Manufacturing method of hard coat film

Abstract

A hardcoat film (10) is provided with a transparent resin film (1) and a hardcoat layer (3) disposed on one surface thereof, the hardcoat layer being formed from a cured product of a hardcoat composition. The thickness of the hardcoat layer is at least 0.15 times the thickness of the transparent resin film. The hardcoat composition has a negative cure shrinkage. Preferably the absolute value of the amount of curl of the hardcoat film cut into a 100 mm × 100 mm square is 20 mm or less. The hardcoat layer optionally contains a cured product of a polyorganosiloxane compound having alicyclic epoxy groups.

Description

[Technical field]

[0001] The present invention relates to a hard coat film having a hard coat layer on a main surface of a transparent resin film. M Regarding the manufacturing method 。 [Background technology]

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

[0003] Patent Document 1 discloses a hard coat film in which a hard coat layer made of an acrylic material is provided on a polyethylene terephthalate film as a transparent substrate material for flexible displays. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-69197 A Summary of the Invention [Problem to be solved by the invention]

[0005] A high hardness is required for a member arranged on a display surface such as a cover window, and accordingly, a hard coat film having a hard coat layer with a large thickness is required. However, when the thickness of the hard coat layer of a hard coat film made using an acrylic hard coat material is increased, the film may warp (curl) with the hard coat layer surface facing inward, making the film difficult to handle. In view of the above, the present invention aims to provide a hard coat film in which curling is suppressed even when the hard coat layer is thick. [Means for solving the problem]

[0006] The present inventors have found that the amount of curl in a hard coat film can be controlled by applying a material having a negative cure shrinkage rate to the hard coat layer, and have arrived at the present invention.

[0007] One embodiment of the present invention is a hard coat film having a hard coat layer on one main surface of a transparent resin film. The hard coat layer is formed by applying a hard coat composition to the main surface of the transparent resin film and irradiating the hard coat composition with active energy rays.

[0008] Examples of the resin material of the transparent resin film include polyester, polycarbonate, polyamide, polyimide, cyclic polyolefin, acrylic resin, cellulose-based resin, etc. The transparent resin film may have a thickness of 10 to 150 μm.

[0009] The thickness of the hard coat layer is 0.15 times or more that of the transparent resin film. The thickness of the hard coat layer may be 3 times or less that of the transparent resin film. The thickness of the hard coat layer may be 2 to 150 μm.

[0010] The hard coat composition used has a negative cure shrinkage rate. The hard coat composition may contain a polyorganosiloxane compound having an alicyclic epoxy group. The weight average molecular weight of the polyorganosiloxane compound may be 500 to 20,000.

[0011] The polyorganosiloxane compound having an alicyclic epoxy group can be obtained, for example, by condensation of a silane compound having an alicyclic epoxy group. The hard coat composition may contain a photocationic polymerization initiator.

[0012] When the hard coat composition is cured on the transparent resin film, it may be irradiated with active energy rays in a heated atmosphere. The heating temperature may be 45 to 150° C. The hard coat composition may be irradiated with active energy rays in a state where a support film is attached to the surface of the transparent resin film on which the hard coat layer is not formed. After the hard coat composition is irradiated with active energy rays, it may be further heated.

[0013] The absolute value of the curl amount of the hard coat film cut into a square of 100 mm×100 mm is preferably 20 mm or less. The linear expansion coefficient of the hard coat layer may be higher than the linear expansion coefficient of the transparent resin film. Effect of the Invention

[0014] According to the present invention, a hard coat film having a thick hard coat layer and little curl can be obtained. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a cross-sectional view of a hard coat film. [Diagram 2] 1 is a cross-sectional view of a laminate in which a support film is bonded to a transparent resin film. [Diagram 3] FIG. 2 is a cross-sectional view of a hard coat film to which a support film is attached. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Hard coat film overview] 1 is a cross-sectional view of a laminate according to one embodiment of the present invention. The laminate 10 is a hard coat film having a hard coat layer 3 on one main surface 1A of a transparent resin film.

[0017] The transparent resin film 1 is a flexible film substrate that serves as a base for forming a hard coat layer. The total light transmittance of the transparent resin film is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The haze of the transparent resin film is preferably 2% or less, and more preferably 1% or less.

[0018] The resin material constituting the transparent resin film is not particularly limited as long as it is a transparent resin, and examples of the transparent resin include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonates, polyamides, transparent polyimides, cyclic polyolefins, acrylic resins such as polymethyl methacrylate (PMMA), and cellulose-based resins such as triacetyl cellulose (TAC).

[0019] Among them, polyester 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, the film substrate is required to have excellent heat resistance and mechanical strength, so transparent polyimide is particularly preferred as the resin material of the transparent resin film. While general wholly aromatic polyimides are colored yellow or brown, transparent polyimides with high visible light transmittance can be obtained by introducing an alicyclic structure, a bent structure, or a fluorine substituent.

[0020] The transparent resin film may be a single layer or a multilayer structure. For example, the transparent resin film may be a laminate in which a plurality of films are laminated together, and may have a functional layer such as an easy-adhesion layer, an antistatic layer, or an antireflection layer provided on the surface on which the hard coat layer is formed (first main surface 1A) and / or the surface on which the hard coat layer is not formed (second main surface 1B).

[0021] The thickness of the transparent resin film is not particularly limited, but is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. The thickness of the transparent resin film is preferably 150 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, and particularly preferably 60 μm or less. If the transparent resin film is too thin, the mechanical properties such as the surface hardness of the hard coat film may be insufficient. On the other hand, if the transparent resin film is too thick, the transparency and flexibility of the hard coat film may be reduced.

[0022] The thickness of the hard coat layer 3 is not particularly limited, but from the viewpoint of surface hardness, it is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, and may be 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. From the viewpoint of transparency and flexibility (flex resistance), the thickness of the hard coat layer is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 90 μm or less, and may be 80 μm or less, or 70 μm or less.

[0023] The total thickness of the hard coat film, i.e., the sum of the thickness of the transparent resin film 1 and the thickness of the hard coat layer 3, is about 15 to 1000 μm, preferably 20 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, and particularly preferably 50 μm or more. The total thickness of the hard coat film is preferably 250 μm or less, more preferably 170 μm or less, even more preferably 150 μm or less, and particularly preferably 110 μm or less.

[0024] The ratio d2 / d1 of the thickness d2 of the hard coat layer 3 to the thickness d1 of the transparent resin film 1 is 0.15 or more, preferably 0.20 or more, more preferably 0.40 or more, and may be 0.60 or more, 0.80 or more, or 1.00 or more. In general, when the thickness d2 of the hard coat layer is large and d2 / d1 is large, the curl of the hard coat film tends to increase, but as described later, by using a hard coat material having a negative cure shrinkage rate, the curl tends to be reduced. The upper limit of the thickness ratio d2 / d1 is not particularly limited, but from the viewpoint of the formability and flexibility of the hard coat layer, d2 / d1 is preferably 3.00 or less, more preferably 2.00 or less, even more preferably 1.80 or less, and may be 1.60 or less or 1.40 or less.

[0025] The linear expansion coefficient of the hard coat layer 3 is preferably larger than that of the transparent resin film 1. The linear expansion coefficient is a value calculated from a thermomechanical analysis (TMA) curve when cooling from a temperature of 100° C. to 30° C. The linear expansion coefficient of the hard coat layer in the hard coat film is measured using a sample in which the transparent resin film is dissolved in a solvent or the like to isolate the hard coat layer.

[0026] Since the linear expansion coefficient of the hard coat layer is relatively large, the stress generated at the interface between the hard coat layer and the transparent resin film during curing of a hard coat material having a negative cure shrinkage coefficient is canceled by the stress generated at the interface due to the difference in linear expansion coefficient (difference in the amount of dimensional change upon heating), so that the curl of the hard coat film can be controlled to a desired value.

[0027] From the viewpoint of stability in controlling curling of the hard coat film, the difference in linear expansion coefficient between the transparent resin film and the hard coat layer is preferably 100 ppm / ° C. or less, more preferably 70 ppm / ° C. or less, and further preferably 50 ppm / ° C. or less. The difference in linear expansion coefficient is preferably 5 ppm / ° C. or more, and may be 10 ppm / ° C. or more, 20 ppm / ° C. or more, or 30 ppm / ° C. or more.

[0028] The hard coat film is preferably such that the absolute value of the curl amount of a sample cut into a 100 mm x 100 mm square is 20 mm or less at room temperature (25°C). The curl amount of the hard coat film is evaluated by placing the surface on which the hard coat layer 3 is formed on a horizontal stand with the surface on top. The distances from the stand to the four vertices of the square (the amount of lift) are measured, and the average value is taken as the curl amount. If the central part of the film surface is lifted (if curl occurs in the opposite direction), the film is placed on the stand with the surface on which the hard coat layer is formed on the bottom, and the curl amount is measured. In this case, the curl amount is a negative value.

[0029] When the hard coat material is photocationically curable, the acid generated as an active species by irradiating a photocationic polymerization initiator (photoacid generator) with light has a longer life than photoradicals, and the curing reaction continues for several days after irradiation. As a result, the amount of curl due to dimensional changes in the hard coat layer may change over time. To reduce the effect of changes over time, the curl amount is measured 10 days after the curing process (photocuring).

[0030] In the manufacturing process of displays and the like that include a hard coat film, the hard coat film may be cut into sheets of a predetermined size and then placed on a belt conveyor or the like for transport. In this case, if the amount of downward curl is large, the end of the film may get into the gap between the conveyors, causing the film to fall from the transport device. In addition, if the amount of upward curl is large, when the hard coat film is suction-fixed from the bottom surface for printing or the like, the gap between the suction device and the film may be large, making suction fixation difficult.

[0031] Therefore, it is preferable that the hard coat film has a small curl amount regardless of whether the hard coat layer is disposed on the upper surface or the lower surface. The absolute value of the curl amount of the hard coat film cut into a 100 mm x 100 mm square is more preferably 15 mm or less, further preferably 10 mm or less, may be 7 mm or less or 5 mm or less, and is ideally 0.

[0032] In the present invention, a material having a negative cure shrinkage rate, that is, a material that expands and increases in volume upon curing, is used as the hard coat material. The cure shrinkage rate of the hard coat material is a volumetric shrinkage rate determined by a density method in accordance with JIS K6901:2008, and is defined as follows: ρ C is the density after hardening, ρ L is the density before hardening. The density of the liquid is measured by the pycnometer method, and the density of the solid is measured by the density gradient tube method. Curing shrinkage rate (%)=100×(ρ C -ρ L ) / ρ C

[0033] Since general hard coat materials such as acrylics have a positive cure shrinkage rate (shrinks with cure), when the thickness of the hard coat layer increases, the compressive stress at the interface between the transparent resin film and the hard coat layer increases, and the warping (curling) of the film with the hard coat layer formed surface on the inside tends to increase. In contrast, when the hard coat material has a negative cure shrinkage, the curling with the hard coat layer formed surface on the inside tends to be reduced.

[0034] On the other hand, if the curing shrinkage rate is too small (the volume expansion during curing is too large), the hard coat film tends to curl outward with the hard coat layer formed surface, and even if the linear expansion coefficient difference between the transparent resin film and the hard coat layer is utilized, the curling may not be adequately controlled. Therefore, the curing shrinkage rate of the hard coat material is preferably -10% or more, more preferably -5% or more, and even more preferably -3% or more. The curing shrinkage rate is preferably -0.01% or less, more preferably -0.1% or less, even more preferably -0.5% or less, and may be -1% or less or -1.5% or less.

[0035] [Hard coat layer] A hard coat layer is formed by applying a hard coat material (hard coat composition) containing a curable resin onto a transparent resin film and curing the hard coat material. As described above, the hard coat material has a negative cure shrinkage rate. The cure shrinkage rate of the hard coat material mainly depends on the structure of the curable resin, particularly on the type of the curable functional group. For example, a material having an alicyclic epoxy group as a curable functional group may show negative cure shrinkage due to photocationic polymerization.

[0036] Hereinafter, a specific example will be given to describe an embodiment in which a hard coat layer is formed from a hard coat material using a polyorganosiloxane compound having an alicyclic epoxy group as a resin material having a negative cure shrinkage rate.

[0037] <Polyorganosiloxane compound> (Silane compounds) The polyorganosiloxane compound having an alicyclic epoxy group can be obtained by condensation of a silane compound represented by the following general formula (1). EBR 1 -Si(OR 3 ) x R 2 3-x ) …(1)

[0038] R 3 is a hydrogen atom or an alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 10. Specific examples of the alkyl group having 1 to 10 carbon atoms 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, and an ethylhexyl group. x is 2 or 3.

[0039] The silane compound represented by the general formula (1) (hereinafter sometimes referred to as "silane compound (1)") has two or three (-OR 3 ) Si-OR 3 Since R is hydrolyzable, a polyorganosiloxane compound can be obtained by condensation of the silane compound. 3The number of carbon atoms in R is preferably 3 or less. 3 It is particularly preferred that is a methyl group.

[0040] R 2 is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of 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. Specific examples of the hydrocarbon in the alkyl group and aralkyl group 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, and a phenethyl group.

[0041] E in the general formula (1) is an alicyclic epoxy group. Since the alicyclic epoxy group maintains an alicyclic structure even when the epoxy group is opened, the cure shrinkage is small and it is likely to show a negative cure shrinkage rate. The alicyclic epoxy group has an epoxy group composed of two adjacent carbon atoms and an oxygen atom constituting an alicyclic ring. Examples of the alicyclic ring include a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, and a cyclooctyl ring. Among them, from the viewpoint of the stability of the structure and the reactivity of the epoxy group, the alicyclic epoxy group is preferably one having a six-membered alicyclic structure such as cyclohexene oxide and methylcyclohexene oxide.

[0042] R 1 is an alkylene group having 2 to 12 carbon atoms, and B is a direct bond, an ether (-O-), or an ester (-COO-). That is, the silane compound of general formula (1) has a Si atom and a -BR group as a spacer. 1 In terms of the curing reactivity of the alicyclic epoxy group, B is a compound in which the alicyclic epoxy group is bonded via an alkylene R 1 A cycloaliphatic epoxy group is directly bonded to the olefin, or an ester is preferred.

[0043] Alkylene R 1Specific examples of R include a dimethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a nonamethylene group, a decamethylene group, an undecamethylene group, and a dodecamethylene group. 1 may be one in which some or all of the hydrogen atoms of the methylene (-CH2-) are substituted with a substituent having 1 to 6 carbon atoms. Examples of the substituent 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, and a phenyl group.

[0044] Alkylene R 1 The larger the number of carbon atoms in the main chain and the longer the chain length, the larger the distance between the Si atom and the alicyclic epoxy group, and the more likely it is that the bending resistance of the hard coat layer after curing will improve. 1 The smaller the number of carbon atoms in the main chain, the harder the hard coat layer tends to be.

[0045] Specific examples of the silane compound represented by general formula (1) include β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, γ-(3,4-epoxycyclohexyl)propyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)propylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, γ-(3,4-epoxycyclohexyl)propyltriethoxysilane, and γ-(3,4-epoxycyclohexyl)propylmethyldiethoxysilane.

[0046] When obtaining a polyorganosiloxane compound by condensation of a silane compound, in addition to the silane compound having an alicyclic epoxy group represented by the above general formula (1), other silane compounds may be used. The other silane compounds (i.e., silane compounds not containing an alicyclic epoxy group, hereinafter sometimes referred to as "silane compound (2)") are represented by the following general formula (2). R 4 -(Si(OR3 ) x R 2 3-x ) …(2)

[0047] In the general formula (2), R 2 , R 3 and x are the same as in general formula (1). 4 R is a monovalent organic group that does not contain an alicyclic epoxy group. 4 represents a substituted or unsubstituted group containing a double bond (for example, a substituted or unsubstituted alkenyl group having 1 to 10 carbon atoms), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 25 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a group having a glycidyl group, a group having an oxetanyl group, or a hydrogen atom.

[0048] When a polyorganosiloxane compound is obtained by condensation of a silane compound, the ratio of the silane compound (1) to the total of the silane compound (1) and the silane compound (2) is preferably 33 to 100 mol%, more preferably 50 to 100 mol%. The ratio of the silane compound (1) may be 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, or may be 100 mol%.

[0049] (Characteristics of polyorganosiloxane compounds) The above silane compounds Si-OR 3By hydrolysis and condensation of the part, Si-O-Si bonds are formed between the silane compounds, and a polyorganosiloxane compound is generated. 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 700 to 18000, more preferably 1000 to 16000, and may be 1200 to 14000 or 1500 to 12000.

[0050] The weight average molecular weight of the polyorganosiloxane compound can be controlled by appropriately selecting the amount of water and the type and amount of catalyst used in the reaction. For example, the more water is charged together with the catalyst during the hydrolysis reaction, the larger the weight average molecular weight tends to be.

[0051] The polyorganosiloxane compound produced by hydrolysis and condensation of the silane compound of general formula (1) contains a structural unit represented by the following formula (3) and a structural unit represented by the following formula (4).

[0052] [EBR 1 -SiO 3 / 2 ] …(3) [EBR 1 -SiO 2 / 2 -D] …(4)

[0053] In the general formula (3) and the general formula (4), E, ​​B and R 1 is the same as in general formula (1). D in general formula (4) is a group selected from the group consisting of a hydrogen atom or 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.

[0054] The constitutional unit represented by formula (3) is a silane compound having a T unit structure in which x=3 in general formula (1), and three alkoxy groups (Si-OR 3 ) are all condensed to form a Si-O-Si bond, and is called a "T3 body." The structural unit represented by formula (4) is a silane compound having a T unit structure with x=3 in general formula (1), and two of the three alkoxy groups are condensed to form a Si-O-Si bond, and is called a "T2 body."

[0055] The smaller the ratio [T3 form] / [T2 form] of the structure represented by formula (3) (T3 form) and the structure represented by formula (4) (T2 form), the more the bending resistance of the hard coat layer obtained by curing the polyorganosiloxane compound tends to improve. From the viewpoint of obtaining a hard coat film in which cracks and breakage of the hard coat layer during bending are suppressed, the ratio of the T3 form to the T2 form of the polyorganosiloxane compound (hereinafter, sometimes referred to as "T3 / T2 ratio") may be less than 5, 4 or less, 3.5 or less, 3 or less, or 2.5 or less. From the viewpoint of ensuring the hardness of the hard coat layer, the T3 / T2 ratio of the polyorganosiloxane compound may be 0.8 or more, 1 or more, 1.5 or more, or 2 or more.

[0056] The content and ratio of T3 and T2 in the polyorganosiloxane compound are as follows: 29 It can be calculated by Si-NMR measurement. 29 In Si-NMR, the Si atom of the T3 isomer and the Si atom of the T2 isomer show different chemical shifts, so the T3 / T2 ratio can be calculated by calculating the integral value of each signal in the NMR spectrum and the ratio of the two.

[0057] The T3 / T2 ratio can be controlled by adjusting the amount of water, the type of catalyst, and the amount of catalyst used in the hydrolysis and condensation reaction of the silane compound. For example, the more the amount of catalyst, the higher the T3 / T2 ratio tends to be. As described later, the use of a neutral salt catalyst tends to reduce the T3 / T2 ratio.

[0058] (Hydrolysis and condensation of silane compounds) By reacting a silane compound with water, the Si-OR of the silane compound is formed. 3 The amount of water required for the hydrolysis and condensation reactions depends on the amount of -OR bonded to the Si atom. 3 The amount of water is preferably 0.3 to 3 equivalents, more preferably 0.5 to 2 equivalents, per equivalent of the group. If the amount of water is too small, the OR that remains without being hydrolyzed may be 3 The hard coat layer tends to have insufficient hardness because of the large number of groups and the small molecular weight of the polyorganosiloxane compound. When the amount of water is excessively large, the reaction rate of hydrolysis and condensation reaction is high, and high molecular weight condensates are generated, which tends to reduce the transparency and flexibility of the hard coat layer.

[0059] In the hydrolysis and condensation reactions of the silane compound, it is preferable to suppress deactivation due to ring opening of the alicyclic epoxy group contained in the silane compound (1). 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 condensation product of the silane compound, it is preferable to carry out the hydrolysis and condensation reactions in the presence of a neutral salt catalyst.

[0060] A neutral salt is a positive salt between a strong acid and a strong base, specifically, a salt between an ion (cation) of an element 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.

[0061] 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.

[0062] As described above, by using a neutral salt catalyst, a polyorganosiloxane compound with a small T3 / T2 ratio can be obtained. In addition, while acid catalysts and base catalysts themselves react electrophilically or nucleophilically with various substances, neutral salts have the advantage of being less corrosive to the metal and resin materials of reaction vessels and storage vessels, and therefore there are fewer restrictions on the materials of production and storage equipment.

[0063] 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 the photocationic polymerization initiator (photoacid generator) and inhibit the polymerization reaction. In contrast, the use of a neutral salt catalyst can suppress the inhibition of polymerization. Therefore, the neutral salt catalyst may remain in the polyorganosiloxane compound obtained by condensation of the silane compound or in the hard coat composition, and the steps of removing the catalyst after the reaction and neutralization can be omitted. The use of the neutral salt catalyst can contribute to the simplification of the manufacturing process and the improvement of the yield.

[0064] The amount of the catalyst used is not particularly limited. The more the amount of the catalyst used, the more the hydrolysis and condensation reaction of the silane compound tends to be accelerated. On the other hand, if the amount of the catalyst used is too large, the transparency of the condensation product may be impaired and purification may become complicated. The amount of the neutral salt catalyst used is determined based on the amount of hydrolyzable silyl groups (-OR) of the silane compound. 3 The amount is preferably 0.000001 to 0.1 mol, and more preferably 0.000005 to 0.01 mol, relative to 1 mol of the compound (II).

[0065] As described above, the polyorganosiloxane compound obtained by hydrolysis and condensation reaction of silane compound may have a neutral salt catalyst remaining.The amount of 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 transparency of the hard coat layer, the amount of basic catalyst remaining in the polyorganosiloxane compound is preferably 10000 ppm or less, more preferably 5000 ppm or less, and even more preferably 3000 ppm or less, and may be 1000 ppm or less, 800 ppm or less, or 500 ppm or less.

[0066] In the hydrolysis and condensation reaction of the silane compound, the reaction may be carried out while refluxing the dilution solvent and the alcohol generated by hydrolysis. The dilution solvent is preferably one that exhibits compatibility with water, and is preferably a water-soluble alcohol or ether compound. Since many silane compounds have low compatibility with neutral salts and water used for hydrolysis, it is preferable to react them as a compatible system in the form of a solution using a dilution solvent.

[0067] The boiling point of the dilution 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 dilution solvent is too low, the dilution solvent may reflux at low temperatures, resulting in a decrease in reaction rate. From the viewpoint of the removability of the dilution solvent after the reaction, the boiling point of the dilution solvent is preferably 200° C. or lower.

[0068] Specific examples of the dilution 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, and propylene glycol dimethyl ether.

[0069] The reaction temperature of the hydrolysis and condensation reaction of the silane compound 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 that the reaction time can be shortened. From the viewpoint of suppressing side reactions of the organic group of the silane compound, the reaction temperature is preferably 200° C. or lower.

[0070] From the viewpoint of increasing the crosslinking density in the cured product (hard coat layer) and improving hardness, it is preferable that the polyorganosiloxane compound obtained by hydrolysis and condensation of the silane compound has a high residual rate of alicyclic epoxy groups. The residual rate of alicyclic epoxy groups, that is, the ratio of the number of moles of alicyclic epoxy groups in the polyorganosiloxane compound obtained by condensation to the number of moles of alicyclic epoxy groups contained in the raw material silane compound (1), is preferably 20% or more, more preferably 40% or more, even more preferably 60% or more, particularly preferably 80% or more, and may be 90% or more or 95% or more. The residual rate of alicyclic epoxy groups is 1 It is determined by H-NMR measurement.

[0071] In the hydrolysis and condensation reactions, the EBR bonded to the Si atom of the silane compound (1) is reacted with the silane compound (2) in a condensation reaction, except for side reactions such as ring-opening of the epoxy group. 1 - does not react and maintains its structure. Therefore, the polyorganosiloxane compound obtained by condensation of the silane compound (1) has a structure represented by the following general formula (5) (hereinafter, sometimes referred to as "structure (5)"). [EBR 1 -Si] …(5)

[0072] E, B and R in general formula (5) 1 is the same as general formula (1). That is, structure (5) is a structure in which an alicyclic epoxy group is bonded to a Si atom with or without another organic group being interposed therebetween.

[0073] The ratio of the number of structures (5) (i.e., the number of alicyclic epoxy groups) to the total number of Si atoms in the polyorganosiloxane compound is preferably 33% or more, more preferably 50% or more, and may be 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, or may be 100%.

[0074] Since the silane compound (1) and the silane compound (2) each have one Si atom per molecule, the polyorganosiloxane compound produced by condensation of N molecules of the silane compound contains N Si atoms. If the alicyclic epoxy group remains unreacted during the hydrolysis and condensation reaction, n structures (5) are produced from n silane compounds (1). Therefore, in the polyorganosiloxane compound obtained by condensation of the silane compounds, the ratio of the silane compound (1) in the silane compounds used as raw materials (molar ratio: n / N) is approximately equal to the ratio of the structure (5) to the number of Si atoms in the polyorganosiloxane compound.

[0075] When silane compound (2) is used in addition to silane compound (1) as the silane compound, the polyorganosiloxane compound has a structure represented by the following general formula (6) (hereinafter sometimes referred to as "structure (6)") in addition to the above structure (5). [R 4 -Si] …(6) R in general formula (6) 4 is the same as general formula (2).

[0076] <Hard Coat Composition> The hard coat composition is a composition containing the above-mentioned curable resin. The hard coat composition preferably contains a photopolymerization initiator in addition to the curable resin such as a polyorganosiloxane compound, and may contain other components.

[0077] (Photocationic polymerization initiator) When the curable resin is a polyorganosiloxane compound having an epoxy group, the hard coat composition preferably contains a photocationic polymerization initiator. The photocationic polymerization initiator is a compound (photoacid generator) that generates an acid by irradiation with active energy rays. The acid generated from the photoacid generator promotes ring-opening and polymerization reaction of the epoxy group of the polyorganosiloxane compound, forming an intermolecular crosslink, and curing the hard coat material.

[0078] 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-allene complexes; silanol-metal chelate complexes; sulfonic acid derivatives such as disulfones, disulfonyldiazomethanes, disulfonylmethanes, sulfonylbenzoylmethanes, imide sulfonates, and benzoin sulfonates; and organic halogen compounds.

[0079] Among the above photoacid generators, aromatic sulfonium salt or aromatic iodonium salt is preferred because it has high stability in the hard coat composition containing polyorganosiloxane compound having alicyclic epoxy group.These counter anions include fluorophosphate anion, fluoroantimonate anion, fluoroborate anion, etc.When using the photoacid generator containing these counter anions, the photocuring speed is high and it is easy to obtain a hard coat layer that has excellent adhesion with transparent resin film.

[0080] The content of the 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, based on 100 parts by weight of the polyorganosiloxane compound.

[0081] (Leveling agent) The hard coat composition may contain a leveling agent. When the hard coat layer contains a leveling agent, it is expected that the surface tension will be reduced, the surface smoothness will be improved, the slipperiness will be improved, and the antifouling properties (fingerprint resistance, etc.) will be improved. In addition, when the leveling agent has a group reactive with an epoxy group and / or a hydrolytic condensation group, it is expected that the scratch resistance of the hard coat layer will be improved.

[0082] Examples of the leveling agent include silicone-based leveling agents and fluorine-based leveling agents. Examples of the silicone-based leveling agent include leveling agents having a polyorganosiloxane skeleton. Examples of the fluorine-based leveling agent include leveling agents having a fluoroaliphatic hydrocarbon skeleton. Examples of the fluoroaliphatic hydrocarbon skeleton include fluoro-C such as fluoromethane, fluoroethane, fluoropropane, fluoroisopropane, fluorobutane, fluoroisobutane, fluoro t-butane, fluoropentane, and fluorohexane. 1-10 Alkanes and the like.

[0083] When the hard coat composition contains a leveling agent, the content thereof 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, based on 100 parts by weight of the polyorganosiloxane compound.

[0084] (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 polyorganosiloxane compound. A compound having a cationic polymerizable functional group is used as the reactive diluent for photo-cationic polymerization. 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, the reactive diluent having an epoxy group is preferred because it has high reactivity with the epoxy group of the polyorganosiloxane compound.

[0085] 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, based on 100 parts by weight of the polyorganosiloxane compound.

[0086] (Photosensitizer) The hard coat composition may contain a photosensitizer for the purpose of improving the photosensitivity of the photocationic polymerization initiator (photoacid generator). Photosensitizers that can absorb light in a wavelength range that the photoacid generator itself cannot absorb are more efficient, so it is preferable that the photosensitizer has little overlap with the absorption wavelength range of the photoacid generator. Examples of photosensitizers include anthracene derivatives, benzophenone derivatives, thioxanthone derivatives, anthraquinone derivatives, and benzoin derivatives.

[0087] 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 even more preferably 10 parts by weight or less, based on 100 parts by weight of the photoacid generator.

[0088] (particle) The hard coat composition may contain particles for the purpose of adjusting the film properties such as surface hardness and bending resistance, suppressing curing shrinkage, etc. As the particles, organic particles, inorganic particles, organic-inorganic composite particles, etc. may be appropriately selected and used. Examples of the organic particle material include poly(meth)acrylic acid alkyl ester, crosslinked poly(meth)acrylic acid alkyl ester, crosslinked styrene, nylon, silicone, crosslinked silicone, crosslinked urethane, crosslinked butadiene, etc. Examples of the inorganic particle material include metal oxides such as silica, titania, alumina, tin oxide, zirconia, zinc oxide, and antimony oxide; metal nitrides such as silicon nitride and boron nitride; and metal salts such as calcium carbonate, calcium hydrogen phosphate, calcium phosphate, and aluminum phosphate. Examples of the organic-inorganic composite filler include those in which an inorganic layer is formed on the surface of organic particles, and those in which an organic layer or organic fine particles is formed on the surface of inorganic particles.

[0089] Examples of the particle shape include spherical, powdery, fibrous, needle-like, scaly, etc. Spherical particles are not anisotropic and stress is unlikely to be unevenly distributed, so that the occurrence of distortion is suppressed, and this can contribute to suppression of curling caused by volume change during hardening of the hard coat material.

[0090] The average particle size of the particles is, for example, about 5 nm to 10 μm. From the viewpoint of increasing the transparency of the hard coat layer, the average particle size 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 size can be measured by a laser diffraction / scattering type particle size distribution measuring device, and the volume-based median size is taken as the average particle size.

[0091] The hard coat composition may contain surface-modified particles. By surface-modifying particles, the dispersibility of particles in polyorganosiloxane compound tends to improve. In addition, when the particle surface is modified by a polymerizable functional group that can react with epoxy group, the functional group on the particle surface reacts with the epoxy group of the polyorganosiloxane compound to form chemical crosslinking, so that the film strength can be improved.

[0092] Examples of polymerizable functional groups that can react with epoxy groups include vinyl groups, (meth)acrylic groups, hydroxyl groups, phenolic hydroxyl groups, carboxyl groups, acid anhydride groups, amino groups, epoxy groups, and oxetane groups. Among these, epoxy groups are preferred. In particular, particles surface-modified with epoxy groups are preferred because they can form chemical crosslinks between the particles and the polyorganosiloxane compound during curing of the hard coat composition by photocationic polymerization.

[0093] Examples of particles having reactive functional groups on the surface include surface-modified inorganic particles and core-shell polymer particles.

[0094] (solvent) The hard coat composition may be solvent-free or may contain a solvent. When a solvent is contained, it is preferable that the solvent does not dissolve the transparent resin film. On the other hand, by using a solvent having a degree of solubility to swell the transparent resin film, the adhesion between the transparent resin film 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, relative to 100 parts by weight of the polyorganosiloxane compound.

[0095] (Additives) The hard coat composition may contain additives such as inorganic pigments, organic pigments, surface conditioners, surface modifiers, plasticizers, dispersants, wetting agents, thickeners, and defoamers. The hard coat composition may also contain a thermoplastic or thermosetting resin material other than the 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 photocationic polymerization initiator.

[0096] <Formation of hard coat layer> A hard coat composition is applied onto a transparent resin film, and the solvent is dried and removed as necessary. The hard coat composition is then cured by irradiating it with active energy rays, thereby obtaining a hard coat film having a hard coat layer 3 on a transparent resin film 1.

[0097] Before applying the hard coat composition, the surface of the transparent resin film may be subjected to a surface treatment such as a corona treatment or a plasma treatment. In addition, an easy-adhesion layer (primer layer) or the like may be provided on the surface of the transparent resin film. The hard coat layer formed by curing the polyorganosiloxane compound exhibits high adhesion to the resin film, so that an easy-adhesion layer or the like may not be provided. That is, the hard coat film may have the transparent resin film 1 and the hard coat layer 3 in contact with each other.

[0098] Before applying a hard coat composition to the first main surface 1A of the transparent resin film 1, a support film 6 may be laminated to the second main surface 1B of the transparent resin film 1 as shown in Fig. 2. The support film 6 is preferably one that can be peeled off from the transparent resin film 1, and for example, a laminate having a weakly adhesive pressure-sensitive adhesive layer 4 on the surface of a film 5 is used.

[0099] With the support film 6 attached to the second main surface 1B of the transparent resin film, a hard coat composition is applied to the first main surface 1A of the transparent resin film and cured to form a laminate in which the hard coat film and the support film 6 are laminated as shown in Fig. 3. The support film is peeled off and removed from this laminate to obtain the hard coat film 10 shown in Fig. 1.

[0100] Forming the hard coat layer 3 with the support film 6 attached thereto may suppress deformation or thermal damage of the transparent resin film during heating or light irradiation. In addition, by attaching the support film 6, the overall thickness increases and the rigidity of the laminate 12 increases, so that curling during the formation of the hard coat layer is suppressed and handling properties are improved.

[0101] From the viewpoint of providing rigidity to the laminate 12 of the transparent resin film 1 and the support film 6, the thickness of the support film 6 is preferably greater than the thickness of the transparent resin film 1. The thickness of the support film 6 is preferably 50 μm or more, more preferably 80 μm or more, and even more preferably 100 μm or more. From the viewpoint of maintaining handleability during roll transport or the like, the thickness of the support film is preferably 500 μm or less, more preferably 300 μm or less, and may be 200 μm or less or 150 μm or less.

[0102] The method of applying the hard coat composition onto the transparent resin film is not particularly limited, and any known method can be used. Examples of the application method include a die coater such as a fountain die or a slot die, a roll coater such as a gravure coater or a comma coater, a bar coater, a dip coater, a spin coater, and a spray coater.

[0103] Examples of the active energy rays irradiated during photocuring include visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, γ-rays, and electron beams. As the active energy rays, ultraviolet light is preferred because of its high curing reaction speed and excellent energy efficiency. The cumulative irradiation dose of the active energy rays is, for example, 50 to 10,000 mJ / cm. 2 This may be set depending on the type and amount of the cationic photopolymerization initiator, the thickness of the hard coat layer, etc.

[0104] When a hard coat composition containing the above-mentioned polyorganosiloxane compound is irradiated with active energy rays, the alicyclic epoxy group undergoes ring-opening and cationic polymerization due to the acid generated from the photocationic polymerization initiator, and curing proceeds, thereby obtaining a hard coat layer containing a cured resin having a structure represented by the following general formula (7). [ABR 1 -Si(O 1 / 2 ) x R 2 3-x ] …(7)

[0105] In formula (7), A is a structure containing an alicyclic ring obtained by the reaction of an alicyclic epoxy group. The number of carbon atoms in A may be 7 or less. An example of a structure having 7 or less carbon atoms is the structure having the rational formula C6H9(OH)(O 1 / 2 ) structure, which has the rational formula C6H8(OH)(O 1 / 2 )(CH3) is an example of such a structure. Among them, the structure represented by the rational formula C6H9(OH)(O 1 / 2 ) is preferred.

[0106] The hard coat layer obtained by curing the above polyorganosiloxane compound contains a structural unit represented by the following formula (8) and a structural unit represented by the following formula (9).

[0107] [ABR 1 -SiO 3 / 2] …(8) [ABR 1 -SiO 2 / 2 -D] …(9)

[0108] In the general formulas (8) and (9), A is the same as in the general formula (7). In the general formulas (7) to (9), B, R 1 and D are the same as those in general formulas (1), (3), and (4). Even after curing by reaction of the alicyclic epoxy groups of the polyorganosiloxane compound, the SiO bond network of the polysiloxane compound is maintained, so the ratio (T3 / T2 ratio) of the structure represented by formula (8) (T3 body) to the structure represented by formula (9) (T2 body) is equal to the T3 / T2 ratio of the polyorganosiloxane compound before curing.

[0109] The polyorganosiloxane compound contains a structure derived from the silane compound (2), and R 4 contains an epoxy group other than an alicyclic epoxy group, in addition to the reaction between the alicyclic epoxy groups derived from the silane compound (1), a reaction between the alicyclic epoxy groups derived from the silane compound (1) and the epoxy groups derived from the silane compound (2), and a reaction between the epoxy groups derived from the silane compound (2) also occur.

[0110] In the polyorganosiloxane compound having an alicyclic epoxy group, a bond is formed between two alicyclic rings by the reaction of the alicyclic epoxy group, so the molecular volume is likely to increase by curing. Since the hard coat composition has a negative cure shrinkage rate, the cure shrinkage is smaller than when a general acrylic hard coat material is used, and curling of the hard coat film can be reduced.

[0111] When the linear expansion coefficient of the hard coat layer is larger than that of the transparent resin film, by raising the temperature during irradiation with active energy rays above room temperature, the stress at the interface between the hard coat layer and the transparent resin film caused by negative curing shrinkage (volume expansion) is cancelled out by the difference in the linear expansion coefficients between the hard coat layer and the transparent resin film (the difference in the amount of shrinkage when returning to room temperature from a heated state), and the amount of curl can be appropriately controlled.

[0112] From the viewpoint of reducing the amount of curling, the temperature during irradiation with active energy rays is preferably 35° C. or higher, more preferably 45° C. or higher, even more preferably 50° C. or higher, and may be 55° C. or higher or 60° C. or higher. From the viewpoint of suppressing plastic deformation of the transparent resin film due to heat, the temperature during irradiation with active energy rays is preferably 150° C. or lower, more preferably 120° C. or lower, and may be 100° C. or lower, 90° C. or lower, or 85° C. or lower.

[0113] The acid, which is the active species of photocationic polymerization, remains in the composition even after irradiation with active energy rays, and the reaction rate is low at low temperatures around room temperature. Therefore, even after irradiation with active energy rays, the curing reaction may proceed for several days, and the curl of the hard coat film may gradually change. In such a case, a hard coat film with less curl can be obtained by irradiating with active energy rays, taking into account the amount of curl change over time.

[0114] Since the hard coat composition has a negative cure shrinkage rate, as the curing proceeds, tensile stress is generated at the interface between the hard coat layer and the transparent resin film, and a force acts to curl the hard coat layer-formed surface outward. If the temperature during the active energy ray irradiation is set high and photocuring is performed in a state where the thermal expansion of the hard coat layer is large, the shrinkage of the hard coat layer is large when the temperature is returned to room temperature, so curling is likely to occur with the hard coat film-formed surface inward. Then, as the curing proceeds over time at room temperature, negative cure shrinkage (volume expansion) occurs in the hard coat layer, so the curling is alleviated over time, and a hard coat film with a small amount of curling is obtained.

[0115] Heating may be performed after irradiation with active energy rays. Heating increases the curing speed and reduces the amount of uncured material, so that the change in curl amount over time can be suppressed. In addition, an increase in the hardness of the hard coat layer due to an increase in the curing rate can also be expected. When heating is performed after irradiation with active energy rays, the heating temperature is, for example, 35°C or higher, preferably 50°C or higher, more preferably 70°C or higher, and may be 80°C or higher, 90°C or higher, or 100°C or higher. From the viewpoint of suppressing plastic deformation of the hard coat film, the heating temperature is preferably 180°C or lower, more preferably 150°C or lower. The heating time is, for example, about 10 seconds to 60 minutes, and may be 20 seconds or more, 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more, and may be 50 minutes or less, 40 minutes or less, 30 minutes or less, 20 minutes or less, 10 minutes or less, or 5 minutes or less.

[0116] [Characteristics of hard coat film] The hard coat layer having a polymer matrix crosslinked by the ring-opening and polymerization reaction of the alicyclic epoxy group of the above polyorganosiloxane compound can achieve a surface hardness comparable to that of glass.The surface hardness (pencil hardness) of the hard coat layer-forming surface of the hard coat film is preferably 2H or more, more preferably 4H or more, and may be 6H or more, 7H or more, or 8H or more.

[0117] When the hard coat film is subjected to a cylindrical mandrel test with the hard coat layer formed surface facing inward, the diameter φ of the mandrel at which cracks occur in the hard coat layer is preferably small. If the thickness of the hard coat layer is the same, the smaller the diameter of the mandrel, the better the bending resistance. The diameter of the mandrel at which cracks occur in the hard coat layer is preferably 3 mm or less, more preferably 2 mm or less. As described above, the smaller the T3 / T2 ratio of the polyorganosiloxane compound, the better the bending resistance and the smaller the mandrel diameter φ tends to be.

[0118] The total light transmittance of the hard coat film is preferably 80% or more, more preferably 85% or more, and even more preferably 89% or more.

[0119] [Applications of hard coat films] The hard coat film may have various functional layers on the hard coat layer 3 or on the second main surface 1B of the transparent resin film 1. In addition, a functional layer may be provided between the transparent resin film 1 and the hard coat layer 3. Examples of the functional layer include an adhesion imparting layer, a tacky adhesive layer, an antireflection layer, a water repellent layer, an oil repellent layer, a transparent conductive layer, a refractive index adjusting layer, an antistatic layer, an antiglare layer, and a polarizer-containing layer.

[0120] The hard coat film of the present invention can be suitably used as 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, etc. The hard coat film of the present invention can be suitably used particularly as a cover window or substrate film for a curved display, a flexible display, etc. EXAMPLES

[0121] The present invention will be described in more detail below by showing examples of producing a hard coat film having a hard coat layer on a transparent resin film, but the present invention is not limited to the following examples.

[0122] [Transparent resin film] <Synthesis of polyimide resin> Dimethylformamide (DMF) was added to a reaction vessel and stirred under a nitrogen atmosphere. Diamine and tetracarboxylic dianhydride were added thereto in the molar ratios shown in Table 1, and the mixture was reacted by stirring under a nitrogen atmosphere for 5 to 10 hours to obtain a polyamic acid solution with a solid content of 18%.

[0123] Pyridine was added as an imidization catalyst to the polyamic acid solution, and after complete dispersion, acetic anhydride was added as a dehydrating agent and stirred at 90°C for 3 hours. After cooling the reaction solution to room temperature, isopropyl alcohol (IPA) was added dropwise while stirring to precipitate polyimide resin. After filtering and washing with IPA, the mixture was vacuum dried to obtain polyimide resin A and polyimide resin B.

[0124] The molar ratios of the monomers (diamine and tetracarboxylic dianhydride) used in the preparation of polyimide resin A (PI-A) and polyimide resin B (PI-B) are shown in Table 1. The abbreviations of the monomers in Table 1 are as follows. TFMB: 2,2'-bis(trifluoromethyl)benzidine 3,3'-DDS: 3,3'-diaminodiphenyl sulfone TMHQ: p-phenylene bis(trimellitic) dianhydride 6FDA: 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropanoic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride TAHMBP: 2,2',3,3',5,5'-hexamethyl-biphenyltetracarboxylic dianhydride

[0125] [Table 1]

[0126] <Polyimide film 1> Polyimide resin A was dissolved in methylene chloride to prepare a solution with a solid content of 11 wt%. This methylene chloride solution was applied to a non-alkali glass plate and dried in air at 40°C for 60 minutes, 70°C for 30 minutes, 150°C for 30 minutes, 170°C for 30 minutes, and 200°C for 60 minutes to obtain polyimide film 1 with a thickness of 50 μm. The linear expansion coefficient of polyimide film 1 (PI1) was 30 ppm / °C, as determined from the TMA curve when the film was heated to 100°C and then cooled to 30°C at 5°C / min, by thermomechanical analysis (TMA).

[0127] <Polyimide film 2> Except for changing the coating thickness of the solution, polyimide film 2 having a thickness of 35 μm was obtained in the same manner as polyimide film 1. The linear expansion coefficient of polyimide film 2 (PI2) was 30 ppm / ° C.

[0128] <Polyimide film 3> A polyimide film 3 having a thickness of 30 μm was obtained in the same manner as in the preparation of the polyimide film 1, except that polyimide resin B was used instead of polyimide resin A and the coating thickness of the solution was changed. The linear expansion coefficient of the polyimide film 3 (PI3) was 16 ppm / °C.

[0129] <Polyethylene terephthalate film 1> A polyethylene terephthalate film with a thickness of 125 μm ("Lumirror U48" manufactured by Toray) was used. The linear expansion coefficient of the polyethylene terephthalate film 1 (PET1) was 15 ppm / °C.

[0130] <Polyethylene terephthalate film 2> A polyethylene terephthalate film with a thickness of 50 μm ("Lumirror U48" manufactured by Toray) was used. The linear expansion coefficient of the polyethylene terephthalate film 2 (PET2) was 15 ppm / °C.

[0131] [Synthesis of polyorganosiloxane compounds] <Synthesis Example 1> In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 66.5g (270mmol) of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane ("SILQUEST A-186" manufactured by Momentive Performance Materials) and 16.5g of 1-methoxy-2-propanol (PGME) were charged and stirred uniformly. A solution of 0.039g (0.405mmol) of magnesium chloride as a catalyst dissolved in a mixture of 9.7g (539mmol) of water and 5.8g of methanol was dropped into this mixture over 5 minutes and stirred until it became uniform. The mixture was then heated to 80°C and polycondensation reaction was carried out for 6 hours while stirring. After the reaction was completed, the solvent and water were removed using a rotary evaporator to obtain polyorganosiloxane compound A.

[0132] Measurements were performed using a Bruker NMR (400 MHz) with deuterated acetone as the solvent.1 From the H-NMR spectrum, it was confirmed that the residual rate of epoxy groups in polyorganosiloxane compound 1 was 95% or more. The weight average molecular weight in terms of polystyrene was measured using a Tosoh GPC device "HLC-8220GPC" (columns: TSKgel GMHXL x 2, TSKgel G3000HXL, TSKgel G2000HXL) with THF as the solvent, and was 3000. 29 The ratio T3 / T2 (molar ratio) of T3 to T2 obtained from the Si-NMR spectrum was 2.3. The amount of magnesium chloride (neutral salt catalyst) remaining in the polyorganosiloxane compound 1 calculated based on the charged amount was 814 ppm.

[0133] <Synthesis Example 2> In 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. A solution of 0.010 g (0.11 mmol) of magnesium chloride as a catalyst dissolved in a mixture of 11.9 g (660 mmol) of water and 4.7 g of methanol was dropped into this mixture over 5 minutes and stirred until it became uniform. The mixture was then heated to 70°C and polycondensation reaction was carried out for 6 hours while stirring. After the reaction was completed, methanol and water were removed using a rotary evaporator to obtain polyorganosiloxane compound B.

[0134] The residual epoxy group rate of the polyorganosiloxane compound 2 was 95% or more, the weight average molecular weight in terms of polystyrene was 4500, T3 / T2 was 2.1, and the residual amount of magnesium chloride (neutral salt catalyst) was 191 ppm.

[0135] [Hard Coat Composition] <Hard Coat Composition 1> Hard coat composition 1 was obtained by blending 100 parts by weight of polyorganosiloxane compound A with 81.8 parts by weight of propylene glycol monomethyl ether, 0.2 parts by weight of a propylene carbonate solution of triarylsulfonium SbF6 salt (manufactured by San-Apro, "CPI-101A") as a photocationic polymerization initiator, as a solid content, and 0.5 parts by weight of a xylene / isobutanol solution of polyether-modified polydimethylsiloxane (manufactured by BYK, "BYK-300") as a leveling agent, as a solid content.

[0136] <Hard Coat Composition 2> Hard coat composition 2 was obtained in the same manner as in the preparation of hard coat resin composition 1, except that the amount of the photocationic polymerization initiator was changed to 2 parts by weight.

[0137] <Hard Coat Composition 3> Hard coat composition 3 was obtained in the same manner as hard coat resin composition 1, except that the leveling agent was changed to a fluorine-based leveling agent ("Megafac RS-90" manufactured by DIC) and the amount added was changed to 0.3 parts by weight in solid content.

[0138] <Hard Coat Composition 4> Polyorganosiloxane compound B 100 parts by weight Triarylsulfonium P (Rf) n F 6-n Hard coat composition 4 was obtained by blending 0.5 parts by weight of a 50% propylene carbonate solution of salt ("CPI-200K" manufactured by San-Apro) as solid content and 0.5 parts by weight of a leveling agent ("BYK-300" manufactured by BYK) as solid content.

[0139] <Hard Coat Composition 5> Hard coat composition 5 was obtained by mixing 100 parts by weight of dipentaerythritol hexaacrylate, 25 parts by weight of propylene glycol monomethyl ether, 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone (BASF's "Irgacure 184") as a photoradical polymerization initiator, and 0.5 parts by weight of a leveling agent (BYK's "BYK-300") as a solid content.

[0140] <Evaluation of hard coat composition> A support film having a 10 μm-thick acrylic adhesive layer attached to a 125 μm-thick polyethylene terephthalate film was laminated to one side of the polyimide film 1, and a hard coat composition was applied to the other side using a bar coater so that the dry film thickness was 50 μm. After heating at 120° C. for 2 minutes, the composition was exposed to an ambient temperature of 80° C. and an accumulated light dose of about 2000 mJ / cm 2 . 2 After heating at 120° C. for 2 minutes to completely cure the hard coat composition, the polyimide film 1 was dissolved by immersion in methylene chloride to isolate the hard coat layer (cured product of the hard coat composition).

[0141] The isolated hard coat layer was used as a sample to measure the linear expansion coefficient and cure shrinkage. The linear expansion coefficient was calculated from the TMA curve when cooled from 100°C to 30°C, as in the transparent resin film. The cure shrinkage was calculated based on the density ρ L and the density ρ of the hard coat layer after photocuring C was calculated based on the following formula. Curing shrinkage rate (%)=100×(ρ C -ρ L ) / ρ C

[0142] For hard coat compositions 1 to 3, the density ρ of the hard coat composition (solid) isolated after drying by heating and before irradiation with ultraviolet light (before curing) was L was measured by a density gradient tube method. For hard coat compositions 4 and 5, the density ρ of the composition (liquid) after heating at 120° C. for 2 minutes to remove volatiles was L was measured by a pycnometer. The density ρ of the hard coat layer after photocuring C was measured by the density gradient tube method.

[0143] The compositions, linear expansion coefficients and cure shrinkage rates of hard coat compositions 1 to 5 are shown in Table 2. The compositions in Table 2 are shown in parts by weight of the blending amount of each component based on 100 parts by weight of the curable resin component.

[0144] [Table 2]

[0145] The acrylic hard coat composition 5 showed a positive cure shrinkage ratio. The hard coat composition 4, which contains a polyorganosiloxane compound having a non-alicyclic epoxy group as the cured resin component, also showed a positive cure shrinkage ratio. On the other hand, the hard coat compositions 1 to 3, which contain a polyorganosiloxane compound having an alicyclic epoxy group as the cured resin component, showed a negative cure shrinkage ratio due to an increase in volume (expansion) upon photocuring.

[0146] [Hard coat film] <Hard coat film 1> A support film having a 10 μm thick acrylic adhesive layer attached to a 125 μm thick polyethylene terephthalate film was attached to one side of the polyimide film 1. The hard coat composition 1 was applied to the other side of the polyimide film using a bar coater so that the dry film thickness was 50 μm, and heated at 120° C. for 2 minutes. Thereafter, the film was transported at an atmospheric temperature of 80° C. and a transport speed of 2 m / min using a transport type ultraviolet irradiation device equipped with an ultraviolet irradiation lamp (Heraeus "H bulb", light emission dose after output adjustment 216 W / cm) arranged at a distance of 93 mm from the coating film, and the accumulated light amount measured with a UV scale of Fujifilm Corporation was 1950 mJ / cm. 2 The hard coat composition was cured by irradiating with ultraviolet rays so as to obtain a hard coat film 1 having a hard coat layer with a thickness of 50 μm on a polyimide film 1.

[0147] <Hard coat film 2~10> Except for changing the thickness of the hard coat layer and the curing conditions (ambient temperature during UV irradiation, distance of the UV irradiation lamp from the coating), hard coat films having a hard coat layer made of a cured product of hard coat composition 1 on polyimide film 1 were produced in the same manner as hard coat film 1. Hard coat films 4, 8, and 10 were heated at 120°C for 2 minutes after UV irradiation.

[0148] <Hard Coat Films 11-13> Using polyimide film 2 instead of polyimide film 1, hard coat composition 1 was applied and heated, and the film was transported at a transport speed of 4 m / min using a transport type ultraviolet irradiation device equipped with an ultraviolet irradiation lamp (high pressure mercury lamp "H03-L31" manufactured by Eye Graphics, luminous dose after output adjustment: 120 W / cm) placed at a distance of 200 mm from the coating film. The total cumulative light amount from UVA to UVC measured with "UV POWR PUCK II" by EIT was 1037 mJ / cm. 2 A hard coat film having a hard coat layer made of a cured product of hard coat composition 1 on polyimide film 2 was produced in the same manner as in the production of hard coat film 1, except that the thickness of the hard coat layer and the atmospheric temperature during ultraviolet irradiation were changed as shown in Table 4.

[0149] <Hard Coat Film 14~16> A hard coat film having a hard coat layer made of a cured product of hard coat composition 1 on polyimide film 3 was produced in the same manner as hard coat films 11 to 13, except that polyimide film 3 was used instead of polyimide film 2 and the atmospheric temperature during ultraviolet irradiation was changed as shown in Table 4.

[0150] <Hard Coat Film 17~21> A polyethylene terephthalate film 1 was used instead of the polyimide film 1, and a hard coat layer was applied and irradiated with light without laminating a support film. A hard coat film having a hard coat layer made of a cured product of the hard coat composition 1 on the polyethylene terephthalate film 1 was produced in the same manner as in the production of the hard coat film 1, except that the thickness of the hard coat layer and the curing conditions (ambient temperature during ultraviolet irradiation, distance of the ultraviolet irradiation lamp from the coating film) were changed.

[0151] <Hard Coat Film 22~36> The type of transparent resin film, the composition and thickness of the hard coat layer, and the curing conditions were changed as shown in Tables 5 and 6, and hard coat films were produced in the same manner as in each of the above examples.

[0152] [evaluation] The above hardcoat films were evaluated according to the following criteria.

[0153] <Curl> The hard coat film was cut into a square of 100 mm x 100 mm, and left to stand for 10 days in an environment of 23 ° C. and 55% RH, then placed on a horizontal table with the hard coat layer formed side on the top, and the distances (floating amounts) of the four vertices of the square from the table were measured, and the average value was taken as the curl amount. For those that curled with the hard coat layer formed side on the outside, the hard coat layer formed side was placed on a horizontal table with the hard coat layer formed side on the bottom, and the curl amount was measured, and the sign of the curl amount was taken as negative. For those that the film cut into a square was curled into a cylindrical shape and the curl value could not be measured, the curl amount of those that curled with the hard coat layer formed side on the inside was taken as +∞, and the curl amount of those that curled with the hard coat layer formed side on the outside was taken as -∞.

[0154] <Surface hardness> The pencil hardness of the surface on which the hard coat layer was formed was measured in accordance with JIS K5600-5-4:1999.

[0155] <Flexibility> For hard coat films 1 to 16, a cylindrical mandrel test was performed using a type 1 testing machine with the hard coat layer formed surface facing inward in accordance with JIS K5600-5-1:1999. When hard coat films 1 to 16 were all bent along a mandrel with a diameter of 2 mm, no cracks or peeling of the hard coat layer occurred.

[0156] The materials, preparation conditions and evaluation results of hard coat films 1 to 36 are shown in Tables 3 to 6.

[0157] [Table 3]

[0158] [Table 4]

[0159] [Table 5]

[0160] [Table 6]

[0161] As shown in Table 6, the hard coat films 31 to 36 using the acrylic hard coat composition 5 having a positive cure shrinkage rate curled into a cylindrical shape with the hard coat layer on the inside when cut into a square shape, regardless of the type of transparent resin film and the curing temperature. The hard coat film 30 using the hard coat composition 4 containing a polyorganosiloxane compound having a non-alicyclic epoxy group as the cured resin component also curled into a cylindrical shape with the hard coat layer on the inside.

[0162] Hard coat films 1 to 29, which were made using a hard coat composition having a negative cure shrinkage rate, all showed reduced curling compared to hard coat films 30 to .

[0163] Comparing hard coat films 1 to 3, it was found that the lower the temperature during UV irradiation, the more curling occurred on the negative side (the surface on which the hard coat layer was formed was on the outside). A similar tendency was observed in comparing hard coat films 5 to 7 and comparing hard coat film 8 with hard coat film 10. These results show that by using a hard coat composition having a negative cure shrinkage rate and adjusting the heating temperature during UV irradiation, a hard coat film with less curling can be obtained even when the hard coat layer is thick.

[0164] From the results shown in Tables 4 to 6, it can be seen that a hard coat film with less curling can be obtained by adjusting the temperature during ultraviolet irradiation, even when the type of transparent resin film, the amount of photocationic polymerization initiator used in the hard coat composition, the type of leveling agent, etc. are changed. When a polyimide film was used as the transparent resin film, the surface hardness tended to be higher than when a PET film was used.

Claims

1. A method for producing a hard coat film, comprising the steps of: providing a transparent resin film having a first main surface and a second main surface; and providing, on the first main surface of the film, a hard coat layer made of a cured product of a hard coat composition and having a thickness 0.15 times or more that of the transparent resin film, the method comprising the steps of: a hard coat composition is applied onto a first main surface of the transparent resin film, and then the hard coat layer is formed by irradiating the first main surface with active energy rays; The hard coat composition has a negative cure shrinkage; The method for producing a hard coat film comprises irradiating the active energy rays in a heated atmosphere at 45°C to 90°C.

2. The method for producing a hard coat film according to claim 1, wherein the hard coat composition contains a polyorganosiloxane compound which is a condensate of a silane compound represented by general formula (1): E-B-R １ -Si(OR ３ ) ｘ R ２ ３－ｘ ) …(1) In the general formula (1), E is an alicyclic epoxy group, B is a direct bond, an ether or an ester, and R １ is an alkylene group having 2 to 12 carbon atoms, R ２ is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of 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; x is 2 or 3; R ３ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

3. The method for producing a hard coat film according to claim 2, wherein the weight average molecular weight of the polyorganosiloxane compound is 500 to 20,000.

4. The method for producing a hard coat film according to any one of claims 1 to 3, wherein the hard coat composition contains a photocationic polymerization initiator.

5. A method for producing a hard coat film described in any one of claims 1 to 4, wherein the active energy rays are irradiated in a state in which a support film having a thickness greater than that of the transparent resin film is bonded to the second main surface of the transparent resin film.

6. The method for producing a hard coat film described in Claim 5, wherein the support film is a laminate having an adhesive layer on a surface of the film, and the adhesive layer of the support film is bonded to the second main surface of the transparent resin film.

7. A method for producing a hard coat film described in claim 5 or 6, wherein after irradiation with the active energy rays, the support film is peeled off from the second main surface of the transparent resin film.

8. The method for producing a hard coat film according to any one of claims 1 to 7, further comprising the step of heating the film after the irradiation with the active energy rays.

9. The method for producing a hard coat film according to any one of claims 1 to 8, wherein the hard coat layer has a linear expansion coefficient greater than a linear expansion coefficient of the transparent resin film.

10. The method for producing a hard coat film according to any one of claims 1 to 9, wherein the transparent resin film comprises one or more resin materials selected from the group consisting of polyester, polycarbonate, polyamide, polyimide, cyclic polyolefin, acrylic resin, and cellulose-based resin.

11. The method for producing a hard coat film according to any one of claims 1 to 10, wherein the transparent resin film has a thickness of 10 to 150 µm.

12. The method for producing a hard coat film according to any one of claims 1 to 11, wherein the hard coat layer has a thickness of 2 to 150 µm.

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