Polarizer and image display device

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 external force.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 contain a cured product of a liquid crystal compound, and peel strength between the first retardation layer and the second retardation layer is 1.0 N / 25 mm or less. The first bonding layer is formed of a pressure-sensitive adhesive having tensile storage modulus of elasticity of 10 MPa or less at 23°C.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polarizing plate and an image display device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in image display devices, a method has been adopted in which a circular polarizing plate is disposed on the viewing side of an image display panel to suppress a decrease in visibility due to reflection of extraneous light.

[0003] A circular polarizing plate is a laminate of a linear polarizing plate and a retardation plate. In a circular polarizing plate, external light heading toward an image display panel is converted into linearly polarized light by the linear polarizing plate, and then converted into circularly polarized light by the subsequent retardation plate. Although the circularly polarized external light is reflected on the surface of the image display panel, the direction of rotation of the polarization plane is reversed during this reflection, and the light is converted into linearly polarized light by the retardation plate, and then blocked by the subsequent linear polarizing plate. As a result, the emission of external light to the outside is significantly suppressed.

[0004] In the retardation plate, a configuration having a retardation layer containing a cured product of a liquid crystal compound is known (for example, Patent Documents 1 and 2). With such a configuration, it is possible to reduce the thickness of the retardation plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-163935 A [Patent Document 2] JP 2019-91030 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a retardation plate having a plurality of retardation layers each containing a cured product of a liquid crystal compound, prioritizing thinning may result in a decrease in durability against external forces, leading to problems such as peeling between the retardation layers.

[0007] An object of the present invention is to provide a polarizing plate including a retardation plate having a plurality of retardation layers each containing a cured product of a liquid crystal compound, the polarizing plate having excellent durability against external forces. [Means for solving the problem]

[0008] The present invention provides the following polarizing plate. [1] A circular polarizing plate formed by laminating a linear polarizing plate, a first bonding layer, and a retardation plate in this order, The retardation plate is A first retardation layer and a second retardation layer are included. The first retardation layer and the second retardation layer include a cured product of a liquid crystal compound, The peel strength between the first retardation layer and the second retardation layer is 1.0 N / 25 mm or less, The first attachment layer is made of an adhesive having a tensile storage modulus of 10 MPa or less at a temperature of 23° C., in the polarizing plate. [2] The polarizing plate according to [1], wherein the retardation plate has only an alignment film between the first retardation layer and the second retardation layer, or has no other intervening layer. [3] The linear polarizing plate has a polarizer, The polarizing plate according to [1] or [2], wherein the polarizer has a thickness of 15 μm or less. [4] The linear polarizing plate is provided on the surface of the polarizer opposite to the first bonding layer. A protective film is provided. The polarizing plate according to [3], wherein the protective film has a thickness of 30 μm or less. [5] The polarizing plate according to any one of [1] to [4], wherein the first retardation layer is a λ / 4 layer having reverse dispersion. [6] The polarizing plate according to any one of [1] to [5], wherein the second retardation layer is a positive C plate. Effect of the Invention

[0009] According to the present invention, it is possible to provide a polarizing plate having excellent durability against external forces. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating an example of a polarizing plate according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing a specific example of a retardation plate. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing a specific example of a retardation plate. [Figure 4] 1 is a schematic cross-sectional view showing an example of an image display device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment. In all of the drawings, the scale of each component is appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[0012] [Polarizing plate] Fig. 1 is a schematic cross-sectional view showing an example of the polarizing plate of this embodiment. As shown in Fig. 1, the polarizing plate 1 has a linear polarizing plate 10, a first bonding layer 21, and a retardation plate 30 laminated in this order from the front side. The retardation plate 30 has a first retardation layer 31 and a second retardation layer 32. The polarizing plate 1 may be a circular polarizing plate. In this specification, the term polarizing plate also includes a circular polarizing plate.

[0013] The retardation plate 30 has a peel strength between the first retardation layer 31 and the second retardation layer 32 of 1.0 N / 25 mm or less, and may be 0.8 N / 25 mm or less. The peel strength is a value measured by a method according to the method described in the adhesion evaluation 1 shown in the examples. The present invention also includes a retardation plate 30 whose peel strength has decreased due to the storage environment or use environment, and whose peel strength immediately after manufacture was more than 1.0 N / 25 mm, but then became 1.0 N / 25 mm or less. The peel strength between the first retardation layer 31 and the second retardation layer 32 of the retardation plate 30 is preferably 0.2 N / 25 mm or more, more preferably 0.4 N / 25 mm or more. After the peel strength has decreased due to the storage environment or use environment, it is preferably 0.1 N / 25 mm or more, more preferably 0.2 N / 25 mm or more. 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 either case, the peel strength between the first retardation layer 31 and the second retardation layer 32 means the strength required to separate the first retardation layer 31 and the second retardation layer 32 between them.

[0014] In the retardation plate 30, when the first phase difference layer 31 and the second phase difference layer 32 are bonded via an attachment layer (hereinafter referred to as the "third attachment layer"), the peel strength between the first phase difference layer 31 and the second phase difference layer 32 largely depends on the attachment force of the third attachment layer. The attachment force of the third attachment layer largely depends on the material of the third attachment layer, and the attachment force of the third attachment layer may cause the peel strength between the first phase difference layer 31 and the second phase difference layer 32 to be 1.0 N / 25 mm or less. Generally, the attachment force of an adhesive is lower than that of a pressure-sensitive adhesive, and when the third attachment layer is formed from an adhesive, the peel strength between the first phase difference layer 31 and the second phase difference layer 32 may be 1.0 N / 25 mm or less. In the retardation plate 30, when the first phase difference layer 31 and the second phase difference layer 32 are laminated without an adhesive layer therebetween, the peel strength between the first phase difference layer 31 and the second phase difference layer 32 is generally low, usually 1.0 N / 25 mm or less. In the retardation plate 30, the configuration in which the first phase difference layer 31 and the second phase difference layer 32 are laminated without an adhesive layer includes a configuration in which only an alignment film is provided between the first phase difference layer 31 and the second phase difference layer 32, or a configuration in which no other layer is provided between the first phase difference layer 31 and the second phase difference layer 32. From the viewpoint of thinning, the third adhesive layer provided between the first phase difference layer 31 and the second phase difference layer 32 is preferably an adhesive rather than a pressure-sensitive adhesive, and from the viewpoint of further thinning, a configuration in which the layers are laminated without a third adhesive layer is preferable.

[0015] The present inventors have found that a polarizing plate using a retardation plate with a low peel strength between the first retardation layer 31 and the second retardation layer 32 has low durability against external forces. The present inventors have further conducted intensive research and have found that even if a polarizing plate using a retardation plate with a peel strength between the first retardation layer 31 and the second retardation layer 32 of 1.0 N / 25 mm or less is used, the polarizing plate can be made to have excellent durability against external forces by making the first attachment layer 21 interposed between the linear polarizing plate 10 and the retardation plate 30 from a pressure-sensitive adhesive having a tensile storage modulus of 10 MPa or less at a temperature of 23 ° C., and have arrived at the present invention. The tensile storage modulus of the pressure-sensitive adhesive forming the first attachment layer 21 at a temperature of 23 ° C. is preferably 8 MPa or less, more preferably 5 MPa or less, even more preferably 1 MPa or less, and may be 0.7 MPa or less, preferably 0.02 MPa or more, and more preferably 0.1 MPa or more. The polarizing plate according to the present invention has high durability against external forces, such as those applied in the crosshatch test in the examples, those applied by dropping, and those applied by peeling off a protective film during the manufacturing process.

[0016] Here, the storage modulus (dynamic modulus) means a commonly used term for viscoelasticity measurement, but it is a value obtained by a method (dynamic viscoelasticity measurement) in which a sample is given a strain or stress that changes (oscillates) over time, and the resulting stress or strain is measured to measure the mechanical properties of the sample. When strain is divided into two waves, one in phase with the stress and the other 90 degrees out of phase, it is the modulus that is in phase with the oscillating stress. The storage modulus depends on the method of applying stress; when the stress is applied by tension, it is called the tensile storage modulus, and when it is applied by shear, it is called the shear storage modulus. The tensile storage modulus and the shear storage modulus are generally related by the following formula (10), and can be converted (see formula (1.12) on page 15 of the book "Lecture on Rheology" (editor: The Society of Rheology of Japan, publisher: Mamoru Nishiguchi, publisher: Polymer Publishing Association, Inc.). E = G × 2 × (1 + ν) Equation (10) Here, E is the tensile storage modulus, G is the shear storage modulus, and ν is the Poisson's ratio. The tensile storage modulus can be measured using a commercially available viscoelasticity measuring device, for example, a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement & Control Co., Ltd. as shown in the Examples below, and the shear storage modulus can be measured using a viscoelasticity measuring device "MCR-301" manufactured by Anton Paar, etc. For temperature control of these viscoelasticity measuring devices, various known temperature control devices such as a circulating thermostatic bath, an electric heater, a Peltier element, etc. are used, and the temperature during measurement can be set by using these devices.

[0017] [First lamination layer] The first bonding layer 21 is a layer that bonds the linear polarizer 10 and the retarder 30. Examples of the adhesive having a tensile storage modulus of 10 MPa or less at a temperature of 23° C. include a pressure-sensitive adhesive and an adhesive. A pressure-sensitive adhesive is preferably used as the first bonding layer 21. The present inventors have found that by using a pressure-sensitive adhesive having a tensile storage modulus of 10 MPa or less as the first bonding layer 21, durability against external forces can be improved.

[0018] Specific examples of adhesives used in the first bonding layer 21 include those based on acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, etc. Among them, it is preferable to select and use an adhesive that has excellent optical transparency, moderate wettability and cohesive strength, excellent adhesion to the substrate, weather resistance, heat resistance, etc., and does not cause peeling problems such as lifting and peeling under heating and humidification conditions, such as acrylic polymers. In the acrylic polymer, an acrylic copolymer having a weight average molecular weight of 100,000 or more, which is obtained by blending an alkyl ester of acrylic acid having an alkyl group with 20 or less carbon atoms, such as a methyl group, an ethyl group, or a butyl group, with a functional group-containing acrylic monomer such as (meth)acrylic acid or hydroxyethyl (meth)acrylate, so that the glass transition temperature is preferably 25°C or less, more preferably 0°C or less, is useful as the base polymer.

[0019] The acrylic polymer is not particularly limited, but (meth)acrylic acid ester-based base polymers such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and copolymer-based base polymers using two or more of these (meth)acrylic acid esters are preferably used. In addition, polar monomers may be copolymerized in these base polymers. Examples of polar monomers include monomers having polar functional groups such as carboxyl groups, hydroxyl groups, amide groups, amino groups, and epoxy groups, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylamide, 2-N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0020] Although these acrylic polymers can be used alone as adhesives, crosslinking agents are usually blended into the adhesives. Examples of crosslinking agents include divalent or polyvalent metal ions that form carboxylate metal salts with carboxyl groups, polyamine compounds that form amide bonds with carboxyl groups, polyepoxy compounds or polyol compounds that form ester bonds with carboxyl groups, and polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are widely used as organic crosslinking agents.

[0021] In this embodiment, the means for adjusting the storage modulus of the adhesive forming the first bonding layer is not particularly limited, but for example, a method of blending an oligomer, specifically a urethane acrylate oligomer, with the above-mentioned adhesive component can be mentioned as a suitable example. Furthermore, an adhesive blended with such a urethane acrylate oligomer may be irradiated with energy rays and cured to be used. An adhesive blended with a urethane acrylate oligomer, or an adhesive with a separator that is coated on a support film (separator) and cured with ultraviolet light, is known and can be obtained from an adhesive manufacturer.

[0022] In addition to the above-mentioned base polymer, crosslinking agent, and oligomer, the adhesive may contain, if necessary, suitable additives such as natural or synthetic resins, tackifier resins, antioxidants, ultraviolet absorbers, dyes, pigments, defoamers, corrosion inhibitors, and photopolymerization initiators in order to adjust the adhesive strength, cohesive strength, viscosity, elastic modulus, glass transition temperature, etc. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex salt compounds.

[0023] When the adhesive is used as the first attaching layer 21, the thickness is determined depending on the adhesive strength, 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 it maintains good processability and shows high durability. Furthermore, by having the thickness in the above range, durability against external forces can be further improved.

[0024] Specific examples of the adhesive used in the first attaching layer 21 include adhesives other than pressure-sensitive adhesives (adhesives), such as water-based adhesives and active energy ray-curable adhesives.

[0025] Examples of the water-based adhesive include an adhesive in which a polyvinyl alcohol 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.

[0026] Examples of the active energy ray curable adhesive include a solventless active energy ray curable adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. By using a solventless active energy ray curable adhesive, the adhesion between layers can be improved.

[0027] The active energy ray curable adhesive preferably contains either one or both of a cationic polymerizable curable compound and a radical polymerizable curable compound, since they exhibit good adhesive properties. The active energy ray curable adhesive may further contain a cationic polymerization initiator, such as a photocationic polymerization initiator, for initiating the curing reaction of the curable compound, or a radical polymerization initiator.

[0028] Examples of the cationic polymerizable curable compound include epoxy compounds such as alicyclic epoxy compounds having an epoxy group bonded to an alicyclic ring, polyfunctional aliphatic epoxy compounds having two or more epoxy groups and no aromatic ring, monofunctional epoxy compounds having one epoxy group (excluding those included in alicyclic epoxy compounds), and polyfunctional aromatic epoxy compounds having two or more epoxy groups and an aromatic ring; oxetane compounds having one or more oxetane rings in the molecule; and combinations of these.

[0029] Examples of the radically polymerizable curable compound include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having a radically polymerizable double bond, or combinations thereof.

[0030] The active energy ray curable adhesive may contain a sensitizer such as a photosensitizing assistant, 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, a known sensitizer can be appropriately applied. When a sensitizer is blended, the blending amount is preferably in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the total amount of the active energy ray curable adhesive.

[0031] The active energy ray-curable adhesive may contain additives such as an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow adjuster, a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent, and a solvent, as necessary.

[0032] When an active energy ray curing adhesive is used, the adhesive layer can be formed by irradiating the adhesive coating layer with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays to cure the adhesive. As the active energy ray, ultraviolet rays are preferred, and as the light source in this case, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps, etc. can be used.

[0033] When an adhesive is used as the first bonding layer 21, the thickness is determined depending on the adhesive strength, but is usually in the range of 0.02 to 10 μm. From the viewpoint of further improving durability against external forces, it is preferable that the thickness of the adhesive layer is 1 to 4 μm.

[0034] [Linear polarizing plate] The linear polarizing plate 10 may be any film having a polarizing function that obtains linearly polarized light from transmitted light. Examples of such films include stretched films adsorbed with a dye having absorption anisotropy, or films containing a film coated with a dye having absorption anisotropy as a polarizer. Examples of dyes having absorption anisotropy include dichroic dyes. Examples of films coated with a dye having absorption anisotropy that are used as polarizers include stretched films adsorbed with a dye having absorption anisotropy, or films having a liquid phase layer obtained by applying a composition containing a dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal.

[0035] <Linear polarizing plate having a stretched film as a polarizer> A linear polarizing plate having a stretched film adsorbed with a dye having absorption anisotropy as a polarizer will be described. The stretched film adsorbed with a dye having absorption anisotropy, which is a polarizer, is usually manufactured through a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, a process of treating the polyvinyl alcohol-based resin film adsorbed with the dichroic dye with a boric acid aqueous solution, and a process of washing with water after the treatment with the boric acid aqueous solution. Such a polarizer may be used as a linear polarizing plate as it is, or a transparent protective film may be attached to at least one surface of such a polarizer and used as a linear polarizing plate.

[0036] The thickness of the polarizer obtained by thus subjecting the polyvinyl alcohol-based resin film to uniaxial stretching, dyeing with a dichroic dye, treating with boric acid, washing with water and drying is preferably 5 to 40 μm, more preferably 15 μm or less, and even more preferably 10 μm or less.

[0037] The material of the protective film to be attached to one or both sides of the polarizer is not particularly limited, and examples thereof include films known in the art, such as cyclic polyolefin resin films, cellulose acetate resin films made of resins such as triacetyl cellulose and diacetyl cellulose, 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. 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 the tensile modulus at a temperature of 23° C. is 2000 MPa or more, the protective film does not easily function as a relaxation layer against external forces, so that durability against external forces is reduced and problems such as peeling between the retardation layers are likely to occur. In addition, the protective film on the viewing side may or may not have a retardation.

[0038] The protective film can be attached to one or both sides of the polarizer via an attachment layer (hereinafter referred to as a "second attachment layer").

[0039] <Linear polarizing plate equipped with a film having a liquid crystal layer as a polarizer> A linear polarizing plate comprising a film having a liquid crystal layer as a polarizer will be described. Examples of a film coated with a dye having absorption anisotropy and used as a polarizer include a film obtained by coating a composition containing a dichroic dye having liquid crystal properties, or a composition containing a dichroic dye and a liquid crystal compound. The film may be used alone as a linear polarizing plate, or may be used as a linear polarizing plate with a protective film on one or both sides. Examples of the protective film include the same film as the linear polarizing plate comprising the above-mentioned stretched film as a polarizer. The protective film is attached to one or both sides of the polarizer via a second attachment layer. It is possible.

[0040] The film coated with the dye having absorption anisotropy is preferably thin, but if it is too thin, the strength decreases and the 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 further preferably 0.5 μm or more and 3 μm or less.

[0041] Specific examples of the film coated with a dye having absorption anisotropy include the films described in JP-A-2013-33249 and the like.

[0042] One embodiment of the linear polarizing plate has a configuration in which a protective film is provided on the surface of the linear polarizing plate opposite to the first bonding layer.

[0043] <Frontmost layer> The linear polarizing plate 10 may have an antireflection layer on the front surface. The antireflection layer has a function of preventing reflected light of external light from being visible on the surface of the linear polarizing plate 10, and can be formed by a conventional method for forming an antireflection layer, such as a coating method, a sputtering method, or a vacuum deposition method. The antireflection layer may be formed in advance on the front side of a protective film provided on the front side of the linear polarizing plate 10, and the linear polarizing plate with an antireflection layer may be constructed using such a protective film, or may be provided separately from the protective film.

[0044] The linear polarizing plate 10 may have a surface treatment layer other than the antireflection layer on the front surface thereof. Examples of such a surface treatment layer include a hard coat layer, an anti-sticking layer, an anti-glare layer, and a diffusion layer.

[0045] [Retardation plate] The retardation plate 30 has a first retardation layer 31 and a second retardation layer 32, and the first retardation layer 31 and the second retardation layer 32 contain a cured product of a liquid crystal compound, and there is no limitation as long as the peel strength between the first retardation layer 31 and the second retardation layer 32 is 1.0 N / 25 mm or less. The retardation plate 30 may have 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.

[0046] The retardation plate 30 preferably has optical characteristics represented 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 may have the optical characteristics represented by formulas (1) and (2), or at least two selected from the first retardation layer 31, the second retardation layer 32, and the third retardation layer may be combined to exhibit the optical characteristics represented by formulas (1) and (2). Re(450) / Re(550)≦1.00 (1) 1.00≦Re(650) / Re(550) (2)

[0047] 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.

[0048] <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 orientation state of the polymerizable liquid crystal or the stretching method of the stretched film. The layer formed by polymerizing the polymerizable liquid crystal contains a cured product of a 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.

[0049] (Layer formed by polymerizing polymerizable liquid crystal) In this specification, the optical axis of the polymerizable liquid crystal is defined as being aligned horizontally to the substrate plane as horizontal alignment, and the optical axis of the polymerizable liquid crystal is defined as being aligned perpendicularly to the substrate plane as vertical alignment. The optical axis refers to the direction in which a cross section cut perpendicular to the optical axis of an index ellipsoid formed by the orientation of the polymerizable liquid crystal is a circle, that is, the direction in which the refractive indexes in the three directions are all equal.

[0050] The polymerizable liquid crystal may be a rod-shaped polymerizable liquid crystal or a disk-shaped polymerizable liquid crystal. When the rod-shaped polymerizable liquid crystal is aligned horizontally or vertically to the substrate, the optical axis of the polymerizable liquid crystal coincides with the long axis direction of the polymerizable liquid crystal. When the disk-shaped polymerizable liquid crystal is aligned, the optical axis of the polymerizable liquid crystal is in a direction perpendicular to the disk surface of the polymerizable liquid crystal.

[0051] The direction of the slow axis of a stretched film varies depending on the stretching method, and the slow axis and optical axis are determined according to the stretching method, such as uniaxial, biaxial or oblique stretching.

[0052] In order for the layer formed by polymerizing the polymerizable liquid crystal to exhibit an in-plane retardation, the polymerizable liquid crystal may be aligned in an appropriate direction. When the polymerizable liquid crystal is rod-shaped, the in-plane retardation is exhibited by aligning the optical axis of the polymerizable liquid crystal horizontally to the substrate plane, in which case the optical axis direction and the slow axis direction are the same. When the polymerizable liquid crystal is disc-shaped, the in-plane retardation is exhibited by aligning the optical axis of the polymerizable liquid crystal horizontally to the substrate plane, in which case the optical axis and the slow axis are perpendicular to each other. The alignment state of the polymerizable liquid crystal can be adjusted by the combination of the alignment film and the polymerizable liquid crystal.

[0053] The in-plane retardation value of the retardation layer can be adjusted by the thickness of the retardation layer. Since the in-plane retardation value is determined by formula (11), the desired in-plane retardation value (Re(λ)) can be obtained by adjusting Δn(λ) and the film thickness d. Re(λ)=d×Δn(λ) (11) In the formula, Re(λ) represents the in-plane retardation value at a wavelength of λ nm, d represents the film thickness, and Δn(λ) represents the birefringence at a wavelength of λ nm.

[0054] The birefringence Δn(λ) is obtained by measuring the in-plane retardation value and dividing it by the thickness of the retardation layer. In a specific measurement method, a film formed on a substrate such as a glass substrate that does not have an in-plane retardation in itself is measured, so that the actual characteristics of the retardation layer can be measured.

[0055] In this specification, the refractive indices in three directions in an index ellipsoid formed by the orientation of a polymerizable liquid crystal or the stretching of a film are represented as nx, ny, and nz. nx represents the principal refractive index in a direction parallel to the film plane in an index ellipsoid formed by a retardation layer. ny represents the principal refractive index in a direction parallel to the film plane. In the index ellipsoid formed by the retardation layer, nz represents the refractive index in a direction parallel to the film plane and perpendicular to the direction of nx. In the index ellipsoid formed by the retardation layer, nz represents the refractive index in a direction perpendicular to the film plane.

[0056] When the optical axis of the rod-shaped polymerizable liquid crystal is oriented horizontally with respect to the substrate plane, the refractive index relationship of the resulting retardation layer is nx > ny ≒ nz (positive A plate), and the axis in the nx direction and the slow axis in the refractive index ellipsoid coincide. The axis in the nx direction and the slow axis coincide.

[0057] Also, when the optical axis of the disk-shaped polymerizable liquid crystal is oriented horizontally with respect to the substrate plane, the refractive index relationship of the resulting retardation layer is nx < ny ≒ nz (negative A plate), and the axis in the ny direction and the slow axis in the refractive index ellipsoid coincide. The axis in the ny direction and the slow axis coincide.

[0058] 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 this specification, exhibiting a retardation in the thickness direction means that in formula (20), Rth (retardation value in the thickness direction) shows a characteristic of being negative. Rth can be calculated from the retardation value (R 40 ) measured by tilting 40 degrees with the in-plane fast axis as the tilt axis and the in-plane retardation value (Re). That is, Rth can be calculated by obtaining nx, ny, and nz from Re, R 40 , d (thickness of the retardation layer), and n0 (average refractive index of the retardation layer) according to the following formulas (21) to (23) and substituting them into formula (20). It can be calculated by substituting them into formula (20). Rth = [(nx + ny) / 2 - nz] × d (20) Re = (nx - ny) × d (21) R 40 = (nx - ny') × 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 Also, nx, ny, and nz are the same as the above definitions.

[0059] When the polymerizable liquid crystal is rod-shaped, a retardation in the thickness direction is developed by orienting the optical axis of the polymerizable liquid crystal perpendicular to the substrate plane. When the polymerizable liquid crystal is disk-shaped, a retardation in the thickness direction is developed by orienting the optical axis of the polymerizable liquid crystal horizontally with respect to the substrate plane. In the case of a disk-shaped polymerizable liquid crystal, since the optical axis of the polymerizable liquid crystal is parallel to the substrate plane, to determine Re and since the thickness is fixed, Rth is uniquely determined. However, in the case of a rod-shaped polymerizable liquid crystal, since the optical axis of the polymerizable liquid crystal is perpendicular to the substrate plane, Rth can be adjusted without changing Re by adjusting the thickness of the retardation layer.

[0060] When the optical axis of the rod-shaped polymerizable liquid crystal is oriented perpendicular to the substrate plane, the refractive index relationship of the resulting retardation layer is nx≒ny < nz (positive C-plate), and in the refractive index ellipsoid the axis in the direction of nz coincides with the slow axis direction.

[0061] Also, when the optical axis of the disk-shaped polymerizable liquid crystal is oriented parallel to the substrate plane, the refractive index relationship of the resulting retardation layer is nx < ny≒nz (negative A-plate), and in the refractive index ellipse the axis in the direction of ny coincides with the slow axis direction.

[0062] <Polymerizable liquid crystal> The polymerizable liquid crystal is a compound having a polymerizable group and liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The liquid crystallinity of the polymerizable liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and when the thermotropic liquid crystal is classified according to the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.

[0063] 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). As the rod-shaped polymerizable liquid crystal, a liquid crystal having a T-shaped or H-shaped mesogen structure that is oriented perpendicular to the molecular axis and has birefringence is preferred from the viewpoint of wavelength dispersion, and a T-shaped liquid crystal is more preferred from the viewpoint of obtaining stronger dispersion. A preferred example of the T-shaped liquid crystal structure is a compound represented by the following formula (A).

[0064] (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).

[0065] [ka]

[0066] In formula (A), Ar represents a divalent aromatic group which may have a substituent. The divalent aromatic group preferably 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 may be bonded to each other via a divalent bonding group such as a single bond, -CO-O-, or -O-. G 1 and G 2 each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. L 1 , L 2 、 B 1 and B. 2 each independently represents a single bond or a divalent linking group. k and l each independently represent an integer of 0 to 3, and satisfy the relationship of 1≦k+l. Here, when 2≦k+l, B 1 and B. 2 , G 1 and G 2 may be the same as or different from each other. E 1 and E 2 each independently represents an alkanediyl group having 1 to 17 carbon atoms, in which a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and -CH2- contained in the alkanediyl group may be substituted with -O-, -S-, or -COO-, and when there are a plurality of -O-, -S-, or -COO-, they are not adjacent to each other. 1 and P 2 each independently represents a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

[0067] G 1 and G 2are 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, or 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, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group. In addition, there are multiple G 1 and G 2 At least one of L is preferably a divalent alicyclic hydrocarbon group. 1 Or L 2 G binds to 1 and G 2 It is more preferable that at least one of the groups is a divalent alicyclic hydrocarbon group.

[0068] 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 O.C.O.R. a6 -, R a7 OC=OOR a8 -, -N=N-, -CR c =CR d -, or C≡C-, where R a1 ~R a8 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms; R c and R d represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. 1 and L 2 are each independently preferably a single bond, -OR a2-1 -, -CH2-, -CH2CH2 -,-COORa4-1 - or OCOR a6-1 -, where R a2-1 , R a4-1 , R a6-1 Each independently represents a single bond, -CH2-, or -CH2CH2-. 1 and L 2 are each independently more preferably a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, or OCO-.

[0069] 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(=O)OR a16 -, where R a9 ~R a16 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. 1 and B. 2 are each independently preferably a single bond, -OR a10-1 -, -CH2-, -CH2CH2-, -COOR a12-1 - or OCOR a14-1 -, where R a10-1 , R a12-1 , R a14-1 Each independently represents a single bond, -CH2-, or -CH2CH2-. B 1 and B. 2 are each independently more preferably a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, -OCO-, or -OCOCH2CH2-.

[0070] 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. When k=2 and l=2, a symmetrical structure is obtained, which is preferable.

[0071] E 1 and E 2 are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms.

[0072] P 1 Or P 2 Examples of the polymerizable group represented by the formula (I) include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

[0073] 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, and an anthracene ring, and the like, and the benzene ring and the naphthalene ring are preferable. Examples of the aromatic heterocycle 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, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, it is preferable that Ar has a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is more preferable that Ar has a benzothiazole group. In addition, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has a π electron.

[0074] In formula (A), the total number of π electrons contained in the divalent aromatic group represented by Ar is N πis preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. Also, it is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

[0075] Suitable examples of the aromatic group represented by Ar include the following groups:

[0076] [ka]

[0077] In formulae (Ar-1) to (Ar-23), * represents a linking portion, Z 0 , Z 1 and Z 2 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

[0078] Q 1 , Q 2 and Q 3 are each independently -CR 2’ R 3’ -, -S-, -NH-, -NR 2’ represents -, -CO- or O-; R 2’ and R 3’ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0079] J 1 , and J 2 each independently represents a carbon atom or a nitrogen atom.

[0080] Y 1 , Y2 and Y 3 each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group.

[0081] W 1 and W 2 each independently represents a hydrogen atom, a cyano group, a methyl group or a halogen atom; and m represents an integer of 0 to 6.

[0082] Y 1 , Y 2 and Y 3 Examples of the aromatic hydrocarbon group in the formula (I) include aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, of which a phenyl group and a naphthyl group are preferred, and a phenyl group is more preferred. Examples of the aromatic heterocyclic group in the formula (I) include aromatic heterocyclic groups 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, of which a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferred.

[0083] Y 1 , Y 2 and Y 3 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

[0084] Z 0 , Z 1 and Z 2 are each preferably independently 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; Z 0 is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group; Z 1 and Z 2is more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

[0085] Q 1 , Q 2 and Q 3 -NH-, -S-, -NR 2’ -, -O- are preferred, R 2’ is preferably a hydrogen atom, and among these, -S-, -O-, and -NH- are particularly preferable.

[0086] Among the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability. In formulas (Ar-16) to (Ar-23), Y 1 is the nitrogen atom to which it is bonded and Z 0 and may form an aromatic heterocyclic group. Examples of the aromatic heterocyclic group include those mentioned above as aromatic heterocyclic rings that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. In addition, Y 1 is the nitrogen atom to which it is bonded and Z 0 In addition, it may be the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group, for example, a benzofuran ring, a benzothiazole ring, a benzoxazole ring, etc.

[0087] (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 polymerizable liquid crystal (B). P11-B11-E11-B12-A11-B13- (X)

[0088] In formula (X), P11 represents a polymerizable group. A11 represents a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. A hydrogen atom contained in the divalent alicyclic hydrocarbon group or the divalent aromatic hydrocarbon group is substituted with 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 atoms 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 fluorine atoms. B11 is -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR 16 -, -NR 16 Represents -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-, -CH2-CH2-, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)-, -OC(=O)-O-, -CH=N-, -N=CH-, -N=N-, -C(=O)-NR 16 -, -NR 16 It represents -C(=O)-, -OCH2-, -OCF2-, -CH2O-, -CF2O-, -CH=CH-C(=O)-O-, -OC(=O)-CH=CH- or a single bond. E11 represents an alkanediyl group having 1 to 12 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH2- constituting the alkanediyl group may be substituted with -O- or -CO-.]

[0089] The number of carbon atoms in the aromatic hydrocarbon group and alicyclic hydrocarbon group of A11 is preferably in the range of 3 to 18, more preferably in the range of 5 to 12, and particularly preferably 5 or 6. A11 is preferably a cyclohexane-1,4-diyl group or a 1,4-phenylene group.

[0090] E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms. -CH2- constituting the alkanediyl group may be replaced with -O-. Specific examples include linear alkanediyl groups having 1 to 12 carbon atoms, such as a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, and a dodecane-1,12-diyl group; -CH2-CH2-O-CH2-CH2-, -CH2-CH2-O-CH2-CH2-O-CH2-CH2-, and -CH2-CH2-O-CH2-CH2-O-CH2-CH2-O-CH2-CH2-. As B11, -O-, -S-, -CO-O-, and -O-CO- are preferable, and among them, -CO-O- is more preferable. As B12 and B13, each independently, -O-, -S-, -C(=O)-, -C(=O)-O-, -OC(=O)- or -OC(=O)-O- is preferable, and among them, -O- or -OC(=O)-O- is more preferable.

[0091] As the polymerizable group represented by P11, a radically polymerizable group or a cationic polymerizable group is preferred from the viewpoint of high polymerization reactivity, particularly high photopolymerization reactivity. In addition, the polymerizable group is preferably a group represented by the following formulae (P-11) to (P-15), since it is easy to handle and the liquid crystal compound can be easily produced.

[0092] [ka]

[0093] [In formulas (P-11) to (P-15), R 17 ~R 21 each independently represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom.

[0094] Specific examples of the groups represented by formulae (P-11) to (P-15) include groups represented by the following formulae (P-16) to (P-20).

[0095] [ka]

[0096] P11 is preferably a group represented by formula (P-14) to formula (P-20), and more preferably a vinyl group, a p-stilbene group, an epoxy group or an oxetanyl group. The group represented by P11-B11- is more preferably an acryloyloxy group or a methacryloyloxy group.

[0097] The polymerizable liquid crystal (B) may be a compound 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 each independently have the same meaning as A11, B14 to B16 each independently have the same meaning as B12, B17 has the same meaning as B11, and E12 has the same meaning as E11. F11 represents 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 (-SO3H), a carboxy group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and -CH2- constituting the alkyl group and the alkoxy group may be replaced with -O-.

[0098] Specific examples of the polymerizable liquid crystal (B) include compounds having a polymerizable group among the compounds described in “3.8.6 Network (completely crosslinked type)” and “6.5.1 Liquid crystal materials b. Polymerizable nematic liquid crystal materials” in the Liquid Crystal Handbook (edited by the Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000), and the polymerizable liquid crystals described in JP-A Nos. 2010-31223, 2010-270108, 2011-6360, and 2011-207765.

[0099] Specific examples of the polymerizable liquid crystal (B) include those represented by the following formulae (I-1) to (I-4), (II-1) to (II-4), (III-1) to (III-26), (IV-1) to (IV-26), (V-1) to (V-2), and (VI-1) to (VI-6). In the following formula, k1 and k2 each independently represent an integer of 2 to 12. These polymerizable liquid crystals (B) are preferable in terms of ease of synthesis or availability.

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] [ka]

[0107] [ka]

[0108] [ka]

[0109] An example of the discotic polymerizable liquid crystal is a compound containing a group represented by formula (W) (hereinafter, sometimes referred to as polymerizable liquid crystal (C)).

[0110] [ka] [In formula (W), R 40 represents the following formulas (W-1) to (W-5).

[0111] [ka]

[0112] X 40 and Z 40represents an alkyl group having 1 to 12 carbon atoms, a hydrogen atom contained in the alkyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH2- constituting the alkyl group may be replaced with -O- or -CO-.

[0113] Specific examples of polymerizable liquid crystals (C) are given in "6.5.1 Liquid crystal materials b. Polymerizable nematic liquid crystal materials" in the Liquid Crystal Handbook (edited by the Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2000). 6.21" and the polymerizable liquid crystals described in JP-A-7-258170, JP-A-7-30637, JP-A-7-309807, and JP-A-8-231470.

[0114] 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, or by combining a layer having the optical properties represented by formulas (4), (6), and (7) with a layer having the optical properties represented by formulas (5), (6), and (7) in 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)

[0115] 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 light leakage during black display of a display device such as an organic EL display device can be suppressed.

[0116] The polymerizable liquid crystal having the specific structure may be, for example, the polymerizable liquid crystal (A). By orienting the polymerizable liquid crystal (A) so that the optical axis is horizontal to the substrate plane, a retardation layer having the optical properties represented by formulas (1) and (2) can be obtained, and further, by adjusting the film thickness according to formula (10), a retardation layer having a desired in-plane retardation value such as the optical property represented by formula (4) can be obtained. 100nm <Re(550)<160nm (4)

[0117] Methods for combining layers having the optical properties represented by formulas (4), (6), and (7) with layers having the optical properties represented by formulas (5), (6), and (7) in a specific slow axis relationship include well-known methods. For example, JP-A Nos. 2001-4837, 2001-21720, and 2000-206331 disclose retardation films having at least two retardation layers made of a liquid crystal compound.

[0118] The retardation layer having the optical properties represented by the above formulas (6) and (7) can be obtained by a known method. That is, the retardation layer obtained by a method other than the method for obtaining the retardation layer having the optical properties represented by the above formulas (1) and (2) generally has the optical properties represented by the formulas (6) and (7).

[0119] (1st retardation layer) The first retardation layer 31 preferably has optical characteristics represented by formula (4) (in this specification, a retardation layer satisfying the optical characteristics represented by formula (4) is also referred to as a "λ / 4 layer"), and more preferably has optical characteristics represented by formula (4-1). The in-plane retardation value Re(550) can be adjusted by the same method as the adjustment method of the in-plane retardation value of the retardation layer. 100nm <Re(550)<160nm (4) 130nm <Re(550)<150nm (4-1)

[0120] Furthermore, the first retardation layer preferably has optical properties represented by formulas (1) and (2) (in this specification, the optical properties represented by formulas (1) and (2) are also referred to as "reverse dispersion".) Such optical properties can be obtained by the same method as the retardation layer. Re(450) / Re(550)≦1.00 (1) 1.00≦Re(650) / Re(550) (2)

[0121] The first retardation layer preferably has a layer A having optical properties represented by formulas (4), (6), and (7), and a layer B having optical properties represented by formulas (5), (6), and (7). Such optical properties can be obtained by the same method as the retardation layer. 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 the optical property represented by formula (4-1), and Layer B is preferably a layer having the optical property represented by formula (5-1). 130nm <Re(550)<150nm (4-1) 265nm <Re(550)<285nm (5-1)

[0122] In addition, when the retardation plate has a third retardation layer, the first retardation layer preferably has optical properties represented by formulas (6) and (7). Such optical properties can be obtained in the same manner as the above-mentioned retardation layer. Re(450) / Re(550)≧1.00 (6) 1.00≧Re(650) / Re(550) (7)

[0123] The first retardation layer is a coating layer formed by polymerizing one or more polymerizable liquid crystals. When the first retardation layer is composed of one retardation layer and has the optical properties represented by formulas (1) and (2), it is preferable that the retardation layer is a coating layer formed by polymerizing a polymerizable liquid crystal (A). When the second retardation layer has the optical properties represented by formulas (6) and (7), it is preferable that the retardation layer is a coating layer formed by polymerizing a polymerizable liquid crystal (B).

[0124] The layer A is preferably a coating layer formed by polymerizing a polymerizable liquid crystal (B). The layer B is preferably a coating layer formed by polymerizing a polymerizable liquid crystal (C).

[0125] 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. The thickness of the first retardation layer can be measured by an interference thickness meter, a laser microscope, or a stylus thickness meter.

[0126] (Second retardation layer) The second retardation layer 32 preferably has the optical characteristic represented by formula (3) (positive C plate). nx≒ny <nz (3)

[0127] The in-plane retardation value Re(550) of the second retardation layer is usually in the range of 0 to 10 nm, and preferably in the range of 0 to 5 nm. The thickness direction retardation value Rth(550) is usually in the range of −10 to −300 nm, and preferably in the range of −20 to −200 nm. The in-plane retardation value Re(550) and the thickness direction retardation value Rth(550) are in the same direction as the above retardation layer. This can be adjusted by law.

[0128] The second retardation layer is a coating layer formed by polymerizing one or more polymerizable liquid crystals, and more preferably is a coating layer formed by polymerizing a polymerizable liquid crystal (B).

[0129] The second retardation layer is a layer formed by polymerizing a polymerizable liquid crystal, and its thickness is usually 10 μm or less, preferably 5 μm or less, more preferably 0.3 μm or more and 3 μm or less. The thickness of the second retardation layer can be obtained by the same method as that of the first retardation layer. In addition, it is preferable that the thickness of the first retardation layer and the second retardation layer is 5 μm or less, respectively.

[0130] (Third retardation layer) The third retardation layer preferably has an optical characteristic represented by formula (5), more preferably has an optical characteristic represented by formula (5-1). The in-plane retardation value Re(550) can be adjusted by the same method as the adjustment method of the in-plane retardation value of the above retardation layer. 200nm <Re(550)<320nm (5) 265nm <Re(550)<285nm (5-1)

[0131] Moreover, the third retardation layer preferably has optical properties represented by the formulas (6) and (7). Such optical properties can be obtained by the same method as for the above retardation layer. Re(450) / Re(550)≧1.00 (6) 1.00≧Re(650) / Re(550) (7)

[0132] The third retardation layer is preferably a coating layer formed by polymerizing one or more polymerizable liquid crystals, more preferably a coating layer formed by polymerizing the polymerizable liquid crystal (B) or (C).

[0133] 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, more preferably 10 μm or more and 50 μm or less. In the case of a layer formed by polymerizing a polymerizable liquid crystal, its thickness is usually 10 μm or less, preferably 5 μm or less, more preferably 0.5 μm or more and 5 μm or less. The thickness of the third retardation layer can be obtained by the same method as that of the first retardation layer.

[0134] (base material) The retardation plate 30 may have a substrate. The substrate is usually a transparent substrate. The transparent substrate means a substrate having transparency capable of transmitting light, particularly visible light, and transparency means a property in which the transmittance for light rays having a wavelength of 380 to 780 nm is 80% or more. A specific transparent substrate is a light-transmitting resin substrate. Resins constituting the light-transmitting resin substrate include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene-based polymers; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide, and polyphenylene oxide. From the viewpoints of availability and transparency, polyethylene terephthalate, polymethacrylic acid esters, cellulose esters, cyclic olefin resins, and polycarbonates are preferred.

[0135] On the surface of the substrate on which the alignment film, the first retardation layer, the second retardation layer, and the third retardation layer are formed, Surface treatment may be performed before forming the alignment film or the retardation layer. Examples of the surface treatment method include a method of treating the surface of the substrate with corona or plasma under vacuum or atmospheric pressure, a method of laser-treating the substrate surface, a method of ozone-treating the substrate surface, a method of saponifying the substrate surface or a method of flame-treating the substrate surface, a primer treatment method in which a coupling agent is applied to the substrate surface, and a graft polymerization method in which a reactive monomer or a polymer having a reactivity is attached to the substrate surface and then reacted by irradiating radiation, plasma or ultraviolet light. Among these, a method of corona- or plasma-treating the substrate surface under vacuum or atmospheric pressure is preferred.

[0136] Methods for performing surface treatment of a substrate with corona or plasma include a method in which the substrate is placed between opposing electrodes under a pressure close to atmospheric pressure and corona or plasma is generated to perform surface treatment of the substrate, a method in which a gas is caused to flow between opposing electrodes, the gas is converted into plasma between the electrodes, and the plasmatized gas is sprayed onto the substrate, and a method in which glow discharge plasma is generated under low pressure conditions to perform surface treatment of the substrate.

[0137] Among these, a method of placing a substrate between opposing electrodes under a pressure close to atmospheric pressure, generating a corona or plasma to perform surface treatment of the substrate, or a method of flowing a gas between opposing electrodes, converting the gas into plasma between the electrodes, and spraying the plasma gas onto the substrate is preferred. Such surface treatment using corona or plasma is usually performed using a commercially available surface treatment device.

[0138] The substrate is preferably a substrate having a small retardation. Examples of substrates having a small retardation include cellulose ester films having no retardation, such as Zerotack (registered trademark) (Konica Minolta Opto Co., Ltd.) and Z-tack (Fujifilm Corporation). Unstretched cyclic olefin resin substrates are also preferred.

[0139] In addition, the surface of the substrate 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 a hard coat treatment, an antistatic treatment, etc. In addition, the substrate may contain additives such as an ultraviolet absorbing agent within a range that does not affect the performance.

[0140] If the substrate is too thin, the strength decreases and the processability tends to be poor, so the thickness is usually 5 to 300 μm, and preferably 10 to 200 μm.

[0141] (Polymerizable liquid crystal composition) A layer (retardation layer) formed by polymerizing a polymerizable liquid crystal is usually formed by applying a composition containing one or more polymerizable liquid crystals (hereinafter, sometimes referred to as a polymerizable liquid crystal composition) onto a substrate, an alignment film, a protective layer, or a retardation layer, and polymerizing the polymerizable liquid crystal in the resulting coating film.

[0142] The polymerizable liquid crystal composition usually contains a solvent, and the solvent is preferably a solvent capable of dissolving the polymerizable liquid crystal and is inactive in the polymerization reaction of the polymerizable liquid crystal. Specific examples of the solvent 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; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, methyl amyl ketone, methyl isobutyl ketone, and N-methyl-2-pyrrolidinone; non-chlorinated aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; non-chlorinated aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as propylene glycol monomethyl ether, tetrahydrofuran, and dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These other solvents may be used alone or in combination.

[0143] 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, relative to 100 parts by mass of the solid content. The solid content means the total of the components excluding the solvent from the polymerizable liquid crystal composition.

[0144] The polymerizable liquid crystal composition is usually applied by a known method such as a coating method such as a spin coating method, an extrusion method, a gravure coating method, a die coating method, a slit coating method, a bar coating method, or an applicator method, or a printing method such as a flexography method. After application, the solvent is usually removed under conditions in which the polymerizable liquid crystal contained in the obtained coating film does not polymerize, thereby forming a dried film. Examples of the drying method include natural drying, ventilation drying, heat drying, and reduced pressure drying.

[0145] (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 solvent resistance that does not dissolve the polymerizable liquid crystal composition when applied, and also has heat resistance in a heat treatment for removing the solvent and orienting the polymerizable liquid crystal. Examples of such an alignment film include an alignment film containing an alignment polymer, a photoalignment film, and a groove alignment film that forms a concave-convex pattern or a plurality of grooves on the surface to achieve alignment.

[0146] Examples of the oriented polymer include polyamides and gelatins having an amide bond in the molecule, polyimides having an imide bond in the molecule, and polyamic acids, which are hydrolyzates thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred. Two or more oriented polymers may be used in combination.

[0147] An alignment film containing an alignment polymer is usually obtained by applying a composition in which an alignment polymer is dissolved in a solvent (hereinafter, sometimes referred to as an alignment polymer composition) to a substrate and then removing the solvent, or by applying an alignment polymer composition to a substrate, removing the solvent, and rubbing the substrate (rubbing method).

[0148] Examples of the solvent include water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, and other alcohol solvents, ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, ethyl lactate, and other ester solvents, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, methyl isobutyl ketone, and other ketone solvents, pentane, hexane, heptane, and other aliphatic hydrocarbon solvents, toluene, xylene, and other aromatic hydrocarbon solvents, acetonitrile, and other nitrile solvents, tetrahydrofuran, dimethoxyethane, and other ether solvents, and chloroform, chlorobenzene, and other chlorinated hydrocarbon solvents. These solvents may be used alone or in combination of two or more.

[0149] The concentration of the oriented polymer in the oriented polymer composition may be within a range in which the oriented polymer material can be completely dissolved in the solvent, and is preferably 0.1 to 20% in terms of solid content relative to the solution, and more preferably about 0.1 to 10%.

[0150] As the oriented polymer composition, a commercially available alignment film material may be used as it is. Examples of commercially available alignment film materials include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark, manufactured by JSR Corporation).

[0151] Examples of the method for applying the oriented polymer composition to the substrate include known methods such as spin coating, extrusion, gravure coating, die coating, slit coating, bar coating, and applicator coating, and printing methods such as flexography. When the retardation layer is produced by a continuous production method in the roll-to-roll format described later, the coating method generally employs a printing method such as gravure coating, die coating, or flexography.

[0152] Methods for removing the solvent contained in the orientable polymer composition include natural drying, ventilation drying, heat drying, and reduced pressure drying.

[0153] In order to impart an alignment control force to the alignment film, rubbing can be carried out as necessary (rubbing method).

[0154] An example of a method for imparting an orientation control force by a rubbing method is to bring an oriented polymer film formed on the surface of a substrate by applying an oriented polymer composition to the substrate and annealing the composition into contact with a rotating rubbing roll wrapped with a rubbing cloth.

[0155] In order to impart an alignment control force to the alignment film, photo-alignment can be performed as necessary (photo-alignment method).

[0156] A photo-alignment film is usually obtained by applying a composition containing a polymer or monomer having a photoreactive group and a solvent (hereinafter, sometimes referred to as a "photo-alignment film-forming composition") to a substrate and irradiating the substrate with light (preferably polarized UV). Photo-alignment films are more preferable in that the direction of the alignment control force can be arbitrarily controlled by selecting the polarization direction of the irradiated light.

[0157] The photoreactive group refers to a group that generates liquid crystal alignment ability by irradiation with light. Specifically, it includes groups involved in photoreactions that are the origin of liquid crystal alignment ability, such as molecular alignment induction caused by light irradiation or isomerization reaction, dimerization reaction, photocrosslinking reaction or photodecomposition reaction. Among them, groups involved in dimerization reaction or photocrosslinking reaction are preferred in terms of excellent alignment ability. As the photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferred, and a group having at least one selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond) and a carbon-oxygen double bond (C=O bond) is particularly preferred.

[0158] Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazolyl groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having an azoxybenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

[0159] Among them, photoreactive groups involved in photodimerization reactions are preferred, and cinnamoyl and chalcone groups are preferred because the amount of polarized light irradiation required for photoalignment is relatively small and a photoalignment film having excellent thermal stability and stability over time is easily obtained. As the polymer having a photoreactive group, a polymer having a cinnamoyl group at the end of the side chain of the polymer is particularly preferred, which has a cinnamoyl group that forms a cinnamic acid structure. preferable.

[0160] A photo-alignment-inducing layer can be formed on a substrate by applying the composition for forming a photo-alignment film on the substrate. The solvent contained in the composition can be the same as the solvent contained in the above-mentioned alignment polymer composition, and can be appropriately selected depending on the solubility of the polymer or monomer having a photoreactive group.

[0161] The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be appropriately adjusted depending on the type of polymer or monomer and the thickness of the intended photo-alignment film, but is preferably at least 0.2% by mass, and more preferably in the range of 0.3 to 10% by mass. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, or a photosensitizer, within a range that does not significantly impair the properties of the photo-alignment film.

[0162] The method for applying the composition for forming a photo-alignment film to a substrate may be the same as the method for applying the alignable polymer composition to a substrate. The method for removing the solvent from the applied composition for forming a photo-alignment film may be the same as the method for removing the solvent from the alignable polymer composition.

[0163] The polarized light may be irradiated by directly irradiating the polarized UV light onto the composition for forming a photo-aligned film coated on the substrate after removing the solvent, or by irradiating the polarized light from the substrate side and transmitting the polarized light. In addition, 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 the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) having a wavelength of 250 to 400 nm is particularly preferable. Examples of light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, ultraviolet lasers such as KrF and ArF, and high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are more preferable. These lamps are preferable because they have a high emission intensity of ultraviolet light with a wavelength of 313 nm. The light from the light source can be irradiated by passing through an appropriate polarizer to irradiate the polarized UV light. As such a polarizer, a polarizing filter, a polarizing prism such as a Glan-Thompson or Glan-Taylor type polarizer, or a wire grid type polarizer can be used.

[0164] If masking is performed during rubbing or polarized light irradiation, a plurality of regions (patterns) in which the liquid crystal alignment directions are different can be formed.

[0165] A groove alignment film is a film that aligns liquid crystals by using a concave-convex pattern or multiple grooves on the film surface. HV Kennell et al. reported that when liquid crystal molecules are placed on a substrate with multiple equally spaced linear grooves, the liquid crystal molecules are oriented along the grooves (Physical Review A24(5), p. 2713, 1981).

[0166] Specific examples of obtaining a groove alignment film include a method in which a photosensitive polyimide surface is exposed through an exposure mask having slits in a periodic pattern, followed by development and rinsing to remove unnecessary polyimide film and form a concave-convex pattern; a method in which a UV-cured resin layer is formed on a plate-shaped master having grooves on its surface, the resin layer is transferred to a base film and then cured; and a method in which a base film on which a UV-cured resin layer has been formed is transported, and a roll-shaped master having a plurality of grooves is pressed against the surface of the UV-cured resin layer to form concave-convex patterns and then cured. Methods described in JP-A-6-34976 and JP-A-2011-242743 can be used.

[0167] In the above method, a roll-shaped master with multiple grooves is pressed against the surface of the UV-cured resin layer. A method in which the concaves and convexes are formed by heating the roll-shaped master and then curing the molded product is preferable. From the viewpoint of durability, stainless steel (SUS) can be used for the roll-shaped master.

[0168] As the UV curable resin, a polymer of a monofunctional acrylate, a polymer of a polyfunctional acrylate, or a polymer of a mixture thereof can be used. A monofunctional acrylate is a compound having one group (hereinafter sometimes referred to as a (meth)acryloyloxy group) selected from the group consisting of an acryloyloxy group (CH2=CH-COO-) and a methacryloyloxy group (CH2=C(CH3)-COO-) in the molecule.

[0169] Examples of 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, alkylated phenyl (meth)acrylates having 2 to 14 carbon atoms, methoxypolyethylene glycol (meth)acrylates, phenoxypolyethylene glycol (meth)acrylates, and isobornyl (meth)acrylates.

[0170] The polyfunctional acrylate is usually a compound having 2 to 6 (meth)acryloyloxy groups in the molecule.

[0171] Examples of bifunctional acrylates having two (meth)acryloyloxy groups include 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; bis(acryloyloxyethyl)ether of bisphenol A; ethoxylated bisphenol A di(meth)acrylate; propoxylated neopentyl glycol di(meth)acrylate; ethoxylated neopentyl glycol di(meth)acrylate, and 3-methylpentanediol di(meth)acrylate.

[0172] Examples of 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; tripentaerythritol tetra(meth)acrylate; tripentaerythritol penta(meth)acrylate; tripentaerythritol hexa(meth)acrylate; tripentaerythritol hepta(meth)acrylate; tripentaerythritol octa(meth)acrylate; pentaerythritol tri(meth)acrylate. )acrylate and acid anhydride reaction products;Reaction products of dipentaerythritol penta(meth)acrylate and acid anhydride;Reaction products 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;Caprolactone modified dipentaerythritol hexa(meth)acrylate;Caprolactone modified tripentaerythritol tetra(meth)acrylate;Caprolactone modified tripentaerythritol penta(meth)acrylate;Caprolactone modified tripentaerythritol hexa(meth)acry acrylate; caprolactone-modified tripentaerythritol hepta(meth)acrylate; caprolactone-modified tripentaerythritol octa(meth)acrylate; a reaction product of caprolactone-modified pentaerythritol tri(meth)acrylate and an acid anhydride; a reaction product of caprolactone-modified dipentaerythritol penta(meth)acrylate and an acid anhydride, and a reaction product of caprolactone-modified tripentaerythritol hepta(meth)acrylate and an acid anhydride. In the specific examples of the multifunctional acrylate shown here, (meth)acrylate means acrylate or methacrylate. In addition, caprolactone-modified means that a ring-opened product or a ring-opened polymer of caprolactone is introduced between the alcohol-derived site and the (meth)acryloyloxy group of the (meth)acrylate compound.

[0173] Commercially available products can also be used for such multifunctional acrylates. Examples of such commercially available 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.), "ARONIX M-220", "M-325", "M-240", "M-270", "M-309", "M-310", "M-321", "M-350", "M-360", "M-370", "M-380", "M-390", "M-400", "M-410", "M-420", "M-430", "M-440", "M-450", "M-460", "M-470", "M-480", "M-490", "M-500", "M-510", "M-520", "M-530", "M-540", "M-550", "M-550", "M-560", "M-570", "M-580", "M-590", "M-60 ... Examples of such copolymers include M-305, M-306, M-450, M-451, M-408, M-400, M-402, M-403, M-404, M-405, and M-406 (manufactured by Toa Gosei Co., Ltd.), EBECRYL11, EBECRYL145, EBECRYL150, EBECRYL40, EBECRYL140, EBECRYL180, DPGDA, HDDA, TPGDA, HPNDA, PETIA, PETRA, TMPTA, TMPEOTA, DPHA, and EBECRYL series (manufactured by Daicel-Cytec Co., Ltd.).

[0174] As for the unevenness of the groove alignment film, the width of the protrusions is preferably 0.05 to 5 μm, the width of the recesses is preferably 0.1 to 5 μm, and the depth of the unevenness is preferably 2 μm or less, more preferably 0.01 to 1 μm. Within these ranges, liquid crystal alignment with little alignment disorder can be obtained.

[0175] 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 further preferably in the range of 10 nm to 500 nm.

[0176] 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 made of a material that exerts a horizontal alignment restraining force as an alignment restraining force, the polymerizable liquid crystal can form a horizontal alignment or a hybrid alignment, and if the alignment film is made of a material that exerts a vertical alignment restraining force, the polymerizable liquid crystal can form a vertical alignment or an inclined alignment. If the alignment film is made of an alignment polymer, the alignment restraining force can be arbitrarily adjusted by the surface state or the rubbing conditions, and if the alignment film is made of a photoalignment polymer, the alignment restraining force can be arbitrarily adjusted by the polarized light irradiation conditions, etc. In addition, the liquid crystal alignment can also be controlled by selecting the physical properties of the polymerizable liquid crystal, such as the surface tension and liquid crystallinity.

[0177] Polymerization of the polymerizable liquid crystal can be carried out by a known method of polymerizing a compound having a polymerizable functional group.Specifically, it can be thermal polymerization or photopolymerization, and photopolymerization is preferred from the viewpoint of ease of polymerization.When polymerizing the polymerizable liquid crystal by photopolymerization, it is preferable to coat a polymerizable liquid crystal composition containing a photopolymerization initiator, dry the polymerizable liquid crystal in the dried coating obtained by drying, and then photopolymerize the polymerizable liquid crystal while maintaining the liquid crystal state.

[0178] Photopolymerization is usually performed by irradiating the dry film with light. The light to be irradiated is appropriately selected according to the type of photopolymerization initiator contained in the dry film, the type of polymerizable liquid crystal (particularly, the type of photopolymerizable group possessed by the polymerizable liquid crystal) and the amount thereof, and specifically includes light selected from the group consisting of visible light, ultraviolet light and laser light, and active electron beams. Among them, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and because photopolymerization devices widely used in this field can be used. It is preferable to select the type of polymerizable liquid crystal and photopolymerization initiator so that photopolymerization can be performed by ultraviolet light. In addition, the polymerization temperature can be controlled by irradiating light while cooling the dry film with an appropriate cooling means during polymerization. By adopting such a cooling means, if polymerization of the polymerizable liquid crystal is performed at a lower temperature, even if a substrate with relatively low heat resistance is used, a retardation layer can be appropriately formed. During photopolymerization, a patterned retardation layer can also be obtained by performing masking or development.

[0179] The polymerizable liquid crystal composition may contain a reactive additive. The reactive additive preferably has a carbon-carbon unsaturated bond and an active hydrogen reactive group in its molecule. The "active hydrogen reactive group" here means a group reactive to a group having active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), or an amino group (-NH2), and 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 contained in the reactive additive is usually 1 to 20, and preferably 1 to 10.

[0180] In the reactive additive, it is preferable that at least two active hydrogen reactive groups are present, and in this case, the multiple active hydrogen reactive groups present may be the same or different.

[0181] The carbon-carbon unsaturated bond of the reactive additive may be a carbon-carbon double bond or a carbon-carbon triple bond, or a combination thereof, but is preferably a carbon-carbon double bond. Among them, the reactive additive preferably contains a carbon-carbon unsaturated bond as a vinyl group and / or a (meth)acrylic group. Furthermore, the active hydrogen reactive group is preferably 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 preferred.

[0182] 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 an oxetane group, such as oxetane acrylate and oxetane methacrylate; 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 vinyl oxazoline and isopropenyl oxazoline; oligomers of compounds having a (meth)acrylic group and an isocyanate group, such as isocyanatomethyl acrylate, isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate, and 20-isocyanatoethyl methacrylate. In addition, compounds having a vinyl group or a vinylene group and an acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride, and vinyl maleic anhydride, can be mentioned. Among these, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyloxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, and oligomers thereof are preferred, and isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate, and oligomers thereof are particularly preferred.

[0183] Specifically, a compound represented by the following formula (Y) is preferred. [ka] [In formula (Y), n is an integer from 1 to 10, R 1’ 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. 2’ is -NH- on one side and >NC(=O)-R on the other side. 3’ R 3’ represents a hydroxyl group or a group having a carbon-carbon unsaturated bond. R in formula (Y) 3’ At least one R 3’ is a group having a carbon-carbon unsaturated bond.

[0184] Among the reactive additives represented by the formula (Y), a compound represented by the following formula (YY) (hereinafter, sometimes referred to as compound (YY)) is particularly preferred (n has the same meaning as above).

[0185] [ka] Compound (YY) may be a commercially available product, either as is or after purification as necessary. Examples of commercially available products include Laromer (registered trademark) LR-9000 (manufactured by BASF).

[0186] When the polymerizable liquid crystal composition contains a reactive additive, the content thereof is usually 0.1 to 30 parts by mass, and preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal.

[0187] The polymerizable liquid crystal composition preferably contains one or more leveling agents. The leveling agent has a function of adjusting the fluidity of the polymerizable liquid crystal composition and making the coating film obtained by coating the polymerizable liquid crystal composition flatter, and specifically includes a surfactant. The leveling agent is preferably at least one selected from the group consisting of leveling agents mainly composed of a polyacrylate compound and leveling agents mainly composed of a fluorine atom-containing compound.

[0188] Leveling agents based on polyacrylate compounds include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", "BYK-361N", "BYK-380", "BYK-381" and "BYK-392" [BYK Chemie].

[0189] Leveling agents containing fluorine-containing compounds as the main component include "Megafac (registered trademark) R-08", "R-30", "R-90", "F-410", "F-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" and "S-3 Examples of such products include "82", "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 Ltd.]; "F-TOP EF301", "F-TOP EF303", "F-TOP EF351" and "F-TOP EF352" [Mitsubishi Materials Electronic Chemicals Co., Ltd.].

[0190] When the polymerizable liquid crystal composition contains a leveling agent, the content is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal. When the content of the leveling agent is within the above range, the polymerizable liquid crystal is easily aligned horizontally, and the obtained polarizing layer tends to be smoother. When the content of the leveling agent relative to the polymerizable liquid crystal is within the above range, the obtained retardation layer tends to be less prone to unevenness.

[0191] The polymerizable liquid crystal composition preferably contains one or more polymerization initiators. The polymerization initiator is a compound capable of initiating the polymerization reaction of the polymerizable liquid crystal, and a photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions. Specifically, a photopolymerization initiator capable of generating active radicals or acids by the action of light is included, and among them, a photopolymerization initiator that generates radicals by the action of light is preferred.

[0192] The polymerization initiator includes a benzoin compound, a benzophenone compound, an alkylphenone compound, an acylphosphine oxide compound, a triazine compound, an iodonium salt, and a sulfonium salt.

[0193] Benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether.

[0194] Benzophenone compounds include benzophenone, o-benzoylmethylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone.

[0195] Examples of alkylphenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one.

[0196] The acylphosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0197] Examples of triazine compounds include 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, and 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl] 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.

[0198] The polymerization initiator may be commercially available. Commercially available polymerization initiators include "Irgacure (registered trademark) 907", "Irgacure (registered trademark) 184", "Irgacure (registered trademark) 651", "Irgacure (registered trademark) 819", "Irgacure (registered trademark) 250", "Irgacure (registered trademark) 369" (Ciba Japan Co., Ltd.); "Seikuol (registered trademark) BZ", "Seikuol (registered trademark) Z", "Seikuol (registered trademark) 100", "Seikuol (registered trademark) 200", "Seikuol (registered trademark) 1 ... Examples of such compounds include "Kayacure (registered trademark) BEE" (Seiko Chemical Co., Ltd.); "Kayacure (registered trademark) BP100" (Nippon Kayaku Co., Ltd.); "Kayacure (registered trademark) UVI-6992" (Dow Chemicals); "ADEKA Optomer SP-152", "ADEKA Optomer SP-170" (ADEKA Corporation); "TAZ-A", "TAZ-PP" (Nippon SiberHegner Co., Ltd.); and "TAZ-104" (Sanwa Chemical Co., Ltd.).

[0199] When the polymerizable liquid crystal composition contains a polymerization initiator, the content can be appropriately adjusted depending on the type and amount of the polymerizable liquid crystal contained in the composition, but is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal. If the content of the polymerization initiator is within this range, the polymerizable liquid crystal can be polymerized without disturbing the alignment.

[0200] When the polymerizable liquid crystal composition contains a photopolymerization initiator, the composition may further contain a photosensitizer.The photosensitizer includes xanthone, thioxanthone, and other xanthone compounds (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and other); anthracene, anthracene containing an alkoxy group (e.g., dibutoxyanthracene, and other anthracene compounds); phenothiazine and rubrene.

[0201] 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 appropriately adjusted depending on the type and amount of the photopolymerization initiator and the polymerizable liquid crystal, but is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal.

[0202] In order to allow the polymerization reaction of the polymerizable liquid crystal to 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.

[0203] Examples of the polymerization inhibitor include radical scavengers such as hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (for example, butylcatechol, etc.), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical; thiophenols; β-naphthylamines, and β-naphthols.

[0204] When the polymerizable liquid crystal composition contains a polymerization inhibitor, the content can be appropriately adjusted depending on the type and amount of the polymerizable liquid crystal, the amount of the photosensitizer used, etc., but is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal. If the content of the polymerization inhibitor is within this range, the polymerizable liquid crystal can be polymerized without disturbing the alignment.

[0205] [Method of manufacturing phase difference plate] When manufacturing a retardation plate, the first retardation layer, the second retardation layer, and the third retardation layer may be formed in any order. Also, the order in which Layer A and Layer B in the first retardation layer are formed may be any order.

[0206] A layer A may be formed on a substrate with or without an alignment film, a layer B may be formed on the layer A with or without an alignment film, and a second retardation layer may be formed on the layer B with or without an alignment film. On the substrate, layer B may be formed with or without an alignment film, layer A may be formed with or without an alignment film on layer B, and a second retardation layer may be formed with or without an alignment film on layer A. A second retardation layer may be formed on a substrate with or without an alignment film, layer A may be formed on the second retardation layer with or without an alignment film, and layer B may be formed on layer A with or without an alignment film. A second retardation layer is formed on a substrate with or without an alignment film, a layer B is formed on the second retardation layer with or without an alignment film, and a layer B is formed on the layer B with or without an alignment film. Layer A may be formed with or without an intervening layer. A layer A may be formed on one surface of the substrate with or without an alignment film, a layer B may be formed on the layer A with or without an alignment film, and a second retardation layer may be formed on the other surface of the substrate with or without an alignment film. A layer B may be formed on one surface of the substrate with or without an alignment film, a layer A may be formed on the layer B with or without an alignment film, and a second retardation layer may be formed on the other surface of the substrate with or without an alignment film.

[0207] 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, a protective layer may be provided between layer A and layer B. When layer A is formed on the second retardation layer with or without an alignment film, when layer A is formed on the second retardation layer with or without an alignment film, when the second retardation layer is formed on layer A with or without an alignment film, or when the second retardation layer is formed on layer B with or without an alignment film, a protective layer may be provided between the second retardation layer and layer A or layer B.

[0208] A first retardation layer may be formed on a substrate with or without an alignment film, a second retardation layer may be formed on the first retardation layer with or without an alignment film, and a third retardation layer may be formed on the second retardation layer with or without an alignment film. A third retardation layer may be formed on the substrate with or without an alignment film, a second retardation layer may be formed on the third retardation layer with or without an alignment film, and a first retardation layer may be formed on the second retardation layer with or without an alignment film. A first retardation layer may be formed on one surface of the substrate with or without an alignment film, a second retardation layer may be formed on the first retardation layer with or without an alignment film, and a third retardation layer may be formed on the other surface of the substrate with or without an alignment film. A second retardation layer may be formed on one surface of the substrate with or without an alignment film, a first retardation layer may be formed on the second retardation layer with or without an alignment film, and a third retardation layer may be formed on the other surface of the substrate with or without an alignment film. A third retardation layer is formed on one surface of the substrate with or without an alignment film therebetween. A second retardation layer may be formed on the retardation layer with or without an alignment film, and a first retardation layer may be formed on the other surface of the base material with or without an alignment film. A second retardation layer may be formed on one surface of the substrate with or without an alignment film, a third retardation layer may be formed on the second retardation layer with or without an alignment film, and a first retardation layer may be formed on the other surface of the substrate with or without an alignment film.

[0209] A first retardation layer may be formed on a substrate with or without an alignment film, and a second retardation layer may be formed on the first retardation layer with or without an alignment film. A second retardation layer may be formed on one surface of the substrate with or without an alignment film, and a first retardation layer may be formed on the second retardation layer with or without an alignment film. The second retardation layer may be formed on one surface of the substrate with or without an alignment film, and the first retardation layer may be formed on the other surface of the substrate with or without an alignment film.

[0210] When the second retardation layer is formed on the first retardation layer with or without an alignment film, or when the first retardation layer is formed on the second retardation layer with or without an alignment film, a protective layer may be provided between the first retardation layer and the second retardation layer. When the third retardation layer is formed on the second retardation layer with or without an alignment film, or when the second retardation layer is formed on the third retardation layer with or without an alignment film, a protective layer may be provided between the second retardation layer and the third retardation layer.

[0211] (protective layer) The protective layer is preferably formed from a protective layer-forming composition that contains a water-soluble polymer, such as an acrylic oligomer or polymer consisting of a multifunctional acrylate (methacrylate), urethane acrylate, polyester acrylate, epoxy acrylate, etc., polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylpyrrolidone, starches, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc., and a solvent.

[0212] The solvent contained in the composition for forming a protective layer may be the same as the solvent described above, and among them, at least one solvent selected from the group consisting of water, alcohol solvents, and ether solvents is preferred because it does not dissolve the layer forming the protective layer. Examples of the alcohol solvent include methanol, ethanol, butanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether. Examples of the ether solvent include ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate. Among them, ethanol, isopropyl alcohol, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate are preferred.

[0213] 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, and more preferably 1 μm or more and 5 μm or less. The thickness of the protective layer can usually be measured by an interference thickness meter, a laser microscope, or a stylus thickness meter.

[0214] Next, a method for continuously manufacturing a retardation plate will be described. A suitable method for continuously manufacturing the present optical film is a roll-to-roll method. Here, a method for manufacturing a retardation layer formed by polymerizing a polymerizable liquid crystal will be described. However, instead of the retardation layer formed by polymerizing a polymerizable liquid crystal, a retardation layer made of a stretched film may be used. In this case, "applying a polymerizable liquid crystal composition" in the following manufacturing steps may be read as "laminating a stretched film". In addition, the manufacturing method of the representative configuration is exemplified below, but the other configurations are manufactured by the following manufacturing method. It should be carried out in accordance with the above.

[0215] (1) preparing a roll having a substrate wound around a core; (2) continuously delivering the substrate from the roll; (3) continuously forming an alignment film on the substrate; (4) applying a polymerizable liquid crystal composition onto the alignment film to continuously form a first retardation layer; (5) continuously forming a protective layer on the first retardation layer obtained in (4); (6) A step of continuously forming an alignment film on the protective layer obtained in (5); (7) A step of applying a polymerizable liquid crystal composition onto the alignment film obtained in (6) to continuously form a second retardation layer; (8) A method in which the steps of winding the continuously obtained optical film around a second core to obtain a second roll are performed in sequence. Note that steps (3), (5) and (6) may be omitted as necessary. In this case, "on the alignment film" in step (4) is replaced with "on the substrate", "the protective layer obtained in (5)" in step (6) is replaced with "the first retardation layer", and "the alignment film obtained in (6)" in step (7) is replaced with "the first retardation layer" or "the protective layer obtained in (5)". In addition, in order to prevent wrinkles and curls during transport, a protective film may be attached when the film is transported in each step.

[0216] Also, (1a) preparing a roll having a substrate wound around a core; (2a) continuously delivering the substrate from the roll; (3a) continuously forming an alignment film on the substrate; (4a) applying a polymerizable liquid crystal composition onto the alignment film to continuously form a second retardation layer; (5a) a step of continuously forming a protective layer on the second retardation layer obtained in (4a); (6a) a step of continuously forming an alignment film on the protective layer obtained in (5a); (7a) applying a polymerizable liquid crystal composition onto the alignment film obtained in (6a) to continuously form a first retardation layer; (8a) A method of sequentially winding the continuously obtained optical film on a second core to obtain a second roll may also be mentioned. Note that steps (3a), (5a) and (6a) may be omitted as necessary. In this case, "on the alignment film" in step (4a) is replaced with "on the substrate", "the protective layer obtained in (5a)" in step (6a) is replaced with "the second retardation layer", and "the alignment film obtained in (6a)" in step (7a) is replaced with "the second retardation layer" or "the protective layer obtained in (5a)". In addition, in order to prevent wrinkles and curls during transport, a protective film may be attached when the film is transported in each step.

[0217] Also, (1b) preparing a roll having a substrate wound around a core; (2b) continuously delivering the substrate from the roll; (3b) continuously forming an alignment film on the substrate; (4b) applying a polymerizable liquid crystal composition onto the alignment film to continuously form a first retardation layer; (5b) a step of continuously forming an alignment layer on the substrate surface opposite to the first retardation layer obtained in (4b); (6b) applying a polymerizable liquid crystal composition onto the alignment film obtained in (5b) to continuously form a second retardation layer; (7b) a step of winding the continuously obtained optical film around a second core to obtain a second roll. Note that steps (3b) and (5b) may be omitted as necessary. In this case, "on the alignment film" in step (4b) refers to "on the substrate", and "on the alignment film obtained in (5b)" in step (6b) refers to "on the substrate obtained in (4b)". In order to prevent wrinkles and curls during transportation, a protective film may be attached to the film when it is transported in each process.

[0218] Also, (1c) preparing a roll having a transparent substrate wound around a core; (2c) continuously delivering the transparent substrate from the roll; (3c) continuously forming an alignment film on the transparent substrate; (4c) applying a polymerizable liquid crystal composition onto the alignment film to continuously form a second retardation layer; (5c) a step of continuously forming an alignment layer on the substrate surface opposite to the second retardation layer obtained in (4c); (6c) applying a polymerizable liquid crystal composition onto the alignment film obtained in (5c) to continuously form a first retardation layer; (7c) A process of winding the continuously obtained optical film on a second core to obtain a second roll. Steps (3c) and (5c) may be omitted as necessary. In this case, "on the alignment film" in step (4c) should be read as "on the substrate", and "on the alignment film obtained in (5c)" in step (6c) should be read as "the substrate surface opposite to the second retardation layer obtained in (4c)". In addition, in order to prevent wrinkles and curls during transportation, a protective film may be attached to the film during transportation in each step.

[0219] Also, (1d) preparing a roll having a substrate wound around a core; (2d) continuously delivering the substrate from the roll; (3d) continuously forming an alignment film on the substrate; (4d) applying a polymerizable liquid crystal composition onto the alignment film to continuously form a layer A; (5d) continuously forming a protective layer on the layer A obtained in (4d); (6d) a step of continuously forming an alignment film on the protective layer obtained in (5d); (7d) a step of applying a polymerizable liquid crystal composition onto the alignment film obtained in (6d) to continuously form a layer B; (8d) a step of continuously forming a protective layer on the layer B obtained in (7d); (9d) a step of continuously forming an alignment film on the protective layer obtained in (8d); (10d) a step of applying a polymerizable liquid crystal composition onto the alignment film obtained in (9d) to continuously form a second retardation layer; (11d) A method in which the steps of winding the continuously obtained optical film around a second core to obtain a second roll are performed in sequence. Note that steps (3d), (5d), (6d), (8d), and (9d) may be omitted as necessary. In this case, "on the alignment film" in step (4d) is replaced with "on the substrate", "the protective layer obtained in (5d)" in step (6d) is replaced with "the layer A", "the alignment film obtained in (6d)" in step (7d) is replaced with "the layer A" or "the protective layer obtained in (5d)", "the protective layer obtained in (8d)" in step (9d) is replaced with "the layer B", and "the alignment film obtained in (9d)" in step (10d) is replaced with "the layer B" or "the protective layer obtained in (9d)". In addition, in order to prevent wrinkles and curls during transportation, a protective film may be attached when the film is transported in each step.

[0220] Also, (1e) preparing a roll having a substrate wound on a core; (2e) continuously delivering the substrate from the roll; (3e) continuously forming an alignment film on the substrate; (4e) applying a polymerizable liquid crystal composition onto the alignment film to continuously form a first retardation layer; (5e) a step of continuously forming a protective layer on the first retardation layer obtained in (4e); (6e) a step of continuously forming an alignment film on the protective layer obtained in (5e); (7e) a step of applying a polymerizable liquid crystal composition onto the alignment film obtained in (6e) to continuously form a second retardation layer; (8e) a step of continuously forming an alignment layer on the substrate surface opposite to the first retardation layer obtained in (4e); (9e) a step of applying a polymerizable liquid crystal composition onto the alignment film obtained in (8e) to continuously form a third retardation layer; (10e) A method in which the optical film obtained continuously is wound around a second core to obtain a second roll is also included. Steps (3e), (5e) and (8e) may be omitted as necessary. In this case, "on the alignment film" in step (4e) is replaced with "on the substrate", "the protective layer obtained in (5e)" in step (6e) is replaced with "the first retardation layer obtained in (4e)", and "on the alignment film obtained in (8e)" in step (9e) is replaced with "the substrate surface opposite to the first retardation layer obtained in (4e)". In addition, in order to prevent wrinkles and curls during transportation, a protective film may be attached when the film is transported in each step. In addition, in order to prevent wrinkles and curls during transportation, a protective film may be attached when the film is transported in each step.

[0221] 2 is a schematic cross-sectional view showing a specific example of the retardation plate 30. FIG. 2(a) is a retardation plate 30 in which a first retardation layer 31 and a second retardation layer 32 are laminated. FIG. 2(b) is 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. 2(c) is 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. 2(d) is 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.

[0222] By removing the substrate 33 from the retardation plate 30, a retardation plate 30 without a substrate (FIG. 2(a)) can be obtained.

[0223] The retardation plate 30 can also be manufactured by bonding a base material 33 having a first retardation layer 31 and a base material 33' having a second retardation layer 32 together. Specific examples are shown in Fig. 2(e), Fig. 2(f) and Fig. 2(g). For bonding, a bonding layer (hereinafter, a bonding layer used for bonding between layers in the retardation plate 30 is also referred to as a "third bonding layer") can be used.

[0224] FIG. 3 is a schematic cross-sectional view showing a specific example of a retardation plate 30 in which the first retardation layer is composed of layers A and B, or in which a third retardation layer is included. FIG. 3(a) shows a retardation plate 30 in which a layer A34, a layer B35, and a second retardation layer 32 are laminated in this order. FIG. 3(b) shows a retardation plate 30 in which a layer B35, a layer A34, and a second retardation layer 32 are laminated in this order. FIG. 3(c) 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. 3(d) 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. 3(e) 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. 3(f) shows a retardation plate 30 in which a substrate 33, a third retardation layer 38, a second retardation layer 32, and a first retardation layer 31 are laminated in this order. Fig. 3(g) shows a retardation plate 30 in which a substrate 33, a second retardation layer 32, a layer B35, and a layer A34 are laminated in this order. Fig. 3(h) shows a retardation plate 30 in which a substrate 33, a second retardation layer 32, a layer A34, and a layer B35 are laminated in this order. A retardation plate 30 without a substrate 33 (Figs. 3(a) and (b)) can also be obtained by peeling off the substrate 33 from a retardation plate 30 having the substrate 33.

[0225] In the case of a configuration including the first retardation layer 31, the layer A34, and the layer B35, or in the case of having the third retardation layer 33, each layer may be laminated on both sides of the substrate 33. As a specific example, for example, FIG. 3(i) is a retardation plate 30 in which the second retardation layer 32, the substrate 33, the layer A34, and the layer B35 are laminated in this order. FIG. 3(j) is a retardation plate 30 in which the second retardation layer 32, the substrate 33, the layer B35, and the layer A34 are laminated in this order. FIG. 3(k) is a retardation plate 30 in which the first retardation layer 31, the substrate 33, the third retardation layer 38, and the second retardation layer 32 are laminated in this order. FIG. 3(l) is a retardation plate 30 in which the first retardation layer 31, the substrate 33, the second retardation layer 32, and the 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 substrate 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 substrate 33, a second retardation layer 32, and a first retardation layer 31 are laminated in this order. The second retardation layer 32, the layer A34, and the layer B35 may be formed by direct coating on each layer, or each layer may be laminated by lamination after production, or each layer may be laminated by sequential transfer.

[0226] The retardation plate 30 may have another layer interposed between the first retardation layer 31 and the second retardation layer 32, or may have no other layer interposed between the first retardation layer 31 and the second retardation layer 32. Examples of the other layer interposed include the base material 33, the above-mentioned protective layer, the above-mentioned alignment film, and the third bonding layer. In the retardation plate 30 having only an alignment film as another layer interposed between the first retardation layer 31 and the second retardation layer 32 or having no other layer interposed between the first retardation layer 31 and the second retardation layer 32, the peel strength between the first retardation layer 31 and the second retardation layer 32 is likely to be 1.0 N / 25 mm or less. In this specification, the layer interposed between the first retardation layer 31 and the second retardation layer 32 means a layer interposed between the outermost surface of the first retardation layer 31 on the second retardation layer 32 side and the outermost surface of the second retardation layer 32 on the first retardation layer 31 side. Therefore, when the first retardation layer 31 is composed of a layer A and a layer B, a layer interposed between the layer A and the layer B is not considered to be a layer interposed between the first retardation layer 31 and the second retardation layer 32.

[0227] [Second lamination layer, third lamination layer] The second bonding layer is a bonding layer used to bond layers together in the linear polarizer 10, and the third bonding layer is a bonding layer used to bond layers together in the retarder 30. Hereinafter, the term "bonding layer" includes both the second bonding layer and the third bonding layer.

[0228] The attachment layer is a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition, or an adhesive layer formed using an adhesive composition. The second attachment layer and the third attachment layer are preferably adhesive layers from the viewpoint of suppressing thermal shrinkage behavior when heat is applied.

[0229] When the lamination 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. The pressure-sensitive adhesive composition may contain, for example, a rubber-based polymer, a (meth)acrylic polymer, a urethane-based polymer, a polyester-based polymer, a silicone-based polymer, a polyvinyl ether-based polymer, a polyvinyl alcohol-based polymer, a polyolefin-based polymer, a vinyl alkyl ether-based polymer, a polyvinyl pyrrolidone-based polymer, a poly(meth)acrylamide-based polymer, a cellulose-based polymer, or the like, as a main component. In this specification, the main component refers to a component that contains 50% by mass or more of the total solid content of the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may be of an active energy ray curing type or a heat curing type. The pressure-sensitive adhesive composition is preferably a rubber-based polymer. The above-mentioned "(meth)acrylic" means "at least one of acrylic and methacrylic". The same applies to the notation "(meth)acrylate" and the like.

[0230] Rubber polymers include natural rubber; polyisobutylene rubber (PIB), isoprene rubber (IR), isobutylene-isoprene rubber (IIR), normal butylene-isobutylene Examples of the rubber include synthetic rubbers such as styrene copolymer rubber, butadiene rubber (BR), 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), and styrene-ethylene-propylene block copolymer rubber (SEP). As the rubber-based polymer, polyisobutylene rubber (PIB), isobutylene-isoprene rubber (IIR), and normal butylene-isobutylene copolymer rubber are preferred, and polyisobutylene rubber (PIB) is more preferred.

[0231] As the (meth)acrylic polymer, a polymer or copolymer containing one or more monomers of (meth)acrylic acid esters such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferably used. It is preferable to copolymerize a polar monomer into the base polymer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0232] The active energy ray curable adhesive composition is an adhesive composition that has a property of being cured by irradiation with active energy rays such as ultraviolet rays or electron beams, has adhesiveness even before irradiation with active energy rays, can be adhered to an adherend such as a film, and 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 type. The active energy ray curable adhesive composition further contains an active energy ray polymerizable compound in addition to a base polymer and a crosslinking agent. If necessary, a photopolymerization initiator, a photosensitizer, etc. may also be contained.

[0233] The adhesive composition may contain, in addition to the polymer, additives such as a solvent, a tackifier, a softener, a filler (metal powder or other inorganic powder, etc.), an antioxidant, an ultraviolet absorber, a dye, a pigment, a colorant, an antifoaming agent, a corrosion inhibitor, a photopolymerization initiator, etc. When an active energy ray-curable adhesive composition is used, a cured product having a desired degree of cure can be obtained by irradiating the formed adhesive layer with active energy rays.

[0234] The pressure-sensitive adhesive layer can be formed by applying a solution of the pressure-sensitive adhesive composition diluted in an organic solvent onto a substrate and drying the applied solution.

[0235] When the lamination 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 moisture permeability. Examples of the adhesive composition include water-based adhesives, active energy ray curing adhesives, natural rubber adhesives, α-olefin adhesives, urethane resin adhesives, ethylene-vinyl acetate resin emulsion adhesives, ethylene-vinyl acetate resin hot melt adhesives, epoxy resin adhesives, vinyl chloride resin solvent-based adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, silicone adhesives, styrene-butadiene rubber solvent-based adhesives, 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 adhesives, polyolefin resin hot melt adhesives, polyvinyl acetate resin solvent-based adhesives, polystyrene resin solvent-based adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone resin adhesives, polyvinyl butyral adhesives, etc. Examples of adhesives include adhesives, polybenzimidazole adhesives, polymethacrylate resin solvent-based adhesives, melamine resin-based adhesives, urea resin-based adhesives, resorcinol-based adhesives, etc. Such adhesives can be used alone or in combination of two or more.

[0236] Examples of the aqueous adhesive include a polyvinyl alcohol-based resin aqueous solution and an aqueous two-liquid urethane-based emulsion adhesive. Examples of the active energy ray curable adhesive include an adhesive that is cured by irradiation with active energy rays such as ultraviolet rays, and include, for example, those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, and 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, as well as oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing a substance that generates active species such as neutral radicals, anion radicals, and cation radicals when irradiated with active energy rays such as ultraviolet rays.

[0237] The thickness of the pasting layer is not particularly limited, but when the pasting layer is a pressure-sensitive adhesive layer, it is preferably 5 μm or more, may be 15 μm or more, may be 20 μm or more, may be 25 μm or more, and is usually 200 μm or less, may be 100 μm or less, or may be 50 μm or less. When the pasting layer is an adhesive layer, the thickness of the pasting layer is preferably 0.01 μm or more, may be 0.05 μm or more, may be 0.5 μm or more, and is preferably 5 μm or less, may be 3 μm or less, or may be 2 μm or less.

[0238] [Method of manufacturing 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 has only one slow axis, it is preferable to set the transmission axis of the linear polarizing plate to be substantially 45° with respect to the slow axis (optical axis) of the first retardation layer of the retardation plate. Substantially 45° is usually in the range of 45±5°. In such an angle arrangement, the polarizing plate can function as a circular polarizing plate.

[0239] Examples of a method for bonding a retardation plate having no substrate to a linear polarizing plate include a method of bonding a retardation plate from which the substrate has been removed to a linear polarizing plate using a first bonding layer, and a method of bonding a retardation plate to a linear polarizing plate using a first bonding layer and then removing the substrate. In this case, the first bonding layer may be directly formed by applying a pressure-sensitive adhesive to the retardation layer side of the retardation plate, or may be directly formed by applying a pressure-sensitive adhesive to the linear polarizing plate side, or a first bonding layer formed on another substrate in advance may be interposed between the linear polarizing plate and the retardation plate. If an alignment film is present between the substrate and the retardation layer, the alignment film may be removed together with the substrate.

[0240] A substrate having a functional group on its surface that forms a chemical bond with a retardation layer or an alignment film, etc., tends to be difficult to remove due to the formation of a chemical bond with the retardation layer or the alignment film, etc. Therefore, when removing the substrate by peeling, a substrate having a small number of functional groups on its surface is preferred, and a substrate that has not been subjected to a surface treatment that forms a functional group on its surface is preferred.

[0241] In addition, since an alignment film having a functional group that forms a chemical bond with a substrate tends to have a large adhesive force between the substrate and the alignment film, when the substrate is peeled off and removed, an alignment film having a small number of functional groups that form a chemical bond with the substrate is preferred. In addition, it is preferable that a reagent that crosslinks the substrate and the alignment film is not included, and further, it is preferable that a solution of the alignment polymer composition and the photoalignment film forming composition does not include a component such as a solvent that dissolves the substrate.

[0242] In addition, the alignment film having a functional group that forms a chemical bond with the retardation layer tends to have a large adhesive force between the retardation layer and the alignment film. Therefore, when removing the alignment film together with the substrate, an alignment film having a small number of functional groups that form a chemical bond with the retardation layer is preferable. In addition, 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.

[0243] In addition, the retardation layer having a functional group that forms a chemical bond with the alignment film tends to have a large adhesion between the alignment film and the retardation layer. Therefore, when removing the substrate or removing the alignment film together with the substrate, a retardation layer having a small number of functional groups that form a chemical bond with the substrate or alignment film is preferred. In addition, the polymerizable liquid crystal composition preferably does not contain a reagent that crosslinks the substrate or alignment film with the retardation layer.

[0244] For example, a first bonding layer 21 is attached to the surface of the first retardation layer 31 of a retardation plate 30 in which a substrate, a second retardation layer 32, and a first retardation layer 31 are laminated in this order, a linear polarizing plate 10 is attached thereto, and then the substrate of the retardation plate 30 is removed, thereby manufacturing a polarizing plate having the configuration shown in FIG. 1 in which the linear polarizing plate 10, the first bonding layer 21, the first retardation layer 31, and the second retardation layer 32 are laminated in this order. In addition, a first bonding layer is attached to the surface of the second retardation layer of a retardation plate in which a substrate, a first retardation layer, and a second retardation layer are laminated in this order, a linear polarizing plate is attached thereto, and then the substrate of the retardation plate is removed, thereby manufacturing a polarizing plate in which a linear polarizing plate, a second retardation layer, and a first retardation layer are laminated in this order. From the viewpoint of thinning, it is preferable to peel off the substrate.

[0245] When the first retardation layer includes the layer A and the layer B, or when the first retardation layer includes the third retardation layer, there is a restriction on the lamination direction of each layer. Specifically, when layer A having a phase difference of λ / 4 and layer B having a phase difference of λ / 2 are laminated, layer B is first formed so that the slow axis of layer B is at 75° with respect to the absorption axis of the linear polarizer, and then layer A is formed so that the slow axis of layer A is at 15°. In addition, when the first retardation layer has a phase difference of λ / 4 and the third retardation layer has a phase difference of λ / 2, the third retardation layer is first formed so that the slow axis of the third retardation layer is 75° with respect to the absorption axis of the linear polarizer, and then the first retardation layer is formed so that the slow axis of the first retardation layer is 15°. There is no limitation on the position of the second retardation layer, but it is necessary that the linear polarizer, layer B and layer A are laminated in this order, or the linear polarizer, the third retardation layer and the first retardation layer are laminated in this order. By laminating in this way, the obtained polarizer can function as a wideband circular polarizer. Here, there is no limitation on the axial angle forming Layer A and Layer B. For example, as described in JP 2004-126538 A, it is known that the function of a broadband λ / 4 plate can be exhibited even if the slow axis angles of Layer A and Layer B are 30° and −30°, or 45° and −45° with respect to the absorption axis of the polarizing plate. Therefore, it is possible to laminate the layers in a desired manner.

[0246] [Image display device] Fig. 4 is a schematic cross-sectional view showing an example of an image display device according to the present embodiment. As shown in Fig. 4, the image display device 2 has, from the front side, the polarizing plate 1 shown in Fig. 1 and an image display panel 40, in this order. In the image display device 2, the polarizing plate 1 is oriented so that the linear polarizing plate 10 side is closer to the front than the retardation plate 30.

[0247] When the polarizing plate 1 is a circular polarizing plate, in the image display device 2, the incident light from the outside is divided into light reflected by the polarizing plate 1 and light transmitted through the polarizing plate 1. The polarizing plate 1 may have an anti-reflection layer on the foremost surface, and by providing an anti-reflection layer, the light reflected on the surface of the polarizing plate 1 (hereinafter also referred to as "external reflected light") can be reduced. 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 "internal reflected light"), It is absorbed by the polarizing plate 1. Although it is desirable that the internally reflected light is entirely absorbed by the polarizing plate 1, a part of it is emitted from the front surface (hereinafter, such light is also referred to as "emitted internally reflected light").

[0248] The polarizing plate 1 may be provided with an adhesive layer on the rear surface thereof, which can be used to attach the polarizing plate 1 to the image display panel 40, and may be configured as a polarizing plate with an adhesive layer.

[0249] <Other Layers That the Image Display Device May Have> The image display device 2 may have layers other than the layers described above. Examples of other layers that the image display device 2 may have are given below.

[0250] (Touch sensor panel) The touch sensor panel is a device (sensor) that detects (senses) a finger or the like that touches the screen of an image display device, and is used as an input means that detects the position of the finger on the screen and inputs the detected position to the image display device. The touch sensor panel may be disposed between the polarizing plate 1 and the image display panel 40, or may be disposed on the front side of the polarizing plate 1. As the touch sensor panel, the detection method is not limited as long as it is a sensor that can detect the touched position, and examples of the touch sensor panel include resistive film type, electrostatic capacitance coupling type, optical sensor type, ultrasonic type, electromagnetic induction coupling type, surface acoustic wave type, infrared type, and the like. Resistive film type and electrostatic capacitance coupling type touch sensor panels are preferably used because of their low cost.

[0251] An example of a resistive touch sensor panel is composed of a pair of substrates arranged opposite each other, an insulating spacer sandwiched between the pair of substrates, a transparent conductive film provided as a resistive film on the inner front surface of each substrate, and a touch position detection circuit. In an image display device equipped with a resistive touch sensor panel, when the surface of the front panel is touched, the opposing resistive film is short-circuited and a current flows through the resistive film. The touch position detection circuit detects the voltage change at this time and detects the touched position.

[0252] An example of a capacitive touch sensor panel is composed of 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 provided with a capacitive touch sensor panel, when the surface of the front panel is touched, the transparent electrode is grounded via the electrostatic capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode and detects the touched position. A capacitive touch sensor panel is divided into an active area and an inactive area located on the outer periphery of the active area. The active area is an area corresponding to an area (display section) where a screen is displayed on a display panel and is an area where a user's touch is sensed, and the inactive area is an area corresponding to an area (non-display section) where a screen is not displayed on a display device.

[0253] The thickness of the touch sensor panel may be, for example, 5 μm or more and 2,000 μm or less, or may be 5 μm or more and 100 μm or less.

[0254] <Flexible image display device> The image display device may be a flexible image display device. The flexible image display device is a foldable image display device. The flexible image display device includes an optical fingerprint authentication system incorporated therein, a foldable image display element, and the 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 disposed on the viewing side of the organic EL display panel and is configured to be foldable. The polarizing plate for a flexible image display device may further include a front plate and a touch sensor panel. It is preferable that the front plate, the polarizing plate of the present invention, and the touch sensor panel are laminated in this order from the viewing side, or the front plate, the touch sensor panel, and the polarizing plate of the present invention are laminated in this order from the viewing side. Since the pattern of the touch sensor panel becomes less visible, resulting in improved visibility of the displayed image, it is more preferable to have a configuration in which the polarizing plate of the present invention is provided on the viewing side of the touch sensor panel, that is, a front plate, the polarizing plate of the present invention, and the touch sensor panel are provided in this order. Each member can be laminated using an adhesive, a pressure-sensitive adhesive, etc. Also, a light-shielding pattern formed on at least one surface of any one of the layers of the front plate, the polarizing plate, and the touch sensor panel can be provided.

[0255] In a flexible image display device including, from the viewing side, a front plate, the polarizing plate of the present invention, and a foldable image display panel, the front plate and the polarizing plate of the present invention constitute a front plate-attached polarizing plate including a polarizing plate and a front plate. In this front plate-attached polarizing plate, the front plate is usually disposed on the viewing side of the polarizing plate, and is laminated with the polarizing plate, for example, by a pressure-sensitive adhesive or adhesive. In a flexible image display device comprising, from the viewing side, a touch sensor panel, the polarizing plate of the present invention, and a foldable image display panel, the touch sensor panel and the polarizing plate of the present invention constitute a polarizing plate with a touch sensor panel comprising a polarizing plate and a touch sensor panel. Also, in a flexible image display device comprising, from the viewing side, the polarizing plate of the present invention, a touch sensor panel, and a foldable image display element, the touch sensor panel and the polarizing plate of the present invention constitute a polarizing plate with a touch sensor panel comprising a polarizing plate and a touch sensor panel. In this polarizing plate with a touch sensor panel, the touch sensor panel may be disposed on the rear side of the polarizing plate (opposite the viewing side), or may be disposed on the viewing side of the polarizing plate. The touch sensor panel and the polarizing plate are laminated together, for example, with an adhesive or a bonding agent.

[0256] 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 the viewing side of the polarizing plate. A polarizing plate with a front plate includes the polarizing plate of the present invention and a front plate disposed on the viewing side of the polarizing plate.

[0257] (Front plate) Examples of the front plate include glass and resin film having a hard coat layer on at least one side. As the glass, for example, highly transparent glass or reinforced glass can be used. In particular, when a thin transparent surface material is used, chemically reinforced glass is preferable. The thickness of the glass can be, for example, 100 μm to 5 mm.

[0258] A front panel including a hard coat layer on at least one side of a resin film can have flexible properties, unlike conventional glass, and the thickness of the hard coat layer is not particularly limited and may be, for example, 5 μm to 100 μm.

[0259] The resin film may be a film formed of a polymer such as norbornene, a cycloolefin derivative having a unit of a monomer containing a cycloolefin such as a polycyclic norbornene monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose), 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, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, or epoxy. Each of 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, for example, a uniaxially stretched film. The resin film may be a polyamideimide film, a polyimide film, a uniaxially stretched polyester film, or a biaxially stretched polyester film, which are preferable because of their excellent transparency and heat resistance, a cycloolefin derivative film or a polymethyl methacrylate film, which are preferable because of their excellent transparency and heat resistance and their ability to accommodate large-sized films, and a triacetyl cellulose film or an isobutyl ester cellulose film, which are preferable because of their relative ease of availability as transparent and optically non-anisotropic resin films. The thickness of the resin film is usually 5 to 200 μm, and preferably 20 to 100 μm.

[0260] (Light blocking 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, it is possible to hide each wiring constituting the display device so that it is not visible to the user. The color and material of the light-shielding pattern are not particularly limited, and the light-shielding pattern can be formed of a resin material having various colors such as black, white, gold, etc. In one embodiment, the thickness of the light-shielding pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. In addition, a shape can be given to the light-shielding pattern in order to suppress the inclusion of air bubbles and the visibility of the boundary due to the step between the light-shielding pattern and the display part. EXAMPLES

[0261] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples and comparative examples, the blending amounts represented by "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[0262] (1) Preparation of active energy ray curable adhesive The components listed below were blended and mixed, and then degassed to prepare active energy ray-curable adhesives A, B, and C, respectively.

[0263] <Active energy ray curing adhesive A> 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation): 70 parts by mass Neopentyl glycol diglycidyl ether (product name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts by mass 2-Ethylhexyl glycidyl ether (product name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts by mass Cationic polymerization initiator (product name: CPI-100_50% solution, manufactured by San-Apro Co., Ltd.): 4.5 parts by weight (actual solid content 2.25 parts by weight) 1,4-diethoxynaphthalene: 2 parts by weight

[0264] <Active energy ray curing adhesive B> Neopentyl glycol diglycidyl ether (product name: EX-211L, manufactured by Nagase ChemteX Corporation): 30 parts by mass 3-Ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (product name: OXT-221, manufactured by Toagosei Co., Ltd.): 13 parts by mass Bisphenol A epoxy resin (product name: EP-4100E, ADEKA Corporation, viscosity 13 Pa·s (temperature 25°C)): 45 parts by weight ·Aromatic-containing oxetane compound (product name: TCM-104, manufactured by TRONLY): 12 parts by mass Cationic polymerization initiator (product name: CPI-100_50% solution, manufactured by San-Apro Co., Ltd.): 4.5 parts by weight (actual solid content 2.25 parts by weight) 1,4-diethoxynaphthalene: 1 part by weight

[0265] <Active energy ray curing adhesive C> N,N-Dimethylacrylamide (KJ Chemicals Co., Ltd.): 7 parts by weight 4-Hydroxybutyl acrylate (Osaka Organic Industry Co., Ltd.): 55 parts by weight 1,4-Cyclohexanedimethanol monoacrylate (Nippon Kasei Co., Ltd.): 28 parts by weight - UV-curable urethane acrylate resin (product name: UV-3000B, Nippon Synthetic Chemical Industry Co., Ltd.): 10 parts by weight 2-Hydroxy-2-methyl-1-phenylpropan-1-one (product name: DAROCUR 1173, BASF Japan Ltd.): 3 parts by weight

[0266] <Measurement of tensile storage modulus of adhesive layer> The adhesive compositions (active energy ray curable adhesives A to C) were applied to one side of a cyclic polyolefin resin film having a thickness of 50 μm using a wire bar #18 of a bar coater manufactured by Daiichi Rika Co., Ltd., so as to have a thickness of 25 μm. Next, the ... 2 (Measurement device: Measurement value using UV Power Puck II manufactured by FusionUV Systems) was irradiated with ultraviolet light in the atmosphere at a temperature of 25°C and a relative humidity of 60%. The adhesive was then cured by leaving it in the dark in the atmosphere at a temperature of 25°C and a relative humidity of 60% for 48 hours. This was cut into pieces of 5 mm x 30 mm, and the cyclic polyolefin resin film was peeled off to obtain a cured film of the adhesive.

[0267] The cured film of the adhesive obtained as described above was gripped with a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement & Control Co., Ltd. with a gripping distance of 2 cm so that the long side was in the tensile direction, and the tensile and contraction frequency was set to 10 Hz and the measurement temperature was set to 23°C, and the tensile storage modulus at a temperature of 23°C was determined. The tensile storage modulus of adhesive layers A to C was, respectively, 2.1 x 10 3 MPa, adhesive layer B: 2.4×10 3 MPa, adhesive layer C: 0.56 MPa.

[0268] (2) Preparation of adhesive layer The following acrylic pressure-sensitive adhesive layers (1) to (3), both sides of which were bonded to release films, were prepared.

[0269] <Adhesive layer (1)> (2-1-1) Preparation of acrylic resin solution 1 A mixed solution of 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 parts of 2-hydroxyethyl acrylate, and 0.5 parts of acrylic acid was charged into a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer, and the air in the vessel was replaced with nitrogen gas to remove oxygen while raising the internal temperature to 55°C. Then, the entire amount of a solution in which 0.12 parts of azobisisobutyronitrile (polymerization initiator) was dissolved in 10 parts of ethyl acetate was added. After adding the polymerization initiator, the temperature was maintained for 1 hour, and then ethyl acetate was added at a rate of 17.3°C while maintaining the internal temperature at 54-56°C. The (meth)acrylic resin was continuously added to the reaction vessel at a rate of 1 part / hr, and when the concentration of the (meth)acrylic resin reached 35% by mass, the addition of ethyl acetate was stopped, and the mixture was kept at this temperature for a further 6 hours from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the (meth)acrylic resin concentration to 20% by mass, to prepare acrylic resin solution 1. The resulting acrylic resin had a weight average molecular weight Mw of 1.7 million and a molecular weight distribution Mw / Mn of 3.9. Note that Mw and Mn were measured using a GPC apparatus with a column of "TSKgel GMH" manufactured by Tosoh Corporation. HR Two "-H(S)" columns were connected in series, and tetrahydrofuran was used as the eluent. The sample concentration was 2 mg / mL, the sample amount was 100 μL, the temperature was 40°C, and the flow rate was 1 mL / min. The measurement was based on polystyrene standards.

[0270] (2-1-2) Preparation of Pressure Sensitive Adhesive Composition 1 To 80 parts by solid content of the acrylic resin solution 1 obtained in (2-1-1), 20 parts by solid content of a bifunctional acrylate (obtained from Shin-Nakamura Chemical Co., Ltd.; product number "A-DOG"), 2.5 parts by active ingredient basis of a crosslinking agent (manufactured by Tosoh Corporation: trade name "Coronate L" (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75% by mass)), 1.5 parts of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name "Irgacure 500"), and 0.3 part of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name "KBM-403") were added, and ethyl acetate was further added so that the solid content concentration became 13% to obtain an adhesive composition 1. A-DOG is a diacrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane and has the structure of the following formula.

[0271] [Chemical formula]

[0272] (2-1-3) Preparation of the adhesive layer (1) The adhesive composition 1 prepared in the above (2-1-2) was applied to the release-treated surface of a separate film made of a polyethylene terephthalate film subjected to release treatment ["PLZ-383030" obtained from Lintec Corporation] using an applicator so that the thickness after drying was 5 μm, and dried at 100°C for 1 minute to prepare an adhesive layer (adhesive sheet). Next, the surface of the obtained adhesive layer on the side opposite to the separator film was bonded to the release-treated surface of a separate film made of a polyethylene terephthalate film subjected to release treatment ["PLR-381031" obtained from Lintec Corporation]. Subsequently, ultraviolet rays were irradiated under the following conditions to prepare the adhesive layer (1). The shear storage modulus of the obtained adhesive layer at 23°C was 0.13 MPa. [UV irradiation conditions] ·Using a Fusion UV lamp system (manufactured by Fusion UV Systems) H bulb ·Integrated light amount of UVA in the UV wavelength region: 250 mJ / cm 2(Measurement equipment: Measurements taken using FusionUV's UV Power Puck II)

[0273] <Adhesive layer (2)> (2-2-1) Preparation of acrylic resin solution 2 A mixed solution of 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 was charged into a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer, and the air in the vessel was replaced with nitrogen gas to remove oxygen while raising the internal temperature to 55°C. Then, the entire amount of a solution in which 0.15 parts of azobisisobutyronitrile (polymerization initiator) was dissolved in 10 parts of ethyl acetate was added. After adding the polymerization initiator, the temperature was maintained for 1 hour, and then ethyl acetate was added at a rate of 17.3 parts / hr to the reaction volume while maintaining the internal temperature at 54-56°C. The ethyl acetate was continuously added to the vessel, and when the concentration of the (meth)acrylic resin reached 35% by mass, the addition of ethyl acetate was stopped, and the temperature was maintained for another 6 hours from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, to prepare acrylic resin solution 2. The resulting acrylic resin had a weight average molecular weight Mw of 1.6 million and a molecular weight distribution Mw / Mn of 4.5. Note that Mw and Mn are the values ​​calculated using the GP The column in the C device was TSKgel GMH HR -H(S)" 2 The columns were connected in series, and measurements were performed using tetrahydrofuran as the eluent at a sample concentration of 2 mg / mL, a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL / min, using standard polystyrene equivalents.

[0274] (2-2-2) Preparation of Pressure Sensitive Adhesive Composition 2 To 100 parts of the solid content of the acrylic resin solution 2 obtained in (2-2-1), 0.15 parts of a crosslinker (manufactured by Tosoh Corporation: product name "Coronate L" (a solution of a trimethylolpropane adduct of tolylene diisocyanate in ethyl acetate (solid content concentration 75% by mass)) was added on an active ingredient basis, and 0.2 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM-403") was added, and ethyl acetate was further added so that the solid content concentration became 13%, thereby obtaining a pressure-sensitive adhesive composition 2.

[0275] (2-2-3) Preparation of adhesive layer (2) The adhesive composition 2 prepared in (2-2-2) above was applied to the release-treated surface of a release-treated polyethylene terephthalate film ("PLR-382190" obtained from Lintec Corporation) using an applicator so that the thickness after drying was 25 μm, and the adhesive layer (adhesive sheet) was prepared by drying at 100 ° C for 1 minute. Next, the surface of the obtained adhesive layer opposite the separator film was laminated to the release-treated surface of a release-treated polyethylene terephthalate film ("PET-251130" obtained from Lintec Corporation) to prepare an adhesive layer (2). The shear storage modulus of the obtained adhesive layer at a temperature of 23 ° C was 0.026 MPa.

[0276] <Adhesive layer (3)> (2-3-1) Preparation of acrylic resin solution 3 A mixed solution of 91 parts of ethyl acetate, 43 parts of 2-ethylhexyl acrylate, 55 parts of butyl acrylate, and 2.0 parts of 2-hydroxyethyl acrylate was charged into a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, and the air in the apparatus was replaced with nitrogen gas to make it oxygen-free, while raising the internal temperature to 55°C. Then, a solution of 0.14 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 for 1 hour, and then ethyl acetate was continuously added to the reaction vessel while maintaining the internal temperature at 54 to 56°C. When the concentration of the (meth)acrylic resin reached 35% by mass, the addition of ethyl acetate was stopped, and the temperature was maintained for 10 hours from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, and acrylic resin solution 3 was prepared. The obtained acrylic resin had a weight average molecular weight Mw The molecular weight distribution (Mw / Mn) was 4.8. The column used in the device was a TSKgel GMH column manufactured by Tosoh Corporation. HR Two "-H(S)" were connected in series, and tetrahydrofuran was used as the eluent. The sample concentration was 2 mg / mL, the sample amount was 100 μL, the temperature was 40°C, and the flow rate was 1 mL / min. The measurements were performed in terms of standard polystyrene.

[0277] (2-3-2) Preparation of Pressure Sensitive Adhesive Composition 3 To 100 parts of the solid content of the acrylic resin solution 3 obtained in (2-3-1), 0.3 parts of a crosslinking agent (manufactured by Tosoh Corporation: product name "Coronate L" (a solution of a trimethylolpropane adduct of tolylene diisocyanate in ethyl acetate (solid content concentration 75% by mass)) was added on an active ingredient basis, and 0.25 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM-403") was added, and ethyl acetate was further added to adjust the solid content concentration to 15%, thereby obtaining a pressure-sensitive adhesive composition 3.

[0278] (2-3-3) Preparation of adhesive layer (3) The adhesive composition 3 prepared in (2-3-2) above was applied to a polyethylene terephthalate sheet that had been subjected to a release treatment. The adhesive was applied to the release-treated surface of a separate film made of a polyethylene terephthalate film ["POGW-502190" obtained from Lintec Corporation] using an applicator so that the thickness after drying would be 25 μm, and dried at 100 ° C for 1 minute to prepare an adhesive layer (adhesive sheet). The adhesive layer obtained was then bonded to the release-treated surface of a separate film made of a polyethylene terephthalate film ["PLR-381031" obtained from Lintec Corporation], the surface of which was released on the opposite side of the separator film, to prepare an adhesive layer (3). The shear storage modulus of the obtained adhesive layer at a temperature of 23 ° C was 0.01 MPa.

[0279] <Measurement of shear storage modulus of adhesive layer and conversion to tensile storage modulus> The shear storage modulus of the adhesive layer was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). The same adhesive layer as used in the examples and comparative examples was cut to a width of 30 mm x length of 30 mm, the release film was peeled off, and a plurality of sheets were laminated to a thickness of 200 μm and bonded to a measurement stage. After that, in a state where it was attached to a measurement chip (PP25, Anton Paar), measurements were performed in a temperature range of -20°C to 100°C under conditions of a frequency of 1.0 Hz, a deformation amount of 1%, a normal force of 1 N, and a temperature rise rate of 5°C / min. The shear storage modulus obtained here was converted by formula (10) to obtain the tensile storage modulus at a temperature of 23°C. E = G × 2 × (1 + ν) Equation (10) Here, E is the tensile storage modulus, G is the shear storage modulus, and ν is the Poisson's ratio. In this specification, the Poisson's ratio of the adhesive is assumed to be 0.5 (see formula (1.12) on page 15 of the book "Lecture on Rheology" (editor: The Society of Rheology of Japan, publisher: Mamoru Nishiguchi, publisher: Polymer Publishing Co., Ltd.).

[0280] (3) Preparation of polarizer A polyvinyl alcohol film having a thickness of 20 μm, a degree of polymerization of 2400, and a degree of saponification of 99% or more was uniaxially stretched to a stretching ratio of 4.5 times on a heated roll and, while maintaining the tension, was immersed for 60 seconds in a dye bath at 28° C. containing 0.05 parts by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water.

[0281] Next, the film was immersed for 110 seconds in a boric acid aqueous solution 1 at 64° C. containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water. Next, the film was immersed for 30 seconds in a boric acid aqueous solution 2 at 67° C. containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water. Thereafter, the film was washed with pure water at 10° C. and dried to obtain a polarizer. The polarizer had a thickness of 8 μm and a boron content of 4.3% by mass.

[0282] (4) Preparation of protective film The following protective films were prepared: Protective film: 13μm thick norbornene resin film (manufactured by Zeon Corporation, product name "ZEONOR").

[0283] (5) Preparation of linear polarizing plate The above protective film was laminated on one side of the polarizer prepared above using a roll laminator via a water-based adhesive. After lamination, a drying treatment was performed at 80°C for 3 minutes. A linear polarizing plate was obtained in which the protective film was laminated only on one side of the polarizer. The linear polarizing plate was a laminate of a polarizer, an adhesive layer, and a protective film in this order.

[0284] (6) Preparation of the first retardation layer (i) Preparation of composition for forming photo-alignment film 5 parts of a photo-alignment material (weight average molecular weight: 30,000) having the following structure was mixed with 95 parts of cyclopentanone (solvent). The resulting mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a photo-alignment film.

[0285] [ka]

[0286] (ii) Preparation of the composition for forming the first retardation layer The following polymerizable liquid crystal compound A and polymerizable liquid crystal compound B were mixed in 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 6 parts of a polymerization initiator, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one ("Irgacure 369 (Irg369)" manufactured by BASF Japan Ltd.) were added.

[0287] Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a first retardation layer.

[0288] Polymerizable liquid crystal compound A was produced by the method described in JP-A-2010-31223. Polymerizable liquid crystal compound B was produced according to the method described in JP-A-2009-173893. The molecular structures of each compound are shown below.

[0289] (Polymerizable liquid crystal compound A) [ka]

[0290] (Polymerizable liquid crystal compound B) [ka]

[0291] (iii) Preparation of retardation layer substrate A cycloolefin resin film (ZF-14-50, manufactured by Zeon Corporation) having a thickness of 50 μm was subjected to corona treatment to prepare a retardation layer substrate. The corona treatment was performed using TEC-4AX manufactured by Ushio Inc. The corona treatment was performed once under the conditions of an output of 0.78 kW and a treatment speed of 10 m / min.

[0292] (iv) Formation of photo-alignment film The composition for forming a photoalignment film was applied to the retardation layer substrate using a bar coater. The applied film was dried at 80° C. for 1 minute, and then irradiated with 100 mJ / cm 2 using a polarized UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.). 2 The polarized UV exposure was carried out with an integrated light amount of The thickness of the horizontal alignment film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and found to be 100 nm.

[0293] (v) Formation of the first retardation layer Next, in an environment of room temperature 25°C and relative humidity 30%, the composition for forming the first retardation layer was passed through a PTFE membrane filter (manufactured by Advantec Toyo Co., Ltd., product number: T300A025A) with a pore size of 0.2 μm, and applied using a bar coater onto a substrate film with an alignment film kept at 25°C. The coating film was dried at 120°C for 1 minute, and then irradiated with ultraviolet light (under a nitrogen atmosphere, wavelength: 365 nm, accumulated light amount at wavelength 365 nm: 1000 mJ / cm2) using a high-pressure mercury lamp (Uniquer VB-15201BY-A, manufactured by Ushio Inc.). 2 The thickness of the resulting coating film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and found to be 2 μm. The retardation values ​​of the obtained first retardation layer were measured to find that Re(450) was 121 nm, Re(550) was 139 nm, and Re(650) was 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

[0294] (7) Preparation of the second retardation layer (i) Preparation of Oriented Polymer Composition (1) An oriented polymer composition (1) was obtained by mixing 1 part of Sunever SE-610 (manufactured by Nissan Chemical Industries, Ltd.) and 99 parts of 2-butoxyethanol.

[0295] (ii) Preparation of the composition for forming the second retardation layer The following polymerizable liquid crystal (BASF, LC242) was mixed in 19.2 parts, a leveling agent (BYK Japan, "BYK-361N") in 0.1 parts, a polymerization initiator (BASF Japan, "Irgacure 907") in 0.5 parts, a reaction additive (BASF Japan, "Laromaer LR-9000") in 1.1 parts, and propylene glycol 1-monomethyl ether 2-acetate in 79.1 parts. The mixture was stirred at 80°C for 1 hour to obtain a composition for forming a second retardation layer.

[0296] [ka]

[0297] (iii) Preparation of retardation layer substrate A cycloolefin resin film (ZF-14-50, manufactured by Zeon Corporation) having a thickness of 50 μm was subjected to corona treatment to prepare a retardation layer substrate. The corona treatment was performed using TEC-4AX manufactured by Ushio Inc. The corona treatment was performed once under the conditions of an output of 0.78 kW and a treatment speed of 10 m / min.

[0298] (iv) Formation of oriented polymer film The alignment polymer composition (1) was applied to the retardation layer substrate using a bar coater and dried at 90° C. for 1 minute to obtain an alignment film. The thickness of the alignment film obtained was measured with a laser microscope and found to be 34 nm.

[0299] (v) Formation of the second retardation layer Next, a composition for forming a second retardation layer is applied onto the alignment film using a bar coater. After drying at 25°C for 1 minute, the sample was irradiated with ultraviolet light using a high-pressure mercury lamp (under a nitrogen atmosphere, temperature: 25°C, cumulative light intensity at a wavelength of 365 nm: 1000 mJ / cm 2) to obtain a second retardation layer. The thickness of the obtained second retardation layer was measured by a laser microscope and found to be 450 nm. In addition, the retardation value of the obtained retardation film (2) at a wavelength of 550 nm was measured and found to be Re(550)=1 nm and Rth(550)=-70 nm. That is, the second retardation layer had the optical properties represented by the following formula (3). Note that the retardation value of the COP at a wavelength of 550 nm is approximately 0, so there is no effect on the optical properties. nx≒ny <nz (3)

[0300] (8) Preparation of retardation plate A The first retardation layer of the first retardation layer with the retardation layer substrate and the second retardation layer of the second retardation layer with the retardation layer substrate were each subjected to a corona treatment. The prepared active energy ray curable adhesive A was applied to one of the corona treated surfaces, and the first retardation layer with the retardation layer substrate and the second retardation layer with the retardation layer substrate were bonded together. The second retardation layer with the retardation layer substrate was irradiated with ultraviolet light to cure the ultraviolet curable adhesive, thereby forming an adhesive layer. The ultraviolet light was 420 mJ / cm2 UVA with a wavelength of 320 nm to 390 nm. 2 The light was irradiated so that the thickness of the retardation plate A was 1.5 μm. The retardation plate A was obtained by laminating the retardation layer substrate / first retardation layer / adhesive layer A / second retardation layer / retardation layer substrate in this order. The thickness of the adhesive layer A after curing was measured with a laser microscope (manufactured by Olympus Corporation, "LEXT") and was found to be 1.5 μm.

[0301] (9) Preparation of retardation plate B A retardation plate B was produced in the same manner as in (8), except that the active energy ray curable adhesive B was used instead of the active energy ray curable adhesive A. A retardation plate B was obtained in which the retardation layer substrate / first retardation layer / adhesive layer B / second retardation layer / retardation layer substrate were laminated in this order. The thickness of the adhesive layer B after curing was measured with a laser microscope (manufactured by Olympus Corporation, "LEXT") and was 3.0 μm.

[0302] (10) Preparation of retardation plate C A retardation plate C was produced in the same manner as the retardation plate B, except that the pressure-sensitive adhesive layer (1) was used instead of the active energy ray-curable adhesive layer B.

[0303] (11) Preparation of retardation plate D A retardation plate D having a substrate / alignment layer / second retardation layer (positive C plate) / alignment layer / first retardation layer (λ / 4 layer) laminated in this order was produced as follows.

[0304] (base material) A cycloolefin polymer film (COP) (ZF-14 manufactured by Zeon Corporation) was prepared as a substrate.

[0305] (Corona treatment) The corona treatment device used was AGF-B10 manufactured by Kasuga Denki Co., Ltd. The corona treatment was carried out once using the corona treatment device under conditions of an output of 0.3 kW and a treatment speed of 3 m / min.

[0306] (High pressure mercury lamp) The high pressure mercury lamp used was a Uniqure VB-15201BY-A manufactured by Ushio Electric Co., Ltd.

[0307] The oriented polymer composition (1) prepared in the preparation of the retardation film A was applied to the surface of the substrate that had been subjected to the corona treatment using a bar coater, and dried at 90° C. for 1 minute. The thickness of the obtained oriented film was measured with a laser microscope and found to be 34 nm. Next, The composition for forming the second retardation layer prepared in the production of the retardation plate A was applied using a bar coater, dried at 90°C for 1 minute, and then irradiated with ultraviolet light using a high-pressure mercury lamp (under a nitrogen atmosphere, integrated light amount at a wavelength of 365 nm: 1000 mJ / cm 2) to form a second retardation layer (positive C plate), and a second retardation film having a second retardation layer was obtained. The thickness of the obtained second retardation layer was measured with a laser microscope, and the thickness was 450 nm. In addition, the retardation value of the obtained second retardation film at a wavelength of 550 nm was measured, and Re(550)=1 nm, Rth(550)=-70 nm. That is, the second retardation layer has a structure represented by the following formula (3): nx≒ny <nz (3) The retardation value of the substrate at a wavelength of 550 nm is approximately 0, so there is no effect on the optical properties.

[0308] Next, the following alignment polymer composition (2) was applied onto the second retardation layer of the second retardation film using a bar coater and dried at 100°C for 1 minute. The thickness of the obtained alignment film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and found to be 100 nm. Next, the alignment film was subjected to a rubbing treatment, and a composition obtained by adding 1 part of Larmer (registered trademark) LR9000 (manufactured by BASF Japan) to the composition for forming the first retardation layer prepared in the preparation of the retardation plate A was applied onto the treated surface using a bar coater and dried at 120°C for 1 minute. The coating film was irradiated with ultraviolet light using a high-pressure mercury lamp (under a nitrogen atmosphere, accumulated light amount at a wavelength of 365 nm: 1000 mJ / cm 2 ) to form a first retardation layer on the second retardation layer, thereby obtaining a retardation plate D. The thickness of the obtained first retardation layer was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) to be 2 μm. The retardation values ​​of the obtained retardation plate D were measured to be 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 D had the optical properties represented by the above formulas (1), (2), and (4).

[0309] (Oriented polymer composition (2)) Commercially available polyvinyl alcohol (Polyvinyl alcohol 1000 fully saponified type, Wako Pure Chemical Industries, Ltd.) Add water and heat at 100°C for 1 hour to a solid content of 2% by mass (solvent concentration 9 8% by mass) of an oriented polymer composition (2).

[0310] (12) Preparation of circular polarizing plate Example 1 The polarizer of the linear polarizing plate was subjected to corona treatment, and the surface of the pressure-sensitive adhesive layer (1) with a release film from which one release film had been peeled off was attached, and then the other release film of the pressure-sensitive adhesive layer was peeled off. The retardation layer substrate on the first retardation layer side of the retardation plate A was peeled off and corona treatment was applied to this pressure-sensitive adhesive layer. Subsequently, the surface on the second retardation layer side from which the retardation layer substrate had been peeled off was subjected to corona treatment, and the surface of the pressure-sensitive adhesive layer (2) with a release film from which one release film had been peeled off was attached. In this way, a circular polarizing plate of Example 1 in which linear polarizing plate / pressure-sensitive adhesive layer (1) / first retardation layer / adhesive layer A / second retardation layer / pressure-sensitive adhesive layer (2) / release film were laminated was obtained.

[0311] Example 2 A circularly polarizing plate was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive layer (2) was used instead of the pressure-sensitive adhesive layer (1).

[0312] Example 3 A circularly polarizing plate was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive layer (3) was used instead of the pressure-sensitive adhesive layer (1).

[0313] Example 4 The polarizer side of the linear polarizer and the first retardation layer side of the retardation plate A from which the retardation layer base material had been peeled off were each subjected to a corona treatment. The prepared active energy ray curable adhesive C was applied to one of the corona-treated surfaces, and the linear polarizer and the retardation plate A were bonded together. The ultraviolet ray curable adhesive was cured by irradiating ultraviolet rays from the linear polarizer side, forming an adhesive layer C. The ultraviolet ray was UVA with a wavelength of 320 nm to 390 nm at 420 mJ / cm. 2The thickness of the active energy ray curable adhesive after curing was measured with a laser microscope (manufactured by Olympus Corporation, "LEXT") and found to be 1.5 μm. Subsequently, a corona treatment was performed on the surface from which the retardation layer base material on the second retardation layer side was peeled off, and one surface of the pressure-sensitive adhesive layer (2) with a release film was attached to the surface from which the release film was peeled off. In this way, a circular polarizing plate of Comparative Example 1 was obtained in which a linear polarizing plate / adhesive layer C / first retardation layer / adhesive layer A / second retardation layer / adhesive layer (2) / release film were laminated.

[0314] Example 5 A circularly polarizing plate was produced in the same manner as in Example 1, except that the retardation plate D was used instead of the retardation plate A. The base material used for forming the retardation layer was peeled off, and then the pressure-sensitive adhesive layer (2) was laminated.

[0315] Example 6 A circularly polarizing plate was produced in the same manner as in Example 5, except that the pressure-sensitive adhesive layer (2) was used instead of the pressure-sensitive adhesive layer (1).

[0316] Example 7 A circularly polarizing plate was produced in the same manner as in Example 5, except that the pressure-sensitive adhesive layer (3) was used instead of the pressure-sensitive adhesive layer (1).

[0317] Example 8 A circular polarizing plate was prepared in the same manner as in Example 4, except that retardation plate D was used instead of retardation plate A.

[0318] Comparative Example 1 A circularly polarizing plate was produced in the same manner as in Example 4, except that the active energy ray-curable adhesive B was used instead of the active energy ray-curable adhesive C.

[0319] Comparative Example 2 A circular polarizing plate was prepared in the same manner as in Comparative Example 1, except that retardation plate D was used instead of retardation plate A.

[0320] (Reference example 1) A circular polarizing plate was prepared in the same manner as in Comparative Example 1, except that the retardation plate C was used instead of the retardation plate A.

[0321] (Reference example 2) A circular polarizing plate was prepared in the same manner as in Comparative Example 1, except that retardation plate B was used instead of retardation plate A.

[0322] (13) Evaluation of adhesion The adhesion between the first retardation layer and the second retardation layer of the obtained circular polarizing plate was evaluated by the following method. Ta.

[0323] (i) Preparation of a sample for evaluating adhesion between retardation layers A corona treatment was applied to a cycloolefin resin film (Zeon Corporation, "ZF-14-50") having a thickness of 50 μm, and the surface from which the release film of each of the circular polarizers prepared in (12) had been peeled off was attached to the film. Subsequently, a corona treatment was applied to the linear polarizer side of the circular polarizer, and one surface from which the release film of the pressure-sensitive adhesive layer (2) with a release film had been peeled off was attached to the film, and this was used as a sample for evaluating adhesion between retardation layers.

[0324] (ii) Adhesion evaluation 1 (initial stage) The obtained sample for adhesion evaluation was cut into a size of 200 mm in length × 25 mm in width, and attached to an alkali-free glass plate via the adhesive layer on the linear polarizer side, and left for one day in an atmosphere at a temperature of 23°C and a relative humidity of 60%.

[0325] A peel test was performed on the evaluation sample attached to the non-alkali glass plate, in which the first retardation layer and the second retardation layer were peeled off at a peeling speed of 300 mm / min in a 180° direction. The peel strength (adhesion) [N / 25 mm] at this time was measured using an "Autograph AGS-50NX" manufactured by Shimadzu Corporation. The measurement results are shown in Table 1. In addition, in Reference Examples 1 and 2, the first retardation layer and the second retardation layer were adhered to each other to such an extent that measurement was not possible. In Reference Examples 1 and 2, it can be said that the peel strength between the first retardation layer and the second retardation layer is more than 1.0 N / 25 mm.

[0326] (iii) Adhesion evaluation 2 (after high humidity and heat test) The evaluation sample laminated to an alkali-free glass plate was subjected to a high humidity heat test in which the sample was stored at a temperature of 80° C. and a relative humidity of 90% RH for 48 hours, and then the adhesion between the first retardation layer and the second retardation layer was evaluated by the same method as in (ii). The measurement results are shown in Table 1. In Reference Examples 1 and 2, the first retardation layer and the second retardation layer were in such close contact with each other that measurement was not possible. In Reference Examples 1 and 2, the peel strength between the first retardation layer and the second retardation layer can be said to be more than 1.0 N / 25 mm.

[0327] (14) Durability evaluation The durability of the obtained circularly polarizing plate against external forces was evaluated by the following method.

[0328] (i) Durability rating 1 (initial) The obtained circular polarizing plate was evaluated by a crosshatch test (JIS "cross-cut adhesion test") according to JIS D0202-1988 as an index of durability against external forces. The release film on the second retardation layer side of the circular polarizing plate was peeled off, and the plate was attached to glass via the adhesive layer (2). 100 1 mm square cross-cuts were cut with a cutter knife on the linear polarizing plate side opposite the glass surface, and adhesive tape (25 mm wide, made by Nichiban) was completely attached. Next, the adhesive tape was peeled off in a direction of 90° to the surface. The durability against external forces was evaluated based on the number of cross-cuts that remained unpeeled out of the 100 cross-cuts. When the number of remaining cross-cuts was 95 to 100 / 100, it was rated as A, when it was 50 to 95 / 100, it was rated as B, and when it was 0 to 49 / 100, it was rated as C. Table 1 shows the evaluation results.

[0329] (ii) Durability evaluation 2 (after high humidity and heat test) The obtained polarizing plate was subjected to a high humidity and heat test in which it was stored at a temperature of 80° and a relative humidity of 90% for 48 hours, and then its durability against external forces was evaluated in the same manner as in (i). Table 1 shows the evaluation results.

[0330] [Table 1] [Explanation of symbols]

[0331] 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

1. A polarizing plate in which a linearly polarizing plate, a first bonding layer, and a retardation plate are laminated in this order, wherein the retardation plate, has a first retardation layer and a second retardation layer, the first retardation layer and the second retardation layer contain a cured product of a liquid crystal compound, the peel strength between the first retardation layer and the second retardation layer is 1.0 N / 25 mm or less, the first bonding layer is made of an adhesive having a tensile storage modulus of 10 MPa or less at a temperature of 23°C, the first bonding layer has a thickness of 25 μm or less, polarizing plate.

2. The polarizing plate according to claim 1, wherein the retardation plate has only an alignment film or no other intervening layer between the first retardation layer and the second retardation layer.

3. The linearly polarizing plate has a polarizer, the polarizer has a thickness of 15 μm or less, polarizing plate according to claim 1 or 2.

4. The linearly polarizing plate has a protective film provided on the surface of the polarizer opposite to the first bonding layer, the protective film has a thickness of 30 μm or less, polarizing plate according to claim 3.

5. The polarizing plate according to claim 1 or 2, wherein the first retardation layer is an inverse-dispersive λ / 4 layer.

6. The polarizing plate according to claim 1 or 2, wherein the second retardation layer is a positive C-plate.

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