CN109536046B - Curing adhesive for polarizing film, optical film, and image display device - Google Patents

Abstract

The curable adhesive for polarizing films containing the curable component of the present invention has the following formula when a cured product of the curable adhesive for polarizing films is immersed in pure water at 23 ℃ for 24 hours: volume water absorption (%): { (M2-M1)/M1 }. times.100 (%), { wherein, in the above formula, M1 represents the weight of the cured product before immersion and M2 represents the weight of the cured product after immersion }, the volume water absorption rate is 10% by weight or less. The curable adhesive for polarizing films has good adhesion between a polarizing plate and a transparent protective film, can satisfy optical durability in a severe environment under high temperature and high humidity, and has sufficient adhesion even when immersed in water for a long time.

Description

Curing adhesive for polarizing film, optical film, and image display device

The present application is a divisional application of an application having an application date of 2014, 08/29, application No. 201480047627.0 and an invention name of "curable adhesive for polarizing film, optical film and image display device".

Technical Field

The present invention relates to a curable adhesive for polarizing films, which is obtained by forming an adhesive layer on a polarizing film obtained by laminating a polarizing plate and a transparent protective film with the adhesive layer interposed therebetween. The present invention also relates to a polarizing film using the adhesive layer. The polarizing film may be used alone or in the form of an optical film laminated with the polarizing film to form an image display device such as a Liquid Crystal Display (LCD), an organic EL display, a CRT, or a PDP.

Background

Liquid crystal display devices are rapidly growing in the market for watches, mobile phones, PDAs, notebook computers, monitors for personal computers, DVD players, TVs, and the like. A liquid crystal display device is a device that makes visible a polarization state caused by switching of liquid crystal, and uses a polarizing plate according to a display principle thereof. In particular, in applications such as TVs, high brightness, high contrast, and wide viewing angle are increasingly demanded, and polarizing films are also increasingly demanded to have high transmittance, high polarization degree, high color reproducibility, and the like.

As the polarizing plate, an iodine-based polarizing plate having a structure in which iodine is adsorbed to, for example, polyvinyl alcohol (hereinafter, also simply referred to as "PVA") and stretched is most widely used from the viewpoint of having high transmittance and high degree of polarization. In general, a polarizing film obtained by bonding transparent protective films to both surfaces of a polarizing plate using a so-called aqueous adhesive in which a polyvinyl alcohol material is dissolved in water is used (patent documents 1 and 2). Triacetyl cellulose or the like having high moisture permeability is used as the transparent protective film. When the above-mentioned water-based adhesive is used (so-called wet lamination), a drying step is required after the polarizing plate and the transparent protective film are bonded.

On the other hand, an active energy ray-curable adhesive has been proposed instead of the above-mentioned aqueous adhesive. When the polarizing film is produced using the active energy ray-curable adhesive, the productivity of the polarizing film can be improved because a drying step is not required. For example, a radical polymerization type active energy ray-curable adhesive using an N-substituted amide monomer as a curable component has been proposed (patent documents 3 and 4 below). This adhesive exhibits excellent durability under high humidity and severe environments at high temperatures, but in the market, there is a real ongoing demand for adhesives that can further improve adhesion and/or water resistance.

In addition, an active energy ray-curable adhesive has been proposed, which focuses on the SP value (solubility parameter) of the curable component, and by using at least 3 kinds of radical polymerizable compounds having different SP values at a predetermined composition ratio, an adhesive layer having improved durability and water resistance can be formed (patent document 5 below).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-220732

Patent document 2: japanese patent laid-open No. 2001-296427

Patent document 3: japanese patent laid-open No. 2008-287207

Patent document 4: japanese patent application laid-open No. 2010-078700

Patent document 5: japanese laid-open patent publication No. 2012 and 144690

Disclosure of Invention

Problems to be solved by the invention

The active energy ray-curable adhesive described in patent document 5 can satisfy durability and water resistance for various transparent protective films used in the production of polarizing films. However, although the polarizing film obtained using the active energy ray-curable adhesive described in patent document 5 can satisfy the water resistance (hot water immersion test) when immersed in hot water at 60 ℃ for 6 hours, the market is seeking further optical durability in a severe environment under high temperature and high humidity. Further, the polarizing film is required to have sufficient adhesive strength even when immersed in water for a long time.

The invention aims to provide a curing adhesive for a polarizing film, which has good adhesion with a polaroid and a transparent protective film, can meet the optical durability in a severe environment under high temperature and high humidity, and has sufficient adhesion even when immersed in water for a long time.

The present invention also provides a polarizing film having a transparent protective film provided on a polarizing plate by using an adhesive layer formed using a curable adhesive for polarizing films, an optical film using the polarizing film, and an image display device using the polarizing film or the optical film.

Means for solving the problems

The present inventors have made extensive studies to solve the above problems, and as a result, have found that the above object can be achieved by the following curable adhesive for polarizing films, and have solved the present invention.

That is, the present invention relates to a curable adhesive for a polarizing film, which is characterized by containing a curable component,

the curable adhesive for a polarizing film has the following formula when a cured product obtained by curing the curable adhesive is immersed in pure water at 23 ℃ for 24 hours:

volume water absorption (%) { (M2-M1)/M1} × 100,

{ wherein, in the above formula, the volume water absorption rate represented by M1 representing the weight of the cured product before immersion and M2 representing the weight of the cured product after immersion } is 10% by weight or less.

The octanol/water partition coefficient (logPow value) of the curable adhesive for a polarizing film is preferably 1 or more.

When the curable component is an active energy ray-curable component, the curable component can be used as an active energy ray-curable adhesive for the polarizing film. The curable component may contain a radical polymerizable compound. The radical polymerizable compound preferably contains a (meth) acrylamide derivative. The radical polymerizable compound preferably contains a polyfunctional compound having at least 2 functional groups having radical polymerizability. The active energy ray-curable adhesive may further contain a photopolymerization initiator.

The curable adhesive for a polarizing film may further contain an acrylic oligomer (a).

The curable adhesive for a polarizing film may further contain a photoacid generator (B).

The curable adhesive for polarizing films may further contain a compound (C) containing either an alkoxy group or an epoxy group. The compound (C) containing either an alkoxy group or an epoxy group is preferably a compound (C1) containing an alkoxy group. Further, the alkoxy group-containing compound (C1) is preferably an alkoxy group-containing melamine compound.

The curable adhesive for a polarizing film may further contain an isocyanate compound (D).

When the curable component is a thermosetting component, the curable adhesive for a polarizing film can be used as a thermosetting adhesive by further containing a thermal polymerization initiator.

The present invention also relates to a polarizing film comprising a polarizing plate and a transparent protective film provided on at least one surface of the polarizing plate via an adhesive layer,

the adhesive layer is formed from a cured product layer of the curable adhesive for polarizing films.

In the polarizing film, the thickness of the adhesive cured layer is preferably 0.1 to 3 μm.

The present invention also relates to an optical film characterized in that at least 1 sheet of the above polarizing film is laminated.

The present invention also relates to an image display device using the polarizing film or the optical film.

Effects of the invention

The curable adhesive for a polarizing film of the present invention has a volume water absorption of 10% by weight or less of a cured product obtained by curing the curable adhesive. This volume water absorption shows that the water absorption is very low when an adhesive layer is formed using a cured product layer obtained from the curable adhesive for polarizing films of the present invention. Therefore, in the polarizing film in which the transparent protective film is provided on the polarizing plate via the adhesive layer including the cured product layer, the adhesion between the polarizing plate and the transparent protective film layer is good, and the optical durability in a severe environment under high temperature and high humidity can be satisfied.

For example, a polarizing film having a cured layer (adhesive layer) formed using the curable adhesive for a polarizing film of the present invention is excellent in optical durability (humidity durability test) under a severe humidity environment (85 ℃x85% RH). Therefore, the polarizing film of the present invention can suppress a decrease (change) in transmittance and polarization degree of the polarizing film to a small degree even when it is placed in the above-described severe humidified environment. The present invention also provides a polarizing film which can suppress a decrease in adhesive strength even in a severe environment such as immersion in water and has sufficient adhesive strength even when immersed in water for a long time.

Detailed Description

< volume Water absorption >

The curable adhesive for a polarizing film of the present invention has a volume water absorption of 10% by weight or less as measured by immersing a cured product obtained by curing the curable adhesive in pure water at 23 ℃ for 24 hours. When the polarizing film is placed in a severe environment of high temperature and high humidity (85 ℃/85% RH, etc.), moisture that has passed through the transparent protective film and the adhesive layer penetrates into the polarizing plate, and the crosslinked structure is hydrolyzed, whereby the alignment of the 2-color dye is disturbed, and deterioration of optical durability such as increase in transmittance and decrease in degree of polarization is caused. By setting the volume water absorption of the adhesive layer to 10 wt% or less, it is possible to suppress the migration of water to the polarizing plate when the polarizing film is placed in a severe high-temperature and high-humidity environment, and to suppress the increase in transmittance and the decrease in polarization degree of the polarizing plate. The volume water absorption is preferably 5 wt% or less, more preferably 3 wt% or less, even more preferably 1.5 wt% or less, and most preferably 1 wt% or less, of the adhesive layer of the polarizing film, from the viewpoint of further improving the optical durability in a severe environment at high temperatures. On the other hand, when the polarizing plate and the transparent protective film are bonded, a certain amount of moisture is retained in the polarizing plate, and appearance defects such as a cavity (ハジキ) and bubbles may occur when the curable adhesive comes into contact with moisture contained in the polarizing plate. In order to suppress the appearance defect, it is preferable that the curable adhesive can absorb a certain amount of moisture. More specifically, the volume water absorption is preferably 0.01 wt% or more, and more preferably 0.05 wt% or more. Specifically, the volume water absorption was measured by the water absorption test method described in JISK 7209.

The curable adhesive for polarizing films of the present invention preferably has a high octanol/water partition coefficient (hereinafter referred to as logPow value). The logPow value is an index indicating the lipophilicity of a substance and is a logarithmic value of the partition coefficient of octanol/water. A high logPow means oleophilic, i.e. low water absorption. The logPow value can also be measured (by the flask permeation method described in JIS-Z-7260), but it can also be calculated by calculation based on the structure of each compound as a constituent (curable component, etc.) of the curable adhesive for polarizing films. In this specification, the logPow value calculated by ChemDraw Ultra manufactured by Cambridge Soft corporation is used.

The logPow value of the curable adhesive for a polarizing film in the present invention can be calculated by the following formula based on the above calculated values.

logPow ═ Sigma (logPowi. times Wi) of curing adhesive

logPowi: logPow value of each component of curing adhesive

And Wi: (number of moles of component i)/(total number of moles of components of the curable adhesive)

In the above calculation, among the components of the curable adhesive, components such as a polymerization initiator and a photoacid generator which do not form a skeleton of a cured product (adhesive layer) are removed from the components in the above calculation. The logPow value of the curable adhesive for polarizing films of the present invention is preferably 1 or more, more preferably 1.5 or more, and most preferably 2 or more. This improves the water resistance and moisture resistance of the adhesive. On the other hand, the logPow value of the curable adhesive for a polarizing film of the present invention is usually about 8 or less, preferably 5 or less, and more preferably 4 or less. If the logPow value is too high, appearance defects such as the above-described craters and bubbles are likely to occur, which is not preferable.

In addition, the means for setting the volume water absorption to 10% by weight or less in the present invention is not particularly limited, but in the case where the curable adhesive for polarizing film is a composition containing a plurality of components, the volume water absorption can be controlled to the above range by selecting each component. For example, when the curable adhesive for a polarizing film is an adhesive composition containing a plurality of components, the volume water absorption can be controlled to the above range by a method such as preparing the adhesive composition so that the ratio of the components having a logPow value of 1 or less is small. In order to adjust the volume water absorption of the present invention to 10 wt% or less, for example, the logPow value of the curable adhesive for polarizing film may be controlled to 1 or more.

< curing shrinkage >

Further, since the curable adhesive for a polarizing film of the present invention has a curable component, when the curable adhesive is cured, curing shrinkage usually occurs. The curing shrinkage is an index indicating the ratio of curing shrinkage when an adhesive layer is formed from the curable adhesive for a polarizing film. When the curing shrinkage of the adhesive layer is increased, it is preferable from the viewpoint of suppressing the occurrence of interfacial strain and the occurrence of poor adhesion when the adhesive layer is formed by curing the curable adhesive for a polarizing film. From the above viewpoint, the cure shrinkage of a cured product obtained by curing the curable adhesive for polarizing films of the present invention is preferably 10% or less. The cure shrinkage is preferably small, and the cure shrinkage is preferably 8% or less, and more preferably 5% or less. The curing shrinkage rate is measured by the method described in japanese patent application laid-open No. 2013-104869, specifically by the method described in the examples using a curing shrinkage sensor manufactured by Sentec corporation.

< curable Components >

The curable adhesive for a polarizing film of the present invention contains a curable component. The curable component is appropriately selected so that the cured product satisfies the above-mentioned volume water absorption rate.

The curable component can be broadly classified into an active energy ray-curable type such as an electron beam-curable type, an ultraviolet-curable type, and a visible light-curable type, and a heat-curable type. Further, ultraviolet-curable adhesives and visible-light-curable adhesives can be roughly classified into radical polymerization-curable adhesives and cationic polymerization-curable adhesives. In the present invention, an active energy ray having a wavelength range of 10nm to less than 380nm is referred to as ultraviolet ray, and an active energy ray having a wavelength range of 380nm to 800nm is referred to as visible light. The curable component of the radical polymerization curable adhesive can be used as the curable component of the thermosetting adhesive.

< 1: radical polymerization curing adhesive >

Examples of the curable component include a radical polymerizable compound used in a radical polymerization curable adhesive. Examples of the radical polymerizable compound include compounds having a radical polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group or a vinyl group. Any of monofunctional radical polymerizable compounds and difunctional or higher polyfunctional radical polymerizable compounds can be used as the curable component. These radical polymerizable compounds may be used alone in 1 kind, or in combination with 2 or more kinds. As these radical polymerizable compounds, for example, compounds having a (meth) acryloyl group are suitable. In the present invention, a (meth) acryloyl group means an acryloyl group and/or a methacryloyl group, and hereinafter, a "(meth)" means the same.

Monofunctional radical polymerizable Compound

Examples of the monofunctional radical polymerizable compound include a (meth) acrylamide derivative having a (meth) acrylamide group. The (meth) acrylamide derivative is preferable in terms of ensuring adhesiveness to a polarizing plate and various transparent protective films, and in terms of high polymerization rate and excellent productivity. Specific examples of the (meth) acrylamide derivative include: n-alkyl group-containing (meth) acrylamide derivatives such as N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-hexyl (meth) acrylamide; n-hydroxyalkyl-containing (meth) acrylamide derivatives such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propane (meth) acrylamide; (meth) acrylamide derivatives having an N-aminoalkyl group such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; n-alkoxy group-containing (meth) acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; n-mercaptoalkyl group-containing (meth) acrylamide derivatives such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide; and the like. Examples of the heterocyclic ring-containing (meth) acrylamide derivative in which the nitrogen atom of the (meth) acrylamide group forms a heterocyclic ring include: n-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloyltetrahydropyrrole and the like.

Among the above (meth) acrylamide derivatives, N-hydroxyalkyl group-containing (meth) acrylamide derivatives are preferable from the viewpoint of adhesion to polarizing plates and various transparent protective films, and N-hydroxyethyl (meth) acrylamide is particularly preferable.

Examples of the monofunctional radical polymerizable compound include: various (meth) acrylic acid derivatives having a (meth) acryloyloxy group. Specifically, examples thereof include: 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, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, (meth) acrylic acid (1-20) alkyl esters such as t-amyl (meth) acrylate, 3-amyl (meth) acrylate, 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 derivative include: cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate;

aralkyl (meth) acrylates such as benzyl (meth) acrylate;

polycyclic (meth) acrylates such as 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dihydrodicyclopentadiene (meth) acrylate (ジシクロペンテニル (メタ) アクリレ - ト), dihydrodicyclopentadiene ethyl (meth) acrylate (ジシクロペンテニル オ キ シ エ チ ル (メタ) アクリレ - ト), and tetrahydrodicyclopentadiene (meth) acrylate (ジシクロペンタニル (メタ) アクリレ ー ト);

(meth) acrylic acid esters having an alkoxy group or a phenoxy group such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and alkylphenoxypolyethylene glycol (meth) acrylate; and the like.

Further, examples of the (meth) acrylic acid derivative include: hydroxyalkyl (meth) acrylates such as 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, and 12-hydroxylauryl (meth) acrylate, and hydroxyl group-containing (meth) acrylates such as [4- (hydroxymethyl) cyclohexyl ] methyl acrylate, cyclohexanedimethanol mono (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate;

epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether;

halogen-containing (meth) acrylates such as 2, 2, 2-trifluoroethyl (meth) acrylate, 2, 2, 2-trifluoroethylethyl (meth) acrylate, 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;

oxetanyl-containing (meth) acrylates such as 3-oxetanyl (meth) acrylate, 3-methyl-oxetanyl (meth) acrylate, 3-ethyl-oxetanyl (meth) acrylate, 3-butyl-oxetanyl (meth) acrylate and 3-hexyl-oxetanyl (meth) acrylate;

and (meth) acrylates having a heterocyclic ring such as tetrahydrofurfuryl (meth) acrylate and butyrolactone (meth) acrylate, and hydroxypivalic acid neopentyl glycol (meth) acrylic acid adducts and p-phenylphenol (meth) acrylate.

Further, examples of the monofunctional radical polymerizable compound include: carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Examples of the monofunctional radical polymerizable compound include: lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam, and methyl vinylpyrrolidone; vinyl monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

As the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. The radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth) acryloyl group at a terminal or in a molecule and having an active methylene group. Examples of the active methylene group include: acetoacetyl, alkoxymalonyl, cyanoacetyl, or the like. The active methylene group is preferably an acetoacetyl group. Specific examples of the radical polymerizable compound 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-ethoxymalonyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetyloxybutyl) acrylamide, N- (4-acetoacetoxymethylbenzyl) acrylamide, N- (2-acetoacetylaminoethyl) acrylamide and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth) acrylate.

Polyfunctional radical polymerizable Compound

Further, examples of the bifunctional or higher polyfunctional radical polymerizable compound include: 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-butylpropanediol di (meth) acrylate, bisphenol A ethylene oxide adduct di (meth) acrylate, bisphenol A propylene oxide adduct di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, dioxane glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, propylene glycol di (meth) acrylate, esters of (meth) acrylic acid and a polyol such as pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and EO-modified diglycerol tetra (meth) acrylate, and 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene. Specific examples thereof include: aronix M-220, M-306 (manufactured by Toyo chemical Co., Ltd.), Light Acrylate 1, 9ND-A (manufactured by Kyoho chemical Co., Ltd.), Light Acrylate DGE-4A (manufactured by Kyoho chemical Co., Ltd.), Light Acrylate DCP-A (manufactured by Kyoho chemical Co., Ltd.), SR-531 (manufactured by Sartomer Co., Ltd.), CD-536 (manufactured by Sartomer Co., Ltd.), and the like. Further, as necessary, there may be enumerated: various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, or various (meth) acrylate monomers, and the like.

The radical polymerizable compound preferably contains the multifunctional radical polymerizable compound in order to control the water absorption of the cured product and to satisfy the optical durability of the polarizing film in a severe humidified environment. Among the above polyfunctional radical polymerizable compounds, radical polymerizable compounds having a high logPow value are preferable. The logPow value of the radical polymerizable compound is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more.

Examples of the radical polymerizable compound having a high logPow value include: alicyclic (meth) acrylates such as tricyclodecane dimethanol di (meth) acrylate (logPow ═ 3.05), isobornyl (meth) acrylate (logPow ═ 3.27), and the like;

long-chain aliphatic (meth) acrylates such as 1, 9-nonanediol di (meth) acrylate (logPow ═ 3.68), 1, 10-decanediol diacrylate (logPow ═ 4.10);

multi-branched (meth) acrylates such as hydroxypivalic acid neopentyl glycol (meth) acrylic acid adduct (logPow ═ 3.35) and 2-ethyl-2-butylpropanediol di (meth) acrylate (logPow ═ 3.92);

aromatic ring-containing (meth) acrylates such as bisphenol a di (meth) acrylate (logPow ═ 5.46), bisphenol a ethylene oxide 4 mol adduct di (meth) acrylate (logPow ═ 5.15), bisphenol a propylene oxide 2 mol adduct di (meth) acrylate (logPow ═ 6.10), bisphenol a propylene oxide 4 mol adduct di (meth) acrylate (logPow ═ 6.43), 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene (logPow ═ 7.48), and p-phenylphenol (meth) acrylate (logPow ═ 3.98); and the like.

The radical polymerizable compound is preferably used in combination with a monofunctional radical polymerizable compound from the viewpoint of having both adhesiveness to a polarizing plate and various transparent protective films and optical durability under severe environments. In general, it is preferable to use 3 to 80 wt% of the monofunctional radical polymerizable compound and 20 to 97 wt% of the polyfunctional radical polymerizable compound in combination with each other based on 100 wt% of the radical polymerizable compound.

< form of radical polymerization curing adhesive >

The curable adhesive for a polarizing film of the present invention can be used as an active energy ray-curable adhesive when the curable component is used in the form of an active energy ray-curable component, and can be used as a thermosetting adhesive when the curable component is used in the form of a thermosetting component. The active energy ray-curable adhesive does not need to contain a photopolymerization initiator when an electron beam or the like is used as an active energy ray, but preferably contains a photopolymerization initiator when ultraviolet light or visible light is used as an active energy ray. On the other hand, when the curable component of the adhesive is used as a thermosetting component, the adhesive preferably contains a thermal polymerization initiator.

Photopolymerization initiator

The photopolymerization initiator in the case of using a radical polymerizable compound can be appropriately selected depending on the active energy ray. When curing is performed by ultraviolet light or visible light, a photopolymerization initiator that is cleaved by ultraviolet light or visible light is used. Examples of the photopolymerization initiator include: benzophenone-based compounds such as benzil, benzophenone, benzoylbenzoic acid, and 3, 3' -dimethyl-4-methoxybenzophenone; 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 -hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [4- (methylthio) -phenyl ] -2-morpholinopropan-1-one; benzoin ether-based compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; optically active oxime compounds such as 1-phenyl-1, 1-propanedione-2- (O-ethoxycarbonyl) oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone and dodecylthioxanthone; camphorquinone; a halogenated ketone; an acylphosphine oxide; acyl phosphonates and the like. Among the photopolymerization initiators, those having a high logPow value are preferable. The curable adhesive for polarizing films contains no photopolymerization initiator in the calculation of the logPow value, but the logPow value of the photopolymerization initiator is preferably 1 or more, more preferably 2 or more, and most preferably 3 or more.

The amount of the photopolymerization initiator is 20 parts by weight or less based on 100 parts by weight of the total amount of the curable components (radical polymerizable compounds). The amount of the photopolymerization initiator is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, and still more preferably 0.1 to 5 parts by weight.

When the curable adhesive for a polarizing film of the present invention is used in the form of a visible light curable adhesive containing a radical polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more. A photopolymerization initiator having high sensitivity to light of 380nm or more will be described later.

As the photopolymerization initiator, it is preferable to use a compound represented by the following general formula (1) alone

[ solution 1]

(in the formula, R¹And R²represents-H, -CH₂CH₃-iPr or Cl, R¹And R²The same or different) or a combination of the compound represented by the general formula (1) and a photopolymerization initiator having high sensitivity to light of 380nm or more, which will be described later. The compound represented by the general formula (1) is more excellent in adhesion than a photopolymerization initiator having high sensitivity to light of 380nm or more is used alone. Among the compounds represented by the general formula (1), R is particularly preferable¹And R²is-CH₂CH₃Diethyl thioxanthone (ll). The composition ratio of the compound represented by the general formula (1) in the adhesive is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and still more preferably 0.9 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components.

Further, it is preferable to add a polymerization initiation aid 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 preferable. When the polymerization initiator is used, the amount thereof to be added is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components.

If necessary, a known photopolymerization initiator may be used in combination. Since a transparent protective film having UV absorption ability does not transmit light of 380nm or less, a photopolymerization initiator having high sensitivity to light of 380nm or more is preferably used as the photopolymerization initiator. Specifically, there may be mentioned: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholinyl) phenyl ] -1-butanone, 2, 4, 6-trimethylbenzoyl-diphenylphosphine oxide, bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide, bis (. eta.5-2, 4-cyclopentadien-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, and the like.

In particular, as the photopolymerization initiator, in addition to the photopolymerization initiator of the general formula (1), a compound represented by the following general formula (2);

[ solution 2]

(in the formula, R³、R⁴And R⁵represents-H, -CH₃、-CH₂CH₃-iPr or Cl, R³、R⁴And R⁵May be the same or different). As the compound represented by the general formula (2), commercially available 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE907 manufacturer: BASF) can be suitably used. In addition thereto, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (trade name: IRGACURE369 manufacturer: BASF), 2- (dimethylamino) -2- [ (4-methylphenyl) methyl group]-1- [4- (4-morpholinyl) phenyl]-1-butanone (trade name: IRGACURE379 manufacturer: BASF) is highly sensitive and preferred.

< radically polymerizable Compound (a1) having active methylene group and radically polymerizable initiator (a2) having dehydrogenation function >

In the active energy ray-curable adhesive, when the radical polymerizable compound (a1) having an active methylene group is used as the radical polymerizable compound, it is preferable to use it in combination with the radical polymerization initiator (a2) having a dehydrogenation function. According to this configuration, the adhesiveness of the adhesive layer of the polarizing film is remarkably improved particularly immediately after the polarizing film is taken out from a high-humidity environment or water (in an undried state). The reason is not clear, but is considered as follows. That is, the radical polymerizable compound (a1) having an active methylene group is polymerized together with other radical polymerizable compounds constituting the adhesive layer, and is incorporated into the main chain and/or side chain of the base polymer in the adhesive layer to form the adhesive layer. In this polymerization process, when the radical polymerization initiator (a2) having a dehydrogenation function is present, hydrogen is removed from the radical polymerizable compound (a2) having an active methylene group while forming the base polymer constituting the adhesive layer, and a radical is generated in the methylene group. Then, the methylene group having generated the radical reacts with a hydroxyl group of the polarizing plate such as PVA, and a covalent bond is formed between the adhesive layer and the polarizing plate. As a result, it is presumed that the adhesiveness of the adhesive layer of the polarizing film is remarkably improved particularly in the non-dried state.

In the present invention, examples of the radical polymerization initiator (a2) having a dehydrogenation function include a thioxanthone-based radical polymerization initiator and a benzophenone-based radical polymerization initiator. The radical polymerization initiator (a2) is preferably a thioxanthone radical polymerization initiator. Examples of the thioxanthone-based radical polymerization initiator include compounds represented by the above general formula (1). Specific examples of the compound represented by the general formula (1) include thioxanthone, dimethylthioxanthone, diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and the like. Among the compounds represented by the general formula (1), R is particularly preferable¹And R²is-CH₂CH₃Diethyl thioxanthone (ll).

When the active energy ray-curable adhesive contains the radical polymerizable compound (a1) having an active methylene group and the radical polymerization initiator (a2) having a dehydrogenation function, the total amount of the curable components is preferably 100% by weight: the curable composition contains 1 to 50 wt% of the above radical polymerizable compound (a1) having an active methylene group and 0.1 to 10 parts by weight of a radical polymerization initiator (a2) relative to 100 parts by weight of the total amount of the curable components.

As described above, in the present invention, in the presence of the radical polymerization initiator (a2) having a dehydrogenation function, the methylene group of the radical polymerizable compound (a1) having an active methylene group, which reacts with the hydroxyl group of the polarizing plate such as PVA to form a covalent bond, is caused to generate a radical. Therefore, in order to generate radicals from the methylene group of the radical polymerizable compound (a1) having an active methylene group and to form the covalent bond sufficiently, it is preferable that the radical polymerizable compound (a1) having an active methylene group is contained in an amount of 1 to 50% by weight, and more preferably, the radical polymerizable compound (a1) having an active methylene group is contained in an amount of 3 to 30% by weight, based on 100% by weight of the total amount of the curable components. In order to sufficiently improve the water resistance and improve the adhesion in a non-dried state, it is preferable that the radical polymerizable compound (a1) having an active methylene group is 1% by weight or more. On the other hand, if it exceeds 50 wt%, curing failure of the adhesive layer may occur. The radical polymerization initiator (a2) having a dehydrogenation function is preferably contained in an amount of 0.1 to 10 parts by weight, more preferably 0.3 to 9 parts by weight, based on 100 parts by weight of the total amount of the curable components. In order to sufficiently progress the dehydrogenation reaction, it is preferable to use 0.1 part by weight or more of the radical polymerization initiator (a 2). On the other hand, if it exceeds 10 parts by weight, the adhesive may not be completely dissolved.

Thermal polymerization initiator

The thermal polymerization initiator is preferably a thermal polymerization initiator that does not initiate polymerization by thermal cracking when the adhesive layer is formed. For example, the thermal polymerization initiator has a 10-hour half-life temperature of 65 ℃ or more, and more preferably 75 to 90 ℃. The half-life is an index indicating the decomposition rate of the polymerization initiator, and means the time until the residual amount of the polymerization initiator becomes half. The decomposition temperature for obtaining the half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in, for example, the manufacturer catalog, for example, "organic peroxide catalog" 9 th edition (5 months 2003) "of japan fat and oil co.

Examples of the thermal polymerization initiator include: lauroyl peroxide (10-hour half-life temperature: 64 ℃ C.), benzoyl peroxide (10-hour half-life temperature: 73 ℃ C.), 1-bis (t-butylperoxy) -3, 3, 5-trimethylcyclohexane (10-hour half-life temperature: 90 ℃ C.), bis (2-ethylhexyl) peroxydicarbonate (10-hour half-life temperature: 49 ℃ C.), bis (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate (10-hour half-life temperature: 51 ℃ C.), t-butyl peroxyneodecanoate (10-hour half-life temperature: 48 ℃ C.), t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide (10-hour half-life temperature: 64 ℃ C.), di-n-octanoyl peroxide, 1, 3, 3-tetramethylbutylperoxy-2-ethylhexanoate (10-hour half-life temperature: 66 ℃ C.), lauroyl peroxide, Organic peroxides such as bis (4-methylbenzoyl) peroxide, dibenzoyl peroxide (10-hour half-life temperature: 73 ℃), tert-butyl peroxyisobutyrate (10-hour half-life temperature: 81 ℃), and 1, 1-bis (tert-hexyl peroxyl) cyclohexane.

Examples of the thermal polymerization initiator include: azo compounds such as 2, 2 '-azobisisobutyronitrile (10-hour half-life temperature: 67 ℃), 2' -azobis (2-methylbutyronitrile) (10-hour half-life temperature: 67 ℃), and 1, 1-azobiscyclohexane-1-carbonitrile (10-hour half-life temperature: 87 ℃).

The amount of the thermal polymerization initiator is 0.01 to 20 parts by weight based on 100 parts by weight of the total amount of the curable components (radical polymerizable compounds). The amount of the thermal polymerization initiator is further 0.05 to 10 parts by weight, and more preferably 0.1 to 3 parts by weight.

< 2: cationic polymerization curing adhesive >

Examples of the curable component of the cationic polymerization curable adhesive include compounds having an epoxy group and an oxetane group. The compound having an epoxy group is not particularly limited as long as it has at least 2 epoxy groups in the molecule, and various curable epoxy compounds generally known can be used. Preferred epoxy compounds include, for example: a compound having at least 2 epoxy groups and at least 1 aromatic ring in the molecule (aromatic epoxy compound), a compound having at least 2 epoxy groups in the molecule, at least 1 of which is formed between adjacent 2 carbon atoms constituting an alicyclic ring (alicyclic epoxy compound), and the like.

< cationic photopolymerization initiator >

The cationic polymerization curable adhesive contains the above-described epoxy compound and oxetane compound as curable components, and both are cured by cationic polymerization and thus a photo cationic polymerization initiator is blended. The photo cation polymerization initiator generates a cation species or lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, etc., and initiates polymerization of an epoxy group or an oxetanyl group.

< other ingredients >

The curable adhesive of the present invention preferably contains the following components.

< acrylic oligomer (A) >

The active energy ray-curable adhesive of the present invention may contain an acrylic oligomer (a) obtained by polymerizing a (meth) acrylic monomer, in addition to the curable component of the radical polymerizable compound. When the active energy ray-curable adhesive contains the acrylic oligomer (a), the curing shrinkage when the adhesive is cured by irradiation with an active energy ray can be reduced, and the interface stress between the adhesive and an adherend such as a polarizing plate or a transparent protective film can be reduced. As a result, the decrease in adhesiveness between the adhesive layer and the adherend can be suppressed. In order to sufficiently suppress the curing shrinkage of the cured product layer (adhesive layer), the content of the acrylic oligomer (a) is preferably 20 parts by weight or less, and more preferably 15 parts by weight or less, relative to 100 parts by weight of the total amount of the curable components. If the content of the acrylic oligomer (a) in the adhesive is too large, the reaction rate when the adhesive is irradiated with an active energy ray is drastically reduced, and curing failure may occur. On the other hand, the acrylic oligomer (A) is preferably contained in an amount of 3 parts by weight or more, more preferably 5 parts by weight or more, based on 100 parts by weight of the total amount of the dry curable components.

The active energy ray-curable adhesive is preferably low in viscosity in consideration of workability and uniformity at the time of application, and therefore the acrylic oligomer (a) obtained by polymerizing a (meth) acrylic monomer is also preferably low in viscosity. The acrylic oligomer having a low viscosity and capable of preventing curing shrinkage of the adhesive layer preferably has a weight average molecular weight (Mw) of 15000 or less, more preferably 10000 or less, and particularly preferably 5000 or less. On the other hand, in order to sufficiently suppress the curing shrinkage of the cured product layer (adhesive layer), the weight average molecular weight (Mw) of the acrylic oligomer (a) is preferably 500 or more, more preferably 1000 or more, and particularly preferably 1500 or more. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer (a) include: (meth) acrylic acid (C1-20) alkyl esters 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, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 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, And, for example, 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-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, etc.), hydroxyl group-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropylmethyl-butyl (meth) acrylate, etc.), alkoxy group-or phenoxy group-containing (meth) acrylates ((2-methoxyethyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and the like), epoxy group-containing (meth) acrylates (for example, glycidyl (meth) acrylate, etc.), halogen-containing (meth) acrylates (e.g., 2, 2, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.), etc. These (meth) acrylates may be used alone or in combination of two or more. Specific examples of the acrylic oligomer (A) include "ARUFON" manufactured by Toyo Synthesis, "ACTFLOW" manufactured by Sudoku chemical Co., Ltd., and "JONCRYL" manufactured by BASF Japan. The acrylic oligomer (a) obtained by polymerizing a (meth) acrylic monomer preferably has a high logPow value. The acrylic oligomer (a) is contained as a component for calculating the logPow value of the curable adhesive for polarizing films. In the calculation of the logPow value, the number of moles of the component of the acrylic oligomer (a) is calculated as the number of moles of the (meth) acrylic monomer constituting the acrylic oligomer (a). The logPow value of the acrylic oligomer (a) obtained by polymerizing a (meth) acrylic monomer is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more.

< photoacid Generator (B) >

The active energy ray-curable adhesive may contain a photoacid generator (B). When the photoacid generator is contained in the active energy ray-curable adhesive, the water resistance and durability of the adhesive layer can be dramatically improved as compared with the case where the photoacid generator is not contained. The photoacid generator (B) can be represented by the following general formula (3).

General formula (3)

[ solution 3]

(wherein, L⁺Represents an arbitrary onium cation. In addition, X^-Representing a selection from PF6₆ ^-、SbF₆ ^-、AsF₆ ^-、SbCl₆ ^-、BiCl₅ ^-、SnCl₆ ^-、ClO₄ ^-Dithiocarbamate anions, SCN-counter anions of the group)

As to the onium cation L preferred as constituting general formula (3)⁺The structure of the onium cation in (2) may be an onium cation selected from the group consisting of the following general formulae (4) to (12).

General formula (4)

[ solution 4]

General formula (5)

[ solution 5]

General formula (6)

[ solution 6]

General formula (7)

[ solution 7]

General formula (8)

[ solution 8]

General formula (9)

[ solution 9]

General formula (10)

[ solution 10]

General formula (11)

[ solution 11]

General formula (12)

[ solution 12]

Ar⁴-I⁺-Ar⁵

(in the above general formulae (4) to (12), wherein R¹、R²And R³Each independently represents a group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heterocyclic oxy group, a substituted or unsubstituted acyl group, a substituted or unsubstituted carbonyloxy group, a substituted or unsubstituted oxycarbonyl group, or a halogen atom. R⁴Is represented by the formula¹、R²And R³The same groups as those described in (1). R⁵Represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylthio group. R⁶And R⁷Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group. R represents a halogen atom, a hydroxyl group, a carboxyl group, a mercapto group, a cyano group, a nitro group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl groupAny one of substituted or unsubstituted aryl, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, substituted or unsubstituted heterocyclic oxy, substituted or unsubstituted alkylthio, substituted or unsubstituted arylthio, substituted or unsubstituted heterocyclic thio, substituted or unsubstituted acyl, substituted or unsubstituted carbonyloxy, and substituted or unsubstituted oxycarbonyl. Ar (Ar)⁴、Ar⁵Represents any one of a substituted or unsubstituted aryl group and a substituted or unsubstituted heterocyclic group. X represents an oxygen or sulfur atom. i represents an integer of 0 to 5. j represents an integer of 0 to 4. k represents an integer of 0 to 3. In addition, may be between adjacent R, Ar⁴And Ar⁵、R²And R³、R²And R⁴、R³And R⁴、R¹And R²、R¹And R³、R¹And R⁴、R¹And R, or R¹And R⁵And a ring structure formed by bonding the two structures. )

Examples of onium cations (sulfonium cations) corresponding to the general formula (4) are:

dimethylphenylsulfonium, dimethyl (o-fluorophenyl) sulfonium, dimethyl (m-chlorophenyl) sulfonium, dimethyl (p-bromophenyl) sulfonium, dimethyl (p-cyanophenyl) sulfonium, dimethyl (m-nitrophenyl) sulfonium, dimethyl (2, 4, 6-tribromophenyl) sulfonium, dimethyl (pentafluorophenyl) sulfonium, dimethyl (p-trifluoromethyl) phenyl) sulfonium, dimethyl (p-hydroxyphenyl) sulfonium, dimethyl (p-mercaptophenyl) sulfonium, dimethyl (p-methylsulfinylphenyl) sulfonium, dimethyl (p-methylsulfonylphenyl) sulfonium, dimethyl (o-acetylphenyl) sulfonium, dimethyl (o-benzoylphenyl) sulfonium, dimethyl (p-methylphenyl) sulfonium, dimethyl (p-isopropylphenyl) sulfonium, dimethyl (p-octadecylphenyl) sulfonium, dimethyl (p-cyclohexylphenyl) sulfonium, dimethyl (p-methoxyphenyl) sulfonium, Dimethyl (o-methoxycarbonylphenyl) sulfonium, dimethyl (p-phenylsulfanylphenyl) sulfonium, (7-methoxy-2-oxo-2H-benzopyran-4-yl) dimethylsulfonium, (4-methoxynaphthalene-1-yl) dimethylsulfonium, dimethyl (p-isopropoxycarbonylphenyl) sulfonium, dimethyl (2-naphthyl) sulfonium, dimethyl (9-anthryl) sulfonium, diethylphenyl sulfonium, methylethylphenyl sulfonium, methyldiphenyl sulfonium, triphenylsulfonium, diisopropylphenyl sulfonium, diphenyl (4-phenylthio-phenyl) -sulfonium, 4 '-bis (diphenylsulfonium) diphenylsulfide, 4' -bis [ (4- (2-hydroxy-ethoxy) -phenyl) ] sulfonium ] ] diphenylsulfide, sulfur, 4, 4' -bis (diphenylsulfonium) biphenylene, diphenyl (o-fluorophenyl) sulfonium, diphenyl (m-chlorophenyl) sulfonium, diphenyl (p-bromophenyl) sulfonium, diphenyl (p-cyanophenyl) sulfonium, diphenyl (m-nitrophenyl) sulfonium, diphenyl (2, 4, 6-tribromophenyl) sulfonium, diphenyl (pentafluorophenyl) sulfonium, diphenyl (p-trifluoromethyl) phenyl) sulfonium, diphenyl (p-hydroxyphenyl) sulfonium, diphenyl (p-mercaptophenyl) sulfonium, diphenyl (p-methylsulfinylphenyl) sulfonium, diphenyl (p-methylsulfonylphenyl) sulfonium, diphenyl (o-acetylphenyl) sulfonium, diphenyl (o-benzoylphenyl) sulfonium, diphenyl (p-methylphenyl) sulfonium, diphenyl (p-isopropylphenyl) sulfonium, diphenyl (p-octadecylphenyl) sulfonium, diphenyl (p-cyclohexylphenyl) sulfonium, diphenyl (p-methoxyphenyl) sulfonium, Diphenyl (o-methoxycarbonylphenyl) sulfonium, diphenyl (p-phenylsulfanylphenyl) sulfonium, (7-methoxy-2-oxo-2H-benzopyran-4-yl) diphenylsulfonium, (4-methoxynaphthalen-1-yl) diphenylsulfonium, diphenyl (p-isopropoxycarbonylphenyl) sulfonium, diphenyl (2-naphthyl) sulfonium, diphenyl (9-anthryl) sulfonium, ethyldiphenylsulfonium, methylethyl (o-tolyl) sulfonium, methyldi (p-tolyl) sulfonium, tri (p-tolyl) sulfonium, diisopropyl (4-phenylthiophenyl) sulfonium, diphenyl (2-thienyl) sulfonium, diphenyl (2-furyl) sulfonium, diphenyl (9-ethyl-9H-carbazol-3-yl) sulfonium, and the like, but are not limited thereto.

Examples of onium cations (sulfoxonium cations) corresponding to the general formula (5) are:

dimethylphenylsulfonium oxide, dimethyl (o-fluorophenyl) sulfonium oxide, dimethyl (m-chlorophenyl) sulfonium oxide, dimethyl (p-bromophenyl) sulfonium oxide, dimethyl (p-cyanophenyl) sulfonium oxide, dimethyl (m-nitrophenyl) sulfonium oxide, dimethyl (2, 4, 6-tribromophenyl) sulfonium oxide, dimethyl (pentafluorophenyl) sulfonium oxide, dimethyl (p-trifluoromethyl) phenyl sulfonium oxide, dimethyl (p-hydroxyphenyl) sulfonium oxide, dimethyl (p-mercaptophenyl) sulfonium oxide, dimethyl (p-methylsulfinylphenyl) sulfonium oxide, dimethyl (p-methylsulfonylphenyl) sulfonium oxide, dimethyl (o-acetylphenyl) sulfonium oxide, dimethyl (o-benzoylphenyl) sulfonium oxide, dimethyl (p-methylphenyl) sulfonium oxide, dimethyl (p-isopropylphenyl) sulfonium oxide, dimethyl (p-octadecylphenyl) sulfonium oxide, Dimethyl (p-cyclohexylphenyl) sulfoxonium, dimethyl (p-methoxyphenyl) sulfoxonium, dimethyl (o-methoxycarbonylphenyl) sulfoxonium, dimethyl (p-phenylsulfanylphenyl) sulfoxonium, (7-methoxy-2-oxo-2H-benzopyran-4-yl) dimethylsulfoxonium, (4-methoxynaphthalene-1-yl) dimethylsulfoxonium, dimethyl (p-isopropoxycarbonylphenyl) sulfoxonium, dimethyl (2-naphthyl) sulfoxonium, dimethyl (9-anthryl) sulfoxonium, diethylphenyl sulfoxonium, methylethylphenyl sulfoxonium, methyldiphenylsulfoxonium, triphenylsulfoxonium, diisopropylphenyl sulfoxonium, diphenyl (4-phenylthio-phenyl) -sulfoxonium, 4' -bis (diphenylsulfoxonium) diphenylsulfide, 4, 4 '-bis [ (4- (2-hydroxy-ethoxy) -phenyl) ] sulfoxonium ] diphenylsulfide, 4' -bis (diphenylsulfoxonium) biphenylene, diphenyl (o-fluorophenyl) sulfoxonium, diphenyl (m-chlorophenyl) sulfoxonium, diphenyl (p-bromophenyl) sulfoxonium, diphenyl (p-cyanophenyl) sulfoxonium, diphenyl (m-nitrophenyl) sulfoxonium, diphenyl (2, 4, 6-tribromophenyl) sulfoxonium, diphenyl (pentafluorophenyl) sulfoxonium, diphenyl (p-trifluoromethyl) phenyl) sulfoxonium, diphenyl (p-hydroxyphenyl) sulfoxonium, diphenyl (p-mercaptophenyl) sulfoxonium, diphenyl (p-methylsulfinylphenyl) sulfoxonium, diphenyl (p-methylsulfonylphenyl) sulfoxonium, diphenyl (o-acetylphenyl) sulfoxonium, diphenyl (p-nitrophenyl) sulfoxonium), Diphenyl (o-benzoylphenyl) sulfoxonium, diphenyl (p-methylphenyl) sulfoxonium, diphenyl (p-isopropylphenyl) sulfoxonium, diphenyl (p-octadecylphenyl) sulfoxonium, diphenyl (p-cyclohexylphenyl) sulfoxonium, diphenyl (p-methoxyphenyl) sulfoxonium, diphenyl (o-methoxycarbonylphenyl) sulfoxonium, diphenyl (p-phenylsulfanylphenyl) sulfoxonium, (7-methoxy-2-oxo-2H-benzopyran-4-yl) diphenylsulfoxonium, (4-methoxynaphthalen-1-yl) diphenylsulfoxonium, diphenyl (p-isopropoxycarbonylphenyl) sulfoxonium, diphenyl (2-naphthyl) sulfoxonium, diphenyl (9-anthracenyl) sulfoxonium, ethyldiphenylsulfoxonium, methylethyl (o-tolyl) sulfoxonium, thionylphosphonium, diphenyliodonium, or their salts, Methyldi (p-tolyl) sulfoxonium, tris (p-tolyl) sulfoxonium, diisopropyl (4-phenylthiophenyl) sulfoxonium, diphenyl (2-thienyl) sulfoxonium, diphenyl (2-furyl) sulfoxonium, diphenyl (9-ethyl-9H carbazol-3-yl) sulfoxonium, and the like, but are not limited thereto.

Examples of phosphonium cations which may be mentioned are the onium cations corresponding to the general formula (6):

trimethylphenylphosphonium, triethylphenylphosphonium, tetraphenylphosphonium, triphenyl (p-fluorophenyl) phosphonium, triphenyl (o-chlorophenyl) phosphonium, triphenyl (m-bromophenyl) phosphonium, triphenyl (p-cyanophenyl) phosphonium, triphenyl (m-nitrophenyl) phosphonium, triphenyl (p-phenylphenylthio) phosphonium, (7-methoxy-2-oxo-2H-benzopyran-4-yl) triphenylphosphonium, triphenyl (o-hydroxyphenyl) phosphonium, triphenyl (o-acetylphenyl) phosphonium, triphenyl (m-benzoylphenyl) phosphonium, triphenyl (p-methylphenyl) phosphonium, triphenyl (p-isopropoxyphenyl) phosphonium, triphenyl (o-methoxycarbonylphenyl) phosphonium, triphenyl (1-naphthyl) phosphonium, triphenyl (9-anthracenyl) phosphonium, triphenyl (2-thienyl) phosphonium, triphenyl (2-furyl) phosphonium, triphenyl (p-isopropoxyphenyl) phosphonium, triphenyl (o-methoxycarbonylphenyl) phosphonium, triphenyl (1-naphthyl) phosphonium, triphenyl (9-anthracenyl) phosphonium, triphenyl (9-thienyl) phosphonium, triphenyl (2, Triphenyl (9-ethyl-9H-carbazol-3-yl) phosphonium, and the like, but is not limited thereto.

Examples of onium cations (pyridinium cations) corresponding to formula (7) include pyridinium cations:

n-phenylpyridinium, N- (o-chlorophenyl) pyridinium, N- (m-chlorophenyl) pyridinium, N- (p-cyanophenyl) pyridinium, N- (o-nitrophenyl) pyridinium, N- (p-acetylphenyl) pyridinium, N- (p-isopropylphenyl) pyridinium, N- (p-octadecyloxyphenyl) pyridinium, N- (p-methoxycarbonylphenyl) pyridinium, N- (9-anthryl) pyridinium, 2-chloro-1-phenylpyridinium, 2-cyano-1-phenylpyridinium, 2-methyl-1-phenylpyridinium, 2-vinyl-1-phenylpyridinium, 2-phenyl-1-phenylpyridinium, 1, 2-diphenylpyridinium, N- (p-cyanophenyl) pyridinium, N- (o-nitrophenyl) pyridinium, N- (p-acetylphenyl) pyridinium, N- (p-isopropylphenyl) pyridinium, N- (p-octadecyloxyphenyl) pyridinium, 2-methoxy-1-phenylpyridinium, 2-phenoxy-1-phenylpyridinium, 2-acetyl-1- (p-tolyl) pyridinium, 2-methoxycarbonyl-1- (p-tolyl) pyridinium, 3-fluoro-1-naphthylpyridinium, 4-methyl-1- (2-furyl) pyridinium, N-methylpyridinium, N-ethylpyridinium and the like, but are not limited thereto.

Examples of onium cations (quinolinium cations) corresponding to formula (8) include quinolinium cations:

n-methylquinolinium, N-ethylquinolinium, N-phenylquinolinium, N-naphthylquinolinium, N- (o-chlorophenyl) quinolinium, N- (m-chlorophenyl) quinolinium, N- (p-cyanophenyl) quinolinium, N- (o-nitrophenyl) quinolinium, N- (p-acetylphenyl) quinolinium, N- (p-isopropylphenyl) quinolinium, N- (p-octadecyloxyphenyl) quinolinium, N- (p-methoxycarbonylphenyl) quinolinium, N- (9-anthryl) quinolinium, 2-chloro-1-phenylquinolinium, 2-cyano-1-phenylquinolinium, 2-methyl-1-phenylquinolinium, 2-vinyl-1-phenylquinolinium, N- (p-chlorophenyl) quinolinium, N- (p-nitrophenyl) quinolinium, N- (p-acetylphenyl) quinolinium, N- (p-isopropylphenyl) quinolinium, 2-phenyl-1-phenylquinolinium, 1, 2-diphenylquinolinium, 2-methoxy-1-phenylquinolinium, 2-phenoxy-1-phenylquinolinium, 2-acetyl-1-phenylquinolinium, 2-methoxycarbonyl-1-phenylquinolinium, 3-fluoro-1-phenylquinolinium, 4-methyl-1-phenylquinolinium, 2-methoxy-1- (p-tolyl) quinolinium, 2-phenoxy-1- (2-furyl) quinolinium, 2-acetyl-1- (2-thienyl) quinolinium, 2-methoxycarbonyl-1-methylquinolinium, 3-fluoro-1-ethylquinolinium, 2-phenylquinolinium, 2-phenylquinolin, 4-methyl-1-isopropylquinolinium, and the like, but is not limited thereto.

Examples of onium cations (isoquinolinium cations) corresponding to general formula (9) include isoquinolinium cations:

n-phenylisoquinolinium, N-methylisoquinolinium, N-ethylisoquinolinium, N- (o-chlorophenyl) isoquinolinium, N- (m-chlorophenyl) isoquinolinium, N- (p-cyanophenyl) isoquinolinium, N- (o-nitrophenyl) isoquinolinium, N- (p-acetylphenyl) isoquinolinium, N- (p-isopropylphenyl) isoquinolinium, N- (p-octadecyloxyphenyl) isoquinolinium, N- (p-methoxycarbonylphenyl) isoquinolinium, N- (9-anthryl) isoquinolinium, 1, 2-diphenylisoquinolinium, N- (2-furyl) isoquinolinium, N- (2-thienyl) isoquinolinium, N-naphthylisoquinolinium and the like, but are not limited thereto.

Examples of onium cations (benzoxazolium cations, benzothiazolium cations) corresponding to general formula (10) include benzoxazolium cations:

n-methylbenzoxazolium, N-ethylbenzoxazolium, N-naphthylbenzoxazolium, N-phenylbenzooxazolium, N- (p-fluorophenyl) benzoxazolium, N- (p-chlorophenyl) benzoxazolium, N- (p-cyanophenyl) benzoxazolium, N- (o-methoxycarbonylphenyl) benzoxazolium, N- (2-furyl) benzoxazolium, N- (o-fluorophenyl) benzoxazolium, N- (p-cyanophenyl) benzoxazolium, N- (m-nitrophenyl) benzoxazolium, N- (p-isopropoxycarbonylphenyl) benzoxazolium, N- (2-thienyl) benzoxazolium, N- (m-carboxyphenyl) benzoxazolium, 2-mercapto-3-phenylbenzoxazolium, N- (p-methoxycarbonylphenyl) benzoxazolium, 2-methyl-3-phenylbenzooxazolium, 2-methylthio-3- (4-phenylthiophenyl) benzoxazolium, 6-hydroxy-3- (p-tolyl) benzoxazolium, 7-mercapto-3-phenylbenzooxazolium, 4, 5-difluoro-3-ethylbenzoxazolium, and the like, but is not limited thereto.

Examples of benzothiazolium cations include:

n-methylbenzothiazolium, N-ethylbenzothiazolium, N-phenylbenzothiazolium, N- (1-naphthyl) benzothiazolium, N- (p-fluorophenyl) benzothiazolium, N- (p-chlorophenyl) benzothiazolium, N- (p-cyanophenyl) benzothiazolium, N- (o-methoxycarbonylphenyl) benzothiazolium, N- (p-tolyl) benzothiazolium, N- (o-fluorophenyl) benzothiazolium, N- (m-nitrophenyl) benzothiazolium, N- (p-isopropoxycarbonylphenyl) benzothiazolium, N- (2-furyl) benzothiazolium, N- (4-methylthiophenyl) benzothiazolium, N- (4-phenylthiophenyl) benzothiazolium, N- (2-naphthyl) benzothiazolium, N- (m-carboxyphenyl) benzothiazolium, 2-mercapto-3-phenylbenzothiazolium, 2-methyl-3-phenylbenzothiazolium, 2-methylthio-3-phenylbenzothiazolium, 6-hydroxy-3-phenylbenzothiazolium, 7-mercapto-3-phenylbenzothiazolium, 4, 5-difluoro-3-phenylbenzothiazolium, and the like, but are not limited thereto.

Mention may be made, as onium cations (furyl or thienyliodonium cations) corresponding to general formula (11):

difuryylium iodide, dithienylium iodide, bis (4, 5-dimethyl-2-furyl) iodonium, bis (5-chloro-2-thienyl) iodonium, bis (5-cyano-2-furyl) iodonium, bis (5-nitro-2-thienyl) iodonium, bis (5-acetyl-2-furyl) iodonium, bis (5-carboxy-2-thienyl) iodonium, bis (5-methoxycarbonyl-2-furyl) iodonium, bis (5-phenyl-2-furyl) iodonium, bis (5- (p-methoxyphenyl) -2-thienyl) iodonium, bis (5-vinyl-2-furyl) iodonium, bis (5-ethynyl-2-thienyl) iodonium, bis (4, 5-dimethyl-2-furyl) iodonium, bis (5-chloro-2-thienyl) iodonium, bis (5-nitro-2-thienyl) iodonium, bis (5-acetyl-2-furyl) iodonium, bis (5- (p-methoxyphenyl) -2, Bis (5-cyclohexyl-2-furyl) iodonium, bis (5-hydroxy-2-thienyl) iodonium, bis (5-phenoxy-2-furyl) iodonium, bis (5-mercapto-2-thienyl) iodonium, bis (5-butylthio-2-thienyl) iodonium, bis (5-phenylthio-2-thienyl) iodonium, and the like, but are not limited thereto.

Examples of onium cations (diaryliodonium cations) corresponding to general formula (12) include:

diphenyliodonium, bis (p-tolyl) iodonium, bis (p-octylphenyl) iodonium, bis (p-octadecylphenyl) iodonium, bis (p-octyloxyphenyl) iodonium, bis (p-octadecyloxyphenyl) iodonium, phenyl (p-octadecyloxyphenyl) iodonium, 4-isopropyl-4 '-methyldiphenyliodonium, (4-isobutylphenyl) -p-tolyliodonium, bis (1-naphthyl) iodonium, bis (4-phenylthiophenyl) iodonium, phenyl (6-benzoyl-9-ethyl-9H-carbazol-3-yl) iodonium, (7-methoxy-2-oxo-2H-benzopyran-3-yl) -4' -isopropylphenyliodonium, and the like, but are not limited thereto.

Next, the counter anion X-in the general formula (3) will be described.

The counter anion X "in the general formula (3) is not particularly limited in principle, but a non-nucleophilic anion is preferable. When the counter anion X "is a non-nucleophilic anion, a nucleophilic reaction of a cation coexisting in the molecule and various materials used in combination is less likely to occur, and as a result, the stability with time of the photoacid generator itself represented by the general formula (2) and an adhesive using the photoacid generator can be improved. The non-nucleophilic anion as used herein refers to an anion having a low ability to cause nucleophilic reaction. Examples of such anions include: PF (particle Filter)₆ ^-、SbF₆ ^-、AsF₆ ^-、SbCl₆ ^-、BiCl₅ ^-、SnCl₆ ^-、ClO₄ ^-Dithiocarbamate anion, SCN^-And the like.

Among the above-mentioned exemplary anions, X is a counter anion in the general formula (3)^-As a particularly preferred counter anion, PF can be mentioned₆ ^-、SbF₆ ^-And AsF₆ ^-Particularly preferred examples thereof include PF₆ ^-、SbF₆ ^-。

Accordingly, specific examples of preferred onium salts constituting the photoacid generator (B) include those having the structures of the onium cations represented by the above-exemplified general formulae (3) to (12) and those selected from PF₆ ^-、SbF₆ ^-、AsF₆ ^-、SbCl₆ ^-、BiCl₅ ^-、SnCl₆ ^-、ClO₄ ^-Dithiocarbamate anion, SCN^-An onium salt composed of the anion of (1).

Specifically, preferable examples of the photoacid generator (B) include "Cyracure UVI-6992", "Cyracure UVI-6974" (manufactured by Tao chemical Japan Co., Ltd., "" Adekaoptomer SP150 "," Adekaoptomer SP152 "," Adekaoptomer SP170 "," Adekaoptomer SP172 "(manufactured by ADEKA Co., Ltd.," "IRGACURE 250" (manufactured by Ciba refiner Co., Ltd.), "" CI-5102 "," CI-2855 "(manufactured by Nippon Cauda Co., Ltd.," "San-aid SI-60L", "San-aid-80L", "San-aid SI-100L", "San-aid SI-110L", "San-aid SI-180L" (manufactured by Sanxin chemical Co., Ltd., "" CPI-100P "," CPI-100A "(manufactured by Sanxin J., Ltd.," "WPI-069", "" WPI-180L ""), "WPI-113", "WPI-116", "WPI-041", "WPI-044", "WPI-054", "WPI-055", "WPAG-281", "WPAG-567" and "WPAG-596" (manufactured by Wako pure chemical industries, Ltd.).

The content of the photoacid generator (B) is 10 parts by weight or less, preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and particularly preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components.

< Compound (C) containing either alkoxy group or epoxy group >

The active energy ray-curable adhesive may contain a compound (C) containing either an alkoxy group or an epoxy group. For example, in the relation with the hydroxyl group of the PVA-based polarizing plate, the alkoxy group-containing compound (C1) undergoes a condensation reaction of the alkoxy group and the hydroxyl group, and the epoxy group-containing compound (C2) undergoes an addition reaction of the epoxy group and the hydroxyl group, whereby stronger adhesiveness can be imparted to the active energy ray-curable adhesive. When the compound containing an epoxy group (C2) is used, a secondary hydroxyl group is formed after the reaction by addition reaction of the epoxy group and the hydroxyl group, and the volume water absorption of the present invention may be increased, so that the compound having an alkoxy group (C1) is more preferably used. That is, the polarizing plate and the transparent protective film are laminated with an active energy ray-curable adhesive containing the photoacid generator (B) and the compound having an alkoxy group (C1), and the active energy ray is irradiated to generate an acid from the photoacid generator (B), and the acid causes a condensation reaction between the alkoxy group of the compound having an alkoxy group (C1) and the hydroxyl group of the polarizing plate, thereby exhibiting good adhesiveness between the polarizing plate and the transparent protective film. Further, an adhesive layer having a lower water absorption rate is formed by a condensation reaction between the compounds having an alkoxy group (C1), and thus optical durability under a severe environment at high temperature and high humidity can be satisfied.

In the active energy ray-curable adhesive, 1 kind of the compound (C) containing either an alkoxy group or an epoxy group may be used alone, or a plurality of kinds may be used in combination. Further, the compound (C) containing either an alkoxy group or an epoxy group may be used in combination with the alkoxy group-containing compound (C1) and the epoxy group-containing compound (C2). The compound (C) containing either an alkoxy group or an epoxy group may or may not be used in combination with the photoacid generator (B), but is preferably used in combination with the photoacid generator (B) from the viewpoint of promoting the reaction between the hydroxyl group and the alkoxy group or epoxy group of the PVA-based polarizing plate.

(Compound having alkoxy group (C1))

As in a moleculeThe compound (C1) having an alkoxy group is not particularly limited as long as it has 1 or more alkoxy groups in the molecule, and a known compound having an alkoxy group can be used. Examples thereof include: having the general formula: - (CH)₂)_nA compound having an alkoxy group represented by-O-R (wherein n is an integer of 1 to 3 and R represents an alkyl group having 1 to 4 carbon atoms or H, and R in the formula is preferably a methyl group) as a substituent. Specifically, examples thereof include: an alkoxy group-containing radical polymerizable compound such as alkoxyalkyl (meth) acrylate or alkoxyalkyl (meth) acrylamide, a melamine compound such as methylolmelamine or alkoxymethylated melamine, an amino resin, and a silane coupling agent. Specific examples of the alkoxy group-containing radical polymerizable compound include: ワスマー 2MA, ワスマー 3MA, ワスマ -IBM, N-isobutoxymethylacrylamide, ワスマ -EMA, N-MAM-PC, MM90, ワスマ -A manufactured by Chi-Yexing company, and the like. Specific examples of the melamine compound include M-3, MK, M-6, M-100 and MC of Sumitex resin series manufactured by Sumitomo chemical Co., Ltd, Nikalac MW-30, MW-100LM, MX-750LM, MX-280 and MX-270 manufactured by Kazala Kagaku K.K. Among them, ワスマー 2MA, N-MAM-PC, MX-750LM and the like are preferably used from the viewpoint of reactivity. When the glass transition temperature Tg of the adhesive layer was calculated, the compound having an alkoxy group and the polymer (C1) were not included in the calculation.

(Compound having epoxy group (C2))

As the compound having an epoxy group (C2), a compound having 1 or more epoxy groups in the molecule, or a polymer (epoxy resin) having 2 or more epoxy groups in the molecule can be used. When a polymer (epoxy resin) is used, a compound having 2 or more functional groups reactive with an epoxy group in a molecule may be used in combination. Here, examples of the functional group reactive with an epoxy group include: carboxyl group, phenolic hydroxyl group, mercapto group, primary or secondary aromatic amino group, and the like. In view of 3-dimensional curability, it is particularly preferable to have 2 or more of these functional groups in one molecule.

Examples of the polymer having 1 or more epoxy groups in the molecule include epoxy resins such as: 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, alicyclic epoxy resins, diphenyl ether type epoxy resins, hydroquinone type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, fluorene type epoxy resins, trifunctional type epoxy resins, tetrafunctional type epoxy resins and other polyfunctional epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, aliphatic chain epoxy resins and the like, and these epoxy resins may be halogenated or hydrogenated. Examples of commercially available epoxy resin products include: JER Coat (コ - ト)828, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000, Epiclon 830, EXA835LV, HP4032D, HP820, EP4100 series, EP4000 series, EPU series, Celloxide series (2021, 2021P, 2083, 2085, 3000, etc.) manufactured by ADEKA, Epolead series, EHPE series, YD series, YDF series, YDCN series, YDB series, phenoxy resins (polyhydroxy polyethers synthesized from bisphenols and epichlorohydrin and having epoxy groups at both ends; YP series, etc.) manufactured by Duncol chemical Co., Ltd, and Epilon series manufactured by Synigal chemical Co., Ltd, but not limited thereto. Two or more of these epoxy resins may be used in combination. When the glass transition temperature Tg of the adhesive layer was calculated, the compound having an epoxy group (C2) was not included in the calculation.

The amount of the compound (C) containing either an alkoxy group or an epoxy group is usually 30 parts by weight or less based on 100 parts by weight of the total amount of the curable components, and if the content of the compound (C) in the active energy ray-curable adhesive is too large, the adhesiveness may be reduced and the impact resistance in a drop test may be deteriorated. The content of the compound (C) in the active energy ray-curable adhesive is more preferably 20 parts by weight or less. On the other hand, the active energy ray-curable adhesive preferably contains the compound (C) in an amount of 2 parts by weight or more, more preferably 5 parts by weight or more, from the viewpoint of water resistance

< isocyanate Compound (D) >

The active energy ray-curable adhesive of the present invention may contain an isocyanate compound (D). The isocyanate compound (D) is a compound having at least 1 isocyanate group in the molecule. When the active energy ray-curable adhesive contains the isocyanate compound (D), the hydroxyl group and the isocyanate group on the surface of the polarizing plate interact with each other to provide stronger adhesiveness and water resistance to the polarizing film. When the active energy ray-curable adhesive contains an N-hydroxyalkyl-containing (meth) acrylamide derivative as a radical polymerizable compound, if the content of the N-hydroxyalkyl-containing (meth) acrylamide derivative is increased, the volume water absorption rate tends to be increased due to the hydroxyl group contained in the adhesive layer, and as a result, the optical durability tends to be lowered in a severe humid environment. By using a combination of an N-hydroxyalkyl-containing (meth) acrylamide derivative and an isocyanate group-containing compound, a urethane bond is formed between a hydroxyl group that does not contribute to adhesion to a polarizing plate and an isocyanate group, and the volume water absorption can be reduced while maintaining adhesion.

As the isocyanate compound (D), there can be mentioned: a polyfunctional isocyanate compound, an active energy ray-curable isocyanate compound, and the like. As the polyfunctional isocyanate compound, for example, there can be mentioned: lower aliphatic polyisocyanates such as 1, 2-ethylenediisocyanate, 1, 4-butylenediisocyanate and 1, 6-hexamethylenediisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated xylene diisocyanate; aromatic polyisocyanates such as 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4' -diphenylmethane diisocyanate and xylylene diisocyanate. Examples of the isocyanate compound (D) include: trimethylolpropane/tolylene diisocyanate adduct [ trade name "Coronate L" manufactured by Nippon polyurethane industries Co., Ltd.), trimethylolpropane/hexamethylene diisocyanate adduct [ trade name "Coronate HL" manufactured by Nippon polyurethane industries Co., Ltd.), trimethylolpropane/xylene diisocyanate adduct [ trade name "Takenate HX" (manufactured by Nippon polyurethane industries Co., Ltd. ], trimethylolpropane/xylene diisocyanate adduct [ trade name "Takenate 110N" manufactured by Mitsui chemical Co., Ltd. ], and the like. Examples of the active energy ray-curable isocyanate compound (D) include: isocyanates having a (meth) acryloyl group include, for example: commercially available products such as Karenz AOI (available from Showa Denko K.K.), Karenz BEI (available from Showa Denko K.K.), and Laromer LR9000 (available from BASF corporation).

The amount of the isocyanate compound (D) blended is usually 30 parts by weight or less based on 100 parts by weight of the total amount of the curable components, and when the content of the compound (D) in the active energy ray-curable adhesive group is too large, the adhesiveness may be deteriorated and the impact resistance in the drop test may be deteriorated. The content of the compound (D) in the active energy ray-curable adhesive is more preferably 20 parts by weight or less. On the other hand, the active energy ray-curable adhesive preferably contains the compound (D) in an amount of 0.1 part by weight or more, more preferably 1 part by weight or more, from the viewpoint of water resistance.

< silane coupling agent (E) >

When the curable adhesive for polarizing films of the present invention is an active energy ray-curable adhesive, an active energy ray-curable compound is preferably used as the silane coupling agent (E), but the same water resistance can be provided even if the curable adhesive is not active energy ray-curable.

Specific examples of the silane coupling agent (E) include active energy ray-curable compounds such as: vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3, 4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like.

3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane are preferred.

As a specific example of the non-active energy ray-curable silane coupling agent, a silane coupling agent having an amino group (E1) is preferable. Specific examples of the silane coupling agent having an amino group (E1) include: gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltriisopropoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldiethoxysilane, gamma- (2-aminoethyl) aminopropyltriisopropoxysilane, gamma- (2- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (6-aminohexyl) aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-2-aminopropyltrimethoxysilane, gamma-methyldiethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-aminopropyltrimethoxysilane, amino group-containing silanes such as 3- (N-ethylamino) -2-methylpropyltrimethoxysilane, γ -ureidopropyltrimethoxysilane, γ -ureidopropyltriethoxysilane, 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-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine.

The silane coupling agent having an amino group (E1) may be used alone in 1 kind or in combination of two or more kinds. Among them, in order to ensure good adhesion, gamma-aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldiethoxysilane, and N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine are preferable.

The amount of the silane coupling agent (E) is preferably in the range of 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, and still more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the total amount of the curable components. This is because, when the amount is more than 20 parts by weight, the storage stability of the adhesive is deteriorated, and when the amount is less than 0.1 part by weight, the effect of the water-resistant adhesion cannot be sufficiently exhibited. When the glass transition temperature Tg of the adhesive layer was calculated, the silane coupling agent (E) was not included in the calculation.

Specific examples of the silane coupling agent other than those described above which are not curable with active energy rays include: 3-urea propyl triethoxy silane, 3-chloropropyl trimethoxy silane, 3-mercaptopropyl methyl dimethoxy silane, 3-mercaptopropyl trimethoxy silane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanate propyl triethoxy silane, imidazole silane, etc.

The photoacid generator (B), the compound (C) containing any one of an alkoxy group and an epoxy group, the isocyanate compound (D), and the silane coupling agent (E) preferably have a logPow value of 1 or more, more preferably 2 or more. The components for calculating the logPow value of the curable adhesive for polarizing films do not include the photoacid generator (B) and the silane coupling agent (E). On the other hand, the components for calculating the logPow value of the curable adhesive for a polarizing film include a compound (C) containing either an alkoxy group or an epoxy group, and an isocyanate compound (D).

< additives other than the above >

In the curable adhesive for polarizing films of the present invention, various additives may be added as other optional components within a range not impairing the object and effects of the present invention. Examples of such additives include: polymers or oligomers such as polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene-butadiene block copolymer, petroleum resin, xylene resin, ketone-aldehyde resin, cellulose resin, fluorine-based oligomer, silicone-based oligomer, and polythioether-based oligomer; polymerization inhibitors such as phenothiazine and 2, 6-di-tert-butyl-4-methylphenol; a polymerization initiation aid; leveling agent; a wettability modifier; a surfactant; a plasticizer; an ultraviolet absorber; an inorganic filler; a pigment; dyes, and the like. Among the various additives, the logPow value is preferably high. The logPow value of each additive is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more. Note that the components in the calculation of the logPow value of the curable adhesive for polarizing films do not include these additives.

The additive is usually 0 to 10 parts by weight, preferably 0 to 5 parts by weight, and most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components.

< viscosity of adhesive >

The curable adhesive for a polarizing film of the present invention contains the above curable component, and the viscosity of the adhesive is preferably 100cp or less at 25 ℃. On the other hand, when the curing adhesive for a polarizing film of the present invention exceeds 100cp at 25 ℃, the temperature of the adhesive may be controlled to be 100cp or less at the time of coating. The viscosity is more preferably in the range of 1 to 80cp, most preferably 10 to 50 cp. The viscosity can be measured by using a model E viscometer TVE22LT manufactured by eastern industries.

In addition, the curable adhesive for a polarizing film of the present invention preferably uses a material that is less irritating to the skin as the curable component from the viewpoint of safety. The skin irritation can be judged by the index of p.i.i.i. P.i.i. measured by the Draize method is widely used as an index indicating the degree of skin irritation. The measurement value is represented by a range of 0 to 8, and the smaller the value, the lower the irritation, and the larger the error of the measurement value, so that it may be regarded as a reference value. The p.i.i.i. is preferably 4 or less, more preferably 3 or less, and most preferably 2 or less.

< polarizing film >

In the polarizing film of the present invention, a transparent protective film is bonded to at least one surface of the polarizing plate via an adhesive layer formed of a cured product layer of the curable adhesive for polarizing film. The adhesive layer as the cured product layer has a volume water absorption of 10 wt% or less, as described above.

< adhesive layer >

The thickness of the adhesive layer formed of the curable adhesive is preferably controlled to 0.1 to 3 μm. The thickness of the adhesive layer is more preferably 0.3 to 2 μm, and still more preferably 0.5 to 1.5 μm. The thickness of the adhesive layer is preferably 0.1 μm or more in order to suppress the occurrence of adhesion failure due to the cohesive force of the adhesive layer and to suppress the occurrence of appearance failure (air bubbles) during lamination. On the other hand, if the adhesive layer is thicker than 3 μm, the polarizing film may not satisfy durability.

The curable adhesive is preferably selected so that the Tg of the adhesive layer formed therefrom is 60 ℃ or higher, more preferably 70 ℃ or higher, even more preferably 75 ℃ or higher, even more preferably 100 ℃ or higher, and even more preferably 120 ℃ or higher. On the other hand, if Tg of the adhesive layer is too high, the bendability of the polarizing film decreases, and therefore: the Tg of the adhesive layer is set to 300 ℃ or less, further to 240 ℃ or less, and further to 180 ℃ or less. Tg < glass transition temperature > was measured using a TAinstruments braking viscoelasticity measuring apparatus RSAIII under the following measurement conditions.

Sample size: the width is 10mm, the length is 30mm,

the distance between the clamps is 20mm,

measurement mode: stretching, frequency: 1Hz, temperature rise rate: 5 ℃ per minute

The dynamic viscoelasticity was measured and used as the temperature Tg of the peak top of tan. delta.

In addition, in the case of a curable adhesive, the storage elastic modulus of the adhesive layer formed therefrom is preferably 1.0X 10 in the region of 70 ℃ or less⁶Pa or above. Still more preferably 1.0X 10⁷pa is higher than the total. GluingThe storage elastic modulus of the agent layer affects the breakage of the polarizing plate when a heat cycle is applied to the polarizing film (-40 ℃ C. to 80 ℃ C., etc.), and when the storage elastic modulus is low, the breakage of the polarizing plate is likely to occur. The temperature region having a high storage elastic modulus is more preferably 80 ℃ or less, most preferably 90 ℃ or less. And Tg<Glass transition temperature>The storage modulus of elasticity was measured under the same measurement conditions using a dynamic viscoelasticity measuring apparatus RSAIII manufactured by TA instruments. The dynamic viscoelasticity was measured by using the value of the storage modulus of elasticity (E '').

The polarizing film of the present invention has the following steps: the method for manufacturing the polarizing plate includes a step of applying a curable adhesive to a surface of the polarizing plate on which the adhesive layer is to be formed and/or a surface of the transparent protective film on which the adhesive layer is to be formed, and then bonding the polarizing plate and the transparent protective film, and a step of curing the curable adhesive to form the adhesive layer.

The polarizing plate and the transparent protective film may be subjected to a surface modification treatment before the application of the curable adhesive. Specific examples of the treatment include corona treatment, plasma treatment, and saponification treatment.

The application method of the curable adhesive is appropriately selected depending on the viscosity of the curable adhesive and the target thickness. Examples of the coating method include: reverse coaters, gravure coaters (direct, reverse or offset), bar reverse coaters, roll coaters, die coaters, bar coaters, rod coaters, and the like. In addition, a dipping method or the like can be suitably used for coating.

The polarizing plate and the transparent protective film were bonded to each other with the curable adhesive applied as described above. The polarizing plate and the transparent protective film may be bonded to each other by a roll laminator or the like.

< curing of adhesive >

The curable adhesive for a polarizing film of the present invention is used in the form of an active energy ray-curable adhesive or a heat-curable adhesive. The active energy ray-curable adhesive can be used in the form of an electron beam-curable adhesive, an ultraviolet-curable adhesive, or a visible light-curable adhesive. From the viewpoint of productivity, the curable adhesive is preferably an active energy ray curable adhesive in a form more preferable than the heat curable adhesive, and further, as the active energy ray curable adhesive, a visible light curable adhesive is preferable from the viewpoint of productivity.

Active energy ray curing type

The active energy ray-curable adhesive is an adhesive layer formed by bonding a polarizing plate and a transparent protective film, and then irradiating the polarizing plate and the transparent protective film with an active energy ray (e.g., an electron beam, ultraviolet light, or visible light) to cure the active energy ray-curable adhesive. The irradiation direction of the active energy ray (e.g., electron beam, ultraviolet ray, visible light, etc.) may be any appropriate direction. Irradiation is preferably from the transparent protective film side. When the polarizing plate is irradiated from the polarizer side, the polarizing plate may be deteriorated by active energy rays (electron beams, ultraviolet rays, visible light, and the like).

Electron Beam curing type

In the electron beam curing type, any appropriate conditions may be adopted as long as the irradiation conditions of the electron beam are conditions under which the active energy ray-curable adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5kV to 300kV, and more preferably 10kV to 250 kV. When the acceleration voltage is less than 5kV, the electron beam may not reach the adhesive and may be insufficiently cured, and when the acceleration voltage exceeds 300kV, the penetration force through the sample is too strong, and the transparent protective film or the polarizing plate may be damaged. The dose is 5 to 100kGy, and more preferably 10 to 75 kGy. When the irradiation dose is less than 5kGy, the adhesive is not sufficiently cured, and when it exceeds 100kGy, the adhesive may damage the transparent protective film and the polarizing plate, resulting in a decrease in mechanical strength and yellowing, and thus, predetermined optical characteristics may not be obtained.

In the electron beam irradiation, irradiation is usually performed in an inert gas, but may be performed in the atmosphere or under a condition where a small amount of oxygen is introduced, if necessary. Although depending on the material of the transparent protective film, oxygen is introduced appropriately, and oxygen inhibition is generated on the surface of the transparent protective film to which the electron beam is irradiated first, so that damage to the transparent protective film can be prevented, and the electron beam can be efficiently irradiated only to the adhesive.

Ultraviolet curing type and visible light curing type

In the method for producing a polarizing film of the present invention, an active energy ray including visible light having a wavelength range of 380nm to 450nm is preferably used as the active energy ray, and particularly, an active energy ray having the largest dose of visible light having a wavelength range of 380nm to 450nm is preferably used as the active energy ray. In the case of using a transparent protective film (ultraviolet-opaque transparent protective film) having ultraviolet absorptivity, the ultraviolet-curable or visible-light-curable adhesive absorbs light having a short wavelength of less than about 380nm, and therefore, light having a wavelength of less than 380nm does not reach the active energy ray-curable adhesive and does not contribute to the polymerization reaction. Further, light having a wavelength shorter than 380nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, resulting in defects such as curling and wrinkling of the polarizing film. Therefore, in the present invention, when the ultraviolet curing type or the visible light curing type is adopted, it is preferable to use a device which does not emit light having a wavelength shorter than 380nm as the active energy ray generating device, and more specifically, the ratio of the integrated illuminance in the wavelength range of 380 to 440nm to the integrated illuminance in the wavelength range of 250 to 370nm is preferably 100: 0 to 100: 50, and more preferably 100: 0 to 100: 40. As the active energy ray of the present invention, a metal halide lamp in which gallium is sealed, or an LED light source which emits light in a wavelength range of 380 to 440nm is preferable. Alternatively, a light source containing ultraviolet rays and visible light such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, an incandescent lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a gallium lamp, an excimer laser, or sunlight may be used, and a band-pass filter may be used to block ultraviolet rays having a wavelength shorter than 380 nm. In order to improve the adhesion property of the adhesive layer between the polarizing plate and the transparent protective film and to prevent curling of the polarizing film, it is preferable to use an active energy ray obtained by a gallium-sealed metal halide lamp using a band-pass filter capable of blocking light having a wavelength shorter than 380nm, or an active energy ray having a wavelength of 405nm obtained by using an LED light source.

In the ultraviolet-curable or visible-light-curable type, the active energy ray-curable adhesive is preferably heated before irradiation with ultraviolet rays or visible light (heating before irradiation), and in this case, the temperature is preferably 40 ℃ or higher, more preferably 50 ℃ or higher. Further, it is also preferable to heat the active energy ray-curable adhesive after irradiation with ultraviolet rays or visible light (heating after irradiation), and in this case, it is preferable to heat the adhesive to 40 ℃ or higher, and more preferably to 50 ℃ or higher.

The active energy ray-curable adhesive of the present invention can be used particularly preferably when an adhesive layer is formed to bond a polarizing plate and a transparent protective film having a light transmittance of less than 5% at a wavelength of 365 nm. Here, the active energy ray-curable adhesive of the present invention contains the photopolymerization initiator of the general formula (1) described above, and can be cured to form an adhesive layer by irradiating ultraviolet rays through a transparent protective film having UV absorbing ability. Therefore, even in the case of a polarizing film in which transparent protective films having UV absorbing ability are laminated on both surfaces of a polarizing plate, the adhesive layer can be cured. However, it is needless to say that the adhesive layer may be cured for a polarizing film in which a transparent protective film having no UV absorbing ability is laminated. The transparent protective film having UV absorption ability means a transparent protective film having a transmittance of light of 380nm of less than 10%.

Examples of the method for imparting UV absorption capability to the transparent protective film include: a method of containing an ultraviolet absorber in the transparent protective film, and a method of laminating a surface treatment layer containing an ultraviolet absorber on the surface of the transparent protective film.

Specific examples of the ultraviolet absorber include: conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like.

After the polarizing plate and the transparent protective film are bonded to each other, an active energy ray (e.g., electron beam, ultraviolet ray, visible light) is irradiated to cure the active energy ray-curable adhesive, thereby forming an adhesive layer. The irradiation direction of the active energy ray (e.g., electron beam, ultraviolet ray, visible light, etc.) may be any appropriate direction. Irradiation is preferably from the transparent protective film side. When irradiated from the polarizer side, the polarizer may be deteriorated by active energy rays (electron beams, ultraviolet rays, visible light, and the like).

Type of Heat curing

On the other hand, in the case of a thermosetting adhesive, after a polarizing plate and a transparent protective film are bonded, polymerization is initiated by a thermal polymerization initiator by heating to form a cured product layer. The heating temperature is set according to the thermal polymerization initiator, but is preferably about 60 to 200 ℃, and more preferably 80 to 150 ℃.

In the case of producing the polarizing film of the present invention by a continuous production line, the line speed depends on the curing time of the adhesive, but is preferably 1 to 500m/min, more preferably 5 to 300m/min, and still more preferably 10 to 100 m/min. When the linear velocity is too low, productivity is insufficient, or damage to the transparent protective film is too large, and a polarizing film that can withstand a durability test or the like cannot be produced. When the linear velocity is too high, the curing of the adhesive becomes insufficient, and the desired adhesiveness may not be obtained.

In the polarizing film of the present invention, the polarizing plate and the transparent protective film are bonded to each other by the adhesive layer formed of the cured product layer of the active energy ray-curable adhesive, but an easy-adhesion layer may be provided between the transparent protective film and the adhesive layer. The easy-adhesion layer can be formed using various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone skeleton, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, or the like. These polymer resins may be used singly or in combination of two or more. In addition, other additives may be added to the formation of the easy adhesion layer. Specifically, a thickener, an ultraviolet absorber, an antioxidant, a stabilizer such as a heat stabilizer, and the like can be used.

The easy-adhesion layer is usually provided in advance on the transparent protective film, and the easy-adhesion layer side of the transparent protective film is bonded to the polarizing plate with an adhesive layer. The easy adhesion layer is formed by applying a material for forming the easy adhesion layer on the transparent protective film by a known technique and drying the applied material. The material for forming the easy adhesion layer is usually adjusted in the form of a solution diluted to an appropriate concentration in consideration of the thickness after drying, the smoothness of coating, and the like. The thickness of the easy adhesion layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and still more preferably 0.05 to 1 μm. In this case, the total thickness of the easy adhesion layer is preferably within the above range.

< polarizing plate >

The polarizing plate is not particularly limited, and various polarizing plates can be used. Examples of the polarizing plate include films obtained by uniaxially stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film, to which a dichroic material such as iodine or a dichroic dye is adsorbed, and polyolefin-based oriented films such as a dehydrated polyvinyl alcohol film or a desalted polyvinyl chloride film. Among them, a polarizing plate containing a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizing plates is not particularly limited, and is usually about 80 μm or less.

The polarizing plate obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced by, for example, dyeing polyvinyl alcohol by immersing it in an aqueous iodine solution and stretching it to 3 to 7 times the original length. The substrate may be immersed in an aqueous solution of boric acid, potassium iodide, or the like as necessary. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. The polyvinyl alcohol film can be washed with water to clean dirt and an anti-blocking agent on the surface of the polyvinyl alcohol film, and in addition, the polyvinyl alcohol film can be swollen to prevent unevenness of dyeing. The stretching may be performed after the dyeing with iodine, or may be performed simultaneously with the dyeing, or may be performed after the stretching with iodine. Stretching may be carried out in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

The curable adhesive of the present invention can exhibit its remarkable effect (satisfying optical durability in a severe environment under high temperature and high humidity) when a thin polarizing plate having a thickness of 10 μm or less is used as a polarizing plate. The polarizing plate having a thickness of 10 μm or less has a relatively large influence of moisture as compared with a polarizing plate having a thickness of more than 10 μm, and thus has insufficient optical durability in an environment of high temperature and high humidity, and is likely to cause an increase in transmittance and a decrease in polarization degree. That is, when the polarizing plates of 10 μm or less are laminated with the adhesive layer of the present invention having a volume water absorption of 10 wt% or less, the deterioration of optical durability such as the increase of transmittance and the decrease of polarization degree of the polarizing film can be remarkably suppressed by suppressing the migration of water to the polarizing plate in a severe environment of high temperature and high humidity. The thickness of the polarizing plate is preferably 1 to 7 μm from the viewpoint of thinning. Such a thin polarizing plate is preferable in that it has less thickness unevenness, excellent visibility, and less dimensional change, and can be made thin even when used as a polarizing film.

As the thin polarizing plate, there can be representatively mentioned: a thin polarizing film described in Japanese patent laid-open Nos. 51-069644, 2000-338329, WO2010/100917, PCT/JP2010/001460, 2010-269002, and 2010-263692. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a stretching resin base material in a state of a laminate and a step of dyeing. With this method, even if the PVA-based resin layer is thin, it can be stretched without causing any trouble such as breaking due to stretching by being supported by the stretching resin base material.

In the production method including the step of stretching in a state of a laminate and the step of dyeing, the thin polarizing film is preferably obtained by a production method including the step of stretching in an aqueous boric acid solution described in WO2010/100917 pamphlet, PCT/JP2010/001460 specification, japanese patent application 2010-269002 specification, and japanese patent application 2010-263692 specification, and particularly preferably obtained by a production method including the step of performing aerial stretching in an aqueous boric acid solution with assistance before stretching in an aqueous boric acid solution described in japanese patent application 2010-269002 specification and japanese patent application 2010-263692 specification, from the viewpoint of being capable of stretching to a high magnification to improve polarizing performance.

The thin high-function polarizing film described in the specification of PCT/JP2010/001460 is a thin high-function polarizing film having a thickness of 7 μm or less, which is formed by integrally forming a film on a resin substrate, contains a PVA-based resin having a dichroic material oriented therein, and has optical properties such as a single-component transmittance of 42.0% or more and a polarization degree of 99.95% or more.

The thin high-functional polarizing film may be manufactured by: a PVA resin layer is formed by coating a PVA resin on a resin substrate having a thickness of at least 20 [ mu ] m and drying the resin substrate, the formed PVA resin layer is immersed in a dyeing solution of a dichroic substance to adsorb the dichroic substance in the PVA resin layer, and the PVA resin layer adsorbed with the dichroic substance is stretched in an aqueous boric acid solution together with the resin substrate so that the total stretch ratio becomes 5 times or more of the original length.

In addition, in the method for manufacturing a laminate film including a thin high-functional polarizing film in which a dichroic material is oriented, the thin high-functional polarizing film can be manufactured by including the steps of: generating a laminate film including a resin base material having a thickness of at least 20 μm and a PVA-based resin layer formed by applying an aqueous solution containing a PVA-based resin to one surface of the resin base material and drying the aqueous solution; immersing the laminate film including the resin substrate and the PVA-based resin layer formed on one surface of the resin substrate in a dyeing solution containing a dichroic substance, thereby causing the dichroic substance to be adsorbed in the PVA-based resin layer contained in the laminate film; stretching the laminate film including the PVA-based resin layer having the dichroic material adsorbed thereon in an aqueous boric acid solution so that the total stretching ratio is 5 times or more the original length; a laminate film comprising a thin highly functional polarizing film having a thickness of 7 [ mu ] m or less, and having optical properties such as a monomer transmittance of 42.0% or more and a polarization degree of 99.95% or more, and comprising a PVA resin layer having a dichroic material adsorbed thereon and a resin base material, the PVA resin layer and the resin base material being stretched integrally.

The thin polarizing films described in japanese patent application No. 2010-269002 and japanese patent application No. 2010-263692 are continuous belt-shaped polarizing films containing a PVA-based resin in which a dichroic material is oriented, and are formed to have a thickness of 10 μm or less by stretching a laminate containing a PVA-based resin layer formed on an amorphous ester-based thermoplastic resin substrate in a two-stage stretching step consisting of in-air auxiliary stretching and boric acid water stretching. The thin polarizing film preferably has optical characteristics satisfying P > - (10) where T is a transmittance of the monomer and P is a degree of polarization^{0.929T-42.4-1}) X100 (wherein, T < 42.3) and P.gtoreq.99.9 (wherein, T.gtoreq.42.3).

Specifically, the thin polarizing film may be manufactured by a method for manufacturing a thin polarizing film including the steps of: stretching a PVA-based resin layer formed on a continuous belt-shaped amorphous ester-based thermoplastic resin substrate at a high temperature in the air to produce a stretched intermediate product including the oriented PVA-based resin layer; adsorbing the dichroic substance to the stretched intermediate to produce a colored intermediate including a PVA-based resin layer in which the dichroic substance (preferably iodine or a mixture of iodine and an organic dye) is oriented; and boric acid underwater stretching the colored intermediate product to produce a polarizing film having a thickness of 10 μm or less comprising a PVA-based resin layer in which the dichroic material is oriented.

In this production method, the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate by the aerial high-temperature stretching and the boric acid underwater stretching preferably has a total stretching ratio of 5 times or more. The liquid temperature of the aqueous boric acid solution used for underwater stretching of boric acid may be set to 60 ℃ or higher. The coloring intermediate is preferably insolubilized before it is stretched in an aqueous boric acid solution, and in this case, it is preferably carried out by immersing the coloring intermediate in an aqueous boric acid solution having a liquid temperature of not more than 40 ℃. The amorphous ester-based thermoplastic resin substrate is preferably a substrate which is capable of forming an amorphous polyethylene terephthalate containing copolymerized polyethylene terephthalate obtained by copolymerizing isophthalic acid, copolymerized polyethylene terephthalate obtained by copolymerizing cyclohexane dimethanol, or other copolymerized polyethylene terephthalate and contains a transparent resin, and the thickness of the substrate may be set to 7 times or more the thickness of the PVA-based resin layer to be formed. The stretching ratio in the in-air high-temperature stretching is preferably 3.5 times or less, and the stretching temperature in the in-air high-temperature stretching is preferably not less than the glass transition temperature of the PVA-based resin, and specifically, is preferably in the range of 95 to 150 ℃. In the case of in-air high-temperature stretching by free-end uniaxial stretching, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate is preferably 5 times or more and 7.5 times or less. In the case of in-air high-temperature stretching by fixed-end uniaxial stretching, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate is preferably 5 times or more and 8.5 times or less.

More specifically, the thin polarizing film may be manufactured by the method as described below.

A continuous belt-like substrate of isophthalic acid copolymerized polyethylene terephthalate (amorphous PET) was prepared by copolymerizing 6 mol% of isophthalic acid. The glass transition temperature of amorphous PET is 75 ℃. A laminate comprising a continuous network of an amorphous PET substrate and a polyvinyl alcohol (PVA) layer was produced in the following manner. Incidentally, the glass transition temperature of PVA is 80 ℃.

A200 μm-thick amorphous PET substrate and a 4-5% PVA aqueous solution obtained by dissolving PVA powder having a polymerization degree of 1000 or more and a saponification degree of 99% or more in water are prepared. Then, a PVA aqueous solution was applied to a 200 μm-thick amorphous PET substrate, and the substrate was dried at 50 to 60 ℃ to obtain a laminate in which a 7 μm-thick PVA layer was formed on the amorphous PET substrate.

A thin, highly functional polarizing film having a thickness of 3 μm was produced by subjecting a laminate comprising a PVA layer having a thickness of 7 μm to the following two-stage stretching step comprising air-assisted stretching and boric acid underwater stretching. The laminate including the PVA layer having a thickness of 7 μm was integrally stretched with the amorphous PET substrate by the in-air auxiliary stretching step in the first stage, to produce a stretched laminate including the PVA layer having a thickness of 5 μm. Specifically, the stretched laminate was obtained by placing a laminate including a PVA layer having a thickness of 7 μm in a stretching device disposed in an oven set at a stretching temperature environment of 130 ℃ and performing free-end uniaxial stretching so that the stretching magnification was 1.8 times. By this stretching treatment, the PVA layer contained in the stretched laminate was changed to a PVA layer 5 μm thick in thickness in which the PVA molecules were oriented.

Subsequently, a colored laminate in which iodine was adsorbed on a PVA layer having a thickness of 5 μm in which PVA molecules were oriented was produced through a dyeing step. Specifically, the colored laminate is obtained by immersing a stretched laminate in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ℃ for an arbitrary period of time so that the monomer transmittance of a PVA layer constituting a finally produced highly functional polarizing film is 40 to 44%, and adsorbing iodine in the PVA layer contained in the stretched laminate. In the step, the dyeing liquid uses water as a solvent, the iodine concentration is in the range of 0.12 to 0.30 wt%, and the potassium iodide concentration is in the range of 0.7 to 2.1 wt%. The concentration ratio of iodine to potassium iodide was 1 to 7. Incidentally, when iodine is dissolved in water, potassium iodide is required. More specifically, the stretched laminate was immersed in a staining solution containing 0.30 wt% of iodine and 2.1 wt% of potassium iodide for 60 seconds to produce a colored laminate in which iodine was adsorbed on a PVA layer having a thickness of 5 μm in which the PVA molecules were oriented.

Further, the colored laminate was further stretched integrally with the amorphous PET substrate by the boric acid underwater stretching step of the second stage, to produce an optical film laminate including a PVA layer constituting a highly functional polarizing film having a thickness of 3 μm. Specifically, the optical film laminate is obtained by placing the colored laminate in a stretching device disposed in a treatment device containing boric acid and potassium iodide and an aqueous boric acid solution set in a liquid temperature range of 60 to 85 ℃, and performing free-end uniaxial stretching so that the stretching magnification is 3.3 times. More specifically, the liquid temperature of the aqueous boric acid solution was 65 ℃. Further, the boric acid content was set to 4 parts by weight with respect to 100 parts by weight of water, and the potassium iodide content was set to 5 parts by weight with respect to 100 parts by weight of water. In this step, the colored laminate having the iodine adsorption amount adjusted is first immersed in an aqueous boric acid solution for 5 to 10 seconds. Then, the colored laminate was passed directly between a plurality of sets of rollers having different peripheral speeds, which were stretching devices disposed in a processing apparatus, and free-end uniaxial stretching was performed for 30 to 90 seconds so that the stretching magnification was 3.3 times. By this stretching treatment, the PVA layer contained in the colored laminate is changed into a PVA layer of 3 μm thickness in which the adsorbed iodine is highly oriented in one direction in the form of a polyiodide complex. The PVA layer constitutes a highly functional polarizing film of the optical film laminate.

Although not a step necessary for producing the optical film laminate, it is preferable that the optical film laminate is taken out from the boric acid aqueous solution in the cleaning step, and the boric acid adhered to the surface of the PVA layer having a thickness of 3 μm formed on the amorphous PET substrate is cleaned with the potassium iodide aqueous solution. Then, the cleaned optical film laminate was dried by a drying process using warm air at 60 ℃. The cleaning step is a step for eliminating appearance defects such as precipitation of boric acid.

Similarly, although not a step necessary for producing the optical film laminate, an adhesive may be applied to the surface of the 3 μm thick PVA layer formed on the amorphous PET substrate by a bonding and/or transfer step, and an 80 μm thick triacetyl cellulose film may be bonded, and then the amorphous PET substrate may be peeled off, and the 3 μm thick PVA layer may be transferred to the 80 μm thick triacetyl cellulose film.

[ other Processes ]

The method for manufacturing a thin polarizing film may further include other steps in addition to the above steps. Examples of the other steps include an insolubilization step, a crosslinking step, and a drying (adjustment of moisture content) step. The other steps may be performed at any appropriate timing.

Typically, the insolubilization step may be performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing insolubilization treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the aqueous boric acid solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilization bath (aqueous boric acid solution) is preferably 20 to 50 ℃. The insolubilization step is preferably performed after the laminate is produced, and before the dyeing step or the underwater stretching step.

Typically, the crosslinking step is performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the crosslinking treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the aqueous boric acid solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. In the case where the crosslinking step is performed after the dyeing step, it is preferable to further incorporate an iodide. The iodine compound can suppress elution of iodine adsorbed in the PVA-based resin layer. The amount of the iodide is preferably 1 to 5 parts by weight based on 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably 20 ℃ to 50 ℃. The crosslinking step is preferably performed before the second aqueous boric acid stretching step. In a preferred embodiment, the dyeing step, the crosslinking step, and the second aqueous diboronic acid stretching step are performed in this order.

< transparent protective film >

As a material for forming the transparent protective film provided on one surface or both surfaces of the polarizing plate, a material excellent in transparency, mechanical strength, thermal stability, water resistance, isotropy, and the like is preferable. Examples thereof include polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such AS diacetylcellulose and triacetylcellulose, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. Examples of the polymer forming the transparent protective film include polyolefin polymers such as polyethylene, polypropylene, ring-based or norbornene-based polyolefins, ethylene-propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamides, imide polymers, sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, acrylic polymers, polyoxymethylene polymers, epoxy polymers, and blends of the above polymers. The transparent protective film may contain 1 or more kinds of any appropriate additives. Examples of additives include: ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, coloring prevention agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, even more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50 wt% or less, high transparency and the like inherent in the thermoplastic resin may not be sufficiently exhibited.

Further, as the transparent protective film, there can be mentioned a polymer film described in Japanese patent laid-open No. 2001-343529 (WO01/37007), for example, a resin composition containing (A) a thermoplastic resin having a substituted and/or unsubstituted imide group in a side chain and (B) a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group in a side chain. As a specific example, a film containing a resin composition comprising an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be cited. As the film, a film of a mixed extrusion product or the like containing the resin composition can be used. These films have a small phase difference and a small photoelastic coefficient, and therefore, can eliminate problems such as unevenness caused by strain of the polarizing film, and have excellent humidification durability because of a small moisture permeability.

In the polarizing film, the transparent protective film preferably has a moisture permeability of 150g/m²The time is less than 24 h. With this configuration, moisture in the air is less likely to enter the polarizing film, and the change in the moisture percentage of the polarizing film itself can be suppressed. As a result, curling and dimensional change of the polarizing film due to the storage environment can be suppressed.

As a material for forming the transparent protective film provided on one surface or both surfaces of the polarizing plate, a material excellent in transparency, mechanical strength, thermal stability, water blocking property, isotropy and the like is preferable, and particularly, a material having a moisture permeability of 150g/m is more preferable²Materials below 24h, particularly preferably 140g/m²Material with a length of less than 24h, more preferably 120g/m²Materials with the length of less than 24 h. The moisture permeability was determined by the method described in examples.

As a material for forming the transparent protective film satisfying the low moisture permeability, for example, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate; a polycarbonate resin; an acrylic resin; amide resins such as nylon and aromatic polyamide; polyolefin-based polymers such as polyethylene, polypropylene and ethylene-propylene copolymers, cyclic olefin-based resins having a ring system or a norbornene structure, (meth) acrylic resins, or mixtures thereof. Among the above resins, polycarbonate-based resins, cyclic polyolefin-based resins, and (meth) acrylic resins are preferable, and cyclic polyolefin-based resins and (meth) acrylic resins are particularly preferable.

The thickness of the transparent protective film can be determined as appropriate, but is usually about 1 to 100 μm in view of workability such as strength and workability, and thin layer property. Particularly preferably 1 to 80 μm, and more preferably 3 to 60 μm.

When transparent protective films are provided on both surfaces of the polarizing plate, transparent protective films made of the same polymer material may be used on the front and back surfaces, or transparent protective films made of different polymer materials may be used.

The surface of the non-adhesive polarizing plate of the transparent protective film may be provided with a functional layer such as a hard coat layer, an antireflection layer, an adhesion-preventing layer, a diffusion layer, or an antiglare layer. The functional layer such as the hard coat layer, the antireflection layer, the adhesion prevention layer, the diffusion layer, or the antiglare layer may be provided separately from the transparent protective film, in addition to the transparent protective film itself.

< optical film >

The polarizing film of the present invention may be used in the form of an optical film laminated with other optical layers in actual use. The optical layer is not particularly limited, and 1 or 2 or more layers of optical layers may be used, for example, optical layers used for forming a liquid crystal display device such as a reflective plate, a semi-transmissive plate, a retardation plate (including a wavelength plate such as 1/2 or 1/4), a viewing angle compensation film, and the like. Particularly, a reflective polarizing film or a semi-transmissive polarizing film in which a reflective plate or a semi-transmissive reflective plate is further laminated on the polarizing film of the present invention, an elliptical polarizing film or a circular polarizing film in which a phase difference plate is further laminated on the polarizing film, a wide-angle polarizing film in which a viewing angle compensating film is further laminated on the polarizing film, or a polarizing film in which a brightness enhancing film is further laminated on the polarizing film is preferable.

The optical film in which the optical layers are laminated on the polarizing film may be formed by laminating the layers one by one in the manufacturing process of a liquid crystal display device or the like, but the optical film prepared by laminating the layers in advance has advantages of excellent stability of quality, excellent assembly operation, and the like, and improvement of the manufacturing process of the liquid crystal display device or the like. The lamination may use an appropriate bonding means such as an adhesive layer. When the polarizing film or another optical film is bonded, the optical axes thereof may be arranged at an appropriate angle according to the target retardation characteristics.

An adhesive layer for adhesion to other members such as a liquid crystal cell may be provided on the polarizing film or the optical film in which at least 1 polarizing film is laminated. The adhesive agent for forming the adhesive layer is not particularly limited, and an adhesive agent using a polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, or a rubber-based polymer as a base polymer can be appropriately selected and used. In particular, an adhesive such as an acrylic adhesive which is excellent in optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness and adhesiveness, and is excellent in weather resistance, heat resistance and the like can be preferably used.

The adhesive layer may be provided on one or both surfaces of the polarizing film or the optical film as a stacked layer of layers having different compositions, types, or the like. When the polarizing film and the optical film are provided on both surfaces, adhesive layers having different compositions, types, thicknesses, and the like may be formed on the front and back surfaces of the polarizing film and the optical film. The thickness of the adhesive layer can be suitably determined depending on the purpose of use, adhesion, etc., and is usually 1 to 500. mu.m, preferably 1 to 200. mu.m, and particularly preferably 1 to 100. mu.m.

The exposed surface of the adhesive layer is protected by temporarily adhering a separator to prevent contamination and the like until the adhesive layer is put into practical use. This prevents contact with the adhesive layer in a normal processing state. As the separator, in addition to the above thickness conditions, conventionally suitable separators such as those obtained by coating an appropriate sheet-like material such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foamed sheet, a metal foil, or a laminate thereof with an appropriate release agent such as a silicone type, a long chain alkyl type, a fluorine type, or molybdenum sulfide, if necessary, can be used.

< image display apparatus >

The polarizing film or optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to a conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell with a polarizing film or an optical film and, if necessary, components such as an illumination system, and then providing a driver circuit and the like. For the liquid crystal cell, any type such as TN type, STN type, and pi type may be used.

A liquid crystal display device in which a polarizing film or an optical film is disposed on one side or both sides of a liquid crystal cell, or an appropriate liquid crystal display device in which a backlight, a reflection plate, or the like is used in an illumination system can be formed. In this case, the polarizing film or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When a polarizing film or an optical film is provided on both sides, they may be the same or different. Further, in forming a liquid crystal display device, appropriate members such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be arranged in one or more layers at appropriate positions.

Examples

Examples of the present invention are described below, but the embodiments of the present invention are not limited to these examples.

< preparation of polarizing plate >

A polyvinyl alcohol film having a thickness of 75 μm and an average polymerization degree of 2400 and a saponification degree of 99.9 mol% was immersed in warm water at 30 ℃ for 60 seconds to swell the film. Then, the film was immersed in a 0.3% aqueous solution of iodine/potassium iodide (weight ratio: 0.5/8) and the film was dyed while being stretched to 3.5 times. Then, stretching was performed in a 65 ℃ boric acid ester aqueous solution so that the total stretching ratio was 6 times. After the stretching, the sheet was dried in an oven at 40 ℃ for 3 minutes to obtain a PVA based polarizing plate X (thickness: 23 μm).

< transparent protective film >

Transparent protective film 1: a triacetyl cellulose film having a thickness of 60 μm (moisture permeability 530 g/m) and not subjected to saponification, corona treatment or the like was used²24h) (Table 1, denoted TAC).

Transparent protective film 2: for a (meth) acrylic resin having a lactone ring structure with a thickness of 40 μm (moisture permeability 96 g/m)²24h) was used after corona treatment (noted as acrylic in Table 1).

Transparent protective film 3: for a cyclic polyolefin film (manufactured by Nippon Raynaud: ZEONOR, moisture permeability: 11 g/m) having a thickness of 55 μm²24h) was used after corona treatment (noted COP in table 1).

< moisture permeability of transparent protective film >

The moisture permeability was measured according to the moisture permeability test (cup method) of JIS Z0208. A sample cut into a diameter of 60mm was placed in a moisture-permeable cup containing about 15g of calcium chloride, the cup was placed in a thermostatic apparatus at a temperature of 40 ℃ and a humidity of 90% R.H., and the weight increase of calcium chloride before and after the cup was left for 24 hours was measured to determine the moisture permeability (g/m)²/24h)。

< active energy ray >

Irradiation device using visible light (gallium-sealed metal halide lamp): light HAMMER10 bulb manufactured by Fusion UV Systems, Inc: peak illuminance of V-bulb: 1600mW/cm²Cumulative dose 1000/mJ/cm²(wavelength 380-440 nm) as an active energy ray. The illuminance of visible light was measured by using the Sola-Check system manufactured by Solatell corporation.

Examples 1 to 4 and comparative examples 1 to 5

(preparation of active energy ray-curable adhesive)

The active energy ray-curable adhesives of example 1 and comparative example 1 were obtained by mixing the respective components and stirring at 50 ℃ for 1 hour in accordance with the formulation table shown in table 1. The viscosity of the actinic energy ray-curable adhesive of example 1 was 95cp (25 ℃), and the viscosity of the actinic energy ray-curable adhesive of comparative example 1 was 45cp (25 ℃).

(preparation of polarizing film)

The active energy ray-curable adhesive of the examples or comparative examples was applied to the transparent protective film to a thickness of 0.7 μm using an MCD coater (manufactured by fuji machine corporation) (cell shape: honeycomb, number of gravure rolls: 1000 pieces/inch, rotation speed 140%/relative line speed), and was bonded to both surfaces of the polarizing plate X using a roll coater. Then, the adhesive was heated from the side of the transparent protective film (both sides) to 50 ℃ by an IR heater, both sides were irradiated with the visible light to cure the active energy ray-curable adhesive of the examples or comparative examples, and then hot air-dried at 70 ℃ for 3 minutes to obtain a polarizing film having transparent protective films on both sides of the polarizing plate. The lamination was carried out at a line speed of 25 m/min.

Polarizing films were produced according to 3 of the transparent protective films 1 to 3.

The polarizing films obtained in the above examples and comparative examples were evaluated as follows. The evaluation results are shown in table 1. In the evaluation of the humidification durability and the adhesion water resistance, the same polarizing films were separately produced.

< volume Water absorption >

The curable adhesive for polarizing films used in each example was sandwiched between 2 sheets of glass provided with a spacer of 100 μm, and cured under the same activation energy conditions as in examples to prepare an adhesive layer (cured product) having a thickness of 100 μm. This was used as a sample. The weight of the sample was set to M1 g. The sample M1g was immersed in pure water at 23 ℃ for 24 hours. Thereafter, the sample was taken out of the pure water, wiped with a dried cloth, and the weight of the sample was measured again within 1 minute (M2 g). According to these results, the compound represented by the formula: the volume water absorption was calculated by { (M2-M1)/M1 }. times.100 (%).

< curing shrinkage >

Measured by a curing shrinkage sensor manufactured by Sentec corporation, "resin curing shrinkage stress measuring apparatus EU 201C". Specifically, the curing shrinkage rate is calculated by the method described in Japanese patent laid-open No. 2013-104869. The curing shrinkage of the cured product of the active energy ray-curable adhesive of example 1 was 8.9%, and the curing shrinkage of the cured product of the active energy ray-curable adhesive of comparative example 1 was 11.9%.

< adhesion >

The polarizing films obtained in the respective examples were cut into a size of 200mm in the direction parallel to the stretching direction of the polarizing plate and 20mm in the orthogonal direction, and a slit was cut between the transparent protective film and the polarizing plate with a cutter knife to bond the polarizing films to a glass plate. The transparent protective film and the polarizing plate were peeled off at a peeling speed of 500mm/min in a 90-degree direction by Tensilon, and the peel strength was measured. The infrared absorption spectrum of the peeled surface after the peeling was measured by ATR method, and the peeling interface was evaluated according to the following criteria.

A: coagulation destruction of transparent protective film

B: interfacial peel-off between transparent protective film/adhesive layer

C: interfacial peeling between adhesive layer/polarizer

D: coagulation destruction of polarizing plate

In the above criteria, the adhesion of a and D is not less than the cohesive force of the film, and thus it means that the adhesion is very excellent. On the other hand, the transparent protective film/adhesive layer (adhesive layer/polarizing plate) interface of B and C has insufficient adhesive force (poor adhesive force). Accordingly, the adhesive strength at A or D was rated as O, the adhesive strength at A-B (simultaneous occurrence of "cohesive failure of transparent protective film" and "interfacial peeling between transparent protective film and adhesive layer") or A-C (simultaneous occurrence of "cohesive failure of transparent protective film" and "interfacial peeling between adhesive layer and polarizing plate") was rated as Δ, and the adhesive strength at B or C was rated as X.

< humidification durability: measurement of Change in monomer transmittance and degree of polarization >

Polarizing films in which 1 transparent protective films 2 and 3 as transparent protective films were laminated on both sides of a polarizing plate were prepared as samples in the same manner as in examples and comparative examples. The polarizing film (sample) was placed in a constant temperature and humidity machine at 85 ℃/85% RH for 500 hours. The monomer transmittance and the degree of polarization of the polarizing film before and after the input were measured by using a spectral transmittance measuring instrument with an integrating sphere (Dot-3 c of color technology research institute in village), and the following calculation was performed:

the amount of change in the monomer transmittance (Δ T:%) is (monomer transmittance (%) after charging (monomer transmittance (%) before charging),

the amount of change in polarization degree (Δ P:%) is (polarization degree (%) after charging (polarization degree (%) before charging).

The polarization degree P is a value obtained by applying, to the following equation, the transmittance (parallel transmittance: Tp) when 2 sheets of the same polarizing films are superimposed such that the transmission axes of the 2 sheets of the same polarizing films are parallel, and the transmittance (orthogonal transmittance: Tc) when the two transmission axes are orthogonal. Polarization degree P (%) { (Tp-Tc)/(Tp + Tc) }^1/2×100

Each transmittance is a value represented by a Y value obtained by correcting the brightness of a fully polarized light beam passing through a glan taylor prism polarizing plate with a 2-degree field of view (C light source) according to JIS Z8701, assuming that the fully polarized light beam passes through the glan taylor prism polarizing plate as 100%.

< Water resistance to adhesion (Hot Water immersion test) >

Polarizing films in which 1 transparent protective films 1 and 3 as transparent protective films were laminated on both sides of a polarizing plate were prepared as samples in the same manner as in examples and comparative examples. The polarizing film (sample) was cut into a rectangular shape having a polarizing plate with a stretching direction of 50mm and a perpendicular direction of 25 mm. The polarizing film was immersed in warm water at 60 ℃ for 6 hours, and the length of peeling was visually measured with a magnifier. The maximum value (mm) of the perpendicular distance from the cross section of the portion where peeling occurred was taken as a measurement value.

< Water resistance of adhesion (resistance to Water peeling) >

Polarizing films in which 1 transparent protective films 1 and 3 as transparent protective films were laminated on both sides of a polarizing plate were prepared as samples in the same manner as in examples and comparative examples. The polarizing film (sample) was cut into a size of 200mm in the direction parallel to the stretching direction of the polarizing plate and 20mm in the orthogonal direction. The polarizing film was immersed in pure water at 23 ℃ for 24 hours, taken out of the pure water, wiped with a dried cloth, and then cut with a cutter knife between the transparent protective film and the polarizing plate, to bond the polarizing film to a glass plate. The operation from the extraction of pure water to the evaluation was carried out within 1 minute. Thereafter, the same evaluation as the above < adhesion > was performed.

< calculation of logPow >

The logPow value of each compound obtained by Chem DrawUltra (Cambridge Soft) was calculated by the following formula. The polymerization initiator and the photoacid generator were removed from the calculation.

logPow ═ Sigma (logPowi. times Wi) of curing adhesive

logPowi: logPow value of each component of curing adhesive

And Wi: (number of moles of component i)/(total number of moles of components of the curable adhesive)

[ Table 1]

In table 1, the radical polymerizable compounds show:

HEAA: hydroxyethyl acrylamide, logPow ═ 0.56, Tg of homopolymer ═ 123 ℃, manufactured by xinko corporation;

ACMO: acryloyl morpholine, logPow ═ 0.20, Tg of homopolymer ═ 150 ℃, manufactured by xinko corporation;

FA-THFM: tetrahydrofurfuryl (meth) acrylate, logPow 1.13, homopolymer Tg 45 ℃, manufactured by hitachi chemical company;

light Acrylate DCP- ｃA: tricyclodecane dimethanol diacrylate, logPow 3.05, Tg 134 ℃ for homopolymer, manufactured by cohniki chemical corporation;

light Acrylate 1, 9 ND-a: 1, 9-nonanediol diacrylate, logPow 3.68, Tg 68 ℃ for the homopolymer, manufactured by honor chemical;

aronix M-220: tripropylene glycol diacrylate, logPow 1.68, Tg69 ℃ of homopolymer, manufactured by east asian synthesis company;

aronix M-306: pentaerythritol tri/tetraacrylate, logPow 1.04, homopolymer Tg 250 ℃ or higher, manufactured by east asia synthesis company.

Acrylic oligomer shows: ARUFON UP-1190, logPow 1.95 manufactured by Toyo Synthesis Co., Ltd.,

alkoxy-containing compounds show: nikalac MX-750LM, logPow 0.8 manufactured by Carbide industries, Japan,

the epoxy-containing compound shows: JER828, logPow 4.76 manufactured by japan epoxy resin corporation,

the isocyanate compound shows: karenz AOI, logPow ═ 1.6 Showa Denko K.K.).

The photopolymerization initiator shows:

IRGACURE907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), logPow ═ 2.09, manufactured by BASF corporation

KAYACURE DETX-S (diethylthioxanthone), logPow 5.12, manufactured by japan chemicals co.

The photoacid generator was CPI-100P (propylene carbonate solution containing 50% of an active ingredient containing triarylsulfonium hexafluorophosphate as a main component), manufactured by San-Apro.

Claims (14)

1. A curable adhesive for a polarizing film, characterized by containing a curable component,

the curable adhesive for a polarizing film has a volume water absorption rate of 10% by weight or less as shown in the following formula when a cured product obtained by curing the curable adhesive is immersed in pure water at 23 ℃ for 24 hours,

volume water absorption (%) { (M2-M1)/M1} × 100,

wherein M1 represents the weight of the cured product before immersion, M2 represents the weight of the cured product after immersion,

the octanol/water partition coefficient (logPow value) is 1 or more,

the curable component is an active energy ray-curable component,

the active energy ray-curable component contains a radical-polymerizable compound,

the radical polymerizable compound comprises a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound having at least 2 functional groups having radical polymerizability,

the monofunctional radical polymerizable compound is used in a proportion of 3 to 40 wt% and the polyfunctional radical polymerizable compound is used in a proportion of 60 to 97 wt% with respect to 100 wt% of the radical polymerizable compound.

2. The curable adhesive for polarizing film according to claim 1, wherein the radical polymerizable compound comprises a (meth) acrylamide derivative.

3. The curable adhesive for a polarizing film according to any one of claims 1 to 2, further comprising a photopolymerization initiator.

4. The curable adhesive for polarizing film according to any one of claims 1 to 2, further comprising an acrylic oligomer (A).

5. The curable adhesive for polarizing film according to any one of claims 1 to 2, further comprising a photoacid generator (B).

6. The curable adhesive for polarizing film according to any one of claims 1 to 2, further comprising a compound (C) containing any one of an alkoxy group and an epoxy group.

7. The curable adhesive for polarizing film according to claim 6, wherein the compound (C) containing either an alkoxy group or an epoxy group is an alkoxy group-containing compound (C1).

8. The curable adhesive for polarizing film according to claim 7, wherein the alkoxy group-containing compound (C1) is an alkoxy group-containing melamine compound.

9. The curable adhesive for a polarizing film according to any one of claims 1 to 2, further comprising an isocyanate compound (D).

10. The curable adhesive for polarizing film according to claim 1, wherein the curable component is a thermosetting component, and further comprises a thermal polymerization initiator.

11. A polarizing film characterized in that a transparent protective film is provided on at least one surface of a polarizing plate via an adhesive layer,

the adhesive layer is formed from a cured product layer of the curable adhesive for a polarizing film according to any one of claims 1 to 10.

12. The polarizing film of claim 11, wherein the adhesive cured layer has a thickness of 0.1 to 3 μm.

13. An optical film characterized by being laminated with at least 1 polarizing film according to claim 11 or 12.

14. An image display device using the polarizing film according to claim 11 or 12 or the optical film according to claim 13.