TW202426983A - Polarizing plate with retardation layers and image display apparatus including polarizing plate with retardation layers - Google Patents

Abstract

Provided is a polarizing plate with retardation layers excellent in bending resistance. The polarizing plate with retardation layers includes in this order: a polarizing plate including a polarizer and a protective layer laminated on at least one surface of the polarizer; a first adhesion layer; a first retardation layer; a second adhesion layer; a second retardation layer; and a third adhesion layer. The polarizing plate with retardation layers has a total thickness of 90 μm or less, the second adhesion layer has a thickness of 3 μm or less, and a thickness of the first adhesion layer, the thickness of the second adhesion layer, and a thickness of the third adhesion layer satisfy the following relationship: thickness of second adhesion layer ≤ thickness of first adhesion layer ≤ thickness of third adhesion layer.

Description

Polarizing plate with phase difference layer and image display device including the polarizing plate with phase difference layer

The present invention relates to a polarizing plate with a phase difference layer and an image display device including the polarizing plate with a phase difference layer.

In recent years, image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (for example, organic EL display devices, inorganic EL display devices) are rapidly becoming popular. In image display devices, polarizing plates and phase difference plates are typically used. In terms of practicality, polarizing plates with phase difference layers, in which the polarizing plates and phase difference plates are integrated, are widely used (for example, Patent Document 1). As the desire for thinning of image display devices increases, the desire for thinning of polarizing plates with phase difference layers also increases. With the purpose of thinning the polarizing plates with phase difference layers, the thinning of phase difference plates continues to progress, and phase difference plates made of liquid crystal materials are used. In addition, as the uses of image display devices expand, the expectations for image display devices also diversify. For example, a smartphone is required to be foldable. Therefore, it is strongly expected that a polarizing plate with a phase difference layer can be realized in the image display device. Prior art literature Patent literature

Patent document 1: Japanese Patent No. 3325560

Problem to be solved by the invention The present invention is made to solve the above-mentioned previous problems, and its main purpose is to provide a polarizing plate with a phase difference layer having excellent bending resistance.

Means for solving the problem 1. The polarizing plate with phase difference layer of the embodiment of the present invention comprises in order: a polarizing plate, which includes a polarizer and a protective layer laminated on at least one side of the polarizer; a first connecting layer; a first phase difference layer; a second connecting layer; a second phase difference layer; and a third connecting layer. The total thickness of the polarizing plate with phase difference layer is less than 90 μm; the thickness of the second connecting layer is less than 3 μm; the thickness of the first connecting layer, the thickness of the second connecting layer, and the thickness of the third connecting layer satisfy the relationship of the thickness of the second connecting layer ≤ the thickness of the first connecting layer ≤ the thickness of the third connecting layer. 2. In the polarizing plate with a phase difference layer of the above 1, the storage elastic modulus G' of the above third bonding layer at 25°C may also be 100 kPa or less. 3. In the polarizing plate with a phase difference layer of the above 1 or 2, the thickness of the above polarizer may also be 10 μm or less. 4. In the polarizing plate with a phase difference layer of any one of the above 1 to 3, the thickness of the above protective layer may also be 40 μm or less. 5. In the polarizing plate with a phase difference layer of any one of the above 1 to 4, the above first phase difference layer and the above second phase difference layer may also be oriented solidified layers of liquid crystal oriented compounds. 6. In the polarizing plate with phase difference layer of any one of 1 to 5 above, the Re(550) of the first phase difference layer may be 100nm to 190nm, the Re(450)/Re(550) of the first phase difference layer may be greater than 0.8 and less than 1, and the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer may be 40° to 50°. 7. In the polarizing plate with phase difference layer of 6 above, the refractive index characteristics of the second phase difference layer may also show the relationship of nz＞nx=ny. 8. In the polarizing plate with phase difference layer of any one of 1 to 5 above, the Re(550) of the first phase difference layer may be 200nm to 300nm, and the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer may be 10° to 20°; the Re(550) of the second phase difference layer may be 100nm to 190nm, and the angle formed by the slow axis of the second phase difference layer and the absorption axis of the polarizer may be 70° to 80°. 9. In the polarizing plate with phase difference layer of any one of 1 to 8 above, the storage elastic modulus G' of the first connecting layer at 25°C may be 30kPa to 140kPa. 10. The polarizing plate with a phase difference layer of any one of 1 to 9 above can also be used in a flexible image display device. 11. Another aspect of the present invention provides an image display device. The image display device includes the polarizing plate with a phase difference layer of any one of 1 to 10 above.

Effect of the invention According to the embodiment of the present invention, a polarizing plate with a phase difference layer having excellent resistance to bending can be provided. According to the embodiment of the present invention, even in the case of including a phase difference layer as a liquid crystal directional solidification layer, a polarizing plate with a phase difference layer having excellent resistance to bending and suppressing the generation of cracks caused by constituent elements such as the phase difference layer can be provided. Therefore, the polarizing plate with a phase difference layer of the embodiment of the present invention can also be suitably used in a bendable image display device.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols) The definitions of terms and symbols in this manual are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index in the plane is the largest (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference measured at 23°C with light of wavelength λnm. For example, "Re(550)" is the in-plane phase difference measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is set to d(nm), Re(λ) can be calculated by the formula: Re(λ)=(nx-ny)×d. (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured at 23°C with light of wavelength λnm. For example, "Rth(550)" is the retardation in the thickness direction measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is set to d(nm), Rth(λ) can be calculated by the formula: Rth(λ)=(nx-nz)×d. (4) Nz coefficient The Nz coefficient can be calculated by Nz=Rth/Re. (5) Angle When an angle is mentioned in this manual, the angle includes both the clockwise direction and the counterclockwise direction relative to the reference direction. Therefore, for example, "45°" means ±45°.

A. Overall structure of polarizing plate with phase difference layer FIG. 1 is a schematic cross-sectional view of a polarizing plate with phase difference layer of an embodiment of the present invention. The polarizing plate with phase difference layer 100 of the illustrated example comprises, from the visual side, a polarizing plate 10, which includes a polarizer 11 and a protective layer 12 laminated on one surface of the polarizer; a first bonding layer 20; a first phase difference layer 30; a second bonding layer 40; a second phase difference layer 50; and a third bonding layer 60. The total thickness of the polarizing plate with phase difference layer 100 is less than 90 μm. In the example of the figure, the polarizer 10 has the protective layer 12 only on one side, but the protective layer may be laminated on both sides of the polarizer 11 (not shown). The first bonding layer 20, the second bonding layer 40 and the third bonding layer 60 are adhesive layers formed by any suitable adhesive, or adhesive layers formed by any suitable adhesive. The thickness of the second bonding layer 40 is less than 3 μm. The first phase difference layer 30 and the second phase difference layer 50 are preferably oriented solidified layers of liquid crystal compounds (hereinafter, sometimes referred to as liquid crystal oriented solidified layers). In this specification, "liquid crystal oriented solidified layer" refers to a layer in which the liquid crystal compound is oriented along a predetermined direction within the layer and its oriented state is fixed. In addition, the term "directional solidified layer" is a concept that includes a directional solidified layer obtained by solidifying a liquid crystal monomer as described later.

The thickness of the first bonding layer 20, the thickness of the second bonding layer 40, and the thickness of the third bonding layer 60 satisfy the relationship of the thickness of the second bonding layer ≤ the thickness of the first bonding layer ≤ the thickness of the third bonding layer. For a polarizing plate used in a flexible image display device, repeated bending will apply stress to the polarizer and bonding layers (e.g., adhesive layer), which may cause appearance defects such as cracks. If the first bonding layer 20, the second bonding layer 40, and the third bonding layer 60 satisfy the above relationship, the stress applied to the first phase difference layer 30 and the second phase difference layer 50 adjacent to each bonding layer can be alleviated when the polarizing plate with phase difference layer is bent. As a result, a polarizing plate with a phase difference layer having excellent bending resistance can be provided.

As mentioned above, the total thickness of the polarizing plate 100 with a phase difference layer is less than 90 μm, preferably less than 80 μm, more preferably less than 70 μm, more preferably less than 60 μm, and particularly preferably less than 50 μm. The total thickness of the polarizing plate with a phase difference layer can be, for example, more than 25 μm. If the total thickness of the polarizing plate with a phase difference layer is within the above range, the secondary moment of the cross section during bending will become smaller, thereby reducing the stress applied to each component (layer). Therefore, the bending resistance of the polarizing plate with a phase difference layer can be further improved. In addition, the total thickness of the polarizing plate with a phase difference layer refers to the total thickness of the polarizing plate, the phase difference layer (the first phase difference layer and the second phase difference layer) and the bonding layer (the first bonding layer, the second bonding layer and the third bonding layer) (that is, the total thickness of the polarizing plate with a phase difference layer does not include the thickness of the peel-off pad that can be temporarily attached to the surface of the third bonding layer).

The components of the polarizing plate with a phase difference layer are described in more detail below.

B. Polarizing plate B-1. Polarizer The polarizer is typically composed of a resin film containing a dichroic substance (typically iodine). As the resin film, any appropriate resin film that can be used as a polarizer can be used. The resin film is typically a polyvinyl alcohol resin (hereinafter referred to as "PVA resin") film. The resin film can be a single-layer resin film or a laminate of two or more layers.

As a specific example of a polarizer composed of a single-layer resin film, a polarizer obtained by subjecting a PVA-based resin film to a dyeing treatment using iodine and a stretching treatment (typically uniaxial stretching) can be cited. The above-mentioned dyeing using iodine is performed, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after the dyeing treatment, or it can be performed while dyeing. In addition, dyeing can also be performed after stretching. If necessary, the PVA-based resin film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, etc. For example, by immersing the PVA-based resin film in water and washing it before dyeing, not only can the dirt or anti-adhesive agent on the surface of the PVA-based resin film be washed away, but the PVA-based resin film can also be swelled to prevent uneven dyeing.

Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by the following method: a PVA-based resin solution is coated on a resin substrate and dried to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; the laminate is stretched and dyed to make the PVA-based resin layer into a polarizer. In this embodiment, a polyvinyl alcohol-based resin layer containing a halogenated substance and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. Stretching typically includes immersing the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching may further include stretching the laminate in the air at a high temperature (for example, above 95°C) before stretching in an aqueous boric acid solution, if necessary. In addition, in this embodiment, the laminate is preferably subjected to a dry shrinking treatment, which is performed by heating the laminate while transporting it in the long-side direction so that it shrinks by more than 2% in the width direction. The manufacturing method representing this embodiment includes sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a dry shrinking treatment on the laminate. By introducing auxiliary stretching, the crystallinity of PVA can be improved even when PVA is coated on a thermoplastic resin, thereby achieving high optical properties. At the same time, by improving the orientation of PVA in advance, when immersed in water in the subsequent dyeing step and stretching step, the problems such as reduction in orientation or dissolution of PVA can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the orientation disorder and reduction in orientation of the polyvinyl alcohol molecules can be suppressed more than when the PVA-based resin layer does not contain halides. Thereby, the optical properties of the polarizer obtained by the treatment steps of immersing the laminate in a liquid such as dyeing treatment and underwater stretching treatment can be improved. Furthermore, by shrinking the laminate in the width direction by using a dry shrinking treatment, the optical properties can be improved. The obtained resin substrate/polarizer laminate can be used directly (i.e., the resin substrate can also be used as a protective layer of the polarizer), or the resin substrate can be peeled off from the resin substrate/polarizer laminate and any appropriate protective layer that meets the purpose can be used on the peeled area layer. The details of the manufacturing method of the aforementioned polarizer are described in, for example, Japanese Patent Publication No. 2012-73580 (Japanese Patent No. 5414738) and Japanese Patent No. 6470455. The entire description thereof is cited as a reference in this specification.

The thickness of the polarizer is preferably 10 μm or less, more preferably 1 μm to 10 μm, more preferably 1 μm to 8 μm, and particularly preferably 2 μm to 5 μm. If the thickness of the polarizer is within the above range, it can help to reduce the thickness of the polarizing plate with a phase difference layer. In addition, the bending resistance of the polarizing plate with a phase difference layer can be improved.

The polarizer preferably shows absorption dichroism at any wavelength between 380nm and 780nm. The single transmittance Ts of the polarizer is preferably 40% to 48%, preferably 41% to 46%. The polarization degree P of the polarizer is preferably 97.0% or more, preferably 99.0% or more, and more preferably 99.9% or more. The above single transmittance is typically measured using an ultraviolet-visible spectrophotometer and the Y value is corrected for the visual sensitivity. The above polarization degree is typically measured using an ultraviolet-visible spectrophotometer and corrected for the visual sensitivity, and is calculated based on the obtained parallel transmittance Tp and orthogonal transmittance Tc by the following formula. Polarization degree (%) = {(Tp-Tc)/(Tp+Tc)} ^{1 /2} ×100

B-2. Protective layer The protective layer is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of the material that is the main component of the film include cellulose resins such as triacetate cellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyether sulfone resins, polysulfone resins, polystyrene resins, polybutylene resins, polyolefin resins, (meth)acrylic resins, acetate resins and other transparent resins. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, and silicone resins can also be listed. In addition, glassy polymers such as silicone polymers can also be listed. In addition, the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted amide group on the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group on the side chain can be used, for example, a resin composition having an alternating copolymer formed by isobutylene and N-methylmaleimide and acrylonitrile-styrene copolymer can be listed. The polymer film can be, for example, an extruded product of the above resin composition.

The polarizing plate with phase difference layer is typically disposed on the visual side of the image display device, and the protective layer 12 is typically disposed on the visual side thereof. Therefore, the protective layer may be subjected to surface treatments such as hard coating, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment as needed.

The thickness of the protective layer is preferably 40 μm or less, more preferably 10 μm to 40 μm, and more preferably 10 μm to 30 μm. Furthermore, when surface treatment is applied, the thickness of the outer protective layer (protective layer 12) is the thickness including the thickness of the surface treatment layer.

C. Adhesive layer The adhesive layer is an adhesive layer formed by any appropriate adhesive, or an adhesive layer formed by any appropriate adhesive. As described above, the adhesive layer satisfies the relationship of the thickness of the second adhesive layer ≤ the thickness of the first adhesive layer ≤ the thickness of the third adhesive layer. The adhesive layer may be an adhesive layer or an adhesive layer as long as the thickness of each adhesive layer satisfies the above relationship. In the case where the thickness of the first adhesive layer is greater than the thickness of the third adhesive layer, the stress applied to the first phase difference layer adjacent to the first adhesive layer during bending will increase, and cracks may be easily generated. Furthermore, the stress relief applied to the second phase difference layer adjacent to the third bonding layer may not be sufficient. Furthermore, when the thickness of the second bonding layer is greater than the thickness of the first bonding layer, the stress applied to the first phase difference layer and the second phase difference layer adjacent to the second bonding layer will increase, and it will be difficult to fully relieve the stress using other bonding layers (the first bonding layer and the third bonding layer), and strain may easily occur.

The thickness of the second bonding layer is 3 μm or less, preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1 μm or less. The thickness of the second bonding layer is preferably 0.5 μm or more. When the thickness of the second bonding layer is greater than 3 μm, the stress applied to the adjacent first phase difference layer and second phase difference layer will increase, and cracks and other appearance defects may be easily generated. When the thickness of the second bonding layer is within the above range, the second bonding layer is preferably an adhesive layer. If the second bonding layer is an adhesive layer, the first phase difference layer and the second phase difference layer can be sufficiently adhered even with the above thickness.

The thickness of each bonding layer can be set to any appropriate value as long as the thickness of the second bonding layer is less than 3 μm and satisfies the relationship of the thickness of the second bonding layer ≤ the thickness of the first bonding layer ≤ the thickness of the third bonding layer. The thickness of the first bonding layer is, for example, 1 μm to 30 μm, preferably 1 μm to 25 μm, more preferably 1 μm to 20 μm, and more preferably 1 μm to 10 μm. The thickness of the third bonding layer is, for example, 5 μm to 60 μm, preferably 5 μm to 50 μm, and more preferably 10 μm to 30 μm. When the polarizing plate with a phase difference layer according to the embodiment of the present invention is applied to a flexible image display device, the position of the bending center can be adjusted to any appropriate position of the image display device by adjusting the thickness of each bonding layer to any appropriate value.

The storage modulus G' of the first bonding layer at 25°C is preferably 30 kPa to 140 kPa, more preferably 35 kPa to 135 kPa. If the storage modulus G' is within the above range, a polarizing plate with a phase difference layer having excellent bending resistance can be provided. In addition, when the first bonding layer has the above storage modulus G', the bonding layer may be an adhesive layer.

The storage modulus G' of the third connecting layer at 25°C is preferably 100 kPa or less, more preferably 90 kPa or less, and even more preferably 85 kPa or less. The storage modulus G' of the third connecting layer at 25°C is, for example, 20 kPa or more. Regarding the stress applied to the phase difference layer, the second phase difference layer may be greater than the first phase difference layer. If the storage modulus G' of the third connecting layer adjacent to the second phase difference layer is within the above range, a polarizing plate with a phase difference layer having excellent bending resistance can be provided. In addition, when the third connecting layer has the above-mentioned storage modulus G', the connecting layer may be an adhesive layer.

C-1. Adhesive When the bonding layer is an adhesive layer formed of an adhesive, a bonding layer having the storage elastic modulus G' as described above can be formed. In addition, a polarizing plate with a phase difference layer having excellent reworkability can be obtained. When the bonding layer is an adhesive layer, the adhesive layer can be formed using any appropriate adhesive. The adhesive contains at least a base polymer. The base polymer is an adhesive component that exhibits adhesiveness in the adhesive layer. Examples of the base polymer include acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers. The base polymer may be used alone or in combination of two or more. From the perspective of ensuring good transparency and adhesion in the adhesive layer (adhesive layer), it is preferable to use an acrylic polymer as the base polymer.

In the present specification, an acrylic polymer is a copolymer containing a monomer component of an alkyl (meth)acrylate at a ratio of 50% by weight or more. "(Meth)acrylic acid" refers to acrylic acid and/or methacrylic acid.

As the alkyl (meth)acrylate, those having an alkyl carbon number of 1 to 20 are preferably used, and those having an alkyl carbon number of 10 to 20 are more preferably used. The alkyl (meth)acrylate may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.

Examples of the (meth)acrylic acid alkyl ester having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, oct ... Nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (i.e., lauryl acrylate), isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate, etc.

Examples of the (meth)acrylic acid alkyl ester having an alicyclic alkyl group include cycloalkyl (meth)acrylic acid ester, (meth)acrylic acid ester having a bicyclic aliphatic hydrocarbon ring, and (meth)acrylic acid ester having a tricyclic or higher aliphatic hydrocarbon ring. Examples of the (meth)acrylic acid alkyl ester include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of the (meth)acrylic acid ester having a bicyclic aliphatic hydrocarbon ring include isobutyl (meth)acrylate. Examples of the (meth)acrylate having a tricyclic or higher aliphatic hydrocarbon ring include dicyclopentyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, tricyclopentyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

As the (meth)acrylic acid alkyl ester, an alkyl acrylate having an alkyl group with 3 to 15 carbon atoms is preferably used, and at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate and dodecyl acrylate (i.e., lauryl acrylate) is more preferably used.

From the viewpoint of appropriately expressing basic properties such as adhesion in the adhesive layer, the content of the alkyl (meth)acrylate in the monomer component is preferably 60% by weight or more, more preferably 70% by weight or more, and more preferably 80% by weight or more. The content of the alkyl (meth)acrylate in the monomer component is, for example, 99% by weight or less.

The content of the (meth)acrylic acid alkyl ester having a linear alkyl group having 10 to 20 carbon atoms is preferably 1 to 40 parts by weight, more preferably 5 to 35 parts by weight, based on 100 parts by weight of the total monomer components of the acrylic base polymer. Lauryl acrylate is particularly preferably used within the above range.

The monomer component may also contain a copolymerizable monomer copolymerizable with the (meth)acrylic acid alkyl ester. Examples of the copolymerizable monomer include monomers having a polar group. Examples of the polar group-containing monomer include monomers having a nitrogen atom ring, hydroxyl group-containing monomers, and carboxyl group-containing monomers. The polar group-containing monomer contributes to the modification of the acrylic polymer, such as introducing crosslinking points into the acrylic polymer and ensuring the cohesive force of the acrylic polymer.

Examples of the monomer having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperidone, N-vinylpyrrolidone, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(methyl)acryloyl-2-pyrrolidone, N-(methyl)acryloylpiperidine, N-(methyl)acryloylpyrrolidine, N-vinyloxapyrrolidine, N-vinyloxapyrrolidine, N-vinyloxapyrrolidine, N-vinyloxapyrrolidine, N-vinyl-3-oxapyrrolidone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxapyrrol-2-one, N-vinyl-3,5-oxapyrroldione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. As the monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

From the perspective of ensuring the cohesive force in the adhesive layer and the adhesion of the adhesive layer to the adherend, the content of the monomer having a nitrogen atom ring in the monomer component is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, and more preferably 0.55% by weight or more. From the perspective of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to the compatibility of various additive components in the adhesive layer with the acrylic polymer), the content of the monomer having a nitrogen atom ring in the monomer component is preferably 10% by weight or less, and more preferably 5% by weight or less.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxyl group-containing monomer, 4-hydroxybutyl (meth)acrylate is preferably used, and 4-hydroxybutyl acrylate is more preferably used.

From the perspective of introducing the cross-linked structure into the acrylic polymer and ensuring the cohesive force in the adhesive layer, the content of the hydroxyl monomer in the monomer component is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and more preferably 0.8% by weight or more. From the perspective of adjusting the polarity of the acrylic polymer (related to the compatibility of various additive components in the adhesive with the acrylic polymer), the content of the hydroxyl monomer in the monomer component is preferably 10% by weight or less, and more preferably 8% by weight or less.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

From the perspective of introducing a cross-linked structure into the acrylic polymer, ensuring the cohesive force in the adhesive layer, and ensuring the adhesion of the adhesive layer to the adherend, the content of the carboxyl group-containing monomer in the monomer component is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and more preferably 0.8% by weight or more. From the perspective of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by acid, the content of the carboxyl group-containing monomer in the monomer component is preferably 30% by weight or less, and more preferably 25% by weight or less.

The content ratio of the polar group-containing monomer in the monomer component is preferably 5% by weight or more, more preferably 6% by weight or more, more preferably 7% by weight or more, and particularly preferably 8% by weight or more. On the other hand, as the content ratio of the polar group-containing monomer increases, the dipole moment of the base polymer increases, and the relative dielectric constant increases. In addition, if the content ratio of the polar group-containing monomer is too high, the glass transition temperature of the polymer tends to increase, and the adhesive force tends to decrease at low temperatures. Therefore, the content ratio of the polar group-containing monomer in the monomer component is preferably 30% by weight or less, and preferably 25% by weight or less.

The monomer component may also contain other copolymerizable monomers. Examples of other copolymerizable monomers include acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. These other copolymerizable monomers may be used alone or in combination of two or more.

The base polymer preferably has a crosslinking structure. Methods for introducing a crosslinking structure into the base polymer include, for example, a method of mixing a base polymer having a functional group that can react with a crosslinking agent and a crosslinking agent into an adhesive, and reacting the base polymer and the crosslinking agent in the adhesive layer; and a method of introducing a branched structure (crosslinking structure) into a polymer chain by polymerizing a monomer component that includes a multifunctional monomer to form a base polymer. These methods may also be used in combination.

Acrylic polymers can be formed by polymerizing monomer components. As a polymerization method, any appropriate method can be used. For example, solution polymerization, active energy line polymerization (for example, UV polymerization), bulk polymerization and emulsion polymerization can be listed. From the perspective of transparency, water resistance and cost of the adhesive layer, solution polymerization and UV polymerization are preferred. As a solvent for solution polymerization, for example, ethyl acetate and toluene are used. In addition, as an initiator for polymerization, for example, a thermal polymerization initiator and a photopolymerization initiator are used. Relative to a total of 100 parts by weight of the monomer components, the amount of the polymerization initiator used is, for example, more than 0.05 parts by weight, and for example, less than 1 part by weight.

From the viewpoint of ensuring the cohesive force in the adhesive layer, the weight average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and more preferably 500,000 or more. The weight average molecular weight of the acrylic polymer is preferably 5 million or less, more preferably 3 million or less, and more preferably 2 million or less. The weight average molecular weight of the acrylic polymer can be measured by gel permeation chromatography (GPC) and calculated by polystyrene conversion.

The glass transition temperature (Tg) of the base polymer is preferably 0° C. or lower, more preferably -10° C. or lower, and more preferably -20° C. or lower. The glass transition temperature of the base polymer is, for example, -80° C. or higher.

The adhesive may further include an oligomer. When an acrylic polymer is used as the base polymer, an acrylic oligomer is preferably used as the oligomer. The acrylic oligomer is a copolymer containing a monomer component of an alkyl (meth)acrylate at a content ratio of 50% by weight or more, and the weight average molecular weight is, for example, 1,000 or more and 30,000 or less.

As a crosslinking agent, any appropriate crosslinking agent can be used, for example, compounds that react with the functional groups (hydroxyl and carboxyl groups, etc.) contained in the base polymer can be listed. As the crosslinking agent, for example, isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, azamide crosslinking agents, carbodiimide crosslinking agents and metal chelate crosslinking agents can be listed. Only one crosslinking agent can be used, or two or more can be used in combination. As a crosslinking agent, isocyanate crosslinking agents, peroxide crosslinking agents and epoxy crosslinking agents are preferably used because they are highly reactive with the hydroxyl and carboxyl groups in the base polymer and are easily introduced into the crosslinked structure.

The adhesive may further contain a silane coupling agent. The content of the silane coupling agent in the adhesive is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, relative to 100 parts by weight of the base polymer. The content of the silane coupling agent is preferably 5 parts by weight or less, more preferably 3 parts by weight or less.

The adhesive may contain any other appropriate components as required. Examples of the other components include adhesives, plasticizers, softeners, anti-degradation agents, fillers, colorants, ultraviolet absorbers, antioxidants, surfactants, and antistatic agents.

C-2. Adhesive When the adhesive layer is an adhesive layer, excellent adhesion can be exhibited even when the adhesive layer is thin, such as the second adhesive layer. The adhesive layer as an adhesive layer can be formed by any appropriate adhesive. As the adhesive, an active energy ray curing type adhesive is preferably used.

As an active energy ray-curing adhesive, any appropriate active energy ray-curing adhesive can be used. Examples of active energy ray-curing adhesives include ultraviolet ray-curing adhesives and electron beam-curing adhesives. In addition, from the perspective of the curing mechanism, examples of active energy ray-curing adhesives include free radical curing adhesives, cationic curing adhesives, anionic curing adhesives, and mixed types of free radical curing adhesives and cationic curing adhesives. Representatively, free radical-curing ultraviolet ray-curing adhesives can be used. This is because of their excellent versatility and easy adjustment of characteristics (structure).

Active energy ray-curing adhesives typically contain monofunctional components, multifunctional components (curing components) and photopolymerization initiators. The monofunctional components and multifunctional components are typically free radical polymerizable compounds. As ideal monofunctional components, for example, higher alkyl esters of (meth)acrylic acid and their modified forms can be listed. Specifically, isostearyl acrylate, lauryl acrylate, acrylamide, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, etc. can be listed. As ideal multifunctional components, for example, monomers and/or oligomers having two or more functional groups such as (meth)acrylate groups and (meth)acrylamide groups can be listed. Specifically, polyethylene glycol diacrylate, trimethylolpropane triacrylate, and glycerol triacrylate can be listed. Specific examples of the monofunctional component or polyfunctional component other than the above include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecanedimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic trihydroxymethylpropane formal acrylate, dialkylene glycol diacrylate, EO-modified diglycerol tetraacrylate, γ-butyrolactone acrylate, N-methylpyrrolidone, hydroxyethylacrylamide, N-hydroxymethylacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, and 9-vinylcarbazole. In one embodiment, the monofunctional component or polyfunctional component has a ring structure. Specifically, acryloyl isofolin, γ-butyrolactone acrylate, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, N-methylpyrrolidone, and 9-vinylcarbazole can be mentioned. The monofunctional component or the polyfunctional component can be used alone or in combination of two or more.

The active energy ray-curable adhesive may further contain a cationic polymerizable compound as needed. The cationic polymerizable compound may be monofunctional or polyfunctional. Examples of monofunctional cationic polymerizable compounds include tertiary butylphenyl glycidyl ether and 3-ethyl-3-[(2-ethylhexyl)oxy]cyclohexylbutane. Examples of polyfunctional cationic polymerizable compounds include 3-ethyl-3-{[(3-ethylcyclohexyl-3-yl)methoxy]methyl}cyclohexylbutane. As a cationic polymerizable compound, a silane coupling agent may also be used. Examples of silane coupling agents include 3-glycidoxypropyltrimethoxysilane.

The active energy ray-curable adhesive may further contain an acrylic oligomer as necessary. The molecular weight of the acrylic oligomer may be appropriately set depending on the purpose.

The active energy ray-curable adhesive may further contain a plasticizer (for example, an oligomer component), a crosslinking agent, a diluent, etc., depending on the purpose. In addition, commercially available products may be used for the above-mentioned components.

The details of the active energy ray-curable adhesive are described in, for example, Japanese Patent Application Publication No. 2018-017996. The description of the publication is incorporated herein by reference.

D. Phase difference layer The first phase difference layer and the second phase difference layer are preferably directional solidified layers of liquid crystal compounds. By using liquid crystal compounds, the same in-plane phase difference as that of the resin film can be achieved with a significantly thinner thickness than the resin film. In addition, since the phase difference layer, which is a directional solidified layer of the liquid crystal compound, is thin and brittle, problems may arise in terms of bending resistance. The polarizing plate with phase difference layer of the embodiment of the present invention is as described above, and the thickness of the first bonding layer, the thickness of the second bonding layer, and the thickness of the third bonding layer satisfy the relationship of the thickness of the second bonding layer ≤ the thickness of the first bonding layer ≤ the thickness of the third bonding layer. If the aforementioned bonding layer is configured, even when a directional solidification layer of a liquid crystal compound is used as a phase difference layer, the stress applied to the phase difference layer can be alleviated, thereby improving the bending resistance.

In one embodiment, the first phase difference layer preferably has Re(550) of 100nm to 190nm, Re(450)/Re(550) of the first phase difference layer is greater than 0.8 and less than 1, and the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer is 40° to 50°. In this embodiment, the refractive index characteristics of the second phase difference layer preferably show the relationship of nz＞nx=ny (hereinafter, also referred to as embodiment 1). In another embodiment of the present invention, Re(550) of the first phase difference layer is 200nm~300nm, and the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer is 10°~20°; Re(550) of the second phase difference layer is 100nm~190nm, and the angle formed by the slow axis of the second phase difference layer and the absorption axis of the polarizer is 70°~80° (hereinafter also referred to as embodiment 2).

D-1. Implementation form 1 As described above, in implementation form 1, the first phase difference layer preferably has Re(550) of 100nm to 190nm, Re(450)/Re(550) of the first phase difference layer is greater than 0.8 and less than 1, and the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer is 40° to 50°. In this implementation form, the refractive index characteristics of the second phase difference layer preferably show the relationship of nz＞nx=ny.

D-1-1. First phase difference layer In this embodiment, the first phase difference layer can function as a λ/4 plate. The in-plane phase difference Re(550) of the first phase difference layer is preferably 100nm to 190nm, more preferably 110nm to 170nm, and more preferably 130nm to 160nm.

The Nz coefficient of the first phase difference layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3. By satisfying the above relationship, when the obtained polarizing plate with phase difference layer is used in an image display device, a very excellent reflection hue can be achieved.

The thickness of the first phase difference layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 7 μm, and even more preferably 1 μm to 5 μm.

The first phase difference layer preferably exhibits inverse dispersion wavelength characteristics. In this case, Re(550)/Re(650) is preferably greater than 1, more preferably greater than 1 and less than 1.2, and more preferably 1.01 to 1.15. Furthermore, Re(450)/Re(550) of the first phase difference layer is preferably greater than 0.8 and less than 1, and more preferably greater than 0.8 and less than 0.95. With the above-mentioned configuration, very excellent anti-reflection characteristics can be achieved. With the above-mentioned configuration, very excellent anti-reflection characteristics can be achieved.

In this embodiment, the angle formed by the slow axis of the first phase difference layer 30 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, and more preferably about 45°. If the angle is within the above range, by setting the first phase difference layer as a λ/4 plate as described above, a polarizing plate with a phase difference layer having very excellent circular polarization characteristics (resulting in very excellent anti-reflection characteristics) can be obtained.

As mentioned above, the first phase difference layer is preferably a directional solidified layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the phase difference layer obtained can be significantly greater than that of a non-liquid crystal material, so the thickness of the phase difference layer for obtaining the desired in-plane phase difference can be significantly reduced. As a result, the polarizing plate with a phase difference layer can be further thinned.

The phase difference layer as the oriented solidification layer of the liquid crystal compound can be formed using a composition containing a polymerizable liquid crystal compound. The polymerizable liquid crystal compound contained in the composition in this specification refers to a compound having a polymerizable group and having liquid crystal properties. The polymerizable group refers to a group that participates in the polymerization reaction, preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in the polymerization reaction by an active free radical or acid generated by a photopolymerization initiator.

Liquid crystal properties can be either thermotropic or lyotropic. Also, the liquid crystal phase can be either nematic or smectic. From the perspective of ease of production, thermotropic nematic liquid crystal is preferred.

In one embodiment, the phase difference layer as a single layer is formed using a composition containing a liquid crystal compound represented by the following formula (1). L ¹ -SP ¹ -A ¹ -D ³ -G ¹ -D ¹ -Ar-D ² -G ² -D ⁴ -A ² -SP ² -L ² (1)

^L1 and ^L2 each independently represent a monovalent organic group, and at least one of ^L1 and ^L2 represents a polymerizable group. As the monovalent organic group, any appropriate group is included. As the polymerizable group represented by at least one of ^L1 and ^L2 , a free radical polymerizable group (a group that can be polymerized by free radicals) can be cited. As the free radical polymerizable group, any appropriate free radical polymerizable group can be used. It is preferably an acryl group or a methacryl group. From the viewpoint of fast polymerization speed and improved productivity, an acryl group is preferably used. A methacryl group can also be used as a polymerizable group of a highly birefringent liquid crystal for the same purpose.

^SP1 and ^SP2 each independently represent a single bond, a linear or branched alkylene group, or a divalent linking group in which one or more _-CH2- groups constituting a linear or branched alkylene group having 1 to 14 carbon atoms are replaced by -O-. Preferred linear or branched alkylene groups having 1 to 14 carbon atoms include methylene, ethylene, propylene, butylene, pentylene, and hexylene.

^A1 and ^A2 each independently represent an alicyclic alkyl group or an aromatic ring substituent. ^A1 and ^A2 are preferably an aromatic ring substituent having 6 or more carbon atoms or a cycloalkyl ring having 6 or more carbon atoms.

D ¹ , D ² , D ³ and D ⁴ each independently represent a single bond or a divalent linking group. Specifically, D ¹ , D ² , D ³ and D ⁴ represent a single bond, -O-CO-, -C(=S)O-, -CR ¹ R ² -, -CR ¹ R ² -CR ³ R ⁴ -, -O-CR ¹ R ² -, -CR ¹ R ² -O-CR ³ R ⁴ -, -CO-O-CR ¹ R ² -, -O-CO-CR ¹ R ² -, -CR ¹ R ² -O-CO-CR ³ R ⁴ -, -CR ¹ R ² -CO-O-CR ³ R ⁴ -, -NR ¹ -CR ² R ³ - or -CO-NR ¹ -. At least one of D ¹ , D ² , D ³ and D ⁴ represents -O-CO-. D ³ is preferably -O-CO-, and D ³ and D ⁴ are more preferably -O-CO-. D ¹ and D ² are preferably single bonds. R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

^G1 and ^G2 each independently represent a single bond or an alicyclic alkyl group. Specifically, ^G1 and ^G2 may represent an unsubstituted or substituted divalent alicyclic alkyl group having 5 to 8 carbon atoms. Furthermore, one or more _-CH2- groups constituting the alicyclic alkyl group may be substituted with -O-, -S- or -NH-. ^G1 and ^G2 preferably represent a single bond.

Ar represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar represents, for example, an aromatic ring selected from the group consisting of the groups represented by the following formulae (Ar-1) to (Ar-6). In addition, in the following formulae (Ar-1) to (Ar-6), *1 represents a bonding site with ^D1 , and *2 represents a bonding site with ^D2 . [Chemical Formula 1]

In the formula (Ar-1), ^Q1 represents N or CH, ^Q2 represents -S-, -O- or -N( ^R5 )-, and ^R5 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In formulae (Ar-1) to (Ar-6), Z ¹ , Z ² and Z ³ each independently represent a hydrogen atom, a monovalent aliphatic alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic alkyl group having 3 to 20 carbon atoms, a monovalent aromatic alkyl group having 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, -NR ⁶ R ⁷ or -SR ⁸ . R ⁶ to R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Z ¹ and Z ² may be bonded to each other to form a ring. The ring may be any of an alicyclic, heterocyclic and aromatic ring, and is preferably an aromatic ring. The substituents in the formed ring may be substituted.

In formulae (Ar-2) and (Ar-3), ^A3 and ^A4 each independently represent a group selected from the group consisting of -O-, -N( ^R9 )-, -S- and -CO-, and ^R9 represents a hydrogen atom or a substituent. Examples of the substituent represented by ^R9 include the same substituents as those that may be possessed by ^Y1 in the above formula (Ar-1).

In the formula (Ar-2), X represents a hydrogen atom or an unsubstituted or substituted non-metal atom of Groups 14 to 16. Examples of the non-metal atom of Groups 14 to 16 represented by X include an oxygen atom, a sulfur atom, an unsubstituted or substituted nitrogen atom, and an unsubstituted or substituted carbon atom. Examples of the substituent include the same substituents as those that may be possessed by ^Y1 in the above formula (Ar-1).

In formula (Ar-3), ^D5 and ^D6 each independently represent a single bond, -O ^- CO-, -C(=S)O-, ^-CR1R2- , -CR1R2-CR3R4- ^{, -O -} CR1R2- ^{, -CR1R2- O - CR3R4-} , ^-CO -O- ^{CR1R2- , -O - CO - CR1R2- , -CR1R2 - O -} CO-CR3R4-, -CR1R2- ^CO -O-CR3R4-, ^-NR1 - ^CR2R3- , or ^-CO - ^{NR1- . R1} , ^R2 , ^R3 and ^R4 are as described above.

In formula (Ar-3), ^SP3 and ^SP4 each independently represent a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more _-CH2- constituting the linear or branched alkylene group having 1 to 12 carbon atoms is replaced by -O-, -S-, -NH-, -N(Q)- or -CO-, and Q represents a polymerizable group.

In the formula (Ar-3), ^L3 and ^L4 each independently represent a monovalent organic group, and at least one of ^L3 and ^L4 and ^L1 and ^L2 in the above formula (1) represents a polymerizable group.

In formulae (Ar-4) to (Ar-6), Ax represents an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocyclic rings. In formulae (Ar-4) to (Ar-6), Ax preferably has an aromatic heterocyclic ring, and more preferably has a benzothiazole ring. In formulae (Ar-4) to (Ar-6), Ay represents a hydrogen atom, an unsubstituted or substituted alkyl group having 1 to 6 carbon atoms, or an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocyclic rings. In formulae (Ar-4) to (Ar-6), Ay preferably represents a hydrogen atom.

In the formulae (Ar-4) to (Ar-6), Q ³ represents a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 6 carbon atoms. In the formulae (Ar-4) to (Ar-6), Q ³ preferably represents a hydrogen atom.

In the aforementioned Ar, preferably, there can be mentioned a group (atomic group) represented by the aforementioned formula (Ar-4) or the aforementioned formula (Ar-6).

Specific examples of the liquid crystal compound represented by formula (1) are disclosed in International Publication No. 2018/123551. The description of the publication is cited as a reference in this specification. These compounds may be used alone or in combination of two or more.

The composition containing the liquid crystal compound preferably contains a polymerization initiator. As the polymerization initiator, any appropriate polymerization agent can be used. It is preferably a photopolymerization initiator that can initiate a polymerization reaction by ultraviolet irradiation. As the photopolymerization initiator, for example, α-carbonyl compounds (described in the specifications of U.S. Patent No. 2,367,661 and U.S. Patent No. 2,367,670), acyloin ethers (described in the specification of U.S. Patent No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (described in the specification of U.S. Patent No. 2,722,512), polynuclear quinone compounds (described in the specifications of U.S. Patent No. 3,046,127 and U.S. Patent No. 2,951,758) can be listed. ), a combination of a triaryl imidazole dimer and p-aminophenyl ketone (described in the specification of U.S. Patent No. 3549367), a triazole compound (described in the specification of U.S. Patent No. 4212970), and an acylphosphine oxide compound (described in Japanese Patent Publication No. 63-40799, Japanese Patent Publication No. 5-29234, Japanese Patent Publication No. 10-95788, and Japanese Patent Publication No. 10-29997). The description of the publication is cited in this specification as a reference. The polymerization initiator may be used alone or in combination of two or more.

From the viewpoint of the workability of forming the phase difference layer, the composition containing the liquid crystal compound preferably contains a solvent. As the solvent, any appropriate solvent can be used, and an organic solvent is preferably used.

The composition containing the liquid crystal compound further contains any other appropriate components. For example, antioxidants such as phenolic antioxidants, liquid crystal compounds other than those mentioned above, leveling agents, surfactants, tilt control agents, orientation aids, plasticizers, and crosslinking agents can be mentioned.

The liquid crystal orientation solidified layer can be formed by performing an orientation treatment on the surface of a predetermined substrate, applying a composition (coating liquid) containing a liquid crystal compound on the surface and orienting the liquid crystal compound in a direction corresponding to the orientation treatment, and fixing the orientation state. In one embodiment, the substrate is any appropriate resin film, and the liquid crystal orientation solidified layer formed on the substrate can be transferred to the surface of the polarizing plate.

As the above-mentioned orientation treatment, any appropriate orientation treatment can be adopted. Specifically, mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment can be cited. As specific examples of mechanical orientation treatment, friction treatment and stretching treatment can be cited. As specific examples of physical orientation treatment, magnetic field orientation treatment and electric field orientation treatment can be cited. As specific examples of chemical orientation treatment, oblique evaporation method and light orientation treatment can be cited. Any appropriate treatment conditions can be adopted for various orientation treatments depending on the purpose.

The liquid crystal compound is oriented by treating it at a temperature that shows a liquid crystal phase according to the type of the liquid crystal compound. By performing the above-mentioned temperature treatment, the liquid crystal compound becomes a liquid crystal state, and the liquid crystal compound is oriented in accordance with the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the aligned liquid crystal compound. In the case where the liquid crystal compound is a polymerizable monomer or a crosslinking monomer, the alignment state is fixed by subjecting the aligned liquid crystal compound to a polymerization treatment or a crosslinking treatment.

The details of the method for forming the directional solidified layer are described in Japanese Patent Application Laid-Open No. 2006-163343, and the description of the publication is incorporated herein by reference.

D-1-2. Second phase difference layer As described above, the second phase difference layer can be a so-called positive C plate whose refractive index characteristics show the relationship of nz＞nx=ny. By using a positive C plate as the second phase difference layer, oblique reflection can be well prevented, and the anti-reflection function can be widened in viewing angle. At this time, the phase difference Rth(550) in the thickness direction of the second phase difference layer is preferably -50nm to -300nm, preferably -70nm to -250nm, more preferably -90nm to -200nm, and particularly preferably -100nm to -180nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the other phase difference layer can be less than 10nm.

The second phase difference layer having the refractive index characteristic of nz＞nx=ny can be formed by any appropriate material. The second phase difference layer is preferably composed of a film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented can be a liquid crystal monomer or a liquid crystal polymer. As a specific example of the liquid crystal compound and the method for forming the phase difference layer, the liquid crystal compound and the method for forming the phase difference layer described in [0020] to [0028] of Japanese Patent Gazette No. 2002-333642 can be cited. At this time, the thickness of the second phase difference layer is preferably 0.5μm to 10μm, more preferably 0.5μm to 8μm, and more preferably 0.5μm to 5μm.

D-2. Second embodiment In the second embodiment, the first phase difference layer preferably has Re(550) of 200nm to 300nm, and the angle between the slow axis of the first phase difference layer and the absorption axis of the polarizer is 10° to 20°. The second phase difference layer preferably has Re(550) of 100nm to 190nm, and the angle between the slow axis of the second phase difference layer and the absorption axis of the polarizer is 70° to 80°. In this embodiment, either the first phase difference layer or the second phase difference layer can function as a λ/4 plate, and the other can function as a λ/2 plate. For example, when the first phase difference layer functions as a λ/2 plate and the second phase difference layer functions as a λ/4 plate, the Re(550) of the first phase difference layer is preferably 200nm to 300nm, more preferably 200nm to 270nm, more preferably 210nm to 260nm, and particularly preferably 230nm to 260nm. The Re(550) of the second phase difference layer is preferably 100nm to 200nm, more preferably 100nm to 170nm, more preferably 110nm to 150nm, and particularly preferably 110nm to 130nm.

The thickness of the first phase difference layer can be adjusted, for example, so that the desired in-plane phase difference of the λ/2 plate can be obtained. The thickness of the first phase difference layer is, for example, 2.0 μm to 4.0 μm. The thickness of the second phase difference layer can be adjusted, for example, so that the desired in-plane phase difference of the λ/4 plate can be obtained. The thickness of the second phase difference layer is, for example, 0.5 μm to 2.5 μm.

In this embodiment, the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and more preferably 12° to 16°. Furthermore, the angle formed by the slow axis of the second phase difference layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and more preferably 72° to 76°. In this embodiment, the first phase difference layer and the second phase difference layer can display an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measured light, can also display a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measured light, and can also display a flat wavelength dispersion characteristic in which the phase difference value hardly changes with the wavelength of the measured light.

At least one of the first phase difference layer and the second phase difference layer has a refractive index characteristic that shows a relationship of nx>ny=nz. In addition, "ny=nz" includes not only a case where ny and nz are completely equal, but also a case where they are substantially equal. Therefore, within the range that does not impair the effect of the present invention, sometimes ny>nz or ny<nz may be achieved. The Nz coefficient of the phase difference layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3.

In this embodiment, the liquid crystal compound used in the first phase difference layer and the second phase difference layer may be, for example, a liquid crystal compound whose liquid crystal phase is a nematic phase (nematic liquid crystal). As the liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer may be used. The liquid crystal compound may have a lyotropic or thermotropic mechanism of expression of liquid crystal properties. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

In the case where the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a cross-linking monomer. This is because the orientation state of the liquid crystal monomer can be fixed by polymerizing or cross-linking (i.e., hardening) the liquid crystal monomer. After the liquid crystal monomer is oriented, for example, if the liquid crystal monomers are polymerized or cross-linked with each other, the above-mentioned orientation state can be fixed. Here, a polymer is formed by polymerization, and a three-dimensional mesh structure is formed by cross-linking, but they are non-liquid crystal. Therefore, the phase difference layer formed, for example, will not cause the temperature change unique to the liquid crystal compound to cause a phase change into a liquid crystal phase, a glass phase, or a crystalline phase. As a result, the phase difference layer becomes a phase difference layer with extremely excellent stability that is not affected by temperature changes.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and even more preferably 60°C to 90°C.

As the above-mentioned liquid crystal monomer, any appropriate liquid crystal monomer can be used. For example, the polymerizable liquid crystal original compounds recorded in Japanese Patent Table 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171 and GB2280445 can be used. As specific examples of the above-mentioned polymerizable liquid crystal original compounds, for example, the trade name LC242 of BASF, the trade name E7 of Merck, and the trade name LC-Sillicon-CC3767 of Wacker-Chem can be cited. As the liquid crystal monomer, a nematic liquid crystal monomer is preferably used. The specific examples of the liquid crystal compound and the details of the method for forming the oriented solidified layer are as described above.

So far, the first phase difference layer has been described as functioning as a λ/2 plate and the second phase difference layer as a λ/4 plate, but the first phase difference layer may be set as a λ/4 plate and the second phase difference layer may be set as a λ/2 plate. Furthermore, the angle between the slow axis of the first phase difference layer and the absorption axis of the polarizer may be set to about 75° and the angle between the slow axis of the second phase difference layer and the absorption axis of the polarizer may be set to about 15°.

E. Image display device The polarizing plate with phase difference layer can be applied to an image display device. Therefore, an image display device including a polarizing plate with phase difference layer is also included in the embodiment of the present invention. The image display device typically includes an image display unit and a polarizing plate with phase difference layer attached to the image display unit through an adhesive layer. As representative examples of image display devices, liquid crystal display devices and electroluminescent (EL) display devices (for example, organic EL display devices, inorganic EL display devices) can be cited. In one embodiment, the image display device is bendable and preferably foldable. In the aforementioned image display device, the effect of the polarizing plate with phase difference layer of the embodiment of the present invention can become significant.

Examples The present invention is specifically described below by way of examples, but the present invention is not limited to these examples. The methods for measuring each characteristic are as follows. In addition, unless otherwise specified, the "parts" and "%" in the examples and comparative examples are based on weight.

(1) Thickness The thickness below 10μm is measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The thickness greater than 10μm is measured using a digital micrometer (manufactured by ANRITSU, product name "KC-351C").

(2) Storage elastic modulus Measured using a dynamic viscoelastic device (viscoelastic spectrometer, manufactured by Rheometric Scientific, "ARES device").

(3) Bendability The polarizing plate with phase difference layer obtained in the embodiment and the comparative example was cut into a size of 10 cm × 5 cm. The third bonding layer of the cut polarizing plate with phase difference layer was bonded to a resin film with a thickness of 20 μm (manufactured by Toyo Kogyo Co., Ltd., product name: RV-20UB), and the sample was cut into a size of 10 cm × 5 cm in such a way that the angle formed by the absorption axis of the polarizer and the long side was 135°, as a test sample. The test sample was subjected to a continuous bending test using a bending tester (manufactured by Yuasa System Equipment Co., Ltd., product name "CL09 Type D01"). FIG. 4 is a schematic diagram illustrating a method for fixing the sample during the bending test of the embodiment of the present invention. As shown in Figure 4, the resin film side of the test sample was fixed with double-sided tape to contact the fixed part of the flex tester for measurement. The bending was performed at 25°C (room temperature) with the visual side protective layer on the inside. The curvature radius of the bending was 1.5 mm, and the bending speed was 30 times/minute. The presence or absence of cracks after bending 100,000 times and 200,000 times was observed with the naked eye and evaluated according to the following criteria. ○: No cracks were confirmed in the 200,000 and 100,000 times of the flex test. △: No cracks were confirmed at 100,000 times, but cracks were confirmed at 200,000 times. ×: Cracks were confirmed in the 200,000 and 100,000 times bending tests.

[Manufacturing Example 1] Preparation of polarizer 1 As a thermoplastic resin substrate, a long amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100 μm) with a Tg of about 75°C was used. One side of the resin substrate was subjected to a corona treatment. 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") in a ratio of 9:1, and a PVA aqueous solution (coating liquid) was prepared. A laminate was prepared by applying the above-mentioned PVA aqueous solution on the corona-treated surface of the resin substrate and drying it at 60°C to form a PVA-based resin layer with a thickness of 13μm. The obtained laminate was uniaxially stretched to 2.4 times in the longitudinal direction (long side direction) between rollers with different peripheral speeds in an oven at 130°C (in-air assisted stretching treatment). Then, the laminate was immersed in an insolubilizing bath (aqueous solution of boric acid obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the polarizer was immersed for 60 seconds while adjusting the concentration in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C, so that the single transmittance (Ts) of the final polarizer became 43% (dyeing treatment). Next, it was immersed for 30 seconds in a crosslinking bath (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C (crosslinking treatment). After that, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4.0 wt%, potassium iodide 5.0 wt%) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (long side direction) between rollers with different peripheral speeds to a total stretching ratio of 5.5 times (in-water stretching treatment). After that, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). After that, it was dried in an oven maintained at 90°C and contacted with a SUS heating roller maintained at a surface temperature of 75°C for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction is 2% by the dry shrinkage treatment. According to the above operation, a polarizer with a thickness of 5.0μm is formed on the resin substrate.

[Manufacturing Example 2] Preparation of Polarizer 2 A long roll of a 30μm thick polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") was uniaxially stretched in the longitudinal direction by a roll stretching machine to 5.9 times in the longitudinal direction, and then subjected to swelling, dyeing, crosslinking, washing, and finally drying to produce a polarizer with a thickness of 12μm. Specifically, the swelling treatment was performed while being treated with 20°C pure water while being stretched to 2.2 times. Next, the dyeing treatment was performed while being treated in a 30°C aqueous solution with an iodine concentration adjusted to a weight ratio of iodine to potassium iodide of 1:7 while being stretched to 1.4 times, so that the single body transmittance of the obtained polarizer became 45.0%. Furthermore, the crosslinking treatment adopts a two-stage crosslinking treatment, and the first stage crosslinking treatment is extended to 1.2 times while being treated in an aqueous solution obtained by dissolving boric acid and potassium iodide at 40°C. The boric acid content of the aqueous solution of the first stage crosslinking treatment is set to 5.0% by weight, and the potassium iodide content is set to 3.0% by weight. The second stage crosslinking treatment is extended to 1.6 times while being treated in an aqueous solution obtained by dissolving boric acid and potassium iodide at 65°C. The boric acid content of the aqueous solution of the second stage crosslinking treatment is set to 3.7% by weight, and the potassium iodide content is set to 5.0% by weight. In addition, the washing treatment is carried out with a potassium iodide aqueous solution at 20°C. The potassium iodide content of the aqueous solution of the washing treatment is set to 3.1% by weight. Finally, the polarizer was obtained by drying at 70°C for 5 minutes.

[Production Example 3] Preparation of Adhesive A A monomer mixture containing 91.5 parts by weight of butyl acrylate, 3 parts by weight of acrylic acid, 0.5 parts by weight of 4-hydroxybutyl acrylate, and 5 parts by weight of acrylyl isoflurane was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler. Next, 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts by weight of ethyl acetate were added to 100 parts by weight of the monomer mixture, and nitrogen was introduced while slowly stirring to replace the nitrogen. The liquid temperature in the flask was maintained at about 55°C, and a polymerization reaction was carried out for 8 hours to prepare a solution of an acrylic polymer (B) with a weight average molecular weight (Mw) of 2.5 million. With respect to 100 parts by weight of the solid content of the obtained acrylic polymer (B) solution, 0.2 parts by weight of an isocyanate crosslinking agent (Coronate L manufactured by Nippon Polyurethane Industry, an adduct of trihydroxymethylpropane and toluene diisocyanate), 0.3 parts by weight of benzoyl peroxide (Nyper BMT manufactured by NOF Corporation) and 0.1 parts by weight of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM403) were mixed to prepare a solution of an acrylic adhesive composition (solid content 11%) (adhesive A).

[Production Example 4] Preparation of Adhesive B 50 parts by weight of PLACCEL FA1DDM (manufactured by Daicel Corporation), 40 parts by weight of acrylamide (ACMO: registered trademark) (manufactured by Kojin Co., Ltd.), 10 parts by weight of ARUFONUP-1190 (manufactured by Toagosei Co., Ltd.), 3 parts by weight of a photopolymerization initiator (product name "KAYACUREDETX-S", manufactured by Nippon Kayaku Co., Ltd.), and 3 parts by weight of Irgacure 907 (manufactured by BASF JAPAN Co., Ltd.) were mixed to prepare Adhesive B. The obtained Adhesive B was photocured (300 mJ/cm ² ) to obtain a cured product with an in-plane refractive index of 1.52 and a refractive index in the thickness direction of 1.52, and the average refractive index was 1.52.

[Production Example 5] Preparation of Adhesive C 1. Preparation of Acrylic Base Polymer In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler and a nitrogen inlet tube, a mixture (solid content concentration 47 mass %) containing 70 parts by weight of 2-ethylhexyl acrylate (2EHA), 20 parts by weight of n-butyl acrylate (BA), 8 parts by weight of lauryl acrylate (LA), 1 part by weight of 4-hydroxybutyl acrylate (4HBA), 0.6 parts by weight of N-vinyl-2-pyrrolidone (NVP), 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator and ethyl acetate as a solvent was stirred at 56°C in a nitrogen environment for 6 hours (polymerization reaction). Thus, a polymer solution containing an acrylic base polymer was obtained. The weight average molecular weight of the acrylic base polymer in the polymer solution is about 2 million. 2. Preparation of adhesive composition In the polymer solution, 1.5 parts by weight of the first acrylic oligomer, 0.26 parts by weight of the first crosslinking agent (trade name "Nyper BMT-40SV", diphenylformyl peroxide, manufactured by NOF Corporation), 0.02 parts by weight of the second crosslinking agent (trade name "Coronate L", trihydroxymethylpropane/toluene diisocyanate trimer adduct, manufactured by Tosoh) and 0.3 parts by weight of the silane coupling agent (trade name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed to prepare adhesive C.

[Production Example 6] Preparation of Adhesive D 1. Preparation of (meth)acrylic acid polymer A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler. And 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate relative to 100 parts by weight of the monomer mixture (solid component). After nitrogen replacement was performed by introducing nitrogen while slowly stirring, the liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was carried out for 7 hours. Afterwards, ethyl acetate was added to the obtained reaction solution to prepare a solution of a (meth)acrylic acid polymer having a weight average molecular weight of 1.6 million and a solid content concentration of 30%.

2. Preparation of acrylic adhesive composition Adhesive D was prepared by mixing 0.1 parts by weight of an isocyanate crosslinking agent (trade name: Takenate D110N, trihydroxymethyl propane diisocyanate, manufactured by Mitsui Chemicals Co., Ltd.), 0.3 parts by weight of a peroxide crosslinking agent, benzoyl peroxide (trade name: Nyper BMT, manufactured by NOF Corporation), and 0.1 parts by weight of a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) with respect to 100 parts by weight of the solid content of the obtained (meth) acrylic polymer A1 solution.

[Production Example 7] Preparation of the first phase difference layer 55 parts by weight of the compound represented by the following formula (I), 25 parts by weight of the compound represented by the following formula (II), and 20 parts by weight of the compound represented by the following formula (III) were added to 400 parts by weight of cyclopentanone (CPN), heated to 60°C, and stirred to dissolve. Thereafter, the solution of the above compounds was returned to room temperature, 3 parts by weight of Irgacure 907 (manufactured by BASF JAPAN), 0.2 parts by weight of MEGAFAC F-554 (manufactured by DIC Corporation), and 0.1 parts by weight of para-methoxyphenol (MEHQ) were added to the solution of the above compounds, and further stirred. The stirred solution was transparent and uniform. The obtained solution was filtered with a 0.20 μm membrane filter to obtain a polymerizable composition. In addition, a polyimide solution for an oriented film is applied to a glass substrate with a thickness of 0.7 mm using a spin coating method, dried at 100°C for 10 minutes, and then fired at 200°C for 60 minutes to obtain a coating. The obtained coating is rubbed using a commercially available rubbing device to form an oriented film. Next, the polymerizable composition obtained above is applied to the substrate (essentially an oriented film) by a spin coating method and dried at 100°C for 2 minutes. After the obtained coating is cooled to room temperature, it is irradiated with ultraviolet light at an intensity of 30 mW/ ^cm2 for 30 seconds using a high-pressure mercury lamp to obtain the first phase difference layer (thickness 3 μm) as an oriented solidified layer of the liquid crystal compound. The in-plane phase difference Re(550) of the first phase difference layer is 130nm. In addition, the Re(450)/Re(550) of the first phase difference layer is 0.851, showing an inverse dispersion wavelength characteristic. The first phase difference layer can function as a λ/4 plate. [Chemical formula 2] [Chemical formula 3]

[Production Example 8] Preparation of the second phase difference layer In an autoclave equipped with a stirrer, a cooling tube, a nitrogen inlet tube and a thermometer, 48 parts by weight of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical, trade name: Metolose 60SH-50), 15601 parts by weight of distilled water, 8161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxocyclobutanemethyl acrylate and 45 parts by weight of tributyl peroxypivalate as a polymerization initiator were added, and nitrogen bubbling was performed for 1 hour. The mixture was then kept at 49°C for 24 hours while stirring to perform free radical suspension polymerization. Then, the mixture was cooled to room temperature, and the resulting suspension containing polymer particles was centrifuged and separated. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure. The obtained fumarate resin was dissolved in a toluene-methyl ethyl ketone mixed solution (toluene/methyl ethyl ketone 50% by weight/50% by weight) to prepare a 20% solution. Furthermore, 5 parts by weight of tributyl trimellitate as a plasticizer was added to 100 parts by weight of the fumarate resin to prepare a dopant. As a support film, a biaxially stretched film (thickness 75 μm) of polyester (polyethylene terephthalate/isophthalate copolymer) was used. The prepared dopant was applied to the support film in such a way that the film thickness after drying became 5 μm, and dried at 140°C. The coating after drying (positive C plate) is Re(550)≒0nm, Rth(550)=-75nm.

[Example 1] The polarizer surface (the surface opposite to the resin substrate) of the laminate of the polarizer obtained in Manufacturing Example 1 and the resin substrate is bonded to an acrylic resin film (manufactured by Toyo Kogyo Co., Ltd., trade name "RV-20UB", thickness 20μm) as a protective layer through a UV-curable adhesive. Specifically, the UV-curable adhesive is applied so that the total thickness becomes 1.0μm, and a roller machine is used for bonding. Thereafter, UV rays are irradiated from the protective layer side to cure the adhesive. Then, the resin substrate is peeled off to obtain a polarizing plate having a structure of protective layer (acrylic resin film)/adhesive layer/polarizer. In addition, the polarizer of the above-mentioned polarizing plate is bonded in such a way that the angle formed by the absorption axis of the polarizer and the slow axis of the first phase difference layer is 45 degrees. The first phase difference layer and the polarizer are laminated by applying adhesive A so that the thickness after drying becomes 5μm. Then, adhesive B (thickness after curing 1μm) is applied on the second phase difference layer to obtain a laminate of protective layer (acrylic resin film)/adhesive layer/polarizer/first bonding layer/first phase difference layer/second bonding layer/second phase difference layer/support film. Then, the support film of the second phase difference layer is peeled off. After that, the support film of the second phase difference layer was peeled off and adhesive C (thickness 50μm) was applied to obtain a polarizing plate with a phase difference layer having a structure of protective layer (acrylic resin film)/adhesive layer/polarizer/first bonding layer/first phase difference layer/second bonding layer/second phase difference layer/third bonding layer. A peelable pad was layered on the third bonding layer until use. The obtained polarizing plate with a phase difference layer was subjected to the above evaluation. The results are listed in Table 1.

[Examples 2 to 6] Except that the type and thickness of the adhesive forming each bonding layer were changed to the contents listed in Table 1, the same operation as in Example 1 was performed to obtain a polarizing plate with a phase difference layer. The obtained polarizing plate with a phase difference layer was subjected to the above evaluation. The results are listed in Table 1.

[Example 7] Except that HC/TAC film is used instead of acrylic resin film as the protective layer of polarizer, a polarizing plate with phase difference layer is obtained in the same manner as Example 6. The obtained polarizing plate with phase difference layer is provided for the above evaluation. The results are shown in Table 1. In addition, the HC/TAC film is a film having a hard coating (HC) layer (thickness 7μm) formed on a cellulose triacetate (TAC) film (manufactured by KONICA MINOLTA, product name "KC2UA", thickness 25μm), and the TAC film is bonded so that the TAC film is on the polarizer side.

[Example 8] Except that HC/COP film is used instead of acrylic resin film as the protective layer of polarizer, a polarizer with phase difference layer is obtained in the same manner as Example 6. The obtained polarizer with phase difference layer is provided for the above evaluation. The results are shown in Table 1. In addition, the HC/COP film is a film having a hard coating (HC) layer (thickness 2μm) formed on a cycloolefin (COP) film (manufactured by ZEON Corporation of Japan, product name "ZF12", thickness 25μm), and the film is bonded so that the COP film is on the polarizer side.

[Example 9] Except that a polycarbonate (PC) resin film (manufactured by Mitsubishi Chemical Corporation, trade name "DURABIO", thickness 20 μm) was used instead of an acrylic resin film as the protective layer of the polarizer, a polarizing plate with a phase difference layer was obtained in the same manner as in Example 6. The obtained polarizing plate with a phase difference layer was subjected to the above evaluation. The results are listed in Table 1.

(Comparative Examples 1 to 6) Except that the type and thickness of the adhesive forming each bonding layer were changed to the contents listed in Table 1, the same operation as in Example 1 was performed to obtain a polarizing plate with a phase difference layer. The obtained polarizing plate with a phase difference layer was subjected to the above evaluation. The results are listed in Table 1.

(Comparative Example 7) Polarizer 2 was used instead of polarizer 1, and the structure of the polarizer was set to (HC/TAC film)/polarizer/adhesive layer (1μm)/TAC film (manufactured by KONICA MINOLTA, product name "KC2UA", thickness 25μm). The same operation as in Example 6 was performed to obtain a polarizer with a phase difference layer. The obtained polarizer with a phase difference layer was subjected to the above evaluation. The results are listed in Table 1.

[Table 1]

[Evaluation] As is apparent from Table 1, the polarizing plate with a phase difference layer of the embodiment of the present invention has excellent resistance to bending. FIG2 is a SEM observation photograph (magnification: 20 times) of the polarizing plate with a phase difference layer of Example 1 of the present invention after the bending test. As is also apparent from FIG2, the polarizing plate with a phase difference layer of Example 1 of the present invention has no cracks even after bending 100,000 times, and has excellent resistance to bending. FIG3 is a SEM observation photograph (magnification: 20 times) of the polarizing plate with a phase difference layer of Comparative Example 3 of the present invention after the bending test. For example, in Comparative Example 3 where the thickness of the second bonding layer is 5 μm, as shown in FIG3 , cracks are generated in the phase difference layer of the polarizing plate with the phase difference layer along the bending axis.

Industrial Applicability The polarizing plate with phase difference layer of the present invention is suitable for use in image display devices such as liquid crystal display devices, organic EL display devices and inorganic EL display devices.

10: Polarizing plate 11: Polarizer 12: Protective layer 20: 1st bonding layer 30: 1st phase difference layer 40: 2nd bonding layer 50: 2nd phase difference layer 60: 3rd bonding layer 100: Polarizing plate with phase difference layer

FIG1 is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to an embodiment of the present invention. FIG2 is a SEM observation photograph (magnification: 20 times) of the polarizing plate with a phase difference layer according to Embodiment 1 of the present invention after the deflection test. FIG3 is a SEM observation photograph (magnification: 20 times) of the polarizing plate with a phase difference layer according to Comparative Example 3 of the present invention after the deflection test. FIG4 is a schematic diagram for explaining the method of fixing the sample during the deflection test of the embodiment of the present invention.

10: Polarizing plate

11: Polarizer

12: Protective layer

20: The first layer

30: 1st phase difference layer

40: Second layer

50: Second phase difference layer

60: The third layer

100: Polarizing plate with phase difference layer

Claims (11)

A polarizing plate with a phase difference layer comprises, in order: a polarizing plate including a polarizer and a protective layer laminated on at least one side of the polarizer; a first connecting layer; a first phase difference layer; a second connecting layer; a second phase difference layer; and a third connecting layer; The total thickness of the polarizing plate with a phase difference layer is less than 90 μm; The thickness of the second connecting layer is less than 3 μm; The thickness of the first connecting layer, the thickness of the second connecting layer, and the thickness of the third connecting layer satisfy the relationship of the thickness of the second connecting layer ≤ the thickness of the first connecting layer ≤ the thickness of the third connecting layer. In the polarizing plate with a phase difference layer as claimed in claim 1, the storage elastic modulus G' of the third connecting layer at 25°C is less than 100 kPa. As in claim 1, the polarizing plate with a phase difference layer, wherein the thickness of the polarizing element is less than 10 μm. As for the polarizing plate with a phase difference layer as claimed in claim 1, the thickness of the protective layer is less than 40 μm. The polarizing plate with phase difference layer as claimed in claim 1, wherein the first phase difference layer and the second phase difference layer are oriented solidified layers of liquid crystal oriented compounds. A polarizing plate with a phase difference layer as claimed in claim 1, wherein Re(550) of the first phase difference layer is 100nm to 190nm, Re(450)/Re(550) of the first phase difference layer is greater than 0.8 and less than 1, and an angle formed by a slow axis of the first phase difference layer and an absorption axis of the polarizer is 40° to 50°. As for the polarizing plate with phase difference layer of claim 6, the refractive index characteristic of the second phase difference layer shows the relationship of nz＞nx=ny. The polarizing plate with phase difference layer as claimed in claim 1, wherein the Re(550) of the first phase difference layer is 200nm-300nm, and the angle formed by the slow axis of the first phase difference layer and the absorption axis of the polarizer is 10°-20°; The Re(550) of the second phase difference layer is 100nm-190nm, and the angle formed by the slow axis of the second phase difference layer and the absorption axis of the polarizer is 70°-80°. The polarizing plate with a phase difference layer as claimed in claim 1, wherein the storage elastic modulus G' of the first connecting layer at 25°C is 30 kPa to 140 kPa. The polarizing plate with a phase difference layer as claimed in claim 1 is used in a flexible image display device. An image display device comprises a polarizing plate with a phase difference layer as described in any one of claims 1 to 10.

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