Hard coat film and method for manufacturing the same, and display

Abstract

A hardcoat film (11) is equipped with a hardcoat layer which contains a cured article of a silsesquioxane compound and is located on one or more main surfaces of a resin film (1). The silsesquioxane compound contains a structure represented by general formula (5) and a structure represented by general formula (6), the ratio of the structure represented by general formula (5) to the total amount of Si atoms is 0.2-0.95, and the ratio of the structure represented by general formula (5) to the total amount of the structure represented by general formula (5) and the structure represented by general formula (6) is greater than 0.4. Z represents an organic group containing an alicyclic epoxy group in general formula (5), and in general formula (6), R4 represents a divalent organic group, the main chain of which has a carbon number of 4-16, and Y represents a glycidyloxy group.　(5): [Z-Si]; (6): [Y-R4-Si]

Description

Technical Field

[0001] The present invention relates to a hard coat film and a method for manufacturing the same. Further, the present invention relates to a display provided with the hard coat film.

Background Art

[0002] Curved displays and foldable displays (flexible displays, foldable displays) have been developed, and there has been a consideration to replace the glass materials that have been used for cover windows, substrates, etc. of displays with plastic film materials having excellent flexibility. Cover windows of flexible displays including foldable displays require various properties such as transparency, hardness, and bending resistance.

[0003] Patent Documents 1 to 3 disclose polysiloxane-based hard coat materials containing a silsesquioxane compound having an epoxy group as a curable resin component.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Foldable displays come in two types: those that fold with the display surface facing inward, and those that fold with the display surface facing outward. When a hard coat film is used as a cover window for a foldable display of the type that folds with the display surface facing outward, the hard coat film is bent so that the hard coat layer surface faces outward when the device is folded.

[0006] As disclosed in Patent Document 1, a hard coat film using a polysiloxane compound having an alicyclic epoxy group as a curable resin component is prone to cracking in the hard coat layer when bent so that the hard coat layer faces outward, and does not have sufficient bending resistance.

[0007] Patent Document 2 describes an example of preparing a hard coat material using a polysiloxane compound having glycidyl groups as the curable resin component, in addition to a hard coat material using a polysiloxane compound having alicyclic epoxy groups as the curable resin component. The cured film (hard coat layer) of the polysiloxane compound having glycidyl groups can exhibit superior flexural resistance compared to the cured film of the polysiloxane compound having alicyclic epoxy groups. However, the cured film of the polysiloxane compound having glycidyl groups does not have sufficient surface hardness.

[0008] Patent Document 3 describes a hard coat film using a siloxane compound obtained by co-condensing a silane compound having an alicyclic epoxy group with a silane compound having a glycidyl group, but neither the surface hardness nor the flexibility of the hard coat layer is considered sufficient.

[0009] In view of the above, the present invention aims to provide a hard coat film that can achieve both excellent surface hardness and flexibility. [Means for solving the problem]

[0010] A hard coat film according to one embodiment of the present invention comprises a hard coat layer containing a cured silsesquioxane compound on at least one main surface of a resin film. The resin film may be a transparent polyimide film.

[0011] In one embodiment of the present invention, a hard coat film is formed by applying a hard coat composition containing a silsesquioxane compound onto a resin film and curing it by irradiation with active energy rays to form a hard coat layer.

[0012] The hard coat film may have a top coat layer on top of the hard coat layer. The top coat layer may contain a fluorine compound. For example, the top coat layer is formed by applying a composition containing a compound having an alkoxysilyl group and a perfluoroalkyl group in its molecule onto the hard coat layer and condensing the compound.

[0013] Silsesquioxane compounds, which are curable resin components of hard coat materials, include structures represented by general formula (5) and general formula (6). [Z-Si] …(5) [YR 4 -Si] …(6)

[0014] In general formula (5), Z is an organic group containing an alicyclic epoxy group. In general formula (6), R 4 A is a divalent organic group with 4 to 16 atoms in its main chain, and Y is a glycidyloxy group.

[0015] The silsesquioxane compound has a ratio of the structure represented by general formula (5) to the total amount of Si atoms of 0.2 to 0.95. Preferably, the silsesquioxane compound has a ratio of the structure represented by general formula (6) to the total amount of Si atoms of 0.05 or more and less than 0.6.

[0016] In silsesquioxane compounds, the ratio of the structure represented by general formula (5) to the total of the structures represented by general formula (6) is greater than 0.4. Preferably, the ratio of the structure represented by general formula (5) to the total of the structures represented by general formula (6) is 0.95 or less.

[0017] The hard coat film may have hard coat layers on both sides of the resin film. In the case of a hard coat film having hard coat layers on both sides of the resin film, it is sufficient that at least one of the hard coat layers contains a cured product of the silsesquioxane compound described above. [Effects of the Invention]

[0018] The hard coat film of the present invention achieves both excellent surface hardness and flexibility, and can be suitably used as a cover window material for foldable displays that are folded so that the display surface faces outward. [Brief explanation of the drawing]

[0019] [Figure 1] This is a cross-sectional view of a hard coat film according to one embodiment. [Figure 2] This is a cross-sectional view of a hard coat film according to one embodiment. [Figure 3] This is a cross-sectional view of a hard coat film according to one embodiment. [Figure 4] This is a cross-sectional view of a hard coat film according to one embodiment. [Modes for carrying out the invention]

[0020] Figure 1 is a cross-sectional view of a hard coat film according to one embodiment of the present invention. The hard coat film 11 comprises a hard coat layer 3 on one main surface of a resin film 1. The hard coat layer 3 is a polysiloxane-based resin cured product layer containing a cured product of a silsesquioxane compound. As shown in Figures 2 and 4, the hard coat film may comprise hard coat layers 3 and 4 on both sides of the resin film 1. As shown in Figures 3 and 4, the hard coat film may comprise a top coat layer 5 on the hard coat layer 3.

[0021] [Resin film] The resin film 1 is a resin substrate that serves as the base for forming the hard coat layer 3. The resin film 1 is preferably transparent. The total light transmittance of the resin film 1 is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The haze of the resin film 1 is preferably 2% or less, and more preferably 1% or less.

[0022] The thickness of the resin film 1 is, for example, about 1 to 1000 μm. Preferably, the thickness of the resin film 1 is 5 to 500 μm, more preferably 10 to 200 μm, and even more preferably 15 to 150 μm. If the thickness is too small, the hardness will be insufficient, and if the thickness is too large, the flexibility will tend to be poor.

[0023] Examples of resin materials that make up the resin film 1 include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins such as polymethyl methacrylate (PMMA), cellulose resins such as triacetylcellulose (TAC), polycarbonate, polyamide, transparent polyimide, and cyclic polyolefin.

[0024] Among these, polyesters such as PET, cellulose-based resins such as TAC, and polyimides are preferred as resin materials due to their excellent transparency and mechanical strength. When hard coat films are used as cover windows for displays, the film substrate is required to have excellent heat resistance and mechanical strength, so transparent polyimides are particularly preferred as the resin material for the resin film. 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.

[0025] The resin film 1 may contain two or more resin materials. The resin film may also contain stabilizers such as UV absorbers and radical trapping agents for the purpose of providing weather resistance, and dyes and pigments such as bluing agents for the purpose of adjusting the color tone.

[0026] The resin film 1 may be a single layer or a multilayer structure. For example, the resin film 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 surface of the film (the surface where the hard coat layer 3 is formed and / or the surface where the hard coat layer is not formed).

[0027] The thickness of the resin film 1 is not particularly limited and can be appropriately selected from, for example, a range of 1 to 1000 μm, preferably 5 to 500 μm, more preferably 10 to 200 μm, and even more preferably 15 to 150 μm.

[0028] [Hard coat layer] A hard coat layer 3 is formed by applying a hard coat composition onto a resin film 1 and curing it. The hard coat composition used to form the hard coat layer 3 contains a silsesquioxane compound as a curable resin component.

[0029] <Silsesquioxane compound> The silsesquioxane compounds contained in the hard coat composition are condensates of silane compounds represented by general formula (A). R a -(Si(OR 2 ) x R 3 3-x ) …(A)

[0030] 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, and R a is an arbitrary monovalent organic group. x is an integer from 1 to 3.

[0031] The silsesquioxane compound contained in the hard coat composition is a condensate of a silane compound and contains a structure represented by general formula (5) and a structure represented by general formula (6). [Z-Si] …(5) [Y-R 4 -Si] …(6)

[0032] In general formula (5), Z is an organic group containing an alicyclic epoxy group. In general formula (6), R 4 is a divalent organic group having 4 to 16 carbon atoms in the main chain, and Y is a glycidyloxy group represented by the following formula.

[0033]

Chemical formula

[0035] In general formulas (1) and (2), R 2 and R 3 R in general formula (A) 2 and R 3 It is the same as in general formula (1). Z in general formula (1) is the same as Z in general formula (5), and Y and R in general formula (2) 4 These are Y and R in general formula (6). 4 It is similar to that.

[0036] (Silane compounds) Silane compounds represented by general formula (A), general formula (1), and general formula (2) contain 1 to 3 (-OR) molecules per molecule. 2 ) has Si-OR 2 It is hydrolyzable. Therefore, silsesquioxane compounds can be obtained by condensation of silane compounds.

[0037] R in general formula (A), general formula (1), and general formula (2) 2 R is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. From the viewpoint of hydrolysis, 2 The alkyl group is preferably one with 3 or fewer carbon atoms, and is particularly preferably a methyl group.

[0038] R in general formula (A), general formula (1), and general formula (2) 3 Preferably, the hydrocarbon group is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 25 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms. Specific examples of hydrocarbon groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isopropyl, isobutyl, cyclohexyl, ethylhexyl, benzyl, phenyl, tolyl, xylyl, naphthyl, and phenethyl groups.

[0039] In general formula (A), general formula (1), and general formula (2), x is preferably 2 or 3. When x=3 (i.e., three alkoxy groups (or hydroxyl groups) on the Si atom - OR 2 (When bonded), the silane compound R 3 It does not have [the specified characteristic]. From the viewpoint of improving hardness by forming a network-like silsesquioxane compound and improving the curing speed by increasing the number of epoxy groups contained in the silsesquioxane compound, it is preferable that x = 3. 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.

[0040] In general formulas (1) and (5), Z is an organic group containing an alicyclic epoxy group, preferably an alkyl group having an alicyclic epoxy group as a substituent. The alicyclic epoxy group is preferably 3,4-epoxycyclohexyl. When Z is an alkyl group having an alicyclic epoxy group as a substituent, the number of carbon atoms in the alkyl group is preferably 16 or less, more preferably 12 or less, even more preferably 10 or less, and particularly preferably 1 to 5.

[0041] Silsesquioxane compounds obtained by condensation of silane compounds containing alicyclic epoxy groups retain their alicyclic structure even after curing by ring-opening polymerization of the epoxy group. Therefore, the reduction in molecular volume due to curing is minimal, and in fact, the volume tends to increase during curing. As a result, curing shrinkage is less likely to occur, which can contribute to suppressing curl in hard coat films. Furthermore, because the alicyclic structure is more rigid than the chain structure, the hardness of the hard coat layer tends to improve. Consequently, the higher the proportion of the silane compound represented by general formula (1) used in the synthesis of the silsesquioxane compound, the higher the hardness of the hard coat layer and the less curl the hard coat film tends to have.

[0042] Specific examples of silane compounds represented by general formula (1) include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 3-(3,4-epoxycyclohexyl)propylmethyldimethoxysilane, 4-(3,4-epoxycyclohexyl)butyltrimethoxysilane, 4-(3,4-epoxycyclohexyl)butylmethyldimethoxysilane, 5-(3,4-epoxycyclohexyl)pentyltrimethoxysilane, and 5-(3,4-epoxycyclohexyl)pentylmethyldimethoxysilane.

[0043] R in general formulas (2) and (6) 4 R is a divalent organic group with 4 to 16 atoms in its main chain. 4 The chain may be linear or branched. The number of atoms in the main chain refers to the number of atoms that make up the linear chain connecting the Si atom and the oxygen atom of the glycidyloxy group Y in general formulas (2) and (6). In other words, the silane compounds of general formula (2) are compounds in which the Si atom and the glycidyloxy group Y are bonded to each other via 4 to 16 atoms.

[0044] R 4 This may be a linear or branched alkylene group, and the main chain may contain atoms other than carbon. For example, R 4 This may include heteroalkylene groups, ether bonds, ester bonds, amide bonds, carbonyl groups, imino groups, etc.

[0045] R 4 When it is a linear alkylene group, specific examples include tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, decamethylene group, dodecamethylene group, tetradecamethylene group, hexadecamethylene group, etc. 4The linear alkylene may have some or all of the hydrogen atoms of the methylene (-CH2-) group that constitutes it replaced by substituents. Specific examples of substituents include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, phenyl, amino, (meth)acrylic, halogen, allyl, vinyl, mercapto, carboxyl, nitro, sulfone, and hydroxyl groups.

[0046] Silsesquioxane compounds obtained by the condensation of silane compounds represented by general formula (2) consist of an epoxy group, which is a polymerizable functional group, and an organic group R having a specific chain length between it and the Si atom. 4 Because of the presence of the organic spacer R, the molecular structure remains flexible even after hardening due to the reaction of the epoxy group. Therefore, the hard coat layer composed of the cured product of the silsesquioxane compound exhibits excellent flexibility (bending resistance). The greater the distance between the Si atom and the epoxy group, the more flexible the organic spacer R is. 4 The larger the number of atoms constituting the main chain and the longer the chain length, the more the bending resistance of the hard coat layer 3 tends to improve. As described above, R 4 The number of atoms in the main chain is 4 or more, preferably 6 or more, and may be 8 or more. On the other hand, R 4 If the number of atoms in the main chain is excessively large, the hardness of the hard coat layer tends to be insufficient. Therefore, R 4 The number of atoms in the main chain is 16 or less, preferably 14 or less, more preferably 12 or less, and may be 10 or less.

[0047] Specific examples of silane compounds represented by general formula (2) include 4-glycidyloxybutyltrimethoxysilane, 4-glycidyloxybutylmethyldimethoxysilane, 4-glycidyloxybutyltriethoxysilane, 4-glycidyloxybutylmethyldiethoxysilane, 5-glycidyloxypentyltrimethoxysilane, 5-glycidyloxypentylmethyldimethoxysilane, 5-glycidyloxypentyltriethoxysilane, 5-glycidyloxypentylmethyldiethoxysilane, 6-glycidyloxyhexyltrimethoxysilane, 6-Glycidyloxyhexylmethyldimethoxysilane, 6-Glycidyloxyhexyltriethoxysilane, 6-Glycidyloxyhexylmethyldiethoxysilane, 7-Glycidyloxyheptyltrimethoxysilane, 7-Glycidyloxyheptylmethyldimethoxysilane, 7-Glycidyloxyheptyltriethoxysilane, 7-Glycidyloxyheptylmethyldiethoxysilane, 8-Glycidyloxyoctyltrimethoxysilane, 8-Glycidyloxyoctylmethyldimethoxysilane, 8-Glycidyloxyoctyltriethoxy Silane, 8-Glycidyloxyoctylmethyldiethoxysilane, 9-Glycidyloxynonyltrimethoxysilane, 9-Glycidyloxynonylmethyldimethoxysilane, 9-Glycidyloxynonyltriethoxysilane, 9-Glycidyloxynonylmethyldiethoxysilane, 10-Glycidyloxydecyltrimethoxysilane, 10-Glycidyloxydecylmethyldimethoxysilane, 10-Glycidyloxydecyltriethoxysilane, 10-Glycidyloxydecylmethyldiethoxysilane, 11-Glycidyloxyundecyltrimeth Xysilane, 11-Glycidyloxyundecylmethyldimethoxysilane, 11-Glycidyloxyundecyltriethoxysilane, 11-Glycidyloxyundecylmethyldiethoxysilane, 12-Glycidyloxidedecyltrimethoxysilane, 12-Glycidyloxidedecylmethyldimethoxysilane, 12-Glycidyloxidedecyltriethoxysilane, 12-Glycidyloxidedecylmethyldiethoxysilane, 13-Glycidyloxytridecyltrimethoxysilane, 13-Glycidyloxytridecylmethyldimethoxysilane,13-Glycidyloxytridecyltriethoxysilane, 13-Glycidyloxytridecylmethyldiethoxysilane, 14-Glycidyloxytetradecyltrimethoxysilane, 14-Glycidyloxytetradecylmethyldimethoxysilane, 14-Glycidyloxytetradecyltriethoxysilane, 14-Glycidyloxytetradecylmethyldiethoxysilane, 15-Glycidyloxypentadecyltrimethoxysilane, 15-Glyci Examples include diloxypentadecylmethyldimethoxysilane, 15-glycidyloxypentadecyltriethoxysilane, 15-glycidyloxypentadecylmethyldiethoxysilane, 16-glycidyloxyhexadecyltrimethoxysilane, 16-glycidyloxyhexadecylmethyldimethoxysilane, 16-glycidyloxyhexadecyltriethoxysilane, and 16-glycidyloxyhexadecylmethyldiethoxysilane.

[0048] As the silane compound, compounds other than the silane compounds represented by general formula (1) and the silane compounds represented by general formula (2) may be used. Such silane compounds are those in general formula (A) with R a However, examples include groups containing substituted or unsubstituted double bonds, groups containing substituted or unsubstituted cycloalkyl groups, groups containing substituted or unsubstituted aromatic rings, groups having substituted or unsubstituted alkyl groups, groups having glycidyl groups, or groups having oxetanyl groups. a Specific examples include vinyl group, allyl group, acryloyloxypropyl group, methacryloyloxypropyl group, cyclopentyl group, cyclohexyl group, benzyl group, phenyl group, tolyl group, xylyl group, naphthyl group, phenethyl group, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isopropyl group, isobutyl group, 3-glycidyloxypropyl group, and the like.

[0049] (Hydrolysis and condensation of silane compounds) By reacting the above silane compounds with water, the Si-OR of the silane compounds is obtained. 2The silane compound undergoes hydrolysis, and the hydrolyzates condense to form a Si-O-Si bond, producing a silane compound condensate (silsesquioxane compound). 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 10 equivalents per 1 equivalent of the base is preferable, 0.5 to 5 equivalents is more preferable, and 1 to 3 equivalents is even 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] From the viewpoint of increasing the hardness of the cured film (hard coat layer), the weight-average molecular weight of the silsesquioxane compound is preferably 500 or higher. Furthermore, from the viewpoint of suppressing volatilization, a weight-average molecular weight of 500 or higher is also preferable. On the other hand, if the molecular weight is excessively high, turbidity may occur due to decreased compatibility with other compositions. Therefore, a weight-average molecular weight of silsesquioxane compound is preferably 20,000 or less. The molecular weight of the silsesquioxane compound can be controlled by selecting the amount of water used in the reaction, the type and amount of catalyst. For example, increasing the amount of water tends to increase the molecular weight.

[0051] From the viewpoint of improving the curing speed and the hardness of the hard coat layer, it is preferable that the silsesquioxane compound has a high epoxy group content. The remaining epoxy group percentage is preferably 40% or more, more preferably 60% or more, even more preferably 80% or more, and may be 90% or more or 95% or more. The remaining epoxy group percentage is 1 This can be calculated by 1H-NMR measurement.

[0052] In the hydrolysis and condensation reactions of silane compounds, it is preferable to carry out the reactions under neutral or basic conditions from the viewpoint of suppressing ring-opening of epoxy groups. 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.

[0053] Silsesquioxane compounds produced by hydrolysis and condensation of silane compounds are silane compounds having a T unit structure with x=3 in general formula (A), general formula (1), and general formula (2), and the three alkoxy groups (Si-OR 2 ) all undergo a condensation reaction to form a structure ("SiO 3 / 2 (referred to as the "T3 form") and a structure in which two of the three alkoxy groups undergo a condensation reaction to form a Si-O-Si bond ("SiO 2 / 2 This may include a "body" or "T2 body".

[0054] Silsesquioxane compounds are SiO 3 / 2 Body (T3 body) and SiO 2 / 2 The molar ratio of the T2 isomer (T3 / T2 ratio) may preferably be less than 5. The T3 / T2 ratio may be 4 or less, 3.5 or less, 3 or less, or 2.5 or less. The T3 / T2 ratio is preferably 0.8 or higher, and may be 1 or higher, 1.5 or higher, or 2 or higher.

[0055] Carrying out the reaction in the presence of a neutral salt catalyst tends to result in a smaller T3 / T2 ratio. Examples of neutral salt catalysts include salts composed of an acid and a base, with salts composed of an alkali metal or alkaline earth metal cation and a halogen anion being preferred. 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.

[0056] When a neutral salt catalyst is used for the hydrolysis and condensation of silane compounds, the neutral salt catalyst may remain in the silsesquioxane compound. The amount of neutral salt remaining in the silsesquioxane compound may be 1 ppm to 10,000 ppm, 50 ppm to 5,000 ppm, or 100 ppm to 1,000 ppm.

[0057] As mentioned above, the silsesquioxane compounds obtained by the condensation of silane compounds include structures represented by general formula (5) and general formula (6).

[0058] From the viewpoint of increasing the hardness of the hard coat layer 3, the ratio of the structure represented by general formula (5) to the total number of Si atoms in the silsesquioxane compound is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably 0.4 or more. On the other hand, from the viewpoint of increasing the flexibility of the hard coat layer when the hard coat film is bent with the hard coat layer 3 forming surface facing outward, the ratio of the structure represented by general formula (5) to the total number of Si atoms in the silsesquioxane compound is preferably 0.95 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0059] From the viewpoint of improving the flexibility of the hard coat layer 3, the ratio of the structure represented by general formula (6) to the total number of Si atoms in the silsesquioxane compound is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. On the other hand, from the viewpoint of reducing the curl of the hard coat film, the ratio of the structure represented by general formula (6) to the total number of Si atoms in the silsesquioxane compound is preferably less than 0.6, more preferably 0.55 or less, and even more preferably 0.5 or less.

[0060] In silsesquioxane compounds, the ratio of the total number of structures represented by general formula (5) and general formula (6) to the total number of Si atoms is preferably 0.4 or more, more preferably 0.6 or more, even more preferably 0.8 or more, and may be 0.9 or more, 0.95 or more, or 1.

[0061] In silsesquioxane compounds, the ratio of the structure represented by general formula (5) to the sum of the structures represented by general formula (6) is preferably greater than 0.4. More preferably, the ratio of the structure represented by general formula (5) to the sum of the structures represented by general formula (6) is 0.45 or higher, and even more preferably 0.5 or higher. The larger the ratio of the structure represented by general formula (5), the higher the hardness of the hard coat layer 3 and the more the curling of the hard coat film tends to be suppressed.

[0062] The inclusion of the structure of general formula (6) tends to improve the flexural resistance of the hard coat layer 3. From the viewpoint of improving the flexural resistance of the hard coat layer when it is bent with the hard coat layer 3 forming surface facing outward, the ratio of the structure represented by general formula (5) to the total of the structures represented by general formula (6) in the silsesquioxane compound is preferably 0.95 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0063] In the hydrolysis and condensation reactions of silane compounds, the -OR in general formula (A) and general formulas (1) and (2) is used. 2 While R is involved in the reaction, other functional groups bonded to the Si atom do not react, except for side reactions such as ring-opening of the epoxy group. Therefore, in silsesquioxane compounds obtained by the condensation of silane compounds, R in general formula (A) is not involved. a (Z in general formula (1), and R in general formula (5)) 4 The structure is preserved (including Z).

[0064] Therefore, the ratio of the structure of general formula (5) to the total number of Si atoms in the silsesquioxane compound is approximately equal to the ratio of the silane compound of general formula (1) to the total amount of the silane compound of general formula (A). Similarly, the ratio of the structure of general formula (6) to the total number of Si atoms in the silsesquioxane compound is approximately equal to the ratio of the silane compound of general formula (2) to the total amount of the silane compound of general formula (A). Furthermore, in the silsesquioxane compound, the ratio of the structure of general formula (5) to the sum of the structures of general formula (6) is approximately equal to the ratio of the silane compound of general formula (1) to the sum of the silane compounds of general formula (1) and general formula (2).

[0065] In other words, by adjusting the charging ratio of the silane compound when synthesizing the silsesquioxane compound, a silsesquioxane compound having the structure represented by general formula (5) and the structure represented by general formula (6) in the above ratios can be obtained. The ratio of the silane compound represented by general formula (1) to the total amount of the silane compound represented by general formula (A) is preferably 0.2 to 0.95, more preferably 0.3 to 0.9, and even more preferably 0.4 to 0.8. The ratio of the silane compound represented by general formula (2) to the total amount of the silane compound represented by general formula (A) is preferably 0.05 or more and less than 0.6, more preferably 0.1 to 0.55, and even more preferably 0.2 to 0.5.

[0066] The ratio of the total amount of silane compounds represented by general formula (1) and general formula (2) to the total amount of silane compounds represented by general formula (A) is preferably 0.4 or higher, more preferably 0.6 or higher, even more preferably 0.8 or higher, and may be 0.9 or higher, 0.95 or higher, or 1.

[0067] The ratio of the silane compound represented by general formula (1) to the total of the silane compounds represented by general formula (2) is preferably greater than 0.4 and 0.95 or less, more preferably between 0.45 and 0.9, and even more preferably between 0.5 and 0.8.

[0068] <Hard coat composition> The hard coat composition contains the above-mentioned silsesquioxane compound as a curable resin component, and further contains a photocationic polymerization initiator. The hard coat composition may further contain leveling agents, reactive diluents, photosensitizers, particles, and other additives as solids (non-volatile components). From the viewpoint of forming a hard coat layer 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 solids (non-volatile components).

[0069] (Photocationic polymerization initiator) A photocationic polymerization initiator is a compound that generates acid upon irradiation with active energy rays (a photoacid generator). The acid generated from the photoacid generator 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 photocationic polymerization initiators include strong acids such as toluenesulfonic acid, antimony hexafluoride, boron tetrafluoride, phosphorus hexafluoride, fluoroalkyl phosphorus fluoride, and fluoroalkyl gallium fluoride; onium salts such as sulfonium salts, ammonium salts, phosphonium salts, iodonium salts, and selenium salts; iron-allene complexes; silanol-metal chelate complexes; sulfonic acid derivatives such as disulfones, disulfonyldiazomethanes, disulfonylmethanes, sulfonylbenzoylmethanes, imidosulfonates, and benzoin sulfonates; and organic halogen compounds. Among these, aromatic sulfonium salts or aromatic iodonium salts are preferred due to their high stability in hard coat compositions.

[0071] 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.

[0072] (Leveling agent) The hard coat composition may contain a leveling agent. Silicone-based leveling agents and fluorine-based leveling agents are preferred. The inclusion of a leveling agent can be expected to reduce the surface tension of the hard coat composition and improve its surface smoothness.

[0073] The leveling agent content in the hard coat composition 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, per 100 parts by weight of the silsesquioxane compound.

[0074] (Reactive diluent) The hard coat composition may contain a reactive diluent. Examples of reactive diluents include cationic polymerizable compounds other than the silsesquioxane compounds mentioned above. For photocationic polymerization, compounds having cationic polymerizable functional groups are used as reactive diluents. Examples of cationic polymerizable functional groups of reactive diluents include epoxy groups, vinyl ether groups, oxetane groups, and alkoxysilyl groups. Among these, those having epoxy groups are preferred as reactive diluents because of their high reactivity with the epoxy groups of silsesquioxane compounds.

[0075] The content of the reactive diluent in the hard coat composition is preferably 100 parts by weight or less, and more preferably 50 parts by weight or less, per 100 parts by weight of the silsesquioxane compound.

[0076] (Photosensitizer) The hard coat composition may contain a photosensitizer for purposes such as improving the photosensitivity of the photocationic polymerization initiator (photoacid generator). The photosensitizer may be either a type that improves the photosensitivity of the photocationic polymerization initiator by absorbing light in wavelength ranges that the photocationic polymerization initiator cannot absorb, or a type that improves the photosensitivity of the photocationic polymerization initiator even though there is no significant difference in the wavelength range absorbed by the photocationic polymerization initiator. For the type of photosensitizer that absorbs light in wavelength ranges that the photocationic polymerization initiator cannot absorb, it is preferable to have a strong absorption in a wavelength range different from the absorption wavelength range of the photocationic polymerization initiator. Examples of photosensitizers include anthracene derivatives, benzophenone derivatives, thioxanthone derivatives, anthraquinone derivatives, benzoin derivatives, and naphthalene derivatives.

[0077] 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 photocationic polymerization initiator.

[0078] (particle) The hard coat composition may contain particles for the purpose of adjusting film properties such as surface hardness and flexibility. The particles may be organic particles, inorganic particles, organic-inorganic composite particles, etc., as appropriate. The particles may be surface-modified, and polymerizable functional groups may be introduced through surface modification.

[0079] 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.

[0080] The particle content in the hard coat composition is preferably 100 parts by weight or less, and more preferably 50 parts by weight or less, per 100 parts by weight of the silsesquioxane compound.

[0081] (solvent) The hard coat composition may be solvent-free or may contain a solvent. If the hard coat composition contains a solvent, it is preferable that the solvent does not dissolve the resin film 1 as the substrate. On the other hand, using a solvent that has enough solubility to swell the resin film may improve the adhesion between the resin film 1 and the hard coat layer 3. 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.

[0082] (Other ingredients) The hard coat composition may contain additives such as inorganic pigments, organic pigments, surface modifiers, surface modifiers, plasticizers, dispersants, wetting agents, thickeners, defoamers, and UV stabilizers. The hard coat composition may also contain thermoplastic, thermosetting, or photocurable 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 a photocationic polymerization initiator.

[0083] <Formation of the hard coat layer> A hard coat layer 3 is formed on the resin film 1 by applying a hard coat composition onto the resin film 1, drying and removing the solvent as necessary, and then curing the hard coat composition by irradiating it with active energy rays.

[0084] Methods for applying the hard coat composition include roll coating such as bar coating, gravure coating, and comma coating; die coating such as slot die coating and fountain die coating; spin coating; spray coating; and dip coating. Before applying the hard coat composition, the surface of the resin film may be subjected to surface treatment such as corona treatment or plasma treatment. Alternatively, an easy-adhesion layer may be provided on the surface of the resin film 1.

[0085] Upon irradiation with active energy rays or heat, an acid is generated from the cationic polymerization initiator, causing ring-opening and cationic polymerization of the epoxy groups of the silsesquioxane compound, leading to curing. If the additives in the hard coat composition, such as reactive diluents or particles, contain epoxy groups, polymerization reactions occur not only between silsesquioxane compounds but also between the silsesquioxane compounds and the additives.

[0086] Ultraviolet light is preferred as the active energy ray. 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 can be set according to the type and amount of photocationic polymerization initiator, the thickness of the film, etc. The curing temperature is not particularly limited, but is usually 150°C or lower, and may be 100°C or lower or 90°C or lower.

[0087] The thickness of the hard coat layer 3 is preferably 0.5 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and particularly preferably 5 μm or more. The thickness of the hard coat layer 3 is preferably 100 μm or less, and more preferably 80 μm or less. The greater the thickness of the hard coat layer, the more the mechanical properties such as surface hardness tend to improve. On the other hand, if the thickness of the hard coat layer is excessively large, the flexibility of the hard coat layer may decrease.

[0088] The total thickness of the resin film 1 and the hard coat layer 3 is preferably 10 to 500 μm, more preferably 15 to 250 μm, and even more preferably 20 to 200 μm. If the thickness is too small, the mechanical strength may be insufficient, and if the thickness is too large, the transparency and flexibility may be insufficient. The ratio of the thickness D1 of the resin film 1 to the thickness D3 of the hard coat layer 3, D3 / D1, is, for example, about 0.01 to 10.

[0089] As shown in Figures 2 and 4, the hard coat film may have the hard coat layer 3 on one side of the resin film 1 and the hard coat layer 4 on the other side. Providing hard coat layers on both sides of the resin film 1 tends to further increase the hardness of the hard coat film. In addition, forming hard coat layers on both sides of the resin film 1 and balancing the stress at the interface between the front and back of the resin film may reduce the curling of the hard coat film.

[0090] When a hard coat film has hard coat layers on both sides, the hard coat layer 3 on one side may be a polysiloxane-based hard coat layer having the above composition, and the composition of the hard coat layer 4 on the other side is not particularly limited. The hard coat layer 4 may be a polysiloxane-based hard coat layer, or it may be a cured composition containing a silsesquioxane compound having the structure of general formula (5).

[0091] When a hard coat film has hard coat layers on both sides, the ratio of the thickness D3 of hard coat layer 3 to the thickness D4 of hard coat layer 4, D3 / D4, is, for example, 0.025 to 40, and may also be 0.05 to 20 or 0.1 to 10. If D3 / D4 is excessively large or excessively small, the hard coat film may curl significantly, resulting in poor handling properties.

[0092] [Top coat layer] As shown in Figures 3 and 4, a topcoat layer 5 may be provided on the surface of the hardcoat layer 3. For example, by providing a topcoat layer 5 containing a fluorine compound on the outermost surface of the hardcoat film, scratch resistance and stain resistance are improved.

[0093] <Fluorine compounds> The fluorine compounds constituting the topcoat layer contain one or more fluorine atoms in their molecules. Preferably, the fluorine compounds contain a perfluoroalkyl group. Examples of compounds containing a perfluoroalkyl group include perfluoroalkyl compounds, perfluoroalkyl ether compounds, perfluoroether compounds, and perfluoropolyether compounds.

[0094] The fluorine compound constituting the topcoat layer is preferably a condensate of a compound having an alkoxysilyl group and a perfluoroalkyl group in its molecule, and the film is formed by increasing the molecular weight through hydrolysis and condensation of the alkoxysilyl group.

[0095] Perfluoroalkyl groups are formed by replacing all hydrogen atoms in an alkyl group with fluorine atoms, such as CF3 (CF2). n It is represented by -. From the viewpoint of condensation reactivity, the trialkoxysilyl group is preferred as the alkoxysilyl group, and among these, the triethoxysilyl group or the trimethoxysilyl group is preferred, and the trimethoxysilyl group is particularly preferred.

[0096] Compounds having an alkoxysilyl group and a perfluoroalkyl group in the molecule preferably have a fluoroalkyl ether structure, and oligomers having repeating units of fluoroalkyl ether are preferred.

[0097] Examples of fluoroalkyl ether structures include -(OC4F8)-, -(OC3F6)-, -(OC2F4)-, and -(OCF2)-. The perfluoroalkyl group of the fluoroalkyl ether may be linear or branched, but a linear structure is preferable from the viewpoint of scratch resistance.

[0098] The number-average molecular weight of the oligomer is preferably 1,000 to 50,000, more preferably 3,000 to 20,000, and even more preferably 5,000 to 10,000. If the number-average molecular weight is less than 1,000, the scratch resistance may be poor, and if it is greater than 50,000, it may be difficult to apply the composition.

[0099] Perfluoroalkyl group-containing compounds may also contain substituents other than perfluoroalkyl groups or repeating units other than fluoroalkyl ethers. Examples of substituents include alkyl groups and fluoroalkyl groups in which some of the hydrogen atoms of the alkyl group are substituted with fluorine atoms (i.e., fluoroalkyl groups other than perfluoroalkyl groups). From the viewpoint of scratch resistance, perfluoroalkyl group-containing compounds are preferable as the proportion of hydrogen atoms of the alkyl group substituted with fluorine increases.

[0100] <Formation of the top coat layer> The method for forming the topcoat layer 5 is not particularly limited, and wet methods such as roll coating (bar coating, gravure coating, comma coating, etc.), die coating (slot die coating, fountain die coating, etc.), spin coating, spray coating, dip coating, etc., and dry methods such as vacuum deposition, sputtering, and CVD can be used. When forming a film by condensing a compound having an alkoxysilyl group and a perfluoroalkyl group in its molecule, a wet method is preferred from the viewpoint of promoting hydrolysis, etc.

[0101] Before forming the topcoat layer 5 on the hardcoat layer 3, surface treatments such as corona treatment, plasma treatment, or ion beam treatment may be performed. Alternatively, a primer layer may be provided on the hardcoat layer 3, and the topcoat layer 5 may be formed on top of it. Examples of materials for the primer layer include metal oxides such as silicon dioxide, titanium dioxide, aluminum oxide, and zirconium oxide; and organic-inorganic hybrid materials which are hydrolysis condensates of alkoxysilanes.

[0102] The surface treatment of the hard coat layer 3 generates hydroxyl groups, carboxyl groups, carbonyl groups, silanol groups, etc., which improves adhesion with compounds containing alkoxysilyl groups and perfluoroalkyl groups (components of the top coat layer 5), and tends to improve scratch resistance and stain resistance.

[0103] For surface treatment, corona treatment is preferred because it can be easily performed under atmospheric pressure. The corona treatment density is 1 W·min / m³.2 The above is preferable, 10 W·min / m 2 The above is more preferable: 30 W·min / m 2 More than 100W min / m 2 Above or above 500W·min / m 2 It may be greater than or equal to 3000W·min / m 2 The following is preferable: 600W·min / m 2 The following are preferable: If the processing density is too low, the adhesion improvement effect from the surface treatment may be insufficient, and if the processing density is too high, the hard coat layer may deteriorate.

[0104] When forming a scratch-resistant layer by a wet process, it is preferable to use a composition obtained by diluting a compound (oligomer) having an alkoxysilyl group and a perfluoroalkyl group in its molecule with a solvent. From the viewpoint of compound solubility and solvent volatility, preferred solvents include perfluoroaliphatic hydrocarbons having 5 to 12 carbon atoms such as perfluorohexane, perfluoromethylcyclohexane, and perfluoro-1,3-dimethylcyclohexane; polyfluoroaromatic hydrocarbons such as bis(trifluoromethyl)benzene; and hydrofluoroethers (HFE) such as perfluoropropyl methyl ether (C3F7OCH3), perfluorobutyl methyl ether (C4F9OCH3), perfluorobutyl ethyl ether (C4F9OC2H5), and perfluorohexyl methyl ether (C2F5CF(OCH3)C3F7). The perfluoroalkyl group and alkyl group of the hydrofluoroether may be linear or branched. Hydrofluoroethers are preferred as solvents, with perfluorobutyl methyl ether (C4F9OCH3) and perfluorobutyl ethyl ether (C4F9OC2H5) being preferred. The solvent may be a mixture of two or more solvents.

[0105] In addition to the perfluoro compounds mentioned above, the composition may also contain other additives such as perfluoroalkyl group-containing compounds, typified by fluoroalkyl ether oligomers that do not have an alkoxysilyl group in their molecule, fluorinated oils, and silicone oils. The inclusion of fluorinated oils or silicone oils may improve scratch resistance and stain resistance.

[0106] The composition may contain catalysts such as acids, bases, or metal-organic compounds. The inclusion of a catalyst may promote the reaction between the alkoxysilyl groups and the functional groups on the hard coat layer surface, potentially improving the adhesion of the topcoat layer 5 to the hard coat layer 3. The composition may also contain water. The presence of water may hydrolyze the alkoxysilyl groups, promoting their reaction with the functional groups on the hard coat layer surface, potentially improving the adhesion of the topcoat layer 5 to the hard coat layer 3.

[0107] Commercially available scratch-resistant coating compositions such as Daikin Industries' "OPTOOL UD509" and "OPTOOL DSX-E" may be used. Alternatively, solvents and additives may be added to commercially available coating compositions before use.

[0108] The solid content concentration of the compound (oligomer) having an alkoxysilyl group and a perfluoroalkyl group in the molecule in the composition is not particularly limited, but from the viewpoint of coatability, it is preferably 20% by weight or less, more preferably 10% by weight or less, even more preferably 5% by weight or less, and may be 1% by weight or less or 0.5% by weight or less. If the solid content concentration is excessively high, the coating film may become cloudy.

[0109] It is preferable to apply the composition onto the hard coat layer 3 and then heat it. Heating promotes the condensation of compounds having an alkoxysilyl group and a perfluoroalkyl group within the alkoxysilyl group molecule. The heating temperature is preferably 30°C or higher, more preferably 60°C or higher, and may be 100°C or higher or 130°C or higher. The heating temperature is usually 170°C or lower.

[0110] The thickness of the topcoat layer 5 is not particularly limited, but is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 6 nm or more, and particularly preferably 10 nm or more. The thickness of the scratch-resistant layer is preferably 1000 nm or less, more preferably 100 nm or less, and may be 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, or 30 nm or less. If the thickness of the scratch-resistant layer is excessively small, scratch resistance and stain resistance may be insufficient, and if the thickness is excessively large, the transparency of the coating film may decrease due to clouding, etc.

[0111] In a scratch-resistant layer formed by a composition containing a compound having an alkoxysilyl group and a perfluoroalkyl group in its molecule, it is preferable that the alkoxysilyl group in the perfluoroalkyl compound undergoes hydrolysis and condensation. When hydrolysis and condensation are promoted by heating after coating the composition, the hydroxyl group generated by the hydrolysis of the alkoxysilyl group can condense not only with the alkoxysilyl group of other perfluoro compounds (and the hydroxyl group generated by their hydrolysis) but also with the functional groups on the surface of the hard coat layer 3 to form covalent bonds. Therefore, the perfluoroalkyl compound is firmly immobilized on the hard coat layer 3, and scratch resistance is expected to improve.

[0112] In particular, the hard coat layer formed by curing a silsesquioxane compound having an epoxy group has hydroxyl groups (silanol groups) generated by hydrolysis during the condensation of the silane compound, and also has hydroxyl groups generated by ring-opening of the epoxy group during curing. These hydroxyl groups can undergo condensation reactions with the alkoxysilyl groups of the perfluoroalkyl compound. Furthermore, the silsesquioxane compound constituting the hard coat layer is an organic compound containing Si atoms, similar to the alkoxysilyl groups of the perfluoro compound, and they have a high affinity for each other. In addition, the alkoxysilyl groups and silanol groups of the silsesquioxane compound can condense with the alkoxysilyl groups of the perfluoro compound, which is thought to improve the adhesion between the hard coat layer 3 and the top coat layer 5.

[0113] [Characteristics of hard coat film] A hard coat film is provided on a resin film 1 with a hard coat layer 3 containing a cured product of a silsesquioxane compound having a structure represented by general formula (5) and a structure represented by general formula (6). This hard coat film has high surface hardness and excellent flexibility.

[0114] The pencil hardness of the hard coat layer 3 forming surface is preferably HB or higher, more preferably H or higher, even more preferably 2H or higher, even more preferably 3H or higher, and may also be 4H or higher. The larger the proportion of the structure represented by general formula (5) in the silsesquioxane compound, the higher the surface hardness tends to be. Also, the larger the thickness of the hard coat layer 3, the higher the surface hardness tends to be.

[0115] When a cylindrical mandrel test is performed on the hard coat film with the hard coat layer 3 forming surface facing outward, in accordance with JIS-K5600, it is preferable that the diameter φ of the mandrel in which cracks occur in the hard coat layer is small. φ is more preferably 4 mm or less, even more preferably 3 mm or less, and may be 2 mm or less. The silsesquioxane compound having the structure represented by general formula (6) tends to result in a smaller φ, and the larger the proportion of the structure represented by general formula (6) in the silsesquioxane compound, the smaller the φ tends to be. Furthermore, the thinner the hard coat layer 3, the smaller the φ tends to be. In the silsesquioxane compound, the ratio of the structure represented by general formula (5) to the total of the structures represented by general formula (6) is 0.95 or less (the ratio of the structure represented by general formula (6) is 0.05 or more). As a result, even when the thickness of the hard coat layer 3 is 40 μm or more, the mandrel diameter φ when the hard coat layer 3 is bent with the hard coat layer 3 on the outside is within the above range, and a hard coat film with excellent bending resistance can be obtained.

[0116] From a handling standpoint, it is preferable that the hard coat film has minimal curling. For example, it is preferable that the hard coat film does not form a tube when cut into 3cm squares. When a 3cm square piece of hard coat film is placed on a horizontal surface, the average amount of lift at the four vertices of the hard coat film is preferably 10mm or less, and more preferably 8mm or less.

[0117] Polysiloxane-based hard coat layers formed by curing silsesquioxane compounds having alicyclic epoxy groups exhibit excellent hardness but tend to have poor flexibility. On the other hand, hard coat layers formed by curing silsesquioxane compounds having glycidyloxy groups and long-chain spacers (with four or more atoms in the main chain) between the Si atoms and the glycidyloxy groups exhibit excellent flexibility but low surface hardness. Furthermore, when a hard coat layer is formed by curing a silsesquioxane compound with long-chain spacers between the Si atoms and the glycidyloxy groups, the hard coat film tends to curl more due to curing shrinkage.

[0118] In contrast, by curing a silsesquioxane compound that has both the structure represented by general formula (5) and the structure represented by general formula (6), and has both structures in a specific ratio, it is possible to achieve both high surface hardness and flexibility, and the occurrence of curl tends to be suppressed.

[0119] By providing a fluorine-based coating layer as a topcoat layer 5 on the hardcoat layer 3 of the hardcoat film, the stain resistance and scratch resistance of the hardcoat film tend to improve. A hardcoat film with a topcoat layer 5 preferably has a water contact angle of 100° or more on its surface (topcoat layer 5). A water contact angle of 105° or more is more preferable, and 110° or more is even more preferable. A high water contact angle means high water repellency and excellent resistance to dirt such as fingerprints (stain resistance).

[0120] It is preferable that the hard coat film maintains a small change in water contact angle and has a water contact angle of 100° or more even after scratch resistance tests (steel wool test) and abrasion resistance tests (eraser test). As described above, the fluorine-based top coat layer 5 formed from the specified material has high adhesion to the polysiloxane-based hard coat layer 3, and therefore has excellent scratch resistance and abrasion resistance, and can maintain a high water contact angle even after scratch resistance tests and abrasion resistance tests.

[0121] 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. The yellowness (YI) of the hard coat film is preferably 5 or lower, more preferably 4 or lower, and particularly preferably 3 or lower.

[0122] [Applications of hard coat films] The hard coat film may have various functional layers. Examples of functional layers include anti-reflective layers, anti-glare layers, anti-static layers, and transparent electrodes. In addition, a transparent adhesive layer may be attached to the surface of the resin film 1 that does not have a hard coat layer. Furthermore, a transparent adhesive layer may be attached to the hard coat film.

[0123] Because the above-mentioned hard coat film has high hardness, it can be suitably used as a cover window material placed on the outermost surface of an image display device. The hard coat film also has excellent flexibility, making it suitable for use as a cover window for foldable displays, and it can be applied to foldable displays of the type that fold with the screen facing outwards. [Examples]

[0124] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0125] [Preparation of polyimide films] As diamines, 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 3,3'-diaminodiphenylsulfone (3,3'-DDS) were dissolved in dimethylformamide (DMF) in a molar ratio of 90:10. As tetracarboxylic dianhydrides, bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylic acid)-(2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl) ester (TAHMBP), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), and 4,4'-oxydiphthalic acid dianhydride (ODPA) were added in a molar ratio of 50:30:20. The mixture was stirred under a nitrogen atmosphere for 12 hours to obtain a polyamic acid solution with a solid content of 18%.

[0126] Pyridine and acetic anhydride were added to this polyamic acid solution, and imidization was carried out by stirring at 80°C for 4 hours. A mixture of 2-propyl alcohol (IPA) and DMF was added dropwise to this solution to precipitate polyimide resin, which was then filtered by suction, washed, and vacuum dried to obtain the polyimide resin.

[0127] 100 parts by weight of the above polyimide, 2 parts by weight of ADEKA's "ADEKA Stab LA-31RG" and 0.8 parts by weight of ADEKA's "ADEKA Stab LA-F70" as UV absorbers, and 0.006 parts by weight of Arimoto Chemical Industry's "Plast Blue 8590" as a bluing agent were dissolved in methylene chloride to obtain a polyimide solution with a solid content of 10% by weight. The polyimide solution was applied to an alkali-free glass plate using a bar coater, and the solvent was removed by heating in an air atmosphere at 40°C for 60 minutes, 80°C for 30 minutes, 150°C for 30 minutes, 170°C for 30 minutes, and 200°C for 60 minutes to obtain a polyimide film with a thickness of 50 μm.

[0128] [Synthesis of silsesquioxane compounds] <Synthesis Example 1> In a reaction vessel equipped with a thermometer, stirrer, and reflux condenser, 43.1 g (175 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-303"), 23.0 g (75 mmol) of 8-glycidyloxyoctyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-4803"), 15.8 g of propylene glycol monomethyl ether, and 5.6 g of methanol were charged and mixed uniformly. To this mixture, a solution of 11.9 mg (0.125 mmol) of magnesium chloride dissolved in 13.5 g (750 mmol) of water was slowly added dropwise, and the mixture was mixed until uniform. 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.

[0129] Measurements were taken using a Bruker 400 MHz NMR spectrum with deuterated acetone as the solvent. 1 The residual rate of methoxy groups, calculated from the 1H-NMR spectrum, was 4.5%, and the residual rate of epoxy groups was 98%. The residual amount of magnesium chloride, calculated based on the initial weight, was 211 ppm.

[0130] <Synthesis Example 2> Silsesquioxane compound 2 was obtained in the same manner as in Synthesis Example 1, except that the amount of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM-303) was changed to 30.9 g (125 mmol) and the amount of 8-glycidyloxyoctyltrimethoxysilane (KBM-4803) was changed to 38.4 g (125 mmol). The residual rate of methoxy groups in silsesquioxane compound 2 was 4.5%, the residual rate of epoxy groups was 98%, and the residual amount of magnesium chloride (calculated value) was 211 ppm.

[0131] <Synthesis Example 3> 368 g (1200 mmol) of 8-glycidyloxyoctyltrimethoxysilane (KBM-4803) and 76.9 g of methanol were charged into a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was stirred uniformly. To this mixture, a solution of 57 mg (0.6 mmol) of magnesium chloride dissolved in 64.7 g (3600 mmol) of water was slowly added dropwise, and the mixture was stirred until uniform. 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 using a rotary evaporator to obtain silsesquioxane compound 3. The residual methoxy group percentage of silsesquioxane compound 3 was 4.5%, the residual epoxy group percentage was 95% or more, and the residual amount of magnesium chloride (calculated value) was 198 ppm.

[0132] <Synthesis Example 4> In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 61.6 g (250 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM-303) and 15.3 g of 1-methoxy-2-propanol were charged and mixed uniformly. To this mixture, a solution of 36 mg (0.375 mmol) of magnesium chloride dissolved in 9.0 g (499 mmol) of water was slowly added dropwise, and the mixture was mixed until uniform. 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 4. The residual methoxy group percentage of silsesquioxane compound 4 was 4.6%, the residual epoxy group percentage was 95% or more, and the residual amount of magnesium chloride (calculated value) was 800 ppm.

[0133] [Production of hard coat film] <Example 1> (Preparation of hard coat composition) Silsesquioxane compound 1 was diluted to 50% with propylene glycol monomethyl ether. To 100 parts by weight of the silsesquioxane compound, 2 parts by weight (solid content) of a 50% propylene carbonate solution of a photocationic polymerization initiator (SunApro "CPI-310FG") and 0.2 parts by weight (solid content) of a silicone leveling agent (BYK "BYK-300") were added to obtain hard coat composition 1.

[0134] (Formation of the hard coat layer) On one side of a 50μm thick transparent polyimide film, a discharge output of 600W·min / m was applied. 2 After corona treatment, the above hard coat composition was applied using a bar coater to a dry film thickness of 40 μm, and heated at 120°C for 10 minutes. Subsequently, a high-pressure mercury lamp was used to apply an integrated light intensity of 600 mJ / cm² at a wavelength of 365 nm. 2 The hard coat composition was cured by irradiating it with ultraviolet light in such a manner.

[0135] (Formation of the top coat layer) On the surface of the hard coat layer, discharge output of 3000W·min / m 2 After corona treatment, a solution of a fluorine-based coating agent (Daikin's "OPTOOL UD509") diluted to 0.1% by weight with hydrofluoroether (3M's "NOVEC7200") was applied using a bar coater to a dry film thickness of 10 nm, and heated at 150°C for 30 minutes to form a topcoat layer, thereby obtaining a hardcoat film having a hardcoat layer and a topcoat layer on one side of a transparent polyimide film.

[0136] <Example 2, Comparative Examples 1, 2> In the preparation of the hard coat composition, silsesquioxane compounds 2 to 4 were used instead of silsesquioxane compound 1. Otherwise, a hard coat film was obtained having a hard coat layer and a top coat layer on one side of a transparent polyimide film, in the same manner as in Example 1.

[0137] [Evaluation of hard coat film]

[0138] <Flexural resistance (cylindrical mandrel test)> In accordance with JIS K5600-5-1:1999, a cylindrical mandrel test was performed on a hard coat film using a Type 1 testing machine, with the hard coat layer facing outwards, to determine the bending diameter φ at which cracks occur in the hard coat layer.

[0139] <Surface hardness (pencil hardness)> In accordance with JIS K5600-5-4:1999, the pencil hardness of the hard coat layer surface (top coat layer surface) was measured under a load of 750g.

[0140] <Water contact angle> The contact angle of pure water (droplet volume: 2 μL) on the hard coat layer formation surface was measured using a contact angle meter (PCA-11, manufactured by Kyowa Interface Chemical).

[0141] <Scratch resistance test (steel wool test)> Steel wool #0000 was placed in a 27mm diameter indenter, and a reciprocating abrasion test (Shinto Kagaku TYPE:30S) was used to perform a scratch resistance test (steel wool test) on the hard coat layer surface under the following conditions: load: 500g, stroke: 50mm, 1 cycle / second, 1500 cycles. After the scratch resistance test, the water contact angle was measured.

[0142] <Abrasion resistance test (eraser test)> A 6mm diameter eraser manufactured by Minoan was placed in the indenter, and an abrasion resistance test (eraser test) of the hard coat layer surface was performed using a reciprocating abrasion testing machine under the same conditions as the scratch resistance test described above. After the abrasion resistance test, the water contact angle was measured.

[0143] <Total light transmittance and haze> The haze meter "HZ-V3" manufactured by Suga Test Instruments was measured according to the methods described in JIS K7361-1:1999 and JIS K7136:2000.

[0144] <Yellowness (YI)> The measurements were taken using a Suga Test Instruments SC-P colorimeter, according to the method described in JIS K7373-:2006.

[0145] [Evaluation Results] Table 1 shows the composition of the hard coat layer in the hard coat films of the examples and comparative examples (molar ratio of silane compounds used in the synthesis of silsesquioxane compounds) and the evaluation results. [Table 1]

[0146] The hard coat films of Examples 1 and 2 exhibited both high surface hardness and excellent flexibility. Furthermore, the changes in water contact angle during scratch resistance and abrasion resistance tests were small, and the top coat layer also demonstrated excellent scratch resistance and abrasion resistance.

[0147] The hard coat film of Comparative Example 1, which used silsesquioxane compound 3 as the curable resin component, obtained by condensing only a silane compound (KBM-4803) with 8 atoms in the main chain between the Si atom and the glycidyloxy group, showed excellent flexural resistance, but its surface hardness was insufficient compared to Examples 1 and 2. The hard coat film of Comparative Example 2, which used silsesquioxane compound 4 as the curable resin component, obtained by condensing only a silane compound (KBM-303) having an alicyclic epoxy group, showed high surface hardness, but its flexural resistance was insufficient.

[0148] From the above results, it can be seen that a hard coat film using a silsesquioxane compound as a curable resin component, which is obtained by co-condensing a silane compound having an alicyclic epoxy group and a silane compound having a spacer with a specific chain length between the Si atom and the glycidyloxy group in a specific ratio, can achieve both high surface hardness and flexibility when the hard coat is bent outwards. [Explanation of Symbols]

[0149] 1. Resin film 3,4 Hard coat layer 5. Top coat layer 11, 12, 13, 14 Hard coat film

Claims

1. A hard coat film comprising a hard coat layer on the first main surface of a resin film having a first main surface and a second main surface, The hard coat layer comprises a cured product of a silsesquioxane compound, The silsesquioxane compound is Including the structure represented by general formula (5) and the structure represented by general formula (6), The ratio of the structure represented by general formula (5) to the total amount of Si atoms is between 0.2 and 0.

95. The ratio of the structure represented by general formula (5) to the sum of the structures represented by general formula (6) is greater than 0.

4. Hard coat film: [Z-Si]…(5) [Y-R] ４ -Si] …(6) In general formula (5), Z is an organic group containing an alicyclic epoxy group, In general formula (6), R ４ A is a divalent organic group with 8 to 16 atoms in its main chain, and Y is a glycidyloxy group.

2. The hard coat film according to claim 1, wherein the silsesquioxane compound has a ratio of the structure represented by general formula (5) to the sum of the structures represented by general formula (6) of the structure represented by general formula (5) of general formula (5) of general formula (6) of 0.95 or less.

3. The hard coat film according to claim 1, wherein the silsesquioxane compound has a ratio of the structure represented by general formula (6) to the total amount of Si atoms of 0.05 or more and less than 0.

6.

4. The hard coat film according to any one of claims 1 to 3, comprising a top coat layer containing a fluorine compound on the hard coat layer.

5. The hard coat film according to any one of claims 1 to 3, comprising a second hard coat layer on the second main surface of the resin film.

6. The hard coat film according to any one of claims 1 to 3, wherein the resin film is a transparent polyimide film.

7. A method for manufacturing a hard coat film according to any one of claims 1 to 3, A method for producing a hard coat film, comprising applying a hard coat composition containing the silsesquioxane compound onto a resin film and curing it by irradiation with active energy rays to form a hard coat layer.

8. A method for producing a hard coat film according to claim 7, comprising forming the hard coat layer, then applying a composition containing a compound having an alkoxysilyl group and a perfluoroalkyl group in its molecule onto the hard coat layer, and condensing the compound to form a top coat layer.

9. A display comprising an image display panel and a hard coat film according to any one of claims 1 to 3.

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