KR20240107318A - A polarizer with a phase contrast layer and an image display device including the polarizer with a phase contrast layer - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer having excellent high temperature durability. The polarizing plate with a retardation layer of an embodiment of the present invention is composed of a polarizing plate including a polarizer with a thickness of 7 μm or more, a first retardation layer that is an orientation-fixed layer of a liquid crystal compound, and a resin film containing a polymer exhibiting negative birefringence. It includes a second phase difference layer.

Description

A polarizer with a phase contrast layer and an image display device including the polarizer with a phase contrast layer

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

In recent years, image display devices typified by liquid crystal displays and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices) are rapidly becoming popular. Polarizing plates and retardation plates are typically used in image display devices. In practical terms, a polarizing plate with a retardation layer that integrates a polarizing plate and a retardation plate is widely used (for example, patent document 1). As the demand for thinner image display devices becomes stronger, the demand for thinner polarizing plates with a retardation layer also becomes stronger. For the purpose of reducing the thickness of polarizing plates with a retardation layer, retardation plates are being thinned, and retardation plates manufactured using liquid crystal materials are being used. A thin retardation plate is prone to large dimensional shrinkage of the polarizer under high temperature conditions, and the retardation may change. Additionally, in a retardation layer formed using a liquid crystal material, the influence of dimensional shrinkage is greater, and as a result, the reflected color may change more.

Japanese Patent Publication No. 3325560

The present invention was made to solve the above-described conventional problems, and its main purpose is to provide a polarizing plate with a retardation layer in which in-plane unevenness of reflected color is suppressed and excellent high-temperature durability.

The polarizing plate with a retardation layer of an embodiment of the present invention includes a polarizing plate including a polarizer with a thickness of 7 μm or more, a first retardation layer that is an orientation-fixed layer of a liquid crystal compound, and a resin containing a polymer exhibiting negative birefringence. It includes a second retardation layer composed of a film.

In one embodiment, the second retardation layer is adjacent to the first retardation layer.

In one embodiment, the second retardation layer is a positive C plate.

In one embodiment, the thickness of the second retardation layer is 1 μm to 30 μm.

In one embodiment, the polymer exhibiting negative birefringence is at least one selected from the group consisting of acrylic resin, styrene-based resin, and maleimide-based resin.

In one embodiment, the in-plane retardation of the first retardation layer is 100nm<Re(550)<160nm, and Re(450)/Re(550)<1, and Re(650)/Re(550)>1. is satisfied.

In one embodiment, the angle between the slow axis of the first retardation layer and the absorption axis of the polarizer is 40° to 50°.

In one embodiment, the first retardation layer has a laminate structure of an orientation-fixed layer of a liquid crystal compound (A) and an orientation-fixed layer of a liquid crystal compound (B), and the orientation-fixed layer (A) is formed as a λ/2 plate. function, and the orientation-fixed layer (B) functions as a λ/4 plate.

In one embodiment, the angle between the slow axis of the orientation-fixed layer (A) of the liquid crystal compound and the absorption axis of the polarizer is 70° to 80°, and the slow axis of the orientation-fixed layer (B) of the liquid crystal compound is 70° to 80°. The angle formed by the absorption axis of the polarizer is 10° to 20°.

In another aspect of the present invention, an image display device is provided. This image display device includes the polarizing plate with the retardation layer.

According to an embodiment of the present invention, it is possible to provide a polarizing plate with a retardation layer in which in-plane unevenness of reflected color is suppressed and excellent high-temperature durability. According to the embodiment of the present invention, even if it is a polarizing plate with a retardation layer including a retardation layer that is a liquid crystal alignment solidification layer, the phase difference change of the polarizing plate in a high temperature environment is suppressed. Therefore, changes in reflected color can also be suppressed. As a result, in-plane unevenness of the reflected color is suppressed, and a polarizing plate with a retardation layer having excellent high-temperature durability can be provided.

1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention.

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 specification are as follows.

(1) Refractive index (nx, ny, nz)

'nx' is the refractive index in the direction where the in-plane refractive index is maximum (i.e., slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., fast axis direction), and 'nz' is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane phase difference measured with light with a wavelength of λ nm at 23°C. For example, 'Re(550)' is the in-plane phase difference measured with light with a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is d(nm).

(3) Phase difference in the thickness direction (Rth)

'Rth(λ)' is the phase difference in the thickness direction measured with light with a wavelength of λ nm at 23°C. For example, 'Rth(550)' is the phase difference in the thickness direction measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d (nm).

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) angle

When an angle is mentioned herein, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, '45°' means ±45°.

A. Overall composition of polarizer with phase contrast layer

1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer in the illustrated example includes a polarizing plate 10, a first retardation layer 20, and a second retardation layer 30 in this order from the viewer's side. The polarizing plate 10 typically includes a polarizer 11 and protective layers 12 and 13 disposed on both sides of the polarizer 11. The protective layer 13 may be omitted. Each member constituting the polarizing plate with a retardation layer may be laminated via any suitable adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. The first phase difference layer 20 is an alignment-fixed layer of a liquid crystal compound (hereinafter, it may simply be referred to as a liquid-crystal alignment-fixed layer). The second retardation layer 30 is made of a resin film containing a polymer that exhibits negative birefringence. In the illustrated example, the first phase difference layer 20 is a single layer. By including a first retardation layer 20, which is a liquid crystal alignment solidification layer, and a second retardation layer 30 composed of a resin film containing a polymer exhibiting negative birefringence, in-plane unevenness of reflected color is suppressed, and excellent high temperature durability is achieved. A polarizing plate with a retardation layer can be provided. The first retardation layer, which is a liquid crystal alignment solidification layer, is easily affected by shrinkage of the polarizer in a high temperature environment, and the retardation may change. Therefore, the reflection color of the polarizing plate with a retardation layer may change, and in-plane unevenness of the reflection color may occur. By including a second retardation layer composed of a resin film containing a polymer exhibiting negative birefringence, the influence of dimensional shrinkage of the polarizer on the first retardation layer can be alleviated. As a result, the phase difference change of the first phase difference layer can be suppressed. In addition, by being composed of a resin film containing a polymer exhibiting negative birefringence, the second retardation layer can have a small change in retardation due to dimensional shrinkage of the polarizer in a high temperature environment. Therefore, the phase difference change in the polarizing plate with a retardation layer in a high temperature environment can be suppressed, and in-plane reflection color unevenness can be further suppressed. Preferably, the first phase difference layer 20 and the second phase difference layer 30 are adjacent to each other. By adjacent to the first retardation layer, which is a liquid crystal alignment solidification layer, and the second retardation layer composed of a resin film, in-plane unevenness of the reflected color is further suppressed, and a polarizing plate with a retardation layer having excellent high temperature durability can be provided. In this specification, 'adjacent' includes not only directly neighboring but also neighboring through any adhesive layer. In this specification, the term 'liquid crystal alignment solidification layer' refers to a layer in which a liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. In addition, the 'alignment solidification layer' is a concept that includes an alignment hardening layer obtained by curing a liquid crystal monomer, as will be described later.

In the illustrated example, the second retardation layer 30 is laminated on the side of the first retardation layer 20 that is not in contact with the polarizing plate 10, but the second retardation layer 30 is laminated on the polarizing plate 10 and the first retardation plate 10. It may be arranged between the layers 20.

Figure 2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention. The polarizing plate 101 with a retardation layer in the illustrated example includes a polarizing plate 10, a first retardation layer 20 that is a liquid crystal alignment solidification layer, and a second retardation layer 30 composed of a resin film containing a polymer exhibiting negative birefringence. ) are included in this order from the poet's side. In the illustrated example, the first phase difference layer 20 has a laminated structure of a liquid crystal alignment solidification layer (A) 21 and a liquid crystal alignment solidification layer (B) 22. Even when a liquid crystal alignment solidification layer having a laminated structure is used as the first retardation layer 20, in-plane unevenness of the reflected color is suppressed, and a polarizing plate with a retardation layer having excellent high-temperature durability can be provided. In the illustrated example, the liquid crystal alignment solidification layer (B) 22 and the second retardation layer 30 are arranged adjacent to each other, but the second retardation layer 30 is adjacent to the polarizing plate 10 and the liquid crystal alignment solidification layer (A) ( 21) may be placed in between.

In one embodiment, the polarizers 100 and 101 with a retardation layer have an adhesive layer provided on the outermost layer (e.g., the side on which the first retardation layer 20 of the second retardation layer 30 in the illustrated example is not laminated). , it can be attached to an image display device (substantially an image display cell). In practical terms, it is preferable that a release liner is temporarily attached to the surface of the pressure-sensitive adhesive layer until the polarizing plate is provided for use. By temporarily attaching the release liner, the adhesive layer can be appropriately protected.

Polarizer with phase contrast layer. A phase difference layer (not shown) different from the first phase difference layer 20 and the second phase difference layer 30 may be further provided. The other phase difference layer is an arbitrary layer provided as needed and may be omitted. The optical properties (e.g., refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the other retardation layer may be appropriately set depending on the purpose.

In the polarizing plate with a retardation layer, the ratio of the thickness of the polarizer to the thickness of the first retardation layer is, for example, the thickness of the polarizer/thickness of the first retardation layer is 0.5 to 7, preferably 1 to 6, and more preferably 2. It is ~5. According to an embodiment of the present invention, even in such a polarizing plate with a retardation layer, the change in phase difference due to dimensional shrinkage in a high temperature environment can be suppressed, and the change in reflected color can also be suppressed.

The total thickness of the polarizing plate with a retardation layer is preferably 40 μm to 120 μm, more preferably 40 μm to 110 μm, and even more preferably 50 μm to 100 μm. A polarizing plate with a retardation layer including a polarizing plate having a certain thickness may have this thickness. In such a polarizing plate with a retardation layer, the influence of dimensional shrinkage of the polarizing plate in a high-temperature environment tends to increase. According to an embodiment of the present invention, even if it is a polarizing plate with a retardation layer having the above thickness, the change in phase difference due to dimensional shrinkage in a high temperature environment can be suppressed, and the change in reflected color can also be suppressed. In addition, the total thickness of the polarizer with a retardation layer refers to the sum of the thicknesses of the polarizer, the retardation layer (if another retardation layer exists, the retardation layer and the other retardation layer), and the adhesive layer for stacking them (i.e., with the retardation layer attached) The total thickness of the polarizing plate does not include the thickness of the adhesive layer provided as the outermost layer and the release liner that may be temporarily adhered to its surface).

Hereinafter, the components of the polarizing plate with a retardation layer will be described in more detail.

B. Polarizer

B-1. polarizer

The polarizer is typically comprised of a polyvinyl alcohol (PVA)-based resin film containing a dichroic substance. As described above, the thickness of the polarizer is 7 μm or more, for example, 8 μm or more, for example, 10 μm or more, for example, 12 μm or more, and for example, 15 μm or more. When the thickness of the polarizer is large, the dimensional shrinkage of the polarizer with a retardation layer tends to increase, and the retardation change may become more noticeable. In the embodiment of the present invention, even when using a polarizer of the above-mentioned thickness, high-temperature durability is excellent and phase difference change due to dimensional shrinkage can be suppressed. As a result, in-plane reflection color unevenness of the polarizer with a retardation layer can be suppressed. The thickness of the polarizer is, for example, 30 μm or less.

The boric acid content of the polarizer is preferably 20% by weight or less, more preferably 5% by weight to 20% by weight, and even more preferably 10% by weight to 18% by weight. If the boric acid content of the polarizer is within this range, a polarizing plate with a retardation layer excellent in high temperature durability can be provided. If the boric acid content is less than 5% by weight, there is a risk that the polarizer may be polyenized and durability may be reduced. According to an embodiment of the present invention, even when placed in a high-temperature environment, a change in phase difference due to dimensional shrinkage of the polarizing plate can be suppressed, and a change in reflected color can also be suppressed. As a result, it is possible to provide a polarizing plate with a retardation layer having excellent reflection color. The boric acid content of the polarizer can be adjusted, for example, by adjusting the boric acid content in the aqueous solution used in each of the following processes. The boric acid content can be calculated as the amount of boric acid contained in the polarizer per unit weight using the following formula, for example, from a neutralization method.

The iodine content of the polarizer is preferably 2% by weight or more, and more preferably 2% by weight to 10% by weight. If the iodine content of the polarizer is in this range, the synergistic effect with the boric acid content described above maintains the ease of curl adjustment during bonding, and further suppresses curl during heating, while Appearance durability can be improved. In this specification, 'iodine content' means the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, among polarizers, iodine exists in the form of iodine ions (I ^- ), iodine molecules (I ₂ ), polyiodine ions (I ₃ ^- , I ₅ ^- ), etc., and the iodine content in this specification is It refers to the amount of iodine including all of these forms. Iodine content can be calculated by, for example, a calibration curve method of fluorescence X-ray analysis. In addition, the polyiodine ion exists in the polarizer in the form of a PVA-iodine complex. By forming such a complex, absorption dichroism can be expressed in the visible light wavelength range. Specifically, the complex of PVA and triiodide ions (PVA·I ₃ ^- ) has an absorption peak around 470 nm, and the complex of PVA and peniodide ions (PVA·I ₅ ^- ) has an absorption peak around 600 nm. have As a result, polyiodine ions can absorb light in a wide range of visible light depending on their shape. Meanwhile, iodine ions (I ^- ) have an absorption peak around 230 nm and are not substantially involved in the absorption of visible light. Therefore, polyiodine ions present in a complex with PVA may be mainly involved in the absorption performance of the polarizer.

The polarizer preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single transmittance (Ts) of the polarizer is preferably 40% to 48%, and more preferably 41% to 46%. The polarization degree (P) of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more. The single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction. The degree of polarization is typically measured using an ultraviolet-visible spectrophotometer, and can be obtained by the following equation based on the parallel transmittance (Tp) and orthogonal transmittance (Tc) with visibility correction.

Polarization degree (%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

The polarizer can be manufactured by any suitable method. For example, various treatments such as swelling treatment, stretching treatment, dyeing treatment with dichroic substances such as iodine, cross-linking treatment, washing treatment, and drying treatment are performed on any suitable resin film such as polyvinyl alcohol (PVA)-based resin film. It can be manufactured by doing this.

B-2. protective layer

The protective layers 12 and 13 are formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that become the main component of the film include cellulose-based resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polyester. Transparent resins such as sulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based resins can be mentioned. Additionally, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. In addition to these, for example, glassy polymers such as siloxane polymers can also be mentioned. Additionally, the polymer film described in Japanese Patent Application Publication No. 2001-343529 (WO01/37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, isobutene and A resin composition containing an alternating copolymer containing N-methylmaleimide and an acrylonitrile/styrene copolymer can be mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition.

The polarizing plate with a retardation layer is typically placed on the viewer's side of the image display device, and the protective layer 12 is typically placed on its viewer's side. Accordingly, the protective layer 12 may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as necessary.

The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. In addition, when surface treatment is performed, the thickness of the outer protective layer (protective layer 12) is a thickness including the thickness of the surface treatment layer.

C. First phase contrast layer

The first phase difference layer 20 is an alignment-fixed layer of a liquid crystal compound. By using a liquid crystal compound, an in-plane retardation equivalent to that of a resin film can be achieved with a thickness significantly thinner than that of a resin film. In addition, in the liquid crystal alignment-fixed layer, the change in phase difference due to dimensional shrinkage in a high-temperature environment of the polarizing plate with a retardation layer may become more noticeable. In an embodiment of the present invention, a polarizing plate with a retardation layer excellent in high-temperature durability can be provided even when a retardation layer that is an orientation-fixed layer of a liquid crystal compound is adopted. The first phase difference layer may be a single layer or a laminate of two or more layers. The first retardation layer is typically provided to provide anti-reflection properties to the polarizer.

C-1. The first phase contrast layer is a single layer.

When the first phase difference layer 20 is a single layer, the first phase difference layer, which is a single layer, may function as a λ/4 plate. The in-plane retardation Re(550) of the first retardation layer is preferably greater than 100 nm and less than 160 nm, more preferably 110 nm to 155 nm, and still more preferably 130 nm to less than 150 nm.

The Nz coefficient of the first phase difference layer, which is a single layer, is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. By satisfying this relationship, when the obtained polarizing plate with a retardation layer is used in an image display device, very excellent reflected color can be achieved.

The thickness of the first retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 7 μm, and still more preferably 1 μm to 5 μm.

The first retardation layer preferably exhibits inverse dispersion wavelength characteristics. In this case, Re(550)/Re(650) preferably exceeds 1, more preferably exceeds 1 and is 1.2 or less, and even more preferably is 1.01 to 1.15. Additionally, Re(450)/Re(550) of the first phase difference layer is preferably less than 1, more preferably less than 0.95, and even more preferably less than 0.90. Re(450)/Re(550) is, for example, 0.8 or more. With this configuration, very excellent anti-reflection properties can be achieved.

The angle formed by the slow axis of the first retardation layer 20 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. It is °. If the angle is in this range, a polarizing plate with a phase difference layer having very excellent circular polarization characteristics (as a result, very excellent anti-reflection characteristics) can be obtained by using the phase difference layer as a λ/4 plate as described above.

As described above, the first phase difference layer 20 is an alignment-fixed layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to a non-liquid crystal material, so the thickness of the retardation layer for obtaining the desired in-plane retardation can be significantly reduced. As a result, further thinning of the polarizing plate with a retardation layer can be realized.

The retardation layer, which is an alignment solidification layer of the liquid crystal compound, may be formed using a composition containing a polymerizable liquid crystal compound. In this specification, 'polymerizable liquid crystal compound included in the composition' refers to a compound that has a polymerizable group and has liquid crystallinity. The polymerizable group refers to a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in the polymerization reaction by active radicals or acids generated from the photopolymerization initiator.

The expression of liquid crystallinity may be thermotropic or lyotropic. Additionally, the composition of the liquid crystal phase may be nematic liquid crystal or smectic liquid crystal. From the viewpoint of ease of manufacture, thermotropic nematic liquid crystal is preferable.

In one embodiment, the retardation layer, which is 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)

L ¹ and L ² each independently represent a monovalent organic group, and at least one of L ¹ and L ² represents a polymerizable group. The monovalent organic group includes any suitable group. The polymerizable group represented by at least one of L ¹ and L ² includes a radical polymerizable group (group capable of radical polymerization). As the radical polymerizable group, any suitable radical polymerizable group can be used. Preferably it is an acryloyl group or a methacryloyl group. The acryloyl group is preferable because the polymerization rate is fast and from the viewpoint of improving productivity. A methacryloyl group can similarly be used as a polymerizable group in highly birefringent liquid crystals.

SP ¹ and SP ² each independently represent a single bond, a linear or branched alkylene group, or one or more of -CH ₂ - constituting a linear or branched alkylene group having 1 to 14 carbon atoms - It represents a divalent linking group substituted with O-. Examples of the linear or branched alkylene group having 1 to 14 carbon atoms include preferably methylene group, ethylene group, propylene group, butylene group, pentylene group, and hexylene group.

A ¹ and A ² each independently represent an alicyclic hydrocarbon group or an aromatic ring substituent. A ¹ and A ² are preferably an aromatic ring substituent having 6 or more carbon atoms or a cycloalkylene 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 are single bonds, -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 -. However, at least one of D ¹ , D ² , D ³ and D ⁴ represents -O-CO-. Among these, it is preferable that D ³ is -O-CO-, and it is more preferable that D ³ and D ⁴ are -O-CO-. D ¹ and D ² are preferably a single bond. 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.

G ¹ and G ² each independently represent a single bond or an alicyclic hydrocarbon group. Specifically, G ¹ and G ² may represent an unsubstituted or substituted divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms. Additionally, one or more of -CH ₂ - constituting the alicyclic hydrocarbon group may be substituted with -O-, -S-, or -NH-. G ¹ and G ² preferably represent a single bond.

Ar represents an aromatic hydrocarbon ring or an aromatic heterocycle. Ar represents, for example, an aromatic ring selected from the group consisting of groups represented by the following formulas (Ar-1) to (Ar-6). In addition, in the following formulas (Ar-1) to (Ar-6), *1 represents the bonding position with D ¹ and *2 represents the bonding position with D ² .

In formula (Ar-1), Q ¹ represents N or CH, and Q ² represents -S-, -O-, or -N(R ⁵ )-. R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In formulas (Ar-1) to (Ar-6), Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent alicyclic group having 3 to 20 carbon atoms. It represents a hydrocarbon group, a monovalent aromatic hydrocarbon 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, and Z ¹ and Z ² may be bonded to each other to form a ring. The ring may be any of alicyclic, heterocyclic, and aromatic rings, and is preferably an aromatic ring. The ring formed may be substituted with a substituent.

In formulas (Ar-2) and (Ar-3), A ³ and A ⁴ each independently represent a group selected from the group consisting of -O-, -N(R ⁹ )-, -S-, and -CO-. and R ⁹ represents a hydrogen atom or a substituent. Examples of the substituent represented by R ⁹ include the same substituents that Y ¹ in the above formula (Ar-1) may have.

In the formula (Ar-2), Examples of non-metallic atoms of Groups 14 to 16 represented by X include oxygen atoms, sulfur atoms, unsubstituted or substituted nitrogen atoms, and unsubstituted or substituted carbon atoms. Examples of the substituent include the same substituents that Y ¹ in the formula (Ar-1) may have.

In formula (Ar-3), D ⁵ and D ⁶ are each independently 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 - . R ¹ , R ² , R ³ and R ⁴ are as described above.

In formula (Ar-3), SP ³ and SP ⁴ are each independently a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a linear or branched alkylene group having 1 to 12 carbon atoms. One or more of -CH ₂ - constituting the group represents a divalent linking group substituted with -O-, -S-, -NH-, -N(Q)-, or -CO-, and Q represents a polymerizable group. indicates.

In (Ar-3), L ³ and L ⁴ each independently represent a monovalent organic group, and at least one of L ³ and L ⁴ and L ¹ and L ² in the formula (1) above represents a polymerizable group.

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

In formulas (Ar-4) to (Ar-6), Q ³ represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms which may be unsubstituted or have a substituent. In formulas (Ar-4) to (Ar-6), Q ³ preferably represents a hydrogen atom.

Among such Ar, the group (atomic group) represented by the above formula (Ar-4) or the above formula (Ar-6) is preferably used.

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

The composition comprising the liquid crystal compound preferably includes a polymerization initiator. As a polymerization initiator, any suitable polymerization agent is used. Preferably, it is a photopolymerization initiator capable of initiating a polymerization reaction by irradiating ultraviolet rays. Photopolymerization initiators include, for example, α-carbonyl compounds (described in the specifications of U.S. Patent No. 2367661 and U.S. Patent No. 2367670), acyloin ethers (described in the specification of U.S. Patent No. 2448828), and α-hydrocarbon substituted aromatic acyloin compounds. (described in the specification of US Patent No. 2722512), polynuclear quinone compounds (described in the specification of US Patent No. 3046127, US Patent No. 2951758), combination of triarylimidazole dimer and p-aminophenyl ketone (described in the specification of US Patent No. 3549367) description), oxadiazole compounds (described in the specification of U.S. Patent No. 4212970), and acylphosphine oxide compounds (Japanese Patent Publication No. 63-40799, Japanese Patent Publication No. 5-29234, Japanese Patent Publication No. 10) -95788, described in Japanese Patent Publication No. 10-29997). The description in this publication is incorporated herein by reference. Only one type of polymerization initiator may be used, or two or more types may be used in combination.

The composition containing the liquid crystal compound preferably contains a solvent from the viewpoint of workability in forming the retardation layer. As the solvent, any suitable solvent can be used, and an organic solvent is preferably used.

The composition comprising the liquid crystal compound further comprises any other suitable components. Examples include antioxidants such as phenolic antioxidants, liquid crystal compounds other than those mentioned above, leveling agents, surfactants, tilt angle control agents, orientation aids, plasticizers, and crosslinking agents.

The liquid crystal alignment solidification layer performs an orientation treatment on the surface of a predetermined substrate, applies a composition (coating liquid) containing a liquid crystal compound to the surface, orients the liquid crystal compound in a direction corresponding to the orientation treatment, and maintains the orientation state. It can be formed by fixing . In one embodiment, the substrate is any suitable resin film, and the liquid crystal alignment solidification layer formed on the substrate can be transferred to the surface of the polarizing plate.

As the orientation treatment, any appropriate orientation treatment may be employed. Specifically, mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment may be mentioned. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. As for the treatment conditions for various orientation treatments, any appropriate conditions may be adopted depending on the purpose.

The alignment of the liquid crystal compound is performed by treatment at a temperature that exhibits a liquid crystal phase depending on the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned in accordance with the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the aligned liquid crystal compound to polymerization treatment or crosslinking treatment as described above.

Details of the method for forming the orientation solidification layer are described in Japanese Patent Application Laid-Open No. 2006-163343. The description in this publication is incorporated herein by reference.

C-2. First phase contrast layer having a laminated structure

In one embodiment, the first retardation layer has a laminate structure of an orientation-fixed layer of a liquid crystal compound (A) and an orientation-fixed layer of a liquid crystal compound (B). When the first phase difference layer has a laminated structure, one of the liquid crystal alignment solidification layer (A) and the liquid crystal alignment solidification layer (B) may function as a λ/4 plate, and the other may function as a λ/2 plate. . For example, when the liquid crystal alignment solidification layer (A) functions as a λ/2 plate and the liquid crystal alignment solidification layer (B) functions as a λ/4 plate, Re(550) of the liquid crystal alignment layer (A) is preferably is 200 nm to 300 nm, more preferably 200 nm to 270 nm, further preferably 210 nm to 260 nm, and particularly preferably 230 nm to 260 nm. Re(550) of the liquid crystal alignment solidification layer (B) is preferably 100 nm to 200 nm, more preferably 100 nm to 170 nm, further preferably 110 nm to 150 nm, and particularly preferably 110 nm to 130 nm.

The thickness of layer A can be adjusted to obtain a desired in-plane retardation, for example, of a λ/2 plate. The thickness of layer A is, for example, 2.0 μm to 4.0 μm. The thickness of layer B can be adjusted to obtain the desired in-plane retardation of, for example, a λ/4 plate. The thickness of layer B is, for example, 0.5 μm to 2.5 μm. In this embodiment, the angle formed by the slow axis of layer A and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and still more preferably 12° to 16°. . Additionally, the angle formed between the slow axis of layer B and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 72° to 76°. When the first phase difference layer has a laminated structure, each layer (e.g., A layer and B layer) may exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases depending on the wavelength of the measurement light, and the phase difference value may vary depending on the wavelength of the measurement light. It may exhibit positive wavelength dispersion characteristics that become smaller, or it may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes depending on the wavelength of the measurement light.

The refractive index characteristic of the retardation layer (at least one layer if it has a laminated structure) typically shows the relationship nx>ny=nz. Additionally, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny>nz or ny<nz occurs within a range that does not impair the effect of the present invention. 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, examples of the liquid crystal compound used in the first retardation layer include a liquid crystal compound (nematic liquid crystal) whose liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The mechanism for expressing liquid crystallinity of the liquid crystal compound may be lyotropic or thermotropic. The liquid crystal polymer and liquid crystal monomer may be used individually or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, by polymerizing or crosslinking the liquid crystal monomers, the alignment state can be fixed. Here, polymers are formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the formed phase contrast layer is unlikely to transition into a liquid crystal phase, a glass phase, or a crystal phase due to temperature changes characteristic of liquid crystalline compounds, for example. As a result, the phase difference layer becomes a phase difference layer that is not affected by temperature changes and has extremely excellent stability.

The temperature range in which a 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 liquid crystal monomer, any suitable liquid crystal monomer may be employed. For example, Japanese Patent Application Publication No. 2002-533742 (WO00/37585), EP 358208 (US 5211877), EP 66137 (US 4388453), WO 93/22397, EP 0261712, DE 19504224, DE 4408171 and GB 22 Polymerization described in 80445, etc. Mesogenic compounds, etc. can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name 'LC242', Merck's trade name 'E7', and Wacker-Chem's trade name 'LC-Sillicon-CC3767'. I can hear it. As the liquid crystal monomer, a nematic liquid crystal monomer is preferable. Specific examples of the liquid crystal compound and details of the method for forming the alignment solidification layer are as described above.

Although the case where the liquid crystal alignment solidification layer (A) functions as a λ/2 plate and the liquid crystal alignment layer (B) functions as a λ/4 plate has been described, the liquid crystal alignment solidification layer (A) functions as a λ/4 plate. , the liquid crystal alignment solidification layer (B) may be a λ/2 plate. In addition, the angle between the slow axis of the liquid crystal alignment solidification layer (A) and the absorption axis of the polarizer is set to about 75°, and the angle between the slow axis of the liquid crystal alignment solidification layer (B) and the absorption axis of the polarizer is set to about 15°. You can do it.

D. Second phase contrast layer

The second retardation layer 30 is preferably made of a resin film containing a polymer exhibiting negative birefringence. Here, 'exhibiting negative birefringence' means that when a polymer is oriented by stretching, etc., the refractive index in the stretching direction becomes relatively small. In other words, it means that the refractive index in the direction orthogonal to the stretching direction increases. By being composed of a resin film containing a polymer exhibiting negative birefringence, the second retardation layer can have a small change in retardation due to dimensional shrinkage of the polarizing plate. Therefore, the phase difference change in the polarizing plate with a retardation layer in a high temperature environment can be suppressed, and in-plane reflection color unevenness can be suppressed.

The second retardation layer is preferably a so-called positive C plate whose refractive index characteristics exhibit the relationship nz>nx=ny. By using a positive C plate as the second phase difference layer, reflection in the oblique direction can be prevented well, and wide viewing angle of the anti-reflection function becomes possible. The phase difference Rth (550) in the thickness direction of the second phase difference layer is preferably -10 nm to -200 nm, more preferably -20 nm to -180 nm, further preferably -30 nm to -160 nm, especially preferably -40 nm to -40 nm. -140nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. That is, the in-plane phase difference Re(550) of the second phase difference layer may be less than 10 nm.

The thickness of the second phase difference layer 30 may be set to any appropriate thickness. The thickness of the second phase difference layer is preferably 1 μm to 30 μm, more preferably 2 μm to 20 μm, and even more preferably 3 μm to 8 μm.

Examples of polymers that exhibit negative birefringence include polymers in which chemical bonds or functional groups with high polarization anisotropy, such as aromatic rings and/or carbonyl groups, are introduced into the side chains. Specifically, acrylic resin, styrene-based resin, maleimide-based resin, etc. can be mentioned. Preferably, at least one polymer selected from the group consisting of acrylic resin, styrene resin, and maleimide resin can be used, and more preferably, styrene resin can be used. Only one type of polymer showing negative birefringence may be used, or two or more types may be used in combination.

Acrylic resin can be obtained, for example, by addition polymerizing an acrylate monomer. Examples of acrylic resins include polymethyl methacrylate (PMMA), polybutyl methacrylate, and polycyclohexyl methacrylate.

Styrene-based resin can be obtained, for example, by addition polymerizing a styrene-based monomer. As styrene-based monomers, for example, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, 2 , 5-dichlorostyrene, p-t-butylstyrene, etc.

Maleimide-based resin can be obtained, for example, by addition polymerizing a maleimide-based monomer. As maleimide monomers, for example, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N- (2-propylphenyl)maleimide, N-(2-isopropylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-dipropylphenyl)maleimide, N- (2,6-diisopropylphenyl)maleimide, N-(2-methyl-6-ethylphenyl)maleimide, N-(2-chlorophenyl)maleimide, N-(2,6-dichlorophenyl)maleimide Mead, N-(2-bromophenyl)maleimide, N-(2,6-dibromophenyl)maleimide, N-(2-biphenyl)maleimide, N-(2-cyanophenyl)maleimide Mead, etc. may be mentioned. Maleimide-based monomers can be obtained from, for example, Tokyo Kasei Kogyo Co., Ltd.

In addition polymerization, the birefringence characteristics of the resulting resin can also be controlled after polymerization by substituting the side chain, maleimidation, grafting, etc.

The polymer showing negative birefringence may be copolymerized with other monomers. By copolymerizing other monomers, brittleness, moldability, and heat resistance can be improved. Examples of the other monomers include olefins such as ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, and 1-hexene; acrylonitrile; (meth)acrylates such as methyl acrylate and methyl methacrylate; maleic anhydride; and vinyl esters such as vinyl acetate.

When the polymer showing negative birefringence is a copolymer of the styrene-based monomer and the other monomer, the mixing ratio of the styrene-based monomer is preferably 50 mol% to 80 mol%. When the polymer showing the negative birefringence is a copolymer of the maleimide monomer and the other monomer, the mixing ratio of the maleimide monomer is preferably 2 mol% to 50 mol%. By mixing in this range, a polymer film with excellent toughness and molding processability can be obtained.

The polymer showing negative birefringence is preferably styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-(meth)acrylate copolymer, styrene-maleimide copolymer, and vinyl ester-maleimide. Copolymers, olefin-maleimide copolymers, etc. are used. These can be used individually or in combination of two or more types. These polymers exhibit high negative birefringence and may also have excellent heat resistance. These polymers can be obtained from, for example, Nova Chemical Japan or Arakawa Chemical Industry Co., Ltd.

As the polymer exhibiting negative birefringence, a polymer having a repeating unit represented by the following general formula (II) is preferably also used. Such polymers exhibit higher negative birefringence and can also have excellent heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using an N-phenyl substituted maleimide in which a phenyl group having a substituent at least in the ortho position is introduced as the N substituent of the maleimide monomer as the starting material.

In the general formula (II), R ₁ to R ₅ each independently represent a hydrogen atom, a halogen atom, carboxylic acid, carboxylic acid ester, hydroxyl group, nitro group, or a straight-chain or branched alkyl group or alkoxy group having 1 to 8 carbon atoms ( However, R ₁ and R ₅ are not hydrogen atoms at the same time), R ₆ and R ₇ represent a hydrogen atom or a straight-chain or branched alkyl group or alkoxy group having 1 to 8 carbon atoms, and n represents an integer of 2 or more.

The polymer showing the negative birefringence is not limited to the above, and for example, cyclic olefin-based copolymers such as those disclosed in Japanese Patent Application Laid-Open No. 2005-350544, etc. can also be used. Additionally, a composition containing a polymer and inorganic fine particles as disclosed in Japanese Patent Application Laid-Open No. 2005-156862, Japanese Patent Application Publication No. 2005-227427, etc. can also be suitably used. Additionally, they can also be used after being modified by copolymerization, branching, crosslinking, molecular end modification (or encapsulation), and stereoregular modification.

The resin composition forming the second phase difference layer may further contain any appropriate additives as needed. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, thickeners, etc. The type and content of additives can be appropriately set depending on the purpose. The content of the additive is typically about 3 to 10 parts by weight based on 100 parts by weight of the total solid content of the resin composition. If the additive content is excessively high, the transparency of the polymer film may be impaired or the additive may ooze out from the surface of the polymer film.

As a method of forming the second retardation layer, any suitable method can be adopted. Examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, and solvent casting. Among these, extrusion molding and solvent casting are preferably used. This is because a retardation film with high smoothness and good optical uniformity can be obtained. Specifically, the extrusion molding method is a method of heating and melting a resin composition containing the thermoplastic resin, plasticizer, additives, etc., extruding this into a thin film on the surface of a casting roll using a T die, etc., and cooling to form a film. . In the solvent casting method, a thick solution (dope) obtained by dissolving the resin composition in a solvent is defoamed, and the solvent is spread uniformly into a thin film on the surface of a metallic endless belt, rotating drum, or plastic substrate. This is a method of forming a film by evaporating. Additionally, molding conditions can be appropriately set depending on the composition or type of the resin used, molding processing method, etc.

E. Adhesive layer

As the adhesive constituting the adhesive layer provided as the outermost layer (the adhesive layer between the adhesive layer and the image display device), any suitable adhesive can be used. Examples of adhesives include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these adhesives, those that are excellent in optical transparency, exhibit appropriate adhesive properties of wettability, cohesiveness, and adhesiveness, and are excellent in weather resistance, heat resistance, etc., are preferably used. An acrylic adhesive is preferably used as it exhibits these characteristics.

F. Image display device

The polarizing plate with a retardation layer described in items A to E above can be applied to an image display device. Accordingly, embodiments of the present invention also include an image display device using such a polarizing plate with a retardation layer. Representative examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices). An image display device according to an embodiment of the present invention is equipped on its viewer side with the polarizing plate with a retardation layer described in the above items A to E. The polarizing plate with a retardation layer is laminated so that the retardation layer is on the image display cell (eg, liquid crystal cell, organic EL cell, inorganic EL cell) side (so that the polarizer is on the viewing side).

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement method for each characteristic is as follows. Additionally, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on weight.

(1) Thickness

The thickness of 10㎛ or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics, product name 'MCPD-3000'). Thickness exceeding 10㎛ was measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

(2) Reflective color staining

The polarizing plate with a retardation layer obtained in the examples and comparative examples was cut to a length of 60 mm and a width of 130 mm, and was used as a sample. The part of the sample measuring 30 mm long and 25 mm wide was designated as measurement position A, the part measuring 30 mm long and 65 mm wide was designated as measurement position B, and the part measuring 30 mm long and 105 mm wide was designated as measurement position C.

Next, the adhesive layer of the polarizing plate with a retardation layer was laminated by bonding it to a glass plate (80 mm x 150 mm) with a thickness of 0.5 mm. After that, the polarizing plate with a retardation layer bonded to the glass plate was left under conditions of 80°C for 500 hours. The color a* value and color b* value at measurement positions A, B, and C were measured using a spectrophotometer (manufactured by Konica Minolta, product name: CM-26d). Plot the color a* value and color b* value of each measurement position, compare the results of measurement position A and measurement position B, and the results of measurement position B and measurement position C, respectively. If the color difference is large (between plots), The value of the (larger distance) side was taken as the color stain of each sample.

(3) Phase difference change

The polarizing plate with a retardation layer obtained in the examples and comparative examples was cut to a width of 15 mm and a length of 200 mm and used as a sample. Tension was applied to the obtained sample in the longitudinal direction using a tensiometer (manufactured by MYCARBON, product name: Digital Luggage Scale). At tension levels of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg, the in-plane phase difference was measured using a phase difference measurement device (manufactured by Oji Keisokuki Co., Ltd., product name: KOBRA-WPR). The phase difference measured at each tension was plotted to calculate the slope, which was used as the value of the phase difference change.

[Manufacture Example 1: Production of polarizer]

1. Fabrication of polarizer

A long roll of 30㎛ thick polyvinyl alcohol (PVA)-based resin film (manufactured by Claret, product name 'PE3000') is stretched uniaxially in the longitudinal direction by a roll stretching machine to a length of 5.9 times, while simultaneously swelling, dyeing, and A polarizer with a thickness of 12 μm was produced by crosslinking, washing, and finally drying.

Specifically, the swelling treatment was carried out with pure water at 20°C and stretched 2.2 times. Next, the dyeing treatment was carried out in an aqueous solution at 30°C with a weight ratio of iodine and potassium iodide of 1:7, with the iodine concentration adjusted so that the resulting polarizer had a single transmittance of 45.0%, and was stretched 1.4 times. In addition, the crosslinking treatment adopted a two-stage crosslinking treatment, and the first crosslinking treatment was stretched 1.2 times while being treated in an aqueous solution of boric acid and potassium iodide at 40°C. The boric acid content of the aqueous solution in the first stage crosslinking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. In the second stage of crosslinking treatment, the material was stretched 1.6 times while being treated in an aqueous solution of boric acid and potassium iodide at 65°C. The boric acid content of the aqueous solution in the second stage crosslinking treatment was 3.7% by weight, and the potassium iodide content was 5.0% by weight. Additionally, the washing treatment was performed with an aqueous potassium iodide solution at 20°C. The potassium iodide content of the aqueous solution for washing treatment was 3.1% by weight. Finally, the drying treatment was performed at 70°C for 5 minutes to obtain a polarizer.

2. Production of polarizer

An HC-COP film was bonded as a protective layer to the surface of the polarizer obtained above (the side opposite to the resin substrate) through an ultraviolet curing adhesive. Specifically, the curable adhesive was applied to a thickness of 1.0 μm and bonded using a roll machine. Afterwards, UV rays were irradiated from the protective layer side to cure the adhesive. In addition, the HC-COP film is a film in which a hard coat (HC) layer (2㎛ thick) is formed on a cycloolefin (COP) film (product name 'ZF12', manufactured by Japan Zeon, product name 'ZF12', thickness 25㎛), and the COP film is on the polarizer side. It was joined together in this way. Next, the resin substrate was peeled, and a polarizing plate having the structure of protective layer (HC layer/COP film)/adhesive layer/polarizer was obtained.

[Manufacture Example 2: Production of the first phase difference layer (A) (single first phase difference layer)]

After adding 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 formula (III) to 400 parts by weight of cyclopentanone (CPN), It was heated to 60°C and stirred to dissolve. Afterwards, the solution of the above compound was returned to room temperature, and to the solution of the above compound, 3 parts by weight of 'Irgacure 907' (manufactured by BASF Japan) and 'Megapack F-554' (manufactured by DIC) were added. Preparation) 0.2 parts by weight and 0.1 parts by weight of p-methoxyphenol (MEHQ) were added and further stirred. The solution after stirring was transparent and uniform. The obtained solution was filtered through a 0.20㎛ membrane filter to obtain a polymerizable composition.

Additionally, the polyimide solution for an alignment film was applied to a glass substrate with a thickness of 0.7 mm using a spin coat method, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The obtained coating film was subjected to a rubbing treatment using a commercially available rubbing device to form an alignment film.

Next, the polymerizable composition obtained above was applied to the substrate (substantially an alignment film) by spin coating and dried at 100°C for 2 minutes. After cooling the obtained coating film to room temperature, it was irradiated with ultraviolet rays at an intensity of 30 mW/cm ² for 30 seconds using a high-pressure mercury lamp to obtain a first retardation layer (thickness 3 μm), which is an alignment-fixed layer of the liquid crystal compound. The in-plane phase difference Re(550) of the first phase difference layer was 130 nm. In addition, Re(450)/Re(550) of the first phase difference layer was 0.851, and showed inverse dispersion wavelength characteristics. The first retardation layer may function as a λ/4 plate.

[Manufacture Example 3: Production of the second phase difference layer]

In an autoclave equipped with a stirrer, cooling tube, nitrogen introduction tube, and thermometer, 48 parts by weight of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical, brand name: Metroz 60SH-50), 15601 parts by weight of distilled water, and diisopropyl fumarate. Add 8161 parts by weight, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of t-butylperoxypivalate as a polymerization initiator, nitrogen bubbling was performed for 1 hour, and then stirred at 49°C for 24 hours. By holding, radical suspension polymerization was performed. Then, it was cooled to room temperature, and the suspension containing the resulting polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure. The obtained fumaric acid ester-based resin was dissolved in a toluene/methyl ethyl ketone mixed solution (toluene/methyl ethyl ketone 50% by weight/50% by weight) to make a 20% solution. Furthermore, dope was prepared by adding 5 parts by weight of tributyl trimellitate as a plasticizer to 100 parts by weight of fumaric acid ester-based resin. As a support film, a biaxially stretched film (75 μm thick) of polyester (polyethylene-terephthalate/isophthalate copolymer) was used. The dope prepared on the support film was applied so that the film thickness after drying was 5 μm, and dried at 140°C. The coated film (positive C plate) after drying had Re(550)≈0nm and Rth(550)=-75nm.

[Manufacture Example 4: Production of the first phase difference layer (B) (first phase difference layer with a laminated structure)]

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystalline phase (manufactured by BASF, brand name 'Paliocolor LC242', expressed in the formula below), and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, brand name 'Irgacure 907') 3 g was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of a polyethylene terephthalate (PET) film (thickness 38㎛) was rubbed using a rubbing cloth, and orientation treatment was performed. The direction of the orientation treatment was set to be 15° when viewed from the viewer's side with respect to the absorption axis direction of the polarizer when bonding to the polarizing plate. The liquid crystal coating liquid was applied to this alignment treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer thus formed was irradiated with light of 1 mJ/cm ² using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal alignment layer (A) on the PET film. The thickness of the liquid crystal alignment solidification layer (A) was 2.5 μm, and the in-plane retardation Re(550) was 270 nm. Additionally, the liquid crystal alignment solidification layer (A) exhibited refractive index characteristics of nx>ny=nz.

A liquid crystal alignment solidification layer (B) was formed on the PET film in the same manner as above except that the coating thickness was changed and the orientation treatment direction was 75° when viewed from the viewer's side with respect to the absorption axis direction of the polarizer. The thickness of the liquid crystal alignment solidification layer (B) was 1.5 μm, and the in-plane retardation Re(550) was 140 nm. Additionally, the liquid crystal alignment solidification layer (B) exhibited refractive index characteristics of nx>ny=nz.

[Example 1]

A protective layer (triacetylcellulose (TAC) film, thickness: 20 μm) was bonded to the polarizer of the polarizing plate obtained in Production Example 1 through an adhesive layer, and the protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive was formed. A polarizer layer/protective layer (TAC) was obtained.

Separately, the liquid crystal alignment solidification layer (A) and the liquid crystal alignment layer (B) obtained in Production Example 4 were prepared so that the angle formed between the absorption axis of the polarizer and the slow axis of the alignment solidification layer (A) was 15°, and the absorption axis of the polarizer was Transfer (lamination) was performed in this order so that the angle formed by the slow axis of the orientation-fixed layer (B) was 75°. The orientation solidification layer (A) and the orientation solidification layer (B) were each laminated through an ultraviolet curing adhesive (thickness of 1 μm after curing).

Next, an ultraviolet curing adhesive (thickness after curing: 1 μm) is applied to the liquid crystal alignment solidification layer (B), the second retardation layer obtained in Production Example 3 is laminated, and the liquid crystal alignment solidification layer (A)/adhesive layer/liquid crystal alignment is formed. A laminate of solidified layer (B)/adhesive layer/second phase difference layer was obtained.

Next, the TAC side surface of the obtained polarizing plate and the liquid crystal alignment solidification layer (A) of the above laminate were laminated through an acrylic pressure-sensitive adhesive layer (thickness of 5 μm). Next, the substrate of the second phase contrast layer was peeled off. Afterwards, an acrylic adhesive (thickness 26㎛) is applied to the base material peeling surface of the second retardation layer, and protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/protective layer (TAC)/adhesive layer/ A polarizing plate with a retardation layer having the structure of the first retardation layer (liquid crystal alignment solidification layer (A)/adhesive layer/liquid crystal alignment solidification layer (B)/adhesive layer/second retardation layer/adhesive layer was obtained. The obtained polarizing plate was as described above. The results were provided for evaluation and are shown in Table 1.

(Comparative Example 1)

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the second retardation layer was not laminated. The obtained polarizing plate was subjected to the above evaluation. The results are shown in Table 1.

[Manufacture Example 5: Production of positive C plate, which is a liquid crystal alignment solidification layer]

20 parts by weight of a side-chain liquid crystal polymer represented by the following formula (the numbers 65 and 35 in the formula represent the mole percent of the monomer unit, and are represented as a block polymer for convenience: weight average molecular weight 5000), a polymerizable liquid crystal exhibiting a nematic liquid crystal phase. Dissolve 80 parts by weight of (manufactured by BASF, brand name 'Paliocolor LC242') and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, brand name 'Irgacure 907') in 200 parts by weight of cyclopentanone. A liquid crystal coating solution was prepared. Then, the coating liquid was applied to the PET base material that had been vertically aligned using a bar coater, and then heated and dried at 80°C for 4 minutes to orient the liquid crystal. By irradiating ultraviolet rays to this liquid crystal layer and curing the liquid crystal layer, a retardation layer (thickness 3 μm) exhibiting refractive index characteristics of nz>nx=ny was formed on the substrate.

(Comparative Example 2)

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the retardation layer obtained in Preparation Example 5 was used instead of the second retardation layer obtained in Preparation Example 3. The obtained polarizing plate was subjected to the above evaluation. The results are shown in Table 1.

[Example 2]

A protective layer (triacetylcellulose (TAC) film, thickness: 20 μm) was bonded to the polarizer of the polarizing plate obtained in Production Example 1 through an adhesive layer, and the protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive A polarizer layer/protective layer (TAC) was obtained.

Separately, the first retardation layer (A) obtained in Preparation Example 2 is bonded to the protective layer (TAC) of the polarizing plate such that the angle formed between the absorption axis of the polarizer and the slow axis of the first retardation layer (A) is 45°. did. The first retardation layer and the protective layer (TAC) were laminated through an ultraviolet curing adhesive (thickness of 1㎛ after curing).

Next, the TAC side surface of the obtained polarizer and the first retardation layer were laminated through an acrylic adhesive layer (thickness 5 μm). Next, the substrate of the second phase contrast layer was peeled off. Afterwards, an acrylic adhesive (thickness 26㎛) is applied to the base material peeling surface of the second retardation layer, and protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/protective layer (TAC)/adhesive layer/ A polarizing plate with a retardation layer having a structure of first retardation layer/adhesive layer/second retardation layer/adhesive layer was obtained. The obtained polarizing plate was subjected to the above evaluation. The results are shown in Table 1.

(Comparative Example 3)

A polarizing plate with a retardation layer was obtained in the same manner as in Example 2 except that the second retardation layer was not laminated. The obtained polarizing plate was subjected to the above evaluation. The results are shown in Table 1.

(Comparative Example 4)

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the retardation layer obtained in Preparation Example 5 was used instead of the second retardation layer obtained in Preparation Example 3. The obtained polarizing plate was subjected to the above evaluation. The results are shown in Table 1.

[Table 1]

[evaluation]

As is clear from Table 1, the polarizing plate with a retardation layer of the example of the present invention had excellent high-temperature durability, and in-plane unevenness of the reflected color was suppressed.

[Industrial applicability]

The polarizing plate with a retardation layer of the present invention is suitably used in image display devices such as liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

10: Polarizer
11: Polarizer
12: protective layer
13: protective layer
20: first phase contrast layer
30: second phase contrast layer
100: Polarizer with phase contrast layer
101: Polarizer with phase contrast layer

Claims (10)

A polarizing plate including a polarizer with a thickness of 7 μm or more,
A first phase difference layer, which is an alignment solidification layer of a liquid crystal compound,
A polarizing plate with a retardation layer including a second retardation layer comprised of a resin film containing a polymer exhibiting negative birefringence. According to paragraph 1,
A polarizing plate with a retardation layer, wherein the second retardation layer is adjacent to the first retardation layer. According to claim 1 or 2,
A polarizing plate with a retardation layer, wherein the second retardation layer is a positive C plate. According to any one of claims 1 to 3,
A polarizing plate with a retardation layer, wherein the second retardation layer has a thickness of 1 μm to 30 μm. According to any one of claims 1 to 4,
A polarizing plate with a retardation layer, wherein the polymer exhibiting negative birefringence is at least one selected from the group consisting of acrylic resin, styrene resin, and maleimide resin. According to any one of claims 1 to 5,
The in-plane phase difference of the first phase difference layer is 100nm<Re(550)<160nm, and,
A polarizing plate with a retardation layer that satisfies Re(450)/Re(550)<1 and Re(650)/Re(550)>1. According to clause 6,
A polarizing plate with a retardation layer, wherein the angle between the slow axis of the first retardation layer and the absorption axis of the polarizer is 40° to 50°. According to any one of claims 1 to 5,
The first retardation layer has a stacked structure of an orientation-fixed liquid crystal compound layer (A) and an orientation-fixed liquid crystal compound layer (B),
A polarizing plate with a retardation layer, wherein the orientation-fixed layer (A) functions as a λ/2 plate, and the orientation-fixed layer (B) functions as a λ/4 plate. According to clause 8,
The angle between the slow axis of the alignment-fixed layer (A) of the liquid crystal compound and the absorption axis of the polarizer is 70° to 80°, and the slow axis of the alignment-fixed layer (B) of the liquid crystal compound and the absorption axis of the polarizer are 70° to 80°. A polarizer with a retardation layer whose axis angle is 10° to 20°. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 9.