Manufacturing method of composite polarizing plates

Abstract

The objective is to provide a composite polarizing plate with high surface uniformity. [Solution] A method for manufacturing a composite polarizing plate, comprising a polarizing plate, an adhesive layer, and a phase difference layer adjacent to each other in this order, (a) Steps to prepare an untreated polarizing plate, (b) A process of obtaining a polarizing plate by annealing an untreated polarizing plate, and (c) A process of laminating the polarizing plate, adhesive layer and phase difference layer in this order. A method for manufacturing a composite polarizing plate, comprising at least [a certain element].

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a composite polarizing plate. [Background technology]

[0002] Conventionally, polarizing plates have been used in various image display panels such as liquid crystal display panels and organic electroluminescent (OLED) display panels, by being bonded to image display elements such as liquid crystal cells and OLED display elements. Polarizing plates usually have a multilayer structure, such as a layer of polymer material obtained by stretching and a cured layer of a curable composition. Patent Document 1 discloses that a thin and high-performance liquid crystal display device can be manufactured by placing a composite polarizing plate between the backlight unit and the liquid crystal cell of a liquid crystal display device, with a reflective polarizer surface on the backlight unit side and an absorptive polarizer on the liquid crystal cell side. Patent Document 2 discloses an optical laminate in which a polarizing film or a phase difference film is bonded to a reflective polarizing plate. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-124467 [Patent Document 2] Japanese Patent Publication No. 2024-068144 [Overview of the project] [Problems that the invention aims to solve]

[0004] From the viewpoint of further improving the optical properties of composite polarizers, it has been found that high surface uniformity of composite polarizers is sometimes required. Therefore, the present invention aims to provide a composite polarizer with high surface uniformity. [Means for solving the problem]

[0005] The present inventors, after diligently studying to solve the above problems, have completed the present invention. That is, the present invention encompasses the following aspects. [1] A method for manufacturing a composite polarizing plate, comprising a polarizing plate, an adhesive layer, and a phase difference layer adjacent to each other in this order, (a) Steps to prepare an untreated polarizing plate, (b) A process of obtaining a polarizing plate by annealing an untreated polarizing plate, and (c) A process of laminating the polarizing plate, adhesive layer and phase difference layer in this order. A method for manufacturing a composite polarizing plate, comprising at least [a certain element]. [2] The manufacturing method according to [1], wherein the annealing treatment is carried out by heating the untreated polarizing plate while it is held in the air. [3] The manufacturing method described in [2], wherein the heating temperature in the annealing process is 60 to 150°C. [4] The manufacturing method according to any one of [1] to [3], wherein the untreated polarizing plate has no protective film, or has a protective film on at least one surface, and if it has a protective film, the protective film is bonded to the untreated polarizing plate via an adhesive layer having a Martens hardness of 5N or less. [5] The manufacturing method according to [4], wherein, if the untreated polarizing plate has a protective film, the thickness of the adhesive layer between the untreated polarizing plate and the protective film is 5 to 50 μm. [6] The manufacturing method according to any one of [1] to [5], wherein the annealing treatment is performed by heating the untreated polarizing plate while it is suspended in mid-air. [7] The manufacturing method according to any one of [1] to [6], wherein the annealing treatment is performed by heating two or more untreated polarizing plates while they are held in the air spaced apart from each other, or by heating two or more untreated polarizing plates with a spacer in between while they are held in the air. [Effects of the Invention]

[0006] According to the present invention, a polarizing plate with high surface uniformity can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram illustrates the state during the annealing process in one embodiment of the present invention. [Figure 2] This figure shows the mapping used to evaluate reflectivity in the examples. [Modes for carrying out the invention]

[0008] The embodiments of the present invention will be described in detail below. However, the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention.

[0009] The present invention provides a method for manufacturing a composite polarizing plate having high surface uniformity, comprising a polarizing plate, an adhesive layer, and a phase difference layer arranged adjacently in that order.

[0010] Composite polarizers, which include a polarizing plate, an adhesive layer, and a phase difference layer adjacent to each other in this order, are widely used in image display elements such as liquid crystal cells and organic EL display elements, and more recently, they have also been used in head-mounted displays and AR glasses used in VR (Virtual Reality) and AR (Augmented Reality) technologies. In particular, when using composite polarizers in VR and AR devices, uniform optical properties are required, but it was unclear which characteristic values ​​of the composite polarizer affect the uniformity of the optical properties. The inventors evaluated various characteristic values ​​of the polarizing plate and found that improving the uniformity of the surface of the composite polarizer also improves the uniformity of the optical properties, and thus discovered the method for manufacturing a composite polarizer of the present invention.

[0011] The present invention relates to a method for manufacturing a composite polarizing plate, comprising a polarizing plate, an adhesive layer, and a phase difference layer adjacent to each other in this order, (a) Steps to prepare an untreated polarizing plate, (b) A process of obtaining a polarizing plate by annealing an untreated polarizing plate, and (c) A process of laminating the polarizing plate, adhesive layer and phase difference layer in this order. A manufacturing method that includes at least [a specific ingredient / method].

[0012] In step (a), an untreated polarizing plate is prepared. Commercially available products such as "DBEF" or "APF" (manufactured by 3M, Sumitomo 3M Co., Ltd.) may be used as the untreated polarizing plate, or an untreated polarizing plate may be manufactured.

[0013] Next, in step (b), the untreated polarizing plate is annealed to obtain a polarizing plate. Preferably, the annealing treatment is carried out by heating the untreated polarizing plate while it is held in the air.

[0014] The reason why heating an untreated polarizing plate while it is suspended in air improves surface uniformity is not clear, but it is thought that heating it while suspended in air softens the polymers contained in the untreated polarizing plate, promoting the uniformity of the surface shape of the untreated polarizing plate. Furthermore, by using λc=250μm and λf=3000μm as cutoff values, it is possible to remove data related to surface irregularities that are too small or large irregularities that do not significantly affect visibility, and evaluate mainly the shapes that have a greater impact on visibility.

[0015] The state of holding an untreated polarizing plate in the air means that the surface of the untreated polarizing plate is held in the air without contact with anything else, except for the holding portion used to hold it in the air. For example, it is preferable to hold the untreated polarizing plate by gripping it with a clip or other gripping member and suspending it in the air, or to hold the untreated polarizing plate in a tray equipped with a gripping portion that has a small contact area with the untreated polarizing plate.

[0016] For example, the state shown in Figure 1 is a possible configuration in which an untreated polarizing plate is held in the air by gripping members such as clips. Alternatively, the state shown in Figure 2 is a possible configuration in which an untreated polarizing plate is held on a support having a gripping portion with a small contact area with the untreated polarizing plate. As is clear from Figures 1 and 2, the untreated polarizing plate may be perpendicular or horizontal to the ground as long as it is held in the air.

[0017] An untreated polarizing plate may have no protective film, or may have a protective film on at least one side. If the untreated polarizing plate has a protective film, it is preferable that the protective film is bonded to the untreated polarizing plate via an adhesive layer having a Martens hardness of 5N or less. As mentioned above, commercially available products such as "DBEF" and "APF" (manufactured by 3M, Sumitomo 3M Co., Ltd.) may be used as untreated polarizing plates, but these commercially available products usually have a protective film bonded to them. According to the inventors' studies, the protective film bonded to these commercially available products is usually bonded to the polarizing plate via an adhesive layer having a Martens hardness greater than 5N. Therefore, from the viewpoint of improving the surface uniformity of the polarizing plate, when using these commercially available products, it is preferable to perform the annealing treatment with the protective film removed, or, after removing the protective film, to bond another protective film that can be bonded via an adhesive layer having a Martens hardness of 5N or less, and then perform the annealing treatment. When a protective film is attached via an adhesive layer and then annealed, the thickness of the adhesive layer is preferably 5 to 50 μm, more preferably 10 to 30 μm.

[0018] From the viewpoint of improving the surface uniformity of the polarizing plate, the untreated polarizing plate may or may not have a protective film on one or both sides via an adhesive layer with a Martens hardness of 5N or less. From the viewpoint of preventing dust and foreign matter from adhering to the polarizing plate due to the environment during annealing, and suppressing the occurrence of wrinkles and cracks due to heating during annealing, it is preferable to have a protective film via an adhesive layer with a Martens hardness of 5N or less.

[0019] The state in which an untreated polarizing plate is held in the air does not include a state in which the polarizing plate is placed on a horizontal stand so that one entire surface covers the surface of the stand, or a state in which the suspended polarizing plate is in contact with a wall. Furthermore, when holding in the air, it is preferable to insert spacers between adjacent untreated polarizing plates so that they do not come into contact with each other. When holding multiple untreated polarizing plates in the air, it is preferable to hold them in the air with, for example, a gap of about 3 to 5 cm between them. The annealing treatment is preferably carried out by heating the untreated polarizing plate while it is suspended in the air, and more preferably by heating two or more untreated polarizing plates held in the air spaced apart from each other, or by heating two or more untreated polarizing plates held in the air with spacers inserted between them.

[0020] The heating temperature in the annealing process is not particularly limited as long as a polarizing plate with high surface uniformity can be obtained, but from the viewpoint of the thermophysical properties of the raw materials commonly used for polarizing plates, it is preferably 60 to 150°C, more preferably 70 to 130°C, and even more preferably 80 to 120°C. The heating time is also not particularly limited as long as a polarizing plate with high surface uniformity can be obtained, but from the viewpoint of the thermophysical properties of the raw materials commonly used for polarizing plates, it is preferably 10 minutes to 2 hours, more preferably 15 minutes to 1.5 hours, and even more preferably 20 minutes to 1 hour.

[0021] Next, in step (c), the polarizing plate processed as described above, the adhesive layer, and the phase difference layer are laminated in this order. When manufacturing the composite polarizing plate of the present invention by laminating the phase difference film and the polarizing plate via the adhesive layer, it is preferable to laminate them so that the slow axis (optical axis) of the phase difference film and the absorption axis of the polarizing film are substantially 45° apart. By laminating them so that the slow axis (optical axis) of the phase difference film and the absorption axis of the polarizing film are substantially 45° apart, the function of a circular polarizing plate can be obtained. Note that substantially 45° is usually in the range of 45±5°.

[0022] The composite polarizer obtained by the manufacturing method of the present invention has high surface uniformity. Specifically, high uniformity refers to the height profile of the surface of the polarizer adjacent to the adhesive layer of the polarizer, calculated in μrad form using λc=250μm and λf=3000μm as cutoff values, and the root mean square slope S slope The uniformity is such that the value is 0 to 100 μrad. Therefore, the composite polarizing plate obtained by the manufacturing method of the present invention has a root mean square slope S calculated by the above method for the height profile of the surface adjacent to the adhesive layer of the polarizing plate. slope The range is 0-100 μrad. Furthermore, since untreated polarizing plates do not have high surface uniformity, the root mean square slope S was calculated in the same manner as above. slope However, it is usually over 100 μrad.

[0023] The above root mean square slope S of the composite polarizing plate obtained by the manufacturing method of the present invention slope The slope is preferably 0 to 150 μrad, more preferably 0 to 100 μrad, even more preferably 0 to 80 μrad, and even more preferably 0 to 50 μrad. Root mean square slope S slope This can be obtained, for example, by using a non-contact surface / layer cross-sectional shape measurement system (Ryoka Systems Co., Ltd. "VertScan") to obtain the height profile of the surface adjacent to the adhesive layer of the polarizing plate at the above cutoff value, and then calculating the double square root slope converted to μrad format from the obtained height profile. Specifically, it can be calculated by the method described in the examples. Root mean square slope S slope For example, it is also possible to calculate the waveness value using the above cutoff value with a white light interferometer manufactured by Zygo.

[0024] (Polarizing plate) The type of polarizer is not particularly limited and may be an absorptive polarizer or a reflective polarizer. An absorptive polarizer is an element that separates natural light into orthogonal polarization components, transmits only one of them, and absorbs the other, thereby extracting light with a polarization plane in one direction. Examples of absorptive polarizers include PVA-iodine-based polarizers and polarizers that include a layer made of a cured polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye. A reflective polarizer is a polarization conversion element that has the function of separating natural light into transmitted polarization and reflected or scattered polarization. Specifically, it can be an anisotropic multilayer thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. Examples of commercially available anisotropic multilayer thin films include the product names "DBEF" and "APF" (manufactured by 3M and Sumitomo 3M Co., Ltd.). Even if these conventional polarizers are used as they are, it is difficult to obtain a polarizer with sufficiently high surface uniformity. Therefore, by using the manufacturing method of the present invention to anneal a polarizing plate and then using it in the manufacture of a composite polarizing plate, it is possible to manufacture a composite polarizing plate with sufficiently high surface uniformity.

[0025] The thickness of the polarizing plate can be about 10 to 100 μm, but from the viewpoint of thinning composite polarizing plates and liquid crystal display devices, it is preferably 10 to 50 μm.

[0026] (Adhesive layer) In the composite polarizing plate of the present invention, the adhesive layer located between the polarizing plate and the phase difference layer is a layer capable of bonding the polarizing plate and the phase difference layer, and can be prepared using materials conventionally known in the art. For example, adhesive compositions mainly composed of resins such as (meth)acrylic, rubber, urethane, ester, silicone, and polyvinyl ether can be used. Among these, from the viewpoint of excellent transparency, tackiness, weather resistance, heat resistance, etc., it is preferable that the adhesive layer be formed from an adhesive composition with a (meth)acrylic resin as the base polymer.

[0027] The adhesive composition may be an active energy ray curing adhesive, a thermosetting adhesive, etc. Examples of (meth)acrylic resins (base polymers) used in the adhesive composition that forms the adhesive layer include polymers or copolymers in which one or more (meth)acrylic acid esters such as butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isobornyl (meth)acrylate are monomer components. The (meth)acrylic resin may also be a copolymer of polar monomers. Examples of polar monomers include monomers having carboxylic acid groups, carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc., such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, hydroxyethyl (meth)acrylic acid, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0028] In one embodiment of the present invention, the structural units derived from (meth)acrylic acid esters in the (meth)acrylic resin constituting the adhesive composition are preferably 80 to 100% by mass, more preferably 85% or more by mass, and even more preferably 90% or more by mass, based on the total mass of all structural units constituting the (meth)acrylic resin. Furthermore, if the (meth)acrylic resin contains structural units derived from polar monomers, the structural units derived from polar monomers are preferably 0.1 to 10% by mass, more preferably 0.5% or more by mass, even more preferably 1% or more by mass, and even more preferably 8% or less by mass, based on the total mass of all structural units constituting the (meth)acrylic resin.

[0029] The weight-average molecular weight (hereinafter also simply referred to as "Mw") of the (meth)acrylic resin is preferably between 500,000 and 2,500,000. A weight-average molecular weight of 500,000 or more improves the durability of the adhesive layer in high-temperature, high-humidity environments. A weight-average molecular weight of 2,500,000 or less improves the operability when applying the adhesive composition. The molecular weight distribution (Mw / Mn), expressed as the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (hereinafter also simply referred to as "Mn"), is usually between 2 and 10. In this specification, the weight-average molecular weight and the number-average molecular weight are polystyrene equivalent values ​​measured by gel permeation chromatography (GPC).

[0030] (Meth)acrylic resins can be produced by various known methods, such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. A polymerization initiator is typically used in the production of these (meth)acrylic resins. The polymerization initiator content is preferably 0.001 to 5 parts by mass per 100 parts by mass of the total monomers used in the production of the (meth)acrylic resin.

[0031] As polymerization initiators, thermal polymerization initiators and photopolymerization initiators are used. Examples of thermal polymerization initiators include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonnitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); lauryl peroxide, Examples of organic peroxides include tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl)peroxide; and inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. Examples of photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone.

[0032] When preparing (meth)acrylic resins by solution polymerization, for example, a method can be used in which the desired monomer and organic solvent are mixed, a thermal polymerization initiator is added under a nitrogen atmosphere, and the mixture is stirred at 40 to 90°C, preferably 50 to 80°C. In addition, to control the reaction, monomers and polymerization initiators may be added continuously or intermittently during polymerization, or added in a dissolved state in the organic solvent. As organic solvents, for example, aromatic hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate and butyl acetate; aliphatic alcohol solvents such as propyl alcohol and isopropyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be used.

[0033] The adhesive composition may contain only the above-mentioned (meth)acrylic resin, but a crosslinking agent may also be used in combination. Examples of crosslinking agents include divalent or higher metal ions that form a metal carboxylate salt with carboxyl groups; polyamine compounds that form an amide bond with carboxyl groups; polyepoxy compounds or polyols that form an ester bond with carboxyl groups; and polyisocyanate compounds that form an amide bond with carboxyl groups. Among these, polyisocyanate compounds are preferred from the viewpoint of crosslinking rate and durability.

[0034] If a crosslinking agent is included, its proportion is, for example, 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the base polymer.

[0035] The adhesive composition may optionally further contain a silane compound. The inclusion of a silane compound can improve the adhesion between the adhesive layer formed from the adhesive and the laminated layer. Examples of silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These may be used individually or in combination of two or more.

[0036] When a silane compound is included, its content in the adhesive is usually 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, more preferably 0.05 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the base polymer.

[0037] In this specification, an active energy ray curing adhesive means an adhesive that has the property of curing upon irradiation with active energy rays such as ultraviolet rays or electron beams, possesses adhesive properties even before irradiation with active energy rays so that it can adhere to a substrate, and has the property of being able to adjust the adhesion strength, etc., after curing by irradiation with active energy rays. The active energy ray curing adhesive is preferably an ultraviolet curing adhesive.

[0038] Active energy ray curing adhesives generally consist of a base polymer such as (meth)acrylic resin and a crosslinking agent as described above, in addition to an energy ray polymerizable compound. Furthermore, they may optionally contain photopolymerization initiators, photosensitizers, and the like.

[0039] Examples of active energy ray polymerizable compounds include (meth)acrylic compounds such as (meth)acrylate monomers having at least one (meth)acryloyloxy group in the molecule; and (meth)acrylate oligomers having at least two (meth)acryloyloxy groups in the molecule, obtained by reacting two or more functional group-containing compounds.

[0040] The adhesive composition may further contain conventionally common components as constituent elements of the adhesive composition. Examples of such components include additives such as resins other than the base polymer, tackifiers, fillers (metal powders and other inorganic powders, etc.), antioxidants, UV absorbers, dyes, pigments, colorants, defoamers, and corrosion inhibitors.

[0041] In one embodiment of the present invention, the adhesive layer may be composed of a reaction product of an adhesive composition containing a base polymer such as a (meth)acrylic resin, a crosslinking agent, and a silane compound. Such an adhesive layer can be formed by applying, for example, a diluted solution of the adhesive composition containing the above components with an organic solvent to the surface on which the adhesive layer will be formed and drying it.

[0042] In one embodiment of the present invention, it is more preferable that the adhesive layer is formed from an active energy ray-curable adhesive. When the adhesive layer is formed from an active energy ray-curable adhesive, for example, a diluted solution of an adhesive composition containing the components described above, for example, an organic solvent, can be applied to the surface on which the adhesive layer is to be formed, dried, and then irradiated with active energy rays to form a cured layer having a desired degree of curing.

[0043] The physical properties of the adhesive layer are not particularly limited as long as it is a layer capable of bonding the polarizing plate and the phase difference layer. However, from the viewpoint of suppressing peeling and wrinkle formation when the composite polarizing plate is processed at high temperatures, it is preferable that it has an elastic modulus of 20 to 600 kPa at 25°C. In the case of use in conventional flat panel display devices, composite polarizing plates are not usually heat-treated at high temperatures, so heat resistance when exposed to high temperatures of 140°C or higher was not necessarily required. In head-mounted displays and AR glasses used in VR (Virtual Reality) and AR (Augmented Reality) technologies, which have seen significant technological advancements in recent years, there is a demand for technology that widens the field of view in order to obtain a high sense of immersion and presence. The composite polarizing plate obtained by the manufacturing method of the present invention has high uniformity and can improve the field of view when used in combination with lenses in VR and AR devices. However, in order to use it as a display for VR and AR devices, it is usually necessary to mold the composite polarizing plate to a lens shape such as a plano-convex shape under high-temperature heating. Under such high-temperature heating conditions, conventional composite polarizers used as displays in flat panel displays may experience delamination or wrinkling between the polarizer and the phase difference layer due to heat treatment. While not necessarily limited to this, the inventors have found that one reason for this is the significant difference in dimensional change behavior due to heat between the polarizer and the phase difference layer. In the composite polarizer of the present invention, by making the adhesive layer between the polarizer and the phase difference layer relatively soft, with an elastic modulus within the above range, even if a difference in dimensional change rate occurs between the polarizer and the phase difference layer due to high-temperature heat treatment, this difference can be absorbed by the adhesive layer. As a result, it is believed that a composite polarizer can be obtained that exhibits excellent suppression of delamination and wrinkling between the polarizer and the phase difference layer even under high-temperature heat treatment, and that exhibits excellent moldability even when processed at high temperatures to match the shape of a plano-convex lens, etc., and can be processed into the desired shape without causing cracks, etc. From a similar viewpoint, the elastic modulus (25°C) of the adhesive layer is preferably 50 to 500 kPa, more preferably 70 to 400 kPa, and even more preferably 80 to 300 kPa, and may be, for example, 200 kPa or less or 150 kPa or less.The elastic modulus of the adhesive layer at 25°C can be measured using a viscoelasticity measuring device, for example, by the method described in the examples below.

[0044] The elastic modulus per unit thickness of the adhesive layer at 25°C is preferably 1 to 30 kPa / μm. When the elastic modulus per unit thickness is within this range, peeling and wrinkle formation between the polarizing plate and the phase difference layer during high-temperature heating are easily suppressed, and moldability at high temperatures can be improved. From the viewpoint of further enhancing these effects, the elastic modulus per unit thickness of the adhesive layer is more preferably 1.5 to 30 kPa / μm, even more preferably 3 to 30 kPa / μm, particularly preferably 6 to 30 kPa / μm, and especially preferably 10 to 30 kPa / μm. The elastic modulus per unit thickness of the adhesive layer can be calculated from the elastic modulus of the adhesive layer and the thickness of the adhesive layer as follows. Elastic modulus per unit film thickness (kPa / μm) = Elastic modulus (kPa) / Thickness (μm)

[0045] The thickness of the adhesive layer can be appropriately determined depending on the composition of the adhesive layer, the composition of the layers adjacent to the adhesive layer, etc. From the viewpoint of easy control of the elastic modulus, suppression of peeling and wrinkle formation in composite polarizers, and / or high-temperature moldability, it is preferably 1 to 50 μm, more preferably 3 to 40 μm, and even more preferably 3 to 30 μm, and may be, for example, 20 μm or less or 10 μm or less. The thickness of the adhesive layer can be measured by a laser microscope or film thickness gauge, and the same method can be used to measure the thickness of each layer and film, such as polarizers and phase difference layers, that constitute the composite polarizer.

[0046] (phase contrast layer) The phase difference layer in the composite polarizer is preferably composed of a polymerizable liquid crystal compound. When the phase difference layer is a cured layer (cured film) of a polymerizable liquid crystal compound, a thinner composite polarizer can be formed compared to when the layer having a phase difference is made of a stretched film.

[0047] From the viewpoint of thinning the composite panel, in one embodiment of the present invention, the thickness of the phase difference layer is preferably 0.1 to 5 μm, more preferably 0.5 to 5 μm, even more preferably 0.5 to 3 μm, and even more preferably 1 to 3 μm. In the present invention, the phase difference layer is a film that exhibits a phase difference in the in-plane or thickness direction, and may consist of a layer made of a polymerizable liquid crystal compound alone, or, if the layer made of the polymer and the alignment film for forming it are adjacent, the phase difference layer may consist of the alignment film. If the phase difference layer includes an alignment film, the thickness of the light distribution film is not included in the thickness of the phase difference layer.

[0048] In this specification, there may be one phase difference layer or two or more phase difference layers. When there are two or more phase difference layers, the thickness of each phase difference layer can be appropriately determined according to the optical properties required for each phase difference film, the configuration and application of the optical laminate, etc., and their thicknesses may be the same or different. The composite polarizing plate includes at least one phase difference layer adjacent to the adhesive layer. This phase difference layer is also referred to as "phase difference layer A".

[0049] The phase difference layer A included in the composite polarizer of the present invention has a phase difference value R at a wavelength of 550 nm, from the viewpoint of circular polarization of transmitted light. 550 However, it is preferably 135 to 160 nm. In other words, the phase difference layer is given by the following equation (1): 135nm ≤ Re(550) ≤ 160nm (1) [In the formula, Re(λ) represents the in-plane phase difference value of the phase difference film at a wavelength of λnm.] It is preferable that the following conditions are met. When the in-plane phase difference Re(550) of the phase difference layer is within the range of equation (1), the phase difference layer functions as a quarter-wave plate, and the effect of improving the front reflection hue (effect of suppressing coloration) when a composite polarizer containing the phase difference layer is applied to an organic EL display device or the like tends to be enhanced. A more preferable range for the phase difference value is 130 nm ≤ Re(550) ≤ 150 nm.

[0050] Furthermore, the phase difference layer A is in addition to equation (1) to the following equations (2) and (3): Re(450) / Re(550)≦1.00 (2) 1.00 ≤ Re(650) / Re(550) (3) [In the formula, Re(λ) represents the in-plane phase difference value of the phase difference film at a wavelength of λnm.] It is preferable that the following conditions are met. When the phase difference layer satisfies formulas (2) and (3), the phase difference film exhibits so-called inverse wavelength dispersion, where the in-plane phase difference value at short wavelengths is smaller than the in-plane phase difference value at long wavelengths. Composite polarizers having such a phase difference layer tend to have superior front hue when incorporated into organic EL display devices and the like. From the viewpoint of improving inverse wavelength dispersion and further enhancing the effect of improving the reflected hue in the front direction, Re(450) / Re(550) is preferably 0.70 or higher, more preferably 0.78 or higher, and also preferably 0.92 or lower, more preferably 0.90 or lower, even more preferably 0.87 or lower, particularly preferably 0.86 or lower, and most particularly preferably 0.85 or lower. Also, Re(650) / Re(550) is preferably 1.01 or higher, more preferably 1.02 or higher. Phase difference layer A is preferably an inverse wavelength dispersion phase difference layer.

[0051] The above phase difference value can be adjusted by the film thickness dA of the phase difference layer A. The in-plane phase difference value is determined by the formula ReA(λ)=(nxA(λ)-nyA(λ))×dA [wherein nxA(λ) represents the principal refractive index at wavelength λnm in the in-plane of the phase difference layer, nyA(λ) represents the refractive index at wavelength λnm in a direction perpendicular to the direction of nxA within the same plane as nxA, and dA represents the film thickness of the phase difference film]. Therefore, to obtain the desired in-plane phase difference value (ReA(λ): in-plane phase difference value of the phase difference film at wavelength λ(nm)), the three-dimensional refractive index and film thickness dA should be adjusted.

[0052] The composite polarizer of the present invention preferably includes a phase difference layer A, which is a "horizontally oriented liquid crystal cured film" in which a polymerizable liquid crystal compound is cured in a state in which it is oriented horizontally with respect to the phase difference film plane. When the optical laminate of the present invention contains only the phase difference layer A, the phase difference film is preferably a "horizontally oriented liquid crystal cured film", and more preferably satisfies the above formulas (1) to (3).

[0053] Examples of the retardation layer that the composite polarizing plate of the present invention may include are a retardation layer that is a positive C-plate (nx≈ny<nz), a retardation layer having a half-wave plate function, and the like. The retardation layer that is a positive C-plate is a "vertically aligned liquid crystal cured film" in which a polymerizable liquid crystal compound is cured in a state of being aligned in a direction perpendicular to the plane of the retardation film. By combining a retardation layer having a quarter-wave plate function and a retardation layer that is a positive C-plate, when the composite polarizing plate is applied to an organic EL display device or the like, improvement in the oblique reflection hue can be expected in addition to improvement in the front reflection hue.

[0054] The polymerizable liquid crystal compound capable of forming the retardation layer in the present invention can be appropriately selected from polymerizable liquid crystal compounds conventionally known in the field of retardation films according to the desired optical properties. The polymerizable liquid crystal compound that can be used in the present invention can be classified, for example, into a rod type (rod-like liquid crystal compound) and a disk type (disk-like liquid crystal compound, discotic liquid crystal compound) according to its shape, and any of the liquid crystal compounds can be used. Further, two or more rod-like liquid crystal compounds, two or more disk-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disk-like liquid crystal compound may be used.

[0055] The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group. Examples of the polymerizable liquid crystal compound generally include polymers (cured products) obtained by polymerizing the polymerizable liquid crystal compound alone in a state of being oriented in a specific direction, a polymerizable liquid crystal compound exhibiting positive wavelength dispersion, and a polymerizable liquid crystal compound exhibiting reverse wavelength dispersion. In the present invention, only one type of polymerizable liquid crystal compound may be used, or both types of polymerizable liquid crystal compounds may be mixed and used.

[0056] In the present invention, the polymerizable groups of the polymerizable liquid crystal compound that form the phase difference layer are preferably photopolymerizable groups. Here, a polymerizable group is a group that can participate in the polymerization reaction by active radicals or acids generated from a polymerization initiator. Examples of polymerizable groups of the polymerizable liquid crystal compound include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, (meth)acryloyl groups, oxyranyl groups, and oxetanyl groups. Among these, (meth)acryloyl groups, vinyl groups, and vinyloxy groups are more preferred, and (meth)acryloyl groups are even more preferred. The liquid crystalline properties exhibited by the polymerizable liquid crystal compound may be thermotropic liquid crystal or lyotropic liquid crystal, but thermotropic liquid crystal is preferred because it allows for precise control of film thickness. Furthermore, the phase order structure in the thermotropic liquid crystal may be nematic liquid crystal, smectic liquid crystal, or discotic liquid crystal. The polymerizable liquid crystal compound can be used alone or in combination of two or more types.

[0057] Polymerizable liquid crystal compounds that form a phase difference layer (hereinafter also referred to as "polymerizable liquid crystal compounds for phase difference layer formation") include compounds that satisfy all of the following conditions (a) to (d) from the viewpoint of imparting the phase difference properties represented by formulas (2) and (3).

[0058] (a) It is a compound that has thermotropic liquid crystal properties; (i) The polymerizable liquid crystal compound has π electrons along the long axis (a). (c) It has π electrons in a direction intersecting the longitudinal axis (a) [intersecting direction (b)]. (e) The π electron density in the long axis direction (a) of a polymerizable liquid crystal compound defined by the following formula (i), where N(πa) is the total number of π electrons present in the long axis direction (a) and N(Aa) is the total molecular weight present in the long axis direction: D(πa)=N(πa) / N(Aa) (i) The π electron density in the cross direction (b) of a polymerizable liquid crystal compound defined by the following formula (ii), where N(πb) is the total number of π electrons present in the cross direction (b) and N(Ab) is the total molecular weight present in the cross direction (b): D(πb) = N(πb) / N(Ab) (ii) satisfies 0 ≦ [D(πa) / D(πb)] ≦ 1 That is, the π - electron density in the crossing direction (b) is greater than the π - electron density in the long - axis direction (a). The polymerizable liquid - crystal compound for forming a retardation layer that satisfies all of the above (a) to (e) can form a nematic phase or a smectic phase, for example, by heating to a temperature above the phase transition temperature. In the nematic phase or smectic phase formed by the alignment of this polymerizable liquid - crystal compound, usually, the long - axis directions of the polymerizable liquid - crystal compounds are aligned parallel to each other, and this long - axis direction becomes the alignment direction of the nematic phase or smectic phase.

[0059] The polymerizable liquid - crystal compound for forming a retardation layer having the above characteristics generally exhibits reverse wavelength dispersion. As a compound that satisfies the characteristics of the above (a) to (e), specifically, for example, the following formula (B1): [Chemical formula] The compound represented by the formula (B1) can be used alone or in combination of two or more.

[0060] In the formula (B1), Ar represents a divalent group having an aromatic group which may have a substituent. The aromatic group here includes, for example, the groups exemplified by (Ar - 1) to (Ar - 23) described later. Also, Ar may have two or more aromatic groups. At least one of nitrogen atom, oxygen atom, and sulfur atom may be contained in the aromatic group. When there are two or more aromatic groups contained in Ar, the two or more aromatic groups may be bonded to each other by a divalent bonding group such as a single bond, -CO - O -, -O -.

[0061] In the formula (B1), G 1 and G 2Each of these independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atoms contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with halogen atoms, C1-C4 alkyl groups, C1-C4 fluoroalkyl groups, C1-C4 alkoxy groups, cyano groups, or nitro groups, and the carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with oxygen atoms, sulfur atoms, or nitrogen atoms.

[0062] In formula (B1), L 1 , L 2 B 1 and B 2 Each of these is independently a single bond or a divalent linking group.

[0063] In equation (B1), k and l each represent integers from 0 to 3 independently, satisfying the relationship 1 ≤ k + l. Here, if 2 ≤ k + l, then B 1 and B 2 , G 1 and G 2 These elements may be identical to each other, or they may be different.

[0064] In formula (B1), E 1 and E 2 Each of these independently represents an alkanediyl group having 1 to 17 carbon atoms, with an alkanediyl group having 4 to 12 carbon atoms being more preferred. Furthermore, the hydrogen atoms in the alkanediyl group may be substituted with halogen atoms, and the -CH2- in the alkanediyl group may be substituted with -O-, -S-, or -C(=O)-.

[0065] In formula (B1), P 1 and P 2 Each of these independently represents a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

[0066] G 1 and G 2Each of these is independently preferably a 1,4-phenylenediyl group which may be 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 which may be 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 methyl-substituted 1,4-phenylenediyl 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-cyclohexandiyl group. Also, there are multiple G 1 and G 2 Preferably, at least one of them is a divalent alicyclic hydrocarbon group, and L 1 or L 2 G that joins 1 and G 2 It is more preferable that at least one of these is a divalent alicyclic hydrocarbon group.

[0067] L 1 and L 2 Each of these is independently, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R a1 Ure a2 -, -R a3 COOR a4 -, -R a5 OCOR a6 -, -R a7 OC=OOR a8 -, -N=N-, -CR c =CR d -, or -C≡C-. Here, R a1 ~R a8 Each of these independently represents a single bond or an alkylene group with 1 to 4 carbon atoms, R c and R d L represents an alkyl group or hydrogen atom with 1 to 4 carbon atoms. 1 and L 2 Each is independently, more preferably a single bond, -OR a2-1 -, -CH2-, -CH2CH2-, -COORa4-1 -, or -OCOR a6-1 - is the case here R a2-1 , R a4-1 , R a6-1 Each of these independently represents either a single bond, -CH2-, or -CH2CH2-. 1 and L 2 Each of these is independently, and more preferably, a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, or -OCO-.

[0068] B 1 and B 2 Each of these is independently, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R a9 Ure a10 -, -R a11 COOR a12 -, -R a13 OCOR a14 -, or -R a15 OC=OOR a16 - is the case here R a9 ~R a16 Each of these independently represents a single bond or an alkylene group with 1 to 4 carbon atoms. 1 and B 2 Each is independently, more preferably a single bond, -OR a10-1 -, -CH2-, -CH2CH2-, -COOR a12-1 -, or -OCOR a14-1 - is the case here R a10-1 , R a12-1 , R a14-1 Each of these independently represents either a single bond, -CH2-, or -CH2CH2-. 1 and B 2 Each of these is independently, and more preferably, a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, -OCO-, or -OCOCH2CH2-.

[0069] From the viewpoint of exhibiting inverse 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. A symmetric structure is preferred when k = 2 and l = 2.

[0070] P 1 or P 2 Examples of polymerizable groups represented by include epoxy groups, vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, (meth)acryloyl groups, oxyranyl groups, and oxetanyl groups. Among these, (meth)acryloyl groups, vinyl groups, and vinyloxy groups are preferred, with (meth)acryloyl groups being more preferred.

[0071] It is preferable that Ar has at least one selected from an aromatic hydrocarbon ring which may have substituents, an aromatic heterocycle which may have substituents, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, etc., with benzene rings and naphthalene rings being preferred. 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, a pyrodazole ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenantholine ring, etc. Among these, it is preferable to have a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is even more preferable to have a benzothiazole ring. Furthermore, if Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

[0072] In formula (B1), the total number of π electrons possessed by the group represented by Ar is N. π It is usually 6 or more, 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 36 or less, more preferably 32 or less, even more preferably 26 or less, and particularly preferably 24 or less.

[0073] Examples of aromatic groups contained in Ar include the following groups:

[0074] [Chemical formula]

[0075] In formulas (Ar-1) to (Ar-23), the * mark represents a connecting portion, and 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 12 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. Also, Z 0 , Z 1 and Z 2 may contain a polymerizable group.

[0076] In formulas (Ar-1) to (Ar-23), Q 1 and Q 2 each independently represents -CR 2’ R 3’ -, -S-, -NH-, -NR 2’ -, -CO- or -O-, and R 2’ and R 3’ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0077] In formulas (Ar-1) to (Ar-23), J 1 and J 2 each independently represents a carbon atom or a nitrogen atom.

[0078] In formulas (Ar-1) to (Ar-23), Y 1 , Y 2 and Y 3 each independently represents an optionally substituted aromatic hydrocarbon group or an aromatic heterocyclic group.

[0079] In equations (Ar-1) to (Ar-23), W 1 and W 2 Each of these independently represents a hydrogen atom, a cyano group, a methyl group, or a halogen atom, and m represents an integer from 0 to 6.

[0080] Y 1 , Y 2 and Y 3 Examples of aromatic hydrocarbon groups in this context include C6-C20 aromatic hydrocarbon groups such as phenyl, naphthyl, anthuryl, phenanthuryl, and biphenyl groups, with phenyl and naphthyl groups being preferred and phenyl groups being more preferred. Examples of aromatic heterocyclic groups include C4-C20 aromatic heterocyclic groups containing at least one heteroatom such as a nitrogen atom, oxygen atom, or sulfur atom, such as furyl, pyrrolyl, thienyl, pyridinyl, thiazolyl, and benzothiazolyl groups, with furyl, thienyl, pyridinyl, thiazolyl, and benzothiazolyl groups being preferred.

[0081] Y 1 , Y 2 and Y 3 Each of these may independently be a substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. A polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. A polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

[0082] Z 0 , Z 1 and Z 2 Preferably, each of these is independently a hydrogen atom, a halogen atom, a C1-C12 alkyl group, a cyano group, a nitro group, or a C1-C12 alkoxy group, Z 0 A hydrogen atom, an alkyl group having 1 to 12 carbon atoms, and a cyano group are more preferably Z 1 and Z 2 Hydrogen atoms, fluorine atoms, chlorine atoms, methyl groups, and cyano groups are more preferred. Also, Z 0 , Z 1 and Z 2It may contain polymerizable groups.

[0083] Q 1 and Q 2 -NH-, -S-, -NR 2’ -, -O- is preferred, R 2’ A hydrogen atom is preferred. Among these, -S-, -O-, and -NH- are particularly preferred.

[0084] Among formulas (Ar-1) to (Ar-23), formulas (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

[0085] In equations (Ar-16) to (Ar-23), Y 1 This is the nitrogen atom and Z that it bonds to. 0 It may also form an aromatic heterocyclic group. Examples of aromatic heterocyclic groups that Ar may have include those mentioned above, such as a pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrazine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring, etc. This aromatic heterocyclic group may have substituents. Also, Y 1 This is the nitrogen atom and Z that it bonds to. 0 In addition, the aforementioned substituted polycyclic aromatic hydrocarbon groups or polycyclic aromatic heterocyclic groups may also be used. Examples include benzofuran rings, benzothiazole rings, and benzoxazole rings.

[0086] The compound represented by formula (B1) can be produced, for example, by the method described in Japanese Patent Publication No. 2010-31223.

[0087] The polymerizable liquid crystal composition for forming a phase difference layer (hereinafter also referred to as the "phase difference layer forming composition") may contain other polymerizable liquid crystal compounds other than the polymerizable liquid crystal compound for forming the phase difference layer, as long as the effects of the present invention are not impaired. When the phase difference layer forming composition contains two or more polymerizable liquid crystal compounds, from the viewpoint of obtaining a phase difference layer with excellent optical properties, it is preferable that at least one of them is a polymerizable liquid crystal compound for forming the phase difference layer, and all of the components contained in the phase difference layer forming composition may be polymerizable liquid crystal compounds for forming the phase difference layer.

[0088] The content of polymerizable liquid crystal compounds in the phase difference layer forming composition is preferably 60 to 99.9% by mass, more preferably 70 to 99.9% by mass, and even more preferably 80 to 99% by mass, relative to the solid content of the phase difference layer forming composition. When the content of polymerizable liquid crystal compounds is within the above range, the orientation of the polymerizable liquid crystal compounds tends to be high.

[0089] The phase difference layer forming composition may contain a polymerization initiator for initiating the polymerization reaction of a polymerizable liquid crystal compound. The polymerization initiator can be appropriately selected from those conventionally used in the field, and may be either a thermal polymerization initiator or a photopolymerization initiator, but a photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions.

[0090] As photopolymerization initiators, known photopolymerization initiators can be used. For example, photopolymerization initiators that generate active radicals include self-cleaving type photopolymerization initiators and hydrogen abstraction type photopolymerization initiators. Self-cleaving photopolymerization initiators include self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. In addition, hydrogen abstraction type photopolymerization initiators include hydrogen abstraction benzophenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosverone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, triazine compounds, etc.

[0091] Iodonium salts and sulfonium salts can be used as photopolymerization initiators that generate acid.

[0092] Examples of photopolymerization initiators include the following: Benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; Hydroxyacetophenone compounds such as oligomers of 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one; α-aminoacetophenone compounds such as 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one; Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl oxime); Acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; Benzophenone compounds such as benzophenone, o-methyl benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone; Dialkoxyacetophenone compounds such as diethoxyacetophenone; 2,4-Bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-Bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-Bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-Bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5- Triazine compounds such as lyazine, 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. The photopolymerization initiator can be appropriately selected from the above photopolymerization initiators in relation to the polymerizable liquid crystal compound contained in the polarizer-forming composition.

[0093] Alternatively, commercially available photopolymerization initiators may be used. Examples of commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, and 369, 379, 127, 754, OXE01, OXE02, OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, Esacure KIP160 (IDM Resins). Examples include: BV Corporation; Seikaol (registered trademark) BZ, Z, and BEE (manufactured by Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (manufactured by Dow Chemical Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arclus NCI-831, Adeka Arclus NCI-930 (manufactured by ADEKA Corporation); TAZ-A and TAZ-PP (manufactured by Nippon Siber Hegner Co., Ltd.); and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.).

[0094] The content of the polymerization initiator in the phase difference layer forming composition is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, even more preferably 2 to 8 parts by mass, and particularly preferably 4 to 8 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, the polymerization reaction of the polymerizable liquid crystal compound can be carried out without significantly disrupting the orientation of the polymerizable liquid crystal compound.

[0095] Furthermore, the phase difference layer forming composition may further contain a photosensitizer. The use of a photosensitizer can further accelerate the polymerization reaction of polymerizable liquid crystal compounds. Examples of photosensitizers include xanthone compounds such as xanthones and thioxanthones (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene); phenothiazines and rubrene. Photosensitizers can be used alone or in combination of two or more.

[0096] If the composition for forming a phase difference layer contains a photosensitizer, its content can be appropriately determined according to the type and amount of polymerization initiator and polymerizable liquid crystal compound, but 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 per 100 parts by mass of polymerizable liquid crystal compound.

[0097] Furthermore, the phase difference layer forming composition may also contain a leveling agent. The leveling agent has the function of adjusting the fluidity of the phase difference layer forming composition and making the coating film obtained by applying the phase difference layer forming composition flatter, and specifically, surfactants are examples. As the leveling agent, at least one selected from the group consisting of leveling agents mainly composed of polyacrylate compounds and leveling agents mainly composed of fluorine atom-containing compounds is preferred. Leveling agents can be used alone or in combination of two or more types.

[0098] Examples of leveling agents primarily composed of 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).

[0099] Examples of leveling agents whose main component is a fluorine atom-containing compound include "Megafac® 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® S-381", "S Examples include "-382", "S-383", "S-393", "SC-101", "SC-105", "KH-40", and "SA-100" (AGC Seimi Chemical Co., Ltd.); "E1830", "E5844" (Daikin Fine Chemical Laboratories, Inc.); "F-Top EF301", "F-Top EF303", "F-Top EF351", and "F-Top EF352" (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0100] When the composition for forming a phase difference layer contains a leveling agent, its content is preferably 0.05 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, it is easier to orient the polymerizable liquid crystal compound, and unevenness is less likely to occur, resulting in a tendency to obtain a smoother phase difference film.

[0101] The phase difference layer forming composition may contain additives other than photosensitizers and leveling agents. Examples of other additives include antioxidants, mold release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When the phase difference layer forming composition contains other additives, the content of the other additives is preferably more than 0% and 20% by mass or less, and more preferably more than 0% and 10% by mass or less, relative to the solid content of the phase difference layer forming composition.

[0102] The phase difference layer forming composition is prepared, for example, by mixing and stirring a polymerizable liquid crystal compound and, if necessary, a polymerization initiator, additives, etc. Furthermore, to improve coatability, a solvent may be added to the phase difference layer forming composition to adjust its viscosity.

[0103] The solvent used in the phase difference layer forming composition can be appropriately selected depending on the type of polymerizable liquid crystal compound used. Specifically, examples include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents can be used individually or in combination of two or more. The solvent content is preferably 100 to 1900 parts by mass, more preferably 150 to 900 parts by mass, and even more preferably 180 to 600 parts by mass, per 100 parts by mass of solid content of the phase difference layer forming composition.

[0104] A phase difference layer can be obtained by applying a phase difference film-forming composition onto a substrate or alignment film, removing the solvent by drying, and curing the polymerizable liquid crystal compound in the resulting coating film in an oriented state. The alignment film has an orientation-regulating force that causes the polymerizable liquid crystal compound to be liquid crystal-oriented in a desired direction, and a precisely oriented phase difference layer (cured layer) can be easily obtained by applying the phase difference film-forming composition onto the alignment film. Preferably, the alignment film has solvent resistance that prevents dissolution by application of the phase difference layer-forming composition, and also has heat resistance for solvent removal and heat treatment for aligning the polymerizable liquid crystal compound.

[0105] Examples of orientation films include orientation films containing orientation polymers, photo-alignment films, groove-alignment films having surface irregularities or multiple grooves, and stretched films stretched in the orientation direction. These various orientation films can be appropriately selected from those conventionally known in the field, depending on the desired orientation restricting force.

[0106] In one embodiment of the present invention, a photo-alignment film is preferred from the viewpoint of improving orientation accuracy and adhesion with the cured layer formed from the phase difference layer forming composition. The photo-alignment film is also advantageous in that the direction of the orientation restricting force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

[0107] Photo-alignment films are typically obtained by applying a composition containing a polymer, oligomer, or monomer having a photoreactive group and a solvent (hereinafter also referred to as the "photo-alignment film forming composition") onto a substrate or the like, and irradiating it with polarized light (preferably polarized UV). If the polymer or the like contained in the photo-alignment film forming composition has the same reactive group (for example, a (meth)acryloyl group) as the polymerizable group of the polymerizable liquid crystal compound that forms the polarized film, the adhesion between the cured layer of the polymerizable liquid crystal compound and the alignment film tends to improve.

[0108] A photoreactive group is a group that generates liquid crystal alignment ability upon light irradiation. Specifically, this includes groups involved in photoreactions that are the origin of liquid crystal alignment ability, such as molecular orientation induction or isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodegradation reactions, which are induced by light irradiation. Among these, groups involved in dimerization reactions or photocrosslinking reactions are preferred because they exhibit excellent orientation properties. As photoreactive groups, groups having unsaturated bonds, especially double bonds, are preferred, and groups having at least one selected from the group consisting of carbon-carbon double bonds (C=C bonds), carbon-nitrogen double bonds (C=N bonds), nitrogen-nitrogen double bonds (N=N bonds), and carbon-oxygen double bonds (C=O bonds) are particularly preferred.

[0109] Specifically, such alignment films can be photo-alignment films, such as those described in Japanese Patent Publication No. 2020-56834 and Japanese Patent Publication No. 2021-196514.

[0110] The thickness of the orientation film is preferably 10 to 3000 nm, more preferably 10 to 1000 nm, even more preferably 10 to 500 nm, even more preferably 10 to 300 nm, and particularly preferably 30 to 300 nm. When the thickness of the orientation film is within the above range, it is possible to exhibit orientation order force while maintaining good adhesion at the interface with the cured layer formed from the polarizing film-forming composition formed on the orientation film, thereby forming a polarizing film with high orientation order.

[0111] For example, a method for forming a phase difference film from a phase difference layer forming composition is: To form a coating film of a composition for forming a phase difference layer, Removing the solvent from the aforementioned coating film, The polymerizable liquid crystal compound is heated to a temperature above the temperature at which it undergoes a phase transition to the liquid phase, and then cooled to cause the polymerizable liquid crystal compound to undergo a phase transition to the liquid crystal phase (e.g., smectic liquid crystal phase), and Polymerizing a polymerizable liquid crystal compound while retaining the liquid crystal phase. It can be manufactured by a method that includes [a specific component].

[0112] The formation of a coating film of the phase difference layer forming composition can be carried out, for example, by applying the phase difference layer forming composition to a substrate or an alignment film. The substrate can be a layer constituting the composite polarizer of the present invention, but in one embodiment of the present invention, it is preferable that it is ultimately peeled off.

[0113] As the substrate, conventionally known resin film substrates in the field of optical films can be used. Specifically, examples of resins constituting such resin films include polyolefin resins such as polyethylene and polypropylene; cycloolefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; poly(meth)acrylic acid resins such as (meth)acrylic acid and poly(meth)acrylate methyl; cellulose ester resins such as triacetylcellulose, diacetylcellulose, and cellulose acetate propionate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate resins; polystyrene resins; polyarylate resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyetherketone resins; polyphenylene sulfide resins; polyphenylene oxide resins, and mixtures thereof. These may be used individually or in combination of two or more. Such resins can be formed into resin film substrates by known means such as solvent casting and melt extrusion. Furthermore, commercially available products may be used as the film substrate or the resin constituting the film substrate. The film substrate may be subjected to surface treatments such as corona treatment or plasma treatment, and release treatments if the substrate is to be peeled off later. The thickness of the substrate is not particularly limited and can be selected appropriately within a practical range. For example, it can be around 5 μm to 300 μm.

[0114] The method for applying the phase difference layer formation composition is not particularly limited, and known methods such as spin coating, extrusion, gravure coating, die coating, bar coating, applicator coating, and printing methods such as flexographic coating can be employed.

[0115] If the composition for forming the phase difference layer contains a solvent, the solvent is usually removed from the applied composition. Methods for removing the solvent include natural drying, forced-air drying, heat drying, and vacuum drying. Preferably, the dried film is dried so that the residual solvent in the phase difference layer is 1% by weight or less of the total mass of the phase difference layer. The amount of residual solvent can be quantified by peeling the phase difference film from the substrate, weighing it, immersing the phase difference film in a solvent that dissolves polarizing films such as tetrahydrofuran, irradiating it with ultrasound for about 10 minutes to extract the dissolved components, and then analyzing this solution by gas chromatography. Each condition, such as drying temperature and drying time, can be appropriately determined depending on the composition of the phase difference layer forming composition, the materials of the substrate and orientation film, etc.

[0116] Polymerizable liquid crystal compounds in a coating film are typically heated above the temperature at which they transition to a liquid crystal state or solution state, and then cooled to the temperature at which they become liquid crystal oriented, thereby orienting and forming a liquid crystal phase.

[0117] The temperature at which the polymerizable liquid crystal compound in the coating film aligns can be determined in advance by observing the texture of a composition containing the polymerizable liquid crystal compound. Alternatively, solvent removal and liquid crystal orientation may be performed simultaneously. The temperature for this process depends on the solvent to be removed and the type of polymerizable liquid crystal compound used, but is preferably in the range of 50 to 200°C, and more preferably in the range of 80 to 130°C.

[0118] A phase difference film is formed as a cured layer of the liquid crystal composition by polymerizing and curing the polymerizable liquid crystal compound while maintaining its liquid crystal state. Photopolymerization is preferred as the polymerization method. In photopolymerization, the light irradiated onto the dried film is appropriately selected according to the type of polymerizable liquid crystal compound contained in the dried film (particularly the type of polymerizable group the polymerizable liquid crystal compound has), the type of polymerization initiator, and their amounts.

[0119] In a preferred embodiment of the present invention, the composite polarizing plate further includes a positive C plate (nx≈ny < nz) on the side opposite to the surface of the above-mentioned retardation layer A adjacent to the above-mentioned adhesive layer. When further including a retardation layer that is a positive C plate, it is preferable from the viewpoint of hue compensation in the diagonal direction.

[0120] (Other layers) The composite polarizing plate of the present invention may further have other layers other than the above. Examples of the other layers include an antireflection layer, a UV absorption layer, an anti-diffusion layer, a stress relaxation layer, a color compensation layer, a hard coat layer, and the like.

[0121] A high optical performance can be expected for the composite polarizing plate manufactured by the manufacturing method of the present invention. Therefore, the composite polarizing plate of the present invention is suitable as a component of various display devices. A display device is a device having a display element and includes a light-emitting element or a light-emitting device as a light source. Examples of the display device include a liquid crystal display device, an organic electro-luminescence (EL) display device, an inorganic electro-luminescence (EL) display device, a touch panel display device, an electron emission display device (for example, a field emission display device (FED), a surface field emission display device (SED)), an electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection display device (for example, a grating light valve (GLV) display device, a display device having a digital micromirror device (DMD)), and a piezoelectric ceramic display. The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device. These display devices may be display devices for displaying a two-dimensional image or may be stereoscopic display devices for displaying a three-dimensional image. In particular, the composite polarizing plate of the present invention is also suitable for applications to VR display devices and AR display devices that require high optical characteristics.

Examples

[0122] 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. Hereinafter, parts and percentages representing usage amounts and content are based on mass unless otherwise specified.

[0123] <Measurement> [thickness] The thickness of the layers or films was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) or a digital micrometer (MH-15M, manufactured by Nikon Corporation).

[0124] [Storage modulus of the adhesive layer] Multiple adhesive layers were stacked to a thickness of 0.2 mm (measured with a digital micrometer ("MH-15M" manufactured by Nikon Corporation)). A cylindrical body with a diameter of 8 mm was punched out and used as a measurement sample. The storage modulus G' [kPa] of this measurement sample was measured using the torsional shear method with a viscoelasticity measuring device ("MCR300" manufactured by Physica Corporation) in accordance with JIS K7244-6, under the following conditions. [Measurement conditions] Normal Force FN:1N Distortion γ: 1% Frequency: 1Hz Temperature: 25℃

[0125] [Martens hardness test] To measure the Mertens hardness of the adhesive of the protective film, a Fischer Instruments microhardness tester, FISCHERSCOPE® HM2000, was used. A COP film (3 μm thick) was attached to the adhesive surface of the protective film as a cover substrate for measurement, and an indentation test was performed by pressing down on it with an indenter. "Measurement conditions supplemented." The average of three measurements was taken as the Mertens hardness.

[0126] [Procurement of polarizing plates] As a polarizing plate, a commercially available reflective polarizing plate manufactured by 3M is used. TM Brightness-enhancing film (APF) was procured and used.

[0127] [Preparation of the adhesive layer] A 5 μm thick (meth)acrylic adhesive layer was prepared as the adhesive layer using the following process. In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube, 95.0 parts by mass of n-butyl acrylate, 4.0 parts by mass of acrylic acid, 1.0 part by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. Under a nitrogen atmosphere, the reaction solution was heated to 60°C while stirring and reacted for 6 hours, after which it was cooled to room temperature. When the weight-average molecular weight of a portion of the obtained solution was measured, the formation of a (meth)acrylic acid ester polymer with a molecular weight of 1.8 million was confirmed. 100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth)acrylic acid ester polymer obtained in the above process, 1.5 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate® L") as an isocyanate-based crosslinking agent, 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") as a silane coupling agent, 7.5 parts by mass of ethoxylated isocyanuric acid triacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., product name "A-9300") as an ultraviolet-curable compound, and 0.5 parts by mass of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by BASF, Irgacure® 907) as a photopolymerization initiator were mixed, stirred thoroughly, and diluted with ethyl acetate to obtain a coating solution of the adhesive composition. The coating solution was applied to the release surface (release layer surface) of a separator (Lintec Corporation: SP-PLR382190) using an applicator so that the thickness after drying would be 5 μm. After drying at 100°C for 1 minute, another separator (Lintec Corporation: SP-PLR381031) was bonded to the side of the adhesive layer opposite to the side to which the separator was bonded. Ultraviolet light (irradiation intensity 500 mW / cm²) was applied to this adhesive layer through the release sheet using an ultraviolet irradiation device with a belt conveyor (Fusion UV Systems, using a D-bulb lamp). 2 , cumulative light intensity 500 mJ / cm2 The adhesive layer with double-sided separators was obtained by irradiating it with ). The storage modulus G' of the adhesive layer at a temperature of 25°C was 106 kPa.

[0128] [Preparation of a composition for forming a phase difference layer] A composition for forming a phase difference layer was obtained by mixing the following components and stirring at 80°C for 1 hour. ·Polymerizable liquid crystal compound: Compound (A11-1) [ka] Compound (x-1) [ka] • Polymerization initiator: 2-Dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure® 369; manufactured by BASF Japan)...8 parts • Leveling agent: Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) ... 0.1 part • Other additives: LALOMER LR9000 (manufactured by BASF Japan)... 6.7 liters ·solvent: Cyclopentanone... 546 copies N-methylpyrrolidone... 364 copies

[0129] [Preparation of compositions for photoalignment film formation] A composition for forming a photo-aligned film was obtained by mixing the following components described in Japanese Patent Publication No. 2013-033249 and stirring the resulting mixture at 80°C for 1 hour. • Photo-oriented polymers: [ka] …2 parts • Solvent: o-xylene...98 parts

[0130] A roll of release polyethylene terephthalate (PET) film with a film width of 800 mm (Unitika Ltd. "FF-50", single-sided release-treated PET film, support substrate thickness: 50 μm) was subjected to corona treatment on the surface opposite the release-treated side. Then, the above-mentioned photo-alignment film layer forming composition was applied to a 600 mm wide area in the center of the film using a slot die coater. The resulting coated film was dried at 120°C for 2 minutes, then cooled to room temperature to form a first dried film. Subsequently, polarized ultraviolet light was applied at 100 mJ / cm² such that the direction of the orientation restricting force was at an angle of 0° with respect to the transport direction (long direction) of the long film. 2 Irradiation (based on 313 nm) was performed to form a long photo-alignment layer. The thickness of the photo-alignment film was 50 nm.

[0131] On this photo-alignment layer, the above-mentioned phase difference layer forming composition was applied to a 600 mm wide area in the center of the film using a slot die coater to form a coated film layer. After heating and drying this coated film layer at 120°C for 2 minutes, it was cooled to room temperature and exposed to ultraviolet light at an exposure dose of 1000 mJ / cm². 2 A phase difference layer was formed by irradiating the dried film layer with ultraviolet light (based on 365 nm). The thickness of the phase difference layer was 2.1 μm. This resulted in obtaining a long phase difference film having a release PET film, a photo-alignment layer, and a phase difference layer in that order.

[0132] [Special annealing process for polarizing plates] To reduce surface waviness of the polarizing plates, the polarizing plates obtained as described above were subjected to a special annealing treatment according to the conditions shown in Table 1. A polarizing plate that was not subjected to the special annealing treatment was designated as Comparative Example 1.

[0133] [Table 1]

[0134] [Protective film during annealing] A protective film, consisting of a PET film coated with an acrylic adhesive, was used to attach to a polarizing plate during annealing. A protective film was prepared by coating a 75 μm PET film with 43 μm of acrylic adhesive, and this was designated as protective film A. Another protective film was prepared by coating a 38 μm PET film with 15 μm of acrylic adhesive, and this was designated as protective film B. The Martens hardness of the acrylic adhesive layer of protective film A was 3.1 N / mm, and the Martens hardness of the acrylic adhesive layer of protective film B was 9.7 N / mm.

[0135] Regarding the "protective film" in Table 1 above, in the examples and comparative examples marked with "-", annealing was performed without attaching anything to both sides of the polarizing plate. In the examples marked with "one side", nothing was attached to one side of the polarizing plate, and a protective film was attached to the other side before annealing. In the examples and comparative examples marked with "both sides", protective film was attached to both sides of the polarizing plate before annealing.

[0136] Regarding the "Type of protective film" in Table 1 above, protective film A was used where "A" was indicated, and protective film B was used where "B" was indicated. For example, where "A / A" was indicated, annealing was performed with the adhesive side of protective film A attached to both sides of the polarizing plate.

[0137] [Annealing process] The annealing process was carried out by placing polarizing plates into a constant-temperature bath preheated to the "annealing bath temperature" shown in Table 1 for the time indicated as "annealing time" in Table 1. Two annealing methods were used, as described in Table 1. Method A: A polarizing plate was cut to 200 x 150 mm, and double clips were attached to two points on the upper edge of the longer side. This was then hung on a hook installed in the upper part of a constant temperature bath and annealed. Method B: A polarizing plate was cut to 200 x 150 mm, layered alternately with A4-sized clean paper, secured with binder clips, and placed on the floor of a constant temperature bath for annealing. The polarizing plates (reflective POL) obtained after annealing were named according to the "Film No." in Table 1, depending on the conditions ((1)~(10)). The thickness of the obtained polarizing plates was 62 μm.

[0138] [Fabrication of composite polarizing plates] A composite polarizer was fabricated by laminating a polarizer that had been annealed using the method described above, or a polarizer that had not been annealed, with the phase difference film via an adhesive layer. In this process, the lamination was carried out so that the reflection axis of the polarizer and the slow phase axis of the phase difference film were relative axes of 45°. This resulted in obtaining composite polarizers containing polarizers annealed under different conditions. For the obtained composite polarizers, S slope Measurements, optical properties, and appearance quality evaluations were performed.

[0139] [S slope [Measurement and calculation] As an index for evaluating the surface uniformity of the composite polarizing plate fabricated as described above, the root mean square slope (S) was calculated in μrad format using λc = 250 μm and λf = 3000 μm as cutoff values ​​for the height profile of the surface of the polarizing plate adjacent to the adhesive layer. slope ) was measured. S slope This was calculated from the height profile obtained using a non-contact surface and layer cross-sectional shape measurement system (Ryoka Systems Co., Ltd. "VertScan") as follows. (Operation in Vertscan) (1) The shape of the polarizing plate surface of the composite polarizer is measured in a 10 × 10 mm area using VertScan, and "planar correction" and "cutoff values ​​λc = 250 μm and λf = 3000 μm" are performed within the device. (2) From the obtained shape, the height profile in the vertical direction (z direction) perpendicular to the plane is extracted as an Excel file. (Operations within a Python program) (1) Read the height profile obtained as described above, define it as a data frame, and store it. (2) Set the number of steps you want to divide in the width direction (here, we set it to 1000 steps). (3) In each divided interval, the polyfit function is used to fit a linear polynomial and calculate its slope. (4) Store the calculated slope for each interval in a data frame and return the data frame with the calculated slope. In this case, the slope is taken as an absolute value and converted to μrad format. (5) A list of calculated slopes in μrad format is returned, and the average value of the slopes in μrad format is taken from this list and given as S slope Let's assume that. In this embodiment, Vertscan and a Python program are used to calculate the root mean square slope S slope Although the above cutoff value was calculated, it is also possible to calculate the Waviness value using, for example, a white light interferometer manufactured by Zygo, using the above cutoff value.

[0140] [Optical properties evaluation] For the evaluation of the optical properties of the composite polarizer, a reflective polarizer was used, and therefore the projected image was evaluated using the reflection projection method. If an absorptive polarizer were used, the projected image using transmitted light may also be evaluated. The reflective polarizer side of a composite polarizer plate was bonded to alkali-free glass (700 μm thick) via a pressure-sensitive adhesive. With the non-glass side facing outwards, S-Light SA160 (manufactured by Japan Technical Center Co., Ltd.) was shone onto the composite polarizer plate at a 5-degree angle. A screen projecting the reflected light was placed opposite, and the shadows of the projected image were observed. The accuracy of the reflection was evaluated on a 4-point scale from A to D based on the appearance of these shadows. The evaluation results are shown in Table 1. A is the best evaluation result. Figure 3 shows the images of the composite polarizer plate of Example 1, which received an evaluation result of A, and the composite polarizer plate of Comparative Example 1, which received an evaluation result of C. For example, when using a composite polarizer plate including a reflective polarizer plate in a display device such as a VR display device or an AR display device, the reflected light that projects the image is visible, so it is considered that uniformity of the image will result in a clearer image when viewed on the above-mentioned display device.

[0141] [Appearance Quality Evaluation] The resulting composite polarizers, as well as the visual quality of each composite polarizer, were observed and evaluated according to the following criteria. The evaluation results are shown in Table 1. A: No wrinkles or cracks, and no foreign matter attached. B: Slight wrinkles are visible, and a small amount of foreign matter is attached. C: Wrinkles and / or cracks are present within the plane. D: Significant wrinkles and / or cracks occur within the plane, rendering it unusable as a composite polarizer.

Claims

1. A method for manufacturing a composite polarizing plate, comprising a polarizing plate, an adhesive layer, and a phase difference layer adjacent to each other in this order, (a) A step of preparing an untreated polarizing plate, (b) A step of obtaining a polarizing plate by annealing an untreated polarizing plate, and (c) A process of laminating the polarizing plate, adhesive layer and phase difference layer in this order. A method for manufacturing a composite polarizing plate, comprising at least [a certain element].

2. The manufacturing method according to claim 1, wherein the annealing treatment is performed by heating an untreated polarizing plate while it is held in the air.

3. The manufacturing method according to claim 2, wherein the heating temperature in the annealing process is 60 to 150°C.

4. The manufacturing method according to claim 1, wherein the untreated polarizing plate has no protective film, or has a protective film on at least one surface, and if it has a protective film, the protective film is bonded to the untreated polarizing plate via an adhesive layer having a Martens hardness of 5 N or less.

5. The manufacturing method according to claim 4, wherein, when the untreated polarizing plate has a protective film, the thickness of the adhesive layer between the untreated polarizing plate and the protective film is 5 to 50 μm.

6. The manufacturing method according to claim 1, wherein the annealing treatment is performed by heating an untreated polarizing plate while it is suspended in mid-air.

7. The manufacturing method according to claim 1, wherein the annealing treatment is performed by heating two or more untreated polarizing plates while they are held in the air spaced apart from each other, or by heating two or more untreated polarizing plates while they are held in the air with a spacer in between.

Images