Composite polarizing plate

Abstract

To provide a composite polarizing plate which hardly causes peeling and wrinkling between a reflective polarizing plate and an absorptive polarizer even when heat treated at high temperature.SOLUTION: A composite polarizing plate is provided, comprising a reflective polarizing plate, an adhesive layer 1, and an absorptive polarizer arranged in the described order, the reflective polarizing plate being a stretched film, and the absorptive polarizer being a cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic pigment, and the adhesive layer 1 having an elastic modulus of 20 to 600 kPa at 25°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composite polarizing plate. [Background technology]

[0002] Conventionally, a composite polarizing plate has been known, which is formed by laminating, via a pressure-sensitive adhesive layer, a reflective polarizing plate having a multilayer structure of polymeric materials with different in-plane birefringence obtained by stretching and an iodine PVA polarizing plate or an absorptive polarizer formed from a composition containing a dichroic dye. For example, Patent Document 1 discloses that a thin, high-performance liquid crystal display device can be manufactured by placing such a composite polarizing plate between a backlight unit and a liquid crystal cell of a liquid crystal display device, with the reflective polarizer surface on the backlight unit side and the absorptive polarizer surface on the liquid crystal cell side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-124467 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been found that when a composite polarizing plate laminated with a reflective polarizing plate made of a stretched film and an absorptive polarizer formed from a composition containing a dichroic dye is heat-treated at a high temperature (e.g., 120°C or higher), peeling or wrinkles may occur between the reflective polarizing plate and the absorptive polarizer. An object of the present invention is to provide a composite polarizing plate that is less likely to peel or wrinkle between a reflective polarizing plate and an absorptive polarizer even when heated at high temperatures. [Means for solving the problem]

[0005] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention includes the following aspects. [1] A composite polarizing plate including a reflective polarizing plate, a pressure-sensitive adhesive layer 1, and an absorptive polarizer in this order, the reflective polarizing plate is a stretched film, the absorptive polarizer is a cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, The composite polarizing plate has a modulus of elasticity at 25°C of 20 to 600 kPa. [2] The composite polarizing plate according to [1] above, wherein the pressure-sensitive adhesive layer 1 has a modulus of elasticity per unit thickness at 25° C. of 1 to 30 kPa / μm. [3] The composite polarizing plate according to [1] or [2] above, which has an optical film on the surface of the absorptive polarizer opposite to the pressure-sensitive adhesive layer 1 via a pressure-sensitive adhesive layer. [4] The composite polarizing plate according to [3] above, wherein the adhesive layer is an adhesive layer. [5] The composite polarizing plate according to [3] or [4] above, wherein the optical film is a thermoplastic resin film. [6] The composite polarizing plate according to any one of the above [3] to [5], wherein the optical film is a thermoplastic resin film having a glass transition temperature of 80 to 180°C. [7] The composite polarizing plate according to any one of [3] to [6] above, wherein the optical film has a thickness of 10 to 90 μm. [8] The composite polarizing plate according to any one of [1] to [7] above, for use in a VR display device. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a composite polarizing plate in which peeling or wrinkling is unlikely to occur between the reflective polarizing plate and the absorptive polarizer even when heated at high temperatures. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view showing an example of a layer structure of a composite polarizing plate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0009] The composite polarizing plate of the present invention includes a reflective polarizing plate, a pressure-sensitive adhesive layer 1, and an absorptive polarizer, in this order. The reflective polarizing plate is a stretched film, and the absorptive polarizer is a cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye. Hereinafter, an example of the layer structure of the composite polarizing plate of the present invention will be described with reference to FIG. 1, but the composite polarizing plate of the present invention is not limited to these embodiments.

[0010] The composite polarizing plate 11 shown in FIG. 1 is formed by laminating a reflective polarizing plate 1, a pressure-sensitive adhesive layer 2, and an absorptive polarizer 3 in this order. In the optical laminate 11 shown in FIG. 1, the absorptive polarizer 3 has anti-diffusion layers 4 on both sides thereof. The absorptive polarizer 3 may be formed on an alignment film 5. If an alignment film 5 is included, the alignment film may be located on the reflective polarizing plate side or the opposite side. In FIG. 1, the absorptive polarizer 3 and the anti-diffusion layers 4 and alignment films 5 located on both sides thereof form an absorptive polarizing plate 12. In the composite polarizing plate 11, the absorptive polarizing plate 12 is laminated to an optical film 7 via a pressure-sensitive adhesive layer 6. Hereinafter, in this specification, a laminate including an absorptive polarizer and, if necessary, an alignment film and / or an anti-diffusion layer will be referred to as an absorptive polarizing plate.

[0011] In addition to the reflective polarizing plate, adhesive layer 1 and absorptive polarizer, anti-diffusion layer, alignment film, adhesive layer and optical film shown in Figure 1, the composite polarizing plate of the present invention may further include other layers as long as they do not affect the effects of the present invention.

[0012] <Adhesive layer 1> In the composite polarizing plate of the present invention, the pressure-sensitive adhesive layer 1 located between the reflective polarizing plate and the absorptive polarizing plate has an elastic modulus of 20 to 600 kPa at 25°C. When the elastic modulus of the pressure-sensitive adhesive layer 1 is within this range, peeling or wrinkling is unlikely to occur between the reflective polarizing plate and the absorptive polarizing plate when the composite polarizing plate is heat-treated at a high temperature, for example, around 140°C. When used in conventional flat panel display devices, the composite polarizing plate after laminating the reflective polarizing plate and the absorptive polarizing plate is not usually heat-treated at a high temperature. Therefore, heat resistance when exposed to temperatures as high as 140°C or higher is not necessarily required. Meanwhile, for example, in head-mounted displays and AR glasses used in VR (Virtual Reality) and AR (Augmented Reality) technologies, which have been developing rapidly in recent years, there is a demand for technology that widens the viewing angle to provide a high sense of immersion and presence. According to the present inventors, a composite polarizing plate formed by laminating a reflective polarizing plate and an absorptive polarizing plate can improve the viewing angle when combined with a lens and used in VR or AR devices. However, for use as a display for VR or AR devices, a composite polarizing plate formed by laminating a reflective polarizing plate and an absorptive polarizing plate typically needs to be molded under high-temperature heating to fit a lens shape, such as a plano-convex shape. Under such high-temperature heating, conventional composite polarizing plates used as displays for flat panel display devices can experience peeling or wrinkles between the reflective polarizing plate and the absorptive polarizing plate due to heat treatment. The present inventors have discovered that one of the causes of this is the significant difference in the thermal dimensional change behavior between the reflective polarizing plate and the absorptive polarizing plate (absorptive polarizer), although this is not necessarily limited to this. In the composite polarizing plate of the present invention, a relatively soft pressure-sensitive adhesive layer 1 having the above-mentioned elastic modulus is located between the reflective polarizing plate and the absorptive polarizing plate. Therefore, even if a difference in the dimensional change rate between the reflective polarizing plate and the absorptive polarizing plate occurs due to high-temperature heating, this difference can be absorbed by the pressure-sensitive adhesive layer 1.This makes it possible to obtain a composite polarizing plate that is excellent in the effect of suppressing peeling and wrinkles between the reflective polarizing plate and the absorptive polarizing plate even under high-temperature heat treatment, and that has excellent formability even when processed at high temperatures to conform to the shape of, for example, a plano-convex lens, etc., and can be processed into a desired shape without generating cracks, etc. From the viewpoint of further enhancing the effects of the present invention, the elastic modulus (25°C) of the pressure-sensitive adhesive layer 1 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. In the following, the effect of suppressing peeling and wrinkles between the reflective polarizer and the absorptive polarizer under high-temperature heating treatment will be referred to as the high-temperature heat resistance effect, and the effect of high moldability under high-temperature heating will be referred to as high-temperature moldability.

[0013] The elastic modulus of the pressure-sensitive adhesive layer 1 can be measured using a viscoelasticity measuring device. In detail, it can be measured by the method described in the examples below, for example.

[0014] The elastic modulus per unit film thickness of the pressure-sensitive adhesive layer 1 at 25°C is preferably 1 to 30 kPa / μm. When the elastic modulus per unit film thickness is within this range, peeling and wrinkle suppression effects between the reflective polarizing plate and the absorptive polarizing plate during high-temperature heating and high-temperature formability can be improved. From the viewpoint of further enhancing these effects, the elastic modulus per unit film thickness of the pressure-sensitive adhesive layer 1 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 pressure-sensitive adhesive layer 1 can be calculated from the elastic modulus of the pressure-sensitive adhesive layer 1 and the thickness of the pressure-sensitive adhesive layer 1 as follows. Elastic modulus per unit film thickness (kPa / μm) = Elastic modulus (kPa) / Thickness (μm)

[0015] The thickness of the pressure-sensitive adhesive layer 1 may be appropriately determined depending on the configuration of the pressure-sensitive adhesive layer 1, the configuration of the layer adjacent to the pressure-sensitive adhesive layer 1, etc. From the viewpoint of easy control of the elastic modulus, the effect of suppressing peeling and wrinkle formation in the composite polarizing plate, and / or high-temperature formability, the thickness 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 pressure-sensitive adhesive layer 1 can be measured using a laser microscope, a film thickness meter, or the like, and the same applies to the measurement of the thickness of each layer or film of the reflective polarizing plate, absorptive polarizer, etc. that constitute the composite polarizing plate.

[0016] The elastic modulus of the pressure-sensitive adhesive layer 1 can be controlled by the types of components constituting it, their content ratios, thickness, etc. The pressure-sensitive adhesive layer 1 is a layer capable of adhering a reflective polarizing plate to an absorptive polarizing plate equipped with an absorptive polarizer, and can be prepared using materials conventionally known in the art. Examples include pressure-sensitive adhesive compositions containing resins such as (meth)acrylic, rubber, urethane, ester, silicone, and polyvinyl ether as the main component. Among these, from the viewpoint of excellent transparency, adhesiveness, weather resistance, heat resistance, etc., the pressure-sensitive adhesive layer 1 is preferably formed from a pressure-sensitive adhesive composition containing a (meth)acrylic resin as the base polymer.

[0017] The adhesive composition may be an active energy ray-curable adhesive, a thermosetting adhesive, or the like. Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition forming the adhesive layer 1 include polymers or copolymers containing one or more (meth)acrylic acid esters as monomer components, 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. The (meth)acrylic resin may also be copolymerized with a polar monomer. Examples of polar monomers include monomers having a carboxylic acid group, a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0018] In one embodiment of the present invention, the structural units derived from (meth)acrylic acid esters in the (meth)acrylic resin constituting the pressure-sensitive adhesive composition preferably account for 80 to 100 mass %, more preferably 85 mass % or more, and even more preferably 90 mass % or more of the total mass of all structural units constituting the (meth)acrylic resin. Furthermore, when the (meth)acrylic resin contains structural units derived from polar monomers, the structural units derived from the polar monomers preferably account for 0.1 to 10 mass %, more preferably 0.5 mass % or more, even more preferably 1 mass % or more, and even more preferably 8 mass % or less of the total mass of all structural units constituting the (meth)acrylic resin.

[0019] The weight-average molecular weight (hereinafter also simply referred to as "Mw") of the (meth)acrylic resin is preferably 500,000 to 2,500,000. When the weight-average molecular weight is 500,000 or more, the durability of the pressure-sensitive adhesive layer 1 in high-temperature, high-humidity environments can be improved. When the weight-average molecular weight is 2,500,000 or less, the operability when applying the pressure-sensitive adhesive composition is improved. The molecular weight distribution (Mw / Mn), which is 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 2 to 10. In this specification, the weight-average molecular weight and number-average molecular weight are polystyrene-equivalent values ​​measured by gel permeation chromatography (GPC).

[0020] (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 usually used in the production of this (meth)acrylic resin. The content of the polymerization initiator is preferably 0.001 to 5 parts by mass relative to 100 parts by mass of the total of all monomers used in the production of the (meth)acrylic resin.

[0021] The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator. Examples of the thermal polymerization initiator include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 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 suitable peroxides include organic peroxides such as 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 suitable photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone.

[0022] When preparing a (meth)acrylic resin by solution polymerization, for example, a method can be used in which the desired monomers and an 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. To control the reaction, the monomers and polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a dissolved state in an organic solvent. Examples of organic solvents that can be used include 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; and ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0023] The pressure-sensitive adhesive composition may contain only the (meth)acrylic resin, or may contain a crosslinking agent in combination. Examples of crosslinking agents include divalent or higher metal ions that form metal carboxylates with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; polyepoxy compounds or polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are preferred from the viewpoints of crosslinking speed, durability, etc.

[0024] When a crosslinking agent is contained, the proportion thereof 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, relative to 100 parts by mass of the base polymer.

[0025] The pressure-sensitive adhesive composition may further contain a silane compound, if necessary. The inclusion of a silane compound can enhance the adhesion between the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive and the layer to be laminated. 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 compounds may be used alone or in combination of two or more.

[0026] When a silane compound is contained, the content thereof 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.

[0027] In this specification, the active energy ray-curable pressure-sensitive adhesive refers to a pressure-sensitive adhesive that has the property of being cured when irradiated with active energy rays such as ultraviolet rays or electron beams, that has adhesiveness even before irradiation with active energy rays and can be adhered to an adherend, and that is cured by irradiation with active energy rays and has the property of being able to adjust adhesion strength, etc. The active energy ray-curable pressure-sensitive adhesive is preferably an ultraviolet ray-curable pressure-sensitive adhesive.

[0028] The active energy ray-curable pressure-sensitive adhesive generally contains an energy ray-polymerizable compound in addition to a base polymer such as the (meth)acrylic resin and a crosslinking agent as described above, and may further contain a photopolymerization initiator, a photosensitizer, etc., as necessary.

[0029] Examples of the active energy ray-polymerizable compound include (meth)acrylic compounds such as (meth)acrylate monomers having at least one (meth)acryloyloxy group in the molecule; and (meth)acryloyloxy group-containing compounds such as (meth)acrylate oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyloxy groups in the molecule.

[0030] The PSA composition may further contain components commonly used in PSA compositions, such as resins other than the base polymer, tackifiers, fillers (metal powders and other inorganic powders, etc.), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, and corrosion inhibitors.

[0031] In one embodiment of the present invention, the pressure-sensitive adhesive layer 1 may be composed of a reaction product of a pressure-sensitive adhesive composition containing a base polymer such as the above-mentioned (meth)acrylic resin, a crosslinking agent, and a silane compound. Such a pressure-sensitive adhesive layer 1 can be formed by applying, for example, an organic solvent-diluted solution of the pressure-sensitive adhesive composition containing the above components to a surface on which the pressure-sensitive adhesive layer 1 is to be formed, and then drying the applied solution.

[0032] In one embodiment of the present invention, the pressure-sensitive adhesive layer 1 is more preferably a layer formed from an active energy ray-curable pressure-sensitive adhesive. When the pressure-sensitive adhesive layer 1 is formed from an active energy ray-curable pressure-sensitive adhesive, for example, a pressure-sensitive adhesive composition containing the components described above, for example, a diluted solution in an organic solvent, is applied to the surface on which the pressure-sensitive adhesive layer 1 is to be formed, and the pressure-sensitive adhesive layer formed by drying is irradiated with active energy rays to form a cured product layer having a desired degree of curing.

[0033] <Absorptive polarizer> In the present invention, the absorptive polarizing plate includes an absorptive polarizer, which is a cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye. In the present invention, the polarizing layer is a layer having a polarizing function (polarizer). The polarizing layer contains a dichroic dye, which is a dye having absorption anisotropy. From the viewpoint of being advantageous for thinning the optical laminate, the polarizing layer in the optical laminate of the present invention is preferably a coating layer, and is a cured layer formed from a polymerizable liquid crystal composition (hereinafter also referred to as a "polarizing layer-forming composition") containing at least one liquid crystal compound, preferably a polymerizable liquid crystal compound and a dichroic dye.

[0034] The polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound (A)") contained in the composition for forming an absorptive polarizer (hereinafter also referred to as "polarizer-forming composition") is a compound having at least one polymerizable group. Here, the polymerizable group refers to a group that can be involved in a polymerization reaction by an active radical generated from a polymerization initiator, an acid, or the like. Examples of the polymerizable group contained in the polymerizable liquid crystal compound (A) include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth)acryloyl group, an oxiranyl group, and an oxetanyl group. Among these, a radically polymerizable group is preferred, a (meth)acryloyl group, a vinyl group, or a vinyloxy group is more preferred, and a (meth)acryloyl group is even more preferred. When the polymerizable liquid crystal compound that forms the absorptive polarizer has the same functional group (polymerizable group), such as a (meth)acryloyl group, as the functional group possessed by the compound that forms the alignment film for forming the absorptive polarizer described below, the compatibility between the alignment film and the absorptive polarizer is high, and excellent adhesion between the layers can be achieved.

[0035] The liquid crystallinity of the polymerizable liquid crystal compound (A) may be thermotropic or lyotropic, but thermotropic liquid crystal is preferred from the viewpoint of mixing with a dichroic dye, which will be described later. When the polymerizable liquid crystal compound (A) is a thermotropic liquid crystal, it may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase or a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. When a polarizing function is exhibited as a cured film by a polymerization reaction, the polymerizable liquid crystal compound (A) is preferably a compound exhibiting smectic liquid crystallinity. By using a polymerizable liquid crystal compound (A) exhibiting smectic liquid crystallinity, a polarizing layer with a high degree of orientational order can be formed. From the viewpoint of achieving a higher degree of orientational order, the liquid crystal state exhibited by the polymerizable liquid crystal compound (A) is more preferably a high-order smectic phase (high-order smectic liquid crystal state). Here, the higher-order smectic phase refers to a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, and a smectic L phase, and among these, a smectic B phase, a smectic F phase, and a smectic I phase are more preferred. The liquid crystal property may be a thermotropic liquid crystal or a lyotropic liquid crystal, but a thermotropic liquid crystal is preferred because it allows precise control of the film thickness. In addition, the polymerizable liquid crystal compound (A) may be a monomer, or may be an oligomer or polymer in which a polymerizable group is polymerized.

[0036] The polymerizable liquid crystal compound (A) is not particularly limited as long as it is a liquid crystal compound having at least one polymerizable group, and known polymerizable liquid crystal compounds can be used. Examples of such polymerizable liquid crystal compounds include a compound represented by the following formula (A1) (hereinafter, sometimes referred to as "polymerizable liquid crystal compound (A1)"). U 1 -V 1 -W 1 -(X 1 -Y 1 ) n -X 2 -W 2 -V 2 -U 2 (A1) [In formula (A1), X 1 and X 2 are each independently a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom, provided that X 1 and X 2 At least one of the groups is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group. Y 1 is a single bond or a divalent linking group. n is 1 to 3, and when n is 2 or more, multiple X 1 may be the same or different. 2 Multiple X 1 In addition, when n is 2 or more, a plurality of Y 1 may be the same or different. From the viewpoint of liquid crystal properties, n is preferably 2 or more. U 1 represents a hydrogen atom or a polymerizable group. U 2 represents a polymerizable group. W 1 and W 2 are each independently a single bond or a divalent linking group. V 1 and V 2 represent each independently an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH2- constituting the alkanediyl group may be replaced by -O-, -CO-, -S- or -NH-.

[0037] In the polymerizable liquid crystal compound (A1), X 1 and X2 are each independently preferably an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, and X 1 and X 2 At least one of these is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, preferably a trans-cyclohexane-1,4-diyl group. The optionally substituted 1,4-phenylene group or the optionally substituted cyclohexane-1,4-diyl group may optionally have a substituent, such as an alkyl group having 1 to 4 carbon atoms, a cyano group, or a halogen atom, such as a chlorine atom or a fluorine atom. Preferably, the group is unsubstituted.

[0038] The polymerizable liquid crystal compound (A1) is a compound represented by the formula (A1) having the formula (A1-1): -(X 1 -Y 1 ) n -X 2 - (A1-1) [In the formula, X 1 , Y 1 , X 2 and n have the same meanings as above.] [hereinafter, also referred to as partial structure (A1-1)] preferably has an asymmetric structure, since this facilitates the development of smectic liquid crystal properties. The polymerizable liquid crystal compound (A1) in which the partial structure (A1-1) is an asymmetric structure is, for example, a compound in which n is 1 and one X 1 and X 2 and Y are different from each other. 1 are compounds having the same structure as each other, and two X 1 have the same structure as each other, and one X 2 These two X 1 The polymerizable liquid crystal compound (A1) has a structure different from that of the two X 1 Of the W 1 X binds to 1 But the other X1 and X 2 The other X 1 and X 2 Furthermore, the polymerizable liquid crystal compound (A1) may be a compound having the same structure as the compound (A1). 1 are compounds having the same structure as each other, and three X 1 and one X 2 The polymerizable liquid crystal compound (A1) may be any one of the following three:

[0039] Y 1 -CH2CH2-, -CH2O-, -CH2CH2O-, -COO-, -OCOO-, single bond, -N=N-, -CR a =CR b -, -C≡C-, -CR a =N- or -CO-NR a - is preferred. a and R b are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1 is more preferably -CH2CH2-, -COO- or a single bond, and 1 If there is an X 2 Y bonded to 1 is more preferably -CH2CH2- or CH2O-. 1 and X 2 When all of Y are the same structure, two or more Y 1 It is preferable that there are plural Y 1 When the compound has an asymmetric structure, the compound tends to exhibit smectic liquid crystallinity.

[0040] U 2 is a polymerizable group. 1 is a hydrogen atom or a polymerizable group, preferably a polymerizable group. 1 and U 2Preferably, both of U are polymerizable groups, and preferably both are radically polymerizable groups. Examples of the polymerizable group include the same groups as those exemplified above as the polymerizable group contained in the polymerizable liquid crystal compound (A). 1 and a polymerizable group represented by U 2 may be different from each other, but are preferably the same type of group, and U 1 and U 2 Preferably, at least one of the groups is a (meth)acryloyl group, and more preferably, both of the groups are (meth)acryloyl groups. The polymerizable group may be in a polymerized state or an unpolymerized state, but is preferably in an unpolymerized state.

[0041] V 1 and V 2 Examples of the alkanediyl group represented by the formula (V) include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a decane-1,10-diyl group, a tetradecane-1,14-diyl group, and an icosane-1,20-diyl group. 1 and V 2 is preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms.

[0042] Examples of the substituent that the alkanediyl group may optionally have include a cyano group and a halogen atom, but the alkanediyl group is preferably unsubstituted, and more preferably an unsubstituted linear alkanediyl group.

[0043] W 1 and W 2 are each independently preferably a single bond, -O-, -S-, -COO- or -OCOO-, more preferably a single bond or -O-.

[0044] The polymerizable liquid crystal compound (A) is not particularly limited as long as it is a polymerizable liquid crystal compound having at least one polymerizable group, and known polymerizable liquid crystal compounds can be used, but it is preferable that it exhibits smectic liquid crystallinity. As a structure that is likely to exhibit smectic liquid crystallinity, it is preferable that it has an asymmetric molecular structure within the molecular structure, and specifically, it is more preferable that it is a polymerizable liquid crystal compound that exhibits smectic liquid crystallinity and has the partial structures (Aa) to (Ai) below. From the perspective of easily exhibiting higher-order smectic liquid crystallinity, it is more preferable that it has the partial structure (Aa), (Ab), or (Ac). In the following (Aa) to (Ai), * represents a bond (single bond).

[0045] [ka]

[0046] Specific examples of the polymerizable liquid crystal compound (A) include compounds represented by formulae (A-1) to (A-25). When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans isomer.

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] Among these, at least one selected from the group consisting of compounds represented by formula (A-2), formula (A-3), formula (A-4), formula (A-5), formula (A-6), formula (A-7), formula (A-8), formula (A-13), formula (A-14), formula (A-15), formula (A-16) and formula (A-17) is preferred. As the polymerizable liquid crystal compound (A), one type may be used alone, or two or more types may be used in combination.

[0051] The polymerizable liquid crystal compound (A) can be produced by a known method, for example, as described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

[0052] In the present invention, the polarizer-forming composition may contain other polymerizable liquid crystal compounds besides the polymerizable liquid crystal compound (A). However, from the viewpoint of obtaining a polarizing layer with a high degree of orientational order, the proportion of the polymerizable liquid crystal compound (A) relative to the total mass of all polymerizable liquid crystal compounds contained in the polarizer-forming composition is preferably 51 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more.

[0053] When the polarizer-forming composition contains two or more polymerizable liquid crystal compounds (A), at least one of them may be the polymerizable liquid crystal compound (A1), or all of them may be the polymerizable liquid crystal compound (A1). By combining multiple polymerizable liquid crystal compounds, it may be possible to temporarily maintain liquid crystallinity even at a temperature below the liquid crystal-crystalline phase transition temperature.

[0054] The content of the polymerizable liquid crystal compound in the polarizer-forming composition is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 99% by mass, based on the solid content of the polarizing layer-forming composition. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. Hereinafter, the term "solid content" refers to the components remaining after excluding volatile components such as solvents from the polarizer-forming composition. Hereinafter, the term "solid content" refers to the components remaining after excluding volatile components such as solvents from the target composition.

[0055] In the present invention, the polarizer-forming composition for forming the absorptive polarizer contains a dichroic dye. Here, the dichroic dye refers to a dye having different absorbance in the long axis direction of the molecule and absorbance in the short axis direction. The dichroic dye that can be used in the present invention is not particularly limited as long as it has the above-mentioned properties, and may be a dye or a pigment. Furthermore, two or more dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. Furthermore, the dichroic dye may be polymerizable or liquid crystalline.

[0056] As a dichroic dye, the maximum absorption wavelength (λ MAX ) is preferred. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes.

[0057] Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, and bisazo dyes and trisazo dyes are preferred, such as a compound represented by formula (I) (hereinafter also referred to as "compound (I)"). K 1 (-N=NK 2 ) p -N=NK 3 (I) [In formula (I), K 1 and K. 3represent, independently of each other, an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted benzoic acid phenyl ester group, or an optionally substituted monovalent heterocyclic group. 2 represents a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, a 4,4'-stilbenylene group which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 0 to 4. When p is an integer of 2 or more, a plurality of K 2 may be the same or different. The -N=N- bond may be replaced with a -C=C-, -COO-, -NHCO-, or -N=CH- bond as long as the compound exhibits absorption in the visible region.

[0058] Examples of monovalent heterocyclic groups include groups in which one hydrogen atom has been removed from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, benzoxazole, etc. Examples of divalent heterocyclic groups include groups in which two hydrogen atoms have been removed from the above heterocyclic compounds.

[0059] K 1 and K. 3 Phenyl group, naphthyl group, benzoic acid phenyl ester group and monovalent heterocyclic group in 2In the formula (I), the p-phenylene group, the naphthalene-1,4-diyl group, the 4,4'-stilbenylene group, and the divalent heterocyclic group may optionally have a substituent, such as an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms and having a polymerizable group, or an alkenyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, or a butoxy group; an alkoxy group having 1 to 20 carbon atoms and having a polymerizable group; a fluorinated alkyl group having 1 to 4 carbon atoms, such as a trifluoromethyl group; Examples of the polymerizable group include an ano group, a nitro group, a halogen atom, and substituted or unsubstituted amino groups such as an amino group, a diethylamino group, and a pyrrolidino group (a substituted amino group refers to an amino group having one or two alkyl groups of 1 to 6 carbon atoms, an amino group having one or two alkyl groups of 1 to 6 carbon atoms and a polymerizable group, or an amino group in which two substituted alkyl groups are bonded to form an alkanediyl group of 2 to 8 carbon atoms. An unsubstituted amino group is -NH2). Examples of the polymerizable group include a (meth)acryloyl group and a (meth)acryloyloxy group.

[0060] Among the compounds (I), compounds represented by any one of the following formulae (I-1) to (I-8) are preferred. [ka] [In formulas (I-1) to (I-8), B 1 ~B 30 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of a substituted amino group and an unsubstituted amino group are as defined above), a chlorine atom, or a trifluoromethyl group. n1 to n4 each independently represent an integer of 0 to 3. If n1 is 2 or more, multiple B 2 may be the same or different from each other, If n2 is 2 or more, multiple B 6 may be the same or different from each other, If n3 is 2 or more, multiple B 9may be the same or different from each other, If n4 is 2 or more, multiple B 14 may be the same or different.]

[0061] The anthraquinone dye is preferably a compound represented by formula (I-9). [ka] [In formula (I-9), R 1 ~R 8 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0062] The oxazone dye is preferably a compound represented by formula (I-10). [ka] [In formula (I-10), R 9 ~R 15 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0063] The acridine dye is preferably a compound represented by formula (I-11). [ka] [In formula (I-11), R 16 ~R 23are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. In formula (I-9), formula (I-10) and formula (I-11), R x Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a toluyl group, a xylyl group, and a naphthyl group.

[0064] As the cyanine dye, compounds represented by formula (I-12) and compounds represented by formula (I-13) are preferred. [ka] [In formula (I-12), D 1 and D 2 represent, independently of each other, a group represented by any one of formulae (I-12a) to (I-12d). [ka] n5 represents an integer from 1 to 3. [ka] [In formula (I-13), D 3 and D 4 represent, independently of each other, a group represented by any one of formulas (I-13a) to (I-13h). [ka] n6 represents an integer from 1 to 3.

[0065] Among these dichroic dyes, azo dyes have high linearity and are therefore suitable for producing a polarizing layer with excellent polarization performance. Therefore, in one embodiment of the present invention, the dichroic dye contained in the polarizing layer-forming composition that forms the polarizing layer is preferably an azo dye.

[0066] In the present invention, the weight average molecular weight of the dichroic dye is usually 300 to 2,000, and preferably 400 to 1,000.

[0067] In one embodiment of the present invention, the dichroic dye contained in the polarizer-forming composition is preferably hydrophobic. When the dichroic dye is hydrophobic, the compatibility between the dichroic dye and the polymerizable liquid crystal compound is improved, and the dichroic dye and the polymerizable liquid crystal compound form a uniform phase state, thereby obtaining an absorptive polarizer layer with a high degree of orientational order. In the present invention, a hydrophobic dichroic dye refers to a dye whose solubility in 100 g of water at 25°C is 1 g or less.

[0068] The content of the dichroic dye in the polarizer-forming composition can be appropriately determined depending on the type of dichroic dye used, but is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.1 to 12 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the dichroic dye is within the above range, the orientation of the polymerizable liquid crystal compound is unlikely to be disturbed, and an absorptive polarizer having a high degree of orientational order can be obtained.

[0069] In the present invention, the polarizer-forming composition may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating the polymerization reaction of a polymerizable liquid crystal compound, and a photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions. Specific examples include photopolymerization initiators capable of generating active radicals or acids under the action of light, and among these, photopolymerization initiators that generate radicals under the action of light are preferred. The polymerization initiators can be used alone or in combination of two or more.

[0070] As the photopolymerization initiator, known photopolymerization initiators can be used. For example, photopolymerization initiators that generate active radicals include self-cleavage type photopolymerization initiators and hydrogen abstraction type photopolymerization initiators. Examples of the self-cleaving photopolymerization initiator that can be used include self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and azo compounds. Examples of the hydrogen abstraction photopolymerization initiator that can be used include hydrogen abstraction benzophenone compounds, benzoin ether compounds, benzil ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, and triazine compounds.

[0071] As the photopolymerization initiator that generates an acid, an iodonium salt, a sulfonium salt, or the like can be used.

[0072] Among these, a reaction at low temperature is preferred from the viewpoint of preventing dissolution of the dye, and a self-cleaving photopolymerization initiator is preferred from the viewpoint of reaction efficiency at low temperature, and an acetophenone-based compound, a hydroxyacetophenone-based compound, an α-aminoacetophenone-based compound, or an oxime ester-based compound is particularly preferred.

[0073] Specific examples of the photopolymerization initiator 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 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one; 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-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; benzophenone compounds such as benzophenone, methyl o-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 triazine-based compounds such as 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 may be appropriately selected from the above-mentioned photopolymerization initiators, for example, in consideration of the relationship with the polymerizable liquid crystal compound contained in the polarizer-forming composition.

[0074] 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, and OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, and Esacure KIP160 (manufactured by IDM Resins); BV); Seikuol (registered trademark) BZ, Z, and BEE (Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (ADEKA Corporation); TAZ-A and TAZ-PP (Nihon Siber Hegner Co., Ltd.); and TAZ-104 (Sanwa Chemical Co., Ltd.).

[0075] The content of the polymerization initiator in the polarizer-forming composition is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, still more preferably 2 to 8 parts by mass, and particularly preferably 4 to 8 parts by mass, relative to 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 disturbing the alignment of the polymerizable liquid crystal compound.

[0076] In the present invention, the polymerization rate of the polymerizable liquid crystal compound is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more, from the viewpoints of line contamination during production and handling.

[0077] The polarizer-forming composition may further contain a photosensitizer. The use of a photosensitizer can further promote the polymerization reaction of the polymerizable liquid crystal compound. Examples of photosensitizers include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene, etc.); phenothiazine, rubrene, etc. The photosensitizers can be used alone or in combination of two or more.

[0078] When the polarizer-forming composition contains a photosensitizer, the content thereof may be determined appropriately depending on the type and amount of the polymerization initiator and polymerizable liquid crystal compound, but is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

[0079] The polarizer-forming composition may also contain a leveling agent. The leveling agent adjusts the fluidity of the polarizer-forming composition and functions to make the coating film obtained by applying the polarizer-forming composition flatter. Specific examples of the leveling agent include surfactants. The leveling agent is preferably at least one selected from the group consisting of leveling agents containing a polyacrylate compound as a main component and leveling agents containing a fluorine atom-containing compound as a main component. The leveling agents can be used alone or in combination of two or more.

[0080] Examples of leveling agents containing polyacrylate compounds as their main components include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", "BYK-361N", "BYK-380", "BYK-381" and "BYK-392" (BYK Chemie).

[0081] Examples of leveling agents containing a fluorine atom-containing compound as a main component include "Megafac (registered trademark) R-08", "R-30", "R-90", "F-410", "F-411", "F-443", "F-445", "F-470", "F-471", "F-477", "F-479", "F-482" and "F-483" (DIC Corporation); "Surflon (registered trademark) S-381" and "S-483" (DIC Corporation); Examples of such grease include "S-382", "S-383", "S-393", "SC-101", "SC-105", "KH-40" and "SA-100" (AGC Seimi Chemical Co., Ltd.); "E1830", "E5844" (Daikin Fine Chemicals Research Institute, Ltd.); "F-TOP EF301", "F-TOP EF303", "F-TOP EF351" and "F-TOP EF352" (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0082] When the polarizer-forming composition contains a leveling agent, the content thereof is preferably 0.05 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound is easily aligned, unevenness is less likely to occur, and a smoother absorption-type polarizer tends to be obtained.

[0083] The polarizer-forming composition may contain additives other than the photosensitizer and the leveling agent. Examples of the additives include antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When the polarizer-forming composition contains other additives, the content of the additives is preferably more than 0% and not more than 20% by mass, more preferably more than 0% and not more than 10% by mass, based on the solid content of the polarizer-forming composition.

[0084] The polarizer-forming composition can be produced by a conventionally known method for preparing a polarizer-forming composition, and can usually be prepared by mixing and stirring a polymerizable liquid crystal compound and a dichroic dye, and, if necessary, a polymerization initiator and the above-mentioned additives, etc. Furthermore, since, for example, compounds that exhibit smectic liquid crystallinity generally have high viscosity, the viscosity may be adjusted by adding a solvent to the polarizer-forming composition from the viewpoint of improving the coatability of the polarizer-forming composition and facilitating the formation of a polarizer layer.

[0085] The solvent used in the polarizer-forming composition can be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and dichroic dye used. Specific 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 alone or in combination. The content of the solvent 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, relative to 100 parts by mass of the solid content of the polarizer-forming composition.

[0086] In the present invention, the polarizer preferably has a high degree of orientational order. A polarizer with a high degree of orientational order exhibits a Bragg peak derived from a higher-order structure, such as a hexatic or crystalline phase, in X-ray diffraction measurement. A Bragg peak refers to a peak derived from the planar periodic structure of molecular orientation. Therefore, the absorption-type polarizer of the present invention preferably exhibits a Bragg peak in X-ray diffraction measurement. That is, in the absorption-type polarizer constituting the composite polarizing plate of the present invention, the polymerizable liquid crystal compound or its polymer is preferably oriented so that the polarizer exhibits a Bragg peak in X-ray diffraction measurement, and it is more preferable that the molecules of the polymerizable liquid crystal compound are horizontally oriented in the direction of light absorption. In the present invention, a polarizer having a molecular orientation planar periodicity of 3.0 to 6.0 Å is preferred. A high degree of orientational order that exhibits a Bragg peak can be achieved by controlling the type of polymerizable liquid crystal compound used, the type and amount of dichroic dye, and the type and amount of polymerization initiator.

[0087] In the present invention, the absorptive polarizer can be obtained, for example, by a method including forming a coating film of a polarizer-forming composition on a substrate or an alignment film described later, removing the solvent from the coating film, raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid crystal phase (e.g., a smectic phase), and polymerizing the polymerizable liquid crystal compound while maintaining the liquid crystal phase.

[0088] Examples of a method for applying the polarizer-forming composition to a substrate or an alignment film include known methods such as coating methods, such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator methods, and printing methods, such as flexography.

[0089] Next, the solvent is removed by drying or the like under conditions that do not polymerize the polymerizable liquid crystal compound contained in the coating film obtained from the polarizer-forming composition, thereby forming a dried coating film. Examples of the drying method include natural drying, ventilation drying, heat drying, and reduced-pressure drying.

[0090] Furthermore, in order to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid phase, the temperature is raised to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then the temperature is lowered to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid crystal phase (e.g., a smectic phase). Such a phase transition may be carried out after or simultaneously with the removal of the solvent from the coating film.

[0091] By polymerizing the polymerizable liquid crystal compound while maintaining its liquid crystal state, an absorptive polarizer layer is formed as a cured product of the polarizer-forming composition. Photopolymerization is a preferred polymerization method. In photopolymerization, the light irradiated onto the dried coating film is appropriately selected depending on the type of polymerizable liquid crystal compound contained in the dried coating film (particularly the type of polymerizable group possessed by the polymerizable liquid crystal compound), the type and amount of polymerization initiator, and other factors. Specific examples include one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays, and actinic electron beams. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and photopolymerization equipment widely used in the field can be used. It is preferable to select the types of polymerizable liquid crystal compound and polymerization initiator contained in the polarizer-forming composition so that they can be photopolymerized by ultraviolet light. Furthermore, the polymerization temperature can be controlled by irradiating the dried coating film with light while cooling it with an appropriate cooling means. During photopolymerization, a patterned polarizing layer can be obtained by performing masking and development.

[0092] Examples of the light source of the active energy rays include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source emitting light in a wavelength range of 380 to 440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

[0093] The UV irradiation intensity is usually 10 to 3,000 mW / cm 2The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a photopolymerization initiator. The light irradiation time is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiating once or multiple times with such ultraviolet irradiation intensity, the cumulative light amount is 10 to 3,000 mJ / cm. 2 , preferably 50 to 2,000 mJ / cm 2 , more preferably 100 to 1,000 mJ / cm 2 is.

[0094] By photopolymerization, the polymerizable liquid crystal compound is polymerized while maintaining a liquid crystal phase, particularly a smectic phase, and preferably a high-order smectic phase, to form a polarizer layer. The polarizer obtained by polymerizing the polymerizable liquid crystal compound while maintaining a smectic phase has the advantage of higher polarization performance, due in part to the action of the dichroic dye, compared to conventional host-guest polarizing films, i.e., polarizers formed in a nematic liquid crystal phase. Furthermore, the polarizer has the advantage of superior strength compared to films coated with only a dichroic dye or lyotropic liquid crystal.

[0095] The thickness of the absorptive polarizer can be appropriately selected depending on the display device to which it is applied, and is preferably 0.1 to 5 μm, more preferably 0.3 to 4 μm, and even more preferably 0.5 to 3 μm. When the film thickness of the absorptive polarizer is equal to or greater than the above lower limit, the necessary light absorption can be sufficiently obtained, and when it is equal to or less than the above upper limit, the occurrence of alignment defects due to a decrease in the alignment regularity of the alignment film can be easily suppressed.

[0096] The absorptive polarizer may be formed on an alignment film. The alignment film has an alignment regulating force that aligns the polymerizable liquid crystal compound in a desired direction, and a precisely aligned polarizer can be easily obtained by applying a polarizer-forming composition onto the alignment film. The alignment film preferably has solvent resistance that prevents the polarizer-forming composition from dissolving when applied, and also has heat resistance during heat treatment for removing the solvent and orienting the polymerizable liquid crystal compound. In the present invention, the alignment film is preferably a photo-alignment film from the viewpoints of the precision and quality of the alignment angle, as well as the water resistance and bending resistance of the absorptive polarizer including the alignment film. The photo-alignment film is also advantageous in that the direction of the alignment regulating force can be freely controlled by selecting the polarization direction of the polarized light to be irradiated.

[0097] A photo-alignment film is typically obtained by applying a composition (hereinafter also referred to as a "photo-alignment film-forming composition") containing a polymer, oligomer, or monomer (hereinafter also referred to as a "polymer, etc. having a photo-reactive group") and a solvent to a substrate or, if necessary, to a diffusion prevention layer (described later) provided on the substrate, followed by irradiation with polarized light (preferably polarized UV). The substrate on which the photo-alignment film is formed is not particularly limited, and conventional resin films known in the field of optical films can be used. When an absorptive polarizer is formed on a substrate, the substrate may be one that is ultimately incorporated into an absorptive polarizer or composite polarizer, or may be one that is peelable from these. When the polymer, etc. contained in the photo-alignment film-forming composition has the same reactive group (e.g., a (meth)acryloyl group) as the functional group of the polymerizable group of the polymerizable liquid crystal compound that forms the absorptive polarizer, adhesion between the polarizer layer and the substrate tends to be improved.

[0098] The photoreactive group refers to a group that exhibits liquid crystal alignment ability upon irradiation with light. Specific examples include groups involved in photoreactions that induce molecular alignment upon irradiation with light or that are the origin of liquid crystal alignment ability, such as isomerization, dimerization, photocrosslinking, or photodecomposition. Among these, groups involved in dimerization or photocrosslinking are preferred because of their excellent alignment properties. As the photoreactive group, groups having an unsaturated bond, particularly a double bond, are preferred, and groups having at least one bond selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) are particularly preferred.

[0099] Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having an azoxybenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

[0100] Among these, photoreactive groups involved in photodimerization reactions are preferred, and cinnamoyl and chalcone groups are preferred because they require a relatively small amount of polarized light irradiation for photoalignment and are likely to produce a photoalignment film with excellent thermal stability and stability over time. As the polymer having a photoreactive group, those having a cinnamoyl group such that the terminal of the polymer side chain has a cinnamic acid structure are particularly preferred.

[0101] The photo-alignment-inducing layer can be formed by applying the composition for forming a photo-alignment film, for example, to a substrate or a diffusion prevention layer provided on the substrate. The solvent contained in the composition can be the same as the solvents exemplified above as solvents that can be used in forming an absorptive polarizer, and can be appropriately selected depending on the solubility of the polymer having a photoreactive group, etc.

[0102] The content of the polymer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted appropriately depending on the type of polymer and the desired thickness of the photo-alignment film, but is preferably at least 0.2% by mass, more preferably in the range of 0.3 to 10% by mass, relative to the mass of the composition for forming a photo-alignment film. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, or a photosensitizer, as long as the properties of the photo-alignment film are not significantly impaired.

[0103] Methods for applying the composition for forming a photo-alignment film onto a substrate or onto a diffusion prevention layer, and methods for removing the solvent from the applied composition for forming a photo-alignment film, include methods similar to those for applying the composition for forming a polarizer onto a substrate or the like and removing the solvent.

[0104] The polarized light irradiation may be performed by directly irradiating the coating film of the photo-alignment film-forming composition with polarized UV light after removing the solvent, or by irradiating the substrate with polarized light and then transmitting the polarized light. It is particularly preferable that the polarized light be substantially parallel. The wavelength of the polarized light to be irradiated should be in a wavelength range in which the photoreactive group in the polymer having a photoreactive group can absorb the light energy. Specifically, UV (ultraviolet light) with a wavelength of 250 to 400 nm is particularly preferable. Examples of light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. High-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are more preferable. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferred due to their high emission intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV light can be irradiated by passing light from the light source through an appropriate polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as a Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

[0105] If masking is performed during polarized light irradiation, a plurality of regions (patterns) with different liquid crystal alignment directions can be formed.

[0106] The number-average molecular weight of the photo-alignment film is preferably 20,000 to 100,000, more preferably 25,000 or more, and more preferably 90,000 or less, and even more preferably 80,000 or less. When the number-average molecular weight of the photo-alignment film is within the above range, adhesion between the photo-alignment film and adjacent layers is likely to be improved. The number-average molecular weight of the photo-alignment film can be controlled by the amount of monomers used in the composition for forming a photo-alignment film, the type and amount of polymerization initiator, etc. The "number average molecular weight of the photo-alignment film" referred to here essentially corresponds to the number average molecular weight of the polymer constituting the cured photo-alignment film, and is a molecular weight calculated by measuring the cured photo-alignment film itself using a measuring instrument such as gel permeation chromatography.

[0107] The thickness of the photo-alignment film is preferably 10 to 5000 nm, more preferably 10 to 1000 nm, and even more preferably 30 to 300 nm. When the thickness of the photo-alignment film is within the above range, the film can exhibit good adhesion at the interface with the absorptive polarizer and can exert an alignment regularity, thereby forming an absorptive polarizer with high alignment order.

[0108] In the composite polarizing plate of the present invention, the absorptive polarizing plate may further include a diffusion prevention layer on one or both surfaces of the absorptive polarizer. The presence of a diffusion prevention layer adjacent to or close to the absorptive polarizer effectively prevents the dichroic dye in the absorptive polarizer from diffusing into other layers, thereby preventing the deterioration of the optical properties of the composite polarizing plate of the present invention over time due to the diffusion of the dichroic dye. To fully achieve this effect, the diffusion prevention layer is preferably provided on the pressure-sensitive adhesive layer 1 side of the absorptive polarizer adjacent to the absorptive polarizer or via only an alignment film forming a polarizer. More preferably, the diffusion prevention layer is provided on both the pressure-sensitive adhesive layer 1 side and the opposite side of the absorptive polarizer adjacent to the absorptive polarizer or via only an alignment film forming a polarizer. When diffusion prevention layers are provided on both sides of the absorptive polarizer, they may be the same or different.

[0109] The diffusion prevention layer is not particularly limited as long as it is a layer having a function of preventing the diffusion of a dichroic dye, and examples thereof include a layer formed from a resin composition containing a water-soluble polymer, and a layer formed from a curable composition containing an active energy ray-curable resin.

[0110] The water-soluble polymer has a polarity significantly different from that of the dichroic dye, and therefore can prevent the diffusion of the dichroic dye. Examples of water-soluble polymers that can form the diffusion prevention layer include polyacrylamide polymers; polyvinyl alcohol, and vinyl alcohol polymers such as ethylene-vinyl alcohol copolymers and (meth)acrylic acid or its anhydride-vinyl alcohol copolymers; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; and polyethylene oxide polymers. These polymers may be used alone or in combination of two or more.

[0111] When the diffusion prevention layer is a layer formed from a resin composition containing a water-soluble polymer (hereinafter also referred to as a "water-soluble polymer-containing resin composition"), the content of the water-soluble polymer in the layer is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more.

[0112] When the diffusion-preventing layer is a layer formed from a water-soluble polymer-containing resin composition, a crosslinking structure may be introduced by using a crosslinking agent to increase the density of the layer and improve the dichroic dye diffusion-preventing function. Examples of such crosslinking agents include water-soluble additives and crosslinking agents such as ionic crosslinking agents such as glyoxylate salts and epoxy crosslinking agents, as well as hydrophobic crosslinking agents such as isocyanate crosslinking agents, polyaldehyde crosslinking agents such as glyoxal and glyoxal derivatives, and metal compound crosslinking agents such as zirconium chloride and titanium lactate crosslinking agents for the purpose of imparting water resistance.

[0113] When a crosslinking agent is used to introduce a crosslinked structure into the diffusion prevention layer, the amount of the crosslinking agent added may be appropriately determined depending on the type of crosslinking agent used, etc. For example, the amount may be 0.1 to 100 parts by mass, preferably 1 to 50 parts by mass, and more preferably 5 to 30 parts by mass, per 100 parts by mass of the water-soluble polymer. When the content of the crosslinking agent is within the above range, the diffusion prevention layer becomes dense, and the shielding effect against the dichroic dye in the absorptive polarizer is likely to be improved.

[0114] The water-soluble polymer-containing resin composition capable of forming the diffusion barrier layer is usually prepared as a solution in which the water-soluble polymer is dissolved in a solvent. The solvent may be selected depending on the water-soluble polymer to be used, but typical examples include water, alcohol, and a mixture of water and alcohol, with water being preferred.

[0115] The solids concentration of the water-soluble polymer-containing resin composition obtained by adding a solvent to the components constituting the diffusion prevention layer, such as the water-soluble polymer and crosslinking agent, is preferably 1 to 50 mass %, more preferably 2 to 30 mass %. When the solids concentration of the water-soluble polymer-containing resin composition is within the above range, the viscosity of the composition is low, resulting in good coatability and handleability.

[0116] The water-soluble polymer-containing resin composition may contain other components such as additives in addition to the water-soluble polymer, crosslinker, and solvent such as water. Examples of such other components include preservatives and leveling agents. When the water-soluble polymer-containing resin composition contains other components such as additives, the amount of such components is preferably 10% by mass or less, more preferably 5% by mass or less, based on the solid content of the resin composition.

[0117] For example, the diffusion prevention layer can be obtained by applying a water-soluble polymer-containing resin composition to the surface on which the diffusion prevention layer is to be formed, and then drying and curing the coating.

[0118] The method for applying the water-soluble polymer-containing resin composition is not particularly limited, and examples thereof include known methods similar to those for applying a polarizer-forming composition to a substrate or the like.

[0119] The drying temperature and time for forming a diffusion-preventing layer from a coating film of the water-soluble polymer-containing resin composition are not particularly limited and may be appropriately determined depending on the composition of the water-soluble polymer-containing resin composition used. The drying treatment can be carried out, for example, by blowing hot air, and the temperature is usually within the range of 40 to 100° C., preferably 60 to 100° C. The drying time is usually 10 seconds to 10 minutes.

[0120] Active energy ray-curable resins tend to have excellent dichroic dye diffusion prevention properties due to their high polymerizability. Examples of curable compositions containing active energy ray-curable resins capable of forming a diffusion barrier layer (hereinafter also referred to as "diffusion barrier layer-forming curable compositions") include cationically polymerizable curable compositions containing cationically polymerizable compounds as curable compounds, radically polymerizable curable compositions containing radically polymerizable compounds as curable compounds, and hybrid curable compositions containing both cationically polymerizable and radically polymerizable compounds. Specific examples of cationically polymerizable compounds include epoxy compounds having one or more epoxy groups in the molecule, oxetane compounds having one or more oxetane rings in the molecule, and vinyl compounds. Specific examples of radically polymerizable compounds include (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, vinyl compounds, and the like. The diffusion barrier layer-forming curable composition may contain one or more cationically polymerizable compounds and / or one or more radically polymerizable compounds.

[0121] The cationically polymerizable compound, which is the main component of the cationically polymerizable curable composition, refers to a compound or oligomer that undergoes a cationic polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays or when heated, and examples of such compounds include epoxy compounds, oxetane compounds, and vinyl compounds. Of these, the preferred cationically polymerizable compound is an epoxy compound.

[0122] An epoxy compound is a compound having one or more, preferably two or more, epoxy groups in the molecule. One type of epoxy compound may be used alone, or two or more types may be used in combination. Examples of epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. From the viewpoints of weather resistance, curing speed, and adhesiveness, it is preferable that the epoxy compound contains an alicyclic epoxy compound or an aliphatic epoxy compound.

[0123] In one embodiment of the present invention, when the curable composition for forming a diffusion prevention layer contains an epoxy compound as a cationically polymerizable compound, the content of the epoxy compound is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, relative to 100 parts by mass of the solid content of the curable composition.

[0124] When the total amount of curable compounds contained in the curable composition for forming a diffusion barrier layer (including hybrid types) containing a cationically polymerizable compound is taken as 100 mass %, the content of the cationically polymerizable compound (when two or more types of cationically polymerizable compounds are contained, the total content of these compounds) is preferably 50 mass % or more, more preferably 60 mass % or more, and even more preferably 70 mass % or more. In addition, the cationically polymerizable curable composition may further contain a polymer component (such as a thermoplastic resin).

[0125] When the curable composition for forming a diffusion barrier layer contains a cationic polymerizable compound, it preferably contains a cationic photopolymerization initiator. The cationic photopolymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of the cationic curable compound. Because the cationic photopolymerization initiator acts catalytically under light, it exhibits excellent storage stability and workability even when mixed with the cationic photocurable compound. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

[0126] The cationic photopolymerization initiator may be used alone or in combination of two or more. Among them, aromatic sulfonium salts are preferably used because they have ultraviolet absorption properties even in the wavelength region around 300 nm, and therefore can provide a cured product with excellent curability, good mechanical strength, and adhesive strength.

[0127] The content of the cationic photopolymerization initiator in the curable composition for forming a diffusion prevention layer is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the solid content of the curable compound. When the content of the cationic photopolymerization initiator is within the above range, the cationic polymerizable compound can be sufficiently cured, and the resulting diffusion prevention layer can be imparted with high mechanical strength and adhesive strength.

[0128] A hybrid curable composition can also be obtained by incorporating a radically polymerizable compound in addition to a cationic polymerizable compound into a cationic polymerization curable composition. The combined use of a radically polymerizable compound is expected to have the effect of increasing the hardness and mechanical strength of the diffusion prevention layer, and further makes it easier to adjust the viscosity, curing speed, etc. of the curable composition.

[0129] The radical polymerizable compound, which is the main component of the radical polymerization type curable composition, refers to a compound or oligomer that undergoes a radical polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays or when heated, and specifically includes a compound having an ethylenically unsaturated bond. Examples of the compound having an ethylenically unsaturated bond include (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, as well as vinyl compounds such as styrene, styrene sulfonic acid, vinyl acetate, vinyl propionate, and N-vinyl-2-pyrrolidone. Among these, the preferred radical polymerizable compound is a (meth)acrylic compound.

[0130] The (meth)acrylic compound is a compound having at least one (meth)acryloyloxy group in the molecule, and may be a monomer, oligomer, or polymer. Examples of the (meth)acrylic compound include (meth)acrylate compounds such as monofunctional (meth)acrylate compounds and polyfunctional (meth)acrylate compounds; urethane (meth)acrylate compounds such as polyfunctional urethane (meth)acrylate compounds; epoxy (meth)acrylate compounds such as polyfunctional epoxy (meth)acrylate compounds; carboxyl group-modified epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, etc. The (meth)acrylic compounds may be used alone or in combination of two or more.

[0131] Examples of the (meth)acrylate compound include a monofunctional (meth)acrylate compound having one (meth)acryloyloxy group in the molecule, and a polyfunctional (meth)acrylate compound having two or more (meth)acryloyloxy groups in the molecule.

[0132] When a polyfunctional (meth)acrylate compound is used, the crosslink density of the diffusion prevention layer can be adjusted by controlling the molecular weight between crosslinks and the number of crosslinks of the compound. More specifically, the smaller the molecular weight between crosslinks, the higher the crosslink density. Also, the larger the number of crosslinks, the denser the crosslink density, and the more effectively the light-absorbing anisotropic film can be shielded from the dichroic dye.

[0133] The urethane (meth)acrylate compound generally refers to a reaction product of an isocyanate compound, a polyol compound, and a (meth)acrylate compound, and is preferably a polyfunctional urethane (meth)acrylate compound having two or more (meth)acryloyloxy groups in the molecule. Because polyfunctional urethane (meth)acrylate compounds can form a crosslinked structure, they are advantageous in terms of improving the dichroic dye diffusion prevention function of the diffusion prevention layer, and can also impart appropriate toughness. The number of functional groups in the polyfunctional urethane (meth)acrylate compound is preferably 2 to 5.

[0134] Examples of epoxy (meth)acrylate compounds include polyfunctional epoxy (meth)acrylates that can be obtained by an addition reaction between polyglycidyl ether and (meth)acrylic acid and have at least two (meth)acryloyloxy groups in the molecule. Examples of polyester (meth)acrylate compounds include compounds that have an ester bond and at least two (meth)acryloyl groups (typically (meth)acryloyloxy groups) in the molecule.

[0135] In one embodiment of the present invention, when the curable composition for forming a diffusion-preventing layer contains a radically polymerizable compound, it is preferable that the radically polymerizable compound contains a polyfunctional (meth)acrylate compound. In this case, the content of the polyfunctional (meth)acrylate compound is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, relative to 100 parts by mass of the solid content of the curable composition, and is preferably 100 parts by mass or less, more preferably 95 parts by mass or less, and even more preferably 90 parts by mass or less.

[0136] In one embodiment of the present invention, when the curable composition for forming a diffusion barrier layer contains a radically polymerizable compound, the radically polymerizable compound preferably contains a polyfunctional (meth)acrylate compound and a polyfunctional urethane (meth)acrylate compound. In this case, the polyfunctional (meth)acrylate compound and the urethane (meth)acrylate compound are preferably contained in a ratio (mass ratio of polyfunctional (meth)acrylate compound:urethane (meth)acrylate compound) of 95:5 to 50:50, more preferably 90:10 to 70:30.

[0137] When the curable composition for forming the diffusion prevention layer contains a radical polymerizable compound, it preferably contains a photoradical polymerization initiator. The photoradical polymerization initiator initiates the polymerization reaction of the radical curable compound by irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams. The photoradical polymerization initiator may be used alone or in combination of two or more.

[0138] Specific examples of the photoradical polymerization initiator include acetophenone-based initiators such as acetophenone, 3-methylacetophenone, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; and 2,2-dimethylbenzophenone. Alkylphenone initiators such as 1,2-diphenylethan-1-one and 1-hydroxycyclohexylphenyl ketone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; acylphosphine oxide initiators such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; and others such as xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

[0139] The content of the photoradical polymerization initiator in the curable composition for forming a diffusion prevention layer is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the solid content of the curable compound. When the content of the photoradical polymerization initiator is within the above range, the polymerization initiation ability is sufficiently exhibited, and the curability is improved, while the photoradical polymerization initiator is less likely to remain, making it easier to suppress a decrease in visible light transmittance, etc.

[0140] In the present invention, the curable composition for forming a diffusion-preventing layer may contain an organic solvent, for example, to adjust the viscosity to a level suitable for the coating method to be adopted, or may be substantially solvent-free (solvent-free). Note that "substantially solvent-free" does not exclude cases where a solvent is inevitably mixed in.

[0141] The solvent may be any solvent capable of dissolving the components constituting the diffusion prevention layer, and examples thereof include the same solvents as those usable in the polarizer-forming composition. These solvents may be used alone or in combination of two or more.

[0142] The type and content of the solvent are appropriately selected depending on the type and content of the components constituting the diffusion prevention layer, the shape, the application method, the thickness of the diffusion prevention layer, etc. When a solvent is contained, the amount thereof is, for example, preferably 3 to 1000 parts by mass, more preferably 5 to 100 parts by mass, and even more preferably 7 to 50 parts by mass per 100 parts by mass of the solid content of the curable composition.

[0143] The curable composition for forming a diffusion prevention layer may contain additives such as a cationic polymerization accelerator, a photosensitizer, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow adjuster, a plasticizer, an antifoaming agent, an antistatic agent, and a leveling agent, as needed.

[0144] For example, a diffusion-preventing layer can be obtained by applying a curable composition for forming a diffusion-preventing layer to the surface on which the diffusion-preventing layer is to be formed, and then irradiating the coating with active energy rays to cure the composition. The method of applying the curable composition for forming a diffusion-preventing layer, the type of active energy rays used for curing, the light source, the irradiation conditions, and the like can be similar to those used in the method of applying and curing the composition for forming a polarizer.

[0145] The thickness of the diffusion prevention layer is preferably 0.1 μm to 5 μm, more preferably 0.3 μm to 4 μm, and even more preferably 0.5 μm to 3 μm. Within this range, diffusion of the dichroic dye in the absorptive polarizer into other layers can be effectively suppressed. When the diffusion prevention layer is provided on both sides of the absorptive polarizer, the thicknesses of the layers may be the same or different.

[0146] <Reflective polarizing plate> The reflective polarizing plate used in the present invention is a polarization conversion element that has the function of separating natural light into transmitted polarized light and reflected or scattered polarized light. Specifically, the reflective polarizing plate can be an anisotropic multilayer thin film that can transmit linearly polarized light in one vibration direction and reflect linearly polarized light in the other vibration direction. Commercially available anisotropic multilayer thin films, such as those under the trade names "DBEF" and "APF" (manufactured by 3M, Sumitomo 3M Limited), can be suitably used. The reflective polarizing plate is not limited by its principle, and may be a combination of a cholesteric liquid crystal and a λ / 4 plate.

[0147] The thickness of the reflective polarizing plate can be about 10 to 100 μm, but is preferably 10 to 50 μm from the viewpoint of thinning the optical laminate, composite polarizing plate, and liquid crystal display device.

[0148] In a preferred embodiment of the present invention, the composite polarizing plate of the present invention preferably has an optical film, via a pressure-sensitive adhesive layer, on the surface opposite the pressure-sensitive adhesive layer 1 of the absorptive polarizer. Composite polarizing plates are often stored, transported, or carried in a rolled state. In this case, if the composite polarizing plate is rolled up with foreign matter, such as dust, adhering to its outer surface, the pressure applied during rolling can press the foreign matter against the composite polarizing plate during storage, transport, or carrying. Even after the pressure is released, indentations or scratches caused by the foreign matter can remain, or indentations caused by external pressure, such as impact, can remain on the roll. Such indentations can lead to defects in the composite polarizing plate. However, by disposing an optical film on the surface opposite the pressure-sensitive adhesive layer 1 of the absorptive polarizer, the formation of indentations (hereinafter also referred to as indentations during rolling) can be suppressed when the composite polarizing plate is processed into a roll.

[0149] The adhesive layer functions to bond an absorptive polarizing plate including an absorptive polarizer to an optical film. Examples of such adhesive layers include the adhesives exemplified above as adhesive compositions capable of forming the adhesive layer 1, as well as active energy ray-curable adhesives, water-based adhesives, organic solvent-based adhesives, and solventless adhesives. Among these, from the viewpoint of excellent suppression of indentation marks during roll processing, the adhesive layer for bonding the absorptive polarizing plate to the optical film is preferably an adhesive layer, and an active energy ray-curable adhesive is more preferred. An active energy ray-curable adhesive is an adhesive that cures upon irradiation with active energy rays such as ultraviolet light. Examples of active energy ray-curable adhesives include the cationic polymerization-type curable compositions and radical polymerization-type curable compositions exemplified as the curable composition for forming the diffusion barrier layer.

[0150] The thickness of the adhesive layer may be appropriately determined depending on the type of adhesive layer used, the configuration of the layer to be laminated, etc., but is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and even more preferably 0.5 to 5 μm, and may be, for example, 3 μm or less. When the thickness of the adhesive layer is within the above range, the effect of suppressing indentation marks during roll processing is likely to be improved.

[0151] The elastic modulus of the adhesive layer at 25°C is preferably 25 to 400 kPa, more preferably 30 to 200 kPa. When the elastic modulus of the adhesive layer is within the above range, the effect of suppressing indentation marks during roll processing can be improved. The elastic modulus of the adhesive layer can be controlled within a desired range by the composition of the adhesive forming the adhesive layer, etc. The elastic modulus of the pressure-sensitive adhesive layer can be measured by the same method as that for the elastic modulus of the pressure-sensitive adhesive layer 1 described above, using a viscoelasticity measuring device.

[0152] Examples of optical films include resin films commonly used as substrates in optical laminates. Specific examples include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose-based resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polycarbonates; polysulfones; polyethersulfones; polyether ketones; polyphenylene sulfide; and polyphenylene oxides. Among these, at least one selected from cellulose-based resins, cyclic olefin-based resins, and (meth)acrylic resins is preferred. These resins may be used alone or in combination of two or more. These resins can be formed into resin films by known methods such as solvent casting and melt extrusion.

[0153] In one embodiment of the present invention, the optical film is preferably a thermoplastic resin film having a glass transition temperature (Tg) of 80 to 180°C. When the optical film is a thermoplastic resin film having a glass transition temperature in the above range, a composite polarizing plate having excellent effects of suppressing indentation marks during roll processing can be obtained. From the viewpoint of further enhancing such effects, the glass transition temperature of the optical film (thermoplastic resin film) is more preferably 90 to 180°C, and even more preferably 100 to 170°C. The glass transition temperature of the optical film can be measured, for example, by a differential scanning calorimeter. Specifically, the glass transition temperature of the resin film can be measured by the method described in the examples below.

[0154] The optical film is preferably thin in terms of having a mass that allows practical handling, but if it is too thin, the strength decreases, and the effect of suppressing indentation marks during the roll processing may be insufficient, or the processability may be poor. The thickness of the optical film is preferably 10 μm to 90 μm, and more preferably 10 μm to 80 μm.

[0155] The composite polarizing plate of the present invention can be obtained by bonding a reflective polarizing plate and an absorptive polarizing plate via a pressure-sensitive adhesive layer 1. In this case, the reflective polarizing plate is formed so that the reflection axis of the reflective polarizing plate and the absorption axis of the absorptive polarizer substantially coincide with each other. The angle between the reflection axis of the reflective polarizing plate and the absorption axis of the absorptive polarizer is preferably 8° or less, more preferably 4° or less, and even more preferably 2° or less. This angle can be controlled, for example, by controlling the alignment force of an alignment film that aligns the absorptive polarizer.

[0156] The composite polarizing plate of the present invention, in which a reflective polarizing plate and an absorptive polarizer are laminated via a pressure-sensitive adhesive layer 1, is excellent in the effect of suppressing peeling and wrinkles between the reflective polarizing plate and the absorptive polarizing plate under high-temperature heating, and has high moldability under high-temperature heating. Therefore, it is suitable for display devices that require molding under high-temperature heating after laminating the reflective polarizing plate and the absorptive polarizing plate. In particular, since the viewing angle can be widened by combining the reflective polarizing plate and the absorptive polarizing plate with a lens, it is suitable for use in VR display devices and AR display devices, which require moldability to match the lens shape under high temperatures, a wide viewing angle, and high optical properties. [Example]

[0157] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" mean % by mass and parts by mass unless otherwise specified.

[0158] 1.Measurement method The physical properties in the examples and comparative examples were measured according to the following methods. (1) Thickness The thickness of each layer or film was measured using a laser microscope (Olympus Corporation, "LEXT") or a digital micrometer (Nikon Corporation, "MH-15M").

[0159] (2) Visibility-corrected polarization degree (Py) and luminous efficiency-corrected single transmittance (Ty) The sample's transmittance along the transmission axis (T1) and transmittance along the absorption axis (T2) were measured using a spectrophotometer (Shimadzu UV-3150) equipped with a polarizer folder using the double-beam method over the wavelength range of 380 to 680 nm in 2 nm steps. The degree of polarization and transmittance at each wavelength were calculated using the following equations (p) and (q). Luminosity correction was then performed using the 2-degree observer (C illuminant) of JIS Z 8701 to calculate the luminosity-corrected degree of polarization (Py) and luminosity-corrected transmittance (Ty). Single transmittance [%] = (T1 + T2) / 2 (p) Degree of polarization [%] = [(T1-T2) / (T1+T2)] x 100 (q)

[0160] (3) Glass transition temperature Tg of thermoplastic resin film The glass transition temperature Tg [°C] of the thermoplastic resin film was measured using a differential scanning calorimeter (Seiko Instruments' EXSTAR6000 series DSC6220).

[0161] (4) Elastic modulus of adhesive layer The adhesive layer was cut into a length of 70 mm and a width of 10 mm, and a tensile test was performed using a Shimadzu Autograph AG-IS. The adhesive layer was chucked at both ends of 10 mm in the longitudinal direction and pulled to break at a sweep speed of 1 mm / min. The tensile modulus was calculated from the slope of the initial linear part of the obtained stress-strain curve, and this value was used as the modulus of elasticity for each adhesive layer. [Measurement conditions] Normal Force FN:1N Distortion γ: 1% Frequency: 1Hz Temperature: 25℃

[0162] 2.Reflective polarizing plate As a reflective polarizer, 3M TM Brightness enhancement film APF was used.

[0163] 3. Absorptive polarizer (1) Preparation of liquid crystal composition The following components were mixed and stirred at 80°C for 1 hour to obtain a liquid crystal composition. The polymerizable liquid crystal compounds (X1) and (X2) have the structures shown below. The dichroic dyes (DP1) to (DP3) are azo dyes described in the examples of JP 2013-101328 A, and each has the structure shown below. Polymerizable liquid crystal compound (X1): 75 parts Polymerizable liquid crystal compound (X2): 25 parts Dichroic dye (DP1): 2.5 parts Dichroic dye (DP2): 2.5 parts Dichroic dye (DP3): 2.5 parts Polymerization initiator [2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure (registered trademark) 369; manufactured by BASF Japan Ltd.)]: 6 parts Leveling agent [polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)]: 1.2 parts Solvent [o-xylene]: 250 parts

[0164] ·Polymerizable liquid crystal compound (X1): [ka] ·Polymerizable liquid crystal compound (X2): [ka] ·Dichroic dye (DP1): [ka] Dichroic dye (DP2): [ka] Dichroic dye (DP3): [ka]

[0165] (2) Preparation of composition for forming photo-alignment film The following components described in JP 2013-033249 A were mixed, and the resulting mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a photoalignment film. Photo-alignable polymer with the structure shown below: 2 parts [ka] Solvent [o-xylene]: 98 parts

[0166] (3) Fabrication of an absorption polarizer <Preparation of a laminate including a diffusion prevention layer (1), a polarizer layer, and a diffusion prevention layer (2)> A release-treated surface of a release-treated polyethylene terephthalate film (SP-PLR382050 manufactured by Lintec Corporation) (release film) was subjected to a corona treatment, and then a resin layer-forming composition (A) was applied as a composition for forming a first diffusion prevention layer by a bar coating method (#2 30 mm / s). The resin layer-forming composition (A) was then applied to the release-treated surface of the release-treated polyethylene terephthalate film (SP-PLR382050 manufactured by Lintec Corporation) at an exposure dose of 500 mJ / cm using a UV irradiation device (SPOT CURE SP-7 manufactured by Ushio Inc.). 2 By irradiating the coating layer of the resin layer-forming composition (A) with ultraviolet light (365 nm standard), a release film with a resin layer was obtained in which a diffusion prevention layer (1) was formed on the surface of the release film. The thickness of the diffusion prevention layer (1) was 1.5 μm. (i) Preparation of resin layer-forming composition (A) The following components were mixed and stirred at 50° C. for 4 hours to obtain a resin layer-forming composition (A). Polyfunctional acrylate monomer [dipentaerythritol hexaacrylate]: 70 parts [ka] Urethane acrylate resin [EBECRYL 4858 (manufactured by Daicel Allnex Co., Ltd.)]: 30 parts Polymerization initiator [2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one [Omnirad 907 (IGM Resins BV)]]: 3 parts Solvent [methyl ethyl ketone]: 10 parts

[0167] After subjecting the surface of the diffusion prevention layer (1) to plasma treatment, the composition for forming a photoalignment film was applied using a slot die coater to form a coating film in a 600 mm wide area at the center of the film. The film was then transported through a ventilated drying oven set at 100°C for 2 minutes to remove the solvent, forming a dry film. The dry film was then irradiated with polarized UV light at 0° to the longitudinal direction of the film at 20 mJ / cm. 2 The optical alignment film was formed by applying an alignment control force to the film by irradiation at an intensity of 313 nm (based on 313 nm). The thickness of the optical alignment film was approximately 50 nm.

[0168] The liquid crystal composition was further coated on the obtained photo-alignment film using a slot die coater to form a coating film in a 600 mm wide area at the center of the film. The film was then transported through a ventilated drying oven set at 110°C for 2 minutes to remove the solvent and form a dry film. Then, ultraviolet light of 1000 mJ / cm was applied using a high-pressure mercury lamp. 2 The polymerizable liquid crystal compound contained in the dried film was cured by irradiation with light at 365 nm (reference wavelength), thereby forming an absorptive polarizer layer. The thickness of the obtained absorptive polarizer layer was 2 μm.

[0169] The film was then continuously wound into a roll to obtain a long laminate with an absorption axis in the 0° direction. Furthermore, after plasma treatment was performed on the absorptive polarizer layer, a polyvinyl alcohol-based resin composition (Mitsubishi Chemical Corporation, Z-200) and glyoxal were mixed in a mass ratio of 92.5:7.5, and then the resulting mixture was mixed with pure water. This mixture was continuously coated using a slot die coater and dried at 100°C for 2 minutes to form a 1 μm thick polyvinyl alcohol-based resin composition film (2) as a second diffusion prevention layer. This resulted in a long laminate (absorptive polarizing plate) comprising a release PET film, diffusion prevention layer (1), photoalignment film, absorptive polarizer layer, and diffusion prevention layer (2) in this order.

[0170] The resulting laminate was cut into a 40 mm x 40 mm square. The diffusion prevention layer (2) side was attached to an alkali-free glass plate (manufactured by Corning Incorporated, product name "Eagle-XG") using a 25 μm thick (meth)acrylic adhesive (manufactured by Lintec Corporation, product name "P-3132"), and the release PET film was peeled off to obtain a measurement sample. The luminous efficacy-corrected polarization index (Py) and luminous efficacy-corrected single transmittance (Ty) of this measurement sample were measured, and the luminous efficacy-corrected polarization index (Py) was 97%, and the luminous efficacy-corrected single transmittance (Ty) was 42%.

[0171] 4. Preparation of the Adhesive Layer (1) Adhesive layer (1) As the pressure-sensitive adhesive layer (1), a (meth)acrylic pressure-sensitive adhesive layer having a thickness of 25 μm was prepared by the following steps. (i) Preparation of Pressure-Sensitive Adhesive Composition (1) A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube was charged with 97.0 parts by mass of n-butyl acrylate, 1.0 part by mass of acrylic acid, 0.5 parts by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the reaction vessel was replaced with nitrogen gas. While stirring under a nitrogen atmosphere, the reaction solution was heated to 60°C and reacted for 6 hours, after which it was cooled to room temperature. The weight-average molecular weight of a portion of the resulting solution was measured, confirming the formation of a (meth)acrylic acid ester polymer with a molecular weight of 1.8 million.

[0172] 100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth)acrylic acid ester polymer obtained in the above process, 0.30 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate (registered trademark) L") as an isocyanate-based crosslinking agent, and 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") as a silane coupling agent were mixed, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of pressure-sensitive adhesive composition (1).

[0173] (ii) Formation of adhesive layer (1) The coating solution was applied to the release-treated surface (release layer surface) of a separator (SP-PLR382190, manufactured by Lintec Corporation) using an applicator so that the thickness after drying would be 15 μm, and then dried at 100° C. for 1 minute. Another separator (SP-PLR381031, manufactured by Lintec Corporation) was laminated to the side of the pressure-sensitive adhesive layer opposite to the side with the separator laminated thereto, thereby obtaining a pressure-sensitive adhesive layer with a double-sided separator. The elastic modulus G' of the pressure-sensitive adhesive layer (1) at a temperature of 25° C. was 25.1 kPa.

[0174] (2) Adhesive layer (2) A 15 μm thick (meth)acrylic pressure-sensitive adhesive layer (2) was produced using the same process as for the pressure-sensitive adhesive layer (1). The pressure-sensitive adhesive layer (2) had an elastic modulus G′ of 25.1 kPa at a temperature of 25° C.

[0175] (3) Adhesive layer (3) As the pressure-sensitive adhesive layer (3), a (meth)acrylic pressure-sensitive adhesive layer having a thickness of 15 μm was prepared by the following steps. (i) Preparation of Pressure-Sensitive Adhesive Composition (2) A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube was charged with 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, and the air in the reaction vessel was replaced with nitrogen gas. While stirring under a nitrogen atmosphere, the reaction solution was heated to 60°C and reacted for 6 hours, after which it was cooled to room temperature. The weight-average molecular weight of a portion of the resulting solution was measured, confirming the formation of a (meth)acrylic acid ester polymer with a molecular weight of 1.8 million.

[0176] 100 parts by mass (solid content equivalent; the same applies below) of the (meth)acrylic acid ester polymer obtained in the above step, 1.5 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate (registered trademark) 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 Co., Ltd.: trade 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 (registered trademark) 907) as a photopolymerization initiator were mixed, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of adhesive composition (2).

[0177] The coating solution was applied to the release-treated surface (release layer surface) of a separator (SP-PLR382190 manufactured by Lintec Corporation) using an applicator so that the thickness after drying would be 5 μm, and then dried at 100° C. for 1 minute. Another separator (SP-PLR381031 manufactured by Lintec Corporation) was then attached to the side of the adhesive layer opposite to the side to which the separator was attached. UV light (irradiation intensity 500 mW / cm ) was applied to this adhesive layer through the release sheet using a UV irradiation device with a belt conveyor (manufactured by Fusion UV Systems, Inc.; the lamp was a D bulb). 2 , cumulative light intensity 500mJ / cm 2 ) to obtain a pressure-sensitive adhesive layer (3) with a double-sided separator. The pressure-sensitive adhesive layer (3) had an elastic modulus G' of 106 kPa at a temperature of 25°C.

[0178] (4) Adhesive layer (4) A 5 μm thick (meth)acrylic pressure-sensitive adhesive layer (4) was produced using the same process as for the pressure-sensitive adhesive layer (3). The pressure-sensitive adhesive layer (4) had an elastic modulus G′ of 106 kPa at a temperature of 25° C.

[0179] 5. Fabrication or Preparation of Thermoplastic Resin Film (1) Thermoplastic resin film (1): 20 μm thick triacetyl cellulose (TAC) film (Fujifilm, Tg: 170°C) (2) Thermoplastic resin film (2): A 60 μm thick (meth)acrylic resin film (Tg: 105 ° C.) prepared by melt extrusion according to JP 2013-254133 A (3) Thermoplastic resin film (3): 13 μm thick cyclic polyolefin resin (COP) film (ZF12 manufactured by Zeon Corporation, Tg: 135 ° C.)

[0180] 6. Preparation of Light-curable Adhesive (1) Light-curing adhesive (1) The following components were blended and mixed, and then degassed to prepare adhesive (1). 4-Hydroxybutyl acrylate (product name: 4HBA, manufactured by xxx Co., Ltd.): 30 parts by mass ·UV7605B (Product name: Shiko UV7605B, manufactured by Mitsubishi Chemical Corporation): 14 parts by mass Dipentaerythritol polyacrylate (product name: A-9550, manufactured by Shin-Nakamura Chemical Co., Ltd.): 56 parts by mass Radical polymerization initiator (product name: Omnirad819): 3.0 parts by mass The adhesive layer formed from the photocurable adhesive (1) had an elastic modulus of 3050 kPa.

[0181] (2) Light-curing adhesive (2) The following components were blended and mixed to prepare adhesive (2). 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "CEL2021P" obtained from Daicel Corporation): 32.5 parts by mass 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (trade name "EHPE3150" available from Daicel Corporation): 7.5 parts by mass 3-Ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (trade name "OXT-221" obtained from Toagosei Co., Ltd.): 60.0 parts by mass Triarylsulfonium salt (trade name "CPI-100P" available from San-Apro Co., Ltd., 50% by weight propylene carbonate solution): 2.25 parts by mass 1,4-diethoxynaphthalene (trade name "Anthracure ET2201" obtained from Kawasaki Kasei Chemical Industries, Ltd.): 2 parts by mass The adhesive layer formed from the photocurable adhesive (2) had an elastic modulus of 2400 kPa.

[0182] 7. Fabrication of Composite Polarizer (1) Comparative Example 1: Preparation of Composite Polarizing Plate 1 According to Example 2 of JP 2018-124467, TMThe polarizing film-forming composition was directly applied onto the brightness-enhancing film APF, followed by curing and laminating an absorptive polarizer to produce Composite Polarizing Plate 1. Composite Polarizing Plate 1 has a layer structure of a reflective polarizing plate / photo-alignment film / absorptive polarizer layer.

[0183] (2) Examples 1 to 4: Preparation of Composite Polarizing Plates 2 to 5 Composite polarizing plates 2 to 5 used in Examples 1 to 4 were made of the above-mentioned 3M TM The brightness-enhancing film APF was prepared by laminating an absorptive polarizing film with adhesive layers (1) to (4) interposed between them. The reflective axis of the APF was aligned with the absorption axis of the absorptive polarizing film. The adhesive layers (1) to (4) were laminated on the anti-diffusion layer (2) side of the absorptive polarizer. The surface to be laminated with the adhesive layer and the adhesive layer surface were each subjected to corona treatment. The same corona treatment was also performed in the preparation of the following composite polarizing plates. Composite polarizing plates 2 to 5 each consisted of a reflective polarizing plate / adhesive layers (1) to (4) / anti-diffusion layer (2) / absorptive polarizer layer / photo-alignment film / anti-diffusion layer (1) / release film.

[0184] (3) Example 5: Preparation of Composite Polarizing Plate 6 The release PET film adjacent to the diffusion prevention layer (1) of the composite polarizing plate 5 was peeled off, and this peeled surface was laminated with a thermoplastic resin film (1) via a pressure-sensitive adhesive layer (4) to produce a composite polarizing plate 6. The composite polarizing plate 6 has a layer structure of a reflective polarizing plate / pressure-sensitive adhesive layer (4) / diffusion prevention layer (2) / absorptive polarizer layer / photoalignment film / diffusion prevention layer (1) / pressure-sensitive adhesive layer (4) / thermoplastic resin film (1).

[0185] (4) Example 6: Preparation of Composite Polarizing Plate 7 The diffusion prevention layer (2) of the absorptive polarizer layer and the thermoplastic resin film (1) were laminated via a pressure-sensitive adhesive layer (4). The release PET film adjacent to the diffusion prevention layer (1) of this laminate was peeled off, and the peeled surface and the 3M TMThe brightness enhancing film APF was laminated with the adhesive layer (4) to prepare a composite polarizing plate 7. The composite polarizing plate 7 has a layer structure of a reflective polarizing plate / adhesive layer (4) / anti-diffusion layer (1) / photo-alignment film / absorptive polarizer layer / anti-diffusion layer (2) / adhesive layer (4) / thermoplastic resin film (1).

[0186] (5) Examples 7 to 9: Preparation of Composite Polarizing Plates 8 to 10 The diffusion prevention layer (2) adjacent to the absorptive polarizer was subjected to a corona treatment. The thermoplastic resin film (1) was also subjected to a corona treatment. Next, the photocurable adhesive (1) was applied to the diffusion prevention layer (2) that had been subjected to the corona treatment in a thickness of 2 μm using a bar coater, and the layer was laminated with the thermoplastic resin film (1). Furthermore, an ultraviolet light irradiation device was used to apply the photocurable adhesive (1) to a thickness of 500 mJ / cm. 2 The photocurable adhesive (1) was cured by irradiating the surface of the thermoplastic resin film (1) with ultraviolet light (365 nm as the reference wavelength) to obtain a composite polarizing plate 8. The composite polarizing plate 8 has a layer structure of a reflective polarizing plate / adhesive layer (4) / anti-diffusion layer (1) / photo-alignment film / absorptive polarizer layer / anti-diffusion layer (2) / photocurable adhesive layer (1) / thermoplastic resin film (1). Similarly, composite polarizing plate 9 was obtained by using thermoplastic resin film (2) instead of thermoplastic resin film (1), and composite polarizing plate 10 was obtained by using thermoplastic resin film (3). Composite polarizing plates 9 and 10 each have a layer structure of reflective polarizing plate / adhesive layer (4) / anti-diffusion layer (1) / photo-alignment film / absorptive polarizer layer / anti-diffusion layer (2) / photo-curable adhesive layer (1) / thermoplastic resin film (2) or (3), respectively.

[0187] (6) Examples 10 and 11: Preparation of Composite Polarizing Plates 11 and 12 The second diffusion prevention layer of the absorptive polarizing film was subjected to a corona treatment. The thermoplastic resin film (2) was also subjected to a corona treatment. Next, the photocurable adhesive (2) was applied to the diffusion prevention layer (2) of the absorptive polarizing film that had been subjected to the corona treatment in a thickness of 2 μm using a bar coater, and the thermoplastic resin film (2) was laminated. Furthermore, an ultraviolet light irradiation device was used to apply the photocurable adhesive (2) to a thickness of 500 mJ / cm.2 The photocurable adhesive (2) was cured by irradiating the surface of the thermoplastic resin film (2) with ultraviolet light (365 nm as the reference wavelength) to obtain a composite polarizing plate 11. The composite polarizing plate 11 has a layer structure of a reflective polarizing plate / adhesive layer (4) / anti-diffusion layer (1) / photo-alignment film / absorptive polarizer layer / anti-diffusion layer (2) / photocurable adhesive layer (2) / thermoplastic resin film (2). Similarly, a composite polarizing plate 12 was obtained by using a thermoplastic resin film (3) instead of the thermoplastic resin film (2). The composite polarizing plate 12 has a layer structure of a reflective polarizing plate / adhesive layer (4) / anti-diffusion layer (1) / photo-alignment film / absorptive polarizer layer / anti-diffusion layer (2) / photo-curable adhesive layer (2) / thermoplastic resin film (3).

[0188] 8. Evaluation of composite polarizer (1) High-temperature heating evaluation The composite polarizing plates 1 to 12 prepared above were cut into 80 x 80 mm pieces. For composite polarizing plates 2 to 5, the release PET film adjacent to the diffusion prevention layer (1) was peeled off, and the plates were then placed in a thermostatic oven at 150°C for 3 minutes. After removing the plates from the oven after 3 minutes, the composite polarizing plates 1 to 12 were visually inspected for any changes in appearance and evaluated according to the following criteria. The results are shown in Table 1. A: No change B: Slight wrinkles C: Large wrinkles have appeared D: Peeling occurred between layers of the composite polarizing plate.

[0189] (2) Dent test A dent test was conducted to simulate foreign matter or external pressure during roll winding. Composite polarizers 1 to 12 were cut into 40 x 40 mm pieces, and for composite polarizers 2 to 5, the release PET film was peeled off to expose the diffusion prevention layer (1). A dent test using an Erichsen pen was conducted on the surface of the composite polarizer that was not the reflective polarizer (APF). After pressing with an Erichsen pen, the diffusion prevention layer (1) was evaluated based on the state of the dents made thereon according to the following criteria. The results are shown in Table 1. A: No problems in the 3N Erichsen pen test (no dents left) B: There was no problem at 1N, but after testing at 3N, the first diffusion prevention layer remained pressed in and after 30 minutes, a slight dent remained or a slight crack occurred. C: There was no problem at 1N, but after testing at 3N, the first diffusion prevention layer remained pressed in and did not return to its original position even after 30 minutes had passed, or cracks occurred. D: After pressing with an Eriksen pen at a strength of 1N, the product remains pressed in for 30 minutes and does not return to its original position, or a crack occurs.

[0190] (3) Appearance evaluation after thermoforming The prepared composite polarizing plates 1 to 12 were each cut to a size of 100 x 100 mm and subjected to thermoforming using a Formech 450DT vacuum forming machine. The mold used was a plano-convex lens (manufactured by Thorlabs, product name "LA1608"), and the heater temperature during molding was 140°C for approximately 10 seconds to perform vacuum forming. After molding, the composite polarizing plates 1 to 12 were visually observed, and their appearance was evaluated according to the following criteria. The results are shown in Table 1. A: Molding was possible and no cracks occurred. B: Molding was successful, but cracks occurred inside the composite polarizing plate. C: It was not possible to mold it into the same shape as the plano-convex lens used as the mold.

[0191] [Table 1] [Explanation of symbols]

[0192] 1:Reflective polarizing plate 2: Adhesive layer 1 3: Absorptive polarizer 4: Diffusion prevention layer 5: Alignment film 6:Adhesive layer 7: Optical film 11: Composite polarizer 12: Absorption polarizer

Claims

1. A composite polarizing plate including a reflective polarizing plate, a pressure-sensitive adhesive layer 1, and an absorptive polarizer in this order, the reflective polarizing plate is a stretched film, the absorptive polarizer is a cured film of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, The composite polarizing plate has an elastic modulus of the pressure-sensitive adhesive layer 1 at 25°C of 20 to 600 kPa.

2. 2. The composite polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer 1 has a modulus of elasticity per unit film thickness at 25° C. of 1 to 30 kPa / μm.

3. 2. The composite polarizing plate according to claim 1, further comprising an optical film on the surface of the absorptive polarizer opposite to the pressure-sensitive adhesive layer via a pressure-sensitive adhesive layer.

4. The composite polarizing plate according to claim 3 , wherein the adhesive layer is an adhesive layer.

5. 4. The composite polarizing plate according to claim 3, wherein the optical film is a thermoplastic resin film.

6. 4. The composite polarizing plate according to claim 3, wherein the optical film is a thermoplastic resin film having a glass transition temperature of 80 to 180°C.

7. 4. The composite polarizing plate according to claim 3, wherein the optical film has a thickness of 10 to 90 μm.

8. 10. The composite polarizer of claim 1 for use in a VR display device.

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