Ultraviolet curable silicone composition and cured product thereof

Abstract

(A) an organopolysiloxane having a main chain composed of repeating diorganosiloxane units, a group represented by formula (1) at one or both ends, and 5% or more of the total number of monovalent organic groups bonded to Si atoms being aromatic groups, (R 1 is a monovalent hydrocarbon group, R 2 is an oxygen atom or an alkylene group, R 3 is an acryloyloxyalkyl group, etc., p is a number satisfying 0≤p≤10, a is a number satisfying 1≤a≤3, and the dotted line is a bonding end) (B) is obtained by formula (2) (R 1 ~R 3 , a, p are the same as above) unit, (b) R 1 3SiO 1 / 2 Unit, (c)R 1 2SiO 2 / 2 unit, (d)SiO 4 / 2 The composition of an organopolysiloxane resin having a unit structure in which 5% or more of the total number of monovalent organic groups bonded to Si atoms are aromatic groups and (C) a photopolymerization initiator has good ultraviolet curing properties and can form a cured product with excellent refractive index, transparency, and heat resistance. #imgabs0#

Description

Technical Field

[0001] The present invention relates to an ultraviolet curable organosilicon composition and a cured product thereof. Background Art

[0002] In recent years, ultraviolet curing materials that have a high refractive index and transparency and cure in a short time by ultraviolet irradiation have attracted attention as materials for lenses having fine shapes.

[0003] Lenses are typically molded using a die-cut process, so materials that cure instantly upon UV exposure are highly advantageous for lens production efficiency. Furthermore, UV-curable materials do not require heating, so changes in lens dimensions due to thermal shrinkage are not a concern.

[0004] As such materials, known ultraviolet curing acrylic materials (Patent Document 1) and epoxy materials (Patent Document 2) are known. However, these materials have poor heat resistance due to their main skeleton being an organic polymer, and are not suitable for applications requiring long-term heat resistance or reflow resistance.

[0005] Meanwhile, a silicone adhesive formulated with a photoactive platinum complex catalyst has been proposed as a UV-curable material with excellent heat resistance (Patent Document 3). However, this material requires time to fully cure and requires heating after UV irradiation, making it unsuitable for lens molding.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 6124379

[0009] Patent Document 2: Japanese Patent No. 4984111

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2015-110752 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] The present invention has been made in view of the above circumstances, and an object thereof is to provide an ultraviolet-curable silicone composition that can form a cured product having good curability by ultraviolet light and excellent refractive index, transparency and heat resistance.

[0013] Means for solving problems

[0014] The present inventors have conducted intensive studies to achieve the above-mentioned objectives and have discovered that by using a specific organopolysiloxane having a (meth)acryloyloxy group-containing group and a specific organopolysiloxane resin having a (meth)acryloyloxy group-containing group, a cured organosilicon product that is rapidly cured by ultraviolet irradiation can be obtained, exhibiting excellent refractive index, transparency, and heat resistance. This has led to the completion of the present invention.

[0015] That is, the present invention provides

[0016] 1. An ultraviolet curable silicone composition comprising:

[0017] (A) an organopolysiloxane having a main chain composed of repeating diorganosiloxane units, having a group represented by the following general formula (1) at one or both ends, and 5% or more of the total number of monovalent organic groups bonded to silicon atoms being aromatic groups,

[0018] [Chemistry 1]

[0019]

[0020] (Where R 1 independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms, R 2 represents an oxygen atom or an alkylene group having 1 to 20 carbon atoms, R 3 Each independently represents an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkoxy group, or a methacryloyloxyalkoxy group, p represents a number satisfying 0≤p≤10, a represents a number satisfying 1≤a≤3, and a dotted line represents a bonding end.

[0021] (B) an organopolysiloxane resin comprising (a) the following general formula (2):

[0022] [Chemistry 2]

[0023]

[0024] (Where R 1 、R 2 、R 3 , a and p have the same meanings as above.)

[0025] The unit represented by (b) R 1 3SiO 1 / 2 Unit (where R 1 represents the same meaning as above), (c) R 1 2SiO 2 / 2 Unit (where R 1 represents the same meaning as above), and (d) SiO 4 / 2 Unit composition, 5% or more of the total number of monovalent organic groups bonded to silicon atoms are aromatic groups, and

[0026] (C) a photopolymerization initiator;

[0027] 2. The UV-curable silicone composition according to 1, further comprising (D) a monofunctional (meth)acrylate compound not containing a siloxane structure;

[0028] 3. The ultraviolet curable silicone composition according to 1 or 2, comprising (E) a silane coupling agent having a (meth)acryloyloxy group;

[0029] 4. A cured product, which is a cured product of the ultraviolet curable silicone composition according to any one of 1 to 3;

[0030] 5. A lens comprising the cured product according to 4.

[0031] Effects of the Invention

[0032] The ultraviolet curable silicone composition of the present invention has good curability by ultraviolet irradiation, and its cured product has a high refractive index and transparency, and is also excellent in transparency and heat resistance, and is therefore suitable as a material for lens molding. DETAILED DESCRIPTION

[0033] Hereinafter, the present invention will be described in detail.

[0034] The ultraviolet curable silicone composition according to the present invention contains the following components (A) to (C).

[0035] (A) an organopolysiloxane having a main chain composed of a repeating diorganosiloxane unit, having a group represented by the following general formula (1) at one or both ends, and 5% or more of the total number of monovalent organic groups bonded to silicon atoms being aromatic groups

[0036] (B) an organopolysiloxane resin comprising (a) a unit represented by the following general formula (2), (b) R 1 3SiO 1 / 2 Unit, (c)R 1 2SiO 2 / 2 unit and (d)SiO 4 / 2 Unit composition, 5% or more of the total number of monovalent organic groups bonded to silicon atoms are aromatic groups

[0037] (C) Photopolymerization initiator

[0038] (A) Organopolysiloxane

[0039] The component (A) used in the present invention is an organopolysiloxane having a main chain composed of repeating diorganosiloxane units and having a group represented by the following general formula (1) at one or both terminals.

[0040] [Chemistry 3]

[0041]

[0042] In formula (1), R 1 Each of them is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, excluding an aliphatic unsaturated group.

[0043] R 2 It is an oxygen atom or an alkylene group having 1 to 20 carbon atoms, preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms.

[0044] R 3 Each is independently an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkoxy group, or a methacryloyloxyalkoxy group.

[0045] In formula (1), R 1 The monovalent hydrocarbon group having 1 to 20 carbon atoms may be linear, branched, or cyclic, and examples thereof include alkyl, alkenyl, aryl, and aralkyl groups.

[0046] Specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, and n-decyl; alkenyl groups such as vinyl, allyl (2-propenyl), 1-propenyl, isopropenyl, and butenyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl, phenylethyl, and phenylpropyl.

[0047] In addition, part or all of the hydrogen atoms bonded to the carbon atoms of these monovalent hydrocarbon groups may be substituted by halogen atoms such as chlorine, fluorine, and bromine, or other substituents such as cyano groups. Specific examples thereof include halogen-substituted hydrocarbon groups such as chloromethyl, bromoethyl, and trifluoropropyl; and cyano-substituted hydrocarbon groups such as cyanoethyl.

[0048] Among them, as R 1 , preferably an alkyl group having 1 to 5 carbon atoms or a phenyl group, more preferably a methyl group, an ethyl group or a phenyl group.

[0049] R 2 The alkylene group having 1 to 20 carbon atoms may be any of linear, branched, and cyclic groups, and specific examples thereof include methylene, ethylene, propylene, trimethylene, tetramethylene, isobutylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, and decylene.

[0050] Among them, as R 2 , preferably an oxygen atom, a methylene group, an ethylene group, or a trimethylene group, and more preferably an oxygen atom or an ethylene group.

[0051] As R 3 The number of carbon atoms of the alkyl group (alkylene group) in the acryloyloxyalkyl group, methacryloyloxyalkyl group, acryloyloxyalkoxy group, or methacryloyloxyalkoxy group is not particularly limited, but is preferably 1 to 10, more preferably 1 to 5. Specific examples of these alkyl groups include R 1 Among the groups exemplified in , the groups have 1 to 10 carbon atoms.

[0052] As R 3 Specific examples of include groups represented by the following formulae, but are not limited to these.

[0053] [Chemistry 4]

[0054]

[0055] In the above formula, b is a number satisfying 1≤b≤4, preferably a number satisfying 1≤b≤3.

[0056] R 5 It is an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 5 carbon atoms. 5 Specific examples include R 2 Among the groups exemplified in , those having 1 to 10 carbon atoms are preferably methylene, ethylene, and trimethylene, and more preferably ethylene.

[0057] In formula (1), p is a number satisfying 0≤p≤10, preferably 0≤p≤5, more preferably 0 or 1. a is a number satisfying 1≤a≤3, preferably 1 or 2.

[0058] The bonding position of the group represented by the general formula (1) in the organopolysiloxane molecule of the component (A) may be at one end or both ends of the molecular chain. In addition, the group represented by the general formula (1) may be present at a non-terminal portion of the molecular chain (i.e., in the middle of the molecular chain or on a side chain of the molecular chain). However, from the perspective of the mechanical properties of the resulting cured product, it is preferred that the group represented by the general formula (1) be present only at the terminal portion.

[0059] In the organopolysiloxane molecule of the component (A), the organic group bonded to the silicon atom other than the group represented by the general formula (1) can be exemplified by the group represented by the general formula (1) above. 1 Among the similar groups, monovalent hydrocarbon groups having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, excluding aliphatic unsaturated groups are particularly preferred.

[0060] As specific examples thereof, the above-mentioned R 1 The same groups as those exemplified in , from the viewpoint of ease of synthesis, are preferably alkyl groups and aryl groups, and more preferably methyl groups and phenyl groups.

[0061] Furthermore, of the total number of monovalent organic groups bonded to silicon atoms in component (A), 5% or more, preferably 10% or more, are aryl groups. If the aryl group content is less than 5%, the resulting cured product will have a low refractive index. Phenyl groups are preferred as aryl groups.

[0062] To further improve the workability of the composition and the mechanical properties of the cured product, the viscosity of the organopolysiloxane (component (A)) at 25°C is preferably 10 to 100,000 mPa·s, more preferably 10 to 50,000 mPa·s. This viscosity range generally corresponds to approximately 10 to 2,000, preferably approximately 50 to 1,100, expressed as a number average degree of polymerization, for linear organopolysiloxanes.

[0063] In the present invention, the viscosity can be measured using a rotational viscometer (for example, BL type, BH type, BS type, cone-plate type, rheometer, etc.) (the same applies hereinafter).

[0064] In the present invention, the degree of polymerization (or molecular weight) can be determined as the polystyrene-equivalent number average degree of polymerization (or number average molecular weight) in gel permeation chromatography (GPC) analysis using toluene or the like as an elution solvent (the same applies hereinafter).

[0065] Specific examples of the organopolysiloxane of the component (A) include organopolysiloxanes shown in (3) to (6) below, but the present invention is not limited to these.

[0066] [Chemistry 5]

[0067]

[0068]

[0069]

[0070]

[0071] (Where R 1 、R 5 and b have the same meanings as above, Me represents a methyl group, and n is a number such that the viscosity of the organopolysiloxane is the above value, preferably 1 to 800, more preferably 50 to 600.)

[0072] Such organopolysiloxanes can be produced by known methods. For example, the polysiloxane represented by formula (3) can be obtained by reacting 2-hydroxyethyl acrylate with a dimethylsiloxane-diphenylsiloxane copolymer terminated at both ends with dimethylvinylsiloxy groups and a hydrosilylation reaction product of chlorodimethylsilane.

[0073] The organopolysiloxane represented by the above formulae (4) and (5) is obtained as a hydrosilylation reaction product of a dimethylsiloxane-diphenylsiloxane copolymer terminated with dimethylvinylsiloxy groups at both ends and 3-(1,1,3,3-tetramethyldisiloxyl)propyl methacrylate (CAS No. 96474-12-3).

[0074] The organopolysiloxane represented by the above formula (5) can be obtained by reacting 2-hydroxyethyl acrylate with a hydrosilylation reaction product of a dimethylsiloxane-diphenylsiloxane copolymer terminated with dimethylvinylsiloxy groups at both ends and dichloromethylsilane.

[0075] (B) Organopolysiloxane resin

[0076] The component (B) is one of the crosslinking components of the present composition and has (a) a unit (M) represented by the following formula (2): A Unit), (b) R 1 3SiO 1 / 2 Unit, (c)R 1 2SiO 2 / 2 unit and (d)SiO 4 / 2 An organopolysiloxane resin having a (meth)acryloyloxy group-containing unit.

[0077] [Chemistry 6]

[0078]

[0079] It should be noted that R in the formula (2) of the unit (a) 1 、R 2 、R 3 , a and p, and R in units (b) and (c) 1 Means the same as above.

[0080] Of the total number of monovalent organic groups bonded to silicon atoms in component (B), 5% or more, preferably 10% or more, of these groups are aryl groups. If the proportion of aryl groups is less than 5%, the resulting cured product will have a low refractive index. Phenyl groups are preferred as aryl groups.

[0081] The content of the (a) unit is preferably 5 to 30 mol%, more preferably 10 to 25 mol%, relative to the total siloxane units in the organopolysiloxane resin (component (B)). Within this range, the mechanical properties of the cured product are improved.

[0082] (B) component may contain R 1 SiO 3 / 2 (R 1represents the same meaning as above) as a trifunctional siloxane unit (i.e., an organosilisesquioxane unit) as a constituent unit. In this case, R 1 SiO 3 / 2 Unit and SiO 4 / 2 The total content of the units is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, of all siloxane units in the organopolysiloxane resin of the component (B).

[0083] The number average molecular weight of component (B) is preferably 500 to 30,000, more preferably 1,000 to 20,000. Within this range, the workability of the composition becomes good. The number average molecular weight is a standard polystyrene conversion value in gel permeation chromatography (GPC).

[0084] The amount of component (B) is preferably 1 to 1000 parts by mass, more preferably 10 to 800 parts by mass, relative to 100 parts by mass of component (A). Within this range, the workability of the composition and the mechanical properties of the cured product are excellent.

[0085] In addition, (B)component may be used individually by 1 type, and may use 2 or more types together.

[0086] (C) Photopolymerization initiator

[0087] Specific examples of the photopolymerization initiator that can be used in the present invention include 2,2-diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651), 1-hydroxy-cyclohexyl-phenyl-ketone (Omnirad 184), 2-hydroxy-2-methyl-1-phenyl-propane-1-one (Omnirad 1173), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propane-1-one (Omnirad 127), methyl phenylglyoxylate (Omnirad MBF), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one (Omnirad 907), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one (Omnirad 1 369), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one (Omnirad 379EG), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO), etc. (all of the above are manufactured by IGM Resins BV). They can be used alone or in combination of two or more.

[0088] As the component (C), from the viewpoint of being less susceptible to oxygen inhibition during ultraviolet curing and improving surface curability, an α-aminoacetophenone-type photopolymerization initiator is preferred, and 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one (Omnirad 1173), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (Omnirad 369), and 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one (Omnirad 379EG) (all manufactured by IGM Resins BV) are more preferred.

[0089] From the viewpoint of curability, the amount of the photopolymerization initiator added is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of (A).

[0090] The composition of the present invention may further contain (D) a monofunctional (meth)acrylate compound not containing a siloxane structure for the purpose of adjusting the mechanical properties and viscosity.

[0091] Specific examples thereof include isoamyl acrylate, lauryl acrylate, stearyl acrylate, ethoxy-diglycol acrylate, methoxy-triglycol acrylate, 2-ethylhexyl-diglycol acrylate, phenoxyethyl acrylate, phenoxydiglycol acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, and dimethylol-tricyclodecane diacrylate. These may be used alone or in combination of two or more.

[0092] Among them, isobornyl acrylate and dimethylol-tricyclodecane diacrylate are particularly preferred.

[0093] When the component (D) is used, the added amount is preferably in the range of 1 to 1000 parts by mass relative to 100 parts by mass of the component (A).

[0094] (E) A silane coupling agent having a (meth)acryloyloxy group may be added for the purpose of imparting adhesiveness to the composition of the present invention.

[0095] Specific examples thereof include (meth)acryloyloxymethyltrimethoxysilane, (meth)acryloyloxymethyltriethoxysilane, (meth)acryloyloxyethyltrimethoxysilane, (meth)acryloyloxyethyltriethoxysilane, (meth)acryloyloxypropyltrimethoxysilane, (meth)acryloyloxypropyltriethoxysilane, (meth)acryloyloxyoctyltrimethoxysilane, and (meth)acryloyloxyoctyltriethoxysilane.

[0096] They can be obtained as commercial products, for example, γ-(methacryloyloxypropyl)trimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), γ-(acryloyloxypropyl)trimethoxysilane (trade name: KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), methacryloyloxyoctyltrimethoxysilane (trade name: KBM-5803, manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

[0097] When the component (E) is used, the amount thereof added is preferably 0.1 to 100 parts by mass, more preferably 0.2 to 50 parts by mass, relative to 100 parts by mass of (A).

[0098] Furthermore, the composition of the present invention may contain additives such as finely powdered silica, colorants (pigments or dyes), silane coupling agents other than component (E), adhesion promoters, polymerization inhibitors, antioxidants, ultraviolet absorbers as light resistance stabilizers, and light stabilizers, within a range that does not impair the effects of the present invention.

[0099] Furthermore, the composition of the present invention may be appropriately mixed with other resin compositions for use.

[0100] The UV-curable silicone composition of the present invention can be obtained by mixing the aforementioned components (A) to (C), and, if necessary, component (D), component (E), and other components in any order, followed by stirring. The apparatus used for stirring and other operations is not particularly limited, and examples thereof include a pestle, a triple-roll mill, a ball mill, and a planetary mixer. These apparatuses may also be appropriately combined.

[0101] From the perspective of moldability and workability during coating, the viscosity of the UV-curable silicone pressure-sensitive adhesive composition of the present invention, as measured at 23°C using a rotational viscometer, is preferably 5000 Pa·s or less, more preferably 3000 Pa·s or less, and even more preferably 1500 Pa·s or less. A viscosity exceeding 5000 Pa·s may significantly deteriorate workability.

[0102] The refractive index of the ultraviolet curable silicone pressure-sensitive adhesive composition of the present invention, when measured at 25°C and a wavelength of 589 nm, is preferably 1.45 or greater, more preferably 1.50 or greater, and even more preferably 1.52 or greater. The refractive index can be measured using, for example, an ATAGO digital refraction system RX-5000.

[0103] The ultraviolet curable silicone composition of the present invention is rapidly cured by irradiation with ultraviolet rays.

[0104] In this case, examples of the light source for the ultraviolet rays to be irradiated include a UVLED lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a carbon arc lamp, and a xenon lamp.

[0105] The irradiation dose of ultraviolet rays (accumulated light dose) is preferably 1 to 10,000 mJ / cm2 for a sheet formed of the composition of the present invention into a thickness of about 2.0 mm. 2 , more preferably 10 to 8000 mJ / cm 2 That is, when using an illumination of 100mW / cm 2 In the case of ultraviolet rays, it is sufficient to irradiate with ultraviolet rays for about 0.01 to 100 seconds.

[0106] The transmittance of the cured product of the present invention is preferably 80% or more, more preferably 85% or more, in terms of transmittance of direct light having a wavelength of 400 nm at 25°C.

[0107] Furthermore, after heating at 150°C for 500 hours, the transmittance of direct light at a wavelength of 400 nm at 25°C is preferably 80% or more, more preferably 82% or more. The transmittance can be measured using, for example, a spectrophotometer U-3900 manufactured by Hitachi High-Tech Science Corporation.

[0108] Example

[0109] The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0110] The compounds of the components used in the Examples are as follows: Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group.

[0111] (A)Ingredients

[0112] [Chemistry 7]

[0113]

[0114]

[0115] (In the formula, the order of arrangement of the siloxane units within the brackets is arbitrary.)

[0116] (B) Ingredients

[0117] (B-1) contains a methacryloyloxy-containing unit represented by the following formula (7), ViMePhSiO 1 / 2 Unit, Ph2SiO 2 / 2 Unit and SiO2 unit, unit containing methacryloyloxy group / ViMePhSiO 1 / 2 Unit / Ph2SiO 2 / 2 A 50% by mass xylene solution of an organopolysiloxane resin (number average molecular weight 2100) having a molar ratio of SiO2 units to SiO2 units of 16 / 4 / 38 / 42

[0118] (B-2) contains a methacryloyloxy group-containing unit represented by the following formula (7), ViMePhSiO 1 / 2 Unit, Ph2SiO 2 / 2 Unit and SiO2 unit, unit containing methacryloyloxy group / ViMePhSiO 1 / 2 Unit / Ph2SiO 2 / 2 A 50% by mass xylene solution of an organopolysiloxane resin (number average molecular weight 1600) having a molar ratio of SiO2 units to SiO2 units of 10 / 15 / 30 / 45

[0119] (B-3) contains a methacryloyloxy group-containing unit represented by the following formula (7), ViMePhSiO 1 / 2 Unit, Ph2SiO 2 / 2 Unit and SiO2 unit, unit containing methacryloyloxy group / ViMePhSiO 1 / 2 Unit / Ph2SiO 2 / 2 A 50% by mass xylene solution of an organopolysiloxane resin (number average molecular weight 1800) having a molar ratio of SiO2 units to SiO2 units of 22 / 3 / 30 / 45.

[0120] [Chemistry 8]

[0121]

[0122] (C) Ingredients

[0123] (C-1) 2-Hydroxy-2-methyl-1-phenyl-propane-1-one (manufactured by IGM Resins BV, Omnirad 1173)

[0124] (D) Ingredients

[0125] (D-1) Isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate IB-XA)

[0126] (D-2) Dimethylol-tricyclodecane diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate DCP-A)

[0127] (E) Ingredients

[0128] (E-1) 3-Methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503)

[0129] [Examples 1 to 8 and Comparative Example 1]

[0130] The above components (A) and (B) were mixed according to the composition shown in Table 1, xylene was distilled off at 100° C. under reduced pressure, and then components (C) to (E) were mixed to prepare the silicone compositions shown in Table 1.

[0131] The following properties were evaluated for the obtained composition and cured product. The results are also shown in Table 1.

[0132] [Viscosity]

[0133] The viscosity of the compositions in Table 1 was measured at 23°C using a rotational viscometer.

[0134] [Refractive index]

[0135] The refractive index of the composition in Table 1 was measured at a measurement wavelength of 589 nm at 25° C. using a digital refractometer RX-5000 manufactured by ATAGO. A refractive index of 1.45 or more is considered sufficiently high.

[0136] [hardness]

[0137] The prepared silicone composition was irradiated with ultraviolet light having a wavelength of 365 nm at a dose of 4000 mJ / cm2 at room temperature (25°C) under a nitrogen atmosphere using an Eye UV electronic control device (model UBX 0601-01) manufactured by Eye Graphics Co., Ltd. 2 The sheet was irradiated with ultraviolet light in a manner to cure. The thickness of the sheet was set to 2.0 mm. The hardness of the obtained cured product was measured according to JIS-K6249:2003.

[0138] [Light transmittance]

[0139] The cured product prepared in the same manner as the hardness measurement was measured using a spectrophotometer U-3900 manufactured by Hitachi High-Tech Science Corporation to measure the transmittance of direct light at a wavelength of 400 nm at 25°C, initially and after heating at 150°C for 500 hours. A transmittance of 80% or more was considered sufficiently high.

[0140] [Table 1]

[0141]

[0142] As shown in Table 1, the UV-curable silicone compositions prepared in Examples 1 to 8 exhibit moderate viscosity and high refractive index. Furthermore, their cured products exhibit sufficient hardness and high transparency. The transmittance of the cured products remains high even after a 150°C heating test, demonstrating their high heat resistance. These results demonstrate their usefulness as lens materials.

[0143] On the other hand, in Comparative Example 1 in which the component (D) was used instead of the component (B), the transmittance after heating at 150° C. for 500 hours was low, and it was found that the heat resistance was poor.

Claims

1. An ultraviolet curable silicone composition comprising: (A) an organopolysiloxane having a main chain composed of repeating diorganosiloxane units, having a group represented by the following general formula (1) at one or both ends, and 5% or more of the total number of monovalent organic groups bonded to silicon atoms being aromatic groups, [Chemistry 1] Where R 1 independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms, R 2 represents an oxygen atom or an alkylene group having 1 to 20 carbon atoms, R 3 independently represent an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkoxy group, or a methacryloyloxyalkoxy group, p represents a number satisfying 0≤p≤10, a represents a number satisfying 1≤a≤3, and a dotted line represents a bonding end. (B) an organopolysiloxane resin, which is present in an amount of 10 to 800 parts by mass relative to 100 parts by mass of the component (A), and which comprises (a) a unit represented by the following general formula (2), (b) R 1 R represents the same meaning as above 1 3SiO 1 / 2 Unit, R in formula (c) 1 R represents the same meaning as above 1 2SiO 2 / 2 unit, and (d) SiO 4 / 2 Unit composition, 5% or more of the total number of monovalent organic groups bonded to silicon atoms are aromatic groups, [Chemistry 2] Where R 1 、R 2 、R 3 , a and p have the same meanings as above, and (C) a photopolymerization initiator. 2 . The ultraviolet-curable silicone composition according to claim 1 , further comprising (D) a monofunctional (meth)acrylate compound not containing a siloxane structure. The ultraviolet curable silicone composition according to claim 1 or 2, further comprising (E) a silane coupling agent having a (meth)acryloyloxy group. 4 . A cured product comprising the ultraviolet curable silicone composition according to claim 1 .

5. A lens comprising the cured product according to claim 4.

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