Curable silicone composition, sealing material, and optical semiconductor device

Abstract

To provide a curable silicone composition which has high thixotropy and can form a cured product exhibiting an excellent refractive index and excellent transparency.SOLUTION: The curable silicone composition contains (A) an alkenyl group-containing organopolysiloxane having at least two alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms per molecule, (C) silica-titania composite oxide particles in an amount of 3 mass% or more based on the total mass of the composition, and (D) a curing catalyst.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable silicone composition, more specifically to a curable silicone composition suitable for use as an encapsulant for optical semiconductors. The present invention also relates to an optical semiconductor device encapsulated with an encapsulant made of a cured product of such a curable silicone composition. [Background technology]

[0002] Curable silicone compositions are used in a wide range of industrial fields because they cure to form cured products that have excellent heat resistance, cold resistance, electrical insulation, weather resistance, water resistance, and transparency. In particular, the cured products are less susceptible to discoloration than other organic materials and show little deterioration in physical properties such as durability, so they are widely used as silicone encapsulants for optical materials, particularly in optical semiconductor devices such as light-emitting diodes (LEDs).

[0003] In recent years, silicone encapsulants used in optical semiconductor devices such as light-emitting diodes (LEDs) are required to have high transparency and a high refractive index in order to achieve higher light extraction efficiency.

[0004] For example, Patent Document 1 describes a hydrosilylation-curable organopolysiloxane composition comprising: (A) a methylphenylalkenylpolysiloxane in which diphenylsiloxane units account for 5 mol % or less of the total siloxane units, at least 20 mol % of all silicon-bonded organic groups in the molecule are phenyl groups, and at least two silicon-bonded alkenyl groups per molecule; (B) a methylphenylhydrogenpolysiloxane in which diphenylsiloxane units account for 5 mol % or less of the total siloxane units, at least 20 mol % of all silicon-bonded organic groups in the molecule are phenyl groups, and at least two silicon-bonded hydrogen atoms per molecule; and (C) a hydrosilylation reaction catalyst, wherein the diphenylsiloxane units in the composition account for 5 mol % or less of the total siloxane units.

[0005] Patent Document 2 also describes a silicone resin composition for coating the light-transmitting surface of a light-emitting diode, which comprises a linear organopolysiloxane component represented by general formula (I) and a compound represented by the following average composition formula (2)H C (R 4 ) d SiO (4-c-d) / 2 (2)(wherein, R 4 are each independently an unsubstituted or halogen atom- or cyano-substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and c and d are numbers that satisfy the conditions 0.001≦c<2, 0.7≦d≦2, and 0.8≦c+d≦3. The document describes a silicone resin composition that contains an organohydrogenpolysiloxane component having two or more SiH groups per molecule, represented by the formula (I) and a plurality of liquid components including a platinum group metal catalyst, wherein the linear organopolysiloxane component contains less than 10% of organosiloxanes with a molecular weight of 1,000 or less, and the content of organosiloxanes with a molecular weight of 1,000 or less is less than 10%, and the silicone resin composition gives a cured product with a Shore 00 hardness of 85 or less.

[0006] Patent Document 3 also describes (A) a branched-chain organopolysiloxane having at least three alkenyl groups per molecule, and at least 30 mol % of all silicon-bonded organic groups being aryl groups; (B) a linear organopolysiloxane having aryl groups and both molecular chain terminals blocked with diorganohydrogensiloxy groups {in an amount such that the number of silicon-bonded hydrogen atoms in this component is 0.5 to 2 moles per mole of alkenyl groups in component (A)}; (C) a branched-chain organopolysiloxane having at least three diorganohydrogensiloxy groups per molecule, and at least 30 mol % of all silicon-bonded organic groups being aryl groups; The document describes a curable organopolysiloxane composition comprising at least a branched-chain organopolysiloxane having diorganohydrogensiloxy groups in which at least 15 mol % of all silicon-bonded organic groups are aryl groups {in an amount such that the diorganohydrogensiloxy groups in component (B) and this component account for 1 to 20 mol % of the total diorganohydrogensiloxy groups}, and (D) a hydrosilylation reaction catalyst (in an amount sufficient to promote curing of this composition).

[0007] Patent Document 4 also discloses a curable composition comprising: (A) an organopolysiloxane having an average composition formula of the following Chemical Formula 1; and (B) an organopolysiloxane containing an alkenyl group, an epoxy group, and an aryl group: [Chemical Formula 1] (R 1 R 2 2SiO 1 / 2 ) a (R 3 R 4 SiO 2 / 2 ) b (R 5 SiO 3 / 2 ) c (SiO2) d (In the above chemical formula 1, R 1 is a monovalent hydrocarbon group having two or more carbon atoms, and R 2 is an alkyl group having 1 to 4 carbon atoms, and R 3 and R 4 are each independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 25 carbon atoms; R 5 is an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, and R 1 , R 3 and R 4 at least one of is an alkenyl group, a is a positive number, b is 0 or a positive number, c is a positive number, d is 0 or a positive number, b / a is 5 or more, and b / c is 5 or more).

[0008] However, conventional curable silicone compositions have insufficient thixotropy, and so even if an appropriate amount of the composition is applied directly to an optical semiconductor on a support substrate using a dispenser and then cured, the applied curable silicone composition flows, and a cured product having the desired shape cannot be obtained. Furthermore, when particles such as silica are added to improve the thixotropy, the transparency of the resulting cured product can be reduced. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Special Publication No. 2012-507582 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-159586 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-1336 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-507025 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a curable silicone composition that is capable of forming a cured product that has high thixotropy, refractive index, and hardness, and that exhibits excellent transparency.

[0011] Another object of the present invention is to provide an encapsulant containing the curable silicone composition of the present invention. Still another object of the present invention is to provide an optical semiconductor device encapsulated with the encapsulant of the present invention. [Means for solving the problem]

[0012] In order to solve the above problems, the present inventors conducted extensive research and surprisingly discovered that by using a specific amount of silica-titania composite oxide particles as a filler, a curable silicone composition can be made to exhibit excellent thixotropy that is suitable for forming into a desired shape, and it is also possible to form a cured product that has excellent refractive index, hardness, and transparency, and this led to the completion of the present invention.

[0013] Therefore, the present invention provides (A) an alkenyl group-containing organopolysiloxane having at least two alkenyl groups per molecule; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule; (C) 3% by mass or more of silica-titania composite oxide particles relative to the total mass of the composition, and (D) Curing catalyst The present invention relates to a curable silicone composition comprising:

[0014] (C) The specific surface area of ​​silica-titania composite oxide particles is 50 m 2 / g or more is preferable.

[0015] (C) The refractive index of the silica-titania composite oxide particles at 25° C. and a wavelength of 589 nm is preferably 1.40 or more.

[0016] The curable silicone composition of the present invention preferably has a refractive index of 1.50 or greater at 25°C and a wavelength of 589 nm.

[0017] (A) The alkenyl group-containing organopolysiloxane preferably comprises a resinous organopolysiloxane, a linear organopolysiloxane, or both, in which the amount of aryl groups relative to all silicon-bonded functional groups is 20 mol % or more.

[0018] The curable silicone composition of the present invention preferably has a viscosity at 25°C of 30 Pa·s or less.

[0019] The present invention also relates to a sealant comprising the curable silicone composition of the present invention.

[0020] The present invention also relates to an optical semiconductor device comprising the encapsulant according to the present invention. [Effects of the Invention]

[0021] The curable silicone composition according to the present invention can provide a curable silicone composition that can form a cured product that is excellent in transparency, hardness, and refractive index, while maintaining thixotropy that is suitable for forming a desired shape when applied. DETAILED DESCRIPTION OF THE INVENTION

[0022] [Curable Silicone Composition] The curable silicone composition according to the present invention comprises: (A) an alkenyl group-containing organopolysiloxane having at least two alkenyl groups per molecule; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule; (C) 3% by mass or more of silica-titania composite oxide particles relative to the total mass of the composition, and (D) Curing catalyst At least includes.

[0023] Each component of the curable silicone composition of the present invention will now be described in detail.

[0024] (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule; Component (A), which is the main component of the composition, is a curable organopolysiloxane containing at least two alkenyl groups per molecule. The curable silicone composition of the present invention may contain one type of alkenyl-containing organopolysiloxane (A), or may contain two or more types of alkenyl-containing organopolysiloxanes (A).

[0025] Examples of the molecular structure of component (A) include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures. Component (A) may be a single organopolysiloxane having any of these molecular structures, or a mixture of two or more organopolysiloxanes having any of these molecular structures. Preferably, the curable silicone composition of the present invention contains both a linear alkenyl group-containing organopolysiloxane and a resinous alkenyl group-containing organopolysiloxane as component (A). In this specification, resinous refers to a molecular structure having a branched or three-dimensional network structure.

[0026] Examples of alkenyl groups contained in component (A) include alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups, with vinyl groups being preferred.

[0027] Examples of silicon-bonded groups other than alkenyl groups contained in component (A) include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, such as alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. Furthermore, the silicon atoms in component (A) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the objectives of the present invention are not impaired. The groups bonded to silicon atoms in component (A) other than alkenyl groups are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups, and aryl groups having 6 to 20 carbon atoms, particularly phenyl groups.

[0028] In one embodiment of the present invention, component (A) may contain, as component (A-1), a resin-like alkenyl group-containing organopolysiloxane. (A-1) The resin-like alkenyl group-containing organopolysiloxane is preferably Average unit formula (I): (R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 SiO 3 / 2 ) c (SiO 4 / 2 ) d (XO1 / 2 ) e (In formula (I), R 1 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 1 is an alkenyl group, 0≦a<1, 0≦b<1, 0≦c<0.9, 0≦d<0.5, and 0≦e<0.4, a+b+c+d=1.0, and c+d>0.

[0029] R in the above formula (I) 1 Examples of halogen-substituted or unsubstituted monovalent hydrocarbon groups include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. R 1 R may contain a small amount of hydroxyl groups or alkoxy groups such as methoxy groups and ethoxy groups, as long as the object of the present invention is not impaired. 1 is preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly a methyl group, alkenyl groups having 2 to 6 carbon atoms, particularly a vinyl group, or aryl groups having 6 to 20 carbon atoms, particularly a phenyl group.

[0030] In the above formula (I), X is a hydrogen atom or an alkyl group. The alkyl group for X is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, and a propyl group.

[0031] In the above formula (I), a is preferably in the range of 0.05≦a≦0.8, more preferably in the range of 0.1≦a≦0.6, and even more preferably in the range of 0.15≦a≦0.4. In the above formula (I), b is preferably in the range of 0≦b≦0.6, more preferably in the range of 0≦b≦0.4, and particularly in the range of 0≦b≦0.2. In the above formula (I), c is preferably in the range of 0.2≦c<0.9, more preferably in the range of 0.3≦c≦0.85, and particularly in the range of 0.4≦c≦0.8. In the above formula (I), d is preferably in the range of 0≦d≦0.4, more preferably in the range of 0≦d≦0.25, and particularly in the range of 0≦d≦0.1. In the above formula (I), e is preferably in the range of 0≦e≦0.15, more preferably in the range of 0≦e≦0.1, and particularly in the range of 0≦e≦0.05.

[0032] In a preferred embodiment of the present invention, the resinous alkenyl group-containing organopolysiloxane of component (A-1) is a polysiloxane represented by the above formula (I), where c is greater than 0, i.e., SiO 3 / 2 The resinous organopolysiloxane of component (A-1) contains siloxane units (T units) represented by the formula: SiO 4 / 2 The siloxane unit (Q unit) represented by the following formula (1) may or may not be contained, but preferably is not contained.

[0033] In a preferred embodiment of the present invention, the resinous alkenyl-containing organopolysiloxane of component (A-1) contains alkenyl groups at the molecular terminals. The resinous organopolysiloxane of component (A-1) is preferably SiO 1 / 2 The siloxane unit (M unit) has an alkenyl group, and the molecular chain side chain (i.e., SiO 2 / 2 Siloxane units (D units) represented by the formula: and SiO 3 / 2 The siloxane units (T units) represented by the following formula may or may not contain an alkenyl group, but preferably do not contain an alkenyl group.

[0034] The alkenyl group content of all silicon-bonded organic groups in the resinous alkenyl-group-containing organopolysiloxane of component (A-1) is not particularly limited, but may be, for example, 3 mol% or more, preferably 5 mol% or more, and more preferably 8 mol% or more of the total silicon-bonded organic groups, and 40 mol% or less, preferably 30 mol% or more, and more preferably 20 mol% or less of the total silicon-bonded organic groups. The alkenyl group content can be determined, for example, by analytical methods such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR), or by the following titration method.

[0035] This section explains how to quantify the amount of alkenyl groups in each component using titration. The alkenyl group content in organopolysiloxane components can be accurately quantified using a titration method commonly known as the Wyss method. The principle is as follows: First, alkenyl groups in the organopolysiloxane raw material are subjected to an addition reaction with iodine monochloride as shown in equation (1). Next, excess iodine monochloride is reacted with potassium iodide and liberated as iodine via the reaction shown in equation (2). The liberated iodine is then titrated with a sodium thiosulfate solution. Equation (1) CH₂=CH- + 2ICl → CH₂I-CHCl- + ICl (excess) Formula (2) ICl+KI → I2+ KCl The amount of alkenyl groups in the component can be quantified from the difference between the amount of sodium thiosulfate required for titration and the amount of titration of a separately prepared blank solution.

[0036] In a preferred embodiment of the present invention, the resinous alkenyl-containing organopolysiloxane of component (A-1) contains an aryl group in the silicon-bonded organic group. That is, in the above formula (I), at least one R 1may be an aryl group. In a preferred embodiment of the present invention, the alkenyl-containing resinous organopolysiloxane of component (A-1) contains silicon-bonded aryl groups in molecular side chains, i.e., in D units and / or T units, and particularly preferably contains silicon-bonded aryl groups only in T units. The alkenyl-containing resinous organopolysiloxane of component (A-1) may or may not contain aryl groups at the molecular terminals, i.e., in M ​​units, but preferably does not. Examples of aryl groups include aryl groups having 6 to 20 carbon atoms, particularly phenyl, tolyl, xylyl, and naphthyl groups.

[0037] When the resinous organopolysiloxane of component (A-1) contains aryl groups, their content (the mole percent of aryl groups relative to all silicon-bonded functional groups in the resinous organopolysiloxane) can be designed as desired, but is usually 5 mole percent or more, preferably 10 mole percent or more, more preferably 15 mole percent or more, even more preferably 20 mole percent or more, and particularly preferably 25 mole percent or more, and is usually 70 mole percent or less, preferably 60 mole percent or less, and more preferably 55 mole percent or less. The aryl group content can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR), etc.

[0038] The organopolysiloxane of component (A-1) is preferably solid or semi-solid at 25° C. There are no particular limitations on the number-average molecular weight of the organopolysiloxane of component (A-1), but it can be in the range of 500 to 10,000.

[0039] When component (A) contains one or more types of resinous organopolysiloxane (A-1), its content is not particularly limited, but is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, based on the total mass of the curable silicone composition of the present invention. Also, the content of component (A-1) is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and particularly preferably 70% by mass or less, based on the total mass of all organopolysiloxane components.

[0040] In one embodiment of the present invention, when two types of (A-1) resinous alkenyl group-containing organopolysiloxanes are contained, the second (A-1) component may contain a resinous alkenyl group-containing organopolysiloxane monomer consisting of only one T unit. The content of this second (A-1) component is not particularly limited, but is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total mass of the curable silicone composition of the present invention, and is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0041] Component (A) may contain a linear alkenyl group-containing organopolysiloxane as component (A-2). The linear alkenyl group-containing organopolysiloxane of component (A-2) is preferably Average structural formula (II):R 2 3SiO(R 2 2SiO 2 / 2 ) m SiR 2 3 (In formula (II), R 2 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 2 is an alkenyl group, and m is 1 to 500).

[0042] In the above formula (II), R 2The halogen-substituted or unsubstituted monovalent hydrocarbon group may be the same as that in formula (I) above.

[0043] In the above formula (II), m is preferably 2 to 300, more preferably 5 to 200, even more preferably 10 to 100, and particularly preferably 15 to 50.

[0044] Examples of such component (A-2) include dimethylpolysiloxanes terminally blocked with dimethylvinylsiloxy groups, dimethylpolysiloxanes terminally blocked with diphenylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminally blocked with diphenylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups, and dimethylsiloxane-methylvinylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups. Examples include dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxy groups at both molecular chain ends, dimethylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxy groups at both molecular chain ends, methylvinylpolysiloxanes capped with trimethylsiloxy groups at both molecular chain ends, methylvinylsiloxane-methylphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends, methylvinylsiloxane-diphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends, and dimethylsiloxane-methylvinylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends.

[0045] In a preferred embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) may be a linear organopolysiloxane capped with alkenyl groups at both molecular chain terminals, i.e., containing alkenyl groups at both molecular chain terminals. The linear organopolysiloxane of component (A-2) may or may not contain alkenyl groups in molecular chain side chains (i.e., D units), but preferably does not.

[0046] The alkenyl group content (mol % of alkenyl groups relative to all silicon-bonded functional groups in the linear organopolysiloxane) of component (A-2) can be designed as desired, but is usually 1 mol % or more, preferably 2 mol % or more, and more preferably 3 mol % or more, and can be 20 mol % or less, preferably 15 mol % or less, more preferably 10 mol % or less, and preferentially 7 mol % or less. The alkenyl group content can be determined, for example, by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), or by the titration method described above.

[0047] In one embodiment of the present invention, the linear organopolysiloxane of component (A-2) contains an aryl group in the silicon-bonded organic group. That is, in the above formula (II), at least one R 2 may be an aryl group. In a preferred embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) contains silicon-bonded aryl groups in side chains on the molecular chain. The linear organopolysiloxane of component (A-2) may or may not contain aryl groups at the molecular chain terminals (i.e., M units), but preferably does not.

[0048] When the linear organopolysiloxane of component (A-2) contains aryl groups, their content (the mole percent of aryl groups relative to all silicon-bonded functional groups in the linear organopolysiloxane) can be designed as desired, but is usually 15 mole percent or more, preferably 25 mole percent or more, more preferably 30 mole percent or more, and even more preferably 35 mole percent or more, and can be 75 mole percent or less, preferably 65 mole percent or less, more preferably 60 mole percent or less, preferentially 55 mole percent or less, and particularly preferably 50 mole percent or less. The aryl group content can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR), etc.

[0049] When component (A) contains linear organopolysiloxane (A-2), its content is not particularly limited, but is preferably 1 mass % or more, more preferably 2 mass % or more, and even more preferably 3 mass % or more, based on the total mass of the curable silicone composition of the present invention. Also, the content of component (A-2) is preferably 20 mass % or less, more preferably 15 mass % or less, even more preferably 10 mass % or less, and particularly preferably 5 mass % or less, based on the total mass of the curable silicone composition of the present invention.

[0050] In a preferred embodiment, component (A) comprises an alkenyl-containing organopolysiloxane containing a large number of aryl groups in the silicon-bonded functional groups, specifically, (A-1) a resinous organopolysiloxane, (A-2) a linear organopolysiloxane, or both, in which the amount of aryl groups in all silicon-bonded functional groups is 20 mol % or more, preferably 25 mol % or more.

[0051] Other alkenyl group-containing organopolysiloxane components The curable silicone composition component according to the present invention may contain, as other organopolysiloxane components, (A-3) an epoxy group-containing organopolysiloxane and / or (A-4) a cyclic organopolysiloxane.

[0052] The molecular structure of the epoxy group-containing organopolysiloxane (A-3) can be exemplified by linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures, and preferably The curable silicone composition according to the present invention may contain one type of epoxy group-containing organopolysiloxane, or may contain a combination of two or more types of epoxy group-containing organopolysiloxanes.

[0053] The epoxy group-containing resinous organopolysiloxane preferably has the following average unit formula (IV): (R 4 3SiO 1 / 2 ) f (R5 2SiO 2 / 2 ) g (R 4 SiO 3 / 2 ) h (SiO 4 / 2 ) i (XO 1 / 2 ) j {In formula (IV), each R 4 is independently a halogen-substituted or unsubstituted monovalent hydrocarbon group, provided that at least two R 4 are alkenyl groups, each R 5 is independently a halogen-substituted or unsubstituted monovalent hydrocarbon group or an epoxy group-containing organic group, provided that at least one R 5 is an epoxy group-containing organic group, X is a hydrogen atom or an alkyl group, 0 ≦ f < 1, 0 < g < 1, 0 ≦ h < 0.9, 0 ≦ i < 0.5, and 0 < j < 0.5, f + g + h + i + j = 1.0, h + i > 0, and j / (f + g + h + i + j) > 0.05}.

[0054] In the above (IV), the halogen-substituted or unsubstituted monovalent hydrocarbon groups of R 4 and R 5 are preferably alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group; aryl groups having 6 to 20 carbon atoms such as phenyl group, tolyl group, xylyl group, naphthyl group; alkenyl groups having 2 to 12 carbon atoms such as vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group; groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine atom, chlorine atom, bromine atom. R 4 is preferably selected from an alkyl group having 1 to 6 carbon atoms, particularly a methyl group, an alkenyl group having 2 to 6 carbon atoms, particularly a vinyl group, an aryl group having 6 to 20 carbon atoms, particularly a phenyl group.

[0055] In the above (IV), R 5 Examples of the epoxy group-containing organic group include glycidoxyalkyl groups such as 2-glycidoxyethyl, 3-glycidoxypropyl, and 4-glycidoxybutyl; epoxycycloalkylalkyl groups such as 2-(3,4-epoxycyclohexyl)-ethyl and 3-(3,4-epoxycyclohexyl)-propyl; and epoxyalkyl groups such as 3,4-epoxybutyl and 7,8-epoxyoctyl. Of these, glycidoxyalkyl groups are preferred, and 3-glycidoxypropyl is particularly preferred. 5 is preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups, alkenyl groups having 2 to 6 carbon atoms, particularly vinyl groups, aryl groups having 6 to 20 carbon atoms, particularly phenyl groups, and 3-glycidoxypropyl groups. 5 is preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly a methyl group, and a 3-glycidoxypropyl group.

[0056] In the above formula (IV), X is a hydrogen atom or an alkyl group. The alkyl group for X is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, and a propyl group.

[0057] In the above formula (IV), based on the assumption that f + g + h + i + j = 1.0, f is preferably in the range of 0.03 ≦ f ≦ 0.7, more preferably 0.06 ≦ f ≦ 0.5, and even more preferably 0.09 ≦ f ≦ 0.3. In the above formula (IV), g is preferably in the range of 0.05 ≦ g ≦ 0.6, more preferably 0.1 ≦ g ≦ 0.4, and particularly 0.2 ≦ g ≦ 0.3. In the above formula (IV), h is preferably in the range of 0.1 ≦ h ≦ 0.8, more preferably 0.25 ≦ h ≦ 0.7, and particularly 0.4 ≦ h ≦ 0.6. In the above formula (IV), i is preferably in the range of 0 ≦ i ≦ 0.4, more preferably 0 ≦ i ≦ 0.25, and particularly 0 ≦ i ≦ 0.1. In the above formula (IV), j is preferably in the range of 0.05≦j≦0.4, more preferably in the range of 0.1≦j≦0.3, and particularly in the range of 0.15≦j≦0.25.

[0058] In one embodiment, in the above formula (IV), j / (f+g+h+i+j) is greater than 0.05. Preferably, j / (f+g+h+i+j) is greater than 0.08, more preferably greater than 0.11, and even more preferably greater than 0.14. Furthermore, j / (f+g+h+i+j) is usually less than 0.5, preferably less than 0.4, more preferably less than 0.3, and particularly preferably less than 0.25.

[0059] In a preferred embodiment of the present invention, the epoxy group-containing resinous organopolysiloxane is a resin represented by the above formula (IV), where h is greater than 0, i.e., SiO 3 / 2 The epoxy group-containing resinous organopolysiloxane of component (C) contains siloxane units (T units) represented by the formula: SiO 4 / 2 The siloxane unit (Q unit) represented by the following formula (1) may or may not be contained, but preferably is not contained.

[0060] In a preferred embodiment of the present invention, the epoxy group-containing organopolysiloxane contains an alkenyl group at the molecular terminal. The epoxy group-containing organopolysiloxane is preferably SiO 1 / 2 The siloxane unit (M unit) has an alkenyl group, and the molecular side chain (i.e., SiO 2 / 2 Siloxane units (D units) represented by the formula: and SiO 3 / 2 The siloxane units (T units) represented by the following formula may or may not contain an alkenyl group, but preferably do not contain an alkenyl group.

[0061] In a preferred embodiment, the amount of alkenyl groups in all silicon-bonded organic groups in the epoxy group-containing organopolysiloxane is not particularly limited, but is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and particularly preferably 7 mol% or more, and may be, for example, 30 mol% or less, preferably 20 mol% or less, and more preferably 15 mol% or less.

[0062] In a preferred embodiment of the present invention, the epoxy group-containing resinous organopolysiloxane contains an aryl group in the silicon atom-bonded organic group. 4 and R 5 At least one of these may be an aryl group. In a preferred embodiment of the present invention, the epoxy group-containing resinous organopolysiloxane contains silicon-bonded aryl groups in the molecular side chains, i.e., D units or T units, preferably T units. The epoxy group-containing resinous organopolysiloxane may or may not contain aryl groups at the molecular terminals, i.e., M units, but preferably does not. Examples of aryl groups include aryl groups having 6 to 20 carbon atoms, particularly phenyl, tolyl, xylyl, and naphthyl groups.

[0063] When the epoxy group-containing organopolysiloxane contains aryl groups, the content thereof (the mole % of aryl groups relative to all silicon-bonded functional groups in the epoxy group-containing organopolysiloxane) can be designed as desired, but is preferably 15 mole % or more, more preferably 20 mole % or more, even more preferably 25 mole % or more, and particularly preferably 30 mole % or more, and is preferably 70 mole % or less, more preferably 60 mole % or less, even more preferably 50 mole % or less, and particularly preferably 40 mole % or less.

[0064] The amount of epoxy-containing organic groups in the epoxy-containing organopolysiloxane relative to the total silicon-bonded organic groups is not particularly limited, but is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, particularly preferably 15 mol% or more, and is, for example, 40 mol% or less, preferably 30 mol% or less, more preferably 25 mol% or less. The amount of epoxy-containing organic groups can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR), nuclear magnetic resonance (NMR), etc.

[0065] In a preferred embodiment of the present invention, the epoxy-containing organopolysiloxane contains hydroxyl groups and / or alkoxy groups as silicon-bonded organic groups. The amount of hydroxyl groups and / or alkoxy groups relative to the total silicon-bonded organic groups in the epoxy-containing organopolysiloxane is not particularly limited, but is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, and is, for example, 30 mol% or less, preferably 20 mol% or less, and more preferably 15 mol% or less. The amount of hydroxyl groups and / or alkoxy groups can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR), etc.

[0066] The viscosity of the epoxy group-containing resinous organopolysiloxane is not particularly limited, but is, for example, within the range of 50 mPa·s to 20,000 mPa·s, and preferably within the range of 50 mPa·s to 3,000 mPa·s at 25° C. In this specification, the viscosity of the organopolysiloxane component can be measured at 25° C. using a rotational viscometer in accordance with JIS K7117-1.

[0067] The amount of epoxy group-containing organopolysiloxane, particularly epoxy group-containing resinous organopolysiloxane, is not particularly limited, but is preferably contained in an amount of at least 0.5 mass %, more preferably at least 1 mass %, and even more preferably at least 2 mass %, based on the total mass of the curable silicone composition of the present invention; and may be contained in an amount of no more than 10 mass %, more preferably no more than 7 mass %, even more preferably no more than 5 mass %, and especially preferably no more than 4 mass %, based on the total mass of the curable silicone composition of the present invention.

[0068] The cyclic organopolysiloxane of component (A-4) is preferably Average structural formula (V):(R 6 2SiO) n (In formula (V), R 6 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 6 is an alkenyl group, and n is a number such that the viscosity at 25°C is 1000 mPa·s or less.

[0069] In the above formula (V), R 6 is a halogen-substituted or unsubstituted monovalent hydrocarbon group represented by R 1 The same can be applied.

[0070] In the above formula (V), n is a number that provides a viscosity of 1000 mPa s or less at 25°C, and is, for example, 4 to 15, preferably 4 to 10, and more preferably 4 to 8. In this specification, the viscosity of the organopolysiloxane component can be measured at 25°C using a rotational viscometer in accordance with JIS K7117-1.

[0071] In one embodiment, the alkenyl group content (mol % of alkenyl groups relative to all silicon-bonded functional groups in the cyclic organopolysiloxane of component (A-4)) can be designed as desired, but is usually 10 mol % or more, preferably 20 mol % or more, more preferably 30 mol % or more, even more preferably 40 mol % or more, and preferentially 45 mol % or more, and may be 80 mol % or less, preferably 70 mol % or less, more preferably 60 mol % or less, and preferentially 55 mol % or less. The alkenyl group content can be determined, for example, by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), titration, or other analytical methods.

[0072] The content of cyclic organopolysiloxane is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and particularly preferably 0.15% by mass or more, based on the total mass of the curable silicone composition of the present invention. Also, the content of cyclic organopolysiloxane is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less, based on the total mass of the curable silicone composition of the present invention.

[0073] The total amount of component (A) is not particularly limited, but is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, and particularly preferably 55% by mass or more, based on the total mass of the curable silicone composition. In a preferred embodiment, component (A) is contained in an amount of 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less, based on the total mass of the curable silicone composition.

[0074] (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule; Component (B) acts as a crosslinker for the curable silicone composition via a hydrosilylation curing reaction and is an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule. The curable silicone composition according to the present invention may contain one type of organohydrogenpolysiloxane (B), or may contain two or more types of organohydrogenpolysiloxane (B).

[0075] Examples of the molecular structure of component (B) include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures. Component (B) may be a single organohydrogenpolysiloxane having any of these molecular structures, or a mixture of two or more organohydrogenpolysiloxanes having any of these molecular structures. Preferably, the curable silicone composition of the present invention contains both a linear organohydrogenpolysiloxane and a resinous organohydrogenpolysiloxane as component (B).

[0076] Examples of silicon-bonded groups other than silicon-bonded hydrogen atoms contained in component (B) include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, such as alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, 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, chlorine, or bromine. The silicon atoms in component (B) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the objective of the present invention is not impaired. The groups bonded to silicon atoms other than silicon-bonded hydrogen atoms in component (B) are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups, and aryl groups having 6 to 20 carbon atoms, particularly phenyl groups.

[0077] In one embodiment of the present invention, the component (B) may contain a linear organohydrogenpolysiloxane as the component (B-1). The linear organohydrogenpolysiloxane of the component (B-1) is preferably Average structural formula (III):R 3 3SiO(R 3 2SiO 2 / 2 ) n SiR 3 3 (In formula (III), R 3 are hydrogen atoms or the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, provided that at least two R 4 is a hydrogen atom, and n is 1 to 100).

[0078] In the above formula (III), R 3Examples of halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups in R include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, 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, chlorine, or bromine. 3 R may contain a small amount of hydroxyl groups or alkoxy groups such as methoxy groups and ethoxy groups, as long as the object of the present invention is not impaired. 3 is preferably selected from a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, particularly a methyl group, or an aryl group having 6 to 20 carbon atoms, particularly a phenyl group.

[0079] In the above formula (III), m is preferably 1 to 50, more preferably 1 to 20, even more preferably 1 to 10, and particularly preferably 1 to 5.

[0080] In a preferred embodiment of the present invention, the linear organohydrogenpolysiloxane of component (B-1) contains silicon-bonded hydrogen atoms at both molecular chain terminals. The linear organohydrogenpolysiloxane of component (B-1) has silicon-bonded hydrogen atoms in the M units, and the D units may or may not contain silicon-bonded hydrogen atoms, but preferably do not.

[0081] The linear organohydrogenpolysiloxane of component (B-1) preferably contains silicon-bonded aryl groups in the molecular side chains. The linear organopolysiloxane of component (B-1) may or may not contain aryl groups at the molecular chain terminals, but preferably does not. In a preferred embodiment, the linear organohydrogenpolysiloxane of component (B-1) contains ArSiO 2 / 2(wherein Ar represents an aryl group), in which two aryl groups are substituted on one silicon atom.

[0082] In one embodiment of the present invention, when the linear organohydrogenpolysiloxane of component (B-1) contains aryl groups, the content of aryl groups in all silicon-bonded organic groups is not particularly limited, but may be, for example, 10 mol% or more, preferably 15 mol% or more, more preferably 20 mol% or more of the total silicon-bonded organic groups, and 50 mol% or less, preferably 40 mol% or more, more preferably 30 mol% or less of the total silicon-bonded organic groups. The aryl group content can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR), nuclear magnetic resonance (NMR), or the like.

[0083] When component (B) contains linear organohydrogenpolysiloxane (B-1), its content is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total mass of the curable silicone composition of the present invention; and may be contained in an amount of 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on the total mass of all organopolysiloxane components.

[0084] In one embodiment of the present invention, component (B) may include a resinous organohydrogenpolysiloxane as component (B-2). The resinous organohydrogenpolysiloxane of component (B-2) may preferably be represented by the following average unit formula (VI): Average unit formula (VI): (R 3 3SiO 1 / 2 ) a (R 3 2SiO 2 / 2 ) b (R 3 SiO 3 / 2 ) c (SiO 4 / 2 ) d (XO 1 / 2 ) e In formula (VI), R 3 are each independently a hydrogen atom or the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, provided that at least two R 3 is a hydrogen atom, 0≦a<1, 0≦b<1, 0≦c<0.9, 0≦d<0.7, and 0≦e<0.4, a+b+c+d=1.0, and c+d>0.

[0085] R in the above formula (VI) 3 The monovalent hydrocarbon group other than the halogen-substituted or unsubstituted alkenyl group and X are R 3 and the same applies to X.

[0086] In the formula (VI), a is preferably in the range of 0.1≦a≦0.9, more preferably in the range of 0.3≦a≦0.8, and even more preferably in the range of 0.5≦a≦0.7. In the formula (VI), b is preferably in the range of 0≦b≦0.5, more preferably in the range of 0≦b≦0.3, and particularly in the range of 0≦b≦0.1. In the formula (VI), c is preferably in the range of 0.1≦c≦0.7, more preferably in the range of 0.2≦c≦0.6, and particularly in the range of 0.3≦c≦0.5. In the formula (VI), d is preferably in the range of 0≦d≦0.5, more preferably in the range of 0≦d≦0.3, and particularly in the range of 0≦d≦0.1. In the formula (VI), e is preferably in the range of 0≦e≦0.15, more preferably in the range of 0≦e≦0.1, and particularly in the range of 0≦e≦0.05.

[0087] In a preferred embodiment of the present invention, the resinous organohydrogenpolysiloxane of component (B-2) has the above formula (VI) in which c is greater than 0, i.e., contains T units. The resinous organohydrogenpolysiloxane of component (B) may or may not contain Q units, but preferably does not contain them.

[0088] In a preferred embodiment of the present invention, the resinous organohydrogenpolysiloxane of component (B-2) contains silicon-bonded hydrogen atoms at the molecular terminals. The resinous organohydrogenpolysiloxane of component (B-2) preferably has silicon-bonded hydrogen atoms in the M units, and may or may not contain silicon-bonded hydrogen atoms in molecular side chains (i.e., D units and T units), but preferably does not.

[0089] When the resinous organohydrogenpolysiloxane of component (B-2) contains aryl groups, the content thereof (the mole % of aryl groups relative to all silicon-bonded functional groups in the resinous organohydrogenpolysiloxane) can be designed as desired, but is usually 1 mole % or more, preferably 5 mole % or more, more preferably 10 mole % or more, even more preferably 13 mole % or more, and particularly preferably 16 mole % or more, and can be 50 mole % or less, preferably 40 mole % or less, more preferably 35 mole % or less, preferentially 30 mole % or less, and particularly preferably 25 mole % or less.

[0090] In one embodiment of the present invention, the resinous organopolysiloxane of component (B-2) can be in a solid or liquid state, preferably a liquid, and its viscosity, at 25°C and 20°C, is not particularly limited, but is preferably in the range of 1 to 100,000 mPa·s, more preferably 2 to 50,000 mPa·s, and even more preferably 3 to 10,000 mPa·s.

[0091] When the curable silicone composition of the present invention contains a resinous organohydrogenpolysiloxane, there are no particular limitations on the amount thereof, but it is preferably contained in an amount of 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, based on the total mass of the curable silicone composition of the present invention, and can be contained in an amount of 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0092] The content of component (B) is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total mass of the curable silicone composition. In a preferred embodiment, component (B) is contained in an amount of 40% by mass or less, preferably 30% by mass or less, and more preferably 25% by mass or less, based on the total mass of the curable silicone composition.

[0093] Furthermore, in one embodiment of the present invention, component (B) is contained in an amount such that the ratio of silicon-bonded alkenyl groups to silicon-bonded hydrogen atoms contained in the organopolysiloxane component is 0.3 moles or more, preferably 0.5 moles or more, and more preferably 0.7 moles or more of silicon-bonded hydrogen atoms per mole of silicon-bonded alkenyl groups in the curable silicone composition; and, for example, the amount may be such that the number of silicon-bonded hydrogen atoms per mole of silicon-bonded alkenyl groups in the curable silicone composition is 5 moles or less, preferably 3 moles or less, more preferably 2 moles or less, even more preferably 1.5 moles or less, preferentially 1.2 moles or less, and particularly preferably 1.0 mole or less.

[0094] (C) Silica-titania composite oxide particles The silica-titania composite oxide particles of component (C) are composite particles composed of silica (SiO2) and titanium oxide (TiO2), and can impart thixotropy suitable for forming the curable silicone composition of the present invention into a desired shape, particularly a dome shape. The curable silicone composition of the present invention may contain one type of silica-titania composite oxide particles (C), or may contain two or more types of silica-titania composite oxide particles (C).

[0095] The average particle size of the primary particles of the silica-titania composite oxide particles of component (C) is not particularly limited, but is, for example, in the range of 10 to 500 nm, and preferably in the range of 10 to 200 nm. In this specification, the average particle size of the silica-titania composite oxide particles can be determined, for example, from the volumetric equivalent particle size distribution by image analysis such as SEM or TEM.

[0096] The specific surface area of ​​the silica-titania composite oxide particles of component (C) is not particularly limited, but is preferably 25 m 2 / g or more, more preferably 50m 2 / g or more, more preferably 75m 2 / g or more, and usually 300m 2 / g or less, preferably 200m 2 In this specification, the specific surface area of ​​the silica-titania composite oxide particles can be measured, for example, by the nitrogen adsorption BET one-point method.

[0097] The refractive index of the silica-titania composite oxide particles of component (C) is not particularly limited, but for example, the refractive index at 25°C and a wavelength of 589 nm (sodium D line) is 1.40 or more, preferably 1.43 or more, and more preferably 1.46 or more. Furthermore, it is usually 1.61 or less, preferably 1.58 or less, and more preferably 1.55 or less. The refractive index of the silica-titania composite oxide particles can be understood as being equal to the refractive index of the liquid with the highest transmittance at 589 nm when the silica-titania composite oxide particles are dispersed in liquids with different refractive indices.

[0098] The silica-titania composite oxide particles of component (C) are not particularly limited in terms of the composition ratio of silica component to titanium oxide component, but for example, the content of titanium component, calculated as titania (titanium oxide), is preferably 0.01 mol % or more, and is preferably 25 mol % or less, and more preferably 20 mol % or less. The content of titanium component can be measured, for example, by fluorescent X-ray analysis.

[0099] The average circularity of the silica-titania composite oxide particles of component (C) is not particularly limited, but is usually at least 0.80, and preferably at least 0.85. The average circularity can be determined, for example, by image analysis using SEM or TEM.

[0100] The crystalline form of the silica-titania composite oxide particles of component (C) is not particularly limited, but is preferably amorphous. In one embodiment, the silica-titania composite oxide particles of component (C) preferably have a crystalline phase ratio of 5 mass% or less. The crystalline phase ratio of the silica-titania composite oxide particles can be determined, for example, by XRD measurement.

[0101] The method for producing the silica-titania composite oxide particles of component (C) is not particularly limited and can be any method known in the art. Examples of methods for producing silica-titania composite oxide particles include the sol-gel method and the flame method. In the sol-gel method, a sol solution having a pH of 2 or less containing silicon and titanium alkoxides, a water-soluble polymer, an acid, and acetylacetone in a ratio of 40 to 200 mol % relative to the titanium is prepared. Phase separation involving spinodal decomposition of the sol solution produces a gel consisting of aggregates of spherical silica-titania composite oxide particles. The gel is then crushed and dried to produce the silica-titania composite oxide particles. In the flame method, silica-titania composite oxide particles can be produced by feeding a gaseous mixture of raw materials consisting of a silicon compound and a titanium compound into a flame and burning the mixture.

[0102] Examples of commercially available silica-titania composite oxide particles that can be used as component (C) of the present invention include Silfil (specific surface area: 100 to 200 g / m), a product of Tokuyama Corporation. 2 , refractive index 1.48, 1.51, or 1.53).

[0103] The silica-titania composite oxide particles of component (C) are contained in an amount of 3% by mass or more, based on the total mass of the curable silicone composition. The silica-titania composite oxide particles of component (C) are preferably contained in an amount of 4.5% by mass or more, and more preferably 6% by mass or more, based on the total mass of the curable silicone composition. In a preferred embodiment, component (C) is contained in an amount of 30% by mass or less, preferably 25% by mass or less, and more preferably 20% by mass or less, based on the total mass of the curable silicone composition.

[0104] (D) Curing catalyst The curing catalyst of component (D) is a hydrosilylation reaction curing catalyst that accelerates the curing of the curable silicone composition of the present invention. Examples of component (D) include platinum-based catalysts such as chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-olefin complexes, platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes, and platinum-supported powders; palladium-based catalysts such as tetrakis(triphenylphosphine)palladium, palladium black, and mixtures with triphenylphosphine; and rhodium-based catalysts, with platinum-based catalysts being particularly preferred.

[0105] The amount of component (D) blended is a catalytic amount. More specifically, when a platinum catalyst is used as component (D), the amount of platinum atoms, relative to the total mass of the curable silicone composition of the present invention, is preferably 0.01 ppm or more, more preferably 0.1 ppm or more, and even more preferably 1 ppm or more. Additionally, the amount of platinum atoms, relative to the total mass of the curable silicone composition of the present invention, is preferably 20 ppm or less, more preferably 15 ppm or less, even more preferably 10 ppm or less, and particularly preferably 5 ppm or less.

[0106] The curable silicone composition of the present invention can contain optional components as long as they do not impair the objectives of the present invention. Examples of optional components include acetylene compounds, organophosphorus compounds, vinyl group-containing siloxane compounds, inorganic fillers other than component (C), such as crushed quartz, silica, titanium oxide, magnesium carbonate, zinc oxide, iron oxide, and diatomaceous earth, inorganic fillers obtained by hydrophobizing the surface of such inorganic fillers with organosilicon compounds, hydrosilylation reaction inhibitors, organopolysiloxanes that do not contain silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups, tackifiers other than component (E-1), heat resistance agents, cold resistance agents, thermally conductive fillers, flame retardants, thixotropic agents, phosphors, and solvents. The amount of these optional components added is typically 0.001 to 20% by mass of the total composition.

[0107] Among the inorganic fillers, examples of silica include fumed silica, dry silica, wet silica, crystalline silica, precipitated silica, etc. The silica may be surface-hydrophobized with an organosilicon compound such as an organoalkoxysilane compound, an organochlorosilane compound, an organosilazane compound, or a low-molecular-weight siloxane compound, or a silane coupling agent, a titanate-based coupling agent, or the like.

[0108] The hydrosilylation reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the curable silicone composition. Examples of such curing reaction inhibitors include alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, and 1-ethynyl-1-cyclohexanol; ene-yne ​​compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; alkenyl-containing low-molecular-weight siloxanes such as tetramethyltetravinylcyclotetrasiloxane and tetramethyltetrahexenylcyclotetrasiloxane; and alkynyloxysilanes such as methyl-tris(1,1-dimethylpropynyloxy)silane and vinyl-tris(1,1-dimethylpropynyloxy)silane. Preferably, the hydrosilylation reaction inhibitor is selected from the alkyne alcohols, and particularly preferably 1-ethynyl-1-cyclohexanol. The amount of the reaction inhibitor added is usually 0.001 to 5% by mass of the entire composition.

[0109] Examples of phosphors include yellow-, red-, green-, and blue-emitting phosphors, such as oxide-based phosphors, oxynitride-based phosphors, nitride-based phosphors, sulfide-based phosphors, oxysulfide-based phosphors, and fluoride-based phosphors, which are widely used in light-emitting diodes (LEDs), as well as mixtures of at least two of these. Examples of oxide-based phosphors include yttrium-aluminum-garnet-based YAG-based green-to-yellow-emitting phosphors containing cerium ions, terbium-aluminum-garnet-based TAG-based yellow-to-yellow-emitting phosphors containing cerium ions, and silicate-based green-to-yellow-emitting phosphors containing cerium or europium ions. Examples of oxynitride-based phosphors include silicon-aluminum-oxygen-based sialon-based red-to-green-emitting phosphors containing europium ions. Examples of nitride-based phosphors include calcium-strontium-aluminum-silicon-based COZN-based red-to-yellow-emitting phosphors containing europium ions. Examples of sulfide-based phosphors include ZnS-based green-emitting phosphors containing copper ions or aluminum ions. Examples of oxysulfide-based phosphors include Y2O2S-based red-emitting phosphors containing europium ions. Examples of fluoride-based phosphors include KSF phosphors (K2SiF6:Mn 4+ ) etc.

[0110] There are no particular restrictions on the viscosity of the curable silicone composition of the present invention. For example, when viscosity is measured using a viscoelasticity measuring device at a measurement temperature of 25°C with a cone plate having a cone diameter of 40 mm and a cone angle of 2° at a shear speed of 10 / s, the viscosity is preferably 35 Pa·s or less, and more preferably 35 Pa·s or less. or 30 Pa·s or less.

[0111] The curable silicone composition according to the present invention has suitable thixotropy, making it excellent for forming predetermined shapes, particularly dome-shaped shapes. For example, when the viscosity of a curable silicone composition is measured using a viscoelasticity measuring device at a measurement temperature of 25°C, with a cone plate having a cone diameter of 40 mm and a cone angle of 2°, and rotated in the same direction at shear speeds of 1 / s and 10 / s, and the viscosity ratio (1 / s) / (10 / s) is taken as the thixotropic index, the value of this thixotropic index is preferably greater than 3.0, more preferably greater than 3.2, even more preferably greater than 3.3, and particularly preferably greater than 3.4.

[0112] The curable silicone composition of the present invention can be cured to form a cured product with good transparency. Specifically, the cured product of the curable silicone composition of the present invention preferably has a light transmittance of 90% or more, and more preferably 95% or more, at wavelengths of 400 nm to 700 nm. The light transmittance of the cured product of the curable silicone composition can be determined, for example, by measuring the cured product with an optical path length of 1 using a spectrophotometer.

[0113] The curable silicone composition of the present invention has a high refractive index. For example, the refractive index of the curable silicone composition of the present invention at 25°C and 589 nm, as measured using an Abbe refractometer, is preferably greater than 1.48, and more preferably 1.50 or greater.

[0114] The curable silicone composition of the present invention can be cured to form a cured product with high hardness. Preferably, the cured product obtained by curing the curable silicone composition of the present invention has a Type D durometer hardness of D50 or more at 25°C. This Type D durometer hardness is determined using a Type D durometer in accordance with JIS K 6253-1997 "Testing method for hardness of vulcanized rubber and thermoplastic rubber."

[0115] The curable silicone composition of the present invention can be prepared by mixing the various components. The method for mixing the various components can be any conventionally known method, and is not particularly limited; however, a uniform mixture can usually be obtained by simple stirring. Furthermore, when solid components such as inorganic fillers are included as optional components, mixing using a mixing device is more preferable. Such mixing devices are not particularly limited, and examples include single- or double-screw continuous mixers, twin-roll mixers, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneader mixers, and Henschel mixers.

[0116] [Sealing materials, films] The present invention also relates to an encapsulant for semiconductors that uses the curable silicone composition of the present invention. The shape of the encapsulant of the present invention is not particularly limited, but is preferably dome-shaped or sheet-shaped. The semiconductors that can be encapsulated with the encapsulant or film of the present invention are not particularly limited, and examples include semiconductors such as SiC and GaN, particularly power semiconductors or optical semiconductors such as light-emitting diodes.

[0117] The encapsulant of the present invention uses the curable silicone composition of the present invention, which exhibits excellent thixotropy, and therefore can be formed into an encapsulant of any desired shape, particularly a dome-shaped encapsulant, and can provide an encapsulant that has excellent hardness, refractive index, and transparency.

[0118] [Optical semiconductor element] The present invention also relates to an optical semiconductor element comprising the encapsulant of the present invention. Examples of optical semiconductor elements include light-emitting diodes (LEDs), semiconductor lasers, photodiodes, phototransistors, solid-state imaging devices, and light emitters and photodetectors for photocouplers, with light-emitting diodes (LEDs) being particularly preferred.

[0119] Light-emitting diodes (LEDs) emit light from the top, bottom, left, and right of the optical semiconductor element. Therefore, light-absorbing materials are not preferred for the components that make up the LED; rather, materials with high light transmittance or high reflectance are preferred. Therefore, the substrate on which the optical semiconductor element is mounted is also preferably made of a material with high light transmittance or high reflectance. Examples of substrates on which such optical semiconductor elements are mounted include conductive metals such as silver, gold, and copper; non-conductive metals such as aluminum and nickel; thermoplastic resins containing white pigments, such as PPA and LCP; thermosetting resins containing white pigments, such as epoxy resin, BT resin, polyimide resin, and silicone resin; and ceramics, such as alumina and alumina nitride.

[0120] The optical semiconductor element of the present invention is encapsulated with the encapsulant of the present invention, and therefore has excellent reliability and light extraction efficiency. [Example]

[0121] The curable silicone composition of the present invention will be described in more detail below with reference to the following examples and comparative examples.

[0122] Curable silicone compositions were prepared by mixing the components in the amounts (parts by mass) shown in the table. Hereinafter, Me represents a methyl group, Vi represents a vinyl group, Ph represents a phenyl group, and Ep represents a 3-glycidoxypropyl group. The structures of the organopolysiloxane components are shown in simplified form in the table, with the functional groups other than Me in the M, D, or T units indicated in parentheses. Furthermore, H / Vi represents the molar ratio of silicon-bonded hydrogen atoms (H) to vinyl groups (Vi) in the organopolysiloxane component. The amount of component d in the curing catalyst is shown in terms of the amount of platinum atoms (ppm).

[0123] (Component a: Alkenyl group-containing organopolysiloxane) Component a-1: Average unit formula (Me3SiO 1 / 2 )5(ViMe2SiO 1 / 2 ) 17 (MeSiO 3 / 2 ) 39 (PhSiO 3 / 2 )39 Resinous alkenyl-containing organopolysiloxane represented by the formula: Component a-2: Average unit formula (Me3SiO 1 / 2 ) 14 (ViMe2SiO 1 / 2 ) 11 (MeSiO 3 / 2 ) 53 (PhSiO 3 / 2 ) 22 Resinous alkenyl-containing organopolysiloxane represented by the formula: Component a-3: Average structural formula (ViMe2SiO 1 / 2 )3(PhSiO 3 / 2 ) a resin-like alkenyl-containing organopolysiloxane represented by the formula: Component a-4: Average structural formula ViMe2SiO(Ph2SiO) 20 Linear alkenyl-containing organopolysiloxane represented by SiMe2Vi Component a-5: Average structural formula ViMe2SiO(Me2SiO) 60 (Ph2SiO) 30 Linear alkenyl-containing organopolysiloxane represented by SiMe2Vi Component a-6: Average structural formula (ViMe2SiO 1 / 2 ) 25 (PhSiO 3 / 2 ) 75 Resinous alkenyl-containing organopolysiloxane represented by the formula: Component a-7: Average unit formula (ViMeSiO 2 / 2 ) Organopolysiloxane containing cyclic alkenyl groups represented by formula 4 Component a-8: Average unit formula (ViMe2SiO 1 / 2 ) 13 (EpMeSiO 2 / 2 ) 24 (PhSiO 3 / 2 ) 46 (OMe) 17 Epoxy group-containing resinous organopolysiloxane represented by the formula: (Component b: organohydrogenpolysiloxane) Component b-1: Linear organohydrogenpolysiloxane with the average structural formula HMe2SiO(Ph2SiO)SiMe2H Component b-2: Average unit formula (HMe2SiO 1 / 2 ) 60 (PhSiO 3 / 2 ) 40 Resin-like organohydrogenpolysiloxane represented by (Component c: Inorganic filler) Component c-1: Silica-titania composite oxide particles (manufactured by Tokuyama Corporation, product name: Silfil, specific surface area: 101 g / m 2 , refractive index 1.51) Component c-2: Silica-titania composite oxide particles (manufactured by Tokuyama Corporation, product name: Silfil, specific surface area: 101 g / m 2 , refractive index 1.53) Component c-3: Silica-titania composite oxide particles (manufactured by Tokuyama Corporation, product name: Silfil, specific surface area: 154 g / m 2 , refractive index 1.53) Component c'-1: fumed silica Component d: A complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with a platinum concentration of 4.0% by mass Component e: 1-ethynyl-2-cyclohexanol

[0124] The following evaluations were carried out, and the results are summarized in Table 1.

[0125] [Viscosity and Thixotropy Index] The viscosity of the curable silicone composition was measured using a viscoelasticity measuring device (MCR302 manufactured by Anton Paar) with a cone plate having a cone diameter of 40 mm and a cone angle of 2°, rotating in the same direction at shear speeds of 1 / s and 10 / s. The measurement temperature was standardized to 25°C. The thixotropic index was calculated as the viscosity ratio (1 / s) / (10 / s). The viscosity was measured at a shear speed of 10 / s.

[0126] [Refractive Index] The refractive index of the curable silicone composition at 25°C before curing was measured using an Abbe refractometer with a 589 nm light source.

[0127] [Hardness of cured product] The resulting curable silicone composition was cured at 150°C for 1 hour, and a 10 mm thick test specimen was prepared. The hardness at 25°C was measured using a Durometer D hardness tester.

[0128] [Light transmittance of cured product] The resulting curable silicone composition was placed between two transparent glass plates and cured by heating at 150°C for 1 hour to prepare a test specimen with an optical path length of 1 mm. The light transmittance of this test specimen was measured at 25°C using a recording spectrophotometer capable of measuring at any wavelength in the visible light range (wavelengths of 400 nm to 700 nm). Table 3 lists the light transmittance value at a wavelength of 450 nm.

[0129] [Table 1]

[0130] As can be seen from the results in Table 1 above, the curable silicone composition of the present invention not only exhibits excellent thixotropy, but is also capable of forming a cured product with a high refractive index, hardness, and transparency. [Industrial Applicability]

[0131] The curable silicone composition of the present invention has excellent thixotropy and can be formed into a cured product of the desired shape. Furthermore, the resulting cured product has excellent refractive index, hardness, and transparency, making it extremely useful, for example, as a dome- or sheet-shaped encapsulant when manufacturing semiconductor packages.

Claims

1. (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule; (C) silica-titania composite oxide particles having a refractive index of 1.40 or more and 1.58 or less at 25°C and a wavelength of 589 nm, in an amount of 3% by mass or more and 20% by mass or less, based on the total mass of the composition; and (D) Curing catalyst A curable silicone composition for use in an encapsulant for an optical semiconductor, comprising: the silicone composition is liquid; The viscosity of the silicone composition was measured at a temperature of 25°C using a cone plate having a cone diameter of 40 mm and a cone angle of 2°, with shear speeds of 1 / s and 10 / s rotating in the same direction. The viscosity ratio (1 / s) / (10 / s) was greater than 3.

0. A curable silicone composition.

2. The specific surface area of ​​the (C) silica-titania composite oxide particles is 50 m ２ / g or more 300m ２ 2. The curable silicone composition of claim 1, wherein the viscosity is 1000 kJ / g or less.

3. 3. The curable silicone composition according to claim 1, wherein the alkenyl group-containing organopolysiloxane (A) comprises a resinous organopolysiloxane, a linear organopolysiloxane, or both, in which the amount of aryl groups accounts for 20 mol % or more and 70 mol % or less of all silicon-bonded functional groups.

4. A sealant obtained by curing the curable silicone composition according to any one of claims 1 to 3.

5. An optical semiconductor device comprising the encapsulant according to claim 4 .

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