Ultraviolet-curable composition and its uses

Abstract

[Problem] To provide an ultraviolet ray curable composition containing silicon atoms, wherein a product obtained by curing said composition has a low refractive index, and has excellent workability when applied onto a base material. [Solution] The ultraviolet ray curable composition of the present invention comprises one or more organic silicon compounds (A) having an average of one or more ultraviolet ray-reactive functional groups per molecule, and is characterized in that the viscosity of the entire composition measured at 25°C using an E-type viscometer is 80 mPa·s or less, an organic solvent is not contained in the composition, and the refractive index of a cured product after curing when measured at 25°C and a wavelength of 589 nm is 1.45 or less.

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet ray-curable composition that can be cured by actinic rays, such as ultraviolet light or electron beams. Specifically, the present invention relates to an ultraviolet ray-curable composition containing an organosilicon compound, preferably an organosilane and / or an organopolysiloxane, and particularly to an ultraviolet ray-curable composition that provides a cured product having a low refractive index and excellent coatability. The curable composition of the present invention has a low refractive index of 1.45 or less, making it suitable as an insulating material for electronic and electrical devices, particularly as a coating material. Furthermore, the composition has excellent coatability and excellent wettability to substrates, making it useful as an inkjet printing material. [Background technology]

[0002] Due to their high heat resistance and excellent chemical stability, silicone resins have been used as coating agents, potting agents, insulating materials, etc. for electronic and electrical devices. Among silicone resins, ultraviolet-curable silicone compositions have also been reported.

[0003] Touch panels are used in a variety of display devices, including mobile devices, industrial equipment, and car navigation systems. To improve their detection sensitivity, it is necessary to suppress the electrical influence from light-emitting elements such as light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs), and an insulating layer is usually placed between the light-emitting elements and the touch screen.

[0004] On the other hand, thin display devices such as OLEDs have a structure in which many functional thin layers are stacked. In recent years, studies have begun to improve the brightness of the entire display device by combining high-refractive index layers and low-refractive index layers and stacking them on the touchscreen layer. In addition, inkjet printing is being adopted as a processing method for organic layers to improve productivity. Therefore, there is a demand for materials that can be processed by inkjet printing for the above-mentioned insulating layer as well.

[0005] JP 2019-73588 A discloses a photocurable resin composition comprising an unsaturated bond-containing aromatic compound and a compound having a mercapto group, and JP 2020-26515 A discloses a photocurable resin composition primarily composed of an unsaturated bond-containing naphthalene compound. Both compositions can be applied by inkjet printing, and the resulting cured products are characterized by a high refractive index of 1.60 or higher.

[0006] Meanwhile, Japanese Patent Publication No. 6200591 discloses an inkjet-coated sealant for electronic devices that comprises a UV-curable functional group-containing polysiloxane silicone and a specific curable compound, and Japanese Patent Application Laid-Open Publication No. 2019-189844 discloses a photocurable resin composition for electronic devices that comprises a polyfunctional cationically polymerizable compound and a specific monofunctional cationically polymerizable compound. These patent documents do not disclose the refractive index of the composition after curing, but when the refractive index is calculated based on the monomer structure in the curable composition, it is 1.48 or higher in both cases. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-73588 [Patent Document 2] Japanese Patent Publication No. 2020-26515 [Patent Document 3] Patent No. 6200591 [Patent Document 4] Japanese Patent Application Publication No. 2019-189844 Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, several UV-curable organopolysiloxane compositions are known, but there is still a need for UV-curable compositions that have a low refractive index of 1.45 or less when cured and that have excellent workability, particularly low viscosity, when applied to a substrate. The present invention aims to provide a curable composition, particularly a UV-curable composition, containing silicon atoms, that has a low refractive index when cured and that has excellent workability when applied to a substrate. [Means for solving the problem]

[0009] The present invention was achieved by discovering that UV-curable compositions obtained by using one or more organosilicon compounds (A) having, on average, one or more UV-reactive functional groups per molecule have low viscosity, excellent workability when applied to substrates, and a low refractive index when cured. The curable compositions of the present invention preferably use, as component (A), (A1) one or more organosilicon compounds having, on average, two or more UV-reactive functional groups per molecule, particularly organopolysiloxanes, and (A2) one or more organosilicon compounds having one UV-reactive functional group per molecule, particularly one or more organosilicon compounds selected from the group consisting of organosilanes and organopolysiloxanes. As component (A) of the composition of the present invention, one or more organosilicon compounds selected from the group consisting of components (A1) and (A2) can be used in a mass ratio of 100 / 0 to 0 / 100 (A1 / A2). That is, the curable composition of the present invention may use a combination of components (A1) and (A2) as component (A), or component (A1) or component (A2) may be used alone. When component (A2) alone is used as component (A), it is preferable to use it in combination with a compound having more than one, preferably two or more, reactive functional groups per molecule that can react with the ultraviolet-reactive functional group possessed by component (A2), preferably ultraviolet-reactive functional groups.

[0010] The present invention relates to an ultraviolet-curable composition comprising an organosilicon compound, and in particular to an ultraviolet-curable organopolysiloxane composition. This composition cures through the formation of bonds via ultraviolet-curable functional groups, but the curing method is not limited to ultraviolet irradiation; any method that can cause a curing reaction of the ultraviolet-curable functional groups can be used. For example, the composition of the present invention may be cured using electron beam irradiation.

[0011] The UV-curable composition of the present invention comprises one or more organosilicon compounds (A) having, on average, one or more UV-reactive functional groups per molecule, the viscosity of the entire composition measured at 25°C using an E-type viscometer being 80 mPa·s or less, the composition being free of organic solvents, and the refractive index of the cured product measured at 25°C and a wavelength of 589 nm being 1.45 or less when the composition is cured. Unless otherwise specified in this specification, the viscosity of a substance is a value measured at 25°C using an E-type viscometer.

[0012] The ultraviolet-reactive functional group contained in component (A) of the present invention is preferably a cationically polymerizable reactive group, and more preferably, the cationically polymerizable reactive group is an epoxy group-containing group.

[0013] The proportion of component (A) in the ultraviolet-curable composition of the present invention is preferably 80% or more by mass of the entire composition.

[0014] The component (A) of the present invention preferably contains (A1) one or more organosilicon compounds, preferably organopolysiloxanes, having an average of two or more UV-reactive functional groups per molecule, and (A2) one or more organosilicon compounds, preferably organosilanes and organopolysiloxanes, having one UV-reactive functional group per molecule, in a mass ratio of 100 / 0 to 0 / 100 (A1 / A2). Therefore, component (A) can be component (A1) alone, component (A2) alone, or a combination of components (A1) and (A2).

[0015] The above component (A2) has an average compositional formula: R c R’ d SiO (4-c―d) / 2 (2) (In the formula, R is an ultraviolet-reactive functional group, R’ is a group selected from a monovalent hydrocarbon group excluding an ultraviolet-reactive functional group, a hydroxyl group, and an alkoxy group, c and d are numbers satisfying the following conditions: 1 < c + d ≤ 4 and 0.05 ≤ c / (c + d) ≤ 0.25, and the number of R in the molecule is 1.) It is preferably an organosilicon compound selected from the group consisting of linear, branched, or cyclic organosilanes and organopolysiloxanes represented by the formula.)

[0016] The ratio of component (A2) contained in the ultraviolet-curable composition of the present invention is preferably 80% by mass or more of the whole composition.)

[0017] The above component (A1) has an average compositional formula: R a R’ b SiO (4-a―b) / 2 (1) (In the formula, R is an ultraviolet-reactive functional group, R’ is a group selected from a monovalent hydrocarbon group excluding an ultraviolet-reactive functional group, a hydroxyl group, and an alkoxy group, a and b are numbers satisfying the following conditions: 1 ≤ a + b ≤ 3 and 0.01 ≤ a / (a + b) ≤ 0.34, and it has at least two Rs in the molecule.) It is preferably an organopolysiloxane which is linear, branched, or cyclic and represented by the formula.) Component (A1) has a viscosity at 25°C of 1 to 1000 mPa·s.)

[0018] The organosilicon compound of component (A2) is represented by the following formula (3’):

Chemical formula

[0019] The organosilicon compound of component (A1) is represented by the following formula (3): [ka] (Wherein, all R 1 ~R 8 On average, two or more of the R groups per molecule are UV-reactive functional groups; 1 From R 8 each independently represents an unsubstituted or fluorine-substituted monovalent hydrocarbon group; and n is a value that provides a viscosity of the organopolysiloxane represented by formula (3) of 1 to 1000 mPa s at 25°C, but n may be 0), Average unit formula: (R3SiO 1 / 2 ) e (R2SiO 2 / 2 ) f (RSiO3 / 2 ) g (SiO 4 / 2 ) h (4) (In the formula, each R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, at least two of all R are ultraviolet-reactive functional groups, (g+h) is a positive number, e is 0 or a positive number, and f is a number in the range of 0 to 10.) An organopolysiloxane represented by the formula: The following formula (5): [ka] (wherein each R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, and x is an integer of 3 to 10, and the molecule contains at least two ultraviolet-reactive functional groups), and a mixture of two or more organopolysiloxanes arbitrarily selected from these.

[0020] The component (A1) preferably has an average of two ultraviolet-reactive functional groups per molecule.

[0021] The component (A2) is preferably an organopolysiloxane having one ultraviolet-reactive functional group in the molecule.

[0022] The ultraviolet-curable composition of the present invention preferably has a viscosity of the entire composition measured at 25° C. using an E-type viscometer of 80 mPa·s or less, particularly in the range of 5 to 30 mPa·s.

[0023] The component (A) is either (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane or a mixture of (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane and at least one compound selected from the following (A1), preferably in a mass ratio of 100 / 0 to 20 / 80 (A2 / A1). (A1): 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy]silane [cyclohexyl)ethyl]-cyclotetrasiloxane, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, 1,5-bis(3-glycidoxypropyl)-1,1,3,3,5,5-hexamethyltrisiloxane, methyl[tris(3-glycidoxypropyl)dimethylsiloxy]silane, tetrakis[(3-glycidoxypropyl)dimethylsiloxy]silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra(3-glycidoxypropyl)-cyclotetrasiloxane. However, the mass ratio of the above-mentioned component (A2) to the component (A1) is in a particularly preferred range, and the curable composition of the present invention can be obtained even when the proportion of the component (A1) relative to the total amount of the components (A2) and (A1) is more than 80 mass% and up to 100 mass%. In other words, only the component (A1) may be used as the component (A).

[0024] In one preferred embodiment of the present invention, the curable composition of the present invention contains, as component (A), (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane in an amount within the range of 50 to 95 mass % of the entire composition.

[0025] In one preferred embodiment of the ultraviolet-curable composition of the present invention, the composition further contains (B) a compound having one or more, preferably two or more, ultraviolet-reactive functional groups in one molecule and having no silicon atoms, and the mass ratio of component (B) to the total of component (A1), component (A2), and component (B) is less than 20%.

[0026] When the above-mentioned component (B) is used, the component (A) may be either the component (A1) alone, the component (A2) alone, or a combination of the components (A1) and (A2). However, when the component (A2) having one ultraviolet-reactive functional group per molecule is used as the component (A) without using the component (A1), it is particularly preferable to use the component (B).

[0027] The present invention further provides an insulating coating agent containing the above ultraviolet-curable composition. The ultraviolet-curable composition of the present invention is useful as an insulating coating agent.

[0028] The present invention further provides a method for using a cured product of the above ultraviolet-curable composition as an insulating coating layer.

[0029] The present invention further provides a display device, such as a liquid crystal display or an organic EL display, which comprises a layer made of a cured product of the above-mentioned ultraviolet-curable composition. DETAILED DESCRIPTION OF THE INVENTION

[0030] The configuration of the present invention will be described in further detail below. The UV-curable composition of the present invention contains, as an essential component, one or more organosilicon compounds (component (A)) having, on average, one or more UV-reactive functional groups per molecule, and may optionally contain a cationic photopolymerization initiator and components selected from various additives. However, the curable composition of the present invention is characterized by the absence of an organic solvent.

[0031] In this specification, the term "organosilicon compound" is used to refer to a concept including organosilanes, organosiloxane oligomers, and organopolysiloxanes.

[0032] In this specification, the term "polysiloxane" refers to a substance having a degree of polymerization of siloxane units (Si-O) of 2 or more, i.e., an average of two or more Si-O bonds per molecule, and polysiloxanes include siloxane oligomers such as disiloxane, trisiloxane, and tetrasiloxane, as well as siloxane polymers with higher degrees of polymerization.

[0033] Component (A) is one or more compounds selected from (A1) one or more organosilicon compounds having an average of two or more UV-reactive functional groups per molecule, and (A2) one or more organosilicon compounds having one UV-reactive functional group per molecule. The ratio of component (A1) / component (A2) can be selected from a range of 100 / 0 to 0 / 100. When component (A) contains only one UV-reactive functional group per molecule (e.g., consisting solely of component (A2)), it is preferable to include (B) a crosslinking component containing one or more, preferably two or more, UV-reactive functional groups per molecule but no silicon atoms, in order to promote crosslinking throughout the composition. When component (A) contains (A1) one or more organosilicon compounds having an average of two or more UV-reactive functional groups per molecule, crosslinking throughout the composition will proceed even without component (B). That is, component (B) is an optional crosslinking component that may be used depending on the type of component (A).

[0034] [Component (A): An organosilicon compound having, on average, one or more UV-reactive functional groups per molecule] The organosilicon compound having a UV-reactive functional group used as component (A), preferably one or more compounds selected from organosilanes and organopolysiloxanes, has an average of one or more UV-reactive functional groups per molecule, and its molecular structure can be any as long as this purpose is achieved. The UV-reactive functional group possessed by component (A) is preferably a cationically polymerizable functional group, and more preferably an epoxy group-containing group.

[0035] More specifically, component (A) is preferably one or more organosilicon compounds selected from the group consisting of components (A1) and (A2) described below. Component (A1) and component (A2) can be used alone or in combination as component (A), and the mass ratio of component (A1) to component (A2) can be 100 / 0 to 0 / 100 (A1 / A2). This mass ratio is preferably 100 / 20 to 0 / 100 (A1 / A2). One preferred embodiment is to use only component (A2) as component (A).

[0036] Component (A) preferably has a viscosity at 25°C of 1 to 1000 mPa·s, more preferably 1 to 500 mPa·s, particularly preferably 1 to 100 mPa·s, and most preferably 1 to 50 mPa·s.

[0037] Furthermore, component (A) contains 1 to 20, preferably 1 to 4, silicon atoms per molecule.

[0038] <Component (A1): An organosilicon compound having an average of two or more UV-reactive functional groups per molecule> The organosilicon compound of component (A1) has the following average composition formula: R a R' b SiO (4-a―b) / 2 (1) The organopolysiloxane is a linear, branched, or cyclic organopolysiloxane represented by the formula (I), preferably a linear or branched organopolysiloxane, and particularly preferably a linear organopolysiloxane.

[0039] In formula (1), R is a UV-reactive functional group, R' is a group selected from a monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding ultraviolet-reactive functional groups; a and b are numbers that satisfy the following conditions: 1≦a+b≦3 and 0.01≦a / (a+b)≦0.34, preferably 2≦a+b≦3 and 0.05≦a / (a+b)≦0.34.

[0040] The UV-reactive functional group represented by R in formula (1) is an organic group that can form a bond between itself upon irradiation with UV light in the presence or absence of a photoinitiator. Examples of UV-reactive functional groups include radically polymerizable groups and cationically polymerizable groups. The radically polymerizable group is not particularly limited as long as it is a functional group that can form a new bond, particularly a bond between radically polymerizable groups, through a radical reaction mechanism. Examples 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 acryloxypropyl, methacryloxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl. Examples of cationically polymerizable groups include vinyl ether groups, epoxy group-containing groups, and oxetane group-containing groups, such as CH₂=CH—O—(CH₂)₁— (n is an integer from 3 to 20), and glycidyloxy-(CH₂) n -(n is an integer from 3 to 20), 3,4-epoxycyclohexyl-(CH2) n - (n is an integer of 2 to 20). The UV-reactive functional group is preferably an epoxy group-containing group. Particularly preferred groups include glycidyloxyalkyl groups, such as glycidyloxypropyl groups, and epoxycyclohexylalkyl groups, particularly 3,4-epoxycyclohexylethyl groups. The linear, branched, or cyclic organopolysiloxane represented by the above average compositional formula has an average of at least two UV-reactive functional groups (R) per molecule. The average number of UV-curable groups per molecule is preferably 2 to 6, more preferably 2 to 4, particularly preferably 2 to 3, and most preferably 2.

[0041] R' is a monovalent hydrocarbon group, including unsubstituted monovalent hydrocarbon groups and fluorine-substituted monovalent hydrocarbon groups. The unsubstituted or fluorine-substituted monovalent hydrocarbon group is preferably a group selected from unsubstituted or fluorine-substituted alkyl, cycloalkyl, arylalkyl, and aryl groups having 1 to 20 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl, with methyl being particularly preferred. Examples of the cycloalkyl group include cyclopentyl and cyclohexyl. Examples of the arylalkyl group include benzyl and phenylethyl. Examples of the aryl group include phenyl and naphthyl. Examples of the fluorine-substituted monovalent hydrocarbon group include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl. A preferred fluorine-substituted monovalent hydrocarbon group is 3,3,3-trifluoropropyl.

[0042] The organopolysiloxane represented by formula (1) has a viscosity at 25°C of 1 to 1000 mPa s, 1 to 500 mPa s, or 1 to 100 mPa s, and most preferably 1 to 50 mPa s. The viscosity of the organopolysiloxane can be adjusted by changing the ratio of a and b in formula (1) and the molecular weight.

[0043] The organopolysiloxane represented by formula (1) preferably has an average of 2 to 20 silicon atoms, more preferably 2 to 5 silicon atoms per molecule.

[0044] In one preferred embodiment, the organopolysiloxane of component (A1) is The following formula (3): [ka] It is a compound represented by the formula:

[0045] Like the compound represented by formula (1), the organopolysiloxane represented by formula (3) has an average of two or more ultraviolet-reactive functional groups per molecule. 1 ~R 8 Among the groups, two or more per molecule are UV-reactive functional groups on average. UV-reactive functional groups are organic groups that can form bonds between themselves upon irradiation with UV light in the presence or absence of a photoinitiator. Examples of UV-reactive functional groups include radically polymerizable groups and cationically polymerizable groups. The radically polymerizable group is not particularly limited as long as it is a functional group that can form a new bond, particularly a bond between radically polymerizable groups, through a radical reaction mechanism. Examples 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 acryloxypropyl, methacryloxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl groups. Examples of cationically polymerizable groups include vinyl ether groups, epoxy group-containing groups, and oxetane group-containing groups, such as CH₂=CH—O—(CH₂)n— (n is an integer from 3 to 20), and glycidyloxy-(CH₂) n -(n is an integer from 3 to 20), 3,4-epoxycyclohexyl-(CH2) n - (n is an integer of 2 to 20). The ultraviolet-reactive functional group is preferably one or more epoxy-containing groups. Particularly preferred groups include glycidyloxyalkyl groups, particularly 3-glycidyloxypropyl groups, and epoxycyclohexylalkyl groups, particularly 3,4-epoxycyclohexylethyl groups.

[0046] In formula (3), R other than the ultraviolet-reactive functional group 1 From R 8 are each independently an unsubstituted or fluorine-substituted monovalent hydrocarbon group, preferably a group selected from unsubstituted or fluorine-substituted alkyl, cycloalkyl, arylalkyl, and aryl groups having 1 to 20 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl, with methyl being particularly preferred. Examples of the cycloalkyl group include cyclopentyl and cyclohexyl. Examples of the arylalkyl group include benzyl and phenylethyl. Examples of the aryl group include phenyl and naphthyl. Examples of the fluorine-substituted monovalent hydrocarbon group include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl. A preferred fluorine-substituted monovalent hydrocarbon group is 3,3,3-trifluoropropyl. Introducing fluorine atoms into the organopolysiloxane of formula (3) may further reduce the refractive index of the cured product obtained from the composition of the present invention.

[0047] The organopolysiloxane of formula (3), which is component (A1), has an average of 2 to 6 ultraviolet-reactive functional groups per molecule overall, preferably 2 to 5, more preferably 2 to 4, particularly preferably 2 to 3, and most preferably 2.

[0048] In particular, it is preferred that one of R1 to R3 and one of R6 to R8 in formula (3) is an ultraviolet-reactive functional group.Furthermore, it is particularly preferred that only one of R1 to R3 and one of R6 to R8 in formula (3) is an ultraviolet-reactive functional group.

[0049] In formula (3), n is a value that results in the viscosity of the organopolysiloxane represented by formula (3) at 25°C of preferably 1 to 1,000 mPa·s, more preferably 1 to 500 mPa·s, particularly preferably 1 to 100 mPa·s, and most preferably 1 to 50 mPa·s. Those skilled in the art can easily determine the value of n so that the viscosity of the organopolysiloxane of formula (3) falls within the aforementioned viscosity range without the need for excessive trial and error. However, it is generally preferred that the number of silicon atoms per molecule be 2 to 20, particularly 2 to 5, so that the compound of formula (3) has the desired viscosity.

[0050] The organopolysiloxane of formula (3) can be used alone or as a mixture of two or more. When two or more organopolysiloxanes are used as a mixture, the viscosity of the mixture at 25°C is preferably within the range described above.

[0051] The compound of formula (1) above may also be an organopolysiloxane represented by the following average unit formula (4). Average unit formula: (R3SiO 1 / 2 ) e (R2SiO 2 / 2 ) f (RSiO 3 / 2 ) g (SiO 4 / 2 ) h (4) In formula (4), each R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, at least two of all R are ultraviolet-reactive functional groups, (g+h) is a positive number, e is 0 or a positive number, and f is a number within the range of 0 to 10. The ultraviolet-reactive functional group and the monovalent hydrocarbon group are as defined above for formula (1), and the preferred viscosity of the organopolysiloxane represented by formula (4) is also as defined above for the organopolysiloxane represented by formula (1).

[0052] The number of ultraviolet-reactive functional groups possessed by the organopolysiloxane represented by formula (4) is preferably 2 to 5, more preferably 2 to 4, particularly preferably 2 to 3, and most preferably 2 per molecule.

[0053] The organopolysiloxane represented by formula (4) preferably has 2 to 20, and particularly preferably 2 to 5, silicon atoms per molecule.

[0054] Specific examples of organopolysiloxanes represented by the above formula (1), particularly formula (3) or formula (4), include 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, methyl[tris(3-glycidoxypropyl)dimethylsiloxy]silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, 1,5-bis(3-glycidoxypropyl)-1,1,3,3,5,5-hexamethyltrisiloxane, methyl[tris(3-glycidoxypropyl)dimethylsiloxy] ]silane, tetrakis[(3-glycidoxypropyl)dimethylsiloxy]silane, polydimethylsiloxane terminated at both ends with (3,4-epoxycyclohexylethyldimethylsilyl), polydimethylsiloxane terminated at both ends with (3-glycidoxypropyldimethylsilyl), copolymer terminated at both ends with trimethylsilyl-dimethylsiloxy / (methyl-3,4-epoxycyclohexylethylsiloxy), copolymer terminated at both ends with trimethylsilyl-dimethylsiloxy / (methyl-3-glycidoxypropylsiloxy), copolymer terminated at both ends with (3,4-epoxycyclohexylethyldimethylsilyl)-dimethylsiloxy / (methyl-3,4-epoxycyclohexylethylsiloxy), copolymer terminated at both ends with (3-glycidoxypropyldimethylsilyl)-dimethylsiloxy / (methyl-3-glycidoxypropylsiloxy) copolymer.

[0055] The compound of the above formula (1) can also be represented by the following formula (5): [ka] (wherein R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, and x is an integer of 3 to 10, and has at least two ultraviolet-reactive functional groups in the molecule).

[0056] The ultraviolet-reactive functional group and unsubstituted or fluorine-substituted monovalent hydrocarbon group that R in formula (5) can represent are as defined for formula (1) above.

[0057] The preferred viscosity of the organopolysiloxane represented by formula (5) is also as defined above for the organopolysiloxane represented by formula (1).

[0058] Specific examples of the cyclic organopolysiloxane represented by formula (5) include 1,3,5-trimethyl-1,3,5-tri[2-(3,4-epoxycyclohexyl)ethyl]cyclotrisiloxane, 1,3,5-trimethyl-1,3,5-tri(3-glycidoxypropyl)cyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxycyclohexyl)ethyl]cyclotetrasiloxane, Examples of suitable siloxanes include 1,3,5,7-tetramethyl-1,3,5,7-tetra(3-glycidoxypropyl)cyclotetrasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7,9-penta[2-(3,4-epoxycyclohexyl)ethyl]cyclopentasiloxane, and 1,3,5,7,9-pentamethyl-1,3,5,7,9-penta(3-glycidoxypropyl)cyclopentasiloxane.

[0059] The organopolysiloxanes represented by the above formulas (1) and (3) to (5) can be used either individually or in any combination of two or more as component (A1). As component (A1), it is particularly preferable to use one or more organosilicon compounds selected from the group consisting of organopolysiloxanes represented by the above formula (3), cyclic organopolysiloxanes represented by formula (5), and combinations thereof.

[0060] Component (A1) preferably has a viscosity at 25°C of the entire component (A1) of 1 to 1000 mPa·s, 1 to 500 mPa·s, 1 to 100 mPa·s, or preferably 1 to 50 mPa·s. When component (A1) is used in combination with component (A2) and / or component (B), even if the viscosity of component (A1) is relatively high, the viscosity of the entire composition can be made to be desired by using a low-viscosity compound as component (A2) and / or component (B).

[0061] Particularly preferred compounds for component (A1) are 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxycyclohexyl)ethyl]- and 1,3,5,7-tetramethyl-1,3,5,7-tetra(3-glycidoxypropyl)-cyclotetrasiloxane.

[0062] [Component (A2): An organosilicon compound having one UV-reactive functional group per molecule] Component (A2) is an organosilicon compound having an organosilane or organopolysiloxane skeleton and one UV-reactive functional group per molecule. Its main function is to control the crosslink density of the cured product obtained from the composition of the present invention, adjust the physical properties of the cured product, and at the same time reduce the viscosity of the composition. As long as this purpose can be achieved, its molecular structure can be any. As an example, the organosilicon compound of component (A2) is: The average composition formula is: Rc R' d SiO (4-c―d) / 2 (2) (wherein R is an ultraviolet-curable functional group, R' is a group selected from a monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding ultraviolet-curable functional groups; c and d are numbers that satisfy the following conditions: 1≦c+d≦4 and 0.05≦c / (c+d)≦0.25. The number of R in the numerator is 1. or a linear, branched, or cyclic organopolysiloxane represented by the following formula: One selected from the group consisting of these organosilanes and organopolysiloxanes may be used, or any two or more may be used in combination.

[0063] The UV-reactive functional group represented by R in formula (2) is an organic group that can form a bond between itself upon irradiation with UV light in the presence or absence of a photoinitiator. Examples of UV-reactive functional groups include radically polymerizable groups and cationically polymerizable groups. The radically polymerizable group is not particularly limited as long as it is a functional group that can form a new bond, particularly a bond between radically polymerizable groups, through a radical reaction mechanism. Examples 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 acryloxypropyl, methacryloxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl. Examples of cationically polymerizable groups include vinyl ether groups, epoxy group-containing groups, and oxetane group-containing groups, such as CH₂=CH—O—(CH₂)₁— (n is an integer from 3 to 20), and glycidyloxy-(CH₂) n -(n is an integer from 3 to 20), 3,4-epoxycyclohexyl-(CH2) n - (n is an integer of 2 to 20). The UV-reactive functional group is preferably one or more epoxy-containing groups. Particularly preferred groups include glycidyloxyalkyl groups, particularly glycidyloxypropyl groups, and epoxycyclohexylalkyl groups, particularly 3,4-epoxycyclohexylethyl groups. The organosilicon compound represented by the above average compositional formula has one UV-reactive functional group (R) per molecule.

[0064] The monovalent hydrocarbon groups represented by R' in formula (2) are each independently selected from the group consisting of unsubstituted monovalent hydrocarbon groups and fluorine-substituted monovalent hydrocarbon groups. The unsubstituted or fluorine-substituted monovalent hydrocarbon groups are preferably selected from unsubstituted or fluorine-substituted alkyl, cycloalkyl, arylalkyl, and aryl groups having 1 to 20 carbon atoms. Examples of the alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl, with methyl being particularly preferred. Examples of the cycloalkyl groups include cyclopentyl and cyclohexyl. Examples of the arylalkyl groups include benzyl and phenylethyl. Examples of the aryl groups include phenyl and naphthyl. Examples of fluorine-substituted monovalent hydrocarbon groups include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl. The fluorine-substituted monovalent hydrocarbon group is preferably a 3,3,3-trifluoropropyl group. By introducing fluorine atoms into the organopolysiloxane of formula (2), the refractive index of the cured product obtained from the composition of the present invention can sometimes be further reduced.

[0065] The organosilicon compound represented by formula (2) preferably has a viscosity at 25°C of 1 to 500 mPa·s, more preferably 1 to 100 mPa·s, and particularly preferably 1 to 50 mPa·s. The viscosity of the organosilicon compound can be adjusted by changing the ratio of c and d in formula (2) and the molecular weight.

[0066] The organosilicon compound represented by the above formula (2) is preferably a compound having 1 to 20, and more preferably 1 to 4, silicon atoms per molecule.

[0067] In one preferred embodiment, the organosilicon compound of component (A2) is The following formula (3'): [ka] The organopolysiloxane compound is represented by the formula:

[0068] As with the compound represented by formula (2), the organopolysiloxane represented by formula (3') is 1 ~R 8 One of the groups is a UV-reactive functional group.

[0069] As with the compound represented by formula (2) above, UV-reactive functional groups are organic groups that can form bonds between themselves upon irradiation with UV light in the presence or absence of a photoinitiator. Examples of UV-curable functional groups include radically polymerizable groups and cationically polymerizable groups. The radically polymerizable group is not particularly limited as long as it is a functional group that can form a new bond, particularly a bond between radically polymerizable groups, through a radical reaction mechanism. Examples 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 acryloxypropyl, methacryloxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl. Examples of cationically polymerizable groups include vinyl ether groups, epoxy group-containing groups, and oxetane group-containing groups, such as CH═CH—O—(CH)— (where n is an integer from 3 to 20), and glycidyloxy-(CH) n -(n is an integer from 3 to 20), 3,4-epoxycyclohexyl-(CH2) n - (n is an integer of 2 to 20). The ultraviolet-reactive functional group is preferably one or more epoxy-containing groups. Particularly preferred groups include glycidyloxyalkyl groups, such as glycidyloxypropyl groups, and epoxycyclohexylalkyl groups, particularly 3,4-epoxycyclohexylethyl groups.

[0070] In formula (3'), R other than the ultraviolet-reactive functional group 1 From R 8 are each independently an unsubstituted or fluorine-substituted monovalent hydrocarbon group, preferably a group selected from unsubstituted or fluorine-substituted alkyl, cycloalkyl, arylalkyl, and aryl groups having 1 to 20 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl, with methyl being particularly preferred. Examples of the cycloalkyl group include cyclopentyl and cyclohexyl. Examples of the arylalkyl group include benzyl and phenylethyl. Examples of the aryl group include phenyl and naphthyl. Examples of the fluorine-substituted monovalent hydrocarbon group include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl. A preferred fluorine-substituted monovalent hydrocarbon group is 3,3,3-trifluoropropyl. Introducing fluorine atoms into the organopolysiloxane of formula (3') can sometimes further reduce the refractive index of the cured product obtained from the composition of the present invention.

[0071] The organopolysiloxane represented by formula (3') has one ultraviolet-reactive functional group per molecule.

[0072] There are no restrictions on the position of the UV-curable functional group in the organopolysiloxane represented by formula (3'). Only the molecular terminal groups, i.e., only one of R1 to R3 or only one of R6 to R8, may be a UV-reactive functional group, or only one of the non-terminal groups R4 to R5 in formula (3') may be a UV-reactive functional group.

[0073] In formula (3'), n is preferably a value that results in the viscosity of the organopolysiloxane represented by formula (3') at 25°C of 1 to 500 mPa·s, more preferably 1 to 100 mPa·s, and particularly preferably 1 to 50 mPa·s. Those skilled in the art can easily determine the value of n so that the viscosity of the organopolysiloxane of formula (3') falls within the aforementioned viscosity range without the need for excessive trial and error. In general, the number of silicon atoms per molecule is preferably 2 to 20, more preferably 2 to 5, so that the compound of formula (3') has the desired viscosity.

[0074] The organopolysiloxane of formula (3') can be used alone or as a mixture of two or more. When two or more organopolysiloxanes are used as a mixture, the viscosity of the mixture at 25°C is 1 to 500 mPa·s, preferably 1 to 100 mPa·s, more preferably 1 to 50 mPa·s, and particularly preferably 5 to 20 mPa·s.

[0075] Specific examples of organopolysiloxanes having one UV-reactive functional group in the molecule, as represented by formula (3'), include 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,3-pentamethyldisiloxane, 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5,5-heptamethyltrisiloxane, 3-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,1,3,5,5,5-heptamethyltrisiloxane, and 1-[2-(3,4-epoxycyclohexyl)ethyl]-1,1,1,3,5,5,5-heptamethyltrisiloxane. 1-(3-glycidoxypropyl)-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane, 1-(3-glycidoxypropyl)-1,1,3,3,3-pentamethyldisiloxane, 1-(3-glycidoxypropyl)-1,1,3,3,5,5,5-heptamethyltrisiloxane, 3-(3-glycidoxypropyl)-1,1,1,3,5,5,5-heptamethyltrisiloxane, and 1-(3-glycidoxypropyl)-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane.

[0076] The organosilicon compound of the above formula (2) may also be a cyclic organopolysiloxane represented by the following formula (4'). formula: [ka] In formula (4'), each R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, and x is an integer of 3 to 5, and there is only one ultraviolet-reactive functional group in the molecule.

[0077] The ultraviolet-reactive functional group and the monovalent hydrocarbon group are as defined above for formula (2).

[0078] The preferred viscosity of the cyclic organopolysiloxane represented by formula (4') is the same as that defined above for the organopolysiloxane represented by formula (2). Therefore, the viscosity at 25°C is preferably 1 to 500 mPa·s, more preferably 1 to 100 mPa·s, and particularly preferably 1 to 50 mPa·s.

[0079] Specific examples of the cyclic organopolysiloxane represented by formula (4') include [2-(3,4-epoxycyclohexyl)ethyl]pentamethylcyclotrisiloxane, [2-(3,4-epoxycyclohexyl)ethyl]heptamethylcyclotetrasiloxane, [2-(3,4-epoxycyclohexyl)ethyl]nonamethylcyclopentasiloxane, 3-glycidoxypropyl-pentamethylcyclotrisiloxane, 3-glycidoxypropyl-heptamethylcyclotetrasiloxane, and 3-glycidoxypropyl-nonamethylcyclopentasiloxane.

[0080] Furthermore, component (A2) may be an organosilane represented by the following formula (5'). Formula: RSiR'3(5') In formula (5'), R is an ultraviolet-reactive functional group, and R' is a group selected from a monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding ultraviolet-reactive functional groups. The ultraviolet-reactive functional group and the monovalent hydrocarbon group are as defined for formula (2), and the alkoxy group is an alkoxy group having 1 to 20 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms, or a cycloalkyl group having 5 to 20 carbon atoms. Specifically, a methoxy group, an ethoxy group, an isopropoxy group, a cyclopentyl group, or a cyclohexyl group is preferred.

[0081] The preferred viscosity of the organosilane represented by formula (5') is the same as that defined above for the organopolysiloxane represented by formula (2). Therefore, the viscosity at 25°C is preferably 1 to 500 mPa·s, more preferably 1 to 100 mPa·s, and particularly preferably 1 to 50 mPa·s.

[0082] Specific examples of organosilanes represented by formula (5') include [2-(3,4-epoxycyclohexyl)ethyl]triethylsilane, [2-(3,4-epoxycyclohexyl)ethyl]dimethylphenylsilane, [2-(3,4-epoxycyclohexyl)ethyl]dimethyloctylsilane, [2-(3,4-epoxycyclohexyl)ethyl]dimethylcyclohexylsilane, [2-(3,4-epoxycyclohexyl)ethyl]trihexylsilane, [2-(3,4-epoxycyclohexyl)ethyl]tributylsilane, 3-glycidoxypropyltriethylsilane, 3-glycidoxypropyldimethylphenylsilane, 3-glycidoxypropyldimethyloctylsilane, 3-glycidoxypropyldimethylcyclohexylsilane, 3-glycidoxypropyltrihexylsilane, and 3-glycidoxypropyltributylsilane.

[0083] The organosilicon compounds represented by the above formula (2), (3'), (4'), or (5') can be used singly or in any combination of two or more. That is, the organosilicon compounds represented by the formula (2), (3'), (4'), or (5'), and mixtures of two or more selected therefrom, can be used as component (A2) of the composition of the present invention.

[0084] As component (A2), it is preferable to use an organosilicon compound selected from organopolysiloxanes represented by formula (3'), cyclic organopolysiloxanes represented by formula (4'), and combinations thereof.

[0085] It is particularly preferred to use 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane as component (A2).

[0086] As component (A), only component (A1) or only component (A2) can be used, or components (A1) and (A2) can be used in combination. The mass ratio of components (A1) and (A2) can be any mass ratio within the range of 100 / 0 to 0 / 100 (A1 / A2), but the proportion of component (A2) relative to the total amount of components (A1) and (A2) (100 mass%) is 50 mass% or more, preferably 65 mass% or more, more preferably 70 mass% or more, and most preferably 75 mass% or more.

[0087] Furthermore, the curable composition of the present invention preferably contains component (A) in an amount of 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the composition. The curable composition of the present invention may consist solely of component (A), and therefore the upper limit of this amount is 100% by mass.

[0088] When component (A1) and component (A2) are used in combination as component (A), the following compound is used as component (A1): 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy]silane 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, 1,5-bis(3-glycidoxypropyl)-1,1,3,3,5,5-hexamethyltrisiloxane, methyl[tris(3-glycidoxypropyl)dimethylsiloxy]silane, tetrakis[(3-glycidoxypropyl)dimethylsiloxy]silane, and 1,3,5,7-tetramethyl-1,3,5,7-tetra(3-glycidoxypropyl)-cyclotetrasiloxane It is preferred to use one compound or a combination of two or more compounds selected from the group consisting of the following in combination with 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane as component (A2), and the mass ratio of component (A2) to component (A1) is preferably 100 / 0 to 20 / 80 (A2 / A1), more preferably 100 / 0 to 50 / 50, and particularly preferably 100 / 0 to 75 / 25. However, this mass ratio of component (A1) to component (A2) is a value that defines a particularly preferred range, and the curable composition of the present invention can also be prepared using only the above-mentioned component (A1).

[0089] When the curable composition of the present invention contains (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane as component (A), the amount thereof is within a range of 50 to 95% by mass of the total curable composition, preferably 65 to 95%, and more preferably 75 to 95%.

[0090] When the above-mentioned components (A1) and (A2) are used in combination as component (A), it is preferable that the ultraviolet-reactive functional group possessed by component (A1) and the ultraviolet-reactive functional group possessed by component (A2) are the same type of reactive functional group. Therefore, when the ultraviolet-reactive functional group possessed by component (A1) is a radically polymerizable group, it is preferable that the ultraviolet-reactive functional group possessed by component (A2) is also a radically polymerizable group. Furthermore, when the ultraviolet-reactive functional group possessed by component (A1) is a cationically polymerizable group, it is preferable that the ultraviolet-reactive functional group possessed by component (A2) is also a cationically polymerizable group. It is preferable that both components (A1) and (A2) have cationically polymerizable reactive groups as their ultraviolet-reactive functional groups.

[0091] [Component (B): A compound that has one or more UV-reactive functional groups in one molecule and does not contain a silicon atom] In addition to the above-mentioned component (A), or component (A1) and / or component (A2), the curable composition of the present invention may further contain a compound (component (B)) having one or more UV-reactive functional groups in one molecule but having no silicon atoms. In particular, when component (A2) is used alone as component (A), it is preferable to use component (B) in addition to component (A2). The use of component (B) in combination with component (A2) may improve the curability of the composition.

[0092] The UV-reactive functional group contained in component (B) can be the same as those listed in relation to components (A), (A1), and (A2). Component (B) differs from components (A), (A1), and (A2) in that the latter contain silicon atoms in their molecules, whereas component (B) does not. As long as the compound does not contain silicon atoms in its molecule and has one or more of the above-mentioned UV-reactive functional groups in its molecule, the chemical structure of the compound is not particularly limited, and any compound can be used as component (B).

[0093] Component (B) can be an organic compound having an epoxy group in the molecule, particularly a compound having an epoxy group but not a cyclic structure. Specific examples of preferred component (B) include, but are not limited to, 2-ethylhexyl glycidyl ether, glycidyl lauryl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,2-epoxydecane, 1,2-epoxydodecane, and 1,7-octadiene diepoxide. 1,2-epoxydodecane, 1,7-octadiene diepoxide, and 1,4-butanediol diglycidyl ether are particularly preferred.

[0094] Component (B) may also include organic compounds having a radically polymerizable reactive group as a UV-reactive functional group in the molecule, such as known (meth)acrylic acid ester compounds having one radically polymerizable reactive group in the molecule and (meth)acrylic acid ester compounds having two or more radically polymerizable reactive groups.

[0095] The UV-reactive functional group of component (B) is preferably the same type of functional group as the UV-reactive functional group of component (A) or component (A1) and / or component (A2) used in combination with component (B). Therefore, for example, if the UV-reactive functional group of component (A1) and / or component (A2) is a radically polymerizable group, the UV-reactive functional group of component (B) is also preferably a radically polymerizable group. Furthermore, if the UV-reactive functional group of component (A1) and / or component (A2) is a cationically polymerizable group, the UV-reactive functional group of component (B) is also preferably a cationically polymerizable group. It is preferred that both component (A1) and / or component (A2) and component (B) have a cationically polymerizable reactive group, particularly preferably an epoxy group, as the UV-reactive functional group.

[0096] The viscosity of component (B) at 25°C is preferably 1 to 1000 mPa·s, more preferably 1 to 500 mPa·s, particularly preferably 1 to 100 mPa·s, and most preferably 1 to 50 mPa·s.

[0097] When component (B) is used in addition to components (A1) and / or (A2), the mass ratio of component (B) to the total amount of components (A1), (A2), and (B) contained in the curable composition of the present invention is less than 20%, preferably less than 10%, particularly preferably less than 5%.

[0098] [Composition containing no organic solvent] In this specification, "free of organic solvent" means that the content of organic solvent is less than 0.05% by mass of the total composition, and preferably is below the analytical limit using an analytical method such as gas chromatography. In the present invention, by adjusting the molecular structure and molecular weight of components (A) and (B), the desired viscosity can be achieved without using an organic solvent.

[0099] [Photopolymerization initiator] In addition to the component (A), a photopolymerization initiator can be optionally added to the UV-curable composition of the present invention. In this case, when the UV-reactive functional group of component (A) is a cationically polymerizable functional group containing an epoxy or vinyl ether, a photocationic polymerization initiator is used as the photopolymerization initiator. Known examples of photocationic polymerization initiators include compounds capable of generating a Brønsted acid or Lewis acid upon irradiation with UV or an electron beam, known as photoacid generators. It is known that an acid is generated upon irradiation with UV or an electron beam, and this acid then initiates a reaction between cationically polymerizable functional groups. Furthermore, when the UV-reactive functional group is a radically polymerizable functional group, a photoradical polymerization initiator can be used as the photopolymerization initiator. The photoradical polymerization initiator generates free radicals upon irradiation with UV or an electron beam, which then initiate a radical polymerization reaction, thereby curing the composition of the present invention. When the composition of the present invention is cured by electron beam irradiation, a polymerization initiator is generally not required.

[0100] (1) Photocationic polymerization initiator The photocationic polymerization initiator used in the curable composition of the present invention can be arbitrarily selected from those known in the art and is not particularly limited to a specific one. Known photocationic polymerization initiators include strong acid-generating compounds such as diazonium salts, sulfonium salts, iodonium salts, and phosphonium salts, 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, commercially available photoinitiators include Omnicat 250, Omnicat 270 (both manufactured by IGM Resins BV), CPI-310B, IK-1 (both manufactured by San-Apro Co., Ltd.), DTS-200 (Midori Chemical Co., Ltd.), and Irgacure 290 (BASF).

[0101] The amount of the cationic photopolymerization initiator added to the curable composition of the present invention is not particularly limited as long as the desired photocuring reaction occurs, but it is generally preferred to use the cationic photopolymerization initiator in an amount of 0.1 to 10 mass %, preferably 0.2 to 5 mass %, and particularly 0.5 to 4 mass %, relative to the total amount of component (A) of the present invention.

[0102] When the UV-reactive functional group possessed by component (A) is a photocationic polymerization initiator such as an epoxy group, a photoradical polymerization initiator described below can be used in combination with the above-described photocationic polymerization initiator as the polymerization initiator. The use of both initiators in combination may improve the curability of the UV-curable organopolysiloxane composition.

[0103] (2) Photoradical polymerization initiator Photoradical polymerization initiators are broadly 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-anisil, benzil, 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, 2-benzyl-2-(dimethylamino)- 4'-Morpholinobutyrophenone, (±)-Camphorquinone, 2-Chlorothioxanthone, 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-Hydroxycyclohexylphenylketone, 2-Hydroxy-2-methylpropiophenone, 2-Hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-Isopropylthioxanthone, Lithium These include, but are not limited to, phenyl(2,4,6-trimethylbenzoyl)phosphinate, 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, other examples of photoradical polymerization initiators 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 photopolymerization initiators, IGM Resins BV), and Irgacure OXE01 and OXE02 (oxime ester-based non-polymerization initiators, BASF).

[0104] 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.

[0105] A photosensitizer can also be used in combination with the cationic or radical photopolymerization initiator. The use of a sensitizer can increase the photon quantum efficiency of the polymerization reaction, allowing longer wavelengths of light to be utilized in the polymerization reaction compared to when a photoinitiator alone is used. This is known to be particularly effective when the coating thickness of the composition is relatively thick or when a relatively long-wavelength LED light source is used. Known sensitizers include anthracene-based compounds, phenothiazine-based compounds, perylene-based compounds, cyanine-based compounds, merocyanine-based compounds, coumarin-based compounds, benzylidene ketone-based compounds, (thio)xanthene or (thio)xanthone-based compounds, such as isopropylthioxanthone, 2,4-diethylthioxanthone, squarylium-based compounds, (thia)pyrylium-based compounds, and porphyrin-based compounds. However, any photosensitizer can be used in the curable composition of the present invention.

[0106] The cured product obtained from the curable composition of the present invention can be designed to have the desired physical properties, curing speed, and viscosity depending on the molecular chain length of component (A) or component (A1) and / or component (A2), the number of UV-reactive functional groups per molecule, the position of the UV-reactive functional groups within the molecule, and the molecular structure. Cured products obtained by curing the curable composition of the present invention are also within the scope of the present invention. Furthermore, the shape of the cured product obtained from the composition of the present invention is not particularly limited. It may be a thin-film coating layer or a molded product such as a sheet. It may be injected into a specific location in an uncured state and cured to form a filler, or it may be used as a sealant or intermediate layer in a laminate or display device. The cured product obtained from the composition of the present invention is particularly preferably in the form of a thin-film coating layer, and particularly preferably an insulating coating layer.

[0107] The curable compositions of the present invention are suitable for use as coatings or potting agents, particularly insulating coatings or potting agents for electronic and electrical devices.

[0108] The curable composition of the present invention preferably has a viscosity of the entire composition measured at 25°C using an E-type viscometer of 80 mPa·s or less, preferably 30 mPa·s or less, and more preferably 20 mPa·s or less.

[0109] The cured product obtained by curing the curable composition of the present invention is characterized by a refractive index of 1.45 or less when measured at 25° C. and a wavelength of 589 nm.

[0110] If desired, the cured product obtained by curing the curable composition of the present invention can be designed so that its dielectric constant is less than 3.0, less than 2.8, etc., and the curable composition of the present invention can also be used to form a coating layer having a low dielectric constant.

[0111] When the curable composition of the present invention is used as a coating agent, in order to provide the composition with fluidity and workability suitable for application to a substrate, the viscosity of the entire composition, as measured using an E-type viscometer, is preferably 80 mPa·s or less, more preferably 1 to 60 mPa·s, even more preferably 5 to 30 mPa·s, and particularly preferably 5 to 20 mPa·s at 25°C. In order to adjust the viscosity of the entire curable composition to a desired viscosity, compounds having a preferred viscosity can be used as each component so that the viscosity of the entire composition is the desired viscosity.

[0112] To adjust the viscosity of the curable composition, improve application properties, and adjust the physical properties of the cured product, the aforementioned component (B), a compound having one or more UV-reactive functional groups per molecule but not containing silicon atoms, may be added to the composition, or the amount added may be adjusted. To suppress an increase in the refractive index, the content of component (B) in the curable composition of the present invention is preferably an amount such that the mass ratio of component (B) to the total of components (A) and (B) is less than 50%. The mass ratio of component (B) to the total of components (A) and (B) is preferably less than 20%, more preferably less than 10%, and even more preferably less than 5%.

[0113] [Component (C)] When the UV-curable organopolysiloxane composition of the present invention is applied to the surface of a substrate as a coating agent by any method, the composition can be further added with component (C) selected from the following to improve the wetting of the composition to the substrate and form a defect-free coating film. It is particularly preferred to use inkjet printing as a method for coating the composition of the present invention onto a substrate. Therefore, component (C) is a component that improves the wetting of the UV-curable organopolysiloxane composition of the present invention to the substrate, thereby significantly improving the inkjet printing properties in particular. Component (C) is at least one compound selected from the group consisting of (C1), (C2), and (C3) below.

[0114] (i) Component (C1) Component (C1) is a silicon-free, non-acrylic nonionic surfactant, i.e., a non-acrylic nonionic surfactant. Non-acrylic refers to a surfactant that does not have a (meth)acrylate group in its molecule. Examples of surfactants that can be used as component (C1) include organic nonionic surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, alkyl glycosides, and acetylene glycol polyethers, as well as fluorine-containing nonionic surfactants. These surfactants can be used alone or in combination. Specific examples of component (C1) include organic nonionic surfactants such as the Emulgen series and Rheodol series manufactured by Kao Corporation, the Surfynol 400 series manufactured by Evonik Industries, and the Olfin E series manufactured by Nissin Chemical Industry Co., Ltd.; and fluorine-containing nonionic surfactants such as the FC-4400 series manufactured by 3M and the Megafac 550 and 560 series manufactured by DIC Corporation. Among these, the alkynol polyethers Surfynol 400 series and Olfine E series are particularly preferred.

[0115] (ii) Component (C2) is a nonionic surfactant containing a silicon atom and having an HLB value of 4 or less. Here, the HLB value indicates the degree of affinity of a surfactant for water and organic compounds. Here, the HLB value is the value defined by the Griffin method (20 × sum of formula weights of hydrophilic moieties / molecular weight). Known silicon-containing nonionic surfactants include silicone polyethers having polyethers as the hydrophilic moiety, glycerol silicones having (di)glycerol derivatives as the hydrophilic moiety, and carbinol silicones having hydroxyethoxy groups as the hydrophilic moiety. Among these surfactants, those with an HLB value of 4 or less, i.e., those with a hydrophilic moiety mass fraction of 20% by mass or less, are preferably used in the composition of the present invention. Among these, carbinol silicones are particularly preferred.

[0116] (iii) Component (C3) is a silicone oil having a viscosity of 90 mPa·s or less at 25°C. Examples of silicone oils include polydimethylsiloxane terminated with trimethylsilyl groups at both ends, polydimethylsiloxane terminated with dimethylvinylsilyl groups at both ends, copolymers of trimethylsilyl-dimethylsiloxy and methylvinylsiloxy groups at both ends, copolymers of dimethylvinylsilyl-dimethylsiloxy and methylvinylsiloxy groups at both ends, copolymers of trimethylsilyl-dimethylsiloxy and methylphenylsiloxy groups at both ends, copolymers of trimethylsilyl-dimethylsiloxy and diphenylsiloxy groups at both ends, copolymers of dimethylvinylsilyl-dimethylsiloxy and methylphenylsiloxy groups at both ends, and copolymers of dimethylvinylsilyl-dimethylsiloxy and diphenylsiloxy groups at both ends. Of these, polydimethylsiloxane terminated with trimethylsilyl groups at both ends and polydimethylsiloxane terminated with dimethylvinylsilyl groups at both ends are preferred. The viscosity range of the silicone oil is preferably 2 to 50 mPa·s, more preferably 2 to 30 mPa·s, and even more preferably 5 to 20 mPa·s, where the viscosity values ​​are measured at 25°C using the rotational viscometer described in the examples.

[0117] The above-mentioned components (C1) to (C3) can be used singly or in combination of two or more thereof. The amount of component (C) in the curable composition is not particularly limited. However, the total amount of components (C1) to (C3) (collectively referred to as component (C)) is preferably 0.05% by mass or more and 1% by mass or less, where the total amount of the above-mentioned component (A) and, if present, component (B) is taken as 100% by mass. If the amount of component (C) is less than 0.05% by mass relative to 100% by mass of the combined amount of components (A) and (B), the effect of improving the wettability of the curable composition to the substrate may not be sufficiently obtained. Furthermore, if the amount of component (C) is more than 1% by mass relative to 100% by mass of the combined amount of components (A) and (B), bleed-out of component (C) from the cured product after curing may occur.

[0118] As component (C), it is preferable to use the silicone oil of component (C3) alone or in combination with one or more components selected from the group consisting of components (C1) and (C2), and it is particularly preferable to use component (C3) alone as component (C).

[0119] <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:

[0120] [Adhesion imparting agent] An adhesion promoter can be added to the composition of the present invention to improve adhesion or cohesion to a substrate in contact with the composition. When the curable composition of the present invention is used for applications requiring adhesion or cohesion to a substrate, such as a coating agent or a sealant, it is preferable to add an adhesion promoter to the curable composition of the present invention. Any known adhesion promoter can be used as this adhesion promoter, as long as it does not inhibit the curing reaction of the composition of the present invention.

[0121] 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 and 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 and having about 4 to 20 silicon atoms; organosilanes having a trialkoxysiloxy group or 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 and having about 4 to 20 silicon atoms; organic compounds having two or more trialkoxysilyl groups (e.g., trimethoxysilyl group, triethoxysilyl group);Examples include reaction products of aminoalkyltrialkoxysilanes and epoxy group-bonded alkyltrialkoxysilanes, and epoxy group-containing ethyl polysilicates. Specific examples 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;

[0122] The amount of adhesion promoter added to the curable composition of the present invention is not particularly limited, but is preferably within the range of 0.01 to 5 parts by mass, or 0.01 to 2 parts by mass, per 100 parts by mass of the total of components (A) and (B), in order to avoid promoting the curing characteristics of the curable composition or discoloration of the cured product.

[0123] [Other additives] In addition to or instead of the adhesion promoter described above, 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 listed above, ultraviolet absorbers, antioxidants, polymerization inhibitors, and fillers (functional fillers such as reinforcing fillers, insulating fillers, and thermally conductive fillers). Appropriate additives can be added to the composition of the present invention as needed. Furthermore, a thixotropic agent may be added to the composition of the present invention as needed, particularly when used as a potting agent or sealing material.

[0124] [Refractive Index of the Cured Product of the Composition of the Present Invention] The cured product obtained from the UV-curable organopolysiloxane composition of the present invention can have a low refractive index, which is 1.45 or less when measured at 25° C. and a wavelength of 589 nm.

[0125] [Application] The ultraviolet-curable organopolysiloxane composition of the present invention can be cured not only by ultraviolet light but also by electron beams, which is also one embodiment of the present invention.

[0126] The curable composition of the present invention has a low viscosity and is particularly useful as a material for forming insulating layers that constitute various articles, particularly electronic and electrical devices. The composition of the present invention can be applied to a substrate or sandwiched between two substrates, at least one of which is transparent to ultraviolet light or an electron beam, and cured by irradiating the composition with ultraviolet light or an electron beam to form an insulating layer. In this case, a pattern can be formed when the composition of the present invention is applied to the substrate and then cured. Alternatively, the composition can be applied to a substrate and cured by irradiating ultraviolet light or an electron beam, leaving both cured and uncured portions, and then removing the uncured portions with a solvent to form an insulating layer with a desired pattern. In particular, when the cured layer of the present invention is an insulating layer, it can be designed to have a low dielectric constant of less than 3.0.

[0127] The curable composition of the present invention has good transparency in the cured product obtained therefrom, and is therefore particularly suitable as a material for forming an insulating layer in display devices such as touch panels and displays. In this case, the insulating layer may be formed into any desired pattern as described above, if necessary. Therefore, display devices such as touch panels and displays that include an insulating layer obtained by curing the ultraviolet-curable organopolysiloxane composition of the present invention are also an embodiment of the present invention.

[0128] Furthermore, an insulating coating layer (insulating film) can be formed by coating an article with the curable 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. Furthermore, a cured product formed by curing the curable composition of the present invention can also be used as an insulating coating layer.

[0129] The insulating film formed from the curable composition of the present invention can be used in a variety of 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 LSIs, system LSIs, DRAMs, SDRAMs, RDRAMs, D-RDRAMs, and multi-chip module multilayer wiring boards, an interlayer insulating film for semiconductors, an etching stopper film, a surface protective film, a buffer coating film, a passivation film in LSIs, a cover coat for flexible copper-clad boards, a solder resist film, and a surface protective film for optical devices.

[0130] In addition to being used as a coating agent, the ultraviolet-curable 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.

[0131] The composition of the present invention can be used as a material for forming a coating layer on the surface of a substrate, particularly using an inkjet printing method. In this case, it is particularly preferable that the composition of the present invention contains the above-mentioned component (C).

[0132] The present invention will be further described below based on examples, but the present invention is not limited to the following examples. [Example]

[0133] The ultraviolet-curable composition of the present invention and its cured product will be described in detail with reference to the following examples. Measurements and evaluations in the examples and comparative examples were carried out as follows.

[0134] [Viscosity of curable composition] The viscosity (mPa·s) of the composition at 25° C. was measured using a rotational viscometer (E-type viscometer VISCONIC EMD, manufactured by Tokimec Inc.).

[0135] [Refractive index of curable composition and cured product thereof] The refractive index (nD) of the cured product at 25°C was measured using a digital refractometer (RX-7000α, manufactured by Atago Co., Ltd.).

[0136] [Appearance of the curable composition and the cured product obtained therefrom] The appearance of the curable composition and the cured product obtained therefrom was visually observed and evaluated.

[0137] [Preparation of Curable Composition] The materials in the amounts shown in Table 1 below were placed in a brown plastic container and mixed thoroughly using a planetary mixer to prepare a curable composition.

[0138] [Curing of curable composition] Approximately 0.2 g of the curable composition was poured between two glass substrates sandwiching a 0.18 mm thick spacer. LED light with a wavelength of 405 nm was irradiated from the outside through one of the glass substrates at 2 J / cm. 2The composition was cured by irradiation with an energy amount of 1000 kJ / cm 2 , to prepare a plate-shaped cured product having a side length of 30 mm and a thickness of 0.18 mm.

[0139] [Examples and Comparative Examples] Using the components below, ultraviolet-curable compositions having the compositions (parts by mass) shown in Table 1 were prepared. (A1a) 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane (A1b) 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane (B1) 1,2-epoxydodecane (B2) 1,7-octadiene diepoxide (C) A catalyst masterbatch composed of the following components: C:(C1) / (X) / (A2)=30 / 2.4 / 67.6 (mass ratio) (C1): 4-Isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (X): 2-Isopropylthioxanthone

[0140] [Table 1]

[0141] As shown in Table 1, the ultraviolet-curable compositions of the present invention (Examples 1 to 3) have a viscosity suitable for application to a substrate as a coating agent at 25°C and are highly transparent. Furthermore, the refractive index of the cured product is 1.45 or less. On the other hand, the compositions not containing component (A2) (Comparative Examples 1 and 2) either have a refractive index of 1.46 or more, or are insufficient in curability. [Industrial Applicability]

[0142] The ultraviolet-curable composition of the present invention is particularly suitable for the above-mentioned applications, in particular as a material for forming an insulating layer in display devices such as touch panels and displays. The present invention includes the following aspects. [1] It contains one or more organosilicon compounds (A) having an average of 1 or more ultraviolet-reactive functional groups in one molecule, the viscosity of the whole composition measured at 25 °C using an E-type viscometer is 80 mPa·s or less, and the composition does not contain an organic solvent, and the refractive index of the cured product after curing measured at 25 °C and a wavelength of 589 nm is 1.45 or less. An ultraviolet-curable composition characterized by this. [2] The ultraviolet-curable composition according to Aspect 1, wherein the ultraviolet-reactive functional group is a cationic polymerizable functional group. [3] The ultraviolet-curable composition according to Aspect 1 or 2, wherein the ultraviolet-reactive functional group is an epoxy group-containing group. [4] The ultraviolet-curable composition according to any one of Aspects 1 to 3, wherein the ratio of component (A) in the curable composition is 80% by mass or more. [5] Component (A) is one or more organosilicon compounds selected from the group consisting of (A1) one or more organosilicon compounds having an average of 2 or more ultraviolet-reactive functional groups in one molecule and (A2) one or more organosilicon compounds having 1 ultraviolet-reactive functional group in one molecule, and is contained at a mass ratio of 100 / 0 to 0 / 100 (A1 / A2). The ultraviolet-curable composition according to any one of Aspects 1 to 4. [6] Component (A2) has an average composition formula: R c R’ d SiO (4-c―d) / 2 (2) (In the formula, R is an ultraviolet-reactive functional group, R' is a group selected from a monovalent hydrocarbon group excluding an ultraviolet-reactive functional group, a hydroxyl group, and an alkoxy group, c and d are numbers that satisfy the following conditions: 1 < c + d ≦ 4 and 0.05 ≦ c / (c + d) ≦ 0.25, and the number of R in the molecule is 1.) The ultraviolet-curable composition according to Aspect 5, which is an organosilicon compound selected from the group consisting of linear, branched, or cyclic organosilanes and organopolysiloxanes represented by the formula. [7] The ultraviolet-curable composition according to Aspect 5 or 6, wherein the ratio of component (A2) in the composition is 80% by mass or more. [8] Component (A1) has an average composition formula: R a R’ b SiO (4-a―b) / 2 (1) (In the formula, R is an ultraviolet-reactive functional group, R' is a group selected from a monovalent hydrocarbon group excluding an ultraviolet-reactive functional group, a hydroxyl group, and an alkoxy group, a and b are numbers that satisfy the following conditions: 1 ≦ a + b ≦ 3 and 0.01 ≦ a / (a + b) ≦ 0.34, and the molecule has at least 2 R's.) The ultraviolet-curable composition according to any one of Aspects 5 to 7, which is a linear, branched, or cyclic organopolysiloxane represented by the formula. [9] The organosilicon compound of component (A2) is the following formula (3'):

change

change

[10] The organosilicon compound of component (A1) is represented by the following formula (3):

change

change

[11] 11. The ultraviolet-curable composition according to any one of aspects 5 to 10, wherein component (A1) has an average of two ultraviolet-reactive functional groups per molecule.

[12] 12. The ultraviolet-curable composition according to any one of aspects 5 to 11, wherein component (A2) is an organopolysiloxane having one ultraviolet-reactive functional group in the molecule.

[13] 13. The ultraviolet-curable composition according to any one of aspects 1 to 12, wherein the viscosity of the entire composition, as measured at 25° C. using an E-type viscometer, is in the range of 5 to 30 mPa·s.

[14] The ultraviolet-curable composition according to any one of Aspects 5 to 13, wherein component (A) is (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane or a mixture of (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane and at least one compound selected from the following (A1), in a mass ratio of 100 / 0 to 20 / 80 (A2 / A1): (A1): 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy]silane [cyclohexyl)ethyl]-cyclotetrasiloxane, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, 1,5-bis(3-glycidoxypropyl)-1,1,3,3,5,5-hexamethyltrisiloxane, methyl[tris(3-glycidoxypropyl)dimethylsiloxy]silane, tetrakis[(3-glycidoxypropyl)dimethylsiloxy]silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra(3-glycidoxypropyl)-cyclotetrasiloxane.

[15] 15. The ultraviolet-curable composition according to any one of aspects 5 to 14, comprising (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane as component (A) in an amount of 50 to 95% by mass of the total composition.

[16] The ultraviolet-curable composition according to any one of aspects 5 to 15, further comprising (B) a compound having one or more ultraviolet-reactive functional groups in one molecule and having no silicon atoms, wherein the mass ratio of component (B) to the total mass of components (A1), (A2), and (B) is less than 20%.

[17] 17. The ultraviolet-curable composition of embodiment 16, comprising only component (A2) as component (A), or comprising a combination of component (A1) and component (A2) as component (A).

[18] An insulating coating agent comprising the ultraviolet-curable composition according to any one of aspects 1 to 17.

[19] A method of using a cured product of the ultraviolet-curable composition according to any one of aspects 1 to 17 as an insulating coating layer.

[20] A display device comprising a layer made of a cured product of the ultraviolet-curable composition according to any one of aspects 1 to 17.

Claims

1. the composition contains one or more organosilicon compounds (A) having, on average, one or more ultraviolet-reactive functional groups per molecule, the viscosity of the entire composition as measured at 25°C using an E-type viscometer is 80 mPa s or less, the composition does not contain any organic solvent, and the refractive index of the cured product as measured at 25°C and at a wavelength of 589 nm is 1.45 or less; An ultraviolet-curable composition comprising (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane as component (A) in an amount ranging from 50 to 95 mass% of the total composition.

2. The ultraviolet-curable composition according to claim 1 , wherein the ultraviolet-reactive functional group is a cationically polymerizable functional group.

3. 3. The ultraviolet-curable composition according to claim 1, wherein the ultraviolet-reactive functional group is an epoxy group-containing group.

4. The ultraviolet-curable composition according to any one of claims 1 to 3, wherein the proportion of component (A) in the curable composition is 80 mass% or more.

5. The ultraviolet-curable composition according to any one of claims 1 to 4, wherein component (A) further comprises (A1) one or more organosilicon compounds having an average of two or more ultraviolet-reactive functional groups per molecule.

6. Component (A1) has the average composition formula: R ａ R’ ｂ SiO （４－ａ―ｂ）／２ (1) wherein R is a UV-reactive functional group; R' is a group selected from a monovalent hydrocarbon group, a hydroxyl group, and an alkoxy group, excluding ultraviolet-reactive functional groups; a and b are numbers that satisfy the following conditions: 1≦a+b≦3 and 0.01≦a / (a+b)≦0.34, and there are at least two R in the numerator.

6. The ultraviolet-curable composition according to claim 5, wherein the organopolysiloxane is a linear, branched, or cyclic organopolysiloxane represented by the formula:

7. The organosilicon compound of component (A1) is represented by the following formula (3): 【Transformation 3】 (Wherein, all R １ ~R ８ On average, two or more of the R groups per molecule are ultraviolet-reactive functional groups; １ From R ８ each independently represents an unsubstituted or fluorine-substituted monovalent hydrocarbon group; and n is a value that provides a viscosity of the organopolysiloxane represented by formula (3) of 1 to 1,000 mPa s at 25°C, but n may be 0), Average unit formula: (R ３ SiO １／２ ) ｅ (R ２ SiO ２／２ ) ｆ (RSiO ３／２ ) ｇ (SiO ４／２ ) ｈ (4) (In the formula, each R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, at least two of all Rs are ultraviolet-reactive functional groups, (g+h) is a positive number, e is 0 or a positive number, and f is a number in the range of 0 to 10.) An organopolysiloxane represented by the formula: The following formula (5): 【Chemistry 4】 (wherein each R is independently a group selected from an ultraviolet-reactive functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, and x is an integer of 3 to 10, and the molecule contains at least two ultraviolet-reactive functional groups), 7. The ultraviolet-curable composition according to claim 5, wherein the organopolysiloxane is one or more organopolysiloxanes having an ultraviolet-reactive functional group selected from the group consisting of organopolysiloxanes of the formula (I) and a mixture of two or more organopolysiloxanes arbitrarily selected from the formula (I).

8. 8. The ultraviolet-curable composition according to claim 5, wherein the number of ultraviolet-reactive functional groups in component (A1) is two on average per molecule.

9. 9. The ultraviolet-curable composition according to claim 1, wherein the viscosity of the entire composition measured at 25° C. using an E-type viscometer is in the range of 5 to 30 mPa·s.

10. The ultraviolet-curable composition according to any one of claims 5 to 9, wherein component (A) is a mixture of (A2) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane and at least one compound selected from the following (A1): (A1): 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane, 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxy [(3-glycidoxypropyl)dimethylsiloxy]silane, 1,3,5,7-tetramethyl-1,3,5,7-tetra(3-glycidoxypropyl)cyclotetrasiloxane.

11. The ultraviolet-curable composition according to any one of claims 5 to 10, further comprising (B) a compound having one or more ultraviolet-reactive functional groups in one molecule and having no silicon atoms, wherein the mass ratio of component (B) to the total mass of components (A1), (A2), and (B) is less than 20%.

12. The ultraviolet-curable composition according to claim 11, comprising only the component (A2) as the component (A), or comprising a combination of the component (A1) and the component (A2) as the component (A).

13. An insulating coating agent comprising the ultraviolet-curable composition according to any one of claims 1 to 12.

14. A method for using a cured product of the ultraviolet-curable composition according to any one of claims 1 to 12 as an insulating coating layer.

15. A display device comprising a layer made of a cured product of the ultraviolet curable composition according to any one of claims 1 to 12.

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