Solvent-free photocurable liquid composition, cured product thereof, optical filler containing the same, and display device including layer made of the cured product

Abstract

[Problem] To provide: a photocurable liquid silicone composition having a low viscosity which enables easy pouring into a small gap, is rapidly cured through irradiation with high energy rays such as ultraviolet radiation, has a high refractive index after being cured with light in both the visible light region and the infrared region, enables a composition that yields a low dielectric constant to be arbitrarily designed, and is particularly useful as a material for a device in which an infrared LED light source is used; a cured product of the composition; an optical filler containing same; and a display device including a layer comprising said cured product. [Solution] Provided is a low viscosity solventless photocurable liquid composition that contains: (A) one or more organosilanes or organopolysiloxanes which have an average of one or more photoreactive functional groups in the molecule and two or more monovalent functional groups selected from among aromatic groups having 6-12 carbon atoms and aralkyl groups having 7-12 carbon atoms and in which the number of silicon atoms is 1-5; and, optionally, (C) a curing catalyst. Also provided are: cured product of the composition; an optical filler containing same; and a display device including a layer comprising said cured product.

Description

[Technical field]

[0001] The present invention relates to a solventless photocurable liquid composition containing an organosilane or organopolysiloxane that can be cured by actinic rays, such as ultraviolet rays or electron beams, particularly a curable liquid composition that has a low viscosity suitable for injection molding and gives a cured product with a high refractive index, the cured product, and uses thereof. The photocurable liquid composition of the present invention is solventless, has a high refractive index and transparency, and is suitable as a material for forming a light-transmitting layer for electronic / electrical devices and optical devices. The solventless photocurable liquid composition can be designed as a material that gives a cured product with excellent refractive index and transparency and low dielectric constant. [Background technology]

[0002] Electronic / electrical devices and optical devices using white and ultraviolet LEDs as light sources have been widely put to practical use. Silicone materials are being actively studied as peripheral materials because of the need for high transparency and reliability. As a liquid sealing material that directly seals a light source, for example, a high refractive index liquid silicone composition as disclosed in Patent Document 1 has already been put to practical use. In addition, infrared LED light sources and devices using them are being actively developed with an eye on the large market for various sensors, surveillance cameras, infrared data communications, etc. Meanwhile, in addition to these conventional LEDs, micro LED technology that takes advantage of its high energy efficiency has been rapidly researched and developed, and is beginning to be applied to various uses.

[0003] Here, in the case of micro LEDs, which have been studied in recent years, the size of the light source substrate is very small, so the surrounding materials are often required to be small in area and thin. In this case, the injection molding method, in which a curable composition is injected into the gap between the light source substrate and the transparent substrate and cured, is considered to be promising as a method for forming a sealing layer between the light source substrate and the transparent substrate. As a material suitable for this processing method, a low-viscosity liquid silicon-based material that can be photocured and has high transparency after curing is required. Furthermore, a material with a high refractive index is desired to reduce interface reflection and increase light extraction efficiency.

[0004] However, the curable liquid silicone composition disclosed in the above Patent Document 1 has a very high overall viscosity of 3,000 mPas or more at 25°C, and is not suitable for injection molding. More specifically, when the overall viscosity of the composition is high and applied to the injection molding method, it may not be possible to inject it into a small gap between members (hereinafter, sometimes referred to as a "small gap"), or sufficient gap filling may not be achieved. Specifically, even if a high-viscosity curable liquid silicone composition is injected between a light source substrate and a transparent substrate to seal them, it is difficult to inject it so as to sufficiently fill the gap between them, which may cause defects and sealing failures in the process, and this is undesirable as it causes a decrease in production efficiency and yield, a decrease in quality, and a failure of the final display device.

[0005] In contrast, Patent Document 2 discloses a low-viscosity electronic device sealant that is characterized by containing a silicone compound having an ultraviolet-reactive group and can be applied by an inkjet method. Here, a low-molecular-weight silicone compound having an epoxy group is described. In addition, Patent Document 3 discloses an ultraviolet-curable low-viscosity resin composition that contains a multifunctional cationic polymerizable compound, a monofunctional cationic polymerizable compound having a viscosity of 8 mPa·s or less, and a cationic curing catalyst. Here, too, a low-molecular-weight silicone compound having an epoxy group is described.

[0006] However, these documents do not specifically disclose a curable liquid composition or a cured product thereof having a high refractive index, specifically a refractive index of more than 1.47 at a wavelength of 847 nm, and it is difficult to use them as a high refractive index material.

[0007] Furthermore, Patent Document 4 discloses a patternable photosensitive resin composition containing a double-ended alicyclic epoxy-modified silicone resin and a photoacid generator. Here, a high refractive index silicone material containing a phenyl group is exemplified, but the composition has a high viscosity due to its high degree of polymerization, and only compositions diluted with an organic solvent are exemplified. However, a solvent-based composition containing an organic solvent uses a large amount of a volatile organic solvent in the coating / application process, which causes problems of deterioration of the working environment and environmental load. Furthermore, when applied to the injection molding method, the organic solvent may have a negative effect on electronic substrates, semiconductor chips, etc., and the injection volume may change before curing, which may cause defects and sealing failures in the process, which is not preferable. In particular, Patent Document 4 does not describe or suggest a solvent-free photocurable liquid composition or a composition suitable for it. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2007-008996 A (Patent No. 5392805 A) [Patent Document 2] International Publication No. 2016 / 167347 [Patent Document 3] JP 2018-111792 A [Patent Document 4] JP 2019-117325 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a photocurable liquid composition which has low viscosity enabling easy injection into small gaps, which cures quickly when irradiated with high-energy rays such as ultraviolet rays, and which has a high refractive index after curing not only in the visible region but also in the infrared region, and which is particularly useful as a material for devices using infrared LED light sources, as well as a cured product thereof, and uses thereof.

[0010] Furthermore, the present inventors have found new problems with the photocurable liquid composition in addition to its low viscosity (gap filling property and coatability), curability, transparency and high refractive index. In recent years, the applications of high refractive index and highly transparent materials have been expanding, and applications as insulating layers / insulating coating layers constituting electronic devices and electric devices are expected. However, in known photocurable liquid compositions that give cured products with high refractive indexes, it is particularly difficult to design a composition that gives a low relative dielectric constant such as 2.70 or less or 2.60 or less, and a solventless photocurable liquid composition that combines a low relative dielectric constant and a high refractive index, has low viscosity and excellent curability has not yet been provided. [Means for solving the problem]

[0011] The photocurable liquid composition of the present invention comprises: (A) One or more organosilanes or organopolysiloxanes having, on average, one or more photoreactive functional groups and two or more monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms in one molecule, and having 1 to 5 silicon atoms. as an essential component, the viscosity of the entire liquid composition measured at 25°C using an E-type viscometer is 500 mPa s or less, and the composition does not contain any organic solvent. It is preferable that the composition further contains a component selected from (C) a curing catalyst, (D) a specific photocurable compound not containing a silicon atom, and (E) a photosensitizer.

[0012] The cured product of the present invention is characterized by being obtained by irradiating the above-mentioned solventless photocurable liquid composition with light and curing it.

[0013] The optical filler of the present invention is characterized by containing the above-mentioned solvent-free photocurable liquid composition.

[0014] The display device of the present invention is characterized by including a layer made of a cured product obtained by curing the above-mentioned solventless photocurable liquid composition. In particular, the display device is preferably a display device using an infrared LED light source.

[0015] The manufacturing method of the display device of the present invention is characterized by comprising the steps of injecting the above-mentioned solventless photocurable liquid composition between a light source substrate and a transparent substrate, and curing the injected solventless photocurable liquid composition by irradiating it with high-energy rays. Effect of the Invention

[0016] The solventless photocurable liquid composition of the present invention does not require the use of organic solvents, has low viscosity that allows it to be easily injected into small gaps, and cures quickly when irradiated with high-energy rays such as ultraviolet rays. In addition, the refractive index after curing is high not only in the visible region but also in the infrared region, making it useful as a material for devices using infrared LED light sources.

[0017] Furthermore, by using the above-mentioned components (A) and (B) in combination, the solventless photocurable liquid composition of the present invention can be designed to give a cured product having a low dielectric constant in addition to the above-mentioned properties. It is possible to provide a solventless photocurable liquid composition that combines a low dielectric constant and a high refractive index, has low viscosity and excellent curing properties, and an insulating layer / insulating coating layer that constitutes an electronic device or an electric device formed by photocuring the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The configuration of the present invention will be described in further detail below. [Component (A)] The component (A) of the present invention is one of the characteristic constituents of the present composition, and is one of the main components of the photocurable liquid composition, which is a component that reduces the viscosity of the composition without impairing the curability of the entire composition, and is a compound that is cured by irradiation with light, if necessary, in the presence of the component (C) described below.

[0019] Component (A) is one or more organosilanes or organopolysiloxanes having 1 to 5 silicon atoms and having, on average, one or more photoreactive functional groups in one molecule, and two or more monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms. Component (A) is characterized by its low volatility and not inhibiting the photocuring of the composition of the present invention. In addition, component (A) is a component that improves the refractive index of the entire composition and the cured product, since it has an aromatic group or an aralkyl group in the molecule.

[0020] Since the number of silicon atoms in such component (A) is 5 or less, it is a silane or siloxane oligomer (organopolysiloxane with a degree of siloxane polymerization of 5 or less) with a small molecular weight, and has at least one organic group that can form bonds between itself by light irradiation in the presence or absence of a curing catalyst as a photoreactive functional group in the molecule, thereby imparting photocuring reactivity to the composition. Meanwhile, component (A) has the property of being a relatively low molecular weight, low viscosity component, yet low volatility. Therefore, the composition of the present invention containing component (A) has excellent photocuring reactivity, and can reduce the viscosity of the entire composition suitable for injection molding, thereby significantly improving gap filling properties.

[0021] Examples of photoreactive functional groups in component (A) include radically polymerizable groups and cationic polymerizable groups. The radically polymerizable group is not particularly limited as long as it is a functional group capable of forming a new bond, particularly a bond between radically polymerizable groups, by a radical reaction mechanism, and examples thereof include an acrylic group, a methacrylic group, a maleimide group, and an organic group containing any of these groups. Specific examples of radically polymerizable groups include groups such as acryloxypropyl, methacryloxypropyl, acrylamidepropyl, methacrylamidepropyl, and 3-(N-maleimide)propyl. Examples of cationic polymerizable groups include groups such as vinyl ether groups, epoxy group-containing groups, and oxetane group-containing groups, for example, CH 2 =CH-O-(CH 2 )n-(n is an integer of 3 to 20), glycidyloxy-(CH2 ) n -(n is an integer from 3 to 20), 3,4-epoxycyclohexyl-(CH 2 ) n -(n is an integer of 2 to 20) and the like.

[0022] The photoreactive functional group of the component (A) is preferably a cationically polymerizable functional group, in particular one or more epoxy group-containing groups. Particularly preferred groups include epoxycyclohexylalkyl groups, in particular 3,4-epoxycyclohexylethyl groups.

[0023] Furthermore, examples of the monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms include aryl groups having 6 to 12 carbon atoms, such as a phenyl group, a tolyl group, and a xylyl group; and aralkyl groups having 7 to 12 carbon atoms, such as a benzyl group and a phenethyl group, with the phenyl group and the phenethyl group being preferred from the viewpoint of economy.

[0024] On the other hand, examples of other groups bonded to silicon atoms in component (A) (specifically, groups other than monovalent functional groups selected from the above-mentioned photoreactive functional groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms) include alkyl groups having 1 to 12 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; and halogen-substituted alkyl groups having 1 to 12 carbon atoms such as 3-chloropropyl and 3,3,3-trifluoropropyl groups, with methyl being preferred from the standpoints of economy and heat resistance. A small amount of alkoxy groups such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, sec-butoxy, and tert-butoxy groups, and hydroxyl groups may be bonded to silicon atoms in component (A).

[0025] Component (A) has the average composition formula (1); R X a R Y b R Z cSiO (4-a―b-c) / 2 (1) (In the formula, R X is a photoreactive functional group, and R Y is a monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms; R Z is a group selected from the group consisting of an unsubstituted or fluorine-substituted monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding monovalent functional groups selected from the group consisting of the photoreactive functional groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, a, b, and c are numbers that satisfy the following conditions: 1≦a+b+c≦3 and 0.08≦a / (a+b+c)≦0.5, and there is one or more R X and at least two R Y ) In this case, it is preferable that the organopolysiloxane has 2 to 5 silicon atoms and is represented by the formula: X , R Y , R Z can be any of the above-mentioned photoreactive functional groups, monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, and groups other than the monovalent functional groups selected from photoreactive functional groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms.

[0026] Further, the component (A) is (A1) a compound represented by the following formula (2): [ka] (2) (Wherein, all R 1 ~R 8 Among the groups, on average, at least one group per molecule is a photoreactive functional group, and at least two of them are monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms; 1 From R 8 each independently represents an unsubstituted or fluorine-substituted monovalent hydrocarbon group; and n is a number from 0 to 3; (A2) The following formula (3): [ka] (3) (In the formula, R 9 , R 10 are each independently a photoreactive functional group, a monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms, and a monovalent hydrocarbon group that is unsubstituted or substituted with fluorine, and all R 9 , R 10 Among these, on average, one or more groups are photoreactive functional groups, at least two are monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and k is a number from 3 to 5. A cyclic organopolysiloxane represented by the formula: Mixtures of these organopolysiloxanes It is preferable that the organopolysiloxane is one or more types having a photoreactive functional group selected from the group consisting of: In this case, the groups described above can be applied as the groups other than the photoreactive functional group, the monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms, and the monovalent functional group selected from the photoreactive functional group, the aromatic group having 6 to 12 carbon atoms and the aralkyl group having 7 to 12 carbon atoms.

[0027] The viscosity of the photocurable liquid composition of the present invention can be controlled by adjusting the number of silicon atoms in component (A). The number of silicon atoms is preferably 2 or 3. If it is equal to or greater than the lower limit of the above range, the mechanical strength of the resulting cured product is sufficiently high, while if it is equal to or less than the upper limit of the above range, the viscosity of the photocurable liquid composition can be easily reduced.

[0028] Furthermore, by adjusting the number of photoreactive functional groups in the (A) component, the hardness of the cured product obtained by curing the photocurable liquid composition of the present invention can be controlled. The number of photoreactive functional groups is preferably 1 to 2 on average per molecule. If it is equal to or greater than the lower limit of the above range, the photocurability of the resulting curable composition is sufficiently high, while if it is equal to or less than the upper limit of the above range, the toughness of the resulting cured product is improved.

[0029] Examples of the component (A) include the following compounds A1 to A20. A1: Diphenyl-bis[2-(3,4-epoxycyclohexyl)ethyl]silane A2: 1,3-dimethyl-1,3-diphenyl-1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]disiloxane A3: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-3,3-diphenyl-1,1,5,5-tetramethyltrisiloxane A4: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,5-diphenyl-1,3,3,5-tetramethyltrisiloxane A5: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,3,5-triphenyl-1,3,5-trimethyltrisiloxane A6: 1,7-bis[2-(3,4-epoxycyclohexyl)ethyl]-3,3-diphenyl-1,1,5,5,7,7-hexamethyltetrasiloxane A7: 1,7-bis[2-(3,4-epoxycyclohexyl)ethyl]-3,5-diphenyl-1,1,3,5,7,7-hexamethyltetrasiloxane A8: 1,7-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,7-diphenyl-1,3,3,5,5,7-hexamethyltetrasiloxane A9: 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-5,7-diphenyl-1,3,5,7-tetramethylcyclotetrasiloxane A10: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-3,7-diphenyl-1,3,5,7-tetramethylcyclotetrasiloxane A11: 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-5,7-diphenethyl-1,3,5,7-tetramethylcyclotetrasiloxane A12: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-3,7-diphenethyl-1,3,5,7-tetramethylcyclotetrasiloxane A13: 1-[2-(3,4-epoxycyclohexyl)ethyl]-3,3-diphenyl-5-phenethyl-1,1,5,5-tetramethyltrisiloxane A14: 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,5-diphenyl-5-phenethyl-1,3,3,5-tetramethyltrisiloxane A15: 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,3,5-triphenyl-1,3,5-trimethyl-5-phenethyltrisiloxane A16: 1-[2-(3,4-epoxycyclohexyl)ethyl]-3,3-diphenyl-7-phenethyl-1,1,5,5,7,7-hexamethyltetrasiloxane A17: 1-[2-(3,4-epoxycyclohexyl)ethyl]-3,5-diphenyl-7-phenethyl-1,1,3,5,7,7-hexamethyltetrasiloxane A18: 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,7-diphenyl-7-phenethyl-1,3,3,5,5,7-hexamethyltetrasiloxane A19: 1-[2-(3,4-epoxycyclohexyl)ethyl]-3,5,7-triphenyl-1,3,5,7-tetramethylcyclotetrasiloxane A20: 1-[2-(3,4-epoxycyclohexyl)ethyl]-3,5,7-triphenethyl-1,3,5,7-tetramethylcyclotetrasiloxane

[0030] The content of the component (A) is preferably 10 to 99.9 parts by mass relative to 100 parts by mass of the photocurable liquid composition containing the component (A). A more preferred content is 15 to 99.5 parts by mass, and an even more preferred content is 25 to 99 parts by mass. This is because when the content of the component (A) is equal to or greater than the lower limit of the above range, the mechanical properties of the obtained cured product are improved, whereas when the content is equal to or less than the upper limit of the above range, the photocurability of the obtained curable composition is sufficiently high.

[0031] When the (B) component described later is used optionally, the content of the (A) component is preferably 90 to 99.9 parts by mass, more preferably 95 to 99.5 parts by mass, and particularly preferably 98 to 99 parts by mass, relative to 100 parts by mass of the entire photocurable liquid composition, and the mass ratio of the (A) component to the (B) component can be selected from the range of 100:0 to 10:90, 100:0 to 15:85, or 100:0 to 20:80. Here, when the solventless photocurable liquid composition according to the present invention is designed to give a cured product having a relative dielectric constant of 2.70 or less, particularly 2.60 or less, by photocuring reaction, the mass ratio of the (A) component to the (B) component is preferably in the range of 80:20 to 20:80, and more preferably in the range of 70:30 to 30:70.

[0032] [(C) component] The component (C) of the present invention is a curing catalyst that cures the photocurable liquid composition depending on the type of light / high energy ray used for curing and as necessary. When the photoreactive functional group of the component (A) is a cationic polymerizable functional group containing epoxy or vinyl ether, a photocationic polymerization initiator (C1) is used as a curing catalyst. As the photocationic polymerization initiator, a compound capable of generating a Bronsted acid or a Lewis acid by irradiation with light or an electron beam, so-called photoacid generators, are known, and it is known that an acid is generated by irradiation with light or the like, and the acid causes a reaction between cationic polymerizable functional groups. In addition, when the photoreactive functional group is a radical polymerizable functional group, a photoradical polymerization initiator (C2) can be used as a curing catalyst. The photoradical polymerization initiator generates free radicals by irradiation with ultraviolet light or an electron beam, which cause a radical polymerization reaction to cure the composition of the present invention. When the composition of the present invention is cured by irradiation with an electron beam, these polymerization initiators are usually not necessary, and the curing reaction proceeds even without the component (C).

[0033] From a practical standpoint, it is preferred that the photoreactive functional group in component (A) is an epoxy group-containing group, and in that case, it is preferred to contain one or more types of (C) curing catalysts selected from (C1) a photocationic polymerization initiator and (C2) a photoradical polymerization initiator.

[0034] (C1) Photocationic polymerization initiator The photocationic polymerization initiator used in the composition of the present invention can be selected from those known in the art and is not particularly limited. Strong acid generating compounds such as diazonium salts, sulfonium salts, iodonium salts, and phosphonium salts are known as photocationic polymerization initiators, and these can be used. Examples of photocationic polymerization initiators include bis(4-tert-butylphenyl)iodonium hexafluorophosphate, cyclopropyldiphenylsulfonium tetrafluoroborate, dimethylphenacylsulfonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, diphenyliodonium tetrafluoromethanesulfonate, 2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(furan-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, and 4-isopropyl-4'-methyldiphenyliodonium. Tetrakis(pentafluorophenyl)borate, 2-[2-(5-methylfuran-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-Triazine, 4-nitrobenzenediazonium tetrafluoroborate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium bromide, tri-p-tolylsulfonium hexafluorophosphate, tri-p-tolylsulfonium trifluoromethanesulfonate, diphenyliodonium triflate, triphenylsulfonium triflate, diphenyliodonium nitrate, bis(4-tert-butylphenyl)iodonium perfluoro-1-butanesulfonate, bis(4-tert-butylphenyl)iodonium triflate, triphenylsulfonium perfluoro-1-butanesulfonate, N-hydroxynaphthalimide triflate, p-toluenesulfonate, diphenyliodonium p-toluenesulfonate, (4-tert-butylphenyl)diphenylsulfonium triflate, tris(4-tert-butylphenyl)sulfonium triflate, N-hydroxy-5-norbornene-2,3-dicarboximide Examples of the photocationic polymerization initiator include, but are not limited to, perfluoro-1-butanesulfonate, (4-phenylthiophenyl)diphenylsulfonium triflate, and 4-(phenylthio)phenyldiphenylsulfonium triethyltrifluorophosphate. In addition to the above compounds, examples of the photocationic polymerization initiator include commercially available photoinitiators such as Omnicat 250, Omnicat 270 (both from IGM Resins BV), CPI-310B, IK-1 (both from San-Apro Co., Ltd.), DTS-200 (Midori Chemical Co., Ltd.), and Irgacure 290 (BASF).

[0035] The amount of the cationic photopolymerization initiator added to the composition of the present invention is not particularly limited as long as the desired photocuring reaction occurs. In general, however, it is preferable to use the cationic photopolymerization initiator in an amount of 0.1 to 10 mass%, particularly 0.5 to 5 mass%, and especially 1 to 2 mass%, based on the total amount of the component (A) of the present invention and the component (B) described below.

[0036] (C2) Photoradical polymerization initiator Photoradical polymerization initiators are roughly divided into photocleavage type and hydrogen abstraction type, and the photoradical polymerization initiator used in the composition of the present invention can be arbitrarily selected from those known in the art and is not particularly limited to a specific one. Examples of photoradical polymerization initiators include acetophenone, p-anisyl, benzyl, benzoin, benzophenone, 2-benzoylbenzoic acid, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, benzoin methyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ethyl ether, 4-benzoylbenzoic acid, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, methyl 2-benzoylbenzoate, 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine ...4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophen Dimethyl-2-(dimethylamino)-4'-morpholinobutyrophenone, (±)-camphorquinone, 4,4'-dichlorobenzophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4-diethylthioxanthen-9-one, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate, 1,4-dibenzoylbenzene, 2-ethylanthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, lithium These include, but are not limited to, phenyl(2,4,6-trimethylbenzoyl)phosphineate, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 2-isonitrosopropiophenone, 2-phenyl-2-(p-toluenesulfonyloxy)acetophenone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.In addition to the above compounds, examples of the photoradical polymerization initiator include Omnirad 651, 184, 1173, 2959, 127, 907, 369, 369E, and 379EG (alkylphenone-based photopolymerization initiators, IGM Resins BV), Omnirad TPO H, TPO-L, and 819 (acylphosphine oxide-based photopolymerization initiators, IGM Resins BV), Omnirad MBF and 754 (intramolecular hydrogen abstraction type photopolymerization initiators, IGM Resins BV), and Irgacure OXE01 and OXE02 (oxime ester-based non-polymerization initiators, BASF).

[0037] The amount of the photoradical polymerization initiator added to the composition of the present invention is not particularly limited as long as the desired photopolymerization reaction or photocuring reaction occurs, but it is generally used in an amount of 0.01 to 5 mass %, preferably 0.05 to 1 mass %, relative to the total mass of the composition of the present invention.

[0038] [(E) Photosensitizer] A photosensitizer can also be used in combination with the above-mentioned photocationic polymerization initiator or photoradical polymerization initiator. The use of a photosensitizer can increase the photon efficiency of the polymerization reaction, and since light of a longer wavelength can be used for the polymerization reaction compared to the case where only a photoinitiator is used, it is known to be particularly effective when the coating thickness of the composition is relatively thick or when an LED light source with a relatively long wavelength is used. In practical terms, the solventless photocurable liquid composition according to the present invention preferably further contains one or more types of photosensitizer (E) in addition to the above-mentioned component (C), and the photocuring reactivity of the entire composition can be improved.

[0039] The photosensitizer can be any known component without any particular limitation, and includes anthracene compounds, phenothiazine compounds, perylene compounds, cyanine compounds, merocyanine compounds, coumarin compounds, benzylidene ketone compounds, (thio)xanthene or (thio)xanthone compounds, such as 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, squalium compounds, (thia)pyrylium compounds, and porphyrin compounds, but is not limited to these and any photosensitizer can be used in the curable composition of the present invention. As an example, in the composition of the present invention, when the photoreactive functional group in the above-mentioned component (A) is an epoxy group-containing group and the photocationic polymerization initiator (C1) is used, a triplet photosensitizer that is a thioxanthone such as 2-isopropylthioxanthone can be suitably used.

[0040] [(B) Component] The photocurable liquid composition of the present invention can contain, as an optional component, (B) one or more organopolysiloxanes having an average of one or more photoreactive functional groups per molecule and having 2 to 10 silicon atoms (excluding organopolysiloxanes corresponding to the above-mentioned component (A)).

[0041] Specifically, component (B) can be distinguished from component (A) in terms of the presence or absence of aromatic groups and aralkyl groups, and the number of silicon atoms therein. That is, (B1) one or more organopolysiloxanes having an average of one or more photoreactive functional groups per molecule, containing less than two monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and having 2 to 5 silicon atoms; (B2) One or more organopolysiloxanes having, on average, one or more photoreactive functional groups in one molecule and having more than 5 and not more than 10 silicon atoms. One or more types are selected from the above.

[0042] Such component (B) has the following average composition formula (4): R X d RY e R Z f SiO (4-d―e-f) / 2 (4) (In the formula, R X is a photoreactive functional group, and R Y is a monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms; R Z is a group selected from the group consisting of an unsubstituted or fluorine-substituted monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding monovalent functional groups selected from the group consisting of the photoreactive functional groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, d, e, and f are numbers that satisfy the following conditions: 1≦d+e+f≦3 and 0.04≦d / (d+e+f)≦0.5, and there is one or more R X and less than two R Y ) and having 2 to 10 silicon atoms, and does not fall under the category of component (A).

[0043] R in component (B) X , R Y , R Z can be any of the above-mentioned photoreactive functional groups, monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, and groups other than the monovalent functional groups selected from photoreactive functional groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms.

[0044] The photoreactive functional group of component (B) is preferably a cationically polymerizable functional group, particularly one or more epoxy group-containing groups. Particularly preferred groups include epoxycyclohexylalkyl groups, particularly 3,4-epoxycyclohexylethyl groups.

[0045] Examples of the component (B) include the following compounds B1 to B21. B1: 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,3-pentamethyldisiloxane B2: 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane B3: 1-[2-(3,4-epoxycyclohexyl)ethyl]-3-phenethyl-1,1,3,3-tetramethyldisiloxane B4: 3-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,1,3,5,5,5-heptamethyltrisiloxane B5: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane B6: 1,3,5-tris[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,5,5-pentamethyltrisiloxane B7: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane B8: 1-[2-(3,4-epoxycyclohexyl)ethyl]-5-phenethyl-1,1,3,3,5,5-hexamethyltrisiloxane B9: 1,7-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5,7,7-octamethyltetrasiloxane B10: 1,7-bis[2-(3,4-epoxycyclohexyl)ethyl]-3-phenyl-1,1,3,5,5,7,7-heptamethyltetrasiloxane B11: 3-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,1,3,5,5,7,7,7-nonamethyltetrasiloxane B12: 3,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,1,3,5,7,7,7-octamethyltetrasiloxane B13: 1-[2-(3,4-epoxycyclohexyl)ethyl]-7-phenethyl-1,1,3,3,5,5,7,7-octamethyltetrasiloxane B14: 3-[2-(3,4-epoxycyclohexyl)ethyl]-5-phenethyl-1,1,1,3,5,7,7,7-octamethyltetrasiloxane B15: 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,3,3,5,5,7,7-heptamethylcyclotetrasiloxane B16: 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,3,5,5,7,7-hexamethylcyclotetrasiloxane B17: 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,3,3,5,7,7-hexamethylcyclotetrasiloxane B18: 1,3,5-tris[2-(3,4-epoxycyclohexyl)ethyl]-7-phenyl-1,3,5,7-tetramethylcyclotetrasiloxane B19: 1,3,5-tris[2-(3,4-epoxycyclohexyl)ethyl]-1,3,5,7,7-pentamethylcyclotetrasiloxane B20: 1,3,5,7-tetrakis[2-(3,4-epoxycyclohexyl)ethyl]-1,3,5,7-tetramethylcyclotetrasiloxane B21: 1,3,5-tris[2-(3,4-epoxycyclohexyl)ethyl]-7-phenethyl-1,3,5,7-tetramethylcyclotetrasiloxane

[0046] In the photocurable liquid composition of the present invention, the inclusion of component (B) increases the degree of freedom for designing the hardness, mechanical strength including tensile strength and elongation at break, curing reaction rate, refractive index, etc. of the cured product obtained by curing the photocurable liquid composition to a desired range. Furthermore, the combined use of components (A) and (B) makes it possible to design the relative dielectric constant of the cured product obtained by curing the photocurable liquid composition to 2.70 or less, preferably 2.60 or less.

[0047] There is no limit to the content, but as described above, when the entire photocurable liquid composition is taken as 100 parts by mass, the sum of the (A) component and the (B) component is preferably 90 to 99.9 parts by mass, and the mass ratio of the (A) component to the (B) component is selected in the range of 100:0 to 10:90, and when the composition is designed to give a cured product having a relative dielectric constant of 2.70 or less, particularly 2.60 or less, by a photocuring reaction, the mass ratio of the (A) component to the (B) component is preferably in the range of 80:20 to 20:80. The content of the (B) component alone is preferably in the range of 0 to 80 parts by mass, more preferably in the range of 0 to 70 parts by mass, and more preferably in the range of 0 to 55 parts by mass.

[0048] The viscosity of the photocurable liquid composition of the present invention is 500 mPa·s or less as measured at 25°C using an E-type viscometer. Within this range, the resulting composition can be cast into a moldable form. It is preferably within the range of 5 to 250 mPa·s, 5 to 200 mPa·s, or 5 to 100 mPa·s. This is because, when the viscosity of the composition is at or above the lower limit of the above range, the mechanical properties of the resulting cured product are good, whereas, when the viscosity is at or below the upper limit of the above range, the castability of the resulting composition is good.

[0049] The refractive index of the photocurable liquid composition of the present invention is preferably 1.46 or more at 25°C and a wavelength of 847 nm, and may be 1.47 or more, 1.49 or more, or 1.50 or more, and may be in the range of 1.46 to 1.54, or 1.46 to 1.53. Due to this characteristic, the refractive index of the cured product obtained by curing the composition is sufficiently high, and in various devices using an infrared LED as a light source, the interfacial reflection between the optical glass and other light transmitting layers can be reduced, and the light extraction efficiency can be increased. The refractive index of the cured product will be described later.

[0050] [(D) component] The photocurable liquid composition of the present invention may further contain a compound represented by formula (D) R X The photocurable compound may contain a silicon-free photocurable compound represented by the formula:X is the photoreactive functional group described above, and may be a radically polymerizable functional group or a cationic polymerizable functional group, but is preferably a cationic polymerizable functional group, particularly one or more epoxy group-containing groups. Particularly preferred groups include a glycidyl group and an epoxycyclohexylalkyl group. Meanwhile, R is a monovalent functional group selected from an unsubstituted or fluorine-substituted monovalent alkyl group, an alkenyl group having 2 to 6 carbon atoms, an aromatic group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a hydroxyl group, and an alkoxy group.

[0051] Examples of such compounds include glycidyl ethers, glycidyl esters, such as allyl glycidyl ether, benzyl glycidyl ether, 2,2-bis(4-glycidoxyphenyl)propane, 1,4-butanediol diglycidyl ether, butyl glycidyl ether, tert-butyl glycidyl ether, 4-tert-butylphenyl glycidyl ether, glycidyl isopropyl ether, glycidyl phenyl ether, diglycidyl-1,2-cyclohexanedicarboxylate, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate, as well as epoxycyclohexyl group-containing compounds, such as 3,4-epoxycyclohexylmethyl acrylate, 1,2-epoxy-4-vinylcyclohexane, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 3,3'-di-7-oxabicyclo[4,1,0]heptane.

[0052] Other Additives In addition to the above components, further additives may be added to the composition of the present invention as desired. Examples of additives include, but are not limited to, the following:

[0053] [Adhesion imparting agent] An adhesion promoter can be added to the composition of the present invention in order to improve adhesion or adhesion to a substrate in contact with the composition. When the curable composition of the present invention is used for applications requiring adhesion or adhesion to a substrate, such as a coating agent or a sealing material, it is preferable to add an adhesion imparting agent to the curable composition of the present invention. As the adhesion promoter, any known adhesion promoter can be used as long as it does not inhibit the curing reaction of the composition of the present invention.

[0054] Examples of adhesion promoters that can be used in the present invention include organosilanes having a trialkoxysiloxy group (e.g., trimethoxysiloxy group, triethoxysiloxy group) or a trialkoxysilylalkyl group (e.g., trimethoxysilylethyl group, triethoxysilylethyl group) and a hydrosilyl group or an alkenyl group (e.g., vinyl group, allyl group), or organosiloxane oligomers having a linear, branched or cyclic structure with about 4 to 20 silicon atoms; organosilanes having a trialkoxysiloxy group or a trialkoxysilylalkyl group and a methacryloxyalkyl group (e.g., 3-methacryloxypropyl group); organosilanes, or organosiloxane oligomers having a linear, branched, or cyclic structure with about 4 to 20 silicon atoms; organosilanes having a trialkoxysiloxy group or a trialkoxysilylalkyl group and an epoxy group-bonded alkyl group (e.g., 3-glycidoxypropyl group, 4-glycidoxybutyl group, 2-(3,4-epoxycyclohexyl)ethyl group, 3-(3,4-epoxycyclohexyl)propyl group), or organosiloxane oligomers having a linear, branched, or cyclic structure with about 4 to 20 silicon atoms; organic compounds having two or more trialkoxysilyl groups (e.g., trimethoxysilyl group, triethoxysilyl group);Examples of the reaction product of aminoalkyltrialkoxysilane and epoxy group-bonded alkyltrialkoxysilane, and epoxy group-containing ethyl polysilicate include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 1,6-bis(trimethoxysilane), silyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,3-bis[2-(trimethoxysilyl)ethyl]-1,1,3,3-tetramethyldisiloxane, reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, condensation reaction product of silanol group-blocked methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, condensation reaction product of silanol group-blocked methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, and tris(3-trimethoxysilylpropyl)isocyanurate.

[0055] The amount of adhesion promoter added to the curable composition of the present invention is not particularly limited, but in order not to promote the curing characteristics of the curable composition or discoloration of the cured product, it is preferably within the range of 0 to 5 parts by mass, or 0 to 2 parts by mass, relative to 100 parts by mass of the total of components (A) and (C).

[0056] [Other additives] In addition to the adhesion promoter described above, or instead of the adhesion promoter, other additives may be added to the composition of the present invention as desired. Examples of additives that can be used include leveling agents, silane coupling agents not included in the adhesion promoters described above, ultraviolet absorbers, antioxidants, polymerization inhibitors, fillers (functional fillers such as reinforcing fillers, insulating fillers, and thermally conductive fillers), and the like. If necessary, appropriate additives can be added to the composition of the present invention. In addition, if necessary, a thixotropic agent may be added to the composition of the present invention, especially when the composition is used as a potting agent or a sealing material.

[0057] This composition can be prepared by uniformly mixing component (A), component (C), component (B) which is added as necessary, and other optional components. When preparing this composition, it can be mixed at room temperature using various stirrers or kneaders, and if necessary, it can be mixed under heating. There is also no limitation on the order in which each component is mixed, and they can be mixed in any order. On the other hand, in order to avoid any effect on the curing during the preparation of this composition, it is recommended to prepare it in a place where there is no contamination of light of 450 nm or less, or where contamination of the above light is as small as possible.

[0058] The present composition can be cured by irradiation with light. Examples of light used to cure the present composition include high-energy rays such as ultraviolet rays and electron beams, and visible light. The wavelength of the light is preferably within the range of 250 to 450 nm, and irradiation with high-energy rays using ultraviolet rays with a wavelength of 400 nm or less is more preferable. The present composition can also be cured using electron beams, which is also one embodiment of the present invention. In this case, even in the absence of component (C), a practically sufficient photocuring reaction proceeds.

[0059] This composition is useful as various injection agents, potting agents, sealants, and adhesives, and is particularly useful as an optical filler for forming light-transmitting layers for various devices using infrared LEDs, particularly display devices. The cured product is less colored and less likely to become cloudy under high temperature or high temperature and high humidity conditions, making it suitable as a light-transmitting layer for display devices using infrared LEDs.

[0060] This composition cures at room temperature, so it can be used to coat substrates with poor heat resistance. Such substrates are generally transparent substrates such as glass, synthetic resin films, sheets, and coatings. In addition, injection molding is an example of a coating method for this composition, taking advantage of its low viscosity characteristics.

[0061] Next, the cured product of the present invention will be described in detail.

[0062] The cured product obtained by curing this composition has a high refractive index, and the refractive index of the cured product is 1.48 or more at 25°C and a wavelength of 847 nm, and the refractive index of the cured product under these conditions is preferably in the range of 1.48 to 1.55, and more preferably in the range of 1.48 to 1.54. Due to this characteristic, the refractive index of the cured product obtained by curing this composition is sufficiently high, and in various devices using an infrared LED as a light source, it is possible to reduce interfacial reflection between optical glass and other light transmitting layers and to increase the light extraction efficiency.

[0063] The cured product obtained by curing this composition may have a dielectric constant of 2.70 or less in addition to the above-mentioned characteristic of a high refractive index, and in particular, a photocurable liquid composition that gives a cured product with a dielectric constant of 2.60 or less can be preferably designed. In particular, by optimizing the types and amounts of the (A) and (B) components, it is possible to design a composition that gives a cured product with a dielectric constant of 2.20 to 2.70, preferably 2.20 to 2.60.

[0064] The cured product of the present invention is characterized by being obtained by curing the above-mentioned photocurable liquid composition by irradiating it with light. The shape of the cured product is not particularly limited, and examples thereof include a sheet, a film, a tape, and a block. In addition, the cured product may be integrated with various substrates.

[0065] The present cured product can be formed, for example, by applying the present composition to a film-like substrate, a tape-like substrate, or a sheet-like substrate, and then curing the composition by light irradiation to form a cured film made of the present cured product on the surface of the substrate. The present composition can also be injected between two substrates, at least one of which is a transparent substrate, and cured by light irradiation from the transparent substrate side to form a cured product integrated with the substrate. The thickness of the cured film is not limited, but is preferably 1 to 3000 μm, more preferably 10 to 2000 μm.

[0066] The display device of the present invention is produced using the photocurable liquid composition of the present invention, and examples thereof include passive display devices such as LCDs (liquid crystal displays) and ECDs (electrochromic displays), and light-emitting display devices such as ELDs (electroluminescent displays). In the display device of the present invention, the space between a display unit such as a liquid crystal or organic EL display and a display-forming member such as a touch panel or a cover lens, or between the display-forming members, is filled with a cured product of the photocurable liquid composition of the present invention, thereby reducing interfacial reflection and increasing light extraction efficiency.

[0067] A typical method for manufacturing the display device of the present invention is an injection molding method that takes advantage of the low viscosity property of the photocurable liquid composition of the present invention. Specifically, the composition is injected into a narrow gap between an infrared LED light source substrate and various transparent substrates, and cured by irradiating with ultraviolet light to manufacture a display device.

[0068] On the other hand, the composition of the present invention can be designed to have a low dielectric constant of 2.70 or less, preferably 2.60 or less, and can therefore be used as an insulating material with a high refractive index and high transparency. Specifically, the composition of the present invention is particularly useful as a material for forming an insulating layer constituting various articles, particularly electronic devices and electric devices. The composition of the present invention can be applied onto a substrate, or sandwiched between two substrates, at least one of which is made of a material that transmits ultraviolet rays or electron beams, and the composition can be cured by irradiating the composition with ultraviolet rays or electron beams to form an insulating layer. In this case, a pattern can be formed when the composition of the present invention is applied to a substrate, and then the composition can be cured, or the composition can be applied to a substrate, and when curing the composition, the cured and uncured parts can be left by irradiation with ultraviolet rays or electron beams, and the uncured parts can be removed with a solvent to form an insulating layer of a desired pattern.

[0069] The composition of the present invention is particularly suitable as a material for forming an insulating layer of a display device such as a touch panel or a display. In this case, the insulating layer may be formed into any desired pattern as described above, if necessary. Therefore, a display device such as a touch panel or a display including an insulating layer obtained by curing the ultraviolet-curable organopolysiloxane composition of the present invention is also an embodiment of the present invention.

[0070] In addition, an insulating coating layer (insulating film) can be formed by coating an article with the composition of the present invention and then curing the coating. Therefore, the composition of the present invention can be used as an insulating coating agent. In addition, a cured product formed by curing the curable composition of the present invention can be used as an insulating coating layer.

[0071] The insulating film formed from the photocurable liquid composition of the present invention can be used for various applications. In particular, it can be used as a component of an electronic device or as a material used in the process of manufacturing an electronic device. Electronic devices include electronic devices such as semiconductor devices and magnetic recording heads. For example, the curable composition of the present invention can be used as an insulating film for semiconductor devices such as LSI, system LSI, DRAM, SDRAM, RDRAM, D-RDRAM, and multi-chip module multilayer wiring boards, an interlayer insulating film for semiconductors, an etching stopper film, a surface protection film, a buffer coat film, a passivation film in LSI, a cover coat for flexible copper-clad boards, a solder resist film, and a surface protection film for optical devices. In particular, the photocurable liquid composition of the present invention has the characteristic of a high refractive index, and is therefore particularly suitable as an insulating layer in optical applications requiring a high refractive index.

[0072] In addition to being used as a coating agent, the photocurable liquid composition of the present invention is also suitable for use as a potting agent, particularly as an insulating potting agent for electronic and electrical devices.

[0073] The present invention will be further described below based on examples, but the present invention is not limited to the following examples. EXAMPLES

[0074] The photocurable liquid composition of the present invention and the cured product thereof will be described in detail with reference to examples. Measurements and evaluations in the examples and comparative examples were carried out as follows.

[0075] [Viscosity of photocurable liquid composition] The viscosity (mPa·s) at 25°C was measured using a rotational viscometer (E-type viscometer VISCONIC EMD manufactured by Tokimec Inc.).

[0076] [Chemical structure of component (A)] The chemical structure of component (A) was identified by nuclear magnetic resonance spectroscopy.

[0077] [Appearance of the photocurable liquid composition and its cured product] The appearance of the photocurable liquid composition and its cured product were visually observed and rated as follows. A:Transparent B: Slightly cloudy

[0078] [Transparency and haze of the cured product] The photocurable liquid composition was filled between two glass plates (filling area: 40 × 40 mm) so that the thickness after curing was 200 microns. 2 ), 405 nm LED light with illuminance of 50 mW / cm 2 The total light transmittance and haze of the cured sheet formed between two glass plates were measured using a SH7000 haze meter manufactured by Nippon Denshoku Industries Co., Ltd. according to the method specified in JIS K7361-1.

[0079] [Hardness of cured product] The photocurable liquid composition was placed in a glass cup with a diameter of 25 mm and a depth of 10 mm, and 405 nm LED light was irradiated under a nitrogen atmosphere with an illuminance of 50 mW / cm. 2 The hardness of the resulting cured product at room temperature was measured using a D-type durometer in accordance with ASTM D 2240.

[0080] [Refractive index of photocurable liquid composition and its cured product] Using the above-mentioned curable composition and the cured product prepared for hardness measurement, the refractive index at a wavelength of 847 nm was measured at room temperature with a Metricon Model 2010 / M prism coupler.

[0081] [Dielectric constant of cured product] Tin foil with a diameter of 33 mm and a thickness of 0.007 mm was pressure-bonded to both sides of the prepared organopolysiloxane cured product. To improve the adhesion between the cured product and the foil, a small amount of silicone oil was used for pressure bonding, if necessary. The capacitance was measured at room temperature and 100 KHz using a Keysight Technologies E4990A precision impedance analyzer connected to a parallel plate electrode with a diameter of 30 mm. The relative dielectric constant was calculated using the measured capacitance value, the thickness of the cured product measured separately, and the electrode area value.

[0082] [Examples 1 to 7, Comparative Example 1] A solventless photocurable liquid composition was prepared using the following components. Components (C), (D), and (E) were mixed in advance to prepare a catalyst solution. This catalyst solution, component (A), and optional component (B) were mixed at room temperature using a planetary centrifugal mixer to prepare a photocurable liquid composition. The mixing ratio of the components, the physical properties of the composition, and the characteristics of the cured product are summarized in Table 1.

[0083] The following compound was used as component (A). (A1) 1-[2-(3,4-epoxycyclohexyl)ethyl]-3,3-diphenyl-5-phenethyl-1,1,5,5-tetramethyltrisiloxane (A2) 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-3,3-diphenyl-1,1,5,5-tetramethyltrisiloxane

[0084] The following compound was used as component (B). (B1): 3-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,1,3,5,5,5-heptamethyltrisiloxane (B2): 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane

[0085] The following compound was used as component (C1). 4-Isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate

[0086] The following compound was used as component (E). 2-Isopropylthioxanthone

[0087] The following compound was used as component (D). 1,2-Epoxy-4-vinylcyclohexane

[0088] [Table 1]

[0089] From the results of Examples 1 to 7, the photocurable liquid silicone composition of the present invention has low viscosity and good transparency. It was also confirmed that the transparency of the cured product obtained by curing was high, and the refractive index, especially the refractive index in the infrared region, was high. In particular, as in Examples 6 and 7, it was possible to design a solventless photocurable liquid composition that can achieve both a high refractive index and a low dielectric constant of the cured product. On the other hand, from the results of Comparative Example 1, it was confirmed that the refractive index of the cured product obtained by photocuring was limited to 1.48 in the photocurable liquid composition made of siloxane that does not contain a monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms, and further, a cured product with a low dielectric constant could not be obtained. [Industrial Applicability]

[0090] The photocurable liquid composition of the present invention has a low viscosity at room temperature and is suitable for injection molding. In addition, it is rapidly cured by irradiation with long wavelength light, for example, visible light with a wavelength of 405 nm and ultraviolet light, which contributes to improving productivity. Furthermore, the obtained cured product has excellent transparency and a high refractive index, especially in the infrared region (1.50 or more), and is therefore useful as a material for devices using infrared LED light sources. In addition, the photocurable liquid composition of the present invention can be used to design a cured product that gives a low relative dielectric constant as necessary, and can also be suitably used for insulating layers / insulating coating layers that require optical properties.

Claims

1. (A) one or more organosilanes or organopolysiloxanes having, on average per molecule, one or more epoxy group-containing photoreactive functional groups, and two or more monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and having 1 to 5 silicon atoms; (C1) a photocationic polymerization initiator, (D) a silicon-atom-free photocurable compound represented by the formula: R x -R (wherein R x is an epoxy group-containing group and R is an alkenyl group having 2 to 6 carbon atoms); and (E) Photosensitizer wherein the viscosity of the entire liquid composition measured at 25°C using an E-type viscometer is 500 mPa·s or less, and the composition does not contain any organic solvent.

2. 2. The solventless photocurable liquid composition according to claim 1, which gives a cured product by photocuring reaction having a refractive index of 1.48 or more at 25°C and a wavelength of 847 nm.

3. The component (A) has an average composition formula (1); R Ｘ ａ R Ｙ ｂ R Ｚ ｃ SiO （４－ａ―ｂ－ｃ）／２ (1) (In the formula, R Ｘ is a photoreactive functional group, R Ｙ is a monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms; R Ｚ is a group selected from the group consisting of an unsubstituted or fluorine-substituted monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding monovalent functional groups selected from the group consisting of the photoreactive functional groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, a, b, and c are numbers that satisfy the following conditions: 1≦a+b+c≦3 and 0.08≦a / (a+b+c)≦0.5, and one or more R Ｘ and at least two R Ｙ ) 2. The solventless photocurable liquid composition according to claim 1, wherein the organopolysiloxane has 2 to 5 silicon atoms and is represented by the following formula:

4. The component (A) is (A1) The following formula (2): 【Chemistry 1】 （２） (Wherein, all R １ ~R ８ Among the groups, on average, one or more groups per molecule are photoreactive functional groups, and at least two of them are monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms; １ From R ８ each independently represents an unsubstituted or fluorine-substituted monovalent hydrocarbon group; and n is a number from 0 to 3; and (A2) The following formula (3): 【Chemistry 2】 （３） (In the formula, R ９ , R １０ are each independently a photoreactive functional group, a monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms, and a monovalent hydrocarbon group which is unsubstituted or substituted with fluorine; ９ , R １０ Among these, on average, one or more groups are photoreactive functional groups, at least two are monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and k is a number from 3 to 5. A cyclic organopolysiloxane represented by the formula: Mixtures of these organopolysiloxanes 2. The solventless photocurable liquid composition according to claim 1, wherein the organopolysiloxane is selected from the group consisting of:

5. 2. The photocurable liquid composition according to claim 1, wherein the number of photoreactive functional groups in component (A) is from 1 to 2 on average per molecule.

6. The solventless photocurable liquid composition according to any one of claims 1 to 4, further comprising (B) one or more organopolysiloxanes having an average of one or more photoreactive functional groups per molecule and having 2 to 10 silicon atoms (excluding organopolysiloxanes corresponding to the above-mentioned component (A)).

7. The component (B) is (B1) one or more organopolysiloxanes which have, on average, one or more photoreactive functional groups per molecule, contain less than two monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and have 2 to 5 silicon atoms; and (B2) One or more organopolysiloxanes having, on average, one or more photoreactive functional groups per molecule and having more than 5 and not more than 10 silicon atoms. The solventless photocurable liquid composition according to claim 6 , wherein the organic solvent is one or more selected from the following:

8. The solventless photocurable liquid composition according to any one of claims 1 to 7, wherein the refractive index of the entire liquid composition before curing at 25°C and a wavelength of 847 nm is 1.47 or more, and the viscosity of the entire liquid composition measured at 25°C using an E-type viscometer is 250 mPa s or less.

9. The solventless photocurable liquid composition according to any one of claims 6 to 8, wherein a mass ratio of the component (A) to the component (B) is in the range of 80:20 to 20:80, and upon photocuring, gives a cured product having a dielectric constant of 2.70 or less.

10. A cured product obtained by curing the solventless photocurable liquid composition according to any one of claims 1 to 9 through light irradiation.

11. An optical filler comprising the solventless photocurable liquid composition according to any one of claims 1 to 9.

12. A display device comprising a layer made of a cured product of the solventless photocurable liquid composition according to any one of claims 1 to 9.

13. A method for manufacturing a display device, comprising: a step of injecting the solventless photocurable liquid composition according to any one of claims 1 to 9 between a light source substrate and a transparent substrate; and a step of curing the injected photocurable liquid composition by irradiating it with high-energy rays.

Images