Photocurable silicone composition and cured product thereof

Abstract

A photocurable silicone composition is disclosed. A cured product of the composition and a method for forming the same are also disclosed. The photocurable silicone composition comprises (A) a specific organopolysiloxane having an alkenyl group in the molecule, (B) a compound having at least two thiol groups in the molecule, (C) a photoradical initiator having a phosphorus atom, and (D) a specific hydroxyphenyltriazine compound. The composition exhibits excellent curability using LED lamps and metal halide lamps with a wide UV-visible range, and cures to form a cured product that exhibits excellent light resistance.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and all benefits of U.S. Provisional Patent Application No. 62 / 939,639, filed November 24, 2019, the contents of which are incorporated herein by reference.

[0002] The present invention relates to a photocurable silicone composition and a cured product thereof. [Background technology]

[0003] The curable silicone composition having good optical transparency and high elongation property is used as adhesive or pressure-sensitive adhesive.In particular, since thermally unstable components such as liquid crystal, OLED, touch panel, and cover lens are required to use image display devices, the photocurable silicone composition that enables relatively low curing temperature such as less than 40°C is mainly used for optical displays.

[0004] Patent Document 1 proposes an ultraviolet-curable silicone composition that contains a linear organopolysiloxane having an aliphatic unsaturated group, an organopolysiloxane having a silicon-bonded mercaptoalkyl group, an acylphosphine oxide-based photoinitiator, and acetophenone and / or propiophenone.

[0005] However, such UV-curable silicone compositions have problems in that they are poorly cured in deep areas when exposed to UV light, resulting in insufficient curing, and they also suffer from the problem that discoloration and haze occur when the cured silicone product is exposed to high temperature or high humidity conditions.

[0006] Patent Document 2 proposes a photocurable silicone composition that includes an organopolysiloxane having at least one aryl group having 6 to 12 carbon atoms and at least one alkenyl group having 2 to 12 carbon atoms in the molecule, an organic compound having at least two ether bonds and at least one aliphatic carbon-carbon double bond in the molecule, a compound having at least two thiol groups in the molecule, a photoradical initiator having a phosphorus atom, and a hindered phenol compound. The photocurable silicone composition is cured by irradiation with active energy rays to form a cured product that suppresses the decrease in transmittance due to coloring and haze even when left under high temperature / high humidity conditions.

[0007] However, such photocurable silicone compositions have the problem that, although they only have excellent light resistance, they have poor curability when used with LED lamps and metal halide lamps that have a wide UV-visible range (365 to 405 nm). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2013-253179(A)

[0009] [Patent Document 2] International Publication No. 2017 / 155919(A1) Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a photocurable silicone composition that exhibits excellent curability with LED lamps and metal halide lamps having a wide UV-visible range, and that cures to form a cured product that exhibits excellent light resistance. Another object of the present invention is to provide a cured product that exhibits excellent light resistance. [Means for solving the problem]

[0011] The photocurable silicone composition of the present invention comprises: (A) The average composition of: R 1 a R 2 b SiO (4-a-b) / 2 (In the formula, R 1 is an alkenyl group having 2 to 12 carbon atoms, R 2 is an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, provided that R 2 wherein at least 30 mol % of the organopolysiloxane is an aryl group or an aralkyl group, and "a" and "b" are positive numbers satisfying 1≦a+b≦2.5 and 0.001≦a / (a+b)≦0.2; (B) a compound having at least two thiol groups in the molecule, in an amount such that the amount of thiol groups in the component is within the range of 0.2 to 2.0 mol per mol of all alkenyl groups in component (A); (C) 0.01 to 5 parts by mass of a photoradical initiator having a phosphorus atom, (D) a general formula: [ka] (In the formula, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 and R 37 are the same or different and are selected from a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 12 carbon atoms; R 4 is a linear or branched alkyl group having 6 to 12 carbon atoms, or a group represented by the following general formula: -CH2CH(OH)CH2OR 5 (In the formula, R 5 is a linear or branched alkyl group having 6 to 20 carbon atoms), and 0.001 to 2 parts by mass of a hydroxyphenyltriazine compound represented by the formula:

[0012] In various embodiments, R in component (D) 31 , R 34 , and R 35 is a hydrogen atom, and R in component (D) 32 , R 33 , R 36 and R 37 is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

[0013] In various embodiments, R in component (D) 4 has the following general formula: -CH2CH(OH)CH2OR 5 (In the formula, R 5 is a linear or branched alkyl group having 6 to 20 carbon atoms.

[0014] In various embodiments, component (D) is a hydroxyphenyltriazine compound represented by the formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] and mixtures thereof. For example, component (D) may comprise simply one or more of the foregoing compounds.

[0015] The cured product of the present invention can be obtained by irradiating the above-mentioned photocurable silicone composition with light. In various embodiments, the cured product is laminated on the same substrate or different substrates, particularly on the same substrate or different substrates within an optical device. Effect of the Invention

[0016] The photocurable silicone composition of the present invention exhibits excellent curability with LED lamps and metal halide lamps having a wide UV-visible range, and cures to form a cured product that exhibits excellent light resistance. Furthermore, the cured product of the present invention exhibits excellent light resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The terms "comprising" or "comprise" are used herein in their broadest sense to mean and encompass the ideas of "including," "include," "consist(ing) essentially of," and "consist(ing) of." The use of "for example," "eg," "such as," and "including" to list examples does not limit the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to," and includes other similar or equivalent examples. As used herein, the term "about" serves to reasonably encompass or account for slight variations in numerical values ​​as determined by instrumental analysis or as a result of handling samples. Such slight variations may be on the order of ±0-25%, ±0-10%, ±0-5%, or ±0-2.5% of the numerical value. Furthermore, the term "about" applies to both numerical values ​​when relating to a range of values. Furthermore, the term "about" may apply to numerical values ​​even if not expressly stated.

[0018] Generally, as used herein, a hyphen "-" or a wavy line "~" in a range of values ​​means "to" or "through," ">" means "above" or "greater-than," "≥" means "at least" or "greater-than or equal to," "<" means "below" or "less-than," and "≤" means "at most" or "less-than or equal to." Each of the foregoing patent applications, patents, and / or patent publications is expressly incorporated herein in its entirety in one or more non-limiting embodiments on an individual basis.

[0019] It should be understood that the appended claims are not limited to the expressions and specific compounds, compositions, or methods described in the detailed description, which may vary among the specific embodiments within the scope of the appended claims. With respect to any Markush group relied upon herein to describe particular features or aspects of various embodiments, it should be understood that different, special, and / or unexpected results may be obtained from each element of the respective Markush group independently of all other Markush elements. Each element of the Markush group may be relied upon individually and / or in combination to provide appropriate support for specific embodiments within the scope of the appended claims.

[0020] Any ranges and subranges relied upon in describing various embodiments of the present invention should also be understood to be within the scope of the appended claims, both individually and inclusively, and all ranges including integer and / or fractional values ​​therein are understood to be described and contemplated, even if such values ​​are not expressly written herein. Those skilled in the art will readily recognize that the recited ranges and subranges fully describe and enable various embodiments of the present invention, and that such ranges and subranges may be further delineated into relevant halves, thirds, fourths, fifths, etc. As merely an example, the range "0.1-0.9" may be further delineated into a lower third, i.e., 0.1-0.3, a middle third, i.e., 0.4-0.6, and an upper third, i.e., 0.7-0.9, which are individually and inclusively within the scope of the appended claims, and may be relied upon and provide sufficient support for specific embodiments within the scope of the appended claims, individually and / or inclusively. Furthermore, with respect to words defining or modifying a range, such as "at least," "greater than," "less than," "less than," etc., such words should be understood to include subranges and / or upper or lower limits. As another example, the range "at least 10" inherently includes the subranges of at least 10 to 35, at least 10 to 25, 25 to 35, etc., and each subrange may be relied upon and fully supported by specific embodiments within the appended claims, individually and / or collectively. Finally, each individual number within a disclosed range may be relied upon and fully supported by specific embodiments within the appended claims. For example, the range "1 to 9" includes various individual integers, such as 3, as well as individual numbers including decimal points (or fractions), such as 4.1, which may be relied upon and fully supported by specific embodiments within the appended claims. <Photocurable silicone composition>

[0021] Component (A) is the base compound of the composition and has the average formula: R 1 a R 2 bSiO (4-a-b) / 2 It is an organopolysiloxane represented by the formula:

[0022] In the formula, R 1 is an alkenyl group having 2 to 12 carbon atoms, examples of which include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, and a dodecenyl group. Among these, a vinyl group and a hexenyl group are preferred.

[0023] In the formula, R 2 is an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. Of these, a methyl group is preferred. Examples of the aryl group include a phenyl group, a tolyl group, a naphthyl group, and a biphenyl group. Of these, a phenyl group is preferred. Examples of the aralkyl group include a phenylmethyl group, a 1-phenylethyl group, a 2-phenylethyl group, and a 2-phenylpropyl group. Of these, a 2-phenylethyl group and a 2-phenylpropyl group are preferred. In component (A), R in the molecule 2 At least 30 mol % of the groups are aryl or aralkyl groups.

[0024] Furthermore, in the formula, "a" and "b" are positive numbers satisfying 1≦a+b≦2.5, preferably 1.5≦a+b≦2.2, and 0.001≦a / (a+b)≦0.2, preferably 0.005≦a / (a+b)≦0.1.

[0025] The state of component (A) at 25°C is not limited, but is preferably a liquid. The viscosity of component (A) at 25°C is not limited, but the viscosity is preferably within the range of 100 to 1,000,000 mPa·s. In this specification, the viscosity is a value measured at 23±2°C using a B-type viscometer in accordance with ASTM D 1084.

[0026] Component (A) may be one organopolysiloxane satisfying the above average compositional formula, or may be a mixture of at least two organopolysiloxanes satisfying the above average compositional formula. Examples of such component (A) include organopolysiloxanes represented by the following "average compositional formula: average formula". In the formula, "Me", "Vi", "Hex", "Ph", "Phe", and "Php" respectively represent methyl, vinyl, hexenyl, phenyl, 2-phenylethyl, and 2-phenylpropyl groups. Vi 0.03 Me 1.03 Ph 0.97 SiO 0.99 :ViMe2SiO(MePhSiO) 65 SiMe2Vi Vi 0.10 Me 1.10 Ph 0.90 SiO 0.95 :ViMe2SiO(MePhSiO) 18.4 SiMe2Vi Vi 0.09 Me 1.06 Ph 0.91 SiO 0.97 :PhSi{O(PhMeSiO) 10 SiMe2Vi}3 Hex 0.09 Me 1.07 Ph 0.89 SiO 0.98 :Si{O(PhMeSiO) 10 SiMe2Hex}4 Hex 0.12 Me 1.12 Ph 0.88 SiO 0.94 :HexMe2SiO(PhMeSiO) 15 SiMe2Hex Vi 0.06 Me 1.38 Phe 0.63 SiO 0.97 :ViMe2SiO(PheMeSiO) 20 (Me2SiO) 10 SiMe2Vi Hex0.06 Me 1.38 Php 0.63 SiO 0.97 :HexMe2SiO(PhpMeSiO) 20 (Me2SiO) 10 SiMe2Hex

[0027] Component (B) is a curing agent for the composition, and is a compound having at least two thiol groups in the molecule. Component (B) is not limited as long as it has sufficient solubility in component (A).

[0028] Examples of such component (B) include o-, m-, or p-xylylenedithiol, ethylene glycol bisthioglycolate, butanediol bisthioglycolate, hexanediol bisthioglycolate, ethylene glycol bis(3-thiopropionate), butanediol bis(3-thiopropionate), trimethylolpropane tris(3-thiopropionate), pentaerythritol tetrakis(3-thiopropionate), trihydroxyethyl triisocyanurate tris(3-thiopropionate), and mercapto-substituted organopolysiloxanes.

[0029] The content of component (B) is such that the amount of thiol groups provided by the component present is within the range of 0.2 to 2.0 mol, or optionally within the range of 0.3 to 1.6 mol, per mol of all alkenyl groups in component (A), because when the content of component (B) is within the above range, the mechanical strength of the resulting cured product is increased.

[0030] Component (C) is a component that initiates the photocuring reaction of the composition, and is a photoradical initiator containing a phosphorus atom. Examples of such component (C) include diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (trade name: TPO, manufactured by BASF), ethyl(2,4,6-trimethylbenzoyl)phenylphosphonate (trade name: TPO-L, manufactured by BASF), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF).

[0031] The content of component (C) is within the range of 0.01 to 5 parts by mass, optionally within the range of 0.05 to 2 parts by mass, or optionally within the range of 0.1 to 1.5 parts by mass per 100 parts by mass of component (A), because when the content of component (C) is within the above range, curing proceeds efficiently and a cured product having excellent heat resistance and light resistance is formed.

[0032] Component (D) is a hydroxyphenyltriazine compound represented by the following general formula: [ka]

[0033] In the formula, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 and R 37 are the same or different and are selected from a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. Of these, a methyl group is preferred. Of these, R 31 , R 34 and R 35 is preferably a hydrogen atom, R 32 , R 33 , R 36 and R 37is preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

[0034] In the formula, R 4 is a linear or branched alkyl group having 6 to 12 carbon atoms, or a group represented by the following general formula: -CH2CH(OH)CH2OR 5 It is a group represented by:

[0035] Among them, R 4 is preferably of the general formula: -CH2CH(OH)CH2OR 5 It is a group represented by:

[0036] R 4 Examples of the alkyl group include hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups.

[0037] In the formula, R 5 R is a linear or branched alkyl group having 6 to 20 carbon atoms. 5 Examples of the alkyl group include hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups.

[0038] Examples of such component (D) include hydroxyphenyltriazine compounds represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] A hydroxyphenyltriazine compound represented by the following formula: [ka] and mixtures thereof.

[0039] The content of component (D) is within the range of 0.001 to 2 parts by mass, optionally within the range of 0.01 to 1.5 parts by mass, or optionally within the range of 0.05 to 1.5 parts by mass per 100 parts by mass of component (A), because when the content of component (D) is within the above range, the curability of the composition by an LED lamp is increased.

[0040] The present composition contains the above-mentioned components (A) to (D), and preferably contains (E) a hindered phenol compound in order to impart heat resistance to the cured product of the present composition. Examples of such component (E) include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,4-dimethyl-6-(1-methylpentadecyl)phenol, diethyl[{3,5-bis(1,1-di-tert-butyl-4-hydroxyphenyl)methyl}phosphonate, 3,4-dimethyl-6-(1-methylpentadecyl)phenol, ... 3′,3″,5,5′,5″-hexane-tert-butyl-4-a,a′,a″-(mesitylene-2,4,6-tolyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, ethylene bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], and hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0041] The content of component (E) is not limited, but the content is preferably within the range of 0.001 to 1 part by mass, and more preferably within the range of 0.003 to 0.5 parts by mass, per 100 parts by mass of component (A). This is because when the content of component (E) is within the above range, the viscosity change of the composition before photocuring is small, and a cured product having excellent heat resistance and light resistance can be obtained.

[0042] The present composition may further contain, as an optional component, a radical scavenger (F) other than component (E) in order to enhance the storage stability of the present composition under light-shielded conditions, and preferably does so. Examples of such component (F) include hindered amines such as N,N',N'',N'''-tetrakis(4,6-bis(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, methyl-1,2,2,6,6-pentamethyl-4-piperidine, and the like. lysyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione; quinones or phenols such as methylhydroquinone, 1,4-naphthoquinone, 4-methoxynaphthol, tert-butylhydroquinone, benzoquinone, pyrogallol, and phenothiazine.

[0043] The content of component (F) is not limited, but the content is preferably within the range of 0.0001 to 1 part by mass, optionally 0.0001 to 0.1 part by mass, or optionally 0.0001 to 0.05 part by mass per 100 parts by mass of component (A). This is because when the content of component (F) is within the above range, a cured product having excellent heat resistance and light resistance can be obtained.

[0044] The composition may further contain, as an optional component, an organic compound (G) having at least two ether bonds and at least one aliphatic carbon-carbon double bond in the molecule. The group having an aliphatic carbon-carbon double bond in component (G) is not limited, and examples thereof include an alkenyl group, an acryloyl group, and a methacryloyl group. Among them, an acryloyl group or a methacryloyl group is preferred. Furthermore, the state of component (G) at 25°C is not limited, and is preferably a liquid. The viscosity of component (G) at 25°C is not limited, but the viscosity is preferably within the range of 1 to 10,000 mPa·s.

[0045] Examples of such component (G) include phenoxydiethylene glycol acrylate, phenoxytetraethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxynonaethylene glycol acrylate, methoxypolyethylene glycol acrylate, ethoxydiethylene glycol acrylate, ethoxyethoxyethyl acrylate, nonylphenoxytetraethylene glycol acrylate, nonylphenoxyoctaethylene glycol acrylate, nonylphenoxydipropylene glycol acrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, polyethylene glycol methacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, bisphenol diethylene glycol diacrylate, bisphenol A triethylene glycol diacrylate, tetraethylene glycol diacrylate, bis Phenol A polyethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, bisphenol A diethylene glycol dimethacrylate, bisphenol A triethylene glycol dimethacrylate, bisphenol A tetraethylene glycol dimethacrylate, bisphenol A polyethylene glycol dimethacrylate, triethylene glycol divinyl ether, tripropylene glycol divinyl ether, polyethylene glycol monoallyl ether, methoxypolyethylene glycol allyl ether, propylene glycol allyl ether, butoxypolyethylene glycol / propylene glycol allyl ether, polyethylene glycol diallyl ether, polypropylene glycol diallyl ether, trimethylolpropane triallyl ether, trimethylolpropane diallyl ether, pentaerythritol tetraallyl ether, and pentaerythritol triallyl ether.

[0046] The content of component (G) is not limited, but the content is preferably within the range of 3 to 30 parts by mass, or optionally within the range of 5 to 20 parts by mass, per 100 parts by mass of component (A). This is because when the content of component (G) is equal to or higher than the lower limit of the above range, the decrease in transmittance of the cured product at high temperature / high humidity is small. On the other hand, when the content is equal to or lower than the upper limit of the above range, the change in hardness of the cured product at high temperature is small, and coloring is reduced.

[0047] In addition to the above-mentioned components (A) and (G), the present composition may further contain, as optional components, an organic compound (H) having at least one aliphatic carbon-carbon double bond in the molecule; a tackifier; an inorganic filler such as silica, titanium oxide, glass, alumina, or zinc oxide; a fine powder of an organic resin such as a polymethacrylate resin or a silicone resin; and a pigment or a fluorescent substance, so long as the object of the present invention is not impaired.

[0048] Component (H) is not limited as long as it is an organic compound having at least one aliphatic carbon-carbon double bond in the molecule, and is preferably a liquid at 25° C. There are no limitations on the viscosity of component (H) at 25° C., but the viscosity is preferably within the range of 1 to 500 mPa s.

[0049] Examples of such components (H) include methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isodecyl acrylate, triacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, phenoxyethyl acrylate, tetrahydrofuran acrylate, benzyl acrylate, o- Phenylphenol ethoxyethyl acrylate, 2-ethylhexyl acrylate, hexanediol diacrylate, nonanediol diacrylate, 2-propenoic acid octahydro-4,7-methano-1H-inden-5-yl ester, decyl vinyl ether, 2-ethylhexyl vinyl ether, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, allyl methacrylate, divinyl sulfone, 3-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane.

[0050] Further examples of tackifiers include silane compounds, such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane; siloxane compounds having at least one silicon-bonded alkenyl group and / or silicon-bonded hydrogen atom, and at least one silicon-bonded alkoxy group in the molecule; silane compounds or siloxane compounds having at least one silicon-bonded alkoxy group, A mixture of a siloxane compound having at least one silicon-bonded hydroxy group and at least one silicon-bonded alkenyl group in the molecule; methyl polysilicate, ethyl polysilicate, and epoxy group-containing ethyl polysilicate are included. The content of the tackifier is not limited, but the content is preferably within the range of 0.01 to 10 parts by mass per 100 parts by mass of component (A).

[0051] The viscosity of the composition at 25°C is not limited, but is preferably within the range of 100 to 100,000 mPa·s, or optionally within the range of 500 to 10,000 mPa·s. This is because when the viscosity of the composition is equal to or higher than the lower limit of the above range, a cured product having high mechanical strength is obtained. On the other hand, when the viscosity is equal to or lower than the upper limit of the above range, the resulting composition has excellent coating properties / workability, and the formation of voids in the cured product is avoided.

[0052] <Cured product> The cured product of the present invention can be obtained by irradiating the above-mentioned photocurable silicone composition with light. Examples of light used to cure the composition include ultraviolet light and visible light, and light having a wavelength in the range of 250 to 500 nm is preferred. This is because excellent curability can be obtained and the cured product is not decomposed by light.

[0053] The cured product is typically optically transparent. This is preferably because optical transparency is desirable for high performance when the cured product is used in an optical device or image display. The form of the cured product is not limited and can be in the form of a sheet, film, or block. The cured product can be combined with various substrates. The cured product is typically laminated between the same substrate or different substrates, particularly between the same substrate or different substrates in an optical device.

[0054] The state of the cured product is not limited, but is preferably an elastomer or a gel. The hardness is preferably within the range of 0 to 80, or optionally within the range of 10 to 70, in Shore OO hardness. This is because, when the cured product is within the above range, good cohesive strength against deformation and good flexibility against material crushing are obtained. In this specification, the Shore OO hardness is a value measured at 23±2°C using OO hardness according to ASTM D 2240.

[0055] <Method of manufacturing the cured product> The method for producing the cured product is as follows: i-1) laminating the photocurable silicone composition of the present invention between the same substrate or different substrates, provided that at least one of the substrates is transparent; i-2) exposing the photocurable silicone composition to light through a transparent substrate.

[0056] In step i-1, the photocurable silicone composition is applied to the surface of a light-shielding substrate (e.g., a black substrate). Examples of coating methods include slit coating, roll coating, spin coating, screen printing, and the like. The thickness of the photocurable silicone composition is not limited, but is preferably in the range of 50 to 1,000 μm, optionally in the range of 50 to 500 μm, or optionally in the range of 100 to 350 μm. Next, a transparent substrate having a light-shielding portion is laminated on the surface of the photocurable silicone composition as described above. The lamination can be performed either in air or in a vacuum. In order to prevent air bubbles from being generated during lamination, it is preferable to perform the lamination in a vacuum. The lamination can also be performed under pressure by a press or the like.

[0057] In step i-2, UV curing is performed by UV irradiation to cure the transparent regions. For example, low-pressure, high-pressure, or extra-high-pressure mercury lamps, metal halide lamps, (pulsed) xenon lamps, or electrodeless lamps are useful as UV lamps. The irradiation dose is preferably 5 to 6,000 mJ / cm. 2 or arbitrarily within the range of 10 to 4,000 mJ / cm 2 is within the range.

[0058] The light-shielding portion of the transparent substrate prevents light from passing through, and the uncured photocurable silicone composition is present at the bottom of the light-shielding portion. To cure the light-shielding portion, side curing is performed by a UV LED (light-emitting diode) lamp. Typical wavelengths of UV LED lamps are 365 nm, 385 nm, 395 nm, and 405 nm. Preferably, 365 nm and 395 nm are commonly used. The irradiation is preferably 50 to 2,000 mJ / cm. 2or arbitrarily within the range of 100 to 1,000 mJ / cm 2 The irradiation time is preferably within the range of 1 to 120 seconds, or optionally within the range of 15 to 60 seconds. The term "uncured" refers to a state in which the composition is fluid in a 25°C environment.

[0059] Another method for producing the cured product is as follows: ii-1) applying the photocurable silicone composition of the present invention onto a transparent or opaque substrate; ii-2) exposing the photocurable silicone composition to light to form a silicone product in a semi-cured state; ii-3) laminating the silicone product with another transparent or opaque substrate; ii-4) exposing the silicone product to light through a transparent substrate.

[0060] In step ii-1, the photocurable silicone composition is applied to the surface of the substrate. Examples of the coating method include the above-mentioned methods. The thickness of the photocurable silicone composition is not limited, but is preferably within the range of 50 to 1,000 μm, optionally within the range of 50 to 500 μm, or optionally within the range of 100 to 350 μm.

[0061] In step ii-2, the applied photocurable silicone composition is partially cured by a UV LED lamp to form a non-flowable uncured layer. The term "uncured" refers to a state where the composition is not flowable at 25°C but is not a fully crosslinked network (having intermediate physical properties between a liquid and a fully cured product). UV curing is performed by UV irradiation, and the source of the UV light is not important in the case of lamps that irradiate light rays close to UV light. Typically, UV LED lamps are commonly used to precisely control the curing speed. Typical wavelengths of UV LED lamps are 365 nm, 385 nm, 395 nm, and 405 nm. Preferably, 365 nm and 395 nm are commonly used. The irradiation dose is preferably 5 to 1,000 mJ / cm. 2 or arbitrarily within the range of 10 to 500 mJ / cm2 The UV irradiation is usually in air, on the top side of the coating (usually air, preferably irradiated from the surface). If necessary to prevent surface oxygen inhibition, the photocurable silicone composition may be irradiated with UV in an environment of gases that do not cause cure inhibition, such as nitrogen and carbon dioxide.

[0062] In step ii-3, a transparent substrate having a light-shielding portion is applied to the surface of the coated photocurable silicone composition prepared above. Lamination can be performed either in air or in vacuum. In order to prevent air bubbles from being generated during lamination, lamination in vacuum is preferred. Lamination can also be performed under pressure by a press or the like.

[0063] In step ii-4, UV curing is performed by UV irradiation to cure the transparent regions. For example, low-pressure, high-pressure, or extra-high-pressure mercury lamps, metal halide lamps, (pulsed) xenon lamps, or electrodeless lamps are useful as UV lamps. The irradiation dose is preferably 5 to 6,000 mJ / cm. 2 or arbitrarily within the range of 10 to 4,000 mJ / cm 2 is within the range.

[0064] The light-shielding portion of the transparent substrate prevents light from passing through, and the uncured photocurable silicone composition is present at the bottom of the light-shielding portion. To cure the light-shielding portion, side curing is performed by a UV LED (light-emitting diode) lamp. Typical wavelengths of UV LED lamps are 365 nm, 385 nm, 395 nm, and 405 nm. Preferably, 365 nm and 395 nm are commonly used. The irradiation is preferably 50 to 2,000 mJ / cm. 2 or arbitrarily within the range of 100 to 1,000 mJ / cm 2 The irradiation time is preferably within the range of 1 to 120 seconds, or optionally within the range of 15 to 60 seconds. The term "uncured" refers to a state in which the composition is fluid in a 25°C environment.

[0065] The cured product is useful as a laminate in an optical device or image display. The optical device is, for example, an optical semiconductor device. Examples of optical semiconductor devices include light-emitting diodes (LEDs), photocouplers, and CCDs. Furthermore, as optical semiconductor elements, light-emitting diode (LED) elements and solid-state image sensors are shown. In particular, even when so-called micro LEDs (mini LEDs) having a structure in which a large number of small LED elements are arranged on a substrate are collectively sealed, the photocurable silicone composition of the present invention can be suitably used. At this time, the refractive index of the cured product can be adjusted as necessary by selecting the type of functional group, such as the content of aryl groups. Furthermore, since the photocurable silicone composition of the present invention has excellent heat resistance and moisture resistance, the transparency is unlikely to decrease and turbidity is hardly caused. Therefore, there is an advantage that the light extraction efficiency of an optical semiconductor device including a micro LED can be well maintained. EXAMPLES

[0066] The photocurable silicone composition and the cured product of the present invention will be described in detail using examples and comparative examples. In the formulas, "Me", "Ph", and "Vi" respectively represent a methyl group, a phenyl group, and a vinyl group. The properties of the photocurable silicone composition and its cured product were measured as follows.

[0067] <Viscosity> The viscosity at 23±2° C. was measured according to ASTM D 1084 “Standard Test Methods for Viscosity of Adhesive” by using a Brookfield LVF Type rotational viscometer (using spindle #2 at 60 rpm).

[0068] <Hardness> The photocurable silicone composition was poured into a mold having a cavity of a specified shape, and the cumulative exposure dose was 4,000 mJ / cm 2As described above, ultraviolet rays were irradiated from the upper liquid surface with a high-pressure mercury lamp. The hardness of the obtained cured product was measured with a Type OO indentation hardness tester according to the method defined by ASTM D 2240-00.

[0069] <Transmittance and Yellowness Index (YI)> The transmittance and yellowness index of a plate-shaped cured product having a thickness of 500 μm cured as described above were measured by the method defined by ASTM D 1003 (UV-visible spectrometer). The yellowness index (YI) was measured by the same method as above with ASTM D 1925 (spectrophotometer, CM-3600A).

[0070] <QUV Aging Test> The resistance to light fatigue was determined by a QUV accelerated weathering tester (Q-Panel Co., Cleveland, Ohio) equipped with a UVA-340 lamp calibrated to 0.89 W / m 2 / nm (ASTM G154 Cycle 1). A plate-shaped cured product having a thickness of 500 μm cured as described above was irradiated in the QUV accelerated weathering tester for 12 consecutive hours per cycle consisting of 8 hours of irradiation at a temperature of 60 °C and 4 hours of darkness (condensation) at a temperature of 50 °C. Then, the plate-shaped cured product was held for 48 cycles (24 days), and the yellowness index (YI) was measured by the same method as above.

[0071] <Deep Curing Characteristics> The photocurable silicone composition was poured into a mold consisting of two black plates with a thickness of 2 cm, and the plates were separated by a spacer with a thickness of 500 μm. Ultraviolet rays at a UV illuminance of 1000 mW / cm 2 were irradiated from the upper liquid surface for 30 seconds and 60 seconds using a 365 nm LED lamp (FireJet (trademark) FJ100). Then, ultraviolet rays at a UV illuminance of 200 mW / cm 2 were irradiated from the upper liquid surface for 30 seconds and 60 seconds using a 395 nm LED lamp (FireJet (trademark) FJ100). After irradiation, the test piece was disassembled, and the length (cm) of the portion that lost fluidity due to curing was measured.

[0072] <Examples 1 to 2 and Comparative Examples 1 to 4> Photocurable silicone compositions were prepared from the following components using a planetary vacuum mixer (Thinky mixer) with the composition (parts by weight) shown in Table 1. The photocurable silicone compositions of Examples 1-2 and Comparative Examples 1-4 were prepared to obtain 0.8 moles of thiol groups in component (b1) per mole of total aliphatic carbon-carbon double bonds in components (a1) and (a2). The properties of this photocurable silicone composition and its cured product are shown in Table 1.

[0073] The following organopolysiloxanes were used as component (A): (a1) having a viscosity of 40,000 mPa s and the following average formula: ViMe2SiO(MePhSiO) 92 SiMe2Vi (Average composition formula: Vi 0.02 Me 1.02 Ph 0.98 SiO 0.99 ) Organopolysiloxane represented by the formula: (a2) having a viscosity of 3,000 mPa s and the following average formula: ViMe2SiO(MePhSiO) 23 SiMe2Vi (Average composition formula: Vi 0.08 Me 1.08 Ph 0.92 SiO 0.96 ) Organopolysiloxane represented by the formula:

[0074] The following organic compounds were used as component (B): (b1): Trimethylolpropane tris(3-thiopropionate)

[0075] The following photoradical initiators were used as component (C): (c1): Ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate

[0076] The following hydroxyphenyltriazine compounds were used as component (D): (d1) A hydroxyphenyltriazine compound represented by the following formula: [ka] (d2) a mixture of hydroxyphenyltriazine compounds represented by the following formula: [ka] and a hydroxyphenyltriazine compound represented by the following formula: [ka]

[0077] The following hydroxyphenyltriazine compounds were used as comparisons for component (D): (d3) A hydroxyphenyltriazine compound represented by the following formula: [ka] (d4) A hydroxyphenyltriazine compound represented by the following formula: [ka] (d5) A hydroxyphenyltriazine compound represented by the following formula: [ka] [Table 1]

[0078] Comparative Example 1 showed severe yellowing / browning during the QUV aging test due to the lack of triazine additive. The yellowness index increased from 0.24 to 24.12. Meanwhile, Examples 1-2 and Comparative Examples 2-4 showed good optical stability during the QUV aging test due to the addition of triazine additive. It was revealed that these additives effectively stabilized the cured product of the photocurable silicone composition under light irradiation conditions. At the same time, these additives reduced the deep curing properties due to high absorption in the UVA and UVB ranges as summarized in Table 1 for transmittance. Among them, it was revealed that certain hydroxyphenyl triazine compounds such as components (d1) and (d2) of Examples 1 and 2, respectively, exhibited superior deep curing properties compared to other hydroxyphenyl triazine compounds such as components (d3), (d4) and (d5) of Comparative Examples 2, 3 and 4, respectively.

[0079] <Examples 3 to 6 and Comparative Examples 5 to 8> Photocurable silicone compositions were prepared from the above components using a planetary vacuum mixer (Thinky mixer) with the composition (parts by weight) shown in Table 2. The photocurable silicone compositions of Examples 3 to 6 and Comparative Examples 5 to 8 were prepared to obtain 0.8 moles of thiol groups in component (b1) per mole of total aliphatic carbon-carbon double bonds in components (a1) and (a2). The properties of this photocurable silicone composition and its cured product are shown in Table 2. [Table 2]

[0080] Examples 3-6 and Comparative Examples 5-8 contained 0.1 ppb of component (c1). In Examples 3-6 and Example 1, the amount of component (d1) was changed from 0.05 to 1. As the content of component (d1) decreased, more yellowing appeared after QUV aging test. As the content of component (d1) increased, a slight adverse effect appeared on deep curing properties and early yellowing. The preferred content of component (d1) seems to be less than 1 ppb and higher than 0.05 ppb (by weight) of the composition. The most preferred range is 0.1-0.5 ppb (by weight) of the composition. Meanwhile, Comparative Examples 5-8 used component (d4) instead of component (d1) and showed poor side curing properties.

[0081] <Examples 7 to 12 and Comparative Examples 9 to 13> Photocurable silicone compositions were prepared from the above and following components using a planetary vacuum mixer (Thinky mixer) with the composition (parts by mass) shown in Table 3. The photocurable silicone compositions of Examples 7 to 12 and Comparative Examples 9 to 13 were prepared to obtain 0.8 moles of thiol groups in component (b1) per mole of total aliphatic carbon-carbon double bonds in components (a1) and (a2). The properties of this photocurable silicone composition and its cured product are shown in Table 3.

[0082] The following photoradical initiators were used as component (C): (c2): A mixture of 90% by mass of ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate and 10% by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (c3): Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide

[0083] The following photoinitiators were used as comparisons for component (C): (c4) 1-Hydroxy-cyclohexyl phenyl ketone (c5) 2-Hydroxy-2-methyl-1-phenylpropan-1-one [Table 3] [Table 4]

[0084] Phosphorus-containing photoinitiators as shown in Examples 7-12 showed superior deep section cure properties compared to Comparative Examples 9-13 which contained simple phenyl ketone type photoinitiators. As the amount of photoinitiator was increased to 1 ppb, more severe yellowing appeared. The content is <1 ppb, more preferably <0.05, in the preferred compositions.

[0085] <Comparative Examples 14 to 24> Photocurable silicone compositions were prepared from the above and following components using a planetary vacuum mixer (Thinky mixer) with the composition (parts by mass) shown in Table 4. The photocurable silicone compositions of Comparative Examples 14 to 24 were prepared to obtain 0.8 moles of thiol groups in component (b1) per mole of total aliphatic carbon-carbon double bonds in components (a1) and (a2). The properties of the photocurable silicone compositions and their cured products are shown in Table 4. [Table 5] [Table 6]

[0086] Because the component (d4) was contained, all of Comparative Examples 14 to 24 exhibited insufficient deep curing properties. [Industrial Applicability]

[0087] The composition is easily cured by irradiation with high energy rays such as ultraviolet light and visible light, provides a transparent cured product, and has excellent deep curing properties. Therefore, the composition is useful as various potting agents, sealants, and adhesives. The cured product has high optical transparency and excellent adhesive properties. Therefore, the cured product is useful as a laminate for optical devices and image displays.

Claims

1. (A) the following average composition formula: R １ ａ R ２ ｂ SiO （４－ａ－ｂ）／２ (In the formula, R １ is an alkenyl group having 2 to 12 carbon atoms, R ２ is an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, provided that R ２ wherein at least 30 mol % of the aryl group or the aralkyl group is the aryl group or the aralkyl group, and "a" and "b" are positive numbers satisfying 1≦a+b≦2.5 and 0.001≦a / (a+b)≦0.2; and (B) a compound having at least two thiol groups in the molecule, in an amount such that the amount of thiol groups in the component is within a range of 0.2 to 2.0 mol per mol of all alkenyl groups in component (A); (C) 0.01 to 5 parts by mass of a photoradical initiator having a phosphorus atom; (D) a compound of the general formula: 【Chemistry 19】 (In the formula, R ３１ , R ３２ , R ３３ , R ３４ , R ３５ , R ３６ and R ３７ are the same or different and are selected from a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 12 carbon atoms; R ４ has the following general formula: -CH ２ CH(OH)CH ２ OR ５ (In the formula, R ５ and 0.001 to 0.5 parts by mass of a hydroxyphenyltriazine compound represented by the formula:

2. R in component (D) ３１ , R ３４ and R ３５ is a hydrogen atom, and R in component (D) ３２ , R ３３ , R ３６ and R ３７ The photocurable silicone composition according to claim 1, wherein is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

3. Component (D) is 2. The photocurable silicone composition of claim 1, which is a hydroxyphenyltriazine compound represented by the formula: 【Chemical 22】 4. The photocurable silicone composition of claim 1, wherein component (D) is a hydroxyphenyltriazine compound represented by the following formula: 【Chemistry 23】 5. The photocurable silicone composition of claim 1, wherein component (D) is a hydroxyphenyltriazine compound represented by the following formula: 【Chemistry 24】

6. A cured product obtained by irradiating the photocurable silicone composition according to any one of claims 1 to 5 with light.

7. The cured product according to claim 6 , wherein the cured product is laminated on the same substrate or between different substrates.

8. The cured product according to claim 6 , wherein the cured product is laminated on the same substrate or between different substrates in an optical device.

Images