Hardco film and method for manufacturing the same

Abstract

A silsesquioxane compound according to one embodiment of the present invention is a condensation product of a silane compound and has a structure represented by [R1-Si]. R1 is an organic group including an alicyclic epoxy group. The ratio of the structure to the total number of Si atoms is preferably 0.2-1.0. The number weight average molecular weight of the silsesquioxane compound is preferably 500-20000, and a ratio T3 / T2 of a T3 structure to a T2 structure is preferably 0.8-5 (exclusive of 5). The silsesquioxane compound is very suitably used in the formation of a hard coat layer. This hard coat composition may include a photocationic polymerization initiator in addition to the silsesquioxane compound.

Description

Technical Field

[0001] The present invention relates to a silsesquioxane compound including a hard coat composition It comprises a hard coat layer which is a cured product. and a hard coat film.

Background Art

[0002] With the rapid progress of electronic devices such as displays, touch panels, and solar cells, there is a demand for thinner, lighter, and more flexible devices. In response to these demands, replacement of glass materials used for substrates, cover windows, etc. with plastic film materials has been studied. In these applications, high heat resistance, dimensional stability at high temperatures, and high mechanical strength are required for plastic films. In recent years, curved displays (flexible displays, foldable displays) have been developed, and particularly for plastic films used for cover windows, etc., in addition to the above characteristics, excellent transparency and flexibility (flex resistance) have come to be required.

[0003] As a material for forming a hard coat layer, Patent Document 1 discloses a hard coat composition based on a silsesquioxane compound obtained by condensing an alkoxysilane containing an alicyclic epoxy group in the presence of a base catalyst. Patent Document 2 discloses a hard coat composition based on a siloxane compound containing an alicyclic epoxy group and having a proportion of T-type silane of 80% or more. Patent Documents 3 and 4 disclose a hard coat composition based on a siloxane compound containing an epoxy group and containing 5 equivalents or more and less than 16 equivalents of a completely condensed T-type silane (T3 body) with respect to a partially uncondensed T-type silane (T2 body).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Although the hard coat layers obtained by curing the silsesquioxane compounds disclosed in Patent Documents 1 to 4 have high hardness, cracks and fissures tend to occur in the hard coat layer when the hard coat film is bent with a small radius of curvature, posing challenges for application to flexible displays, foldable displays, and the like.

[0006] In view of the above, the present invention aims to provide a hard coat film having high hardness and excellent flexibility, and a curable material for forming the hard coat layer of the hard coat film. [Means for solving the problem]

[0007] In light of the above, after diligent research, we found that silsesquioxane compounds having an alicyclic epoxy group and in which the ratio of completely condensed T-type silane (T3) to partially uncondensed T-type silane (T2) is within a predetermined range can achieve both high hardness and flexibility when forming a hard coat layer.

[0008] A silsesquioxane compound according to one aspect of the present invention is a condensate of a silane compound represented by general formula (A). The number average molecular weight of the silsesquioxane compound is preferably 500 to 20000. R a -(Si(OR 2 ) x R 3 3-x ) …(A)

[0009] In general formula (A), R 2 is a hydrogen atom or an alkyl group, and R 3 is a monovalent hydrocarbon group selected from the group consisting of a hydrogen atom, an alkyl group, an aryl group, and an aralkyl group. x is an integer from 1 to 3.

[0010] By using the silane compound represented by general formula (1) as the above silane compound, a silsesquioxane having the structure represented by the following general formula (5) can be obtained. R 1 -(Si(OR 2 ) x R 3 3-x ) …(1) [R 1 -Si] …(5)

[0011] In general formula (1), R 2 , R 3 and x are the same as in general formula (A). R 1 is an organic group containing an alicyclic epoxy group. The ratio of the structure represented by general formula (5) to the total number of Si atoms of the silsesquioxane is preferably 0.2 to 1.0.

[0012] The silsesquioxane contains a structural unit (T3 unit) represented by general formula (3) and a structural unit (T2 unit) represented by general formula (4). The ratio T3 / T2 of the content of the T3 unit to the T2 unit is preferably 0.8 or more and less than 5. [R a -SiO 3 / 2 …(3) [R a -SiO 2 / 2 -Z] …(4)

[0013] In general formulas (3) and (4), R a is the same as in general formula (A). In general formula (4), Z is a hydroxy group or an alkoxy group.

[0014] Silsesquioxanes can be obtained by hydrolysis and condensation reactions of silane compounds. By using a compound represented by general formula (1) as part or all of the silane compound, a silsesquioxane having the structure of formula (5) can be obtained.

[0015] The hydrolysis and condensation reactions of silane compounds may be carried out in the presence of a neutral salt catalyst. Silsesquioxanes obtained by reactions in the presence of a neutral salt catalyst tend to have a small T3 / T2 ratio, making it easy to obtain compounds with a T3 / T2 ratio of less than 5.

[0016] As a neutral salt catalyst, a salt comprising a combination of an ion of an element selected from the group consisting of alkali metal elements and group 2 elements, and a halide ion selected from the group consisting of chloride ions, bromide ions, and iodide ions is preferred.

[0017] Silsesquioxane obtained by hydrolysis and condensation reactions of silane compounds may contain residual neutral salts. Silsesquioxane may contain neutral salts in a concentration of approximately 1 to 10,000 ppm.

[0018] The silsesquioxane described above is cationic polymerizable and is suitably used for forming a hard coat layer. One aspect of the present invention is a hard coat composition containing the silsesquioxane described above. In addition to silsesquioxane, the hard coat composition may also contain a cationic polymerization initiator. The cationic polymerization initiator may be a photocatalytic cationic polymerization initiator (photoacid generator).

[0019] One aspect of the present invention is a hard coat film comprising a hard coat layer made of a cured product of the above-mentioned hard coat composition on at least one main surface of a resin substrate. The thickness of the hard coat layer may be 0.5 to 100 μm. Examples of resin materials for the resin substrate include polyester, polycarbonate, polyamide, polyimide, cyclic polyolefin, acrylic resin, and cellulose-based resin.

[0020] A hard coat film is formed by applying the above-mentioned hard coat composition onto a resin substrate and curing the hard coat composition (the above-mentioned silsesquioxane) by irradiating it with active energy rays. [Effects of the Invention]

[0021] The cured film (hard coat layer) formed by the curing of the above-mentioned silsesquioxane compound has high surface hardness and excellent flexibility. A hard coat film having this cured film on a resin substrate is less prone to cracking even when bent with a small radius of curvature, and can be suitably used for flexible displays and foldable displays. [Modes for carrying out the invention]

[0022] One aspect of the present invention is a silsesquioxane having cationic polymerizability and a method for producing the same. Further aspects of the present invention are a hard coat composition containing the silsesquioxane compound, and a hard coat film comprising a hard coat layer made of a cured product of the hard coat composition, and a method for producing the same. Preferred forms of the silsesquioxane compound, the hard coat composition for forming the hard coat layer, and the hard coat film will be described in order below. Unless otherwise specified, the components and functional groups exemplified herein may be used alone or in combination (coexistence) of two or more types.

[0023] [Silsesquioxane compounds] <Silane compounds> A silsesquioxane compound according to one aspect of the present invention is a condensate of a silane compound represented by the following general formula (A). R a -(Si(OR 2 ) x R 3 3-x ) …(A)

[0024] R 2The group is either a hydrogen atom or an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms. Specific examples of alkyl groups with 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isopropyl, isobutyl, cyclohexyl, and ethylhexyl groups.

[0025] Silane compounds represented by general formula (A) contain 1 to 3 (-OR) molecules per molecule. 2 ) has Si-OR 2 Because it is hydrolyzable, a silsesquioxane compound can be obtained by condensation of a silane compound. From the viewpoint of hydrolysis, R 2 The number of carbon atoms is preferably 3 or less, R 2 It is particularly preferable that the group is a methyl group.

[0026] R 3 The group is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of alkyl groups, aryl groups, and aralkyl groups. The alkyl group preferably has 1 to 16 carbon atoms. The aryl group preferably has 6 to 25 carbon atoms. The aralkyl group preferably has 7 to 12 carbon atoms. Specific examples of hydrocarbons in alkyl groups and aralkyl groups include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isopropyl group, isobutyl group, cyclohexyl group, ethylhexyl group, benzyl group, phenyl group, tolyl group, xylyl group, naphthyl group, phenethyl group, and the like.

[0027] In general formula (A), x is an integer from 1 to 3, and when x=3 (i.e., the Si atom has three alkoxy groups (or hydroxyl groups) - OR 2 (When bonded), the silane compound R 3It does not have [a specific characteristic]. From the viewpoint of forming a network-like silsesquioxane compound and increasing the number of epoxy groups contained in the silsesquioxane compound to increase the hardness of the cured film, it is preferable that x = 3 in general formula (A). A silane compound with x = 2 and a silane compound with x = 3 may be used in combination. In addition, a silane compound with x = 1 may be used in addition to a silane compound with x = 2 or 3 for the purpose of adjusting the molecular weight of the silsesquioxane compound obtained by condensation.

[0028] SiO contained in silane compounds 3 / 2 (T structure; corresponding to x=3 in general formula (A)), SiO 2 / 2 (Structure D; corresponding to x=2 in general formula (A)), and SiO 1 / 2 The ratio of T structures to the total number of structures (M structures; corresponding to x=1 in general formula (A)) is preferably 0.2 or higher, more preferably 0.4 or higher, even more preferably 0.6 or higher, and may be 0.7 or higher, 0.8 or higher, 0.9 or higher, 0.95 or higher, or 1. The higher the ratio of T structures of the silane compound, the higher the mechanical strength of the hard coat layer tends to be.

[0029] In general formula (A), R a R is any monovalent organic group. The silsesquioxane compound in one aspect of the present invention is a silane compound represented by the following general formula (1) as the silane compound, i.e., the organic group R in general formula (A). a R 1 It contains the compound that is [this compound]. R 1 -(Si(OR 2 ) x R 3 3-x ) …(1)

[0030] In general formula (1), R 2 , R 3 And x are the same as in general formula (A). R 1 This is an organic group containing an alicyclic epoxy group. Because the silane compound contains an alicyclic epoxy group, the silsesquioxane compound obtained by the condensation of the silane compound has photocationic polymerizability.

[0031] Organic groups containing alicyclic epoxy groups include alicyclic epoxy groups, alkyl groups having alicyclic epoxy groups as substituents, and ethylene glycol groups having alicyclic epoxy groups as substituents. From the viewpoint of heat resistance and flexural resistance of the hard coat layer, R 1 Preferably, alkyl groups have alicyclic epoxy groups as substituents. Specific examples of alkyl groups having alicyclic epoxy groups as substituents include (3,4-epoxycyclohexyl)methyl group, 2-(3,4-epoxycyclohexyl)ethyl group, 3-(3,4-epoxycyclohexyl)propyl group, 4-(3,4-epoxycyclohexyl)butyl group, 5-(3,4-epoxycyclohexyl)pentyl group, 6-(3,4-epoxycyclohexyl)hexyl group, 7-(3,4-epoxycyclohexyl)heptyl group, 8-(3,4-epoxycyclohexyl)octyl group, 9-(3,4-epoxycyclohexyl)nonyl group, and 10-(3,4-epoxycyclohexyl) Examples include the chlorohexyl)decyl group, 11-(3,4-epoxycyclohexyl)undecyl group, 12-(3,4-epoxycyclohexyl)dodecyl group, 13-(3,4-epoxycyclohexyl)tridecyl group, 14-(3,4-epoxycyclohexyl)tetradecyl group, 15-(3,4-epoxycyclohexyl)pentadecyl group, 16-(3,4-epoxycyclohexyl)hexadecyl group, 2-(3,4-epoxycyclohexyl)isopropyl group, 3-(3,4-epoxycyclohexyl)isobutyl group, and 6-(3,4-epoxycyclohexyl)ethylhexyl group.

[0032] Specific examples of compounds represented by general formula (1) (hereinafter sometimes referred to as "silane compounds (1)") include (3,4-epoxycyclohexyl)trimethoxysilane, (3,4-epoxycyclohexyl)methyldimethoxysilane, (3,4-epoxycyclohexyl)dimethylmethoxysilane, (3,4-epoxycyclohexyl)triethoxysilane, (3,4-epoxycyclohexyl)methyldiethoxysilane, (3,4-epoxycyclohexyl)dimethylethoxysilane, {(3,4-epoxycyclohexyl)methyl}trimethoxysilane, {(3,4-epoxycyclohexyl)methyl}methyldimethoxysilane, {(3,4-epoxycyclohexyl)methyl}dimethylmethoxysilane, {(3,4-epoxycyclohexyl)methyl}triethoxysilane, {(3,4-epoxycyclohexyl)methyl}methyldiethoxysilane, {(3,4-epoxycyclohexyl)methyl}dimethylethoxysilane, {2-(3,4-epoxycyclohexyl)ethyl}trimethoxysilane, {2-(3,4-epoxycyclohexyl)ethyl}methyldimethoxysilane, {2-(3,4-epoxycyclohexyl)ethyl}methyldimethoxysilane {2-(3,4-epoxycyclohexyl)ethyl}dimethylmethoxysilane, {2-(3,4-epoxycyclohexyl)ethyl}triethoxysilane, {2-(3,4-epoxycyclohexyl)ethyl}methyldiethoxysilane, {2-(3,4-epoxycyclohexyl)ethyl}dimethylethoxysilane, {3-(3,4-epoxycyclohexyl)propyl}trimethoxysilane, {3-(3,4-epoxycyclohexyl)propyl}methyldimethoxysilane, {3-(3,4-epoxycyclohexyl)propyl}dimethylmethoxysilane, {3-(3,4 {3-(3,4-epoxycyclohexyl)propyl}triethoxysilane, {3-(3,4-epoxycyclohexyl)propyl}methyldiethoxysilane, {3-(3,4-epoxycyclohexyl)propyl}dimethylethoxysilane, {4-(3,4-epoxycyclohexyl)butyl}trimethoxysilane, {4-(3,4-epoxycyclohexyl)butyl}methyldimethoxysilane, {4-(3,4-epoxycyclohexyl)butyl}dimethylmethoxysilane, {4-(3,{4-Epoxycyclohexyl)butyl}methyldiethoxysilane, {4-(3,4-Epoxycyclohexyl)butyl}dimethylethoxysilane, {5-(3,4-Epoxycyclohexyl)pentyl}trimethoxysilane, {5-(3,4-Epoxycyclohexyl)pentyl}methyldimethoxysilane, {5-(3,4-Epoxycyclohexyl)pentyl}dimethylmethoxysilane, {5-(3,4-Epoxycyclohexyl)pentyl}triethoxysilane, {5-(3,4-Epoxycyclohexyl)pentyl}methyldiethoxysilane {5-(3,4-epoxycyclohexyl)pentyl}dimethylethoxysilane, {6-(3,4-epoxycyclohexyl)hexyl}trimethoxysilane, {6-(3,4-epoxycyclohexyl)hexyl}methyldimethoxysilane, {6-(3,4-epoxycyclohexyl)hexyl}dimethylmethoxysilane, {6-(3,4-epoxycyclohexyl)hexyl}triethoxysilane, {6-(3,4-epoxycyclohexyl)hexyl}methyldiethoxysilane, {6-(3,4-epoxycyclohexyl)hexyl} Dimethylethoxysilane, {8-(3,4-epoxycyclohexyl)octyl}trimethoxysilane, {8-(3,4-epoxycyclohexyl)octyl}methyldimethoxysilane, {8-(3,4-epoxycyclohexyl)octyl}dimethylmethoxysilane, {8-(3,4-epoxycyclohexyl)octyl}triethoxysilane, {8-(3,4-epoxycyclohexyl)octyl}methyldiethoxysilane, {8-(3,4-epoxycyclohexyl)octyl}dimethylethoxysilane, {10-(3,4-epoxycyclohexyl) {10-(3,4-epoxycyclohexyl)decyl}trimethoxysilane, {10-(3,4-epoxycyclohexyl)decyl}methyldimethoxysilane, {10-(3,4-epoxycyclohexyl)decyl}dimethylmethoxysilane, {10-(3,4-epoxycyclohexyl)decyl}triethoxysilane, {10-(3,4-epoxycyclohexyl)decyl}methyldiethoxysilane, {10-(3,4-epoxycyclohexyl)decyl}dimethylethoxysilane, {12-(3,{12-(3,4-epoxycyclohexyl)dodecyl}methyldimethoxysilane, {12-(3,4-epoxycyclohexyl)dodecyl}dimethylmethoxysilane, {12-(3,4-epoxycyclohexyl)dodecyl}triethoxysilane, {12-(3,4-epoxycyclohexyl)dodecyl}methyldiethoxysilane, {12-(3,4-epoxycyclohexyl)dodecyl}dimethylethoxysilane, {14-(3,4-epoxycyclohexyl)tetradecyl}trimethoxysilane, {14-(3,4-epoxycyclohexyl)tetradecyl}methyldimethoxysilane, {14-(3,4-epoxycyclohexyl)tetradecyl}dimethylmethoxysilane, {14-(3,4-epoxycyclohexyl)tetradecyl}tri Examples include toxysilane, {14-(3,4-epoxycyclohexyl)tetradecyl}methyldiethoxysilane, {14-(3,4-epoxycyclohexyl)tetradecyl}dimethylethoxysilane, {16-(3,4-epoxycyclohexyl)hexadecyl}trimethoxysilane, {16-(3,4-epoxycyclohexyl)hexadecyl}methyldimethoxysilane, {16-(3,4-epoxycyclohexyl)hexadecyl}dimethylmethoxysilane, {16-(3,4-epoxycyclohexyl)hexadecyl}triethoxysilane, {16-(3,4-epoxycyclohexyl)hexadecyl}methyldiethoxysilane, and {16-(3,4-epoxycyclohexyl)hexadecyl}dimethylethoxysilane.

[0033] When obtaining a silsesquioxane compound by condensation of a silane compound, in addition to silane compound (1) above, other silane compounds may be used as the compound represented by general formula (A). Other silane compounds (i.e., silane compounds that do not contain an alicyclic epoxy group, hereinafter sometimes referred to as "silane compound (2)") are represented by the following general formula (2). R 4 -(Si(OR 2 ) x R 3 3-x ) …(2)

[0034] In general formula (2), R2 , R 3 And x are the same as in general formula (A). R 4 This is a monovalent organic group that does not contain an alicyclic epoxy group. 4 This includes groups containing substituted or unsubstituted double bonds, groups containing substituted or unsubstituted cycloalkyl groups, groups containing substituted or unsubstituted aromatic rings, substituted or unsubstituted alkyl groups, groups having a glycidyl group, groups having an oxetanyl group, or hydrogen atoms.

[0035] Groups containing substituted or unsubstituted double bonds include vinyl groups, allyl groups, Iso Examples include propenyl groups. Groups containing substituted or unsubstituted cycloalkyl groups include cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclobutylmethyl group, cyclopentylmethyl group, cyclohexylmethyl group, cyclobutylethyl group, cyclopentylethyl group, and cyclohexylethyl group. Groups containing substituted or unsubstituted aromatic rings include phenyl group, 4-methylphenyl group, tolyl group, and naphthyl group. Examples of substituted or unsubstituted alkyl groups include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, isopropyl group, isobutyl group, cyclohexyl group, and ethylhexyl group. Groups containing a glycidyl group include glycidyloxymethyl group, 2-glycidyloxyethyl group, 3-glycidyloxypropyl group, 4-glycidyloxybutyl group, 5-glycidyloxypentyl group, 6-glycidyloxyhexyl group, 7-glycidyloxyheptyl group, 8-glycidyloxyoctyl group, 9-glycidyloxynonyl group, 10-glycidyloxydecyl group, 11-glycidyloxyundecyl group, 12-glycidyloxidedodecyl group, 14-glycidyloxytetradecyl group, and 16-glycidyloxyhexadecyl group. Groups containing an oxetanyl group include oxetanylmethyl group, 3-methyl-3-oxetanylmethoxymethyl group, and 3-ethyl-3-oxetanylmethoxymethyl group.

[0036] When obtaining a silsesquioxane compound by condensation of silane compounds, the ratio of silane compound (1) to the silane compound represented by general formula (A) (i.e., the sum of silane compound (1) and silane compound (2)) is preferably 20 to 100 mol%, more preferably 33 to 100 mol%, and even more preferably 50 to 100 mol%. The ratio of silane compound (1) is determined by the organic group R in the silsesquioxane compound. a The ratio of alicyclic epoxy groups to the total amount is approximately equal. The silsesquioxane compound tends to have a higher hardness in the hard coat layer due to the presence of alicyclic epoxy groups derived from silane compound (1). The ratio of silane compound (1) may be 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more, or it may be 100 mol%.

[0037] <Properties of silsesquioxane compounds> (molecular weight) Si-OR of the above silane compounds 2 Through partial hydrolysis and condensation, Si-O-Si bonds are formed between silane compounds, generating silsesquioxane compounds. From the viewpoint of increasing the hardness of the cured film (hard coat layer), the number average molecular weight of the silsesquioxane compound is preferably 500 or more. Also, from the viewpoint of suppressing volatilization, the number average molecular weight of the silsesquioxane compound is preferably 500 or more. On the other hand, if the molecular weight is excessively large, turbidity may occur due to a decrease in compatibility with other compositions. For this reason, the number average molecular weight of the silsesquioxane compound is preferably 20,000 or less. The number average molecular weight of the silsesquioxane compound is more preferably 700 to 18,000, even more preferably 1,000 to 16,000, and may also be 1,200 to 14,000, or 1,500 to 12,000.

[0038] The number-average molecular weight of silsesquioxane compounds can be controlled by appropriately selecting the amount of water used in the reaction, as well as the type and amount of catalyst. For example, the more water added along with the catalyst during a hydrolysis reaction, the higher the number-average molecular weight tends to be.

[0039] (T3 / T2 ratio) The silsesquioxane compounds produced by the hydrolysis condensation of silane compounds of general formula (A) include structural units represented by the following formula (3) and structural units represented by the following formula (4).

[0040] [R a SiO 3 / 2 ] …(3) [R a SiO 2 / 2 -Z] …(4)

[0041] In general formulas (3) and (4), R a This is the same as general formula (A). In the silsesquioxane compound produced by the condensation of silane compound (1), R a The above R 4 In formula (4), Z is a hydroxyl group or an alkoxy group having an alkyl group with 1 to 10 carbon atoms. Specific examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, and decyloxy groups.

[0042] The constituent unit represented by formula (3) is a silane compound having a T unit structure where x=3 in general formula (A) and three alkoxy groups (Si-OR 2 The structure in which all of the alkoxy groups in the silane compound have undergone a condensation reaction to form a Si-O-Si bond is called the "T3 isomer". The constituent unit represented by formula (4) is a structure in which two of the three alkoxy groups of the silane compound having a T unit structure with x=3 in general formula (A) have undergone a condensation reaction to form a Si-O-Si bond, and is called the "T2 isomer".

[0043] In the embodiments of the present invention, the silsesquioxane compound preferably has a ratio [T3] / [T2] of the structure represented by formula (3) (T3 isomer) to the structure represented by formula (4) (T2 isomer) of less than 5. A ratio of T3 isomer to T2 isomer (hereinafter sometimes referred to as the "T3 / T2 ratio") of less than 5 tends to improve the flexibility of the hard coat layer formed by the curing of the silsesquioxane compound.

[0044] The T3 / T2 ratio of the silsesquioxane compound is more preferably 4 or less, even more preferably 3.5 or less, and may be 3 or less or 2.5 or less. The smaller the T3 / T2 ratio, the higher the flexural resistance of the hard coat layer, and the more likely it is that cracks and fractures in the hard coat layer when the hard coat film is bent will be suppressed.

[0045] From the viewpoint of increasing the surface hardness of the hard coat layer, the T3 / T2 ratio of the silsesquioxane compound is preferably 0.8 or higher, more preferably 1 or higher, even more preferably 1.5 or higher, and may also be 2 or higher.

[0046] The higher the proportion of T3 isomers, the easier it is to form a dense, three-dimensionally grown polysiloxane skeleton, which tends to increase hardness. However, this also reduces the flexibility of the molecular structure, so when the proportion of T3 isomers is 5 or higher, the flexural resistance of the hard coat layer is considered to be insufficient. As described above, a T3 / T2 ratio of less than 5 is considered to provide an excellent balance between the superior mechanical strength due to the formation of the polysiloxane skeleton and the flexibility (flexural resistance) due to the T2 isomers, resulting in the formation of a hard coat layer with high surface hardness and excellent flexural resistance.

[0047] SiO in silsesquioxane compounds 3 / 2 Body and SiO 2 / 2 The content and proportion of the body are, 29 This can be calculated by Si-NMR measurement. 29 In Si-NMR, SiO 3 / 2 Si atoms and SiO 2 / 2Since the Si atoms in a molecule exhibit different chemical shifts, the T3 / T2 ratio can be calculated by determining the integral value of each signal in the NMR spectrum and taking the ratio of the two.

[0048] The T3 / T2 ratio can be controlled by adjusting the amount of water used in the hydrolysis condensation reaction of silane compounds, the type of catalyst, and the amount of catalyst. For example, a larger amount of catalyst tends to result in a larger T3 / T2 ratio. As described later, using a neutral salt catalyst tends to result in a smaller T3 / T2 ratio.

[0049] <Hydrolysis and condensation of silane compounds> By reacting a silane compound with water, the Si-OR of the silane compound is produced. 2 The silsesquioxane compound is obtained by partial hydrolysis and condensation of the hydrolysates. The amount of water required for the hydrolysis and condensation reaction is determined by the -OR bonded to the Si atom. 2 0.3 to 3 equivalents per 1 equivalent of the base is preferable, and 0.5 to 2 equivalents is more preferable. If the amount of water is excessively small, the OR will remain without hydrolysis. 2 Due to the large number of groups and the low molecular weight of the silsesquioxane compound, the hard coat layer tends to lack sufficient hardness. If the amount of water is excessively high, the reaction rates of hydrolysis and condensation reactions are high, leading to the formation of high molecular weight condensates, which tends to reduce the transparency and flexibility of the hard coat layer.

[0050] In the hydrolysis and condensation reactions of silane compounds, it is preferable to suppress the deactivation of the alicyclic epoxy group contained in the silane compound (1) by ring-opening. From the viewpoint of suppressing the ring-opening of the epoxy group, it is preferable to carry out the reaction under neutral or basic conditions. In particular, from the viewpoint of reducing the T3 / T2 ratio of the silsesquioxane compound obtained as a condensate of the silane compound, it is preferable to carry out the hydrolysis and condensation reactions in the presence of a neutral salt catalyst.

[0051] A neutral salt is a normal salt of a strong acid and a strong base, specifically an alkali metal element and a second tribeIt is a salt of an elemental ion (cation) selected from the group consisting of elements, and a halide ion (anion) selected from the group consisting of chloride ions, bromide ions, and iodide ions.

[0052] Specific examples of neutral salts include lithium chloride, sodium chloride, potassium chloride, beryllium chloride, magnesium chloride, calcium chloride, lithium bromide, sodium bromide, potassium bromide, beryllium bromide, magnesium bromide, calcium bromide, lithium iodide, sodium iodide, potassium iodide, beryllium iodide, magnesium iodide, and calcium iodide.

[0053] As described above, by using a neutral salt catalyst, silsesquioxane compounds with a small T3 / T2 ratio can be obtained. Furthermore, while acid and base catalysts react electrophilically and nucleophilically with various substances, neutral salts have the advantage of being less corrosive to metal and resin materials in reaction vessels and storage containers, thus reducing constraints on the materials used in manufacturing and storage equipment.

[0054] If a basic catalyst, commonly used in the condensation reaction of silane compounds, remains in the hard coat composition, it may quench the acid generated from the photocationic polymerization initiator (photoacid generator), thereby inhibiting the polymerization reaction. In contrast, using a neutral salt catalyst can suppress polymerization inhibition. Therefore, the silsesquioxane compound obtained by the condensation of silane compounds and the hard coat composition may contain residual neutral salt catalysts, and steps such as catalyst removal or neutralization after the reaction can be omitted. The use of a neutral salt catalyst can contribute to simplifying the manufacturing process and improving yield.

[0055] The amount of catalyst used is not particularly limited. A larger amount of catalyst tends to accelerate the hydrolysis and condensation reactions of the silane compound. On the other hand, excessive use of catalyst may impair the transparency of the condensate or complicate purification. The amount of neutral salt catalyst used depends on the hydrolyzable silyl group (-OR) of the silane compound. 2) 0.000001 to 0.1 moles per mole is preferable, and 0.000005 to 0.01 moles is more preferable.

[0056] As described above, the silsesquioxane compound obtained by the hydrolysis and condensation reaction of the silane compound may contain residual neutral salt catalyst. The amount of residual neutral salt (catalyst) in the silsesquioxane compound may be 1 ppm or more, 10 ppm or more, 50 ppm or more, or 100 ppm or more. From the viewpoint of transparency of the hard coat layer, the amount of residual basic catalyst in the silsesquioxane compound is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, even more preferably 3,000 ppm or less, and may be 1,000 ppm or less, 800 ppm or less, or 500 ppm or less.

[0057] In the hydrolysis and condensation reactions of silane compounds, the reaction may be carried out under reflux of the diluent and the alcohol generated by hydrolysis. The diluent is preferably one that is miscible with water, and a water-soluble alcohol or ether compound is preferred. Since many silane compounds have low miscibility with neutral salts or water used in hydrolysis, it is preferable to react them as a miscible system in solution using a diluent.

[0058] The boiling point of the diluent is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. If the boiling point of the diluent is excessively low, the diluent may reflux at low temperatures, which may reduce the reaction rate. From the viewpoint of the ease of removing the diluent after the reaction, the boiling point of the diluent is preferably 200°C or lower.

[0059] Specific examples of diluent solvents include methanol, ethanol, 1-propanol, 2-propanol, 2-butanol, 1-methoxy-2-propanol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, and propylene glycol dimethyl ether.

[0060] The reaction temperature for the hydrolysis and condensation reactions of silane compounds is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. A reaction temperature of 40°C or higher allows for a shorter reaction time due to the high catalytic activity of the neutral salt. From the viewpoint of suppressing side reactions of the organic groups of the silane compound, a reaction temperature of 200°C or lower is preferable.

[0061] From the viewpoint of increasing the crosslinking point density in the cured product (hard coat layer) and improving hardness, it is preferable that the silsesquioxane compound obtained by hydrolysis and condensation of a silane compound has a high epoxy group retention rate. The epoxy group retention rate, that is, the ratio of the number of moles of epoxy groups in the silsesquioxane compound obtained by condensation to the number of moles of epoxy groups in the silane compound represented by general formula (A), which is the raw material, is preferably 20% or more, more preferably 40% or more, even more preferably 60% or more, particularly preferably 80% or more, and may be 90% or more or 95% or more. The epoxy group retention rate is 1 It can be determined by 1H-NMR measurement.

[0062] As described above, silsesquioxane compounds are obtained by hydrolysis and condensation reactions of silane compounds represented by general formula (A). In the hydrolysis and condensation reactions, excluding side reactions such as ring opening of epoxy groups, a monovalent organic group R bonded to the Si atom is formed. a Since it does not react, in silsesquioxane compounds, [R] in silane compounds a The structural part of -Si is retained. Therefore, the silsesquioxane compound obtained by the condensation of silane compound (1) has a structure represented by the following general formula (5) (hereinafter sometimes referred to as "structure (5)"). [R 1 -Si] …(5)

[0063] R in general formula (5) 1 This is the same as general formula (1). That is, structure (5) is a structure in which an alicyclic epoxy group is bonded to a Si atom, either via or without other organic groups.

[0064] The ratio of the number of structural (5) groups (i.e., the number of alicyclic epoxy groups) to the total number of Si atoms in the silsesquioxane compound is preferably 20% or more, more preferably 33% or more, even more preferably 50% or more, and may be 60% or more, 70% or less, 80% or more, 90% or more, or 95% or more.

[0065] Since silane compounds represented by general formula (A) have one Si atom per molecule, the silsesquioxane compound produced by the condensation of N molecules of silane compounds contains N Si atoms. If alicyclic epoxy groups remain unreacted during hydrolysis and condensation reactions, n structures (5) are produced from n silane compounds (1). Therefore, in the silsesquioxane compound obtained by the condensation of silane compounds, the proportion of silane compound (1) in the silane compounds used as starting materials (molar ratio: n / N) is approximately equal to the ratio of structures (5) to the number of Si atoms in the silsesquioxane compound.

[0066] When silane compound (2) is used in addition to silane compound (1) as the silane compound, the silsesquioxane compound has a structure represented by the following general formula (6) in addition to the structure (5) described above (hereinafter sometimes referred to as "structure (6)"). [R 4 -Si] …(6) R in general formula (6) 4 This is the same as in general formula (2).

[0067] [Hard coat composition] One embodiment of the present invention is a hard coat composition containing the above-mentioned silsesquioxane compound as an essential component. The hard coat composition preferably contains a cationic polymerization initiator in addition to the silsesquioxane compound, and may also contain other components.

[0068] From the viewpoint of forming a hard coat cured film with excellent mechanical strength, the content of the silsesquioxane compound in the hard coat composition is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, and even more preferably 60 parts by weight or more, based on 100 parts by weight of the total solid content (non-volatile content).

[0069] <Cationic polymerization initiator> The hard coat composition preferably contains a thermal cationic polymerization initiator or a photocationic polymerization initiator as a curing catalyst. A thermal cationic polymerization initiator is a compound that generates acid upon heating (thermal acid generator), and a photocationic polymerization initiator is a compound that generates acid upon irradiation with active energy rays (photoacid generator). The acid generated from the cationic polymerization initiator promotes the ring-opening and polymerization reaction of the epoxy group of the silsesquioxane compound, forming intermolecular crosslinks and curing the hard coat material.

[0070] Examples of photoacid generators include onium salts, which are combinations of anions (strong acids) such as antimony hexafluoride, boron tetrafluoride, phosphorus hexafluoride, fluoroalkyl phosphorus fluoride, and fluoroalkyl gallium fluoride with cations such as sulfonium, ammonium, phosphonium, iodonium, and selenium; iron-allene complexes; silanol-metal chelate complexes; sulfonic acid derivatives such as disulfones, disulfonyldiazomethanes, disulfonylmethanes, sulfonylbenzoylmethanes, imidosulfonates, and benzoin sulfonates; and organic halogen compounds.

[0071] As the cation for the photoacid generator, aromatic sulfonium or aromatic iodonium is preferred due to its high stability in the hard coat composition. As the counteranion, fluoroantimonate anions, fluoroborate anions, fluorophosphate anions, fluorogallium anions, etc. are preferred because they have high acidity and make it easy to obtain a hard coat layer with excellent surface hardness and adhesion to the resin substrate.

[0072] The amount of photocationic polymerization initiator in the hard coat composition is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.2 to 2 parts by weight, per 100 parts by weight of the silsesquioxane compound.

[0073] <Leveling agent> The hard coat composition may contain a leveling agent. The inclusion of a leveling agent in the hard coat layer can be expected to reduce surface tension, improve surface smoothness, enhance slipperiness, and improve stain resistance (fingerprint resistance, etc.). Furthermore, if the leveling agent has groups that react with epoxy groups and / or hydrolyzable condensation groups, improved scratch resistance of the hard coat layer can be expected.

[0074] Examples of leveling agents include silicone-based leveling agents and fluorine-based leveling agents. Examples of silicone-based leveling agents include leveling agents having a polysiloxane skeleton.

[0075] Examples of fluorine-based leveling agents include leveling agents having a fluoroaliphatic hydrocarbon skeleton. Examples of fluoroaliphatic hydrocarbon skeletons include fluoromethane, fluoroethane, fluoropropane, fluoroisopropane, fluorobutane, fluoroisobutane, fluorot-butane, fluoropentane, fluorohexane, and other fluoroC 1-10 Examples include alkanes. The fluoroaliphatic hydrocarbon skeleton only needs to have at least some of the hydrogen atoms of the hydrocarbon replaced by fluorine atoms. From the viewpoint of improving the scratch resistance, slipperiness, and stain resistance of the hard coat layer, perfluoroaliphatic hydrocarbons in which all hydrogen atoms are replaced by fluorine atoms are particularly preferred.

[0076] When the hard coat composition contains a leveling agent, its content is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and even more preferably 0.05 to 1 part by weight or less, per 100 parts by weight of the silsesquioxane compound. When the hard coat layer contains a leveling agent, it is preferable that 30% or more of the total amount of the leveling agent is segregated within 100 nm from the surface of the hard coat layer. The amount of leveling agent present within 100 nm from the surface of the hard coat layer is more preferably 50% or more, and even more preferably 80% or more. Segregation of the leveling agent on the surface tends to increase the water contact angle of the hard coat layer, thereby improving its stain resistance.

[0077] <Reactive additives> The hard coat composition may contain a reactive additive. The reactive diluent may contain, for example, a cationic polymerizable compound other than the silsesquioxane compound mentioned above. As the reactive additive for photocationic polymerization, a compound having a cationic polymerizable functional group is used. Examples of cationic polymerizable functional groups in the reactive diluent include epoxy groups, vinyl ether groups, oxetane groups, and alkoxysilyl groups. Due to its compatibility with silsesquioxane compounds and high reactivity with the epoxy groups of silsesquioxane compounds, a reactive additive having an epoxy group is preferred. Furthermore, because it has a high reaction rate, increases the hard coat layer curing rate, reduces surface tackiness (increases tack-free properties), and tends to suppress adhesion (blocking) of the hard coat film, a reactive additive having a vinyl ether group is preferred.

[0078] The content of the reactive additive in the hard coat composition is preferably 150 parts by weight or less, more preferably 100 parts by weight or less, and even more preferably 50 parts by weight or less, per 100 parts by weight of the silsesquioxane compound.

[0079] <Photosensitizer> The hard coat composition may contain a photosensitizer for purposes such as improving the photosensitivity of the photocationic polymerization initiator (photoacid generator). A photosensitizer that can absorb light in wavelength ranges that the photoacid generator itself cannot absorb is more efficient, and therefore, one that has little overlap with the absorption wavelength range of the photoacid generator is preferred. Examples of photosensitizers include anthracene derivatives, benzophenone derivatives, thioxanthone derivatives, anthraquinone derivatives, and benzoin derivatives.

[0080] The amount of photosensitizer in the hard coat composition is preferably 500 parts by weight or less, more preferably 100 parts by weight or less, and even more preferably 50 parts by weight or less, per 100 parts by weight of the above-mentioned photoacid generator.

[0081] <particle> The hard coat composition may contain particles for purposes such as adjusting film properties like surface hardness and flexibility, or suppressing curing shrinkage. The particles may be organic particles, inorganic particles, or organic-inorganic composite particles, selected as appropriate. Examples of organic particle materials include alkyl poly(meth)acrylates, crosslinked alkyl poly(meth)acrylates, crosslinked styrene, nylon, silicone, crosslinked silicone, crosslinked urethane, and crosslinked butadiene. Examples of inorganic particle materials include metal oxides such as silica, titania, alumina, tin oxide, zirconia, zinc oxide, and antimony oxide; metal nitrides such as silicon nitride and boron nitride; and metal salts such as calcium carbonate, calcium hydrogen phosphate, calcium phosphate, and aluminum phosphate. Examples of organic-inorganic composite fillers include those in which an inorganic layer is formed on the surface of organic particles, or those in which an organic layer or organic fine particles are formed on the surface of inorganic particles.

[0082] Particle shapes include spherical, powdery, fibrous, needle-shaped, and flaky. Spherical particles are anisotropic and stress is less likely to be unevenly distributed, thus suppressing the generation of strain and contributing to the suppression of film warping caused by curing shrinkage, etc.

[0083] The average particle diameter is, for example, about 5 nm to 10 μm. From the viewpoint of improving the transparency of the hard coat layer, the average particle diameter is preferably 1000 nm or less, more preferably 500 nm or less, even more preferably 300 nm or less, and particularly preferably 100 nm or less. The particle diameter can be measured using a laser diffraction / scattering particle size distribution analyzer, and the median diameter based on volume is taken as the average particle diameter.

[0084] The hard coat composition may contain surface-modified particles. Surface modification of the particles tends to improve their dispersibility in the silsesquioxane compound. Furthermore, if the particle surface is modified with polymerizable functional groups that can react with epoxy groups, the functional groups on the particle surface react with the epoxy groups of the silsesquioxane compound to form chemical crosslinks, which can be expected to improve film strength.

[0085] Polymerizable functional groups that can react with epoxy groups include vinyl groups, (meth)acrylic groups, hydroxyl groups, phenolic hydroxyl groups, carboxyl groups, acid anhydride groups, amino groups, epoxy groups, and oxetane groups. Among these, epoxy groups are preferred. In particular, particles surface-modified with epoxy groups are preferred because they can form chemical crosslinks between the particles and the silsesquioxane compound during the curing of the hard coat composition by photocationic polymerization.

[0086] Examples of particles having reactive functional groups on their surface include surface-modified inorganic particles and core-shell polymer particles.

[0087] <Solvent> The hard coat composition may be solvent-free or may contain a solvent. If a solvent is included, it is preferable that the solvent does not dissolve the resin substrate. On the other hand, using a solvent that has enough solubility to swell the resin substrate may improve the adhesion between the resin substrate and the hard coat layer. The solvent content is preferably 500 parts by weight or less, more preferably 300 parts by weight or less, and even more preferably 100 parts by weight or less, per 100 parts by weight of the silsesquioxane compound.

[0088] <Additives> The hard coat composition may contain additives such as inorganic pigments, organic pigments, surface modifiers, surface modifiers, plasticizers, dispersants, wetting agents, thickeners, and defoamers. The hard coat composition may also contain thermoplastic or thermosetting resin materials other than the silsesquioxane compounds mentioned above. If the silsesquioxane compounds and / or resin materials other than the silsesquioxane compounds are radically polymerizable, the hard coat composition may contain a radical polymerization initiator in addition to the cationic polymerization initiator.

[0089] [Hard coat film] A hard coat film is obtained by applying a hard coat composition onto a resin substrate, drying and removing the solvent as necessary, and then curing the hard coat composition by irradiation with active energy rays. The hard coat layer may be formed on only one main surface of the resin substrate, or on both main surfaces of the resin substrate.

[0090] <Resin substrate> The resin substrate is a film substrate that serves as the base for forming the hard coat layer. The resin substrate is preferably transparent, and its total light transmittance is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The haze of the resin substrate is preferably 2% or less, and more preferably 1% or less.

[0091] The thickness of the resin substrate is not particularly limited, for example, 1 to 1000 μm, preferably 5 to 500 μm, more preferably 10 to 200 μm, and even more preferably 15 to 150 μm.

[0092] The resin material constituting the resin substrate is preferably a transparent resin. Examples of transparent resins include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate, polyamide, transparent polyimide, cyclic polyolefin, acrylic resins such as polymethyl methacrylate (PMMA), and cellulosic resins such as triacetylcellulose (TAC).

[0093] Among these, polyesters such as PET and transparent polyimides are preferred due to their high mechanical strength. When hard coat films are used as cover windows for displays, the film substrate requires excellent heat resistance and mechanical strength, so transparent polyimides are particularly preferred as the resin material for the resin substrate. While general all-aromatic polyimides are colored yellow or brown, transparent polyimides with high visible light transmittance can be obtained by introducing alicyclic structures, bent structures, fluorine substituents, etc.

[0094] The resin substrate may be a single layer or a multilayer structure. For example, the resin substrate may be a laminate formed by bonding multiple films together, and functional layers such as an easy-adhesion layer, an antistatic layer, or an anti-reflective layer may be provided on the hard coat layer-forming surface and / or the non-hard coat layer-forming surface of the film substrate. Furthermore, the resin substrate may have a hard coat layer formed of a material other than the silsesquioxane compound on one of its main surfaces.

[0095] <Formation of the hard coat layer> As described above, a hard coat layer is formed by applying a hard coat composition onto a resin substrate and curing it. Before applying the hard coat composition, the surface of the resin substrate may be subjected to surface treatment such as corona treatment or plasma treatment. Alternatively, an easy-adhesion layer (primer layer) may be provided on the surface of the resin substrate. However, since the hard coat layer formed by curing the hard coat composition containing the silsesquioxane compound exhibits high adhesion to the resin substrate, it is not necessary to provide an easy-adhesion layer. In other words, the hard coat film may be in contact with the resin substrate.

[0096] When a hard coat composition is irradiated with active energy rays or heated, an acid is generated from the cationic polymerization initiator, and the epoxy groups of the silsesquioxane compound undergo ring-opening and cationic polymerization, causing curing to proceed. If the hard coat composition contains a reactive additive, in addition to the polymerization reaction between the silsesquioxane compounds, a polymerization reaction also occurs between the epoxy groups of the silsesquioxane compound and the reactive additive. Furthermore, if the hard coat composition contains particles having reactive functional groups on their surface, the functional groups on the particle surface may react with the epoxy groups of the silsesquioxane compound to form chemical crosslinks.

[0097] Examples of active energy rays used during photocuring include visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, gamma rays, and electron beams. Ultraviolet light is preferred as the active energy ray due to its high curing reaction rate and excellent energy efficiency. The cumulative irradiation dose of the active energy ray is, for example, 50 to 10,000 mJ / cm². 2 The curing temperature is approximate and should be set according to the type and amount of photocationic polymerization initiator, the thickness of the hard coat layer, etc. The curing temperature is not particularly limited, but is usually 150°C or lower.

[0098] The thickness of the hard coat layer is preferably 0.5 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, particularly preferably 5 μm or more, and may be 10 μm or more, 20 μm or more, or 30 μm or more. The greater the thickness of the hard coat layer, the higher the surface hardness tends to be. On the other hand, from the viewpoint of transparency and flexibility, the thickness of the hard coat layer is preferably 100 μm or less, more preferably 80 μm or less, and may be 70 μm or less.

[0099] The total thickness of the hard coat film is, for example, 1 to 1000 μm, preferably 10 to 500 μm, more preferably 15 to 250 μm, and even more preferably 20 to 200 μm. The ratio of the thickness of the hard coat layer to the thickness of the resin substrate in the hard coat film (hard coat layer thickness / resin substrate thickness) is not particularly limited and can be appropriately selected from, for example, between 1 / 10 and 10 / 1.

[0100] [Characteristics of hard coat film] The hard coat layer formed by curing the above hard coat composition exhibits excellent adhesion to the resin substrate. Furthermore, because the hard coat composition has a polymer matrix in which silsesquioxane compounds are crosslinked by ring-opening and polymerization reactions of epoxy groups, it can achieve a surface hardness comparable to that of glass. The surface hardness (pencil hardness) of the hard coat layer-forming surface of the hard coat film is preferably HB or higher, more preferably H or higher, even more preferably 2H or higher, and may be 3H or higher or 4H or higher.

[0101] As described above, the hard coat film has high surface hardness and excellent flexibility. When a cylindrical mandrel test is performed with the hard coat layer facing outwards, it is preferable that the diameter φ of the mandrel at which cracks occur in the hard coat layer is small. If the thickness of the hard coat layer is the same, the smaller the mandrel diameter, the better the flexibility. For example, when the thickness of the hard coat layer is 10 μm, the diameter of the mandrel at which cracks occur in the hard coat layer is preferably 8 mm or less, more preferably 6 mm or less, and may also be 4 mm or less, or 2 mm or less. When the hard coat layer is formed using the same material, the mandrel diameter φ tends to increase as the thickness of the hard coat layer increases.

[0102] The total light transmittance of the hard coat film is preferably 80% or higher, more preferably 85% or higher, and even more preferably 88% or higher. The haze of the hard coat film is preferably 1.5% or lower, more preferably 0.9% or lower, even more preferably 0.7% or lower, and particularly preferably 0.5% or lower.

[0103] When a humid heat test is performed on a hard coat film by leaving it undisturbed in an environment of 60°C and 90% humidity for 24 hours, the change in haze (ΔHaze) is preferably 0.3% or less, more preferably 0.2% or less, and even more preferably 0.1% or less.

[0104] [Applications of hard coat films] The hard coat film may have various functional layers on the hard coat layer or on the non-hard coat surface of the resin substrate. Examples of functional layers include anti-reflective layers, anti-glare layers, anti-static layers, and transparent electrodes. The hard coat film may also have a transparent adhesive layer attached to it.

[0105] The hard coat film of the present invention has high transparency and excellent mechanical strength, making it suitable for use as a cover window on the surface of an image display panel, as well as for transparent substrates for displays, transparent substrates for touch panels, and substrates for solar cells. In addition to transparency and mechanical strength, the hard coat film of the present invention also has excellent flexibility, making it particularly suitable for use as a cover window or substrate film for curved displays and flexible displays. [Examples]

[0106] Below are silsesquioxane compounds and hard coat to The present invention will be described in more detail with reference to examples of film manufacturing, but the present invention is not limited to the following examples.

[0107] [Synthesis of silsesquioxane compounds (condensates of silane compounds)] <Synthesis Example 1> In a reaction vessel equipped with a thermometer, stirrer, and reflux condenser, 66.5 g (270 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Momentive Performance Materials "SILQUEST A-186") and 16.5 g of 1-methoxy-2-propanol (PGME) were charged and mixed uniformly. To this mixture, 0.039 g (0.405 mmol) of magnesium chloride, used as a catalyst, was dissolved in a mixture of 9.7 g (539 mmol) of water and 5.8 g of methanol, and this solution was added dropwise over 5 minutes, while mixing until homogeneous. The temperature was then raised to 80°C, and the polycondensation reaction was carried out for 6 hours with stirring. After the reaction was complete, the solvent and water were removed by distillation using a rotary evaporator to obtain silsesquioxane compound 1.

[0108] Measurements were taken using a Bruker NMR spectrometer (400 MHz) with deuterated acetone as the solvent. 1 From the 1H-NMR spectrum, it was confirmed that the epoxy group retention rate of silsesquioxane compound 1 was 95% or higher. Based on the amount used, the remaining amount of magnesium chloride (neutral salt catalyst) in silsesquioxane compound 1 was calculated to be 814 ppm.

[0109] <Synthesis Example 2> Except for using 0.50 g (1.56 mmol) of tetrabutylammonium bromide (TBAB) instead of magnesium chloride as a catalyst, the polycondensation reaction of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was carried out in the same manner as in Synthesis Example 1 to obtain silsesquioxane compound 2.

[0110] <Synthesis Example 3> In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 66.5 g (270 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 7.3 g (405 mmol) of water were charged and mixed uniformly. To this mixture, 0.13 ml of a 25 wt% aqueous ammonia solution (1.7 mmol as ammonia) was added dropwise over 5 minutes as a catalyst, and the mixture was mixed until homogeneous. Thereafter, the polycondensation reaction and removal of volatile components were carried out in the same manner as in Synthesis Example 1 to obtain silsesquioxane compound 3.

[0111] <Synthesis Example 4> In a reaction vessel equipped with a thermometer, stirrer, and reflux condenser, 39.8 g (162 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 1.69 g (9 mmol) of phenyltrimethoxysilane, and 166 g of dioxane were charged and mixed uniformly. To this mixture, 4.7 g (1.7 mmol as potassium carbonate) of a 5% aqueous potassium carbonate solution was added dropwise over 5 minutes as a catalyst, followed by the dropwise addition of 15.3 g (850 mmol) of water, and the mixture was mixed until uniform. The temperature was then raised to 70°C, and the polycondensation reaction was carried out for 2 hours with stirring. After the reaction was complete, volatile components were removed using a rotary evaporator to obtain silsesquioxane compound 4.

[0112] <Synthesis Example 5> In a reaction vessel equipped with a thermometer, a stirring device, and a reflux condenser, 19.7 g (80.2 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 23.8 g (120 mmol) of phenyltrimethoxysilane, and 174 g of dioxane were charged and stirred uniformly. Thereafter, in the same manner as in Synthesis Example 4, a polycondensation reaction and distillation of volatile components were carried out to obtain silsesquioxane compound 5.

[0113] [Evaluation of Compounds] For the silsesquioxane compounds 1 to 5 obtained in Synthesis Examples 1 to 5, the number average molecular weight Mn and the T3 / T2 ratio were measured by the following method.

[0114] [Number average molecular weight Mn] Using a GPC apparatus "HLC-8220GPC" manufactured by Tosoh Corporation (columns: TSKgel GMHXL × 2, TSKgel G3000HXL, TSKgel G2000HXL), measurement was carried out using THF as a solvent, and the number average molecular weight in terms of polystyrene was calculated.

[0115] [T3 / T2 ratio] Using an NMR (600 MHz) manufactured by Agilent, 29 Si-NMR spectrum was measured, and the ratio T3 / T2 (molar ratio) of the SiO 3 / 2 body (T3 body) to the SiO 2 / 2 body (T2 body) was determined.

[0116] The molar ratios of the raw materials (silane compounds) in Synthesis Examples 1 to 5, the types of catalysts, and the evaluation results (T3 / T2 ratio and number average molecular weight Mn) of the silsesquioxane compounds are shown in Table 1.

[0117] [Table 1]

[0118] In Synthesis Example 1, which used magnesium chloride as a neutral salt catalyst, the silsesquioxane compound had a T3 / T2 ratio of less than 5, whereas in Synthesis Examples 2-4, which used a basic catalyst, the T3 / T2 ratio of the silsesquioxane compound exceeded 5. In Synthesis Example 5, where the proportion of phenyltrimethoxysilane, a silane compound that does not contain an alicyclic epoxy group, was high, the T3 / T2 ratio of the silsesquioxane compound was below 0.8. This shows that by using a neutral salt catalyst to carry out the condensation reaction of a silane compound containing an alicyclic epoxy group, a silsesquioxane compound with a T3 isomer ratio within a predetermined range can be obtained.

[0119] [Preparation of hard coat compositions and fabrication of hard coat films] <Example 1> (Preparation of hard coat composition) A hard coat composition was obtained by adding 1 part by weight (on a solid content basis) of a 50% propylene carbonate solution of diphenyl(4-phenylthiophenyl)sulfonium·SbF6 (SunApro "CPI-101A") as a photocationic polymerization initiator to silsesquioxane compound 1 (100 parts by weight) obtained in Synthesis Example 1.

[0120] (Preparation of hard coat film) The hard coat composition described above was applied to one side of a transparent polyimide film (50 μm thick) according to Example 12 of WO2020 / 004236 using a bar coater to a film thickness of 10 μm after heating, and then heated at 120°C for 10 minutes. Subsequently, a high-pressure mercury lamp was used to heat the film to an integrated light intensity of 1000 mJ / cm² at a wavelength of 365 nm. 2 The film was irradiated with ultraviolet light to achieve the desired result. Subsequently, it was heat-treated at 80°C for 2 hours to obtain a hard-coated film having a 10 μm thick hard-coat layer on one side of the transparent polyimide film.

[0121] <Comparative Examples 1-5> In preparing the hard coat composition, silsesquioxane compounds 2-5 were used instead of silsesquioxane compound 1, and the thickness of the hard coat layer was changed as shown in Table 2. Otherwise, the hard coat film was prepared in the same manner as in Example 1.

[0122] <Examples 2-7> In preparing the hard coat composition, the amount of photocationic polymerization initiator added was changed as shown in Table 2, and 0.5 parts by weight of polyether-modified polydimethylsiloxane (BYK-300, manufactured by BYK) was added as a leveling agent. The thickness of the hard coat layer was also changed as shown in Table 2. Except for these changes, the hard coat film was prepared in the same manner as in Example 1.

[0123] [Evaluation of hard coat film] The hard coat film described above was evaluated using the following method.

[0124] <Surface hardness (pencil hardness)> In accordance with JIS K5600-5-4:1999, the pencil hardness of the hard coat layer surface was measured under a load of 750g.

[0125] <Flexural resistance (cylindrical madrel test)> In accordance with JIS K5600-5-1:1999, a cylindrical mandrel test was performed using a Type 1 testing machine with the hard coat layer facing outwards. 。

[0126] Table 2 shows the composition of the hard coat composition used to prepare the hard coat films of Examples 1-7 and Comparative Examples 1-5 (type of silsesquioxane compound and its T3 / T2 ratio, as well as the amount of polymerization initiator and leveling agent), the thickness of the hard coat layer, and the evaluation results of the hard coat film. In Table 2, the composition is expressed in parts by weight as the amount (solid content) of polymerization initiator and leveling agent per 100 parts by weight of silsesquioxane compound.

[0127] [Table 2]

[0128] Silces with a T3 / T2 ratio exceeding 5 tree The hard coat films of Comparative Examples 1-3, using oxane compounds 2-4, exhibited excellent surface hardness, but the mandrel diameter φ was 10 mm or more when the hard coat layer thickness was 10 μm (or less), resulting in insufficient flexibility. In Comparative Example 4, where the hard coat layer thickness was increased, the surface hardness was improved compared to Comparative Example 3, but the mandrel diameter φ was even larger. Silces with a small T3 / T2 ratio tree The hard coat film of Comparative Example 5, which used oxane compound 5, had a mandrel diameter of φ6 mm and excellent flexibility, but its pencil hardness was low at B, indicating insufficient surface hardness as a hard coat layer.

[0129] Silces with a T3 / T2 ratio of 2.3 tree The hard coat film of Example 1 using oxane compound 1 exhibited excellent surface hardness and flexibility. In a comparison between Example 1 and Examples 2-7, there was a tendency for pencil hardness to improve as the thickness of the hard coat layer increased. Furthermore, there was a tendency for the mandrel diameter to increase with increasing hard coat layer thickness. In Example 7, with a hard coat layer thickness of 37 μm, the mandrel diameter exceeded 10 mm. However, compared to Comparative Example 4, Example 7 exhibited high surface hardness and a small mandrel diameter (i.e., high flexibility), suggesting that Silces has a T3 / T2 ratio of 5 or higher. tree Compared to oxane compounds, it is possible to form a hard coat layer with higher hardness and superior flexibility.

[0130] <Examples 8-18> A hard coat film was prepared in the same manner as in Example 1, except that the composition of the hard coat composition and the thickness of the hard coat layer were changed as shown in Table 3, using silsesquioxane compound 1. The surface hardness and flexural resistance of the obtained hard coat films were evaluated. For the hard coat films of Examples 13 to 18, the water contact angle was also measured before and after the steel wool test described below.

[0131] (Water contact angle before and after steel wool test) The water contact angle (initial value) of the hard coat layer of the hard coat film was measured using the droplet method, with the hard coat layer facing upwards. A reciprocating abrasion tester (Heidon Type 30) was used, with a 500g load applied to steel wool #0000, and the friction area measured was 4.5 cm². 2 After conducting a steel wool test by moving it back and forth 500 times over the hard coat layer, the water contact angle was measured again.

[0132] Table 3 shows the composition of the hard coat composition used to prepare the hard coat films in Examples 8 to 18, the thickness of the hard coat layer, and the evaluation results of the hard coat films. Table 3 also shows the evaluation results for Examples 1 and 5. The composition in Table 3 is shown in parts by weight of the solid content (based on a total resin content of 100 parts by weight).

[0133] Details of the reactive additives and leveling agents in Table 3 are as follows. (Reactive additives) EEC: 3',4'-Epoxycyclohexylmethyl 3,4-Epoxycyclohexanecarboxylate (Daicel Chemical Industries, Ltd. "Celoxide 2021P") PEGDGE: Polyethylene glycol (n=22) diglycidyl ether (Nagase ChemteX "Denacol EX-861") SG-P3: Methyl ethyl ketone solution of epoxy group-containing acrylic ester polymer (Nagase Chemtex "Teisan Resin SG-P3"; weight-average molecular weight 850,000, epoxy value 0.21 eq / kg) ECMA: (3,4-Epoxycyclohexyl)methyl acrylate (Leveling agent) BYK-300: Polyether-modified polydimethylsiloxane (BYK's "BYK-300") RS-75: Perfluoropolyether-based surface modifier (DIC's "Megafac RS-75") RS-90: Perfluoropolyether-based surface modifier (DIC's "Megafac RS-90")

[0134] [Table 3]

[0135] Examples 8-12, which included cationic polymerizable reactive additives, exhibited excellent surface hardness and flexural resistance, similar to Examples 1-7. Examples 5, 13-18, which included leveling agents, showed a larger water contact angle and superior stain resistance compared to Example 1, which did not include a leveling agent. In particular, Examples 13-18, which included fluorine-based leveling agents, showed a large initial water contact angle and maintained a high contact angle even after steel wool testing, indicating excellent stain resistance as well as superior scratch resistance.

Claims

1. A hard coat film comprising a hard coat layer made of a cured product of a hard coat composition on at least one main surface of a transparent resin substrate, The pencil hardness of the hard coat layer is 2H or higher. The transparent resin substrate contains polyimide resin, The hard coat composition comprises a silsesquioxane compound and a photocationic polymerization initiator. The silsesquioxane compound is It is a condensate of a silane compound represented by general formula (A), R ａ -(Si(OR ２ ) ｘ R ３ ３－ｘ ) …(A) The number-average molecular weight is 500 to 20,000. It includes the T3 isomer represented by general formula (3) and the T2 isomer represented by general formula (4), [R ａ SiO ３／２ ] …(3) [R ａ SiO ２／２ -Z] …(4) The ratio of T3 to T2 content, T3 / T2, is 0.8 or more and less than 5. The structure includes the structure represented by general formula (5), [R １ -Si] …(5) The ratio of the number of Si atoms in the structure represented by the general formula (5) to the total number of Si atoms is 0.2 to 1.

0. In general formula (A), R ２ R is a hydrogen atom or an alkyl group, ３ x is a hydrogen atom, or a monovalent hydrocarbon group selected from the group consisting of alkyl groups, aryl groups, and aralkyl groups, where x is an integer from 1 to 3; In general formulas (A), (3), and (4), R ａ This is a monovalent organic group having a carbon atom bonded to a Si atom, and is a group containing an alicyclic epoxy group, a group containing a glycidyl group, a group containing an oxetanyl group, a group containing a substituted or unsubstituted double bond, a group containing a substituted or unsubstituted cycloalkyl group, a group containing a substituted or unsubstituted aromatic ring, or a substituted or unsubstituted alkyl group; In general formula (4), Z is a hydroxyl group or an alkoxy group; In general formula (5), R １ It is an organic group containing an alicyclic epoxy group, The silane compound represented by general formula (A) has a ratio of x=3 to the total of x=1, x=2, and x=3, which is 0.9 or greater. The hard coat composition contains a neutral salt, which is a catalyst for the hydrolysis condensation reaction of the silane compound, in an amount of 1 ppm to 10,000 ppm based on the silsesquioxane compound. Hard coat film.

2. The hard coat film according to claim 1, wherein the neutral salt is a salt comprising a combination of an ion of an element selected from the group consisting of alkali metal elements and group 2 elements, and a halide ion selected from the group consisting of chloride ions, bromide ions, and iodide ions.

3. The hard coat film according to claim 1 or 2, wherein the thickness of the hard coat layer is 0.5 to 100 μm.

4. A method for producing a hard coat film according to any one of claims 1 to 3, A method for producing a hard coat film, comprising applying the hard coat composition onto a transparent resin substrate containing polyimide resin, and curing the hard coat composition by irradiating it with active energy rays to form the hard coat layer.

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