength, and heat resistance, and a pressure-sensitive adhesive rubber sheet obtained by curing the composition. <P>SOLUTION: The addition-curable silicone rubber composition comprises (A) an organopolysiloxane containing at least two alkenyl groups bonded to a silicon atom in one molecule, (B) a resinous copolymer mainly composed of an R<SB>3</SB>SiO<SB>1/2</SB>unit (wherein R is a monovalent hydrocarbon group) and an SiO<SB>2</SB>unit with a molar ratio [R<SB>3</SB>SiO<SB>1/2</SB>/SiO<SB>2</SB>] of 0.5-1.5 and the total amount of R of 0-0.0001 mol/g, (C) an organohydrogenpolysiloxane containing at least two Si-H groups in one molecule, (D) a fine powder silica, (E) a heat resistance-imparting agent and (F) an addition reaction catalyst, and gives the cured product having surface tackiness. The pressure-sensitive adhesive rubber sheet is obtained by curing the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to an addition-curable silicone rubber composition that provides tackiness, and more specifically, an addition-curable silicone rubber composition that provides a rubber sheet with a small decrease in adhesive strength even when the cured rubber sheet is exposed to high temperatures. And an adhesive rubber sheet obtained by curing the composition.

  Conventionally, a rubber sheet has been used as a fixing sheet for various parts and tools, for example, fixing medical instruments in hospitals and the like, and fixing tableware in restaurants and party venues. Moreover, it is utilized as a conveyance sheet | seat in the assembly process of various micro components and thin piece components using the adhesive force. In particular, adhesive rubber sheets with excellent heat resistance can be used in processes that require heating, such as adhesive curing, washing, and solder reflow, so they can be used in applications that cannot be used with ordinary adhesives. In the manufacturing process of electronic components such as capacitors, actuators, inductors, etc., these components are used for fixing and transporting. Or it is used for the process of manufacturing the electronic device which has the process of mounting an electronic component etc. on the surface of a thin printed wiring board including a flexible printed wiring board, and the process of mounting the said printed wiring board in an electronic device. . Japanese Patent Application Laid-Open No. 2002-170788 (Patent Document 1) exemplifies a silicone pressure-sensitive adhesive material used in such a process, but the specific composition of the silicone is not described at all.

  The pressure-sensitive adhesive is also called a pressure-sensitive adhesive, and has a property of easily adhering to the surface of an object with a pressure small enough to be pressed with a fingertip. Such adhesives are used for adhesive products such as cellophane tape, vinyl tape for electrical insulation, masking tape, and adhesive sheet. As the pressure-sensitive adhesive used for these pressure-sensitive adhesive tapes and sheets, those mainly composed of natural rubber, synthetic rubber, etc. are used, but these pressure-sensitive adhesive compositions are easily deteriorated by heat, light, etc. However, there is a problem that the adhesiveness decreases at low temperatures. In contrast, silicone adhesives have excellent heat resistance, cold resistance, and electrical characteristics unique to silicones, and can have adhesiveness without impairing these characteristics, so that a high degree of reliability is required. Widely used in various adhesive products.

These silicone pressure-sensitive adhesives include silicone pressure-sensitive adhesives comprising a polysiloxane having (CH ₃ ) ₃ SiO _0.5 units and SiO ₂ units and a condensate of dimethyl silicone raw rubber, and hydrosilyl alkenyl group-containing organopolysiloxanes and organohydrogenpolysiloxanes. Addition-type silicone pressure-sensitive adhesives based on a chemical reaction (see Patent Documents 2 and 3: Japanese Patent Publication No. 54-37907 and Japanese Patent Application Laid-Open No. 63-22886) are known. However, these adhesives mainly form a thin film by coating and utilize the adhesiveness of the surface, and are not mentioned at all about rubber hardness and strength. Actually, even if these compositions are used as rubber sheets, the adhesive strength is sufficient, but since they do not have rubber strength, they are not suitable for use in the manufacturing process of fixed sheets for jigs and electronic parts that are used repeatedly. In particular, a pressure-sensitive adhesive material used for a production line of various electronic components has a heating step, and therefore, it is preferable to use silicone rubber having good heat resistance. However, in these production lines, for example, in a solder reflow process, the temperature may be 250 ° C. or higher, and further heat resistance is required.

  Japanese Patent Application Laid-Open No. 2004-189945 (Patent Document 4) shows a high-strength silicone rubber adhesive material, but there is no description about heat resistance, and there is no specific example of adding a heat resistance imparting agent. . In addition, JP 2004-190013 A (Patent Document 5) exemplifies the addition of a hindered amine as a heat resistance imparting agent, but the amine compound has a hydrosilylation catalyst poison which is a crosslinking reaction of silicone rubber. Therefore, it is not preferable and cannot be used particularly for molding in a short time.

JP 2002-170788 A Japanese Patent Publication No.54-37907 JP-A-63-22886 JP 2004-189945 A JP 2004-190013 A

  The present invention has been made in view of the above circumstances, and has excellent moldability, surface tackiness, and appropriate rubber hardness and rubber strength. Addition-curable silicone rubber composition that can be suitably used as an adhesive-fixing sheet and has a heat resistance, and therefore provides a cured product that can withstand a heating process such as solder reflow, and an adhesive rubber sheet obtained by curing this composition The purpose is to provide.

  As a result of intensive studies to achieve the above object, the present inventor has excellent moldability by making an addition-curable silicone rubber composition containing the following components (A) to (D). The cured product of the composition has surface tackiness and has appropriate rubber hardness and rubber strength, so it can be suitably used as an adhesive fixing sheet in the production line of electronic parts that are used repeatedly, and it is also heat resistant. Therefore, the present inventors have found that it can be an adhesive rubber sheet that can withstand a heating process such as solder reflow, and has led to the present invention.

Therefore, the present invention
(A) Organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule: 30 to 95 parts by mass
(B) R ₃ SiO _1/2 unit (wherein R is an unsubstituted or substituted monovalent hydrocarbon group) and SiO ₂ unit as main components, and the moles of R ₃ SiO _1/2 unit and SiO ₂ unit A resinous material having a ratio [R ₃ SiO _1/2 / SiO ₂ ] of 0.5 to 1.5 and R containing no alkenyl group or a total amount of 0.0001 mol / g or less. Polymer: 5-70 parts by mass
(However, the sum of the components (A) and (B) is 100 parts by mass).
(C) Organohydrogenpolysiloxane containing hydrogen atoms bonded to at least two silicon atoms in one molecule: 0.2 to 30 parts by mass
(D) Fine powder silica: 1 to 200 parts by mass,
(E) Heat resistance imparting agent: 0.05 to 50 parts by mass,
(F) Addition reaction catalyst: an addition-curable silicone rubber composition containing a catalytic amount, the cured product having surface tackiness, and an adhesive rubber sheet obtained by curing the composition provide.

  The addition-curable silicone rubber composition of the present invention has excellent moldability, and the cured product has high rubber strength and surface adhesiveness, and has excellent heat resistance with little decrease in adhesive strength even when exposed to high temperatures. Can be a sheet.

  The component (A) of the addition-curable silicone rubber composition of the present invention is an organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule. The organopolysiloxane of the component (A) As for, what is shown by the following average compositional formula (1) can be used.

R ¹ _a SiO _{(4-a) / 2} (1)
In the above formula (1), R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and at least two of R ¹ are An alkenyl group. a is a positive number in the range of 1.5 to 2.8, preferably 1.8 to 2.5, more preferably 1.95 to 2.05.

Here, examples of the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and tert-butyl. Group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, alkyl group such as decyl group, aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenylethyl group, Aralkyl groups such as phenylpropyl group, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, alkenyl groups such as octenyl groups, and some or all of the hydrogen atoms of these groups Substituted with a halogen atom such as fluorine, bromine or chlorine, a cyano group, etc., for example, a chloromethyl group, Roropuropiru group, bromoethyl group, trifluoropropyl group, but cyanoethyl group and the like, Preferably, at least 90 mol% of all R ¹ is a methyl group.

In this case, at least two of R ¹ are alkenyl groups (preferably those having 2 to 8 carbon atoms, more preferably those having 2 to 6 carbon atoms, and particularly preferably vinyl groups). is necessary. Preferably, 0.001 to 10 mol%, particularly 0.01 to 5 mol% of the total R ¹ is an alkenyl group. This alkenyl group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both.

  The structure of the organopolysiloxane basically has a linear structure in which the main chain is composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. , A partially branched structure, a ring structure or the like may be used. The molecular weight is not particularly limited, and can be used from a low-viscosity liquid to a high-viscosity raw rubber-like one. Usually, the average degree of polymerization (for example, the weight average degree of polymerization) or the number of silicon atoms in one molecule is 100 to 100. It may be about 50,000, preferably 200 to 20,000, more preferably about 250 to 10,000.

The resinous copolymer of the component (B) of the present invention contains R ₃ SiO _1/2 units and SiO ₂ units as main components. Here, R is an unsubstituted or substituted monovalent hydrocarbon group, preferably having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms. Examples of the monovalent hydrocarbon group represented by R include a methyl group, Alkyl groups such as ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, phenyl group, tolyl group Aryl groups such as xylyl group and naphthyl group, aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl Alkenyl groups such as groups, and some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine and chlorine, Those substituted with a group such as, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group and the like.

The resinous copolymer of the component (B) may be composed only of the R ₃ SiO _1/2 unit and the SiO ₂ unit, and if necessary, the R ₂ SiO unit or the RSiO _3/2 unit. (R is as described above) may be contained in a total amount of 50% or less, preferably 40% or less, based on the total copolymer mass. However, R ₃ SiO _1/2 units and SiO ₂ units may be included. The molar ratio [R ₃ SiO _1/2 / SiO ₂ ] is 0.5 to 1.5, preferably 0.5 to 1.3. Even if this molar ratio is smaller than 0.5 or larger than 1.5, the tackiness is lowered.

  Furthermore, the resinous copolymer of component (B) has an alkenyl group content of 0.0001 mol / g or less (that is, 0 mol / g or more and 0.0001 mol / g or less), preferably 0.00005 mol. / G or less (that is, 0 to 0.00005 mol / g), more preferably not containing an alkenyl group. If the alkenyl group is contained in an amount of more than 0.0001 mol / g, sufficient adhesive strength cannot be obtained.

  The resinous copolymer may be a liquid that is fluid at room temperature (for example, 25 ° C.) or a solid that is not fluid. However, the resinous copolymer may be solid at room temperature in terms of stickiness of the cured product. preferable. This resinous copolymer can be usually produced by hydrolyzing an appropriate chlorosilane or alkoxysilane by a method well known in the art.

  The blending amount of the resinous copolymer of the component (B) is an amount of 5 to 70% by mass, preferably 10 to 60% by mass, based on the total amount of the component (A) and the component (B). Is the amount. If it is less than 5% by mass, sufficient tackiness cannot be obtained, and if it exceeds 70% by mass, the tackiness is also lowered and the rubber physical properties are also markedly lowered.

  The component (C) of the present invention is an organohydrogenpolysiloxane having at least 2, preferably 3 or more hydrogen atoms (Si-H groups) bonded to silicon atoms in one molecule. The H group crosslinks with the alkenyl group bonded to the silicon atom in the components (A) and (B) by a hydrosilyl addition reaction to cure the composition, and thus acts as a curing agent. The organohydrogenpolysiloxane of component (C) is at least 2 (usually about 2 to 200), preferably 3 or more (usually about 3 to 100), more preferably 3 to 50 per molecule. Those having one silicon-bonded hydrogen atom and those represented by the following average composition formula (2) are preferably used. In addition, even if this silicon atom-bonded hydrogen atom (Si-H group) is present at the end of the molecular chain (that is, on a monofunctional siloxy unit), it is in the middle of the molecular chain (on a bifunctional or trifunctional siloxane unit). Or both of them may be present.

R ² _b H _c SiO _{(4-bc) / 2} (2)
(Wherein R ² is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, b is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0.)

Here, examples of the monovalent hydrocarbon group for R ² include the same groups as those exemplified for R ¹ , but those having no aliphatic unsaturated group are preferred. Further, b is preferably 0.8 to 2.0, c is preferably 0.01 to 1.0, and b + c is preferably 1.0 to 2.5. The molecular structure of the organohydrogenpolysiloxane is linear, cyclic, Either a branched structure or a three-dimensional network structure may be used.

  In this case, the number of silicon atoms in one molecule (or the degree of polymerization) is preferably 2 to 300, particularly about 4 to 150 at room temperature (25 ° C.). In addition, the hydrogen atom couple | bonded with a silicon atom may be located in any of the molecular chain terminal and the middle of a molecular chain, and may be located in both.

Examples of the organohydrogenpolysiloxane of the component (C) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogensiloxane cyclic polymer, methyl Hydrogensiloxane / dimethylsiloxane cyclic copolymer, tris (dimethylhydrogensiloxy) methylsilane, tris (dimethylhydrogensiloxy) phenylsilane, trimethylsiloxy-group-capped methylhydrogenpolysiloxane, trimethylsiloxy-group-capped dimethylsiloxane・ Methylhydrogensiloxane copolymer, dimethylpolysiloxane blocked with dimethylhydrogensiloxy at both ends, dimethylsiloxane blocked with dimethylhydrogensiloxy at both ends ・ Methylhigh Roger emissions copolymer, both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane copolymers, both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer, (CH _{3) 2} HSiO Copolymer consisting of _1/2 units and SiO _4/2 units, Copolymer consisting of (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) SiO _3/2 units Examples include coalescence.

  The compounding amount of the organohydrogenpolysiloxane is 0.2 to 30 parts by mass and preferably 0.5 to 15 parts by mass with respect to 100 parts by mass as a total of the components (A) and (B). Even if the blending amount is less than 0.2 parts by mass, even if it exceeds 30 parts by mass, sufficient rubber strength cannot be obtained.

The fine powder silica of the component (D) of the present invention is added to improve the rubber strength and may be any one having SiO ₂ as a main component, preferably fumed silica, One selected from precipitated silica, diatomaceous earth, pulverized quartz, and fused quartz may be used alone or in combination of two or more.

The average particle diameter of the finely divided silica is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. If the average particle diameter exceeds 20 μm, not only the rubber strength cannot be improved, but also the lowering is caused. There is. For silica other than fumed silica and precipitated silica, the average particle size is preferably 0.5 μm or more, particularly preferably 1 μm or more. As for fumed silica and precipitated silica, the primary particle diameter is sufficiently smaller than 5 μm (usually about 0.001 to 1 μm), but it is preferable to define the specific surface area. In this case, the specific surface area according to the BET method is preferably 50 to 400 m ² / g, more preferably 80 to 350 m ² / g. In the present invention, the average particle diameter can be measured, for example, as a cumulative weight average value D ₅₀ (or median diameter) in a particle size distribution measurement by a laser light diffraction method.

  These finely divided silicas may be used as they are, but those previously treated with a surface hydrophobizing agent may be used, or one or two or more types of silicones of components (A), (B), (C) You may use what processed by adding a surface treating agent at the time of kneading | mixing with oil (namely, in the compounding process of a composition). These surface treatment agents may be any known ones such as alkylalkoxysilanes, alkylchlorosilanes, alkylsilazanes, silane coupling agents, titanate-based treatment agents, fatty acid esters, etc. Two or more kinds may be used simultaneously or at different timings.

  Moreover, the compounding quantity of these fine powder silica is 1-200 mass parts with respect to a total of 100 mass parts of (A) and (B) component, and it is preferable that it is 3-100 mass parts. If the blending amount is less than 1 part by mass, sufficient rubber strength cannot be obtained, and if it exceeds 200 parts by mass, blending becomes difficult.

  (E) The heat resistance imparting agent of the component is anything from hydrates, carbonates, organic acid salts, various organic antioxidants such as BHT, metal oxides, etc. used in silicone rubber for the purpose of improving heat resistance. But you can. Among these, metal oxides are particularly preferable because they do not adversely affect the tackiness and curability. Examples of such metal oxides include iron oxide, titanium oxide, cerium oxide, magnesium oxide, aluminum oxide, and zinc oxide, and iron oxide and cerium oxide are particularly preferable. These can be used individually by 1 type or in mixture of 2 or more types.

  The compounding amount of these heat resistance imparting agents is 0.05 to 50 parts by mass, preferably 0.2 to 20 parts by mass with respect to 100 parts by mass as a total of the components (A) and (B). When the blending amount is less than 0.05 parts by mass, the heat resistance is hardly improved, and when it exceeds 50 parts by mass, the physical properties of the rubber are deteriorated.

  Examples of the addition reaction catalyst for component (F) include platinum black, platinous chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and an olefin, platinum bisacetoacetate, etc. Platinum-based catalysts, palladium-based catalysts, rhodium-based catalysts, and the like. In addition, the compounding quantity of this addition reaction catalyst can be made into a catalyst quantity, and 0.5-1,000 ppm with respect to the total mass of (A), (B), (C) component normally as a platinum group metal, Particularly, it is about 1 to 500 ppm.

  As other components, a conductive agent such as carbon black, conductive zinc white, and metal powder, and a filler such as a color pigment may be blended as necessary, as long as the object of the present invention is not impaired. Furthermore, hydrosilylation reaction control agents such as nitrogen-containing compounds, acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates, tin compounds, mercury compounds, sulfur compounds, internal mold release agents such as dimethyl silicone oil, adhesion imparting agents, thixotropes It is optional to add a property-imparting agent or the like as appropriate.

  Besides these, a solvent may be added for the purpose of reducing the viscosity. Any solvent may be used as long as it can dissolve silicone and has a boiling point of 200 ° C. or lower. For example, xylene, toluene, benzene, heptane, hexane, cyclohexane, trichloroethylene, perchloroethylene, methylene chloride, ethyl acetate, methyl isobutyl ketone, methyl ethyl ketone, butanol, ligroin, cyclohexanone, diethyl ether, petroleum ether, industrial gasoline, rubber volatilization Examples thereof include organic solvents such as oil and silicone solvent, and these may be used alone or in combination of two or more as a mixed solvent.

  The pressure-sensitive adhesive rubber sheet of the present invention can be obtained by curing an addition-curable silicone rubber composition containing the above components. In this case, as a method for obtaining an adhesive rubber sheet using the silicone rubber composition of the present invention, more specifically, a method for directly obtaining the above-mentioned silicone rubber composition by compression molding, injection molding, injection molding, etc. There are a method of forming a sheet on a metal substrate, a resin substrate, a resin film by insert molding, or a method of obtaining a rubber sheet integrated with a base material by dipping, coating, screen printing or the like.

  The curing conditions for the addition-curable silicone rubber composition are preferably in the range of 10 seconds to 1 hour at a temperature of 80 to 250 ° C. Furthermore, after-curing may be performed at a temperature of 120 to 250 ° C. for about 1 to 100 hours for the purpose of removing low molecular siloxane. Moreover, 0.05-50 mm is preferable and, as for the thickness of rubber sheet itself, More preferably, it is 0.1-20 mm. If it is less than 0.05 mm, it may be insufficient to make use of the elasticity of the sheet, and if it exceeds 50 mm, it is disadvantageous in terms of cost.

  The rubber sheet thus obtained has adhesiveness on the surface, and the surface adhesive force measured by a texture analyzer (manufactured by Texture Technologies Corp.) is 20 to 300 g, particularly 30 to 200 g. Further, in the present invention, it is preferable that the adhesive strength of the cooled rubber sheet after being left in an oven at 250 ° C. for 12 hours maintains 70% or more, particularly 80% or more of the initial adhesive strength.

  The hardness of the rubber sheet of the present invention is preferably in the range of 5 to 50, more preferably in the range of 5 to 40 with a durometer A hardness meter. If it is less than 5, the strength as rubber may be insufficient, and if it exceeds 50, the adhesiveness may be lowered. The rubber strength is preferably 0.5 MPa or more, more preferably 0.8 MPa or more, as measured by JIS K6249. If it is less than 0.5 MPa, when it is used in a production line for electronic parts, it is easily broken, and there is a possibility that it cannot withstand repeated use.

  The adhesive rubber sheet of the present invention can be used as an adhesive fixing sheet in the production of various electronic components such as chip-type electronic components such as capacitors, actuators and inductors, and mounting of flexible printed boards.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In each example, “part” indicates “part by mass”, “average particle diameter” indicates a value measured as a cumulative weight average value (D ₅₀ ) in particle size distribution measurement by laser beam diffraction method, and “specific surface area” indicates a value measured by BET method. Show.

[Example 1]
A resinous material comprising 60 parts of dimethylpolysiloxane (1) having an average degree of polymerization of 300 blocked at both ends with dimethylvinylsiloxy groups, and (CH ₃ ) ₃ SiO _1/2 units and SiO ₂ units solid at room temperature Polymer (2) [(CH ₃ ) ₃ SiO _1/2 unit / SiO ₂ unit (molar ratio) = 0.75] 40 parts, hydrophobized with a specific surface area of 110 m ² / g as fine powder silica 8 parts of fumed silica (manufactured by Nippon Aerosil Co., Ltd., R-972) and 1 part of iron oxide (Fe ₂ O ₃ ) with an average particle size of 0.10 μm are put in a planetary mixer and mixed for 30 minutes. One pass through the roll. In 100 parts of this silicone rubber base, methyl hydrogen polysiloxane (3) having a Si—H group in the molecular side chain (that is, on the siloxane unit in the middle of the molecular chain) as a crosslinking agent (polymerization degree 20, Si—H group) 0.99 parts of 0.0060 mol / g) and 0.05 parts of ethynylcyclohexanol as a reaction control agent were added, and stirring was continued for 15 minutes to obtain a silicone rubber composition. This silicone rubber composition was mixed with 0.1 part of a platinum catalyst (Pt concentration 1%), and a 2 mm thick rubber sheet having a sticky surface was obtained by press curing at 120 ° C. for 10 minutes. Table 1 shows the results of measurement of rubber hardness (durometer A), tensile strength, and elongation at break based on JIS K6249 from this 2 mm sheet. Furthermore, the surface adhesive strength was measured from a 2 mm sheet with a texture analyzer (manufactured by Texture Technologies Corp.), the rubber sheet was allowed to stand in an oven at 250 ° C. for 12 hours, cooled, and then the adhesive strength was measured again. The results are shown in Table 1.

[Example 2]
70 parts of dimethylpolysiloxane (1) of Example 1, 15 parts of fumed silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g, 3 parts of hexamethyldisilazane, and 1 part of water The mixture was kneaded at 150 ° C. for 2 hours. 30 parts of the resinous copolymer (2) of Example 1 was added thereto, and the kneading was further continued at 150 ° C. for 2 hours. In 100 parts of this silicone rubber base, 0.5 part of cerium oxide having an average particle diameter of 1 μm and 2 parts of titanium oxide having an average particle diameter of 0.2 μm, Si—H groups are added to the molecular side chain of Example 1 as a crosslinking agent. 1.26 parts of methylhydrogenpolysiloxane (3) having and 0.05 part of ethynylcyclohexanol as a reaction control agent were added, and stirring was continued for 15 minutes to obtain a silicone rubber composition. This silicone rubber composition was mixed with 0.1 part of a platinum catalyst (Pt concentration: 1%), and a rubber sheet having a thickness of 2 mm having adhesiveness on the surface was obtained by press curing at 120 ° C. for 10 minutes. About this hardened | cured material, the rubber hardness (durometer A), tensile strength, elongation at the time of cutting | disconnection, and the surface adhesive force before and behind a heat test were measured similarly to Example 1. FIG. The results are shown in Table 1.

[Example 3]
60 parts of dimethylpolysiloxane (4) (vinyl group content: 0.0002 mol / g) having an average degree of polymerization of 500 having vinyl groups bonded to Si atoms in the molecular side chain at both ends blocked with trimethylsiloxy groups, Resinous copolymer (5) [(CH ₃ ) ₃ SiO ₁ // consisting of (CH ₃ ) ₃ SiO _1/2 units, SiO ₂ units and (CH ₃ ) ₂ SiO units which are solid at room temperature and dissolved in toluene. ₂ units / SiO ₂ units (molar ratio) = 0.80, (CH ₃ ) ₂ SiO content 15 mol%] 40 parts (resin content) were mixed at room temperature, and the solvent was removed at 120 ° C. under reduced pressure for 3 hours. After removal, stirring was continued for another hour. To 100 parts of this silicone rubber base, 10 parts of diatomaceous earth with an average particle diameter of 7 μm, 30 parts of quartz powder with an average particle diameter of 2 μm, 1 part of iron oxide (Fe ₂ O ₃ ) with an average particle diameter of 0.3 μm, as a crosslinking agent 2.25 parts of methylhydrogenpolysiloxane (3) having a Si—H group in the molecular side chain of Example 1 and 0.05 part of ethynylcyclohexanol as a reaction control agent were added, and stirring was continued for 15 minutes. A rubber composition was obtained. This silicone rubber composition was mixed with 0.1 part of a platinum catalyst (Pt concentration: 1%), and a rubber sheet having a thickness of 2 mm having adhesiveness on the surface was obtained by press curing at 120 ° C. for 10 minutes. About this hardened | cured material, the rubber hardness (durometer A), tensile strength, elongation at the time of cutting | disconnection, and the surface adhesive force before and behind a heat test were measured similarly to Example 1. FIG. The results are shown in Table 1.

[Comparative Example 1]
60 parts of dimethylpolysiloxane (1) of Example 1, 40 parts of resinous copolymer (2) of Example 1, and hydrophobized fumed silica having a specific surface area of 110 m ² / g as fine powder silica ( 8 parts of Nippon Aerosil Co., Ltd., R-972) were put into a planetary mixer, mixed for 30 minutes, and then passed once through three rolls. To 100 parts of this silicone rubber base, 0.99 parts of methyl hydrogen polysiloxane (3) having a Si—H group in the molecular side chain of Example 1 as a crosslinking agent, and 0.05 parts of ethynylcyclohexanol as a reaction control agent And stirring was continued for 15 minutes to obtain a silicone rubber composition. This silicone rubber composition was mixed with 0.1 part of a platinum catalyst (Pt concentration: 1%), and a rubber sheet having a thickness of 2 mm having adhesiveness on the surface was obtained by press curing at 120 ° C. for 10 minutes. About this hardened | cured material, the rubber hardness (durometer A), tensile strength, elongation at the time of cutting | disconnection, and the surface adhesive force before and behind a heat test were measured similarly to Example 1. FIG. The results are shown in Table 1.

[Comparative Example 2]
55 parts of dimethylpolysiloxane (1) of Example 1, 15 parts of fumed silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g, 3 parts of hexamethyldisilazane, and 1 part of water The mixture was kneaded at 150 ° C. for 2 hours. 30 parts of the resinous copolymer (2) of Example 1 was added thereto, and the kneading was further continued at 150 ° C. for 2 hours. To 100 parts of this silicone rubber base, 1.26 parts of methylhydrogenpolysiloxane (3) having a Si—H group in the molecular side chain of Example 1 as a crosslinking agent, and 0.05 part of ethynylcyclohexanol as a reaction control agent And stirring was continued for 15 minutes to obtain a silicone rubber composition. This silicone rubber composition was mixed with 0.1 part of a platinum catalyst (Pt concentration: 1%), and a rubber sheet having a thickness of 2 mm having adhesiveness on the surface was obtained by press curing at 120 ° C. for 10 minutes. About this hardened | cured material, the rubber hardness (durometer A), tensile strength, elongation at the time of cutting | disconnection, and the surface adhesive force before and behind a heat test were measured similarly to Example 1. FIG. The results are shown in Table 1.

[Comparative Example 3]
60 parts of the dimethylpolysiloxane (4) of Example 3 and 40 parts of the resinous copolymer (5) of Example 3 dissolved in toluene were mixed at room temperature, and the solvent was removed under reduced pressure at 120 ° C. for 3 hours. Thereafter, stirring was continued for another hour. 100 parts of this silicone rubber base, 1 part of iron oxide (Fe ₂ O ₃ ) having an average particle size of 0.3 μm, and methylhydrogenpolysiloxane (3) having a Si—H group in the molecular side chain of Example 1 as a crosslinking agent 2) and 0.05 part of ethynylcyclohexanol as a reaction control agent were added and stirring was continued for 15 minutes to obtain a silicone rubber composition. This silicone rubber composition was mixed with 0.1 part of a platinum catalyst (Pt concentration: 1%), and a rubber sheet having a thickness of 2 mm having adhesiveness on the surface was obtained by press curing at 120 ° C. for 10 minutes. About this hardened | cured material, the rubber hardness (durometer A), tensile strength, elongation at the time of cutting | disconnection, and the surface adhesive force before and behind a heat test were measured similarly to Example 1. FIG. The results are shown in Table 1.

Claims (9)

(A) Organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule: 30 to 95 parts by mass
(B) R ₃ SiO _1/2 unit (wherein R is an unsubstituted or substituted monovalent hydrocarbon group) and SiO ₂ unit as main components, and the moles of R ₃ SiO _1/2 unit and SiO ₂ unit A resinous material having a ratio [R ₃ SiO _1/2 / SiO ₂ ] of 0.5 to 1.5 and R containing no alkenyl group or a total amount of 0.0001 mol / g or less. Polymer: 5-70 parts by mass
(However, the sum of the components (A) and (B) is 100 parts by mass).
(C) Organohydrogenpolysiloxane containing hydrogen atoms bonded to at least two silicon atoms in one molecule: 0.2 to 30 parts by mass
(D) Fine powder silica: 1 to 200 parts by mass,
(E) Heat resistance imparting agent: 0.05 to 50 parts by mass,
(F) Addition reaction catalyst: An addition-curable silicone rubber composition comprising a catalytic amount, and the cured product has surface tackiness.   2. The addition-curable silicone rubber composition according to claim 1, wherein the resinous copolymer of component (B) contains substantially no alkenyl group and is solid at room temperature.   The addition-curable silicone rubber composition according to claim 1 or 2, wherein the heat resistance imparting agent of component (E) is a metal oxide.   4. The addition-curable silicone rubber composition according to claim 3, wherein the metal oxide is selected from iron oxide, cerium oxide, titanium oxide, aluminum oxide, magnesium oxide and zinc oxide.   The addition-curable silicone rubber composition according to any one of claims 1 to 4, wherein the cured silicone rubber has a durometer A hardness of 5 to 50 and a tensile strength of 0.5 MPa or more.   The addition-curable silicone rubber composition according to any one of claims 1 to 5, wherein the cured silicone rubber has an adhesive strength after standing for 12 hours at 250 ° C of 70% or more of the initial adhesive strength.   An adhesive rubber sheet obtained by curing the addition-curable silicone rubber composition according to any one of claims 1 to 6.   The pressure-sensitive adhesive rubber sheet according to claim 7, which is used for fixing an electronic component. The pressure-sensitive adhesive rubber sheet according to claim 8, wherein the electronic component is a chip-type electronic component selected from a capacitor, an actuator and an inductor, or a flexible printed board.