Curable silicone composition, encapsulant and optical semiconductor device

Abstract

This invention provides a curable silicone composition that exhibits high thixotropy and can form a cured product with excellent refractive index and transparency. The aforementioned problems are addressed by a curable silicone composition comprising the following components: (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule; (B) an organohydrogen-containing organopolysiloxane having at least two hydrogen atoms bonded to silicon atoms per molecule; (C) silicon dioxide-titanium oxide composite oxide particles comprising at least 3% by mass relative to the total mass of the composition; and (D) a curing catalyst.

Description

Technical Field

[0001] This invention relates to a curable silicone composition, and more specifically, to a curable silicone composition suitable for use as a sealing material in optoelectronic semiconductors. Furthermore, this invention also relates to an optoelectronic semiconductor device sealed by a sealing material composed of a cured product of such a curable silicone composition. Prior Technology

[0002] Curable silicone compositions undergo curing to form a cured product with excellent heat resistance, cold resistance, electrical insulation, weather resistance, water repellency, and transparency, thus finding wide application in various industries. In particular, compared to other organic materials, this cured product is less prone to discoloration and exhibits less degradation in physical properties such as durability. Therefore, it is widely used as an optical material, especially as a silicone sealing material in light-emitting diodes (LEDs) and other optical semiconductor devices.

[0003] In recent years, in order to achieve higher light extraction efficiency, the organic silicon sealing materials used in light semiconductor devices such as light-emitting diodes (LEDs) have been required to have higher transparency and higher refractive index.

[0004] For example, Patent Document 1 describes a hydrogenated silanization reaction-cured organic polysiloxane composition, characterized by comprising the following components: (A) a methylphenylenyl polysiloxane in which diphenylsiloxane units comprise 5 mol% or less of the total siloxane units, at least 20 mol% of all organic groups bonded to silicon atoms in the molecule are phenyl, and each molecule has at least two alkenyl groups bonded to silicon atoms; (B) a methylphenyl hydrogenated polysiloxane in which diphenylsiloxane units comprise 5 mol% or less of the total siloxane units, at least 20 mol% of all organic groups bonded to silicon atoms in the molecule are phenyl, and each molecule has at least two hydrogen atoms bonded to silicon atoms; and (C) a hydrogenated silanization reaction catalyst; wherein, in this composition, the diphenylsiloxane units comprise 5 mol% or less of the total siloxane units.

[0005] Furthermore, Patent Document 2 describes a silicone resin composition that covers the light-transmitting surface of a light-emitting diode and contains: a linear organic polysiloxane component represented by general formula (I); and an average composition of the following formula (2): HC(R4)dSiO(4-cd) / 2 (2) (where R4 is independently an unsubstituted or halogenated monovalent hydrocarbon group without aliphatic unsaturated bonds, and c and d are given by the following conditions: 0.001 ≤ c < 2, 0.7 ≤ d ≤ 2 and 0.8 ≤ c + d ≤ 2). The formula represents an organohydrogen polysiloxane component having two or more SiH groups in one molecule; and a variety of liquid components containing a platinum group metal catalyst; wherein the proportion of organosiloxanes with a molecular weight of less than 1,000 in the linear organosiloxane component is less than 10%, the content of organosiloxanes with a molecular weight of less than 1,000 is less than 10%, and a cured product with a Shore 00 hardness of less than 85 is provided.

[0006] Furthermore, Patent Document 3 describes a curable organopolysiloxane composition comprising at least the following components: (A) a branched organopolysiloxane having at least three alkenyl groups in a molecule, all of which are aryl groups, with at least 30 mol% of the organic groups bonded to silicon atoms; (B) a linear organopolysiloxane having aryl groups and its molecular chain capped at both ends by diorganohydrosilaneoxy groups {relative to the 1 mol alkenyl group in component (A), the hydrogen groups bonded to silicon atoms in this component}. (Amount of 0.5-2 moles); (C) A branched organic polysiloxane having at least three diorganohydrosiloxane groups bonded to silicon atoms in a molecule, of which at least 15 moles are aryl groups {the amount of diorganohydrosiloxanes in this component is 1-20 moles relative to the total amount of diorganohydrosiloxanes contained in component (B) above and in this component}; and (D) A catalyst for hydrogenation silylation reaction (amount to promote the curing of this composition).

[0007] Furthermore, Patent Document 4 describes a curable composition comprising: (A) an organopolysiloxane having the average composition of the following Formula 1; (B) an organopolysiloxane comprising an alkenyl group, an epoxy group, and an aryl group: [Formula 1] (R1R22SiO1 / 2) a(R3R4SiO2 / 2) b(R5SiO3 / 2) c(SiO2) d(In the above Formula 1, R1 is a monovalent hydrocarbon group with 2 or more carbon atoms, R2 is an alkyl group with 1-4 carbon atoms, R3 and R4 are independently alkyl groups with 1-20 carbon atoms, alkenyl groups with 2-20 carbon atoms, or aryl groups with 6-25 carbon atoms, respectively, R5 is an alkyl group with 1-20 carbon atoms or an aryl group with 6-25 carbon atoms, R1, R3 and R At least one of the four groups 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, existing curable silicone compositions have the following problems: due to insufficient thixotropy, even when applied directly and in appropriate amounts to the optoelectronic semiconductor on the support substrate using a dispensing machine and then cured, the applied curable silicone composition still flows, sometimes failing to obtain a cured product with the desired shape. Furthermore, when adding particles such as silicon dioxide to improve thixotropy, there is a possibility of reduced transparency of the resulting cured product. [Previous Technical Documents] [Patent Literature]

[0009] Patent Document 1: Japanese Patent Publication No. 2012-507582 Patent Document 2: Japanese Patent Application Publication No. 2014-159586 Patent Document 3: Japanese Patent Application Publication No. 2010-1336 Patent Document 4: Japanese Patent Application Publication No. 2015-507025 Summary of the Invention

[0010] [The technical problem that the invention aims to solve]

[0011] The purpose of this invention is to provide a curable silicone composition that can form a cured product with high thixotropy, refractive index and hardness, and exhibits excellent transparency.

[0012] Another object of the present invention is to provide a sealing material comprising the curable silicone composition of the present invention. Furthermore, yet another object of the present invention is to provide an optical semiconductor device sealed by the sealing material of the present invention. [Technical means used to solve the problem]

[0013] To address the aforementioned issues, the inventors conducted in-depth research and surprisingly discovered that by using a specific amount of silicon dioxide-titanium oxide composite oxide particles as fillers, the cured silicone composition exhibits excellent thixotropic properties suitable for forming the desired shape, and can form cured products with excellent refractive index, hardness, and transparency, thereby completing the present invention.

[0014] Therefore, the present invention relates to a curable silicone composition comprising: (A) Alkenyl-containing organopolysiloxanes, each molecule having at least two alkenyl groups; (B) Organohydrogen polysiloxanes, each molecule having at least two hydrogen atoms bonded to silicon atoms; (C) Silicon dioxide-titanium oxide composite oxide particles comprising more than 3% by mass relative to the total mass of the composition; and (D) Curing catalyst.

[0015] Preferably, the specific surface area of ​​(C) silicon dioxide-titanium oxide composite oxide particles is above 50 m² / g.

[0016] Preferably, the refractive index of the (C) silicon dioxide-titanium oxide composite oxide particles is above 1.40 at 25°C and a wavelength of 589 nm.

[0017] The curable silicone composition of the present invention preferably has a refractive index of 1.50 or higher at 25°C and a wavelength of 589 nm.

[0018] Preferably, (A) is a resinous organopolysiloxane containing alkenyl organopolysiloxane in which the amount of aryl groups among all functional groups bonded to silicon atoms is 20 moles or more, a linear organopolysiloxane, or both.

[0019] The curable silicone composition of the present invention preferably has a viscosity of less than 30 Pa·s at 25°C.

[0020] The present invention also relates to a sealing material composed of the curable silicone composition of the present invention.

[0021] The present invention also relates to an optical semiconductor device comprising the sealing material of the present invention. [Invention Effects]

[0022] According to the curable silicone composition of the present invention, a curable silicone composition can be provided that is capable of maintaining thixotropy suitable for forming the desired shape during application, while being capable of forming a cured product with excellent transparency, hardness, and refractive index. Simple Explanation of the Diagram

[0023] none Implementation

[0024] [Curing silicone composition] The curable silicone composition of the present invention comprises at least: (A) Alkenyl-containing organopolysiloxanes, each molecule having at least two alkenyl groups; (B) Organohydrogen polysiloxanes, each molecule having at least two hydrogen atoms bonded to silicon atoms; (C) Silicon dioxide-titanium oxide composite oxide particles comprising more than 3% by mass relative to the total mass of the composition; and (D) Curing catalyst.

[0025] The components of the cured silicone composition of the present invention will now be described in detail.

[0026] (A) Alkenyl-containing organopolysiloxanes having at least two alkenyl groups per molecule (A) is the main component of this composition and is a curable organopolysiloxane having at least two alkenyl groups in one molecule. The curable silicone composition of the present invention may contain one (A) alkenyl-containing organopolysiloxane or two or more (A) alkenyl-containing organopolysiloxanes.

[0027] Examples of molecular structures for component (A) include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures. Component (A) may also be one organopolysiloxane having such molecular structures, or a mixture of two or more organopolysiloxanes having such molecular structures. Preferably, the curable silicone composition of the present invention comprises both a linear alkenyl organopolysiloxane and a resinous alkenyl organopolysiloxane as component (A). In this specification, resinous refers to a molecular structure having a branched or three-dimensional network structure.

[0028] Examples of alkenyl groups included in component (A) include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, etc., alkenyl groups with 2 to 12 carbons, with vinyl being preferred.

[0029] As a group bonded to silicon atoms, other than an alkenyl group, included in component (A) may be a halogenated or unsubstituted monovalent hydrocarbon group, such as: alkyl groups with 1-12 carbon atoms, including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tributyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups with 6-20 carbon atoms, including phenyl, tolyl, xylyl, and naphthyl; aralkyl groups with 7-20 carbon atoms, including benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups are substituted by halogen atoms such as fluorine, chlorine, or bromine atoms. Furthermore, without prejudice to the purpose of this invention, a small amount of hydroxyl or alkoxy groups such as methoxy or ethoxy may be present on the silicon atoms in component (A). (A) The groups that bond to silicon atoms, other than alkenyl groups, are preferably selected from alkyl groups having 1 to 6 carbon atoms, especially methyl groups, aryl groups having 6 to 20 carbon atoms, especially phenyl groups.

[0030] In one embodiment of the present invention, component (A) may comprise a resinous alkenyl-containing organopolysiloxane as component (A-1). The resinous alkenyl-containing organopolysiloxane (A-1) is preferably represented by the following average unit formula (I): Average unit cell (I): (R 1 3SiO 1 / 2) a(R 1 2SiO 2 / 2) b(R 1SiO 3 / 2) c(SiO 4 / 2) d(XO 1 / 2) e (In formula (I), R1 refers to the same or different halogenated or unsubstituted monovalent hydrocarbon groups, wherein in one molecule, at least two R1 are alkenyl groups, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 0.9, 0 ≤ d < 0.5, 0 ≤ e < 0.4, a + b + c + d = 1.0, and c + d > 0).

[0031] Examples of halogenated or unsubstituted monovalent hydrocarbon groups as R1 in formula (I) above include: alkyl groups with 1-12 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tributyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups with 6-20 carbon atoms such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups with 7-20 carbon atoms such as benzyl, phenethyl, and phenylpropyl; alkenyl groups with 2-12 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 are substituted by halogen atoms such as fluorine, chlorine, or bromine. Within the scope of this invention, R1 may be a small amount of hydroxyl or alkoxy such as methoxy or ethoxy. R1 is preferably selected from alkyl groups having 1-6 carbon atoms, especially methyl, alkenyl groups having 2-6 carbon atoms, especially vinyl, or aryl groups having 6-20 carbon atoms, especially phenyl.

[0032] In formula (I) above, X is a hydrogen atom or an alkyl group. Preferably, X is an alkyl group having 1 to 3 carbon atoms, specifically methyl, ethyl and propyl.

[0033] In equation (I) above, 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 equation (I) above, 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 equation (I) above, 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 equation (I) above, 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 especially in the range of 0 ≤ e ≤ 0.05.

[0034] In a preferred embodiment of the present invention, in formula (I) above, c is greater than 0, that is, the resinous alkenyl organopolysiloxane of component (A-1) comprises a siloxane unit (T unit) represented by SiO 3 / 2. The resinous organopolysiloxane of component (A-1) may or may not contain a siloxane unit (Q unit) represented by SiO 4 / 2, but preferably does not contain it.

[0035] In a preferred embodiment of the present invention, the resinous alkenyl-containing organopolysiloxane of component (A-1) contains an alkenyl group at the molecule end. Preferably, the resinous organopolysiloxane of component (A-1) has an alkenyl group on the siloxane unit (M unit) represented by SiO 1 / 2, and may or may not contain an alkenyl group on the molecular chain side chains (i.e., the siloxane unit (D unit) represented by SiO 2 / 2 and the siloxane unit (T unit) represented by SiO 3 / 2), but preferably does not contain an alkenyl group.

[0036] The content of alkenyl groups in the resinous alkenyl-containing organopolysiloxane of component (A-1) is not particularly limited. For example, it can be 3 mol% or more of the total amount of organic groups bonded to silicon atoms, preferably 5 mol% or more, more preferably 8 mol% or more, and can be 40 mol% or less of the total amount of organic groups bonded to silicon atoms, preferably 30 mol% or less, more preferably 20 mol% or less. In addition, the content of alkenyl groups can be determined by analytical methods such as Fourier Transform Infrared Spectrometer (FT-IR), Nuclear Magnetic Resonance (NMR), or the titration method described below.

[0037] A method for quantifying the amount of alkenyl groups in each component by titration is described. The alkenyl group content in organopolysiloxane components can be quantified with high precision using the well-known Widmanstätten titration method. The principle is as follows. First, as shown in formula (1), the alkenyl groups in the organopolysiloxane raw material undergo an addition reaction with iodine monochloride. Next, by the reaction shown in formula (2), excess iodine monochloride reacts with potassium iodide to release iodine. Then, the released iodine is titrated with sodium thiosulfate solution. Equation (1) CH₂=CH⁻ + 2ICl → CH₂I⁻CHCl⁻ + ICl (excess) Equation (2) ICl + KI → I²⁺ KCl The amount of alkenyl groups in the component can be quantified by the difference between the amount of sodium thiosulfate required for titration and the titration amount of a separately prepared blank solution.

[0038] In a preferred embodiment of the present invention, the resinous alkenyl organopolysiloxane of component (A-1) contains aryl groups in the organic groups bonded to silicon atoms. That is, in the above formula (I), at least one R1 may be an aryl group. In a preferred embodiment of the present invention, the resinous alkenyl organopolysiloxane of component (A-1) contains aryl groups bonded to silicon atoms in the side chains of the molecular chain, i.e., D units and / or T units, and particularly preferably only in the T units. The resinous alkenyl organopolysiloxane of component (A-1) may or may not contain aryl groups at the molecular ends, i.e., M units, but preferably not. In addition, aryl groups with 6-20 carbon atoms can be listed as aryl groups, especially phenyl, tolyl, xylyl, and naphthyl.

[0039] When the resinous organopolysiloxane of component (A-1) contains aryl groups, its content (the percentage of aryl groups in all functional groups bonded to silicon atoms in the resinous organopolysiloxane, in moles%) can be designed as needed. Typically, it can be 5 moles or more, preferably 10 moles or more, more preferably 15 moles or more, further preferably 20 moles or more, particularly preferably 25 moles or more, and typically 70 moles or less, preferably 60 moles or less, and more preferably 55 moles or less. Furthermore, the aryl content can be determined by analysis using methods such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR).

[0040] The organopolysiloxane of component (A-1) is preferably solid or semi-solid at 25°C. The number of organopolysiloxanes of component (A-1) is not particularly limited in terms of average molecular weight, and can be in the range of 500-10,000.

[0041] When component (A) contains one or more (A-1) resinous organopolysiloxanes, their content is not particularly limited. Based on the total mass of the cured silicone composition of the present invention, it is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and particularly preferably 50% by mass or more. Furthermore, based on the total mass of all organopolysiloxane components, the content of component (A-1) is preferably 90% by mass or less, more preferably 80% by mass or less, further preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0042] In one embodiment of the present invention, when two (A-1) resinous alkenyl organopolysiloxanes are included, a resinous alkenyl organopolysiloxane monomer consisting of only one T unit may be included as a second (A-1) component. The content of this second (A-1) component is not particularly limited, but based on the total mass of the cured silicone composition of the present invention, it is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 3% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass or less, and further preferably 5% by mass or less.

[0043] Component (A) may also include a linear alkenyl-containing organopolysiloxane as component (A-2). The linear alkenyl-containing organopolysiloxane of component (A-2) is preferably represented by the following average structural formula (II): Average structural formula (II): R₂₃SiO(R₂₂SiO₂ / 2)mSiR₂₃ (In formula (II), R2 is the same or different halogenated or unsubstituted monovalent hydrocarbon group, wherein, in one molecule, at least two R2 are alkenyl groups, and m is 1-500).

[0044] In formula (II) above, the halogenated or unsubstituted monovalent hydrocarbon group of R2 can be the same group as in formula (I) above.

[0045] In the above formula (II), m is preferably 2-300, more preferably 5-200, even more preferably 10-100, and particularly preferably 15-50.

[0046] Examples of this (A-2) component include dimethyl polysiloxanes whose molecular chains are capped at both ends by dimethylvinylsiloxy groups, dimethyl polysiloxanes whose molecular chains are capped at both ends by diphenylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers whose molecular chains are capped at both ends by dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane copolymers whose molecular chains are capped at both ends by dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers whose molecular chains are capped at both ends by diphenylvinylsiloxy groups, and dimethylsiloxane-methylvinylsiloxane copolymers whose molecular chains are capped at both ends by dimethylvinylsiloxy groups. The following are listed: a dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymer with both ends capped by dimethylvinylsiloxy; a dimethylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymer with both ends capped by dimethylvinylsiloxy; a methylvinylpolysiloxane with both ends capped by trimethylsiloxy; a methylvinylsiloxane-methylphenylsiloxane copolymer with both ends capped by trimethylsiloxy; a methylvinylsiloxane-diphenylsiloxane copolymer with both ends capped by trimethylsiloxy; and a dimethylsiloxane-methylvinylsiloxane copolymer with both ends capped by trimethylsiloxy.

[0047] In a preferred embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) can be a linear organopolysiloxane with alkenyl groups at both ends of the molecular chain, or with the ends of the molecular chain capped by alkenyl groups. The linear organopolysiloxane of component (A-2) may or may not contain alkenyl groups on the side chains (i.e., D units) of the molecular chain, but preferably does not contain alkenyl groups.

[0048] The content of alkenyl groups in the linear organopolysiloxane of component (A-2) (the percentage of alkenyl groups in all functional groups bonded to silicon atoms in the linear organopolysiloxane, in moles%) can be designed as needed. Typically, it can be 1 mole% or more, preferably 2 moles or more, further preferably 3 moles or more, and can be 20 moles or less, preferably 15 moles or less, even more preferably 10 moles or less, and most preferably 7 moles or less. Furthermore, the content of alkenyl groups can be determined by analysis, for example, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and the titration method described above.

[0049] In one embodiment of the present invention, the linear organopolysiloxane of component (A-2) contains an aryl group in the organic group bonded to the silicon atom. That is, in formula (II) above, at least one R2 may be an aryl group. In a preferred embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) contains an aryl group bonded to the silicon atom on the side chain of the molecular chain. The linear organopolysiloxane of component (A-2) may or may not contain an aryl group at the end of the molecular chain (i.e., the M unit), but preferably it does not.

[0050] When the linear organopolysiloxane of component (A-2) contains aryl groups, its content (the percentage of aryl groups in all functional groups bonded to silicon atoms in the linear organopolysiloxane, in moles%) can be designed as needed. Typically, it can be 15 moles or more, preferably 25 moles or more, more preferably 30 moles or more, further preferably 35 moles or more, and can be 75 moles or less, preferably 65 moles or less, more preferably 60 moles or less, preferably 55 moles or less, and particularly preferably 50 moles or less. Furthermore, the content of aryl groups can be determined by analysis such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR).

[0051] When component (A) contains linear organopolysiloxane (A-2), its content is not particularly limited. Based on the total mass of the cured silicone composition of the present invention, it is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more. Furthermore, based on the total mass of the cured silicone composition of the present invention, the content of component (A-2) is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

[0052] In a preferred embodiment, component (A) comprises an alkenyl organopolysiloxane in which the functional groups bonded to silicon atoms contain a majority of aryl groups. Specifically, it comprises a (A-1) resinous organopolysiloxane, (A-2) linear organopolysiloxane, or both of the above, in which the amount of aryl groups in all functional groups bonded to silicon atoms is 20 mol% or more, preferably 25 mol% or more.

[0053] Other alkenyl organopolysiloxane components The curable silicone composition of the present invention may also include (A-3) epoxy-containing organic polysiloxane and / or (A-4) cyclic organic polysiloxane as other organic polysiloxane components.

[0054] Examples of the molecular structure of (A-3) epoxy-containing organopolysiloxanes include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures, with epoxy-containing resinous organopolysiloxanes being more preferred. The curable silicone composition of the present invention may contain one epoxy-containing organopolysiloxane or a combination of two or more epoxy-containing organopolysiloxanes.

[0055] Preferred epoxy-containing resinous organopolysiloxanes are represented by the following average unit formula (IV): (R₄₃SiO₂¹ / ²)f(R₅₂SiO₂² / ²)g(R₄SiO₂³ / ²)h(SiO₄₂²)i(XO¹ / ²)j {In formula (IV), R4 is independently a halogenated or unsubstituted monovalent hydrocarbon group, wherein at least two R4 are alkenyl groups, R5 is independently a halogenated or unsubstituted monovalent hydrocarbon group or an epoxy-containing organic group, wherein at least one R5 is an epoxy-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, 0 < j < 0.5, f + g + h + i + j = 1.0, h + i > 0, and j / (f + g + h + i + j) > 0.05}.

[0056] In formula (IV) above, examples of alkyl groups with 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tributyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups with 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; alkenyl groups with 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 are replaced by halogen atoms such as fluorine, chlorine, or bromine atoms. R4 is preferably selected from alkyl groups having 1-6 carbon atoms, especially methyl groups, alkenyl groups having 2-6 carbon atoms, especially vinyl groups, aryl groups having 6-20 carbon atoms, especially phenyl groups.

[0057] In (IV) above, examples of the epoxy-containing organic group as R5 include: 2-epoxypropoxyethyl, 3-epoxypropoxypropyl, 4-epoxypropoxybutyl, etc., epoxypropoxyalkyl groups; 2-(3,4-epoxycyclohexyl)-ethyl, 3-(3,4-epoxycyclohexyl)-propyl, etc., epoxycycloalkyl groups; 3,4-epoxybutyl, 7,8-epoxyoctyl, etc., epoxyalkyl groups; preferably epoxypropoxyalkyl groups, particularly preferably 3-epoxypropoxypropyl. R5 is preferably selected from alkyl groups having 1-6 carbon atoms, especially methyl, alkenyl groups having 2-6 carbon atoms, especially vinyl, aryl groups having 6-20 carbon atoms, especially phenyl, and 3-epoxypropoxypropyl. R5 is preferably selected from alkyl groups having 1-6 carbon atoms, especially methyl, and 3-epoxypropoxypropyl.

[0058] In formula (IV) above, X is a hydrogen atom or an alkyl group. Preferably, X is an alkyl group having 1 to 3 carbon atoms, specifically methyl, ethyl and propyl.

[0059] In equation (IV) above, with f + g + h + i + j = 1.0 as the baseline, f is preferably in the range of 0.03 ≤ f ≤ 0.7, more preferably in the range of 0.06 ≤ f ≤ 0.5, and even more preferably in the range of 0.09 ≤ f ≤ 0.3. In equation (IV) above, g is preferably in the range of 0.05 ≤ g ≤ 0.6, more preferably in the range of 0.1 ≤ g ≤ 0.4, and particularly in the range of 0.2 ≤ g ≤ 0.3. In equation (IV) above, h is preferably in the range of 0.1 ≤ h ≤ 0.8, more preferably in the range of 0.25 ≤ h ≤ 0.7, and particularly in the range of 0.4 ≤ h ≤ 0.6. In equation (IV) above, i is preferably in the range of 0 ≤ i ≤ 0.4, more preferably in the range of 0 ≤ i ≤ 0.25, and especially in the range of 0 ≤ i ≤ 0.1. In equation (IV) above, j is preferably in the range of 0.05 ≤ j ≤ 0.4, more preferably in the range of 0.1 ≤ j ≤ 0.3, and especially in the range of 0.15 ≤ j ≤ 0.25.

[0060] In one embodiment, in equation (IV) above, 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 generally less than 0.5, preferably less than 0.4, even more preferably less than 0.3, and particularly preferably less than 0.25.

[0061] In a preferred embodiment of the present invention, in formula (IV) above, h is greater than 0, that is, the epoxy-containing resinous organopolysiloxane comprises a silicate unit (T unit) represented by SiO3 / 2. The epoxy-containing resinous organopolysiloxane of component (C) may or may not contain a silicate unit (Q unit) represented by SiO4 / 2, but preferably does not.

[0062] In a preferred embodiment of the present invention, the epoxy-containing organopolysiloxane contains an alkenyl group at the molecule's end. Preferably, the epoxy-containing organopolysiloxane has an alkenyl group on the siloxane unit (M unit) represented by SiO₂ 1 / 2, and may or may not contain an alkenyl group on the molecular side chains (i.e., the siloxane unit (D unit) represented by SiO₂ 2 / 2 and the siloxane unit (T unit) represented by SiO₃ 3 / 2), but preferably does not contain an alkenyl group.

[0063] In a preferred embodiment, the amount of alkenyl groups in all organic groups bonded to silicon atoms in the epoxy-containing organopolysiloxane is not particularly limited, but is preferably 1 mol% or more, more preferably 3 mol% or more, further preferably 5 mol% or more, particularly preferably 7 mol% or more, and for example, may be 30 mol% or less, preferably 20 mol% or less, and more preferably 15 mol% or less.

[0064] In a preferred embodiment of the present invention, the epoxy-containing resinous organopolysiloxane contains an aryl group in the organic group bonded to the silicon atom. That is, in formula (IV) above, at least one of R4 and R5 may be an aryl group. In a preferred embodiment of the present invention, the epoxy-containing resinous organopolysiloxane contains an aryl group bonded to the silicon atom in the molecular side chain, i.e., the D unit or the T unit, preferably the T unit. The epoxy-containing resinous organopolysiloxane may or may not contain an aryl group at the molecular terminal, i.e., the M unit, but preferably it does not contain one. In addition, aryl groups with 6-20 carbon atoms can be listed as examples, especially phenyl, tolyl, xylyl, and naphthyl.

[0065] When the epoxy-containing organopolysiloxane contains aryl groups, its content (the percentage of aryl groups in all functional groups bonded to silicon atoms in the epoxy-containing organopolysiloxane in moles) can be designed as needed. Preferably, it is 15 moles, more preferably 20 moles or more, further preferably 25 moles or more, particularly preferably 30 moles or more, and preferably 70 moles or less, more preferably 60 moles or less, further preferably 50 moles or less, and particularly preferably 40 moles or less.

[0066] The amount of epoxy-containing organic groups in the total organic groups bonded to silicon atoms in the epoxy-containing organopolysiloxane is not particularly limited, but preferably 1 mol% or more, more preferably 5 mol% or more, further preferably 10 mol% or more, particularly preferably 15 mol% or more, and, for example, 40 mol% or less, preferably 30 mol% or less, and even more preferably 25 mol% or less. Furthermore, the amount of epoxy-containing organic groups can be determined by analysis such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR).

[0067] In a preferred embodiment of the present invention, the epoxy-containing organopolysiloxane contains hydroxyl and / or alkoxy groups as organic groups bonded to silicon atoms. The amount of hydroxyl and / or alkoxy groups among all organic groups bonded to silicon atoms in the epoxy-containing organopolysiloxane is not particularly limited, but preferably 2 mol% or more, more preferably 5 mol% or more, further preferably 10 mol% or more, and, for example, 30 mol% or less, preferably 20 mol% or less, and more preferably 15 mol% or less. Furthermore, the amount of hydroxyl and / or alkoxy groups can be determined using, for example, Fourier transform infrared spectrophotometry (FT-IR) or nuclear magnetic resonance (NMR).

[0068] The viscosity of the epoxy-containing resin-like organopolysiloxane is not particularly limited, for example, in the range of 50 mPa·s to 20000 mPa·s at 25°C, preferably in the range of 50 mPa·s to 3000 mPa·s. In this specification, the viscosity of the organopolysiloxane component can be determined at 25°C using a rotational viscometer according to JIS K7117-1.

[0069] The content of epoxy-containing organopolysiloxanes, particularly epoxy-containing resinous organopolysiloxanes, is not particularly limited. Based on the total mass of the cured silicone composition of the present invention, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more. Furthermore, based on the total mass of the cured silicone composition of the present invention, it is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 5% by mass or less, and particularly preferably 4% by mass or less.

[0070] The cyclic organopolysiloxane of component (A-4) is preferably represented by the following average structural formula (V): Average structural formula (V): (R 6 2SiO) n (In formula (V), R6 is the same or different halogenated or unsubstituted monovalent hydrocarbon group, wherein, in one molecule, at least two R6 are alkenyl groups, and n is a number of molecules with a viscosity of less than 1000 mPa·s at 25°C).

[0071] In the above formula (V), the halogenated or unsubstituted monovalent hydrocarbon group of R6 can be the same group as R1 in the above formula (I).

[0072] In the above formula (V), n is a number representing a viscosity of 1000 mPa·s or less at 25°C, for example, 4-15, preferably 4-10, and even more preferably 4-8. Furthermore, in this specification, the viscosity of the organopolysiloxane component can be measured at 25°C using a rotational viscometer according to JIS K7117-1.

[0073] In one embodiment, the content of alkenyl groups in the cyclic alkenyl-containing organopolysiloxane of component (A-4) (the percentage of alkenyl groups in all functional groups bonded to silicon atoms in the cyclic organopolysiloxane, in moles%) can be designed as needed, typically 10 moles or more, preferably 20 moles or more, more preferably 30 moles or more, even more preferably 40 moles or more, preferably 45 moles or more, and can be 80 moles or less, preferably 70 moles or less, more preferably 60 moles or less, and preferably 55 moles or less. Furthermore, the content of alkenyl groups can be determined by analysis, for example, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and the above-mentioned titration method.

[0074] The content of cyclic organopolysiloxane is not particularly limited, but based on the total mass of the curable silicone composition of the present invention, it is 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 0.15% by mass or more. Furthermore, based on the total mass of the curable silicone composition of the present invention, the content of cyclic organopolysiloxane is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and particularly preferably 1% by mass or less.

[0075] The total content of component (A) is not particularly limited, but based on the total mass of the cured silicone composition, it is preferably 40% by mass or more, more preferably 45% by mass or more, further preferably 50% by mass or more, and particularly preferably 55% by mass or more. In a preferred embodiment, based on the total mass of the cured silicone composition, the content of component (A) can be 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less.

[0076] (B) Organohydrogen-based polysiloxanes, each molecule having at least two hydrogen atoms bonded to silicon atoms. Component (B) functions as a crosslinking agent in the cured silicone composition through a hydrogenation silanization curing reaction, and is an organohydrogen polysiloxane with at least two hydrogen atoms bonded to silicon atoms per molecule. The cured silicone composition of the present invention may contain one (B) organohydrogen polysiloxane or two or more (B) organohydrogen polysiloxanes.

[0077] Examples of molecular structures for component (B) include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures. Component (B) may also be a single organohydrogen polysiloxane having such molecular structures, or a mixture of two or more organohydrogen polysiloxanes having such molecular structures. Preferably, the curable silicone composition of the present invention comprises both linear organohydrogen polysiloxane and resinous organohydrogen polysiloxane as component (B).

[0078] As part of component (B), groups bonded to silicon atoms, excluding hydrogen atoms, can include halogenated or unsubstituted monovalent hydrocarbon groups other than alkenyl groups. Examples include: alkyl groups with 1-12 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tributyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups with 6-20 carbon atoms such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups with 7-20 carbon atoms such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, chlorine, or bromine atoms. Furthermore, without hindering the purpose of this invention, a small amount of hydroxyl or alkoxy groups such as methoxy or ethoxy may be present on the silicon atoms in component (B). (B) The groups bonded to silicon atoms, other than hydrogen atoms, of the component are preferably selected from alkyl groups having 1-6 carbon atoms, especially methyl groups, and aryl groups having 6-20 carbon atoms, especially phenyl groups.

[0079] In one embodiment of the present invention, component (B) may also comprise a linear organohydrogen polysiloxane as component (B-1). Preferably, the linear organohydrogen polysiloxane of component (B-1) is represented by the following average structural formula (III): Average structural formula (III): R33SiO(R32SiO2 / 2)nSiR33 (In formula (III), R3 is a hydrogen atom or a monovalent hydrocarbon group other than an alkenyl group that is halogenated or unsubstituted, and in a molecule, at least two R4 are hydrogen atoms, and n is 1-100).

[0080] In formula (III) above, the halogenated or unsubstituted monovalent hydrocarbon group other than the alkenyl group as R3 can be exemplified by: alkyl groups with 1-12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tributyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups with 6-20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups with 7-20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups are substituted by halogen atoms such as fluorine, chlorine, or bromine atoms. Without hindering the purpose of the invention, R3 may be a small amount of hydroxyl or alkoxy groups such as methoxy or ethoxy. R3 is preferably selected from hydrogen atoms, alkyl groups with 1-6 carbon atoms, especially methyl, or aryl groups with 6-20 carbon atoms, especially phenyl.

[0081] In the above formula (III), m is preferably 1-50, more preferably 1-20, even more preferably 1-10, and particularly preferably 1-5.

[0082] In a preferred embodiment of the present invention, the linear organohydrogen polysiloxane of component (B-1) contains hydrogen atoms bonded to silicon atoms at both ends of the molecular chain. The linear organohydrogen polysiloxane of component (B-1) has hydrogen atoms bonded to silicon atoms on the M unit, and may or may not contain hydrogen atoms bonded to silicon atoms on the D unit, but preferably does not contain them.

[0083] The linear organohydrogen polysiloxane of component (B-1) preferably contains aryl groups bonded to silicon atoms on the side chains of the molecular chain. The linear organohydrogen polysiloxane of component (B-1) may or may not contain aryl groups at the ends of the molecular chain, but preferably does not. In a preferred embodiment, the linear organohydrogen polysiloxane of component (B-1) comprises a structural unit in which one silicon atom, represented by Ar₂SiO₂ / ₂ (where Ar represents an aryl group), is replaced by two aryl groups.

[0084] In one embodiment of the present invention, when the linear organohydrogen polysiloxane of component (B-1) contains aryl groups, the content of aryl groups in all organic groups bonded to silicon atoms is not particularly limited. For example, it can be 10 mol% or more of the total amount of organic groups bonded to silicon atoms, preferably 15 mol% or more, more preferably 20 mol% or more, and can be 50 mol% or less of the total amount of organic groups bonded to silicon atoms, preferably 40 mol%, more preferably 30 mol% or less. Furthermore, the content of aryl groups can be determined by analysis such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR).

[0085] When component (B) contains (B-1) linear organohydrogen polysiloxane, its content is not particularly limited. Based on the total mass of the cured silicone composition of the present invention, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, based on the total mass of all organopolysiloxane components, it is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0086] In one embodiment of the present invention, component (B) may also comprise a resinous organohydrogen polysiloxane as component (B-2). The resinous organohydrogen polysiloxane of component (B-2) is preferably represented by the following average unit formula (VI): Average unit cell (VI): (R³⁺·3SiO₂¹ / ²) a(R³⁺·2SiO₂² / ²) b(R³SiO₂³ / ²) c(SiO₂⁴ / ²) d(XO¹ / ²) e In formula (VI), R3 is independently a hydrogen atom or a monovalent hydrocarbon group other than an alkenyl group that is halogenated or unsubstituted, wherein in a molecule, at least two R3 are hydrogen atoms, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 0.9, 0 ≤ d < 0.7, 0 ≤ e < 0.4, a + b + c + d = 1.0, and c + d > 0.

[0087] As for R3 in formula (VI) above, the same groups as R3 and X in formula (III) above can be used, whether halogenated or unsubstituted, as a monovalent hydrocarbon group other than an alkenyl group.

[0088] In equation (VI) above, a is preferably in the range of 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 equation (VI) above, 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 equation (VI) above, 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 equation (VI) above, 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 above formula (VI), e is preferably in the range of 0 ≤ e ≤ 0.15, more preferably in the range of 0 ≤ e ≤ 0.1, and especially in the range of 0 ≤ e ≤ 0.05.

[0089] In a preferred embodiment of the present invention, in formula (VI) above, c is greater than 0, that is, the resinous organohydrogen polysiloxane of component (B-2) contains T units. The resinous organohydrogen polysiloxane of component (B) may or may not contain Q units, but preferably does not.

[0090] In a preferred embodiment of the present invention, the resinous organohydrogen polysiloxane of component (B-2) contains hydrogen atoms bonded to silicon atoms at the molecular ends. Preferably, the resinous organohydrogen polysiloxane of component (B-2) has hydrogen atoms bonded to silicon atoms on the M units, and the side chains of the molecular chain (i.e., D units and T units) may or may not contain hydrogen atoms bonded to silicon atoms, but preferably they do not.

[0091] When the resinous organohydrogen polysiloxane of component (B-2) contains aryl groups, its content (the percentage of aryl groups in all functional groups bonded to silicon atoms in the resinous organohydrogen polysiloxane in mol%) can be designed as needed. It is usually 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, further preferably 13 mol% or more, particularly preferably 16 mol% or more, and can be 50 mol% or less, preferably 40 mol% or less, more preferably 35 mol% or less, preferably 30 mol% or less, and particularly preferably 25 mol% or less.

[0092] Furthermore, in one embodiment of the present invention, the resinous organopolysiloxane of component (B-2) can be in a state ranging from solid to liquid. Preferably, it is a liquid, and its viscosity is not particularly limited, but at 25°C and 20 mPa·s, it is preferably in the range of 1-100,000 mPa·s, more preferably in the range of 2-50,000 mPa·s, and even more preferably in the range of 3-10,000 mPa·s.

[0093] When the curable silicone composition of the present invention contains a resinous organic hydrogen polysiloxane, its content is not particularly limited. Based on the total mass of the curable silicone composition of the present invention, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 1.5% by mass or more, and may be 15% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less.

[0094] The content of component (B) is not particularly limited, but based on the total mass of the cured silicone composition, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. In a preferred embodiment, based on the total mass of the cured silicone composition, the content of component (B) may be 40% by mass or less, preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0095] Furthermore, in one embodiment of the present invention, the ratio of alkenyl groups bonded to silicon atoms to hydrogen atoms in the organopolysiloxane component (B) is such that, relative to 1 mol of alkenyl groups bonded to silicon atoms in the cured silicone composition, the amount of hydrogen atoms bonded to silicon atoms can be 0.3 mol or more, preferably 0.5 mol or more, more preferably 0.7 mol or more. For example, relative to 1 mol of alkenyl groups bonded to silicon atoms in the cured silicone composition, the amount of hydrogen atoms bonded to silicon atoms can be 5 mol or less, preferably 3 mol or less, more preferably 2 mol or less, further preferably 1.5 mol or less, preferably 1.2 mol or less, and particularly preferably 1.0 mol or less.

[0096] (C) Silicon dioxide-titanium oxide composite oxide particles The (C) component, a silicon dioxide-titanium oxide composite oxide particle, is a composite particle composed of silicon dioxide (SiO₂) and titanium oxide (TiO₂), which can impart thixotropic properties to the curable silicone composition suitable for this invention, enabling it to form the desired shape, particularly a dome shape. The curable silicone composition of this invention may contain one or more (C) silicon dioxide-titanium oxide composite oxide particles.

[0097] (C) The average particle size of the primary particles of the silicon dioxide-titanium oxide composite oxide particles is not particularly limited, for example, in the range of 10-500 nm, preferably in the range of 10-200 nm. In this specification, the average particle size of the silicon dioxide-titanium oxide composite oxide particles can be determined, for example, by using volume-converted particle size distribution analysis methods such as SEM or TEM.

[0098] (C) The specific surface area of ​​the silicon dioxide-titanium oxide composite oxide particles is not particularly limited, but preferably 25 m² / g or more, more preferably 50 m² / g or more, even more preferably 75 m² / g or more, and typically 300 m² / g or less, preferably 200 m² / g or less. In this specification, the specific surface area of ​​the silicon dioxide-titanium oxide composite oxide particles can be measured, for example, by the nitrogen adsorption BET single-point method.

[0099] (C) The refractive index of the silicon dioxide-titanium oxide composite oxide particles is not particularly limited. For example, at 25°C and a wavelength of 589 nm (sodium D-rays), the refractive index is 1.40 or higher, preferably 1.43 or higher, and even more preferably 1.46 or higher. Furthermore, it is typically 1.61 or lower, preferably 1.58 or lower, and even more preferably 1.55 or lower. Additionally, the refractive index of the silicon dioxide-titanium oxide 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 silicon dioxide-titanium oxide composite oxide particles are dispersed in liquids with different refractive indices.

[0100] In the silicon dioxide-titanium oxide composite oxide particles of composition (C), the composition ratio of silicon dioxide to titanium oxide is not particularly limited. For example, when converted to titanium oxide, the titanium content is preferably 0.01 mol% or more, and more preferably 25 mol% or less, and even more preferably 20 mol% or less. The titanium content can be determined, for example, by fluorescence X-ray analysis.

[0101] (C) The average sphericity of the silicon dioxide-titanium oxide composite oxide particles is not particularly limited, but is usually above 0.80, and preferably above 0.85. The average sphericity can be determined, for example, by image analysis methods such as SEM or TEM.

[0102] The crystal form of the silicon dioxide-titanium oxide composite oxide particles with composition (C) is not particularly limited, but amorphous is preferred. Furthermore, in one embodiment, the proportion of the crystalline phase in the silicon dioxide-titanium oxide composite oxide particles with composition (C) is preferably 5% by mass or less. The proportion of the crystalline phase in the silicon dioxide-titanium oxide composite oxide particles can be determined, for example, by XRD measurement.

[0103] (C) There are no particular limitations on the method for manufacturing silicon dioxide-titanium oxide composite oxide particles, and they can be manufactured using methods well-known in the art. Examples of methods for manufacturing silicon dioxide-titanium oxide composite oxide particles include the sol-gel method and the flame method. In the sol-gel method, a sol solution with a pH of 2 or lower containing acetone in a ratio of 40-200 moles relative to silicon and titanium alkoxides, a water-soluble polymer, an acid, and titanium is prepared. The sol solution undergoes phase separation accompanied by cyclohexane decomposition to generate a gel composed of aggregates of spherical silicon dioxide-titanium oxide composite oxide particles. The gel is crushed and dried, thereby manufacturing silicon dioxide-titanium oxide composite oxide particles. Furthermore, in the flame method, raw materials composed of silicon compounds and titanium compounds are fed into a flame in a gaseous mixture for combustion, thereby manufacturing silicon dioxide-titanium oxide composite oxide particles.

[0104] Examples of commercially available silicon dioxide-titanium oxide composite oxide particles used as component (C) of this invention include Silfil (specific surface area: 100-200 g / m², refractive index 1.48, 1.51 or 1.53) manufactured by Tokuyama Co., Ltd.

[0105] Based on the total mass of the cured silicone composition, the content of silicon dioxide-titanium oxide composite oxide particles in component (C) in this invention is 3% by mass or more. Based on the total mass of the cured silicone composition, the content of silicon dioxide-titanium oxide composite oxide particles in component (C) is preferably 4.5% by mass or more, more preferably 6% by mass or more. Furthermore, in a preferred embodiment, based on the total mass of the cured silicone composition, the content of component (C) is 30% by mass or less, preferably 25% by mass or less, and more preferably 20% by mass or less.

[0106] (D) Curing catalyst The curing catalyst for component (D) is a curing catalyst for the hydrogenation silanization reaction, and is also a catalyst used to promote the curing of the curable silicone composition of the present invention. Examples of such component (D) include: platinum-based catalysts such as chloroplatinic acid, alcoholic 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 tetra(triphenylphosphine)palladium, palladium black, and mixtures with triphenylphosphine; and rhodium-based catalysts, with platinum-based catalysts being particularly preferred.

[0107] The amount of component (D) is the amount of catalyst. More specifically, when a platinum catalyst is used as component (D), the amount of platinum atoms relative to the total mass of the cured 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. Furthermore, the amount of platinum atoms relative to the total mass of the cured 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.

[0108] To the extent that it does not impair the purpose of the present invention, the curable silicone composition of the present invention can be formulated with any components. Examples of such arbitrary components include, for instance, acetylene compounds, organophosphorus compounds, vinyl siloxane compounds, inorganic fillers other than component (C), such as ground quartz, silicon dioxide, titanium dioxide, magnesium carbonate, zinc oxide, iron oxide, diatomaceous earth, inorganic fillers obtained by hydrophobically treating the surface of the inorganic filler with an organosilicone compound, hydrogenated silanization reaction inhibitors, organopolysiloxanes that do not contain hydrogen atoms bonded to silicon atoms or alkenyl groups bonded to silicon atoms, tackifiers different from component (E-1), heat-resistant agents, cold-resistant agents, thermally conductive fillers, flame-retardant agents, thixotropic agents, phosphors, solvents, etc. The amount of such arbitrary components added is typically 0.001-20% by mass of the total composition.

[0109] Among inorganic filler materials, silicon dioxide can be categorized into various types, such as fumed silicon dioxide, dry silicon dioxide, wet silicon dioxide, crystalline silicon dioxide, and precipitated silicon dioxide. Furthermore, silicon dioxide can also be surface-hydrophobicated using organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low molecular weight siloxane compounds, or by using silane coupling agents, titanate coupling agents, etc.

[0110] Hydrogenation silanization reaction inhibitors are components used to inhibit the hydrogenation silanization reaction of cured silicone compositions. Examples of such curing reaction inhibitors include: alkynols 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; enyne 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. The inhibitor for the hydrogenation silanization reaction is preferably selected from alkynols, and particularly preferably 1-ethynyl-1-cyclohexanol. The amount of the inhibitor added is typically 0.001-5% of the total mass of the composition.

[0111] Examples of phosphors include yellow, red, green, and blue phosphors, as well as mixtures of at least two of them, which are widely used in light-emitting diodes (LEDs) and are composed of oxide phosphors, oxynitride phosphors, nitride phosphors, sulfide phosphors, sulfide phosphors, fluoride phosphors, etc. Examples of oxide phosphors include YAG-type green-yellow phosphors containing cerium ions (yttrium, aluminum, garnet), TAG-type yellow phosphors containing cerium ions (tegron, aluminum, garnet), and silicate-type green-yellow phosphors containing cerium or europium ions. Examples of oxynitride phosphors include silane-type red-green phosphors containing europium ions (silicon, aluminum, oxygen, nitrogen). Examples of nitride-based fluoresces include red luminescent fluoresces of the calcium, strontium, aluminum, silicon, and nitrogen systems containing europium ions. Examples of sulfide-based fluoresces include green luminescent fluoresces of the ZnS type containing copper or aluminum ions. Examples of oxide-based fluoresces include red luminescent fluoresces of the Y₂O₂S type containing europium ions. Examples of fluoride-based fluoresces include KSF fluoresces (K₂SiF₆:Mn⁴⁺).

[0112] The viscosity of the cured silicone composition of the present invention is not particularly limited. For example, when using a viscoelasticity measuring device, at a measuring temperature of 25°C, using a cone plate with a cone diameter of 40 mm and a cone angle of 2°, and a shear rate of 10 / s, the viscosity is preferably below 35 Pa·s, and more preferably below 30 Pa·s.

[0113] The cured silicone composition of the present invention exhibits excellent thixotropic properties suitable for forming specific shapes, particularly dome shapes. For example, for the cured silicone composition, using a viscoelasticity measuring device at a measuring temperature of 25°C, the viscosity is measured by rotating a cone plate with a cone diameter of 40 mm and a cone angle of 2° in the same direction at shear rates of 1 / s and 10 / s. When the viscosity ratio of (1 / s) / (10 / s) is taken as the thixotropic index, the value of the thixotropic index is preferably greater than 3.0, more preferably greater than 3.2, further preferably greater than 3.3, and particularly preferably greater than 3.4.

[0114] 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 transmittance of 90% or more, and more preferably 95% or more, at wavelengths of 400 nm to 700 nm. Furthermore, the 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.

[0115] 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 was measured using an Abbe refractometer, and is preferably greater than 1.48, and more preferably greater than 1.50.

[0116] The curable silicone composition of this invention can be cured to form a high-hardness cured product. The cured product obtained by curing the curable silicone composition of this invention preferably has a D50 or higher hardness on a D-type hardness tester at 25°C. Furthermore, the hardness of this D-type hardness tester is determined using a D-type hardness tester according to JIS K6253-1997 "Test Method for Hardness of Vulcanized Rubber and Thermoplastic Rubber".

[0117] The curable silicone composition of this invention can be prepared by mixing the various components. The mixing method can be any method known in the art and is not particularly limited; generally, a homogeneous mixture is formed by simple stirring. Furthermore, when solid components such as inorganic fillers are included as arbitrary components, it is preferable to use a mixing device for mixing. The mixing device is not particularly limited and examples include single-shaft or twin-shaft continuous mixers, two-roll mills, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneading mixers, Henschel mixers, etc.

[0118] [Sealing materials, films] This invention also relates to a sealing material for semiconductors using the curable silicone composition of this invention. The shape of the sealing material of this invention is not particularly limited, but it is preferably dome-shaped or sheet-shaped. The semiconductor sealed by the sealing material or film of this invention is not particularly limited; examples include semiconductors such as SiC and GaN, and especially power semiconductors or light-emitting diodes (LEDs).

[0119] According to the sealing material of the present invention, since the curable silicone composition of the present invention exhibits excellent thixotropic properties, it is possible to form a sealing material of a desired shape, particularly a dome shape, and to provide a sealing material with excellent hardness, refractive index and transparency.

[0120] [Optical Semiconductor Components] The present invention also relates to an optical semiconductor element comprising the sealing material of the present invention. Examples of optical semiconductor elements include light-emitting diodes (LEDs), semiconductor lasers, photodiodes, phototransistors, solid-state cameras, light-emitting elements for optocouplers, and photosensitive elements, with light-emitting diodes (LEDs) being particularly preferred.

[0121] Since light-emitting diodes (LEDs) can emit light from the top, bottom, left, and right sides of a semiconductor element, the components constituting an LED are preferably made of light-absorbing materials, and more preferably of materials with high light transmittance or high reflectivity. Therefore, the substrate on which the semiconductor element is mounted is also preferably made of a material with high light transmittance or high reflectivity. Examples of substrates for mounting the semiconductor element include: conductive metals such as silver, gold, and copper; non-conductive metals such as aluminum and nickel; thermoplastic resins mixed with 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 aluminum nitride.

[0122] The optical semiconductor element of the present invention is sealed by the sealing material of the present invention, thus exhibiting excellent reliability and light extraction efficiency. [Example]

[0123] The curable silicone composition of the present invention will be described in detail through the following examples and comparative examples.

[0124] The curable silicone composition was prepared by mixing the components according to the proportions (parts by mass) shown in the table. In the following text, Me represents methyl, Vi represents vinyl, Ph represents phenyl, and Ep represents 3-epoxypropoxypropyl. Furthermore, the structure of the organopolysiloxane component is simplified in the table, with functional groups other than Me on the M, D, or T units indicated in parentheses. Additionally, H / Vi represents the molar ratio of hydrogen atoms (H) bonded to silicon atoms to vinyl groups (Vi) in the organopolysiloxane component. The amount of the curing catalyst (d component) is expressed in platinum atoms (ppm).

[0125] (Ingredient a: Alkenyl organopolysiloxane) Component a-1: A resinous, alkenyl-containing organopolysiloxane represented by the average unit formula (Me 3SiO 1 / 2) 5(ViMe 2SiO 1 / 2) 17(MeSiO 3 / 2) 39(PhSiO 3 / 2) 39. Component a-2: A resinous, alkenyl-containing organopolysiloxane represented by the average unit formula (Me 3SiO 1 / 2) 14(ViMe 2SiO 1 / 2) 11(MeSiO 3 / 2) 53(PhSiO 3 / 2) 22. Component a-3: A resinous, alkenyl-containing organopolysiloxane represented by the average structural formula (ViMe 2SiO 1 / 2) 3(PhSiO 3 / 2). Component a-4: A linear alkenyl-containing organopolysiloxane represented by the average structural formula ViMe 2SiO(Ph 2SiO) 20SiMe 2Vi. Component a-5: A linear alkenyl-containing organopolysiloxane represented by the average structural formula ViMe 2SiO(Me 2SiO) 60(Ph 2SiO) 30SiMe 2Vi. Component a-6: A resinous, alkenyl-containing organopolysiloxane represented by the average structural formula (ViMe 2SiO 1 / 2) 25(PhSiO 3 / 2) 75. Component a-7: A cyclic alkenyl-containing organopolysiloxane represented by the average unit formula (ViMeSiO 2 / 2) 4. Component a-8: An epoxy-containing resinous organopolysiloxane represented by the average unit formula (ViMe 2SiO 1 / 2) 13(EpMeSiO 2 / 2) 24(PhSiO 3 / 2) 46(OMe) 17. (Ingredient b: Organic hydrogen polysiloxane) Component b-1: A linear organohydrogen polysiloxane represented by the average structural formula HMe 2SiO(Ph 2SiO)SiMe 2H. Component b-2: A resinous organohydrogen polysiloxane represented by the average unit formula (HMe 2SiO 1 / 2) 60(PhSiO 3 / 2) 40. (Component c: Inorganic filler material) Composition c-1: Silicon dioxide-titanium oxide composite oxide particles (manufactured by Tokuyama Co., Ltd., product name: Silfil, specific surface area: 101 g / m2, refractive index 1.51) Composition c-2: Silicon dioxide-titanium oxide composite oxide particles (manufactured by Tokuyama Co., Ltd., product name: Silfil, specific surface area: 101 g / m2, refractive index 1.53) Composition c-3: Silicon dioxide-titanium oxide composite oxide particles (manufactured by Tokuyama Co., Ltd., product name: Silfil, specific surface area: 154 g / m2, refractive index 1.53) Component c'-1: Fumed silicon dioxide Component d: A complex of platinum (4.0% by mass) and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. Ingredient e: 1-Ethynyl-2-cyclohexanol

[0126] The following evaluations were conducted, and the results are summarized in Table 1.

[0127] [Viscosity and Thixotropic Index] For cured silicone compositions, a viscoelasticity measuring apparatus (MCR302, manufactured by Anton Paar) was used. A cone plate with a diameter of 40 mm and a cone angle of 2° was used, and viscosity was measured by rotating in the same direction at shear rates of 1 / s and 10 / s. The measurement temperature was uniformly set at 25°C. The thixotropic index was calculated as the viscosity ratio of (1 / s) / (10 / s). The viscosity value was measured at a shear rate of 10 / s.

[0128] [Refractive Index] The refractive index of the curable silicone composition at 25°C before curing was determined using an Abbe refractometer. A 589 nm light source was used for the measurement.

[0129] [Hardness of the cured product] The obtained curable silicone composition was cured at 150°C for 1 hour to prepare a 10 mm thick test specimen, and the hardness at 25°C was measured using a D-type hardness tester.

[0130] [Light transmittance of cured material] The obtained curable silicone composition was placed between two transparent glass plates and cured at 150°C for 1 hour to form a test specimen with an optical path length of 1 mm. The transmittance of this test specimen was measured at 25°C using an automated recording spectrophotometer capable of measuring at any wavelength within the visible light range (400 nm–700 nm). The transmittance value at a wavelength of 450 nm is also listed in Table 3.

[0131] [Table 1] Element Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 a-1 M 5-M(Vi) 17-T 39-T(Ph) 39 54.4 - 62.39 63.2 - - - a-2M 14-M(Vi) 11-T 53-T(Ph) 22 - - - - 61.2 61.2 52.7 a-3 M(Vi) 3-T(Ph) 3.3 - 3.3 3.8 - - - a-4 M(Vi)-D(Ph) 20-M(Vi) 4.2 9.1 4.2 4.9 - - But a-5 M(Vi)-D 60-D(Ph 2) 30-M(Vi) But But But But 16.4 16.4 14.1 a-6M(Vi) 25-T(Ph) 75 But 55.69 But But But But But a-7D(Vi) 4 0.2 0.9 0.2 0.2 0.2 0.2 0.2 a-8 M(Vi) 13-D(Ep) 24-T(Ph) 46-(OMe) 17 2.5 2.5 2.5 2.9 2.4 2.4 2.1 b-1 M(H)-D(Ph 2)-M(H) 18 16.8 19.4 21 10.8 10.8 9.2 b-2 M(H) 60-T(Ph) 40 But 2.0 But But 4.8 4.8 4.1 c-1 SiO2-TiO2 composite particles RI1.51 17.39 - - 3.9 - - c-2 SiO2-TiO2 composite particles RI1.53 - 13 - - - - - c-3SiO2-TiO2 composite particles RI1.51 - - 8 - - - - c'-1 Fumed silicon dioxide - - - 3.99 - 3.9 17.3 e 1-ethynyl-2-cyclohexanol 0.01 0.01 0.01 0.01 0.3 0.3 0.3 Total 100 100 100 100 100 100 100 d. Platinum-cured catalyst (Pt content, ppm) 1.5 3.0 1.5 1.5 4.0 4.0 4.0 H / Vi 0.8 0.8 0.8 0.8 1.1 1.1 1.1 evaluate Viscosity (Pa·s) 20 20 20 15 9 20 25 Thixotropic index 3.5 3.5 3.5 3.2 1.5 3.2 3.3 Refractive index 1.51 1.53 1.51 1.50 1.48 1.48 1.48 Hardness D 52 63 51 50 30 30 32 Transmittance (%, 450 nm) 98 98 99 50 45 85 20

[0132] As can be seen from the results in Table 1 above, the curable silicone composition of the present invention has excellent thixotropic properties and can form a cured product with high refractive index, hardness and transparency. [Industry availability]

[0133] The curable silicone composition of the present invention has excellent thixotropic properties, enabling the formation of cured products of desired shapes. Furthermore, the obtained cured products have excellent refractive index, hardness, and transparency, and are therefore very useful, for example, when used as dome-shaped or sheet-shaped sealing materials in the manufacture of semiconductor packages.

[0134] none

[0135] none

Claims

1. A curable silicone composition comprising: (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule; (B) an organohydrogen-containing organohydrogen-containing organopolysiloxane having at least two hydrogen atoms bonded to silicon atoms per molecule; (C) silicon dioxide-titanium oxide composite oxide particles at a mass of 3% to 20% by mass relative to the total mass of the composition, wherein the (C) silicon dioxide-titanium oxide composite oxide particles have a refractive index of about 1.40 to about 1.58 as measured at a wavelength of 589 nm; and (D) a curing catalyst wherein the curable silicone composition has a viscosity of 30 Pa·s or less at 25°C.

2. The cured silicone composition as described in claim 1, wherein, The specific surface area of ​​the (C) silicon dioxide-titanium oxide composite oxide particles is above 50 m2 / g.

3. The cured silicone composition as described in claim 1 or 2, wherein, The (A) alkenyl organopolysiloxane comprises resinous organopolysiloxanes, linear organopolysiloxanes, or both, in which the amount of aryl groups among all functional groups bonded to silicon atoms is 20 mol% or more.

4. A sealing material comprising a curable silicone composition as described in claim 1 or 2.

5. An optical semiconductor device comprising a sealing material as described in claim 4.