TWI850515B - Manufacturing method of polarizing film - Google Patents

Abstract

The object of the present invention is to provide a method for continuously and stably manufacturing a polarizing film, wherein the polarizing element and the transparent protective film of the polarizing film have excellent adhesion to the adhesive layer and the generation of bubbles is suppressed. The manufacturing method of the polarizing film of the present invention is characterized in that it comprises the following steps: a first coating step, which is to coat the bonding surface of the polarizing element with a bonding composition containing water and a hydrophilic monomer while conveying the polarizing element, so as to form a wet first coating film; a second coating step, which is to coat the bonding surface of the transparent protective film with a bonding agent composition containing a free radical polymerizable compound and a cationic polymerizable compound while conveying the transparent protective film, so as to form a second coating film; a first thickness measuring step, which is to measure the thickness of the wet first coating film online; The drying step is to use a dryer to remove water from the wet first coating to form a dry first coating after the first thickness measuring step; the second thickness measuring step is to measure the thickness of the dry first coating online after the drying step; the dryness adjustment step is to adjust the temperature and/or air volume of the dryer so that the ratio of the thickness of the wet first coating obtained by the online measurement to the thickness of the dry first coating satisfies the following formula (A), thereby adjusting the dryness of the newly formed dry first coating. (Thickness of the dry first coating/Thickness of the wet first coating)-(Content rate of water in the easily bonded composition)≦0.05(A)

Description

Manufacturing method of polarizing film

The present invention relates to a method for manufacturing a polarizing film, wherein the polarizing film is provided with a transparent protective film on at least one side of a polarizing element through an adhesive layer. The polarizing film can be used alone or in the form of an optical film formed by laminating the polarizing film to form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, a PDP, etc.

The market for LCD devices is expanding rapidly in clocks, mobile phones, PDAs, laptops, computer monitors, DVD players, and TVs. LCD devices visualize polarization states by switching liquid crystals, and polarizers are used based on their display principles. In particular, in TV applications, high brightness, high contrast, and wide viewing angles are increasingly sought, and thus polarizing films are increasingly sought for high transmittance, high polarization, and high color reproducibility.

As a polarizer, iodine-based polarizers, which have a structure in which polyvinyl alcohol (hereinafter referred to as "PVA") absorbs iodine and stretches, are the most commonly used due to their high transmittance and high polarization degree. Generally speaking, polarizing films are made by bonding transparent protective films on both sides of the polarizer using a so-called water-based adhesive, which is made by dissolving polyvinyl alcohol-based materials in water (Patent Document 1 below). The transparent protective film uses cellulose triacetate with high moisture permeability. When using the aforementioned water-based adhesive (so-called wet lamination), a drying step is required after bonding the polarizer and the transparent protective film.

On the other hand, an active energy ray-curable adhesive has been proposed to replace the aforementioned water-based adhesive. When the active energy ray-curable adhesive is used to manufacture polarizing films, the productivity of the polarizing films can be improved because a drying step is not required.

For example, Patent Document 2 proposes an active energy ray-curable adhesive composition that can be easily and sufficiently bonded to a polyvinyl alcohol-based film and a plastic film; the active energy ray-curable adhesive composition contains (A) a (meth) acrylic free radical polymerizable compound, (B) a cationic polymerizable compound, (C) a photo-free radical polymerization initiator, and (D) a photo-cationic polymerization initiator. Prior Art Documents Patent Documents

Patent document 1: Japanese Patent Publication No. 2001-296427 Patent document 2: Japanese Patent Publication No. 5046721

Problems to be solved by the invention In recent years, in the field of optical films such as polarizing films, displays have been continuously thinned and refined, requiring more stringent appearance quality. In this situation, a countermeasure is needed to suppress the generation of bubbles when the polarizer and the protective film are bonded using an adhesive. As a countermeasure to suppress the generation of bubbles, it is effective to increase the coating thickness of the adhesive or reduce the viscosity of the adhesive. However, if the coating thickness of the adhesive is increased, there will be a problem of fading after humidification, and the low viscosity of the adhesive will increase the restrictions on meeting optical properties or adhesion.

In addition, as a means of reducing the viscosity of the adhesive, it is effective to mix water, which is a non-hazardous substance, into the adhesive. However, in the case of a cationic polymerization type adhesive as described in Patent Document 2, water has the problem of hindering the cationic polymerization reaction.

The present invention is to solve the above-mentioned problem, and its purpose is to provide a method for continuously and stably manufacturing a polarizing film, wherein the polarizing element and the transparent protective film of the polarizing film have excellent adhesion to the adhesive layer, and the generation of bubbles is suppressed.

Means to solve the problem The above problem can be solved by the following structure.

That is, the present invention is related to a method for manufacturing a polarizing film, wherein the polarizing film is provided with a transparent protective film through an adhesive layer on at least one side of the polarizing element. The manufacturing method is characterized in that it includes the following steps: The first coating step is to apply an easily bondable composition containing water and a hydrophilic monomer to the bonding surface of the polarizing element while conveying the polarizing element, thereby forming a wet first coating film; The second coating step is to convey the polarizing element while conveying the A bonding agent composition containing a free radical polymerizable compound and a cationic polymerizable compound is applied to the bonding surface of the transparent protective film to form a second coating; The first thickness measurement step is to measure the thickness of the wet first coating online; The drying step is to use a dryer to remove the water in the wet first coating after the first thickness measurement step to form a dry first coating; The second thickness measurement step is to measure the thickness of the wet first coating online ... The step of adjusting the degree of dryness is to adjust the temperature and/or air volume of the dryer so that the ratio of the thickness of the wet first coating obtained by the online measurement to the thickness of the dry first coating satisfies the following formula (A), thereby adjusting the degree of dryness of the newly formed dry first coating; The step of bonding is to bond the bonding formed on the polarizer. The aforementioned dry first coating on the bonding surface and the aforementioned second coating formed on the bonding surface of the aforementioned transparent protective film form an uncured adhesive layer; and The next step is to cure the aforementioned uncured adhesive layer to obtain the aforementioned adhesive layer, so that the aforementioned polarizer and the aforementioned transparent protective film are bonded; (Thickness of the dry first coating/Thickness of the wet first coating)-(Content ratio of water in the easy-bonding composition) ≦0.05(A).

In the method for producing the polarizing film, the aforementioned easy-to-bond composition preferably contains a compound represented by the following general formula (1) and/or an organic metal compound having an MO bond (M is silicon, titanium, aluminum or zirconium, and O is an oxygen atom) in the structural formula; [Chemical Formula 1] (However, X is a functional group containing a reactive group, and ^R1 and ^R2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group or a heterocyclic group.) In addition, in the present invention, the compound represented by the above general formula (1) is also referred to as a "boron-containing compound".

In the above-mentioned method for manufacturing a polarizing film, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (1'): [Chemical Formula 2] (However, Y is an organic group, and X, ^R1 and ^R2 are the same as described above).

In the above-mentioned method for manufacturing a polarizing film, the reactive group possessed by the compound represented by the above-mentioned general formula (1) is preferably at least one reactive group selected from the group consisting of an α,β-unsaturated carbonyl group, a vinyl group, a vinyl ether group, an epoxy group, an oxycyclobutane group, an amino group, an aldehyde group, a butyl group and a halogen group.

In the above-mentioned method for manufacturing the polarizing film, the moisture content of the above-mentioned polarizer is preferably less than 15% by mass.

In the method for manufacturing the polarizing film, the first coating step and the second coating step are preferably coating steps using a post-metering coating method.

In the method for manufacturing the polarizing film, the post-metering coating method is preferably a gravure roller coating method using a gravure roller.

Effect of the invention The manufacturing method of the polarizing film of the present invention is characterized in that water is mixed into the easy-adhesive composition to be applied to the bonding surface of the polarizer to suppress the generation of bubbles by lowering the viscosity, and on the other hand, the adhesive composition to be applied to the bonding surface of the transparent protective film contains a free radical polymerizable compound and a cationic polymerizable compound in order to improve the adhesion.

In the continuous production of polarizing film, when water remains in the first coating obtained by applying the aforementioned easy-bonding composition on the bonding surface of the polarizer, water will remain in the uncured adhesive layer obtained by bonding the first coating and the second coating obtained by applying the aforementioned adhesive composition. As a result, the undesirable situation that the cationic polymerization reaction of the uncured adhesive layer is hindered will occur, resulting in reduced adhesion of the adhesive layer. Therefore, the water in the first coating must be removed in the drying step. In the drying step, the initial set temperature and set air volume of the dryer are determined according to the amount of water mixed in the bondable composition. We believe that by the drying conditions set at the beginning, the water in the first coating film will be sufficiently removed to a level that does not hinder the cationic polymerization reaction.

However, due to various factors such as deterioration and damage of the drying equipment piping, blockage of the blow-off port, and temperature changes in the surrounding environment, the drying degree of the first coating layer may vary during the continuous production of polarizing film, and the water in the first coating layer may not be fully removed, and water may remain in the first coating layer after the drying step. Therefore, as described above, the cationic polymerization reaction of the uncured adhesive layer may be hindered by the remaining water, making it difficult to stably form an adhesive layer with uniform adhesive properties, and it may be difficult to continuously and stably manufacture polarizing films with excellent adhesive properties.

According to the manufacturing method of the polarizing film of the present invention, the temperature and/or air volume of the dryer are adjusted so that the ratio of the thickness of the wet first coating film measured online to the thickness of the dry first coating film satisfies the above formula (A), thereby adjusting the degree of dryness of the newly formed dry first coating film, thereby continuously and stably forming a dry first coating film with a small variation in the degree of dryness and from which water has been fully removed. Therefore, the undesirable situation that the cationic polymerization reaction of the uncured adhesive layer is hindered by the residual water can be prevented, and an adhesive layer with uniform adhesive properties can be continuously and stably formed.

As described above, the manufacturing method of the polarizing film of the present invention can continuously and stably manufacture a polarizing film with high appearance quality. The polarizing element and transparent protective film of the polarizing film have excellent adhesion to the adhesive layer, and the generation of bubbles is suppressed.

The aforementioned easy-to-bond composition preferably contains the aforementioned boron-containing compound. The aforementioned boron-containing compound can react with functional groups such as hydroxyl groups possessed by the polarizer. Thereby, the adhesion between the polarizer and the adhesive layer can be improved, and as a result, the effect of improving the water-resistant adhesion of the polarizing film can be exerted. Here, when the moisture content of the polarizer is low, for example, when the moisture content of the polarizer is below 15% by mass, there is a situation where the boron-containing compound and the functional groups possessed by the polarizer cannot fully react and the above-mentioned effect cannot be fully obtained. However, even in the case where the moisture content of the polarizer is low, because the easy-to-bond composition contains water, the reactivity of the boron-containing compound to the functional groups possessed by the polarizer will be improved, thereby improving the adhesion between the polarizer and the adhesive layer. As a result, even when the moisture content of the polarizer is low, the water-resistant adhesion of the polarizing film can be improved, the coating property of the easy-to-adhere composition can be improved, and the generation of bubbles in the polarizing film can be suppressed.

The aforementioned easy-to-bond composition preferably contains the aforementioned organic metal compound. The aforementioned organic metal compound will become an active metal species due to the inclusion of water, and as a result, the organic metal compound will form a strong bond with the polarizer. However, the aforementioned organic metal compound has a plurality of reaction points, so the organic metal compound after reacting with the polarizer still has unreacted points. And the aforementioned organic metal compound can form a strong bond with the curable component in the second coating formed on the bonding surface of the transparent protective film. As mentioned above, the aforementioned organic metal compound can form a strong bond with both the polarizer and the adhesive layer, so the water-resistant adhesion between the polarizer and the adhesive layer will be dramatically improved.

The aforementioned first coating step and the aforementioned second coating step are preferably coating steps using a post-metering coating method. Thereby, the adhesion of the polarizing film can be improved, and at the same time, the coating property when applying the easy-to-bond composition and the adhesive composition can be improved, and the thickness uniformity of the first coating film and the second coating film can be improved. In addition, the "post-metering coating method" in the present invention refers to a method of applying external force to the liquid film to remove excess liquid to obtain a predetermined coating film thickness. Specific examples of the post-metering coating method include a gravure roller coating method, a forward roll coating method, an air knife coating method, a rod/bar coating method, and the like.

The present invention is a method for manufacturing a polarizing film, wherein the polarizing film is provided with a transparent protective film through an adhesive layer on at least one side of the polarizing element. The manufacturing method comprises the following steps: The first coating step is to apply an easily bondable composition containing water and a hydrophilic monomer to the bonding surface of the polarizing element while conveying the polarizing element, thereby forming a wet first coating film; The second coating step is to apply a While conveying the transparent protective film, an adhesive composition containing a free radical polymerizable compound and a cationic polymerizable compound is applied to the bonding surface of the transparent protective film to form a second coating; The first thickness measurement step is to measure the thickness of the wet first coating online; The drying step is to use a dryer to remove water from the wet first coating after the first thickness measurement step. To form a dry first coating; The second thickness measurement step is to measure the thickness of the dry first coating online after the drying step; The dryness adjustment step is to adjust the temperature and/or air volume of the dryer so that the ratio of the thickness of the wet first coating obtained by the online measurement to the thickness of the dry first coating satisfies the following formula (A), thereby adjusting the newly formed The dryness of the dry first coating; The laminating step is to laminate the dry first coating formed on the laminating surface of the polarizer and the second coating formed on the laminating surface of the transparent protective film to form an uncured adhesive layer; and The bonding step is to bond the polarizer and the transparent protective film by hardening the uncured adhesive layer to obtain the aforementioned adhesive layer. (Thickness of the dry first coating/Thickness of the wet first coating)-(Content of water in the easily bondable composition) ≦0.05(A)

The following is a detailed description of the method for manufacturing the polarizing film of the present invention.

<Highly adhesive composition> The highly adhesive composition contains at least water and a hydrophilic monomer.

The hydrophilic monomer is not particularly limited as long as it is soluble in water, and examples thereof include: carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, liconic acid, monobutyl hydroxyfumarate and monobutyl hydroxyicarbanoate, and salts thereof; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, and polyethylene glycol mono(meth)acrylate, etc. Hydroxyl-containing monomers; acrylamide monomers such as (meth)acrylamide, diacetone acrylamide and N-hydroxymethyl (meth)acrylamide; heterocyclic (meth)acrylamide derivatives such as N-acryloyl fomafrine, N-acryloyl piperidine, N-methacryloyl piperidine and N-acryloyl pyrrolidine; ester compounds at both ends of ethylene glycol oligomers such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate; ester compounds at both ends of propylene glycol oligomers, etc. These may be used alone or in combination of two or more. Among these, hydroxyl-containing monomers are preferably used.

The content of the hydrophilic monomer in the adhesive composition is not particularly limited, but is preferably 20% by mass or more, more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 65% by mass or less, from the viewpoint of improving adhesiveness.

The easily bondable composition may contain, as a curable component, a polymerizable compound X having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less.

The polymerizable compound X can be used without limitation as long as it has a free radical polymerizable group such as a (meth)acrylate group and has an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less. Examples of the polymerizable compound X include N-methoxymethylacrylamide (SP value 22.9) and N-ethoxymethylacrylamide (SP value 22.3). In addition, commercially available products can be used as appropriate for the polymerizable compound X, such as WASMER 2MA (manufactured by Kasano Kosan Co., Ltd., SP value 22.9), WASMER EMA (manufactured by Kasano Kosan Co., Ltd., SP value 22.3), and WASMER 3MA (manufactured by Kasano Kosan Co., Ltd., SP value 22.4). One of these may be used, or two or more of them may be used in combination.

Here, the calculation method of the SP value (solubility parameter) of the present invention is described below.

(Calculation method of solubility parameter (SP value)) In the present invention, the solubility parameter (SP value) of the polymerizable compound X can be calculated by the Fedors calculation method [refer to "Polymer Engineering and Science (Polymer Eng. &Sci.)", Vol. 14, No. 2 (1974), pp. 148-154], that is: [Mathematical formula 1] (However, Δei is derived from the vaporization energy of an atom or group at 25°C, and Δvi is the molar volume at 25°C).

In the above mathematical formula, Δei and Δvi represent fixed values assigned to i atoms and groups in the main molecule. Representative examples of the values of Δe and Δv assigned to atoms or groups are shown in Table 1 below.

[Table 1]

The content of the polymerizable compound X in the easily bondable composition is not particularly limited, but is preferably 0.5 mass % or less.

Furthermore, the bonding composition preferably contains a compound represented by the following general formula (1): [Chemical Formula 3] (However, X is a functional group containing a reactive group, and ^R1 and ^R2 independently represent a hydrogen atom, an aliphatic alkyl group which may have a substituent, an aryl group, or a heterocyclic group.) Examples of the aliphatic alkyl group include a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a cyclic alkyl group having 3 to 20 carbon atoms which may have a substituent, and an alkenyl group having 2 to 20 carbon atoms; examples of the aryl group include a phenyl group having 6 to 20 carbon atoms which may have a substituent, a naphthyl group having 10 to 20 carbon atoms which may have a substituent, and the like; examples of the heterocyclic group include, for example, a 5-membered or 6-membered ring group containing at least one heteroatom and which may have a substituent. These may be linked to each other to form a ring. In the general formula (1), ^R1 and ^R2 are preferably hydrogen atoms or linear or branched alkyl groups having 1 to 3 carbon atoms, and hydrogen atoms are the most preferred. In addition, the compound represented by the general formula (1) may be present in an unreacted state in the finally formed adhesive layer, or may be present in a state where each functional group has reacted.

In the compound represented by the general formula (1), X is a functional group containing a reactive group and capable of reacting with the curing component constituting the adhesive layer. The reactive group contained in X may be, for example, a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxycyclobutane group, an α,β-unsaturated carbonyl group, a hydroxyl group, a halogen group, and the like. When the adhesive composition constituting the adhesive layer is active energy ray-curable, the reactive group contained in X is preferably at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, oxacyclobutane and alkyl. In particular, the adhesive composition of the present invention constituting the adhesive layer is free radical polymerizable, so the reactive group contained in X is preferably at least one reactive group selected from the group consisting of (meth)acryl, styryl and (meth)acrylamide. When the compound represented by the general formula (1) has a (meth)acrylamide group, it is preferred because the reactivity is high and the copolymerization rate with the active energy ray adhesive composition can be increased. In addition, the (meth)acrylamide group has high polarity and excellent adhesion, so the effect of the present invention can be efficiently obtained, and it is also suitable from this point of view. In addition, the adhesive composition of the present invention constituting the adhesive layer is cationic polymerizable, so the reactive group contained in X preferably has at least one functional group selected from hydroxyl, amino, aldehyde, carboxyl, vinyl ether, epoxy, cyclohexane, and alkyl. In particular, when it has an epoxy group, it is more preferable because the adhesive layer obtained has excellent adhesion to the adherend; when it has a vinyl ether group, it is more preferable because the adhesive composition has excellent curing properties.

Preferred specific examples of the compound represented by the general formula (1) include the compound represented by the following general formula (1'): [Chemical Formula 4] (Y is an organic group, and X, ^R1 and ^R2 are the same as above.) More preferably, the following compounds (1a) to (1d) are mentioned.

[Chemical formula 5]

In the present invention, the compound represented by the general formula (1) may be one in which the reactive group is directly bonded to the boron atom. As shown in the above specific examples, the compound represented by the general formula (1) is preferably one in which the reactive group is bonded to the boron atom via an organic group, that is, a compound represented by the general formula (1'). When the compound represented by the general formula (1) is, for example, one that is bonded to the reactive group via an oxygen atom bonded to the boron atom, the water-resistant adhesion of the polarizing film tends to deteriorate. On the other hand, when the compound represented by the general formula (1) is not one having a boron-oxygen bond, but one having a boron-carbon bond through the boron atom and an organic group and containing a reactive group (represented by the general formula (1')), it is more preferred because the water-resistant adhesion of the polarizing film can be improved. The aforementioned organic group specifically refers to an organic group having 1 to 20 carbon atoms which may have a substituent, and more specifically includes a linear or branched alkylene group having 1 to 20 carbon atoms which may have a substituent, a cyclic alkylene group having 3 to 20 carbon atoms which may have a substituent, a phenylene group having 6 to 20 carbon atoms which may have a substituent, and a naphthylene group having 10 to 20 carbon atoms which may have a substituent.

Examples of the compound represented by the general formula (1) include, in addition to the compounds exemplified above, esters of (meth)acrylates and boric acid, such as esters of hydroxyethylacrylamide and boric acid, esters of hydroxymethylacrylamide and boric acid, esters of hydroxyethylacrylate and boric acid, and esters of hydroxybutylacrylate and boric acid.

If the content of the compound represented by the general formula (1) in the adhesive composition is too low, the ratio of the compound represented by the general formula (1) existing at the interface between the polarizer and the adhesive layer will decrease, and the adhesive effect may be reduced. Therefore, in the adhesive composition, the content of the compound represented by the general formula (1) is preferably 0.01 mass % or more, preferably 0.05 mass % or more, more preferably 0.1 mass % or more, and particularly preferably 0.5 mass % or more. In addition, in the adhesive composition, the content of the compound represented by the general formula (1) is usually 5 mass % or less, preferably 3 mass % or less, and more preferably 2 mass % or less.

Furthermore, the easily bondable composition preferably contains an organic metal compound having an M-O bond (M is silicon, titanium, aluminum or zirconium, and O is an oxygen atom) in the structural formula. In addition, the aforementioned organic metal compound may exist in an unreacted state in the finally formed bonding agent layer, or may exist in a state where each functional group has reacted.

The aforementioned organic metal compound has an M-O bond in the structural formula (M is silicon, titanium, aluminum or zirconium, and O is an oxygen atom). The aforementioned organic metal is preferably at least one selected from the group consisting of organic silicon compounds, metal alkoxides and metal chelates.

The aforementioned organic silicon compound can be used without particular limitation and can be any one having a Si-O bond, and specific examples include active energy ray-curable organic silicon compounds and non-active energy ray-curable organic silicon compounds. In particular, it is preferred that the carbon number of the organic group of the organic silicon compound is 3 or more. Specific examples of the active energy ray-curable compound include vinyl trichlorosilane, vinyl trimethoxysilane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, p-phenylene trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, and 3-acryloxypropyl trimethoxysilane.

Preferred are 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane.

As the non-active energy ray-hardening compound, a compound having an amine group is preferred. Specific examples of the compound having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropyltriisopropoxysilane, γ-(2-(2-aminoethyl)aminoethyl)aminopropyltrimethoxysilane, γ-(6-aminohexyl)aminopropyltrimethoxysilane, 3-(N-ethylamino)- Amine-containing silanes such as 2-methylpropyltrimethoxysilane, γ-ureapropyltrimethoxysilane, γ-ureapropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-benzyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl)aminomethyltrimethoxysilane, and N,N’-bis[3-(trimethoxysilyl)propyl]ethylenediamine; ketimine-type silanes such as N-(1,3-dimethylbutylene)-3-(triethoxysilyl)-1-propylamine.

The compound having an amino group may be used alone or in combination. Among them, γ-aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiethoxysilane, and N-(1,3-dimethylbutylene)-3-(triethoxysilyl)-1-propylamine are preferred in order to ensure good adhesion.

Specific examples of the non-active energy ray-curable compounds other than the above include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-butylmethyldimethoxysilane, 3-butyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxysilane, imidazole silane, etc.

The aforementioned metal alkoxide is a compound in which at least one alkoxy group belonging to an organic group is bonded to a metal, and the metal chelate is a compound in which an organic group is bonded or coordinated to a metal via an oxygen atom. The metal is preferably titanium, aluminum, or zirconium. Among them, aluminum and zirconium are more reactive than titanium, but the service life of the adhesive composition is shortened and the effect of improving water-resistant adhesiveness is reduced. Therefore, from the perspective of improving the water-resistant adhesiveness of the adhesive layer, the metal of the organic metal compound is preferably titanium.

When the adhesive composition contains a metal alkoxide as the organic metal compound, the metal alkoxide preferably has an organic group with 3 or more carbon atoms, and more preferably 6 or more carbon atoms. If the carbon atoms are less than 2, the useful life of the adhesive composition may be shortened and the effect of improving water-resistant adhesiveness may be reduced. An organic group with 6 or more carbon atoms, such as octyloxy, can be used appropriately. Suitable metal alkoxides include, for example, tetraisopropyl titanium, tetra-n-butyl titanium, butyl titanium dimer, tetraoctyl titanium, tri-pentyl titanium, tetra-tert-butyl titanium, tetrastearyl titanium, tetraisopropoxyzirconia, tetra-n-butyl oxide, tetraoctyl zirconium oxide, tetra-tert-butyl oxide, tetrapropoxyzirconia, di-butyl aluminum, aluminum ethoxide, aluminum isopropoxide, aluminum butoxide, aluminum mono-di-butyl diisopropoxide, aluminum mono-di-butoxy diisopropoxide, etc. Among them, tetraoctyl titanium is preferred.

When the easily adhesive composition contains a metal chelate as an organic metal compound, it is preferred that the carbon number of the organic group contained in the metal chelate is 3 or more. If the carbon number is less than 2, the service life of the easily adhesive composition will be shortened and the effect of improving the water-resistant adhesiveness of the polarizing film will be reduced. Examples of the organic group having a carbon number of 3 or more include acetylacetonate, acetylacetate, isostearate, and caprylate. Among them, from the perspective of improving the water-resistant adhesiveness of the adhesive layer, the organic group is preferably acetylacetonate or acetylacetate. Suitable metal chelates include, for example, titanium acetylacetonate, titanium octanediolate, titanium tetraacetylacetonate, titanium ethyl acetylacetonate, titanium polyhydroxystearate, dipropoxybis(acetylacetonate), dibutoxybis(octanediolate), dipropoxybis(ethyl acetylacetonate), titanium lactate, diethanolamine titanium, triethanolamine titanium, dipropoxybis(lactic acid), dipropoxybis(triethanolamine), titanium bis(lactic acid), titanium ... ethanolamine) titanium, di-n-butoxybis(triethanolamine) titanium, tri-n-butoxy monostearate titanium, diisopropoxybis(ethyl acetate) titanium, diisopropoxybis(ethyl acetate) titanium, diisopropoxybis(acetylacetone) titanium, titanium phosphate compounds, ammonium lactate, 1,3-propanedioxybis(ethyl acetate) titanium, dodecylbenzenesulfonate titanium compounds, aminoethylamine Titanium ethoxide, Zirconium tetraacetylacetonate, Zirconium monoacetylacetonate, Zirconium diacetylacetonate, Zirconium acetylacetonate bis(ethyl acetylacetate), Zirconium acetate, Zirconium tri-n-butoxy(ethyl acetylacetate), Zirconium di-n-butoxybis(ethyl acetylacetate), Zirconium n-butoxytris(ethyl acetylacetate), Zirconium tetra(n-propyl acetylacetate), Zirconium tetra(ethyl acetylacetate), Zirconium tetra(ethyl acetylacetate) , (ethyl acetylacetate)aluminum, acetylacetonate aluminum, acetylacetonate bis(ethyl acetylacetate)aluminum, diisopropoxy(ethyl acetylacetate)aluminum, diisopropoxy(ethyl acetylacetate)aluminum, isopropoxybis(ethyl acetylacetate)aluminum, isopropoxybis(ethyl acetylacetate)aluminum, 3-(ethyl acetylacetate)aluminum, 3-(ethyl acetylacetate)aluminum, monoacetylacetonate bis(ethyl acetylacetate)aluminum. Among them, titanium acetylacetonate and titanium ethyl acetylacetate are preferred.

In addition to the above, the organic metal compounds that can be used in the present invention include organic metal carbonates such as zinc octanoate, zinc laurate, zinc stearate, and tin octanoate, and zinc chelate compounds such as acetylacetonate tin chelate, benzylacetonate zinc chelate, diphenylmethane zinc chelate, and ethyl acetylacetonate zinc chelate.

If the content of the organic metal compound in the adhesive composition is too low, the ratio of the organic metal compound present at the interface between the polarizer and the adhesive layer will decrease, and the adhesive effect may be reduced. Therefore, the content of the organic metal compound in the adhesive composition is preferably 0.01 mass % or more, preferably 0.05 mass % or more, and more preferably 0.1 mass % or more. In addition, the content of the organic metal compound in the adhesive composition is usually 10 mass % or less.

The easily bondable composition contains water as a solvent. An organic solvent may be mixed into the easily bondable composition within the scope that does not impair the effect of the present invention, but it is preferred not to mix the organic solvent.

The adhesive composition may also contain additives.

The aforementioned additives include, for example, adhesive resins, surfactants, plasticizers, tackifiers, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, preservatives, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, titanium ester coupling agents, inorganic or organic fillers, metal powders, granules, foils, etc.

<Adhesive composition> The adhesive composition of the present invention can be either thermosetting or active energy ray-curable. The resin constituting the thermosetting adhesive composition can be polyvinyl alcohol resin, epoxy resin, unsaturated polyester, urethane resin, acrylic resin, urea resin, melamine resin, phenol resin, etc., and can be used together with a hardener as needed. The resin constituting the thermosetting adhesive composition can more preferably be polyvinyl alcohol resin or epoxy resin. Active energy ray-curable adhesive compositions can be classified according to active energy rays and can be roughly divided into electron beam curing, ultraviolet curing, and visible light curing. In addition, the curing reaction is used to classify and distinguish free radical polymerizable adhesive compositions from cationic polymerizable adhesive compositions, and in the present invention, free radical polymerizable and cationic polymerizable adhesive compositions are used. In addition, in the present invention, active energy rays with a wavelength range of 10nm and less than 380nm are marked as ultraviolet rays, and active energy rays with a wavelength range of 380nm to 800nm are marked as visible rays.

In the method for manufacturing the polarizing film of the present invention, the adhesive composition is preferably active energy ray-curable, and is particularly preferably visible light-curable using visible light of 380nm to 450nm.

The adhesive composition of the present invention contains at least a free radical polymerizable compound and a cationic polymerizable compound.

Examples of free radical polymerizable compounds include compounds having free radical polymerizable functional groups with carbon-carbon double bonds such as (meth)acryloyl and vinyl. Any of monofunctional free radical polymerizable compounds or polyfunctional free radical polymerizable compounds having two or more functional groups can be used. Moreover, these free radical polymerizable compounds can be used alone or in combination of two or more. These free radical polymerizable compounds are preferably compounds having (meth)acryloyl. In addition, in the present invention, the so-called (meth)acryloyl refers to acryl and/or methacryloyl, and hereinafter "(meth)" is synonymous.

The monofunctional free radical polymerizable compound may be exemplified by the compound represented by the following general formula (2): [Chemical Formula 6] (However, R ³ is a hydrogen atom or a methyl group, R ⁴ and R ⁵ are independently a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, and R ⁴ and R ⁵ may also form a cyclic heterocycle.) The number of carbon atoms in the alkyl group, the hydroxyalkyl group and/or the alkoxyalkyl group is not particularly limited, and examples thereof include 1 to 4. In addition, examples of the cyclic heterocycle that may be formed by R ⁴ and R ⁵ include N-acryloyl isofrain, etc.

Specific examples of the compound represented by the general formula (2) include (meth)acrylamide derivatives containing an N-alkyl group such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; (meth)acrylamide derivatives containing an N-hydroxyalkyl group such as N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-hydroxymethyl-N-propane(meth)acrylamide; and (meth)acrylamide derivatives containing an N-alkoxy group such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide. In addition, the (meth)acrylamide derivative containing a cyclic ether group includes a (meth)acrylamide derivative containing a heterocyclic ring formed by the nitrogen atom of the (meth)acrylamide group, and examples thereof include N-acryloyl fophrine, N-acryloyl piperidine, N-methylacryloyl piperidine, and N-acryloyl pyrrolidine.

Furthermore, the adhesive composition may contain a monofunctional radical polymerizable compound other than the above as a curable component. Examples of the monofunctional radical polymerizable compound include various (meth)acrylic acid derivatives having a (meth)acryloyl group. Examples of the (meth)acrylic acid derivatives include alkyl (meth)acrylates (having a carbon number of 1 to 20) such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, tertiary butyl (meth)acrylate, n-pentyl (meth)acrylate, tertiary pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate.

Examples of the (meth)acrylic acid derivatives include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aryl (meth)acrylates such as benzyl (meth)acrylate; 2-isoborneol (meth)acrylate, 2-norbornenyl methyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornenyl methyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and 1,2-diisobornenyl (meth)acrylate. Polycyclic (meth)acrylates such as dicyclopentenyloxyethyl acrylate and dicyclopentyl (meth)acrylate; (meth)acrylate-2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxy polyethylene glycol (meth)acrylate and other alkoxy- or phenoxy-containing (meth)acrylates, etc. Among them, dicyclopentenyloxyethyl acrylate and phenoxyethyl acrylate are preferred because of their good adhesion to various protective films.

Examples of the (meth)acrylic acid derivatives include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and the like. esters; or hydroxyl-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; epoxy-containing (meth)acrylates such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethyl ethyl (meth)acrylate Halogen-containing (meth)acrylates such as tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; 3-oxacyclobutane methyl (meth)acrylate, 3-methyl-oxacyclobutane methyl (meth)acrylate, and 3-hydroxy-2-hydroxypropyl (meth)acrylate; (meth)acrylates containing oxygen-containing cyclobutyl groups such as 3-ethoxycyclobutyl (meth)acrylate, 3-butyloxycyclobutyl (meth)acrylate, 3-hexyloxycyclobutyl (meth)acrylate, etc.; (meth)acrylates containing heterocyclic groups such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; or hydroxytrimethylacetic acid neopentyl glycol (meth)acrylate adduct, p-phenylphenol (meth)acrylate, etc. Among them, 2-hydroxy-3-phenoxypropyl acrylate is preferred because of its excellent adhesion to various protective films.

Examples of the monofunctional free radical polymerizable compound include carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and ω-carboxy-polycaprolactone mono(meth)acrylate.

In addition, monofunctional free radical polymerizable compounds include, for example, vinyl monomers of the lactamide type such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinyl monomers having nitrogen-containing heterocyclic rings such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperidone, vinylpyrrolidone, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylfenofolin; and the like.

If the adhesive composition of the present invention contains a highly polar hydroxyl-containing (meth)acrylate, carboxyl-containing (meth)acrylate or phosphoric acid-containing (meth)acrylate among monofunctional free radical polymerizable compounds, the adhesion to various substrates will be improved. The content of hydroxyl-containing (meth)acrylate is preferably 1% by mass to 30% by mass relative to the adhesive composition. When the content of hydroxyl-containing (meth)acrylate is too high, the water absorption rate of the cured product will increase and the water resistance will deteriorate. The content of carboxyl-containing (meth)acrylate is preferably 1% by mass to 20% by mass relative to the adhesive composition. When the content of carboxyl-containing (meth)acrylate is too high, the optical durability of the polarizing film will decrease, so it is not good. The phosphoric acid group-containing (meth)acrylate may be exemplified by 2-(meth)acryloyloxyethyl acid phosphate; its content is preferably 0.1 mass % to 10 mass % relative to the adhesive composition. When the content of the phosphoric acid group-containing (meth)acrylate is too high, the optical durability of the polarizing film is reduced, so it is not good.

In addition, the monofunctional free radical polymerizable compound may be a free radical polymerizable compound having an active methylene group. The free radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acryl group at the end or in the molecule and having an active methylene group. Examples of the active methylene group include acetoacetyl group, alkoxypropanoyl group, or cyanoacetyl group. The aforementioned active methylene group is preferably acetoacetyl group. Examples of free radical polymerizable compounds having an active methylene group include acetoacetoxyalkyl (meth)acrylates such as 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl (meth)acrylate; 2-ethoxypropanoyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, and N-(2-acetoacetylaminoethyl)acrylamide. The free radical polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth)acrylate.

Examples of the polyfunctional free radical polymerizable compound having two or more functional groups include N,N'-methylenebis(meth)acrylamide, which is a polyfunctional (meth)acrylamide derivative, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropylene glycol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A bicyclopentane diacrylate, and bisphenol A dicyclopentane diacrylate. Esterification products of (meth)acrylic acid and polyols such as 1,2-dioxypropyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, cyclotrihydroxymethylpropane formal (meth)acrylate, dialkylene glycol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, neopentylethol tri(meth)acrylate, neopentylethol tetra(meth)acrylate, dipentylethol penta(meth)acrylate, dipentylethol hexa(meth)acrylate, EO-modified diglycerol tetra(meth)acrylate, and 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include ARONIX M-220 (manufactured by Toagosei Co., Ltd.), LIGHT-ACRYLATE 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), LIGHT-ACRYLATE DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), LIGHT-ACRYLATE DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer Co., Ltd.), CD-536 (manufactured by Sartomer Co., Ltd.), etc. In addition, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, or various (meth)acrylate monomers may be used as needed. In addition, multifunctional (meth)acrylamide derivatives have excellent productivity due to their fast polymerization speed, and are excellent in crosslinking when the adhesive composition is made into a cured product, so they are preferably contained in the adhesive composition.

From the perspective of both adhesion to polarizers or various transparent protective films, as well as optical durability in harsh environments, it is better to use a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound together as a radical polymerizable compound. In addition, the liquid viscosity of a monofunctional radical polymerizable compound is relatively low, so by including it in the adhesive composition, the liquid viscosity of the adhesive composition can be reduced. In addition, most monofunctional radical polymerizable compounds have functional groups that can exhibit various functions, and by including it in the adhesive composition, the adhesive composition and/or the cured product of the adhesive composition can exhibit various functions. Polyfunctional radical polymerizable compounds can cause the cured product of the adhesive composition to produce three-dimensional crosslinking, so it is advisable to include them in the adhesive composition. The polyfunctional radical polymerizable compound is preferably used in an amount of 10 to 1000 parts by mass based on 100 parts by mass of the monofunctional radical polymerizable compound.

From the viewpoint of improving the adhesion of the adhesive layer, the content of the free radical polymerizable compound in the adhesive composition is preferably 55-80% by mass, more preferably 65-80% by mass, and even more preferably 67-75% by mass.

When electron beams or the like are used as active energy rays, the adhesive composition does not necessarily need to contain a photoradical polymerization initiator. However, when ultraviolet rays or visible rays are used as active energy rays, the adhesive composition preferably contains a photoradical polymerization initiator.

The photoradical polymerization initiator can be appropriately selected according to the active energy rays. When curing by ultraviolet rays or visible rays, a photoradical polymerization initiator that cracks by ultraviolet rays or visible rays is used. Examples of the photoradical polymerization initiator include diphenyl ketone compounds such as benzil, diphenyl ketone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxydiphenyl ketone; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α-hydroxycyclohexylphenyl ketone; methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2- Acetophenone compounds such as diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-oxofolinylpropane-1, etc.; benzoin alkyl ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisole methyl ether, etc.; aromatic ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; optically active oxime compounds such as 1-benzophenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; 9-oxysulfuronium , 2-chloro-9-oxysulfuron , 2-methyl 9-oxosulfuron , 2,4-dimethyl 9-oxosulfuron , isopropyl-9-oxysulfide , 2,4-dichloro-9-oxysulfuron , 2,4-diethyl 9-oxysulfide 、2,4-Diisopropyl 9-oxysulfide 、Dodecyl 9-oxysulfide 9-Oxosulfuron Series compounds; camphorquinone; halogenated ketone; acyl phosphine oxide; acyl phosphonate, etc.

The content of the photo-radical polymerization initiator in the adhesive composition is preferably 20% by mass or less, preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and particularly preferably 0.1 to 5% by mass.

When the adhesive composition of the present invention is used for visible light curing containing a free radical polymerizable compound as a curing component, it is particularly suitable to use a photo radical polymerization initiator with high sensitivity to light above 380nm. The photo radical polymerization initiator with high sensitivity to light above 380nm will be described later.

The photo-radical polymerization initiator is preferably a compound represented by the following general formula (3) alone, or a compound represented by the general formula (3) and a photo-radical polymerization initiator having high sensitivity to light of 380 nm or above described below; [Chemical Formula 7] (In the formula, ^R6 and ^R7 represent -H, _-CH2CH3 , _-iPr or Cl, and ^R6 and ^R7 may be the same or different.) Compared with the case of using a photo-radical polymerization initiator having high sensitivity to light above 380nm alone, the bonding property is better when the compound represented by general formula (3) is used. Among the compounds represented by general formula (3), diethyl 9- _sulfuronium with ^R6 and ^R7 being _-CH2CH3 The composition ratio of the compound represented by the general formula (3) in the connecter composition is preferably 0.1-5 mass %, more preferably 0.5-4 mass %, and even more preferably 0.9-3 mass % relative to the total amount of the connecter composition.

Furthermore, a polymerization initiation aid may be added as needed. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., and ethyl 4-dimethylaminobenzoate is particularly preferred. When a polymerization initiation aid is used, its addition amount relative to the total amount of the adhesive composition is generally 0-5% by mass, preferably 0-4% by mass, and most preferably 0-3% by mass.

In addition, a known photo-radical polymerization initiator can be used as needed. The transparent protective film with UV absorption ability will not transmit light below 380nm, so the photo-radical polymerization initiator is preferably a photo-radical polymerization initiator with high sensitivity to light above 380nm. Specifically, for example, 2-methyl-1-(4-methylthiophenyl)-2-oxothiopropane-1-one, 2-benzyl-2-dimethylamino-1-(4-oxothiophenyl)-butan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-oxothio)phenyl]-1-butanone, 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, and the like can be cited.

In particular, the photoradical polymerization initiator is preferably a compound represented by the following general formula (4) in addition to the photoradical polymerization initiator represented by the general formula (3): [Chemical formula 8] (In the formula, R ⁸ , R ⁹ and R ¹⁰ represent -H, -CH ₃ , -CH ₂ CH ₃ , -iPr or Cl, and R ⁸ , R ⁹ and R ¹⁰ may be the same or different.) As the compound represented by the general formula (4), 2-methyl-1-(4-methylthiophenyl)-2-oxoformylpropan-1-one (trade name: IRGACURE907, manufacturer: BASF), which is also a commercial product, can be suitably used. In addition, 2-benzyl-2-dimethylamino-1-(4-oxoformylphenyl)-butan-1-one (trade name: IRGACURE369, manufacturer: BASF) and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-oxoformyl)phenyl]-1-butanone (trade name: IRGACURE379, manufacturer: BASF) are preferred because of their high sensitivity.

In the above-mentioned adhesive composition, when a radical polymerizable compound having an active methylene group is used as the radical polymerizable compound, it is preferably used in combination with a radical polymerization initiator having a hydrogen abstracting effect. With the above-mentioned composition, the adhesiveness of the adhesive layer of the polarizing film will be significantly improved, especially even just after being taken out of a high humidity environment or water (non-dry state). The reason is not clearly understood, but it can be inferred as follows. That is, the radical polymerizable compound having an active methylene group will polymerize with other radical polymerizable compounds constituting the adhesive layer, while being incorporated into the main chain and/or side chain of the base polymer in the adhesive layer to form the adhesive layer. In the aforementioned polymerization process, once there is a free radical polymerization initiator with hydrogen abstraction, it will form a base polymer constituting the adhesive layer while abstracting hydrogen from the free radical polymerizable compound with active methylene groups to generate free radicals in the methylene groups. Then, the methylene groups that have generated free radicals will react with the hydroxyl groups of polarizers such as PVA to form a covalent bond between the adhesive layer and the polarizer. As a result, it can be inferred that the adhesive layer of the polarizing film will have significantly improved adhesion even in a non-dry state.

In the present invention, the free radical polymerization initiator having a hydrogen abstracting function may be, for example, 9-sulfuryl The free radical polymerization initiator is 9-oxysulfide. It is preferably a free radical polymerization initiator. is a free radical polymerization initiator, and examples thereof include the compound represented by the above general formula (3). Specific examples of the compound represented by the general formula (3) include 9-oxysulfuron Series, dimethyl 9-oxysulfide Series, diethyl 9-oxysulfide 、Isopropyl 9-oxysulfide Series, 9-chlorosulfuron Among the compounds represented by the general formula (3), R ⁶ and R ⁷ are -CH ₂ CH ₃ diethyl 9-sulfuron Especially good.

Cationic polymerizable compounds are classified into monofunctional cationic polymerizable compounds having one cationic polymerizable functional group in the molecule and polyfunctional cationic polymerizable compounds having two or more cationic polymerizable functional groups in the molecule.

The liquid viscosity of monofunctional cationic polymerizable compounds is relatively low, so by including them in the adhesive composition, the liquid viscosity of the adhesive composition can be reduced. In addition, most monofunctional cationic polymerizable compounds have functional groups that can exhibit various functions, and by including them in the adhesive composition, the adhesive composition and/or the cured product of the adhesive composition can exhibit various functions.

The multifunctional cationic polymerizable compound can cause three-dimensional cross-linking of the cured product of the adhesive composition.

Examples of the cationically polymerizable functional group include an epoxy group, an oxycyclobutane group, and a vinyl ether group.

Examples of the compound having an epoxy group include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. From the viewpoint of excellent curability or adhesion, alicyclic epoxy compounds are preferred.

Examples of the alicyclic epoxy compound include 3,4-epoxyepoxyhexylmethyl-3,4-epoxyepoxyhexanecarboxylate, caprolactone-modified products, trimethylcaprolactone-modified products, and valerolactone-modified products of 3,4-epoxyepoxyhexylmethyl-3,4-epoxyepoxyhexanecarboxylate. Specific examples include CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, and CELLOXIDE 2085 (all manufactured by DAICEL Chemical Industries, Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, and R-6110 (all manufactured by DOW CHEMICAL Japan Co., Ltd.).

Examples of the compound having an oxadiazole group include 3-ethyl-3-hydroxymethyloxadiazole, 1,4-bis[(3-ethyl-3-oxadiazole)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxadiazole, di[(3-ethyl-3-oxadiazole)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxadiazole, and phenol novolacoxadiazole. Specific examples include ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211, ARON OXETANE OXT-221, and ARON OXETANE OXT-212 (all manufactured by Toagosei Co., Ltd.).

Examples of the compound having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol tetravinyl ether, and the like.

From the viewpoint of improving the adhesiveness of the adhesive layer, the content of the cationic polymerizable compound in the adhesive composition is preferably 5-40% by mass, more preferably 10-30% by mass, and even more preferably 15-25% by mass.

The adhesive composition of the present invention contains a cationic polymerizable compound as a curing component, and therefore preferably contains a photo-cationic polymerization initiator. The photo-cationic polymerization initiator generates cationic species or Lewis acid by irradiation with active energy rays such as visible light, ultraviolet light, X-rays, and electron beams, and initiates polymerization of epoxy groups or oxycyclobutane groups. The photo-cationic polymerization initiator can use a photoacid generator and a photoalkali generator, and the photoacid generator described below is preferably used. Furthermore, when the adhesive composition used in the present invention is used for visible light curing, it is preferable to use a photocationic polymerization initiator that is particularly highly sensitive to light of 380 nm or longer. However, photocationic polymerization initiators are generally compounds that show maximum absorption in the vicinity of 300 nm or in a wavelength region shorter than that. Therefore, by mixing a photosensitizer that shows maximum absorption in a longer wavelength region, specifically, light with a wavelength longer than 380 nm, the photocationic polymerization initiator can be responsive to light of the vicinity of the wavelength, thereby promoting the generation of cationic species or acid from the photocationic polymerization initiator. As photosensitizers, for example, anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds and photoreduction pigments can be mentioned, and two or more of them can also be used in combination. Anthracene compounds are particularly ideal because of their excellent photosensitization effect, and specifically, ANTHRACURE UVS-1331 and ANTHRACURE UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.) can be mentioned. The content of the photosensitizer is preferably 0.1% to 5% by mass, and more preferably 0.5% to 3% by mass.

The photoacid generator may be, for example, a compound represented by the following general formula (5). General formula (5) [Chemical formula 9] (However, L ⁺ represents _an arbitrary onium cation; and ^X- represents a relative anion selected from the group consisting of _PF6- ^, _SbF6- ^, _AsF6- , ^{SbCl6- ,} _BiCl5- ^, _SnCl6- ^, _ClO4- ^, dithiocarbamate anions, and SCN-).

Next, the relative anion X ^- in the general formula (5) is described.

In principle, the relative anion ^X- in the general formula (5) is not particularly limited, but is preferably a non-nucleophilic anion. When the relative anion ^X- is a non-nucleophilic anion, it is difficult to cause the cations coexisting in the molecule or the various materials used in combination to undergo nucleophilic reactions, thereby improving the long-term stability of the photoacid generator represented by the general formula (5) itself or the composition using the same. The non-nucleophilic anion here refers to an anion with a low ability to initiate a nucleophilic reaction. Examples of the anion include PF ₆ ^- , SbF ₆ ^- , AsF ₆ ^- , SbCl ₆ ^- , BiCl ₅ ^- , SnCl ₆ ^- , ClO ₄ ^- , dithiocarbamate anions, and SCN ^- .

Preferred specific examples of the photoacid generator of the present invention include "Cyracure-UVI-6992", "Cyracure-UVI-6974" (all manufactured by DOW CHEMICAL Japan Co., Ltd.), "ADEKA OPTOMER SP150", "ADEKA OPTOMER SP152", "ADEKA OPTOMER SP170", "ADEKA OPTOMER SP172" (all manufactured by ADEKA Co., Ltd.), "IRGACURE 250" (manufactured by Ciba Specialty Chemicals Co., Ltd.), "CI-5102", "CI-2855" (all manufactured by Nippon Soda Co., Ltd.), "SANEIDO SI-60L", "SANEIDO SI-80L", "SANEIDO SI-100L", "SANEIDO SI-110L", "SANEIDO SI-180L" (all manufactured by Sanshin Chemical Co., Ltd.), "CPI-100P", "CPI-110P", "CPI-100A" (all manufactured by San-Apro Co., Ltd.), "WPI-069", "WPI-113", "WPI-116", "WPI-041", "WPI-044", "WPI-054", "WPI-055", "WPAG-281", "WPAG-567", "WPAG-596" (all manufactured by Wako Junyaku Co., Ltd.).

The content of the photoacid generator is less than 10% by mass relative to the total amount of the adhesive composition, and is preferably 0.01-10% by mass, more preferably 0.05-5% by mass, and particularly preferably 0.1-3% by mass.

A photoalkali generator is a compound that can change its molecular structure or cleave the molecules by irradiation with light such as ultraviolet light or visible light, and function as a catalyst for the polymerization reaction of free radical polymerizable compounds or epoxy resins to generate one or more alkaline substances. Examples of alkaline substances include secondary amines and tertiary amines. Examples of photoalkali generators include the above-mentioned α-aminoacetophenone compounds, the above-mentioned oxime ester compounds, or compounds having substituents such as acyloxyimino groups, N-formylated aromatic amine groups, N-acylated aromatic amine groups, nitrobenzylcarbamate groups, and alkoxybenzylcarbamate groups. Among them, oxime ester compounds are preferred.

Examples of the compound having an acyloxyimino group include O,O'-succinic acid dibenzoyl oxime, O,O'-succinic acid dinaphthylacetonoxime, and benzophenone oxime acrylate-styrene copolymer.

Examples of the compound having an N-formylated aromatic amine group or an N-acylated aromatic amine group include di-N-(p-formylamino)diphenylmethane, di-N-(p-acetylamino)diphenylmethane, di-N-(p-benzylamino)diphenylmethane, 4-formylaminostilbene, 4-acetylaminostilbene, 2,4-diformylaminostilbene, Olefins, 1-formamidonaphthalene, 1-acetamidonaphthalene, 1,5-diformamidonaphthalene, 1-formamidoanthracene, 1,4-diformamidoanthracene, 1-acetamidoanthracene, 1,4-diformamidoanthraquinone, 1,5-diformamidoanthraquinone, 3,3'-dimethyl-4,4'-diformamidobiphenyl, 4,4'-diformamidodiphenyl ketone.

Examples of the compound having a nitrobenzylcarbamate group or an alkoxybenzylcarbamate group include bis{{(2-nitrobenzyl)oxy}carbonyl}diaminodiphenylmethane, 2,4-bis{(2-nitrobenzyl)oxy}stilbene, bis{(2-nitrobenzyloxy)carbonyl}hexane-1,6-diamine and interrupted amine{{(2-nitro-4-chlorobenzyl)oxy}amide}.

The photobase generator is preferably at least one of an oxime ester compound and an α-aminoacetophenone compound, and is preferably an oxime ester compound. The α-aminoacetophenone compound preferably has two or more nitrogen atoms.

Other photoalkali generators that can be used include WPBG-018 (trade name: 9-anthrylmethyl N,N’-diethylcarbamate), WPBG-027 (trade name: (E)-1-[3-(2-hydroxyphenyl)-2-propenoyl]piperidine), WPBG-082 (trade name: guanidinium2-(3-benzoylphenyl)propionate), and WPBG-140 (trade name: 1-(anthraquinon-2-yl)ethyl imidazolecarboxylate).

The above-mentioned adhesive composition may contain a photoacid generator and a compound containing either an alkoxy group or an epoxide group in the adhesive composition.

When using a compound having one or more epoxy groups in the molecule or a polymer (epoxy resin) having two or more epoxy groups in the molecule, a compound having two or more functional groups reactive with epoxy groups in the molecule may also be used in combination. The functional groups reactive with epoxy groups herein include, for example, carboxyl groups, phenolic hydroxyl groups, hydroxyl groups, primary or secondary aromatic amine groups, etc. In consideration of three-dimensional curability, it is particularly preferred to have two or more of these functional groups in one molecule.

Examples of polymers having one or more epoxy groups in the molecule include epoxy resins, and there are bisphenol A type epoxy resins derived from bisphenol A and epichlorohydrin, bisphenol F type epoxy resins derived from bisphenol F and epichlorohydrin, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, bisphenol F novolac type epoxy resins, aliphatic epoxy resins, Diphenyl ether epoxy resin, hydroquinone epoxy resin, naphthalene epoxy resin, biphenyl epoxy resin, fluorene epoxy resin, trifunctional epoxy resin or tetrafunctional epoxy resin and other multifunctional epoxy resins, glycidyl ester epoxy resin, glycidyl amine epoxy resin, hydantoin epoxy resin, isocyanate epoxy resin, aliphatic chain epoxy resin, etc. These epoxy resins may be halogenated or hydrogenated. Commercially available epoxy resin products include JERCoat manufactured by Japan Epoxy Resins Co., Ltd. 828, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000; Epiclon830, EXA835LV, HP4032D, HP820 manufactured by DIC Corporation; EP4100 series, EP4000 series, EPU series manufactured by ADEKA Corporation; DAICEL Chemical CELLOXIDE series (2021, 2021P, 2083, 2085, 3000, etc.), EPOLEAD series, EHPE series manufactured by Nippon Steel Chemical Co., Ltd.; YD series, YDF series, YDCN series, YDB series, phenoxy resin (polyhydroxy polyether synthesized from bisphenols and epichlorohydrin and having epoxy groups at both ends; YP series, etc.) manufactured by NAGASE CHEMTEX; DENACOL series manufactured by NAGASE CHEMTEX; Epolite series manufactured by Kyoeisha Chemical Co., Ltd., etc., but not limited to the above. Two or more of these epoxy resins may be used in combination.

The compound having an alkoxy group in the molecule is not particularly limited as long as it has one or more alkoxy groups in the molecule, and known compounds can be used. Representative examples of such compounds include melamine compounds, amino resins, and silane coupling agents.

The amount of the compound containing either an alkoxy group or an epoxy group is usually less than 30% by mass relative to the total amount of the adhesive composition. If the content of the compound in the composition is too much, the adhesiveness will be reduced, and the impact resistance in the drop test will deteriorate. The content of the compound in the composition is preferably less than 20% by mass. On the other hand, from the perspective of water resistance, the composition should contain more than 2% by mass of the compound, and preferably more than 5% by mass.

The adhesive composition used in the present invention preferably contains the aforementioned polymerizable compound X as a curing component. The SP value of the aforementioned polymerizable compound X is close to the SP value of the transparent protective film such as unsaponified cellulose triacetate film and acrylic film, so the aforementioned polymerizable compound X helps to improve the adhesion between the adhesive layer and the transparent protective film.

The content of the aforementioned polymerizable compound X in the adhesive composition is not particularly limited, but from the viewpoint of improving the adhesion between the adhesive layer and the transparent protective film, it is preferably 80% by mass or less, more preferably 60% by mass or less, and preferably 25% by mass or more, more preferably 35% by mass or more.

In the present invention, the compound described in the general formula (1), preferably the compound described in the general formula (1'), and more preferably the compound described in the general formula (1a) to (1d) can be mixed into the adhesive composition. In addition, in the present invention, the organic metal compound can be mixed into the adhesive composition. When these compounds are mixed into the adhesive composition, the adhesion with the polarizer or the transparent protective film can be improved, so it is preferred. From the perspective of improving the adhesion and water resistance when the polarizer and the transparent protective film are bonded through the adhesive layer, the content of the compound described in the general formula (1) in the adhesive composition is preferably 0.001~50 mass%, preferably 0.1~30 mass%, and more preferably 1~10 mass%. In the adhesive composition, the content of the organometallic compound is preferably 0.1-10% by mass, more preferably 0.5-7% by mass, and even more preferably 1-5% by mass.

Bubble suppressors are compounds that can reduce the surface tension of adhesive compositions by being mixed into the adhesive composition, thereby having the effect of reducing bubbles between the adhesive composition and the transparent protective film. Bubble suppressors can be those that can reduce the surface tension of adhesive compositions when added into the adhesive composition, for example: polysiloxane-based bubble suppressors with a polysiloxane skeleton such as polydimethylsiloxane, (meth)acrylic-based bubble suppressors with a (meth)acrylic skeleton formed by polymerization of (meth)acrylates, polyether-based bubble suppressors formed by polymerization of vinyl ethers or cyclic ethers, fluorine-based bubble suppressors composed of fluorine-based compounds with perfluoroalkyl groups, etc.

The bubble suppressant preferably has a reactive group in the compound. In this case, the occurrence of stacked bubbles can be reduced when the polarizer and the transparent protective film are bonded. The reactive group possessed by the bubble suppressant may be a polymerizable functional group, specifically, for example: free radical polymerizable functional groups having ethylene double bonds such as (meth)acryl, vinyl, and allyl; cation polymerizable functional groups such as epoxy groups such as glyoxypropyl, cyclohexane, vinyl ether, cyclic ether, cyclic sulfide, and lactone. From the perspective of reactivity in the adhesive composition, a bubble suppressant having a double bond as a reactive group is preferred, and a bubble suppressant having a (meth)acryl group is more preferred.

Considering the effects of suppressing lamination bubbles and improving adhesion, polysilicone-based bubble suppressors are preferred among the bubble suppressors. In addition, among bubble suppressors, considering the adhesion of the adhesive layer, those containing urethane bonds or isocyanurate ring structures in the main chain skeleton or side chain are preferred. Commercially available polysilicone-based bubble suppressors can also be appropriately used, such as "BYK-UV3505" (manufactured by BYK Japan), which is acryl-modified polydimethylsiloxane.

In order to take into account both the adhesion of the adhesive layer and the effect of reducing accumulated bubbles, the content of the bubble inhibitor is preferably 0.01~0.6 mass % when the total amount of the adhesive composition is set to 100 mass %.

The adhesive composition used in the present invention may contain, in addition to the curing component of the aforementioned free radical polymerizable compound, an acrylic oligomer formed by polymerization of (meth)acrylic acid monomers. By containing the acrylic oligomer in the adhesive composition, the curing shrinkage can be reduced when the composition is irradiated with active energy rays to cure it, and the interfacial stress between the adhesive and the adherends such as polarizers and transparent protective films can be reduced. As a result, the reduction in the adhesion between the adhesive layer and the adherend can be suppressed. In order to fully suppress the curing shrinkage of the adhesive layer, the content of the acrylic oligomer is preferably 20% by mass or less, and more preferably 15% by mass or less relative to the total amount of the adhesive composition. If the content of acrylic acid oligomer in the adhesive composition is too high, the reaction rate will decrease rapidly after the composition is irradiated with active energy rays, resulting in poor curing. On the other hand, the acrylic acid oligomer is preferably contained in an amount of 3% by mass or more relative to the total amount of the adhesive composition, and more preferably 5% by mass or more.

Considering the workability and uniformity during application, the adhesive composition preferably has a low viscosity, so the acrylic oligomer obtained by polymerizing (meth)acrylic acid monomers also preferably has a low viscosity. As an acrylic oligomer with low viscosity that can prevent the adhesive layer from hardening and shrinking, the weight average molecular weight (Mw) of the acrylic oligomer is preferably 15,000 or less, preferably 10,000 or less, and particularly preferably 5,000 or less. On the other hand, in order to fully inhibit the hardening and shrinking of the adhesive layer, the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, preferably 1000 or more, and particularly preferably 1500 or more. The (meth)acrylic acid monomer constituting the acrylic oligomer may be specifically exemplified by methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, S-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, tert-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, and n-hexyl (meth)acrylate. , cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, N-octadecyl (meth)acrylate and other (meth)acrylic acid (carbon number 1-20) alkyl esters; and cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isoborneol (meth)acrylate, 2-norborneol (meth)acrylate, etc.), methyl (meth)acrylate, 5-norbornyl-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornyl methyl (meth)acrylate, etc.), hydroxyl-containing (meth)acrylates (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy- or phenoxy-containing (meth)acrylates (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethylcarbenicillate, etc.), alkylaminoalkyl (meth)acrylate (for example, dimethylaminoethyl (meth)acrylate). These (meth)acrylates may be used alone or in combination of two or more. Specific examples of acrylic oligomers include "ARUFON" manufactured by Toagosei Co., Ltd., "ACTFLOW" manufactured by Soken Chemical Co., Ltd., and "JONCRYL" manufactured by BASF JAPAN.

When the adhesive composition used in the present invention is active energy ray-curable, it is preferable to use an active energy ray-curable compound as the silane coupling agent. However, even if it is not active energy ray-curable, the same water resistance can be imparted.

Specific examples of the silane coupling agent include active energy ray-curable compounds such as vinyl trichlorosilane, vinyl trimethoxysilane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, p-phenylenediyl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, and 3-acryloxypropyl trimethoxysilane.

Preferred are 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane.

As specific examples of non-active energy ray-curable silane coupling agents, silane coupling agents having an amino group are preferred. Specific examples of silane coupling agents having an amino group include: γ-aminopropyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-aminopropyl triisopropoxysilane, γ-aminopropyl methyl dimethoxysilane, γ-aminopropyl methyl diethoxysilane, γ-(2-aminoethyl)aminopropyl trimethoxysilane, γ-(2-aminoethyl)aminopropyl methyl dimethoxysilane, Silane, γ-(2-aminoethyl)aminopropyl triethoxysilane, γ-(2-aminoethyl)aminopropyl methyldiethoxysilane, γ-(2-aminoethyl)aminopropyl triisopropoxysilane, γ-(2-(2-aminoethyl)aminoethyl)aminopropyl trimethoxysilane, γ-(6-aminohexyl)aminopropyl trimethoxysilane, 3-(N-ethylamino) -2-methylpropyltrimethoxysilane, γ-ureapropyltrimethoxysilane, γ-ureapropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-benzyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl)aminomethyltrimethoxysilane, N,N'-bis[3-(trimethoxysilyl)propyl]ethylenediamine and other amine-containing silanes; N-(1,3-dimethylbutylene)-3-(triethoxysilyl)-1-propylamine and other ketimine-type silanes.

The silane coupling agent having an amino group may be used alone or in combination. Among them, γ-aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiethoxysilane, and N-(1,3-dimethylbutylene)-3-(triethoxysilyl)-1-propaneamine are preferred in order to ensure good adhesion.

The mixing amount of the silane coupling agent is preferably in the range of 0.01-20 mass % relative to the total amount of the adhesive composition, preferably 0.05-15 mass %, and more preferably 0.1-10 mass %. When the mixing amount is greater than 20 mass %, the storage stability of the adhesive composition will deteriorate, and when it is less than 0.1 mass %, the effect of water-resistant adhesion cannot be fully exerted.

Specific examples of non-active energy ray-curable silane coupling agents other than the above include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-butylmethyldimethoxysilane, 3-butyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxysilane, imidazole silane, etc.

When the adhesive composition used in the present invention contains a compound having a vinyl ether group, the water-resistant adhesion between the polarizer and the adhesive layer will be improved, which is very ideal. Although the reason for obtaining this effect is still unclear, it can be inferred that one of the reasons is that the vinyl ether group of the compound interacts with the polarizer, thereby improving the adhesion between the polarizer and the adhesive layer. In order to further improve the water-resistant adhesion between the polarizer and the adhesive layer, the compound is preferably a free radical polymerizable compound having a vinyl ether group. In addition, the content of the compound is preferably 0.1 to 19 mass % relative to the total amount of the adhesive composition.

The adhesive composition used in the present invention may contain a compound that can produce keto-enol tautomerism. For example, in an adhesive composition containing a crosslinking agent or in an adhesive composition mixed with a crosslinking agent, a state containing the above-mentioned compound that can produce keto-enol tautomerism may be appropriately adopted. In this way, the excessive increase in viscosity or gelation of the adhesive composition after the organic metal compound is mixed, as well as the formation of microgels, can be suppressed, and the effect of extending the service life of the composition can be achieved.

As the compound capable of producing keto-enol tautomerism, various β-dicarbonyl compounds can be used. Specific examples include β-diketones such as acetylacetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2,4-dione, and 2,6-dimethylheptane-3,5-dione; acetylacetic acid esters such as methyl acetylacetate, ethyl acetylacetate, isopropyl acetylacetate, and tertiary butyl acetylacetate; acetylacetic acid esters such as ethyl propionyl acetate, ethyl propionyl acetate, isopropyl acetylacetate, and tertiary butyl propionyl acetate; isobutyryl acetate esters such as ethyl isobutyryl acetate, ethyl isobutyryl acetate, isopropyl isobutyryl acetate, and tertiary butyl isobutyryl acetate; malonic acid esters such as methyl malonate and ethyl malonate, and the like. Suitable compounds include acetylacetone and acetylacetate. The compounds that can produce keto-enol tautomerism can be used alone or in combination of two or more.

The amount of the compound that can produce keto-enol tautomerism is set to, for example, 0.05 to 10 parts by mass, preferably 0.2 to 3 parts by mass (e.g., 0.3 to 2 parts by mass) relative to 1 part by mass of the organic metal compound. If the amount of the compound used is less than 0.05 parts by mass relative to 1 part by mass of the organic metal compound, it may be difficult to fully exert the effect of use. On the other hand, if the amount of the compound used is greater than 10 parts by mass relative to 1 part by mass of the organic metal compound, there is an excessive interaction with the organic metal compound, and it is difficult to exhibit the desired water resistance.

The adhesive composition of the present invention may contain a polyrotaxane. The polyrotaxane has a cyclic molecule, a linear molecule penetrating the opening of the cyclic molecule, and a capping group, wherein the capping group is arranged at both ends of the linear molecule in such a manner that the cyclic molecule does not detach from the linear molecule. The cyclic molecule preferably has a functional group that is hardenable by active energy rays.

The cyclic molecule is not particularly limited as long as it has a linear molecule encapsulated in a thorn-like manner at its opening, can move on the linear molecule, and has an active energy line polymerizable group. In addition, in this specification, the "cyclic" in "cyclic molecule" means substantially "cyclic". That is, as long as it can move on the linear molecule, the cyclic molecule may not be a completely closed ring.

Specific examples of cyclic molecules include cyclic polymers such as cyclic polyethers, cyclic polyesters, cyclic polyetheramines, and cyclic polyamines; and cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. Among them, cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are preferred from the viewpoint of being easier to obtain and being able to select a variety of end groups. Two or more cyclic molecules may be mixed in the polyrotaxane or the linker.

In the polyrotaxane used in the present invention, the above-mentioned cyclic molecule has an active energy ray polymerizable group. Thus, even after the polyrotaxane reacts with the active energy ray curable component and is cured, a bonding agent with a movable crosslinking point can be obtained. The active energy ray polymerizable group of the cyclic molecule can be any group that can polymerize with the above-mentioned active energy ray curable compound, and examples thereof include free radical polymerizable groups such as (meth)acryloyl and (meth)acryloyloxy groups.

When cyclodextrin is used as the cyclic molecule, the active energy ray polymerizable group is preferably a hydroxyl group introduced into the cyclodextrin via any appropriate linker. The number of active energy ray polymerizable groups in one molecule of the polyrotaxane is preferably 2 to 1280, preferably 50 to 1000, and more preferably 90 to 900.

It is preferable to introduce a hydrophobic modifying group into the cyclic molecule. By introducing a hydrophobic modifying group, the compatibility with the active energy line curing component can be improved. Moreover, since the hydrophobicity is imparted, water can be prevented from penetrating into the interface between the adhesive layer and the polarizer when used in a polarizing film, and the water resistance can be further improved. Examples of the hydrophobic modifying group include polyester chains, polyamide chains, alkyl chains, oxyalkyl chains, ether chains, etc. Specific examples include the groups described in [0027] to [0042] of WO2009/145073.

Polarizing films that use a resin composition containing polyrotaxane as an adhesive have excellent water resistance. The reason for the improved water resistance of polarizing films is still unclear, but we speculate as follows. That is, we believe that the mobility of the cyclic molecules of polyrotaxane makes the cross-linking points movable (the so-called pulley effect), thereby imparting flexibility to the hardened adhesive and increasing its adhesion to the uneven surface of the polarizer, thereby preventing water from invading the interface between the polarizer and the adhesive layer. We also believe that the fact that polyrotaxane has a hydrophobic modification group and can impart hydrophobicity to the adhesive also helps prevent water from invading the interface between the polarizer and the adhesive layer. The content of polyrotaxane should be 2% by mass to 50% by mass relative to the resin composition.

<Polarizer> In the present invention, from the perspective of improving optical durability in a harsh environment of high temperature and high humidity, a thin polarizer with a thickness of 3µm or more and 15µm or less is preferably used as a polarizer, preferably 12µm or less, more preferably 10µm or less, and particularly preferably 8µm or less. Such a thin polarizer has less thickness variation, better visibility, and less dimensional change, so it has excellent durability against thermal shock.

In addition, thin polarizers generally have low moisture content, specifically, in most cases, the moisture content is below 15 mass%. Although the thin polarizer with low moisture content has the aforementioned effects, on the other hand, it has low reactivity with the boron-containing compound or organometallic compound contained in the easy-bonding composition used in the present invention, and there are cases where the effect of improving the adhesion between the polarizer and the adhesive layer is insufficient. Therefore, in the manufacturing method of the polarizing film of the present invention, when a polarizer with a moisture content of 15 mass% or less is used, when the total amount of the easy-bonding composition is set to 100 mass%, the water content is preferably 5~90 mass%, preferably 30~80 mass%, and more preferably 40~70 mass%.

The polarizer is made of polyvinyl alcohol resin. Examples of the polarizer include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified films of ethylene-vinyl acetate copolymers, which are made by absorbing dichroic materials such as iodine or dichroic dyes and then uniaxially stretching them, and polyene oriented films such as dehydrated polyvinyl alcohol or dehydrogenated polyvinyl chloride. Among these, the polarizer composed of polyvinyl alcohol films and dichroic materials such as iodine is preferred.

The polarizer of the polyvinyl alcohol film dyed with iodine and stretched uniaxially can be made by, for example, immersing the polyvinyl alcohol in an iodine aqueous solution for dyeing and stretching it to 3 to 7 times the original length. It can also be immersed in an aqueous solution that can also contain boric acid or potassium iodide such as zinc sulfate and zinc chloride as needed. The polyvinyl alcohol film can also be immersed in water for washing before dyeing as needed. By washing the polyvinyl alcohol film with water, the dirt and anti-adhesive on the surface of the polyvinyl alcohol film can be washed away. In addition, by swelling the polyvinyl alcohol film, it can also prevent uneven dyeing, etc. Stretching can be carried out after dyeing with iodine, or it can be dyed and stretched at the same time, or it can be dyed with iodine after stretching. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

From the perspective of extension stability and humidification reliability, the polarizer preferably contains boric acid. Furthermore, from the perspective of suppressing the generation of through cracks, the content of boric acid in the polarizer is preferably 22% by mass or less, more preferably 20% by mass or less, relative to the total amount of the polarizer. From the perspective of extension stability and humidification reliability, the content of boric acid is preferably 10% by mass or more, more preferably 12% by mass or more, relative to the total amount of the polarizer.

Representative examples of thin polarizers include: Japanese Patent No. 4751486 Specification, Japanese Patent No. 4751481 Specification, Japanese Patent No. 4815544 Specification, Japanese Patent No. 5048120 Specification, International Publication No. 2014/077599 Manual, International Publication No. 2014/077636 Manual, etc., or thin polarizers produced by the manufacturing methods described therein.

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 at a high rate to improve the polarization performance, the aforementioned thin polarizer is preferably obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in the specification of Japanese Patent No. 4751486, the specification of Japanese Patent No. 4751481, and the specification of Japanese Patent No. 4815544, and is particularly preferably obtained by a manufacturing method including a step of auxiliary air stretching before stretching in an aqueous boric acid solution as described in the specification of Japanese Patent No. 4751481 and the specification of Japanese Patent No. 4815544. The thin polarizers can be produced by a method comprising the steps of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA resin) layer and a stretching resin substrate in a laminated state and dyeing. With this method, even if the PVA resin layer is very thin, it can be stretched without causing defects such as breakage due to stretching because it is supported by the stretching resin substrate.

<Transparent protective film> The transparent protective film should preferably be excellent in transparency, mechanical strength, thermal stability, moisture barrier and isotropy. Examples include polyester polymers such as polyethylene terephthalate or polyethylene naphthalate, cellulose polymers such as cellulose diacetate or cellulose triacetate, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin), polycarbonate polymers, etc. In addition, the following polymers can be cited as examples of polymers forming the above-mentioned transparent protective film: polyethylene, polypropylene, polyolefins having a ring system or even a norbornene structure, polyolefin polymers of ethylene-propylene copolymers, vinyl chloride polymers, amide polymers such as nylon or aromatic polyamide, imide polymers, sulfonium polymers, polyethersulfonium polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinyl chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyoxymethylene polymers, epoxy polymers or blends of the above polymers, etc. The transparent protective film may also contain one or more arbitrary appropriate additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, coloring agents, etc. The content of the thermoplastic resin in the transparent protective film is preferably 50-100% by mass, preferably 50-99% by mass, more preferably 60-98% by mass, and particularly preferably 70-97% by mass. When the content of the thermoplastic resin in the transparent protective film is less than 50% by mass, there is a risk that the high transparency originally possessed by the thermoplastic resin cannot be fully exerted.

As the transparent protective film, there can be cited the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01/37007), for example, a resin composition containing (A) a thermoplastic resin having a substituted and/or unsubstituted amide group in the side chain and a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group in the side chain. A specific example is a film containing a resin composition of an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The film can be a film composed of a mixed extrudate of the resin composition. Such films can eliminate the unevenness and other undesirable conditions caused by the strain of polarizing films due to their small phase difference and small photoelastic coefficient, and have excellent humidification durability due to their low moisture permeability.

In addition, the moisture permeability of the transparent protective film used in the present invention is preferably 150 g/m ² /24h or less. According to the above structure, it is difficult for moisture in the air to enter the polarizing film, and the change in moisture content of the polarizing film itself can be suppressed. As a result, the curling or dimensional change of the polarizing film caused by the storage environment can be suppressed.

The transparent protective film disposed on one or both sides of the polarizer is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier and isotropy, and in particular, preferably has a moisture permeability of 150g/ ^m2 /24h or less, 120g/ ^m2 /24h or less, and 5-70g/ ^m2 /24h or less.

The material for forming the transparent protective film satisfying the aforementioned low moisture permeability may be polyester resins such as polyethylene terephthalate or polyethylene naphthalate; polycarbonate resins; aromatic ester resins; amide resins such as nylon or aromatic polyamide; polyolefin polymers such as polyethylene, polypropylene, and ethylene-propylene copolymers, cyclic olefin resins having a cyclic or even norbornene structure, (meth) acrylic resins, or mixtures thereof. Among the aforementioned resins, polycarbonate resins, cyclic polyolefin resins, and (meth) acrylic resins are preferred, and cyclic polyolefin resins and (meth) acrylic resins are particularly preferred.

The thickness of the transparent protective film can be appropriately determined. Generally speaking, from the perspective of strength, workability, thinness, etc., it is preferably 5~100μm. 10~60μm is particularly preferred, and 13~40μm is more preferred.

The aforementioned transparent protective film usually uses one with a front phase difference of less than 40nm and a thickness direction phase difference of less than 80nm. The front phase difference Re is represented by Re=(nx-ny)×d. The thickness direction phase difference Rth is represented by Rth=(nx-nz)×d. And, the Nz coefficient is represented by Nz=(nx-nz)/(nx-ny). [However, the refractive index of the slow axis direction, fast axis direction and thickness direction of the film is set to nx, ny, nz respectively, and d(nm) is set to the thickness of the film; the slow axis direction is set to the direction where the refractive index in the film surface becomes the largest]. In addition, the transparent protective film should be as colorless as possible. A protective film with a thickness direction phase difference value of -90nm~+75nm can be appropriately used. By using the retardation value (Rth) in the thickness direction of -90nm~+75nm, the problem of the transparent protective film causing the polarizing film to be colored (optically colored) can be almost solved. The retardation value (Rth) in the thickness direction is preferably -80nm~+60nm, and -70nm~+45nm is particularly preferred.

On the other hand, as the aforementioned transparent protective film, a phase difference plate having a front phase difference of 40 nm or more and/or a thickness direction phase difference of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a phase difference plate is used as a transparent protective film, the phase difference plate can also function as a transparent protective film, so it can be thinned.

As the phase difference plate, there can be used birefringent films made by uniaxial or biaxial stretching of polymer materials, oriented films of liquid crystal polymers, and oriented layers of liquid crystal polymers supported by films, etc. There is no particular restriction on the thickness of the phase difference plate, which is generally around 20 to 150 μm. Examples of polymer materials include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyaryl sulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or various binary and ternary copolymers, graft copolymers, and blends thereof. These polymer materials can be oriented (stretched film) by stretching.

Liquid crystal polymers include, for example, various main chain or side chain types in which conjugated linear atomic groups (mesogens) that can impart liquid crystal orientation are introduced into the main chain or side chain of the polymer. Specific examples of main chain type liquid crystal polymers include nematic polyester liquid crystal polymers, discotic polymers, or cholesterol polymers, which have a structure in which a mesogen is bonded to a spacer that can impart flexibility. Specific examples of side chain type liquid crystal polymers include those with polysiloxane, polyacrylate, polymethacrylate, or polymalonate as the main chain skeleton, and with a mesogen composed of a para-substituted cyclic compound unit that imparts nematic orientation as a side chain via a spacer composed of conjugated atomic groups. These liquid crystal polymers are formed by, for example, spreading a liquid crystal polymer solution on a surface of a film such as polyimide or polyvinyl alcohol formed on a glass plate that has been subjected to a friction treatment or an orientation treatment surface such as an obliquely evaporated silicon oxide surface, and then performing a heat treatment.

The phase difference plate may be one having an appropriate phase difference according to the intended use, for example, one that utilizes the birefringence of various wavelength plates or liquid crystal layers for coloring or compensating for viewing angles, or one that layers two or more phase difference plates to control optical properties such as phase difference.

Retardation plates can be selected to meet the relationship of nx=ny＞nz, nx＞ny＞nz, nx＞ny=nz, nx＞nz＞ny, nz=nx＞ny, nz＞nx＞ny, nz＞nx=ny according to various uses. In addition, ny=nz not only includes the case where ny and nz are completely the same, but also includes the case where ny and nz are substantially the same.

For example, for a phase difference plate satisfying nx＞ny＞nz, it is preferable to use a phase difference satisfying 40~100nm in the front direction, 100~320nm in the thickness direction, and 1.8~4.5 in the Nz coefficient. For example, for a phase difference plate satisfying nx＞ny=nz (positive A plate), it is preferable to use a phase difference satisfying 100~200nm in the front direction. For example, for a phase difference plate satisfying nz=nx＞ny (negative A plate), it is preferable to use a phase difference satisfying 100~200nm in the front direction. For example, for a phase difference plate satisfying nx＞nz＞ny, it is preferable to use a phase difference satisfying 150~300nm in the front direction and an Nz coefficient satisfying greater than 0 and up to 0.7. Furthermore, as described above, for example, those satisfying nx=ny＞nz, nz＞nx＞ny, or nz＞nx=ny may be used.

The transparent protective film can be appropriately selected according to the liquid crystal display device used. For example, in the case of VA (Vertical Alignment, including MVA and PVA), it is better that the transparent protective film on at least one side (unit side) of the polarizing film has a phase difference. As for the specific phase difference, the range of Re=0~240nm and Rth=0~500nm is preferred. In terms of three-dimensional refractive index, the situation of nx＞ny=nz, nx＞ny＞nz, nx＞nz＞ny, nx=ny＞nz (positive A plate, biaxial, negative C plate) is preferred. The VA type is preferably a combination of a positive A plate and a negative C plate, or a single biaxial film. When polarizing films are used above and below the liquid crystal unit, both the upper and lower sides of the liquid crystal unit can have a phase difference, or the transparent protective film on either side can have a phase difference.

For example, in the case of IPS (In-Plane Switching, including FFS), the transparent protective film on one side of the polarizing film can be used regardless of whether it has a phase difference or not. For example, when there is no phase difference, it is better if the upper and lower sides (sides of the unit) of the liquid crystal unit have no phase difference. When there is a phase difference, it is better if both the upper and lower sides of the liquid crystal unit have a phase difference, or if either side has a phase difference (for example, the upper side is a biaxial film that satisfies the relationship nx＞nz＞ny and the lower side has no phase difference, or the upper side is a positive A plate and the lower side is a negative C plate). When there is a phase difference, the range of Re=-500~500nm and Rth=-500~500nm is better. In terms of three-dimensional refractive index, nx＞ny=nz, nx＞nz＞ny, nz＞nx=ny, nz＞nx＞ny (positive A plate, biaxial, negative C plate) are preferred.

The transparent protective film may be further laminated with a peelable substrate to improve its mechanical strength or operability. The peelable substrate may be peeled off from the laminate containing the transparent protective film and the polarizer before or after laminating the transparent protective film and the polarizer, during the step or in other steps.

<Polarizing film manufacturing method> The following describes each step in the polarizing film manufacturing method of the present invention with reference to FIG1.

<First coating step> The first coating step is a step of coating the bonding surface of the polarizer 2 with the bonding composition while conveying the polarizer 2 to form a wet first coating film. In addition, the bonding composition may be coated on one side of the polarizer 2 or on both sides of the polarizer 2.

<Second coating step> The second coating step is a step of coating the aforementioned adhesive composition on the bonding surface of the transparent protective film 3 while conveying the transparent protective film 3 to form a second coating film.

The polarizer 2 and the transparent protective film 3 may also be subjected to surface modification treatment before the coating step. It is particularly preferable to perform surface modification treatment on the surface of the polarizer 2. The surface modification treatment may include corona treatment, plasma treatment, excimer treatment and flame treatment, and corona treatment is particularly preferred. By performing corona treatment, reactive functional groups such as carbonyl or amine groups can be generated on the surface of the polarizer 2, thereby improving the adhesion with the adhesive layer. In addition, the ashing effect can remove foreign matter on the surface and reduce surface unevenness, so that a polarizing film with excellent appearance characteristics can be made.

The coaters 4 and 5 are not particularly limited, and examples thereof include reverse coaters, gravure coaters (direct, reverse and planographic), rod reverse coaters, roll coaters, die coaters, rod coaters and rod coaters.

The method of applying the easy-to-adhesive composition on the bonding surface of the polarizer 2 and the method of applying the adhesive composition on the bonding surface of the transparent protective film 3 can be appropriately selected according to the viscosity or desired thickness of the aforementioned components. However, from the perspective of removing foreign matter on the surface of the polarizer 2 and the transparent protective film 3, coating properties, and controlling the thickness of the coating film, it is preferable to use a post-metering coating method. Specific examples of the post-metering coating method include a gravure roller coating method, a forward roll coating method, an air knife coating method, a rod/bar coating method, and the like. Among them, from the perspective of removing foreign matter on the surface of the polarizer 2 and the transparent protective film 3, coating properties, and controlling the thickness of the coating film, the gravure roller coating method is particularly preferable.

In the gravure roller coating method, various patterns can be formed on the surface of the gravure roller, such as honeycomb grid pattern, trapezoidal pattern, lattice pattern, pyramid pattern or oblique line pattern. In order to effectively prevent the appearance defects of the polarizing film finally obtained, the pattern formed on the surface of the gravure roller is preferably a honeycomb grid pattern. When it is a honeycomb grid pattern, in order to improve the surface accuracy of the coated surface after coating, the groove volume is preferably 1~ ^5cm3 / ^m2 , and preferably 2~ ^3cm3 / ^m2 . Similarly, in order to improve the surface accuracy of the coated surface after coating, the number of groove lines per inch of the roller is preferably 200~3000 lines/inch. Furthermore, relative to the traveling speed of the polarizer 2 and the transparent protective film 3, the rotation speed ratio of the gravure roller is preferably 100-300%.

<First thickness measurement step> The first thickness measurement step is a step of measuring the thickness of the wet first coating online. The film thickness gauge 6 used for online measurement is preferably an optical (non-contact) film thickness gauge. The optical (non-contact) film thickness gauge is not particularly limited, and examples thereof include a spectral interference film thickness gauge, a reflection spectral film thickness gauge, and a concentric focus film thickness gauge. In particular, a spectral interference film thickness gauge that can measure the thickness of the coating in total width is preferred.

<Drying step> The adhesive composition contains water, so after the thickness of the wet first coating is measured online, the water in the wet first coating is removed using a dryer 7. When water remains in the dry first coating, water will remain in the uncured adhesive layer obtained by laminating the dry first coating and the second coating. As a result, adverse conditions such as the segregation of the polymerization initiator in the uncured adhesive layer and the cation curing of the uncured adhesive layer being hindered will occur, resulting in reduced adhesion of the adhesive layer. Therefore, a drying step is provided to remove as much water as possible from the wet first coating. The drying step is a method well known to those skilled in the art, and can be performed, for example, by air drying, heat drying or hot air drying.

The temperature of the dryer 7 is not particularly limited, but is preferably 15-40° C., preferably 20-35° C. Also, the air volume of the dryer 7 is not particularly limited, but is preferably 3.8-30.0 m ³ /min per unit width (m), preferably 6.0-15.5 m ³ /min.

<Dryness adjustment step> After the aforementioned drying step, the thickness of the dry first coating is measured online with a film thickness meter 8, and the temperature and/or air volume of the dryer 7 are adjusted so that the ratio of the thickness of the wet first coating measured online to the thickness of the dry first coating satisfies the following formula (A), thereby adjusting the dryness of the newly formed dry first coating. (Thickness of the dry first coating/Thickness of the wet first coating)-(Content ratio of water in the easily bonded composition)≦0.05(A)

(Thickness of the first dry coating/Thickness of the first wet coating)-(Content ratio of water in the adhesive composition) is preferably 0.04 or less, preferably 0.03 or less, and even more preferably 0.02 or less.

The film thickness meter 8 used for online measurement is preferably an optical (non-contact) film thickness meter. The optical (non-contact) film thickness meter is not particularly limited, and examples thereof include the above-mentioned film thickness meter. In particular, a spectroscopic interference film thickness meter that can measure the thickness of the dry first coating in total width is preferred.

<Laminating step> The laminating step is a step of laminating the dry first coating formed on the laminating surface of the polarizer 2 and the second coating formed on the laminating surface of the transparent protective film 3 to form an uncured adhesive layer. The laminating can be performed by a roller laminator 9 or the like.

<Next step> The next step is to manufacture the polarizing film 1 by bonding the polarizing element 2 and the transparent protective film 3 together by hardening the unhardened adhesive layer to obtain an adhesive layer.

After the polarizer 2 and the transparent protective film 3 are bonded together, the active energy rays (electron beam, ultraviolet rays, visible light, etc.) are irradiated, or heated, to cure the uncured adhesive layer to form an adhesive layer. The irradiation direction of the active energy rays (electron beam, ultraviolet rays, visible light, etc.) can be irradiated from any appropriate direction. It is preferred to irradiate from the side of the transparent protective film 3. If irradiation is performed from the side of the polarizer 2, there is a risk that the polarizer 2 will be degraded by the active energy rays (electron beam, ultraviolet rays, visible light, etc.).

Any appropriate conditions may be used for the electron beam irradiation as long as the above-mentioned uncured adhesive layer can be cured. For example, the accelerating voltage during the electron beam irradiation is preferably 5kV~300kV, preferably 10kV~250kV. When the accelerating voltage is lower than 5kV, the electron beam will not be able to reach the uncured adhesive layer and may not be cured enough; when the accelerating voltage is higher than 300kV, the penetration will be too strong and may damage the transparent protective film or polarizer. The irradiation dose is preferably 5~100kGy, preferably 10~75kGy. When the irradiation dose is less than 5kGy, the uncured adhesive layer will not be cured enough; when it is greater than 100kGy, it will damage the transparent protective film or polarizer, reduce the mechanical strength or cause yellowing, and there is a tendency that the predetermined optical properties cannot be obtained.

Electron beam irradiation is usually performed in an inert gas, but if necessary, it can be performed in the atmosphere or under conditions where a small amount of oxygen is introduced. Although it depends on the material of the transparent protective film, by appropriately introducing oxygen to intentionally create an oxygen barrier on the surface of the transparent protective film that the electron beam will initially contact, it is possible to prevent damage to the transparent protective film and efficiently irradiate only the uncured adhesive layer with the electron beam.

In the manufacturing method of the polarizing film of the present invention, the active energy ray is preferably the one including visible light in the wavelength range of 380nm~450nm, especially the active energy ray with the largest irradiation amount of visible light in the wavelength range of 380nm~450nm. When using ultraviolet light and visible light, if a transparent protective film endowed with ultraviolet light absorption ability (ultraviolet light non-transmissive transparent protective film) is used, it will absorb light with a wavelength shorter than about 380nm, so the light with a wavelength shorter than 380nm will not reach the adhesive composition and will not help its polymerization reaction. In addition, the light with a wavelength shorter than 380nm absorbed by the transparent protective film will be converted into heat, causing the transparent protective film itself to heat up, causing the polarizing film to curl, wrinkle and other defects. Therefore, when ultraviolet rays and visible rays are used in the present invention, it is preferred that the active energy ray generating device does not emit light with a wavelength shorter than 380nm. More specifically, the ratio of the accumulated illuminance in the wavelength range of 380-440nm to the accumulated illuminance in the wavelength range of 250-370nm is preferably 100:0 to 100:50, and more preferably 100:0 to 100:40. In the manufacturing method of the polarizing film of the present invention, the active energy ray is preferably a metal halogen lamp filled with gallium or an LED light source emitting a wavelength range of 380-440nm. Alternatively, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, incandescent bulbs, xenon lamps, halogen lamps, carbon arc lamps, metal halogen lamps, fluorescent lamps, tungsten filament lamps, gallium lamps, ultraviolet and visible light sources including excimer lasers or sunlight may be used. Bandpass filters may also be used to shield ultraviolet rays with wavelengths shorter than 380nm. In order to improve the bonding performance of the adhesive layer between the polarizer and the transparent protective film and prevent the polarizing film from curling, it is advisable to use a metal halogen lamp filled with gallium and use active energy rays obtained through a bandpass filter that can block light with a wavelength shorter than 380nm, or use active energy rays with a wavelength of 405nm obtained by using an LED light source.

It is preferred to heat the uncured adhesive layer before irradiation with ultraviolet rays or visible rays (heating before irradiation), preferably to a temperature of 40°C or above, preferably to a temperature of 50°C or above. It is also preferred to heat the adhesive layer after irradiation with ultraviolet rays or visible rays (heating after irradiation), preferably to a temperature of 40°C or above, preferably to a temperature of 50°C or above.

The adhesive composition used in the present invention is particularly suitable for forming an adhesive layer for bonding a polarizer to a transparent protective film having a transmittance of less than 5% at a wavelength of 365 nm. Here, the adhesive composition used in the present invention can be cured to form an adhesive layer by irradiating ultraviolet rays through a transparent protective film having UV absorption ability with a photo radical polymerization initiator containing the above-mentioned general formula (3). Therefore, even if a polarizing film is laminated with a transparent protective film having UV absorption ability on both sides of the polarizer, the adhesive layer can be cured. And of course, the adhesive layer can also be cured for a polarizing film laminated with a transparent protective film that does not have UV absorption ability. Furthermore, the so-called transparent protective film having UV absorption capability refers to a transparent protective film having a transmittance of less than 10% for light of 380 nm.

The method of imparting UV absorption capability to the transparent protective film includes a method of making the transparent protective film contain an ultraviolet absorber, or a method of coating the surface of the transparent protective film with a surface treatment layer containing an ultraviolet absorber.

Specific examples of the ultraviolet absorber include conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds, tris(iodine) compounds, and the like.

In the manufacturing method of the polarizing film of the present invention, the production line speed is determined by the curing time of the uncured adhesive layer, but is preferably 1-500 m/min, more preferably 5-300 m/min, and even more preferably 10-100 m/min. When the production line speed is too low, the productivity is poor, or excessive damage is caused to the transparent protective film, and a polarizing film that can withstand durability tests cannot be produced. When the production line speed is too high, the curing of the uncured adhesive layer will be insufficient, and the desired adhesion may not be obtained.

<Adhesive layer> The adhesive layer is formed by hardening the uncured adhesive layer. The thickness of the adhesive layer is preferably 0.01~3µm. If the adhesive layer is too thin, the peeling force is reduced due to insufficient cohesion of the adhesive layer, which is not good. If the adhesive layer is too thick, it becomes easy to peel off when stress is applied to the cross section of the polarizing film, and peeling defects caused by impact occur, which is not good. The thickness of the adhesive layer is preferably 0.1~2.5μm, and more preferably 0.5~1.5μm.

<Optical film> When the polarizing film of the present invention is actually used, it can be used as an optical film laminated with other optical layers. There is no particular limitation on the optical layer, and examples thereof include phase difference films (including 1/2 or 1/4 wavelength plates), visual compensation films, brightness enhancement films, reflective plates or semi-transmissive plates, etc., which can be used to form optical layers for liquid crystal display devices, etc.

As the retardation film, a film having a front retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. The front retardation is usually controlled within the range of 40 to 200 nm, and the thickness direction retardation is usually controlled within the range of 80 to 300 nm.

As the phase difference film, there can be used birefringent films made by uniaxial or biaxial stretching of polymer materials, oriented films of liquid crystal polymers, and oriented layers of liquid crystal polymers supported by films. The thickness of the phase difference film is not particularly limited, and is generally about 20 to 150 μm.

As a phase difference film, a reverse wavelength dispersion phase difference film satisfying the following formula (1) to (3) can also be used: 0.70＜Re[450]/Re[550]＜0.97…(1) 1.5×10-3＜Δn＜6×10-3…(2) 1.13＜NZ＜1.50…(3) (wherein, Re[450] and Re[550] are the in-plane phase difference values of the phase difference film measured at 23°C with light of wavelengths of 450nm and 550nm, respectively; Δn is the in-plane birefringence of nx-ny when the refractive index in the slow axis direction and the fast axis direction of the phase difference film are set to nx and ny, respectively; NZ is the ratio of the birefringence in the thickness direction nx-nz to the in-plane birefringence nx-ny when nz is the refractive index in the thickness direction of the phase difference film).

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

The adhesive layer can also be provided on one or both sides of the polarizing film or optical film in the form of overlapping layers of different compositions or types. Furthermore, when provided on both sides, adhesive layers of different compositions, types or thicknesses can be provided on the front and back of the polarizing film or optical film. The thickness of the adhesive layer can be appropriately determined according to the purpose of use or the bonding force, and is generally 1~500µm, preferably 1~200µm, and particularly preferably 1~100µm.

To prevent the exposed surface of the adhesive layer from being contaminated, a separating piece may be temporarily attached and covered before it is actually used. This prevents the adhesive layer from being touched during normal operation. As a separating piece, in addition to the above-mentioned thickness conditions, appropriate items known in the art may be used, such as plastic films, rubber sheets, paper, cloth, non-woven fabrics, meshes, foam sheets, or metal foils and laminates thereof, which may be coated with appropriate stripping agents such as polysilicone, long-chain alkyl, fluorine, or molybdenum sulfide as needed.

<Image display device> The polarizing film or optical film of the present invention can be suitably used in the formation of various devices such as liquid crystal display devices. The formation of liquid crystal display devices can be carried out in the same manner as before. That is, liquid crystal display devices are generally formed by properly assembling liquid crystal units with polarizing films or optical films and components such as lighting systems that meet the needs and incorporating them into drive circuits, etc. In the present invention, there is no special limitation except that the polarizing film or optical film of the present invention is used, and it can be used according to common knowledge. Regarding the liquid crystal unit, any type such as TN type, STN type, π type, etc. can be used.

A liquid crystal display device can be formed in which a polarizing film or an optical film is arranged on one side or both sides of a liquid crystal unit, or a liquid crystal display device that uses a backlight or a reflective plate as an appropriate lighting system. In this case, the polarizing film or the optical film of the present invention can be arranged on one side or both sides of the liquid crystal unit. When the polarizing film or the optical film is arranged on both sides, they can be the same or different. In addition, when forming a liquid crystal display device, one or more layers of appropriate parts 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 arranged at an appropriate position.

Embodiments The following describes embodiments of the present invention, but the embodiments of the present invention are not limited thereto.

<Polarizer> First, a laminate with a 9μm thick PVA layer formed on an amorphous PET substrate was made into a stretched laminate by air-assisted stretching at a stretching temperature of 130°C. Then, the stretched laminate was dyed to make a colored laminate. The colored laminate and the amorphous PET substrate were stretched together by stretching in boric acid water at a stretching temperature of 65°C, so that the total stretching ratio was 5.94 times, and an optical thin film laminate including a 5μm thick PVA layer was made. By the two-stage extension, an optical film laminate including a PVA layer with a thickness of 5 μm for constituting a thin polarizer can be obtained. The PVA molecules of the PVA layer formed on the amorphous PET substrate of the optical film laminate are highly oriented, and the iodine adsorbed by dyeing is highly oriented in one direction in the form of a polyiodine ion complex. The moisture content of the thin polarizer (PVA layer) is 10 mass %.

<Transparent protective film> As the transparent protective film, a 13µm thick cycloolefin polymer film (ZEON Japan: ZF-14) was used.

<Active Energy Ray> As active energy rays, ultraviolet rays with a maximum illuminance of 500mW/ ^cm2 and an accumulated light quantity of 800mJ/ ^cm2 were irradiated from the transparent protective film side using a UV irradiation device (high-pressure mercury lamp manufactured by Toshiba) to produce a polarizing film.

<Preparation of an easy-to-bond composition> 54 parts by mass of 4-hydroxybutyl acrylate, 1 part by mass of 3-acrylamidophenylboronic acid (manufactured by Junsei Chemical Co., Ltd.) and 45 parts by mass of water were mixed and stirred at 25°C for 10 minutes to prepare an easy-to-bond composition. The water content in the easy-to-bond composition was 0.45.

<Preparation of adhesive composition> ω-carboxy-polycaprolactone (n≒2) monoacrylate (M5300, manufactured by Toagosei Co., Ltd.) 5 parts by mass, isoborneol acrylate 10 parts by mass, acrylyl isoflurane (ACMO, manufactured by Kojin Co., Ltd., SP value: 22.9) 20 parts by mass, 3,4-epoxyepoxyhexylmethyl-3,4-epoxyepoxyhexanecarboxylate (CELLOXIDE 2021P, manufactured by Daicel Chemical Industries, Ltd.) 1 part by mass, 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide (TPO, manufactured by Ciba Specialty Chemicals Co., Ltd.) and p-phenylphenylthiodiphenylphosphine PF were mixed. ₆ salt (CPI-110P manufactured by San-Apro Co., Ltd.) and 2 parts by weight were mixed and stirred at 50° C. for 1 hour to prepare an adhesive composition.

Example 1 On a continuous production line, a gravure roller coating method with a gravure roller was used to coat the PVA surface of a manufactured optical film laminate including a PVA layer with a thickness of 5µm with a prepared easy-to-bond composition at an initial setting thickness of 1190nm, thereby continuously forming a wet first coating film. On the other hand, on another continuous production line, a gravure roller coating method with a gravure roller was used to coat the prepared adhesive composition at an initial setting thickness of 1500nm on the bonding surface of the aforementioned transparent protective film, thereby continuously forming a second coating film. Then, the thickness of the wet first coating is measured online on a continuous production line using a spectroscopic interferometer film thickness meter (manufactured by Ocean Optics: spectrometer "USB2000+", light source "HL-2000", optical fiber "OCF-103995"). On the continuous production line, the dryer is used to dry the first wet coating at an initial setting of 25°C and an air volume of 12.5 ^m3 /min per unit width (m) to remove water from the first wet coating. At the same time, the thickness of the first dry coating is measured online with a spectroscopic interference film thickness meter (manufactured by Ocean Optics: spectrometer "USB2000+", light source "HL-2000", optical fiber "OCF-103995"). The temperature and air volume of the dryer are adjusted based on the measurement results to adjust the degree of dryness of the first dry coating to be formed. In addition, the degree of drying of the dry first coating is adjusted by appropriately adjusting the temperature of the dryer to 22-28°C and the air volume to 6.0-15.5 ^m3 /min so as to satisfy the following formula (A). (Thickness of the dry first coating/Thickness of the wet first coating)-(Content ratio of water in the adhesive composition) ≦0.05 (A) Next, the dry first coating formed on the bonding surface of the optical thin film laminate and the second coating formed on the bonding surface of the transparent protective film are bonded using a roller machine to form an uncured adhesive layer. Afterwards, the ultraviolet rays are irradiated from the side of the laminated transparent protective film using an active energy ray irradiation device, so that the polarizer and the transparent protective film are bonded through the adhesive layer, and hot air drying is performed at 70°C for 3 minutes to peel off the amorphous PET substrate, thereby obtaining a polarizing film with a transparent protective film on one side of the polarizer. The lamination production line speed is 25m/minute. Through the above series of steps, the polarizing film is continuously manufactured for 15 hours.

Comparative Example 1 On a continuous production line, a gravure roller coating method with a gravure roller was used to coat the PVA surface of a manufactured optical film laminate including a PVA layer with a thickness of 5µm with a prepared easy-to-bond composition at an initial setting thickness of 1195nm, thereby continuously forming a wet first coating film. On the other hand, on another continuous production line, a gravure roller coating method with a gravure roller was used to coat the prepared adhesive composition at an initial setting thickness of 1500nm on the bonding surface of the aforementioned transparent protective film, thereby continuously forming a second coating film. Then, the thickness of the wet first coating was measured online on the continuous production line using a spectroscopic interferometer (manufactured by Ocean Optics: spectrometer "USB2000+", light source "HL-2000", optical fiber "OCF-103995"). The first wet coating was dried in a dryer at 25°C and an initial setting of 12.5 ^m3 /min of air volume per unit width (m) to remove water from the wet first coating and form a dry first coating. Next, the dry first coating formed on the bonding surface of the optical thin film laminate and the second coating formed on the bonding surface of the transparent protective film were bonded using a roller machine to form an uncured adhesive layer. Afterwards, the ultraviolet rays are irradiated from the side of the laminated transparent protective film using an active energy ray irradiation device, so that the polarizer and the transparent protective film are bonded through the adhesive layer, and hot air drying is performed at 70°C for 3 minutes to peel off the amorphous PET substrate, thereby obtaining a polarizing film with a transparent protective film on one side of the polarizer. The lamination production line speed is 25m/minute. Through the above series of steps, the polarizing film is continuously manufactured for 15 hours.

Comparative Example 2 On a continuous production line, a gravure roller coating method with a gravure roller was used to coat the PVA surface of the optical film laminate including a 5µm thick PVA layer with a prepared easy-to-bond composition at an initial setting thickness of 1200nm, thereby continuously forming a wet first coating film. On the other hand, on another continuous production line, a gravure roller coating method with a gravure roller was used to coat the prepared adhesive composition at an initial setting thickness of 1500nm on the bonding surface of the aforementioned transparent protective film, thereby continuously forming a second coating film. Then, the thickness of the wet first coating was measured online on the continuous production line using a spectroscopic interferometer (manufactured by Ocean Optics: spectrometer "USB2000+", light source "HL-2000", optical fiber "OCF-103995"). The first wet coating was dried in a dryer at 25°C and an initial setting of 12.5 ^m3 /min of air volume per unit width (m) to remove water from the wet first coating and form a dry first coating. Next, the dry first coating formed on the bonding surface of the optical thin film laminate and the second coating formed on the bonding surface of the transparent protective film were bonded using a roller machine to form an uncured adhesive layer. Afterwards, the ultraviolet rays are irradiated from the side of the laminated transparent protective film using an active energy ray irradiation device, so that the polarizer and the transparent protective film are bonded through the adhesive layer, and hot air drying is performed at 70°C for 3 minutes to peel off the amorphous PET substrate, thereby obtaining a polarizing film with a transparent protective film on one side of the polarizer. The lamination production line speed is 25m/minute. Through the above series of steps, the polarizing film is continuously manufactured for 15 hours.

(Evaluation of adhesion) 5 minutes and 15 hours after the start of production, the polarizing film was cut into a size of 200mm in the extension direction parallel to the polarizer and 15mm in the straight direction, and then the polarizing film was bonded to the glass plate. Then, a cut was made between the transparent protective film and the polarizer with a utility knife, and the transparent protective film and the polarizer were peeled off in a 90-degree direction at a peeling speed of 1000mm/minute using a universal testing machine (TENSILON), and the peeling strength (N/15mm) was measured. The adhesion was evaluated according to the following criteria. ○: When the peeling force is 1N or more ×: When the peeling force is less than 1N

(Evaluation of bubbles) The number of bubbles was counted using an optical microscope on both sides of the polarizing film 5 minutes and 15 hours after the start of production. The number of bubbles was counted within a 5cm×5cm area, and a score of ○ was given when the total number of bubbles on both sides was less than 3, and a score of × was given when the total number of bubbles on both sides was more than 3.

[Table 2]

As shown in Table 2, in Example 1, the drying degree adjustment step is performed, so the variation of the drying degree of the dry first coating is suppressed in the continuous production, and even after 15 hours from the start of production, a polarizing film with excellent adhesion can be stably obtained. It can also be seen that the obtained polarizing film has suppressed the generation of bubbles. On the other hand, it can be seen that in Comparative Examples 1 and 2, the drying degree adjustment step is not performed, so the variation of the drying degree of the dry first coating becomes larger in the continuous production, and the polarizing film after 15 hours from the start of production has low adhesion of the adhesive layer because the water remaining in the first coating hinders the cationic polymerization reaction.

Industrial Applicability The polarizing film of the present invention can be used alone or in the form of a laminated optical film in image display devices such as liquid crystal display devices (LCD), organic EL display devices, CRT, PDP, etc.

1: Polarizing film 2: Polarizing element 3: Transparent protective film 4,5: Coating machine 6,8: Film thickness meter 7: Dryer 9: Roller laminator

FIG. 1 is a schematic diagram showing an example of a method for manufacturing the polarizing film of the present invention.

1: Polarizing film

2: Polarizer

3: Transparent protective film

4,5:Applicator

6,8: Film thickness gauge

7: Dryer

9: Roller laminating machine

Claims (7)

A method for manufacturing a polarizing film, wherein the polarizing film is provided with a transparent protective film on at least one side of a polarizing element through an adhesive layer, and the manufacturing method is characterized in that it comprises the following steps: a first coating step, wherein a bonding composition containing water and a hydrophilic monomer is coated on the bonding surface of the polarizing element while the polarizing element is transported, so as to form a wet first coating film; a second coating step, wherein a bonding composition containing water and a hydrophilic monomer is coated on the bonding surface of the polarizing element while the polarizing element is transported; and The bonding surface is coated with an adhesive composition containing a free radical polymerizable compound and a cationic polymerizable compound to form a second coating film; the first thickness measuring step is to measure the thickness of the aforementioned wet first coating film online; the drying step is to remove water in the aforementioned wet first coating film using a dryer after the aforementioned first thickness measuring step to form a dry first coating film; the second thickness measuring step is to measure the thickness of the aforementioned dry first coating film online after the aforementioned drying step; The step of adjusting the degree of dryness is to adjust the temperature and/or air volume of the dryer so that the ratio of the thickness of the wet first coating film obtained by the online measurement to the thickness of the dry first coating film satisfies the following formula (A), thereby adjusting the degree of dryness of the newly formed dry first coating film; the step of laminating is to laminate the dry first coating film formed on the laminating surface of the polarizer and the second coating film formed on the laminating surface of the transparent protective film, thereby forming The uncured adhesive layer is formed; and the following step is to cure the uncured adhesive layer to obtain the aforementioned adhesive layer, so that the aforementioned polarizer and the aforementioned transparent protective film are bonded; (thickness of the first dry coating/thickness of the first wet coating)-(water content in the easy-bonding composition) ≦0.05 (A); and, when the total amount of the easy-bonding composition is set to 100% by mass, the water content of the aforementioned easy-bonding composition is 40~70% by mass. A method for producing a polarizing film as claimed in claim 1, wherein the aforementioned easily bondable composition contains a compound represented by the following general formula (1) and/or an organic metal compound having an MO bond (M is silicon, titanium, aluminum or zirconium, and O is an oxygen atom) in the structural formula;

(However, X is a functional group including a reactive group, and ^R1 and ^R2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aromatic group or a heterocyclic group). The method for manufacturing a polarizing film according to claim 2, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (1'):

(However, Y is an organic group, and X, ^R1 and ^R2 are the same as described above). The method for manufacturing a polarizing film as claimed in claim 2, wherein the reactive group of the compound represented by the general formula (1) is selected from at least one reactive group in the group consisting of α,β-unsaturated carbonyl, vinyl, vinyl ether, epoxy, cyclohexane, amino, aldehyde, butyl and halogen. The method for manufacturing a polarizing film as claimed in claim 1, wherein the moisture content of the polarizing element is less than 15% by mass. A method for manufacturing a polarizing film as claimed in any one of claims 1 to 5, wherein the first coating step and the second coating step are coating steps using a post-metering coating method. The manufacturing method of polarizing film as claimed in claim 6, wherein the aforementioned post-metering coating method is a gravure roller coating method using a gravure roller.