JP2024018516A - Polarizer and image display device - Google Patents

Abstract

To provide a polarizer including a retardation plate having a plurality of retardation layers each containing a cured product of a liquid crystal compound, the polarizer having excellent durability against peeling force applied when a base material is peeled.SOLUTION: A polarizer is formed by laminating a linear polarizer, a first bonding layer and a retardation plate in this order. The retardation plate includes a first retardation layer and a second retardation layer, where the first retardation layer and the second retardation layer each contains a cured product of a liquid crystal compound and has a puncture modulus of elasticity of 70 g/mm or more. The first bonding layer has a tensile modulus of elasticity of 1.0×108 Pa or less at 23°C and 55% relative humidity.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polarizing plate and an image display device.

Conventionally, in image display devices, a method has been adopted in which a circularly polarizing plate is disposed on the viewing side of an image display panel to suppress a decrease in visibility due to reflection of external light.

A circularly polarizing plate has a structure in which a linearly polarizing plate and a retardation plate are laminated. In the circularly polarizing plate, external light directed toward the image display panel is converted into linearly polarized light by a linearly polarizing plate, and then converted into circularly polarized light by a subsequent retardation plate. External light, which is circularly polarized light, is reflected on the surface of the image display panel, but upon reflection, the rotation direction of the polarization plane is reversed, and after being converted to linearly polarized light by a retardation plate, the light is blocked by the following linear polarizer. be done. As a result, the emission of extraneous light to the outside is significantly suppressed.

In the retardation plate, a structure having a retardation layer containing a cured product of a liquid crystal compound is known (for example, Patent Documents 1 and 2). According to this configuration, it is possible to reduce the thickness of the retardation plate.

Japanese Patent Application Publication No. 2015-163935 JP2019-91030A

In a retardation plate having multiple retardation layers containing a cured product of a liquid crystal compound, if priority is given to making it thin, the retardation layer, especially the retardation layer close to the base material to be peeled off, will be damaged by the peeling force applied when the base material is peeled off. There have been cases where problems have occurred in which damage has occurred.

An object of the present invention is to provide a polarizing plate equipped with a retardation plate having a plurality of retardation layers containing a cured product of a liquid crystal compound, which has excellent durability against peeling force applied when peeling off a base material. With the goal.

The present invention provides the following polarizing plate.
[1] A polarizing plate in which a linear polarizing plate, a first bonding layer, and a retardation plate are laminated in this order,
The retardation plate is
comprising a first retardation layer and a second retardation layer,
The first retardation layer and the second retardation layer include a cured product of a liquid crystal compound,
The puncture modulus is 70 g/mm or more,
The first bonding layer is a polarizing plate having a tensile modulus of 1.0×10 ⁸ Pa or less at a temperature of 23° C. and a relative humidity of 55%.
[2] The polarizing plate according to [1], wherein the product of the thickness (m) and the tensile modulus (Pa) of the first bonding layer is 500 or less. [3] The retardation plate is The polarizing plate according to [1] or [2], which has only an alignment film or no other intervening layer between the retardation layer and the second retardation layer.
[4] The linearly polarizing plate has a polarizer,
The polarizing plate according to any one of [1] to [3], wherein the polarizer has a thickness of 15 μm or less.
[5] The linearly polarizing plate has a protective film provided on the surface of the polarizer opposite to the first lamination layer,
The polarizing plate according to [4], wherein the protective film has a thickness of 30 μm or less.
[6] The polarizing plate according to any one of [1] to [5], wherein the first retardation layer is a reverse dispersion λ/4 layer.
[7] The polarizing plate according to any one of [1] to [6], wherein the second retardation layer is a positive C plate.

According to the present invention, it is possible to provide a polarizing plate that has excellent durability against peeling force applied when peeling off a base material.

FIG. 1 is a schematic cross-sectional view schematically showing an example of a polarizing plate of this embodiment. FIG. 2 is a schematic cross-sectional view schematically showing a specific example of a retardation plate. FIG. 2 is a schematic cross-sectional view schematically showing a specific example of a retardation plate. FIG. 1 is a schematic cross-sectional view schematically showing an example of an image display device according to the present embodiment.

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, each component is shown adjusted to an appropriate scale to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the actual scale of the component.

[Polarizer]
FIG. 1 is a schematic cross-sectional view schematically showing an example of a polarizing plate of this embodiment. As shown in FIG. 1, in the polarizing plate 1, a linear polarizing plate 10, a first bonding layer 21, and a retardation plate 30 are laminated in this order from the front side. The retardation plate 30 includes a first retardation layer 31 and a second retardation layer 32. The polarizing plate 1 may be a circularly polarizing plate. In this specification, the term polarizing plate also includes circularly polarizing plates.

The retardation plate 30 has a piercing elastic modulus of 70 g/mm or more. The puncture elastic modulus is a value measured by a method according to the method described in Examples. The puncture elastic modulus of the retardation plate 30 is preferably 140 g/mm or less, more preferably 120 g/mm or less, and may be 110 g/mm or less. The retardation plate 30 may or may not include a base material that is planned to be peeled off from the polarizing plate, and the puncture elastic modulus of the retardation plate 30 in this specification is the same as that of the retardation plate. 30 means the puncture elastic modulus of the layer structure of the portion that does not include the base material that is scheduled to be peeled off from the polarizing plate. In the retardation plate 30, there may or may not be another layer interposed between the first retardation layer 31 and the second retardation layer 32.

In the retardation plate 30, when the first retardation layer 31 and the second retardation layer 32 are laminated via a lamination layer (hereinafter referred to as "third lamination layer"), piercing Although the elastic modulus depends on the hardness of the third bonding layer, when the third bonding layer is a layer made of an adhesive, the puncture elastic modulus tends to be low and may be less than 70 g/mm. . On the other hand, when the third bonding layer is a layer made of adhesive, the puncture elastic modulus tends to be high and may be 70 g/mm or more. In the retardation plate 30, when the first retardation layer 31 and the second retardation layer 32 are laminated without a bonding layer interposed therebetween, the puncture elastic modulus of the retardation plate 30 tends to be high and is usually 70 g/mm or more. In the retardation plate 30, a configuration in which the first retardation layer 31 and the second retardation layer 32 are laminated without a bonding layer is such that the first retardation layer 31 and the second retardation layer 32, there may be mentioned a structure having only an alignment film or having no other intervening layer.

The present inventors have found that a polarizing plate using a retardation plate having a high puncture elastic modulus has low durability against the peeling force applied when peeling the base material. On the other hand, if the puncture elastic modulus of the retardation plate is lowered, the peeling force of the base material becomes lighter, which tends to cause the problem that the base material tends to float. The present inventors further conducted intensive research and found that even if the polarizing plate uses a retardation plate with a puncture elastic modulus of 70 g/mm or more, the By making the bonding layer 21 made of an adhesive having a tensile modulus of 1.0 x 10 ⁸ Pa or less at a temperature of 23° C. and a relative humidity of 55%, the bonding layer 21 can be added at the time of peeling off the base material. The present invention was developed based on the finding that a polarizing plate having excellent durability against peeling force can be obtained. Furthermore, with this configuration, the present invention can suppress the occurrence of cracks caused by heat shock or polishing. The tensile modulus of the adhesive forming the first bonding layer 21 at a temperature of 23° C. and a relative humidity of 55% is preferably 1.0×10 ⁷ Pa or less, more preferably 1.0×10 ⁶ Pa or less, preferably 1.0×10 ³ Pa or more, and more preferably 1.0×10 ⁵ Pa or more. Further, the product of the thickness (m) and the tensile modulus (Pa) of the adhesive forming the first bonding layer 21 is preferably 500 or less, more preferably 50 or less, and even more preferably 5 or less. The product of the thickness (m) and tensile modulus (Pa) of the adhesive forming the first bonding layer 21 is preferably 0.005 or more, more preferably 0.5 or more. By setting the value within this range, durability against peeling force can be improved.

The polarizing plate according to the present invention has high durability against peeling force applied when peeling off a base material. Damage to the retardation layer can be suppressed. The retardation layer of a retardation plate, if it is a layer containing a cured product of a liquid crystal compound, is thin and easily damaged when the base material is peeled off, especially the closer the retardation layer is to the base material, the more likely it is to be damaged. In the polarizing plate according to the invention, such damage can be suppressed. Examples of the base material include base materials used in the manufacturing process of the retardation plate.

The tensile modulus of the adhesive forming the first bonding layer 21 at a temperature of 23° C. and a relative humidity of 55% can be measured by the following procedure. An adhesive composition is applied to the release-treated surface of a polyethylene terephthalate film (hereinafter sometimes referred to as "PET film") that has been subjected to a release process using an applicator. Thereafter, the pressure-sensitive adhesive composition applied to the PET film was dried by placing it in a room temperature atmosphere for 30 minutes to pre-dry it, and then placing it at a temperature of 100°C for 5 minutes to dry it. Thoroughly volatilize the solvent. Finally, a predetermined curing treatment (heat treatment, ultraviolet irradiation treatment, etc.) is performed to create a bonding layer on the PET film, and the bonding layer obtained by peeling off the PET film is used as a sample for measurement as described below. The tensile modulus may be measured by the method described in Examples.

[First lamination layer]
The first bonding layer 21 is a layer responsible for bonding the linearly polarizing plate 10 and the retardation plate 30 together. Examples of the pressure-sensitive adhesive having a tensile modulus of elasticity of 1.0×10 ⁸ Pa or less at a temperature of 23° C. and a relative humidity of 55% include pressure-sensitive adhesives and adhesives. As the first bonding layer 21, an adhesive is preferably used.

The specific adhesive used in the first bonding layer 21 may be made of, for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether, or the like as a base polymer. Among these, polymers such as acrylic polymers have excellent optical transparency, maintain appropriate wettability and cohesive strength, and have excellent adhesion to substrates, as well as weather resistance and heat resistance. It is preferable to select and use a material that does not cause peeling problems such as lifting or peeling under conditions of heating or humidification. In acrylic polymers, alkyl esters of acrylic acid having alkyl groups with carbon numbers of 20 or less, such as methyl, ethyl, and butyl groups, and functional compounds such as (meth)acrylic acid and hydroxyethyl (meth)acrylate are used. An acrylic copolymer with a weight average molecular weight of 100,000 or more, which is blended with a group-containing acrylic monomer so that the glass transition temperature is preferably 25°C or lower, more preferably 0°C or lower, is useful as a base polymer. It is.

Acrylic polymers include, but are not particularly limited to, (meth)acrylics such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Acid ester base polymers and copolymer base polymers using two or more of these (meth)acrylate esters are preferably used. Moreover, a polar monomer may be copolymerized with these base polymers. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylamide, and 2-N,N-dimethylaminoethyl (meth) Examples include monomers having polar functional groups such as carboxyl groups, hydroxyl groups, amide groups, amino groups, and epoxy groups, such as acrylate and glycidyl (meth)acrylate.

Although these acrylic polymers can be used alone as an adhesive, a crosslinking agent is usually added to the adhesive. Examples of crosslinking agents include divalent or polyvalent metal ions that form carboxylic acid metal salts with carboxyl groups, polyamine compounds that form amide bonds with carboxyl groups, Examples include polyepoxy compounds and polyol compounds that form ester bonds with carboxyl groups, and polyisocyanate compounds that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are widely used as organic crosslinking agents.

In this embodiment, the means for adjusting the tensile modulus of the adhesive forming the first bonding layer is not particularly limited, but for example, oligomer, specifically urethane acrylate, is added to the above-mentioned adhesive component. Preferred methods include blending oligomers. Furthermore, an adhesive containing such a urethane acrylate oligomer may be cured by irradiating it with energy rays. Adhesives containing urethane acrylate oligomers, or adhesives with separators that are coated onto a support film (separator) and cured with ultraviolet light, are well known and can be obtained from adhesive manufacturers.

In addition to the above-mentioned base polymer, crosslinking agent, and oligomer, the adhesive may contain natural products, for example, to adjust the adhesive strength, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. Appropriate additives such as synthetic resins, tackifying resins, antioxidants, ultraviolet absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, and photopolymerization initiators may also be blended. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex salt compounds.

The thickness of the first bonding layer 21 is determined depending on its adhesive strength, etc., but is usually in the range of 1 to 40 μm. The thickness of the adhesive layer is preferably 3 to 25 μm or 20 μm or less, since this maintains good processability and exhibits high durability. Further, by having a thickness within the above range, durability against peeling force can be further improved.

Specific adhesives used for the first bonding layer 21 include adhesives other than pressure-sensitive adhesives (adhesives), such as water-based adhesives and active energy ray-curable adhesives.

Examples of water-based adhesives include adhesives in which polyvinyl alcohol-based resin is dissolved or dispersed in water. The drying method when using a water-based adhesive is not particularly limited, but for example, a method of drying using a hot air dryer or an infrared dryer can be adopted.

Examples of active energy ray-curable adhesives include solvent-free active energy ray-curable adhesives containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Can be mentioned. By using a solvent-free active energy ray-curable adhesive, it is possible to improve the adhesion between layers.

The active energy ray-curable adhesive preferably contains one or both of a cationically polymerizable curable compound and a radically polymerizable curable compound, since it exhibits good adhesive properties. The active energy ray-curable adhesive may further contain a cationic polymerization initiator such as a photocationic polymerization initiator or a radical polymerization initiator for starting the curing reaction of the curable compound.

Examples of cationically polymerizable curable compounds include alicyclic epoxy compounds having an epoxy group bonded to an alicyclic ring, and polyfunctional aliphatic epoxy compounds having two or more epoxy groups and no aromatic ring. , monofunctional epoxy groups having one epoxy group (excluding those included in alicyclic epoxy compounds), polyfunctional aromatic epoxy compounds having two or more epoxy groups and an aromatic ring, etc. Compounds; oxetane compounds having one or more oxetane rings in the molecule; combinations thereof can be mentioned.

Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), and others having radically polymerizable double bonds. or a combination thereof.

The active energy ray-curable adhesive may contain a sensitizer such as a photosensitizer, if necessary. By using a sensitizer, the reactivity is improved and the mechanical strength and adhesive strength of the adhesive layer can be further improved. As the sensitizer, any known sensitizer can be used as appropriate. When a sensitizer is blended, the blending amount is preferably in the range of 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the active energy ray-curable adhesive.

Active energy ray-curable adhesives contain ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, antifoaming agents, and antistatic agents, as required. It may contain additives such as a chemical agent, a leveling agent, and a solvent.

When using an active energy ray-curable adhesive, the adhesive layer can be formed by irradiating active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays to harden the adhesive coating layer. can. As the active energy ray, ultraviolet rays are preferable, and in this case, as a light source, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp, etc. can be used. can.

The thickness of the adhesive used as the first bonding layer 21 is determined depending on its adhesive strength, etc., but is usually in the range of 0.02 to 10 μm. The thickness of the adhesive layer is preferably 1 to 4 μm from the viewpoint of further improving durability against external forces.

[Linear polarizing plate]
The linearly polarizing plate 10 may be any film that has a polarizing function to obtain linearly polarized light from transmitted light. Examples of the film include a stretched film on which a dye having absorption anisotropy is adsorbed, a film containing a film coated with a dye having absorption anisotropy as a polarizer, and the like. Examples of dyes having absorption anisotropy include dichroic dyes. A film coated with a dye having absorption anisotropy and used as a polarizer may be a stretched film on which a dye having absorption anisotropy is adsorbed, or a composition containing a dichroic dye having liquid crystallinity or a dichroic dye. Examples include a film having a liquid phase layer obtained by applying a composition containing a chromatic dye and a polymerizable liquid crystal.

<Linear polarizing plate including stretched film as a polarizer>
A linear polarizing plate including a stretched film as a polarizer on which a dye having absorption anisotropy is adsorbed will be described. Stretched films that have adsorbed dyes with absorption anisotropy, which are polarizers, are usually produced through a process of uniaxially stretching a polyvinyl alcohol resin film or by dyeing the polyvinyl alcohol resin film with a dichroic dye. It is manufactured through the steps of adsorbing a dichroic dye, treating the polyvinyl alcohol resin film with the dichroic dye adsorbed with an aqueous boric acid solution, and washing with water after the treatment with the aqueous boric acid solution. Such a polarizer may be used as it is as a linear polarizing plate, or such a polarizer with a transparent protective film pasted on at least one surface may be used as a linear polarizing plate.

The thickness of the polarizer obtained by uniaxially stretching the polyvinyl alcohol resin film, dyeing with a dichroic dye, boric acid treatment, washing with water, and drying is preferably 5 to 40 μm, more preferably 15 μm or less. , more preferably 10 μm or less.

The material of the protective film attached to one or both sides of the polarizer is not particularly limited, but examples include cyclic polyolefin resin films, cellulose acetate-based resins such as triacetylcellulose, and diacetylcellulose. Films known in the art, such as resin films, polyester resin films made of resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polycarbonate resin films, (meth)acrylic resin films, and polypropylene resin films. can be mentioned. From the viewpoint of thinning, the thickness of the protective film is usually 300 μm or less, preferably 200 μm or less, more preferably 30 μm or less, and usually 5 μm or more, and may be 10 μm or more. . If the thickness of the protective film is 30 μm or less, or if the tensile modulus at 23°C is 2000 MPa or more, the protective film will not function as a layer for relieving the force applied when peeling off the base material, resulting in poor durability against peeling off the base material. This tends to cause problems such as damage to the retardation layer close to the base material to be peeled off. Further, the protective film on the viewing side may or may not have a retardation.

The protective film can be bonded to one or both sides of the polarizer via a bonding layer (hereinafter referred to as "second bonding layer").

<Linear polarizing plate including a film having a liquid crystal layer as a polarizer>
A linear polarizing plate including a film having a liquid crystal layer as a polarizer will be described. A film coated with a dye having absorption anisotropy and used as a polarizer may be coated with a composition containing a dichroic dye having liquid crystal properties, or a composition containing a dichroic dye and a liquid crystal compound. Examples include the resulting film. The film may be used alone as a linearly polarizing plate, or may be used as a linearly polarizing plate with a protective film on one or both sides. Examples of the protective film include the same one as the linear polarizing plate having the above-mentioned stretched film as a polarizer. The protective film can be bonded to one or both sides of the polarizer via a second bonding layer.

It is preferable for a film coated with a dye having absorption anisotropy to be thin, but if it is too thin, the strength tends to decrease and processability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 15 μm or less, more preferably 5 μm or less, and even more preferably 0.5 μm or more and 3 μm or less.

Specific examples of the film coated with the dye having absorption anisotropy include the films described in JP-A No. 2013-33249 and the like.

One embodiment of the linearly polarizing plate includes a configuration in which a protective film is provided on the surface of the linearly polarizing plate opposite to the first bonding layer.

<Foremost layer>
The linear polarizing plate 10 may include an antireflection layer on the front surface. The antireflection layer has a function of preventing external light reflected from the surface or inside of the linear polarizing plate 10 from being visible, and can be formed using a conventional method for forming an antireflection layer, that is, a coating method. , a sputtering method, a vacuum evaporation method, or the like. The antireflection layer may be formed in advance on the front side of a protective film provided on the front side of the linearly polarizing plate 10, and such a protective film may be used to configure a linearly polarizing plate with an antireflection layer. It may be provided separately from the protective film.

The linearly polarizing plate 10 may have a surface treatment layer other than the antireflection layer on the front surface. Examples of such surface treatment layers include hard coat layers, anti-sticking layers, anti-glare layers, and diffusion layers.

[Retardation plate]
The retardation plate 30 has a first retardation layer 31 and a second retardation layer 32, the first retardation layer 31 and the second retardation layer 32 contain a cured product of a liquid crystal compound, and have a piercing elastic modulus of 70 g. There is no limitation as long as it is equal to or greater than /mm. The retardation plate 30 may include a third retardation layer. Each of the first retardation layer, the second retardation layer, and the third retardation layer may be composed of two or more layers. The retardation plate 30 may have a base material on the surface opposite to the linearly polarizing plate 10 side. The base material may be a base material for forming a retardation layer, and may be peelable from the retardation layer.

It is preferable that the retardation plate 30 has optical characteristics expressed by formulas (1) and (2). In order for the retardation plate 30 to have such optical characteristics, the first retardation layer 31, the second retardation layer 32, or the third retardation layer must have the optical characteristics expressed by formulas (1) and (2). or by combining at least two selected from the first retardation layer 31, the second retardation layer 32, and the third retardation layer, the optical characteristics expressed by formulas (1) and (2) can be achieved. It only needs to be expressed.
Re(450)/Re(550)≦1.00 (1)
1.00≦Re(650)/Re(550) (2)

In this specification, Re (450) represents an in-plane retardation value at a wavelength of 450 nm, Re (550) represents an in-plane retardation value at a wavelength of 550 nm, and Re (650) represents an in-plane retardation value at a wavelength of 650 nm. represents.

<Retardation layer>
Examples of the retardation layer include a layer formed by polymerizing a polymerizable liquid crystal and a stretched film. The optical properties of the retardation layer can be adjusted by the alignment state of the polymerizable liquid crystal or the stretching method of the stretched film. The layer formed by polymerizing the polymerizable liquid crystal includes a cured product of the liquid crystal compound. In the retardation plate 30, from the viewpoint of thinning, at least the first retardation layer 31 and the second retardation layer 32 are layers containing a cured product of a liquid crystal compound.

(Layer formed by polymerizing polymerizable liquid crystal)
In this specification, horizontal alignment refers to a polymerizable liquid crystal whose optical axis is aligned horizontally to the plane of the substrate, and vertical alignment refers to a polymerizable liquid crystal whose optical axis is aligned perpendicular to the substrate plane. Define. Optical axis means the direction in which the cross section cut out in the direction perpendicular to the optical axis is a circle in the refractive index ellipsoid formed by the orientation of polymerizable liquid crystal, that is, the direction in which the refractive index in all three directions is equal. .

Examples of the polymerizable liquid crystal include rod-shaped polymerizable liquid crystals and disk-shaped polymerizable liquid crystals. When the rod-shaped polymerizable liquid crystal is aligned horizontally or vertically with respect to the base material, the optical axis of the polymerizable liquid crystal coincides with the long axis direction of the polymerizable liquid crystal. When the disc-shaped polymerizable liquid crystal is oriented, the optical axis of the polymerizable liquid crystal exists in a direction perpendicular to the disc surface of the polymerizable liquid crystal.

The slow axis direction of a stretched film varies depending on the stretching method, and the slow axis and optical axis are determined depending on the stretching method, such as uniaxial, biaxial or diagonal stretching.

In order for the layer formed by polymerizing the polymerizable liquid crystal to exhibit an in-plane retardation, the polymerizable liquid crystal may be oriented in a suitable direction. When the polymerizable liquid crystal is rod-shaped, an in-plane retardation occurs by aligning the optical axis of the polymerizable liquid crystal horizontally to the plane of the substrate. In this case, the optical axis direction and the slow axis direction are Match. When the polymerizable liquid crystal is disc-shaped, an in-plane retardation occurs by aligning the optical axis of the polymerizable liquid crystal horizontally to the substrate plane. In this case, the optical axis and the slow axis are orthogonal. do. The alignment state of the polymerizable liquid crystal can be adjusted by combining the alignment film and the polymerizable liquid crystal.

The in-plane retardation value of the retardation layer can be adjusted by adjusting the thickness of the retardation layer. Since the in-plane retardation value is determined by equation (10), in order to obtain the desired in-plane retardation value (Re(λ)), Δn(λ) and the film thickness d may be adjusted.
Re(λ)=d×Δn(λ) (10)
In the formula, Re(λ) represents the in-plane retardation value at the wavelength λnm, d represents the film thickness, and Δn(λ) represents the birefringence at the wavelength λnm.

The birefringence Δn(λ) is obtained by measuring the in-plane retardation value and dividing it by the thickness of the retardation layer. In the specific measurement method, the actual characteristics of the retardation layer are measured by measuring a film formed on a substrate that does not have an in-plane retardation, such as a glass substrate. be able to.

In this specification, the refractive indices in three directions in a refractive index ellipsoid formed by orientation of a polymerizable liquid crystal or stretching of a film are expressed as nx, ny, and nz. nx represents the principal refractive index in the direction parallel to the film plane in the refractive index ellipsoid formed by the retardation layer. ny represents the refractive index in a direction parallel to the film plane and perpendicular to the direction of nx in the refractive index ellipsoid formed by the retardation layer. nz represents the refractive index in the direction perpendicular to the film plane in the refractive index ellipsoid formed by the retardation layer.

When the optical axis of the rod-shaped polymerizable liquid crystal is oriented horizontally to the substrate plane, the refractive index relationship of the obtained retardation layer is nx > ny ≒ nz (positive A plate), which is The axis in the nx direction and the slow axis coincide.

Furthermore, when the optical axis of the disc-shaped polymerizable liquid crystal is oriented horizontally to the substrate plane, the refractive index relationship of the obtained retardation layer is nx < ny ≒ nz (negative A plate), and the refractive index The axis in the ny direction of the ellipsoid coincides with the slow axis.

In order for the layer formed by polymerizing the polymerizable liquid crystal to exhibit a retardation in the thickness direction, the polymerizable liquid crystal may be oriented in a suitable direction. In the present invention, expressing a retardation in the thickness direction is defined as exhibiting a characteristic in which Rth (retardation value in the thickness direction) is negative in equation (20). Rth can be calculated from the phase difference value (R ₄₀ ) measured by tilting the in-plane fast axis by 40 degrees as the tilt axis and the in-plane phase difference value (Re). That is, Rth is determined by calculating nx, ny, and nz from Re, R ₄₀ , d (thickness of the retardation layer), and n0 (average refractive index of the retardation layer) using the following equations (21) to (23). , can be calculated by substituting these into equation (20).
Rth=[(nx+ny)/2-nz]×d (20)
Re = (nx-ny)×d (21)
R ₄₀ = (nx-ny') x d/cos(φ) (22)
(nx+ny+nz)/3=n0 (23)
here,
φ=sin ^-1 [sin (40°)/n0]
ny'=ny×nz/[ny ² ×sin ² (φ)+nz ² ×cos ² (φ)] ^1/2
Further, nx, ny and nz are the same as defined above.

When the polymerizable liquid crystal is rod-shaped, the optical axis of the polymerizable liquid crystal is oriented perpendicularly to the plane of the base material, thereby producing a retardation in the thickness direction. When the polymerizable liquid crystal is disc-shaped, the optical axis of the polymerizable liquid crystal is oriented horizontally to the plane of the base material, thereby producing a retardation in the thickness direction. In the case of a disc-shaped polymerizable liquid crystal, the optical axis of the polymerizable liquid crystal is parallel to the plane of the substrate, so once Re is determined, the thickness is fixed, so Rth is uniquely determined. In the case of a rod-shaped polymerizable liquid crystal, since the optical axis of the polymerizable liquid crystal is perpendicular to the plane of the substrate, it is possible to adjust Rth without changing Re by adjusting the thickness of the retardation layer. I can do it.

When the optical axis of the rod-shaped polymerizable liquid crystal is oriented perpendicularly to the plane of the substrate, the refractive index relationship of the resulting retardation layer is nx≒ny<nz (positive C plate), which is the same in the refractive index ellipsoid. The axis in the nz direction and the slow axis direction coincide.

In addition, when the optical axis of the disc-shaped polymerizable liquid crystal is oriented parallel to the substrate plane, the refractive index relationship of the obtained retardation layer is nx < ny ≒ nz (negative A plate), and the refractive index The axis of the ny direction in the ellipsoid coincides with the slow axis direction.

<Polymerizable liquid crystal>
A polymerizable liquid crystal is a compound that has a polymerizable group and has liquid crystallinity. A polymerizable group means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by active radicals, acids, etc. generated from a photopolymerization initiator, which will be described later. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, and the like. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and if the thermotropic liquid crystal is classified according to the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.

Examples of the rod-shaped polymerizable liquid crystal include a compound represented by the following formula (A) and a compound containing a group represented by the following formula (X). The rod-shaped polymerizable liquid crystal is preferably a liquid crystal having a T-shaped or H-shaped mesogenic structure that is oriented perpendicular to the molecular axis direction and has birefringence from the viewpoint of wavelength dispersion, and stronger dispersion can be obtained. From this point of view, a T-shaped liquid crystal is more preferable, and specific examples of the structure of the T-shaped liquid crystal include a compound represented by the following formula (A).

(Compound represented by formula (A))
Formula (A) is as follows. Hereinafter, the compound represented by formula (A) may be referred to as polymerizable liquid crystal (A).

In formula (A), Ar represents a divalent aromatic group which may have a substituent. Preferably, the divalent aromatic group contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When the divalent group Ar contains two or more aromatic groups, the two or more aromatic groups are bonded to each other through a single bond or a divalent bonding group such as -CO-O- or -O-. You can leave it there.
G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, or a fluoroalkyl group having 1 to 4 carbon atoms. It may be substituted with 1 to 4 alkoxy groups, cyano groups, or nitro groups, and the carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group are oxygen atoms, sulfur atoms. Alternatively, it may be substituted with a nitrogen atom.
L ¹ , L ² _, B ¹ and B ² are each independently a single bond or a divalent linking group.
k and l each independently represent an integer from 0 to 3, and satisfy the relationship 1≦k+l. Here, when 2≦k+l, B ¹ and B ² and G ¹ and G ² may be the same or different from each other.
E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, where the hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and the alkanediyl group The -CH ₂ - contained therein may be substituted with -O-, -S-, or -COO-, and when a plurality of -O-, -S-, or -COO- are present, they are not adjacent to each other. P ¹ and P ² each independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms. , a 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, and more preferably a 1,4-cyclohexanediyl group substituted with a methyl group. ,4-phenylenediyl group, unsubstituted 1,4-phenylenediyl group, or unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably unsubstituted 1,4-phenylenediyl group or unsubstituted It is a substituted 1,4-trans-cyclohexanediyl group.
Furthermore, at least one of the plurality of G ¹ and G ² is preferably a divalent alicyclic hydrocarbon group, and at least one of G ¹ and G ² bonded to L ¹ or L ² More preferably, one is a divalent alicyclic hydrocarbon group.

L ¹ and L ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC=OOR ^a8 -, -N=N-, -CR ^c =CR ^d -, or C≡C-. Here, R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or OCOR ^a6-1 - . Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. L ¹ and L ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, or OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 -, or R ^a15 OC=OOR ^a16 -. Here, R ^a9 to R ^a16 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or OCOR ^a14-1 - . Here, R ^a10-1 , R ^a12-1 , and R ^a14-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. B ¹ and B ² are each independently, more preferably, a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO-, or OCOCH ₂ CH ₂ - .

From the viewpoint of expressing reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and l=2. It is preferable that k=2 and l=2 because a symmetrical structure is obtained.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by P ¹ or P ² include epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, and oxiranyl group. , and oxetanyl group. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable.

It is preferable that Ar has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and the like, with benzene rings and naphthalene rings being preferred. The aromatic heterocycles include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, and a pyrazole ring. , thiazole ring, benzothiazole ring, thienothiazole ring, oxazole ring, benzoxazole ring, and phenanthroline ring. Among these, it is preferable to have a thiazole ring, benzothiazole ring, or benzofuran ring, and more preferably to have a benzothiazole group. Further, when Ar includes a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (A), the total number N _π of π electrons contained in the divalent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, still more preferably 14 or more, and especially Preferably it is 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and still more preferably 24 or less.

Preferred examples of the aromatic group represented by Ar include the following groups.

In formulas (Ar-1) to (Ar-23), the mark * represents a connecting part, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 12 carbon atoms. group, cyano group, nitro group, alkylsulfinyl group having 1 to 12 carbon atoms, alkylsulfonyl group having 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, Alkylthio group having 1 to 12 carbon atoms, N-alkylamino group having 1 to 12 carbon atoms, N,N-dialkylamino group having 2 to 12 carbon atoms, N-alkylsulfamoyl group having 1 to 12 carbon atoms, or carbon Represents an N,N-dialkylsulfamoyl group having numbers 2 to 12.

Q ¹ , Q ² and Q ³ each independently represent -CR ^2' R ^3' -, -S-, -NH-, -NR ^2' -, -CO- or O-, and R ^2' and R ^3' each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group, or a halogen atom, and m represents an integer of 0 to 6.

Examples of the aromatic hydrocarbon group for Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group, and biphenyl group. , naphthyl group is preferred, and phenyl group is more preferred. Examples of the aromatic heterocyclic group include a group having 4 to 20 carbon atoms and containing at least one heteroatom such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group. Examples include aromatic heterocyclic groups, and furyl, thienyl, pyridinyl, thiazolyl, and benzothiazolyl groups are preferred.

Y ¹ , Y ² and Y ³ may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z ⁰ , Z ¹ and Z ² are each independently preferably a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms; ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

Q ¹ , Q ² and Q ³ are preferably -NH-, -S-, -NR ^2' -, -O-, and R ^2' is preferably a hydrogen atom. Among them, -S-, -O-, and -NH- are particularly preferred.

Among formulas (Ar-1) to (Ar-23), formulas (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.
In formulas (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . Examples of the aromatic heterocyclic group include those mentioned above as aromatic heterocycles that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, and an indole ring. ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring, etc. This aromatic heterocyclic group may have a substituent. Further, Y ¹ may be the aforementioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group, together with the nitrogen atom to which it is bonded and Z ⁰ . Examples include a benzofuran ring, a benzothiazole ring, a benzoxazole ring, and the like.

(Compound containing a group represented by formula (X))
Formula (X) is as follows. Hereinafter, a compound containing a group represented by formula (X) may be referred to as a polymerizable liquid crystal (B).
P11-B11-E11-B12-A11-B13- (X)

[In formula (X), P11 represents a polymerizable group.
A11 represents a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. The hydrogen atom contained in the divalent alicyclic hydrocarbon group and the divalent aromatic hydrocarbon group is a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group. The hydrogen atom contained in the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms may be substituted with a fluorine atom.
B11 is -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR ¹⁶ -, -NR ¹⁶ -CO-, -CO-, - CS- or a single bond. R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
B12 and B13 each independently represent -C≡C-, -CH=CH-, -CH ₂ -CH ₂ -, -O-, -S-, -C(=O)-, -C(=O ) -O-, -OC(=O)-, -OC(=O)-O-, -CH=N-, -N=CH-, -N=N-, -C(=O ) -NR ¹⁶ -, -NR ¹⁶ -C(=O)-, -OCH ₂ -, -OCF ₂ -, -CH ₂ O-, -CF ₂ O-, -CH=CH-C(=O)- Represents O-, -OC(=O)-CH=CH- or a single bond.
E11 represents an alkanediyl group having 1 to 12 carbon atoms, the hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and the hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. Furthermore, -CH ₂ - constituting the alkanediyl group may be replaced with -O- or -CO-. ]

The number of carbon atoms in the aromatic hydrocarbon group and the alicyclic hydrocarbon group of A11 is preferably in the range of 3 to 18, more preferably in the range of 5 to 12, particularly 5 or 6. preferable. As A11, cyclohexane-1,4-diyl group and 1,4-phenylene group are preferable.

E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms. -CH ₂ - constituting the alkanediyl group may be replaced with -O-.
Specifically, methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane -1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group and dodecane-1,12-diyl group Linear alkanediyl group having 1 to 12 carbon atoms such as diyl group; -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -, -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O- CH ₂ -CH ₂ - and -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -, and the like.
As B11, -O-, -S-, -CO-O-, and -O-CO- are preferable, and -CO-O- is especially preferable.
B12 and B13 are each independently -O-, -S-, -C(=O)-, -C(=O)-O-, -O-C(=O)-, -O-C (=O)-O- is preferred, and -O- or -OC(=O)-O- is particularly preferred.

The polymerizable group represented by P11 is preferably a radically polymerizable group or a cationic polymerizable group in terms of high polymerization reactivity, particularly photopolymerization reactivity, and is easy to handle and also easy to produce a liquid crystal compound. Therefore, the polymerizable group is preferably a group represented by the following formulas (P-11) to (P-15).

［式（Ｐ－１１）～（Ｐ－１５）中、
Ｒ^１７～Ｒ^２１はそれぞれ独立に、炭素数１～６のアルキル基または水素原子を表わす。］

[In formulas (P-11) to (P-15),
R ¹⁷ to R ²¹ each independently represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. ]

Specific examples of the groups represented by formulas (P-11) to (P-15) include groups represented by formulas (P-16) to (P-20) below.

P11 is preferably a group represented by formula (P-14) to formula (P-20), and more preferably a vinyl group, p-stilbene group, epoxy group or oxetanyl group.
More preferably, the group represented by P11-B11- is an acryloyloxy group or a methacryloyloxy group.

Examples of the polymerizable liquid crystal (B) include compounds represented by formula (I), formula (II), formula (III), formula (IV), formula (V), or formula (VI).
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (I)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (II)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (III)
P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (IV)
P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (V)
P11-B11-E11-B12-A11-B13-A12-F11 (VI)
(In the formula,
A12 to A14 are each independently synonymous with A11, B14 to B16 are each independently synonymous with B12, B17 is synonymous with B11, and E12 is synonymous with E11.
F11 is a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxy group, a methylol group, a formyl group, a sulfo group (-SO ₃ H) represents a carboxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and -CH ₂ - constituting the alkyl group and alkoxy group may be replaced with -O-. good. )

Specific examples of polymerizable liquid crystals (B) include "3.8.6 Network (fully cross-linked)" in the Liquid Crystal Handbook (edited by the Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000); Compounds having a polymerizable group among the compounds described in "6.5.1 Liquid crystal material b. Polymerizable nematic liquid crystal material", JP-A No. 2010-31223, JP-A No. 2010-270108, JP-A No. 2011 Examples include polymerizable liquid crystals described in JP-A-6360 and JP-A-2011-207765.

Specific examples of the polymerizable liquid crystal (B) include the following formulas (I-1) to (I-4), formulas (II-1) to (II-4), and formulas (III-1) to ( III-26), compounds represented by formula (IV-1) to formula (IV-26), formula (V-1) to formula (V-2), and formula (VI-1) to formula (VI-6) can be mentioned. In the following formula, k1 and k2 each independently represent an integer from 2 to 12. These polymerizable liquid crystals (B) are preferable in terms of their ease of synthesis or availability.

Examples of the disc-shaped polymerizable liquid crystal include a compound containing a group represented by formula (W) (hereinafter sometimes referred to as polymerizable liquid crystal (C)).

［式（Ｗ）中、Ｒ^４０は、下記式（Ｗ－１）～（Ｗ－５）を表わす。

[In formula (W), R ⁴⁰ represents the following formulas (W-1) to (W-5).

X ⁴⁰ and Z ⁴⁰ represent an alkanediyl group having 1 to 12 carbon atoms, and the hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms; The hydrogen atoms included may be substituted with halogen atoms. Furthermore, -CH ₂ - constituting the alkanediyl group may be replaced with -O- or -CO-.

Specific examples of polymerizable liquid crystals (C) include “6.5.1 Liquid crystal materials b. Polymerizable nematic liquid crystals” in the Liquid Crystal Handbook (edited by the Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000). Compounds described in "Materials Figure 6.21", polymerizable liquid crystals described in JP-A-7-258170, JP-A-7-30637, JP-A-7-309807, and JP-A-8-231470 are mentioned. It will be done.

The retardation plate 30 having the optical properties represented by formulas (1) and (2) can be obtained by polymerizing a polymerizable liquid crystal having a specific structure, by stretching a polymer film having a specific structure, Alternatively, a layer having optical properties represented by formulas (4), (6) and formula (7) and a layer having optical properties represented by formulas (5), (6) and formula (7) are combined. It can be obtained by combining them with a specific slow axis relationship.
Re(450)/Re(550)≦1.00 (1)
1.00≦Re(650)/Re(550) (2)
100nm<Re(550)<160nm (4)
200nm<Re(550)<320nm (5)
Re(450)/Re(550)≧1.00 (6)
1.00≧Re(650)/Re(550) (7)

The retardation plate 30 preferably has optical characteristics expressed by formulas (1) and (2). When the retardation plate 30 has the optical characteristics expressed by formulas (1) and (2), uniform polarization conversion characteristics can be obtained for light of each wavelength in the visible light range, and organic EL display It is possible to suppress light leakage when a display device such as a device displays black.

Examples of the polymerizable liquid crystal having the specific structure include the polymerizable liquid crystal (A). By orienting the polymerizable liquid crystal (A) so that the optical axis is horizontal to the plane of the base material, a retardation layer having optical properties represented by formulas (1) and (2) can be obtained. Furthermore, by adjusting the film thickness according to the above formula (10), it is possible to obtain a retardation layer having a desired in-plane retardation value, such as the optical property expressed by the formula (4), for example.
100nm<Re(550)<160nm (4)

A layer having optical properties represented by formulas (4), (6) and formula (7) and a layer having optical properties represented by formulas (5), (6) and formula (7) are As a method of combining in a slow axis relationship, a well-known method can be mentioned.
For example, JP-A Nos. 2001-4837, 2001-21720, and 2000-206331 disclose retardation films having at least two retardation layers made of liquid crystal compounds.

The retardation layer having the optical properties expressed by the above formulas (6) and (7) can be obtained by a well-known method. That is, a retardation layer obtained by a method other than the method of obtaining a retardation layer having optical properties represented by the above formulas (1) and (2) is generally represented by formulas (6) and (7). It has optical properties.

(First retardation layer)
The first retardation layer 31 preferably has optical properties expressed by formula (4) (herein, the retardation layer satisfying the optical properties expressed by formula (4) is referred to as "λ/4 layer"). ), more preferably having optical properties expressed by formula (4-1). The in-plane retardation value Re (550) can be adjusted by the same method as the method for adjusting the in-plane retardation value of the retardation layer.
100nm<Re(550)<160nm (4)
130nm<Re(550)<150nm (4-1)

Furthermore, the first retardation layer preferably has optical properties represented by formulas (1) and (2) (herein, optical properties represented by formulas (1) and (2)). (also called "inverse dispersion"). Such optical properties can be obtained by the same method as for the above-mentioned retardation layer.
Re(450)/Re(550)≦1.00 (1)
1.00≦Re(650)/Re(550) (2)

Further, the first retardation layer preferably includes a layer A having optical properties represented by formulas (4), (6), and (7), and a layer A having optical properties represented by formulas (5), (6), and formula (7). It has a layer B having optical properties expressed as follows. Such optical properties can be obtained by the same method as for the retardation layer described above.
100nm<Re(550)<160nm (4)
200nm<Re(550)<320nm (5)
Re(450)/Re(550)≧1.00 (6)
1.00≧Re(650)/Re(550) (7)
Layer A is preferably a layer having optical properties expressed by formula (4-1), and layer B is preferably a layer having optical properties expressed by formula (5-1).
130nm<Re(550)<150nm (4-1)
265nm<Re(550)<285nm (5-1)

Further, when the retardation plate has a third retardation layer, the first retardation layer preferably has optical characteristics expressed by formulas (6) and (7). Such optical properties can be obtained by the same method as for the retardation layer described above.
Re(450)/Re(550)≧1.00 (6)
1.00≧Re(650)/Re(550) (7)

The first retardation layer is a coating layer formed by polymerizing one or more polymerizable liquid crystals. When the first retardation layer consists of one retardation layer and has the optical properties expressed by formulas (1) and (2), the retardation layer is formed by polymerizing the polymerizable liquid crystal (A). It is preferable that the coating layer is When the second retardation layer has the optical properties represented by formulas (6) and (7), the retardation layer is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (B). .

Layer A is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (B). Layer B is preferably a coating layer formed by polymerizing the polymerizable liquid crystal (C).

The first retardation layer is a layer formed by polymerizing a polymerizable liquid crystal, and its thickness is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 μm or more and 3 μm or less. be. The thickness of the first retardation layer can be determined by measurement using an interference thickness meter, a laser microscope, or a stylus thickness meter.

(Second retardation layer)
The second retardation layer 32 preferably has optical characteristics expressed by formula (3) (positive C plate).
nx≒ny<nz (3)

The in-plane retardation value Re (550) of the second retardation layer is usually in the range of 0 to 10 nm, preferably in the range of 0 to 5 nm. The retardation value Rth in the thickness direction is usually in the range of -10 to -300 nm, preferably in the range of -20 to -200 nm. The in-plane retardation value Re (550) and the thickness direction retardation value Rth can be adjusted by the same method as for the above retardation layer.

The second retardation layer is a coating layer formed by polymerizing one or more polymerizable liquid crystals. More preferably, it is a coating layer formed by polymerizing the polymerizable liquid crystal (B).

The second retardation layer is a layer formed by polymerizing polymerizable liquid crystal, and its thickness is usually 10 μm or less, preferably 5 μm or less, and more preferably 0.3 μm or more and 3 μm or less. be. The thickness of the second retardation layer can be determined by the same method as the first retardation layer. Further, the thickness of each of the first retardation layer and the second retardation layer is preferably 5 μm or less.

(Third retardation layer)
The third retardation layer preferably has optical properties expressed by formula (5), and more preferably has optical properties expressed by formula (5-1). The in-plane retardation value Re (550) can be adjusted by the same method as the method for adjusting the in-plane retardation value of the retardation layer.
200nm<Re(550)<320nm (5)
265nm<Re(550)<285nm (5-1)

Further, the third retardation layer preferably has optical properties expressed by formulas (6) and (7). Such optical properties can be obtained by the same method as for the above-mentioned retardation layer.
Re(450)/Re(550)≧1.00 (6)
1.00≧Re(650)/Re(550) (7)

The third retardation layer is preferably a coating layer formed by polymerizing one or more polymerizable liquid crystals. More preferably, it is a coating layer formed by polymerizing the polymerizable liquid crystal (B) or (C).

The third retardation layer may be a stretched film, and in the case of a stretched film, its thickness is usually 300 μm or less, preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. When the third retardation layer is a layer formed by polymerizing a polymerizable liquid crystal, its thickness is usually 10 μm or less, preferably 5 μm or less, and more preferably 0.5 μm or more and 5 μm or less. . The thickness of the third retardation layer can be determined by the same method as the first retardation layer.

(Base material)
The retardation plate 30 may have a base material. The substrate is usually a transparent substrate. Transparent substrate refers to a substrate that has transparency that allows light, particularly visible light, to pass through, and transparency refers to the property that the transmittance for light rays with a wavelength of 380 to 780 nm is 80% or more. say. A specific example of the transparent base material is a translucent resin base material. Examples of resins constituting the translucent resin base material include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate ester; polyacrylate ester; triacetyl cellulose; Cellulose esters such as diacetyl cellulose and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide and polyphenylene oxide. From the viewpoint of availability and transparency, polyethylene terephthalate, polymethacrylate, cellulose ester, cyclic olefin resin, or polycarbonate are preferred.

The surface of the base material on which the alignment film, the first retardation layer, the second retardation layer, and the third retardation layer are formed is subjected to surface treatment before forming the alignment film or the retardation layer. Good too. Surface treatment methods include methods of treating the surface of the base material with corona or plasma under vacuum or atmospheric pressure, methods of laser treatment of the base material surface, methods of ozone treatment of the base material surface, and methods of treating the base material surface with quenching. A method of chemical treatment or a method of flame treatment of the surface of the base material, a method of primer treatment of applying a coupling agent to the surface of the base material, a method of attaching a reactive monomer or a reactive polymer to the surface of the base material, and then radiation, Examples include a graft polymerization method in which a reaction is caused by irradiating plasma or ultraviolet rays. Among these, a method in which the surface of the base material is subjected to corona or plasma treatment under vacuum or atmospheric pressure is preferred.

A method for surface treating a base material with corona or plasma is to place the base material between opposing electrodes under pressure near atmospheric pressure, generate corona or plasma, and perform surface treatment on the base material. , a method of flowing gas between opposing electrodes, turning the gas into plasma between the electrodes, and spraying the plasma-formed gas onto the substrate; and a method of generating glow discharge plasma under low pressure conditions to treat the surface of the substrate. One example is how to do this.

Among them, there are two methods: placing a base material between opposing electrodes under pressure near atmospheric pressure and generating corona or plasma to treat the surface of the base material; It is preferable to use a method in which the gas is turned into plasma between the steps, and the plasmatized gas is sprayed onto the base material. Such corona or plasma surface treatment is usually performed using commercially available surface treatment equipment.

The base material is preferably a base material with a small retardation. Examples of the base material having a small retardation include cellulose ester films having no retardation such as Zerotack (registered trademark) (Konica Minolta Opto Co., Ltd.) and ZTack (Fuji Film Co., Ltd.). Further, an unstretched cyclic olefin resin base material is also preferred.

Further, the surface of the base material on which the alignment film, the first retardation layer, the second retardation layer, and the third retardation layer are not formed may be subjected to hard coat treatment, antistatic treatment, or the like. Additionally, additives such as ultraviolet absorbers may be included within a range that does not affect performance.

The thickness of the base material is usually 5 to 300 μm, preferably 10 to 200 μm, because if it is too thin, the strength will decrease and the workability will tend to be poor.

(Polymerizable liquid crystal composition)
A layer (retardation layer) formed by polymerizing a polymerizable liquid crystal is usually formed by using a composition containing one or more polymerizable liquid crystals (hereinafter sometimes referred to as a polymerizable liquid crystal composition) as a base material. It is formed by coating on an alignment film, protective layer or retardation layer, and polymerizing the polymerizable liquid crystal in the resulting coating film.

The polymerizable liquid crystal composition usually contains a solvent, and the solvent is preferably a solvent that can dissolve the polymerizable liquid crystal and is inert to the polymerization reaction of the polymerizable liquid crystal.
Specific solvents include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, and phenol; ester solvents such as ethyl acetate and butyl acetate; acetone, methyl ethyl ketone, Ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, methyl amyl ketone, methyl isobutyl ketone, N-methyl-2-pyrrolidinone; non-chlorinated aliphatic hydrocarbon solvents such as pentane, hexane, heptane; toluene, xylene, etc. non-chlorinated aromatic hydrocarbon solvents; nitrile solvents such as acetonitrile; ether solvents such as propylene glycol monomethyl ether, tetrahydrofuran, dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These other solvents may be used alone or in combination.

The content of the solvent in the polymerizable liquid crystal composition is usually preferably 10 parts by mass to 10,000 parts by mass, more preferably 50 parts by mass to 5,000 parts by mass, based on 100 parts by mass of solid content. The solid content means the total of the components of the polymerizable liquid crystal composition excluding the solvent.

The polymerizable liquid crystal composition is usually applied by coating methods such as spin coating method, extrusion method, gravure coating method, die coating method, slit coating method, bar coating method, applicator method, or printing method such as flexographic method. This is done by a known method such as a method. After coating, a dry film is usually formed by removing the solvent under conditions such that the polymerizable liquid crystal contained in the obtained coating film does not polymerize. Examples of the drying method include natural drying, ventilation drying, heat drying, and reduced pressure drying.

(alignment film)
In this specification, the alignment film has an alignment regulating force that aligns the polymerizable liquid crystal in a desired direction.
The alignment film is preferably one that has resistance to a solvent that does not dissolve when the polymerizable liquid crystal composition is applied, etc., and also has heat resistance during heat treatment for removing the solvent and aligning the polymerizable liquid crystal. Examples of such an alignment film include an alignment film containing an alignment polymer, a photo-alignment film, and a groove alignment film in which a concavo-convex pattern or a plurality of grooves are formed on the surface for orientation.

Examples of oriented polymers include polyamides and gelatins having an amide bond in the molecule, polyimide having an imide bond in the molecule, and polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, Examples include polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylic esters. Among them, polyvinyl alcohol is preferred. Two or more types of oriented polymers may be used in combination.

An oriented film containing an oriented polymer is usually produced by applying a composition in which an oriented polymer is dissolved in a solvent (hereinafter sometimes referred to as an oriented polymer composition) to a base material, and then removing the solvent or forming an oriented film. It can be obtained by applying a polymer composition on a base material, removing the solvent, and rubbing it (rubbing method).

Examples of the solvent include water, alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, Ester solvents such as propylene glycol methyl ether acetate and ethyl lactate, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone, aliphatic hydrocarbon solvents such as pentane, hexane, and heptane, toluene, Examples include aromatic hydrocarbon solvents such as xylene, nitrile solvents such as acetonitrile, ether solvents such as tetrahydrofuran and dimethoxyethane, and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents may be used alone or in combination of two or more.

The concentration of the oriented polymer in the oriented polymer composition may be within a range that allows the oriented polymer material to be completely dissolved in the solvent, but it is preferably 0.1 to 20% in terms of solid content with respect to the solution. It is more preferably about .1 to 10%.

Commercially available alignment film materials may be used as they are as the alignment polymer composition. Commercially available alignment film materials include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.), Optomer (registered trademark, manufactured by JSR Corporation), and the like.

Methods for applying the oriented polymer composition to the substrate include coating methods such as spin coating, extrusion, gravure coating, die coating, slit coating, bar coating, and applicator methods, and flexography. Examples of known methods include printing methods such as . When the present optical film is manufactured by a roll-to-roll continuous manufacturing method described below, a printing method such as a gravure coating method, a die coating method, or a flexo method is usually adopted as the coating method.

Examples of methods for removing the solvent contained in the oriented polymer composition include natural drying, ventilation drying, heating drying, and reduced pressure drying.

In order to impart an alignment regulating force to the alignment film, rubbing can be performed as necessary (rubbing method).

As a method of imparting an orientation regulating force by a rubbing method, a rubbing cloth is wrapped around a rotating rubbing roll, and an oriented polymer composition is applied to a substrate and annealed to form an oriented polymer composition on the surface of the substrate. Examples include a method of bringing oriented polymer films into contact with each other.

In order to impart an alignment regulating force to the alignment film, photoalignment can be performed as necessary (photoalignment method).

A photo-alignment film is usually produced by coating a base material with a composition containing a polymer or monomer having a photo-reactive group and a solvent (hereinafter sometimes referred to as a "composition for forming a photo-alignment film"), and applying light ( Preferably, it is obtained by irradiating with polarized UV light. A photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated light.

The photoreactive group refers to a group that produces liquid crystal alignment ability when irradiated with light. Specifically, groups that are involved in molecular alignment induction caused by light irradiation or photoreactions that are the origin of liquid crystal alignment ability, such as isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions, can be mentioned. Among these, groups that participate in a dimerization reaction or a photocrosslinking reaction are preferable because they have excellent orientation. The photoreactive group is preferably a group having an unsaturated bond, especially a double bond, such as a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), or a nitrogen-nitrogen double bond. Particularly preferred is a group having at least one selected from the group consisting of a double bond (N=N bond) and a carbon-oxygen double bond (C=O bond).

Examples of the photoreactive group having a C═C bond include a vinyl group, a polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C=N bond include groups having structures such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N=N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having an azoxybenzene structure. Examples of the photoreactive group having a C═O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, or a halogenated alkyl group.

Among these, photoreactive groups that participate in photodimerization reactions are preferred, since the amount of polarized light irradiation required for photoalignment is relatively small, and it is easy to obtain a photoalignment film with excellent thermal stability and stability over time. Cinnamoyl and chalcone groups are preferred. As the polymer having a photoreactive group, one having a cinnamoyl group such that the end of the polymer side chain has a cinnamic acid structure is particularly preferred.

By applying the composition for forming a photo-alignment film onto a base material, a photo-alignment inducing layer can be formed on the base material. Examples of the solvent contained in the composition include those similar to those contained in the above-mentioned oriented polymer composition, and can be appropriately selected depending on the solubility of the polymer or monomer having a photoreactive group. .

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted as appropriate depending on the type of polymer or monomer and the desired thickness of the photo-alignment film, but it should be at least 0.2% by mass. It is preferably in the range of 0.3 to 10% by mass. The composition for forming a photo-alignment film may contain a polymeric material such as polyvinyl alcohol or polyimide, and a photosensitizer as long as the properties of the photo-alignment film are not significantly impaired.

Examples of the method for applying the photo-alignment film-forming composition to the substrate include the same method as the method for applying the alignment polymer composition to the substrate. Examples of the method for removing the solvent from the applied composition for forming a photo-alignment film include the same method as the method for removing the solvent from the alignment polymer composition.

In order to irradiate polarized light, polarized UV can be directly irradiated onto the photo-alignment film forming composition coated on the substrate, from which the solvent has been removed, or the polarized light can be irradiated from the substrate side, allowing the polarized light to pass through. It may also be a form of irradiation. Moreover, it is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range in which a photoreactive group of a polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) having a wavelength in the range of 250 to 400 nm is particularly preferred. Light sources used for polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. Lamps are more preferred. These lamps are preferable because they emit a high intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV can be irradiated by passing the light from the light source through a suitable polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

Note that by performing masking when performing rubbing or polarized light irradiation, it is also possible to form a plurality of regions (patterns) in which the directions of liquid crystal alignment are different.

A groove alignment film is a film in which liquid crystal alignment can be obtained by a concavo-convex pattern or a plurality of grooves on the film surface. H. V. Kennel et al. reported the fact that when liquid crystal molecules are placed on a substrate that has a plurality of linear grooves lined up at equal intervals, the liquid crystal molecules align in the direction along the grooves ( Physical Review A24(5), page 2713, 1981).

A specific example of obtaining a groove alignment film is to expose the photosensitive polyimide surface to light through an exposure mask having slits in a periodic pattern, and then perform development and rinsing to remove unnecessary polyimide films and create uneven surfaces. A method of forming a pattern, a method of forming a UV-cured resin layer on a plate-shaped master having grooves on the surface, transferring the resin layer to a base film and then curing it, and transporting the base film on which the UV-cured resin layer has been formed. However, there is a method in which a roll-shaped master having a plurality of grooves is pressed against the surface of the UV-cured resin layer to form unevenness and then cured, such as methods described in JP-A-6-34976 and JP-A-2011-242743. method etc. can be used.

Among the above methods, a method in which a roll-shaped master having a plurality of grooves is pressed against the surface of the UV-cured resin layer to form irregularities and then cured is preferred. As the rolled master, stainless steel (SUS) can be used from the viewpoint of durability.

As the UV curing resin, a monofunctional acrylate polymer, a polyfunctional acrylate polymer, or a mixture thereof can be used.
Monofunctional acrylate refers to a group selected from the group consisting of acryloyloxy group (CH2=CH-COO-) and methacryloyloxy group (CH2=C(CH3)-COO-) (hereinafter referred to as (meth)acryloyloxy group) ) is a compound that has one compound in its molecule.

Monofunctional acrylates having one (meth)acryloyloxy group include alkyl (meth)acrylates having 4 to 16 carbon atoms, β-carboxyalkyl (meth)acrylates having 2 to 14 carbon atoms, and alkylated carbon atoms having 2 to 14 carbon atoms. Examples include phenyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, and isobonyl (meth)acrylate.

Polyfunctional acrylate is usually a compound having 2 to 6 (meth)acryloyloxy groups in the molecule.

As the bifunctional acrylate having two (meth)acryloyloxy groups, 1,3-butanediol di(meth)acrylate; 1,3-butanediol (meth)acrylate; 1,6-hexanediol di(meth)acrylate ; Ethylene glycol di(meth)acrylate; Diethylene glycol di(meth)acrylate; Neopentyl glycol di(meth)acrylate; Triethylene glycol di(meth)acrylate; Tetraethylene glycol di(meth)acrylate; Polyethylene glycol diacrylate; Bisphenol A bis(acryloyloxyethyl) ether; ethoxylated bisphenol A di(meth)acrylate; propoxylated neopentyl glycol di(meth)acrylate; ethoxylated neopentyl glycol di(meth)acrylate and 3-methylpentanediol di(meth)acrylate; ) Acrylate etc. are exemplified.

Polyfunctional acrylates having 3 to 6 (meth)acryloyloxy groups include trimethylolpropane tri(meth)acrylate; pentaerythritol tri(meth)acrylate; tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate ; Ethoxylated trimethylolpropane tri(meth)acrylate; Propoxylated trimethylolpropane tri(meth)acrylate; Pentaerythritol tetra(meth)acrylate; Dipentaerythritol penta(meth)acrylate; Dipentaerythritol hexa(meth)acrylate; Pentaerythritol tetra(meth)acrylate; Tripentaerythritol penta(meth)acrylate; Tripentaerythritol hexa(meth)acrylate; Tripentaerythritol hepta(meth)acrylate; Tripentaerythritol octa(meth)acrylate; Pentaerythritol tri(meth)acrylate Reaction product of acrylate and acid anhydride; Reaction product of dipentaerythritol penta(meth)acrylate and acid anhydride; Reaction product of tripentaerythritol hepta(meth)acrylate and acid anhydride; Caprolactone-modified trimethylolpropane tri (meth)acrylate; caprolactone-modified pentaerythritol tri(meth)acrylate; caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; caprolactone-modified pentaerythritol tetra(meth)acrylate; caprolactone-modified dipentaerythritol penta(meth)acrylate; ) acrylate; caprolactone-modified dipentaerythritol hexa(meth)acrylate; caprolactone-modified tripentaerythritol tetra(meth)acrylate; caprolactone-modified tripentaerythritol penta(meth)acrylate; caprolactone-modified tripentaerythritol hexa(meth)acrylate; caprolactone-modified tri- Pentaerythritol hepta(meth)acrylate; Caprolactone-modified tripentaerythritol octa(meth)acrylate; Reaction product of caprolactone-modified pentaerythritol tri(meth)acrylate and acid anhydride; Caprolactone-modified dipentaerythritol penta(meth)acrylate and acid anhydride and caprolactone-modified tripentaerythritol hepta(meth)acrylate and acid anhydrides. In addition, in the specific example of the polyfunctional acrylate shown here, (meth)acrylate means acrylate or methacrylate. Moreover, caprolactone modification means that a ring-opened product or a ring-opened polymer of caprolactone is introduced between the alcohol-derived moiety of the (meth)acrylate compound and the (meth)acryloyloxy group.

Commercially available products can also be used as such polyfunctional acrylates. Such commercial products include A-DOD-N, A-HD-N, A-NOD-N, APG-100, APG-200, APG-400, A-GLY-9E, A-GLY-20E, A- TMM-3, A-TMPT, AD-TMP, ATM-35E, A-TMMT, A-9550, A-DPH, HD-N, NOD-N, NPG, TMPT (manufactured by Shin Nakamura Chemical Co., Ltd.), "ARONIXM" -220", "M-325", "M-240", "M-270", "M-309", "M-310", "M-321", "M-350" ", "M-360", "M-305", "M-306", "M-450", "M-451", "M-408", "M-400" , "M-402", "M-403", "M-404", "M-405", "M-406" (manufactured by Toagosei Co., Ltd.), "EBECRYL11", "145" ", "150", "40", "140", "180", DPGDA, HDDA, TPGDA, HPNDA, PETIA, PETRA, TMPTA, TMPEOTA, DPHA, EBECRYL series (manufactured by Daicel Cytec Corporation) etc. can be mentioned.

Regarding the unevenness of the groove alignment film, the width of the convex portion is preferably 0.05 to 5 μm, the width of the concave portion is preferably 0.1 to 5 μm, and the depth of the step of the unevenness is preferably 2 μm or less, preferably is preferably 0.01 to 1 μm or less. Within this range, liquid crystal alignment with little alignment disorder can be obtained.

The thickness of the alignment film is usually in the range of 10 nm to 10,000 nm, preferably in the range of 10 nm to 1,000 nm, more preferably 500 nm or less, and even more preferably in the range of 10 nm to 500 nm.

The liquid crystal alignment of the polymerizable liquid crystal is controlled by the properties of the alignment film and the polymerizable liquid crystal. For example, if the alignment film is a material that exhibits a horizontal alignment regulating force as an alignment regulating force, the polymerizable liquid crystal can form a horizontal alignment or a hybrid alignment, and if the alignment film is a material that exhibits a vertical alignment regulating force, it can be polymerized. The liquid crystals can be vertically aligned or tilted. If the alignment film is made of an oriented polymer, the alignment regulating force can be adjusted arbitrarily by changing the surface condition and rubbing conditions, and if it is made of a photo-alignable polymer, it can be adjusted by changing the polarized light irradiation conditions. It is possible to arbitrarily adjust it by etc. Moreover, liquid crystal alignment can also be controlled by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal.

The polymerizable liquid crystal can be polymerized by a known method of polymerizing a compound having a polymerizable functional group. Specific examples include thermal polymerization and photopolymerization, with photopolymerization being preferred from the viewpoint of ease of polymerization. When polymerizing a polymerizable liquid crystal by photopolymerization, a polymerizable liquid crystal composition containing a photopolymerization initiator is applied and dried to bring the polymerizable liquid crystal in the dry film into a liquid crystal phase state. It is preferable to carry out photopolymerization while maintaining the .

Photopolymerization is usually carried out by irradiating the dry film with light. The light to be irradiated is appropriately selected depending on the type of photopolymerization initiator contained in the dry film, the type of polymerizable liquid crystal (especially the type of photopolymerizable group possessed by the polymerizable liquid crystal), and the amount thereof. Examples include light selected from the group consisting of visible light, ultraviolet light and laser light, and active electron beams. Among these, ultraviolet light is preferable because it is easy to control the progress of the polymerization reaction and it is possible to use photopolymerization equipment that is widely used in the field. It is preferable to select the types of polymerizable liquid crystal and photopolymerization initiator. Furthermore, during polymerization, the polymerization temperature can be controlled by irradiating light while cooling the dry film using an appropriate cooling means. By employing such a cooling means and polymerizing the polymerizable liquid crystal at a lower temperature, a retardation layer can be appropriately formed even if a base material with relatively low heat resistance is used. A patterned retardation layer can also be obtained by performing masking or development during photopolymerization.

The polymerizable liquid crystal composition may also contain a reactive additive. The reactive additive preferably has a carbon-carbon unsaturated bond and an active hydrogen-reactive group in its molecule. The term "active hydrogen-reactive group" as used herein refers to a group that is reactive with groups having active hydrogen, such as carboxyl group (-COOH), hydroxyl group (-OH), and amino group (-NH2). Representative examples thereof include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, and a maleic anhydride group. The number of carbon-carbon unsaturated bonds and active hydrogen-reactive groups that the reactive additive has is usually 1 to 20 each, preferably 1 to 10 each.

In the reactive additive, it is preferable that at least two active hydrogen-reactive groups exist, and in this case, the plurality of active hydrogen-reactive groups may be the same or different.

The carbon-carbon unsaturated bond possessed by the reactive additive may be a carbon-carbon double bond, a carbon-carbon triple bond, or a combination thereof, and is preferably a carbon-carbon double bond. Among these, the reactive additive preferably contains a carbon-carbon unsaturated bond as a vinyl group and/or (meth)acrylic group. Further, it is preferable that the active hydrogen-reactive group is at least one selected from the group consisting of an epoxy group, a glycidyl group, and an isocyanate group, and a reactive additive having an acrylic group and an isocyanate group is particularly preferable.

Specific examples of reactive additives include compounds having a (meth)acrylic group and an epoxy group, such as methacryloxyglycidyl ether and acryloxyglycidyl ether; Compounds having a (meth)acrylic group and a lactone group, such as lactone acrylate and lactone methacrylate; Compounds having a vinyl group and an oxazoline group, such as vinyloxazoline and isopropenyloxazoline; Isocyanatomethyl acrylate Examples include oligomers of compounds having a (meth)acrylic group and an isocyanate group, such as isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate, and 20-isocyanatoethyl methacrylate. Other examples include compounds having a vinyl group or vinylene group and an acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride, and vinyl maleic anhydride. Among them, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyloxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate and the aforementioned oligomers are preferred, and isocyanatomethyl acrylate, Particular preference is given to 2-isocyanatoethyl acrylate and the oligomers mentioned above.

［式（Ｙ）中、
ｎは１～１０までの整数を表わし、Ｒ１’は、炭素数２～２０の２価の脂肪族又は脂環式炭化水素基、或いは炭素数５～２０の２価の芳香族炭化水素基を表わす。各繰り返し単位にある２つのＲ２’は、一方が－ＮＨ－であり、他方が＞Ｎ－Ｃ（＝Ｏ）－Ｒ３’で示される基である。Ｒ３’は、水酸基又は炭素－炭素不飽和結合を有する基を表す。
式（Ｙ）中のＲ３’のうち、少なくとも１つのＲ３’は炭素－炭素不飽和結合を有する
基である。］ Specifically, a compound represented by the following formula (Y) is preferred.

[In formula (Y),
n represents an integer from 1 to 10, and R1' represents a divalent aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 5 to 20 carbon atoms. represent. One of the two R2's in each repeating unit is -NH-, and the other is a group represented by >N-C(=O)-R3'. R3' represents a hydroxyl group or a group having a carbon-carbon unsaturated bond.
Among R3's in formula (Y), at least one R3' is a group having a carbon-carbon unsaturated bond. ]

Among the reactive additives represented by the formula (Y), the compound represented by the following formula (YY) (hereinafter sometimes referred to as compound (YY)) is particularly preferable (n is (same meaning as above).

化合物（ＹＹ）には、市販品をそのまま又は必要に応じて精製して用いることができる。市販品としては、例えば、Ｌａｒｏｍｅｒ（登録商標）ＬＲ－９０００（ＢＡＳＦ社製）が挙げられる。

As the compound (YY), a commercially available product can be used as it is or after being purified if necessary. Examples of commercially available products include Laromer (registered trademark) LR-9000 (manufactured by BASF).

When the polymerizable liquid crystal composition contains a reactive additive, the content thereof is usually 0.1 parts by mass to 30 parts by mass, preferably 0.1 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. ~5 parts by mass.

The polymerizable liquid crystal composition preferably contains one or more leveling agents. The leveling agent has the function of adjusting the fluidity of the polymerizable liquid crystal composition and making the coating film obtained by applying the polymerizable liquid crystal composition more flat. It will be done. The leveling agent is preferably at least one selected from the group consisting of a leveling agent containing a polyacrylate compound as a main component and a leveling agent containing a fluorine atom-containing compound as a main component.

Leveling agents containing polyacrylate compounds as main ingredients include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", BYK-361N”, “BYK-380”, “BYK-381” and “BYK-392” [BYK Chemie].

Leveling agents whose main component is a fluorine atom-containing compound include "Megafac (registered trademark) R-08", "Megafac (registered trademark) R-30", "Megafac (registered trademark) R-30", "Megafac (registered trademark) R-90", "Megafac (registered trademark)" "F-410", "Megafac (registered trademark)" -411", "F-443", "F-445", "F-470", "F-471", "F-477", "F-479", "F-" 482" and "F-483" [DIC Corporation]; "Surflon (registered trademark) S-381", "S-382", "S-383", "S-393", "Surflon (registered trademark) S-381", "S-382", "S-383", "S-393", "SC-101", "SC-105", "KH-40" and "SA-100" [AGC Seimi Chemical Co., Ltd.]; "E1830", "E5844" [Daikin Fine Chemical Research Institute Co., Ltd.]; Examples include "F-TOP EF301", "F-TOP EF303", "F-TOP EF351" and "F-TOP EF352" [Mitsubishi Materials Electronic Chemicals Co., Ltd.].

When the polymerizable liquid crystal composition contains a leveling agent, the content is preferably 0.01 parts by mass or more and 5 parts by mass or less, and 0.05 parts by mass or more and 5 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal. The following is more preferable, and 0.05 parts by mass or more and 3 parts by mass or less is even more preferable. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal, and the resulting polarizing layer tends to be smoother. When the content of the leveling agent in the polymerizable liquid crystal is within the above range, the obtained retardation layer tends to be less likely to have unevenness.

The polymerizable liquid crystal composition preferably contains one or more polymerization initiators. The polymerization initiator is a compound that can initiate the polymerization reaction of the polymerizable liquid crystal, and a photopolymerization initiator is preferable because it can initiate the polymerization reaction under lower temperature conditions. Specifically, photopolymerization initiators that can generate active radicals or acids by the action of light can be mentioned, and among them, photopolymerization initiators that can generate radicals by the action of light are preferred.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and sulfonium salts.

Benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of benzophenone compounds include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone. and 2,4,6-trimethylbenzophenone.

Examples of alkylphenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane. -1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[ 4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexylphenylketone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one Examples include oligomers.

Examples of the acylphosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

As triazine compounds, 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl) -1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2 -(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3 ,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine and 2,4-bis(trichloromethyl) -6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine is mentioned.

A commercially available polymerization initiator can be used. Commercially available polymerization initiators include "Irgacure (registered trademark) 907", "Irgacure (registered trademark) 184", "Irgacure (registered trademark) 651", "Irgacure (registered trademark) 819", and "Irgacure (registered trademark)". (registered trademark) 250”, “Irgacure (registered trademark) 369” (Ciba Japan Co., Ltd.); “Seiqual (registered trademark) BZ”, “Seiqual (registered trademark) Z”, “Seiqual (registered trademark) BEE” ( Seiko Chemical Co., Ltd.); “Kayacure (registered trademark) BP100” (Nippon Kayaku Co., Ltd.); “Kayacure (registered trademark) UVI-6992” (manufactured by Dow Corporation); “Adeka Optomer SP-152” "," "ADEKA Optomer SP-170" (ADEKA Co., Ltd.); "TAZ-A", "TAZ-PP" (Japan Siberhegner Co., Ltd.); and "TAZ-104" (Sanwa Chemical Co., Ltd.).

When the polymerizable liquid crystal composition contains a polymerization initiator, the content can be adjusted as appropriate depending on the type and amount of polymerizable liquid crystal contained in the composition, but it is The amount is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight. If the content of the polymerizable initiator is within this range, polymerization can be carried out without disturbing the orientation of the polymerizable liquid crystal.

When the polymerizable liquid crystal composition contains a photopolymerization initiator, the composition may further contain a photosensitizer. Examples of photosensitizers include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and anthracene containing an alkoxy group (e.g., dibutoxyanthracene, etc.); Includes phenothiazines and rubrene.

When the polymerizable liquid crystal composition contains a photopolymerization initiator and a photosensitizer, the polymerization reaction of the polymerizable liquid crystal contained in the composition can be further promoted. The amount of the photosensitizer used can be adjusted as appropriate depending on the type and amount of the photopolymerization initiator and polymerizable liquid crystal, but is preferably 0.1 to 30 parts by weight based on 100 parts by weight of the polymerizable liquid crystal. More preferably 0.5 to 10 parts by weight, even more preferably 0.5 to 8 parts by weight.

In order to make the polymerization reaction of the polymerizable liquid crystal proceed more stably, the polymerizable liquid crystal composition may contain an appropriate amount of a polymerization inhibitor, which makes it easier to control the degree of progress of the polymerization reaction of the polymerizable liquid crystal. Become.

Examples of polymerization inhibitors include radical scavengers such as hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (such as butylcatechol), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical. ; thiophenols; β-naphthylamines and β-naphthols.

When the polymerizable liquid crystal composition contains a polymerization inhibitor, the content can be adjusted as appropriate depending on the type and amount of the polymerizable liquid crystal, the amount of photosensitizer used, etc. 0.1 to 30 parts by weight is preferable, more preferably 0.5 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight. If the content of the polymerization inhibitor is within this range, polymerization can be carried out without disturbing the orientation of the polymerizable liquid crystal.

[Method for manufacturing retardation plate]
When manufacturing a retardation plate, the order of forming the first retardation layer, the second retardation layer, and the third retardation layer is arbitrary. Further, the order in which the layers A and B in the first retardation layer are formed is also arbitrary.

A layer A is formed on the base material with or without an alignment film, a layer B is formed on the layer A with or without an alignment film, and an alignment film is formed on the layer B. The second retardation layer may be formed with or without a film.
A layer B is formed on the base material with or without an alignment film, a layer A is formed on the layer B with or without an alignment film, and an alignment film is formed on the layer A. The second retardation layer may be formed with or without a film.
A second retardation layer is formed on the substrate with or without an alignment film, a layer A is formed on the second retardation layer with or without an alignment film, and the layer A is formed on the second retardation layer with or without an alignment film. Layer B may be formed on layer A with or without an alignment film.
forming a second retardation layer on the base material with or without an alignment film; forming a layer B on the second retardation layer with or without an alignment film; Layer A may be formed on layer B with or without an alignment film.
A layer A is formed on one side of the base material with or without an alignment film, a layer B is formed on the layer A with or without an alignment film, and a layer B is formed on the other side of the base material. A second retardation layer may be formed on the surface with or without an alignment film.
A layer B is formed on one side of the base material with or without an alignment film, a layer A is formed on the layer B with or without an alignment film, and a layer A is formed on the other side of the base material. A second retardation layer may be formed on the surface with or without an alignment film.

When layer B is formed on layer A with or without an alignment film, or when layer A is formed on layer B with or without an alignment film, layer A and There may be a protective layer between layer B and layer B. Further, when layer A is formed on the second retardation layer with or without an alignment film, layer A is formed on the second retardation layer with or without an alignment film. In this case, the second retardation layer is formed on layer A with or without an alignment film, or the second retardation layer is formed on layer B with or without an alignment film. If so, there may be a protective layer between the second retardation layer and layer A or layer B.

A first retardation layer is formed on the base material with or without an alignment film, and a second retardation layer is formed on the first retardation layer with or without an alignment film. A third retardation layer may be formed on the second retardation layer with or without an alignment film.
A third retardation layer is formed on the base material with or without an alignment film, and a second retardation layer is formed on the third retardation layer with or without an alignment film. A first retardation layer may be formed on the second retardation layer with or without an alignment film. A first retardation layer is formed on one surface of the base material with or without an alignment film, and a second retardation layer is formed on the first retardation layer with or without an alignment film. may be formed, and a third retardation layer may be formed on the other surface of the base material with or without an alignment film.
A second retardation layer is formed on one surface of the base material with or without an alignment film, and a first retardation layer is formed on the second retardation layer with or without an alignment film. may be formed, and a third retardation layer may be formed on the other surface of the base material with or without an alignment film.
A third retardation layer is formed on one surface of the base material with or without an alignment film, and a second retardation layer is formed on the third retardation layer with or without an alignment film. may be formed, and the first retardation layer may be formed on the other surface of the base material with or without an alignment film.
A second retardation layer is formed on one surface of the base material with or without an alignment film, and a third retardation layer is formed on the second retardation layer with or without an alignment film. may be formed, and the first retardation layer may be formed on the other surface of the base material with or without an alignment film.

A first retardation layer is formed on the base material with or without an alignment film, and a second retardation layer is formed on the first retardation layer with or without an alignment film. Good too.
A second retardation layer is formed on one surface of the base material with or without an alignment film, and a first retardation layer is formed on the second retardation layer with or without an alignment film. may be formed.
A second retardation layer is formed on one surface of the base material with or without an alignment film, and a first retardation layer is formed on the other surface of the base material with or without an alignment film. You may.

When the second retardation layer is formed on the first retardation layer with or without an alignment film, or when the second retardation layer is formed on the second retardation layer with or without an alignment film, the first retardation layer is formed on the first retardation layer. When a retardation layer is formed, a protective layer may be provided between the first retardation layer and the second retardation layer. Further, when a third retardation layer is formed on the second retardation layer with or without an alignment film, or when a third retardation layer is formed on the third retardation layer with or without an alignment film, When two retardation layers are formed, a protective layer may be provided between the second retardation layer and the third retardation layer.

(protective layer)
The protective layer is usually made of acrylic oligomers or polymers made of polyfunctional acrylates (methacrylates), urethane acrylates, polyester acrylates, epoxy acrylates, etc., polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyvinylpyrrolidone, starches, methylcellulose, carboxylic The protective layer is preferably formed from a composition for forming a protective layer containing a water-soluble polymer such as methylcellulose or sodium alginate and a solvent.

Examples of the solvent contained in the composition for forming a protective layer include the same solvents as those described above, and among them, at least one solvent selected from the group consisting of water, an alcohol solvent, and an ether solvent forms the protective layer. This is preferable because it does not cause the layer to dissolve. Alcohol solvents include methanol, ethanol, butanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether and propylene glycol monomethyl ether. Ether solvents include ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate. Among these, ethanol, isopropyl alcohol, propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate are preferred.

The thickness of the protective layer is usually 20 μm or less. The thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less. The thickness of the protective layer can usually be determined by measurement using an interference thickness meter, a laser microscope, or a stylus thickness meter.

Next, a method for continuously manufacturing a retardation plate will be described. A preferred method for continuously manufacturing the present optical film is a roll-to-roll method. Here, we will explain a method for manufacturing a retardation layer formed by polymerizing a polymerizable liquid crystal, but instead of a retardation layer formed by polymerizing a polymerizable liquid crystal, a retardation layer made of a stretched film is used. In this case, "coating a polymerizable liquid crystal composition" in the manufacturing process described below may be replaced with "laminating a stretched film".
Further, although a manufacturing method of a typical configuration is illustrated below, other configurations may be implemented according to the manufacturing method described below.

(1) A step of preparing a roll in which a base material is wound around a core,
(2) a step of continuously feeding out the base material from the roll;
(3) a step of continuously forming an alignment film on the base material;
(4) applying a polymerizable liquid crystal composition on the alignment film to continuously form a first retardation layer;
(5) Continuously forming a protective layer on the first retardation layer obtained in (4) above,
(6) a step of continuously forming an alignment film on the protective layer obtained in (5) above;
(7) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in (6) above to continuously form a second retardation layer;
(8) A method may be mentioned in which the optical film obtained continuously is wound around a second core, and the steps of obtaining a second roll are performed in order. Note that steps (3), (5), and (6) may be omitted if necessary, and in this case, "on the alignment film" in step (4) refers to "on the base material". In step (6), the "protective layer obtained in step (5)" is added to "the first retardation layer", and in step (7), "the alignment film obtained in step (6)" is added to "the first retardation layer". "first retardation layer" or "protective layer obtained in (5) above". Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step.

Also,
(1a) preparing a roll in which the base material is wound around a core;
(2a) continuously feeding out the base material from the roll;
(3a) Continuously forming an alignment film on the base material,
(4a) applying a polymerizable liquid crystal composition on the alignment film to continuously form a second retardation layer;
(5a) Continuously forming a protective layer on the second retardation layer obtained in (4a),
(6a) Continuously forming an alignment film on the protective layer obtained in (5a),
(7a) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in (6a) to continuously form a first retardation layer;
(8a) There is also a method in which the optical film obtained continuously is wound around a second core, and the steps of obtaining a second roll are sequentially performed. Note that steps (3a), (5a), and (6a) may be omitted if necessary, and in this case, "on the alignment film" in step (4a) refers to "on the base material". In step (6a), the "protective layer obtained in (5a)" is added to "the second retardation layer", and in step (7a), "the alignment film obtained in (6a)" is added to "the second retardation layer". "second retardation layer" or "protective layer obtained in (5a) above". Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step.

Also,
(1b) preparing a roll in which the base material is wound around a core;
(2b) continuously feeding out the base material from the roll;
(3b) Continuously forming an alignment film on the base material,
(4b) applying a polymerizable liquid crystal composition on the alignment film to continuously form a first retardation layer;
(5b) Continuously forming an alignment film on the base material surface opposite to the first retardation layer obtained in (4b),
(6b) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in the above (5b) to continuously form a second retardation layer;
(7b) A method of sequentially performing the step of winding up the optical film obtained continuously onto a second core to obtain a second roll is also exemplified. Note that steps (3b) and (5b) may be omitted if necessary, and in this case, "on the alignment film" in step (4b) means "on the substrate" in step (6b). ), "on the alignment film obtained in (5b) above" is replaced with "on the base material surface opposite to the first retardation layer obtained in (4b) above". Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step.

Also,
(1c) preparing a roll in which a transparent base material is wound around a core;
(2c) continuously feeding out the transparent base material from the roll;
(3c) a step of continuously forming an alignment film on the transparent substrate;
(4c) applying a polymerizable liquid crystal composition on the alignment film to continuously form a second retardation layer;
(5c) a step of continuously forming an alignment film on the substrate surface opposite to the second retardation layer obtained in (4c);
(6c) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in (5c) to continuously form a first retardation layer;
(7c) A method of sequentially performing the step of winding up the optical film obtained continuously onto a second core to obtain a second roll is also exemplified. Note that steps (3c) and (5c) may be omitted if necessary, and in this case, "on the alignment film" in step (4c) means "on the base material" in step (6c). ), "on the alignment film obtained in (5c) above" is replaced with "on the base material surface opposite to the second retardation layer obtained in (4c) above". Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step.

Also,
(1d) preparing a roll in which the base material is wound around a core;
(2d) continuously feeding out the base material from the roll;
(3d) continuously forming an alignment film on the base material,
(4d) applying a polymerizable liquid crystal composition on the alignment film to continuously form layer A;
(5d) Continuously forming a protective layer on layer A obtained in (4d),
(6d) Continuously forming an alignment film on the protective layer obtained in (5d),
(7d) Applying a polymerizable liquid crystal composition on the alignment film obtained in (6d) above to continuously form layer B;
(8d) Continuously forming a protective layer on layer B obtained in (7d),
(9d) Continuously forming an alignment film on the protective layer obtained in (8d),
(10d) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in (9d) to continuously form a second retardation layer;
(11d) A method may be mentioned in which the optical film obtained continuously is wound around a second core, and the steps of obtaining a second roll are sequentially performed. Note that steps (3d), (5d), (6d), (8d), and (9d) may be omitted as necessary, and in this case, "on the alignment film" in step (4d) "on the base material", in step (6d) "the protective layer obtained in the above (5d)" is "on the layer A", in the step (7d) "the protective layer obtained in the above (6d)" The "alignment film" is added to "the layer A" or the "protective layer obtained in step (5d) above", and the "protective layer obtained in step (8d)" in step (9d) is added to "the layer B". In step (10d), "the alignment film obtained in (9d) above" is read as "the layer B" or "the protective layer obtained in (9d) above". Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step.

Also,
(1e) preparing a roll in which the base material is wound around a core;
(2e) continuously feeding out the base material from the roll;
(3e) Continuously forming an alignment film on the base material,
(4e) applying a polymerizable liquid crystal composition on the alignment film to continuously form a first retardation layer;
(5e) Continuously forming a protective layer on the first retardation layer obtained in (4e),
(6e) Continuously forming an alignment film on the protective layer obtained in (5e),
(7e) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in the above (6e) to continuously form a second retardation layer;
(8e) Continuously forming an alignment film on the surface of the base material opposite to the first retardation layer obtained in (4e),
(9e) a step of applying a polymerizable liquid crystal composition on the alignment film obtained in (8e) to continuously form a third retardation layer;
(10e) There is also a method in which the optical film obtained continuously is wound around a second core, and the steps of obtaining a second roll are sequentially performed. In addition,
Steps (3e), (5e), and (8e) may be omitted if necessary, and in this case, "on the alignment film" in step (4e) means "on the base material" in step ( The "protective layer obtained in step (5e) above" in step 6e) is added to the "first retardation layer obtained in step (4e) above" in step (9e), "the protective layer obtained in step (8e) above""On the film" should be read as "on the base material surface opposite to the first retardation layer obtained in (4e) above." Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step. Further, in order to suppress wrinkles and curls during transportation, a protective film may be laminated when the film is transported in each step.

FIG. 2 is a schematic cross-sectional view schematically showing a specific example of the retardation plate 30. FIG. 2A shows a retardation plate 30 in which a first retardation layer 31 and a second retardation layer 32 are laminated. FIG. 2B shows a retardation plate 30 in which a base material 33, a first retardation layer 31, and a second retardation layer 32 are laminated in this order. FIG. 2C shows a retardation plate 30 in which a base material 33, a second retardation layer 32, and a first retardation layer 31 are laminated in this order. FIG. 2D shows a retardation plate 30 in which a first retardation layer 31, a base material 33, and a second retardation layer are laminated in this order.

By removing the base material from the retardation plate 30 having the base material 33, it is possible to obtain the retardation plate 30 without the base material (FIG. 2(a)).

Further, the retardation plate 30 can also be manufactured by bonding the base material 33 having the first retardation layer 31 and the base material 33' having the second retardation layer 32. Specific examples include FIG. 2(e), FIG. 2(f), and FIG. 2(g). For bonding, a bonding layer (hereinafter, the bonding layer used for bonding between layers within the retardation plate 30 is also referred to as a "third bonding layer") can be used.

FIG. 3 is a schematic cross-sectional view schematically showing a specific example of the retardation plate 30 when the first retardation layer is composed of layers A and B, or when it has a third retardation layer. . FIG. 3A shows a retardation plate 30 in which layer A 34, layer B 35, and second retardation layer 32 are laminated in this order. FIG. 3(b) shows a retardation plate 30 in which layer B35, layer A34, and second retardation layer 32 are laminated in this order. FIG. 3C shows a retardation plate 30 in which a base material 33, a layer A34, a layer B35, and a second retardation layer 32 are laminated in this order. FIG. 3D shows a retardation plate 30 in which a base material 33, a first retardation layer 31, a second retardation layer 32, and a third retardation layer 38 are laminated in this order. FIG. 3E shows a retardation plate 30 in which a base material 33, a layer B35, a layer A34, and a second retardation layer 32 are laminated in this order. FIG. 3F shows a retardation plate 30 in which a base material 33, a third retardation layer 38, a second retardation layer 32, and a first retardation layer 31 are laminated in this order. FIG. 3G shows a retardation plate 30 in which a base material 33, a second retardation 32, a layer B35, and a layer A34 are laminated in this order. FIG. 3(h) shows a retardation plate 30 in which a base material 33, a second retardation 32, a layer A34, and a layer B35 are laminated in this order. By peeling the base material 33 from the retardation plate 30 having the base material 33, it is also possible to obtain the retardation plate 30 (FIGS. 3A and 3B) without the base material 33.

In the case of a structure including the first retardation layer 31, layer A34, and layer B35, or in the case of having the third retardation layer 33, the respective layers may be laminated on both sides of the base material 33. As a specific example, for example, FIG. 3(i) shows a retardation plate 30 in which a second retardation layer 32, a base material 33, a layer A34, and a layer B35 are laminated in this order. FIG. 3(j) shows a retardation plate 30 in which the second retardation layer 32, the base material 33, the layer B35, and the layer A34 are laminated in this order. FIG. 3(k) shows a retardation plate 30 in which a first retardation layer 31, a base material 33, a third retardation layer 38, and a second retardation layer 32 are laminated in this order. FIG. 3(l) shows a retardation plate 30 in which a first retardation layer 31, a base material 33, a second retardation layer 32, and a third retardation layer 38 are laminated in this order. FIG. 3(m) shows a retardation plate 30 in which a third retardation layer 38, a base material 33, a first retardation layer 31, and a second retardation layer 32 are laminated in this order. FIG. 3(n) shows a retardation plate 30 in which a third retardation layer 38, a base material 33, a second retardation layer 32, and a first retardation layer 31 are laminated in this order. The second retardation layer 32, layer A34, and layer B35 may be formed by direct coating on each layer, each layer may be bonded together after manufacturing, or each layer may be sequentially laminated by transfer. .

The retardation plate 30 may have a structure with another intervening layer between the first retardation layer 31 and the second retardation layer 32, or may have a structure without another intervening layer. good. Other intervening layers include the base material 33, the above-mentioned protective layer, the above-mentioned alignment film, and the third bonding layer. In a configuration in which the retardation plate 30 has only an alignment film as an intervening layer between the first retardation layer 31 and the second retardation layer 32, or in a configuration in which there is no other intervening layer, The puncture modulus tends to be 35 g/mm or more. In the present specification, the layer interposed between the first retardation layer 31 and the second retardation layer 32 is a layer that extends from the outermost surface of the first retardation layer 31 on the second retardation layer 32 side to the second retardation layer 32. 32 and the outermost surface on the first retardation layer 31 side. Therefore, when the first retardation layer 31 is composed of layer A and layer B, the layer interposed between layer A and layer B is the layer between the first retardation layer 31 and the second retardation layer 32. It is not considered to be an intervening layer.

[Second lamination layer, third lamination layer]
The second bonding layer is a bonding layer used for bonding layers within the linearly polarizing plate 10, and the third bonding layer is a bonding layer used for bonding layers within the retardation plate 30. This is the laminating layer used. Hereinafter, when it is referred to as a bonding layer, it includes both the second bonding layer and the third bonding layer.

The bonding layer is an adhesive layer formed using an adhesive composition or an adhesive layer formed using an adhesive composition. The second bonding layer and the third bonding layer are preferably adhesive layers from the viewpoint of suppressing thermal shrinkage behavior when heat is applied.

When the bonding layer is a pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer is not particularly limited as long as it can satisfy the moisture permeability described above. Examples of the adhesive composition include rubber polymers, (meth)acrylic polymers, urethane polymers, polyester polymers, silicone polymers, polyvinyl ether polymers, polyvinyl alcohol polymers, polyolefin polymers, and vinyl alkyl ether polymers. Any polymer may be used as long as it contains a polymer such as a polyvinylpyrrolidone polymer, a poly(meth)acrylamide polymer, or a cellulose polymer as a main component. In this specification, the main component refers to a component containing 50% by mass or more of the total solid content of the adhesive composition. The adhesive composition may be of an active energy ray curable type or a thermosetting type. As the adhesive composition, rubber-based polymers are preferred. In addition, the above-mentioned "(meth)acrylic" means "at least one of acrylic and methacryl." The same applies to expressions such as "(meth)acrylate".

Examples of rubber-based polymers include natural rubber; polyisobutylene rubber (PIB), isoprene rubber (IR), isobutylene-isoprene rubber (IIR), normal butylene-isobutylene copolymer rubber, butadiene rubber (BR), and chloroprene rubber (CR). , acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-styrene block copolymer rubber (SIBS), styrene-ethylene-butylene-styrene block copolymer rubber (SEBS), styrene-ethylene-propylene-styrene block copolymer rubber (SEPS), styrene-butadiene-styrene block copolymer rubber (SBS), styrene-ethylene-propylene block copolymer rubber (SEP), etc. Examples include synthetic rubber. The rubber-based polymer is preferably polyisobutylene rubber (PIB), isobutylene-isoprene rubber (IIR), or normal butylene-isobutylene copolymer rubber, and more preferably polyisobutylene rubber (PIB).

The (meth)acrylic polymer is one type of (meth)acrylic ester such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Alternatively, a polymer or copolymer containing two or more types of monomers is preferably used. It is preferable to copolymerize a polar monomer with the base polymer. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl ( Examples include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc., such as meth)acrylates.

An active energy ray-curable adhesive composition has the property of being cured by irradiation with active energy rays such as ultraviolet rays or electron beams, and remains sticky and forms a film even before irradiation with active energy rays. It is an adhesive composition that can be closely adhered to adherends such as adhesives, etc., and has the property that it can be cured by irradiation with active energy rays to adjust the adhesive strength. The active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition. The active energy ray curable adhesive composition further contains an active energy ray polymerizable compound in addition to the base polymer and the crosslinking agent. Furthermore, if necessary, a photopolymerization initiator, a photosensitizer, etc. may be included.

In addition to the polymer, the adhesive composition contains a solvent; a tackifier, a softener, a filler (such as metal powder or other inorganic powder), an antioxidant, an ultraviolet absorber, a dye, a pigment, a colorant, and an antifoaming agent. , a corrosion inhibitor, a photopolymerization initiator, and other additives. When an active energy ray-curable adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating the formed adhesive layer with active energy rays.

The adhesive layer can be formed by applying a diluted solution of the adhesive composition in an organic solvent onto a base material and drying it.

When the bonding layer is an adhesive layer, the adhesive composition used to form the adhesive layer is not particularly limited as long as it can satisfy the above moisture permeability. Examples of adhesive compositions include water-based adhesives, active energy ray-curable adhesives, natural rubber adhesives, α-olefin adhesives, urethane resin adhesives, ethylene-vinyl acetate resin emulsion adhesives, and ethylene-vinyl acetate resin emulsion adhesives. Vinyl acetate resin hot melt adhesive, epoxy resin adhesive, vinyl chloride resin solvent adhesive, chloroprene rubber adhesive, cyanoacrylate adhesive, silicone adhesive, styrene-butadiene rubber solvent adhesive, nitrile Rubber adhesives, nitrocellulose adhesives, reactive hot melt adhesives, phenolic resin adhesives, modified silicone adhesives, polyester hot melt adhesives, polyamide resin hot melt adhesives, polyimide adhesives, polyurethane Resin hot melt adhesive, polyolefin resin hot melt adhesive, polyvinyl acetate resin solvent-based adhesive, polystyrene resin solvent-based adhesive, polyvinyl alcohol-based adhesive, polyvinylpyrrolidone resin-based adhesive, polyvinyl butyral-based adhesive, polybenzimidazole Examples include adhesives, polymethacrylate resin solvent adhesives, melamine resin adhesives, urea resin adhesives, resorcinol adhesives, and the like. Such adhesives can be used alone or in combination of two or more.

Examples of water-based adhesives include polyvinyl alcohol resin aqueous solutions, water-based two-component urethane emulsion adhesives, and the like. Active energy ray-curable adhesives are adhesives that are cured by irradiation with active energy rays such as ultraviolet rays, such as those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, Examples include those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. . Examples of the photopolymerization initiator include those containing substances that generate active species such as neutral radicals, anion radicals, and cation radicals upon irradiation with active energy rays such as ultraviolet rays.

The thickness of the bonding layer is not particularly limited, but when the bonding layer is an adhesive layer, it is preferably 5 μm or more, may be 15 μm or more, may be 20 μm or more, and may be 25 μm or more. It may be generally 200 μm or less, may be 100 μm or less, or may be 50 μm or less. When the bonding layer is an adhesive layer, the thickness of the bonding layer is preferably 0.01 μm or more, may be 0.05 μm or more, may be 0.5 μm or more, and may be 5 μm or more. It is preferably below, and may be 3 μm or less, or may be 2 μm or less.

[Manufacturing method of polarizing plate]
The polarizing plate of this embodiment can be obtained by bonding the above-mentioned retardation plate and the above-mentioned linear polarizing plate together using a first bonding layer. When the first retardation layer of the retardation plate is composed of only one layer and there is only one slow axis, the relative It is preferable to set the transmission axis of the linearly polarizing plate to substantially 45°. Substantially 45° is typically in the range of 45±5°. In such an angular arrangement, the polarizing plate can function as a circularly polarizing plate.

As a method for laminating a retardation plate without a base material to a linearly polarizing plate, the retardation plate from which the base material has been removed (peeled) is laminated to the linearly polarizing plate using a first laminating layer. and a method of removing (peeling) the base material after laminating the retardation plate to the linearly polarizing plate using the first laminating layer. In this embodiment, it is preferable that the base material be removed after the retardation plate is bonded to the linearly polarizing plate. According to the present invention, even in such a configuration, damage to the retardation layer of the retardation plate can be suppressed when the base material is removed.

The first bonding layer may be formed directly by applying an adhesive to the retardation layer side of the retardation plate, or may be formed directly by applying an adhesive to the linear polarizing plate side. Alternatively, a first bonding layer previously formed on another base material may be interposed between the linearly polarizing plate and the retardation plate. If there is an alignment film between the base material and the retardation layer, the alignment film may be removed together with the base material.

A base material having a functional group on its surface that forms a chemical bond with the retardation layer, alignment film, etc. tends to form a chemical bond with the retardation layer, alignment film, etc., making it difficult to remove. Therefore, when removing the base material by peeling it off, a base material with few functional groups on the surface is preferable, and a base material that has not been subjected to surface treatment to form functional groups on the surface is preferable.

In addition, alignment films that have functional groups that form chemical bonds with the base material tend to have a strong adhesion between the base material and the alignment film, so when removing the base material by peeling it, it is necessary to It is preferable to use an alignment film with a small number of functional groups forming . In addition, it is preferable that a reagent that crosslinks the substrate and the alignment film is not included, and further, the solution of the alignment polymer composition and the composition for forming a photoalignment film contains components such as a solvent that dissolve the substrate. It is preferable that it not be included.

Furthermore, an alignment film having a functional group that forms a chemical bond with the retardation layer tends to have a strong adhesion between the retardation layer and the alignment film. Therefore, when removing the alignment film together with the base material, it is preferable to use an alignment film that has fewer functional groups that form chemical bonds with the retardation layer. Further, it is preferable that the retardation layer and the alignment film do not contain a reagent that crosslinks the retardation layer and the alignment film.

Further, a retardation layer having a functional group that forms a chemical bond with the alignment film tends to have a strong adhesion between the alignment film and the retardation layer. Therefore, when removing the base material or when removing the alignment film together with the base material, a retardation layer having fewer functional groups that form chemical bonds with the base material or the alignment film is preferable. Furthermore, the polymerizable liquid crystal composition preferably does not contain a reagent that crosslinks the base material or the alignment film and the retardation layer.

For example, the first bonding layer 21 is attached to the surface of the first retardation layer 31 of the retardation plate 30 in which the base material, the second retardation layer 32, and the first retardation layer 31 are laminated in this order, By laminating the linear polarizing plate 10 there and then removing the base material of the retardation plate 30, the linear polarizing plate 10, the first lamination layer 21, the first retardation layer 31, and the second retardation layer 32 are laminated in this order, a polarizing plate having the configuration shown in FIG. 1 can be manufactured. In addition, the first bonding layer is attached to the surface of the second retardation layer of the retardation plate in which the base material, the first retardation layer, and the second retardation layer are laminated in this order, and the linear polarizing layer is attached thereto. A polarizing plate in which a linearly polarizing plate, a second retardation layer, and a first retardation layer are laminated in this order can be manufactured by laminating them together and then removing the base material of the retardation plate. From the viewpoint of thinning the film, it is preferable to peel off the base material.

When the first retardation layer includes layer A and layer B, or when it includes the third retardation layer, there is a restriction on the stacking direction of each layer.
Specifically, when layer A having a retardation of λ/4 and layer B having a retardation of λ/2 are laminated, layer B is first stacked with respect to the absorption axis of the linear polarizing plate. The layer A is formed so that the slow axis is 75°, and then layer A is formed so that the slow axis of layer A is 15°.
In addition, in the case of having a first retardation layer having a retardation of λ/4 and a third retardation layer having a retardation of λ/2, the third retardation layer is first is formed so that the slow axis of the third retardation layer is 75°, and then the first retardation layer is formed so that the slow axis of the first retardation layer is 15°. There is no restriction on the position of the second retardation layer, but the linear polarizing plate, layer B and layer A may be laminated in this order, or the linear polarizing plate, third retardation layer and first retardation layer may be laminated in this order. It needs to be laminated with By laminating in this manner, the resulting polarizing plate can function as a broadband circularly polarizing plate. Here, there is no limit to the axis angle at which the layers A and B are formed, and for example, as described in JP-A-2004-126538, the slow axis angle of the layers A and B is set to the absorption axis of the polarizing plate. However, it is known that the function as a broadband λ/4 plate can be achieved even if the angle is 30° and -30°, or 45° and -45°, so it is possible to laminate layers in a desired manner. It is.

[Image display device]
FIG. 4 is a schematic cross-sectional view schematically showing an example of the image display device of this embodiment. As shown in FIG. 4, the image display device 2 includes the polarizing plate 1 shown in FIG. 1 and the image display panel 40 in this order from the front side. In the image display device 2, the polarizing plate 1 is arranged in such a direction that the linearly polarizing plate 10 side is in front of the retardation plate 30.

When the polarizing plate 1 is a circularly polarizing plate, in the image display device 2, external incident light includes light that is reflected by the polarizing plate 1 and light that is transmitted through the polarizing plate 1. The polarizing plate 1 may have an anti-reflection layer on the front surface, and by providing the anti-reflection layer, light reflected on the surface of the polarizing plate 1 (hereinafter also referred to as "external reflected light") is reduced. can do. The light transmitted through the polarizing plate 1 is reflected by the image display panel 40 to become reflected light (hereinafter also referred to as "internally reflected light"), and is absorbed by the polarizing plate 1. Although it is desirable that all of the internally reflected light be absorbed by the polarizing plate 1, a portion of it is emitted from the front surface (hereinafter, such light is also referred to as "emitted internally reflected light").

The polarizing plate 1 may be provided with an adhesive layer on the rear surface that can be used to bond the polarizing plate 1 to the image display panel 40, and may be configured as a polarizing plate with an adhesive layer.

<Other layers that the image display device may have>
The image display device 2 may have layers other than the layers described above. Hereinafter, other layers that the image display device 2 may have will be illustrated.

(touch sensor panel)
A touch sensor panel is a device (sensor) that detects (sensing) a finger or the like that contacts (touches) the screen of an image display device, and serves as an input means to detect the position of the finger on the screen and input it to the image display device. used. The touch sensor panel may be placed between the polarizing plate 1 and the image display panel 40, or may be placed on the front side of the polarizing plate 1. As a touch sensor panel, the detection method is not limited as long as it is a sensor that can detect the touched position, such as resistive film method, capacitive coupling method, optical sensor method, ultrasonic method, electromagnetic inductive coupling. Examples include touch sensor panels using a touch sensor panel based on a surface acoustic wave method, a surface acoustic wave method, an infrared method, or the like. Resistive film type and capacitive coupling type touch sensor panels are preferably used because of their low cost.

An example of a resistive film type touch sensor panel includes a pair of substrates facing each other, an insulating spacer sandwiched between the pair of substrates, and a transparent resistive film provided as a resistive film on the inside front of each substrate. It is composed of a conductive film and a touch position detection circuit. In an image display device equipped with a resistive film type touch sensor panel, when the surface of the front plate is touched, opposing resistive films are short-circuited, and current flows through the resistive films. The touch position detection circuit detects the voltage change at this time, and the touched position is detected.

An example of a capacitive coupling type touch sensor panel includes a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device including a capacitive coupling type touch sensor panel, when the surface of the front plate is touched, a transparent electrode is grounded at the touched point via the capacitance of the human body. A touch position detection circuit detects grounding of the transparent electrode, and the touched position is detected. A capacitive touch sensor panel is divided into an active area and a non-active area located around the active area. The active area corresponds to the area where the screen is displayed on the display panel (display part) and is the area where the user's touch is sensed, and the inactive area is the area where the screen is not displayed on the display device (non-active area). This is the area corresponding to the display section).

The thickness of the touch sensor panel may be, for example, 5 μm or more and 2,000 μm or less, or 5 μm or more and 100 μm or less.

<Flexible image display device>
The image display device may be a flexible image display device. A flexible image display device is an image display device that can be folded. The flexible image display device incorporates an optical fingerprint authentication system and includes a bendable image display element and a polarizing plate of the present invention. The foldable image display element is, for example, an organic EL display panel. The polarizing plate of the present invention is placed on the viewing side of the organic EL display panel and is configured to be bendable. The polarizing plate for a flexible image display device may further include a front plate and a touch sensor panel.
The front plate, the polarizing plate of the present invention, and the touch sensor panel may be laminated in this order from the viewing side, or the front plate, the touch sensor panel, and the polarizing plate of the present invention may be laminated in this order from the viewing side. preferable. If a polarizer is present on the viewing side of the touch sensor panel, the pattern of the touch sensor panel becomes difficult to see, and as a result, the visibility of the displayed image improves. Therefore, the polarizing plate of the present invention is placed on the viewing side of the touch sensor panel. It is more preferable to have a configuration including a front plate, a polarizing plate of the present invention, and a touch sensor panel in this order. Each member can be laminated using an adhesive, a pressure-sensitive adhesive, or the like. Further, a light-shielding pattern formed on at least one surface of any one of the front plate, polarizing plate, and touch sensor panel can be provided.

In a flexible image display device that includes, from the viewing side, a front plate, a polarizing plate of the present invention, and a foldable image display panel, the front plate and the polarizing plate of the present invention are polarized light with a front plate that includes a polarizing plate and a front plate. Configure the board. In this polarizing plate with a front plate, the front plate is usually arranged on the viewing side of the polarizing plate, and is laminated with the polarizing plate using, for example, a pressure-sensitive adhesive or an adhesive.
In a flexible image display device that includes, from the viewing side, a touch sensor panel, a polarizing plate of the present invention, and a foldable image display panel, the touch sensor panel and the polarizing plate of the present invention include a touch sensor that includes a polarizing plate and a touch sensor panel. Constitutes a polarizing plate with a panel. Further, from the viewing side, in a flexible image display device including a polarizing plate of the present invention, a touch sensor panel, and a bendable image display element, the touch sensor panel and the polarizing plate of the present invention combine the polarizing plate and the touch sensor panel. A polarizing plate with a touch sensor panel is configured. In this polarizing plate with a touch sensor panel, the touch sensor panel may be placed on the back side (opposite to the viewing side) of the polarizing plate, or may be placed on the viewing side of the polarizing plate. The touch sensor panel and the polarizing plate are laminated with, for example, an adhesive or an adhesive.

The polarizing plate of the present invention can also be used as a polarizing plate with a front plate by laminating a front plate on its viewing side. A polarizing plate with a front plate includes the polarizing plate of the present invention and a front plate disposed on the viewing side thereof.

(Front plate)
Examples of the front plate include glass, a resin film containing a hard coat layer on at least one surface thereof, and the like. As the glass, for example, high transmittance glass or tempered glass can be used. Especially when using a thin transparent surface material, chemically strengthened glass is preferable. The thickness of the glass can be, for example, 100 μm to 5 mm.

The front panel, which includes a hard coat layer on at least one surface of the resin film, is not rigid like existing glass, but can have flexible characteristics. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 μm to 100 μm.

Examples of resin films include cycloolefin derivatives having units of monomers containing cycloolefins such as norbornene and polycyclic norbornene monomers, cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isobutyl ester) cellulose, propionylcellulose, butyrylcellulose, acetylpropionylcellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene , polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, The film may be made of a polymer such as polycarbonate, polyurethane, or epoxy. These polymers can be used alone or in a mixture of two or more.
The resin film may be an unstretched film or a stretched film, such as a uniaxially stretched film or a biaxially stretched film. As the resin film, polyamide-imide film, polyimide film, uniaxially oriented polyester film, and biaxially oriented polyester film are preferable because they have excellent transparency and heat resistance. Cycloolefin derivative films and polymethyl methacrylate films are preferable because they can be used in various applications, while triacetyl cellulose and isobutyl ester cellulose films are preferable because resin films that are transparent and have no optical anisotropy are relatively easy to obtain. However, each is preferable. The thickness of the resin film is usually 5 to 200 μm, preferably 20 to 100 μm.

(shading pattern)
The light shielding pattern is a member also called a bezel, and can be formed on the display element side of the front panel. By providing the light-shielding pattern, each wiring constituting the display device can be hidden so that it is not visible to the user. The color and material of the light shielding pattern are not particularly limited, and may be formed of resin materials having various colors such as black, white, and gold. In one embodiment, the thickness of the light shielding pattern may be in the range of 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. Further, in order to suppress the inclusion of air bubbles and visibility of the boundary portion due to the step difference between the light shielding pattern and the display section, a shape can be given to the light shielding pattern.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The amounts expressed in "%" and "parts" in Examples and Comparative Examples are mass % and parts by mass, unless otherwise specified.

[Evaluation of circularly polarizing plate (durability against base material peeling)]
An adhesive layer was laminated on the protective film on the outermost surface of the linearly polarizing plate of the circularly polarizing plate. This was cut to prepare a test piece with a width of 25 mm and a length of about 150 mm. The adhesive layer of the test piece was attached to a glass plate. A release tape (width 25 mm x length approximately 180 mm) was applied to the surface (one side of width 25 mm) of the outermost base material of the retardation material (the base material used for forming the second retardation layer) of the circularly polarizing plate. Pasted. One end of the peeling tape was grasped and the base material layer was peeled off using a tensile testing machine. The peeling speed was both 300 mm/min and 15000 mm/min. The peeling angle was 180°. If the retardation layer on the side closer to the base material is damaged during peeling, zipping will occur (rating C), if this phenomenon is not observed, there will be no zipping (rating A), if this phenomenon is slightly observed, zipping will occur. It was determined that it was slightly present (evaluation B).

[Measurement of puncture elastic modulus of retardation plate]
A needle was attached to a handy compression testing machine "NDG5 piercing tester, needle penetration force measurement specification" manufactured by Kato Tech Co., Ltd. A needle was inserted perpendicularly to the surface of the second retardation layer side of the retardation material from which the base material had been peeled off from the outermost surface. Calculate the stress F (g) just before the measurement sample puncture test sample breaks and the amount of strain S (mm) at that time, and calculate the puncture elastic modulus (g/mm) as stress F (g) / amount of strain S ( mm). This operation was performed for each of the five measurement samples, and the average value was taken as the piercing elastic modulus. The needle used had a tip diameter of 1 mmφ and a diameter of 0.5R. The needle piercing speed was 0.33 cm/sec. The measurements were performed in a room temperature environment with a temperature of 23° C. and a relative humidity of 55%.
Using the above method, the puncture elastic modulus of retardation plates A, B, and C used in the production of circularly polarizing plates of Examples 1 to 6, Comparative Examples 1 to 2, and Reference Example 1, which will be described later, was measured. Table 1 shows the measurement results.

[Measurement of tensile modulus of first lamination layer]
The adhesive used as the first lamination layer is applied to one side of the release paper using a coating machine [Bar coater, manufactured by Daiichi Rika Co., Ltd.], and the release paper is further laminated on the top surface of the adhesive layer. The sample was heated at 90° C. for 1 minute, and then cured for 7 days at a temperature of 23° C. and a relative humidity of 55%. This laminate was cut into pieces with a MD length of 100 mm and a TD length of 50 mm, and the release paper on both sides was peeled off to obtain an adhesive layer film consisting only of the adhesive layer. Regarding the adhesive layer, the adhesive was also cured using a predetermined curing method to obtain a film consisting only of the adhesive layer.

In accordance with JIS K7161:1994 and JIS K7127:1999, if the test piece does not have a yield point, the tensile strain at break is taken as the elongation at break, and if it has a yield point, the tensile elongation at break is taken as the elongation at break. It was measured. The adhesive layer film obtained as described above was placed between the upper and lower grips of a tensile tester [Autograph AG-Xplus tester manufactured by Shimadzu Corporation], and the sample for measurement was placed at a distance of 5 cm between the grips. The measurement sample was pulled in the MD length direction at a pulling speed of 300 mm/min in an environment of a temperature of 23°C and a relative humidity of 55%, holding both ends of the MD lengthwise. The tensile modulus [Pa] in the transverse direction was calculated.

[Production Example 1: Production of laminate including first retardation layer]
(i) Preparation of composition for forming photo-alignment film 5 parts of photo-alignment material having the following structure (weight average molecular weight: 30,000) and 95 parts of cyclopentanone (solvent) were mixed. The resulting mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a photo-alignment film.

(ii) Preparation of first retardation layer forming composition Polymerizable liquid crystal compound A and polymerizable liquid crystal compound B shown below were mixed at a mass ratio of 90:10. To 100 parts of this mixture, 1.0 part of a leveling agent (F-556; manufactured by DIC Corporation) and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane as a polymerization initiator were added. 6 parts of -1-one ("Irgacure 369 (Irg369)", manufactured by BASF Japan Ltd.) was added.

Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 13%, and the mixture was stirred at 80° C. for 1 hour to obtain a first retardation layer forming composition.

Polymerizable liquid crystal compound A was produced by the method described in JP-A No. 2010-31223. Furthermore, polymerizable liquid crystal compound B was produced according to the method described in JP-A No. 2009-173893. The molecular structure of each is shown below.

(Polymerizable liquid crystal compound A)

(Polymerizable liquid crystal compound B)

(iii) Preparation of retardation layer base material A cycloolefin resin film (manufactured by Nippon Zeon Co., Ltd., "ZF-14-50") having a thickness of 50 μm was subjected to corona treatment to prepare a retardation layer base material. Corona treatment was performed using TEC-4AX manufactured by Ushio Inc. Corona treatment was performed once under conditions of an output of 0.78 kW and a treatment speed of 10 m/min.

(iv) Formation of photo-alignment film The composition for forming a photo-alignment film was applied to the retardation layer base material using a bar coater. The coating film was dried at 80° C. for 1 minute, and polarized UV exposure was performed using a polarized UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) at an integrated light intensity of 100 mJ/cm ² . The thickness of the obtained horizontal alignment film was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 100 nm.

(v) Formation of first retardation layer Subsequently, in an environment of room temperature 25°C and relative humidity 30%, the composition for forming the first retardation layer was applied to a PTFE membrane filter with a pore size of 0.2 μm (Advantech Toyo Co., Ltd. (product number: T300A025A) and coated on a substrate film with an alignment film kept at 25° C. using a bar coater. After drying the coating film at 120°C for 1 minute, it was irradiated with ultraviolet rays using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured by Ushio Inc.) (under nitrogen atmosphere, wavelength: 365 nm, cumulative light intensity at wavelength 365 nm). :1000mJ/ ^cm2 ). The thickness of the obtained coating film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2 μm.
When the retardation values of the obtained first retardation layer were measured, Re (450) = 121 nm, Re (550) = 139 nm, and Re (650) = 146 nm.
The relationship between the in-plane retardation values at each wavelength was as follows.
Re(450)/Re(550)=0.87
Re(650)/Re(550)=1.05

[Production Example 2: Production of laminate including second retardation layer]
(i) Preparation of oriented polymer composition (1) 1 part of Sunever SE-610 (manufactured by Nissan Chemical Co., Ltd.) and 99 parts of 2-butoxyethanol were mixed to obtain an oriented polymer composition (1). .

(ii) Preparation of second retardation layer forming composition 19.2 parts of polymerizable liquid crystal (manufactured by BASF, LC242) shown in the figure below, 0 parts of a leveling agent ("BYK-361N", manufactured by BYK Chemie Japan) .1 part, 0.5 parts of polymerization initiator ("Irgacure 907" manufactured by BASF Japan), 1.1 parts of reaction additive ("Laromaer LR-9000" manufactured by BASF Japan), and 2 parts of propylene glycol 1-monomethyl ether. - 79.1 parts of acetate were mixed. A composition for forming a second retardation layer was obtained by stirring the mixed solution at 80° C. for 1 hour.

(iii) Preparation of retardation layer base material A cycloolefin resin film (manufactured by Nippon Zeon Co., Ltd., "ZF-14-50") having a thickness of 50 μm was subjected to corona treatment to prepare a retardation layer base material. Corona treatment was performed using TEC-4AX manufactured by Ushio Inc. Corona treatment was performed once under conditions of an output of 0.78 kW and a treatment speed of 10 m/min.

(iv) Formation of oriented polymer film The oriented polymer composition (1) was applied to the retardation layer base material using a bar coater, and dried at 90° C. for 1 minute to obtain an oriented film. The thickness of the obtained alignment film was measured using a laser microscope and was found to be 34 nm.

(v) Formation of second retardation layer Next, a composition for forming a second retardation layer was applied onto the alignment film using a bar coater, dried at 90°C for 1 minute, and then using a high-pressure mercury lamp. Then, a second retardation layer was obtained by irradiating ultraviolet light (under nitrogen atmosphere, temperature: 25° C., cumulative light amount at 365 nm wavelength: 1000 mJ/cm ² ). When the film thickness of the obtained second retardation layer was measured using a laser microscope, the film thickness was 450 nm. Furthermore, when the retardation values of the obtained retardation film (2) at a wavelength of 550 nm were measured, they were Re (550) = 1 nm and Rth (550) = -70 nm. That is, the second retardation layer had optical characteristics expressed by the following formula (3). Note that since the retardation value of COP at a wavelength of 550 nm is approximately 0, it does not affect the optical characteristics.
nx≒ny<nz (3)

[Production Example 3: Production of retardation plate A]
The laminate containing the first retardation layer obtained in Production Example 1 and the laminate containing the second retardation layer obtained in Production Example 2 were each treated with the following active energy ray-curable adhesive A. were bonded together so that the retardation layer surface (the surface on the opposite side to the surface on the base material side) was the bonding surface. Next, the active energy ray-curable adhesive A was cured by irradiation with ultraviolet rays. In this way, a retardation plate A including two retardation layers, a first retardation layer and a second retardation layer, was produced.

<Active energy ray curable adhesive A>
After blending and mixing the following components, the active energy ray-curable adhesive A was prepared by defoaming.
・3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (product name: CEL2021P, manufactured by Daicel Corporation): 70 parts by mass ・Neopentyl glycol diglycidyl ether (product name: EX-211, Nagasechem) 2-ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagase ChemteX Corporation): 20 parts by mass ・Cationic polymerization initiator (trade name: CPI-100_50% solution, San-Apro) Co., Ltd.): 4.5 parts by mass (substantially solid content 2.25 parts by mass)
・1,4-diethoxynaphthalene: 2 parts by mass

[Production Example 4: Production of retardation plate B]
A retardation plate B in which base material/alignment layer/second retardation layer (positive C plate)/orientation layer/first retardation layer (λ/4 layer) were laminated in this order was produced as follows. .

(Base material)
A cycloolefin polymer film (COP) (ZF-14 manufactured by Zeon Corporation) was prepared as a base material.

(Corona treatment)
AGF-B10 manufactured by Kasuga Denki Co., Ltd. was used as the corona treatment device. Corona treatment was performed once using the above corona treatment apparatus under conditions of an output of 0.3 kW and a treatment speed of 3 m/min.

(High pressure mercury lamp)
Unicure VB-15201BY-A manufactured by Ushio Inc. was used as a high-pressure mercury lamp.

The oriented polymer composition (1) prepared in the production of retardation plate A was applied to the surface of the corona-treated substrate using a bar coater, and dried at 90° C. for 1 minute. The thickness of the obtained alignment film was measured using a laser microscope and was found to be 34 nm. Subsequently, the second retardation layer forming composition prepared in the production of retardation plate A was applied onto the alignment film using a bar coater, dried at 90°C for 1 minute, and then coated using a high-pressure mercury lamp. Then, a second retardation layer (positive C plate) is formed by irradiating ultraviolet rays (under a nitrogen atmosphere, cumulative light amount at a wavelength of 365 nm: 1000 mJ/cm ² ), and a second retardation film having the second retardation layer is formed. I got it. When the film thickness of the obtained second retardation layer was measured using a laser microscope, the film thickness was 450 nm. Furthermore, when the retardation values of the obtained second retardation film at a wavelength of 550 nm were measured, Re(550)=1 nm and Rth(550)=-70 nm. That is, the second retardation layer has the following formula (3):
nx≒ny<nz (3)
It had optical properties expressed as follows. Note that since the retardation value of the base material at a wavelength of 550 nm is approximately 0, it does not affect the optical properties.

Next, on the second retardation layer of the second retardation film, the following oriented polymer composition (2) was applied using a bar coater and dried at 100° C. for 1 minute. The thickness of the obtained alignment film was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 100 nm. Subsequently, the alignment film was subjected to a rubbing treatment, and the first retardation layer forming composition prepared in the production of retardation plate A was applied to the treated surface using a bar coater, and dried at 120° C. for 1 minute. A first retardation layer is formed on the second retardation layer by irradiating the coating film with ultraviolet rays (in a nitrogen atmosphere, cumulative light amount at a wavelength of 365 nm: 1000 mJ/cm ² ) using a high-pressure mercury lamp, A retardation plate B was obtained. The thickness of the obtained first retardation layer was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2 μm. When the retardation values of the obtained retardation plate B were measured, Re (450) = 121 nm, Re (550) = 139 nm, and Re (650) = 146 nm.
The relationship between the in-plane retardation values at each wavelength was as follows.
Re(450)/Re(550)=0.87
Re(650)/Re(550)=1.05
That is, the obtained retardation plate B had optical characteristics expressed by the above-mentioned formulas (1), (2), and (4).

(Oriented polymer composition (2))
Commercially available polyvinyl alcohol (Polyvinyl Alcohol 1000 completely saponified type, manufactured by Wako Pure Chemical Industries, Ltd.) was added to water and heated at 100°C for 1 hour to obtain an oriented polymer with a solid content of 2% by mass (solvent concentration of 98% by mass). Composition (2) was obtained.

[Production Example 5: Production of retardation plate C]
In producing the retardation plate A, the adhesive layer 3 was used instead of the active energy ray-curable adhesive A to bond the laminate including the first retardation layer and the laminate including the second retardation layer. Retardation plate C was produced in the same manner as retardation plate A, except that the retardation plate was produced using (a sheet-like acrylic adhesive having a thickness of 5 μm).

[Manufacture example 6: Preparation of polarizer]
A polyvinyl alcohol film with a thickness of 20 μm, a degree of polymerization of 2,400, and a degree of saponification of 99.9% or more is uniaxially stretched in a dry manner at a stretching ratio of 4.5 times, and while maintaining the tension state, 0 iodine per 100 parts by weight of water is added. 05 parts by weight and 5 parts by weight of potassium iodide for 60 seconds at 28°C.

Next, it was immersed for 110 seconds in a 64° C. boric acid aqueous solution 1 containing 5.5 parts by weight of boric acid and 15 parts by weight of potassium iodide per 100 parts by weight of water. Next, it was immersed for 30 seconds in a 67° C. boric acid aqueous solution 2 containing 5.5 parts by weight of boric acid and 15 parts by weight of potassium iodide per 100 parts by weight of water. Thereafter, it was washed with pure water at 3° C. and dried to obtain a polarizer with a thickness of 8 μm.

[Production Example 7: Production of linear polarizing plate]
The following protective films were prepared.
Protective film: Norbornene resin film with a thickness of 13 μm [manufactured by Nippon Zeon Co., Ltd., product name “ZEONOR”]
The above-mentioned protective film was bonded to one side of the polarizer produced above using a roll bonding machine via a water-based adhesive. After lamination, drying treatment was performed at 80° C. for 3 minutes. A linear polarizing plate was obtained in which a protective film was laminated only on one side of the polarizer. The linear polarizing plate had a polarizer, an adhesive layer, and a protective film laminated in this order.

[Production Example 8: Preparation of adhesive layer 1]
81.8 parts of ethyl acetate, 90.0 parts of butyl acrylate, 5.0 parts of methyl acrylate, and 5.0 parts of acrylic acid were placed in a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer. A mixed solution was charged, and the internal temperature was raised to 55° C. while replacing the air in the device with nitrogen gas to make it oxygen-free. Thereafter, the entire amount of a solution prepared by dissolving 0.15 parts of azobisisobutyronitrile (polymerization initiator) in 10 parts of ethyl acetate was added. After adding the polymerization initiator, the temperature was maintained at this temperature for 1 hour, and then ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56°C. ) When the concentration of the acrylic resin reached 35% by mass, the addition of ethyl acetate was stopped, and the mixture was kept at this temperature until 6 hours had elapsed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of (meth)acrylic resin to 20% by mass to prepare acrylic resin solution 1. The obtained acrylic resin had a weight average molecular weight Mw of 1.6 million and a molecular weight distribution Mw/Mn of 4.5. For Mw and Mn, two columns of "TSKgel GMHHR-H (S)" manufactured by Tosoh Corporation were connected in series in the GPC device, tetrahydrofuran was used as the eluent, and the sample concentration was 2 mg/mL. Measurements were made using standard polystyrene conversion under the conditions of a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

To 100 parts of the solid content of the above acrylic resin solution 1, a crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L") (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75% by mass)) ) on an active ingredient basis and 0.2 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") were added, and the solid content concentration was further adjusted to 13%. Ethyl acetate was added to obtain adhesive composition 1.

Adhesive composition 1 was applied to the release-treated surface of a release-treated polyethylene terephthalate film [PLR-382190 obtained from Lintec Corporation] using an applicator after drying. It was coated to a thickness of 25 μm and dried at 100° C. for 1 minute to prepare an adhesive layer (adhesive sheet). Next, the surface of the resulting adhesive layer opposite to the separator film was the release-treated surface of a polyethylene terephthalate film ("PET-251130" obtained from Lintec Corporation) that had been subjected to a release treatment. The adhesive layer 1 was produced by laminating.

[Production Example 9: Preparation of adhesive layer 2]
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 part of 2-hydroxyethyl acrylate, and 0.5 parts of acrylic acid were added. The internal temperature was raised to 55° C. while replacing the air inside the device with nitrogen gas to make it oxygen-free. Thereafter, a solution of 0.12 parts of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in its entirety. After adding the polymerization initiator, the temperature was maintained at this temperature for 1 hour, and then ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56°C. ) When the concentration of the acrylic resin reached 35% by mass, the addition of ethyl acetate was stopped, and the mixture was kept at this temperature until 6 hours had elapsed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of (meth)acrylic resin to 20% by mass to prepare acrylic resin solution 2. The obtained acrylic resin had a weight average molecular weight Mw of 1.7 million and a molecular weight distribution Mw/Mn of 3.9. For Mw and Mn, two columns of "TSKgel GMHHR-H (S)" manufactured by Tosoh Corporation were connected in series in the GPC device, tetrahydrofuran was used as the eluent, and the sample concentration was 2 mg/mL. Measurements were made using standard polystyrene conversion under the conditions of a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

To 80 parts of solid content of acrylic resin solution 2, 20 parts (solid content) of bifunctional acrylate (obtained from Shin-Nakamura Chemical Co., Ltd.; product number "A-DOG"), crosslinking agent (manufactured by Tosoh Corporation: product) 2.5 parts of "Coronate L" (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75% by mass)) based on the active ingredient, photopolymerization initiator (manufactured by Ciba Specialty Chemicals) : 1.5 parts of silane coupling agent (product name: "Irgacure 500") and 0.3 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") were added, and the solid content concentration was further adjusted to 13%. Ethyl acetate was added to obtain adhesive composition 2.
A-DOG is a diacrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane, and has the structure of the following formula.

Adhesive composition 2 was applied to the release-treated surface of a release-treated polyethylene terephthalate film [PLZ-383030 obtained from Lintec Corporation] using an applicator to determine the thickness after drying. The adhesive layer (adhesive sheet) was prepared by applying the adhesive so that the adhesive layer had a thickness of 15 μm and drying at 100° C. for 1 minute. Next, the surface of the obtained adhesive layer opposite to the separator film was the release-treated surface of a polyethylene terephthalate film ("PLR-381031" obtained from Lintec Corporation), which had been subjected to a release treatment. Pasted. Subsequently, ultraviolet rays were irradiated under the following conditions to produce adhesive layer 2.
<UV irradiation conditions>
・Using Fusion UV lamp system (manufactured by Fusion UV Systems) H bulb ・Cumulative light intensity of UV wavelength range UVA 250 mJ/cm ² (Measuring device: Value measured by UV Power Puck II manufactured by Fusion UV)

[Production Example 10: Preparation of adhesive layer 3]
Adhesive layer 3 was produced in the same manner as in Production Example 9, except that adhesive composition 2 was applied so that the thickness after drying was 5 μm.

[Example 1]
The laminate (circularly polarizing plate) of Example 1 was produced as follows. Adhesive layer 1 (sheet-like acrylic adhesive with a thickness of 25 μm) was laminated on the polarizer of the linearly polarizing plate produced above. The tensile modulus of adhesive layer 1 measured by the above method was as shown in Table 1. From the retardation plate A produced in Production Example 3, the base material used to form the first retardation layer was peeled off. The exposed horizontal alignment film and the adhesive layer (first lamination layer) are laminated together to form a laminate (circular) in which a linear polarizing plate, a first lamination layer, and a retardation plate A are laminated in this order. A polarizing plate) was prepared. The angle between the absorption axis of the polarizer and the slow axis of the first retardation layer was 45°.

[Example 2]
Example 1 except that adhesive layer 2 (sheet-like acrylic adhesive with a thickness of 15 μm) was used in place of adhesive layer 1 used in the production of the laminate (circularly polarizing plate) of Example 1. In the same manner as above, a laminate (circularly polarizing plate) in which a linearly polarizing plate, a first bonding layer, and a retardation plate A were laminated in this order was obtained. The tensile modulus of adhesive layer 2 measured by the above method was as shown in Table 1.

[Example 3]
Example 1 except that adhesive layer 3 (sheet-like acrylic adhesive with a thickness of 5 μm) was used in place of adhesive layer 1 used in the production of the laminate (circularly polarizing plate) of Example 1. In the same manner as above, a laminate (circularly polarizing plate) in which a linearly polarizing plate, a first bonding layer, and a retardation plate A were laminated in this order was obtained. The tensile modulus of the adhesive layer 3 measured by the above method is as shown in Table 1.

[Example 4]
In place of the retardation plate A used in the production of the laminate (circularly polarizing plate) in Example 1, the retardation plate B produced in Production Example 4 was used, and the adhesive was applied to the first retardation layer of the retardation plate B. The linear polarizing plate, the first laminating layer, and the retardation plate B were laminated in this order in the same manner as in Example 1, except that the agent layer 1 (first laminating layer) was laminated. A laminate (circularly polarizing plate) was obtained.

[Example 5]
In place of the retardation plate A used in the production of the laminate (circularly polarizing plate) in Example 2, the retardation plate B produced in Production Example 4 was used, and the adhesive was applied to the first retardation layer of the retardation plate B. The linear polarizing plate, the first laminating layer, and the retardation plate B were laminated in this order in the same manner as in Example 2, except that the agent layer 2 (first laminating layer) was laminated. A laminate (circularly polarizing plate) was obtained.

[Example 6]
The procedure was the same as in Example 4, except that adhesive layer 3 (sheet-like adhesive with a thickness of 5 μm) was used instead of adhesive layer 1 used in the production of the laminate (circularly polarizing plate) in Example 4. Thus, a laminate (circularly polarizing plate) in which the linearly polarizing plate, the first bonding layer, and the retardation plate B were laminated in this order was obtained.

[Comparative example 1]
In place of the adhesive layer 1 used in the production of the laminate (circularly polarizing plate) of Example 1, an adhesive layer A (thickness after drying: 1.5 μm) formed from the above-mentioned active energy ray-curable adhesive A was used. ) was used in the same manner as in Example 1, to obtain a laminate (circularly polarizing plate) in which a linearly polarizing plate, a first bonding layer, and a retardation plate A were laminated in this order. The tensile modulus of adhesive layer A measured by the above method was as shown in Table 1.

[Comparative example 2]
In place of the adhesive layer 1 used in the production of the laminate (circularly polarizing plate) of Example 4, an adhesive layer A (thickness after drying: 1.5 μm) formed of the above-mentioned active energy ray-curable adhesive A was used. ) was used in the same manner as in Example 4, to obtain a laminate (circularly polarizing plate) in which a linearly polarizing plate, a first bonding layer, and a retardation plate B were laminated in this order.

[Reference example 1]
A straight line was produced in the same manner as in Example 3, except that the retardation plate C prepared in Production Example 5 was used in place of the retardation plate A used in the production of the laminate (circularly polarizing plate) in Example 3. A laminate (circularly polarizing plate) in which a polarizing plate, a first bonding layer, and a retardation plate were laminated in this order was obtained.

[evaluation]
The durability of the circularly polarizing plates of Examples 1 to 6, Comparative Examples 1 to 2, and Reference Example 1 when the base material used to form the second retardation layer was peeled off was evaluated according to the method described above. Table 1 shows the evaluation results.

1 polarizing plate, 2 image display device, 10 linear polarizing plate, 21 first bonding layer, 30 retardation plate, 31 first retardation layer, 32 second retardation layer, 40 image display panel.

Claims (7)

A polarizing plate in which a linear polarizing plate, a first bonding layer, and a retardation plate are laminated in this order,
The retardation plate is
comprising a first retardation layer and a second retardation layer,
The first retardation layer and the second retardation layer include a cured product of a liquid crystal compound,
The puncture modulus is 70 g/mm or more,
The first bonding layer is a polarizing plate having a tensile modulus of 1.0×10 ⁸ Pa or less at a temperature of 23° C. and a relative humidity of 55%. The polarizing plate according to claim 1, wherein the product of the thickness (m) of the first bonding layer and the tensile modulus (Pa) is 500 or less. The polarizing plate according to claim 1 or 2, wherein the retardation plate has only an alignment film or no other intervening layer between the first retardation layer and the second retardation layer. . The linearly polarizing plate has a polarizer,
The polarizing plate according to claim 1 or 2, wherein the polarizer has a thickness of 15 μm or less. The linear polarizing plate has a protective film provided on the surface of the polarizer opposite to the first bonding layer,
The polarizing plate according to claim 4, wherein the protective film has a thickness of 30 μm or less. The polarizing plate according to claim 1 or 2, wherein the first retardation layer is a λ/4 layer with reverse dispersion property. The polarizing plate according to claim 1 or 2, wherein the second retardation layer is a positive C plate.

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