JP7315357B2 - Method for manufacturing polarizing film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polarizing film in which a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer. The polarizing film can form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, a PDP, or the like, either alone or as an optical film in which the polarizing film is laminated.

2. Description of the Related Art Liquid crystal display devices for watches, mobile phones, PDAs, laptop computers, monitors for personal computers, DVD players, TVs, etc. are rapidly expanding their market. A liquid crystal display device visualizes a polarized state by switching liquid crystal, and a polarizer is used from its display principle. In particular, in applications such as TVs, higher brightness, higher contrast, and wider viewing angles are increasingly required, and polarizing films are increasingly required to have higher transmittance, higher degree of polarization, and higher color reproducibility.

As a polarizer, since it has a high transmittance and a high degree of polarization, for example, an iodine-based polarizer having a structure in which iodine is adsorbed to polyvinyl alcohol (hereinafter also simply referred to as “PVA”) and stretched is most commonly and widely used. Generally, a polarizing film is obtained by laminating transparent protective films on both sides of a polarizer with a so-called water-based adhesive made by dissolving a polyvinyl alcohol-based material in water (Patent Document 1 below). As the transparent protective film, triacetyl cellulose or the like having high moisture permeability is used. When the water-based adhesive is used (so-called wet lamination), a drying process is required after bonding the polarizer and the transparent protective film.

On the other hand, active energy ray-curable adhesives have been proposed instead of the water-based adhesives. When a polarizing film is produced using an active energy ray-curable adhesive, the productivity of the polarizing film can be improved because a drying step is not required. 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 Document 2 below).

Japanese Patent Application Laid-Open No. 2001-296427 Japanese Unexamined Patent Application Publication No. 2012-052000

The adhesive layer formed using the active energy ray-curable adhesive described in Patent Document 2 can sufficiently clear a water resistance test for evaluating the presence or absence of color loss and peeling after immersion in hot water at 60° C. for 6 hours, for example. However, in recent years, for adhesives for polarizing films, for example, it is possible to clear a more severe water resistance test, which evaluates the presence or absence of peeling when the end nail is peeled off after being immersed in water (saturated), and further improvement in water resistance is being sought. Therefore, the polarizing film using the active energy ray-curable adhesive described in Patent Document 2 has room for further improvement in terms of water-resistant adhesiveness.

An object of the present invention is to provide a method for continuously and stably producing a polarizing film having excellent adhesiveness between a polarizer and a transparent protective film and an adhesive layer.

The above problems can be solved by the following configuration.

That is, the present invention provides a method for producing a polarizing film in which a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer,
A first coating step of applying an adhesive composition A containing 10 to 99% by mass of a polymerizable compound X having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less to the bonding surface of the polarizer while conveying the polarizer to form a first coating film;
A second coating step of applying an adhesive composition B containing 25 to 80% by mass of the polymerizable compound X to the bonding surface of the transparent protective film while conveying the transparent protective film to form a second coating film;
A thickness measurement step of in-line measuring the thickness of the first coating film and the second coating film;
Based on the thicknesses of the first coating film and the second coating film obtained by the in-line measurement, the content of the polymerizable compound X in the uncured adhesive layer obtained by bonding the first coating film and the second coating film is 40 to 64% by mass.
The present invention relates to a method for producing a polarizing film, comprising: a bonding step of bonding a bonding surface of the polarizer on which the first coating film is formed and a bonding surface of the transparent protective film on which the second coating film is formed to form the uncured adhesive layer; and a bonding step of bonding the polarizer and the transparent protective film via the adhesive layer obtained by curing the uncured adhesive layer.

In the method for producing a polarizing film, the adhesive composition A and/or the adhesive composition B contains a polymerization initiator,
The coating amount adjustment process is based on the thickness of the 1st coating film obtained by the inline measurement and the thickness of the second coating film, so that the content of the polymerization starting agent in the unhoused adhesive layer is obtained by pasting the first coating and the second coating film. It is preferable that the process of adjusting the amount of coating of the adhesive assembly B in the coating of the adhesive assembly composition A in the coating process and the amount of coating of the adhesive assembly B in the second coating process.

In the method for producing a polarizing film, the polymerizable compound X is preferably at least one selected from the group consisting of acryloylmorpholine, N-methoxymethylacrylamide, and N-ethoxymethylacrylamide.

で表される化合物（ただし、Ｘは反応性基を含む官能基であり、Ｒ^１およびＲ^２はそれぞれ独立に、水素原子、置換基を有してもよい、脂肪族炭化水素基、アリール基、またはヘテロ環基を表す）及び／又は構造式中にＭ－Ｏ結合（Ｍはケイ素、チタン、アルミニウム、またはジルコニウムであり、Ｏは酸素原子である）を有する有機金属化合物を含有することが好ましい。なお、本発明においては、前記一般式（１）で表される化合物を「ホウ素含有化合物」ともいう。 In the method for producing a polarizing film, the adhesive composition A has the following general formula (1):

(where X is a functional group containing a reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group, or a heterocyclic group) and/or an organometallic compound having an MO bond (M is silicon, titanium, aluminum, or zirconium, and O is an oxygen atom) in the structural formula. In addition, in this invention, the compound represented by the said General formula (1) is also called a "boron-containing compound."

で表される化合物（ただし、Ｙは有機基であり、Ｘ、Ｒ^１およびＲ^２は前記と同じ）であることが好ましい。 In the method for producing a polarizing film, the compound represented by the general formula (1) is represented by the following general formula (1′)

(where Y is an organic group, and X, R ¹ and R ² are the same as above).

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

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

In the method for producing a polarizing film, the post-measurement coating method is preferably a gravure roll coating method using a gravure roll.

Conventionally, in the continuous production of polarizing films, when an adhesive composition is applied to both the bonding surface of a polarizer and the bonding surface of a transparent protective film to form a coating film, the thickness of each coating film was initially set. It was determined by the amount of application of each adhesive composition. In addition, in the step of applying each adhesive composition, it was believed that each adhesive composition was quantitatively applied in an initially set application amount. Therefore, no particular operation was performed to change the coating amount of each adhesive composition during continuous production, and the thickness of each coating film was not strictly controlled.

However, due to changes in the viscosity of each adhesive composition, precipitation of solid matter, etc., the coating member of the coating machine is clogged with each adhesive composition, or the surface condition of the coating member or blade changes during maintenance of the coating machine. If the thickness of each coating film fluctuates significantly during continuous production, the content of components contained in each coating film (e.g., curable components, polymerization initiators, etc.) also fluctuates significantly, making it difficult to stably form an adhesive layer with uniform adhesive properties, making it difficult to continuously and stably produce a polarizing film with excellent adhesiveness.

According to the method for producing a polarizing film of the present invention, by adopting the thickness measuring step and the coating amount adjusting step, it is possible to suppress large fluctuations in the thickness of the first coating film and / or the second coating film during continuous production, thereby suppressing fluctuations in the content of the components contained in the first coating film and / or the second coating film. Therefore, it is possible to stably form an adhesive layer with uniform adhesive properties. As a result, it is possible to continuously and stably produce a polarizing film having excellent adhesiveness.

The adhesive compositions A and B contain a polymerizable compound X having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less. Since the SP value of the polymerizable compound X is close to the SP value of transparent protective films such as unsaponified triacetyl cellulose films and acrylic films, the polymerizable compound X contributes to improving the adhesion between the adhesive layer and the transparent protective film.

In the method for producing a polarizing film of the present invention, the adhesive composition A contains 10 to 99% by mass of the polymerizable compound X, and the adhesive composition B contains 25 to 80% by mass of the polymerizable compound X. As described above, the polymerizable compound X contributes to improving the adhesiveness between the adhesive layer and the transparent protective film, so it is preferable to add a large amount of the polymerizable compound X to the adhesive composition B. However, when a large amount of the polymerizable compound X is blended in the adhesive composition B, the polymerizable compound X tends to penetrate into the transparent protective film, and excessive penetration of the polymerizable compound X into the transparent protective film facilitates the formation of a fragile layer in the adhesive layer. As a result, the adhesiveness between the adhesive layer and the transparent protective film tends to decrease. As in the present invention, by blending a part of the polymerizable compound X to be blended in the adhesive composition B into the adhesive composition A, the total amount of the polymerizable compound X (the content of the polymerizable compound X in the uncured adhesive layer) is maintained (without reducing), and the excessive permeation of the polymerizable compound X into the transparent protective film can be suppressed. As a result, deterioration in the adhesion between the adhesive layer and the transparent protective film can be suppressed. Thus, in the method for producing a polarizing film of the present invention, since the polymerizable compound X is blended in both the adhesive compositions A and B, the total blending amount of the polymerizable compound X (the content of the polymerizable compound X in the uncured adhesive layer) is adjusted to be uniform by the thickness measurement step and the coating amount adjustment step.

Further, in the method for producing a polarizing film of the present invention, since the polymerizable compound X is blended in both the adhesive compositions A and B, the polymerizable compound X is adjusted by the thickness measurement step and the coating amount adjustment step so that the blended amount of the polymerization initiator (the content of the polymerization initiator in the uncured adhesive layer) with respect to the total blended amount of the curable components (total content of the curable components in the uncured adhesive layer) is uniform.

The adhesive composition A preferably contains the boron-containing compound. The boron-containing compound can react with functional groups such as hydroxyl groups provided in the polarizer. This makes it possible to improve the adhesiveness between the polarizer and the adhesive layer, resulting in an effect of improving the water-resistant adhesiveness of the polarizing film.

The adhesive composition A preferably contains the organometallic compound. The organometallic compound becomes an active metal species through the presence of moisture, and as a result, the organometallic compound can form a strong bond with the polarizer. However, since the organometallic compound has a plurality of reaction points, the organometallic compound reacted with the polarizer still has unreacted points. Then, the organometallic compound can form a strong bond with the curable component in the second coating film formed on the bonding surface of the transparent protective film. As described above, the organometallic compound can form a strong bond with both the polarizer and the adhesive layer, thereby dramatically improving the water-resistant adhesion between the polarizer and the adhesive layer.

The first coating step and the second coating step are preferably coating steps using a post-metering coating method. Thereby, while improving the adhesiveness of the polarizing film, it is possible to improve the coatability when applying the adhesive compositions A and B, and it is possible to improve the thickness uniformity of the first coating film and the second coating film. In the present invention, the "post-metering coating method" means a method of applying an external force to the liquid film to remove excess liquid to obtain a predetermined coating film thickness. Specific examples of the post-metering coating method include gravure roll coating, forward roll coating, air knife coating, and rod/bar coating.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of the manufacturing method of the polarizing film of this invention.

The present invention is a method for producing a polarizing film in which a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer,
A first coating step of applying an adhesive composition A containing 10 to 99% by mass of a polymerizable compound X having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less to the bonding surface of the polarizer while conveying the polarizer to form a first coating film;
A second coating step of applying an adhesive composition B containing 25 to 80% by mass of the polymerizable compound X to the bonding surface of the transparent protective film while conveying the transparent protective film to form a second coating film;
A thickness measurement step of in-line measuring the thickness of the first coating film and the second coating film;
Based on the thicknesses of the first coating film and the second coating film obtained by the in-line measurement, the content of the polymerizable compound X in the uncured adhesive layer obtained by bonding the first coating film and the second coating film is 40 to 64% by mass.
A bonding step of bonding a bonding surface of the polarizer on which the first coating film is formed and a bonding surface of the transparent protective film on which the second coating film is formed to form the uncured adhesive layer; and a bonding step of bonding the polarizer and the transparent protective film via the adhesive layer obtained by curing the uncured adhesive layer.

Hereinafter, the method for producing the polarizing film of the present invention will be described in detail.

<Adhesive compositions A and B>
The mode of curing the adhesive compositions A and B can be broadly classified into heat curing and active energy ray curing. Resins constituting the thermosetting adhesive composition include polyvinyl alcohol resins, epoxy resins, unsaturated polyesters, urethane resins, acrylic resins, urea resins, melamine resins, phenol resins, etc., and if necessary, a curing agent is used in combination. Polyvinyl alcohol resins and epoxy resins are more preferably used as resins constituting the thermosetting adhesive composition. Active energy ray-curable adhesive compositions can be broadly classified into electron beam curable, ultraviolet ray curable and visible ray curable according to active energy ray. In addition, the mode of curing can be classified into a radically polymerizable adhesive composition and a cationic polymerizable adhesive composition. In the present invention, active energy rays with a wavelength range of 10 nm to less than 380 nm are expressed as ultraviolet rays, and active energy rays with a wavelength range of 380 nm to 800 nm are expressed as visible rays.

In the production of the polarizing film according to the present invention, the adhesive compositions A and B are preferably active energy ray-curable. Furthermore, it is particularly preferred to be visible light curable using visible light of 380 nm to 450 nm.

Examples of the curable component contained in the radically polymerizable adhesive composition include radically polymerizable compounds used in the radically polymerizable adhesive composition. Examples of radically polymerizable compounds include compounds having radically polymerizable functional groups of carbon-carbon double bonds such as (meth)acryloyl groups and vinyl groups. These curable components can be either monofunctional radically polymerizable compounds or bifunctional or higher polyfunctional radically polymerizable compounds. Moreover, these radical polymerizable compounds can be used individually by 1 type or in combination of 2 or more types. As these radically polymerizable compounds, for example, compounds having a (meth)acryloyl group are suitable. In the present invention, (meth)acryloyl means an acryloyl group and/or a methacryloyl group, and "(meth)" has the same meaning below.

で表される化合物（ただし、Ｒ^３は水素原子またはメチル基であり、Ｒ^４およびＲ^５はそれぞれ独立に、水素原子、アルキル基、ヒドロキシアルキル基、アルコキシアルキル基または環状エーテル基であって、Ｒ^４およびＲ^５は環状複素環を形成してもよい）が挙げられる。アルキル基、ヒドロキシアルキル基、および／またはアルコキシアルキル基のアルキル部分の炭素数は特に限定されないが、例えば１～４個のものが例示される。また、Ｒ^４およびＲ^５が形成してもよい環状複素環は、例えばＮ－アクリロイルモルホリンなどが挙げられる。 Examples of monofunctional radically polymerizable compounds include the following general formula (2):

(where R ³ is a hydrogen atom or a methyl group, R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, and R ⁴ and R ⁵ may form a cyclic heterocyclic ring). Although the number of carbon atoms in the alkyl portion of the alkyl group, hydroxyalkyl group and/or alkoxyalkyl group is not particularly limited, examples thereof include 1 to 4 carbon atoms. In addition, examples of the cyclic heterocycle that may be formed by R ⁴ and R ⁵ include N-acryloylmorpholine.

Specific examples of the compound represented by formula (2) include N-alkyl group-containing (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-methylol-N-pro N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as pan(meth)acrylamide; and N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide. Examples of the cyclic ether group-containing (meth)acrylamide derivatives include heterocycle-containing (meth)acrylamide derivatives in which the nitrogen atom of the (meth)acrylamide group forms a heterocyclic ring, such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like.

The adhesive compositions A and B used in the present invention contain a polymerizable compound X having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less as a curable component.

As the polymerizable compound X, any compound having a radical polymerizable group such as a (meth)acrylate group and having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less can be used without limitation. Examples of the polymerizable compound X include acryloylmorpholine (SP value 22.9), N-methoxymethylacrylamide (SP value 22.9), N-ethoxymethylacrylamide (SP value 22.3) and the like. Commercially available products can also be suitably used as the polymerizable compound X. Examples include ACMO (manufactured by Kojin Co., Ltd., SP value 22.9), Wasmer 2MA (manufactured by Kasano Kosan Co., Ltd., SP value 22.9), Wasmer EMA (manufactured by Kasano Kosan Co., Ltd., SP value 22.3), and Wasmer 3MA (manufactured by Kasano Kosan Co., Ltd., SP value 22.4). These may be used alone or in combination of two or more. Among these, acryloylmorpholine is preferably used.

Here, the method for calculating the SP value (solubility parameter) in the present invention will be described below.

（ただしΔｅｉは原子または基に帰属する２５℃における蒸発エネルギー、Δｖｉは２５℃におけるモル体積である）にて計算して求めることができる。 (Calculation method of solubility parameter (SP value))
In the present invention, the solubility parameter (SP value) of the polymerizable compound X is calculated according to Fedors' calculation method ["Polymer Eng. &Sci.", Vol. 14, No. 2 (1974), pp. 148-154].

(where Δei is the vaporization energy at 25° C. attributed to the atom or group, and Δvi is the molar volume at 25° C.).

Δei and Δvi in the above formula represent constant numerical values given to i atoms and groups in the main molecule. Also, representative examples of numerical values of Δe and Δv given for atoms or groups are shown in Table 1 below.

As described above, the content of the polymerizable compound X in the adhesive composition A is 10% by mass or more, preferably 30% by mass or more, and more preferably 50% by mass or more, from the viewpoint of suppressing excessive permeation of the polymerizable compound X into the transparent protective film by blending part of the polymerizable compound X in the adhesive composition B into the adhesive composition A. From the viewpoint of imparting an anchoring effect between the The content of the polymerizable compound X in the adhesive composition A is adjusted in consideration of the content of the polymerizable compound X in the adhesive composition B so that the content of the polymerizable compound X in the uncured adhesive layer obtained by laminating the first coating and the second coating is 40 to 64% by mass.

On the other hand, as described above, the content of the polymerizable compound X in the adhesive composition B is 80% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less from the viewpoint of suppressing excessive permeation of the polymerizable compound X into the transparent protective film by blending part of the polymerizable compound X in the adhesive composition B into the adhesive composition A. On the other hand, from the viewpoint of improving the adhesiveness between the adhesive layer and the transparent protective film, it is 25% by mass or more. Yes, preferably 35% by mass or more, more preferably 40% by mass or more. The content of the polymerizable compound X in the adhesive composition B is adjusted in consideration of the content of the polymerizable compound X in the adhesive composition A so that the content of the polymerizable compound X in the uncured adhesive layer obtained by laminating the first coating and the second coating is 40 to 64% by mass.

で表される化合物（ただし、Ｘは反応性基を含む官能基であり、Ｒ^１およびＲ^２はそれぞれ独立に、水素原子、置換基を有してもよい、脂肪族炭化水素基、アリール基、またはヘテロ環基を表す）を含有することが好ましい。前記脂肪族炭化水素基としては、炭素数１～２０の置換基を有してもよい直鎖または分岐のアルキル基、炭素数３～２０の置換基を有してもよい環状アルキル基、炭素数２～２０のアルケニル基が挙げられ、アリール基としては、炭素数６～２０の置換基を有してもよいフェニル基、炭素数１０～２０の置換基を有してもよいナフチル基などが挙げられ、ヘテロ環基としては例えば、少なくとも一つのヘテロ原子を含む、置換基を有してもよい５員環または６員環の基が挙げられる。これらは互いに連結して環を形成してもよい。一般式（１）中、Ｒ^１およびＲ^２として好ましくは、水素原子、炭素数１～３の直鎖または分岐のアルキル基であり、最も好ましくは、水素原子である。なお、一般式（１）で表される化合物は、最終的に形成される接着剤層中に未反応の状態で存在しても良く、各官能基が反応した状態で存在しても良い。 Further, the adhesive composition A has the following general formula (1):

(where X is a functional group containing a reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group, or a heterocyclic group). Examples of the aliphatic hydrocarbon group include linear or branched alkyl groups optionally having substituents having 1 to 20 carbon atoms, cyclic alkyl groups having 3 to 20 carbon atoms optionally having substituents, and alkenyl groups having 2 to 20 carbon atoms. Examples of the aryl groups include phenyl groups optionally having substituents having 6 to 20 carbon atoms and naphthyl groups optionally having substituents having 10 to 20 carbon atoms. 5- or 6-membered ring groups optionally having These may be linked together to form a ring. In formula (1), R ¹ and R ² are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, most preferably a hydrogen atom. The compound represented by the general formula (1) may exist in the finally formed adhesive layer in an unreacted state, or may exist in a state in which each functional group is reacted.

X possessed by the compound represented by the general formula (1) is a functional group containing a reactive group, which is a functional group capable of reacting with a curable component constituting the adhesive layer. Examples of the reactive group contained in X include a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, an α,β-unsaturated carbonyl group, a mercapto group, and a halogen group. When the adhesive composition constituting the adhesive layer is active energy ray-curable, the reactive group contained in X is preferably at least one reactive group selected from the group consisting of a vinyl group, a (meth)acrylic group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group and a mercapto group. and (meth)acrylamide groups, and when the compound represented by the general formula (1) has a (meth)acrylamide group, the reactivity is high and the copolymerization ratio with the active energy ray adhesive composition is more preferable. In addition, the (meth)acrylamide group has a high polarity and is excellent in adhesiveness, so it is preferable from the viewpoint that the effects of the present invention can be obtained efficiently. When the adhesive composition constituting the adhesive layer is cationically polymerizable, the reactive group contained in X preferably has at least one functional group selected from a hydroxyl group, an amino group, an aldehyde, a carboxyl group, a vinyl ether group, an epoxy group, an oxetane group, and a mercapto group. Particularly when it has an epoxy group, it is preferable because the adhesion between the obtained adhesive layer and the adherend is excellent, and when it has a vinyl ether group, it is preferable because the curability of the adhesive composition is excellent.

で表される化合物（ただし、Ｙは有機基であり、Ｘ、Ｒ^１およびＲ^２は前記と同じ）が挙げられる。さらに好適には、以下の化合物（１ａ）～（１ｄ）が挙げられる。 Preferred specific examples of the compound represented by the general formula (1) include the following general formula (1′)

(where Y is an organic group, and X, R ¹ and R ² are the same as above). More preferred are the following compounds (1a) to (1d).

In the present invention, the compound represented by the general formula (1) may be one in which the reactive group and the boron atom are directly bonded, but as shown in the specific example above, the compound represented by the general formula (1) is preferably a compound in which the reactive group and the boron atom are bonded via an organic group, that is, the compound represented by the general formula (1'). For example, when the compound represented by the general formula (1) is bonded to a reactive group via an oxygen atom bonded to a boron atom, the polarizing film tends to deteriorate in waterproof adhesion. On the other hand, the compound represented by the general formula (1) does not have a boron-oxygen bond, and the boron atom and the organic group are bonded to each other, thereby having a boron-carbon bond and a reactive group. The organic group specifically means an organic group having 1 to 20 carbon atoms which may have a substituent, more specifically, for example, a linear or branched alkylene group which may have a substituent having 1 to 20 carbon atoms, a cyclic alkylene group which may have a substituent having 3 to 20 carbon atoms, a phenylene group which may have a substituent having 6 to 20 carbon atoms, a naphthylene group which may have a substituent having 10 to 20 carbon atoms, and the like.

Examples of the compound represented by the general formula (1) include, in addition to the compounds exemplified above, esters of (meth)acrylate and boric acid, such as esters of hydroxyethylacrylamide and boric acid, esters of methylolacrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.

If the content of the compound represented by the general formula (1) in the adhesive composition A is too small, the ratio of the compound represented by the general formula (1) present at the interface between the polarizer and the adhesive layer decreases, and the adhesion between the polarizer and the adhesive layer may decrease. Therefore, the content of the compound represented by general formula (1) in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more. In addition, the content of the compound represented by general formula (1) in the adhesive composition A is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less.

Also, the adhesive composition A preferably contains an organometallic compound having an MO bond (M is silicon, titanium, aluminum, or zirconium, and O is an oxygen atom) in its structural formula. The organometallic compound may exist in an unreacted state in the finally formed adhesive layer, or may exist in a state in which each functional group is reacted.

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

As the organosilicon compound, those having a Si—O bond can be used without particular limitation, and specific examples thereof include active energy ray-curable organosilicon compounds and non-active energy ray-curable organosilicon compounds. In particular, it is preferable that the organic group of the organosilicon compound has 3 or more carbon atoms. Specific examples of active energy ray-curable compounds include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxysilane. roxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like.

Preferred are 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane.

A compound having an amino group is preferable as the compound that is not active energy ray-curable. Specific examples of compounds having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiethoxysilane. . amino group-containing silanes such as -aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl)aminomethyltrimethoxysilane, N,N'-bis[3-(trimethoxysilyl)propyl]ethylenediamine; ketimine-type silanes such as N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine can be mentioned.

Only one compound having an amino group may be used, or a plurality of such compounds may be used in combination. Among these, γ-aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiethoxysilane, and N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine are preferred in order to ensure good adhesion.

Specific examples of non-active energy ray-curable compounds other than the above include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazolesilane.

The metal alkoxide is a compound in which at least one alkoxy group, which is an organic group, is bonded to a metal, and the metal chelate is a compound in which an organic group is bonded or coordinated to a metal via an oxygen atom. Preferred metals are titanium, aluminum and zirconium. Among these, aluminum and zirconium have faster reactivity than titanium, which may shorten the pot life of the adhesive composition A and reduce the effect of improving water-resistant adhesion. Therefore, from the viewpoint of improving the water-resistant adhesiveness of the adhesive layer, titanium is more preferable as the metal of the organometallic compound.

When the adhesive composition A contains a metal alkoxide as an organometallic compound, it is preferable to use an organic group having 3 or more carbon atoms in the metal alkoxide, more preferably 6 or more. If the number of carbon atoms is 2 or less, the pot life of the adhesive composition A may be shortened, and the effect of improving water-resistant adhesion may be lowered. Examples of the organic group having 6 or more carbon atoms include an octoxy group, which can be preferably used. Suitable metal alkoxides include, for example, tetraisopropyl titanate, tetra-butyl titanate, butyl titanate dimer, tetraoctyl titanate, tertiary amyl titanate, tetra tertiary butyl titanate, tetrastearyl titanate, zirconium tetraisopropoxide, zirconium tetra normal butoxide, zirconium tetraoctoxide, zirconium tetratertiary butoxide, zirconium tetrapropoxide, aluminum sec. Tylate, aluminum ethylate, aluminum isopropylate, aluminum butyrate, aluminum diisopropylate mono-secondary butyrate, mono-sec butoxyaluminum diisopropylate, and the like. Among them, tetraoctyl titanate is preferred.

When the adhesive composition A contains a metal chelate as the organometallic compound, it preferably contains an organic group having 3 or more carbon atoms in the metal chelate. If the number of carbon atoms is 2 or less, the pot life of the adhesive composition A may be shortened, and the effect of improving the water-resistant adhesion of the polarizing film may be reduced. Organic groups having 3 or more carbon atoms include, for example, an acetylacetonate group, an ethylacetoacetate group, an isostearate group, an octylene glycolate group, and the like. Among these, an acetylacetonate group or an ethylacetoacetate group is preferable as the organic group from the viewpoint of improving the water-resistant adhesiveness of the adhesive layer. Suitable metal chelates include, for example, titanium acetylacetonate, titanium octylene glycolate, titanium tetraacetylacetonate, titanium ethylacetoacetate, polyhydroxytitanium stearate, dipropoxy-bis(acetylacetonate) titanium, dibutoxytitanium-bis(octylene glycolate), dipropoxytitanium-bis(ethylacetoacetate), titanium lactate, titanium diethanolamine, titanium triethanolamine, dipropoxytitanium-bis( lactate), dipropoxytitanium-bis (triethanolaminate), di-n-butoxytitanium-bis (triethanolaminate), tri-n-butoxytitanium monostearate, diisopropoxy bis (ethylacetoacetate) titanium, diisopropoxy bis (acetylacetate) titanium, diisopropoxy bis (acetylacetone) titanium, titanium phosphate compound, titanium lactate ammonium salt, titanium-1,3-pro Pandioxybis(ethylacetoacetate), titanium dodecylbenzenesulfonate, titanium aminoethylaminoethanolate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium acetylacetonate bisethylacetoacetate, zirconium acetate, tri-n-butoxyethylacetoacetate zirconium, di-n-butoxybis(ethylacetoacetate) zirconium, n-butoxy Tris(ethylacetoacetate) zirconium, tetrakis(n-propylacetoacetate) zirconium, tetrakis(acetylacetoacetate) zirconium, tetrakis(ethylacetoacetate) zirconium, aluminum ethylacetoacetate, aluminum acetylacetonate, aluminum acetylacetonate bisethylacetoacetate, diisopropoxyethylacetoacetate aluminum, diisopropoxyacetylacetonate aluminum, isopropoxybis(ethylacetoacetate) aluminum, iso propoxybis(acetylacetonato)aluminum, tris(ethylacetoacetate)aluminum, tris(acetylacetonato)aluminum, monoacetylacetonato-bis(ethylacetoacetate)aluminum. Among them, titanium acetylacetonate and titanium ethylacetoacetate are preferable.

Examples of organometallic compounds that can be used in the present invention include, in addition to the above, organic carboxylic acid metal salts such as zinc octylate, zinc laurate, zinc stearate, and tin octylate, and zinc chelate compounds such as zinc acetylacetone chelate, zinc benzoylacetone chelate, zinc dibenzoylmethane chelate, and ethyl zinc acetoacetate chelate.

If the content of the organometallic compound in the adhesive composition A is too small, the ratio of the organometallic compound present at the interface between the polarizer and the adhesive layer is reduced, and the adhesion between the polarizer and the adhesive layer may be reduced. Therefore, the content of the organometallic compound in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more. Moreover, the content of the organometallic compound in the adhesive composition A is usually 10% by mass or less.

In the present invention, the compound represented by the general formula (1), preferably the compound represented by the general formula (1'), and more preferably the compound represented by the general formulas (1a) to (1d) can be blended into the adhesive composition B. Further, in the present invention, the organometallic compound can be blended in the adhesive composition B. When these compounds are blended in the adhesive composition B, the adhesiveness to the polarizer and the transparent protective film may be improved, which is preferable. From the viewpoint of improving the adhesiveness and water resistance when the polarizer and the transparent protective film are adhered via the adhesive layer, the content of the compound represented by the general formula (1) in the adhesive composition B is preferably 0.001 to 50% by mass, more preferably 0.1 to 30% by mass, and further preferably 1 to 10% by mass. The content of the organometallic compound in the adhesive composition B is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 1.0 to 3% by mass.

Moreover, the adhesive compositions A and B may contain a monofunctional radically polymerizable compound other than the above as a curable component. Examples of monofunctional radically polymerizable compounds include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Examples of the (meth)acrylic acid derivatives 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, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n -hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, n-octadecyl (meth)acrylate (meth)acrylic acid (C1-20) alkyl esters.

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; Cyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and other polycyclic (meth)acrylates; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethylcarbitol (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxypolyethylene glycol (meth)acrylate, and other alkoxy or phenoxy group-containing (meth)acrylates; . Among these, dicyclopentenyloxyethyl acrylate and phenoxyethyl acrylate are preferred because of their excellent adhesion to various protective films.

Examples of the (meth)acrylic acid derivative include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as 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 acrylates, heptadecafluorodecyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; ) oxetane group-containing (meth)acrylates such as acrylate; tetrahydrofurfuryl (meth)acrylate, butyrolactone (meth)acrylate, and other heterocyclic (meth)acrylates, neopentylglycol hydroxypivalate (meth)acrylic acid adducts, and p-phenylphenol (meth)acrylate. Among these, 2-hydroxy-3-phenoxypropyl acrylate is preferable because of its excellent adhesion to various protective films.

Examples of monofunctional radically polymerizable compounds 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 monofunctional radically polymerizable compounds include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinyl-based monomers having a nitrogen-containing heterocyclic ring, such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

Among the monofunctional radically polymerizable compounds, if a hydroxyl group-containing (meth)acrylate, a carboxyl group-containing (meth)acrylate, or a phosphoric acid group-containing (meth)acrylate having high polarity is contained, adhesion to various transparent protective films is improved. The content of the hydroxyl group-containing (meth)acrylate in the adhesive composition A or B is preferably 1% by mass to 30% by mass. If the content of the hydroxyl group-containing (meth)acrylate is too high, the water absorption rate of the cured product may increase and the water resistance may deteriorate. The content of the carboxyl group-containing (meth)acrylate in the adhesive composition A or B is preferably 1% by mass to 20% by mass. When the content of the carboxyl group-containing (meth)acrylate is too high, the optical durability of the polarizing film is lowered, which is not preferable. Phosphate group-containing (meth)acrylates include 2-(meth)acryloyloxyethyl acid phosphate, and the content thereof in adhesive composition A or B is preferably 0.1% by mass to 10% by mass. When the content of the phosphate group-containing (meth)acrylate is too high, the optical durability of the polarizing film is lowered, which is not preferable.

Moreover, a radically polymerizable compound having an active methylene group can be used as the monofunctional radically polymerizable compound. A radically polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acrylic group at the end or in the molecule and an active methylene group. Active methylene groups include, for example, an acetoacetyl group, an alkoxymalonyl group, a cyanoacetyl group, and the like. Preferably, the active methylene group is an acetoacetyl group. Examples of the radically 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; -acetoacetoxymethylbenzyl)acrylamide, N-(2-acetoacetylaminoethyl)acrylamide and the like. The radically polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth)acrylate.

Examples of the difunctional or higher polyfunctional radically polymerizable compound include polyfunctional (meth)acrylamide derivatives such as N,N'-methylenebis(meth)acrylamide, 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, and bisacrylate phenol A di(meth)acrylate. , bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate acrylates, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, esters of (meth)acrylic acid and polyhydric alcohols such as EO-modified diglycerin tetra(meth)acrylate, and 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include Aronix M-220 (manufactured by Toagosei Co., Ltd.), light acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer), CD-536 (manufactured by Sartomer), and the like. Various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, various (meth)acrylate monomers, and the like can also be used as necessary. In addition, the polyfunctional (meth)acrylamide derivative has a high polymerization rate and excellent productivity, and also has excellent crosslinkability when the adhesive composition is used as a cured product, so it is preferable to include it in the adhesive composition.

It is preferable to use a monofunctional radically polymerizable compound and a multifunctional radically polymerizable compound together from the viewpoint of achieving both adhesion to a polarizer and various transparent protective films and optical durability in a harsh environment. Since the monofunctional radically polymerizable compound has a relatively low liquid viscosity, the liquid viscosity of the adhesive composition can be lowered by including it in the adhesive composition. In addition, the monofunctional radically polymerizable compound often has a functional group that exhibits various functions, and by including it in the adhesive composition, the adhesive composition and / or the cured product of the adhesive composition can exhibit various functions. The polyfunctional radically polymerizable compound is preferably contained in the adhesive composition because it can three-dimensionally crosslink the cured product of the adhesive composition. It is preferable to use 10 to 1000 parts by mass of the polyfunctional radically polymerizable compound with respect to 100 parts by mass of the monofunctional radically polymerizable compound.

When an electron beam or the like is used as the active energy ray, the radically polymerizable adhesive composition does not need to contain a photopolymerization initiator. However, when ultraviolet rays or visible light is used as the active energy ray, the adhesive compositions A and/or B preferably contain a photopolymerization initiator.

A photopolymerization initiator in the case of using a radically polymerizable compound is appropriately selected depending on the active energy ray. When curing with ultraviolet light or visible light, a photopolymerization initiator that is cleaved with ultraviolet light or visible light is used. Examples of the photopolymerization initiator include benzophenone compounds such as benzyl, benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α-hydroxycyclohexylphenylketone; Acetophenone compounds such as methoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether compounds; aromatic ketal compounds such as benzyl dimethyl ketal; Aromatic sulfonyl chloride compounds such as nyl chloride; Photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone-based compounds; camphorquinone; halogenated ketones; acylphosphinoxide;

The amount of the photopolymerization initiator is preferably 20% by mass or less in the adhesive composition A and / or B, more preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and particularly preferably 0.1 to 5% by mass. The content of the photopolymerization initiator in the adhesive composition A and / or B is adjusted so that the content of the photopolymerization initiator in the uncured adhesive layer obtained by bonding the first coating and the second coating is 2.3 to 7% by mass.

When the adhesive compositions A and B are curable with visible light containing a radically polymerizable compound as a curable component, it is preferable to use a photopolymerization initiator that is particularly sensitive to light of 380 nm or longer. A photopolymerization initiator highly sensitive to light of 380 nm or more will be described later.

（式中、Ｒ^６およびＲ^７は－Ｈ、－ＣＨ_２ＣＨ_３、－ｉＰｒまたはＣｌを示し、Ｒ^６およびＲ^７は同一または異なっても良い）を単独で使用するか、あるいは一般式（３）で表される化合物と後述する３８０ｎｍ以上の光に対して高感度な光重合開始剤とを併用することが好ましい。一般式（３）で表される化合物を使用した場合、３８０ｎｍ以上の光に対して高感度な光重合開始剤を単独で使用した場合に比べて接着性に優れる。一般式（３）で表される化合物の中でも、Ｒ^６およびＲ^７が－ＣＨ_２ＣＨ_３であるジエチルチオキサントンが特に好ましい。接着剤組成物Ａ又はＢ中の一般式（３）で表される化合物の組成比率は、接着剤組成物Ａ又はＢの全量に対して、０．１～５質量％であることが好ましく、０．５～４質量％であることがより好ましく、０．９～３質量％であることがさらに好ましい。 As the photopolymerization initiator, a compound represented by the following general formula (3);

(Wherein, R ⁶ and R ⁷ represent —H, —CH ₂ CH ₃ , —iPr, or Cl, and R ⁶ and R ⁷ may be the same or different) is used alone, or the compound represented by general formula (3) and a photopolymerization initiator highly sensitive to light of 380 nm or longer, which will be described later, are preferably used in combination. When the compound represented by the general formula (3) is used, the adhesiveness is excellent as compared with the case where a photopolymerization initiator highly sensitive to light of 380 nm or more is used alone. Among the compounds represented by general formula (3), diethylthioxanthone in which R ⁶ and R ⁷ are —CH ₂ CH ₃ is particularly preferred. The composition ratio of the compound represented by general formula (3) in the adhesive composition A or B is preferably 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 0.9 to 3% by mass, relative to the total amount of the adhesive composition A or B.

Moreover, it is preferable to add a polymerization initiation aid as necessary. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and ethyl 4-dimethylaminobenzoate is particularly preferred. When a polymerization initiation aid is used, the amount added is generally 0 to 5% by mass, preferably 0 to 4% by mass, most preferably 0 to 3% by mass, relative to the total amount of adhesive composition A or B.

Moreover, a well-known photoinitiator can be used together as needed. Since the transparent protective film having UV absorbability does not transmit light of 380 nm or less, it is preferable to use a photopolymerization initiator that is highly sensitive to light of 380 nm or more. Specifically, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4 ,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium and the like.

（式中、Ｒ^８、Ｒ^９およびＲ^１０は－Ｈ、－ＣＨ_３、－ＣＨ_２ＣＨ_３、－ｉＰｒまたはＣｌを示し、Ｒ^８、Ｒ^９およびＲ^１０は同一または異なっても良い）を使用することが好ましい。一般式（４）で表される化合物としては、市販品でもある２－メチル－１－（４－メチルチオフェニル）－２－モルフォリノプロパン－１－オン（商品名：ＩＲＧＡＣＵＲＥ９０７ メーカー：ＢＡＳＦ）が好適に使用可能である。その他、２－ベンジル－２－ジメチルアミノ－１－（４－モルフォリノフェニル）－ブタノン－１（商品名：ＩＲＧＡＣＵＲＥ３６９ メーカー：ＢＡＳＦ）、２－（ジメチルアミノ）－２－［（４－メチルフェニル）メチル］－１－［４－（４－モルホリニル）フェニル］－１－ブタノン（商品名：ＩＲＧＡＣＵＲＥ３７９ メーカー：ＢＡＳＦ）が感度が高いため好ましい。 In particular, as a photopolymerization initiator, in addition to the photopolymerization initiator of general formula (3), a compound represented by the following general formula (4);

(wherein R ⁸ , R ⁹ and R ¹⁰ represent —H, —CH ₃ , —CH ₂ CH ₃ , —iPr or Cl, and R ⁸ , R ⁹ and R ¹⁰ may be the same or different) is preferably used. As the compound represented by the general formula (4), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (trade name: IRGACURE907, manufacturer: BASF), which is also commercially available, can be preferably used. In addition, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (trade name: IRGACURE369, manufacturer: BASF) and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (trade name: IRGACURE379, manufacturer: BASF) are preferred due to their high sensitivity.

When a radically polymerizable compound having an active methylene group is used as the radically polymerizable compound, it is preferably used in combination with a radical polymerization initiator capable of abstracting hydrogen. According to such a configuration, the adhesiveness of the adhesive layer of the polarizing film is remarkably improved even immediately after being taken out from a high-humidity environment or water (in a non-dried state). Although the reason for this is not clear, the following causes are conceivable. That is, the radically polymerizable compound having an active methylene group is incorporated into the main chain and/or side chains of the base polymer in the adhesive layer while being polymerized together with other radically polymerizable compounds constituting the adhesive layer, forming the adhesive layer. In the polymerization process, if a radical polymerization initiator having a hydrogen-abstracting action is present, hydrogen is abstracted from the radically polymerizable compound having an active methylene group while the base polymer constituting the adhesive layer is being formed, and radicals are generated in the methylene group. Then, the methylene groups generated by the radicals react with the hydroxyl groups of the polarizer such as PVA to form covalent bonds between the adhesive layer and the polarizer. As a result, it is presumed that the adhesiveness of the adhesive layer of the polarizing film is remarkably improved even in a non-dried state.

Examples of radical polymerization initiators having a hydrogen abstraction action include thioxanthone-based radical polymerization initiators and benzophenone-based radical polymerization initiators. The radical polymerization initiator is preferably a thioxanthone radical polymerization initiator. Examples of the thioxanthone-based radical polymerization initiator include compounds represented by the above general formula (3). Specific examples of the compound represented by formula (3) include thioxanthone, dimethylthioxanthone, diethylthioxanthone, isopropylthioxanthone, and chlorothioxanthone. Among the compounds represented by general formula (3), diethylthioxanthone in which R ⁶ and R ⁷ are —CH ₂ CH ₃ is particularly preferred.

In the case of containing a radically polymerizable compound having an active methylene group and a radical polymerization initiator having a hydrogen abstraction action, when the total amount of the curable component is 100% by mass, the radically polymerizable compound having the active methylene group is preferably contained in an amount of 1 to 50% by mass, and the radical polymerization initiator is preferably contained in an amount of 0.1 to 10% by mass with respect to the total amount of the adhesive composition A or B.

As described above, in the present invention, a radical is generated in the methylene group of a radically polymerizable compound having an active methylene group in the presence of a radical polymerization initiator capable of abstracting hydrogen, and the methylene group reacts with a hydroxyl group of a polarizer such as PVA to form a covalent bond. Therefore, in order to generate a radical in the methylene group of the radically polymerizable compound having an active methylene group and sufficiently form such a covalent bond, when the total amount of the curable component is 100% by mass, the radically polymerizable compound having an active methylene group is preferably contained in an amount of 1 to 50% by mass, more preferably 3 to 30% by mass. In order to sufficiently improve the water resistance and improve the adhesiveness in a non-dry state, the content of the radically polymerizable compound having an active methylene group is preferably 1% by mass or more. On the other hand, if it exceeds 50% by mass, the curing failure of the adhesive layer may occur. The radical polymerization initiator having a hydrogen abstraction action is preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.3 to 9% by mass, based on the total amount of the adhesive composition A or B. In order to allow the hydrogen abstraction reaction to proceed sufficiently, it is preferable to use 0.1% by mass or more of the radical polymerization initiator. On the other hand, if it exceeds 10% by mass, it may not dissolve completely in the composition.

Adhesive compositions A and B preferably further contain the following components as necessary.

The bubble suppressor is a compound that can lower the surface tension of the adhesive composition A and/or B when blended therein, and has the effect of reducing air bubbles between the laminated transparent protective film. Examples of the cell suppressor include silicone-based cell suppressors having a polysiloxane skeleton such as polydimethylsiloxane, (meth)acrylic cell suppressors having a (meth)acrylic skeleton obtained by polymerizing (meth)acrylic acid esters, etc., polyether-based cell suppressors obtained by polymerizing vinyl ethers, cyclic ethers, and the like, and fluorine-containing cell suppressors composed of a fluorine-based compound having a perfluoroalkyl group.

The foam suppressor preferably has a reactive group in the compound. In this case, the generation of lamination bubbles can be reduced when the polarizer and the transparent protective film are laminated. The reactive group possessed by the cell suppressor includes a polymerizable functional group, and specific examples thereof include a radically polymerizable functional group having an ethylenic double bond such as a (meth)acryloyl group, a vinyl group and an allyl group, an epoxy group such as a glycidyl group, a cationically polymerizable functional group such as an oxetane group, a vinyl ether group, a cyclic ether group, a cyclic thioether group and a lactone group. From the viewpoint of reactivity in the adhesive composition, a cell suppressor having a double bond as a reactive group is preferred, and a cell suppressor having a (meth)acryloyl group is more preferred.

In view of lamination bubble suppressing effect and adhesiveness improving effect, silicone-based cell suppressing agents are preferable among the above cell suppressing agents. Further, among the cell suppressing agents, those containing a urethane bond or an isocyanurate ring structure in the main chain skeleton or side chains are preferable in consideration of the adhesiveness of the adhesive layer. As the silicone-based foam inhibitor, commercially available products can also be suitably used, for example, "BYK-UV3505" (manufactured by BYK-Chemie Japan), which is an acryl group-modified polydimethylsiloxane.

In order to achieve both the adhesive strength of the resulting adhesive layer and the effect of reducing lamination air bubbles, the content of the bubble suppressor is preferably 0.01 to 0.6% by mass when the total amount of the adhesive composition A or B is 100% by mass.

The adhesive composition A and/or B can contain an acrylic oligomer obtained by polymerizing a (meth)acrylic monomer in addition to the curable component related to the radically polymerizable compound. By containing the acrylic oligomer in the adhesive composition, it is possible to reduce curing shrinkage when the composition is irradiated and cured with an active energy ray, and interfacial stress between the adhesive and an adherend such as a polarizer and a transparent protective film can be reduced. As a result, deterioration in adhesion between the adhesive layer and the adherend can be suppressed. In order to sufficiently suppress cure shrinkage of the adhesive layer, the content of the acrylic oligomer is preferably 20% by mass or less, more preferably 15% by mass or less, relative to the total amount of the adhesive composition A or B. If the content of the acrylic oligomer in the adhesive composition is too high, the reaction rate when the composition is irradiated with an active energy ray will decrease significantly, resulting in poor curing in some cases. On the other hand, the acrylic oligomer is preferably contained in an amount of 3% by mass or more, more preferably 5% by mass or more, relative to the total amount of the adhesive composition A or B.

Since the adhesive compositions A and B preferably have low viscosity in consideration of workability and uniformity during coating, the acrylic oligomer obtained by polymerizing the (meth)acrylic monomer also preferably has a low viscosity. The acrylic oligomer having a low viscosity and capable of preventing cure shrinkage of the adhesive layer preferably has a weight average molecular weight (Mw) of 15,000 or less, more preferably 10,000 or less, and particularly preferably 5,000 or less. On the other hand, in order to sufficiently suppress curing shrinkage of the adhesive layer, the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more, and particularly preferably 1500 or more. Specific examples of the (meth)acrylic monomer constituting the acrylic oligomer 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, S-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2- (meth)acrylic acid (C1-20) alkyl esters such as dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and N-octadecyl (meth)acrylate; (Meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)acrylate) methacrylate, etc.), alkoxy group- or phenoxy group-containing (meth)acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (e.g., 2,2,2-tri fluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc.), alkylaminoalkyl (meth)acrylates (e.g., dimethylaminoethyl (meth)acrylate, etc.), and the like. These (meth)acrylates can be used alone or in combination of two or more. Specific examples of acrylic oligomers include "ARUFON" manufactured by Toagosei Co., Ltd., "ACT FLOW" manufactured by Soken Chemical Co., Ltd., and "JONCRYL" manufactured by BASF Japan.

（ただし、Ｌ^＋は、任意のオニウムカチオンを表す。また、Ｘ^－は、ＰＦ_６ ^－、ＳｂＦ_６ ^－、ＡｓＦ_６ ^－、ＳｂＣｌ_６ ^－、ＢｉＣｌ_５ ^－、ＳｎＣｌ_６ ^－、ＣｌＯ_４ ^－、ジチオカルバメートアニオン、ＳＣＮ^－よりからなる群より選択されるカウンターアニオンを表す。） Adhesive composition A and/or B can contain a photoacid generator. When the adhesive composition contains a photoacid generator, the water resistance and durability of the adhesive layer can be dramatically improved as compared with the case where the adhesive composition does not contain a photoacid generator. The photoacid generator can be represented by the following general formula (5).
general formula (5)

(wherein L ⁺ represents an arbitrary onium cation, and X ⁻ represents a counter anion selected from the group consisting of PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , SbCl ₆ ⁻ , BiCl ₅ ⁻ , SnCl ₆ ⁻ , ClO ₄ ⁻ , dithiocarbamate anion, and SCN ⁻ ).

Next, the counter anion X ⁻ in general formula (5) will be explained.

The counter anion X 1 ⁻ in general formula (5) is not particularly limited in principle, but is preferably a non-nucleophilic anion. When the counter anion X ⁻ is a non-nucleophilic anion, nucleophilic reactions in cations coexisting in the molecule and various materials used in combination are less likely to occur, and as a result, it is possible to improve the temporal stability of the photoacid generator itself represented by the general formula (5) and the composition using it. A non-nucleophilic anion as used herein refers to an anion having a low ability to cause a nucleophilic reaction. Such anions include PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , SbCl ₆ ⁻ , BiCl ₅ ⁻ , SnCl ₆ ⁻ , ClO ₄ ⁻ , dithiocarbamate anions, SCN ⁻ and the like.

Specifically, "Cyracure UVI-6992", "Cyracure UVI-6974" (manufactured by Dow Chemical Japan Co., Ltd.), "ADEKA OPTOMER SP150", "ADEKA OPTOMER SP152", "ADEKA OPTOMER SP170", "ADEKA OPTOMER SP172" (manufactured by ADEKA Corporation), "IRGACURE250" (manufactured by Ciba Specialty Chemicals), "CI-5102", "CI-2855" (manufactured by Nippon Soda Co., Ltd.), "San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L", "San-Aid SI-110L", "San-Aid SI-180L" (manufactured by Sanshin Chemical Co., Ltd.), "CPI-100P", "CPI-100A" (manufactured by San-Apro Co., Ltd.) ), “WPI-069”, “WPI-113”, “WPI-116”, “WPI-041”, “WPI-044”, “WPI-054”, “WPI-055”, “WPAG-281”, “WPAG-567” and “WPAG-596” (manufactured by Wako Pure Chemical Industries, Ltd.) are preferred specific examples of the photoacid generator of the present invention.

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

The photobase generator is a compound capable of functioning as a catalyst for the polymerization reaction of a radically polymerizable compound or an epoxy resin and generating one or more kinds of basic substances by changing the molecular structure or by cleaving the molecule upon irradiation with light such as ultraviolet rays or visible light. Examples of basic substances include secondary amines and tertiary amines. Examples of the photobase generator include the α-aminoacetophenone compound, the oxime ester compound, and compounds having a substituent such as an acyloxyimino group, an N-formylated aromatic amino group, an N-acylated aromatic amino group, a nitrobenzylcarbamate group, and an alkoxybenzylcarbamate group. Among them, oxime ester compounds are preferred.

Examples of compounds having an acyloxyimino group include O,O'-diacetophenone oxime succinate, O,O'-dinaphthophenone oxime succinate, and benzophenone oxime acrylate-styrene copolymer.

Examples of compounds having an N-formylated aromatic amino group and an N-acylated aromatic amino group include di-N-(p-formylamino)diphenylmethane, di-N(p-aceethylamino)diphenylmelane, di-N-(p-benzamido)diphenylmethane, 4-formylaminotoluylene, 4-acetylaminotoluylene, 2,4-diformylaminotoluylene, 1-formylaminonaphthalene, 1-acetylaminonaphthalene, 1,5 -diformylaminonaphthalene, 1-formylaminoanthracene, 1,4-diformylaminoanthracene, 1-acetylaminoanthracene, 1,4-diformylaminoanthraquinone, 1,5-diformylaminoanthraquinone, 3,3'-dimethyl-4,4'-diformylaminobiphenyl, 4,4'-diformylaminobenzophenone.

Examples of compounds having a nitrobenzylcarbamate group and an alkoxybenzylcarbamate group include bis{{(2-nitrobenzyl)oxy}carbonyl}diaminodiphenylmethane, 2,4-di{(2-nitrobenzyl)oxy}toluylene, bis{(2-nitrobenzyloxy)carbonyl}hexane-1,6-diamine, and m-xylidine {{(2-nitro-4-chlorobenzyl)oxy}amide}.

The photobase generator is preferably at least one of an oxime ester compound and an α-aminoacetophenone compound, more preferably an oxime ester compound. As α-aminoacetophenone compounds, those having two or more nitrogen atoms are particularly preferred.

Other photobase generators include WPBG-018 (trade name: 9-anthrylmethyl N,N'-diethylcarbamate), WPBG-027 (trade name: (E)-1-[3-(2-hydroxyphenyl)-2-propenoyl]piperidine), and WPBG-082 (trade name: Photobase generators such as guanidinium 2-(3-benzoylphenyl)propionate) and WPBG-140 (trade name: 1-(anthraquinon-2-yl)ethyl imidazolecarboxylate) can also be used.

In the adhesive composition, a photoacid generator and a compound containing either an alkoxy group or an epoxy group can be used in combination.

When a compound having one or more epoxy groups in the molecule or a polymer (epoxy resin) having two or more epoxy groups in the molecule is used, a compound having two or more functional groups reactive with epoxy groups in the molecule may be used in combination. Examples of functional groups reactive with epoxy groups include carboxyl groups, phenolic hydroxyl groups, mercapto groups, and primary or secondary aromatic amino groups. Considering three-dimensional curability, it is particularly preferable to have two or more of these functional groups in one molecule.

Polymers having one or more epoxy groups in the molecule include, for example, epoxy resins, bisphenol A type epoxy resin derived from bisphenol A and epichlorohydrin, bisphenol F type epoxy resin derived from bisphenol F and epichlorohydrin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy resin, alicyclic epoxy resin, diphenyl ether type epoxy resin, hydroquinone type epoxy resin. resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins, fluorene-type epoxy resins, polyfunctional epoxy resins such as tri- or tetra-functional epoxy resins, glycidyl ester-type epoxy resins, glycidylamine-type epoxy resins, hydantoin-type epoxy resins, isocyanurate-type epoxy resins, aliphatic chain epoxy resins, etc. These epoxy resins may be halogenated or hydrogenated. Examples of commercially available epoxy resin products include JER Coat 828, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, and YX4000 manufactured by Japan Epoxy Resin Co., Ltd.; Epiclon 830, EXA835LV, HP4032D and HP820 manufactured by DIC Corporation; EP4100 series, EP4000 series, EPU series, Celoxide series (2021, 2021P, 2083, 2085, 3000, etc.) manufactured by Daicel Chemical Co., Ltd., Epolead series, EHPE series, YD series manufactured by Nippon Steel Chemical Co., Ltd., YDF series, YDCN series, YDB series, phenoxy resin (polyhydroxy polyether synthesized from bisphenols and epichlorohydrin with epoxy groups at both ends) YP series, etc.), Denacol series manufactured by Nagase ChemteX Corporation, and Epolite series manufactured by Kyoeisha Chemical Co., Ltd., but are not limited thereto. These epoxy resins may be used in combination of two or more.

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

The compounding amount of the compound containing either an alkoxy group or an epoxy group is usually 30% by mass or less with respect to the total amount of the adhesive composition A or B. If the content of the compound in the composition is too large, the adhesiveness may decrease and the impact resistance to the drop test may deteriorate. More preferably, the content of the compound in the composition is 20% by mass or less. On the other hand, from the viewpoint of water resistance, the content of the compound in the composition is preferably 2% by mass or more, more preferably 5% by mass or more.

When the adhesive compositions A and B are active energy ray-curable, the silane coupling agent is preferably an active energy ray-curable compound, but similar water resistance can be imparted even if it is not active energy ray-curable.

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

Preferred are 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane.

As a specific example of the silane coupling agent that is not curable with active energy rays, a silane coupling agent having an amino group is preferable. Specific examples of silane coupling agents having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiene. Toxysilane, γ-(2-aminoethyl)aminopropyltriisopropoxysilane, γ-(2-(2-aminoethyl)aminoethyl)aminopropyltrimethoxysilane, γ-(6-aminohexyl)aminopropyltrimethoxysilane, 3-(N-ethylamino)-2-methylpropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-benzyl-γ-vinylaminopropyltrimethoxysilane, N-benzyl-γ-aminopropyltrimethoxysilane Amino group-containing silanes such as benzyl-γ-aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl)aminomethyltrimethoxysilane, N,N'-bis[3-(trimethoxysilyl)propyl]ethylenediamine; Mention may be made of min-type silanes.

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

The amount of the silane coupling agent is preferably in the range of 0.01 to 20% by mass, preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, relative to the total amount of the adhesive composition A or B. This is because if the amount exceeds 20% by mass, the storage stability of the adhesive composition deteriorates, and if the amount is less than 0.1% by mass, the effect of water-resistant adhesion is not sufficiently exhibited.

Specific examples of non-active energy ray-curable silane coupling agents other than the above include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazolesilane.

When the adhesive composition A and/or B contains a compound having a vinyl ether group, it is preferable because the water-resistant adhesion between the polarizer and the adhesive layer is improved. Although the reason why such an effect is obtained is not clear, it is speculated that one of the reasons is that the vinyl ether group of the compound interacts with the polarizer to increase the adhesive strength between the polarizer and the adhesive layer. In order to further improve the water-resistant adhesion between the polarizer and the adhesive layer, the compound is preferably a radically polymerizable compound having a vinyl ether group. Moreover, the content of the compound is preferably 0.1 to 19% by mass with respect to the total amount of the adhesive composition A or B.

Adhesive compositions A and/or B can contain compounds that produce keto-enol tautomerism. For example, in an adhesive composition containing a cross-linking agent or an adhesive composition that can be used by blending a cross-linking agent, an aspect containing a compound that causes the above-mentioned keto-enol tautomerism can be preferably employed. As a result, excessive increase in viscosity and gelation of the adhesive composition after incorporation of the organometallic compound, as well as formation of microgels, can be suppressed, and the effect of extending the pot life of the composition can be realized.

Various β-dicarbonyl compounds can be used as the compound that causes keto-enol tautomerism. Specific examples include β-diketones such as acetylacetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2,4-dione, and 2,6-dimethylheptane-3,5-dione; propionyl acetate esters such as propyl and tert-butyl propionyl acetate; isobutyryl acetate esters such as ethyl isobutyryl acetate, ethyl isobutyryl acetate, isopropyl isobutyryl acetate and tert-butyl isobutyryl acetate; malonic acid esters such as methyl malonate and ethyl malonate; Among the preferred compounds are acetylacetone and acetoacetates. Compounds that cause such keto-enol tautomerism may be used alone or in combination of two or more.

The amount of the compound that causes keto-enol tautomerism is, for example, 0.05 to 10 parts by mass, preferably 0.2 to 3 parts by mass (eg, 0.3 to 2 parts by mass) per 1 part by mass of the organometallic compound. If the amount of the compound used is less than 0.05 parts by mass with respect to 1 part by mass of the organometallic compound, it may be difficult to exhibit sufficient effects. On the other hand, if the amount of the compound used exceeds 10 parts by mass with respect to 1 part by mass of the organometallic compound, it may excessively interact with the organometallic compound, making it difficult to achieve the intended water resistance.

The adhesive composition A and/or B may contain polyrotaxane. The polyrotaxane has a cyclic molecule, a linear molecule penetrating through an opening of the cyclic molecule, and blocking groups arranged at both ends of the linear molecule so that the cyclic molecule does not detach from the linear molecule. The cyclic molecule preferably has an active energy ray-curable functional group.

The cyclic molecule is not particularly limited as long as it is a molecule in which a straight-chain molecule is skewered in its opening, is movable on the straight-chain molecule, and has an active energy ray-polymerizable group. In the present specification, "cyclic" in "cyclic molecule" means substantially "cyclic". That is, a cyclic molecule does not have to be completely closed so long as it can move on the linear molecule.

Preferred examples of cyclic molecules include cyclic polymers such as cyclic polyethers, cyclic polyesters, cyclic polyetheramines and cyclic polyamines, and cyclodextrins such as α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin. Among them, cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are preferred because they are relatively easily available and many types of blocking groups can be selected. Two or more cyclic molecules may be mixed in the polyrotaxane or adhesive.

In the polyrotaxane used in the present invention, the cyclic molecule has an active energy ray-polymerizable group. As a result, the polyrotaxane reacts with the active energy ray-curable component to obtain an adhesive in which the cross-linking points are movable even after curing. The active energy ray-polymerizable group possessed by the cyclic molecule may be any group capable of polymerizing with the active energy ray-curable compound, and examples thereof include radically polymerizable groups such as (meth)acryloyl groups and (meth)acryloyloxy groups.

When cyclodextrin is used as the cyclic molecule, the active energy ray-polymerizable group is preferably introduced to the hydroxyl group of cyclodextrin via any suitable linker. The number of active energy ray-polymerizable groups in one molecule of the polyrotaxane is preferably 2 to 1,280, more preferably 50 to 1,000, still more preferably 90 to 900.

A hydrophobic modification group is preferably introduced into the cyclic molecule. By introducing a hydrophobic modifying group, the compatibility with the active energy ray-curable component can be improved. In addition, since it is imparted with hydrophobicity, when it is used in a polarizing film, it is possible to prevent water from entering the interface between the adhesive layer and the polarizer, thereby further improving the water resistance. Hydrophobic modifying groups include polyester chains, polyamide chains, alkyl chains, oxyalkylene chains, ether chains, and the like. Specific examples include groups described in [0027] to [0042] of WO2009/145073.

A polarizing film using an adhesive composition containing polyrotaxane as an adhesive has excellent water resistance. Although the reason why the water resistance of the polarizing film is improved is not clear, it is presumed as follows. That is, it is thought that the mobility of the cyclic molecules of the polyrotaxane allows the cross-linking points to move (so-called pulley effect), which imparts flexibility to the cured adhesive and increases the adhesion to the uneven surface of the polarizer. Furthermore, it is considered that the fact that the polyrotaxane has a hydrophobic modification group to impart hydrophobicity to the adhesive also contributed to the prevention of water from entering the interface between the polarizer and the adhesive layer. The content of the polyrotaxane in the adhesive composition A or B is preferably 2% by mass to 50% by mass.

In the present invention, a cationic polymerizable adhesive composition may be used for forming the adhesive layer. The cationically polymerizable compounds used in the cationically polymerizable adhesive composition are classified into monofunctional cationically polymerizable compounds having one cationically polymerizable functional group in the molecule and polyfunctional cationically polymerizable compounds having two or more cationically polymerizable functional groups in the molecule. Since the monofunctional cationically polymerizable compound has a relatively low liquid viscosity, the liquid viscosity of the adhesive composition can be lowered by including it in the adhesive composition. In addition, the monofunctional cationically polymerizable compound often has a functional group that exhibits various functions, and by including it in the adhesive composition, the adhesive composition and / or the cured product of the adhesive composition can exhibit various functions. The polyfunctional cationically polymerizable compound is preferably contained in the adhesive composition because it can three-dimensionally crosslink the cured product of the adhesive composition. The ratio of the monofunctional cationically polymerizable compound to the polyfunctional cationically polymerizable compound is preferably in the range of 10 parts by mass to 1000 parts by mass of the polyfunctional cationically polymerizable compound with respect to 100 parts by mass of the monofunctional cationically polymerizable compound. Examples of cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Compounds having an epoxy group include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. The cationically polymerizable adhesive composition of the present invention is particularly preferred to contain an alicyclic epoxy compound because of its excellent curability and adhesiveness. The alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, caprolactone-modified products, trimethylcaprolactone-modified products, and valerolactone-modified products of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate. Side 2083, Celoxide 2085 (manufactured by Daicel Chemical Industries, Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, R-6110 (manufactured by Dow Chemical Japan) and the like. A compound having an oxetanyl group has the effect of improving the curability of the cationic polymerizable adhesive composition of the present invention and lowering the liquid viscosity of the composition, and is therefore preferably contained. Compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetanyl)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, phenol novolac oxetane and the like. Tan OXT-101, Aron oxetane OXT-121, Aron oxetane OXT-211, Aron oxetane OXT-221, Aron oxetane OXT-212 (manufactured by Toagosei Co., Ltd.) and the like are commercially available. A compound having a vinyl ether group has the effect of improving the curability of the cationic polymerizable adhesive composition of the present invention and lowering the liquid viscosity of the composition, and is therefore preferably contained. Examples of compounds having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol vinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, and pentaerythritol type tetravinyl ether.

The cationic polymerizable adhesive composition contains, as a curable component, at least one compound selected from the compounds having an epoxy group, the compound having an oxetanyl group, and the compound having a vinyl ether group as described above, and since these are all cured by cationic polymerization, a cationic photopolymerization initiator is added. This cationic photopolymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays and electron beams, and initiates the polymerization reaction of epoxy groups and oxetanyl groups. A photoacid generator and a photobase generator can be used as the photocationic polymerization initiator, and the photoacid generator described later is preferably used. Further, when the adhesive composition used in the present invention is used for curing with visible light, it is preferable to use a cationic photopolymerization initiator that is particularly sensitive to light of 380 nm or more, but the photocationic polymerization initiator is generally a compound that exhibits maximum absorption in a wavelength region near or shorter than 300 nm. Cationic species or acid generation from the agent can be facilitated. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducible dyes, etc. These may be used in combination of two or more. Anthracene compounds are particularly preferable because of their excellent photosensitizing effect, and specific examples thereof include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Kasei Co., Ltd.). The content of the photosensitizer is preferably 0.1% by mass to 5% by mass, more preferably 0.5% by mass to 3% by mass.

<Polarizer>
In the present invention, from the viewpoint of improving optical durability in a harsh environment under high temperature and high humidity, it is preferable to use a thin polarizer having a thickness of 3 μm or more and 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, and particularly preferably 8 μm or less. Such a thin polarizer has little unevenness in thickness, excellent visibility, and little dimensional change, so it is excellent in durability against thermal shock.

A polarizer using a polyvinyl alcohol-based resin is used. Examples of polarizers include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene/vinyl acetate copolymer films, which are uniaxially stretched after adsorbing dichroic substances such as iodine and dichroic dyes, and oriented polyene films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Among these, a polarizer composed of a polyvinyl alcohol-based film and a dichroic substance such as iodine is suitable.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or it may be immersed in an aqueous solution of potassium iodide or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, dirt and anti-blocking agents on the surface of the polyvinyl alcohol film can be washed away, and by swelling the polyvinyl alcohol film, non-uniformity such as uneven dyeing can be prevented. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

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

As a thin polarizer, typically,
Patent No. 4751486,
Patent No. 4751481 specification,
Patent No. 4815544 specification,
Patent No. 5048120,
WO 2014/077599 pamphlet,
International Publication No. 2014/077636,
and the like, or thin polarizers obtained from the production methods described therein.

The thin polarizer is preferably obtained by a method including a step of drawing in an aqueous boric acid solution as described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, and Japanese Patent No. 4815544, especially Japanese Patent No. 4751481 and Japanese Patent No. 4815544, in that the thin polarizer can be stretched at a high magnification and can improve the polarizing performance. It is preferably obtained by a process described in the specification including a step of auxiliary stretching in the air before stretching in an aqueous boric acid solution. These thin polarizers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a stretching resin base material in the state of a laminate, and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the stretching resin substrate.

<Transparent protective film>
As the transparent protective film, a film having excellent transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. is preferable. Examples include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. Polyolefin polymers such as polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, ethylene/propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamides, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or the above polymers. Blends and the like are also examples of polymers that form the transparent protective film. One or more of any suitable additives may be contained in the transparent protective film. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the thermoplastic resin in the transparent protective film is preferably 50-100% by mass, more preferably 50-99% by mass, still more preferably 60-98% by mass, and particularly preferably 70-97% by mass. If the content of the thermoplastic resin in the transparent protective film is 50% by mass or less, there is a possibility that the high transparency inherent in the thermoplastic resin cannot be sufficiently exhibited.

Examples of transparent protective films include polymer films described in JP-A-2001-343529 (WO01/37007), such as (A) a thermoplastic resin having a substituted and/or unsubstituted imide group in a side chain, and a resin composition containing a thermoplastic resin having a substituted and/or unsubstituted phenyl and nitrile group in a side chain. A specific example is a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. A film made of a mixed extruded product of a resin composition or the like can be used as the film. Since these films have a small retardation and a small photoelastic coefficient, problems such as unevenness due to distortion of the polarizing film can be eliminated.

Moreover, it is preferable that the transparent protective film used in the present invention has a moisture permeability of 150 g/m ² /24 h or less. According to such a configuration, it is difficult for moisture in the air to enter the polarizing film, and a change in the moisture content of the polarizing film itself can be suppressed. As a result, curling and dimensional changes of the polarizing film caused by the storage environment can be suppressed.

As the transparent protective film provided on one or both sides of the polarizer, those having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. are preferable, and those having a moisture permeability of 150 g/m ² /24h or less are more preferable, those of 120 g/m ² /24h or less are particularly preferable, and those of 5 to 70 g/m ² /24h or less are even more preferable.

Materials for forming the transparent protective film that satisfies the low moisture permeability include, for example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; arylate-based resins; amide-based resins such as nylon and aromatic polyamide; Among these resins, polycarbonate-based resins, cyclic polyolefin-based resins, and (meth)acrylic-based resins are preferred, and cyclic polyolefin-based resins and (meth)acrylic-based resins are particularly preferred.

The thickness of the transparent protective film can be determined as appropriate, but is generally preferably 5 to 100 μm from the viewpoints of strength, workability such as handleability, and thinness. 10 to 60 μm is particularly preferable, and 13 to 40 μm is more preferable.

As the transparent protective film, a film having a front retardation of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re=(nx−ny)×d. The thickness direction retardation Rth is represented by Rth=(nx−nz)×d. Also, the Nz coefficient is represented by Nz=(nx−nz)/(nx−ny). [However, nx, ny, and nz are the refractive indices in the slow axis direction, the fast axis direction, and the thickness direction of the film, and d (nm) is the thickness of the film. The slow axis direction is the direction in which the in-plane refractive index of the film is maximized. ]. In addition, it is preferable that the transparent protective film has as little coloring as possible. A protective film having a retardation value in the thickness direction of −90 nm to +75 nm is preferably used. By using a film having a retardation value (Rth) in the thickness direction of −90 nm to +75 nm, coloring (optical coloring) of the polarizing film caused by the transparent protective film can be substantially eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, particularly −70 nm to +45 nm.

On the other hand, as the transparent protective film, a retardation plate having a front retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. The front retardation is usually controlled in the range of 40-200 nm, and the thickness direction retardation is usually controlled in the range of 80-300 nm. When a retardation plate is used as the transparent protective film, the retardation plate also functions as a transparent protective film, so that the thickness can be reduced.

Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, and a film in which an oriented layer of a liquid crystal polymer is supported. Although the thickness of the retardation plate is not particularly limited, it is generally about 20 to 150 μm. Polymer materials include, for example, polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary or ternary systems. Examples include polymers, graft copolymers, and blends. These polymer materials become oriented products (stretched films) by stretching or the like.

Examples of the liquid crystal polymer include various types of main chain type and side chain type in which a conjugated linear atomic group (mesogen) that imparts liquid crystal orientation is introduced into the main chain or side chain of the polymer. Specific examples of the main chain type liquid crystal polymer include, for example, nematic orientation polyester-based liquid crystal polymer, discotic polymer, and cholesteric polymer having a structure in which mesogenic groups are bonded by a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include those having a main chain skeleton of polysiloxane, polyacrylate, polymethacrylate or polymalonate, and having a mesogenic portion composed of a para-substituted cyclic compound unit imparting nematic alignment via a spacer portion composed of a conjugated atomic group as a side chain. These liquid crystalline polymers are formed, for example, by spreading a liquid crystalline polymer solution on the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate and subjecting the surface to rubbing treatment, or obliquely vapor-depositing silicon oxide, followed by heat treatment.

The retardation plate may have an appropriate retardation according to the purpose of use, such as for the purpose of compensating for coloring and viewing angle due to birefringence of various wavelength plates and liquid crystal layers, and may be one in which optical characteristics such as retardation are controlled by laminating two or more retardation plates.

The retardation plate satisfying the relationships nx=ny>nz, nx>ny>nz, nx>ny=nz, nx>nz>ny, nz=nx>ny, nz>nx>ny, and nz>nx=ny is selected and used according to various applications. Note that ny=nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

For example, a retardation plate that satisfies nx>ny>nz preferably has a front retardation of 40 to 100 nm, a thickness direction retardation of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5. For example, a retardation plate (positive A plate) satisfying nx>ny=nz preferably has a front retardation of 100 to 200 nm. For example, a retardation plate (negative A plate) satisfying nz=nx>ny preferably has a front retardation of 100 to 200 nm. For example, a retardation plate satisfying nx>nz>ny preferably has a front retardation of 150 to 300 nm and an Nz coefficient of more than 0 to 0.7. Also, as described above, for example, one that satisfies nx=ny>nz, nz>nx>ny, or nz>nx=ny can be used.

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

For example, in the case of IPS (In-Plane Switching, including FFS), the transparent protective film on one side of the polarizing film may or may not have retardation. For example, when there is no phase difference, it is desirable that both the upper and lower sides of the liquid crystal cell (on the cell side) have no phase difference. If the liquid crystal cell has a retardation, it is preferable that one of the upper and lower liquid crystal cells has a retardation (for example, a biaxial film that satisfies the relationship nx>nz>ny on the upper side, no retardation on the lower side, or a positive A plate on the upper side and a positive C plate on the lower side). When it has a phase difference, it is desirable that Re=-500 to 500 nm and Rth=-500 to 500 nm. In terms of three-dimensional refractive index, nx>ny=nz, nx>nz>ny, nz>nx=ny, nz>nx>ny (positive A plate, biaxial, positive C plate) are desirable.

In order to supplement the mechanical strength and handleability of the transparent protective film, a peelable substrate may be further laminated. The peelable substrate can be peeled off from the laminate including the transparent protective film and the polarizer before or after bonding the transparent protective film and the polarizer together, during the process, or in a separate process.

<Method for producing polarizing film>
Each step in the method for producing a polarizing film according to the present invention will be described below with reference to FIG.

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

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

The polarizer 2 and the transparent protective film 3 may be subjected to surface modification treatment before the coating process. In particular, it is preferable to subject the surface of the polarizer 2 to a surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment and flame treatment, with corona treatment being particularly preferred. By performing the corona treatment, reactive functional groups such as carbonyl groups and amino groups are generated on the surface of the polarizer 2, and adhesion to the adhesive layer is improved. In addition, foreign matter on the surface is removed by the ashing effect, and unevenness on the surface is reduced, so that a polarizing film with excellent appearance characteristics can be produced.

Coating machines 4 and 5 are not particularly limited, and examples thereof include reverse coaters, gravure coaters (direct, reverse, and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, and rod coaters.

The method of applying the adhesive composition A to the bonding surface of the polarizer 2 and the method of applying the adhesive composition B to the bonding surface of the transparent protective film 3 are appropriately selected depending on the viscosity of each adhesive composition and the desired thickness, but from the viewpoint of removing foreign substances on the surfaces of the polarizer 2 and the transparent protective film 3, coating properties, and controlling the thickness of the coating film, it is preferable to use a post-metering coating method. Specific examples of the post-metering coating method include gravure roll coating, forward roll coating, air knife coating, and rod/bar coating. Among these, the gravure roll coating method is particularly preferable from the viewpoint of removal of foreign matters on the surfaces of the polarizer 2 and the transparent protective film 3, coatability, and thickness control of the coating film.

In the gravure roll coating method, various patterns can be formed on the surface of the gravure roll, such as a honeycomb mesh pattern, a trapezoidal pattern, a grid pattern, a pyramid pattern, or a diagonal line pattern. In order to effectively prevent appearance defects of the finally obtained polarizing film, the pattern formed on the surface of the gravure roll is preferably a honeycomb mesh pattern. In the case of a honeycomb mesh pattern, the cell volume is preferably 1 to 5 cm ³ /m ² , more preferably 2 to 3 cm ³ /m ² , in order to improve the surface precision of the coated surface after coating. Similarly, the number of cell lines per inch of the roll is preferably 200 to 3000 lines/inch in order to improve the surface precision of the coated surface after coating. Further, the rotation speed ratio of the gravure roll to the traveling speed of the polarizer 2 and the transparent protective film 3 is preferably 100 to 300%.

Each thickness of the first coating film and the second coating film is adjusted by adjusting the coating amount of each adhesive composition based on the content of the polymerizable compound X contained in the adhesive compositions A and B. Specifically, based on the content of the polymerizable compound X contained in the adhesive compositions A and B, the content of the polymerizable compound X in the uncured adhesive layer obtained by bonding the first coating and the second coating is 40 to 64% by mass, preferably 50 to 62% by mass, more preferably 53 to 61% by mass.

In addition, based on the content of the polymerization initiator contained in the adhesive composition A and / or B, the content of the polymerization initiator in the uncured adhesive layer obtained by laminating the first coating and the second coating is 2.3 to 7% by mass, preferably 2.4 to 5% by mass, more preferably 2.6 to 4% by mass.

<Thickness measurement process>
The thickness measurement step is a step of in-line measuring the thickness of the first coating film and the second coating film. The film thickness meters 6 and 7 used for in-line measurement are preferably optical (non-contact) film thickness meters. The optical (non-contact) film thickness gauge is not particularly limited, and examples thereof include a spectroscopic interference film thickness meter, a spectroscopic reflection film thickness meter, and a confocal film thickness meter. In particular, a spectroscopic interference film thickness meter capable of measuring the thickness of the coating film over the entire width is preferred.

<Coating amount adjustment process>
In the coating amount adjusting step, based on the thicknesses of the first coating film and the second coating film obtained by the in-line measurement, the content of the polymerizable compound X in the uncured adhesive layer obtained by bonding the first coating film and the second coating film is 40 to 64% by mass, preferably 50 to 62% by mass, more preferably 53 to 61% by mass. This is the step of adjusting the coating amount of the adhesive composition B.

In the coating amount adjusting step, based on the thicknesses of the first coating film and the second coating film obtained by the in-line measurement, the content of the polymerization initiator in the uncured adhesive layer obtained by bonding the first coating film and the second coating film is 2.3 to 7% by mass, preferably 2.4 to 5% by mass, more preferably 2.6 to 4% by mass. The step of adjusting the coating amount of the agent composition B is preferred.

As a method for adjusting the coating amount, for example, when the ratio of the thickness of the first coating to the thickness of the second coating (thickness ratio) is outside the predetermined range initially set in the first coating step and the second coating step, the coating amount of the adhesive composition A in the first coating step and / or the coating amount of the adhesive composition B in the second coating step is appropriately adjusted so that the ratio of the thickness of the first coating to the thickness of the second coating (thickness ratio) is within the predetermined range initially set. A method of adjusting so as to be Specifically, the thickness ratio is preferably adjusted to be within ±10% of the initially set thickness ratio, more preferably within ±5%, still more preferably within ±3%, and particularly preferably within ±1%.

<Lamination process>
The bonding step is a step of bonding the bonding surface of the polarizer 2 on which the first coating film is formed and the bonding surface of the transparent protective film 3 on which the second coating film is formed to form an uncured adhesive layer. The lamination can be performed by a roll laminator 8 or the like.

<Adhesion process>
The bonding step is a step of bonding the polarizer 2 and the transparent protective film 3 through an adhesive layer obtained by curing an uncured adhesive layer to produce the polarizing film 1 .

After bonding the polarizer 2 and the transparent protective film 3 together, an active energy ray (electron beam, ultraviolet light, visible light, etc.) is irradiated to cure the uncured adhesive layer to form an adhesive layer. The irradiation direction of the active energy rays (electron beam, ultraviolet rays, visible rays, etc.) can be any suitable direction. Preferably, the light is irradiated from the transparent protective film 3 side. When irradiated from the polarizer 2 side, the polarizer 2 may be deteriorated by active energy rays (electron beam, ultraviolet rays, visible light, etc.).

Any appropriate irradiation conditions can be adopted as long as the conditions are such that the uncured adhesive layer can be cured when the electron beam is irradiated. For example, the acceleration voltage in electron beam irradiation is preferably 5 kV to 300 kV, more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the uncured adhesive layer and may result in insufficient curing. The irradiation dose is preferably 5-100 kGy, more preferably 10-75 kGy. If the irradiation dose is less than 5 kGy, the uncured adhesive layer will be insufficiently cured, and if it exceeds 100 kGy, the transparent protective film and polarizer will be damaged, the mechanical strength will be reduced and yellowing will occur, and the desired optical properties will tend to be unobtainable.

The electron beam irradiation is usually carried out in an inert gas, but if necessary, it may be carried out in the atmosphere or under the condition that a little oxygen is introduced. Although it depends on the material of the transparent protective film, by appropriately introducing oxygen, the surface of the transparent protective film that is first exposed to the electron beam is intentionally inhibited by oxygen, and damage to the transparent protective film can be prevented, and only the uncured adhesive layer can be efficiently irradiated with the electron beam.

In the method for producing a polarizing film according to the present invention, as the active energy ray, one containing visible light in the wavelength range of 380 nm to 450 nm, particularly the active energy ray with the highest irradiation amount of visible light in the wavelength range of 380 nm to 450 nm It is preferable to use. In the case of using ultraviolet rays and visible rays, when using a transparent protective film imparted with ultraviolet absorption ability (ultraviolet-impermeable transparent protective film), light having a wavelength shorter than about 380 nm is absorbed. Furthermore, light with a wavelength shorter than 380 nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, causing defects such as curling and wrinkling of the polarizing film. Therefore, when ultraviolet light or visible light is employed in the present invention, it is preferable to use a device that does not emit light with a wavelength shorter than 380 nm as the active energy ray generator. More specifically, the ratio of the integrated illuminance in the wavelength range of 380 to 440 nm to the integrated illuminance in the wavelength range of 250 to 370 nm is preferably 100:0 to 100:50, more preferably 100:0 to 100:40. In the method for producing a polarizing film according to the present invention, a gallium-encapsulated metal halide lamp and an LED light source emitting light in a wavelength range of 380 to 440 nm are preferable as active energy rays. Alternatively, a low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, incandescent lamp, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excimer laser, or a light source containing ultraviolet rays and visible rays such as sunlight can be used, and ultraviolet rays with a wavelength shorter than 380 nm can be blocked using a bandpass filter. In order to prevent curling of the polarizing film while improving the adhesion performance of the adhesive layer between the polarizer and the transparent protective film, it is preferable to use an active energy ray obtained through a band-pass filter capable of blocking light with a wavelength shorter than 380 nm using a gallium-filled metal halide lamp, or an active energy ray having a wavelength of 405 nm obtained using an LED light source.

It is preferable to heat the uncured adhesive layer before irradiation with ultraviolet light or visible light (pre-irradiation heating), in which case the temperature is preferably 40°C or higher, more preferably 50°C or higher. It is also preferable to heat the adhesive layer after irradiation with ultraviolet light or visible light (post-irradiation heating). In this case, the temperature is preferably 40°C or higher, more preferably 50°C or higher.

The adhesive compositions A and B used in the present invention are particularly suitable for forming an adhesive layer for bonding a polarizer and a transparent protective film having a light transmittance of less than 5% at a wavelength of 365 nm. Here, the adhesive compositions A and B used in the present invention contain the photopolymerization initiator of general formula (3) described above, so that the adhesive layer can be cured by irradiating ultraviolet rays through a transparent protective film having UV absorption ability. Therefore, the adhesive layer can be cured even in a polarizing film in which transparent protective films having UV absorption ability are laminated on both sides of a polarizer. However, of course, the adhesive layer can be cured even in a polarizing film laminated with a transparent protective film having no UV absorption ability. The transparent protective film having UV absorbability means a transparent protective film having a transmittance of less than 10% for light of 380 nm.

Examples of the method for imparting UV absorption ability to the transparent protective film include a method of incorporating an ultraviolet absorber into the transparent protective film and a method of laminating a surface treatment layer containing an ultraviolet absorber on the surface of the transparent protective film.

Specific examples of UV absorbers include conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like.

In the method for producing a polarizing film according to the present invention, the line speed is preferably 1 to 500 m/min, more preferably 5 to 300 m/min, even more preferably 10 to 100 m/min, depending on the curing time of the uncured adhesive layer. If the line speed is too low, the productivity is poor, or the damage to the transparent protective film is too great, and a polarizing film that can withstand a durability test or the like cannot be produced. If the line speed is too high, the curing of the uncured adhesive layer may be insufficient, and the intended adhesiveness may not be obtained.

<Adhesive layer>
The adhesive layer is formed by curing an uncured adhesive layer. The thickness of the adhesive layer is preferably 0.01 to 3.0 μm. If the thickness of the adhesive layer is too thin, the cohesive force of the adhesive layer will be insufficient and the peeling force will decrease, which is not preferable. If the thickness of the adhesive layer is too thick, the polarizing film is likely to be peeled off when stress is applied to the cross section of the polarizing film, which is not preferable because the peeling failure occurs due to impact. The thickness of the adhesive layer is more preferably 0.1 to 2.5 μm, still more preferably 0.5 to 1.5 μm.

<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, a retardation film (including a wave plate such as 1/2 or 1/4), a visual compensation film, a brightness enhancement film, a reflective plate or a translucent plate, such as a liquid crystal display device.

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

Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, and a film in which an oriented layer of a liquid crystal polymer is supported. Although the thickness of the retardation film is not particularly limited, it is generally about 20 to 150 μm.

As the retardation film, the following formulas (1) to (3):
0.70<Re[450]/Re[550]<0.97 (1)
1.5×10−3<Δn<6×10−3 (2)
1.13<NZ<1.50 (3)
(Wherein, Re [450] and Re [550] are the in-plane retardation values of the retardation film measured with light having wavelengths of 450 nm and 550 nm at 23° C., respectively, Δn is the in-plane birefringence that is nx−ny when the refractive indices in the slow axis direction and the fast axis direction of the retardation film are nx and ny, respectively, and NZ is the thickness direction birefringence when nz is the refractive index in the thickness direction of the retardation film. A reverse wavelength dispersion type retardation film that satisfies the ratio of nx-nz to in-plane birefringence nx-ny may be used.

The polarizing film and the optical film having at least one layer of polarizing film laminated thereon may be provided with an adhesive layer for adhering to other members such as a liquid crystal cell. The adhesive that forms the adhesive layer is not particularly limited, but for example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer can be appropriately selected and used. In particular, adhesives such as acrylic pressure-sensitive adhesives which are excellent in optical transparency, exhibit appropriate wettability, cohesiveness and adhesive properties, and are excellent in weather resistance and heat resistance can be preferably used.

The adhesive layer can also be provided on one side or both sides of the polarizing film or the optical film as a superimposed layer of different compositions or types. Further, when the adhesive layer is provided on both sides, the front and back surfaces of the polarizing film or the optical film may have adhesive layers with different compositions, types, thicknesses, and the like. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 1 to 200 μm, particularly preferably 1 to 100 μm.

The exposed surface of the adhesive layer is temporarily covered by a separator for the purpose of preventing contamination, etc., until the adhesive layer is put into practical use. This prevents contact with the adhesive layer during normal handling conditions. As the separator, excluding the thickness conditions described above, for example, an appropriate thin sheet such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, or a laminate thereof may be coated with an appropriate release agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide.

<Image display device>
The polarizing film or optical film of the present invention can be preferably used for forming various devices such as liquid crystal display devices. Formation of the liquid crystal display device can be carried out according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or an optical film, and an illumination system as necessary, and incorporating a drive circuit. As for the liquid crystal cell, any type such as TN type, STN type, or π type can be used.

Appropriate liquid crystal display devices such as a liquid crystal display device having a polarizing film or an optical film arranged on one side or both sides of a liquid crystal cell, or a device using a backlight or a reflector for an illumination system can be formed. In that case, the polarizing film or optical film according to the present invention can be placed on one side or both sides of the liquid crystal cell. When polarizing films or optical films are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, appropriate parts such as a diffuser plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffuser plate, and a backlight can be arranged at appropriate positions in one or more layers.

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

<Polarizer>
First, a laminate in which a PVA layer having a thickness of 9 μm was formed on an amorphous PET substrate was subjected to auxiliary stretching in the air at a stretching temperature of 130° C. to prepare a stretched laminate. Next, the stretched laminate was dyed to prepare a colored laminate. An optical film laminate including a PVA layer having a thickness of 5 μm, which constitutes a thin polarizer in which the PVA molecules of the PVA layer formed on the amorphous PET base material by such two-stage stretching are highly oriented and the iodine adsorbed by the dyeing is highly oriented in one direction as a polyiodine ion complex, was obtained. The thin polarizer (PVA layer) had a moisture content of 10% by mass.

<Transparent protective film>
A 25 μm-thick triacetyl cellulose film (manufactured by Konica Minolta: KC2UA) was used as the transparent protective film.

<Active energy ray>
As active energy rays, visible light (gallium-encapsulated metal halide lamp) Irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc. Bulb: V-bulb Peak illuminance: 1600 mW/cm ² , Integrated irradiation amount 1000/mJ/cm 2 (wavelength 380 to 440 nm) was used. The illuminance of visible light was measured using a Sola-Check system manufactured by Solatell.

<Preparation of Adhesive Composition A>
An adhesive composition A was prepared by mixing 90 parts by mass of acryloylmorpholine (manufactured by Kojin Co., Ltd., trade name "ACMO", SP value: 22.9), 1 part by mass of 3-acrylamidophenylboronic acid (manufactured by Junsei Chemical Co., Ltd.), and 9 parts by mass of hydroxyethylacrylamide (manufactured by Kojin Co., Ltd., trade name "HEAA") and stirring at 25 ° C. for 30 minutes.

<Preparation of Adhesive Composition B>
45 parts by mass of acryloylmorpholine (manufactured by Kojin Co., Ltd., trade name "ACMO", SP value: 22.9), 41 parts by mass of 1,9-nonanediol diacrylate (trade name "Light Acrylate 1.9ND-A", manufactured by Kyoeisha Chemical Co., Ltd.), 10 parts by mass of an acrylic oligomer obtained by polymerizing (meth)acrylic monomer (trade name "ARUFON UG4010", manufactured by Toagosei Co., Ltd.), and diethylthioxane as a photopolymerization initiator. Ton (compound described in general formula (3), trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) 1.5 parts by mass, and 2-methyl-1-(4-methylthiophenyl) -2-morpholinopropan-1-one (compound described in general formula (4), trade name "IRGACURE907", manufactured by BASF) 2.5 parts by mass are mixed and stirred at 50 ° C. for 1 hour. , Adhesive Composition B was prepared.

Example 1
On a continuous line, using a gravure roll coating method equipped with a gravure roll, the prepared adhesive composition A was applied to the PVA surface of the prepared optical film laminate containing the PVA layer with a thickness of 5 μm to an initial setting thickness of 760 nm to continuously form a first coating film.
On the other hand, on another continuous line, using a gravure roll coating method equipped with a gravure roll, the prepared adhesive composition B was applied to the bonding surface of the transparent protective film with an initial setting thickness of 1500 nm to continuously form a second coating film. The ratio of the thickness of the first coating film to the thickness of the second coating film (thickness ratio) was initially set to 0.507 (760 nm/1500 nm).
Then, on a continuous line, the thicknesses of the first coating film and the second coating film are measured in-line with a spectral interference film thickness meter (manufactured by Ocean Optics: Spectrometer “USB2000+”, light source “HL-2000”, fiber “OCF-103995”), and the ratio (thickness ratio) of the thickness of the first coating film to the thickness of the second coating film obtained by in-line measurement is within ±1% of the initially set thickness ratio (0.507). , the coating amount of the adhesive composition A in the first coating step and the coating amount of the adhesive composition B in the second coating step were appropriately adjusted.
Next, using a roll machine, the bonding surface on which the first coating film of the optical film laminate was formed and the bonding surface on which the second coating film of the transparent protective film was formed were bonded together to form an uncured adhesive layer. After that, from the side of the laminated transparent protective film, the visible light was irradiated using an active energy ray irradiation device to adhere the polarizer and the transparent protective film via an adhesive layer, followed by hot air drying at 70° C. for 3 minutes, and the amorphous PET base material was peeled off to obtain a polarizing film having a transparent protective film on one side of the polarizer. The lamination line speed was 25 m/min. A polarizing film was continuously manufactured for 15 hours through the series of steps.

Example 2
On a continuous line, using a gravure roll coating system equipped with a gravure roll, the prepared adhesive composition A was applied to the PVA surface of the prepared optical film laminate containing a PVA layer with a thickness of 5 μm to an initial setting thickness of 610 nm to continuously form a first coating film.
On the other hand, on another continuous line, using a gravure roll coating method equipped with a gravure roll, the prepared adhesive composition B was applied to the bonding surface of the transparent protective film with an initial setting thickness of 1510 nm to continuously form a second coating film. The ratio of the thickness of the first coating film to the thickness of the second coating film (thickness ratio) was initially set to 0.404 (610 nm/1510 nm).
Then, on a continuous line, the thicknesses of the first coating film and the second coating film are measured in-line with a spectral interferometry film thickness meter (manufactured by Ocean Optics: spectrometer “USB2000+”, light source “HL-2000”, fiber “OCF-103995”), and the ratio (thickness ratio) of the thickness of the first coating film to the thickness of the second coating film obtained by in-line measurement is within ±1% of the initially set thickness ratio (0.404). , the coating amount of the adhesive composition A in the first coating step and the coating amount of the adhesive composition B in the second coating step were appropriately adjusted.
Thereafter, a polarizing film was obtained in the same manner as in Example 1. A polarizing film was continuously manufactured for 15 hours through the series of steps.

Example 3
On a continuous line, using a gravure roll coating method equipped with a gravure roll, the prepared adhesive composition A was applied to the PVA surface of the prepared optical film laminate containing a PVA layer having a thickness of 5 μm to an initial setting thickness of 600 nm to continuously form a first coating film.
On the other hand, on another continuous line, using a gravure roll coating system equipped with a gravure roll, the prepared adhesive composition B was applied to the bonding surface of the transparent protective film with an initial setting thickness of 1150 nm to continuously form a second coating film. The ratio of the thickness of the first coating film to the thickness of the second coating film (thickness ratio) was initially set to 0.522 (600 nm/1150 nm).
Then, on a continuous line, the thicknesses of the first coating film and the second coating film are measured in-line with a spectral interference film thickness meter (manufactured by Ocean Optics: spectroscope “USB2000+”, light source “HL-2000”, fiber “OCF-103995”), and the ratio (thickness ratio) of the thickness of the first coating film to the thickness of the second coating film obtained by in-line measurement is within ±1% of the initially set thickness ratio (0.522). , the coating amount of the adhesive composition A in the first coating step and the coating amount of the adhesive composition B in the second coating step were appropriately adjusted.
Thereafter, a polarizing film was obtained in the same manner as in Example 1. A polarizing film was continuously manufactured for 15 hours through the series of steps.

Comparative example 1
On a continuous line, using a gravure roll coating method equipped with a gravure roll, the prepared adhesive composition A was applied to the PVA surface of the prepared optical film laminate containing a PVA layer with a thickness of 5 μm to an initial setting thickness of 690 nm to continuously form a first coating film.
On the other hand, on another continuous line, using a gravure roll coating system equipped with a gravure roll, the prepared adhesive composition B was applied to the bonding surface of the transparent protective film with an initial setting thickness of 1280 nm to continuously form a second coating film. The ratio of the thickness of the first coating film to the thickness of the second coating film (thickness ratio) was initially set to 0.539 (690 nm/1280 nm).
Next, using a roll machine, the bonding surface on which the first coating film of the optical film laminate was formed and the bonding surface on which the second coating film of the transparent protective film was formed were bonded together to form an uncured adhesive layer. After that, from the side of the laminated transparent protective film, the visible light was irradiated using an active energy ray irradiation device to adhere the polarizer and the transparent protective film via an adhesive layer, followed by hot air drying at 70° C. for 3 minutes, and the amorphous PET base material was peeled off to obtain a polarizing film having a transparent protective film on one side of the polarizer. The lamination line speed was 25 m/min. A polarizing film was continuously manufactured for 15 hours through the series of steps.

(Evaluation of adhesive force)
Five minutes after the start of production and 15 hours after the start of production, the polarizing film was cut into a size of 200 mm parallel to the stretching direction of the polarizer and 15 mm in the direction perpendicular to it, and the polarizing film was attached to a glass plate. Then, a cut was made between the transparent protective film and the polarizer with a cutter knife, and Tensilon was used to peel the transparent protective film and the polarizer at a peeling speed of 1000 mm/min in the direction of 90 degrees.
○: When the peel force is 1N or more ×: When the peel force is less than 1N

From Table 2, in Examples 1 to 3, since the thickness measurement step and the coating amount adjustment step are performed, fluctuations in the thickness ratio between the first coating film and the second coating film are suppressed during continuous production. On the other hand, in Comparative Example 1, since the thickness measurement step and the coating amount adjustment step were not performed, the variation in the thickness ratio between the first coating film and the second coating film increased during continuous production, and 15 hours after the start of production.

The polarizing film of the present invention is used alone or as an optical film in which it is laminated for use in image display devices such as liquid crystal display devices (LCD), organic EL display devices, CRTs and PDPs.

1: Polarizing film 2: Polarizer 3: Transparent protective film 4, 5: Coating machine 6, 7: Thickness meter 8: Dryer

Claims (8)

A method for producing a polarizing film in which a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer,
A first coating step of applying an adhesive composition A containing 50 to 99% by mass of a polymerizable compound X having an SP value of 21.0 (MJ/m ³ ) ^1/2 or more and 26.0 (MJ/m ³ ) ^1/2 or less to the bonding surface of the polarizer while conveying the polarizer to form a first coating film;
A second coating step of applying an adhesive composition B containing 25 to 80% by mass of the polymerizable compound X to the bonding surface of the transparent protective film while conveying the transparent protective film to form a second coating film;
A thickness measurement step of in-line measuring the thickness of the first coating film and the second coating film;
Based on the thicknesses of the first coating film and the second coating film obtained by the in-line measurement, the content of the polymerizable compound X in the uncured adhesive layer obtained by bonding the first coating film and the second coating film is 40 to 64% by mass.
A method for producing a polarizing film, comprising: a bonding step of bonding a bonding surface of the polarizer on which the first coating film is formed and a bonding surface of the transparent protective film on which the second coating film is formed to form the uncured adhesive layer; and a bonding step of bonding the polarizer and the transparent protective film via the adhesive layer obtained by curing the uncured adhesive layer. The adhesive composition A and / or the adhesive composition B contains a polymerization initiator,
The coating amount adjusting step is a step of adjusting the coating amount of the adhesive composition A in the first coating step and/or the coating amount of the adhesive composition B in the second coating step so that the content of the polymerization initiator in the uncured adhesive layer obtained by bonding the first coating and the second coating is 2.3 to 7% by mass based on the thicknesses of the first coating and the second coating obtained by the in-line measurement. The method for producing the polarizing film according to 1. 3. The method for producing a polarizing film according to claim 1, wherein the polymerizable compound X is at least one selected from the group consisting of acryloylmorpholine, N-methoxymethylacrylamide, and N-ethoxymethylacrylamide. The adhesive composition A has the following general formula (1):
wherein X is a functional group containing a reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group, or a heterocyclic group) and/or an organometallic compound having a MO bond (M is silicon, titanium, aluminum, or zirconium, and O is an oxygen atom) in the structural formula. The compound represented by the general formula (1) is the following general formula (1')
The method for producing a polarizing film according to claim 4, which is a compound represented by (Y is an organic group, and X, ^R1 and ^R2 are the same as described above). The reactive group possessed by the compound represented by the general formula (1) is an α,β-unsaturated carbonyl group, a vinyl group, a vinyl ether group, an epoxy group, an oxetane group, an amino group, an aldehyde group, a mercapto group, and at least one reactive group selected from the group consisting of a halogen group. The method for producing a polarizing film according to claim 4 or 5. The method for producing a polarizing film according to any one of claims 1 to 6, wherein the first coating step and the second coating step are coating steps using a post-metering coating method. The method for producing a polarizing film according to claim 7, wherein the post-measurement coating method is a gravure roll coating method using a gravure roll.