UV-curable compositions and their uses

Abstract

[Problem] To provide a silicon-atom-containing ultraviolet-curable composition which gives cured objects having excellent flexibility and which has excellent applicability to substrates. [Solution] This ultraviolet-curable composition is characterized by comprising (A) one or more organopolysiloxanes each having three or more silicon atoms and having, in the molecule, two or more ultraviolet-curable functional groups on average and (B) one or more organosilicon compounds each having one ultraviolet-curable functional group in the molecule, and by containing substantially no organic solvent and having, as a whole, a viscosity, as measured at 25°C with an E-type viscometer, of 80 mPa·s or less.

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet-curable composition that can be cured by chemical rays, such as ultraviolet light or electron beams, and more particularly to an ultraviolet-curable composition comprising an organosilicon compound, preferably organosilane and / or organopolysiloxane, and more specifically to an ultraviolet-curable composition from which the resulting cured product has good mechanical properties, particularly high elongation properties, and excellent coatability. The curable composition of the present invention has excellent flexibility and is suitable as an insulating material for electronic and electrical devices, and is particularly suitable as a material for use as a coating layer and protective layer. Furthermore, it has excellent coatability and excellent wettability to substrates, and is 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 coatings, potting agents, and insulating materials for electronic and electrical devices. Among silicone resins, UV-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 electrical interference 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 element and the touchscreen.

[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, research has begun to improve the reliability of the display device, especially the flexible display device as a whole, by stacking a highly flexible insulating layer on the touchscreen layer. In addition, inkjet printing has been adopted as a processing method for organic layers to improve productivity. Therefore, there is a need for materials that can be processed by inkjet printing for the insulating layer mentioned above.

[0005] In the International Patent Application Publication Gazette WO2019 / 117298, a curable composition is disclosed which consists of a disiloxane compound having an ultraviolet curable functional group, a polysiloxane having an ultraviolet curable functional group, and an optionally blended silicon-free compound having an ultraviolet curable functional group, and can be applied by an inkjet method. However, since the ratio of the disiloxane compound having two or more ultraviolet curable functional groups in the composition is high, the hardness of the cured product is high, and it may not be applicable to uses where flexibility is required.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, ultraviolet curable organopolysiloxane compositions are well known, but there is still a need for an ultraviolet curable composition that has excellent flexibility in its cured product and excellent workability for application to a substrate, particularly a low viscosity. The present invention aims to provide a curable composition containing silicon atoms, particularly an ultraviolet curable composition, which has a cured product with high flexibility, particularly high elongation characteristics, and also has excellent workability when applied to a substrate.

Means for Solving the Problems

[0008] The present invention has been completed by discovering that an ultraviolet curable composition obtained by using in combination (A) one or more organopolysiloxanes having 3 or more silicon atoms and having an average of 2 or more ultraviolet curable functional groups in one molecule, and (B) one or more organosilicon compounds having 1 ultraviolet curable functional group in one molecule has a low viscosity, excellent workability when applied to a substrate, and its cured product exhibits excellent flexibility.

[0009] The present invention relates to an ultraviolet curable composition containing an organosilicon compound, particularly an ultraviolet curable organopolysiloxane composition. This composition cures by forming bonds with ultraviolet curable functional groups, but the curing method is not limited to ultraviolet irradiation, and any method capable of causing the ultraviolet curable functional groups to undergo a curing reaction can be used. For example, the composition of the present invention may be cured using electron beam irradiation.

[0010] The ultraviolet curable composition of the present invention contains (A) one or more organopolysiloxanes having 3 or more silicon atoms and an average of 2 or more ultraviolet curable functional groups per molecule, and (B) one or more organosilicon compounds having 1 ultraviolet curable functional group per molecule. The viscosity of the entire 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. The cured product when the composition is cured has good flexibility. Unless otherwise specified in this specification, the viscosity of a substance is the value measured using an E-type viscometer at 25 °C.

[0011] The ultraviolet curable functional group possessed by component (A) of the present invention is preferably a cationic polymerization reactive group. Furthermore, the cationic polymerization reactive group is preferably an epoxy group-containing group.

[0012] The average number of silicon atoms of the above component (A) is preferably 10 or less.

[0013] The above component (B) has an average compositional formula: R c R’ d SiO (4-c―d) / 2 (2) (In the formula, R is an ultraviolet curable functional group, R’ is a group selected from a monovalent hydrocarbon group excluding an ultraviolet curable 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

[0014] The above component (A) has an average composition formula: R a R’ b SiO (4-a―b) / 2 (1) (In the formula, R is an ultraviolet curable functional group, R’ is a group selected from monovalent hydrocarbon groups excluding ultraviolet curable functional groups, hydroxyl groups, and alkoxy groups, a and b are numbers satisfying the following conditions: 1 ≤ a + b ≤ 3 and 0.01 ≤ a / (a + b) ≤ 0.5, and having at least 2 R's in the molecule.) It is preferably a linear, branched or cyclic organopolysiloxane represented by

[0015] The organosilicon compound of component (B) is represented by the following formula (3'):

Chemical formula

Chemical formula

[0016] The above component (B) is preferably an organopolysiloxane having 3 or more silicon atoms and one UV-curable functional group in the molecule.

[0017] Furthermore, the above component (A) is given by the following formula (3): [ka] (3) (In the formula, all R 1 ~R 8 On average, two or more of the groups per molecule are UV-curable functional groups; other R 1 From R 8 Each of these is an organopolysiloxane represented by an unsubstituted or fluorine-substituted monovalent hydrocarbon group; n is a number between 1 and 20. Average unit formula: (R3SiO 1 / 2 ) e (R2SiO 2 / 2 ) f (RSiO 3 / 2 ) g (SiO 4 / 2 ) h (5) (wherein R is independently selected from UV-curable functional groups and unsubstituted or fluorine-substituted monovalent hydrocarbon groups, at least two of all R are UV-curable 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.) Organopolysiloxane represented by this formula, Formula (4): [ka] (4) A cyclic organopolysiloxane represented by the formula (wherein R is independently selected from an ultraviolet-curable functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, x is an integer from 3 to 10, and the molecule has at least two ultraviolet-curable functional groups), Preferably, it is one or more organopolysiloxanes having UV-curable functional groups, selected from the group consisting of two or more organopolysiloxanes arbitrarily selected from thereto.

[0018] The number of UV-curable functional groups in component (A) is preferably two on average per molecule.

[0019] The above component (A) is preferably a linear organopolysiloxane having UV-curable functional groups at both ends and having an average silicon atom count of 5 to 12.

[0020] It is preferable that the curable composition contains component (B) and component (A) in a mass ratio of 25 / 75 to 90 / 10 (A / B), or that the content of component (A) exceeds 20% by mass of the total amount of the curable composition.

[0021] In one preferred embodiment of the UV-curable composition of the present invention, the composition further comprises one or more organopolysiloxanes having two silicon atoms and two UV-curable functional groups in one molecule, such that the mass ratio of component (A') to the total of component (A), component (B), and component (A') is less than 30%.

[0022] In one preferred embodiment of the present invention, component (B) is 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane.

[0023] In one preferred embodiment of the present invention, component (A) is 1,1,3,3,5,5,7,7,9,9-decamethyl-1,9-bis[2-(3,4-epoxycyclohexyl)ethyl]pentasiloxane.

[0024] The viscosity of the UV-curable composition of the present invention, as measured at 25°C using an E-type viscometer, is particularly preferably in the range of 5 to 30 mPa·s.

[0025] The present invention further provides an insulating coating agent containing the above-described UV-curable composition. The UV-curable composition of the present invention is useful as an insulating coating agent.

[0026] The present invention further provides a cured product of the above-mentioned ultraviolet-curable composition. It also provides a method for using the cured product as an insulating coating layer.

[0027] The present invention further provides a display device comprising a layer made of a cured product of the above-mentioned ultraviolet-curable composition, such as a liquid crystal display, an organic EL display, or an organic EL flexible display. [Modes for carrying out the invention]

[0028] The configuration of the present invention will be described in more detail below. The UV-curable composition of the present invention contains, as essential curing components, (A) one or more organopolysiloxanes having 3 or more silicon atoms and an average of 2 or more UV-curable functional groups per molecule, and (B) one or more organosilicon compounds having 1 UV-curable functional group per molecule. Optionally, it may also contain photocationic polymerization initiators and components selected from various additives. However, the curable composition of the present invention is characterized by being substantially free of organic solvents.

[0029] In this specification, the term "organosilicon compounds" is used to mean a concept that includes organosilanes, organosiloxane oligomers, and organopolysiloxanes.

[0030] In this specification, the term "polysiloxane" refers to a material in which the degree of polymerization of siloxane units (Si-O) is 2 or higher, that is, having an average of 2 or more Si-O bonds per molecule. Polysiloxanes include siloxane oligomers such as disiloxanes, trisiloxanes, and tetrasiloxanes, as well as siloxane polymers with a higher degree of polymerization.

[0031] [Ingredients (A)] Component (A) is one or more organopolysiloxanes having three or more silicon atoms and an average of two or more UV-curable functional groups per molecule. Its molecular structure can be any as long as this objective is achieved. The UV-curable functional groups of component (A) are preferably cationic polymerizable functional groups, and more preferably epoxy group-containing groups.

[0032] Component (A) preferably has a viscosity of 1 to 1000 mPa·s at 25°C, more preferably 1 to 500 mPa·s, particularly preferably 1 to 100 mPa·s, and most preferably 1 to 50 mPa·s.

[0033] Furthermore, component (A) contains 3 to 20 silicon atoms per molecule, preferably in the range of 3 to 12.

[0034] The organopolysiloxane component (A) has the following average chemical formula: R a R' b SiO (4-a―b) / 2 (1) The organopolysiloxane represented by is linear, branched, or cyclic, preferably linear or branched, and particularly preferably linear.

[0035] In formula (1), R is an ultraviolet-curable functional group, R' is a group selected from monovalent hydrocarbon groups, hydroxyl groups, and alkoxy groups, excluding UV-curable functional groups. a and b are numbers that satisfy the following conditions: 1 ≤ a + b ≤ 3 and 0.01 ≤ a / (a + b) ≤ 0.5, preferably 2 ≤ a + b ≤ 3 and 0.05 ≤ a / (a + b) ≤ 0.34.

[0036] The UV-curable functional group represented by R in formula (1) is an organic group that can form bonds with each other upon irradiation with ultraviolet light, with or without the presence of a photoinitiator. Examples of UV-curable functional groups include radical polymerizable groups and cationic polymerizable groups. Radical polymerizable groups are not particularly limited as long as they are functional groups that can form new bonds, especially bonds between radical polymerizable groups, through a radical reaction mechanism, but examples include acrylic groups, methacrylic groups, maleimide groups, and organic groups containing any of these groups. Specific examples of radical polymerizable groups include acrylicoxypropyl, methacrylicoxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl. Cationic polymerizable groups include vinyl ether groups, epoxy group-containing groups, oxetane group-containing groups, etc., such as CH2=CH-O-(CH2)n-(n is an integer from 3 to 20), glycidyloxy-(CH2) n -(n is an integer between 3 and 20), 3,4-epoxycyclohexyl-(CH2) n Examples of bases include -(where n is an integer between 2 and 20). The UV-curable 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 composition formula has, on average, at least two UV-curable functional groups (R) per molecule. The number of UV-curable groups is preferably 2 to 6, more preferably 2 to 4, particularly preferably 2 to 3, and most preferably 2 per molecule.

[0037] R' is a monovalent hydrocarbon group, which includes unsubstituted monovalent hydrocarbon groups and fluorine-substituted monovalent hydrocarbon groups. 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 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl groups, with methyl groups being particularly preferred. Examples of cycloalkyl groups include cyclopentyl and cyclohexyl. Examples of arylalkyl groups include benzyl and phenylethyl groups. Examples of aryl groups include phenyl and naphthyl groups. Examples of fluorine-substituted monovalent hydrocarbon groups include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. 3,3,3-trifluoropropyl is preferred as the fluorine-substituted monovalent hydrocarbon group.

[0038] The organopolysiloxane represented by formula (1) above has a viscosity at 25°C of 1 to 1000 mPa·s, 1 to 500 mPa·s, or 1 to 100 mPa·s, 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.

[0039] The organopolysiloxane represented by formula (1) preferably has an average of 3 to 20 silicon atoms per molecule, more preferably 3 to 12, and particularly preferably 5 to 12 silicon atoms.

[0040] In one preferred embodiment, the organopolysiloxane of component (A) is The following formula (3): [ka] (3) It is a compound represented by [formula].

[0041] Similar to the compound represented by formula (1) above, the organopolysiloxane represented by formula (3) has an average of two or more UV-curable functional groups per molecule. In formula (3), all R 1 ~R 8 Of the groups, on average, two or more per molecule are UV-curable functional groups. UV-curable functional groups are organic groups that can form bonds with each other upon irradiation with ultraviolet light, with or without the presence of a photoinitiator. Examples of UV-curable functional groups include radical polymerizable groups and cationic polymerizable groups. Radical polymerizable groups are not particularly limited as long as they are functional groups that can form new bonds, especially bonds between radical polymerizable groups, through a radical reaction mechanism, but examples include acrylic groups, methacrylic groups, maleimide groups, and organic groups containing any of these groups. Specific examples of radical polymerizable groups include acrylicoxypropyl, methacrylicoxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl. Cationic polymerizable groups include vinyl ether groups, epoxy group-containing groups, oxetane group-containing groups, etc., such as CH2=CH-O-(CH2)n-(n is an integer from 3 to 20), glycidyloxy-(CH2) n -(n is an integer between 3 and 20), 3,4-epoxycyclohexyl-(CH2) n Examples of bases include -(where n is an integer between 2 and 20).

[0042] The UV-curable functional group is preferably a group containing one or more epoxy groups. Particularly preferred groups include glycidyloxyalkyl groups, especially 3-glycidyloxypropyl groups, and epoxycyclohexylalkyl groups, especially 3,4-epoxycyclohexylethyl groups.

[0043] In formula (3), R other than the UV-curable functional group 1 From R 8Each of these is 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 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl groups, with methyl being particularly preferred. Examples of cycloalkyl groups include cyclopentyl and cyclohexyl. Examples of arylalkyl groups include benzyl and phenylethyl groups. Examples of aryl groups include phenyl and naphthyl groups. Examples of fluorine-substituted monovalent hydrocarbon groups include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. 3,3,3-trifluoropropyl is preferred as the fluorine-substituted monovalent hydrocarbon group.

[0044] The number of UV-curable functional groups in the organopolysiloxane of formula (3), which is component (A), is on average 2 to 6 per molecule overall, preferably 2 to 5, more preferably 2 to 4, particularly preferably 2 to 3, and most preferably 2.

[0045] In particular, it is preferable that one of R1 to R3 and one of R6 to R8 in formula (3) are UV-curable functional groups. Furthermore, it is especially preferable that only one of R1 to R3 and one of R6 to R8 in formula (3) are UV-curable functional groups.

[0046] In formula (3), n is the value such that the viscosity of the organopolysiloxane represented by formula (3) 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. Those skilled in the art can easily determine the value of n without excessive trial and error so that the viscosity of the organopolysiloxane of formula (3) falls within the aforementioned viscosity range. However, generally, it is preferable that the number of silicon atoms per molecule of the compound of formula (3) is 3 to 12, particularly 3 to 5, so that the compound of formula (3) has the desired viscosity.

[0047] 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, it is preferable that the viscosity of the mixture at 25°C is the viscosity described above.

[0048] Furthermore, the compound of formula (1) above may 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), R is a group independently selected from UV-curable functional groups and unsubstituted or fluorine-substituted monovalent hydrocarbon groups, at least two of all R are UV-curable 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. The UV-curable functional group and monovalent hydrocarbon group are as defined above for formula (1). Furthermore, the preferred viscosity of the organopolysiloxane represented by formula (4) is as specified above for the organopolysiloxane represented by formula (1).

[0049] The number of UV-curable functional groups in 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.

[0050] The organopolysiloxane represented by formula (4) preferably has 3 to 20 silicon atoms, more preferably 3 to 12 silicon atoms, and particularly preferably 5 to 12 silicon atoms per molecule.

[0051] Specific examples of organopolysiloxanes represented by (1) above, particularly formula (3) or formula (4), include 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, 1,7-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5,7,7-octamethyltetrasiloxane, and 1,9-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1 ,3,3,5,5,7,7,9,9-decamethylpentasiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, 1,5-bis(3-glycidoxypropyl)-1,1,3,3,5,5-hexamethyltrisiloxane, 1,7-bis(3-glycidoxypropyl)-1,1,3,3,5,5, Examples include 7,7-octamethyltetrasiloxane, 1,9-bis(3-glycidoxypropyl)-1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxane, (3,4-epoxycyclohexylethyldimethylsilyl)-polydimethylsiloxane, (3-glycidoxypropyldimethylsilyl)-polydimethylsiloxane, trimethylsilyl-dimethylsiloxy / (methyl-3,4-epoxycyclohexylethylsiloxy) copolymer, trimethylsilyl-dimethylsiloxy / (methyl-3-glycidoxypropylsiloxy) copolymer, (3,4-epoxycyclohexylethyldimethylsilyl)-dimethylsiloxy / (methyl-3,4-epoxycyclohexylethylsiloxy) copolymer, and (3-glycidoxypropyldimethylsilyl)-dimethylsiloxy / (methyl-3-glycidoxypropylsiloxy) copolymer.

[0052] Furthermore, the compound of formula (1) above is the following formula (5): [ka] (5) The cyclic organopolysiloxane may be represented by the formula (wherein R is independently selected from an ultraviolet-curable functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, and x is an integer from 3 to 10, having at least two ultraviolet-curable functional groups in the molecule).

[0053] The ultraviolet-curable functional groups and unsubstituted or fluorine-substituted monovalent hydrocarbon groups that R in formula (5) can represent are as defined for formula (1) above.

[0054] Furthermore, the preferred viscosity of the organopolysiloxane represented by formula (5) is the same as specified above for the organopolysiloxane represented by formula (1).

[0055] Specific examples of cyclic organopolysiloxanes 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, and 1,3,5,7-tetramethyl-1,3,5,7-tetra[2-(3,4-epoxycyclohexyl)ethyl]cyclotetramethyl Examples include lasiloxane, 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.

[0056] The organopolysiloxanes represented by formulas (1), (3) to (5) described above can be used individually or in any combination of two or more as component (A). As component (A), it is preferable to use one or more organopolysiloxanes selected from the group consisting of organopolysiloxanes represented by formula (3), cyclic organopolysiloxanes represented by formula (5), and combinations thereof.

[0057] Component (A) is particularly preferably a linear organopolysiloxane having UV-curable functional groups only at both ends of the molecular chain and having an average of 5 to 12 silicon atoms, and a linear dimethylpolysiloxane having epoxy group-containing groups at both ends of the molecular chain is particularly preferred.

[0058] The compound recommended as component (A) is one or more compounds selected from the group consisting of 1,5-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5-hexamethyltrisiloxane, 1,9-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxane, methyl(tris[2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, tetrakis([2-(3,4-epoxycyclohexyl)ethyl]dimethylsiloxy)silane, and (3,4-epoxycyclohexylethyldimethylsilyl)-polydimethylsiloxane (both terminals). Among these, 1,1,3,3,5,5,7,7,9,9-decamethyl-1,9-bis[2-(3,4-epoxycyclohexyl)ethyl]pentasiloxane is particularly preferred for use.

[0059] [Component (B)] Component (B) is an organosilicon compound having one UV-curable functional group per molecule on an organosilane or organopolysiloxane skeleton. Its main effect is to control the crosslinking density of the cured product obtained from the composition of the present invention, adjust the physical properties of the cured product, and simultaneously reduce the viscosity of the composition. Unlike component (A), component (B) has only one UV-curable functional group in its molecule. If it has two or more functional groups in its molecule, component (B) itself becomes a crosslinking component, and the purpose of using this component may not be achieved.

[0060] On the other hand, the molecular structure of component (B) is arbitrary as long as the above objective is achieved. As an example, the organosilicon compound of component (B) is The average composition formula below; Rc R' d SiO (4-c―d) / 2 (2) (In the formula, R is an ultraviolet-curable functional group, R' is a group selected from monovalent hydrocarbon groups, hydroxyl groups, and alkoxy groups, excluding UV-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. Also, the number of R in the numerator is 1. These are organosilanes represented by , or linear, branched, or cyclic organopolysiloxanes. One of these organosilanes and organopolysiloxanes can be selected from this group, or any combination of two or more can be used.

[0061] The UV-curable functional group represented by R in formula (2) is an organic group that can form bonds with each other upon irradiation with ultraviolet light, with or without the presence of a photoinitiator. Examples of UV-curable functional groups include radical polymerizable groups and cationic polymerizable groups. Radical polymerizable groups are not particularly limited as long as they are functional groups that can form new bonds, especially bonds between radical polymerizable groups, through a radical reaction mechanism, but examples include acrylic groups, methacrylic groups, maleimide groups, and organic groups containing any of these groups. Specific examples of radical polymerizable groups include acrylicoxypropyl, methacrylicoxypropyl, acrylamidopropyl, methacrylamidopropyl, and 3-(N-maleimido)propyl. Cationic polymerizable groups include vinyl ether groups, epoxy group-containing groups, oxetane group-containing groups, etc., such as CH2=CH-O-(CH2)n-(n is an integer from 3 to 20), glycidyloxy-(CH2) n -(n is an integer between 3 and 20), 3,4-epoxycyclohexyl-(CH2) n Examples of bases include -(where n is an integer between 2 and 20).

[0062] The UV-curable functional group is preferably a group containing one or more epoxy groups. Particularly preferred groups include glycidyloxyalkyl groups, especially glycidyloxypropyl groups, epoxycyclohexylalkyl groups, and especially 3,4-epoxycyclohexylethyl groups. The organosilicon compound represented by the above average composition formula has one UV-curable functional group (R) per molecule.

[0063] The monovalent hydrocarbon group represented by R' in formula (2) is independently selected from the group consisting of unsubstituted monovalent hydrocarbon groups and fluorine-substituted monovalent hydrocarbon groups. The unsubstituted or fluorine-substituted monovalent hydrocarbon group is preferably selected from unsubstituted or fluorine-substituted alkyl, cycloalkyl, arylalkyl, and aryl groups having 1 to 20 carbon atoms. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl groups, with methyl being particularly preferred. Examples of cycloalkyl groups include cyclopentyl and cyclohexyl. Examples of arylalkyl groups include benzyl and phenylethyl groups. Examples of aryl groups include phenyl and naphthyl groups. Examples of fluorine-substituted monovalent hydrocarbon groups include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. A preferred monovalent hydrocarbon group substituted with fluorine is the 3,3,3-trifluoropropyl group.

[0064] The organosilicon compound represented by formula (2) above preferably has a viscosity of 1 to 50 mPa·s at 25°C, more preferably 1 to 20 mPa·s, and particularly preferably 2 to 10 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.

[0065] The organosilicon compound represented by formula (2) above is preferably a compound having 1 to 10 silicon atoms, more preferably 1 to 4 silicon atoms, per molecule.

[0066] In one preferred embodiment, the organosilicon compound of component (B) is The following equation (3'): [ka] (3') This is an organopolysiloxane compound represented by [formula].

[0067] Similar to the compound represented by formula (2) above, the organopolysiloxane represented by formula (3') is all R 1 ~R 8 Only one of the groups is an ultraviolet-curable functional group.

[0068] Similar to the compound represented by formula (2) above, UV-curable functional groups are organic groups that can form bonds with each other upon irradiation with ultraviolet light, in or out of the presence of a photoinitiator. Examples of UV-curable functional groups include radical polymerizable groups and cationic polymerizable groups. Radical polymerizable groups are not particularly limited as long as they are functional groups that can form new bonds, especially bonds between radical polymerizable groups, through a radical reaction mechanism, but examples include acrylic groups, methacrylic groups, maleimide groups, and organic groups containing any of these groups. Specific examples of radical polymerizable groups include acrylicoxypropyl, methacrylicoxypropyl, acrylamidopropyl, methacrylmidopropyl, and 3-(N-maleimido)propyl. Cationic polymerizable groups include vinyl ether groups, epoxy group-containing groups, oxetane group-containing groups, etc., such as CH2=CH-O-(CH2)n-(n is an integer from 3 to 20), glycidyloxy-(CH2) n -(n is an integer between 3 and 20), 3,4-epoxycyclohexyl-(CH2) n Examples of bases include -(where n is an integer between 2 and 20).

[0069] The UV-curable functional group is preferably a group containing one or more epoxy groups. Particularly preferred groups include glycidyloxyalkyl groups, such as glycidyloxypropyl groups and epoxycyclohexylalkyl groups, especially 3,4-epoxycyclohexylethyl groups.

[0070] In formula (3'), R other than the UV-curable functional group 1 From R 8 Each of these is 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 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl groups, with methyl being particularly preferred. Examples of cycloalkyl groups include cyclopentyl and cyclohexyl. Examples of arylalkyl groups include benzyl and phenylethyl groups. Examples of aryl groups include phenyl and naphthyl groups. Examples of fluorine-substituted monovalent hydrocarbon groups include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. 3,3,3-trifluoropropyl is preferred as the fluorine-substituted monovalent hydrocarbon group.

[0071] There are no restrictions on the position of the UV-curable functional group in the organopolysiloxane represented by formula (3'). Only one of the molecular terminal groups, i.e., one of R1 to R3 or one of R6 to R8, may be a UV-curable functional group. Alternatively, only one of the non-terminal groups R4 to R5 in formula (3') may be a UV-curable functional group.

[0072] In formula (3'), n is preferably a value such that the viscosity of the organopolysiloxane represented by formula (3') at 25°C is 1 to 50 mPa·s, more preferably 1 to 20 mPa·s, and particularly preferably 2 to 10 mPa·s. A person skilled in the art can easily determine the value of n without excessive trial and error so that the viscosity of the organopolysiloxane of formula (3') falls within the aforementioned viscosity range. Generally, the number of silicon atoms per molecule is preferably 2 to 10, and more preferably 2 to 4, so that the compound of formula (3') has the desired viscosity.

[0073] 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 50 mPa·s, preferably 1 to 20 mPa·s, and more preferably 2 to 10 mPa·s.

[0074] Specific examples of organopolysiloxanes having one UV-curable functional group in the molecule, 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-epoxycyclo Examples include hexyl)ethyl]-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.

[0075] Furthermore, the organosilicon compound of formula (2) above may be a cyclic organopolysiloxane represented by the following formula (4'). formula: [ka] (4') In formula (4'), R is a group independently selected from UV-curable functional groups and unsubstituted or fluorine-substituted monovalent hydrocarbon groups, and x is an integer between 3 and 5, with only one UV-curable functional group in the molecule.

[0076] The UV-curable functional group and monovalent hydrocarbon group are as defined for formula (2) above.

[0077] The preferred viscosity of the cyclic organopolysiloxane represented by formula (4') is the same as specified above for the organopolysiloxane represented by formula (2). Therefore, the viscosity at 25°C is preferably 1 to 50 mPa·s, more preferably 1 to 10 mPa·s, and particularly preferably 2 to 10 mPa·s.

[0078] Specific examples of cyclic organopolysiloxanes 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.

[0079] Furthermore, component (B) may be an organosilane represented by the following formula (5'). Formula: RSiR'3(5') In formula (5'), R is an ultraviolet-curable functional group, and R' is a group selected from monovalent hydrocarbon groups, hydroxyl groups, and alkoxy groups, excluding ultraviolet-curable functional groups. The UV-curable functional group and monovalent hydrocarbon group are as defined for formula (2) above, and the alkoxy group is an alkoxy group having 1 to 20 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, or a cycloalkyl group having 5 to 20 carbon atoms. Specifically, a methoxy group, ethoxy group, isopropoxy group, cyclopentyl group, or cyclohexyl group is preferred.

[0080] Furthermore, the preferred viscosity of the organosilane represented by formula (5') is the same as the viscosity previously specified for the organopolysiloxane represented by formula (2). Therefore, the viscosity at 25°C is preferably 1 to 50 mPa·s, more preferably 1 to 20 mPa·s, and particularly preferably 2 to 10 mPa·s.

[0081] 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.

[0082] The organosilicon compounds represented by formulas (2), (3'), (4'), or (5') described above can be used individually or in any combination of two or more. That is, organosilicon compounds represented by formulas (2), (3'), (4'), or (5'), and mixtures of two or more arbitrarily selected therefrom, can be used as component (B) of the composition of the present invention.

[0083] Preferably, as component (B), an organosilicon compound selected from an organopolysiloxane represented by formula (3'), a cyclic organopolysiloxane represented by formula (4'), and combinations thereof can be used. In particular, component (B) is an organopolysiloxane having an average of 3 or more silicon atoms and one UV-curable functional group in the molecule, and it is especially preferable that the number of silicon atoms is 3 or 4.

[0084] It is particularly preferable to use 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane as component (B).

[0085] [Amount of ingredients (A) and (B) to be used] Component (A) and component (B) can be used in any mass ratio, but the proportion of component (A) is 25% by mass or more and 90% by mass or less, preferably 30% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 70% by mass or less, relative to 100% by mass of the total amount of component (A) and component (B). In other words, the proportion of component (B) is 10% by mass or more and 75% by mass or less, preferably 20% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 60% by mass or less. Within this range, the viscosity of the curable composition can be appropriately adjusted, and the resulting cured product can be designed to have good mechanical properties, particularly high tensile elongation.

[0086] On the other hand, from the standpoint of suitably achieving the objectives of the present invention, it is preferable that the content of component (A) exceeds 20% by mass with respect to the total amount of the curable composition.

[0087] [Component (A')] In addition to components (A) and (B) above, the curable composition of the present invention may further contain one or more organopolysiloxanes (component A') having two silicon atoms and two UV-curable functional groups in one molecule. In particular, when an organopolysiloxane with more than five silicon atoms is used as component (A), using component (A') may allow for the design of materials with high mechanical properties, especially high tensile elongation, of the cured product.

[0088] The UV-curable functional group of component (A') can be the same as those listed in relation to components (A) and (B). Therefore, an organopolysiloxane having two epoxy groups in its molecule, specifically a disiloxane having two epoxy groups in its molecule and two silicon atoms, can be used.

[0089] Specific examples of component (A') include 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane and 1,1-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,3,3,3-tetramethyldisiloxane, but 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]-1,1,3,3-tetramethyldisiloxane is preferred.

[0090] The viscosity of component (A') is preferably 1 to 100 mPa·s, more preferably 10 to 50 mPa·s, at 25°C.

[0091] Component (A') may be used to improve the mechanical properties of the cured product, particularly its tensile elongation, and its amount can be adjusted to adjust the viscosity of the curable composition, improve its applicability, and adjust the physical properties of the cured product. Specifically, the amount of component (A') in the curable composition of the present invention is preferably such that the mass ratio of component (A') to the total of components (A), (B), and (A') is less than 30% in order to suppress a decrease in the flexibility of the cured product. It is more preferable that the mass ratio of component (A') to the total of components (A), (B), and (A') is less than 25%, and even more preferable that it is less than 20%.

[0092] [Overall viscosity of the composition] The curable composition of the present invention can be used as a coating agent, and in order for the composition to have suitable fluidity and workability for application to a substrate, the viscosity of the entire composition is 80 mPa·s or less at 25°C, as measured using an E-type viscometer. The preferred viscosity range is 1 to 60 mPa·s, more preferably 5 to 30 mPa·s, and particularly preferably 5 to 20 mPa·s. In order to adjust the viscosity of the entire curable composition to a desired viscosity, compounds having the preferred viscosity can be used as components so that the viscosity of the entire composition has the desired viscosity.

[0093] [No organic solvents used] The UV-curable composition of the present invention, by using the above-mentioned components, can achieve a viscosity suitable for the above-mentioned coating agent without substantially using organic solvents, and is substantially free of organic solvents. In this specification, "substantially free of organic solvents" means that the content of organic solvents is less than 0.05% by mass of the total composition, and preferably below the analytical limit using an analytical method such as gas chromatography. In the present invention, the desired viscosity can be achieved without using organic solvents by adjusting the molecular structure and molecular weight of component (A) and component (B).

[0094] [Photopolymerization initiator] In addition to components (A) and (B) above, a photopolymerization initiator may be optionally added to the UV-curable composition of the present invention. In this case, if the UV-curable functional groups of components (A) and (B) are cationic polymerizable functional groups including epoxy or vinyl ether, a photocationic polymerization initiator is used as the photopolymerization initiator. As photocationic polymerization initiators, compounds that can generate Brønsted acid or Lewis acid by irradiation with ultraviolet light or electron beams, so-called photoacid generators, are known, and it is known that acid is generated by irradiation with ultraviolet light, etc., and that this acid causes a reaction between cationic polymerizable functional groups. Furthermore, if the UV-curable functional group is a radical polymerizable functional group, a photoradical polymerization initiator can be used as the photopolymerization initiator. Photoradical polymerization initiators generate free radicals by irradiation with ultraviolet light or electron beams, which cause a radical polymerization reaction and can cure the composition of the present invention. When curing the composition of the present invention by electron beam irradiation, a polymerization initiator is usually not required.

[0095] (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 any 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-Triadine, 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-Dicarboxymide Examples of photocatalytic polymerization initiators 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 such as Omnicat 250, Omnicat 270 (both from IGM Resins BV), CPI-310B, IK-1 (both from Sunapro Co., Ltd.), DTS-200 (Midori Chemical Co., Ltd.), and Irgacure 290 (BASF) can also be used.

[0096] The amount of photocationic polymerization initiator added to the curable composition of the present invention is not particularly limited as long as the desired photocuring reaction occurs. However, it is generally preferable to use the photocationic polymerization initiator in an amount of 0.1 to 10% by mass, preferably 0.2 to 5% by mass, and particularly 0.5 to 4% by mass, relative to the total amount of components (A) and (B) of the present invention.

[0097] If the UV-curable functional groups of components (A) and (B) are photocationic polymerization initiators such as epoxy groups, then in addition to the photocationic polymerization initiators mentioned above, the photoradical polymerization initiators described below may also be used in combination as polymerization initiators. Using both initiators in combination may improve the curability of the UV-curable organopolysiloxane composition.

[0098] (2) Photoradical polymerization initiator Photoradical polymerization initiators are broadly classified into photocleavage type and hydrogen abstraction type, but 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 any specific one. Examples of photoradical polymerization initiators include acetophenone, p-anisyl, benzyl, benzoin, benzophenone, 2-benzoylbenzoic acid, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, benzoin methyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ethyl ether, 4-benzoylbenzoic acid, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, methyl 2-benzoylbenzoate, 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-benzyl-2-(dimethylamino)- 4'-Morphorinobutyrophenone, (±)-Camphorquinone, 2-Chlorothioxanthone, 4,4'-Dichlorobenzophenone, 2,2-Diethoxyacetophenone, 2,2-Dimethoxy-2-phenylacetophenone, 2,4-Diethylthioxanthene-9-one, Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, Ethyl(2,4,6-trimethylbenzoyl)phenylphosphine, 1,4-Dibenzoylbenzene, 2-Ethylanthraquinone, 1-Hydroxycyclohexylphenyl ketone, 2-Hydroxy-2-methylpropiophenone, 2-Hydroxy-4'-(2-Hydroxyethoxy)-2-methylpropiophenone, 2-Isopropylthioxanthone, Lithium Examples include, but are not limited to, phenyl(2,4,6-trimethylbenzoyl)phosphine, 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 initiators that can be used as photoradical polymerization initiators include Omnirad (registered trademark) 651, 184, 1173, 2959, 127, 907, 369, 369E, and 379EG (alkylphenone-based photopolymerization initiators, IGM Resins BV), Omnirad (registered trademark) TPO H, TPO-L, and 819 (acylphosphine oxide-based photopolymerization initiators, IGM Resins BV), Omnirad (registered trademark) MBF and 754 (intramolecular hydrogen abstraction type photopolymerization initiators, IGM Resins BV), and Irgacure (registered trademark) OXE01 and OXE02 (oxime ester-based non-polymerization initiators, BASF).

[0099] The amount of photoradical polymerization initiator added to the composition of the present invention is not particularly limited as long as the desired photopolymerization or photocuring reaction occurs, but generally it is used in an amount of 0.01 to 5% by mass, preferably 0.05 to 1% by mass, relative to the total mass of the composition of the present invention.

[0100] Furthermore, a photosensitizer can be used in combination with the above-mentioned photocationic polymerization initiator or photoradical polymerization initiator. The use of a sensitizer can increase the photon-quantum efficiency of the polymerization reaction, and compared to the case where only a photoinitiator is used, it is possible to utilize longer wavelength light in the polymerization reaction. 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 compounds, phenothiazine compounds, perylene compounds, cyanine compounds, merocyanine compounds, coumarin compounds, benzylidene ketone compounds, (thio)xanthene or (thio)xanthone compounds, such as isopropylthioxanthone, 2,4-diethylthioxanthone, alkyl-substituted anthracenes, squarium compounds, (thia)pyrillium compounds, and porphyrin compounds. However, any photosensitizer is not limited to these and can be used in the curable composition of the present invention.

[0101] The cured product obtained from the curable composition of the present invention can be designed to have desired physical properties and curing speed, and the viscosity of the curable composition can be designed to have desired values, depending on the molecular chain lengths of component (A) and component (B), the positions of UV-curable functional groups within the molecule, the molecular structure, and the number of UV-curable functional groups per molecule of component (A). Furthermore, the cured product obtained by curing the curable composition of the present invention is also included in the scope of the present invention. Moreover, the shape of the cured product obtained from the composition of the present invention is not particularly limited, and may be a thin film coating layer, a molded product such as a sheet, or it may be injected into a specific area in an uncured state and cured to form a filler, or it may be used as a sealing material or intermediate layer for laminates or display devices, etc. The cured product obtained from the composition of the present invention is particularly preferably in the form of a thin film coating layer, and is particularly preferably an insulating coating layer.

[0102] The curable composition of the present invention is suitable for use as a coating agent or potting agent, particularly as an insulating coating agent or potting agent for electronic and electrical devices.

[0103] The cured product obtained by curing the curable composition of the present invention is characterized by excellent mechanical properties, particularly tensile properties. When a test specimen with a thickness of 0.5 mm is evaluated at 25°C with a tensile speed of 50 mm / min, it typically exhibits a tensile elongation of 10% or more. By optimizing the curable composition, it is possible to achieve a tensile elongation of 50% or more in the cured product, making it useful as a layer-forming material for flexible displays.

[0104] If desired, the cured product obtained by curing the curable composition of the present invention can be designed to have a relative permittivity of 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 relative permittivity.

[0105] [Component (C)] When the UV-curable organopolysiloxane composition of the present invention is applied to a substrate surface as a coating agent by any method, in order to improve the wettability of the composition to the substrate and form a defect-free coating film, a component (C) selected from the following can be added to the composition of the present invention which contains the above-mentioned components. It is particularly preferable to use an inkjet printing method as a method for coating the substrate with the composition of the present invention. Therefore, component (C) is a component that improves the wettability of the UV-curable organopolysiloxane composition of the present invention to the substrate and significantly improves the inkjet printing characteristics in particular. Component (C) is at least one compound selected from the group consisting of (C1), (C2), and (C3) below.

[0106] (i) Component (C1) Component (C1) is a nonionic surfactant that does not contain silicon atoms and is not acrylic-based, i.e., a non-acrylic nonionic surfactant. Non-acrylic means that the surfactant 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-based nonionic surfactants, and one or more of these can be used in combination. Specific examples of component (C1) include the Emulgen series and Leodol series from Kao Corporation, the Surfinol 400 series from Evonik Industries, and the Orfin E series from Nisshin Chemical Industry Co., Ltd. as organic nonionic surfactants, and the FC-4400 series from 3M and the Megafac 550 and 560 series from DIC Corporation as fluorine-based nonionic surfactants. Among these, the Surfinol 400 series and Orphine E series, which are alquinol polyethers, are particularly preferred.

[0107] (ii) Component (C2) is a nonionic surfactant containing a silicon atom and having an HLB value of 4 or less. Here, the HLB value is a value that represents the degree of affinity of the surfactant to water and organic compounds, and here the HLB value is the value defined by the Griffin method (20 × sum of the formula weights of the hydrophilic parts / molecular weight). Silicone polyethers having a polyether as the hydrophilic part, glycerol silicones having a (di)glycerol derivative as the hydrophilic part, and carbinol silicones having a hydroxyethoxy group as the hydrophilic part are known as silicon-containing nonionic surfactants. Among these surfactants, it is preferable to use those with an HLB value of 4 or less, that is, those with a mass fraction of the hydrophilic part of 20% by mass or less, in the composition of the present invention. Among these, carbinol silicone is particularly preferred.

[0108] (iii) Component (C3) is a silicone oil with a viscosity of 90 mPa·s or less at 25°C. Examples of silicone oils include terminally trimethylsilyl-polydimethylsiloxane, terminally dimethylvinylsilyl-polydimethylsiloxane, terminally trimethylsilyl-dimethylsiloxy / methylvinylsiloxy copolymer, terminally dimethylvinylsilyl-dimethylsiloxy / methylvinylsiloxy copolymer, terminally trimethylsilyl-dimethylsiloxy / methylphenylsiloxy copolymer, terminally trimethylsilyl-dimethylsiloxy / diphenylsiloxy copolymer, terminally dimethylvinylsilyl-dimethylsiloxy / methylphenylsiloxy copolymer, terminally dimethylvinylsilyl-dimethylsiloxy / diphenylsiloxy copolymer, etc., but terminally trimethylsilyl-polydimethylsiloxane and terminally dimethylvinylsilyl-polydimethylsiloxane can be used. The preferred viscosity range for the silicone oil is 2 to 50 mPa·s, a more preferred range is 2 to 30 mPa·s, and an even more preferred range is 5 to 20 mPa·s. The viscosity values ​​here were measured at 25°C using the rotational viscometer described in the examples.

[0109] The components (C1) to (C3) described above can be used individually or in combination of two or more. The amount of component (C) to be blended into the curable composition is not particularly limited, but it is preferable that the sum of components (C1) to (C3) (collectively referred to as component (C)) is 0.05% by mass or more and 1% by mass or less, relative to the total amount of components (A) and (B) described above, which is 100% by mass. If the amount of component (C) is less than 0.05% by mass relative to the total amount of components (A) and (B) which is 100% by mass, the effect of improving the wettability of the curable composition to the substrate may not be sufficiently obtained, and if the amount of component (C) exceeds 1% by mass relative to the total amount of components (A) and (B) which is 100% by mass, there is a risk that component (C) may bleed out from the cured product after curing.

[0110] It is preferable to use component (C) as component (C3) silicone oil alone, or component (C3) in combination with one or more components selected from the group consisting of component (C1) and component (C2), and it is particularly preferable to use component (C3) alone as component (C).

[0111] [Other additives] The composition of the present invention may optionally contain other additives. Examples of additives that can be used include leveling agents, silane coupling agents not listed above as adhesion-improving agents, 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, the composition of the present invention may optionally contain thixotropic agents, particularly when used as a potting agent or sealing material. In particular, the following adhesion-improving agents may and preferably be added to the composition of the present invention.

[0112] [Adhesion-enhancing agent] The composition of the present invention may contain an adhesion promoter to improve adhesion and bonding to the substrate in contact with the composition. When the curable composition of the present invention is used in applications requiring adhesion or bonding to a substrate, such as coatings and sealants, 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.

[0113] 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 alkenyl group (e.g., vinyl group, allyl group), or organosiloxane oligomers having a linear, branched, or cyclic structure with approximately 4 to 20 silicon atoms; organosiloxanes having a trialkoxysiloxy group or a trialkoxysilylalkyl group and a methacryloxyalkyl group (e.g., 3-methacryloxypropyl group). Organosilane oligomers having linear, branched, or cyclic structures with approximately 4 to 20 silicon atoms; organosilanes or organosiloxane oligomers having linear, branched, or cyclic structures with approximately 4 to 20 silicon atoms, possessing a trialkoxysiloxy group or trialkoxysilyl alkyl 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); organic compounds having two or more trialkoxysilyl groups (e.g., trimethoxyyl group, triethoxysilyl group);Examples include reaction products of aminoalkyltrialkoxysilanes and epoxy-bonded alkyltrialkoxysilanes, and epoxy-containing ethyl polysilicates. Specifically, these include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 1,6-bis(trimethoxy) Examples include silyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,3-bis[2-(trimethoxysilyl)ethyl]-1,1,3,3-tetramethyldisiloxane, reaction products of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, condensation products of silanol-blocked methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, condensation products of silanol-blocked methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, and tris(3-trimethoxysilylpropyl)isocyanurate.

[0114] The amount of adhesion promoter added to the curable composition of the present invention is not particularly limited, but it is preferable that the amount is in the range of 0.01 to 5 parts by mass, or 0.01 to 2 parts by mass, based on 100 parts by mass of the total of components (A) and (B), in order to avoid promoting the curing properties of the curable composition or discoloration of the cured product.

[0115] [Application] The UV-curable organopolysiloxane composition of the present invention can be cured not only by ultraviolet light but also by electron beam, which is also one aspect of the present invention.

[0116] The curable composition of the present invention has low viscosity and is particularly useful as a material for forming insulating layers in various articles, especially 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 made of a material that allows ultraviolet light or electron beams to pass through, and cured by irradiation with ultraviolet light or electron beams to form an insulating layer. In this case, a pattern can be formed when applying the composition of the present invention to the substrate and then curing the composition, or the composition can be applied to the substrate and cured by irradiation with ultraviolet light or electron beams, leaving cured and uncured portions, and then the uncured portions can be removed with a solvent to form an insulating layer with a desired pattern. In particular, when the cured layer according to the present invention is an insulating layer, it can be designed to have a low dielectric constant of less than 3.0.

[0117] The curable composition of the present invention is particularly suitable as a material for forming an insulating layer in display devices such as touch panels and displays, due to the good transparency of the cured product obtained therefrom. In this case, the insulating layer may form any desired pattern as described above, if necessary. Therefore, a display device such as a touch panel or display, which includes an insulating layer obtained by curing the ultraviolet-curable organopolysiloxane composition of the present invention, is also one embodiment of the present invention.

[0118] Furthermore, the curable composition of the present invention can be used to coat an article and then cure it to form an insulating coating layer (insulating film). Therefore, the composition of the present invention can be used as an insulating coating agent. In addition, the cured product formed by curing the curable composition of the present invention can also be used as an insulating coating layer.

[0119] 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 electronic devices or as a material used in the manufacturing process of electronic devices. Electronic devices include electronic equipment 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, as well as as an interlayer insulating film for semiconductors, an etching stopper film, a surface protective film, a buffer coat 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.

[0120] Furthermore, in addition to being used as a coating agent, the UV-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.

[0121] The composition of the present invention can be used in particular as a material for forming a coating layer on a substrate surface using an inkjet printing method, in which case it is especially preferable that the composition of the present invention contains the above-mentioned component (C).

[0122] The present invention will be further described below based on examples, but the present invention is not limited to the following examples. [Examples]

[0123] The UV-curable composition and its cured product of the present invention will be described in detail with reference to examples. Furthermore, the measurements and evaluations in the examples and comparative examples were carried out as follows.

[0124] [Viscosity of curable compositions] The viscosity (mPa·s) of the composition at 25°C was measured using a rotational viscometer (VISCONIC EMD, E-type viscometer, manufactured by Tokimec Co., Ltd.).

[0125] [Appearance of the curable composition and the cured product obtained therefrom] The curable composition and the cured product obtained therefrom were observed and evaluated visually.

[0126] [Preparation of curable compositions] The quantities of each material listed in Table 1 below were placed in a brown plastic container and thoroughly mixed using a planetary mixer to prepare a curable composition.

[0127] [Curing of curable compositions and preparation of tensile test specimens] Approximately 0.2 g of a curable composition was injected between two glass substrates separated by a 0.5 mm thick spacer. LED light with a wavelength of 405 nm was shone from the outside through one of the glass substrates at a rate of 2 J / cm². 2 By irradiating with this energy level, the composition was cured to produce a plate-shaped cured material with a long side of 50 mm and a thickness of 0.5 mm. By dividing the short piece into three equal parts, a 10 × 50 × 0.5 (thickness) mm piece was obtained. 3 A strip-shaped tensile test specimen was prepared.

[0128] [Wettability of curable organopolysiloxane compositions to substrates (contact angle of the composition)] Two microliters of the curable composition were dropped onto a silicon nitride coated glass substrate, and the contact angle of the curable composition immediately after dropping and after 1 minute was measured at 23°C using a DM-700 contact angle measuring device manufactured by Kyowa Interface Chemical Co., Ltd. The unit of the contact angle is degrees (°).

[0129] [Examples and Comparative Examples] Using the following components, UV-curable compositions with the compositions (parts by mass) shown in Table 1 were prepared. (A1) 1,1,3,3,5,5,7,7,9,9-decamethyl-1,9-bis[2-(3,4-epoxycyclohexyl)ethyl]pentasiloxane: Average number of silicon atoms: 5 (A2) [2-(3,4-epoxycyclohexyl)ethyl] substituted polydimethylsiloxane at both ends: average silicon atom count 12 (B) 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane (A')1,3-Bis[2-(3,4-Epoxycyclohexyl)ethyl]-1,1,3,3-Tetramethyldisiloxane (C)DOWSIL TM 5562 Carbinol Fluid (manufactured by Dow Chemical Company) (D1) 4-Isopropyl-4'-methyldiphenyliodonium-tetrakis(pentafluorophenyl)borate (D2)2-Isopropylthioxanthone

[0130] [Table 1]

[0131] As shown in Table 1, the UV-curable compositions of the present invention (Examples 1-6) have a viscosity at 25°C that is suitable for application to a substrate as a coating agent, particularly for application by inkjet printing, and also have high transparency. Furthermore, these compositions have good wettability to the substrate, but the wettability can be further improved by adding component (C) (Example 6). In addition, the cured products obtained from the compositions of the present invention have high tensile elongation and excellent flexibility. On the other hand, compositions without component (B) (Comparative Examples 1 and 2) have a viscosity low enough to be applied, but the tensile elongation of the cured products is low and they cannot be said to have sufficient flexibility. [Industrial applicability]

[0132] The ultraviolet-curable composition of the present invention is suitable for the above-mentioned applications, particularly as a material for forming an insulating layer in display devices such as touch panels and displays, especially flexible displays.

Claims

1. (A) A linear organopolysiloxane having an epoxy group containing an ultraviolet-curable functional group at both ends of the molecular chain, and having an average number of silicon atoms in the range of 5 to 12, and (B) One or more organosilicon compounds having one UV-curable functional group per molecule An ultraviolet-curable composition comprising [a certain substance], substantially free of organic solvents, and having a total viscosity of 80 mPa·s or less as measured at 25°C using an E-type viscometer.

2. Component (B) has the average empirical formula: R ｃ R’ ｄ SiO （４－ｃ―ｄ）／２ (2) (In the formula, R is an epoxy group-containing group which is an ultraviolet-curable functional group, R' is a group selected from monovalent hydrocarbon groups, hydroxyl groups, and alkoxy groups, excluding UV-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, and the number of R in the numerator is 1. The ultraviolet-curable composition according to claim 1, wherein the organosilicon compound is selected from the group consisting of linear, branched, or cyclic organosilanes and organopolysiloxanes represented by .

3. Component (B) is, The following formula (3'): 【Chemistry 1】 （３’） (In the formula, all R １ ~R ８ Of the groups, only one epoxy group-containing group, which is an ultraviolet-curable functional group, exists in the molecule; the other R １ From R ８ Each of these is an organopolysiloxane represented by an unsubstituted or fluorine-substituted monovalent hydrocarbon group; n is a numerical value between 0 and 3. Alternatively, the following formula (4'): 【Chemistry 2】 （４’） A cyclic organopolysiloxane represented by the formula (wherein R is independently selected from an epoxy group-containing group that is an ultraviolet-curable functional group and an unsubstituted or fluorine-substituted monovalent hydrocarbon group, and x is an integer from 3 to 5, having only one epoxy group-containing group that is an ultraviolet-curable functional group in the molecule), Alternatively, the following formula (5'): RSiR' ３ (5') The ultraviolet-curable composition according to claim 2, which is a silicon-containing compound having one epoxy-containing group that is an ultraviolet-curable functional group in its molecule, selected from the group consisting of organosilanes represented by the formula (wherein R is an epoxy-containing group that is an ultraviolet-curable functional group, and R' is a group selected from monovalent hydrocarbon groups, hydroxyl groups, and alkoxy groups other than the ultraviolet-curable functional group).

4. The ultraviolet-curable composition according to claim 1, wherein component (B) is an organopolysiloxane having an average of 3 or more silicon atoms and one epoxy group-containing group which is an ultraviolet-curable functional group in the molecule.

5. The ultraviolet-curable composition according to any one of claims 1 to 4, wherein the ultraviolet-curable composition contains component (A) and component (B) in a mass ratio of 25 / 75 to 90 / 10 (A / B).

6. The ultraviolet-curable composition according to any one of claims 1 to 4, wherein the content of component (A) in the ultraviolet-curable composition is more than 20% by mass of the total amount of the curable composition.

7. Furthermore, the UV-curable composition according to any one of claims 1 to 4, further comprising (A') one or more organopolysiloxanes having two silicon atoms and two UV-curable functional groups in one molecule, in such a range that the mass ratio of component (A') to the total amount of component (A), component (B), and component (A') is less than 30%.

8. The UV-curable composition according to any one of claims 1 to 4, wherein component (A) is 1,1,3,3,5,5,7,7,9,9-decamethyl-1,9-bis[2-(3,4-epoxycyclohexyl)ethyl]pentasiloxane.

9. The UV-curable composition according to any one of claims 1 to 4, wherein component (B) is 1,1,1,3,5,5,5-heptamethyl-3-[2-(3,4-epoxycyclohexyl)ethyl]trisiloxane.

10. The ultraviolet-curable composition according to any one of claims 1 to 4, 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.

11. An insulating coating agent comprising the ultraviolet-curable composition according to any one of claims 1 to 4.

12. A cured product of the ultraviolet-curable composition according to any one of claims 1 to 4.

13. A method for using a cured product of an ultraviolet-curable composition according to any one of claims 1 to 4 as an insulating coating layer.

14. A display device comprising a layer made of a cured product of an ultraviolet-curable composition according to any one of claims 1 to 4.

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