Hard Coating Film and Method for Producing the Same

Abstract

A polyorganosiloxane compound according to one embodiment of the present invention is a condensation product of a silane compound, and has a structure represented by (Y-R1-Si). In the formula, Y represents a glycidyloxy group; and R1 represents a chain alkylene group that has from 4 to 16 carbon atoms in the main chain. It is preferable that the weight average molecular weight of this polyorganosiloxane compound is from 500 to 20,000; and it is preferable that the ratio of the T3 structure to the T2 structure, namely, T3 / T2 is less than 5. This polyorganosiloxane compound is suitable for use in the formation of a hard coat layer. This hard coat composition may contain a cationic photopolymerization initiator in addition to the polyorganosiloxane compound.

Description

Technical Field

[0001] The present invention relates to a polyorganosiloxane compound including a hard coat composition comprising a hard coat layer which is a cured product of 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 thinning, lightening, and further flexibilization of the devices. In response to these demands, replacement of glass materials used for substrates, cover windows, etc. with plastic film materials is being considered. 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 in particular, plastic films used for cover windows, etc. are required to have excellent transparency and flexibility (bend resistance) in addition to the above characteristics.

[0003] As a material for forming a hard coat layer, Patent Document 1 discloses a polyorganosiloxane compound having an epoxy group as a photopolymerizable functional group.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although the hard coat layer obtained by curing the polyorganosiloxane compound disclosed in Patent Document 1 has high hardness, when the hard coat film is bent with a small radius of curvature, cracks and fractures are likely to occur in the hard coat layer, and there are problems in applying it to flexible displays, foldable displays, and the like. Further, when the hard coat film is used as a cover window material for a display, high transparency is required, and there is still room for improvement in transparency (light transmittance).

[0006] In view of the above, an object of the present invention is to provide a hard coat film having high transparency and hardness and excellent bending resistance, and a curable material for forming the hard coat layer of the hard coat film.

Means for Solving the Problems

[0007] The inventors of the present invention have found that a polyorganosiloxane compound obtained by condensing a silane compound having a hydrocarbon group having a specific chain length between an Si atom and an epoxy group has excellent transparency and surface hardness after photocuring, and also has excellent bending resistance.

[0008] The polyorganosiloxane compound according to one embodiment of the present invention is a condensate of a silane compound represented by the general formula (A). The weight average molecular weight of the polysiloxane compound is preferably from 500 to 20,000. Q-(Si(OR 2 ) x R 3 3-x ) …(A)

[0009] In the general formula (A), R 2 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R 3 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. x is 2 or 3.

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

[0011] In the general formula (1), R 2 、R 3 and x are the same as those in the general formula (A). R 1 is a chain alkylene group having 4 to 16 carbon atoms in the main chain. Y is a glycidyloxy group represented by the following formula.

[0012]

Chemical formula

[0013] The ratio of the structure represented by the general formula (5) to the total number of Si atoms of the polyorganosiloxane compound may be 30% or more. The polyorganosiloxane compound may further contain the structure represented by the general formula (6). [X-Si] …(6)

[0014] By using, as the above silane compound, in addition to the silane compound represented by the general formula (1), the silane compound represented by the following general formula (2), a polyorganosiloxane compound having the structure represented by the formula (6) in addition to the structure represented by the formula (5) can be obtained. X-(Si(OR 2 ) x R 3 3-x ) …(2)

[0015] In the general formula (2) and the general formula (6), X is a monovalent organic group containing an alicyclic epoxy group. In the general formula (2), R 2 、R 3and x is the same as in the general formula (A).

[0016] The polyorganosiloxane compound may contain a structural unit (T3 structure) represented by the general formula (3) and a structural unit (T2 structure) represented by the general formula (4). The ratio T3 / T2 of the content of the T3 structure to the T2 structure is preferably less than 5. [Q-SiO 3 / 2 …(3) [Q-SiO 2 / 2 -Z] …(4)

[0017] Q in the general formula (3) and the general formula (4) is the same as in the general formula (A). In the general formula (4), Z is a monovalent organic group selected from the group consisting of a hydrogen atom, an alkoxy group having an alkyl group with 1 to 10 carbon atoms, an alkyl group with 1 to 10 carbon atoms, an aryl group with 6 to 25 carbon atoms, and an aralkyl group with 7 to 12 carbon atoms.

[0018] A polyorganosiloxane compound is obtained by the hydrolysis and condensation reaction of a silane compound. By using the compound represented by the general formula (1) as part or all of the silane compound, a polyorganosiloxane compound having the structure of the formula (5) is obtained.

[0019] The hydrolysis and condensation reaction of the silane compound may be carried out in the presence of a neutral salt catalyst. Since the polyorganosiloxane compound obtained by the reaction in the presence of a neutral salt catalyst tends to have a smaller T3 / T2 ratio, a compound having a T3 / T2 ratio of less than 5 can be easily obtained.

[0020] As the neutral salt catalyst, a salt composed of a combination of an ion of an element selected from the group consisting of an alkali metal element and a Group 2 element and a halide ion selected from the group consisting of a chloride ion, a bromide ion, and an iodide ion is preferred.

[0021] The polyorganosiloxane compound obtained by the hydrolysis and condensation reaction of the silane compound may contain the above neutral salt. The polyorganosiloxane compound may contain the neutral salt in an amount of about 1 to 10,000 ppm.

[0022] The above polyorganosiloxane compound has photocurability and is suitably used for forming a hard coat layer. One aspect of the present invention is a hard coat composition containing the above polyorganosiloxane compound. The hard coat composition may contain a photo cationic polymerization initiator in addition to the polyorganosiloxane compound. The photo cationic polymerization initiator may be a non-antimony-based photo cationic polymerization initiator that does not contain antimony.

[0023] One aspect of the present invention is a hard coat film provided with a hard coat layer composed of a cured product of the above hard coat composition on at least one main surface of a transparent resin substrate. The thickness of the hard coat layer may be 0.5 to 100 μm. Examples of the resin material of the transparent resin substrate include polyester, polycarbonate, polyamide, polyimide, cyclic polyolefin, acrylic resin, and cellulose-based resin.

[0024] A hard coat film is formed by applying the above hard coat composition on a transparent resin substrate and irradiating it with active energy rays to cure the hard coat composition (the above polyorganosiloxane compound).

Advantages of the Invention

[0025] The cured film (hard coat layer) formed by curing the above polysiloxane compound has high surface hardness and transparency, and is excellent in bending resistance. A hard coat film provided with the cured film on a transparent resin substrate is less likely to crack even when bent with a small radius of curvature, and can be suitably used for flexible displays and foldable displays.

Embodiments for Carrying Out the Invention

[0026] One aspect of the present invention is a polyorganosiloxane compound having cationic polymerizability and a method for producing the same. A further aspect of the present invention is a hard coat composition containing the silane compound, and a hard coat film comprising a hard coat layer formed from a cured product of the hard coat composition and a method for producing the same. Hereinafter, the preferred forms of the polyorganosiloxane compound, the hard coat composition for forming the hard coat layer, and the hard coat film will be described in order. In addition, the components, functional groups, etc. exemplified in this specification may be used alone or in combination of two or more (coexist) unless otherwise specified.

[0027] [Polyorganosiloxane compound] [Silane compound] The polyorganosiloxane compound of one aspect of the present invention is a condensate of a silane compound represented by the following general formula (A). Q-(Si(OR 2 ) x R 3 3-x ) …(A)

[0028] R 2 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Specific examples of the alkyl group 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 and the like.

[0029] The silane compound represented by the general formula (A) has two or three (-OR 2 ) in one molecule. Since Si-OR 2 has hydrolyzability, a polyorganosiloxane compound can be obtained by condensation of the silane compound. From the viewpoint of hydrolyzability, the carbon number of R 2 is preferably 3 or less, and it is particularly preferable that R 2 is a methyl group.

[0030] R 3is a monovalent hydrocarbon group selected from the group consisting of a hydrogen atom, 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 the hydrocarbon include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an isopropyl group, an isobutyl group, a cyclohexyl group, an ethylhexyl group, a benzyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a phenethyl group, and the like.

[0031] In general formula (A), x is 2 or 3. When x = 3 (that is, when three alkoxy groups (or hydroxy groups) -OR 2 are bonded to the Si atom), the silane compound does not have R 3 . From the viewpoints of forming a network-like polysiloxane compound and increasing the number of epoxy groups contained in the polysiloxane compound to enhance the hardness of the cured film, in general formula (A), it is preferable that x = 3. A silane compound with x = 2 and a silane compound with x = 3 may be used in combination. Further, for the purpose of adjusting the molecular weight of the polysiloxane compound obtained by condensation, in addition to the silane compound in which x is 2 or 3, a silane compound in which x is 1 may also be used.

[0032] In general formula (A), Q is an arbitrary monovalent organic group. When Q contains an epoxy group, the polyorganosiloxane compound obtained by condensation of the silane compound has cationic photopolymerizability.

[0033] (Silane compound having a long-chain spacer) The polyorganosiloxane compound according to one embodiment of the present invention includes, as the above silane compound, a silane compound represented by the following general formula (1). Y-R 1 -(Si(OR 2 ) x R 3 3-x ) …(1)

[0034] In general formula (1), R 2 , R 3and x is the same as in the general formula (A). R 1 is a linear alkylene group having 4 to 16 carbon atoms in the main chain. Y is a glycidyloxy group represented by the following formula.

[0035] [Chemical formula]

[0036] The number of carbon atoms in the main chain means the number of carbon atoms contained in the straight chain connecting the Si atom and the oxygen atom of the glycidyloxy group Y in the general formula (1). When R 1 is a linear alkylene group, the number of carbon atoms in the main chain is equal to the number of carbon atoms of R 1 . That is, the silane compound of the general formula (1) (hereinafter sometimes referred to as "silane compound (1)") is a compound in which the Si atom and the glycidyloxy group Y are bonded via 4 to 16 carbon atoms therebetween.

[0037] Specific examples of the linear alkylene group having 4 to 16 carbon atoms include a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a decamethylene group, a dodecamethylene group, a tetradecamethylene group, a hexadecamethylene group, etc. R 1 may be such that some or all of the hydrogen atoms of methylene (-CH2-) are substituted with substituents having 1 to 6 carbon atoms. Examples of the substituents having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a cyclohexyl group, a phenyl group, etc.

[0038] In the polyorganosiloxane compound obtained by the condensation of the silane compound (1), due to the presence of the alkylene group R 1 having a specific chain length between the epoxy group, which is a polymerizable functional group, and the Si atom, the molecular structure has flexibility even after being cured by the reaction of the epoxy group. Therefore, the hard coat layer composed of the cured product of the polyorganosiloxane compound exhibits excellent flexibility (flexural resistance).

[0039] The greater the distance between the Si atom and the epoxy group, that is, the greater the number of carbon atoms in the main chain of the alkylene group R 1 which is a spacer and the longer the chain length, the more likely the flexural resistance of the hard coat layer is to improve. As described above, the number of carbon atoms in the main chain of R 1 is 4 or more, preferably 6 or more, and may be 8 or more. On the other hand, when the number of carbon atoms in the main chain of R 1 is excessively large, the hardness of the hard coat layer tends to be insufficient. Therefore, the number of carbon atoms in the main chain of R 1 is 16 or less, preferably 14 or less, more preferably 12 or less, and may be 10 or less.

[0040] Specific examples of the silane compound (1) 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-glycidyloxyoctyltriethoxysilane, 8-glycidyloxyoctylmethyldiethoxysilane, 9-glycidyloxynonyltrimethoxysilane, 9-glycidyloxynonylmethyldimethoxysilane, 9-glycidyloxynonyltriethoxysilane, 9-glycidyloxynonylmethyldiethoxysilane, 10-glycidyloxydecyltrimethoxysilane, 10-glycidyloxydecylmethyldimethoxysilane, 10-glycidyloxydecyltriethoxysilane, 10-glycidyloxydecylmethyldiethoxysilane, 11-glycidyloxyundecyltrimethoxysilane, 11-glycidyloxyundecylmethyldimethoxysilane, 11-glycidyloxyundecyltriethoxysilane, 11-glycidyloxyundecylmethyldiethoxysilane, 12-glycidyloxydodecyltrimethoxysilane, 12-glycidyloxydodecylmethyldimethoxysilane, 12-glycidyloxydodecyltriethoxysilane, 12-glycidyloxydodecylmethyldiethoxysilane, 13-glycidyloxytridecyltrimethoxysilane, 13-glycidyloxytridecylmethyldimethoxysilane,13-Glycidyloxytridecyltriethoxysilane, 13-glycidyloxytridecylmethyldiethoxysilane, 14-glycidyloxytetradecyltrimethoxysilane, 14-glycidyloxytetradecylmethyldimethoxysilane, 14-glycidyloxytetradecyltriethoxysilane, 14-glycidyloxytetradecylmethyldiethoxysilane, 15-glycidyloxypentadecyltrimethoxysilane, 15-glycidyloxypentadecylmethyldimethoxysilane, 15-glycidyloxypentadecyltriethoxysilane, 15-glycidyloxypentadecylmethyldiethoxysilane, 16-glycidyloxyhexadecyltrimethoxysilane, 16-glycidyloxyhexadecylmethyldimethoxysilane, 16-glycidyloxyhexadecyltriethoxysilane, 16-glycidyloxyhexadecylmethyldiethoxysilane, etc.

[0041] (Other silane compounds) When obtaining a polyorganosiloxane compound by condensation of a silane compound, as the silane compound, in addition to the above silane compound (1), other silane compounds may be used. For example, a compound represented by the following general formula (2) may be used as the silane compound. X-(Si(OR 2 ) x R 3 3-x ) …(2)

[0042] In the general formula (2), R 2 , R 3 and x are the same as in the general formula (A). X is a monovalent organic group containing an alicyclic epoxy group.

[0043] Examples of X include an alicyclic epoxy group, an alkyl group having an alicyclic epoxy group as a substituent, an ethylene glycol group having an alicyclic epoxy group as a substituent, etc. Specific examples of the alicyclic epoxy group of X include a 3,4-epoxycyclohexyl group.

[0044] From the viewpoints of heat resistance, flexural resistance, etc. of the hard coat layer, X is preferably an alkyl group having an alicyclic epoxy group as a substituent. In the general formula (2), when X is an alkyl group having an alicyclic epoxy group as a substituent, the alkylene group between the Si atom and the epoxy group may be linear or branched, but a linear alkylene group is preferred, a linear alkylene having 1 to 5 carbon atoms is preferred, and ethylene is particularly preferred.

[0045] Specific examples of the silane compound of the general formula (2) (hereinafter sometimes referred to as "silane compound (2)") include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyldimethylmethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 3-(3,4-epoxycyclohexyl)propylmethyldimethoxysilane, 3-(3,4-epoxycyclohexyl)propyldimethylmethoxysilane, and the like.

[0046] By using the compound (1) and the silane compound (2) containing an alicyclic epoxy group in combination, the surface hardness of the hard coat layer formed by the curing of the hard coat composition containing the polyorganosiloxane compound may be improved. Further, since the alicyclic epoxy group has a higher curing rate in photo cationic polymerization than the glycidyl group, by using a silane compound containing an alicyclic epoxy group in combination, the curing rate of the hard coat layer is increased, the tackiness of the surface is reduced (the tack-free property is increased), and the adhesion (blocking) of the hard coat film is suppressed.

[0047] When obtaining a polyorganosiloxane compound by condensation of a silane compound, the ratio of the silane compound (2) to the total of the silane compound (1) and the silane compound (2) may be 1% or more, 3% or more, 5% or more, 7% or more, or 10% or more in terms of molar ratio. When using the compound (1) and the compound (2) as the silane compounds containing an epoxy group, the ratio of the compound (2) is substantially equal to the ratio of the alicyclic epoxy group to the total amount of the epoxy groups in the polyorganosiloxane compound.

[0048] Since the polyorganosiloxane compound has an alicyclic epoxy group derived from the silane compound (2), the hardness and tack-free property of the hard coat layer tend to be enhanced. On the other hand, when the content of the alicyclic epoxy group is excessively large, the flexibility of the hard coat layer is low, and the flex resistance may decrease. Therefore, the ratio of the silane compound (2) to the total of the silane compound (1) and the silane compound (2) is preferably 40% or less, more preferably 30% or less, and may be 25% or less, 20% or less, or 15% or less in terms of molar ratio.

[0049] As the silane compound other than the silane compound (1), a silane compound containing no epoxy group may be used. Examples of the silane compound containing no epoxy group include those in which, in the general formula (A), Q is a monovalent organic group selected from the group consisting of a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group having 6 to 25 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms. When Q is a substituted alkyl group, examples of the substituent include a thiol group, an amino group, a (meth)acryloyl group, a phenyl group, a cyclohexyl group, and a halogen.

[0050] From the viewpoint of increasing the surface hardness of the hard coat layer, the larger the number of epoxy groups contained in one molecule of the polyorganosiloxane compound, the more preferable. When obtaining a polyorganosiloxane compound by condensation of a silane compound of the general formula (A), the ratio of the silane compound not containing an epoxy group to an epoxy group-containing silane compound such as the silane compound (1) and the silane compound (2) is preferably 2 or less, more preferably 1 or less, still more preferably 0.4 or less, particularly preferably 0.2 or less, and may even be 0 in terms of molar ratio. Further, the ratio of the silane compound not containing an epoxy group to the silane compound (1) is preferably 2 or less, more preferably 1 or less, still more preferably 0.4 or less, particularly preferably 0.2 or less, and may even be 0 in terms of molar ratio.

[0051] <Properties of polyorganosiloxane compound> (Molecular weight) Si-OR of the above silane compound 2 By hydrolysis and condensation of the Si-OR moiety, an Si-O-Si bond is formed between the silane compounds, and a polyorganosiloxane compound is produced. From the viewpoint of increasing the hardness of the cured film (hard coat layer), the weight average molecular weight of the polyorganosiloxane compound is preferably 500 or more. Also, from the viewpoint of suppressing volatilization, the weight average molecular weight of the polyorganosiloxane compound is preferably 500 or more. On the other hand, if the molecular weight is excessively large, cloudiness may occur due to a decrease in compatibility with other compositions. Therefore, the weight average molecular weight of the polyorganosiloxane compound is preferably 20000 or less. The weight average molecular weight of the polyorganosiloxane compound is more preferably 1000 to 18000, still more preferably 1500 to 16000, and may also be 2000 to 14000, or 2800 to 12000.

[0052] The weight average molecular weight of the polyorganosiloxane compound can be controlled by appropriately selecting the amount of water used in the reaction, the type and amount of the catalyst. For example, the larger the amount of water charged together with the catalyst during the hydrolysis reaction, the greater the tendency for the weight average molecular weight to increase.

[0053] (T3 / T2 ratio) The polyorganosiloxane compound produced by hydrolysis and condensation of the silane compound of general formula (A) contains a structural unit represented by the following formula (3) and a structural unit represented by the following formula (4).

[0054] [Q-SiO 3 / 2 …(3) [Q-SiO 2 / 2 -Z] …(4)

[0055] In general formula (3) and general formula (4), Q is the same as in general formula (A). In the polyorganosiloxane compound produced by the condensation of the silane compound (1), Q− is the above Y-R 1 −. Z in formula (4) is a monovalent organic group selected from the group consisting of a hydrogen atom, an alkoxy group having an alkyl group with 1 to 10 carbon atoms, an alkyl group with 1 to 10 carbon atoms, an aryl group with 6 to 25 carbon atoms, and an aralkyl group with 7 to 12 carbon atoms.

[0056] Specific examples of the monovalent organic group Z include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy 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, cyclohexyl group, ethylhexyl group, benzyl group, phenyl group, tolyl group, xylyl group, naphthyl group, phenethyl group, etc.

[0057] The structural unit represented by formula (3): [SiO 3 / 2 body] has a structure in which the three alkoxy groups (Si-OR 2 ) of the silane compound having a T unit structure with x = 3 in general formula (A) have all undergone a condensation reaction to form a Si-O-Si bond, and is called a "T3 structure". The structural unit represented by formula (4): [SiO 2 / 2The "body" has a structure in which, among the three alkoxy groups of the silane compound having a T unit structure with x = 3 in the general formula (A), two have undergone a condensation reaction to form a Si - O - Si bond, and is referred to as the "T2 structure".

[0058] The polyorganosiloxane compound of an embodiment of the present invention is SiO represented by the formula (3) 3 / 2 body (T3 structure) and SiO represented by the formula (4) 2 / 2 body (T2 structure) ratio [SiO 3 / 2 body] / [SiO 2 / 2 body] is preferably less than 5. In addition to the polyorganosiloxane compound having a long-chain spacer structure derived from the alkylene group R 1 of the silane compound (1), when the ratio of the T3 structure to the T2 structure (hereinafter sometimes referred to as the "T3 / T2 ratio") is less than 5, the flexural resistance of the hard coat layer formed by the curing of the polyorganosiloxane compound tends to improve. Also, when the T3 / T2 ratio is less than 5, the adhesion between the hard coat layer and the transparent resin substrate tends to improve.

[0059] The T3 / T2 ratio of the polyorganosiloxane 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 tendency to suppress cracks and fractures in the hard coat layer when the hard coat film is bent.

[0060] SiO 3 / 2 The higher the ratio of the body (T3 structure), the easier it is to form a three-dimensionally grown dense network-like polysiloxane skeleton, and the hardness tends to increase. On the other hand, since the flexibility of the molecular structure decreases, when the ratio of the T3 structure is 5 or more, the flexural resistance is considered to be insufficient. As described above, when the T3 / T2 ratio is less than 5, it is considered that a hard coat layer excellent in both the excellent mechanical strength due to the formation of the polysiloxane skeleton and the flexibility (flexural resistance) due to the SiO 2 / 2 body (T2 structure) is formed, so that a hard coat layer having high surface hardness and excellent flexural resistance is formed.

[0061] The polyorganosiloxane compound may not contain SiO 3 / 2 units (i.e., the T3 / T2 ratio is 0). However, from the viewpoint of increasing the surface hardness of the hard coat layer, the T3 / T2 ratio is preferably 0.5 or more, more preferably 1 or more, and may be 1.5 or more or 2 or more.

[0062] The polyorganosiloxane compound obtained by the condensation of compound (1) is composed of an SiO 3 / 2 unit (T3 structure) represented by the following formula (3’) and an SiO 2 / 2 unit (T2 structure) represented by the following formula (4’). The ratio [SiO 3 / 2 unit] / [SiO 2 / 2 unit] is preferably less than 5, more preferably 4 or less, still more preferably 3.5 or less, and may be 3 or less or 2.5 or less. The ratio of the two may be 0, but is preferably 0.5 or more, more preferably 1 or more, and may be 1.5 or more or 2 or more.

[0063] [Y-R 1 -SiO 3 / 2 …(3’) [Y-R 1 -SiO 2 / 2 -Z] …(4’)

[0064] Y and R in general formula (3’) and general formula (4’) 1 are the same as those in general formula (1). Z in general formula (4’) is the same as that in general formula (4).

[0065] In the polyorganosiloxane compound obtained by the condensation of silane compound (1) and another silane compound (for example, silane compound (2) or a silane compound not containing an epoxy group), the ratio of the SiO 3 / 2 unit of formula (3’) to the SiO 2 / 2 unit of formula (4’) is preferably within the above range.

[0066] The SiO 3 / 2 units and SiO in the polyorganosiloxane compound2 / 2 The content and ratio of the body can be calculated by 29 Si-NMR measurement. 29 In Si-NMR, since the Si atoms of the SiO 3 / 2 body and the Si atoms of the SiO 2 / 2 body show different chemical shifts, the integral values of the respective signals in the NMR spectrum are obtained, and the T3 / T2 ratio can be calculated from the ratio of the two.

[0067] The T3 / T2 ratio can be controlled by adjusting the amount of water used in the hydrolysis and condensation reaction of the silane compound, the type of catalyst, and the amount of catalyst. For example, the larger the amount of catalyst, the greater the tendency for the T3 / T2 ratio to increase. As will be described later, the use of a neutral salt catalyst tends to reduce the T3 / T2.

[0068] <Hydrolysis and Condensation of Silane Compound> By reacting the silane compound with water, the Si-OR of the silane compound 2 portion is hydrolyzed, and the hydrolyzate is condensed to obtain a polysiloxane compound. The amount of water required for the hydrolysis and condensation reaction is preferably 0.3 to 3 equivalents, more preferably 0.5 to 2 equivalents, per equivalent of the -OR 2 group bonded to the Si atom. When the amount of water is excessively small, there are many OR 2 groups remaining without being hydrolyzed, and the molecular weight of the polyorganosiloxane compound is small, so the hardness of the hard coat layer tends to be insufficient. When the amount of water is excessively large, the reaction rate of the hydrolysis and condensation reaction is large, high molecular weight condensates are formed, and the transparency and flexibility of the hard coat layer tend to decrease.

[0069] In the hydrolysis reaction and condensation reaction of the silane compound, it is preferable to suppress the deactivation due to the ring opening of the epoxy group contained in the silane compound (1) or the silane compound (2). 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 polyorganosiloxane compound obtained as the condensate of the silane compound, it is preferable to carry out the hydrolysis and condensation reactions in the presence of a neutral salt catalyst.

[0070] A neutral salt is a normal salt of a strong acid and a strong base. Specifically, it is a salt of an ion (cation) selected from the group consisting of alkali metal elements and Group 2 elements and a halide ion (anion) selected from the group consisting of chloride ion, bromide ion, and iodide ion.

[0071] Specific examples of the neutral salt 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, calcium iodide, and the like.

[0072] As described above, by using a neutral salt catalyst, a polyorganosiloxane compound having a small T3 / T2 ratio can be obtained. In addition, an acid catalyst or a base catalyst reacts electrophilicly and nucleophilically with various substances by itself, while a neutral salt has the advantage of low erosion to the metal and resin materials of the reaction vessel and storage vessel, so there are few restrictions on the materials of the manufacturing and storage equipment.

[0073] When a basic catalyst generally used in the condensation reaction of a silane compound remains in the hard coat composition, it may quench the acid generated from a photo cationic polymerization initiator (photo acid generator) and inhibit the polymerization reaction. On the other hand, by using a neutral salt catalyst, polymerization inhibition can be suppressed. Therefore, in the polyorganosiloxane compound obtained by the condensation of a silane compound, or in the hard coat composition, a neutral salt catalyst may remain, and steps such as removal or neutralization of the catalyst after the reaction can be omitted. The use of a neutral salt catalyst can contribute to the simplification of the manufacturing process and the improvement of the yield.

[0074] The amount of the catalyst used is not particularly limited. The larger the amount of the catalyst used, the more likely the hydrolysis and condensation reactions of the silane compound are to be promoted. On the other hand, if the amount of the catalyst used is excessively large, the transparency of the condensate may be impaired or the purification may become complicated. The amount of the neutral salt catalyst used is preferably 0.000001 to 0.1 mol, more preferably 0.000005 to 0.01 mol, per 1 mol of the hydrolyzable silyl group (-OR 2 ) of the silane compound.

[0075] As described above, in the polyorganosiloxane compound obtained by the hydrolysis and condensation reaction of the silane compound, a neutral salt catalyst may remain. The amount of the neutral salt (catalyst) remaining in the polyorganosiloxane compound may be 1 ppm or more, 10 ppm or more, 50 ppm or more, or 100 ppm or more. From the viewpoint of the transparency of the hard coat layer, the amount of the basic catalyst remaining in the polyorganosiloxane compound is preferably 10000 ppm or less, more preferably 5000 ppm or less, still more preferably 3000 ppm or less, and may be 1000 ppm or less, 800 ppm or less, or 500 ppm or less.

[0076] In the hydrolysis and condensation reactions of silane compounds, the reaction may be carried out while refluxing a diluting solvent and alcohols or the like generated by hydrolysis. The diluting solvent preferably exhibits compatibility with water, and a water-soluble alcohol or ether compound is preferred. Since many silane compounds have low compatibility with neutral salts and water used for hydrolysis, it is preferable to react them as a solution in a compatible system using a diluting solvent.

[0077] The boiling point of the diluting solvent 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 diluting solvent is excessively low, the diluting solvent may be in a reflux state at a low temperature, and thus the reaction rate may decrease. From the viewpoint of the removability of the diluting solvent after the reaction, the boiling point of the diluting solvent is preferably 200°C or lower.

[0078] Specific examples of the diluting solvent 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, propylene glycol dimethyl ether, and the like.

[0079] The reaction temperature of 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. If the reaction temperature is 40°C or higher, the catalytic activity of the neutral salt is high, so the reaction time can be shortened. From the viewpoint of suppressing side reactions of the organic groups of silane compounds, the reaction temperature is preferably 200°C or lower.

[0080] From the perspective of increasing the crosslinking point density in the cured product (hard coat layer) and improving the hardness, it is preferable that the polyorganosiloxane compound obtained by hydrolysis and condensation of the silane compound has a higher residual rate of epoxy groups. The residual rate of epoxy groups, that is, the ratio of the number of moles of epoxy groups in the polyorganosiloxane compound obtained by condensation to the number of moles of epoxy groups contained in the silane compound as the raw material, is preferably 20% or more, more preferably 40% or more, still more preferably 60% or more, particularly preferably 80% or more, and may be 90% or more or 95% or more. The residual rate of epoxy groups is 1 determined by 1H-NMR measurement.

[0081] As described above, a polyorganosiloxane compound is obtained by the hydrolysis and condensation reaction of the silane compound represented by the general formula (A). In the hydrolysis and condensation reaction, except for side reactions such as ring-opening of epoxy groups, the monovalent organic group Q bonded to the Si atom does not react. Therefore, in the polyorganosiloxane compound, the [Q-Si] structural part in the silane compound is retained. Therefore, the polyorganosiloxane compound obtained by condensation of the silane compound (1) has a structure represented by the following general formula (5) (hereinafter, may be referred to as "structure (5)"). [Y-R 1 -Si] …(5)

[0082] Y and R in the general formula (5) 1 are the same as those in the general formula (1). The content of the structure (5) in the polyorganosiloxane compound is approximately equal to the sum of the content of the structure of the general formula (3') and the content of the structure of the general formula (4').

[0083] The ratio of the number of the structure (5) to the total number of Si atoms in the polyorganosiloxane compound is preferably 30% or more, more preferably 50% or more, still more preferably 60% or more, particularly preferably 70% or more, and may be 80% or more, 85% or more, 90% or more, or 95% or more.

[0084] Since the silane compound represented by the general formula (A) has one Si per molecule, the polyorganosiloxane compound formed by the condensation of N molecules of the silane compound contains N Si atoms. When the epoxy group remains unreacted during the hydrolysis and condensation reaction, n structures (5) are formed from n silane compounds (1). Therefore, in the polyorganosiloxane compound obtained by the condensation of the silane compound, the ratio (molar ratio: n / N) of the silane compound (1) in the silane compound used as the raw material is approximately equal to the ratio of the structure (5) to the number of Si atoms in the polyorganosiloxane compound.

[0085] When a silane compound (2) is used in addition to the silane compound (1) as the silane compound, the polyorganosiloxane compound has, in addition to the above structure (5), a structure represented by the following general formula (6) (hereinafter sometimes referred to as "structure (6)"). [X-Si] …(6) X in the general formula (6) is the same as in the general formula (2).

[0086] The ratio of the number of the structure (6) to the total number of Si atoms in the polyorganosiloxane compound may be 1% or more, 3% or more, 5% or more, 7% or more, or 10% or more, and may be 40% or less, 30% or less, 25% or less, 20% or less, or 15% or less.

[0087] The ratio of the number of epoxy groups to the total number of Si atoms in the polyorganosiloxane compound is preferably 30% or more, more preferably 50% or more, still more preferably 60% or more, particularly preferably 70% or more, and may be 80% or more, 85% or more, 90% or more, or 95% or more. The ratio of the number of glycidyloxy groups to the total number of epoxy groups is preferably 60% or more, more preferably 70% or more, and may be 80% or more, 85% or more, 90% or more, 95% or more, or 100%. The ratio of the number of alicyclic epoxy groups to the total number of epoxy groups may be 1% or more, 3% or more, 5% or more, 7% or more, or 10% or more, and may also be 40% or less, 30% or less, 25% or less, 20% or less, or 15% or less. These ratios can be adjusted to any range according to the composition (ratio of compounds) of the silane compound used as a raw material for the polyorganosiloxane compound.

[0088] [Hard coat composition] The hard coat composition, which is one aspect of the present invention, is a composition containing the above polyorganosiloxane compound as an essential component. The hard coat composition preferably contains a photo cationic polymerization initiator in addition to the polyorganosiloxane compound, and may contain other components.

[0089] From the viewpoint of forming a hard coat cured film having excellent mechanical strength, the content of the above polyorganosiloxane compound in the hard coat composition is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, still more preferably 60 parts by weight or more, based on 100 parts by weight in total of the solid content (non-volatile content).

[0090] [Photo cationic polymerization initiator] The photo cationic polymerization initiator is a compound (photoacid generator) that generates an acid upon irradiation with active energy rays. The acid generated from the photoacid generator causes the ring-opening and polymerization reaction of the epoxy groups of the above polyorganosiloxane compound, forming intermolecular cross-links and curing the hard coat material.

[0091] Examples of photoacid generators include strong acids such as toluenesulfonic acid or boron tetrafluoride; onium salts such as sulfonium salts, ammonium salts, phosphonium salts, iodonium salts, and selenium salts; iron-allyl complexes; silanol-metal chelate complexes; sulfonic acid derivatives such as disulfones, disulfonyldiazomethanes, disulfonylmethanes, sulfonylbenzoylmethanes, imidosulfonates, and benzoin sulfonates; and organic halogen compounds.

[0092] Among the above photoacid generators, aromatic sulfonium salts or aromatic iodonium salts are preferred because of their high stability in a hard coat composition containing a polyorganosiloxane compound having an epoxy group. Examples of these counter anions include fluorophosphate-based anions, fluoroantimonate-based anions, and fluoroborate-based anions. When a photoacid generator containing these counter anions is used, a hard coat layer with a high photocuring rate and excellent adhesion to a transparent resin substrate can be easily obtained.

[0093] Among them, as counter anions with a lower environmental load and less impact on the environment and the human body compared to antimony-based anions such as SbF6, fluorophosphate-based anions and fluoroborate-based anions are preferred. When a photoacid generator containing these non-antimony-based counter anions is used, the hardness of the hard coat layer tends to improve. In addition, even when the hard coat layer (hard coat film) is exposed to a high-temperature and high-humidity environment, the residue of the photoacid generator is less likely to bleed out, and the decrease in transparency due to an increase in haze is suppressed.

[0094] Specific examples of non-antimony-based photoacid generators with a high photocuring rate and not containing antimony-based compounds include diphenyl(4-phenylthiophenyl)sulfonium hexafluorophosphate, hexafluorophosphate derivatives in which some or all of the fluorine atoms of hexafluorophosphate are substituted with perfluoroalkyl groups, triphenylsulfonium tetrakispentafluorophenylborate, and the like.

[0095] The content of the photo cationic 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 still more preferably 0.2 to 2 parts by weight with respect to 100 parts by weight of the polyorganosiloxane compound.

[0096] <Reactive diluent> The hard coat composition may contain a reactive diluent. The reactive diluent may contain, for example, a cationic polymerizable compound other than the above polyorganosiloxane compound. As the reactive diluent for photo cationic polymerization, a compound having a cationic polymerizable functional group is used. Examples of the cationic polymerizable functional group of the reactive diluent include an epoxy group, a vinyl ether group, an oxetane group, and an alkoxysilyl group. Among them, since the reactivity with the epoxy group of the polyorganosiloxane compound is high, those having an epoxy group are preferred as the reactive diluent.

[0097] The content of the reactive diluent in the hard coat composition is preferably 100 parts by weight or less, more preferably 50 parts by weight or less with respect to 100 parts by weight of the polyorganosiloxane compound.

[0098] <Photosensitizer> The hard coat composition may contain a photosensitizer for the purpose of improving the photosensitivity of the photo cationic polymerization initiator (photoacid generator). Since the photosensitizer can more efficiently absorb light in a wavelength range that the photoacid generator itself cannot absorb, those having little overlap with the absorption wavelength range of the photoacid generator are preferred. Examples of the photosensitizer include anthracene derivatives, benzophenone derivatives, thioxanthone derivatives, anthraquinone derivatives, benzoin derivatives, and the like.

[0099] The content of the photosensitizer in the hard coat composition is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and still more preferably 10 parts by weight or less with respect to 100 parts by weight of the above photoacid generator.

[0100] <Particles> The hard coat composition may contain particles for the purpose of adjusting film properties such as surface hardness and flexural resistance, and suppressing curing shrinkage. As the particles, organic particles, inorganic particles, organic-inorganic composite particles, etc. may be appropriately selected and used. Examples of the material of the organic particles include poly(alkyl methacrylate), crosslinked poly(alkyl methacrylate), crosslinked styrene, nylon, silicone, crosslinked silicone, crosslinked urethane, crosslinked butadiene, etc. Examples of the material of the inorganic particles include , chi metal oxides such as titania, alumina, tin oxide, zirconia, zinc oxide, antimony oxide, etc.; metal nitrides such as silicon nitride, boron nitride, etc.; metal salts such as calcium carbonate, calcium hydrogen phosphate, calcium phosphate, aluminum phosphate, etc. Examples of the organic-inorganic composite filler include those in which an inorganic layer is formed on the surface of the organic particles, and those in which an organic layer or organic fine particles are formed on the surface of the inorganic particles.

[0101] Examples of the shape of the particles include spherical, powdery, fibrous, acicular, scaly, etc. Since spherical particles have no anisotropy and stress is difficult to be unevenly distributed, the generation of strain can be suppressed, which can contribute to the suppression of film warping caused by curing shrinkage and the like.

[0102] The average particle diameter of the particles is, for example, about 5 nm to 10 μm. From the viewpoint of enhancing the transparency of the hard coat layer, the average particle diameter is preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 300 nm or less, and particularly preferably 100 nm or less. The particle diameter can be measured by a laser diffraction / scattering type particle size distribution measuring device, and the volume-based median diameter is taken as the average particle diameter.

[0103] The hard coat composition may contain surface-modified particles. When the particles are surface-modified, the dispersibility of the particles in the polyorganosiloxane compound tends to be improved. Further, when the particle surface is modified with a polymerizable functional group capable of reacting with an epoxy group, the functional group on the particle surface reacts with the epoxy group of the above polyorganosiloxane compound to form a chemical crosslink, so that an improvement in film strength can be expected.

[0104] Examples of the polymerizable functional group capable of reacting with an epoxy group include a vinyl group, (meth)acrylic group, hydroxyl group, phenolic hydroxyl group, carboxyl group, acid anhydride group, amino group, epoxy group, oxetane group, etc. Among them, an epoxy group is preferable. In particular, when curing the hard coat composition by photo cationic polymerization, particles surface-modified with an epoxy group are preferable because a chemical crosslink can be formed between the particles and the polyorganosiloxane compound.

[0105] Examples of the particles having a reactive functional group on the surface include surface-modified inorganic particles and core-shell polymer particles.

[0106] <Solvent> The hard coat composition may be a solvent-free type or may contain a solvent. When containing a solvent, it is preferable that the solvent does not dissolve the transparent resin substrate. On the other hand, by using a solvent having a solubility to swell the transparent resin substrate, the adhesion between the transparent resin substrate and the hard coat layer may be improved. The content of the solvent 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 with respect to 100 parts by weight of the polyorganosiloxane compound.

[0107] <Additive> The hard coat composition may contain additives such as inorganic pigments, organic pigments, surface conditioners, surface modifiers, plasticizers, dispersants, wetting agents, thickeners, defoamers, etc. Further, the hard coat composition may contain a thermoplastic or thermosetting resin material other than the above polyorganosiloxane compound. When the polyorganosiloxane compound and / or the resin material other than the polyorganosiloxane compound has radical polymerizability, the hard coat composition may contain a radical polymerization initiator in addition to the photo cationic polymerization initiator.

[0108] [Hard Coat Film] A hard coat film is obtained by applying a hard coat composition onto a transparent resin substrate, drying and removing the solvent as necessary, and then irradiating with active energy rays to cure the hard coat composition. The hard coat layer may be formed on only one main surface of the transparent resin substrate, or may be formed on both main surfaces of the transparent resin substrate.

[0109] <Transparent resin substrate> The transparent resin substrate is a film substrate that serves as a base for forming the hard coat layer. The total light transmittance of the transparent resin substrate is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The haze of the transparent resin substrate is preferably 2% or less, and more preferably 1% or less.

[0110] The thickness of the transparent resin substrate is not particularly limited. For example, it is 1 to 1000 μm, preferably 5 to 500 μm, more preferably 10 to 200 μm, and even more preferably 15 to 150 μm.

[0111] The resin material constituting the transparent resin substrate is not particularly limited as long as it is a transparent resin. Examples of the transparent resin 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 cellulose-based resins such as triacetyl cellulose (TAC).

[0112] Among them, polyesters such as PET and transparent polyimide are preferred because of their high mechanical strength. When the hard coat film is used for the cover window of a display, excellent heat resistance and mechanical strength are required for the film substrate. Therefore, transparent polyimide is particularly preferred as the resin material of the transparent resin substrate. In contrast to general fully aromatic polyimides which are colored yellow or brown, transparent polyimides with high visible light transmittance can be obtained by introducing an alicyclic structure, a bent structure, a fluorine substituent, etc.

[0113] The transparent resin substrate may be a single layer or a multi-layer structure. For example, the transparent resin substrate may be a laminate in which a plurality of films are laminated, or may be one provided with functional layers such as an easy adhesion layer, an antistatic layer, and an antireflection layer on the hard coat layer forming surface and / or the non-hard coat layer forming surface of the film substrate. Further, the transparent resin substrate may be provided with a hard coat layer formed of a material other than the above polyorganosiloxane compound on one main surface.

[0114] <Formation of Hard Coat Layer> As described above, a hard coat layer is formed by applying and curing a hard coat composition on the transparent resin substrate. Before applying the hard coat composition, surface treatment such as corona treatment or plasma treatment may be performed on the surface of the transparent resin substrate. Further, an easy adhesion layer (primer layer) or the like may be provided on the surface of the transparent resin substrate. Note that since the hard coat layer formed by curing the hard coat composition containing the above polyorganosiloxane compound exhibits high adhesion to the transparent resin substrate, it is not necessary to provide an easy adhesion layer or the like. That is, in the hard coat film, the transparent resin substrate and the hard coat layer may be in contact with each other.

[0115] By irradiating the hard coat composition with active energy rays, an acid is generated from the photo cationic polymerization initiator, and the epoxy groups of the polyorganosiloxane compound are ring-opened and cationically polymerized, whereby the curing proceeds. When the hard coat composition contains a reactive diluent, in addition to the polymerization reaction between the polyorganosiloxane compounds, a polymerization reaction between the epoxy group of the polyorganosiloxane compound and the reactive diluent also occurs. Further, when the hard coat composition contains particles having reactive functional groups on the surface, the functional groups on the particle surface may react with the epoxy groups of the polyorganosiloxane compound to form a chemical crosslink.

[0116] Examples of the active energy rays irradiated during photocuring include visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, γ-rays, electron beams, and the like. Since the curing reaction rate is high and the energy efficiency is excellent, ultraviolet rays are preferred as the active energy rays. The integrated irradiation dose of the active energy rays is, for example, about 50 to 10,000 mJ / cm 2 and may be set according to the type and blending amount of the photo cationic polymerization initiator, the thickness of the hard coat layer, and the like. The curing temperature is not particularly limited, but is usually 100°C or lower.

[0117] The thickness of the hard coat layer is preferably 0.5 μm or more, more preferably 2 μm or more, still 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 viewpoints of transparency and flex resistance, 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.

[0118] 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 still more preferably 20 to 200 μm. The ratio of the thickness of the hard coat layer to the thickness of the transparent resin substrate (hard coat layer thickness / transparent resin substrate thickness) in the hard coat film is not particularly limited and may be appropriately selected, for example, from between 1 / 10 and 10 / 1.

[0119] [Properties of the Hard Coat Film] The hard coat layer formed by curing the above hard coat composition has excellent adhesion to the transparent resin substrate. Further, since the hard coat composition has a polymer matrix in which a polyorganosiloxane compound is crosslinked by ring-opening and polymerization reactions of epoxy groups, a surface hardness comparable to that of glass can be achieved. The surface hardness (pencil hardness) of the hard coat layer forming surface of the hard coat film is preferably HB or more, more preferably H or more, still more preferably 2H or more, and may be 3H or more or 4H or more.

[0120] The hard coat film has high surface hardness as described above and is also excellent in flexural resistance. When a cylindrical mandrel test is performed with the hard coat layer forming surface facing outward, the mandrel diameter at which cracks occur in the hard coat layer is preferably 8 mm or less, more preferably 6 mm or less, and may be 4 mm or less, or 2 mm or less.

[0121] The total light transmittance of the hard coat film is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more. Also, the haze of the hard coat film is preferably 1.5% or less, more preferably 0.9% or less, even more preferably 0.6% or less, and particularly preferably 0.5% or less.

[0122] When a damp heat test is performed by leaving the hard coat film stationary in an environment of 60°C and 90% humidity for 24 hours, the change amount of haze ΔHaze is preferably 0.3% or less, more preferably 0.2% or less, and even more preferably 0.1% or less. As described above, by using a non-antimony-based photo cationic polymerization initiator (photoacid generator), bleeding out of residues and the like is less likely to occur, and the increase in haze due to the damp heat test tends to be suppressed.

[0123] [Application of Hard Coat Film] Various functional layers may be provided on the hard coat layer or on the non-hard coat layer forming surface of the transparent resin substrate of the hard coat film. Examples of the functional layer include an antireflection layer, an antiglare layer, an antistatic layer, and a transparent electrode. Also, a transparent adhesive layer may be attached to the hard coat film.

[0124] The hard coat film of the present invention has high transparency and excellent mechanical strength, and thus can be suitably used for a cover window provided on the surface of an image display panel, a transparent substrate for a display, a transparent substrate for a touch panel, a substrate for a solar cell, and the like. In addition to transparency and mechanical strength, the hard coat film of the present invention is also excellent in bending resistance, and thus can be particularly suitably used as a cover window or a substrate film for a curved display, a flexible display, or the like.

Examples

[0125] Hereinafter, production examples of a polyorganosiloxane compound and a hard coat film will be shown to more specifically explain the present invention, but the present invention is not limited to the following examples.

[0126] [Synthesis of polyorganosiloxane compound] <Synthesis Example 1> Into a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 67.4 g (220 mmol) of 8-glycidyloxyoctyltrimethoxysilane (“KBM-4803” manufactured by Shin-Etsu Chemical Co., Ltd.) and 11.6 g of methanol were charged and stirred uniformly. To this mixed solution, a solution prepared by dissolving 0.010 g (0.11 mmol) of magnesium chloride in a mixed solution of 11.9 g (660 mmol) of water and 4.7 g of methanol was added dropwise over 5 minutes and stirred until uniform. Thereafter, the temperature was raised to 70° C., and a polycondensation reaction was carried out for 6 hours with stirring. After completion of the reaction, methanol and water were removed by a rotary evaporator to obtain a polyorganosiloxane compound 1 having an epoxy group.

[0127] <Synthesis Example 2> Into a reaction vessel equipped with a thermometer, a stirring device, and a reflux condenser, 69.0 g (225 mmol) of 8-glycidyloxyoctyltrimethoxysilane, 6.2 g (25 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (SILQUEST A-186 manufactured by Momentive Performance Materials), and 15.3 g of 1-methoxy-2-propanol (PGME) were charged and stirred uniformly. To this mixed solution, a solution prepared by dissolving 0.012 g (0.125 mmol) of magnesium chloride in a mixed solution of 13.5 g (750 mmol) of water and 5.4 g of methanol was added dropwise over 5 minutes and stirred until homogeneous. Then, the temperature was raised to 80 °C, and a polycondensation reaction was carried out for 6 hours with stirring. After completion of the reaction, the solvent was distilled off using a rotary evaporator to obtain a polyorganosiloxane compound 2 having an epoxy group.

[0128] <Synthesis Examples 3 to 5> Polyorganosiloxane compounds 3 to 5 were obtained in the same manner as in Synthesis Example 2, except that the ratio of 8-glycidyloxyoctyltrimethoxysilane to 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was changed as shown in Table 1.

[0129] <Synthesis Example 6> Into a reaction vessel equipped with a thermometer, a stirring device, and a reflux condenser, 66.5 g (270 mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 16.5 g of PGME were charged and stirred uniformly. To this mixed solution, a solution prepared by dissolving 0.039 g (0.405 mmol) of magnesium chloride in a mixed solution of 9.7 g (539 mmol) of water and 5.8 g of methanol was added dropwise over 5 minutes and stirred until homogeneous. Then, the temperature was raised to 80 °C, and a polycondensation reaction was carried out for 6 hours with stirring. After completion of the reaction, the solvent was distilled off using a rotary evaporator to obtain a polyorganosiloxane compound 6.

[0130] <Synthesis Example 7> A reaction vessel equipped with a thermometer, a stirring device, and a reflux condenser was charged with 63.8 g (270 mmol) of 3-glycidyloxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) and 16.5 g of PGME, and the mixture was stirred uniformly. To this mixed solution, a solution prepared by dissolving 0.013 g (0.135 mmol) of magnesium chloride in a mixed solution of 14.6 g (810 mmol) of water and 5.8 g of methanol was added dropwise over 5 minutes, and the mixture was stirred until it became uniform. Then, the temperature was raised to 80°C, and a polycondensation reaction was carried out for 6 hours with stirring. After completion of the reaction, the solvent was distilled off using a rotary evaporator to obtain a polyorganosiloxane compound 7.

[0131] <Synthesis Example 8> A reaction vessel equipped with a thermometer, a stirring device, and a reflux condenser was charged with 46.0 g (150 mmol) of 8-glycidyloxyoctyltrimethoxysilane and 9.2 g of PGME, and the mixture was stirred uniformly. To this mixed solution, a solution prepared by dissolving 0.0052 g (0.0375 mmol) of potassium carbonate in a mixed solution of 8.1 g (450 mmol) of water and 3.2 g of methanol was added dropwise over 5 minutes, and the mixture was stirred until it became uniform. Then, the temperature was raised to 80°C, and a polycondensation reaction was carried out for 6 hours with stirring. After completion of the reaction, the solvent was distilled off using a rotary evaporator to obtain a polyorganosiloxane compound 8 having an epoxy group.

[0132] <Synthesis Example 9> A condensation reaction and solvent distillation were carried out in the same manner as in Synthesis Example 8, except that the amount of the condensation catalyst (potassium carbonate) was changed to 0.0104 g (0.075 mmol), to obtain a polyorganosiloxane compound 9.

[0133] [Evaluation of Compounds] For the polyorganosiloxane compounds 1 to 9 obtained in Synthesis Examples 1 to 9, the weight-average molecular weight Mw, the T3 / T2 ratio, and the residual ratio of the epoxy group were measured by the following methods. The amount of the residual catalyst was calculated based on the charged amounts of the silane compound and the catalyst in the reaction.

[0134] <Weight-average molecular weight Mw> Using the GPC device "HLC-8220GPC" manufactured by Tosoh Corporation (columns: two TSKgel GMHXL, TSKgel G3000HXL, TSKgel G2000HXL), measurements were carried out using THF as a solvent, and the weight-average molecular weight in terms of polystyrene was calculated.

[0135] <T3 / T2 ratio> Using an NMR (600 MHz) manufactured by Agilent, 29 the Si-NMR spectrum was measured, and the ratio T3 / T2 (molar ratio) of the SiO 3 / 2 body (T3 structure) to the SiO 2 / 2 body (T2 structure) was determined.

[0136] <Residual ratio of epoxy groups> Using an NMR (400 MHz) manufactured by Bruker, with deuterated acetone as a solvent, 1 the 1H-NMR spectrum was measured to determine the remaining amount of epoxy groups. For all of the polyorganosiloxane compounds 1 to 9, the residual ratio of epoxy groups was 95% or more.

[0137] The amounts of raw materials (silane compounds) used, the types of condensation catalysts, and the evaluation results (catalyst content, T3 / T2 ratio, and weight-average molecular weight Mw) of the polyorganosiloxane compounds in Synthesis Examples 1 to 9 are shown in Table 1.

[0138]

Table 1

[0139] For the polyorganosiloxane compounds in Synthesis Examples 1 to 7 using magnesium chloride, a neutral salt catalyst, as the condensation catalyst, the T3 / T2 ratio was less than 5, whereas in Synthesis Examples 8 and 9 using potassium carbonate, the T3 / T2 ratio of the polyorganosiloxane compounds exceeded 5. From these results, it can be seen that by carrying out the condensation reaction of silane compounds using a neutral salt catalyst, a polyorganosiloxane compound with a small ratio of the SiO 3 / 2 body (T3 structure) can be obtained.

[0140] [Preparation of Hard Coat Composition] <Hard Coat Composition 1 To 100 parts by weight of the polyorganosiloxane compound 1 obtained in Synthesis Example 1, 0.5 part by weight of a 50% solution of triarylsulfonium·P(Rf) n F 6-n salt (manufactured by San-Apro, "CPI-200K") in propylene carbonate and 0.125 part by weight of a 52% solution of polyether-modified polydimethylsiloxane in xylene / isobutanol (manufactured by BYK, "BYK-300") as a leveling agent were added to obtain Hard Coat Composition 1. The above blending amounts are the solid contents of each component.

[0141] <Hard Coat Compositions 2 to 5, 7 to 9 Instead of the polyorganosiloxane compound 1, polyorganosiloxane compounds 2 to 5, 7 to 9 were used, and a hard coat composition was prepared by blending a photo cationic polymerization initiator and a leveling agent. In preparing the composition, PGME was blended as a diluting solvent to adjust the viscosity of the solution (see Table 2 for the blending amount).

[0142] <Hard Coat Composition 6 To 100 parts by weight of the polyorganosiloxane compound 6 obtained in Synthesis Example 6, 0.2 part by weight of a 50% solution of diphenyl(4-phenylthiophenyl)sulfonium·SbF6 (manufactured by San-Apro, "CPI-101A") in propylene carbonate as a photo cationic polymerization initiator, 0.25 part by weight of a leveling agent (manufactured by BYK, "BYK-300"), and 99.3 parts by weight of PGME as a diluting solvent were added to obtain Hard Coat Composition 6 with a total solid content concentration of 50% by weight. The above blending amounts are the solid contents of each component.

[0143] <Hard Coat Composition 10 As a photo cationic polymerization initiator, a 50% solution of diphenyl(4-phenylthiophenyl)sulfonium·SbF6 (manufactured by San-Apro, "CPI-101A") in propylene carbonate was used, and 24.2 parts by weight of PGME was blended as a diluting solvent. Otherwise, in the same manner as the preparation of the hard coat composition 1, a hard coat composition 10 with a total solid content concentration of 80% by weight was obtained.

[0144] [Fabrication of Hard Coat Film] <Hard Coat Film 1> On one surface of the transparent polyimide film (thickness: 50 μm) of Example 12 of WO2020 / 004236, the hard coat composition 1 was applied using a bar coater so that the film thickness after heating would be 10 μm, and then heated at 120°C for 10 minutes. Thereafter, using a high-pressure mercury lamp, ultraviolet rays were irradiated so that the integrated light quantity with a wavelength of 250 to 390 nm would be 1000 mJ / cm 2 to cure the hard coat composition, and a hard coat film 1 having a hard coat layer with a thickness of 10 μm on one surface of the transparent polyimide film was obtained.

[0145] <Hard Coat Films 2 to 5> The coating thickness of the hard coat composition was changed so that the thickness of the hard coat (HC) layer would be the value shown in Table 1. Otherwise, in the same manner as the fabrication of the hard coat film 1, using the hard coat composition 1, a hard coat layer was formed on one surface of the transparent polyimide film to fabricate hard coat films 2 to 5.

[0146] <Hard Coat Film 6> The hard coat composition 6 was applied using a bar coater so that the dry film thickness (film thickness after heating) became 50 μm, and heating and curing were performed in the same manner as in Production Example 1 to produce a hard coat film having a hard coat layer with a thickness of 50 μm on one surface of a transparent polyimide film. On the surface of this hard coat film where the hard coat layer was not formed, the hard coat composition 1 was applied using a bar coater so that the dry film thickness became 50 μm, and heating and curing were performed to produce a hard coat film 6 having hard coat layers with a thickness of 50 μm on both surfaces of the transparent polyimide film.

[0147] <Hard coat film 7> A hard coat film 7 having a hard coat layer with a thickness of 50 μm on one surface of a PET film was produced in the same manner as the production of the hard coat film 3, except that a polyethylene terephthalate (PET) film with a thickness of 50 μm (Lumirror 50U48 manufactured by Toray Industries, Inc.) was used instead of the transparent polyimide film.

[0148] <Hard coat film 8> A hard coat film 8 having a hard coat layer with a thickness of 50 μm on one surface of a transparent polyimide film was produced in the same manner as the production of the hard coat film 3, except that a hard coat composition 10 containing an antimony-based photo cationic polymerization initiator was used instead of the hard coat composition 1.

[0149] <Hard coat films 9 to 16> Hard coat films 9 to 16 having hard coat layers with a thickness of 50 μm on one surface of a transparent polyimide film were produced in the same manner as the production of the hard coat film 3, except that hard coat compositions 2 to 9 were used instead of the hard coat composition 1.

[0150] [Evaluation of hard coat film] The above hard coat films 1 to 16 were evaluated by the following method.

[0151] [Surface hardness and adhesion] In accordance with JIS K5600-5-4:1999, the pencil hardness of the hard coat layer forming surface was measured under a load of 750 g. For the hard coat film 6 having hard coat layers on both sides, evaluation was carried out on the surface on the hard coat layer side formed using the hard coat composition 1 (polyorganosiloxane compound 1). When the test was conducted using a pencil with a hardness of H, those with no peeling in the hard coat layer were rated as having good adhesion (OK), and those with peeling observed in the hard coat layer were rated as having poor adhesion (NG). For the films 15 and 16 with poor adhesion, evaluation of the surface hardness was not performed.

[0152] <Mandrel Test> In accordance with JIS K5600-5-1:1999, a cylindrical mandrel test was conducted using a type 1 testing machine with the hard coat layer forming surface on the outside. For the hard coat film 6, the test was conducted with the surface on the hard coat layer side formed using the hard coat composition 1 on the outside. The smaller the diameter φ of the mandrel, the better the flex resistance.

[0153] <Total Light Transmittance and Haze> Measurement was carried out by the method described in JIS K7361-1:1999 and JIS K7136:2000 using a haze meter "HZ-V3" manufactured by Suga Test Instruments Co., Ltd. In the measurement, a D65 light source was used, and the total light transmittance was calculated as the ratio of the total transmitted light beam (parallel light component and diffused light component) to the parallel incident light beam on the hard coat film.

[0154] <Change in Haze by Damp Heat Test> The hard coat film was left standing in a thermo-hygrostat set at a temperature of 60°C and a humidity of 90% for 24 hours, and then the haze was measured by the above method. The change amount of haze ΔHaze (=[Haze of the hard coat film after the damp heat test] - [Haze of the hard coat film before the damp heat test]) before and after the damp heat test was calculated.

[0155] <Surface Tackiness> Place the hard coat film on a horizontal table with the hard coat layer forming surface facing upward (in the case of the hard coat film 6, the hard coat layer formed using the hard coat composition 1 is on the upper side). Place a PET film with a thickness of 75 μm on the hard coat layer and press it for 1 second with a load of 10 N / cm 2 After unloading, visually check whether there is adhesion (blocking) between the hard coat layer and the PET film. Those with no adhesion are rated as A, those with adhesion but the area is within 30% of the loaded area are rated as B, and those with adhesion in an area larger than 30% are rated as C.

[0156] Table 2 shows the composition of the hard coat compositions used to produce the hard coat films 1 to 16, the thicknesses of the hard coat layer and the hard coat films, and the evaluation results of the hard coat films. The compositions in Table 2 represent the blending amounts of the polymerization initiator, leveling agent, and solvent in parts by weight with respect to 100 parts by weight of the polyorganosiloxane compound.

[0157]

Table 2

[0158] The hard coat film 14 is formed with a hard coat layer using a polyorganosiloxane compound 7 which is a condensate of a silane compound (3-glycidyloxypropyltrimethoxysilane) in which an Si atom and a glycidyloxy group are bonded via a propylene group. The result of the mandrel test for this hard coat film 14 is 10 mm, indicating that the flex resistance of the hard coat layer is not sufficient.

[0159] The hard coat film 13 is formed by using a polyorganosiloxane compound 6 which is a condensate of a silane compound (2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane) in which an Si atom and an alicyclic epoxy group are bonded via an ethylene group to form a hard coat layer. Although the tackiness of the surface of the hard coat layer of this hard coat film 13 was improved, the mandrel diameter was 32 mm and the flex resistance of the hard coat layer was poor.

[0160] The hard coat films 1 to 5 are formed by using a polyorganosiloxane compound 1 which is a condensate of a silane compound (8-glycidyloxyoctyltrimethoxysilane) in which an Si atom and a glycidyloxy group are bonded via an octylene group to form a hard coat layer. In these hard coat films 1 to 5, the mandrel diameter tended to increase (flex resistance decreased) as the thickness of the hard coat layer increased. However, even when the thickness of the hard coat layer was increased to 75 μm, the mandrel diameter was 6 mm, indicating excellent flex resistance. The hard coat film 6 with hard coat layers formed on both sides and the hard coat film 7 using a PET film substrate also showed excellent flex resistance, similar to the hard coat films 1 to 5.

[0161] In the hard coat films 15 and 16 formed by using polyorganosiloxane compounds 8 and 9 with a high ratio of T3 structure to form a hard coat layer, the mandrel diameter was larger and the flex resistance was lower compared to the hard coat film 3. Also, in the hard coat films 15 and 16, the adhesion of the hard coat layer to the transparent polyimide film was poor.

[0162] From the above results, it can be seen that by using a polyorganosiloxane compound which is a condensate of a silane compound in which an Si atom and a glycidyloxy group are bonded via an alkylene group having 4 or more carbon atoms and having a small ratio of T3 structure (T3 / T2 ratio less than 5), a hard coat layer excellent in hardness, adhesion and flex resistance can be formed.

[0163] The hard coat film 8 formed by using the composition 10 containing an antimony-based photo cationic polymerization initiator exhibited a mandrel diameter (flexural resistance) equivalent to that of the hard coat film 3. However, its surface hardness was lower than that of the hard coat film 3, and an increase in haze was observed after the damp heat test. From these results, it can be seen that by using a non-antimony-based photo cationic polymerization initiator, the hardness and the damp heat resistance (transparency after the damp heat test) of the hard coat layer tend to be improved compared to the case of using an antimony-based photo polymerization initiator.

[0164] In the hard coat films 9 to 12, as the silane compound, in addition to 8-glycidyloxyoctyltrimethoxysilane, a polyorganosiloxane compound 9 to 12 condensed by using 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, which is a silane compound containing an alicyclic epoxy group, in combination was used to form the hard coat layer. In these hard coat films 9 to 12, the tackiness of the hard coat layer surface was improved, and it is considered that the high photo cationic polymerizability of the alicyclic epoxy group is involved in the improvement of the tackiness. In addition, in the hard coat films 9 to 12, a tendency for the flexural resistance to decrease was observed as the amount of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane used increased. Therefore, from the viewpoint of the flexural resistance of the hard coat layer, it can be said that it is preferable to reduce the ratio of the silane compound containing an alicyclic epoxy group within the range where the tackiness can be improved.

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, wherein the hard coat composition contains a polyorganosiloxane compound which is a condensate of a silane compound represented by the general formula (A), Q-(Si(OR ２ )) ｘ R ３ ３－ｘ )…(A) the polyorganosiloxane compound, has a weight average molecular weight of 500 to 20,000, contains a T3 structure represented by the general formula (3) and a T2 structure represented by the general formula (4), [Q - SiO ３／２ …(3) [Q - SiO ２／２ - Z] …(4) the ratio T3 / T2 of the content of the T3 structure to the T2 structure is less than 5, the ratio of the structure represented by the general formula (5) to the total number of Si atoms is 60% or more, [Y-R １ -Si] …(5) a hard coat film (however, excluding those in which the hard coat composition contains silica fine particles): In the general formula (5), Y is a glycidyloxy group, and R1 is a chain alkylene group having 4 to 16 carbon atoms in the main chain; In general formula (A), R ２ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ３ 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, Q is a monovalent organic group, x is 2 or 3; in the silane compound represented by the general formula (A), the ratio of those in which Q is a monovalent organic group containing an epoxy group is 90 mol% or more; in the general formula (3) and the general formula (4), Q is the same as in the general formula (A); in the general formula (4), Z is a monovalent organic group selected from the group consisting of a hydrogen atom, an alkoxy group having an alkyl group having 1 to 10 carbon atoms, 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.

2. The hard coat film according to claim 1, wherein the polyorganosiloxane compound further contains a structure represented by the general formula (6), and the ratio of the structure represented by the general formula (6) to the total number of Si atoms is 1 to 40%: [X-Si] …(6) In the general formula (6), X is a monovalent organic group containing an alicyclic epoxy group.

3. The hard coat composition contains a neutral salt composed of a combination of an ion of an element selected from the group consisting of an alkali metal element and a Group 2 element and a halide ion selected from the group consisting of a chloride ion, a bromide ion, and an iodide ion, and the concentration of the neutral salt is 1 ppm to 10,000 ppm based on the polyorganosiloxane compound. The hard coat film according to claim 1 or 2.

4. The hard coat film according to any one of claims 1 to 3, wherein the hard coat composition further contains a photo cationic polymerization initiator.

5. The hard coat film according to claim 4, wherein the photo cationic polymerization initiator does not contain antimony.

6. The hard coat film according to any one of claims 1 to 5, wherein the hard coat composition does not contain particles.

7. The hard coat film according to any one of claims 1 to 6, wherein the thickness of the hard coat layer is 0.5 to 100 μm.

8. The hard coat film according to any one of claims 1 to 7, wherein the transparent resin substrate contains one or more resin materials selected from the group consisting of polyester, polycarbonate, polyamide, polyimide, cyclic polyolefin, acrylic resin, and cellulose-based resin.

9. A method for producing a hard coat film according to any one of claims 1 to 8, The method for producing a hard coat film, comprising applying the hard coat composition onto a transparent resin substrate and irradiating active energy rays to cure the hard coat composition to form the hard coat layer.

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