Heat-resistant silicone gel-forming composition and use of same

Abstract

The present invention provides: a novel silicone gel-forming composition which has excellent heat resistance; and the like.　Disclosed is a silicone gel-forming composition which contains the following components (A)-(E): (A) an organopolysiloxane that has two or more alkenyl groups on average in each molecule, the alkenyl groups being each bonded to a silicon atom; (B) an organohydrogenpolysiloxane that has two or more hydrogen atoms which are each bonded to a silicon atom in each molecule; (C) an organosiloxane compound that has one hydrogen atom which is bonded to a silicon atom in each molecule (excluding a compound that has an alkoxysilyl group); (D) a hydrosilylation reaction catalyst; and (E) a heat-resistant additive. With respect to this silicone gel-forming composition, the molar ratio of the silicon atom-bonded hydrogen atoms in the components (B) and (C) to the alkenyl groups in the component (A) is 0.80 or more.

Description

Heat-resistant silicone gel-forming composition and its uses

[0001] The present invention relates to a heat-resistant silicone gel-forming composition, an electronic component sealant containing the composition, a silicone gel obtained by curing the composition or the electronic component sealant, an electronic component containing the silicone gel, and a method for producing the electronic component.

[0002] As one type of curable organopolysiloxane composition, a composition capable of forming a silicone gel upon curing (silicone gel-forming composition) is known. Such silicone gel-forming compositions are widely used as encapsulants or sealants for electrical and electronic devices (e.g., Patent Documents 1 to 3). The silicone gel obtained from the silicone gel-forming composition is required to have heat resistance so that the gel can be stably maintained even when exposed to high temperatures, for example, exceeding 210°C, due to the usage environment and characteristics of the electrical and electronic devices to which it is applied.

[0003] Patent Publication No. 2022-545162 International Publication No. 2022 / 013917 Pamphlet International Publication No. 2015 / 034029 Pamphlet

[0004] The present invention provides a novel silicone gel-forming composition that has excellent heat resistance.

[0005] The present invention provides the following silicone gel-forming compositions, etc. [1] A silicone gel-forming composition comprising the following components (A) to (E): (A) an organopolysiloxane having, on average, two or more silicon-bonded alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule, (C) an organosiloxane compound having one silicon-bonded hydrogen atom per molecule (excluding compounds having an alkoxysilyl group), (D) a hydrosilylation reaction catalyst, and (E) a heat-resistant additive, wherein the molar ratio of silicon-bonded hydrogen atoms in components (B) and (C) to alkenyl groups in component (A) is 0.80 or greater. [2] The silicone gel-forming composition according to [1], wherein the molar ratio of silicon-bonded hydrogen atoms in component (B) to alkenyl groups in component (A) is 0.10 or greater. [3] The silicone gel-forming composition according to [1] or [2], wherein component (C) comprises one or more compounds selected from the group consisting of compounds represented by the following general formulas (1) to (7): (In formula (1), R １ ~R ５ are each independently the same or different monovalent hydrocarbon groups containing 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. (In formula (2), R １ ~R ３ , R ５ ~R ７ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ４ is a group selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. (In formula (3), R １ ~R ２ , R ５ ~R ７ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ３ ~R ４are each independently the same or different groups selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. (In formula (4), R １ ~R ３ , R ７ ~R ９ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ４ ~R ６ are each independently the same or different groups selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. (In formula (5), R １ ~R ２ , R ７ ~R ９ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ３ ~R ６ are each independently the same or different groups selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. (In formula (6), R １ ~R ２ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ３ are groups selected from the group consisting of identical or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups, and a is an integer of 2 to 5. (In formula (7), each R is independently the same or different monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds.) [4] The silicone gel-forming composition according to any one of [1] to [3], wherein component (A) has a viscosity of 10 to 10,000 mPa·s at 25°C, and component (B) has a viscosity of 2 to 1,000 mPa·s at 25°C. [5] The silicone gel-forming composition according to any one of [1] to [4], wherein component (A) is one or more members selected from the group consisting of linear organopolysiloxanes, branched organopolysiloxanes, and mixtures thereof. [6] The silicone gel-forming composition according to any one of [1] to [5], wherein the content of component (D) is 0.01 to 1,000 ppm by mass, based on the total amount of the silicone gel-forming composition. [7] The silicone gel-forming composition according to any one of [1] to [6], wherein component (E) comprises one or more metals selected from the group consisting of metal silanolates and metal carboxylates. [8] The silicone gel-forming composition according to [7], wherein the metal is selected from the group consisting of cerium, iron, manganese, vanadium, magnesium, aluminum, nickel, titanium, and zinc. [9] The silicone gel-forming composition according to any one of [1] to [8], wherein the composition is substantially transparent.

[10] The silicone gel-forming composition according to any one of [1] to [9], wherein the composition is used for sealing electronic components.

[11] The silicone gel-forming composition according to

[10] , wherein the electronic component is a power device.

[12] An electronic component sealant comprising the silicone gel-forming composition according to any one of [1] to

[11] .

[13] The electronic component sealant according to

[12] , wherein the composition is substantially transparent.

[14] A silicone gel obtained by curing the silicone gel-forming composition according to any one of [1] to

[11] or the electronic component sealant according to

[12] or

[13] .

[15] The silicone gel according to

[14] , which has a 1 / 4 cone penetration value as specified in JIS K2210 of 10 to 150.

[16] An electronic component comprising the silicone gel according to

[14] or

[15] .

[17] A method for producing an electronic component, comprising using the silicone gel-forming composition according to any one of [1] to

[11] or the electronic component sealant according to

[12] or

[13] .

[0006] According to one aspect of the present invention, there is provided a silicone gel-forming composition having excellent heat resistance. According to a preferred aspect of the present invention, there is provided a silicone gel-forming composition that can provide a silicone gel with little change in the degree of cure even after exposure to a high-temperature environment for an extended period of time (e.g., 2000 hours).

[0007] The upper and lower limit values ​​of the numerical ranges described herein can be arbitrarily combined. For example, when a numerical range is described as "preferably 30 to 100, more preferably 40 to 80," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. Furthermore, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. In addition, when a numerical range described herein as "60 to 100," for example, means a range of "60 or more and 100 or less."

[0008] 1. Silicone Gel-Forming Composition One aspect of the present invention provides a silicone gel-forming composition (hereinafter also referred to as the "composition of the present invention"). The composition of the present invention comprises (A) an organopolysiloxane having an average of two or more silicon-bonded alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule, (C) an organosiloxane compound (excluding compounds having an alkoxysilyl group) having one silicon-bonded hydrogen atom per molecule, (D) a hydrosilylation reaction catalyst, and (E) a heat-resistant additive, wherein the molar ratio of silicon-bonded hydrogen atoms in components (B) and (C) to alkenyl groups in component (A) is 0.80 or greater. Each of the components that make up the composition of the present invention is described in detail below.

[0009] 1.1 Component (A): Organopolysiloxane Component (A) is an organopolysiloxane that serves as a base polymer. The composition of the present invention contains, as component (A), an organopolysiloxane having, on average, two or more alkenyl groups bonded to silicon atoms per molecule. In one embodiment of the present invention, the alkenyl group may be an alkenyl group having 2 to 12 carbon atoms. Specific examples of alkenyl groups having 2 to 12 carbon atoms include vinyl, propenyl (including allyl), butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups. These groups also include structural isomers. In one aspect of the present invention, the alkenyl group is preferably an alkenyl group having 2 to 10 carbon atoms, more preferably an alkenyl group having 2 to 8 carbon atoms, still more preferably a group selected from the group consisting of a vinyl group, an allyl group, and a hexenyl group, and particularly preferably a vinyl group.

[0010] In component (A), the silicon-bonded group other than an alkenyl group may be a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. Examples of monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds include alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups. Examples of the alkyl groups include methyl, ethyl, propyl groups such as n-propyl and isopropyl, butyl groups such as n-butyl, isobutyl, s-butyl, and t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups. These groups also include structural isomers. Examples of the aryl groups include phenyl, tolyl, xylyl, and naphthyl groups. Examples of the aralkyl groups include benzyl, phenethyl, 3-phenylpropyl, and 4-phenylbutyl groups. The halogenated alkyl group may be a group in which some or all of the hydrogen atoms bonded to carbon atoms in the alkyl group have been substituted with halogen atoms such as chlorine atoms or bromine atoms, and specific examples include a chloromethyl group, a 3-chloropropyl group, a 3,3,3-trifluoropropyl group, etc. Among these, the monovalent hydrocarbon group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group.

[0011] The molecular structure of component (A) may be linear, partially branched linear, branched, cyclic, network, dendritic, or the like. In one embodiment of the present invention, component (A) is a mixture of two or more of these molecular structures. In another embodiment of the present invention, component (A) is one or more selected from the group consisting of linear organopolysiloxanes, branched organopolysiloxanes, and mixtures thereof.

[0012] Specific examples of linear organopolysiloxanes include dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, methylphenylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylphenylsiloxy groups, and dimethylpolysiloxanes capped at both molecular chain terminals with methylvinylphenylsiloxy groups.

[0013] Examples of branched organopolysiloxanes include MQ resins, MDQ resins, MTQ resins, MDTQ resins, TD resins, TQ resins, and TDQ resins, which are composed of any combination of triorganosiloxy units (M units) (organo groups are methyl groups only, or methyl groups and vinyl groups or phenyl groups), diorganosiloxy units (D units) (organo groups are methyl groups only, methyl groups and vinyl groups or phenyl groups), monoorganosiloxy units (T units) (organo groups are methyl groups, vinyl groups, or phenyl groups), and siloxy units (Q units).

[0014] In one embodiment of the present invention, the viscosity of component (A) at 25°C is, for example, in the range of 10 to 10,000 mPa·s, preferably 20 to 10,000 mPa·s, and more preferably 100 to 5,000 mPa·s. When the viscosity of component (A) is at or above the lower limit of the above range, the physical properties of the resulting silicone gel, particularly flexibility and elongation, can be significantly improved. Furthermore, when the viscosity of component (A) is at or below the upper limit of the above range, the handleability of the resulting silicone gel can be improved. Note that, in this specification, viscosity refers to the value measured at 25°C using a B-type viscometer.

[0015] 1.2 Component (B): Organohydrogenpolysiloxane Component (B) is an organohydrogenpolysiloxane that functions as a primary crosslinking agent. The composition of the present invention contains, as component (B), an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule. Component (B) is a compound containing a hydrosilyl group (—SiH) that is added to the monovalent hydrocarbon group having an aliphatic unsaturated bond in component (A) during the hydrosilylation reaction.

[0016] Specific examples of the organohydrogenpolysiloxane of component (B) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, 1-(3-glycidoxypropyl)-1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-di(3-glycidoxypropyl)-1,3,5,7-tetramethylcyclotetrasiloxane, 1-(3-glycidoxypropyl)-5-trimethoxysilylethyl-1,3,5,7-tetramethylcyclotetrasiloxane, and siloxanes having trimers at both ends of the molecular chain. Tylsiloxy-capped methylhydrogenpolysiloxane, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, dimethylpolysiloxane capped at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with dimethylhydrogensiloxy groups, methylhydrogensiloxane-diphenylsiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, hydrolysis condensate of trimethoxysilane, (CH ３ ) ２ HSiO １ / ２ Units and SiO ４ / ２ a copolymer consisting of (CH ３ ) ２ HSiO １ / ２ Units and SiO ４ / ２ Units and (C ６ H５ )SiO ３ / ２ The term "polyvinyl alcohol" includes copolymers consisting of these units, and mixtures of two or more of these units.

[0017] In one embodiment of the present invention, the viscosity of component (B) at 25°C is, for example, in the range of 2 to 1,000 mPa·s, preferably 2 to 500 mPa·s, more preferably 2 to 100 mPa·s, and even more preferably 5 to 50 mPa·s. When the viscosity of component (B) is at or above the lower limit of the above range, the physical properties of the resulting silicone gel, particularly flexibility and elongation, can be significantly improved. Furthermore, when the viscosity of component (B) is at or below the upper limit of the above range, the handleability of the resulting silicone gel can be improved.

[0018] In one embodiment of the present invention, the content of component (B) is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, and even more preferably 0.4 to 6 parts by mass per 100 parts by mass of component (A). When the content of component (B) is at or above the lower limit of the above range, the curability of the composition can be improved. Furthermore, when the content of component (B) is at or below the upper limit of the above range, foaming and changes in hardness at high temperatures can be suppressed, and the heat resistance of the cured product (silicone gel) can be further improved. Furthermore, when the content of component (B) is at or below the upper limit of the above range, production costs can be sufficiently reduced.

[0019] In one embodiment of the present invention, the content of component (B) is such that the molar ratio of silicon-bonded hydrogen atoms in component (B) to alkenyl groups in component (A) is 0.10 or more, 0.20 or more, or 0.30 or more. When the content of component (B) is equal to or greater than the above molar ratio, the curability of the composition can be improved. The upper limit of this molar ratio is not particularly limited, but may be, for example, 1.00 or less, 0.90 or less, or 0.80 or less.

[0020] 1.3 Component (C): Organosiloxane Compound Component (C) is an organosiloxane compound having SiH groups capable of capping the alkenyl groups of component (A) by undergoing a hydrosilylation reaction with the alkenyl groups. The composition of the present invention contains, as component (C), an organosiloxane compound having one silicon-bonded hydrogen atom per molecule. In the composition of the present invention, component (C) does not contain a compound having an alkoxysilyl group (0 mass %). The silicon-bonded group other than the silicon-bonded hydrogen atom in component (C) may be, for example, a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. The monovalent hydrocarbon group may be the same as those described in "1.1 Component (A): Organopolysiloxane." In the present invention, by using the above-mentioned component (C), which does not contain a compound having an alkoxysilyl group, a hydrolyzable group, in combination with the component (E) described below, the heat resistance of the silicone gel obtained by curing the composition of one embodiment of the present invention can be stably maintained for a long period of time. On the other hand, even when components (C) and (E) are used in combination, if the composition of the present invention contains a large amount of the above-mentioned compound having an alkoxysilyl group (i.e., an organosiloxane compound having one silicon-bonded hydrogen atom and one or more alkoxysilyl groups per molecule), the effect of improving heat resistance over a long period of time may be reduced. That is, in one embodiment of the composition of the present invention, from the viewpoint of further improving the heat resistance of the cured product (silicone gel), the content of the organosiloxane compound having one silicon-bonded hydrogen atom and one or more alkoxysilyl groups per molecule is preferably 5 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.1 parts by mass or less, and particularly preferably 0 part by mass (i.e., the composition of the present invention does not contain the above-mentioned compound) per 100 parts by mass of component (A).

[0021] In one embodiment of the present invention, component (C) includes one or more compounds selected from the group consisting of compounds represented by the following general formulas (1) to (7):

[0022] In the above general formula (1), R １ ~R ５ are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. The monovalent hydrocarbon groups may be the same or different. Specific examples of the monovalent hydrocarbon groups include alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups. Specific examples of the alkyl groups include methyl groups, ethyl groups, propyl groups such as n-propyl and isopropyl groups, butyl groups such as n-butyl, isobutyl, s-butyl, and t-butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, undecyl groups, and dodecyl groups. These groups also include structural isomers. Specific examples of the aryl groups include phenyl groups, tolyl groups, xylyl groups, and naphthyl groups. Specific examples of the aralkyl groups include benzyl groups, phenethyl groups, 3-phenylpropyl groups, and 4-phenylbutyl groups. The halogenated alkyl group may be a group in which some or all of the hydrogen atoms bonded to carbon atoms in the alkyl group have been substituted with halogen atoms such as chlorine atoms or bromine atoms, and specific examples include a chloromethyl group, a 3-chloropropyl group, a 3,3,3-trifluoropropyl group, etc. Among these, the monovalent hydrocarbon group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group.

[0023] In the above general formula (2), R １ ~R ３ , R ５ ~R ７ are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ４ is a group selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. １ ~R ３ , R ５ ~R ７The monovalent hydrocarbon groups that can be selected as may be the same or different groups. The monovalent hydrocarbon groups may be the same groups as those described in the general formula (1) above.

[0024] In the above general formula (3), R １ ~R ２ , R ５ ~R ７ are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ３ ~R ４ are each independently selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. The monovalent hydrocarbon groups may be the same or different. Furthermore, the monovalent hydrocarbon groups may be the same groups as those described in the general formula (1) above.

[0025] In the above general formula (4), R １ ~R ３ , R ７ ~R ９ are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ４ ~R ６ are each independently selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. The monovalent hydrocarbon groups may be the same or different. Furthermore, the monovalent hydrocarbon groups may be the same groups as those described in the general formula (1) above.

[0026] In the above general formula (5), R １ ~R ２ , R ７ ~R ９ are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ３ ~R ６are each independently selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups. The monovalent hydrocarbon groups may be the same or different. Furthermore, the monovalent hydrocarbon groups may be the same groups as those described in the general formula (1) above.

[0027] In the above general formula (6), R １ ~R ２ are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and R ３ is a group selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups, and a is an integer from 2 to 5. The monovalent hydrocarbon groups may be the same or different groups. Furthermore, the monovalent hydrocarbon groups may be the same groups as those described in the general formula (1) above. a may be an integer from 2 to 4, an integer from 2 to 3, or 2.

[0028] In the general formula (7), each R is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. The monovalent hydrocarbon groups may be the same or different. The monovalent hydrocarbon groups may also be the same groups as those described in the general formula (1).

[0029] The above-mentioned compound having an alkoxysilyl group includes, for example, a compound having a structure of the following formula (8).

[0030] In one embodiment of the present invention, the content of component (C) is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 8 parts by mass, and even more preferably 0.4 to 4 parts by mass per 100 parts by mass of component (A). When the content of component (C) is at or above the lower limit of the above range, the heat resistance of the composition can be improved. When the content of component (C) is at or below the upper limit of the above range, foaming and changes in hardness at high temperatures can be suppressed, and the heat resistance of the cured product (silicone gel) can be further improved. When the content of component (B) is at or below the upper limit of the above range, production costs can be sufficiently reduced.

[0031] In one embodiment of the present invention, the content of component (C) is preferably such that the molar ratio of silicon-bonded hydrogen atoms in components (B) and (C) to alkenyl groups in component (A) is 0.80 or more, greater than 0.80, 0.85 or more, or 0.90 or more. When the content of component (B) is equal to or greater than the above molar ratio, the curability of the composition can be improved. The upper limit of this molar ratio is not particularly limited, but may be, for example, 5.00 or less, 3.00 or less, 2.00 or less, or 1.50 or less.

[0032] 1.4 Component (D): Hydrosilylation Reaction Catalyst Component (D) is a component for accelerating the hydrosilylation reaction and curing the composition of the present invention. Specific examples of hydrosilylation reaction catalysts include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Among these, platinum-based catalysts are preferred because they can significantly accelerate curing. Specific examples of the platinum-based catalyst include platinum fine powder, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-alkenylsiloxane complexes, platinum-olefin complexes, platinum-carbonyl complexes, and catalysts in which these platinum-based catalysts are dispersed or encapsulated in thermoplastic resins such as silicone resins, polycarbonate resins, and acrylic resins. Among these, platinum-alkenylsiloxane complexes are preferred. The alkenylsiloxane may be 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which a portion of the methyl groups of these alkenylsiloxanes have been substituted with ethyl groups, phenyl groups, or the like, or alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, or the like. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is particularly preferred because of the good stability of the platinum-alkenylsiloxane complex. Catalysts that promote the hydrosilylation reaction also include non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt.

[0033] The hydrosilylation catalyst may also be a high-energy ray-activated catalyst (also called a photoactivated catalyst) that promotes the hydrosilylation reaction upon irradiation with high-energy rays such as ultraviolet rays. Examples of high-energy rays include ultraviolet rays, gamma rays, X-rays, alpha rays, and electron beams. Specific examples of the high energy ray activated catalyst include (methylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)trimethylplatinum(IV), (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)dimethylethylplatinum(IV), (cyclopentadienyl)dimethylacetylplatinum(IV), (trimethylsilylcyclopentadienyl)trimethylplatinum(IV), (methoxycarbonylcyclopentadienyl)trimethylplatinum(IV), (dimethylphenylsilylcyclopentadienyl)trimethylcyclopentadienylplatinum(IV), trimethyl(acetylacetonato)platinum(IV), trimethyl(3,5-heptanedionato) ... Examples of suitable platinum complexes include trimethyl(methylacetoacetate)platinum(IV), bis(2,4-pentanedionato)platinum(II), bis(2,4-hexanedionato)platinum(II), bis(2,4-heptanedionato)platinum(II), bis(3,5-heptanedionato)platinum(II), bis(1-phenyl-1,3-butanedionato)platinum(II), bis(1,3-diphenyl-1,3-propanedionato)platinum(II), and bis(hexafluoroacetylacetonato)platinum(II).

[0034] In one embodiment of the present invention, the content of component (D) is in the range of 0.001 to 5 parts by weight, 0.01 to 3 parts by weight, or 0.01 to 2 parts by weight per 100 parts by weight of component (A).

[0035] In one embodiment of the present invention, the content of component (D) is preferably in the range of 0.01 to 1,000 ppm by mass, more preferably 0.01 to 500 ppm by mass, and even more preferably 0.01 to 200 ppm by mass, of metal atoms in the catalyst, based on the total amount of the silicone gel-forming composition.

[0036] 1.5 Component (E): Heat-Resistant Additive Component (E) is a component that imparts heat resistance to the composition of the present invention. The heat-resistant additive has the effect of suppressing the increase in resin hardness due to, for example, cleavage of the dimethylsiloxane chain length, against the oxidative degradation of the silicone gel that occurs in high-temperature environments, such as at temperatures of 180°C or higher. In the present invention, the heat-resistant additive of component (E) is not particularly limited as long as it can impart heat resistance, and any additive known in the technical field can be used. In one embodiment, the heat-resistant additive is preferably one that can make the silicone gel-forming composition of one embodiment of the present invention substantially transparent. The term "substantially transparent" will be described later.

[0037] A composition according to one embodiment of the present invention includes, as component (E), one or more metals selected from the group consisting of metal silanolates and metal carboxylates. Metal silanolates are silicon-containing compounds having at least one unit in which a metal atom is bonded to a silicon atom via an oxygen atom. Metal carboxylates are salts of a metal atom and a carboxylic acid. Metals that form metal silanolates and metal carboxylates include, for example, cerium (Ce) (including trivalent and tetravalent), iron (Fe) (including divalent and trivalent), manganese (Mn), vanadium (V), magnesium (Mg), aluminum (Al), nickel (Ni), titanium (Ti), zinc (Zn), and niobium (Nb). In one embodiment of the present invention, the metal is cerium (Ce) or iron (Fe). Furthermore, in the metal carboxylate, the carboxylic acid may specifically be, for example, a linear aliphatic carboxylic acid such as ethanoic acid (acetic acid), propanoic acid (propionic acid), butanoic acid (butyric acid), pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), octadecanoic acid (stearic acid), or oleic acid; a branched aliphatic carboxylic acid such as 2-methylbutanoic acid, 2-methylpentanoic acid, 2-ethylhexanoic acid, 2-methylheptanoic acid, 4-methyloctanoic acid, or 3,5,5-trimethylhexanoic acid; or an alicyclic carboxylic acid such as naphthenic acid.

[0038] Specific examples of metal silanolates include cerium silanolate, iron silanolate, manganese silanolate, vanadium silanolate, magnesium silanolate, aluminum silanolate, nickel silanolate, titanium silanolate, zinc silanolate, and niobium silanolate. Specific examples of metal carboxylates include cerium carboxylate, iron carboxylate, manganese carboxylate, vanadium carboxylate, magnesium carboxylate, aluminum carboxylate, nickel carboxylate, titanium carboxylate, zinc carboxylate, and niobium carboxylate. These metal silanolates and metal carboxylates may be used alone or in combination of two or more. In one embodiment of the present invention, component (E) comprises one or more selected from the group consisting of cerium silanolate, iron silanolate, cerium carboxylate, and iron carboxylate.

[0039] The metal silanolate may be synthesized by a known method or may be a commercially available product. The metal silanolate can be synthesized by referring to the descriptions in, for example, WO 2022 / 013917 and JP 2019-518777 A.

[0040] In one embodiment of the present invention, the heat-resistant additive of component (E) may include a reaction product obtained by heat-treating a metal carboxylate and an organopolysiloxane. The reaction product can be synthesized by referring to the description in, for example, JP 2015-7203 A.

[0041] The content of component (E) is preferably 0.02 to 5 parts by mass, more preferably 0.02 to 3 parts by mass, and even more preferably 0.20 to 1 part by mass, per 100 parts by mass of component (A). Furthermore, the content of component (E) is preferably an amount such that the content of metal atoms in component (E) is 1 to 500 ppm by mass, and more preferably 10 to 300 ppm by mass, relative to the total amount of the composition. By adjusting the amount of component (E) within this range, the heat resistance of the resulting silicone gel can be improved.

[0042] 1.6 Optional Components In addition to components (A) to (E), the composition of one embodiment of the present invention may contain, as necessary, other organopolysiloxanes; adhesion promoters; cure inhibitors; inorganic fillers such as silica, glass, alumina, and zinc oxide; fine organic resin powders such as polymethacrylate; phosphors; dyes; pigments; flame retardants; solvents; and the like.

[0043] In one embodiment of the present invention, the adhesion promoter includes, for example, 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,4-bis(trimethoxysilyl)hexane, 1,5-bis(trimethoxysilyl)hexane, 2,5-bis(trimethoxysilyl)hexane, 1-methyldimethoxysilyl-6-trimethoxysilylhexane, 1-phenyldiethoxysilyl-6-triethoxysilylhexane, and 1,6-bis(methyldimethoxysilyl)hexane.

[0044] In one embodiment of the present invention, cure inhibitors include, for example, acetylenic compounds such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, and 1-ethynylcyclohexanol; eneyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; triazoles such as benzotriazole; phosphines; mercaptans; and hydrazines.

[0045] 1.7 Production Method and Form of the Composition of the Present Invention The composition of one embodiment of the present invention can be produced by uniformly mixing components (A) to (E) and any optional components used as needed at room temperature (e.g., 15 to 30°C) using the mechanical force of a mixer or the like. Furthermore, the composition of one embodiment of the present invention may be a one-component (single-liquid) composition, or a multi-component composition of two or more components (two-liquid) types.

[0046] 1.8 Properties of the Composition of the Present Invention The composition of one embodiment of the present invention preferably has a viscosity at 25°C in the range of 100 to 10,000 mPa·s, more preferably 200 to 8,000 mPa·s, and even more preferably 300 to 5,000 mPa·s. Furthermore, the composition of one embodiment of the present invention is substantially transparent. As used herein, "substantially transparent" means that when the composition or a silicone gel described below is placed in a glass container or the like, the bottom (contact surface) of the glass container or the like can be visually observed through the composition or silicone gel. Furthermore, "substantially transparent" may be determined by visible light transmittance; for example, a composition with a visible light transmittance of 80% or more, preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more can be determined to be "substantially transparent."

[0047] 1.9 Uses of the Composition of the Present Invention The composition of one embodiment of the present invention can be used to seal electronic components because it stably maintains excellent heat resistance over a long period of time. Specific examples of such electronic components include electrical and electronic devices. The electrical and electronic devices may include electrical circuits or electrodes in which metal electrodes (silver, copper, aluminum, gold, etc.) and metal oxide film electrodes (ITO (indium tin oxide), etc.) are formed on a base material such as glass, epoxy resin, polyimide resin, phenolic resin, or ceramics. Examples of such electronic components include peripheral components of the electrical and electronic devices described above, automotive electronic components such as electronic control units (ECUs), automotive component cases, terminal boxes, lighting components, and solar cell modules, among other metal and / or resin structures that require durability and water resistance. Furthermore, examples of such electronic components include power devices (power semiconductors) for engine control (in transportation equipment), power / train systems, and air conditioning control. The composition of one embodiment of the present invention can be suitably used as an adhesive, potting material, coating material, sealant, or the like for protecting or adhering such electronic components.

[0048] 2. Electronic Component Sealant One aspect of the present invention provides an electronic component sealant (hereinafter also referred to as "electronic component sealant of the present invention") containing the silicone gel-forming composition described above in "1. Silicone Gel-Forming Composition." The components and composition of the silicone gel-forming composition contained in the electronic component sealant of the present invention are the same as those described above in "1. Silicone Gel-Forming Composition." Furthermore, the electronic components to which the electronic component sealant of the present invention can be applied are the same as those described above in "1.9 Uses of the Composition of the Present Invention."

[0049] The content of the silicone gel-forming composition contained in the electronic component encapsulant of one embodiment of the present invention is not particularly limited, but may be 30 to 100% by mass, 40 to 99% by mass, or 50 to 98% by mass, based on the total amount (100% by mass) of the electronic component encapsulant. In some embodiments, the electronic component encapsulant of the present invention may consist essentially of the silicone gel-forming composition of one embodiment of the present invention. As used herein, "consisting essentially of the silicone gel-forming composition of one embodiment of the present invention" means that the composition may contain other components, such as impurities, that may be unavoidably contained during the manufacturing process of the silicone gel-forming composition. In these embodiments, the electronic component encapsulant of the present invention may contain, for example, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.0% by mass or less, or 0.5% by mass or less of other components, based on the total amount (100% by mass) of the electronic component encapsulant.

[0050] The electronic component encapsulant according to one embodiment of the present invention is substantially transparent.

[0051] 3. Method for curing the composition of the present invention and silicone gel One aspect of the present invention provides a silicone gel (hereinafter also referred to as the "silicone gel of the present invention") obtained by curing the silicone gel-forming composition described above in "1. Silicone gel-forming composition" or the electronic component sealant described above in "2. Electronic component sealant." The silicone gel of the present invention can be prepared by curing the silicone gel-forming composition of one embodiment of the present invention under temperature conditions appropriate for the intended use. The temperature for curing the silicone gel-forming composition is not particularly limited, but is usually within the range of 25°C to 150°C.

[0052] The silicone gel of one embodiment of the present invention preferably has a 1 / 4 cone penetration value (initial penetration) as specified in JIS K2210 of 10 to 150, more preferably 20 to 120, and even more preferably 30 to 100.

[0053] The silicone gel of one embodiment of the present invention has a ¼ cone penetration value (penetration after 1000 hours) after being held at a high temperature of more than 210°C for 1000 hours or more and then cooled to 25°C at room temperature, of preferably 10 to 150, more preferably 20 to 120, and even more preferably 30 to 100. The silicone gel of one embodiment of the present invention has a ¼ cone penetration value (penetration after 2000 hours) after being held at a high temperature of more than 210°C for 2000 hours or more and then cooled to 25°C at room temperature, of preferably 10 to 150, more preferably 20 to 120, and even more preferably 30 to 100.

[0054] In the silicone gel of one embodiment of the present invention, the rate of change in penetration from the initial penetration after 1000 hours is preferably within 40%, more preferably within 35%, and even more preferably within 30%.In the silicone gel of one embodiment of the present invention, the rate of change in penetration from the initial penetration after 2000 hours is preferably within 50%, more preferably within 45%, and even more preferably within 40%.

[0055] 4. Electronic Component and Method for Manufacturing Electronic Component As one aspect, the present invention provides an electronic component (hereinafter also referred to as the "electronic component of the present invention") comprising the silicone gel described above in "3. Method for Curing the Composition of the Present Invention and Silicone Gel." Specific examples of the electronic component include those described above in "1.9 Uses of the Composition of the Present Invention." An electronic component of one aspect of the present invention comprises a cured layer made of the silicone gel of one aspect of the present invention. The cured layer may have a thickness of 1 to 50 mm, 2 to 40 mm, 5 to 30 mm, 5 to 20 mm, or 5 to 10 mm, depending on the type of electronic component.

[0056] Furthermore, as one aspect, the present invention provides a method for producing an electronic component (hereinafter also referred to as the "method for producing an electronic component of the present invention"), which comprises using the silicone gel-forming composition described above in "1. Silicone Gel-Forming Composition" or the electronic component sealant described above in "2. Electronic Component Sealant" (hereinafter also referred to as the "method for producing an electronic component of the present invention"). Specific examples of such electronic components include those described above in "1.9 Uses of the Composition of the Present Invention." Furthermore, the use is not particularly limited, and may involve applying the silicone gel-forming composition of the present invention or the electronic component sealant of the present invention to the electronic component as an adhesive, potting material, coating material, sealant, or the like at any stage in the manufacturing process of the electronic component. The amount or range of application can be appropriately determined depending on the type of electronic component.

[0057] The present invention will be further described below based on examples, but the present invention is not limited to the following examples.

[0058] The silicone gel-forming compositions of Examples 1 to 9 and Comparative Examples 1 to 4 were prepared by uniformly mixing the components listed below in the ratios shown in Table 1. These compositions were cured using the method described below, and the resulting cured products (silicone gels) were evaluated for their quarter-cone penetration and heat resistance. The evaluation results are shown in Table 1. In Table 1, the composition of each component is listed in parts by mass relative to 100 parts by mass of component (A). In Table 1, "H / Vi(component (B) / component (A))" represents the total moles of silicon-bonded hydrogen atoms in component (B) per mole of total vinyl groups in component (A). Similarly, in Table 1, "H / Vi(component (B) + (C) / component (A))" represents the total moles of silicon-bonded hydrogen atoms in components (B) and (C) per mole of total vinyl groups in component (A).

[0059] <Component (A)> Component (A-1): a compound represented by the following formula: ((CH ３ ) ２ (CH ２ =CH)SiO １／２ ) ２ ((CH ３ ) ２ SiO ２／２ ) １６０ Component (A-2): (CH ３ ) ２ SiO ２／２ Units 91.7 mol%, CH ３ SiO ３／２ 5.3 mol% of units, (CH ３ ) SiO １／２ 2.4 mol% of units, (CH ３ ) ２ (CH ２ =CH)SiO １／２ Branched polyorganosiloxane consisting of 0.6 mol% units (viscosity: 680 mPa s, vinyl group content: 0.20 mass%) Component (A-3): (CH ３ ) ２ SiO ２／２ Units 98.4 mol%, CH ３ SiO ４／２ 0.3 mol% of units, (CH ３ ) SiO １／２0.2 mol% of units, (CH ３ ) ２ (CH ２ =CH)SiO １／２ Branched polyorganosiloxane consisting of 1.1 mol% units (viscosity: 500 mPa·s, vinyl group content: 0.46% by mass) Component (A-4): a compound represented by the following formula: ((CH ３ ) ２ (CH ２ =CH)SiO １／２ ) ２ ((CH ３ ) ２ SiO ２／２ ) ２５０ ((CH ３ ) (C ６ H ５ ) SiO ２／２ ) １５ and a dimethylpolysiloxane-methylphenylpolysiloxane copolymer (viscosity: 3200 mPa s, vinyl group content: 0.25% by mass) endblocked at both ends by dimethylvinylsiloxy groups, as represented by the formula (1). Each of the above components (A-1) to (A-4) has an average of two or more alkenyl groups bonded to silicon atoms per molecule.

[0060] <Component (B)> Component (B-1): a compound represented by the following formula: ((CH ３ ) HSiO １／２ ) ０．６７ (SiO ４／２ ) ０．３３ Component (B-2): A copolymer of dimethylsiloxane and methylhydrogensiloxane having trimethylsiloxy groups blocked at both ends of a linear molecular chain (viscosity: 9 mPa s, content of silicon-bonded hydrogen atoms: 0.75% by mass); Component (B-3): A dimethylpolysiloxane having dimethylhydrogensiloxy groups blocked at both ends of a linear molecular chain (viscosity: 14 mPa s, content of silicon-bonded hydrogen atoms: 0.15% by mass). Each of the above components (B-1) to (B-3) has two or more hydrogen atoms bonded to silicon atoms in one molecule.

[0061] <Component (C)> Component (C-1): Trisiloxane represented by the following formula (viscosity: 0.8 mPa·s)

[0062] <Component (D)> Component (D-1): Complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (platinum content: 0.5% by mass)

[0063] <Component (E)> Component (E-1): cerium silanolate having an Si—O—Ce bond in the molecule (cerium content in the silanolate: 0.5% by mass) Component (E-2): iron (III) tris(2-ethylhexanoate) mineral spirit solution (iron content in the solution: 6% by mass)

[0064] <Component (F)> Component (F-1): 1-ethynylcyclohexanol (ETCH)

[0065] <Component (G)> Component (G-1): 1,6-bis(trimethoxysilyl)hexane

[0066] <Component (H)> Component (H-1): Hydrogensiloxane having a trialkoxysilyl group represented by the following formula (viscosity: 1.6 mPa·s)

[0067] [1 / 4 cone penetration of silicone gel] A silicone gel-forming composition was gently poured into a 50 mL glass beaker to a height of 3 cm from the bottom of the beaker, and then heated at 100°C for 30 minutes to produce a silicone gel. The 1 / 4 cone penetration of this silicone gel was measured using the method specified in JIS K2220. The 1 / 4 cone penetration of the silicone gel before being subjected to the heat resistance test described below was taken as the "initial penetration."

[0068] [Transparency of Silicone Gel] The cured silicone gel was visually observed from above the beaker, and if the bottom of the beaker was visible, it was deemed to be transparent and was judged to have passed.

[0069] [Heat Resistance of Silicone Gel] The silicone gel cured by the above method was placed in an oven at 225°C. After 1000 hours and 2000 hours, each sample was removed and cooled to room temperature at 25°C. The 1 / 4 cone penetration of this silicone gel was then measured according to the method specified in JIS K2220. The 1 / 4 cone penetrations after 1000 hours and 2000 hours were designated the "1000-hour penetration" and "2000-hour penetration," respectively, and samples whose change in penetration after 2000 hours from the initial penetration was within 50% were judged to be acceptable.

[0070]

[0071] As shown in Table 1, the silicone gels of Examples 1 to 9, which contained all of components (A) to (E), showed little change in their quarter-cone penetration values ​​even after 2000 hours of exposure to a high-temperature environment compared to before exposure, demonstrating excellent heat resistance over a long period of time and transparency. On the other hand, Comparative Example 1, which did not contain component (C), showed a significantly lower quarter-cone penetration value after 2000 hours compared to before exposure, indicating insufficient heat resistance. Comparative Example 2, which did not contain component (E), also showed a significantly lower quarter-cone penetration value even after 1000 hours compared to before exposure, indicating insufficient heat resistance. Comparative Example 3, in which the molar ratio of silicon-bonded hydrogen atoms in components (B) and (C) to alkenyl groups in component (A) was less than 0.80, showed a significantly lower quarter-cone penetration value after 2000 hours compared to before exposure, indicating insufficient heat resistance. Furthermore, in Comparative Example 4, which contained a hydrogensiloxane having a trialkoxysilyl group (component (H)), the ¼ cone penetration value after 2000 hours was significantly smaller than that before exposure, indicating that the sample did not have sufficient heat resistance.

Claims

1. A silicone gel-forming composition comprising the following components (A) to (E): (A) an organopolysiloxane having, on average, two or more alkenyl groups bonded to silicon atoms per molecule, (B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms per molecule, (C) an organosiloxane compound having one hydrogen atom bonded to a silicon atom per molecule (excluding compounds having an alkoxysilyl group), (D) a hydrosilylation reaction catalyst, and (E) a heat resistance additive, wherein the molar ratio of silicon-bonded hydrogen atoms in components (B) and (C) to the alkenyl groups in component (A) is 0.80 or more.

2. The silicone gel-forming composition according to claim 1, wherein the molar ratio of silicon-bonded hydrogen atoms in component (B) to alkenyl groups in component (A) is 0.10 or greater.

3. The silicone gel-forming composition according to claim 1, wherein component (C) comprises one or more compounds selected from the group consisting of compounds represented by the following general formulas (1) to (7): (In formula (1), R １ ~R ５ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. (In formula (2), R １ ~R ３ , R ５ ~R ７ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds; R ４ is a group selected from monovalent hydrocarbon groups having 1 to 12 carbon atoms that do not contain aliphatic unsaturated bonds, and trimethylsiloxy groups. (In formula (3), R １ ~R ２ , R ５ ~R ７ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds; R ３ ~R ４ are each independently a group selected from the group consisting of the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and a trimethylsiloxy group. (In formula (4), R １ ~R ３ , R ７ ~R ９ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds; R ４ ~R ６ are each independently a group selected from the group consisting of the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and a trimethylsiloxy group. (In formula (5), R １ ~R ２ , R ７ ~R ９ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds; R ３ ~R ６ are each independently a group selected from the group consisting of the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and a trimethylsiloxy group. (In formula (6), R １ ~R ２ are each independently the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds; R ３ are groups selected from the group consisting of identical or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds, and trimethylsiloxy groups, and a is an integer from 2 to 5. (In formula (7), each R is independently the same or different monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds.) 4. The silicone gel forming composition according to claim 1, wherein component (A) has a viscosity of 10 to 10,000 mPa·s at 25°C, and component (B) has a viscosity of 2 to 1,000 mPa·s at 25°C.

5. The silicone gel-forming composition according to claim 1, wherein component (A) is at least one member selected from the group consisting of linear organopolysiloxanes, branched organopolysiloxanes, and mixtures thereof.

6. The silicone gel-forming composition according to claim 1, wherein the content of component (D) is 0.01 to 1,000 ppm by mass based on the total amount of the silicone gel-forming composition.

7. The silicone gel-forming composition according to claim 1, wherein component (E) comprises at least one member selected from the group consisting of metal silanolates and metal carboxylates.

8. The silicone gel-forming composition of claim 7, wherein said metal is selected from the group consisting of cerium, iron, manganese, vanadium, magnesium, aluminum, nickel, titanium and zinc.

9. The silicone gel-forming composition of claim 1, which is substantially transparent.

10. The silicone gel-forming composition according to claim 1 for use in encapsulating electronic components.

11. The silicone gel forming composition according to claim 10, wherein the electronic component is a power device.

12. An electronic component sealant comprising the silicone gel-forming composition according to claim 1.

13. The electronic component encapsulant of claim 12, which is substantially transparent.

14. A silicone gel obtained by curing the silicone gel-forming composition according to any one of claims 1 to 11 or the electronic component sealant according to claim 12 or 13.

15. The silicone gel according to claim 14, which has a 1 / 4 cone penetration value, as specified in JIS K2210, of 10 to 150.

16. An electronic component comprising the silicone gel of claim 14.

17. A method for producing an electronic component, comprising using the silicone gel-forming composition according to any one of claims 1 to 11 or the electronic component sealant according to claim 12 or 13.