Polarizing film, optical film, and image display device

Abstract

Provided is a polarizing film in which a resin protective film is laminated on at least one surface of a polarizer via a molecular bonding layer, the polarizer being a polyvinyl alcohol-based resin film having a thickness of 10 [mu] m or less and an iodine concentration of 5.5 mass% or more, and the molecular bonding layer being formed from at least a molecular binder. The molecular binder is a triazine ring-containing compound having at least a reactive group A and a reactive group B. The reactive group A is at least one functional group selected from the group consisting of an amino group, an azide group, a diazomethyl group, a bis (aziridinyl) group, a mercapto group, an isocyanate group, a urea group, and an epoxy group. The reactive group B is at least one functional group selected from the group consisting of silanol groups and groups capable of generating silanol groups by hydrolysis reaction.

Description

Technical Field

[0001] The present invention relates to a polarizing film having a resin protective film laminated on at least one side of a polarizer via a molecular bonding layer. The polarizing film can be used alone or in the form of an optical film laminated with the polarizing film to form an image display device such as a liquid crystal display (LCD), an organic EL display device, a CRT, a PDP, etc. Background Art

[0002] Polarizers are used in image display devices such as liquid crystal display devices. Typically, polarizers can be manufactured by dyeing a polyvinyl alcohol (PVA) resin film with a dichroic substance such as iodine. In recent years, the demand for thinner image display devices has been increasing. Therefore, there is a demand for thinner polarizers. However, since there is a limit to the amount of iodine that can be introduced into a PVA resin film through the dyeing process, if the polarizer is simply thinned, the ratio of iodine to PVA remains unchanged, and the iodine content decreases as the PVA resin film becomes thinner. As a result, the transmittance of the polarizer increases, causing a decrease in polarization characteristics. Therefore, a polarizer with a higher iodine content than before is required. However, in polarizers with a higher iodine content, there is a durability problem that the optical characteristics are significantly reduced in a high temperature and high humidity environment.

[0003] On the other hand, in the following patent document 1, for the purpose of suppressing the poor appearance caused by the heat shrinkage of the polyvinyl alcohol-based polarizing film and providing a polarizing plate with excellent durability, the following technology is recorded: in a polarizing plate comprising a polarizing film formed of a polyvinyl alcohol-based resin and a light-transmitting supporting substrate laminated on at least one side of the polarizing film via a bonding layer, the bonding layer is formed by a material containing a molecular bonding agent, and the molecular bonding agent connects the polarizing film and the supporting substrate by chemical bonding.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: WO2022 / 172755 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The subject of the technology described in Patent Document 1 is to suppress the appearance defect caused by the heat shrinkage of the polyvinyl alcohol-based polarizing film, but it does not mention the decrease of the polarization degree in a high-temperature and high-humidity environment at all.

[0009] The present invention has been developed in view of the above-mentioned actual situation, and an object of the present invention is to provide a polarizing film in which a decrease in polarization degree in a high-temperature and high-humidity environment is suppressed.

[0010] Furthermore, an object of the present invention is to provide an optical film using the polarizing film, and to provide an image display device using the polarizing film or the optical film.

[0011] Solutions to the problem

[0012] The inventors of the present invention have repeatedly conducted in-depth research to solve the above-mentioned problems, and as a result, have found that the above-mentioned purpose can be achieved by using a polarizer designed to have a specific thickness and iodine concentration, and a polarizing film formed by laminating the polarizer with a resin protective film via a molecular bonding layer formed by a specific molecular binder, thereby solving the present invention.

[0013] That is, the present invention relates to a polarizing film (1), which is a polarizing film having a resin protective film laminated on at least one side of a polarizer via a molecular bonding layer, wherein the polarizer is a polyvinyl alcohol resin film having a thickness of 10 μm or less and an iodine concentration of 5.5% by mass or more, and the molecular bonding layer is formed of at least a molecular bonding agent.

[0014] The molecular binder is a triazine ring-containing compound having at least a reactive group A and a reactive group B, wherein the reactive group A is at least one functional group selected from an amino group, an azido group, a diazomethyl group, a diaziridine group, a thiol group, an isocyanate group, a urea group and an epoxy group, and the reactive group B is at least one functional group selected from a silanol group and a group capable of generating a silanol group through a hydrolysis reaction.

[0015] In the above polarizing film (1), preferably, the polarizing film (2) is one in which the triazine ring-containing compound is a triazine ring-containing compound represented by the following general formula (1):

[0016] [Chemical formula 1]

[0017]

[0018] (Among them, R 1 and R 2 is at least one functional group selected from the group consisting of an amino group, an azido group, a diazomethyl group, a diaziridinyl group, a thiol group, an isocyanate group, a urea group, and an epoxy group, and R 1 With R 2 They may be the same functional groups or different functional groups. Y is a divalent organic group. X is at least one functional group selected from a silanol group and a group that can generate a silanol group through a hydrolysis reaction.

[0019] In the above polarizing film (1) or (2), the polarizing film (3) is preferred, wherein R of the triazine ring-containing compound represented by the above general formula (1) is 1 and R 2 Either or both of them are amino groups.

[0020] In the above polarizing film (1) or (2), the polarizing film (4) is preferred, wherein R of the triazine ring-containing compound represented by the above general formula (1) is 1 and R 2 Either or both of them are azido groups.

[0021] In any one of the above polarizing films (1) to (4), preferably, the polarizing film (5) is configured such that the molecular bonding layer has a thickness of 0.001 to 0.200 μm.

[0022] Among any of the polarizing films (1) to (5), the preferred polarizing film is a polarizing film (6), wherein, when the iodine concentration of the polarizer is α mass % and the thickness of the molecular bonding layer is β μm, α / β is 27.5 to 11500.

[0023] Furthermore, the present invention relates to an optical film (7) in which at least one polarizing film is laminated.

[0024] Furthermore, the present invention relates to an image display device (8) using any one of the polarizing films (1) to (6) or the optical film (4).

[0025] Effects of the Invention

[0026] As described above, as the polarizing film becomes thinner, the polarization degree decreases in a high temperature and high humidity environment, thereby causing a problem of deterioration in optical properties. The polarizing film of the present invention uses a polyvinyl alcohol resin film with a thickness of less than 10 μm and an iodine concentration of more than 5.5% by mass as a polarizer, thereby achieving excellent polarization properties and thinness, but the reduction in polarization degree in a high temperature and high humidity environment cannot be suppressed by such a polarizer alone. The polarizing film of the present invention further utilizes a molecular bonding layer formed by a specific molecular binder to laminate the above-mentioned polarizer and the resin protective film together. As a result, a polarizing film in which the reduction in polarization degree in a high temperature and high humidity environment is suppressed can be formed. The reason why such an effect can be obtained is not yet clear, but it can be speculated as follows.

[0027] In order to achieve both excellent polarization characteristics and thinness, it is necessary to suppress the phenomenon of iodine leakage from the polarizer under high temperature and high humidity (hereinafter also referred to as "iodine leakage"). The present inventors have conducted in-depth research and found that by laminating the above-mentioned specific polarizer with a resin protective film using a molecular bonding layer formed by a specific molecular binder, specifically a triazine ring-containing compound having a reactive group A and a reactive group B, the swelling of the polarizer under high temperature and high humidity can be suppressed, and the leakage of iodine from the polarizer can be suppressed. As a result, the humidification reliability of the polarization characteristics of the polarizing film is significantly improved. That is, in the present invention, a polyvinyl alcohol-based resin film with a thickness of less than 10 μm and an iodine concentration of more than 5.5% by mass is used as a polarizer, and the polarizer is laminated with a resin protective film using a molecular bonding layer formed by a specific molecular binder, specifically a triazine ring-containing compound having a reactive group A and a reactive group B. Only then was it achieved for the first time to suppress the reduction in the polarization degree of the polarizing film in a high temperature and high humidity environment. The reason for such a significant effect is not yet clear, but it is presumed to be due to the following reasons: the triazine ring-containing compound forms a strong covalent bond with both the polarizer and the resin protective film via the reactive group A and the reactive group B, thereby suppressing the expansion of the polarizer under high temperature and high humidity, and as a result, suppressing the leakage of iodine from the polarizer. In particular, when a molecular bonding layer is formed using the triazine ring-containing compound represented by the general formula (1), the decrease in the polarization degree of the polarizing film in a high temperature and high humidity environment can be significantly suppressed. DETAILED DESCRIPTION

[0028] The polarizing film of the present invention includes a resin protective film laminated on at least one surface of a polarizer via a molecular bonding layer, and the molecular bonding layer is formed of at least a molecular bonding agent.

[0029] <Molecular bonding layer>

[0030] The molecular binder forming the molecular bonding layer is a triazine ring-containing compound having at least a reactive group A and a reactive group B. The reactive group A is at least one functional group selected from an amino group, an azido group, a diazomethyl group, a diaziridinyl group, a mercapto group, an isocyanate group, a urea group, and an epoxy group. As for the amino group, unsubstituted or substituted amino groups, primary ammonium groups, secondary ammonium groups, tertiary ammonium groups, and quaternary ammonium groups can be cited, and preferably, for example, aminoethyl groups, aminoethylamino groups, and the like can be cited.

[0031] The reactive group B is at least one functional group selected from a silanol group and a group capable of generating a silanol group by a hydrolysis reaction. The group capable of generating a silanol group by a hydrolysis reaction is a group represented by "Si-Z", and Z includes: an alkoxy group having 1 to 10 carbon atoms such as a methoxy group, an ethoxy group, an n- or iso-propoxy group; and a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0032] In the present invention, the triazine ring-containing compound is preferably a triazine ring-containing compound represented by the following general formula (1):

[0033] [Chemical formula 2]

[0034]

[0035] (Among them, R 1 and R 2 is at least one functional group selected from the group consisting of an amino group, an azido group, a diazomethyl group, a diaziridinyl group, a thiol group, an isocyanate group, a urea group, and an epoxy group, and R 1 With R 2 It can be the same functional group or different functional groups. Y is a divalent organic group. X is at least one functional group selected from a silanol group and a group that can generate a silanol group by hydrolysis reaction. Y is an alkylene group having 1 to 10 carbon atoms such as a methylene group, an ethylene group or a propylene group, and an amino group and a group that can generate a silanol group by hydrolysis reaction are the same as above.

[0036] In the present invention, especially when the compound represented by the general formula (1) is used as a molecular binder, the molecular bonding layer can further suppress the swelling of the polarizer, resulting in a significant improvement in the humidification reliability of the polarization characteristics of the polarizing film. The reason for such a significant effect is not yet clear, but it can be inferred as follows.

[0037] The triazine ring-containing compound represented by the general formula (1) comprises a functional group X and two or more functional groups bonded to the 2nd and 4th positions of the triazine ring, wherein the functional group X has a maximum of three silanol groups and / or a group capable of generating a silanol group by a hydrolysis reaction, and the two or more functional groups bonded to the 2nd and 4th positions of the triazine ring are specifically at least one R selected from the group consisting of an amino group, an azido group, a diazomethyl group, a diaziridinyl group, a mercapto group, an isocyanate group, a urea group and an epoxy group. 1 Base and R 2 Here, for example, when the functional group X of the triazine ring-containing compound represented by the general formula (1) first reacts with the functional group on the surface of the resin protective film, due to the stereostructure of the triazine ring, R 1 Base and R 2 At least one of the bases is located at a position extending toward the polarizer side. 1 Base and R 2At least one of the groups is likely to react with the functional groups on the surface of the polarizer. Therefore, the triazine ring-containing compound represented by the general formula (1) is likely to form a covalent bond with both the polarizer and the resin protective film. As a result, even if the polarizing film is exposed to high temperature and high humidity, the swelling of the polarizer can be suppressed at a high level, and as a result, the reduction in polarization degree can be very effectively suppressed. It should be noted that even in the case where the functional group X of the triazine ring-containing compound represented by the general formula (1) first reacts with the functional group on the surface of the polarizer, or R 1 Base and R 2 In the case where at least one of the triazine rings reacts with the resin protective film first and then with the polarizer, or in the case where the triazine ring reacts with the polarizer first and then with the resin protective film, the same effect as described above can be obtained due to the stereostructure of the triazine ring. That is, the triazine ring-containing compound represented by the general formula (1) can ultimately form a covalent bond with the polarizer and the resin protective film with extremely good efficiency. Therefore, even if the polarizing film is exposed to high temperature and high humidity, the swelling of the polarizer can be suppressed, and as a result, the reduction in polarization degree can be suppressed extremely effectively.

[0038] From the viewpoint of further suppressing the decrease in polarization degree in a high-temperature and high-humidity environment, the triazine ring-containing compound represented by the general formula (1) is preferably R 1 and R 2 A triazine ring-containing compound in which either or both of R 1 and R 2 A triazine ring-containing compound in which either or both of them are an azido group.

[0039] The triazine ring-containing compound may be used alone or in combination of two or more. For example, the molecular bonding layer may be formed using the following two molecular bonding agents among the triazine ring-containing compounds represented by the general formula (1): 1 Base and R 2 A compound containing at least one selected from a silanol group and a group capable of generating a silanol group by hydrolysis as a functional group X; and a compound containing an amino group as R 1 Base and R 2 A compound containing, as the functional group X, at least one selected from a silanol group and a group capable of generating a silanol group by a hydrolysis reaction.

[0040] The triazine ring-containing compound used in the present invention can form strong covalent bonds with both the polarizer and the resin protective film via the reactive group A and the reactive group B. Therefore, even if the molecular bonding layer of the present invention is thin, it is possible to suppress the swelling of the polarizer. Therefore, from the viewpoint of thinning, the thickness of the molecular bonding layer is preferably 0.001 to 0.200 μm, more preferably 0.003 to 0.070 μm, and even more preferably 0.005 to 0.060 μm.

[0041] In order to improve the polarization degree of the polarizing film, it is preferred to increase the iodine concentration of the polarizer as much as possible, but if the iodine concentration of the polarizer is high, iodine leakage is also likely to occur. In the polarizing film of the present invention, if α / β is set to 27.5~11500 when the iodine concentration of the polarizer is set to α mass% and the thickness of the molecular bonding layer is set to βμm, the polarization characteristics of the polarizer are excellent, and the decrease in polarization degree in a high temperature and high humidity environment can be more effectively suppressed, so it is preferred. The reason why a better effect is exerted by setting α / β within the above range is not yet clear, but it can be inferred as follows: the higher the iodine concentration α, the easier it is for iodine to transfer to the adjacent molecular bonding layer (iodine is easy to leak), so the thinner the thickness β of the molecular bonding layer is, the more iodine leakage can be suppressed. In order to further improve the effect, α / β is more preferably 107~3833, and more preferably 125~2300.

[0042] <Polarizing filter>

[0043] In the present invention, a polyvinyl alcohol resin film having a thickness of 10 μm or less and an iodine concentration of 5.5% by mass or more is used as a polarizer. In order to further improve the polarization degree of the polarizing film, the iodine concentration of the polarizer is preferably set to 7.5% by mass or more. In addition, from the viewpoint of thinning, the thickness of the polarizer is preferably 10 μm or less, more preferably 5 μm or less. The above-mentioned polarizer can be, for example, a film obtained by adsorbing iodine on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and a partially saponified film of an ethylene-vinyl acetate copolymer and then uniaxially stretching it.

[0044] The polarizer formed by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching can be made, for example, as follows: dyeing is performed by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching to 3 to 7 times the initial length. As required, it can also be immersed in an aqueous solution of potassium iodide or the like optionally containing boric acid, zinc sulfate, zinc chloride, etc. In addition, as required, the polyvinyl alcohol film can also be immersed in water and washed before dyeing. By washing the polyvinyl alcohol film with water, not only can the stains and anti-adhesion agents on the surface of the polyvinyl alcohol film be cleaned, but also the effect of preventing uneven dyeing, etc., by swelling the polyvinyl alcohol film. Stretching can be performed after dyeing with iodine, or it can be stretched while dyeing, and it can also be dyed with iodine after stretching. It can also be stretched in an aqueous solution of boric acid, potassium iodide, etc., or in a water bath.

[0045] From the perspective of tensile stability and humidification reliability, the polarizer preferably contains boric acid. In addition, from the perspective of suppressing the occurrence of through cracks, the boric acid content contained in the polarizer is preferably 22% by mass or less, and more preferably 20% by mass or less relative to the total amount of the polarizer. From the perspective of tensile stability and humidification reliability, the boric acid content is preferably 10% by mass or more, and more preferably 12% by mass or more relative to the total amount of the polarizer.

[0046] Typical thin polarizers include those described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014 / 077599, International Publication No. 2014 / 077636, etc., or those obtained by the production methods described in these documents.

[0047] As the above-mentioned thin polarizer, in the manufacturing method including the step of stretching in the state of a laminate and the step of dyeing, from the viewpoint of being able to stretch to a high ratio and thus improving the polarization performance, it is preferable to use a thin polarizer obtained by a manufacturing method including the step of stretching in a boric acid aqueous solution as described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, and Japanese Patent No. 4815544, and it is particularly preferable to use a thin polarizer obtained by a manufacturing method including the step of auxiliary stretching in a gas atmosphere before stretching in a boric acid aqueous solution as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544. These thin polarizing films can be obtained by a manufacturing method including the step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as a PVA resin) layer and a stretching resin substrate in the state of a laminate and the step of dyeing. According to this production method, even if the PVA-based resin layer is thin, it can be stretched by being supported by the stretchable resin substrate without causing problems such as breakage due to stretching.

[0048] <Resin protective film>

[0049] As the material constituting the resin protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier, isotropy, etc. can be used. As a specific example of such a thermoplastic resin, cellulose resins such as cellulose triacetate resin films, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof can be cited. The transparent protective film may contain one or more arbitrary appropriate additives. As additives, for example, ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc. The content of the above-mentioned thermoplastic resin in the resin protective film is preferably 50~100% by mass, more preferably 50~99% by mass, further preferably 60~98% by mass, and particularly preferably 70~97% by mass. When the content of the thermoplastic resin in the resin protective film is 50% by mass or less, there is a concern that high transparency and the like inherent in the thermoplastic resin may not be fully exhibited.

[0050] In addition, as a material for forming the resin protective film, a material having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. is preferred, and a material having a moisture permeability of 150 g / m 2 / 24h or less, more preferably a moisture permeability of 140g / m 2 / 24h or less, more preferably a material with a moisture permeability of 120g / m 2 / Materials under 24h.

[0051] A functional layer such as a hard coating layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer or an anti-glare layer may be provided on the side of the resin protective film that is not bonded to the polarizer. It should be noted that the functional layers such as the hard coating layer, the anti-reflection layer, the anti-adhesion layer, the diffusion layer or the anti-glare layer may be provided as a layer different from the resin protective film in addition to being provided to protect the resin protective film itself.

[0052] The thickness of the resin protective film can be appropriately determined, and is generally about 1 to 500 μm, preferably 1 to 300 μm, more preferably 5 to 200 μm, further preferably 10 to 80 μm, and further preferably 10 to 40 μm from the perspectives of strength, workability such as handling, and thinness.

[0053] The polarizing film of the present invention can be further laminated with a phase difference film to form an optical film. As the phase difference film, there can be cited: a birefringent film formed by uniaxial or biaxial stretching of a polymer raw material, an oriented film of a liquid crystal polymer, and a material formed by supporting an oriented layer of a liquid crystal polymer with a film. The thickness of the phase difference film is not particularly limited, and is usually about 20 to 150 μm.

[0054] As the retardation film, a reverse wavelength dispersion type retardation film satisfying the following formulas (1) to (3) can be used:

[0055] 0.70<Re

[450] / Re

[550] <0.97・・・(1)

[0056] 1.5×10 -3 <Δn<6×10 -3 ・・・(2)

[0057] 1.13<NZ<1.50・・・(3)

[0058] (Wherein, Re

[450] and Re

[550] are the in-plane phase difference values ​​of the phase difference film measured at 23°C using light of wavelengths of 450nm and 550nm, respectively; Δn is the in-plane birefringence, which is nx-ny when the refractive indices in the slow axis direction and fast axis direction of the phase difference film are set to nx and ny, respectively; NZ is the ratio of nx-nz to nx-ny when nz is set to the refractive index in the thickness direction of the phase difference film, wherein nx-nz is the birefringence in the thickness direction and nx-ny is the in-plane birefringence).

[0059] The polarizing film of the present invention may be provided with a phase difference layer. The phase difference layer may be a single layer or a multi-layer layer.

[0060] In the formation of the phase difference layer, it is preferred to use a liquid crystal compound, and a solution containing the liquid crystal compound can be applied using, for example, a wire rod, a slit coater, a comma coater, a gravure coater, a slit die, etc. At this time, the applied liquid crystal solution can be dried naturally or heated and dried. It should be noted that the liquid crystal solution is preferably applied at a concentration lower than the isotropic phase-liquid crystal phase transition concentration, i.e., in the isotropic phase state. In this case, it can be stably oriented by methods such as friction treatment and photo-orientation.

[0061] The polarizing film of the present invention can be produced, for example, by the following production method.

[0062] The method is a method for manufacturing a polarizing film in which a resin protective film is laminated on at least one side of a polarizer via a molecular bonding layer, wherein the polarizer is a polyvinyl alcohol resin film with a thickness of less than 10 μm and an iodine concentration of more than 5.5 mass %, and the method comprises: a coating step of coating a molecular binder on either or both of the bonding surface of the polarizer and the bonding surface of the resin protective film; a bonding step of bonding the polarizer and the resin protective film; and a step of irradiating the polarizer and the resin protective film with active energy rays from the polarizer surface side or the resin protective film surface side, or The resin protective film is heated to cure the molecular binder, and the polarizer and the resin protective film are bonded via the molecular bonding layer obtained thereby, wherein the molecular binder is a triazine ring-containing compound having at least a reactive group A and a reactive group B, wherein the reactive group A is at least one functional group selected from an amino group, an azido group, a diazomethyl group, a diaziridine group, a mercapto group, an isocyanate group, a urea group, and an epoxy group, and the reactive group B is at least one functional group selected from a silanol group and a group capable of generating a silanol group by a hydrolysis reaction. Each step is described below.

[0063] <Coating process>

[0064] In the coating process, the molecular binder is coated on either or both of the bonding surface of the polarizer and the bonding surface of the resin protective film. During coating, the molecular binder can be directly coated, or it can be coated in the form of a molecular binder-containing composition in which a solvent and / or an additive are added to the molecular binder. As a solvent, a solvent that can stabilize the above-mentioned triazine ring-containing compound and dissolve or disperse it is preferred. Such a solvent can use an organic solvent, water, or a mixed solvent thereof. As the above-mentioned solvent, for example, it can be selected from the following: esters such as ethyl acetate, butyl acetate, and 2-hydroxyethyl acetate; ketones such as methyl ethyl ketone, acetone, cyclohexanone, methyl isobutyl ketone, diethyl ketone, methyl n-propyl ketone, and acetylacetone; cyclic ethers such as tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, and cyclohexanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether; glycol ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; and the like. Examples of additives include: binder resins, surfactants, plasticizers, tackifiers, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, anticorrosives, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, titanium coupling agents, inorganic or organic fillers, metal powders, particles, foils, etc. As the binder resin, any one that is transparent may be mentioned, and examples include polymers such as acrylic resins, styrene resins, polyvinyl alcohol resins, polyurethane resins, polyester resins, polypropylene resins, polyethylene resins, epoxy resins, and polycarbonate resins.

[0065] In the case of a composition containing a molecular binder in which a solvent and / or an additive is added to the molecular binder, the concentration of the molecular binder in the composition containing the molecular binder is not particularly limited. Its concentration is preferably 0.05 to 10.00% by mass, more preferably 0.10 to 1.00% by mass. By setting the concentration of the molecular binder to 0.05% by mass or more, the molecular binder can be effectively imparted to the polarizer and / or the resin protective film. In addition, by setting it to 10.00% by mass or less, the unintended reaction in the composition containing the molecular binder can be suppressed, and the stability of the solution is excellent.

[0066] As a method for directly coating the molecular binder, or preparing a molecular binder-containing composition in which a solvent and / or additives are added to the molecular binder and coating, it can be appropriately selected according to the molecular binder, the viscosity of the composition, and the target thickness, and examples thereof include: a reverse coater, a gravure coater (direct, reverse, or offset), a rod-type reverse coater, a roll coater, a die coater, a wire rod coater, and a rod coater. The viscosity of the molecular binder-containing composition is preferably 3 to 100 mPa·s, more preferably 5 to 50 mPa·s, and most preferably 10 to 30 mPa·s. When the viscosity of the composition is high, the surface smoothness after coating is insufficient, and a poor appearance may occur, which is not preferred.

[0067] When a molecular binding agent-containing composition containing a solvent and / or an additive is used, a drying step is provided after the coating step to remove the solvent. The drying step may be air drying or heat drying to a degree that the molecular binding agent does not react or modify.

[0068] For the polarizer and / or the resin protective film, it is preferred to perform a surface modification treatment before the coating process. As the surface modification treatment, corona treatment, plasma treatment, ITRO treatment and the like can be cited, and corona treatment is particularly preferred. By performing the corona treatment, reactive functional groups such as carbonyl and amino groups can be generated on the surface of the polarizer and the resin protective film, thereby improving the adhesion with the molecular bonding layer and inhibiting the swelling of the polarizer. In addition, foreign matter on the surface can be removed or the surface unevenness can be reduced by the ashing effect, thereby making a polarizing film with excellent appearance characteristics.

[0069] <Lamination process>

[0070] The polarizer and the resin protective film are bonded together using a roll laminator or the like through the molecular binder applied as described above.

[0071] <Bonding process>

[0072] After the polarizer and the resin protective film are laminated, the molecular binder is cured by irradiating active energy rays (electron beam, ultraviolet light, visible light, etc.) or heating the laminated polarizer and the resin protective film to form a molecular bonding layer. In the case of heating, as a heating condition, it is preferably heated at 40° C. for 24 hours. In addition, in the case of irradiating active energy rays (electron beam, ultraviolet light, visible light, etc.), the irradiation direction can be irradiated from any appropriate direction.

[0073] The irradiation conditions when irradiating with electron beams can be any appropriate conditions as long as they are conditions that can cure the above-mentioned molecular binder. For example, the acceleration voltage of electron beam irradiation is preferably 5kV~300kV, and more preferably 10kV~250kV. When the acceleration voltage is less than 5kV, there is a risk that the electron beam cannot reach the molecular binder and cause insufficient curing. If the acceleration voltage exceeds 300kV, there is a risk that the penetration force through the sample is too strong and damages the polarizer and the resin protective film. As an irradiation dose, it is 5~100kGy, and more preferably 10~75kGy. When the irradiation dose is less than 5kGy, the molecular binder is insufficiently cured. If it is greater than 100kGy, it will damage the polarizer and the resin protective film, resulting in a decrease in mechanical strength and yellowing, and the given optical properties cannot be obtained.

[0074] Electron beam irradiation is usually performed in an inert gas, but can be performed in the atmosphere under conditions where a small amount of oxygen is introduced as needed. Although it depends on the materials of the polarizer and the resin protective film, by appropriately introducing oxygen, the polarizer and the resin protective film that are initially irradiated with the electron beam will instead produce oxygen barriers, thereby preventing damage to the polarizer and the resin protective film, and allowing the electron beam to be efficiently irradiated only to the molecular binder.

[0075] In the case of manufacturing the polarizing film of the present invention, when the reactive group A possessed by the triazine ring-containing compound as a molecular binder is an azido group, a diazomethyl group or a diaziridinyl group, it is preferred to irradiate light (ultraviolet rays) across the resin protective film. By irradiating light (ultraviolet rays), the azido group, diazomethyl group or diaziridinyl group possessed by the triazine ring-containing compound as a molecular binder decomposes to generate nitre. The nitre will attack the functional groups (for example, -CH3, -CH2-, -CH<, -CH=CH-) on the surface of the adherend (polarizer and / or resin protective film). Furthermore, hydrogen abstraction radical addition or radical addition reaction will occur to generate a chemical bond between the molecular binder and the surface of the adherend. It should be noted that chemical bonds will not be generated in the unirradiated area. Light (ultraviolet rays) irradiation can be performed using, for example, a UV irradiation device (for example, a high-pressure mercury UV lamp, a low-pressure mercury UV lamp, a fluorescent UV lamp (short arc xenon lamp, chemical lamp), a metal halide lamp). The wavelength of the irradiated ultraviolet light is preferably 200 to 450 nm. If the irradiation light amount is too small, the reaction is difficult to proceed. On the contrary, if the irradiation light amount is too large, there is a risk of degradation of the adherend. In the embodiment of the present application, when the molecular binder contains an azide group, the preferred irradiation light amount (light source wavelength: 254 nm) is 1 mJ / cm 2 ~5J / cm 2 , more preferably 5 mJ / cm 2 ~1J / cm 2 In the present embodiment, the transmittance of the resin protective film at a wavelength of 254 nm is preferably 10% or more, and more preferably 20% or more.

[0076] When the polarizing film of the present invention is manufactured by a continuous production line, the line speed depends on the curing time of the molecular binder, but is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and further preferably 10 to 100 m / min. When the line speed is too low, productivity is insufficient, or damage to the polarizer or the resin protective film is too large, and a polarizing film that can withstand durability tests, etc. cannot be produced. When the line speed is too high, the curing of the molecular binder sometimes becomes insufficient, and the target adhesion cannot be obtained.

[0077] An adhesive layer for bonding to other components such as a liquid crystal cell may be provided on the polarizing film or the optical film laminated with at least one polarizing film. The adhesive forming the adhesive layer is not particularly limited, and an adhesive having a base polymer such as acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine, rubber, etc. may be appropriately selected and used. It is particularly preferred to use an adhesive such as an acrylic adhesive that has excellent optical transparency and exhibits appropriate adhesive properties such as wettability, cohesion and adhesion, and has excellent weather resistance, heat resistance, etc.

[0078] The adhesive layer may be provided on one or both sides of the polarizing film or optical film in the form of a laminated layer of layers of different compositions or types. In addition, when provided on both sides, adhesive layers of different compositions, types, thicknesses, etc. may be formed on the front and back sides of the polarizing film or optical film. The thickness of the adhesive layer may be appropriately determined according to the purpose of use, adhesive strength, etc., and is usually 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

[0079] The exposed surface of the adhesive layer is temporarily covered by a separator for the purpose of preventing contamination until it is actually used. Thus, it is possible to prevent contact with the adhesive layer under normal handling conditions. As a separator, in addition to the above-mentioned thickness conditions, a separator such as a plastic film, a rubber sheet, paper, a cloth, a non-woven fabric, a net, a foam sheet, a metal foil, a laminate thereof, etc., can be coated with an appropriate release agent such as silicone, long-chain alkyl, fluorine, molybdenum sulfide as needed, and other suitable thin layers such as a separator prescribed in the past can be used.

[0080] The polarizing film and optical film of the present invention can be preferably used for forming various devices such as liquid crystal display devices. The formation of the liquid crystal display device can be carried out in a conventional manner. That is, the liquid crystal display device is usually formed by appropriately assembling a liquid crystal cell with a polarizing film or an optical film, and components such as a lighting system used as needed, and loading a driving circuit, etc. In the present invention, except for the use of the polarizing film or optical film of the present invention, there is no particular limitation, and it can be carried out in a conventional manner. Regarding the liquid crystal cell, any type of liquid crystal cell such as TN type, STN type, π type, etc. can be used.

[0081] A suitable liquid crystal display device such as a liquid crystal display device with an optical laminated body disposed on one side or both sides of a liquid crystal cell, a liquid crystal display device using a backlight or a reflector in a lighting system can be formed. In this case, the optical laminated body of the present invention can be disposed on one side or both sides of the liquid crystal cell. In the case where the optical laminated body is disposed on both sides, they can be the same or different. Furthermore, when forming a liquid crystal display device, suitable components such as a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, etc., can be configured at an appropriate position.

[0082] Example

[0083] Although examples of the present invention are described below, the embodiments of the present invention are not limited to these.

[0084] <Polarizing filter>

[0085] First, a stretched laminate is formed by auxiliary stretching in a gas atmosphere at a stretching temperature of 130° C. from a laminate having a 9 μm thick PVA layer formed on an amorphous PET substrate. Next, a colored laminate is formed by dyeing from the stretched laminate. The colored laminate is further stretched in a boric acid aqueous solution at a stretching temperature of 65 degrees to form an optical film laminate including a 5 μm thick PVA layer by a total stretching ratio of 5.94 times. Thus, an optical film laminate including a 5 μm thick PVA layer (thin polarizer) constituting an iodine-based thin polarizer (polarizer thickness 5 μm, iodine concentration α of the polarizer 8.2 mass%) is obtained. The iodine-based thin polarizer is an iodine-based thin polarizer in which the PVA molecules of the PVA layer formed on the amorphous PET substrate are highly oriented by the two-stage stretching as described above, and the iodine adsorbed by dyeing is highly oriented in one direction in the form of a polyiodide ion complex.

[0086] <Resin protective film>

[0087] Cyclic olefin polymer (COP); trade name "Zeonor Film ZF14", manufactured by Zeonor Co., Ltd.

[0088] Polycarbonate polymers (PC)

[0089] First, a polyester carbonate resin is produced, and then film-formed to produce a resin protective film.

[0090] (Polymerization of polyester carbonate resins)

[0091] Relative to 81.98 parts by mass of isosorbide (hereinafter, sometimes abbreviated as "ISB"), 47.19 parts by mass of tricyclodecane dimethanol (hereinafter, sometimes abbreviated as "TCDDM"), 175.1 parts by mass of diphenyl carbonate (hereinafter, sometimes abbreviated as "DPC"), and 0.979 parts by mass of a 0.2% aqueous solution of cesium carbonate as a catalyst were put into a reaction vessel, and in a nitrogen atmosphere, as the first stage of the reaction, the heating tank temperature was heated to 150°C, and the raw materials were dissolved while stirring as needed (about 15 minutes). Next, the pressure was changed from normal pressure to 13.3 kPa, and the heating tank temperature was raised to 190°C in 1 hour, while the generated phenol was extracted outside the reaction vessel. After the entire reaction vessel was kept at 190°C for 15 minutes, as the second stage, the pressure in the reaction vessel was 6.67 kPa, and the heating tank temperature was raised to 230°C in 15 minutes, and the generated phenol was extracted outside the reaction vessel. The stirring torque of the stirrer gradually increased, so the pressure in the reaction container was kept below 0.200 kPa in order to raise the temperature to 250° C. in 8 minutes and remove the generated phenol. After reaching the predetermined stirring torque, the reaction was terminated and the generated reactant was extruded into water to obtain polycarbonate resin pellets.

[0092] (Production of resin protective film)

[0093] The obtained polycarbonate resin was vacuum dried at 80°C for 5 hours, and then an optical film made of the polycarbonate resin was produced using a film forming apparatus equipped with a single screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 300 mm, setting temperature: 250°C), a chill roll (setting temperature: 120-130°C) and a winder. The obtained optical film had a wavelength dispersion value of 1.02, an in-plane retardation Re (550) of 2 nm, and a thickness of 13 μm.

[0094] <Active energy rays>

[0095] In Example 2, a UV-LED irradiation device manufactured by Quark Technology was used as the active energy ray to provide UV irradiation (265 nm, 100 mJ / cm 2 ) was irradiated. In Comparative Example 1, as the active energy ray, visible light (metal halide lamp enclosed in gallium) was used. Irradiation device: LightHAMMER10 manufactured by Fusion UV Systems, Inc. Valve: V valve, peak illuminance: 1600 mW / cm 2 , cumulative irradiation 1000mJ / cm 2 (wavelength 380~440nm).

[0096] <Molecular binding agent>

[0097] ·6-(3-triethoxysilylpropyl)amino-1,3,5-triazine-2,4-diazide (the compound described in the general formula (1) (R 1 and R 2 is an azido group); manufactured by Sulfur Chemical Laboratory Co., Ltd.

[0098] N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (the compound described in the general formula (1) (R 1 and R 2 is 2-aminoethyl); manufactured by Sulfur Chemical Laboratory Co., Ltd.

[0099] <Adhesive composition>

[0100] Adhesive composition 1: 15% by mass of hydroxyethyl acrylamide (HEAA) (manufactured by KJ Chemical Co., Ltd.), 30% by mass of acryloyl morpholine (ACMO) (manufactured by KJ Chemical Co., Ltd.), 40% by mass of 1,9-nonanediol dimethacrylate (1,9ND-A) (manufactured by Kyoeisha Chemical Co., Ltd.), 10% by mass of UP1190 (manufactured by Toagosei Co., Ltd.), 3% by mass of 2-methyl-4'-methylthio-2-morpholinopropiophenone (Omnirad 907) (manufactured by IGM RESINS), 2% by mass of diethylthioxanthone (DETX-S) (manufactured by Nippon Kayaku Co., Ltd.)

[0101] Adhesive composition 2: an aqueous solution containing a polyvinyl alcohol resin containing an acetoacetyl group (average degree of polymerization of 1200, degree of saponification of 98.5 mol%, degree of acetoacetylation of 5 mol%) and methylolmelamine at a mass ratio of 3:1

[0102] (Manufacturing of polarizing film)

[0103] Example 1

[0104] A 0.5 mass % aqueous solution of N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine was applied to the bonding surface of the corona-treated resin protective film (COP) and the bonding surface of the polarizer side of the above-mentioned optical film laminate that was also corona-treated (coating process), and after a drying process to remove water as a solvent, the two were bonded using a roll laminator (bonding process), and left at 40°C for 24 hours (bonding process), thereby manufacturing a polarizing film in which a resin protective film was laminated on one side of the polarizer via a molecular bonding layer. The thickness of the molecular bonding layer of the obtained polarizing film was 0.01 μm.

[0105] Example 2

[0106] A 0.5 mass % ethanol aqueous solution of 6-(3-triethoxysilylpropyl)amino-1,3,5-triazine-2,4-diazide was applied to both the bonding surface of the resin protective film (PC) subjected to the corona treatment and the bonding surface of the polarizer side of the above-mentioned optical film laminate subjected to the same corona treatment (coating step), and after a drying step to remove the ethanol as a solvent, the two were bonded using a roll laminator (bonding step), and UV irradiation (265 nm, 100 mJ / cm 2 ) (bonding step) to produce a polarizing film in which a resin protective film was laminated on one side of a polarizer via a molecular bonding layer. The thickness of the molecular bonding layer of the obtained polarizing film was 0.01 μm.

[0107] Comparative Example 1

[0108] The adhesive composition 1 was applied to both the bonding surface of the resin protective film (COP) and the bonding surface of the polarizer side of the optical film laminate (coating step), and the two were bonded using a roll laminator (bonding step), and UV irradiation (380-440nm, 1000mJ / cm 2 ) (bonding step), thereby producing a polarizing film in which the resin protective film was laminated on one side of the polarizer via the adhesive layer. The thickness of the adhesive layer of the obtained polarizing film was 1.54 μm.

[0109] Comparative Example 2

[0110] The adhesive composition 2 was applied to the bonding surface of the resin protective film (COP) and the bonding surface of the polarizer side of the optical film laminate in such a manner that the thickness of the adhesive layer after drying reached 0.1 μm (coating process), and the two were bonded using a roll bonding machine (bonding process), and heated and dried in an oven (90° C.-10 minutes) (bonding process). However, after the bonding process, the resin film and the polarizer were not bonded, and the polarizing film could not be manufactured.

[0111] The following evaluations were performed on the polarizing films produced in Examples 1 and 2 and Comparative Examples 1 and 2.

[0112] (Measurement of the thickness of the molecular bonding layer and the adhesive layer)

[0113] The thickness of the molecular bonding layer and the adhesive layer was measured by cross-sectional TEM observation using HT7820 manufactured by Hitachi Ltd. by cryo-ultra-thin sectioning method including heavy metal staining. The acceleration voltage in the measurement was set to 100 kV.

[0114] (Measurement of bonding strength of molecular bonding layer and adhesive layer)

[0115] Using a tensile tester (VPA-H200), the polarizing film sample cut into strips of 15 mm in width and 10 cm in length was peeled off at an angle of 90° (speed 1000 mm / min) to observe its stress. For the polarizing film sample, No. 5000NS was used to fix it to a plate on the polarizer side, and PI tape No. 360A was backed on the resin protective film side. The resin protective film and PI tape were lifted together for measurement.

[0116] (iodine adsorption)

[0117] First, test pieces of 1 cm × 1 cm were cut out from the resin protective film and the resin protective film with molecular bonding layer, and the mass of the test pieces was measured (average weight per 1 cm). 2 The sample mass (g)). The resin protective film and the resin protective film with a molecular bonding layer were immersed in an iodine solution obtained by mixing 1% by mass of iodine and 7% by mass of potassium iodide in pure water for 4 days. Then, the iodine solution attached to the surface was cleaned with pure water, dried at room temperature, and quantified by an ion chromatograph. The ion chromatograph used the ICS-3000 manufactured by Thermo Fisher Scientific. About 5 mg of the sample was collected, placed in a ceramic dish and weighed, and then a combustion aid was added. Next, an automatic sample combustion device (NittoseikoAnalytech, AQF-2100H) was used to burn it, and the generated gas was captured into 10 mL of absorption liquid. After capture, the absorption liquid was adjusted to 15 mL with ultrapure water, and quantitative analysis was performed using an ion chromatograph. It should be noted that for samples with high concentrations, they were diluted 10 times after capture and quantitative analysis was performed using an ion chromatograph. The measurement conditions are as follows.

[0118] Based on the obtained iodine concentration (μg / g), the sample weight and sample area, the iodine adsorption amount (μg / cm 2 ).

[0119] (Iodine adsorption amount) = (Iodine concentration obtained by measurement (μg / g)) × (Weight of sample collected (g)) / (Area of ​​sample collected (cm 2 ))

[0120] Among them, (the sample area collected (cm 2 ) = weight of sample collected (g) / (average per 1cm 2 Sample weight (g)

[0121] In addition, the iodine adsorption amount of the molecular bonding layer (adhesive layer) was determined using the following formula.

[0122] (Amount of iodine adsorbed by the molecular bonding layer (adhesive layer)) = (Amount of iodine adsorbed by the resin protective film with molecular bonding layer) - (Amount of iodine adsorbed by the resin protective film)

[0123] The ion chromatography conditions were as follows.

[0124] Separation column: Dionex IonPac AS20

[0125] Guard column: Dionex Ion Pac AG20

[0126] Removal system: Dionex ADRS-600 (external mode)

[0127] Detector: Conductivity detector

[0128] · Eluent: KOH aqueous solution (using eluent generator EGCⅢ)

[0129] Eluent flow rate: 1.0mL / min

[0130] Sample injection volume: 250μL

[0131] (Heating and humidification test (transmittance change test))

[0132] The transmittance Ts of the obtained polarizing film was measured using an ultraviolet visible spectrophotometer (V-7100 manufactured by JASCO Corporation), and the single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc were set as Ts, Tp, and Tc of the polarizing film, respectively. These Ts, Tp, and Tc are the Y values ​​obtained by measuring the 2-degree field of view (C light source) of JISZ8701 and correcting for visibility. After exposure to an environment of 60°C and 95%RH for 240 hours, the transmittance Ts of the polarizing film after exposure was measured by the same method, and the transmittance change ΔT(%) was calculated as |(transmittance Ts(%) before exposure) - (transmittance Ts(%) after exposure)|. The smaller the transmittance change ΔT(%), the more the decrease in the degree of polarization of the polarizing film is suppressed in a high temperature and high humidity environment.

[0133]

[0134] According to the results in Table 1, the polarizing films of Examples 1 and 2 can also suppress the swelling of the polarizer under high temperature and high humidity, thereby suppressing the leakage of iodine from the polarizer, and as a result, suppressing the reduction of polarization degree. It should be noted that in the polarizing film of Comparative Example 2, the amount of iodine adsorption in the adhesive layer is reduced, so at first glance, the reduction of polarization degree in a high temperature and high humidity environment seems to be suppressed, but in fact, the swelling of the polarizer cannot be suppressed, and bonding cannot be performed, so it cannot be used as a polarizing film product.

Claims

1. A polarizing film comprising a polarizing film having a resin protective film laminated on at least one side of a polarizer via a molecular bonding layer, The polarizer is a polyvinyl alcohol resin film having a thickness of 10 μm or less and an iodine concentration of 5.5% by mass or more. The molecular bonding layer is formed of at least a molecular bonding agent, The molecular binder is a triazine ring-containing compound having at least a reactive group A and a reactive group B, The reactive group A is at least one functional group selected from an amino group, an azido group, a diazomethyl group, a diaziridinyl group, a thiol group, an isocyanate group, a urea group and an epoxy group, The reactive group B is at least one functional group selected from a silanol group and a group capable of generating a silanol group through a hydrolysis reaction.

2. The polarizing film according to claim 1, wherein The triazine ring-containing compound is a triazine ring-containing compound represented by the following general formula (1): ， in, R 1 and R 2 is at least one functional group selected from the group consisting of an amino group, an azido group, a diazomethyl group, a diaziridinyl group, a thiol group, an isocyanate group, a urea group, and an epoxy group, and R 1 With R 2 are optionally the same functional group or different functional groups, Y is a divalent organic group, X is at least one functional group selected from a silanol group and a group capable of generating a silanol group by a hydrolysis reaction.

3. The polarizing film according to claim 2, wherein: The triazine ring-containing compound represented by the general formula (1) has R 1 and R 2 Either or both of them are amino groups.

4. The polarizing film according to claim 2, wherein: The triazine ring-containing compound represented by the general formula (1) has R 1 and R 2 Either or both of them are azido groups.

5. The polarizing film according to any one of claims 1 to 4, wherein The thickness of the molecular bonding layer is 0.001-0.200 μm.

6. The polarizing film according to any one of claims 1 to 5, wherein When the iodine concentration of the polarizer is α mass % and the thickness of the molecular bonding layer is β μm, α / β is 27.5 to 11500. 7 . An optical film comprising at least one polarizing film according to claim 1 laminated thereon. 8 . An image display device using the polarizing film according to claim 1 or the optical film according to claim 7 .

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