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 molecular bonding layer being formed from at least a molecular bonding agent, the molecular bonding agent being 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, and the reactive group B is at least one functional group selected from the group consisting of a silanol group and a group capable of generating a silanol group by a hydrolysis reaction. A compatible layer in which the molecular bonding layer and the resin protective film are compatible with each other is formed on the resin protective film side of the molecular bonding layer.

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, for 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 studies to solve the above-mentioned problems, and as a result, they have found that a polarizing film in which a polarizer and a resin protective film are stacked via a molecular bonding layer formed by a specific molecular binder, and a compatibility layer is formed on one side of the resin protective film within the molecular bonding layer in which the molecular bonding layer and the resin protective film are compatible with each other, can achieve the above-mentioned purpose, thereby solving the present invention.

[0013] That is, the present invention relates to a polarizing film (1) comprising a resin protective film laminated on at least one side of a polarizer via a molecular bonding layer, wherein 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 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. A compatibility layer formed by the molecular bonding layer and the resin protective film being compatible with each other is formed on one side of the resin protective film of the molecular bonding layer, and the compatibility layer is formed with a thickness of 50 to 90% relative to the thickness of the molecular bonding layer. It should be noted that the method for confirming the compatibility layer will be described later.

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

[0016] [Chemical formula 1]

[0017]

[0018] (In general formula (1), 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 The functional groups are the same or different. 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 hydrolysis reaction.

[0019] In the above polarizing film (2), preferably, the polarizing film (3) is a polarizing film in which 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 (2), preferably, the polarizing film (4) is a polarizing film in which 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] Furthermore, the present invention relates to an optical film (6) in which at least one polarizing film is laminated.

[0023] Furthermore, the present invention relates to an image display device (7) using any one of the polarizing films (1) to (5) or the optical film (6).

[0024] Effects of the Invention

[0025] 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 of optical properties. The polarizing film of the present invention uses a molecular bonding layer formed by a specific molecular binder to laminate the above-mentioned polarizer and resin protective film. As a result, a polarizing film can be formed in which the decrease in polarization degree in a high temperature and high humidity environment is suppressed. The reason for obtaining such an effect is not yet clear, but it can be inferred as follows.

[0026] In order to maintain excellent polarization characteristics, 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 and the 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, a covalent bond can be formed between the molecular bonding layer and the resin protective film, as a result, a compatibility layer can be formed on the resin protective film side of the molecular bonding layer. By forming such a compatibility layer, the polarizer is firmly fixed to the resin protective film, and the expansion of the polarizer under high temperature and high humidity can be suppressed, thereby suppressing the leakage of iodine from the polarizer. As a result, the humidification reliability of the polarization characteristics of the polarizing film is significantly improved. In particular, when the molecular bonding layer is formed using the triazine ring-containing compound represented by the general formula (1), the reduction in the polarization degree of the polarizing film in a high temperature and high humidity environment can be significantly suppressed. DETAILED DESCRIPTION

[0027] 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.

[0028] <Molecular bonding layer>

[0029] 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.

[0030] 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, a n- or iso-propoxy group; and a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0031] In the present invention, the triazine ring-containing compound is preferably a triazine ring-containing compound represented by the following general formula (1):

[0032] [Chemical formula 2]

[0033]

[0034] (Where 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 and an ethylene group, and the amino group and the group that can generate a silanol group by hydrolysis reaction are the same as above.

[0035] In the present invention, in particular, when the compound represented by the general formula (1) is used as a molecular binder, a compatibility layer is formed in a wider range on the resin protective film side of the molecular bonding layer, thereby 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 obtaining such a significant effect is not yet clear, but it can be inferred as follows.

[0036] 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, a compatibility layer is formed on the side of the resin protective film, and 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 2 At 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 bases reacts with the resin protective film first and then with the polarizer, or in the case where the base reacts with the polarizer first and then with the resin protective film, a compatibility layer can be formed on the side of the resin protective film, and due to the stereoscopic structure of the triazine ring, the same effect as described above can be obtained. That is, the triazine ring-containing compound represented by the general formula (1) can eventually form a compatibility layer on the side of the resin protective film of the molecular bonding layer, and form covalent bonds 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 the iodine leakage of the polarizer can be suppressed at a high level. As a result, the reduction in polarization degree can be suppressed extremely effectively.

[0037] 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 them are amino groups.

[0038] The triazine ring-containing compound used in the present invention can form a compatibility layer on one side of the resin protective film, and form a strong covalent bond 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 very thin, it can 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 further preferably 0.005 to 0.060 μm.

[0039] <Polarizing filter>

[0040] In the present invention, in order to further improve the polarization degree of the polarizing film, the iodine concentration of the polarizer is preferably set to 5.5 mass % or more, and more preferably 7.5 mass % or more. In addition, from the viewpoint of thinning, the thickness of the polarizer is preferably 10 μm or less, and 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 the film.

[0041] 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-blocking 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.

[0042] 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 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.

[0043] 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.

[0044] 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 preferred 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 preferred 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 very thin, it can be stretched without causing problems such as breakage due to stretching by being supported by the stretchable resin substrate.

[0045] <Resin protective film>

[0046] 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 specific examples of such thermoplastic resins, 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 to 100% by mass, more preferably 50 to 99% by mass, further preferably 60 to 98% by mass, and particularly preferably 70 to 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.

[0047] 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.

[0048] 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.

[0049] The thickness of the resin protective film can be appropriately determined. Generally, it is 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.

[0050] 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, a material formed by supporting an oriented layer of a liquid crystal polymer with a film, etc. The thickness of the phase difference film is not particularly limited, and is usually about 20 to 150 μm.

[0051] As the retardation film, a reverse wavelength dispersion type retardation film satisfying the following formulas (1) to (3) can be used:

[0052] 0.70<Re

[450] / Re

[550] <0.97···(1)

[0053] 1.5×10 -3 <Δn<6×10 -3 ···(2)

[0054] 1.13<NZ<1.50···(3)

[0055] (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).

[0056] 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.

[0057] 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.

[0058] The polarizing film of the present invention can be produced, for example, by the following production method.

[0059] 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, and the method comprises: a coating step of coating a molecular binder on either or both of the bonding surfaces of the polarizer and the resin protective film; a bonding step of bonding the polarizer and the resin protective film; and a bonding step of curing the molecular binder by irradiating active energy rays from one side of the polarizer surface or the resin protective film surface, or heating the bonded polarizer and the resin protective film, and bonding the polarizer and the resin protective film via the molecular bonding layer thus obtained. The bonding process of the bonding is as follows: the molecular bonding agent 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 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, and a compatibility layer formed by the molecular bonding layer and the resin protective film being compatible with each other is formed on one side of the resin protective film of the molecular bonding layer. The various processes are described below.

[0060] <Coating process>

[0061] In the coating process, the molecular binder is applied to 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 applied directly, or it can be made into a molecular binder-containing composition in which a solvent and / or an additive are added to the molecular binder for coating. As a solvent, a solvent that can stabilize, dissolve or disperse the above-mentioned triazine ring-containing compound 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; tetrahydrofuran (THF), dihydrofuran (THF), Cyclic ethers such as oxane; 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; etc. Examples of additives include binder resins, surfactants, plasticizers, tackifiers, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, titanium coupling agents, inorganic or organic fillers, metal powders, particles, foils, etc. The binder resin may be any one that is transparent, and examples of the binder resin include polymers such as acrylic resins, styrene resins, polyvinyl alcohol resins, polyurethane resins, polyester resins, polypropylene resins, polyethylene resins, epoxy resins, and polycarbonate resins.

[0062] In the case of making a molecular binder-containing composition in which a solvent and / or an additive are added to the molecular binder, the concentration of the molecular binder in the molecular binder-containing composition 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 efficiently imparted to the polarizer and / or the resin protective film. In addition, by setting it to 10.00% by mass or less, it is possible to suppress unexpected reactions in the molecular binder-containing composition, and the stability of the solution is excellent.

[0063] As a method for directly coating a molecular binder, or preparing a composition containing a molecular binder in which a solvent and / or an additive 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 composition containing a molecular binder 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.

[0064] 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.

[0065] 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 suppressing 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.

[0066] <Lamination process>

[0067] 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.

[0068] <Bonding process>

[0069] 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.

[0070] The irradiation conditions for electron beam irradiation 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 to 300kV, and more preferably 10kV to 250kV. When the acceleration voltage is less than 5kV, there is a risk that the electron beam cannot reach the adhesive 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. The irradiation dose is 5 to 100kGy, and more preferably 10 to 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.

[0071] 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, an oxygen shield can be actively generated in the polarizer and the resin protective film that are first irradiated with the electron beam, thereby preventing damage to the polarizer and the resin protective film, thereby allowing the electron beam to be efficiently irradiated only to the molecular binder.

[0072] 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 nitrene. The nitrene 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 free radical addition or free 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, more preferably 20% or more.

[0073] 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, and 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 optical 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.

[0074] 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, thereby having excellent weather resistance, heat resistance, etc.

[0075] 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 surface and back 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.

[0076] For the exposed surface of the adhesive layer, a separator is temporarily bonded to cover it until it is actually used for the purpose of preventing contamination. 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 used as required with a suitable release agent such as silicone, long-chain alkyl, fluorine, molybdenum sulfide, etc., and the like, and the like, which is coated with a suitable thin layer such as a plastic film, a rubber sheet, paper, a cloth, a non-woven fabric, a net, a foam sheet, a metal foil, or a laminate thereof, etc., as previously specified.

[0077] 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.

[0078] 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.

[0079] Example

[0080] Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

[0081] <Polarizing filter>

[0082] 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 (polarizer thickness 5 μm) including a 5 μm thick PVA layer (thin polarizer) constituting an iodine-based thin polarizer 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.

[0083] <Resin protective film>

[0084] Cyclic olefin polymer (COP); trade name "Zeonor Film ZF14", manufactured by Zeonor Co., Ltd.

[0085] Polycarbonate polymers (PC)

[0086] First, a polyester carbonate resin is produced, and then film-formed to produce a resin protective film.

[0087] (Polymerization of polyester carbonate resins)

[0088] 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, and 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 reaction product was extruded into water to obtain polycarbonate resin pellets.

[0089] (Production of resin protective film)

[0090] 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., barrel 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.

[0091] <Active energy rays>

[0092] A UV-LED irradiation device manufactured by Quark Technology was used to irradiate with UV light (265 nm, 100 mJ / cm 2 ) was irradiated.

[0093] <Molecular binding agent>

[0094] ·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

[0095] 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

[0096] (Manufacturing of Polarizing Film)

[0097] Example 1

[0098] 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 on 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 10 nm.

[0099] Comparative Example 1

[0100] 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 10 nm.

[0101] The polarizing films produced in Example 1 and Comparative Example 1 were evaluated as follows.

[0102] (Measurement of the thickness of the molecular bonding layer and the adhesive layer)

[0103] The thickness of the molecular bonding 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.

[0104] (Method for confirming the formation of a compatible layer in a molecular bonding layer)

[0105] The formation of a compatible layer in the molecular bonding layer was confirmed by TOF-SIMS depth profile measurement. The specific method is described below.

[0106] <TOF-SIMS measurement equipment>

[0107] The polarizing film composed of three layers (polarizer / molecular bonding layer / resin protective film) was cut into about 1 cm square and fixed on a dedicated sample stand. TOF-SIMS measurement was performed using TRIFT-V manufactured by ULVAC-PHI. The etching ions used were Ar gas cluster ions (Ar n + ), with an etching ion acceleration voltage of 20 kV and an etching area of ​​400 μm square, the etching proceeded from the polarizer side to the resin protective film side. The primary ion used for irradiation was Bi3 2+ (primary ion acceleration voltage 30kV), measured a 100μm square area, observed the fragment ions of each material component, and made a depth profile. Specifically, the "C2N3 - 、m / z=66” ion、“C4H - 、m / z=49” ions and “C2H3O2 - , m / z=59” ion depth profile.

[0108] The peak intensity of each component depth profile obtained by TOF-SIMS measurement was converted to 100% to produce an analytical depth profile. In the analytical depth profile, the area containing each component with a peak intensity of 20% or more was regarded as the existence area. - , m / z=66” ions start to increase from the polarizer side toward the protective film side and the position where the peak intensity reaches 20% is set as “A”, and the “C2N3 - , m / z=66” The position where the ions begin to decrease and the peak intensity reaches 20% is set as “B”, and the “distance between AB” is set as the thickness of the molecular bonding layer. According to the TEM image, it was confirmed that the thickness of the molecular bonding layer was 10nm, so the “distance between AB” was set to 10nm. In the “distance between AB”, the peak intensity was more than 20% and the overlap of the ion peaks from the resin protective film was the largest. The ratio of the above-mentioned overlapping distance to the “distance between AB”, i.e. 10nm, was calculated as the thickness of the compatible layer.

[0109] (Heating and humidification test (transmittance change test))

[0110] 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 respectively used as Ts, Tp, and Tc of the polarizing film. These Ts, Tp, and Tc are 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 in a high temperature and high humidity environment is suppressed.

[0111] [Table 1]

[0112]

[0113] According to the results in Table 1, in the polarizing film of Example 1, a compatibility layer is formed on the side of the resin protective film in the molecular bonding layer with a thickness greater than 50% relative to the thickness of the molecular bonding layer. Therefore, even under high temperature and high humidity conditions, the swelling of the polarizer can be suppressed, thereby suppressing the iodine leakage of the polarizer, and as a result, the reduction in polarization degree is fully suppressed.

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 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, A compatibility layer formed by compatibility between the molecular bonding layer and the resin protective film is formed on the resin protective film side of the molecular bonding layer, and the compatibility layer is formed to have a thickness of 50 to 90% of the thickness of the molecular bonding layer.

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 the general formula (1), 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 to 0.200 μm. 6 . An optical film comprising at least one polarizing film according to claim 1 laminated thereon. 7 . An image display device using the polarizing film according to claim 1 or the optical film according to claim 6 .

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