Addition-curable silicone rubber composition and cured product thereof

Abstract

Provided is an addition-curable silicone rubber composition that provides an addition-curable silicone rubber that has oil-bleeding properties and self-adhesive properties. [Solution] A composition containing the following components (A) to (F): (A) (A-1) a polysiloxane having two or more silicon-bonded alkenyl groups and no aromatic hydrocarbon groups, (A-2) a polysiloxane having two or more silicon-bonded alkenyl groups and at least one aryl group or aralkyl group per molecule, (B-1) an organosilicon compound having at least one phenylene skeleton or phenyl group per molecule and at least one silicon-bonded hydrogen atom per molecule, (B-2) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule, (C) a platinum group metal catalyst, (D) a specific silicone oil: 1 to 10 parts by mass per 100 parts by mass of component (A), and (E) an organic compound having one or more isocyanate groups.

Description

[Technical Field]

[0001] The present invention relates to an addition-curable silicone rubber composition having self-adhesive properties and oil-bleeding properties, and a cured product thereof. [Background technology]

[0002] Silicone rubber has traditionally been widely used in a variety of fields, including building materials, electrical and electronic components, automotive parts, and office equipment components, due to its excellent heat resistance, weather resistance, durability, and electrical properties. Its widespread use in automotive parts has been remarkable, with applications including oil seals, gaskets and rubber stoppers for wire connectors, O-rings, diaphragms, and distributor grommets. In particular, connectors and distributor grommets require ease of assembly, sealing after installation, waterproofing, and insulation. For these applications, silicone rubber that allows oil to bleed onto the surface of molded products is known to be effective, and silicone rubber with oil-bleeding properties is widely used for these applications. In recent years, silicone rubber has also been used in many parts combined with metals and organic resins.

[0003] Meanwhile, many methods have been proposed for obtaining articles in which a cured product of an addition-cure silicone rubber composition is integrated with a metal or organic resin. Typical methods include applying a primer to the surface of the molded resin, then applying and curing an uncured silicone rubber composition on top of that to bond them together, applying an adhesive to the interface to integrate the two, incorporating the two by entrapment through two-color molding, and curing a self-adhesive silicone rubber composition on top of the molded resin.

[0004] However, methods using adhesives or primers not only increase the number of steps, but also have problems such as staining the non-adhered surfaces depending on the application method. Furthermore, methods using two-color molding have problems such as restrictions on the shape of the integrated product and insufficient adhesion at the interface. In contrast, a self-adhesive silicone rubber composition in which an adhesive is added to a silicone rubber composition eliminates the need for the above-mentioned application step, thereby shortening work time, reducing costs, and improving workability. Therefore, self-adhesive silicone rubber compositions in which an adhesive is added are an effective means for producing integrally molded products with resin.

[0005] Furthermore, many methods have been reported for adhering an addition-type heat-curable silicone rubber composition to an organic resin in primerless molding. For example, there is a method of curing a self-adhesive silicone rubber composition on a resin, and many techniques for specifying adhesive components have been proposed for this self-adhesive silicone rubber composition. For example, Patent Documents 1 and 2 describe an integrally molded product of an oil-bleeding silicone rubber and a resin in which a thermoplastic oligomer containing an aliphatic unsaturated group is blended with the thermoplastic resin (Patent Document 1: JP 9-165516 A, Patent Document 2: JP 9-165517 A). In addition, Patent Documents 3, 4, and 5 describe a method in which an organohydrogenpolysiloxane having a SiH bond and an aromatic skeleton in one molecule is added to a silicone rubber composition with self-adhesive properties as an adhesion improver to bond it to organic resins or metals (Patent Document 3: JP 6-172738 A, Patent Document 4: JP 2001-200162 A, and Patent Document 5: JP 2008-537967 A). In addition, Patent Documents 6 and 7 describe a method in which an organic compound having one or more isocyanate groups in one molecule is added to a silicone rubber composition as an adhesion improver to bond it to organic resins or metals (Patent Document 6: JP 2011-099090 A, Patent Document 7: WO 2021 / 210273). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-165516 [Patent Document 2] Japanese Patent Application Publication No. 9-165517 [Patent Document 3] Japanese Patent Application Publication No. 6-172738 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-200162 [Patent Document 5] Special Publication No. 2008-537967 [Patent Document 6] Japanese Patent Application Laid-Open No. 2011-099090 [Patent Document 7] International Publication No. 2021 / 210273 Summary of the Invention [Problem to be solved by the invention]

[0007] However, no addition-cure silicone rubber that possesses both self-adhesive properties and oil-bleeding properties is known. The present invention has been made in consideration of the above circumstances, and its object is to provide an addition-cure silicone rubber composition that provides a silicone rubber that combines oil-bleeding properties and self-adhesive properties, and a cured silicone rubber obtained by curing said composition. [Means for solving the problem]

[0008] The present inventors have investigated the addition of phenyl-modified silicone oil to further impart oil-bleeding properties to addition-curable silicone rubber compositions with self-adhesive properties. However, if the amount of phenyl-modified silicone oil added is increased to the extent that sufficient oil-bleeding properties are obtained, the adhesion between the resulting silicone rubber and organic resins or metals is significantly reduced. On the other hand, if the amount of phenyl-modified silicone oil added is reduced to the extent that sufficient adhesion between organic resins or metals is obtained, the oil-bleeding properties are not sufficiently obtained.

[0009] As a result of extensive research into achieving the above object, the present inventors discovered that an addition-curable silicone rubber composition containing specific amounts of the components (A) to (E) described below as essential components provides a silicone rubber that has sufficient adhesive strength to a wide range of organic resins and also has good oil-bleed properties, leading to the creation of the present invention.

[0010] That is, the present invention provides an addition-curable silicone rubber composition shown in [1] below. [1] An addition-curable silicone rubber composition containing the following components (A) to (E): (A) 100 parts by mass of an organopolysiloxane consisting of the following components (A-1) and (A-2): (A-1) Organopolysiloxane having at least two alkenyl groups bonded to silicon atoms in each molecule and no aromatic hydrocarbon groups: 90 to 97 parts by mass (A-2) 3 to 10 parts by mass of an organopolysiloxane having at least two alkenyl groups bonded to silicon atoms in each molecule, and at least one aryl group having 6 to 10 carbon atoms or one aralkyl group having 7 to 10 carbon atoms bonded to a silicon atom in each molecule, wherein the ratio (%) of the number of aryl groups and aralkyl groups to the total number of groups bonded to silicon atoms is 2 to 40%. (B-1) An organosilicon compound having 1 to 100 silicon atoms, which has at least one phenylene skeleton or phenyl group per molecule and at least one hydrogen atom bonded to a silicon atom per molecule: 0.05 to 10 parts by mass per 100 parts by mass of the component (A). (B-2) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in each molecule and having no aromatic hydrocarbon groups: 0.2 to 30 parts by mass per 100 parts by mass of the component (A); (C) Platinum group metal catalyst: Catalyst amount (D) Silicone oil represented by the following general formula (1): 1 to 10 parts by mass per 100 parts by mass of the component (A) [ka] (In formula (1), R 1 are each independently an alkyl group having 1 to 10 carbon atoms, n is a number from 1 to 50, m is a number from 0 to 50, and p is a number from 1 to 50, the ratio (%) of the number of phenyl groups bonded to silicon atoms to the total number of alkyl groups and phenyl groups bonded to silicon atoms is 20% or more and 50% or less, and the siloxane units enclosed in parentheses in general formula (1) may be bonded randomly or may form a block structure. (E) An organic compound other than the above components (A) and (B), which has at least one functional group selected from an alkenyl group, an alkoxysilyl group, and a hydrosilyl group in one molecule and at least one isocyanate group in one molecule: 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

[0011] Furthermore, the present invention provides a silicone rubber composition further having one or more components selected from the following [2] to [5]. [2] The addition-curable silicone rubber composition according to [1] above, wherein the component (E) is an organosilicon compound represented by the following general formula (2): [ka] (In the formula, R 2 are each independently an alkyl group having 1 to 3 carbon atoms, and k is an integer of 1≦k≦10). [3] The addition-curable silicone rubber composition according to [1] or [2] above, further comprising (F) at least one reaction inhibitor selected from acetylene alcohol compounds and compounds in which the alcoholic hydroxyl group of an acetylene alcohol compound is modified with silane or siloxane, in an amount such that 1 to 500 moles of acetylene are present per mole of platinum atoms in component (C). [4] The addition-curable silicone rubber composition according to any one of [1] to [3] above, further comprising (G) a reinforcing filler in an amount of 5 to 100 parts by mass per 100 parts by mass of component (A). [5] The component (G) has a specific surface area of ​​50 m2 by the BET method. 2 / g or more. The present invention further provides a cured silicone rubber product obtained by curing the addition-curable silicone rubber composition according to any one of the above items [1] to [5]. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an addition-cure silicone rubber composition that can give a silicone rubber that has excellent self-adhesion to various organic resins and oil-bleeding properties, and a cured silicone rubber obtained by curing the composition. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in more detail below.

[0014] In this specification, the degree of polymerization is a value determined based on the weight average molecular weight in terms of polystyrene obtained by GPC (gel permeation chromatography) analysis using tetrahydrofuran (THF) as a developing solvent, measured under the following conditions. [Measurement conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) TSKgel SuperH2000(6.0mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 10 μL (0.5 wt% tetrahydrofuran solution)

[0015] (A) Alkenyl group-containing organopolysiloxane Component (A) is the base polymer (main component) of the addition-curable silicone rubber composition, and is a combination of the following components (A-1) and (A-2). (A-1) Organopolysiloxane having at least two alkenyl groups bonded to silicon atoms per molecule and no aromatic hydrocarbon groups: 90 to 97 parts by weight per 100 parts by weight of component (A). (A-2) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and at least one silicon-bonded aryl group having 6 to 10 carbon atoms or one silicon-bonded aralkyl group per molecule, wherein the ratio (%) of the number of aryl groups and aralkyl groups to the total number of groups bonded to silicon atoms is 2 to 40%: 3 to 10 parts by mass per 100 parts by mass of component (A); Each component will be described in detail below.

[0016] Component (A-1) Component (A-1) is an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule and no aromatic hydrocarbon groups. This component is part of the base polymer (main component) of the addition-curable silicone rubber composition of the present invention.

[0017] The molecular structure of component (A-1) is preferably linear. Among these, diorganopolysiloxanes whose main chain is essentially composed of repeating diorganosiloxane units and whose molecular chain ends are blocked with triorganosiloxy groups are preferred. In the organopolysiloxane molecule, the silicon atom to which the alkenyl group is bonded may be located at either or both of the molecular chain ends (i.e., triorganosiloxy groups) and / or in the molecular chain (i.e., difunctional diorganosiloxane units located at non-terminal positions). Component (A-1) may be used alone or in combination with two or more. A particularly preferred component (A-1) is a combination of a linear diorganopolysiloxane (a1) containing alkenyl groups bonded to silicon atoms at both molecular chain ends and a linear diorganopolysiloxane (a2) in which alkenyl groups are bonded to multiple silicon atoms in the molecular chain. The combined use of these compounds increases the rubber strength. When the compounds (a1) and (a2) are used in combination, the ratio of the amounts is not particularly limited.

[0018] In component (A-1), the alkenyl group bonded to a silicon atom is, for example, an alkenyl group having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. Examples include vinyl, allyl, propenyl, butenyl, pentenyl, hexenyl, cyclohexenyl, and heptenyl groups. Vinyl groups are particularly preferred. Component (A-1) contains two or more silicon-bonded alkenyl groups per molecule, preferably 2 to 100, and more preferably 2 to 50.

[0019] In component (A-1), the groups other than alkenyl groups bonded to silicon atoms may be substituted or unsubstituted monovalent hydrocarbon groups other than aryl groups and aralkyl groups. Examples include substituted or unsubstituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. Examples of monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Methyl groups are particularly preferred. Preferably, the organopolysiloxane represented by (A-1) does not contain an isocyanate group.

[0020] Component (A-1) is preferably a linear organopolysiloxane having a weight-average degree of polymerization of 50 to 2,000. The weight-average degree of polymerization is more preferably 100 to 1,500, and even more preferably 120 to 1,000. If the weight-average degree of polymerization of component (A-1) is below the lower limit, the mechanical properties of the cured product of the resulting addition-curable silicone rubber composition may be poor. If the weight-average degree of polymerization exceeds 2,000, the viscosity of the resulting addition-curable silicone rubber composition may be high, which may result in poor handling and workability.

[0021] Component (A-1) preferably has a viscosity of 50 to 200,000 mPa·s at 25°C. This viscosity is more preferably 100 to 150,000 mPa·s, and even more preferably 400 to 100,000 mPa·s. When the viscosity of component (A-1) is equal to or greater than the lower limit mentioned above, the resulting cured silicone rubber will have good mechanical properties. When the viscosity is equal to or less than the upper limit mentioned above, the resulting addition-curable silicone rubber composition will not have a high viscosity, and will be easy to handle and work with. In the present invention, the viscosity of the organopolysiloxane is measured at 25°C, for example, using a VISCOMATER TVB-10.

[0022] Examples of the organopolysiloxane represented by component (A-1) include a dimethylsiloxane-methylvinylsiloxane copolymer capped at both molecular chain terminals with trimethylsiloxy groups, a methylvinylpolysiloxane capped at both molecular chain terminals with trimethylsiloxy groups, a dimethylpolysiloxane capped at both molecular chain terminals with dimethylvinylsiloxy groups, a methylvinylpolysiloxane capped at both molecular chain terminals with dimethylvinylsiloxy groups, a dimethylsiloxane-methylvinylsiloxane copolymer capped at both molecular chain terminals with dimethylvinylsiloxy groups, a dimethylpolysiloxane capped at both molecular chain terminals with divinylmethylsiloxy groups, a dimethylsiloxane-methylvinylsiloxane copolymer capped at both molecular chain terminals with divinylmethylsiloxy groups, a dimethylpolysiloxane capped at both molecular chain terminals with trivinylsiloxy groups, a dimethylsiloxane-methylvinylsiloxane copolymer capped at both molecular chain terminals with trivinylsiloxy groups, and a mixture of two or more of these organopolysiloxanes.

[0023] Component (A-2) Component (A-2) is an organopolysiloxane having per molecule at least two silicon-bonded alkenyl groups and per molecule at least one silicon-bonded aryl group having 6 to 10 carbon atoms or one silicon-bonded aralkyl group having 7 to 10 carbon atoms, with the ratio (%) of the number of aryl groups and aralkyl groups to the total number of silicon-bonded groups being 2 to 40%. Like component (A-1) described above, this organopolysiloxane is part of the base polymer (main component) of the addition-curable silicone rubber composition of the present invention.

[0024] The molecular structure of component (A-2) is preferably linear. Of these, diorganopolysiloxanes whose main chain is essentially composed of repeating diorganosiloxane units and whose molecular chain ends are blocked with triorganosiloxy groups are preferred. The silicon atoms to which alkenyl groups are bonded in the organopolysiloxane molecule may be located at either or both of the molecular chain ends (i.e., triorganosiloxy groups) and / or in the middle of the molecular chain (i.e., bifunctional diorganosiloxane units located at non-terminal locations). A particularly preferred component (A-2) is a linear diorganopolysiloxane having at least alkenyl groups bonded to silicon atoms at both molecular chain ends. Component (A-2) may be used alone or in combination.

[0025] In component (A-2), examples of the alkenyl group bonded to a silicon atom include alkenyl groups having 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. More specific examples include vinyl groups, allyl groups, propenyl groups, butenyl groups, pentenyl groups, hexenyl groups, cyclohexenyl groups, and heptenyl groups, with vinyl groups being particularly preferred. Component (A-2) should have at least two, preferably 2 to 100, and more preferably 2 to 50 alkenyl groups bonded to a silicon atom per molecule.

[0026] Component (A-2) has at least one silicon-bonded aryl group having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms, preferably 7 to 8 carbon atoms. Preferred examples of the aryl group include phenyl, tolyl, xylyl, and naphthyl groups. Preferred examples of the aralkyl group include benzyl and phenethyl groups. Component (A-2) preferably has at least one phenyl group per molecule. Furthermore, in component (A-2), any group other than the aryl group, aralkyl group, and alkenyl group bonded to the silicon atom may be a substituted or unsubstituted monovalent hydrocarbon group. For example, a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, may be mentioned. Examples of monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Methyl groups are particularly preferred. Preferably, the organopolysiloxane represented by (A-2) does not contain an isocyanate group.

[0027] Component (A-2) is preferably a linear organopolysiloxane having a weight-average degree of polymerization of 50 to 2,000. The weight-average degree of polymerization is more preferably 100 to 1,500, and even more preferably 120 to 1,000. If the weight-average degree of polymerization is lower than the above lower limit, the mechanical properties of the resulting silicone rubber cured product may deteriorate. If the weight-average degree of polymerization is higher than the above upper limit, the viscosity of the resulting addition-curable silicone rubber composition may increase, which may result in poor handling and workability.

[0028] Component (A-2) preferably has a viscosity at 25°C of 50 to 200,000 mPa·s. The viscosity is more preferably 100 to 150,000 mPa·s, and even more preferably 400 to 100,000 mPa·s. If the viscosity of component (A-2) is at least the lower limit above, the mechanical properties of the cured product of the resulting addition-curable silicone rubber composition will be good. If the viscosity is at most the upper limit above, the viscosity of the resulting addition-curable silicone rubber composition will not be too high, and handling and workability will be favorable. The viscosity can be measured as described above.

[0029] The aryl and aralkyl group content in component (A-2) is 2 to 40%, expressed as a ratio (%) of the number of aryl and aralkyl groups to the total number of groups bonded to silicon atoms. The aryl and aralkyl group content is preferably 2.5 to 30%, and more preferably 2.5 to 20%. Component (A-2) preferably has at least one phenyl group per molecule, and the phenyl group content, expressed as a ratio (%) of the number of phenyl groups to the total number of groups bonded to silicon atoms, is 2 to 40%, preferably 2.5 to 30%, and more preferably 2.5 to 20%. Within the above ranges, the resulting silicone rubber can achieve both good self-adhesion and oil-bleed properties, and maintain them at a good balance.

[0030] The compounding ratio (parts by mass) of component (A-1) to component (A-2) is 90 to 97 parts by mass, preferably 91 to 97 parts by mass, and 3 to 10 parts by mass, preferably 3 to 9 parts by mass, of component (A-2) per 100 parts by mass of the total of (A-1) and (A-2). By keeping the compounding ratio of component (A-1) to component (A-2) within the above range, the obtained silicone rubber can achieve both self-adhesion and oil-bleeding properties, and maintain them in good condition.

[0031] (B) Organosilicon compounds having hydrogen atoms bonded to silicon atoms (hereinafter referred to as SiH groups) In the present invention, component (B) functions as an adhesion-imparting component and a crosslinking agent. Component (B) of the present invention is characterized by the use in combination of (B-1) an organosilicon compound having 1 to 100 silicon atoms, which has at least one phenylene skeleton or phenyl group per molecule and at least one silicon-bonded hydrogen atom (hereinafter referred to as SiH group) per molecule, and (B-2) an organohydrogenpolysiloxane other than component (B-1), which has at least two silicon-bonded hydrogen atoms per molecule and does not contain an aromatic hydrocarbon group. Each component will be described in detail below.

[0032] (B-1) Component Component (B-1) functions as an adhesion-imparting component and a crosslinking agent. Component (B-1) has at least one SiH group and at least one phenylene skeleton or phenyl group per molecule. Component (B-1) is an organosilicon compound such as organosilane or organo(poly)siloxane, having 1 to 100, preferably 2 to 50, and more preferably 2 to 30 silicon atoms per molecule. In the present invention, the term "phenylene skeleton" encompasses polyvalent aromatic ring structures such as divalent to hexavalent, particularly divalent to tetravalent, phenylene structures, naphthalene structures, and anthracene structures.

[0033] The organosilicon compound has at least one SiH group per molecule, preferably 1 to 50, more preferably 1 to 30, more preferably 1 to 20, and even more preferably 2 to 10. The organosilicon compound has at least one phenylene skeleton, preferably 1 to 4, or at least one phenyl group, preferably 1 to 10. Furthermore, the organosilicon compound may contain one or more functional groups, such as an epoxy group (e.g., a glycidoxy group), an alkoxysilyl group (e.g., a trimethoxysilyl group, a triethoxysilyl group, or a methyldimethoxysilyl group), an ester group, an acrylic group, a methacrylic group, a carboxy anhydride group, an isocyanate group, an amino group, or an amide group.

[0034] Component (B-1) is preferably an organosilane or organo(poly)siloxane having 1 to 100, preferably 2 to 30, silicon atoms per molecule, and more preferably an organosilicon compound such as a linear or cyclic organosiloxane oligomer or organoalkoxysilane having 1 to 30, preferably 2 to 20, and particularly 4 to 10 silicon atoms.

[0035] In the component (B-1), the organosilicon compound having at least one phenyl group per molecule is, for example, an organohydrogen(poly)siloxane represented by the following average composition formula (2). R 3 c H d SiO (4-c-d) / 2 (2) In the formula, R 3 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, c is 0.7 to 2.1, d is 0.001 to 1.0, and c+d is a positive number satisfying the range of 0.8 to 3.0. The organohydrogen(poly)siloxane has 1 to 100, preferably 2 to 50, silicon atoms per molecule, and at least 1, preferably 1 to 50, more preferably 2 to 30 SiH groups per molecule.

[0036] R 3 Examples of the substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, represented by the formula (I), include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenethyl, and 1-methyl-1-phenylethyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. In particular, methyl, phenyl, and aralkyl groups having 7 to 10 carbon atoms are preferred. The hydrogen atom bonded to the silicon atom and all organic groups (R 3Preferably, 2% or more of the total number of aryl or aralkyl groups bonded to silicon atoms, more preferably 3% or more, and even more preferably 5% or more. Preferably, the aryl or aralkyl groups do not contain aliphatic unsaturated groups.

[0037] c is a number from 0.7 to 2.1, preferably a number from 0.8 to 2.0; d is a number from 0.001 to 1.0, preferably a number from 0.01 to 1.0; and c+d is a positive number satisfying 0.8 to 3.0, preferably a positive number satisfying 1.0 to 2.5. The molecular structure of the organohydrogenpolysiloxane represented by (B-1) may be any of linear, cyclic, branched, and three-dimensional network structures. The number of silicon atoms (or degree of polymerization) per molecule is 1 to 100, preferably 2 to 50. The organohydrogenpolysiloxane is preferably liquid at room temperature (25°C). The hydrogen atoms bonded to the silicon atoms may be located at either the molecular chain terminals, the molecular chain midway (non-terminal), or both.

[0038] The SiH group content in the organohydrogen(poly)siloxane (B-1) is preferably 0.0005 to 0.017 mol / g, more preferably 0.0008 to 0.017 mol / g. Within this range, sufficient crosslinking can be achieved, resulting in a stable substance.

[0039] More preferred examples of the organosilicon compound include the compounds shown below. [ka]

[0040] In component (B-1), the organosilicon compound containing SiH groups and a phenylene skeleton preferably has at least three, usually 3 to 20, and particularly about 4 to 10 SiH groups per molecule and at least one, usually 1 to 20, and particularly about 2 to 10, divalent to hexavalent, preferably divalent to tetravalent, phenylene skeleton per molecule, and may further contain functional groups such as epoxy groups such as glycidoxy groups, alkoxysilyl groups such as trimethoxysilyl, triethoxysilyl, and methyldimethoxysilyl groups, ester groups, acrylic groups, methacrylic groups, carboxy anhydride groups, isocyanate groups, amino groups, and amide groups. The organosilicon compound having at least one phenylene skeleton per molecule is preferably a linear or cyclic organosiloxane oligomer or organoalkoxysilane, having 3 to 100, preferably 3 to 50, and particularly preferably about 4 to 30 silicon atoms. For example, [ka] (n is 1 to 4)

[0041] [ka] and R w , R x is an unsubstituted or substituted monovalent hydrocarbon group, where q is 1 to 50 and h is 0 to 100, preferably q is 1 to 20 and h is 1 to 50. and R" is a group represented by [ka] (Rw and Rx are the same as above, and y is 0 to 100.) and Y' is a group selected from [ka] (R w ,R x ,q,h are the same as above) and z = 1 to 10.

[0042] Furthermore, organic compounds and organosilicon compounds containing alkoxysilyl groups such as trimethoxysilyl groups, triethoxysilyl groups, and methyldimethoxysilyl groups, acrylic groups, methacrylic groups, ester groups, carboxy anhydride groups, isocyanate groups, amino groups, and amide groups can also be used.

[0043] In addition, the above R w , R x The unsubstituted or substituted monovalent hydrocarbon group preferably has 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms, and includes alkyl groups, aryl groups, aralkyl groups, alkenyl groups, as well as substituted monovalent hydrocarbon groups such as alkoxy groups, acrylic groups, methacrylic groups, acryloyl groups, methacryloyl groups, amino groups, and alkylamino groups.

[0044] The blending amount of component (B-1) is 0.05 to 10 parts by mass, preferably 0.1 to 9 parts by mass, and more preferably 0.2 to 8 parts by mass, per 100 parts by mass of component (A). When the blending amount of component (B-1) is within the above range, the resulting silicone rubber has good adhesiveness. The organosilicon compounds having a phenylene skeleton or a phenyl group may be used alone or in combination of two or more. An organosilicon compound having a phenylene skeleton and an organosilicon compound having a phenyl group may also be used in combination. When these are used in combination, the blending ratio is not particularly limited.

[0045] (B-2) Component Component (B-2) is an organohydrogenpolysiloxane different from component (B-1), which has at least two, and preferably three or more, hydrogen atoms bonded to silicon atoms (i.e., SiH groups) in one molecule, and which does not contain aromatic hydrocarbon groups such as phenyl groups or phenylene skeletons in the molecule.

[0046] The component (B-2) is more preferably an organohydrogenpolysiloxane represented by the following average composition formula (3) having at least two (e.g., 2 to 200), preferably three or more (e.g., 3 to 200), more preferably 5 to 100, and even more preferably about 8 to 50 SiH groups per molecule. R 3’ C’ H d’ SiO (4-c’-d’) / 2 (3) (In the formula, R 3’ are each independently an unsubstituted or substituted aliphatic monovalent hydrocarbon group having 1 to 12 carbon atoms, and c ’ is a number between 0.7 and 2.1, and d ’ is a number between 0.001 and 1.0, and c ’ +d ’ is a positive number between 0.8 and 3.0)

[0047] In the above formula, R 3’ Examples of the unsubstituted or substituted aliphatic monovalent hydrocarbon group having 1 to 12 carbon atoms, represented by the formula (I), include monovalent hydrocarbon groups having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, and heptyl; halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl; and cyano-substituted alkyl groups. R 3’ does not include an aryl group such as a phenyl group or an aromatic hydrocarbon group such as an aralkyl group. 3’ is preferably an aliphatic saturated hydrocarbon from which an aliphatic unsaturated bond such as an alkenyl group is excluded. 3’ is preferably an alkyl group, particularly a methyl group. Preferably, the organohydrogenpolysiloxane represented by (B-2) does not have an isocyanate group.

[0048] c ’ is a number from 0.7 to 2.1, preferably a number from 0.8 to 2.0, and d ’is a number from 0.001 to 1.0, preferably a number from 0.01 to 1.0, and c ’ +d ’ is a positive number that satisfies the range of 0.8 to 3.0, and preferably a positive number that satisfies the range of 1.0 to 2.5.

[0049] The molecular structure of the organohydrogenpolysiloxane represented by (B-2) may be any of linear, cyclic, branched, and three-dimensional network structures. The number of silicon atoms (or degree of polymerization) per molecule is preferably 2 to 300, more preferably 3 to 200, even more preferably 10 to 200, and even more preferably 15 to 100. The organohydrogenpolysiloxane is preferably liquid at room temperature (25°C). The hydrogen atoms bonded to the silicon atoms may be located at the molecular chain terminals, midway along the molecular chain (non-terminal positions), or both.

[0050] Examples of organohydrogenpolysiloxanes represented by component (B-2) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogencyclopolysiloxane, methylhydrogencyclosiloxane-dimethylsiloxane cyclic copolymer, tris(dimethylhydrogensiloxy)methylsilane, methylhydrogenpolysiloxane capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends with trimethylsiloxy groups, dimethylpolysiloxane capped at both ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends with dimethylhydrogensiloxy groups, and (CH3)2HSiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)3SiO units 1 / 2 Units and (CH3)2HSiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units 1 / 2 Units and SiO 4 / 2 Units and (CH3)SiO 3 / 2 A copolymer consisting of (CH3)2HSiO units 1 / 2Units and SiO 4 / 2 Units and (CH3)2SiO 2 / 2 The component (B-2) may be a copolymer consisting of a copolymer ...

[0051] The content of SiH groups in the component (B-2) is preferably 0.0005 to 0.017 mol / g, and more preferably 0.0008 to 0.017 mol / g. If it is within this range, crosslinking will be sufficient and a stable substance will be obtained.

[0052] The blend amount of component (B-2) is 0.2 to 30 parts by mass, preferably 0.2 to 20 parts by mass, and particularly preferably 0.3 to 15 parts by mass, per 100 parts by mass of component (A). Within this range, good curability and good compression set are achieved.

[0053] The total amount of components (B-1) and (B-2) is such that the ratio of the total number of Si-H groups in components (B-1) and (B-2) to the total number of alkenyl groups in the composition of the present invention (total number of Si-H groups / total number of alkenyl groups) is 2.0 to 3.0, and more preferably 2.0 to 2.8. Within this range, the curability of the composition is improved. The total number of alkenyl groups in the composition of the present invention particularly refers to the alkenyl groups in component (A) described above. Furthermore, when a compound having alkenyl groups is added as component (E) described below, this refers to the total number of alkenyl groups in component (A) and component (E).

[0054] (C)Platinum group metal catalyst Component (C) is an addition reaction catalyst, and is a platinum group metal catalyst, such as platinum black, platinic chloride, chloroplatinic acid, reaction products of chloroplatinic acid with monohydric alcohols, complexes of chloroplatinic acid with olefins, platinum bisacetoacetate, palladium catalysts, and rhodium catalysts.

[0055] The amount of platinum group metal catalyst blended can be a catalytic amount, preferably 0.5 to 500 ppm, more preferably 1 to 200 ppm, of platinum group metal (by mass) relative to the total mass of components (A) and (B). The platinum group metal catalyst may be used alone or in combination of two or more.

[0056] (D) Component Component (D) is a silicone oil represented by the following general formula (1). [ka] In formula (1), R 1 are each independently an alkyl group having 1 to 10 carbon atoms; n is a number from 1 to 50, preferably a number from 1 to 30, and more preferably a number from 1 to 20; m is a number from 0 to 50, preferably a number from 0 to 30, and more preferably a number from 0 to 20; p is a number from 1 to 50, preferably a number from 1 to 30, and more preferably a number from 1 to 20; the ratio (%) of the number of phenyl groups bonded to silicon atoms to the total number of alkyl groups and phenyl groups bonded to silicon atoms is 20% or more and 50% or less; and the siloxane units enclosed in parentheses in general formula (1) may be bonded randomly or may form a block structure.

[0057] Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups, with a methyl group being preferred.

[0058] In the silicone oil, the ratio (%) of the number of phenyl groups bonded to silicon atoms to the total number of alkyl groups and phenyl groups bonded to silicon atoms, i.e., phenyl group content (%) = number of phenyl groups / (number of phenyl groups + number of alkyl groups) × 100, is 20% or more and less than 50%, preferably 20% or more and 45% or less, and more preferably 20% or more and 40% or less.

[0059] In the general formula (1), the siloxane units enclosed in parentheses may be bonded randomly or may form a block structure.

[0060] The blending amount of component (D) is 1 to 10 parts by mass, preferably 3 to 8 parts by mass, per 100 parts by mass of component (A). If the blending amount is less than the above lower limit, the silicone rubber may not exhibit sufficient oil-bleeding properties. On the other hand, if the blending amount is more than the above upper limit, the physical properties and heat resistance of the resulting cured product may deteriorate, and mold contamination may occur during molding.

[0061] (E) Adhesion aid Component (E) is an organic compound other than components (A) and (B) that contains at least one functional group selected from an alkenyl group, an alkoxysilyl group, and a hydrosilyl group, and at least one isocyanate group per molecule. This component is added to enhance the adhesiveness of the silicone rubber composition to organic resins. While any organic compound that satisfies the above requirements may be used as component (E), it is preferred that component (E) be an organosilicon compound containing at least one isocyanate group and at least one alkoxysilyl group (silicon-bonded alkoxy group) per molecule. However, component (E) is an organosilicon compound other than components (A) and (B), and preferably does not contain an aromatic hydrocarbon group, particularly a phenyl group or a phenylene skeleton.

[0062] Examples of component (E) include isocyanate group-containing silane coupling agents (i.e., isocyanate-functional group-containing organoalkoxysilanes) such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane; organic compounds containing an alkenyl group and an isocyanate group in one molecule, such as vinyl isocyanate, allyl isocyanate, 1-butene-4-isocyanate, 1-vinyl-2-isocyanatebenzene, 1-vinyl-3-isocyanatebenzene, 1-vinyl-4-isocyanatebenzene, 1-allyl-2-isocyanatebenzene, 1-allyl-3-isocyanatebenzene, and 1-allyl-4-isocyanatebenzene; isocyanate-functional group-containing organohydrogensiloxanes represented by the following chemical formula; mixtures of two or more of these; and partial hydrolysis condensates of one or more of these. [ka] (In the formula, k is an integer of 0 to 40, preferably an integer of 0 to 20; p is an integer of 1 to 40, preferably an integer of 1 to 20; q is an integer of 1 to 10, preferably an integer of 1 to 5; and k+p+q is an integer of 1 to 90, preferably an integer of 2 to 45.)

[0063] Preferably, the organic silicon compound is represented by the following general formula (2). [ka] In the formula, R 2 are each independently an alkyl group having 1 to 3 carbon atoms, and k is an integer of 1 to 10, preferably an integer of 1 to 8. Of these, 3-isocyanatepropyltrimethoxysilane or 3-isocyanatepropyltriethoxysilane is preferred.

[0064] The blending amount of component (E) is 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass, per 100 parts by mass of the organopolysiloxane of component (A). If the blending amount is less than the above lower limit, the resulting composition may not exhibit sufficient adhesive strength. If the blending amount exceeds the above upper limit, the composition may become more thixotropic, reducing fluidity and reducing workability. Component (E) may be used alone or in combination of two or more types.

[0065] When component (E) contains alkenyl groups, SiH groups, or both, the total amount of SiH groups contained in components (B) and (E) per mole of silicon-bonded alkenyl groups contained in components (A) and (E) in the composition is 1 to 10 moles, preferably 1.2 to 9 moles, and more preferably 1.5 to 8 moles. If the total amount of SiH groups is less than 1 mole per mole of silicon-bonded alkenyl groups in the composition, the composition may not cure sufficiently and may not exhibit sufficient adhesive strength. On the other hand, if this amount exceeds 10 moles, the heat resistance of the resulting silicone rubber cured product may be significantly inferior.

[0066] (F) Curing reaction inhibitor Component (F) is at least one curing reaction inhibitor selected from acetylene alcohol compounds and compounds in which the alcoholic hydroxyl group of an acetylene alcohol compound has been modified with silane or siloxane. Component (F) functions as a reaction inhibitor for platinum group metal catalysts, and the curing initiation time can be controlled by adjusting the amount added.

[0067] The acetylene alcohol compound of component (F) may be any compound in which an ethynyl group and a hydroxyl group are present in the same molecule, but it is preferable that the ethynyl group and the hydroxyl group are bonded to the same carbon atom. Examples include the following compounds. [ka]

[0068] Acetylenic alcohol compounds modified with silane or siloxane are compounds in which the hydroxyl group of the acetylene is converted into an Si-O-C bond and bonded to the silane or siloxane. Examples include the following compounds: [ka] In the above formula, s is an integer of 0 to 50, preferably an integer of 3 to 20, and t is an integer of 1 to 50, preferably an integer of 3 to 20.

[0069] The amount of component (F) blended is an amount such that 1 to 500 moles of acetylene are blended per mole of platinum group metal atom contained in the platinum group metal catalyst (C) described above, preferably 2 to 70 moles, more preferably 4 to 60 moles, and even more preferably 5 to 50 moles. Within the above range, good curability is achieved and a pot life sufficient for working can be obtained. The component (F) may be used alone or in combination of two or more types.

[0070] (G) Reinforcing filler The silicone rubber composition of the present invention preferably further contains a reinforcing filler. The reinforcing filler is preferably a reinforcing silica fine powder. The type of silica used for the reinforcing silica fine powder is not particularly limited, and any silica commonly used as a reinforcing agent for general rubbers may be used. The reinforcing silica fine powder may be one that has been used in conventional silicone rubber compositions. Preferably, the reinforcing silica fine powder has a specific surface area of ​​50 m2 as measured by the BET method. 2 A reinforcing fine silica powder having a specific surface area of ​​50 to 400 m / g or more as measured by the BET method is preferred. 2 / g, especially 100-350m 2 / g of precipitated silica (wet silica), fumed silica (dry silica), calcined silica, etc. are preferably used, and fumed silica is preferred because it improves rubber strength.

[0071] The reinforcing silica fine powder may be a silica fine powder whose surface has been hydrophobized with a surface treatment agent. Examples of the surface treatment agent include generally hydrolyzable organosilicon compounds such as chlorosilanes, alkoxysilanes, and organosilazanes. When the surface of the silica fine powder is hydrophobized, the silica fine powder may be directly surface-hydrophobized in advance with a surface treatment agent in a powder state, or the surface may be hydrophobized by adding a surface treatment agent when kneading the silica fine powder with a silicone oil (for example, the alkenyl-containing organopolysiloxane of component (A)).

[0072] The method for surface hydrophobization of the reinforcing silica fine powder is not particularly limited. Conventional treatment methods include well-known techniques. For example, the untreated silica fine powder and a treating agent are placed in a mechanical mixer or fluidized bed sealed at atmospheric pressure, and mixed at room temperature or by heat treatment (heating) in the presence of an inert gas, if necessary. A catalyst (such as a hydrolysis promoter) may be used to accelerate the treatment. After mixing, the mixture is dried to produce the treated silica fine powder. The amount of treating agent added may be equal to or greater than the amount calculated from the surface area covered by the treating agent.

[0073] Examples of treating agents include silazanes such as hexamethyldisilazane; silane coupling agents such as methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, vinyltris(methoxyethoxy)silane, trimethylchlorosilane, dimethyldichlorosilane, divinyldimethoxysilane, and chloropropyltrimethoxysilane; and organosilicon compounds such as polymethylsiloxane and organohydrogenpolysiloxane. Surface treatment with these agents is used to produce hydrophobic silica fine powder. Silane coupling agents or silazanes are particularly preferred as treating agents. Component (G) may be used alone or in combination of two or more.

[0074] In addition to the components described above, the addition-curable silicone rubber composition of the present invention can contain various additives depending on the purpose, such as metal oxides and composites thereof, such as titanium oxide, iron oxide, cerium oxide, vanadium oxide, cobalt oxide, chromium oxide, and manganese oxide, and inorganic fillers such as quartz powder, diatomaceous earth, calcium carbonate, magnesium carbonate, alumina, carbon, hollow glass, hollow resin, conductive inorganic powders such as gold, silver, and copper, and plating powder. Furthermore, pigments, heat resistance agents, flame retardants, plasticizers, and the like may also be added as long as the desired properties are not impaired. The amounts of these optional components added are not particularly limited and can be adjusted appropriately as long as the effects of the present invention are not impaired.

[0075] The addition-curable silicone rubber composition of the present invention is prepared by uniformly mixing the above-mentioned components (A) to (E), component (F), component (G), and other components at room temperature. When component (G) is added, it is preferable to first mix component (G) with all or part of component (A), heat-treat the mixture in a planetary mixer or kneader at 100 to 200°C for 1 to 4 hours, and then cool to room temperature to prepare a base compound. The components other than component (G) are then added to and mixed with the base compound.

[0076] The molding method can be selected appropriately depending on the viscosity of the mixture. For example, any of methods such as cast molding, compression molding, dispenser molding, injection molding, extrusion molding, and transfer molding can be used. The curing conditions for the silicone rubber composition of the present invention may be those of a general method, and the composition can be molded by heating at 60 to 200°C for 10 seconds to 1 hour, for example.

[0077] In particular, to make the most of the adhesive properties of the silicone rubber composition of the present invention, preferred methods include insert molding, in which the adherend is placed in a mold beforehand and the uncured composition is brought into contact with the adherend to cure, thereby obtaining a molded product that integrates the two, and two-color molding, in which a molten or uncured organic resin and the composition are alternately injected into a mold to obtain a unified product. To be effectively used in such molding, the silicone rubber composition of the present invention must be able to withstand a shear rate of 0.9 s at 25°C. -1 The viscosity at this temperature is preferably 50 to 5,000 Pa·s, more preferably 80 to 4,000 Pa·s, and even more preferably 100 to 3,000 Pa·s. If the viscosity is less than 50 Pa·s or more than 5,000 Pa·s, molding may become difficult. In the present invention, the viscosity of the silicone rubber composition can be measured using a shear viscometer, a HAAKE MARS40 Rheometer (manufactured by Thermo Fisher Scientific).

[0078] The addition-curable silicone rubber composition of the present invention exhibits excellent adhesion to organic resins. Examples of organic resins that can be used as adherends for this composition include typical olefin polymerization or condensation polymerization thermoplastic resins. Examples include acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate (PC) resin, polyurethane (PU) resin, styrene resin, polyethylene (PE) resin, polypropylene (PP) resin, acrylic resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyphenylene oxide (PPO) resin, polyphenylene sulfide (PPS) resin, polysulfone resin, nylon (PA) resin, aromatic polyamide (aromatic PA) resin, polyimide (PI) resin, and liquid crystal resin. Furthermore, glass fibers may be blended into the organic resin to further improve the mechanical strength of the cured product. The amount of glass fiber blended can be adjusted as needed. The cured product of the addition-curable silicone rubber composition of the present invention exhibits excellent adhesion even to substrates containing glass fibers.

[0079] The curing conditions for the addition-curable silicone rubber composition according to the present invention are preferably set to a temperature and curing time that do not cause deformation, melting, or deterioration of the resin, in order to achieve strong adhesion with thermoplastic resins, etc. Although it depends on the type of resin and the thickness of the rubber, it is possible to obtain an integrally molded product under curing conditions of 120 to 220°C for about 5 seconds to 5 minutes for resins with high softening points, and 60 to 120°C for about 15 seconds to 30 minutes for resins with low softening points. [Example]

[0080] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, parts refer to parts by mass. The average degree of polymerization refers to the weight-average degree of polymerization. In the following, the viscosity is a value measured at 25°C using a VISCOMTER TVB-10 or a Canon-Fenske viscometer manufactured by Shibata Scientific Co., Ltd. (the appropriate viscometer varies depending on the viscosity). In the following description, the phenyl group content refers to the ratio (%) of the number of phenyl groups or aralkyl groups bonded to silicon atoms to the total number of groups bonded to silicon atoms.

[0081] The components used in the examples and comparative examples are as follows: (A) Base oil (A-1-1): A linear dimethylpolysiloxane with both molecular chain ends capped with vinyldimethylsiloxy groups, an average degree of polymerization of 700, and a viscosity of 30,000 mPa·s at 25°C. (A-1-2): A linear dimethylvinylpolysiloxane represented by the following formula (4) and having a viscosity of 700 mPa·s at 25°C. [ka] (A-2-1): A linear dimethyldiphenylpolysiloxane (phenyl group content: 2.9%) represented by the following formula (5) and having a viscosity of 20,000 mPa·s at 25°C. [ka] (A-2-2): A linear dimethyldiphenylpolysiloxane (phenyl group content: 5.6%) represented by the following formula (6) and having a viscosity of 5,000 mPa·s at 25°C. [ka] (A-2-3): A linear dimethyldiphenylpolysiloxane (phenyl group content: 10.2%) represented by the following formula (7) and having a viscosity of 3,000 mPa·s at 25°C. [ka] (A-2-4): A linear dimethyldiphenylpolysiloxane (phenyl group content: 54.5%, comparative component) represented by the following formula (8) and having a viscosity of 8,000 mPa·s at 25°C. [ka]

[0082] (B) Crosslinker (B-1-1): An organosilicon compound represented by the following formula (9): [ka] (B-1-2): An organosilicon compound represented by the following formula (10): [ka] (B-2-1): A linear dimethylsiloxane-methylhydrogensiloxane copolymer (SiH group content 0.0112 mol / g) with both molecular chain ends capped with trimethylsiloxy groups, a weight-average degree of polymerization of 62, and a viscosity of 40 mPa·s at 25°C. (B-2-2): A linear dimethylsiloxane (SiH group content: 0.0013 mol / g) with both molecular chain ends capped with dimethylhydrosilyl groups, a weight-average degree of polymerization of 18, and a viscosity of 15 mPa·s at 25°C.

[0083] (C) Platinum catalyst: dimethylpolysiloxane solution containing 1% by mass of chloroplatinic acid / 1,3-divinyltetramethyldisiloxane complex as platinum atom content

[0084] (D) Bleed oil (D-1): Silicone oil represented by the following formula (11) having a phenyl group content of 25 mol % [ka] (D-2): Silicone oil represented by the following formula (12) having a phenyl group content of 62.5 mol% (component for comparative examples) [ka] (D-3): Silicone oil represented by the following formula (13) having a phenyl group content of 6 mol% (component for comparison) [ka]

[0085] (E) Adhesion aid: an organosilicon compound represented by the following formula (14): [ka]

[0086] (F) Reaction inhibitor: ethynylcyclohexanol

[0087] (G): Specific surface area is 300m by BET method 2 / g of silica fine powder (product name: Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.)

[0088] [Preparation Example 1] 60 parts by mass of base oil (A-1-1), 8 parts by mass of hexamethyldisilazane, 2 parts by mass of water, and 40 parts by mass of silica fine powder (G) were placed in a kneader and mixed at room temperature for 1 hour. The temperature was then raised to 150 ° C. and mixed for 2 hours. After this, 30 parts by mass of base oil (A-1-1) was added and mixed until uniform, to obtain a base compound.

[0089] Examples 1 to 3 and Comparative Examples 1 to 4 The base compound obtained in Preparation Example 1 above, the remaining components of (A) the base oil, (B) the crosslinking agent, (C) the platinum catalyst, (D) the bleed oil, (E) the adhesion promoter, and (F) the reaction inhibitor were mixed in a mixer at room temperature for 30 minutes in amounts corresponding to the compounding ratios shown in Table 1 below, to obtain an addition-curable silicone rubber composition. In Examples 1 to 3, the amount of ethynylcyclohexanol blended was such that 47 moles of acetylene were present per mole of platinum atom in the platinum catalyst (C). In Comparative Examples 1 to 4, the amount of ethynylcyclohexanol blended was such that 63 moles of acetylene were blended per mole of platinum atom in the platinum catalyst (C).

[0090] [Methods for evaluating various physical properties] Each of the compositions prepared above was press-cured at 150°C for 10 minutes to prepare a sheet measuring 130mm x 170mm x 2.0mm in accordance with JIS K 6249:2003. The density, hardness, tensile strength, and elongation at break of this sheet were measured in accordance with JIS K 6249:2003. The results are shown in Table 2.

[0091] Adhesion evaluation Two polyamide (PA) test pieces (approximately 20 x 50 mm) were prepared and overlapped with an area of ​​10 mm x 20 mm. Each of the addition-cure silicone rubber compositions obtained above was sandwiched between them and heat-cured at 150°C for 30 minutes (rubber thickness: 1-3 mm). Tensile tests were conducted on the integrated molded products to measure the cohesive failure rate and shear adhesive strength (MPa). The cohesive failure rate (i.e., rubber failure rate) was calculated as the ratio (%) of the area where the rubber failed (cohesive failure) without interfacial delamination to the total area of ​​the adhesive interface. These results are shown in Table 2. The adhesiveness was evaluated for two types of adherends: PA containing glass fiber and PA without glass fiber.

[0092] Oil bleeding evaluation Each of the compositions prepared above was press-cured at 150°C for 10 minutes to prepare a sheet measuring 130mm x 170mm x 2.0mm in accordance with JIS K 6249:2003. The surface of this sheet was evaluated by touching with a finger after 24 hours. A rating of ◯ was given to sheets where oil had bled and fingerprints remained, △ to sheets where there was little oil bleeding but fingerprints remained, and × to sheets where no oil bleeding was observed.

[0093] [Table 1]

[0094] [Table 2]

[0095] As shown in Table 1, the cured products of Comparative Examples 1 to 4 obtained from silicone rubber compositions in which the (A-2) or (D) component did not satisfy the ranges of the present invention exhibited poor self-adhesion of the silicone rubber and were unable to exhibit sufficient oil-bleeding properties. On the other hand, as shown in Table 1, the cured products obtained from the silicone rubber compositions of the present invention exhibited good oil-bleeding properties and were also able to exhibit sufficient self-adhesion. In particular, the cured products exhibited good adhesion to both glass fiber-containing polyamide and glass fiber-free polyamide. More specifically, as shown in Examples 1 to 3, the desired effect can be achieved by adding a phenyl group-containing organopolysiloxane to a highly self-adhesive silicone rubber composition and also adding (A-2) an organopolysiloxane having alkenyl groups bonded to silicon atoms and having 2 to 40 mol % of phenyl groups bonded to silicon atoms per molecule.

[0096] The silicone rubber composition of the present invention can provide an addition-cure silicone rubber composition that is capable of producing a silicone rubber that has excellent self-adhesion to various organic resins and oil-bleeding properties, as well as a cured silicone rubber obtained by curing the composition.

Claims

1. An addition-curable silicone rubber composition containing the following components (A) to (F): (A) 100 parts by mass of an organopolysiloxane consisting of the following components (A-1) and (A-2): (A-1) Organopolysiloxane having at least two alkenyl groups bonded to silicon atoms in each molecule and no aromatic hydrocarbon groups: 90 to 97 parts by mass (A-2) 3 to 10 parts by mass of an organopolysiloxane having, per molecule, at least two silicon-bonded alkenyl groups and at least one silicon-bonded aryl group having 6 to 10 carbon atoms or one silicon-bonded aralkyl group having 7 to 10 carbon atoms, wherein the ratio (%) of the number of aryl groups and aralkyl groups to the total number of silicon-bonded groups is 2 to 40%. (B-1) An organosilicon compound having 1 to 100 silicon atoms, which has at least one phenylene skeleton or phenyl group per molecule and at least one hydrogen atom bonded to a silicon atom per molecule: 0.05 to 10 parts by weight per 100 parts by weight of the component (A). (B-2) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule and no aromatic hydrocarbon groups: 0.2 to 30 parts by weight per 100 parts by weight of component (A); (C) Platinum group metal catalyst: catalyst amount (D) Silicone oil represented by the following general formula (1): 1 to 10 parts by mass per 100 parts by mass of the component (A) 【Chemistry 1】 (In formula (1), R １ are each independently an alkyl group having 1 to 10 carbon atoms, n is a number from 1 to 50, m is a number from 0 to 50, and p is a number from 1 to 50, the ratio (%) of the number of phenyl groups bonded to silicon atoms to the total number of alkyl groups and phenyl groups bonded to silicon atoms is 20% or more and 50% or less, and the siloxane units enclosed in parentheses in general formula (1) may be bonded randomly or may form a block structure. (E) an organic compound other than the components (A) and (B) above, which has at least one functional group selected from an alkenyl group, an alkoxysilyl group, and a hydrosilyl group in one molecule and at least one isocyanate group in one molecule: 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

2. 2. The addition-curable silicone rubber composition according to claim 1, wherein component (E) is an organosilicon compound represented by the following general formula (2): 【Chemistry 2】 (In the formula, R ２ are each independently an alkyl group having 1 to 3 carbon atoms, and k is an integer satisfying the condition 1≦k≦10.

3. The addition-curable silicone rubber composition according to claim 1, further comprising (F) at least one curing reaction inhibitor selected from the group consisting of acetylene alcohol compounds and compounds in which the alcoholic hydroxyl group of an acetylene alcohol compound has been modified with a silane or a siloxane, in an amount such that 1 to 500 moles of acetylene are present per mole of platinum group metal atom in component (C).

4. 2. The addition-curable silicone rubber composition according to claim 1, further comprising (G) a reinforcing filler in an amount of 5 to 100 parts by mass per 100 parts by mass of component (A).

5. The component (G) has a specific surface area of ​​50 m2 as measured by the BET method. ２ 5. The addition-curable silicone rubber composition according to claim 4, wherein the fumed silica has a viscosity of at least 1000 MPa.

6. A cured silicone rubber obtained by curing the addition-curable silicone rubber composition according to any one of claims 1 to 5.

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