Curable silicone composition and cured product thereof

Abstract

A curable silicone composition is provided. The composition comprises a mixture of (A) an epoxy-functional silicone resin having a monovalent aromatic hydrocarbon group, (B) an epoxy-functional silicone, and (C-1) an iodonium salt-type cationic photoinitiator and (C-2) a sulfonium salt-type cationic photoinitiator. The composition exhibits excellent curability upon UV irradiation and further heating, generally forming a cured product with excellent transparency.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the priority and all benefits of U.S. Provisional Patent Application No. 63 / 084,890, filed on September 29, 2020, the content of which is incorporated herein by reference.

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

Background Art

[0003] Epoxy - functional silicones are used in curable silicone compositions that can be cured by irradiating ultraviolet light ( "UV"). For example, Patent Document 1 discloses a curable silicone composition, which is an epoxy - functional silicone resin represented by the average unit formula (R3SiO 6~10 , 1~6 , 6~10 ) i (R2SiO 2 / 2 ) ii (RSiO 3 / 2 ) iii (SiO 4 / 2 ) iv wherein each R is an organic group independently selected from a monovalent aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, and a monovalent epoxy - substituted organic group, 0 ≦ i < 0.4, 0 < ii < 0.5, 0 < iii < 1, 0 ≦ iv < 0.4, 0.1 ≦ ii / iii ≦ 0.3, i + ii + iii + iv = 1, the resin has a number - average molecular weight of at least about 2,000, and at least about 15 mol% of the organic groups are monovalent aromatic hydrocarbon groups, and about 2 - about 50 mol% of the siloxane units have epoxy - substituted organic groups, and an epoxy - functional silicone oligomer represented by the general formula R”R’2SiO(R’2SiO) v SiR’2R”, wherein each R’ is C 1~8 ​​​​​​wherein each R″ is an epoxy-substituted organic group and “v” is 0 or a positive integer; and a cationic photoinitiator, wherein the composition can be cured by exposure to UV light.

[0004] However, such curable silicone compositions have problems in that the compositions do not cure sufficiently, or the transparency and mechanical properties of the cured product are insufficient.

[0005] Therefore, it is desirable to develop a curable silicone composition that has excellent curability by UV irradiation and further by heating to form a cured product with good transparency. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 2014 / 154626(A1) Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a curable silicone composition that has excellent curability by UV irradiation and then by heating to form a cured product with good transparency. Another object of the present invention is to provide a cured product with excellent transparency. [Means for solving the problem]

[0008] The curable silicone composition of the present invention comprises: (A) an epoxy-functional silicone resin represented by the average unit formula: [ka] In the formula, each R 1 is C 1~6A monovalent aliphatic hydrocarbon group, C 6~10 The same or different organic groups selected from a monovalent aromatic hydrocarbon group and a monovalent epoxy-substituted organic group, provided that at least about 15 mol% of all R 1 is a monovalent aromatic hydrocarbon group, and "a", "b", "c", and "d" satisfy the conditions of 0 ≦ a < 0.4, 0 < b < 0.5, 0 < c < 1, 0 ≦ d < 0.4, 0.1 ≦ b / c ≦ 0.6, and a + b + c + d = 1, and about 2 to about 30 mol% of all siloxane units have a monovalent epoxy-substituted organic group, an epoxy-functional silicone resin, and 6~10 (B) An epoxy-functional silicone represented by the following general formula:

Chemical formula

Chemical formula

[0009] In various embodiments, the monovalent epoxy-substituted organic group in component (A) is a group selected from a glycidoxyalkyl group, a 3,4-epoxycyclohexylalkyl group, and an epoxyalkyl group.

[0010] In various embodiments, the monovalent epoxy-substituted organic group in component (B) is a group selected from a glycidoxyalkyl group, a 3,4-epoxycyclohexylalkyl group, and an epoxyalkyl group.

[0011] In various embodiments, component (C-1) is typically an iodonium salt-type cationic photoinitiator having a structure represented by the following general formula: [ka] [In the formula, each R c are the same or different C 1~6 Alkyl group, C 6~24 Aryl group or substituted C 6~24 is an aryl group, and X - is a non-nucleophilic non-basic anion].

[0012] In various embodiments, component (C-2) is typically a sulfonium salt-type cationic photoinitiator having a structure represented by the following formula: [ka] or a sulfonium salt-type cationic photoinitiator having a structure represented by the following formula: [ka] [In the formula, each R c and X - is the same as above, and R d is an unsubstituted or heteroatom-substituted divalent hydrocarbon group.

[0013] In various embodiments, the mass ratio of component (C-1):component (C-2) is typically in the range of 1:10 to 10:1.

[0014] In various embodiments, the curable silicone composition further comprises (D) an adhesion promoter in an amount of about 0.01 to about 5 weight percent of the total weight of components (A), (B), (C), and (D).

[0015] The cured product of the present invention can be obtained by curing the above-described curable silicone composition. [Effects of the Invention]

[0016] The curable silicone composition of the present invention has excellent curability upon UV irradiation and further upon heating to form a cured product with excellent transparency. On the other hand, the cured product of the present invention has excellent transparency.

[0017] The terms "comprising" or "comprise" are used herein in their broadest sense to mean and encompass the ideas of "including," "include," "consisting essentially of," and "consisting 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 encompasses other similar or equivalent examples. As used herein, the term "about" serves to reasonably encompass or account for slight variations in a numerical value as determined by instrumental analysis or as a result of sample handling. 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 a numerical value even if not expressly stated. In general, as used herein, ">" means "greater than" or "over," "≥" means "at least" or "greater-than or equal to," "<" means "below" or "less-than," and "≤" means "at most" or "less-than or equal to."

[0018] As used herein, the term "epoxy-functional" or "epoxy-substituted" refers to a functional group in which the oxygen atoms of the epoxy substituent are directly bonded to two adjacent carbon atoms in a carbon chain or ring system. Examples of epoxy-substituted functional groups include, but are not limited to, glycidoxyalkyl groups such as 2-glycidoxyethyl, 3-glycidoxypropyl, and 4-glycidoxybutyl; (3,4-epoxycycloalkyl)alkyl groups such as 2-(3,4-epoxycyclohexyl)ethyl, 3-(3,4-epoxycyclohexyl)propyl, 2-(3,4-epoxy-3-methylcyclohexyl)-2-methylethyl, 2-(2,3-epoxycyclopentyl)ethyl, and 3-(2,3-epoxycyclopentyl)propyl; and epoxyalkyl groups such as 2,3-epoxypropyl, 3,4-epoxybutyl, and 4,5-epoxypentyl.

[0019] <Curable Silicone Composition> Component (A) is an epoxy-functional silicone resin represented by the following average siloxane unit formula: [ka]

[0020] In the formula, each R 1 is C 1~6 Monovalent aliphatic hydrocarbon radical, C 6~10 They are the same or different organic groups selected from monovalent aromatic hydrocarbon groups and monovalent epoxy-substituted organic groups.

[0021] C in component (A) 1~6 Examples of monovalent aliphatic hydrocarbon groups include C groups such as methyl, ethyl, propyl, butyl, and hexyl groups. 1~6 Alkyl groups; C such as vinyl, allyl, and hexenyl groups 2~6 alkenyl groups; and C groups such as 3-chloropropyl and 3,3,3-trifluoropropyl groups 1~6 Among these, methyl groups are generally preferred.

[0022] C in component (A) 6~10 Examples of the monovalent aromatic hydrocarbon group include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Among them, the phenyl group is generally preferred.

[0023] Examples of the monovalent epoxy-substituted organic group in component (A) include glycidoxyalkyl groups such as 3-glycidoxypropyl group, 4-glycidoxybutyl group, and 5-glycidoxypentyl group; 3,4-epoxycycloalkylalkyl groups such as 2-(3,4-epoxysilocyclohexyl)ethyl, 3-(3,4-epoxysilocyclohexyl)propyl, 2-(3,4-epoxy-3-methylsilocyclohexyl)-2-methylethyl, 2-(2,3-epoxysilopentyl)ethyl, and 3-(2,3-epoxysilopentyl)propyl; and epoxyalkyl groups such as 2,3-epoxypropyl group, 3,4-epoxybutyl group, and 4,5-epoxypentyl group. Among them, the 3,4-epoxycycloalkylalkyl group is generally preferred.

[0024] In component (A), all R 1 of at least about 15 mol%, optionally at least about 20 mol%, or optionally at least about 25 mol% is C 6~10 a monovalent aromatic hydrocarbon group. If the content of the monovalent aromatic hydrocarbon group is at least the above lower limit, the light transmittance of the cured product can be improved, and similarly its mechanical properties can also be improved.

[0025] In the formula, "a", "b", "c", and "d" are mole fractions and numbers that satisfy the conditions of 0 ≤ a < 0.4, 0 < b < 0.5, 0 < c < 1, 0 ≤ d < 0.4, 0.1 ≤ b / c ≤ 0.6, and a + b + c + d = 1, optionally a = 0, 0 < b < 0.5, 0 < c < 1, 0 ≤ d < 0.2, 0.1 ≤ b / c ≤ 0.6, and b + c + d = 1, or optionally a = 0, 0 < b < 0.5, 0 < c < 1, d = 0, 0.1 ≤ b / c ≤ 0.6, and b + c = 1. "a" is 0 ≤ a < 0.4, optionally 0 ≤ a < 0.2, or optionally a = 0, but it is (R 1 3SiO 1 / 2If the number of siloxane units is too large, the molecular weight of the epoxy-containing organopolysiloxane resin (A) decreases. 4 / 2 When the siloxane unit is introduced, the hardness of the cured product of the epoxy-functional silicone resin (A) increases significantly, and the cured product may become brittle. For this reason, "d" is 0≦d<0.4, optionally 0≦d<0.2, or optionally d=0. In addition, (R 1 2SiO 2 / 2 ) units and (R 1 SiO 3 / 2 The molar ratio "b / c" of (R ) units can be about 0.1 or more and about 0.6 or less. In some examples, deviations from this range in the production of epoxy-functional silicone resin (A) can result in insoluble by-products, reduced toughness making the product more susceptible to cracking, or a product with reduced strength and elasticity making it more susceptible to scratching. In some examples, the molar ratio "b / c" ranges from about 0.1 to about 0.6 or less. The epoxy-functional silicone resin (A) can be a mixture of (R ) units. 1 2SiO 2 / 2 ) siloxane units and (R 1 SiO 3 / 2 ) siloxane units, and its molecular structure is in most cases a network structure or a three-dimensional structure because the "b / c" molar ratio is greater than about 0.1 and less than about 0.6. Therefore, in the epoxy-functional silicone resin (A), (R 1 2SiO 2 / 2 ) siloxane units and ((R 1 SiO 3 / 2 ) siloxane units are present, but (R 1 3SiO 1 / 2 ) siloxane units and (SiO 4 / 2 The siloxane unit is an optional building block. That is, there may be an epoxy-functional silicone resin comprising the average unit formula: [ka]

[0026] In component (A), about 2 to about 30 mol%, optionally about 10 mol% to about 30 mol%, or optionally about 15 mol% to about 30 mol% of the siloxane units in the molecule contain epoxy-substituted organic groups. The presence of such siloxane units at or above the lower limit of the above range can improve crosslink density during curing. On the other hand, an amount below the upper limit of the above range can be advantageous because it can improve the light transmittance and heat resistance of the cured product. In the epoxy-functional monovalent hydrocarbon group, the epoxy group can be bonded to the silicon atom via an alkylene group, thereby avoiding direct bonding to the silicon atom. The epoxy-functional silicone resin (A) can be produced by well-known conventional manufacturing methods.

[0027] There is no particular limitation on the weight average molecular weight of the epoxy-functional silicone resin (A). However, in consideration of the toughness of the cured product and its solubility in organic solvents, in some embodiments, the molecular weight is about 10 3 More than or equal to approximately 10 6 In one embodiment, the epoxy-functional silicone resin (A) comprises a combination of two or more such epoxy-functional silicone resins having different amounts and types of epoxy-containing organic groups and monovalent hydrocarbon groups, or having different molecular weights.

[0028] Component (B) is an epoxy-functional silicone having the following general formula: [ka]

[0029] In the formula, each R 2 is C 1~6 Monovalent aliphatic hydrocarbon groups and C 6~10 are the same or different organic groups selected from monovalent aromatic hydrocarbon groups.

[0030] C in component (B) 1~6 Examples of monovalent aliphatic hydrocarbon groups include C groups such as methyl, ethyl, propyl, butyl, and hexyl groups. 1~6Alkyl groups; C such as vinyl, allyl, and hexenyl groups 2~6 alkenyl groups; and C groups such as 3-chloropropyl and 3,3,3-trifluoropropyl groups 1~6 Among these, methyl groups are generally preferred.

[0031] C in component (B) 6~10 Examples of monovalent aromatic hydrocarbon groups include phenyl, tolyl, xylyl, and naphthyl groups, with phenyl being generally preferred.

[0032] In the formula, each 1 are the same or different groups selected from monovalent epoxy-substituted organic groups and epoxy-functional siloxy groups represented by the general formula: [ka]

[0033] X 1 Examples of the monovalent epoxy-substituted organic group include glycidoxyalkyl groups such as 3-glycidoxypropyl, 4-glycidoxybutyl, and 5-glycidoxypentyl; 3,4-epoxycycloalkyl groups such as 2-(3,4-epoxycyclohexyl)ethyl, 3-(3,4-epoxycyclohexyl)propyl, 2-(3,4-epoxy-3-methylcyclohexyl)-2-methylethyl, 2-(2,3-epoxycyclopentyl)ethyl, and 3-(2,3-epoxycyclopentyl)propyl; and epoxyalkyl groups such as 2,3-epoxypropyl, 3,4-epoxybutyl, and 4,5-epoxypentyl. Among these, 3,4-epoxycycloalkylalkyl groups are generally preferred.

[0034] In the above general formula, each R 3 are the same or different C 1~6 R is a monovalent aliphatic hydrocarbon group. 3 C 1~6Examples of monovalent aliphatic hydrocarbon groups include C groups such as methyl, ethyl, propyl, butyl, and hexyl groups. 1~6 Alkyl groups; C such as vinyl, allyl, and hexenyl groups 2~6 alkenyl groups; and C groups such as 3-chloropropyl and 3,3,3-trifluoropropyl groups 1~6 Among these, methyl groups are generally preferred.

[0035] In the above general formula, R 4 is C 2~6 is an alkylene group. 4 C 2~6 Examples of alkylene groups include ethylene, methylethylene, propylene, butylene, and hexylene groups, with the ethylene group being generally preferred.

[0036] In the above general formula, X 2 is a monovalent epoxy-substituted organic group. 2 Examples of the monovalent epoxy-substituted organic group include glycidoxyalkyl groups such as 3-glycidoxypropyl, 4-glycidoxybutyl, and 5-glycidoxypentyl; 3,4-epoxycycloalkylalkyl groups such as 2-(3,4-epoxycyclohexyl)ethyl, 3-(3,4-epoxycyclohexyl)propyl, 2-(3,4-epoxy-3-methylcyclohexyl)-2-methylethyl, 2-(2,3-epoxycyclopentyl)ethyl, and 3-(2,3-epoxycyclopentyl)propyl; and epoxyalkyl groups such as 2,3-epoxypropyl, 3,4-epoxybutyl, and 4,5-epoxypentyl. Among these, 3,4-epoxycycloalkylalkyl groups are generally preferred.

[0037] In the above general formula, "x" is a number from about 0 to about 5, optionally from about 0 to about 2, or optionally about 0.

[0038] In the above general formula, "m" is a number from about 0 to about 100, optionally from about 0 to about 20, or optionally from about 0 to about 10. When "m" is equal to or less than the upper limit of the above range, the mechanical strength of the cured product can be improved.

[0039] The state of component (B) at 25°C is not limited, but it is generally a liquid. The viscosity of component (B) at 25°C is not limited, but it is generally within the range of about 5 to about 100 mPa·s. In this specification, viscosity is a value measured at 23±2°C using a Brookfield viscometer in accordance with ASTM D 1084.

[0040] The content of component (B) is about 5% to about 40% by mass, optionally about 10% to about 40% by mass, optionally about 10% to about 35% by mass, or optionally about 10% to about 30% by mass of the total mass of components (A), (B), and (C). If the content of component (B) is at or above the lower limit of the above range, the flexibility and impact strength of the cured product can be improved. On the other hand, if the content is at or below the upper limit of the above range, the toughness and tensile strength of the cured product can be improved.

[0041] Component (C) is a cationic photoinitiator used as a photoinitiator for epoxy-functional silicones, and is a mixture of cationic photoinitiators including (C-1) an iodonium salt-type cationic photoinitiator and (C-2) a sulfonium salt-type cationic photoinitiator.

[0042] The iodonium salt cationic photoinitiator of component (C-1) is not limited, but is preferably a compound having a structure represented by the following general formula: [ka]

[0043] In the formula, R c are methyl, ethyl, propyl, butyl, and other C 1~6 Alkyl groups: phenyl, naphthyl, biphenyl, tolyl, propylphenyl, decylphenyl, dodecylphenyl, and other C 6~24or an alkyl group, an aryl group, an alkoxy group, a mercapto atom, an oxygen atom, or another heteroatom-substituted aryl group, wherein X - is SbF6 - , AsF6 - , PF6 - , BF4 - , B(C6F5)4 - , HSO4 - , ClO4 - , CF3SO3 - , nonafluorobutanesulfonate, tris(pentafluoroethyl)trifluorophosphate, tris(heptafluoropropyl)trifluorophosphate, tris(nonafluoroisobutyl)trifluorophosphate, bis(nonafluorobutylisobutyl)tetrafluorophosphate, and other non-nucleophilic non-basic anions.

[0044] In the formula, each R C is preferably C 6~24 It is an aryl group, or an aryl group substituted with an alkyl group or an alkoxy group. Specific examples of the cation portion of the diaryliodonium salt include diphenyliodonium, 4-isopropyl-4'-methyldiphenyliodonium, 4-methyl-4'-methyl-propyldiphenyliodonium, bis(4-tert-butylphenyl)iodonium, and 4-methoxyphenylphenyliodonium.

[0045] Specific examples of the iodonium salt type cationic photoinitiator include compounds represented by the following formula: [ka] [ka] [ka] In the above formula, "Me", "i-Pr", and "t-Bu" represent a methyl group, an isopropyl group, and a tert-butyl group, respectively; X - is the same as above.

[0046] Specific trade names of iodonium salt-type cationic photoinitiators include TR-PAG-30101, 30201, 30408, 30401s, and 31102 (manufactured by TRONYL).

[0047] On the other hand, the sulfonium salt type cationic photoinitiator of component (C-2) is not limited, but is preferably a compound having a structure represented by the following formula: [ka] or a compound having a structure represented by the formula: [ka]

[0048] In the formula, each R c and X - is the same as above.

[0049] In the formula, R d methylene, ethylene, propylene, butylene, and other C 1~6 Unsubstituted or heteroatom-substituted divalent hydrocarbon groups such as alkylene groups; phenylene groups, naphthylene groups, biphenylene groups, tolylene groups, propylphenylene groups, decylphenylene groups, dodecylphenylene groups, and other C 6~24 It may represent an arylene group; as well as a phenyl-thio-phenylene group, a phenylene-oxy-phenylene group, or a divalent hydrocarbon group substituted with mercapto, oxygen, or other heteroatoms.

[0050] Specific examples of the cation portion of the triarylsulfonium salt include triphenylsulfonium, diphenyl-4-methylphenylsulfonium, tris(4-methylphenyl)sulfonium, diphenyl-2,4,6-trimethylphenylsulfonium, and 4-(phenylthio)phenyldiphenylsulfonium.

[0051] In the formula, each R C is preferably C 6~24 an aryl group, or an alkyl group, an aryl group, or a mercapto-substituted aryl group; R d is preferably a thio-substituted divalent group. Examples of the iodonium salt type cationic photoinitiator include compounds represented by the following formula: [ka] [ka] [ka] [ka] [ka] In the above formula, "Me" represents a methyl group, and X - is the same as above, and each R 5 are the same or different alkyl groups, aryl groups, alkoxy groups, or mercapto atoms, oxygen atoms, or other heteroatom-containing organic groups.

[0052] Specific trade names of sulfonium salt-type cationic photoinitiators include CPI (registered trademark)-100P, 101A, 200K, 210S, 310B, and 410S (manufactured by Sunapro Inc.), CPI-310B, and TR-PAG-21608 (manufactured by TRONYL), etc.

[0053] In the component (C), the mass ratio of component (C-1) to component (C-2) is not limited, but is typically in the range of 1:10 to 10:1, or 1:5 to 5:1, because a mass ratio within this range results in the composition exhibiting excellent curability by ultraviolet light and subsequent heating.

[0054] Furthermore, the composition may contain a cationic photoinitiator other than the components (C-1) and (C-2) as long as it does not impair the objectives of the present invention. Other cationic photoinitiators known to those skilled in the art, such as selenonium salts, phosphonium salts, diazonium salts, paratoluenesulfonates, trichloromethyl-substituted triazines, and trichloromethyl-substituted benzenes, may also be used. Examples of selenonium salts include those represented by the formula R c 3Se + X - Examples of phosphonium salts include salts represented by the formula R c 4P + X - Examples of diazonium salts include salts represented by the formula R c N2 + X - and R c and X - is R c 3S + X - and examples of paratoluenesulfonic acid salts include those of the formula CH3C6H4SO3R c1 In the formula, R c1 represents an organic group containing an electron-withdrawing group such as a benzoylphenylmethyl group or a phthalimide group. Examples of trichloromethyl-substituted triazines include [CC13]2C3N3R c2 In the formula, R c2 represents phenyl, substituted or unsubstituted phenylethyl, substituted or unsubstituted furanylethynyl, and other electron-withdrawing groups. Examples of trichloromethyl-substituted benzenes include CCl3C6H3R c R c3In the formula, R c is R c 3S + X - is the same as described herein for R c3 represents halogen groups, halogen-substituted alkyl groups, and other halogen-containing groups.

[0055] Examples of photoinitiators include, for example, triphenylsulfonium tetrafluoroborate, di(p-tert-butylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium hexafluoroantimonate, 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate salt, and p-chlorophenyldiazonium tetrafluoroborate.

[0056] The content of component (C) is about 0.2% to about 2% by mass, optionally about 0.2% to about 1% by mass, or optionally about 0.2% to about 0.8% by mass, of the total mass of components (A), (B), and (C). If the content of component (C) is at or above the lower limit of the above range, the curable silicone composition will be sufficiently cured. On the other hand, if the content is at or below the upper limit of the above range, the optical performance of the cured product will be improved.

[0057] The present composition contains the above-mentioned components (A) to (C), and may also contain (D) an adhesion promoter, and / or a photosensitizer, and / or an alcohol, and / or an inorganic filler in order to impart better mechanical strength to a cured product of the present composition.

[0058] Component (D) is an adhesion promoter. Examples of adhesion promoters include epoxy-functional alkoxysilanes such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyldiethoxysilane, and combinations thereof; unsaturated alkoxysilanes such as vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hexenyltrimethoxysilane, undecylenyltrimethoxysilane, 3-methacryloyloxysilane, methyltrimethoxysilane, methyltriethoxy ... Examples of suitable adhesion promoters include hydroxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, and combinations thereof; and epoxy-functional siloxanes having silicon-bonded alkoxy groups, such as the reaction product of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane (e.g., any of those described above), or a physical blend of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane. The adhesion promoter may include a combination of an epoxy-functional alkoxysilane and an epoxy-functional siloxane. For example, the adhesion promoter is exemplified by a mixture of 3-glycidoxypropyltrimethoxysilane with the reaction product of a hydroxy-terminated methylvinylsiloxane and 3-glycidoxypropyltrimethoxysilane, or a mixture of 3-glycidoxypropyltrimethoxysilane with a hydroxy-terminated methylvinylsiloxane, or a mixture of 3-glycidoxypropyltrimethoxysilane with a hydroxy-terminated methylvinyl / dimethylsiloxane copolymer.

[0059] The content of component (D) is not limited, but is generally about 0.01 to about 5 mass % of the total mass of components (A), (B), (C), and (D), or optionally about 0.1 to about 2 mass %. If the content of component (D) is equal to or greater than the lower limit of the above range, the adhesiveness of the cured product can be improved. On the other hand, if the content is equal to or less than the upper limit of the above range, the mechanical properties of the cured product can be improved.

[0060] Examples of photosensitizers include isopropyl-9H-thioxanthen-9-one, anthrone, 1-hydroxycyclohexyl-phenyl ketone, 2,4-diethyl-9H-thioxanthen-9-one, 2-isopropylthioxanthene, 2-hydroxy-2-methyl-phenylpropan-1-one, 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT), pentaerythritol tetrakis[3-(3,5-di-tert-butyl ether] ... octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylenebis[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 Examples include 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].

[0061] The content of the photosensitizer is not limited, but is generally within the range of about 0.001 to about 1% by mass, optionally about 0.005 to about 0.5% by mass, or optionally about 0.005 to about 0.1% by mass, of the total mass of components (A), (B), (C), and the photosensitizer. If the content of the photosensitizer is equal to or greater than the lower limit of the above range, the curability of the cured product may be improved. On the other hand, if the content is equal to or less than the upper limit of the above range, the optical clearance of the cured product may be improved.

[0062] Examples of alcohols include monohydric alcohols such as ethyl alcohol, isopropyl alcohol, isobutyl alcohol, 1-decanol, 1-dodecanol, 1-octanol, oleyl alcohol, 1-hexadecanol, and stearyl alcohol; and polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, 1,10-decanediol, glycerol, and pentaerythritol.

[0063] The content of the alcohol is not limited, but is generally about 0.01 to about 10% by mass of the total mass of components (A), (B), (C), and the alcohol, or optionally about 0.1 to about 10% by mass.

[0064] Inorganic fillers increase the mechanical strength of the cured product. Examples of fillers include one or more of micronized or untreated precipitated or fumed silica, precipitated or ground calcium carbonate, zinc carbonate, clays such as micronized kaolin, ground quartz, aluminum hydroxide, zirconium silicate, diatomaceous earth, wollastonite, pyrophyllate, and metal oxides such as fumed or precipitated titanium dioxide, cerium oxide, magnesium oxide powder, zinc oxide, and iron oxide.

[0065] The amount of filler included is not limited, but is generally within the range of about 1 to about 95% by weight, optionally within the range of about 5 to about 95% by weight, or optionally within the range of about 5 to about 90% by weight of the total weight of components (A), (B), (C), and the filler.

[0066] The present compositions can be cured by irradiation with UV light (i.e., ultraviolet ("UV") light). 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 exposure dose is generally about 5 to about 6,000 mJ / cm. 2 or optionally within the range of about 10 to about 4,000 mJ / cm 2 is within the range.

[0067] <Cured product> When the composition is cured by exposure to UV light, it forms a cured product. The cured product of the present invention has a hardness, as measured using the Shore D hardness scale specified in ASTM D2240, of at least 20 to 95, typically at least 30 to 80, and more typically at least 30 to 70. The reason for this is as follows: if the hardness of the cured product is below the lower limit of the specified range, the strength of the cured product may be insufficient. On the other hand, if the hardness exceeds the upper limit of the specified range, the flexibility of the target cured product tends to be insufficient.

[0068] To exhibit satisfactory flexibility, the cured product may have an elongation of at least 10%, as specified in ASTM D412, because below the specified range the cured product will have insufficient flexibility.

[0069] Because the cured products of the present invention are flexible and highly transparent, they are useful as optical members or parts that are transparent to light, such as visible light, infrared light, ultraviolet light, far ultraviolet light, X-rays, and lasers. The cured products of the present invention are also useful as optical members or parts that must be flexible, for example, for use in a bent or curved state, and as optical members or parts for devices involving high-energy, high-output light. Additionally, by forming the cured silicone material of the present invention into a single article or body together with any of a variety of substrates to produce a composite material, it is possible to produce an article or part having a flexible, highly transparent cured layer, and the cured layer can be expected to provide impact and stress relief functions. [Example]

[0070] The curable silicone composition and cured product of the present invention will now be described in detail using examples and comparative examples. It should be noted that in the formulas, "Me," "Pr," "Vi," "Ph," "Gly," and "Ep" represent methyl, propyl, vinyl, and phenyl groups, respectively; 3-glycidoxypropyl, and 2-(3,4-epoxycyclohexyl)ethyl groups. The structure of the epoxy-functional silicone resin used in the examples is: 13C NMR and 29 The molecular weights of the epoxy-functional silicone resins were determined by Si NMR measurements. The weight average molecular weights of the epoxy-functional silicone resins were calculated using GPC based on comparison with polystyrene standards. The viscosities of the epoxy-functional silicones and silicone resins were measured as follows.

[0071] <Viscosity> The viscosity at 23±2° C. was measured according to ASTM D 1084 “Standard Test Methods for Viscosity of Adhesives” using a Brookfield HA or HB Type rotational viscometer (using spindle #52, 5 rpm).

[0072] <Examples 1 to 2 and Comparative Examples 1 to 3> The curable silicone compositions (% by weight) shown in Table 1 were prepared using the following components.

[0073] The following epoxy-functional silicone resin was used as component (A): (a1): An epoxy-functional silicone resin having a weight average molecular weight of 2,000 to 6,000 and represented by the following average unit formula: [ka]

[0074] The following epoxy-functional silicones were used as component (B): (b1): An epoxy-functional silicone having a viscosity of 40 mPa·s, a weight average molecular weight of 382, ​​and represented by the following formula: [ka]

[0075] The following cationic photoinitiators were used as component (C-1): (c1): 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate represented by the following formula: [ka] (TRONYL TR-PAG-30408)

[0076] The following cationic photoinitiator was used as component (C-2): (c2): Triarylsulfonium borate having a structure represented by the following formula: [ka] (TRONYL CPI-310B) (c3): Triarylsulfonium tetrakis(pentafluorophenyl)borate salt represented by the following formula: [ka] (TRONYL TR-PAG-21608)

[0077] The following component was used as component (D): (d1): A silicone resin having a viscosity of 4800 mPa·s, a weight average molecular weight of 2,200, and represented by the following average unit formula: [ka]

[0078] The following components were used as photosensitizers: (e1): 2-isopropoxythioxanthone

[0079] <Curability of Curable Silicone Composition> Approximately 0.1 to 3 g of each curable silicone composition was placed on a glass slide. After leveling the surface with a bar coater, the composition was applied under 5000 mW / cm 2 or a metal halide UV lamp with a D-type bulb of 365 nm, 5000 mJ / cm 2The curable silicone composition was cured by passing it through an LED. The cured product was evaluated as follows. The properties of the cured product are shown in Table 1. ○○: Rapid curing (can be cured even with lower light intensity) ○: Hardened ×: Not cured

[0080] <Heat curing at 135°C for 1 hour> Approximately 0.1 to 3 g of each curable silicone composition was placed on a glass slide. After leveling the surface with a bar coater, the curable silicone composition was cured in a convection oven set at 135°C for 1 hour. The cured products were evaluated as follows. The properties of the cured products are shown in Table 1. ○○: Rapid curing (can be cured even with lower light intensity) ○: Hardened ×: Not cured

[0081] Curing in shadow areas: UV (LED 365 nm, 5000 mJ / cm 2 ) + Heating (135℃ / 1 hour) Approximately 0.1 to 3 g of each curable silicone composition was placed on a black acrylic substrate. After leveling the surface with a bar coater, a portion of the surface was covered with the black acrylic substrate to create a shadow area. The LED lamp was 365 nm, 5000 mJ / cm. 2 The curable silicone composition was cured by passing it through a vacuum oven, followed by thermal curing (135°C / 1 hour). The cured product in the shadow area was evaluated as follows. The properties of the cured product are shown in Table 1. ○○: Rapid curing (can be cured even with lower light intensity) ○: Hardened ×: Not cured

[0082] <Optical performance (yellow index <5)> Samples with a thickness of approximately 150 micrometers were prepared using a sandwich glass structure. The curable silicone composition was cured by UV, heat, or UV + heat. The yellow index (ASTM D1925) was measured using a spectrophotometer. The cured product was evaluated in the shadow area as follows. The properties of the cured product are shown in Table 1. ○: Yellow index <5 ×: Yellow index ≥ 5

[0083] [Table 1] [Industrial Applicability]

[0084] The curable silicone composition of the present invention can be cured by exposure to UV light, and is therefore useful as a variety of adhesives, encapsulants, coatings, and the like for electrical and electronic components. The present invention includes the following aspects. [1] A curable silicone composition comprising: (A) An epoxy-functional silicone resin represented by the following average unit formula, [ka] wherein each R 1 is the same or different organic group selected from a monovalent aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, and a monovalent epoxy-substituted organic group, provided that at least about 15 mol% of all R 1~6 is a C 6~10 monovalent aromatic hydrocarbon group, and "a", "b", "c", and "d" are numbers satisfying the conditions of 0 ≦ a < 0.4, 0 < b < 0.5, 0 < c < 1, 0 ≦ d < 0.4, 0.1 ≦ b / c ≦ 0.6, and a + b + c + d = 1, and about 2 to about 30 mol% of all siloxane units have a monovalent epoxy-substituted organic group, an epoxy-functional silicone resin; and 1 (B) An epoxy-functional silicone represented by the following general formula, 6~10 wherein each R is the same or different organic group selected from a C [ka] monovalent aliphatic hydrocarbon group and a C 2 monovalent aromatic hydrocarbon group, each X 1~6 is the same or different group selected from a monovalent epoxy-substituted organic group and an epoxy-functional siloxy group represented by the following general formula, 6~10 wherein each R 1 is the same or different C [ka] monovalent aliphatic hydrocarbon group, R 3 is a C 1~6 alkylene group, X 4 is a monovalent epoxy-substituted organic group, "x" is a number from about 0 to about 5, "m" is a number from about 0 to about 100, and is present in an amount of about 5% to about 40% by mass of the total mass of components (A), (B), and (C), an epoxy-functional silicone; and 2~6 (C) A mixture of cationic photoinitiators comprising 2 (C-1) an iodonium salt type cationic photoinitiator, and (C-2) a sulfonium salt type cationic photoinitiator, present in an amount of about 0.2% to about 2% by mass of the total mass of components (A), (B), and (C), a mixture of cationic photoinitiators; and a curable silicone composition containing the same. [2] The curable silicone composition according to [1] above, wherein the monovalent epoxy-substituted organic group in component (A) is a group selected from a glycidoxyalkyl group, a 3,4-epoxycyclohexylalkyl group, and an epoxyalkyl group. [3] The curable silicone composition according to [1] above, wherein the monovalent epoxy-substituted organic group in component (B) is a group selected from a glycidoxyalkyl group, a 3,4-epoxycyclohexylalkyl group, and an epoxyalkyl group. ​ ​ [4] The component (C-1) is an iodonium salt-type cationic photoinitiator having a structure represented by the following general formula:

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Claims

1. 1. A curable silicone composition comprising: (A) an epoxy-functional silicone resin represented by the average unit formula: 【Chemistry 1】 In the formula, each R １ But C １～６ Monovalent aliphatic hydrocarbon group, C ６～１０ are the same or different organic groups selected from monovalent aromatic hydrocarbon groups and monovalent epoxy-substituted organic groups, provided that all R １ At least 15 mol % of ６～１０ an epoxy-functional silicone resin in which "a," "b," "c," and "d" are monovalent aromatic hydrocarbon groups, and are numbers that satisfy the conditions: 0≦a<0.4, 0<b<0.5, 0<c<1, 0≦d<0.4, 0.1≦b / c≦0.6, and a+b+c+d=1, and 2 to 30 mol % of all siloxane units have monovalent epoxy-substituted organic groups; (B) an epoxy-functional silicone represented by the general formula: 【Chemistry 2】 In the formula, each R ２ But C １～６ Monovalent aliphatic hydrocarbon groups and C ６～１０ are the same or different organic groups selected from monovalent aromatic hydrocarbon groups, and each X １ are the same or different groups selected from glycidoxyalkyl groups, 3,4-epoxycycloalkylalkyl groups, epoxyalkyl groups, and epoxy-functional siloxy groups represented by the general formula: 【Transformation 3】 In the formula, each R ３ However, the same or different C １～６ is a monovalent aliphatic hydrocarbon group, R ４ But C ２～６ is an alkylene group, and X ２ is a monovalent epoxy-substituted organic group, "x" is a number from 0 to 5, and "m" is a number from 0 to 100, in an amount of 5% to 40% by weight of the total weight of components (A), (B), and (C); (C) a mixture of cationic photoinitiators, (C-1) an iodonium salt-type cationic photoinitiator, and (C-2) a mixture of cationic photoinitiators containing a sulfonium salt-type cationic photoinitiator in an amount of 0.2% by mass to 2% by mass of the total mass of components (A), (B), and (C); 1. A curable silicone composition comprising:

2. 2. The curable silicone composition according to claim 1, wherein the monovalent epoxy-substituted organic group in component (A) is a group selected from a glycidoxyalkyl group, a 3,4-epoxycyclohexylalkyl group, and an epoxyalkyl group.

3. The component (C-1) is an iodonium salt-type cationic photoinitiator having a structure represented by the following general formula: 【Chemistry 4】 [In the formula, each R ｃ are the same or different C １～６ Alkyl group, C ６～２４ Aryl group, or substituted C ６～２４ is an aryl group, and X － is a non-nucleophilic, non-basic anion.

4. The component (C-2) is a sulfonium salt-type cationic photoinitiator having a structure represented by the following general formula: 【Transformation 5】 or a sulfonium salt-type cationic photoinitiator having a structure represented by the following general formula: 【Transformation 6】 wherein each R c is the same or different C 1-6 alkyl, C 6-24 aryl, or substituted C 6-24 aryl; X − is a non-nucleophilic non-basic anion; and R ｄ and n is an unsubstituted or heteroatom-substituted divalent hydrocarbon group.

5. 2. The curable silicone composition according to claim 1, wherein the mass ratio of component (C-1):component (C-2) is in the range of 1:10 to 10:

1.

6. The curable silicone composition according to any one of claims 1 to 5, A curable silicone composition further comprising, as component (D), an adhesion promoter in an amount of 0.01 to 5% by weight based on the total weight of components (A), (B), (C), and (D).

7. A cured product obtained by curing the curable silicone composition according to any one of claims 1 to 6.

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