CN111458783A - Polarizing film and method for producing same - Google Patents

Abstract

The invention provides a polarizing film, which is a polarizing film laminated with a transparent protective film on at least one side of a polarizing plate through an adhesive layer, wherein the adhesive layer is a layer formed by a cured product layer obtained by irradiating an active energy ray curing adhesive composition with active energy rays, the active energy ray curing adhesive composition contains a component A with logPow of-1 to 1 and a component B with logPow of 2 to 7, and the concentration of the component A on the polarizing plate side in the adhesive layer is high. The polarizing film exhibits high adhesive strength when a polarizing plate and a transparent protective film are laminated, and has an adhesive layer having excellent water resistance.

Description

Polarizing film and method for producing same

This application is a divisional application, the application number of its parent application: 201580038040.8, filing date: 2015.7.14, title of the invention: a polarizing film and a method for producing the same.

Technical Field

The present invention relates to a polarizing film in which a transparent protective film is laminated on at least one side of a polarizing plate with an adhesive layer interposed therebetween, and a method for producing the same, wherein the polarizing film can be used alone or as an optical film on which the polarizing film is laminated to form an image display device such as a liquid crystal display device (L CD), an organic E L display device, a CRT, or a PDP.

Background

The market demand for liquid crystal display devices is rapidly expanding in watches, mobile phones, PDAs, notebook personal computers, monitors for personal computers, DVD players, TVs, and the like. A liquid crystal display device is a device for visualizing a polarization state caused by switching (switching) of liquid crystal, and a polarizing plate is currently used according to a display principle thereof. In particular, in applications such as TVs, high brightness, high contrast, and wide viewing angle are increasingly required, and polarizing films are also increasingly required to have high transmittance, high polarization degree, high color reproducibility, and the like.

As a polarizing plate, an iodine-based polarizing plate having a structure in which, for example, polyvinyl alcohol (hereinafter, also simply referred to as "PVA") is adsorbed with iodine and stretched is most widely used because of its high transmittance and high degree of polarization. In general, a polarizing film is used which is obtained by laminating transparent protective films on both surfaces of a polarizing plate with a so-called aqueous adhesive obtained by dissolving a polyvinyl alcohol-based material in water ( patent documents 1 and 2 listed below). Triacetyl cellulose or the like having high moisture permeability is used as the transparent protective film. When the 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 to each other.

On the other hand, an active energy ray-curable adhesive has been proposed instead of the aqueous adhesive. In the case of producing a polarizing film using an active energy ray-curable adhesive, a drying process is not required, and therefore, the productivity of the polarizing film can be improved. For example, the present inventors have proposed a radical polymerization type active energy ray-curable adhesive using an N-substituted amide monomer as a curable component (patent documents 3 and 4 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. 2012 and 052000

Patent document 4: japanese laid-open patent publication No. 2012 and 068593

Disclosure of Invention

Problems to be solved by the invention

The adhesive layers formed using the active energy ray-curable adhesives described in patent documents 3 and 4 can sufficiently pass, for example, a water resistance test for evaluating the presence or absence of discoloration and peeling after immersion in hot water at 60 ℃ for 6 hours. However, in recent years, further improvement in water resistance to the extent that the peeling of the nail at the end can be evaluated after immersion (saturation) in water, for example, by a more severe water resistance test has been increasingly demanded for adhesives for polarizing films. Therefore, in actual circumstances, there is room for further improvement in water resistance of the adhesives for polarizing films reported so far, including the active energy ray-curable adhesives described in patent documents 3 and 4.

However, in recent years, contradictory (contradictory) properties are often required for organic polymer materials, and it is actually difficult to satisfy the required properties for a single organic polymer material. In order to satisfy contradictory requirements, a technique of adding a different material having different properties to an organic polymer material and compounding the material has been proposed in many fields. In the case of adhering 2 different kinds of adherends in the adhesion technique, for example, it is conceivable to form an adhesive layer into a 2-layer structure in order to improve the adhesiveness to each adherend. However, when the adhesive layer has a 2-layer structure, stress is concentrated on the interface, and the adhesive strength of the adhesive layer may be reduced. In particular, it is difficult to establish a technique for forming an adhesive layer having a 2-layer structure for polarizing films, which have been required to be thinner in recent years.

As described above, in the field of adhesives for polarizing films, which are particularly required to be thin, it is actually difficult to develop a technique for improving the adhesiveness and also improving the water resistance when 2 kinds of adherends different from each other, i.e., a polarizing plate and a transparent protective film, are adhered.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a polarizing film having an adhesive layer exhibiting high adhesive strength and excellent water resistance when a polarizing plate and a transparent protective film are laminated, and a method for producing the polarizing film.

Means for solving the problems

Since the polarizing plate and the transparent protective film, which are members of the polarizing film, exhibit different properties from the viewpoint of hydrophilicity, for example, it is advantageous to form the adhesive layer for laminating these adherends into a 2-layer structure from the viewpoint of improving the adhesive force to both adherends, but as described above, the adhesive force may be rather reduced by interfacial peeling or the like in the adhesive layer.

As a result of intensive studies to solve the above problems, the present inventors have found that if an adhesive layer having a component-inclined structure in which the concentration of a hydrophilic component on the polarizer side is increased is used in the adhesive layer instead of the 2-layer structure, the adhesiveness to a polarizing plate can be improved and the water resistance of the adhesive layer can be improved. The present invention has been completed based on this finding, and has the following configuration.

That is, the present invention relates to a polarizing film in which a transparent protective film is laminated on at least one side of a polarizing plate via an adhesive layer, wherein the adhesive layer is a layer formed of a cured product obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray, the active energy ray-curable adhesive composition contains a component a having a logPow of-1 to 1 and a component B having a logPow of 2 to 7, each representing an octanol/water partition coefficient, and the adhesive layer has a high concentration of the component a on the polarizing plate side.

The adhesive layer of the polarizing film of the present invention is formed of a cured product obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray, wherein the active energy ray-curable adhesive composition contains a component A having a logPow of-1 to 1 and a component B having a logPow of 2 to 7, both of which represent octanol/water distribution coefficients. The polarizing plate, particularly a polyvinyl alcohol polarizing plate, which is an adherend of the adhesive layer exhibits hydrophilicity, and the adhesive layer of the present invention has a high concentration of component A on the polarizing plate side, and the component A has a logPow of-1 to 1, and exhibits high hydrophilicity. Therefore, the component a having particularly strong affinity for the polarizing plate and exhibiting hydrophilicity is more localized at the interface on the polarizing plate side of the adhesive layer, and the adhesive layer and the polarizing plate are strongly adhered. On the other hand, since the adhesive layer provided in the polarizing film of the present invention has a component gradient structure in which the concentration of the component a on the polarizer side is high, the concentration of the component B having a logPow of 2 to 7 and high hydrophobicity on the transparent protective film side is high, in contrast to the high concentration of the component a on the polarizer side. Since the transparent protective film is more hydrophobic than the polarizing plate, the adhesive layer included in the polarizing film of the present invention is also strongly adhered to the transparent protective film, and the water resistance is improved.

As far as the present inventors know, in an adhesive layer provided in a polarizing film which is recently required to be thin, there is no example in which a component-inclined structure in which the concentration of a hydrophilic component on the polarizer side becomes high is employed.

The adhesive layer of the polarizing film of the present invention can be confirmed, for example, by Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) in terms of the concentration of the component A on the polarizer side becoming high and the composition gradient structure in which the concentration of the component A on the polarizer side becomes high. TOF-SIMS is based on the principle that when a sample is irradiated with a primary ion beam (e.g., 1E12 ions/cm) under ultra-high vacuum²Below), only from the outermost surface (depth) of the sample

Left and right) to emit secondary ions, and the secondary ions are introduced into a time-of-flight (TOF) mass spectrometer to obtain a mass spectrum. By using this principle, information on the elemental composition and chemical structure of the compound present on the outermost surface of the sample can be obtained. In the present invention, a cluster ion etching method may be used to confirm that the concentration of the a component on the polarizer side in the adhesive layer is high and that the adhesive layer has a component gradient structure in which the concentration of the a component on the polarizer side is high.

Hereinafter, the "cluster ion etching method" will be described. For example, using a monoatomic ion beam (Ar)⁺、Cs⁺Etc.) when the surface of the adhesive layer is etched by a general etching method used as an etching ion, the molecular structure of the surface of the adhesive layer is broken to form a damaged layer. In this case, even if the mass spectrum of the surface is intended to be obtained by TOF-SIMS, the accurate mass spectrum of the surface of the adhesive layer cannot be measured due to the influence of the damaged layer. On the other hand, the method utilizes "Ar gas cluster ion (Arn)⁺) In the case of the "cluster ion etching method" used as an etching ion, the damage applied to the surface of the etched adhesive layer is reduced, and the damaged layer is not formed, so that the surface of the etched adhesive layer is protectedThe molecular structure of the surface before etching is maintained. Therefore, by using TOF-SIMS, the mass spectrum of the surface of the adhesive layer can be accurately measured.

FIG. 1 is a schematic diagram showing a method for evaluating the increase in the concentration of the component A on the polarizer side in the adhesive layer by TOF-SIMS. Fig. 1 (I) shows an example of a polarizing film of the present invention, in which a transparent protective film 2 is laminated on both surfaces of a polarizing plate 1 via an adhesive layer 3. First, the transparent protective film 2 of the polarizing film given in (I) (the upper transparent protective film 2 in (I) of fig. 1) is cut horizontally with a microtome, and the thickness ((II)) of the transparent protective film 2 in contact with the adhesive layer 3 is reduced. Then, as shown in (III), the composition of the surface of the cut transparent protective film 2 was analyzed by measuring the mass spectrum of the surface by TOF-SIMS. Then, as shown In (IV), the surface of the cut transparent protective film 2 was etched by the "cluster ion etching method", and then the composition of the surface was analyzed by TOF-SIMS. Further, as shown in (V), the surface of the transparent protective film 2 was etched by the "cluster ion etching method" to deposit the surface of the adhesive layer 3 on the transparent protective film 2 side, and the composition of the surface was analyzed by TOF-SIMS. From then on, the etching treatment by the "cluster ion etching method" and the analysis of the composition of the surface of the deposited adhesive layer 3 by TOF-SIMS were repeated, and the etching treatment and the analysis of the composition of the surface of the adhesive layer 3 (and further the polarizing plate 1) were continued until the surface of the polarizing plate finally reached. By the above-described method, it was confirmed that the adhesive layer had a component gradient structure in which the concentration of the a component on the polarizer side was high and the concentration of the a component on the polarizer side was high.

In the polarizing film, when the active energy ray-curable adhesive composition contains a (meth) acrylamide derivative as the component a and when the active energy ray-curable adhesive composition contains a polyfunctional (meth) acrylate as the component B, the adhesive layer is preferably higher in adhesiveness to the polarizing plate and the transparent protective film and water resistance.

In the polarizing film, the active energy ray-curable adhesive composition preferably contains an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer. In the polarizing film, the active energy ray-curable adhesive composition preferably contains a photopolymerization initiator containing a hydroxyl group. When the active energy ray-curable adhesive composition contains an acrylic oligomer obtained by polymerizing a non-polymerizable (meth) acrylic monomer, the components of the adhesive composition interposed between the polarizing plate and the transparent protective film tend to be biased, and the concentration of the component a in the adhesive layer tends to be higher on the polarizing plate side. In addition, when a hydroxyl group-containing photopolymerization initiator is contained as a polymerization initiator, the solubility in the adhesive layer having a high concentration of the component a on the polarizer side is improved, and the curability of the adhesive layer is improved. In these cases, the adhesiveness and water resistance between the adhesive layer and the polarizing plate and the transparent protective film are further improved, which is preferable.

In the polarizing film, the active energy ray-curable adhesive composition preferably contains at least 1 organic metal compound selected from the group consisting of metal alkoxides and metal chelates.

When a polarizing film obtained by laminating a transparent protective film on a polarizing plate with an adhesive layer interposed therebetween is exposed to a dew condensation environment, particularly, adhesive peeling occurs between the adhesive layer and the polarizing plate, and one of the mechanisms thereof can be estimated as follows. First, the moisture having passed through the protective film diffuses in the adhesive layer, and the moisture diffuses toward the polarizing plate interface side. In the conventional polarizing film, the participation of hydrogen bonds and/or ionic bonds in the adhesive force between the adhesive layer and the polarizing plate is large, but the hydrogen bonds and ionic bonds at the interface are dissociated by the moisture diffused to the interface side of the polarizing plate, and as a result, the adhesive force between the adhesive layer and the polarizing plate is reduced. In this case, the adhesive layer may be peeled off from the polarizing plate in a dew condensation environment.

On the other hand, in the polarizing film of the present invention, when the active energy ray-curable adhesive composition contains at least 1 kind of organic metal compound selected from the group consisting of metal alkoxides and metal chelates, the organic metal compound becomes an active metal species due to inclusion of moisture, and as a result, the organic metal compound strongly interacts with both the polarizing plate and the active energy ray-curable component constituting the adhesive layer. Therefore, even if moisture is present at the interface between the polarizing plate and the adhesive layer, they strongly interact with each other via the organic metal compound, and thus the adhesion water resistance between the polarizing plate and the adhesive layer is greatly improved.

In the polarizing film, the metal of the organometallic compound contained in the active energy ray-curable adhesive composition is preferably titanium.

In the polarizing film, it is preferable that the active energy ray-curable adhesive composition contains the metal alkoxide as the organometallic compound, and the number of carbon atoms of an organic group contained in the metal alkoxide is 6 or more.

In the polarizing film, it is preferable that the active energy ray-curable adhesive composition contains the metal chelate as the organometallic compound, and the number of carbon atoms of an organic group of the metal chelate is 4 or more.

The polarizing film preferably contains an alkoxysilyl group-containing compound having a viscosity of 15 mPas or more. When the active energy ray-curable adhesive composition for forming the adhesive layer contains an alkoxysilyl group-containing compound having a viscosity of 15mPa · s or more, the adhesion water resistance between the polarizing plate and the adhesive layer is improved, and the following reasons can be considered. When moisture passes through the protective film and moisture diffuses in the adhesive layer, the alkoxysilane group included in the compound is incorporated with moisture and changed to a silanol group at the interface between the polarizing plate and the adhesive layer, and a covalent bond is formed with a functional group such as a hydroxyl group or a carboxyl group present on the surface of the polarizing plate. In addition, when the viscosity of the alkoxysilyl group-containing compound is 15mPa · s or more (high molecular weight), the fluidity can be maintained in the pre-polymerization stage of the adhesive composition, and the adhesive composition being polymerized and the alkoxysilyl group-containing compound are suitably incompatible in the intermediate stage of the polymerization of the composition, and the alkoxysilyl group-containing compound having a low viscosity (low molecular weight) tends to be more likely to be biased toward the interface of the adherend. Therefore, even if the blending amount is set to be low, since the alkoxysilyl group-containing compound having a viscosity of 15mPa · s or more is biased toward the polarizing plate surface side, more hydrogen bonds and/or ionic bonds and covalent bonds are formed between the polarizing plate and the adhesive layer, and the adhesive water resistance between the polarizing plate and the adhesive layer is greatly improved.

In the polarizing film, the main chain of the alkoxysilyl group-containing compound is preferably an acrylic polymer structure.

In the polarizing film, the storage modulus at 25 ℃ of the adhesive layer obtained by curing the active energy ray-curable adhesive composition is preferably 1.0 × 10⁷Pa or above.

The polarizing film of the present invention can be produced, for example, by a production method comprising: a coating step of coating the active energy ray-curable adhesive composition on at least one surface of the polarizing plate and the transparent protective film; a bonding step of bonding the polarizing plate and the transparent protective film; and a bonding step of irradiating the polarizing plate surface side or the transparent protective film surface side with an active energy ray to cure the active energy ray-curable adhesive composition, and bonding the polarizing plate and the transparent protective film with the adhesive layer interposed therebetween. In particular, in the method for producing a polarizing film of the present invention, it is preferable that the concentration of the component a in the adhesive layer is higher on the polarizer side if the temperature of the active energy ray-curable adhesive composition is adjusted to 15 to 40 ℃ after the coating step and before the adhesion step. In order to adjust the temperature of the active energy ray-curable adhesive composition to 15 to 40 ℃, the temperature of the film to which the adhesive composition is applied may be adjusted by adjusting the temperature in the room in which the film is transported, the temperature of the guide roll, or the like, for example.

The polarizing film of the present invention is characterized in that the concentration of the component a on the polarizer side of the adhesive layer formed after the adhesion step is high. The polarizing film of the present invention can be produced, for example, by the following production method:

the method for producing a polarizing film is a method for producing a polarizing film in which a transparent protective film is laminated on at least one surface of a polarizing plate via an adhesive layer, the adhesive layer being formed of a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray, the method comprising: a first coating step of coating a first active energy ray-curable adhesive composition containing a component A having a logPow of-1 to 1, which represents an octanol/water distribution coefficient, on a bonding surface of the polarizing plate; a second coating step of coating a second active energy ray-curable adhesive composition containing a component B having a logPow of 2 to 7 on the bonding surface of the transparent protective film; a bonding step of bonding the polarizing plate and the transparent protective film; and a bonding step of curing the active energy ray-curable adhesive composition by irradiating the composition with an active energy ray from the polarizing plate surface side or the transparent protective film surface side, and bonding the polarizing plate and the transparent protective film with the adhesive layer interposed therebetween, wherein the concentration of the component a on the polarizing plate side of the adhesive layer formed after the bonding step is high.

In addition, when the adhesive layer has a 2-layer structure, stress is concentrated on the interface thereof as described above, and the adhesive force of the adhesive layer may be reduced. On the other hand, according to this production method, since the first active energy ray-curable adhesive composition and the second active energy ray-curable adhesive composition are bonded in a state of having fluidity, the compatibility is made to some extent between the 2 layers, and therefore, a 2-layer structure is not formed, but a component gradient structure in which the concentration of the component a exhibiting high hydrophilicity on the polarizer side becomes high is formed. Thus, interfacial peeling between the first active energy ray-curable adhesive composition and the second active energy ray-curable adhesive composition does not occur, the polarizing plate and the transparent protective film have good adhesiveness, and the polarizing film has good water resistance.

In the above method for producing a polarizing film, the active energy ray-curable adhesive composition preferably contains at least 1 organic metal compound selected from the group consisting of metal alkoxides and metal chelates.

In the above method for producing a polarizing film, the first active energy ray-curable adhesive composition preferably contains the organometallic compound.

In the above method for producing a polarizing film, the metal of the organometallic compound contained in the active energy ray-curable adhesive composition is preferably titanium.

In the above method for producing a polarizing film, it is preferable that the active energy ray-curable adhesive composition contains the metal alkoxide as the organometallic compound, and the number of carbon atoms of an organic group contained in the metal alkoxide is 6 or more.

In the above method for producing a polarizing film, it is preferable that the active energy ray-curable adhesive composition contains the metal chelate as the organometallic compound, and the number of carbon atoms of an organic group of the metal chelate is 4 or more.

In the above method for producing a polarizing film, it is preferable that the polarizing film contains an alkoxysilyl group-containing compound having a viscosity of 15mPa · s or more.

In the above method for producing a polarizing film, the main chain of the alkoxysilyl group-containing compound is preferably an acrylic polymer structure.

In the method for producing a polarizing film, the storage modulus at 25 ℃ of the adhesive layer obtained by curing the active energy ray-curable adhesive composition is preferably 1.0 × 10⁷Pa or above.

Drawings

FIG. 1 is a schematic view showing a method for evaluating a composition gradient structure of an adhesive layer by TOF-SIMS.

Detailed Description

The polarizing film of the present invention is a polarizing film obtained by laminating a transparent protective film on at least one side of a polarizing plate with an adhesive layer interposed therebetween, wherein the adhesive layer is formed of a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray.

The active energy ray-curable adhesive composition can be broadly classified into an electron beam-curable type, an ultraviolet-curable type, a visible ray-curable type, and the like. Further, ultraviolet-curable adhesives and visible-light-curable adhesives can be classified into radical polymerization-curable adhesives and cationic polymerization-curable adhesives. In the present invention, the active energy ray having a wavelength ranging from 10nm to less than 380nm is expressed as ultraviolet rays, and the active energy ray having a wavelength ranging from 380nm to 800nm is expressed as visible rays.

Examples of the compound constituting the radical polymerization curing adhesive include radical polymerizable compounds. 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. The active energy ray-curable adhesive composition used in the present invention preferably contains a compound having a (meth) acryloyl group as a main component, and specifically, the active energy ray-curable adhesive composition preferably contains 50% by weight or more of the compound having a (meth) acryloyl group, and more preferably contains 80% by weight or more, based on 100% by weight of the total amount of the active energy ray-curable adhesive composition. In the present invention, the term "(meth) acryloyl group" means an acryloyl group and/or a methacryloyl group, and the term "(meth)" means the same as below.

< 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 because it not only ensures adhesiveness to a polarizing plate or various transparent protective films, but also has a high polymerization rate and excellent productivity. Specific examples of the (meth) acrylamide derivative include (meth) acrylamide derivatives having an N-alkyl group 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; (meth) acrylamide derivatives having an N-hydroxyalkyl group 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; (meth) acrylamide derivatives having an N-alkoxy group such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; (meth) acrylamide derivatives having an N-mercaptoalkyl group 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, and N-acryloylpyrrolidine.

Among the above (meth) acrylamide derivatives, from the viewpoint of adhesiveness to a polarizing plate or various transparent protective films, (meth) acrylamide derivatives containing an N-hydroxyalkyl group are preferable, and examples of the monofunctional radical polymerizable compound include various (meth) acrylic acid derivatives having a (meth) acryloyloxy group. Specific 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, (C1-20) alkyl (meth) acrylates such as t-amyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, hexadecyl (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-norbornene-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentenyl (meth) acrylate; (meth) acrylates 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, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and alkylphenoxypolyethylene glycol (meth) acrylate; and the like.

Examples of the (meth) acrylic acid derivative include hydroxyl group-containing (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, hydroxyalkyl (meth) acrylates such as 10-hydroxydecyl (meth) acrylate and 12-hydroxylauryl (meth) acrylate, and [ 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, 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 group-containing (meth) acrylates such as 3-oxetanylmethyl (meth) acrylate, 3-methyloxetanylmethyl (meth) acrylate, 3-ethyloxetanylmethyl (meth) acrylate, 3-butyloxetanylmethyl (meth) acrylate, and 3-hexyloxetanylmethyl (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.

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-caprolactam, and methyl vinylpyrrolidone; vinyl monomers having a nitrogen-containing heterocyclic ring 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 an acetoacetyl group, an alkoxymalonyl group, and a cyanoacetyl group. 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-acetoacetyloxymethylbenzyl) 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 >

Examples of the polyfunctional radical polymerizable compound having two or more functional groups 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 ｃA ethylene oxide adduct di (meth) acrylate, bisphenol ｃA propylene oxide adduct di (meth) acrylate, bisphenol ｃA diglycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, cyclic trimethylolpropane methylal (meth) acrylate, dioxane glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetrｃA (meth) acrylate, dipentaerythritol pentｃA (meth) acrylate, dipentaerythritol hexｃA (meth) acrylate, EO-modified diglycerol tetrｃA (meth) acrylate, etc. (meth) acrylate, Satureacrylate, Saturex acrylate, acrylate-acrylate, acrylate-acrylate manufactured by Tokyo chemical industries, various chemical industries such as acrylate-acrylate (acrylate-synthesized by chemical industries, various chemical industries such as exemplified by ATR-3-acrylate-3-acrylate-R.

The adhesive layer of the present invention has a high concentration of the component a on the polarizer side. In addition, in order to realize a component tilt structure for the component A, the active energy ray-curable adhesive composition contains a component A having a logPow of-1 to 1, which represents an octanol/water distribution coefficient, and a component B having a logPow of 2 to 7 in the adhesive layer.

Octanol/water partition coefficient (logPow) is an index indicating lipophilicity of a substance, and refers to the logarithm of octanol/water partition coefficient. A high logPow means oleophilic, i.e. low water absorption. The logPow value can be measured (by the flask permeation method described in JIS-Z-7260), but can also be calculated by calculation. In this specification, the logPow value calculated by Chem Draw Ultra manufactured by cambridge soft corporation is used.

As the component A having a logPow of-1 to 1, among the above-mentioned radical polymerizable compounds, a compound having a logPow of-1 to 1 can be used, and specific examples thereof include hydroxyethylacrylamide (trade name "HEAA", manufactured by Kyowa Kaisha, ACR.84, manufactured by ACR.O.W.: 0.56), N-vinylformamide (trade name "Beamset 770", manufactured by Zakawa Kagaku K.K., L, o.P.: 0.25), acryloylmorpholine (trade name "ACMO", manufactured by Kyowa Kaisha, L, 0, 20), γ -butyrolactone acrylate (trade name "GB 89631A", manufactured by Kagaka Orobao Chemicals, L, 2, Ogaku Kogyo.K.: 0.19), acrylic acid dimer (trade name "β -CEA", manufactured by Daicel, L, 3, 0.2), N-vinylpyrrolidone (trade name "NVP", manufactured by Japan, L, Ogaku Kogyo.24), acetoacetoxy ethyl methacrylate (trade name "TAIkara.7, manufactured by Takara.7, manufactured by Takara.8, a.8, a derivative of acrylamide (trade name" OSC.: a.8, a derivative of a.8, a derivative of a.8, a derivative of a derivative, a derivative of a polyacrylamide (a derivative of a derivative, a derivative of a polyacrylamide (SAG.8, a.8, a derivative of a.8, a derivative of a.8, a derivative, a.8, a derivative of a polyacrylamide (a derivative of a.6, a derivative of a polyacrylamide (see, a derivative of a derivative.

In order to improve the adhesive strength and water resistance of the adhesive layer, the content of the component A having a logPow of-1 to 1 is preferably 5 to 50 wt%, more preferably 10 to 45 wt%, based on 100 wt% of the total amount of the active energy ray-curable adhesive composition.

Examples of the component B having ｃA logPow of 2 to 7 include compounds having ｃA logPow of 2 to 7 among the radical polymerizable compounds described above, specifically dicyclopentenyl acrylate (trade name "FANCRY L FA-511 AS", manufactured by Hitachi chemical Co., Ltd., L OGPo Pow: 2.26), butyl acrylate (trade name "ACRY L0 IC ACID BUTY L1", manufactured by Mitsubishi chemical Co., Ltd., L2 OGPo Pow: 2.35), 1, 6-hexanediol diacrylate (trade name "L3 IGHT ACRY L4-4 ATE1.6HX-A", manufactured by Co., Ltd., ATE1.6HX OGPo Po 72, 2.43), dicyclopentenyl acrylate (trade name "FANCRY ATE1.6HX FA-513 AS", manufactured by Kogyo chemical Co., trade name "POFO 72", bisphenol A-ATE1.6HX ", bisphenol A-A adduct, bisphenol A-acrylate (trade name" POFOROYO-POFO chemical Co., POFO 52-A), bisphenol A-A adduct, POFO-A ", manufactured by Nomex chemical Co., POFO chemical Co., Ltd., POFO.72", AS bisphenol A.72, ｃA adduct, ｃA bisphenol A.72, ｃA, bisphenol A-A.72, POFO.72, ｃA, bisphenol A-POFO.72, ｃA, POFO.72, POFO.A.72, POFO.72, POFO.A.A.72, POFO.72, POFO.A.A.A.2.2.72, POFO.72, POFO.2.72, POFO.72, POFO.2.72, POFO.72, POFO.2.2.72, POFO.72, POFO.2.72, POFO.72, POFO.2.2.2.2.72, POFO.72, POFO.FO.72, POFO.72, POFO.2.2.2.A.72, POFO.A.2.2.72, POF.A.A.72, POF, POF.72, POFO.72, POF.72, POF..

In order to improve the adhesive strength and water resistance of the adhesive layer, the content of the component B having a logPow of 2 to 7 is preferably 30 to 95 wt%, more preferably 40 to 80 wt%, based on 100 wt% of the total amount of the active energy ray-curable adhesive composition.

The active energy ray-curable adhesive composition does not need to contain a photopolymerization initiator when an electron beam or the like is used as an active energy ray, and preferably contains a photopolymerization initiator when ultraviolet rays or visible rays are used as an active energy ray.

< photopolymerization initiator >

When a radical polymerizable compound is used, a photopolymerization initiator which is cleaved with ultraviolet or visible light rays can be suitably selected depending on the active energy rays, and when the compound is cured with ultraviolet or visible light rays, a photopolymerization initiator which is cleaved with ultraviolet or visible light rays can be used, and 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' -dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α -hydroxycyclohexylphenylketone, benzoine-based compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [ 4- (methylthio) -phenyl ] -2-morpholinyl-1-acetone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin, benzoin methyl ether, benzoin-2-morpholino-1-acetone, benzoin-methyl ether-propyl-2-dimethylthioxanthone, 2-oxone-methyl ketone, 2-dimethylthioxanthone, 2-carbonylthioxanthone, 2-dimethylthioxanthone, and the like, 2-dimethylthioxanthone, optically active ketone, 2-chlorothioxanthone, 2-dimethylthioxanthone, and the like, 2-chlorothioxanthone, and the like, the like aromatic ketone compounds such as the like, the optically active benzophenone-thionaphthone, the compound.

The amount of the photopolymerization initiator is 20% by weight or less based on the total amount of the active energy ray-curable adhesive composition taken as 100% by weight. The amount of the photopolymerization initiator is preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and still more preferably 0.1 to 5% by weight.

When the curable adhesive for polarizing films of the present invention is used in a visible light curable type 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. The photopolymerization initiator having high sensitivity to light of 380nm or more will be described later.

As the photopolymerization initiator, a compound represented by the following general formula (1) is preferably used 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. When the compound represented by the general formula (1) is used, the adhesiveness is superior to that when a photopolymerization initiator highly sensitive 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 composition 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, a polymerization initiation aid is preferably added as needed. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., and ethyl 4-dimethylaminobenzoate is particularly preferable. When a 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.

Specific examples of the photopolymerization initiator include 2-methyl-1- (4-methylthiophenyl) -2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [ 4- (4-morpholino) phenyl ] -1-butanone, 2, 4, 6-trimethylbenzoyl-diphenylphosphine oxide, bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide, bis (η 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, it is preferable to use a compound represented by the following general formula (2) in addition to the photopolymerization initiator of the general formula (1):

[ 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), 2-methyl-1- (4-methylthiophenyl) -2-morpholino-1-propanone (trade name: IRGACURE907 manufacturer: BASF), which is also commercially available, can be suitably used. In addition thereto, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone (trade name: IRGACURE369, manufacturer: BASF), 2- (dimethylamino) -2- [ (4-methylphenyl) methyl]-1- [ 4- (4-morpholinyl) phenyl]-1-butanone (trade name: IRGACURE379 manufacturer: BASF) is preferred because of its high sensitivity.

In the present invention, among the above photopolymerization initiators, a photopolymerization initiator containing a hydroxyl group is preferably used. When the active energy ray-curable adhesive composition contains a hydroxyl group-containing photopolymerization initiator as a polymerization initiator, the solubility in the adhesive layer having a high concentration of the component a on the polarizer side is improved, and the curability of the adhesive layer is improved. Examples of the photopolymerization initiator having a hydroxyl group include 2-methyl-2-hydroxypropiophenone (trade name "DAROCUR 1173", manufactured by BASF), 1-hydroxycyclohexyl phenyl ketone (trade name "IRGACURE 184", manufactured by BASF), 1- [ 4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-1-propanone (trade name "IRGACURE 2959", manufactured by BASF), and 2-hydroxy-1- { 4- [ 4- (2-hydroxy-2-methyl-propionyl) -benzyl ] phenyl } -2-methyl-1-propanone (trade name "IRGACURE 127", manufactured by BASF). In particular, 1-hydroxycyclohexylphenylketone is more preferable because it is particularly excellent in solubility in an adhesive layer having a high concentration of component a.

< radical polymerizable Compound having active methylene group and radical polymerization initiator having dehydrogenation action >

In the active energy ray-curable adhesive composition, when a radical polymerizable compound having an active methylene group is used as the radical polymerizable compound, it is preferable to use the radical polymerizable compound in combination with a radical polymerization initiator having a dehydrogenation function. With this configuration, the adhesiveness of the adhesive layer of the polarizing film is significantly improved even immediately after the polarizing film is taken out from a particularly high-humidity environment or water (non-dried state). Although the reason for this is not clear, the following reason can be considered. That is, it is presumed that the radical polymerizable compound having an active methylene group is polymerized together with other radical polymerizable compounds constituting the adhesive layer and is introduced 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, if a radical polymerization initiator having a dehydrogenation function is present, hydrogen is removed from a radical polymerizable compound having an active methylene group while forming a base polymer constituting the adhesive layer, and radicals are generated in the methylene group. Thereafter, the methylene group having generated the radical reacts with the 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, 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 having a dehydrogenation function include a thioxanthone-based radical polymerization initiator, a benzophenone-based radical polymerization initiator, and the like. The radical polymerization initiator is preferably a thioxanthone-based 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).

In the active energy ray-curable adhesive composition, when the composition contains a radical polymerizable compound having an active methylene group and a radical polymerization initiator having a dehydrogenation function, the radical polymerizable compound having an active methylene group is preferably contained in an amount of 1 to 50% by weight based on 100% by weight of the total amount of the curable components, and the radical polymerization initiator is preferably contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the curable components.

As described above, in the present invention, in the presence of a radical polymerization initiator having a dehydrogenation function, a methylene group of a radical polymerizable compound having an active methylene group is caused to generate a radical, and the methylene group reacts with a hydroxyl group of a polarizing plate such as PVA to form a covalent bond. Therefore, in order to generate radicals from the methylene group of the radical polymerizable compound having an active methylene group and to form the covalent bond sufficiently, the radical polymerizable compound having an active methylene group is preferably contained in an amount of 1 to 50% by weight, more preferably 3 to 30% by weight, based on 100% by weight of the total amount of the curable components. In order to improve the adhesiveness in a non-dried state by sufficiently improving the water resistance, it is preferable to set the radical polymerizable compound having an active methylene group to 1% by weight or more. On the other hand, if the amount is more than 50% by weight, poor curing of the adhesive layer may occur. The radical polymerization initiator 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 a radical polymerization initiator. On the other hand, if it is more than 10 parts by weight, it may not be completely dissolved in the composition.

< cationic polymerization curing type adhesive >

Examples of the curable component of the cationic polymerization curable adhesive include compounds having an epoxy group or an oxetanyl 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. Preferable epoxy compounds include compounds having at least 2 epoxy groups and at least 1 aromatic ring in the molecule (aromatic epoxy compounds); a compound having at least 2 epoxy groups in the molecule, at least 1 of which is formed between 2 adjacent carbon atoms constituting the alicyclic ring (alicyclic epoxy compound), and the like. However, in order to realize a component-inclined structure with respect to the component A in the adhesive layer, even when a cationic polymerization-curable adhesive is used, the active energy ray-curable adhesive composition needs to contain the component A having a logPow of-1 to 1, which represents an octanol/water partition coefficient, and the component B having a logPow of 2 to 7.

< photo cation polymerization initiator >

The cationic polymerization-curable adhesive contains the above-described epoxy compound and oxetane compound as curable components, and both are compounds cured by cationic polymerization, and therefore 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 rays, ultraviolet rays, X-rays, electron beams, etc., and initiates a polymerization reaction of an epoxy group or an oxetanyl group.

< at least 1 organometallic compound selected from metal alkoxides and metal chelates >

The metal alkoxide is a compound in which at least one alkoxy group as an organic group is bonded to a metal, and the metal chelate is a compound in which an organic group is bonded or coordinated to a metal through an oxygen atom. The metal is preferably titanium, aluminum, or zirconium. Among them, aluminum and zirconium are more reactive than titanium, and the pot life of the adhesive composition is shortened, and the effect of improving the adhesive water resistance may be reduced. Therefore, titanium is more preferable as the metal of the organic metal compound from the viewpoint of improving the adhesion water resistance of the adhesive layer.

When the curable adhesive composition for a polarizing film of the present invention contains a metal alkoxide as an organometallic compound, a compound having an organic group of a metal alkoxide and having 4 or more carbon atoms is preferably used, and a compound having 6 or more carbon atoms is more preferably contained. If the number of carbon atoms is 3 or less, the pot life of the adhesive composition may be shortened, and the effect of improving the adhesive water resistance may be reduced. Examples of the organic group having 6 or more carbon atoms include an octyloxy group, and the organic group can be suitably used. Examples of suitable metal alkoxides include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetraoctyl titanate, tert-amyl titanate, tetra-tert-butyl titanate, tetrastearyl titanate, tetraisopropoxy zirconium, tetra-n-butoxy zirconium, tetraoctyloxy zirconium, tetra-tert-butoxy zirconium, tetrapropoxy zirconium, sec-butoxy aluminum, ethoxy aluminum, isopropoxy aluminum, butoxy aluminum, mono-sec-butoxy diisopropoxy aluminum, diisopropoxy mono-sec-butoxy aluminum, and the like. Among them, tetraoctyl titanate is preferable.

When the curable adhesive composition for a polarizing film of the present invention contains a metal chelate as an organometallic compound, it preferably contains a compound in which the number of carbon atoms of an organic group contained in the metal chelate is 4 or more. If the number of carbon atoms is 3 or less, the pot life of the adhesive composition may be shortened, and the effect of improving the adhesive water resistance may be reduced. Examples of the organic group having 4 or more carbon atoms include an acetylacetonato group, an ethylacetoacetate group, an isostearate group, and an octyleneglycolate group. Among them, from the viewpoint of improving the adhesive water resistance of the adhesive layer, an acetylacetonato group or an ethylacetoacetate group is preferable as the organic group. Examples of suitable metal chelates include titanium acetylacetonate, titanium octylene glycolate, titanium tetraacetylacetonate, titanium ethylacetoacetate, titanium polyhydroxystearate, dipropoxy-bis (acetylacetonato) titanium, dibutyl bis (octylene glycolate) titanate, dipropyl bis (acetoacetato) titanate, titanium lactate, titanium diethanolamine, titanium triethanolamine, dipropyl bis (lactate) titanate, dipropyl bis (triethanolamine) titanate, di-n-butyl bis (triethanolamine) titanate, tri-n-butyl monostearate, diisopropyl bis (acetoacetato) titanate, diisopropyl bis (acetylacetonato) titanate, titanium phosphate compound, titanium ammonium lactate, 1, 3-propylenedioxy titanium bis (ethylacetoacetate), titanium dodecylbenzenesulfonate titanium compound, Titanium aminoethylaminoglycolate, zirconium tetraacetoacetate, zirconium monoacetylacetonate, zirconium bisacetoacetonate, zirconium bis (ethylacetoacetate) (acetylacetonate), zirconium acetate, tri-n-butyl (ethylacetoacetate) zirconate, zirconium tetra-n-propyl (acetoacetate), zirconium tetra (acetoacetoacetate), zirconium tetra (ethylacetoacetate), aluminum ethylacetoacetate, aluminum acetylacetonate, aluminum bis (ethylacetoacetate) acetylacetonate, diisopropyl acetoacetate aluminate, diisopropyl acetylacetonate, isopropyl bis (ethylacetoacetate) aluminate, isopropyl bis (acetylacetonate) aluminate, aluminum tris (ethylacetoacetate), aluminum tris (acetylacetonate), aluminum bis (ethylacetoacetate) monoacetylacetonate. Among them, titanium acetylacetonate and titanium ethyl acetoacetate are preferable.

The organic metal compounds usable in the present invention include, in addition to the above, metal salts of organic carboxylic acids such as zinc octanoate, zinc laurate, zinc stearate and tin octanoate, zinc chelate compounds such as zinc acetylacetonate chelate, zinc benzoylacetonate chelate, zinc dibenzoylmethane chelate and ethyl zinc acetoacetate chelate.

< other ingredients >

The active energy ray-curable adhesive composition of the present invention may contain the following components.

< alkoxysilyl group-containing compound having viscosity of 15 mPas or more >

As the alkoxysilyl group-containing compound having a viscosity of 15mPa · s or more, a compound having a higher molecular weight than that of the alkoxysilyl group-containing low-molecular weight compound can be used, and in particular, a polymer having an alkoxysilyl group at a side chain and/or a molecular terminal, or an oligomer-type alkoxysilyl group-containing compound can be suitably used.

As the polymer having an alkoxysilyl group at a side chain and/or a molecular terminal, a polymer having a main chain of a (meth) acrylic polymer structure can be suitably used. Examples of the (meth) acrylic monomer constituting the acrylic polymer include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, tolyl (meth) acrylate, benzyl (meth) acrylate, (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, stearyl (meth) acrylate and isostearyl (meth) acrylate. In the present invention, the term "(meth) acryloyl group" means an acryloyl group and/or a methacryloyl group, and the same shall apply to the following "(meth)".

The viscosity of the polymer having an alkoxysilyl group at a side chain and/or a molecular terminal is preferably 15mPa · s or more, more preferably 10000mPa · s or more, and still more preferably 100000mPa · s or more. The upper limit of the viscosity is not particularly limited, but is preferably 2000000 mPas or less in view of handling properties and the like.

Examples of the oligomer-type alkoxysilyl group-containing compound include a hydrolysis condensate of a low-molecular-weight alkoxysilyl group-containing compound. As the hydrolysis condensate of the alkoxysilyl group-containing compound having a low molecular weight, commercially available products can be suitably used, and examples thereof include X-41-1059A, X-24-9590, KR-516, X-41-1805, KR513, X-40-9296, KR-511, KR-500, X-40-9225, X-40-9246, X-40-9250, KR-401N, X-40-9227, KR-510, KR-9218, and KR-213, all manufactured by shin-Etsu chemical Co., Ltd.

The viscosity of the oligomeric alkoxysilyl group-containing compound is preferably 15mPa · s or more, more preferably 20mPa · s or more, and still more preferably 25mPa · s or more. The upper limit of the viscosity is not particularly limited, but is preferably 100000mPa · s or less in consideration of handling properties and the like.

In the present invention, the content of the alkoxysilyl group-containing compound having a viscosity of 15mPa · s or more is preferably in the range of 0.2 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 0.8 to 5 parts by weight, based on 100 parts by weight of the total amount of the active energy ray-curable components. This is because if the amount is more than 15 parts by weight, the storage stability of the adhesive composition is deteriorated, or the ratio of the components for adhesion to the polarizing plate or the protective film is relatively insufficient, which may cause a decrease in adhesiveness. When the amount is less than 0.2 parts by weight, the effect of adhesion and water resistance cannot be sufficiently exhibited.

< acrylic oligomer >

The active energy ray-curable adhesive composition used in the present invention may contain an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer, in addition to the curable component of the radical polymerizable compound or the cationic polymerization-curable adhesive. When the active energy ray-curable adhesive composition contains an acrylic oligomer obtained by polymerizing a non-polymerizable (meth) acrylic monomer, the components of the adhesive composition interposed between the polarizing plate and the transparent protective film are easily biased, and a component-inclined structure in which the concentration of the component a on the polarizing plate side is high is more easily obtained. This is preferable because the adhesiveness and water resistance between the adhesive layer and the polarizing plate and the transparent protective film are further improved. Further, by containing an acrylic oligomer component in the active energy ray-curable adhesive composition, the curing shrinkage when the composition is cured by irradiation with active energy rays 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 more reliably obtain a component-inclined structure of the cured product layer (adhesive layer) and to sufficiently suppress curing shrinkage, the content of the acrylic oligomer is preferably 5 to 30 wt%, more preferably 10 to 20 wt%, when the total amount of the active energy ray-curable adhesive composition is 100 wt%.

In view of workability and uniformity in coating, the active energy ray-curable adhesive composition is preferably low in viscosity, and the acrylic oligomer (a) obtained by polymerizing a (meth) acrylic monomer is preferably a low-viscosity acrylic oligomer having a weight average molecular weight (Mw) of 15000 or less, more preferably 10000 or less, particularly preferably 5000 or less, and in order to further advance the components of the adhesive composition interposed between the polarizing plate and the transparent protective film, the acrylic oligomer (a) preferably has a weight average molecular weight (Mw) of 500 or more, more preferably 1000 or more, and particularly preferably 1500 or more, and the (meth) acrylic monomers constituting the acrylic oligomer (a) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-amyl (meth) acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, 2-nitro-propyl (meth) acrylate, 2-ethyl (meth) acrylate, 2-methyl (meth) acrylate, such as the ester of acrylic acid, 2-glycidyl (meth) acrylate, 2-glycidyl methacrylate, 2-methyl (meth-2-ethyl methacrylate, 2-ethyl methacrylate, and the like, for example, 2-ethyl (meth-2-ethyl methacrylate) acrylate, 2-ethyl methacrylate, such as the compound containing glycidyl methacrylate, can be used as the compound (acrylate alone, such as the compound (acrylate, and the compound containing a-2-n-ethyl methacrylate, for example, 2-ethyl methacrylate, such as the compound (meth-2-n-ethyl methacrylate) acrylate, 2-ethyl methacrylate, and the compound, such as the compound (meth-ethyl methacrylate, 2-ethyl methacrylate, and the compound (acrylate, such as the compound (acrylate, for example, 2-ethyl methacrylate, 2-n-ethyl methacrylate, 2-n-butyl (acrylate, 2-n-ethyl methacrylate) acrylate, 2-butyl (meth-ethyl methacrylate) acrylate, 2-n-butyl (acrylate, 2-n-butyl methacrylate) acrylate.

When the acrylic oligomer (a) is a liquid, it is not necessary to consider the solubility in the adhesive composition, and therefore it can be suitably used. The acrylic oligomer (A) is usually liquid in the case where the glass transition temperature (Tg) is lower than 25 ℃. In order to achieve compatibility with the adhesive composition and balance of components in the adhesive layer, the acrylic oligomer (a) preferably contains a polar functional group. Examples of the polar functional group include a hydroxyl group, an epoxy group, a carboxyl group, and an alkoxysilyl group. Specifically, examples thereof include "ARUFON UH series", "ARUFON UC series", "ARUFON UF series", "ARUFON UG series", and "ARUFON US series" (all manufactured by east Asia Co., Ltd.). Among them, epoxy groups are preferably contained because an improvement in adhesiveness due to interaction with a polarizing plate is expected. Specific examples thereof include "ARUFON UG-4000" and "ARUFON UG-4010" (both manufactured by Toyo chemical Co., Ltd.).

< photoacid generators >

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

General formula (3)

[ solution 3]

L⁺X^-

(wherein, L⁺Represents an arbitrary onium cation. In addition, X^－Is selected from PF6₆ ^－、SbF₆ ^－、AsF₆ ^－、SbCl₆ ^－、BiCl₅ ^－、SnCl₆ ^－、ClO₄ ^－Dithiocarbamate anion, SCN^－The counter anion of (1). )

Among the above-mentioned exemplary anions, the counter anion X in the general formula (3) is particularly preferably used^－Examples of the anion of (2) include PF₆－、SbF₆ ^－And AsF₆ ^－Particularly preferred is PF₆ ^－、SbF₆ ^－。

Thus, examples of preferred onium salts constituting the photoacid generator usable in the present invention include "CYRACURE UVI-6992", "CYRACURE UVI-6974" (manufactured by DOW CHEMICA L Japan K.K.), "Adeka Optimer SP 150", "Adeka Optimer SP 152", "Adeka Optimer SP 170", "Adeka Optimer SP 172" (manufactured by ADEKA K.K.), "IRGACURE 250" (manufactured by Ciba Specialty Chemicals), "CI-5102", "CI-2855" (manufactured by Nippon Cao.K.), "Sunaid SI-60L", "Sunaid SI-80L", "Sunaid SI-100L", "Sunaid SI-110L", "Sunaid SI-180L" (manufactured by Sanxin Chemicals), "WPI-100P 064", "WPI-04116", "WPI-100P" (manufactured by WPI-100 WPI), and "WPI-054", and "WPI-567".

The content of the photoacid generator 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 containing any of alkoxy group and epoxy group >

In the active energy ray-curable adhesive composition, a photoacid generator and any compound containing an alkoxy group or an epoxy group may be used in combination.

(Compound having epoxy group and Polymer)

When a compound having 1 or more epoxy groups in a molecule or a polymer (epoxy resin) having 2 or more epoxy groups in a molecule is used, a compound having two or more functional groups reactive with epoxy groups in a molecule may be used in combination. Examples of the functional group having reactivity with an epoxy group include a carboxyl group, a phenolic hydroxyl group, a mercapto group, and a 1-or 2-stage aromatic amino group. In view of three-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, P-phenylene type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, fluorene type epoxy resins, 3-functional epoxy resins, 4-functional epoxy resins and other multifunctional 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, which may be halogenated or hydrogenated, and commercially available epoxy resin products such as epoxy resins of the series of epoxy series of the series of epoxy resins, e.g., the series of epoxy resins of the series of epoxy resins produced by deutoyoxylex series of the series of chemicals, e.g., epoxy resins of epoxy series of epoxy resins of the series of epoxy resins produced by deutov. No. 21, No. hei series, No. 21, No. 3, No. and No. 3, No. series of epoxy series produced by deutoyodyfine series of epoxy series, No. the series of epoxy series of the series of epoxy series of the series of chemicals EP-series of the series of epoxy series of the series of chemicals EP-series of the series of chemicals, No. kayodyno. 3, No. the series of.

(Compound having alkoxy group and Polymer)

The compound having an alkoxy group in the molecule is not particularly limited as long as it has 1 or more alkoxy groups in the molecule, and known compounds can be used. Representative examples of such compounds include melamine compounds, amino resins, and silane coupling agents.

The amount of the compound containing any of an alkoxy group and 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 in the composition is too large, the adhesiveness is lowered, and the impact resistance in the drop test may be deteriorated. The content of the compound in the composition is more preferably 20 parts by weight or less. On the other hand, the compound is preferably contained in the composition in an amount of 2 parts by weight or more, more preferably 5 parts by weight or more, from the viewpoint of water resistance.

< silane coupling agent >

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, 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 include 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 3-acryloxypropyltrimethoxysilane, which are active energy ray-curable compounds.

3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane are preferred.

As a specific example of the silane coupling agent which is not curable with active energy rays, a silane coupling agent having an amino group (D1) is preferable. Specific examples of the silane coupling agent having an amino group (D1) 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, 3- (N-ethylamino) -2-methylpropyltrimethoxysilane, Amino group-containing silanes such as γ -ureidopropyltrimethoxysilane, γ -ureidopropyltriethoxysilane, N-phenyl- γ -aminopropyltrimethoxysilane, N-benzyl- γ -aminopropyltrimethoxysilane, N-vinylbenzyl- γ -aminopropyltriethoxysilane, N-cyclohexylaminomethyl-triethoxysilane, N-cyclohexylaminomethyl-diethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl) aminomethyl-trimethoxysilane, 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 (D1) may be used alone in 1 kind or in combination of two or more kinds. Among them, in order to ensure good adhesiveness, 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 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 the storage stability of the adhesive is deteriorated when the amount is more than 20 parts by weight, and the effect of the water-resistant tackiness cannot be sufficiently exhibited when the amount is less than 0.1 part by weight.

Specific examples of the silane coupling agent other than those described above which are not active energy ray-curable include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazolesilane.

< Compound having vinyl Ether group >

When the curable adhesive composition for a polarizing film of the present invention contains a compound having a vinyl ether group, the water resistance of adhesion between the polarizing plate and the adhesive layer is improved, and therefore, the composition is preferable. Although the reason why this effect can be obtained is not clear, it is presumed that one of the reasons is that the vinyl ether group of the compound having a vinyl ether group interacts with the polarizing plate to improve the adhesive strength between the polarizing plate and the adhesive layer. In order to further improve the water resistance of the adhesion between the polarizing plate and the adhesive layer, the compound having a vinyl ether group is preferably a radical polymerizable compound having a vinyl ether group. The content of the compound having a vinyl ether group is preferably 0.1 to 19 parts by weight based on 100 parts by weight of the total amount of the curable components.

< Compound producing keto-enol tautomerism >

The curable adhesive composition for a polarizing film of the present invention may contain a compound which causes keto-enol tautomerism. For example, in an adhesive composition containing a crosslinking agent or an adhesive composition which can be used in combination with a crosslinking agent, a form containing a compound which causes the keto-enol tautomerism described above can be preferably used. This suppresses excessive increase in viscosity and gelation of the adhesive composition containing the organometallic compound, and formation of a microgel, and thus can achieve an effect of prolonging the pot life of the composition.

As the compounds generating the ketone-enol tautomerism, various β -dicarbonyl compounds can be used, specific examples include β -diones such as acetylacetone, 2, 4-hexanedione, 3, 5-heptanedione, 2-methyl-3, 5-hexanedione, 6-methyl-2, 4-heptanedione, 2, 6-dimethyl-3, 5-heptanedione, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, tert-butyl acetoacetate, and other acetoacetate esters, propionyl acetate esters such as ethyl propionylacetate, isopropyl propionylacetate, tert-butyl propionylacetate, and other isobutyrylacetate esters, malonic esters such as methyl malonate, ethyl malonate, and other malonate esters, and among them, acetylacetone and acetoacetate esters can be used alone or in combination of 2 or more.

The amount of the compound which causes keto-enol tautomerism can be, for example, 0.05 to 10 parts by weight, preferably 0.2 to 3 parts by weight (for example, 0.3 to 2 parts by weight) relative to 1 part by weight of the organometallic compound. If the amount of the above compound is less than 0.05 part by weight based on 1 part by weight of the organometallic compound, it may be difficult to exhibit sufficient effect in use. On the other hand, if the amount of the compound used is more than 10 parts by weight relative to 1 part by weight of the organometallic compound, the compound may interact with the organometallic compound too much to exhibit desired water resistance.

Additives other than the above

In addition, in the active energy ray-curable adhesive composition used in the present invention, various additives may be blended as other optional components within a range not impairing the object and effect of the present invention. Examples of the additive include polymers or oligomers such as epoxy resins, polyamides, polyamideimides, polyurethanes, polybutadienes, polychloroprenes, polyethers, polyesters, styrene-butadiene block copolymers, petroleum resins, xylene resins, ketone resins, cellulose resins, fluorine-based oligomers, silicone-based oligomers, and polythioether-based oligomers; 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.

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 active energy ray-curable adhesive composition used in the present invention contains the curable component, and from the viewpoint of coatability, the viscosity of the adhesive composition is preferably 100cp or less at 25 ℃, and on the other hand, when the curable adhesive for polarizing film of the present invention is more than 100cp at 25 ℃, the temperature of the adhesive may be controlled and adjusted to 100cp or less at the time of coating, and the viscosity may be measured using an E-viscometer TVE 22L T manufactured by eastern industries, more preferably, the range of the viscosity is 1 to 80cp, and most preferably, the viscosity is 10 to 50 cp..

In addition, from the viewpoint of safety, it is preferable to use a material having low skin irritation as the curable component in the active energy ray-curable adhesive composition used in the present invention. Skin irritation can be judged by using an index such as p.i.i.i. P.i.i. is widely used as an index indicating the degree of skin disorders and is measured by the Draize method. The measurement value is represented by a range of 0 to 8, and the smaller the value, the lower the irritation, but the larger the error of the measurement value, and therefore, it is desirable to understand the value 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.

The polarizing film of the present invention is a polarizing film in which a transparent protective film is laminated on at least one surface of a polarizing plate with an adhesive layer interposed therebetween, and the adhesive layer has a high concentration of component a on the polarizing plate side. The concentration distribution in the thickness direction of the adhesive layer can be analyzed by alternately repeating etching using cluster ions and TOF-SIMS measurement, for example. Specifically, a specific secondary ion is selected for each component of the adhesive composition, and the components that are partially offset in the thickness direction can be identified by comparing the strength ratios of the secondary ions in the thickness direction. The evaluation is carried out by calculating the ratio of the component A in the interface on the polarizer side of the adhesive layer, assuming that the ratio of the component A having a logPow of-1 to 1 in the central part of the adhesive layer in the thickness direction is 1. When the ratio of the a component in the polarizer-side interface of the adhesive layer is greater than 1, it means that the concentration of the a component on the polarizer side of the adhesive layer is high. The ratio of the component a in the polarizer-side interface is preferably 1.05 or more, more preferably 1.10 or more, and most preferably 1.20 or more.

< adhesive layer >

The thickness of the adhesive layer formed by the active energy ray-curable adhesive composition 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 cohesive force of the adhesive layer and to suppress the occurrence of appearance failure (air bubbles) during lamination. On the other hand, if the thickness of the adhesive layer is more than 3 μm, the polarizing film may not satisfy durability.

The active energy ray-curable adhesive composition is preferably selected so that the Tg of the adhesive layer formed from the composition 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 the Tg of the adhesive layer is too high, the bendability of the polarizing film decreases, and therefore the Tg of the adhesive layer is preferably 300 ℃ or less, more preferably 240 ℃ or less, and even more preferably 180 ℃ or less. The Tg (glass transition temperature) was measured under the following measurement conditions using a dynamic viscoelasticity measuring apparatus RSAIII manufactured by TA Instruments.

Sample size: 10mm wide and 30mm long,

The distance between the clamps is 20mm,

Measurement mode: stretching and 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.

In addition, the active energy ray-curable adhesive composition is preferably designed such that the storage modulus of the adhesive layer formed from the composition is 1.0 × 10 in the region of 70 ℃ or lower⁶Pa or more, more preferably 1.0 × 10⁷Pa or above. The storage modulus of the adhesive layer affects the polarizer cracks when a thermal cycle is applied to the polarizing film (-40 ℃ to 80 ℃ or the like), and when the storage modulus is low, the polarizer cracks are liable to occur. The temperature region having a high storage modulus is more preferably 80 ℃ or less, most preferably 90 ℃ or less. The storage modulus was measured under the same measurement conditions using a dynamic viscoelasticity measuring apparatus RSAIII manufactured by TA Instruments together with Tg (glass transition temperature). The dynamic viscoelasticity was measured by using the value of the storage modulus (E').

The polarizing film of the present invention can be produced, for example, by a method for producing a polarizing film comprising: a coating step of coating an active energy ray-curable adhesive composition on at least one surface of the polarizing plate and the transparent protective film; a bonding step of bonding the polarizing plate and the transparent protective film; and a bonding step of curing the active energy ray-curable adhesive composition by irradiating the composition with active energy rays from the polarizing plate surface side or the transparent protective film surface side, and bonding the polarizing plate and the transparent protective film with the adhesive layer interposed therebetween.

In the adhesive layer of the present invention, in order to increase the concentration of the component a on the polarizer side, it is preferable to adjust the temperature of the active energy ray-curable adhesive composition to 15 to 40 ℃ after the coating step and before the adhesion step. The reason why the temperature condition is preferably set is as follows.

In order to increase the concentration of the component a on the polarizer side in the adhesive layer, it is necessary to form a component-inclined structure of the component a and the component B during the period from after the coating step to before the bonding step, that is, in the stage of the adhesive composition consisting of the monomer component before the polymerization of the adhesive composition is started. Generally, if the temperature of a composition containing 2 or more components is high, the components are easily compatible with each other, and as a result, it is difficult to obtain a component-inclined structure. Accordingly, in the method for producing a polarizing film of the present invention, the temperature of the active energy ray-curable adhesive composition is adjusted to 15 to 40 ℃ after the application step and before the adhesion step, whereby the components a and B are not completely compatible with each other, and as a result, the component gradient structure of the components a and B is easily formed. In order to more reliably form the component gradient structure of the component A and the component B, the temperature of the active energy ray-curable adhesive composition is more preferably adjusted to 20 to 35 ℃ and still more preferably adjusted to 23 to 32 ℃ after the application step and before the adhesion step.

In addition, as a method of setting the temperature of the active energy ray-curable adhesive composition within the above range, for example, a method of setting the atmospheric temperature at the time of performing each step within the above range can be cited.

The polarizing film of the present invention can be produced by the following method for producing a polarizing film:

the method for producing a polarizing film is characterized in that a transparent protective film is laminated on at least one surface of a polarizing plate via an adhesive layer, the adhesive layer being a layer formed from a cured product obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray, and the method for producing a polarizing film comprises: a first coating step of coating a first active energy ray-curable adhesive composition containing a component A having a logPow of-1 to 1, which represents an octanol/water distribution coefficient, on a bonding surface of the polarizing plate; a second coating step of coating a second active energy ray-curable adhesive composition containing a component B having a logPow of 2 to 7 on the bonding surface of the transparent protective film; a bonding step of bonding the polarizing plate and the transparent protective film; and a bonding step of curing the active energy ray-curable adhesive composition by irradiating the composition with an active energy ray from the polarizing plate surface side or the transparent protective film surface side, and bonding the polarizing plate and the transparent protective film with the adhesive layer interposed therebetween, wherein the concentration of the component a on the polarizing plate side of the adhesive layer formed after the bonding step is high.

The manufacturing method comprises the following steps: a first coating step of coating a first active energy ray-curable adhesive composition containing a component A having a logPow of-1 to 1, which represents an octanol/water distribution coefficient, on a bonding surface of a polarizing plate; and a second coating step of coating a second active energy ray-curable adhesive composition containing a component B having a logPow of 2 to 7 on the bonding surface of the transparent protective film. This further increases the concentration of the component a on the polarizer side of the adhesive layer formed after the adhesion step, and more reliably has a component gradient structure in which the concentration of the component a on the polarizer side increases. In order to form the component-inclined structure more reliably, the content of the component a having a logPow of-1 to 1 is preferably 50 to 95 wt%, and more preferably 60 to 80 wt%, when the total amount of the first active energy ray-curable adhesive composition applied to the bonding surface of the polarizing plate is 100 wt%. Similarly, the content of the component B having a logPow of 2 to 7 is preferably 50 to 95% by weight, more preferably 60 to 80% by weight, based on 100% by weight of the total amount of the second active energy ray-curable adhesive composition applied to the bonding surface of the transparent protective film. In addition, the ratio of the first active energy ray-curable adhesive composition to the second active energy ray-curable adhesive composition is preferably 5: 95-50: 50, more preferably 10: 90-40: 60.

in the method for producing a polarizing film of the present invention, the polarizing plate or the transparent protective film may be subjected to a surface modification treatment before the application of the active energy ray-curable adhesive composition. Specific examples of the treatment include corona treatment, plasma treatment, and saponification treatment.

The coating method of the active energy ray-curable adhesive composition can be appropriately selected depending on the viscosity of the composition and the desired thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse, or offset), a reverse bar coater, a roll coater, a die coater, a bar coater, and a bar coater. In addition, a dipping method or the like can be suitably used in the coating.

The polarizing plate and the transparent protective film were bonded with the active energy ray-curable adhesive composition applied as described above interposed therebetween. The polarizing plate and the transparent protective film may be bonded to each other by a roll press or the like.

The active energy ray-curable adhesive composition preferably contains at least 1 organometallic compound selected from metal alkoxides and metal chelates. In addition, the first active energy ray-curable adhesive composition preferably contains the organometallic compound. In addition, the metal of the organometallic compound contained in the active energy ray-curable adhesive composition is preferably titanium.

The active energy ray-curable adhesive composition preferably contains the metal alkoxide as the organometallic compound, and the number of carbon atoms of an organic group contained in the metal alkoxide is 6 or more, and the active energy ray-curable adhesive composition preferably contains the metal chelate as the organometallic compound, and the number of carbon atoms of an organic group contained in the metal chelate is 4 or more.

The storage modulus at 25 ℃ of the adhesive layer obtained by curing the active energy ray-curable adhesive composition is preferably 1.0 × 10⁷Pa or above.

< curing of the adhesive >

The active energy ray-curable adhesive composition used in the present invention may be used in the form of an electron beam-curable adhesive composition, an ultraviolet-curable adhesive composition, or a visible light-curable adhesive composition. As the active energy ray-curable adhesive composition, a visible ray-curable adhesive composition is preferred from the viewpoint of productivity.

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

In the electron beam curing type, any suitable conditions may be employed as long as the irradiation conditions of the electron beam are such that the active energy ray-curable adhesive composition can be cured. For example, the acceleration voltage for electron beam irradiation is preferably 5kV to 300kV, and more preferably 10kV to 250 kV. If the acceleration voltage is less than 5kV, the electron beam may not reach the adhesive and cure may be insufficient, and if the acceleration voltage is higher than 300kV, the penetration force through the sample may be too strong, and damage may be caused to the transparent protective film and the polarizing plate. The dose of irradiation is preferably 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 is more than 100kGy, the adhesive damages the transparent protective film and the polarizing plate, resulting in a decrease in mechanical strength and yellowing, and thus, a predetermined optical characteristic cannot be obtained.

The electron beam irradiation is usually carried out in an inert gas, and if necessary, it may be carried out in the atmosphere or under a condition where a small amount of oxygen is introduced. Although it depends on the material of the transparent protective film, oxygen is introduced appropriately, so that oxygen is intentionally inhibited from being applied to the surface of the transparent protective film where the electron beam first strikes, and damage to the transparent protective film can be prevented, and the electron beam can be effectively irradiated only to the adhesive.

In the method for manufacturing a polarizing film of the present invention, it is preferable to use, as an active energy ray, a ray including a visible ray having a wavelength range of 380nm to 450nm, particularly an active energy ray having the largest dose of a visible ray having a wavelength range of 380nm to 450nm, in an ultraviolet curing type or a visible ray curing type, in the case of using a transparent protective film (a non-transmissive ultraviolet type transparent protective film) to which an ultraviolet absorbing ability is imparted, since light having a wavelength shorter than 380nm is substantially absorbed, the light having a wavelength shorter than 380nm does not reach the active energy ray curing type adhesive and does not participate in a polymerization reaction, further, light having a wavelength shorter than 380nm absorbed by the transparent protective film is converted into heat to cause a defect such as curling or a wrinkle of the polarizing film, and the transparent protective film itself is generated, in the case of using an ultraviolet curing type or visible ray curing type, it is preferable to use, as an active energy ray generating device, a device which does not emit light having a wavelength shorter than 380nm, and more preferable to use, as a band pass-through a halogen light source, a wavelength range of 100 nm, a wavelength of 100 nm, a wavelength of 100 to 100 nm, a wavelength of 100 nm, a halogen light of preferably 100 nm, a halogen light of a wavelength of a halogen light of a wavelength of a halogen lamp, a wavelength of a halogen lamp, a wavelength of a lamp, a.

In the ultraviolet-curable or visible-light-curable type, it is also preferable to heat the active energy ray-curable adhesive after irradiation with ultraviolet rays or visible rays (post-irradiation heating), 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 suitably used particularly in the case of forming an adhesive layer for bonding a polarizing plate to a transparent protective film having a light transmittance of 365nm of less than 5%. Here, the active energy ray-curable adhesive of the present invention contains the photopolymerization initiator of the general formula (1) described above, and thus can be cured to form an adhesive layer by irradiating ultraviolet rays through a transparent protective film having UV-absorbing ability. Therefore, in a polarizing film in which transparent protective films having UV absorbing ability are laminated on both surfaces of a polarizing plate, the adhesive layer may be cured. However, it is needless to say that the adhesive layer may be cured in the polarizing film in which the 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 a method for imparting UV absorption ability to the transparent protective film include a method in which an ultraviolet absorber is contained in the transparent protective film, and a method in which a surface treatment layer containing an ultraviolet absorber is laminated 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.

The water content of the polarizing plate is usually 1% or more, preferably 3% or more, more preferably 5% or more when the polarizing plate is bonded to the transparent protective film, and when the water content of the polarizing plate is too high, the water content in the polarizing plate after bonding moves to the adhesive layer, and the B component having a logPOW of 2 to 7 in the adhesive composition is delaminated, thereby causing poor appearance, and therefore, the water content of the polarizing plate is not preferably 18% or less, more preferably 15% or less, most preferably 12% or less.

Water content (%) { (W-D)/W } × 100

The irradiation direction of the active energy rays (electron beam, ultraviolet rays, visible rays, etc.) may be irradiated from any suitable direction. Irradiation is preferably from the transparent protective film side. If the polarizing plate is irradiated from the polarizer side, the polarizing plate may be deteriorated by active energy rays (electron beams, ultraviolet rays, visible rays, and the like).

In the case of producing the polarizing film of the present invention by a continuous 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. If the production line speed is too low, the productivity is insufficient, or the 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 production line speed is too high, the adhesive may not be sufficiently cured, 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 laminated via an adhesive layer formed by a cured product layer of the active energy ray-curable adhesive, and 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-based skeleton, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins may be used alone in 1 kind, or in combination with 2 or more kinds. In addition, other additives may be added during 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 on the transparent protective film in advance, and the easy-adhesion layer side of the transparent protective film is bonded to the polarizing plate by the adhesive layer. The easy adhesion layer is formed by coating a material for forming the easy adhesion layer on the transparent protective film by a known technique and drying the coating. The material for forming the easy-adhesion layer is usually prepared as 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 addition, a plurality of easy adhesion layers may be provided, and in this case, the total thickness of the easy adhesion layers is preferably set to 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 a polarizing plate 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, while adsorbing a dichroic material such as iodine or a dichroic dye, and a polyolefin-based alignment film such as a dehydrated polyvinyl alcohol or a desalted polyvinyl chloride. Among them, a polarizing plate containing a polyvinyl alcohol film and a dichroic material such as iodine is suitable. The thickness of these polarizing plates is not particularly limited, but is generally about 80 μm or less.

The polarizing plate obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced, for example, by immersing the polyvinyl alcohol film in an aqueous iodine solution to dye the film and stretching the film to 3 to 7 times the original length. If necessary, the substrate may be immersed in an aqueous solution of boric acid, potassium iodide, or the like. If necessary, the polyvinyl alcohol film may be washed with water by immersing it in water before dyeing. By washing the polyvinyl alcohol film with water, dirt and an anti-blocking agent on the surface of the polyvinyl alcohol film can be washed, and the polyvinyl alcohol film is swollen, thereby having an effect of preventing unevenness such as uneven dyeing. The stretching may be performed after the dyeing with iodine, or may be performed while 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.

In addition, when a thin polarizing plate having a thickness of 10 μm or less is used as the polarizing plate, the active energy ray-curable adhesive composition used in the present invention can exhibit its effect (satisfying optical durability in a severe environment under high temperature and high humidity) remarkably. 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 liable to cause an increase in transmittance and a decrease in polarization degree. That is, when the polarizing plate of 10 μm or less is laminated with the adhesive layer of the present invention, the deterioration of the optical durability such as the increase of the transmittance and the decrease of the 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, is excellent in observation properties, has less dimensional change, and can be made thin as a thickness of a polarizing film.

Representative examples of thin polarizing plates include thin polarizing films described in JP 51-069644 a, JP 2000-338329 a, WO2010/100917 a, PCT/JP2010/001460 a, and JP 2010-269002 a or JP 2010-263692 a. 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 troubles such as breakage due to stretching because it is supported by the resin base material for stretching.

As the thin polarizing film, in a manufacturing method including a step of stretching in a state of a laminate and a step of dyeing, from the viewpoint that the polarizing performance can be improved by stretching at a high magnification, polarizing films obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in WO2010/100917 pamphlet, PCT/JP2010/001460 pamphlet, japanese patent application 2010-269002 pamphlet, and japanese patent application 2010-263692 are preferable, and polarizing films obtained by a manufacturing method including a step of performing in-air stretching in an aqueous boric acid solution before stretching in an aqueous boric acid solution as described in japanese patent application 2010-269002 pamphlet and japanese patent application 2010-263692 are particularly preferable.

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

The thin high-functional polarizing film can be produced by forming a PVA-based resin layer on a resin substrate having a thickness of at least 20 μm by coating and drying a PVA-based resin, immersing the formed PVA-based resin layer in a dyeing solution containing a dichroic material, allowing the PVA-based resin layer to adsorb the dichroic material, and stretching the PVA-based resin layer adsorbed with the dichroic material in an aqueous boric acid solution so that the total stretching magnification is 5 times or more the original length.

The thin high-functional polarizing film can be produced by a method for producing a laminate film including a thin high-functional polarizing film in which a dichroic material is aligned, the method including: a step of forming a laminate film including a resin base having a thickness of at least 20 μm and a PVA resin layer formed by applying an aqueous solution containing a PVA resin to one surface of the resin base and drying the aqueous solution; a step of impregnating 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 to thereby adsorb the dichroic substance to 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 of the original length; and a step of stretching the PVA resin layer having the dichroic substance adsorbed thereon and the resin substrate integrally to produce a laminate film having a thin highly functional polarizing film formed on one surface of the resin substrate, the thin highly functional polarizing film comprising the PVA resin layer having the dichroic substance oriented therein, 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 degree of polarization of 99.95% or more.

The thin polarizing films described in the above-mentioned Japanese patent application No. 2010-269002 and No. 2010-263692 are continuous belt-like polarizing films comprising a PVA-based resin in which a dichroic material is oriented, and a laminate comprising a PVA-based resin layer formed on an amorphous ester-based thermoplastic resin substrate is stretched in air-assisted stretching and boric acid water stretchingThe resulting sheet is stretched in a 2-stage stretching step to a thickness of 10 μm or less. When the monomer transmittance is T and the polarization degree is P, the thin polarizing film is preferably formed to satisfy P > - (10)^{0.929T－42.4－1}) × 100 (wherein T < 42.3), and P.gtoreq.99.9 (wherein T.gtoreq.42.3).

Specifically, the thin polarizing film can be produced by a method for producing a thin polarizing film comprising a step of producing a stretched intermediate product comprising an oriented PVA-based resin layer by in-air high-temperature stretching of a PVA-based resin layer formed on a continuous belt-like amorphous ester-based thermoplastic resin substrate; a step of producing a colored intermediate product including a PVA-based resin layer in which a dichroic material (preferably iodine or a mixture of iodine and an organic dye) is oriented by adsorption of the dichroic material onto the stretched intermediate product; and a step of stretching the colored intermediate product in boric acid water to form a polarizing film having a thickness of 10 μm or less, the polarizing film including a PVA-based resin layer having a dichroic material oriented therein.

In this production method, it is desirable that the total draw ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate by the in-air high-temperature drawing and the boric acid underwater drawing is 5 times or more. The liquid temperature of the aqueous boric acid solution used for underwater stretching of boric acid may be 60 ℃ or higher. In this case, it is desirable to perform insolubilization treatment of the colored intermediate product before stretching the colored intermediate product in an aqueous boric acid solution, and in this case, it is desirable to perform insolubilization treatment by immersing the colored intermediate product in an aqueous boric acid solution having a liquid temperature of not higher than 40 ℃. The amorphous ester thermoplastic resin substrate may be an amorphous polyethylene terephthalate including copolymerized polyethylene terephthalate copolymerized with isophthalic acid, copolymerized polyethylene terephthalate copolymerized with cyclohexanedimethanol, or other copolymerized polyethylene terephthalate, and is preferably a substrate made of a transparent resin, and the thickness of the substrate may be 7 times or more the thickness of the PVA 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 lower than the glass transition temperature of the PVA-based resin, more specifically, 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, a thin polarizing film can be manufactured by the following method.

A continuous belt-like substrate of isophthalic acid-copolymerized polyethylene terephthalate (amorphous PET) in which 6 mol% of isophthalic acid was copolymerized was prepared. The glass transition temperature of amorphous PET is 75 ℃. A laminate including a continuous belt-shaped amorphous PET substrate and a polyvinyl alcohol (PVA) layer was produced as follows. Incidentally, the glass transition temperature of PVA is 80 ℃.

A200 μm thick amorphous PET substrate and a 4-5% concentration PVA aqueous solution in which PVA powder having a polymerization degree of 1000 or more and a saponification degree of 99% or more is dissolved 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 laminate comprising a PVA layer having a thickness of 7 μm was subjected to the following 2-stage stretching step including air-assisted stretching and boric acid underwater stretching to produce a thin highly functional polarizing film having a thickness of 3 μm. 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 of 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 loading a laminate including a PVA layer having a thickness of 7 μm into a stretching device equipped in an oven set to 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 having a thickness of 5 μm in which the PVA molecules were oriented.

Then, a colored laminate in which iodine is adsorbed on a PVA layer having a thickness of 5 μm in which PVA molecules are oriented is produced in 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 time such that the monomer transmittance of the PVA layer constituting the highly functional polarizing film finally produced is 40 to 44%, thereby adsorbing iodine in the PVA layer contained in the stretched laminate. In this step, the dyeing liquid is prepared by using water as a solvent, and 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 ratio of the concentration of iodine to potassium iodide was 1 to 7. Incidentally, potassium iodide is required for dissolving iodine in water. More specifically, the stretched laminate was immersed in a dyeing solution containing 0.30 wt% of iodine and 2.1 wt% of potassium iodide for 60 seconds, thereby producing a colored laminate in which iodine was adsorbed to a PVA layer having a thickness of 5 μm in which PVA molecules were oriented.

Subsequently, the colored laminate was further stretched integrally with the amorphous PET substrate in 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 loading the colored laminate into a stretching device equipped with a treatment device for an aqueous boric acid solution having a liquid temperature range of 60 to 85 ℃ containing boric acid and potassium iodide, and performing free-end uniaxial stretching so that the stretching ratio 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 immersed in an aqueous boric acid solution for 5 to 10 seconds. Then, the colored laminate was passed through a stretching device provided in the processing apparatus, i.e., between a plurality of sets of rollers having different peripheral speeds, as it was, and free-end uniaxial stretching was performed so that the stretching magnification was 3.3 times for 30 to 90 seconds. By this stretching treatment, the PVA layer contained in the colored laminate becomes a PVA layer of 3 μm thickness in which the adsorbed iodine is highly oriented in one direction as 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 to take out the optical film laminate from the boric acid aqueous solution in the cleaning step and clean the boric acid adhering to the surface of the PVA layer having a thickness of 3 μm formed on the amorphous PET substrate with a potassium iodide aqueous solution. Thereafter, 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.

Although not necessarily required for the production of the optical film laminate, a triacetyl cellulose film having a thickness of 80 μm may be laminated on the surface of a PVA layer having a thickness of 3 μm formed on an amorphous PET substrate by a laminating and/or transferring step, and then the amorphous PET substrate may be peeled off to transfer the PVA layer having a thickness of 3 μm to the triacetyl cellulose film having a thickness of 80 μm.

[ other Processes ]

The method for manufacturing the thin polarizing film may 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 suitable timing.

Typically, the insolubilization step is 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. The PVA resin layer can be provided with water resistance by performing crosslinking treatment. 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 to 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 ℃. Preferably, the crosslinking step is performed before the second aqueous diboronic 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 barrier property, 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. Further, as examples of the polymer forming the transparent protective film, polyethylene, polypropylene, polyolefin having a ring system or a norbornene structure, polyolefin-based polymers such as an ethylene-propylene copolymer, vinyl chloride-based polymers, amide-based polymers such as nylon or aromatic polyamide, imide-based polymers, sulfone-based polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, aryl ester-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, or blends of the above polymers can be given. The transparent protective film may contain 1 or more kinds of any suitable additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. 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.

The transparent protective film may be a polymer film described in Japanese patent application 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 a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group in a side chain. Specific examples thereof include a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. As the film, a film formed of a mixed extrusion product of a resin composition or the like can be used. These films have a small phase difference and a small photoelastic coefficient, and therefore can eliminate the problems such as unevenness caused by deformation 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. According to 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 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 barrier 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 can be 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 aryl ester-based 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 norbornene structure, (meth) acrylic resins, or mixtures thereof. Among the 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 may be suitably determined, but is generally about 1 to 100 μm in view of strength, handling properties such as handling properties, and thin layer properties. 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. As the combination of the transparent protective film, from the viewpoint of moisture permeability, a combination of a polyethylene terephthalate film and a cyclic polyolefin resin film, a combination of a (meth) acrylic resin film and a cyclic polyolefin resin film, and a combination of a (meth) acrylic resin film and a (meth) acrylic resin film are preferable. By providing transparent protective films having low moisture permeability on both sides of the polarizing plate, moisture hardly enters the polarizing film, and a polarizing film having particularly excellent water resistance can be obtained.

A functional layer such as a hard coat layer, an antireflection layer, an adhesion-preventing layer, a diffusion layer, or an antiglare layer may be provided on the surface of the transparent protective film to which the polarizing plate is not adhered. The functional layer such as the hard coat layer, the antireflection layer, the adhesion preventing 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 can be used as an optical film laminated with other optical layers in practical use. The optical layer is not particularly limited, but for example, an optical layer used in the formation of a liquid crystal display device such as a 1-layer or 2-layer or more reflective plate, semi-transmissive plate, retardation plate (including wavelength plates such as 1/2 and 1/4), viewing angle compensation film, or the like may be used. In particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by further laminating a reflective plate or a semi-transmissive reflective plate on the polarizing film of the present invention, an elliptical polarizing film or a circular polarizing film obtained by further laminating a phase difference plate on the polarizing film, a wide-viewing-angle polarizing film obtained by further laminating a viewing angle compensation film on the polarizing film, or a polarizing film obtained by further laminating a brightness enhancement film on the polarizing film is preferable.

The optical film obtained by laminating the optical layers on the polarizing film can be formed by sequentially laminating the optical layers one by one in the manufacturing process of a liquid crystal display device or the like, and the method of laminating the optical films in advance has an advantage that the manufacturing process of the liquid crystal display device or the like can be improved because the method is excellent in quality stability, assembling workability, and the like. For lamination, an appropriate adhesive method such as an adhesive layer can be used. When the polarizing film or other optical film is bonded, the optical axes thereof may be set to an appropriate arrangement angle depending on the desired retardation characteristics and the like.

The polarizing film or the optical film in which at least 1 polarizing film is laminated may be provided with an adhesive layer for adhesion to other members such as a liquid crystal cell. The adhesive agent for forming the adhesive layer is not particularly limited, and for example, an adhesive agent containing 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 acrylic pressure-sensitive adhesive or the like having excellent optical transparency, adhesion properties such as appropriate wettability, cohesiveness and adhesiveness, and excellent weather resistance, heat resistance and the like is 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 materials of different compositions, types, or the like. In the case of providing both surfaces, adhesive layers of different compositions, kinds, thicknesses, and the like may be used on the front and back surfaces of the polarizing film or the optical film. The thickness of the adhesive layer is suitably determined depending on the purpose of use, adhesive strength, etc., and is generally 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 covered by temporarily attaching a spacer for the purpose of preventing contamination or the like until the adhesive layer is used for actual use. This can prevent contact with the adhesive layer in a normal handling state. As the spacer, in addition to the above thickness conditions, for example, an appropriate material obtained by a conventional method, such as a material obtained by coating an appropriate paper-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-based, a long-chain alkyl-based, a fluorine-based, or a molybdenum sulfide, as necessary, can be used.

< image display device >

The polarizing film or the optical film of the present invention can be preferably used for formation of 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, a polarizing film or an optical film, and components such as an illumination system used as needed, and incorporating the same into a driving circuit, and the like. For the liquid crystal cell, for example, any type of liquid crystal cell such as TN type, STN type, and pi type may be used.

A suitable liquid crystal display device such as 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 a liquid crystal display device using a backlight or a reflector in an illumination system can be formed. In this case, the polarizing film or the optical film of the present invention may be provided on one side or both sides of the liquid crystal cell. When the polarizing film or the optical film is provided on both sides, they may be the same or different. In the formation of the 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 disposed in appropriate positions, for example, in 1 layer or 2 layers or more.

[ examples ]

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

Production example 1

< production of polyvinyl alcohol-based polarizing plate X >

A75 μm thick polyvinyl alcohol film having 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. Then, the film was immersed in an aqueous solution of iodine/potassium iodide (weight ratio: 0.5/8) having a concentration of 0.3%, and the film was dyed while stretching to 3.5 times. Thereafter, stretching was performed in an aqueous solution of boric acid ester at 65 ℃ so that the total stretching ratio became 6 times. After the stretching, the obtained film was dried in an oven at 40 ℃ for 3 minutes to obtain a polyvinyl alcohol polarizing plate X (thickness: 23 μm).

Production example 2

< production of polyvinyl alcohol-based thin polarizing plate Y >

In order to produce the thin polarizing plate Y, first, a laminate in which a 24 μm-thick PVA layer was formed on an amorphous PET substrate was subjected to air-assisted stretching at a stretching temperature of 130 ℃ to produce a stretched laminate, then the stretched laminate was dyed to produce a colored laminate, and then the colored laminate was subjected to boric acid underwater stretching at a stretching temperature of 65 ℃ to produce an optical film laminate including a10 μm-thick PVA layer integrally stretched with an amorphous PET substrate so that the total stretching magnification was 5.94 times. By such 2-stage stretching, PVA molecules in the PVA layer formed on the amorphous PET substrate are highly oriented, and an optical film laminate including a PVA layer having a thickness of 10 μm, which constitutes the polyvinyl alcohol-based thin polarizing plate Y in which iodine adsorbed by dyeing is highly oriented in one direction as a polyiodide complex, can be produced.

< transparent protective film >

Transparent protective film A: 100 parts by weight of an imidized MS resin described in production example 1 of Japanese patent application laid-open No. 2010-284840 and 0.62 part by weight of a triazine-based ultraviolet absorber (product name: T-712, manufactured by ADEKA) were mixed at 220 ℃ using a 2-shaft kneader to prepare resin pellets. The obtained resin pellets were dried at 100.5kPa and 100 ℃ for 12 hours, extruded from a T-die at a die temperature of 270 ℃ by a uniaxial extruder, and formed into a film shape (thickness 1)60 μm). The film was further stretched in the direction of transport at 150 ℃ in an atmosphere (thickness: 80 μm), then coated with an easy-adhesive agent comprising a water-based urethane resin, and then stretched in the direction orthogonal to the direction of transport of the film at 150 ℃ in an atmosphere to give a film having a thickness of 40 μm (moisture permeability: 58 g/m)²24h) of a transparent protective film A.

Transparent protective film B: a cyclic polyolefin film (manufactured by Zeon corporation, Japan; moisture permeability: 11 g/m) having a thickness of 55 μm was used²24h) films subjected to corona treatment.

And (3) a transparent protective film C: a PET film (manufactured by Toyo Boseki Co., Ltd., moisture permeability of 13 g/m) having a thickness of 80 μm was used²24h) using a urethane resin, and a film subjected to an easy-adhesion treatment.

< moisture permeability of transparent protective film >

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

< active energy ray >

As the active energy ray, a visible ray (gallium-sealed metal halide lamp) irradiation device L light HAMMER10 lamp manufactured by fusion UV Sysymems, Inc., having a V lamp peak illuminance of 1600mW/cm was used²Cumulative dose of radiation 1000/mJ/cm²(wavelength 380-440 nm). The illuminance of visible light was measured by using Sola-Check system manufactured by Solatell corporation.

Examples 1 to 5 and comparative examples 1 to 2

(preparation of active energy ray-curable adhesive composition)

The respective components were mixed and stirred at 50 ℃ for 1 hour in accordance with the formulation table shown in Table 1 to obtain active energy ray-curable adhesive compositions of examples 1 to 5 and comparative examples 1 to 2.

(preparation of polarizing film)

The active energy ray-curable adhesive compositions of examples 1 to 5 and comparative examples 1 to 2 were applied to the transparent protective film A, B or C using an MCD coater (manufactured by Fuji machine Co.) (cell shape: number of honeycomb-shaped gravure rolls/inch, rotation speed 140%/line speed) so as to have the adhesive layer thickness described in Table 1, and when a polarizing plate X was used, the transparent protective films were bonded to both surfaces thereof using a roll press. On the other hand, in the case of using the thin polarizing plate Y, the transparent protective film is bonded only to the side opposite to the PVA layer by a roll press. Then, the adhesive compositions of examples 1 to 5 and comparative examples 1 to 2 were cured by heating the transparent protective films (both sides in the case of using the polarizing plate X) from the side of the transparent protective films to be bonded to each other with an IR heater at 50 ℃ and irradiating both sides with the above visible light rays, and then dried with hot air at 70 ℃ for 3 minutes to obtain polarizing films having transparent protective films on both sides of the polarizing plate. The linear speed of the laminating production line is 25 m/min.

The polarizing films obtained in the above examples and comparative examples were evaluated as follows. The evaluation results are shown in table 1.

< identification of inclined composition structure of adhesive layer >

After the adhesive layer was exposed by mechanically cutting the transparent protective film, the thickness direction analysis of the adhesive layer was performed by alternately repeating etching using cluster ions and TOF-SIMS measurement. TOF-SIMS used "TRIFTV" manufactured by Ulvac-Phi. Specific secondary ions were selected for each component, and the components that were partially offset in the thickness direction were identified by comparing the intensity ratios of the secondary ions in the thickness direction. The evaluation is performed by calculating the ratio of the component A in the interface on the polarizer side of the adhesive layer, assuming that the ratio of the component A having a logPow of-1 to 1 in the central portion in the thickness direction of the adhesive layer is 1. When the ratio of the a component in the polarizer-side interface of the adhesive layer is greater than 1, it means that the concentration of the a component on the polarizer side of the adhesive layer is high. The evaluation results are shown in table 1.

< temperature measurement of active energy ray-curable adhesive composition >

The surface of the transparent protective film coated with the adhesive composition was measured with a thermal imaging system "F L IR-E49001" manufactured by F L IR company, and the temperature of the adhesive composition immediately after coating was estimated to be the same as that of the transparent protective film since the adhesive layer to be coated was a very thin film relative to the transparent protective film.

< adhesive force >

The polarizing films obtained in the respective examples were cut out in a size of 200mm in a direction parallel to the stretching direction of the polarizing plate and 20mm in a direction perpendicular thereto, and a slit was cut out between the transparent protective film and the polarizing plate with a cutter to bond the polarizing films to a glass plate. The transparent protective film and the polarizing plate were peeled from each other at a peeling speed of 500mm/min in a direction of 90 degrees by using a tenter, and the peel strength was measured. The infrared absorption spectrum of the peeled surface after peeling was measured by ATR method, and the peeled interface was evaluated based on 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, a and D mean that the adhesive strength is not less than the cohesive strength of the film, and therefore the adhesive strength is very excellent, while B and C mean that the adhesive strength at the interface of the transparent protective film/adhesive layer (adhesive layer/polarizing plate) is insufficient (adhesive strength difference). in view of these, the adhesive strength at a or D is ○, the adhesive strength at a · B (simultaneous occurrence of "cohesive failure of the transparent protective film" and "interfacial peeling between the transparent protective film/adhesive layer") or a · C (simultaneous occurrence of "cohesive failure of the transparent protective film" and "interfacial peeling between the adhesive layer/polarizing plate") is △, and the adhesive strength at B or C is ×.

< durability of adhesive bond (warm water immersion test) >

The polarizing film obtained in each example was cut into a rectangular shape of 50mm in the stretching direction of the polarizing plate and 25mm in the vertical direction. The polarizing film was immersed in warm water at 60 ℃ for 6 hours, and the length under peeling was visually measured with a magnifier. The measurement was performed using the maximum value (mm) of the vertical distance from the cross section of the portion where peeling occurred.

Durability of adhesive bond (resistance to water peeling force) >

The polarizing film obtained in each example was cut out in a size of 200mm in a 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 dry cloth, and then a cut was made between the transparent protective film and the polarizing plate with a cutter to bond the polarizing film to the glass plate. The operation from the removal from pure water to the evaluation was performed within 1 minute. Thereafter, the same evaluation as the above-mentioned < adhesive strength > was carried out.

[ Table 1]

[ Table 1]

In table 1, the compounds used represent:

4 HBA: 4-hydroxybutyl acrylate, logPow ═ 0.68, manufactured by Osaka chemical industries, Inc,

HEAA: hydroxyethyl acrylamide, logPow ═ 0.56, manufactured by Xinghan corporation,

ACMO: acryloylmorpholine, logPow 0.20, manufactured by Kyoto Co., Ltd,

FANCRY L FA511AS dicyclopentenyl acrylate, logPow 2.26, manufactured by Hitachi chemical Co., Ltd,

L IGHT ACRY L ATE DCP-A Dicidol diacrylate, logPow 3.05, available from KyoeishｃA chemical Co., Ltd,

L IGHT ACRY L ATE1, 9 ND-A: 1, 9-nonanediol diacrylate, logPow ═ 3.68, available from Kyoeisha chemical Co., Ltd,

FANCRY L FA-P324A bisphenol A PO4 mol modified diacrylate, logPow 6.43, manufactured by Hitachi chemical Co., Ltd,

Aronix M-220: tripropylene glycol diacrylate, logPow 1.68 manufactured by Toyo Synthesis Ltd,

Aronix M-5700: 2-hydroxy-3-phenoxypropyl acrylate, logPow ═ 1.17, available from Toyama Synthesis Ltd,

ARUFON UG-4010: acrylic oligomer obtained by polymerizing (meth) acrylic monomer, manufactured by Toyata Ltd,

NIKANO L Y-1000, xylene resin, manufactured by FUDOW Corp

IRGACURE 907: 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, manufactured by BASF,

KAYACURE DETX-S: diethylthioxanthone, manufactured by Nippon Chemicals Ltd,

IRGACURE 184: 1-Hydroxycyclohexylphenyl ketone manufactured by BASF corporation.

Example 6

An active energy ray-curable adhesive composition containing the following compound was prepared.

A first active energy ray-curable adhesive composition (liquid viscosity 10mPa · s/25 ℃); HEAA 94 wt.%, IRGACURE9073 wt.%, KAYACURE DETX-S3 wt.%

The second active energy ray-curable adhesive composition (liquid viscosity: 350 mPas/25 ℃ C.); L IGHTACRY L ATE1, 9 ND-A94 wt%, IRGACURE9073 wt%, KAYACURE DETX-S3 wt%)

(preparation of polarizing film)

A first active energy ray-curable adhesive composition (adhesive layer thickness: 0.3 μm) was applied to the PVA layer of the thin polarizing plate Y. Further, a second active energy ray-curable adhesive composition (adhesive layer thickness 0.7 μm) was applied to the bonding surface of the transparent protective film a, and then they were bonded by a roll press. The ratio of the first active energy ray-curable adhesive composition to the second active energy ray-curable adhesive composition was 30: 70. then, the transparent protective film side was heated to 50 ℃ by an IR heater, the first and second active energy ray-curable adhesive compositions were cured by irradiating both sides with the above visible light rays, and 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 linear speed of the laminating production line is 25 m/min.

The polarizing film obtained in example 6 was evaluated for adhesion to the thin polarizing plate Y and the transparent protective film a. In addition, the contact angle between the first active energy ray-curable adhesive composition and the thin polarizing plate Y and the contact angle between the second active energy ray-curable adhesive composition and the transparent protective film Y were evaluated. The contact angle was evaluated according to JIS-K6768. The evaluation results are shown in table 2.

[ Table 2]

[ Table 2]

< storage modulus >

The storage modulus was measured under the following measurement conditions using a dynamic viscoelasticity measuring apparatus RSAIII manufactured by TA Instruments.

Sample size: 10mm wide and 30mm long,

The distance between the clamps is 20mm,

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

The dynamic viscoelasticity was measured by using a measurement value of the storage modulus at 25 ℃.

Examples 7 to 15 and comparative example 3

(preparation of active energy ray-curable adhesive composition)

The respective components were mixed and stirred at 50 ℃ for 1 hour in accordance with the formulation table shown in table 3 to obtain active energy ray-curable adhesive compositions of examples 7 to 15 and comparative example 3.

[ Table 3]

[ Table 3]

In table 3, the compounds used represent:

TPGDA: tripropylene glycol diacrylate, manufactured by Toyo Synthesis Co., Ltd. (Aronix M-220), and metal alkoxide and metal chelate compounds:

TC-750: ethyl acetoacetate chelate (C6 in organic group), manufactured by MatsumotoFinechial Co., Ltd.;

TC-100: titanium acetylacetonate (carbon number 5 of organic group) manufactured by Matsumoto Finechemical Co., Ltd;

TA-30: octyloxy titanium (carbon number 8 of organic group), manufactured by Matsumoto Finechemical Co., Ltd.;

d20: titanium butoxide (carbon number 4 of organic group) manufactured by shin-Etsu Silicone Co., Ltd;

ZA 65: zirconium butoxide (carbon number 4 of organic group), manufactured by Matsumoto Finechemical Co., Ltd.;

aluminum Chelate M: (acetoacetoxyalkyl ester) diisopropyl ester (organic group having 4 or more carbon atoms), manufactured by Kagawa Fine chemical Co., Ltd.;

the vinyl ether compound represents:

VEEA: 2- (2-ethyleneoxyethoxy) ethyl acrylate, manufactured by Nippon catalyst Co., Ltd.;

the photoacid generator is represented by:

manufactured by CPI-100P, Sun-Apro.

Examples 16 to 19 and comparative examples 4 to 7

(preparation of active energy ray-curable adhesive composition)

The respective components were mixed and stirred at 50 ℃ for 1 hour in accordance with the formulation table shown in Table 4 to obtain active energy ray-curable adhesive compositions of examples 16 to 19 and comparative examples 4 to 7.

[ Table 4]

In table 4, the alkoxysilyl group-containing compound is represented by:

TA polymer SA 100S: main chain (meth) acrylic polymer type, manufactured by Kaneka corporation

X-MAP SA 110S: main chain (meth) acrylic polymer type, manufactured by Kaneka corporation

X-40-9225: oligomeric alkoxysilyl group-containing compound, commercially available from shin-Etsu Silicone Co,

KR-213: oligomeric alkoxysilyl group-containing compound, commercially available from shin-Etsu Silicone Co,

KC-89S: low molecular weight alkoxysilyl group-containing compound manufactured by shin-Etsu Silicone Co Ltd,

KBM 403: low molecular weight alkoxysilyl group-containing compound, manufactured by shin-Etsu Silicone Co.

Claims (26)

1. A polarizing film comprising a polarizing plate and a transparent protective film laminated on at least one side of the polarizing plate with an adhesive layer interposed therebetween,

the adhesive layer is a layer formed from a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray,

the active energy ray-curable adhesive composition contains a component A having a logPow of-1 to 1 and a component B having a logPow of 2 to 7,

the concentration of the component A on the polarizer side of the adhesive layer is high.

2. The polarizing film of claim 1,

the active energy ray-curable adhesive composition contains a (meth) acrylamide derivative as the component A.

3. The polarizing film according to claim 1 or 2,

the active energy ray-curable adhesive composition contains a polyfunctional (meth) acrylate as the component B.

4. The polarizing film according to any one of claims 1 to 3,

the active energy ray-curable adhesive composition contains an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer.

5. The polarizing film according to any one of claims 1 to 4,

the active energy ray-curable adhesive composition contains a photopolymerization initiator containing a hydroxyl group.

6. The polarizing film according to any one of claims 1 to 5,

the active energy ray-curable adhesive composition contains at least 1 organometallic compound selected from metal alkoxides and metal chelates.

7. The polarizing film of claim 6,

the metal of the organometallic compound contained in the active energy ray-curable adhesive composition is titanium.

8. The polarizing film of claim 6 or 7,

the active energy ray-curable adhesive composition contains the metal alkoxide as the organometallic compound, and the number of carbon atoms of an organic group contained in the metal alkoxide is 6 or more.

9. The polarizing film of claim 6 or 7,

the active energy ray-curable adhesive composition contains the metal chelate as the organometallic compound, and the number of carbon atoms of an organic group of the metal chelate is 4 or more.

10. The polarizing film according to any one of claims 1 to 9, which contains an alkoxysilyl group-containing compound having a viscosity of 15 mPa-s or more.

11. The polarizing film of claim 10,

the main chain of the compound containing the alkoxy silane group is an acrylic polymer structure.

12. The polarizing film according to any one of claims 1 to 11,

the storage modulus at 25 ℃ of an adhesive layer obtained by curing the active energy ray-curable adhesive composition is 1.0 × 10⁷Pa or above.

13. A method for producing a polarizing film according to any one of claims 1 to 12,

the method of manufacturing the polarizing film includes:

a coating step of coating the active energy ray-curable adhesive composition on at least one surface of the polarizing plate and the transparent protective film;

a bonding step of bonding the polarizing plate and the transparent protective film;

a bonding step of irradiating the polarizing plate surface side or the transparent protective film surface side with an active energy ray to cure the active energy ray-curable adhesive composition, and bonding the polarizing plate and the transparent protective film with the adhesive layer interposed therebetween,

the temperature of the active energy ray-curable adhesive composition is adjusted to 15 to 40 ℃ after the coating step and before the adhesion step.

14. A method for producing a polarizing film, characterized in that a transparent protective film is laminated on at least one surface of a polarizing plate with an adhesive layer interposed therebetween,

the adhesive layer is a layer formed from a cured product layer obtained by irradiating an active energy ray-curable adhesive composition with an active energy ray,

the method for manufacturing the polarizing film comprises the following steps:

a first coating step of coating a first active energy ray-curable adhesive composition containing a component A having a logPow of-1 to 1, which represents an octanol/water distribution coefficient, on a bonding surface of the polarizing plate;

a second coating step of coating a second active energy ray-curable adhesive composition containing a component B having a logPow of 2 to 7 on the bonding surface of the transparent protective film;

a bonding step of bonding the polarizing plate and the transparent protective film; and

a bonding step of irradiating the polarizing plate surface side or the transparent protective film surface side with an active energy ray to cure the active energy ray-curable adhesive composition, and bonding the polarizing plate and the transparent protective film with the adhesive layer interposed therebetween,

the concentration of the component a on the polarizer side of the adhesive layer formed after the bonding step is high.

15. The polarizing film production method according to claim 14,

the active energy ray-curable adhesive composition contains a (meth) acrylamide derivative as the component A.

16. The polarizing film production method according to claim 14 or 15,

the active energy ray-curable adhesive composition contains a polyfunctional (meth) acrylate as the component B.

17. The polarizing film production method according to any one of claims 14 to 16,

the active energy ray-curable adhesive composition contains an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer.

18. The method for producing a polarizing film according to any one of claims 14 to 17,

the active energy ray-curable adhesive composition contains a photopolymerization initiator containing a hydroxyl group.

19. The method for producing a polarizing film according to any one of claims 14 to 18,

the active energy ray-curable adhesive composition contains at least 1 organometallic compound selected from metal alkoxides and metal chelates.

20. The polarizing film production method of claim 19,

the first active energy ray-curable adhesive composition contains the organometallic compound.

21. The polarizing film production method according to claim 19 or 20,

the metal of the organometallic compound contained in the active energy ray-curable adhesive composition is titanium.

22. The method for producing a polarizing film according to any one of claims 19 to 21,

the active energy ray-curable adhesive composition contains the metal alkoxide as the organometallic compound, and the number of carbon atoms of an organic group contained in the metal alkoxide is 6 or more.

23. The polarizing film production method according to any one of claims 19 to 22, wherein,

the active energy ray-curable adhesive composition contains the metal chelate as the organometallic compound, and the number of carbon atoms of an organic group of the metal chelate is 4 or more.

24. The polarizing film according to any one of claims 14 to 23, which contains an alkoxysilyl group-containing compound having a viscosity of 15 mPa-s or more.

25. The polarizing film production method of claim 24, wherein,

the main chain of the compound containing the alkoxy silane group is an acrylic polymer structure.

26. The method for producing a polarizing film according to any one of claims 17 to 21,

the storage modulus at 25 ℃ of an adhesive layer obtained by curing the active energy ray-curable adhesive composition is 1.0 × 10⁷Pa or above.

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