JP7790890B2 - Addition-curable fluorosilicone composition, silicone rubber, and molded article - Google Patents

Description

The present invention relates to an addition-curable fluorosilicone composition that produces a cured product that exhibits good adhesion to metals and thermoplastic resins, a fluorosilicone rubber obtained by heat-curing the composition, and an integrally molded article consisting of a layer of the fluorosilicone rubber and a layer of metal or thermoplastic resin.

Traditionally, liquid addition-curable fluorosilicone rubber compositions have been used in aircraft and automotive rubber parts, printer parts, and other applications due to their excellent gasoline and oil resistance (Patent Document 1). In recent years, they have also been used in mobile phone parts due to their sebum resistance. Liquid addition-curable fluorosilicone rubber compositions used in these parts are expected to be able to adhere to metals and thermoplastic resins. One method for achieving this is insert molding, in which molded metal or thermoplastic resin is placed in a mold, liquid fluorosilicone rubber is injected into the mold, and the resulting material is heated and cured for adhesion (Patent Document 2). However, its adhesive properties have not been clarified. Furthermore, there have been no examples of molded articles made by molding, curing, and adhering liquid addition-curable fluorosilicone rubber adhesive compositions using mold-based casting, compression molding, or injection molding processes.

JP 2013-047290 A JP 2013-194113 A

The present invention has been developed in light of the above circumstances, and aims to provide an addition-cure fluorosilicone composition that is liquid at 23°C and produces a cured product that adheres well to metals and thermoplastic resins, as well as a fluorosilicone rubber obtained by heat-curing the composition. A further aim of the present invention is to provide an integrally molded article in which a layer of the fluorosilicone rubber is bonded to a layer of metal or thermoplastic resin.

The fluorosilicone composition targeted by this invention contains a linear polysiloxane with a main chain consisting of repeating diorganosiloxane units containing fluoroalkyl groups as the main component that forms the silicone rubber matrix after curing. On the other hand, typical dimethylsilicone compositions use a linear dimethylpolysiloxane as the main component, whose main chain is composed of repeating dimethylsiloxane units. In this respect, the fluorosilicone composition targeted by this invention is fundamentally different from a dimethylsilicone composition.

As a result of extensive research to achieve the above-mentioned objective, the inventors discovered that an addition-curable fluorosilicone composition containing an isocyanuric acid derivative having three trialkoxysilyl groups per molecule as an adhesion-imparting component produces a cured product that adheres well to metals and thermoplastic resins. Furthermore, they discovered that this addition-curable fluorosilicone composition is suitable as a material for casting, compression molding, and injection molding, leading to the completion of the present invention.

That is, the present invention provides: (A) a compound represented by the following general formula (1):
(wherein R ¹ , R ⁴ , and R ⁵ are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; x is an integer from 1 to 10; m is an integer from 0 to 100; and n is an integer from 1 to 800, with the proviso that 5≦m+n≦800.)
(B) an organohydrogenpolysiloxane having a viscosity at 25°C of 100 to 500,000 mPa s, represented by the formula:
(C) addition reaction catalyst: catalytic amount,
(D) A reinforcing silica filler surface-treated with an organosilicon compound represented by the following general formula (2):
(In the above formula (2), ^R3 's are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; ^R2 's are the group represented by ^R3 above or a 3,3,3-trifluoropropyl group; and p is an integer satisfying the range of 1 to 20.)
10 to 60 parts by mass per 100 parts by mass of component (A), and (E) an isocyanuric acid derivative having three trialkoxysilyl groups per molecule
The present invention provides an addition-curable fluorosilicone composition containing 0.1 to 5 parts by mass of component (A) per 100 parts by mass of component (A).
The present invention preferably provides the above addition-curable fluorosilicone composition in a liquid form.
The present invention also provides a fluorosilicone rubber that is a cured product of the addition-curable fluorosilicone composition, a molded article of the silicone rubber, and a molded article having a layer of the silicone rubber and a layer of a metal or thermoplastic resin.

The addition-curable fluorosilicone composition of the present invention produces a self-adhesive fluorosilicone rubber that adheres well to metals and thermoplastic resins. Heat-curing the composition provides an integrally molded article in which the fluorosilicone rubber layer is bonded to a metal layer or a thermoplastic resin layer, contributing to improved productivity in adhesive molding and molded products.

The present invention is described in more detail below.

(A) Vinyl Group-Containing Organopolysiloxane Component (A) is an organopolysiloxane represented by the following general formula (1) and having a viscosity at 25°C of 100 to 500,000 mPa·s.
(wherein R ¹ , R ⁴ , and R ⁵ are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; x is an integer from 1 to 10; m is an integer from 0 to 100; and n is an integer from 1 to 800, with the proviso that 5≦m+n≦800.)

In the above formula (1), R ¹ , R ⁴ , and R ⁵ are each independently a group selected from alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, and cyclohexyl, aryl groups having 6 to 12 carbon atoms, such as phenyl and tolyl, and aralkyl groups having 7 to 12 carbon atoms, such as benzyl. ^{R 1} , R ⁴ , and R ⁵ are each preferably alkyl groups having 1 to 8 carbon atoms, and particularly preferably methyl groups.

m is an integer between 0 and 100, preferably between 0 and 50, more preferably between 0 or 1 and 30, even more preferably between 0 or 1 and 20, and most preferably between 0 or 1 and 10. n is an integer between 1 and 800, preferably between 5 and 750, more preferably between 10 and 650, even more preferably between 50 and 650, and most preferably between 100 and 650. However, (m+n) is an integer in the range 5≦m+n≦800, preferably 10≦m+n≦680, more preferably 60≦m+n≦680, and even more preferably 120≦m+n≦680. x is an integer between 1 and 10, preferably between 1 and 3, and most preferably x=1.

The viscosity of component (A) at 25°C is in the range of 100 to 500,000 mPa·s, preferably 300 to 100,000 mPa·s, because this ensures good physical properties for the cured product and good handling and workability of the composition. If the viscosity at 25°C is less than 100 mPa·s, the strength of the resulting cured product will be insufficient. If it exceeds 500,000 mPa·s, the handleability of the composition will decrease. In the present invention, viscosity is the value measured using a rotational viscometer using the method described in JIS K 7117-1:1999. The degree of polymerization of organopolysiloxane (A) is in the range that results in a viscosity at 25°C of 100 to 500,000 mPa·s.

The number of fluoroalkyl group-containing siloxane units (i.e., the value of n) is preferably 10% or more, more preferably 20 % or more, and particularly preferably 30 to 100% of all siloxane units in the molecule (particularly the sum of the difunctional siloxane units constituting the main chain (i.e., n+m)). The upper limit is not particularly limited as long as it is 100% or less, and may be 95% or less, 90% or less, or 80 % or less. This range is preferable because it allows for excellent durability against hydrocarbon solvents.

Component (B) is an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms per molecule. This organohydrogenpolysiloxane undergoes a hydrosilylation addition reaction with component (A) and acts as a curing agent (crosslinking agent). There are no particular restrictions on the molecular structure of component (B), and various conventionally produced organohydrogenpolysiloxanes can be used, including linear, cyclic, branched, and three-dimensional network structures (resinous).

The organohydrogenpolysiloxane of component (B) has two or more (typically 2 to 200), preferably 3 to 100, and particularly preferably 3 to 50, silicon-bonded hydrogen atoms (i.e., hydrosilyl groups represented by SiH) per molecule. When the organohydrogenpolysiloxane of component (B) has a linear or branched structure, these SiH groups may be located either at the molecular chain terminals (i.e., diorganohydrogensiloxy groups) or in the middle of the molecular chain (i.e., difunctional organohydrogensiloxane units or trifunctional hydrogensilsesquioxane units located at non-terminal positions), or may be located at both locations.

Examples of monovalent organic groups bonded to silicon atoms other than silicon-bonded hydrogen atoms include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, that do not contain aliphatic unsaturated bonds, such as vinyl groups. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms such as fluorine, bromine, or chlorine, such as fluoroalkyl groups such as trifluoropropyl. Preferred are fluoroalkyl groups such as methyl and trifluoropropyl. The number of silicon atoms (or degree of polymerization) per molecule of component (B) is preferably 2 to 300, more preferably 3 to 200, and even more preferably 4 to 150.

Component (B) should be liquid at room temperature (25°C). The viscosity of component (B) at 25°C is preferably 0.1 to 1,000 mPa·s, more preferably 0.5 to 500 mPa·s, and even more preferably 1 to 200 mPa·s. If the viscosity of component (B) is too low or too high, the workability of the composition may be reduced.

(B) Examples of organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy)methylsilane, tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymers, methylhydrogenpolysiloxanes capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both ends with trimethylsiloxy groups, methylhydrogensiloxane-trifluoropropylmethylsiloxane copolymers capped at both ends with trimethylsiloxy groups, dimethylpolysiloxanes capped at both ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both ends with dimethylhydrogensiloxy groups, copolymer of methylhydrogensiloxane and trifluoropropylmethylsiloxane, trifluoropropylmethylpolysiloxane capped at both ends with dimethylhydrogensiloxy groups, copolymer of dimethylsiloxane and methylhydrogensiloxane capped at both ends with dimethylhydrogensiloxy groups, copolymer of methylhydrogensiloxane and diphenylsiloxane capped at both ends with trimethylsiloxy groups, copolymer of methylhydrogensiloxane, diphenylsiloxane and dimethylsiloxane capped at both ends with trimethylsiloxy groups, copolymer of methylhydrogensiloxane, methylphenylsiloxane and dimethylsiloxane capped at both ends with trimethylsiloxy groups, copolymer of methylhydrogensiloxane, dimethylsiloxane and diphenylsiloxane capped at both ends with dimethylhydrogensiloxy groups, copolymer of methylhydrogensiloxane, dimethylsiloxane and methylphenylsiloxane capped at both ends with dimethylhydrogensiloxy groups, (CH Examples include a copolymer consisting of ( _CH3 )2HSiO1 _{/2 units} , ( _CH3 ) _{3SiO1 /2} units, and SiO4 _{/2 units} , a copolymer consisting of ( _CH3 )2HSiO1 _/2 units and SiO4 _/2 units, a copolymer consisting of _{( CH3} )2HSiO1 _/2 units, SiO4 _/2 units, and ( _C6H5 )SiO3 _{/2 units} , and the above-exemplified compounds in which some or all of the methyl groups have been substituted with other alkyl groups, phenyl groups, trifluoropropyl groups, etc. One type of organohydrogenpolysiloxane may be used alone, or two or more types may be used in combination.

The component (B) is more preferably represented by the following formula (6).
In formula (6), R ^1' are each independently a group selected from a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, including the groups exemplified for R ¹ above. However, at least two of R ^1' , preferably 3 to 100, and more preferably 3 to 50, are hydrogen atoms. x' is an integer of 1 to 10, preferably 1 to 3, and most preferably x'=1. k is an integer of 2 to 200, preferably an integer of 3 to 100, and more preferably an integer of 5 to 50. q is an integer of 0 to 200, preferably an integer of 1 to 100, and more preferably an integer of 2 to 100. k+q is 2 to 300, more preferably 3 to 200, and even more preferably 4 to 150.

The amount of component (B) is such that the ratio of silicon-bonded hydrogen atoms in component (B) to one silicon-bonded vinyl group in component (A) is within the range of 0.5 to 10, preferably 1 to 5. If the amount of component (B) is less than the above lower limit, the resulting composition will not cure sufficiently. If the amount of component (B) exceeds the above upper limit, the heat resistance of the resulting silicone rubber will be extremely poor. Furthermore, when a vinyl-containing organosiloxane other than component (A), as described below, is included, it is sufficient that the ratio of the number of silicon-bonded hydrogen atoms in component (B) to the number of silicon-bonded vinyl groups in the composition satisfies the above range.

(C) Addition Reaction Catalyst: Component (C) is an addition reaction catalyst. Component (C) may be any catalyst that promotes the addition reaction between the vinyl group in component (A) and the hydrogen atom bonded to the silicon atom in component (B). Typically, platinum group metal catalysts are suitable. Examples include platinum, palladium, rhodium, etc., platinum group metals, or compounds thereof, such as chloroplatinic acid, alcohol-modified chloroplatinic acid, coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds, tetrakis(triphenylphosphine)palladium, and chlorotris(triphenylphosphine)rhodium, with platinum compounds being particularly preferred. Component (C) may be used alone or in combination of two or more.

The amount of component (C) that can be blended may be an effective catalytic amount, but is typically 0.5 to 1,000 ppm, preferably 1 to 500 ppm, and more preferably 10 to 100 ppm, by mass, converted into catalytic metal element (platinum group metal element) relative to the total amount of components (A) and (B). Meeting this range ensures an appropriate reaction rate for the addition reaction, and the cured product has good heat resistance.

(D) Reinforcing Silica Filler Component (D) is a reinforcing silica that has been surface-treated with a linear organosilicon compound having silanol groups at both molecular chain terminals, represented by the following formula (2).
In the above formula (2), ^R3 's are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, and examples thereof include those described above for ^R1 . A methyl group is preferred. ^R2 's are the groups represented by ^R3 above, or a 3,3,3-trifluoropropyl group. Preferably, ^R2 's are a methyl group or a 3,3,3-trifluoropropyl group, and at least one R2 ^'s is a 3,3,3-trifluoropropyl group. p's an integer from 1 to 20, and preferably an integer from 3 to 9.
In the present invention, the reinforcing silica filler is essential for imparting sufficient strength to the resulting silicone rubber.

By including the reinforcing silica filler, which has been surface-treated with a linear organosilicon compound whose molecular chain ends are blocked with silanol groups, the viscosity of the composition and the tackiness of the molded rubber article can be reduced.

The reinforcing silica filler can be any of those conventionally used in silicone rubber compositions, with precipitated silica (wet silica), fumed silica (dry silica), and pyrogenic silica being preferred. Fumed silica is particularly preferred.

Component (D) may be untreated silica that has been surface-treated in advance with the organosilicon compound of formula (2). Alternatively, untreated silica may be kneaded with the polysiloxane component of the present invention (i.e., component (A)), and the organosilicon compound of formula (2) may be added. The mixture may be heated and mixed, preferably in the presence of a small amount of water, to perform surface treatment within the mixture. Furthermore, the silica that is surface-treated with the organosilicon compound of formula (2) in the present invention may be dry silica (e.g., Aerosil R-974) that has been surface-treated in advance with dimethyldichlorosilane or the like. It is preferable to further treat the surface of the dry silica that has been surface-treated with dimethyldichlorosilane or the like with the organosilicon compound of formula (2) in this way.

When silica is surface-treated with the organosilicon compound of formula (2), the treatment amount is preferably 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass, of the organosilicon compound per 40 parts by mass of silica prior to surface treatment with the organosilicon compound of formula (2).

The specific surface area of the silica, measured by the BET method, before surface treatment with the organosilicon compound of formula (2) is 50 m ² /g or more, preferably 100 to 400 m ² /g, and more preferably 150 to 350 m ² /g. If the specific surface area is less than 50 m ² /g, not only will sufficient strength not be obtained, but the appearance of the rubber molded product may also be poor. If it is greater than ^{400 m 2} /g, compounding may become difficult. The specific surface area of the silica after surface treatment, measured by the BET method, may also be within the above range.

The amount of component (D) blended is 10 to 60 parts by mass, preferably 15 to 55 parts by mass, per 100 parts by mass of component (A). If the blending amount is less than the above lower limit, the resulting silicone rubber will not have sufficient rubber strength, and if the blending amount exceeds the above upper limit, it will be difficult to blend into the composition.

(E) Adhesion Promoter : Component (E) is an isocyanuric acid derivative having three trialkoxy groups per molecule. Component (E) is an adhesion promoter. By incorporating component (E), the cured product obtained from the addition-curable fluorosilicone composition of the present invention can possess self-adhesive properties. More specifically, component (E) of the present invention is an isocyanuric acid derivative having three trialkoxysilyl groups per molecule, such as trimethoxysilyl and triethoxysilyl groups. More preferably, it is an isocyanuric acid derivative having three trialkoxysilyl-substituted alkyl groups. Examples of alkyl groups, such as the trimethoxysilyl-substituted alkyl groups, include those having 2 to 10 carbon atoms, such as ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, and octyl groups. Among these, propyl is preferred. By incorporating component (E), the resulting composition can possess excellent adhesion to metals and thermoplastic resins.

The component (E) is preferably an isocyanuric acid derivative represented by the following formula (3) and having three trialkoxysilyl-substituted propyl groups in one molecule.
( ^R6 's are each independently an alkyl group having 1 to 3 carbon atoms.)
The trialkoxy group may be a trimethoxysilyl group or a triethoxysilyl group.

The amount of component (E) blended is in the range of 0.1 to 5 parts by mass, preferably 0.2 to 3.5 parts by mass, and more preferably 0.3 to 3.0 parts by mass, per 100 parts by mass of component (A). If the amount of component (E) blended is less than the above lower limit, the resulting cured product will not have good adhesion to metals or thermoplastic resins. Furthermore, if the amount exceeds the above upper limit, the heat resistance of the cured product may be significantly reduced.

The addition-curable fluorosilicone composition of the present invention may optionally contain other components in addition to the components (A) through (E) described above, provided that the components do not impair the appearance of the molded rubber article. Examples of such components include conductive agents such as carbon black, conductive zinc oxide, and metal powder; hydrosilylation reaction inhibitors such as nitrogen-containing compounds, acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates, tin compounds, mercury compounds, and sulfur compounds; heat resistance agents such as iron oxide and cerium oxide; compression set improvers such as triazole compounds and benzotriazole derivatives; internal release agents such as dimethyl silicone oil; adhesion promoters other than component (E); and thixotropy-imparting agents.

Also, for example, the composition may contain a dimethylpolysiloxane other than component (A) that contains vinyl groups at both ends and does not have a fluoroalkyl group. More specifically, it is an organopolysiloxane containing vinyl groups at both ends that is liquid at room temperature and has an average degree of polymerization of 1,500 or less. The average degree of polymerization is preferably 1,500 or less, typically 100 to 1,500, and preferably 150 to 1,100. Furthermore, the viscosity at 25°C measured with a rotational viscometer as described in JIS K 6249:2003 is preferably 1,000 to 100,000 mPa·s, and preferably 5,000 to 100,000 mPa·s. The amount of dimethylpolysiloxane blended is 1 to 20 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of component (A).

The composition of the present invention can also contain a vinyl group-containing MQ resin. More specifically, the MQ resin has a vinyl group content of 0.01 to 5 mmol/g, preferably 0.1 to 1 mmol/g. The molar ratio of M units to Q units (M units/Q units) is preferably 0.5 to 1.5, more preferably 0.7 to 1.2. The vinyl group-containing MQ resin preferably has a weight-average molecular weight of 2,000 to 8,000, particularly 4,000 to 6,000, as measured by gel permeation chromatography (GPC) using polystyrene as the standard, and is typically solid at room temperature. The amount of MQ resin blended is 1 to 20 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of component (A).

The addition-curable fluorosilicone composition of the present invention can be prepared by uniformly mixing the above components (A) through (E), and, if necessary, each optional component, using a conventional mixer/stirrer or kneader such as a kneader or planetary mixer.

The composition of the present invention is preferably liquid at 23°C. From the viewpoint of workability and the like, the viscosity at 23°C at a shear rate of 0.9 s ^-1 is preferably 8,000 Pa·s or less, more preferably 100 to 7,000 Pa·s, even more preferably 500 to 6,500 Pa·s, particularly preferably 1,600 to 6,000 Pa·s, and particularly preferably 2,000 to 6,000 Pa·s. If the viscosity exceeds 8,000 Pa·s, material supply during injection, compression, and injection molding may take a long time, resulting in a significant decrease in productivity. In the present invention, the viscosity at the above shear rates was measured using a precision rotational viscometer (manufactured by Thermo Fisher Scientific).

The addition-curable fluorosilicone composition of the present invention can also be prepared as a two-part composition. In this case, the components (B) acting as a crosslinking agent and (C) acting as an addition reaction catalyst can be appropriately divided so that they are not mixed in the same composition (Part A or Part B). For example, a two-part composition can be prepared consisting of Part A containing Parts (A), (C), and (D), and Part B containing Parts (A), (B), (D), and (E), and it is preferable to prepare the two parts so that they can be mixed in equal amounts by mass or volume.

The addition-curable fluorosilicone composition of the present invention can be applied to various molding methods such as cast molding, compression molding, and injection molding, and is suitable for use in adhesive molding because it adheres to metals and certain thermoplastic resins. The present invention also provides a molded article, preferably an integrally molded article, having a layer made of fluorosilicone rubber, which is a cured product of the addition-curable fluorosilicone composition, and a layer made of metal or thermoplastic resin. Below, we will explain in detail the methods for molding fluorosilicone rubber by cast molding, compression molding, or injection molding. In the present invention, an integrally molded article is one in which, for example, resin parts or metal parts are inserted into a mold and filled with silicone rubber, resulting in a strong adhesion and integration.

In the case of injection molding, the addition-cure fluorosilicone composition is divided into two parts, Part A and Part B. The two parts are mixed in equal amounts and poured into a metal mold. It is then heated and cured in a thermostatic chamber to form silicone rubber. In the case of compression molding, a metal mold is placed in a compressor such as a press, and equal amounts of Part A and Part B are mixed, just as in injection molding. The mixture is then poured into the mold and heated to harden, forming silicone rubber. In the case of injection molding, Part A and Part B are supplied from the material supply pump to a metering machine. Equal amounts of Part A and Part B then join through the material supply line. The material is mixed in the screw and cylinder sections of the molding machine. The mixture is then injected into the mold, where it is heated and cured to form silicone rubber.

The curing conditions for addition-curable fluorosilicone compositions can be the same as those for known liquid addition-curable silicone compositions. For example, the curing temperature is 80 to 200°C, particularly 100 to 180°C, and the composition can be cured and molded by heating for 3 to 60 minutes, particularly 5 to 30 minutes.

The fluorosilicone rubber molded articles obtained by heat curing the addition-curable fluorosilicone composition of the present invention have excellent gasoline and oil resistance, making them suitable for use in aircraft and automotive rubber parts, printer parts, and more recently, mobile parts due to their sebum resistance.

The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

The viscosity of component (A) was measured at 25°C using a BH-type rotational viscometer (rotor No. 7, rotation speed 10 rpm). The viscosity of component (B) was measured at 25°C using a BL-type rotational viscometer (rotor No. 2, rotation speed 60 rpm).

The viscosity of the composition was measured by the following method.
The viscosity of the composition was measured at 23° C. and a shear rate of 0.9 s ⁻¹ using a cone and plate measuring jig of a precision rotational viscometer (manufactured by Thermo Fisher Scientific).

The hardness, tensile strength, elongation at break, and tear strength (angle) of the cured product were measured by the following methods.
The composition was subjected to primary vulcanization by press curing at 150° C. for 10 minutes. The hardness, tensile strength, elongation at break, and tear strength (angle) of the cured product were measured in accordance with JIS K 6249:2003.

The shear adhesive strength of the cured product to various substrates was measured by the following method.
(1) A composition was filled between two flat stainless steel (SUS) plates measuring 25 mm in width, 100 mm in length, and 0.3 mm in thickness, and the composition was cured by heating in a constant temperature bath at 120°C for 30 minutes to prepare a test specimen having a rubber layer with a bonding area of 25 mm x 10 mm and a rubber layer thickness of 2 mm.
(2) The composition was filled between two flat aluminum (Al) plates measuring 25 mm in width, 100 mm in length, and 1 mm in thickness, and then heated and cured in a constant temperature bath at 120°C for 30 minutes to prepare a test piece having a rubber layer with an adhesive area of 25 mm x 10 mm and a rubber layer thickness of 2 mm.
(3) The composition was filled between two flat polyamide 6 resin (PA6 resin) plates measuring 25 mm in width, 100 mm in length, and 2 mm in thickness, and the composition was cured by heating in a constant temperature bath at 120°C for 30 minutes to prepare a test piece having a rubber layer with an adhesive area of 25 mm x 10 mm and a rubber layer thickness of 2 mm.
For each of the test pieces, a tensile stress was applied in the horizontal direction to the bonded surface to measure the shear bond strength.

The components used in the following examples and comparative examples are as follows: Component (A): a compound represented by the following formula (1)
Trifluoropropylmethylpolysiloxane (vinyl group content: 4.5×10 ⁻⁵ mol/g) having a viscosity of 80.8 Pa·s at 25° C. and both ends capped with dimethylvinylsiloxy groups.
Component (D): fumed silica having a specific surface area of 200 m ² /g as measured by the BET method (Aerosil R-974, manufactured by Nippon Aerosil Co., Ltd.);
A silanol compound represented by the following formula (2):
(B) Crosslinking agent: Methylhydrogenpolysiloxane represented by the following formula (3) (viscosity: 0.06 Pa·s, SiH group content: 0.0047 mol/g)
(C) Platinum catalyst (Pt concentration 0.5% by mass)
(E) Adhesion promoter: a compound represented by the following formula (5):
(F) A dimethylpolysiloxane capped at both ends with dimethylvinylsiloxy groups, having a viscosity of about 5 Pa s at 25°C and an average degree of polymerization of about 448 (number of vinyl groups per molecule: 2, vinyl group content: 0.060 mmol/g).
(G) A copolymer consisting of ( _CH3 ) _{3SiO1 /2} (M) units, ( _CH2 =CH)( _CH3 ) _{2SiO1/2 (} M) units, and SiO4 _/2 (Q) units (number of vinyl groups per molecule: 4.0, vinyl group content: 0.84 mmol/g, molar ratio of M units to Q units per molecule (M units/Q units): 0.85).
Reaction inhibitor: ethynylcyclohexanol Compression set improver: benzotriazole silane represented by the following formula (4)
Heat resistance agent: cerium oxide

[Example 1]
(A) 55 parts by mass of trifluoropropylmethylpolysiloxane represented by the above formula (1) (vinyl group content 4.5× ¹⁰ mol/g), 40 parts by mass of the above fumed silica, 6.6 parts by mass of the silanol compound represented by the above formula (2), 0.55 parts by mass of water, and 0.3 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisilazane were mixed at room temperature for 30 minutes, and then the temperature was raised to 160° C. and stirring was continued for 3 hours. Further, 65 parts by mass of trifluoropropylmethylpolysiloxane represented by the above formula (1) was added, and after mixing for 30 minutes, a silicone rubber base was obtained.
320 parts by mass of the silicone rubber base, 17 parts by mass of the trifluoropropylmethylpolysiloxane represented by the formula (1) above (note that the amount of component (D) per 100 parts by mass of component (A) was 31.1 parts by mass), 2.5 parts by mass of the (F) dimethylpolysiloxane capped at both ends with dimethylvinylsiloxy groups, 2.5 parts by mass of the (G) copolymer comprising MQ units, and 8.3 parts by mass of (B) methylhydrogenpolysiloxane represented by the formula (3) above (the ratio of the number of SiH groups in component (B) to the number of silicon-bonded vinyl groups in the blending components [SiH/SiVi] was 2.3, and the ratio of the number of SiH groups in component (B) to SiVi of component (A) [SiH/SiVi] was 3.6), 0.08 parts by mass of the reaction inhibitor, (C) platinum catalyst (Pt concentration Addition-curable fluorosilicone composition 1, which is liquid at 23°C, was prepared by appropriately mixing 0.4 parts by mass of a hydroxybenzoate (0.5 mass%), 0.015 parts by mass of the compression set improver described above, 0.57 parts by mass of the heat resistance imparting agent described above, and 1.7 parts by mass of the compound (E) represented by formula (5) described above (an amount such that the amount of component (E) was 0.66 parts by mass per 100 parts by mass of component (A)).
The viscosity of the resulting addition-curable fluorosilicone composition 1 was measured using the method described above. The composition was then cured using the same method, and the hardness, tensile strength, elongation at break, tear strength (angle), and shear adhesive strength to various substrates were measured. The results are shown in Table 1.

[Example 2]
Addition-curable fluorosilicone composition 2, which was liquid at 23°C, was prepared by repeating Example 1, except that the amount of the adhesion promoter (E) was changed to 3.4 parts by mass ( an amount such that the amount of component (E) was 1.32 parts by mass per 100 parts by mass of component A).
The viscosity of the resulting addition-curable fluorosilicone composition 2 was measured using the method described above. The composition was then cured using the method described above, and the hardness, tensile strength, elongation at break, tear strength (angle), and shear adhesive strength to various substrates were measured. The results are shown in Table 1.

[Comparative Example 1]
Addition-curable fluorosilicone composition 3, which is liquid at 23°C, was prepared by repeating Example 1, except that the adhesion promoter (E) was not added.
The viscosity of the resulting addition-curable fluorosilicone composition 3 was measured using the method described above. The composition was then cured using the method described above, and the hardness, tensile strength, elongation at break, tear strength (angle), and shear adhesive strength to various substrates were measured. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, when the adhesion promoter (E) was blended in an amount of more than 5 parts by mass per 100 parts by mass of component (A), the resulting composition had a high viscosity and was poor in handleability.

As shown in Table 1 above, the silicone composition of the present invention, due to the inclusion of component (E), exhibits excellent adhesion to aluminum plates, stainless steel plates, and polyamide resins.
Thus, the addition-curable fluorosilicone composition of the present invention provides a self-adhesive fluorosilicone rubber that adheres well to metals and thermoplastics.

Claims (9)

(A) Represented by the following general formula (1):

In the formula, R ¹ , R ⁴ , and R ⁵ are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, x is an integer from 1 to 10, m is an integer from 0 to 100, and n is an integer from 50 to 800, with the proviso that m and n are integers that satisfy both of the following two conditions α and β:
Condition α: 120≦m+n≦800
Condition β: the number of fluoroalkyl group-containing siloxane units (n) is 30 to 100 % of the total number of bifunctional siloxane units (n+m) constituting the main chain;
an organopolysiloxane (B) having a viscosity at 25°C of 100 to 500,000 mPa s; and an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule, in an amount such that the ratio of the number of silicon-bonded hydrogen atoms in component (B) per silicon-bonded vinyl group in component (A) is 0.5 to 10.
(C) addition reaction catalyst: catalytic amount,
(D) A reinforcing silica filler surface-treated with an organosilicon compound represented by the following general formula (2):
(In the above formula (2), ^R3 's are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; ^R2 's are the group represented by ^R3 above or a 3,3,3-trifluoropropyl group; and p is an integer satisfying the range of 1 to 20.)
10 to 60 parts by mass per 100 parts by mass of component (A), and (E) an isocyanuric acid derivative having three trialkoxysilyl groups per molecule
An addition-curable fluorosilicone composition comprising 0.1 to 5 parts by mass of component (A) per 100 parts by mass of component (A). The addition-curable fluorosilicone composition of claim 1, wherein component (E) is represented by the following formula (3):
( ^R5 's are each independently an alkyl group having 1 to 3 carbon atoms). 3. The addition-curable fluorosilicone composition according to claim 1, wherein in component (D), ^R2 is a methyl group or a 3,3,3-trifluoropropyl group. 3. The addition-curable fluorosilicone composition according to claim 1 , wherein in component (D), at least one of ^R2 is a 3,3,3-trifluoropropyl group. The addition-curable fluorosilicone composition according to any one of claims 1 to 4, wherein x is 1 in formula (1). The addition-curable fluorosilicone composition according to any one of claims 1 to 5, which is liquid at 23°C. The addition-curable fluorosilicone composition according to any one of claims 1 to 6, which is suitable for casting, compression molding, or injection molding. A fluorosilicone rubber that is a cured product of the addition-curable fluorosilicone composition described in any one of claims 1 to 6. A molded article having a layer made of the fluorosilicone rubber according to claim 8 and a layer made of a metal or a thermoplastic resin.