Laminate and method of manufacturing the same

Abstract

To provide a laminate having a liquid crystal layer between two adhesive layers that can prevent occurrence of light leakage after a durability test.SOLUTION: A laminate having a polarizer, a first adhesive layer, a liquid crystal layer, and a second adhesive layer in this order has cracks in an end region of the liquid crystal layer and satisfies the formula: N+(Dm×1.34)<120 [in this formula, N represents the number of cracks with a depth of 20 μm or more from the end in a plan view among the cracks per 10 mm end length of the laminate, and Dm represents the greatest depth [μm] among the depths of the counted cracks].SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a laminate and a method for producing the same. [Background technology]

[0002] Patent Document 1 proposes a retardation film having an optically anisotropic layer containing a liquid crystal compound. Patent Document 2 proposes a method for producing a wide-viewing angle polarizing plate by heat-treating an optical compensation film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-146367 A [Patent Document 2] JP 2005-221551 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a laminate having a liquid crystal layer between two pressure-sensitive adhesive layers, light leakage may occur after a durability test.

[0005] An object of the present invention is to provide a laminate having a liquid crystal layer between two pressure-sensitive adhesive layers, in which the occurrence of light leakage is suppressed after a durability test. [Means for solving the problem]

[0006] The present invention provides the following aspects [1] to

[10] . [1] A laminate having, in this order, a polarizing plate, a first pressure-sensitive adhesive layer, a liquid crystal layer, and a second pressure-sensitive adhesive layer, the laminate has cracks in edge regions of the liquid crystal layer, A laminate satisfying the following formula (1): N+(Dm×1.34)<120 (1) [In the formula, N represents the number of cracks having a depth of 20 μm or more from the end in a plan view per 10 mm of the end length of the laminate, Dm represents the maximum depth [μm] of the counted number of cracks.][2] The laminate according to [1], wherein the liquid crystal layer has a layer containing a cured product of a polymerizable liquid crystal compound. [3] The laminate according to [1] or [2], wherein the liquid crystal layer further comprises an alignment layer. [4] The laminate according to [2] or [3], wherein at least one end of the crack is present at an end of the liquid crystal layer that intersects with the alignment direction of the polymerizable liquid crystal compound. [5] The laminate according to any one of [1] to [4], wherein the laminate is in a sheet form. [6] The laminate according to any one of [1] to [5], wherein the laminate has polished end faces. [7] An image display device comprising the laminate according to any one of [1] to [6]. [8] A method for producing a laminate according to any one of [1] to [6], A preparation step of preparing a liquid crystal layer and a polarizing plate; a lamination step of laminating the liquid crystal layer to a polarizing plate via a first pressure-sensitive adhesive layer and providing a second pressure-sensitive adhesive layer on the opposite side of the liquid crystal layer to the first pressure-sensitive adhesive layer to obtain a laminate; A cutting step of cutting the laminate; and The manufacturing method includes a polishing step of polishing an edge of the laminate. [9] The polishing step comprises: A first step of stacking a plurality of laminates to obtain a laminate; and A second step of cutting the end surface of the obtained laminate by moving a cutting tool having a cutting blade, which rotates around a rotation axis, relative to the laminate along the length direction of the end surface of the obtained laminate. The method for producing a semiconductor device according to [8],

[10] The manufacturing method described in [9], wherein in the second step, the incident angle of the cutting blade when the end of the cutting blade in the outer direction of the rotation radius contacts the laminate is greater than -30 degrees and less than 30 degrees. Effect of the Invention

[0007] According to the present invention, it is possible to provide a laminate having a liquid crystal layer between two pressure-sensitive adhesive layers, in which the occurrence of light leakage is suppressed after a durability test. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic cross-sectional view of a laminate according to another embodiment of the present invention. [Diagram 3] 1(A) to 1(E) are schematic cross-sectional views illustrating an example of each production step in the production method of the composite retardation plate of the present invention. [Figure 4] 1A and 1B are a side view and a front view showing an example of a cutting tool. [Diagram 5] FIG. 13 is a side view showing the angle of incidence of the cutting blade with respect to the stack. [Figure 6] 5 is an exploded view showing details of a cutting part of the cutting tool shown in FIG. 4. [Figure 7] 5 is a schematic perspective view showing an example of an end face processing device equipped with the cutting tool shown in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment. In all of the drawings, the scale of each component is appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[0010] <Laminate> Fig. 1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention. The laminate 100 shown in Fig. 1 has a polarizing plate 101, a first adhesive layer 102, a liquid crystal layer 103, and a second adhesive layer 104, in this order.

[0011] The laminate 100 may further include layers other than the layers described above. Examples of the other layers include a protective film that can be disposed on the outer side of the polarizing plate 101 of the laminate 100 (the side opposite to the first adhesive layer 102).

[0012] The thickness of the laminate 100 is not particularly limited as it varies depending on the function required of the laminate 100 and the use of the laminate 100, but may be, for example, 25 μm or more and 1000 μm or less, preferably 100 μm or more and 500 μm or less, and more preferably 100 μm or more and 300 μm or less.

[0013] The laminate 100 may be in a long shape or in a sheet-like shape. The laminate 100 is preferably in a sheet-like shape. A sheet-like laminate can be obtained by cutting a long laminate. When the laminate 100 is in a sheet-like shape, the shape of the laminate 100 in a plan view may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangle. When the shape of the laminate 100 in a plan view is a rectangle, the length of the long side is, for example, 1 The length of the short side is, for example, 5 mm or more and 800 mm or less, preferably 30 mm or more and 500 mm or less, and more preferably 50 mm or more and 300 mm or less. In this specification, a plan view means a view from the thickness direction of a layer.

[0014] When the laminate 100 is in a sheet-like form, the laminate 100 preferably has polished end faces for the purpose of removing fuzz and the like that occurs on the end faces of the laminate during cutting and from the viewpoint of dimensional accuracy. A part or all of the end faces of the laminate 100 may be polished when viewed from above, and preferably all of the end faces are polished. Furthermore, when the laminate 100 has a rectangular shape in plan view, the lengths of the sides of the layers constituting the laminate 100 may be the same. The corners of the layers constituting the laminate 100 may be rounded, or the ends may be notched or perforated.

[0015] The laminate 100 can be used in an image display device. The image display device may be any type, such as a liquid crystal display device or an organic EL display device. The laminate 100 can be disposed on the front side (viewing side) or the back side of the image display device. Since the light leakage described below is easily visible when the laminate 100 is disposed on the front side (viewing side) of the image display device, the laminate 100 is preferably disposed on the front side of the image display device. When the image display device is a liquid crystal display device, the laminate 100 can be disposed as a laminate including a polarizing plate disposed on the front side of the front side or the back side of the liquid crystal cell. When the image display device is an organic EL display device, the laminate 100 can be disposed on the front side as a circular polarizing plate disposed on the front side for the purpose of preventing reflection of external light.

[0016] The laminate 100 may be, for example, a laminate having anti-reflection properties. An example of a laminate having anti-reflection properties is a circular polarizing plate. In an image display device, by providing a laminate having anti-reflection properties on the front side of the image display device, it is possible to suppress a decrease in visibility due to reflection of external light.

[0017] The laminate has a crack in the edge region of the liquid crystal layer. In the present invention, the crack is a crack observed linearly in the edge region of the liquid crystal layer when the laminate is observed in plan view with transmitted light of an optical microscope, and does not include cracks observed in a polarizing plate, a hard coat layer, or the like. The crack may or may not penetrate in the thickness direction. In addition, the crack refers to a crack in which at least one end of the crack is present at an end of the liquid crystal layer intersecting with the alignment direction of the polymerizable liquid crystal compound. The end of the liquid crystal layer intersecting with the alignment direction of the liquid crystal compound refers to a side of the laminate in a direction that is not parallel to the alignment direction of the liquid crystal compound in the liquid crystal layer, for example, when the laminate is rectangular. The shape of the crack is not particularly limited, and is usually observed as a line shape, for example, a straight line shape, a folded line shape, a curved shape, or a shape that is a combination of these. For example, it may be a straight line, a folded line, or a curved line, or a straight line, a folded line, or a curved line from which multiple straight lines, folded lines, and / or curved lines branch, or a combination of these. In any shape, at least one end of the straight line, bent line or curved line constituting the crack is present at an end of the liquid crystal layer that intersects with the alignment direction of the polymerizable liquid crystal compound.

[0018] The laminate satisfies the following formula (1). N+(Dm×1.34)<120 (1) When the laminate satisfies formula (1), the laminate has excellent durability. In the formula, N represents the number of cracks present in the edge region of the liquid crystal layer, the number of cracks having a depth of 20 μm or more from the edge in a plan view, per 10 mm of edge length (hereinafter also referred to as the number of cracks). The number of cracks N is determined by observing the crack with transmitted light through an optical microscope, when the crack is a combination of multiple straight lines, folded lines, and / or curves, that is, when at least one of the straight lines, folded lines, and curves constituting the crack is connected to another straight line, folded line, or curve at at least one point. If two lines intersect, they are counted as one. In the present invention, the depth from the edge in plan view refers to the minimum value D of the linear distance from a point on a crack observed in plan view to the edge of the liquid crystal layer intersecting the alignment direction of the polymerizable liquid crystal compound. Dm means the maximum depth [μm] (hereinafter also referred to as maximum depth) of the cracks counted in number. When formula (1) is satisfied, the maximum crack depth Dm is less than 90 μm. The upper limit of the number N of cracks may be, for example, 20 or less, preferably 18 or less, and more preferably 15 or less. On the other hand, the lower limit of the number N of cracks is, for example, preferably 1 or more, and more preferably 3 or more. The maximum depth Dm of the crack may be, for example, 85 μm or less, and is preferably 80 μm or less.

[0019] The present inventors have found that, for example, when the end faces of a laminate are polished, light leakage tends to occur around the end faces of the laminate after a durability test is performed on the laminate. This is because cracks that occur around the end faces of the laminate that are not parallel to the alignment direction of the liquid crystal layer become larger during the durability test and are observed as light leakage. As a result of intensive research focusing on these cracks, the inventors have found that light leakage after a durability test tends to be suppressed when the maximum depth and number of cracks satisfy the relationship shown in the above formula (1), and have completed the present invention. The durability test in the present invention refers to a test carried out according to the method explained in the examples described later.

[0020] From the viewpoint of durability, the laminate preferably satisfies the following formula (1'). N+(Dm×1.34)<111 (1') When formula (1') is satisfied, the maximum crack depth Dm is less than 83 μm.

[0021] For example, the manufacturing conditions of the laminate can be adjusted so that the laminate satisfies formula (1) or formula (1'). For example, in the polishing process, the feed speed, the approach direction of the cutting blade to the laminate, the rotation speed, the approach angle, etc. can be adjusted as described later.

[0022] [Polarizing plate] The polarizing plate 101 may be any film having a polarizing function that obtains linearly polarized light from transmitted light. Examples of such films include stretched films adsorbed with a dye having absorption anisotropy, or films containing a film coated with a dye having absorption anisotropy as a polarizer. Examples of dyes having absorption anisotropy include dichroic dyes. Examples of films coated with a dye having absorption anisotropy that are used as polarizers include stretched films adsorbed with a dye having absorption anisotropy, or films having a liquid phase layer obtained by applying a composition containing a dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal to a substrate film.

[0023] (1) Stretched film adsorbed with a dye having anisotropic absorption A polarizer, which is a stretched film having a dye having absorption anisotropy adsorbed thereon, can usually be produced through a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, a process of treating the polyvinyl alcohol-based resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution, and a process of washing with water after the treatment with the aqueous boric acid solution. The thickness of the polarizer is, for example, 2 μm or more and 40 μm or less. The thickness of the polarizer may be 5 μm or more, and may be 20 μm or less, further 15 μm or less, or further 10 μm or less.

[0024] Polyvinyl alcohol resins are obtained by saponifying polyvinyl acetate resins. Polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers that can be copolymerized with vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

[0025] The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000.

[0026] Such a polyvinyl alcohol-based resin is used as a raw film for a polarizer. The method for forming a film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a known method. The thickness of the polyvinyl alcohol-based raw film can be, for example, about 10 to 150 μm.

[0027] The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during the boric acid treatment. It is also possible to perform the uniaxial stretching at these multiple stages. In the uniaxial stretching, the film may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a heated roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state where the polyvinyl alcohol-based resin film is swollen using a solvent. The stretching ratio is usually about 3 to 8 times.

[0028] Dyeing of a polyvinyl alcohol-based resin film with a dichroic dye is performed, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. Specific examples of the dichroic dye include iodine and dichroic organic dyes. Dichroic organic dyes include dichroic direct dyes made of disazo compounds such as CIDIRECT RED 39, and dichroic direct dyes made of compounds such as trisazo and tetrakisazo. It is preferable that the polyvinyl alcohol-based resin film is immersed in water before the dyeing process.

[0029] When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol resin film by immersing it in an aqueous solution containing iodine and potassium iodide is usually adopted. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by mass per 100 parts by mass of water. The content of potassium iodide is usually about 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40°C. The immersion time in this aqueous solution (dyeing time) is usually about 20 to 1,800 seconds.

[0030] On the other hand, when a dichroic organic dye is used as the dichroic pigment, a method of dyeing a polyvinyl alcohol resin film by immersing it in an aqueous solution containing a water-soluble dichroic dye is usually adopted. The content of the dichroic organic dye in this aqueous solution is usually 1×10 -4 ~10 parts by mass, preferably 1 × 10 -3 ~1 part by mass, more preferably 1 × 10 -3 ~1×10 -2 The amount of each component is expressed as parts by mass. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80°C. The immersion time in this aqueous solution (dyeing time) is usually about 10 to 1,800 seconds.

[0031] The boric acid treatment after dyeing with a dichroic dye can usually be carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The content of boric acid in this aqueous boric acid solution is usually about 2 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, this aqueous boric acid solution preferably contains potassium iodide, and in this case, the content of potassium iodide is usually about 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the aqueous boric acid solution is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid treatment is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

[0032] The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The washing can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of the water used in the washing is usually about 5 to 40° C. The immersion time is usually about 1 to 120 seconds.

[0033] After washing with water, a drying treatment is carried out to obtain a polarizer. The drying treatment can be carried out, for example, using a hot air dryer or a far-infrared heater. The temperature of the drying treatment is usually about 30 to 100°C, and preferably 50 to 80°C. The time of the drying treatment is usually about 60 to 600 seconds, and preferably 120 to 600 seconds. The moisture content of the polarizer is reduced to a practical level by the drying treatment. The moisture content is usually about 5 to 20 mass%, and preferably 8 to 15 mass%. If the moisture content is less than 5 mass%, the polarizer loses its flexibility, and the polarizer may be damaged or broken after drying. If the moisture content exceeds 20 mass%, the thermal stability of the polarizer may be deteriorated.

[0034] The polyvinyl alcohol-based resin film is then uniaxially stretched, dyed with a dichroic dye, treated with boric acid, washed with water and dried to obtain a polarizer having a thickness preferably of 5 to 40 μm.

[0035] A thermoplastic resin film may be attached to one or both sides of the polarizer. The material of the thermoplastic resin film attached to one or both sides of the polarizer is not particularly limited, and examples thereof include films known in the art, such as cyclic polyolefin resin films, cellulose acetate resin films made of resins such as triacetyl cellulose and diacetyl cellulose, polyester resin films made of resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, polycarbonate resin films, (meth)acrylic resin films, and polypropylene resin films. From the viewpoint of thinning, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, and usually 5 μm or more, and preferably 20 μm or more.

[0036] The thermoplastic resin film may have a function as a protective film. The thermoplastic resin film may also be a protective film having optical functions such as a retardation film and a brightness improving film. For example, a transparent resin film made of the above material may be stretched (uniaxially stretched or biaxially stretched, etc.) or a liquid crystal layer may be formed on the film to form a retardation film having an arbitrary retardation value. When a laminate having a thermoplastic resin film is used in a display device, the thermoplastic resin film arranged on the viewing side may or may not have a retardation. On the other hand, when the protective film on the side laminated to the retardation layer has a retardation, the retardation is preferably 10 nm or less.

[0037] The thermoplastic resin film may have a hard coat layer formed thereon. The hard coat layer may be formed on one side of the thermoplastic resin film, or may be formed on both sides. By providing a hard coat layer, the thermoplastic resin film can be improved in hardness and scratch resistance. The hard coat layer is, for example, a cured layer of an ultraviolet curing resin. Examples of the ultraviolet curing resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard coat layer may contain additives to improve strength. The additives are not limited, and examples include inorganic fine particles, organic fine particles, and mixtures thereof.

[0038] The polarizing plate 101 may be a polarizer having thermoplastic resin films attached (laminated) on both sides thereof via an adhesive layer. Examples of adhesives used for attaching the polarizer and the thermoplastic resin films include active energy ray-curable adhesives such as ultraviolet-curable adhesives, aqueous solutions of polyvinyl alcohol-based resins or aqueous solutions containing a crosslinking agent, and water-based adhesives such as urethane-based emulsion adhesives. When the thermoplastic resin films are attached to both sides of the polarizer, the adhesives forming the two adhesive layers may be the same or different. For example, when the thermoplastic resin films are attached to both sides, one side may be attached using an aqueous adhesive, and the other side may be attached using an active energy ray-curable adhesive. The ultraviolet-curable adhesive may be a mixture of a radically polymerizable (meth)acrylic compound and a photoradical polymerization initiator, or a mixture of a cationic polymerizable epoxy compound and a photocationic polymerization initiator. It is also possible to use a cationic polymerizable epoxy compound and a radically polymerizable (meth)acrylic compound in combination, and to use a photocationic polymerization initiator and a photoradical polymerization initiator in combination as initiators.

[0039] When an active energy ray curable adhesive is used, the adhesive is cured by irradiating it with active energy rays after lamination. The light source of the active energy rays is not particularly limited, but active energy rays (ultraviolet rays) having an emission distribution of wavelengths of 400 nm or less are preferred, and specifically, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps, etc. are preferably used.

[0040] In order to improve the adhesion between the polarizer and the thermoplastic resin film, prior to bonding of the polarizer and the thermoplastic resin film, the bonding surfaces of the polarizer and / or the thermoplastic resin film may be subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, primer coating treatment, and saponification treatment.

[0041] As described above, the polarizing plate can be produced by laminating a thermoplastic resin film to a polarizer that is a single-layer film, but the method is not limited to this method. For example, the polarizing plate can be produced by a method using a base film, as described in JP-A-2009-98653. The latter method is advantageous for obtaining a polarizing plate having a thin film polarizer (polarizer layer), and can include, for example, the following steps.

[0042] a resin layer forming step of applying a coating liquid containing a polyvinyl alcohol-based resin to at least one surface of a substrate film and then drying the applied liquid to form a polyvinyl alcohol-based resin layer to obtain a laminated film; A stretching step of stretching the laminated film to obtain a stretched film; a dyeing step of dyeing the polyvinyl alcohol-based resin layer of the stretched film with a dichroic dye to form a polarizer layer (corresponding to a polarizer) to obtain a polarizing laminate film; a first lamination step of laminating a thermoplastic resin film onto a polarizer layer of the polarizing laminate film using an adhesive to obtain a laminated film; The base film is peeled off from the laminated film to obtain a polarizing plate with a thermoplastic resin film on one side. A peeling process is performed. In the dyeing step, zinc element can be incorporated into the polarizer by adding a zinc salt to the treatment liquid containing the dichroic dye.

[0043] When a thermoplastic resin film is laminated on both sides of the polarizer layer (polarizer), a second lamination step is further included in which another thermoplastic resin film is laminated to the polarizer surface of the polarizing plate with a thermoplastic resin film on one side using an adhesive.

[0044] In the above method using a substrate film, a drying step can be included in the dyeing step for obtaining a polarizing laminate film (for example, after a crosslinking step or a washing step during the dyeing step for obtaining a polarizing laminate film). The polarizers contained in the above polarizing laminate film, the polarizing plate with a thermoplastic resin film on one side, and the polarizing plate with thermoplastic resin films on both sides obtained through the second lamination step, or polarizers isolated from these, are also polarizers belonging to the present invention.

[0045] (2) A polarizer formed by applying and curing a dye having anisotropic absorption Examples of polarizers formed by applying and curing a dye having absorption anisotropy include polarizers containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying a composition containing a polymerizable dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal to a substrate film (or an alignment film formed on a substrate film) and curing the composition. If necessary, the substrate film or both the substrate film and the alignment film may be peeled off and removed from the polarizer. The material and thickness of the substrate film may be the same as those of the thermoplastic resin film described above. The polarizer formed by applying and curing a dye having absorption anisotropy may be incorporated into a laminate in a form in which a thermoplastic resin film is attached to one or both sides of the polarizer. As the thermoplastic resin film, a thermoplastic resin film similar to that which can be used in a polarizer that is a stretched film or layer can be used. Specific examples of polarizers formed by applying and curing a dye having absorption anisotropy include those described in JP2014-148883A and the like.

[0046] The thickness of a polarizer formed by coating and curing a dye having absorption anisotropy is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 5 μm or less.

[0047] The polarizing plate 101 may have a luminosity-corrected single transmittance Ty of, for example, 40% or more and 47% or less, and preferably 41% or more and 45% or less. The polarizing plate may have a luminosity-corrected polarization degree Py of, for example, 99.9% or more, and preferably 99.95% or more. If Ty is too high, Py tends to decrease and the display quality of the image display device tends to decrease. If Ty is too low, the luminance of the image display device tends to decrease and the display quality tends to decrease, or it tends to become necessary to increase the input power in order to sufficiently increase the luminance. The luminosity-corrected single transmittance Ty and the luminosity-corrected polarization degree Py can be measured according to the method described in the Examples section below.

[0048] [First adhesive layer] The first adhesive layer 102 can be interposed between the polarizing plate 101 and the liquid crystal layer 103 to bond them together. The first adhesive layer 102 can be composed of an adhesive composition containing as a main component a resin such as a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin. Among them, an adhesive composition containing a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance, etc., is preferable. The adhesive composition may be of an active energy ray curing type or a heat curing type.

[0049] As the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition, for example, a polymer or copolymer containing one or more (meth)acrylic acid esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, is preferably used. It is preferable to copolymerize a polar monomer into the base polymer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0050] The adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include divalent or higher metal ions that form a carboxylate metal salt with a carboxyl group; polyamine compounds that form an amide bond with a carboxyl group; polyepoxy compounds or polyols that form an ester bond with a carboxyl group; and polyisocyanate compounds that form an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferred.

[0051] The first adhesive layer 102 can be formed, for example, by a method in which an adhesive composition is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, which is then directly applied to the target surface of the laminate to form an adhesive layer, or by a method in which an adhesive layer is formed in sheet form on a separate film that has been subjected to a release treatment, and then this is transferred to the target surface of the polarizing plate. The thickness of the first adhesive layer 102 is determined depending on its adhesive strength, etc., but may be, for example, in the range of 1 μm or more and 50 μm or less, preferably 2 μm or more and 40 μm or less, more preferably 3 μm or more and 30 μm or less, and even more preferably 3 μm or more and 25 μm or less.

[0052] The laminate 100 may include the above-mentioned separate film. The separate film may be a film made of a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate, or the like. Among them, a stretched film of polyethylene terephthalate is preferable.

[0053] The first adhesive layer 102 may contain optional components such as glass fibers, glass beads, resin beads, fillers made of metal powder or other inorganic powders, pigments, colorants, antioxidants, UV absorbers, antistatic agents, and the like.

[0054] Examples of the antistatic agent include ionic compounds, conductive fine particles, conductive polymers, etc., with ionic compounds being preferred. The cationic component constituting the ionic compound may be either an inorganic cation or an organic cation. Examples of the organic cation include a pyridinium cation, an imidazolium cation, an ammonium cation, a sulfonium cation, a phosphonium cation, a piperidinium cation, and a pyrrolidinium cation. Examples of the inorganic cation include a lithium ion and a potassium ion. On the other hand, the anion component constituting the ionic compound may be an inorganic anion or an organic anion, but an anion component containing a fluorine atom is preferred because it gives an ionic compound with excellent antistatic performance. As an anion component containing a fluorine atom, a hexafluorophosphate anion [(PF6 - )], bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N - ] anion, bis(fluorosulfonyl)imide anion [(FSO2)2N - ] anion, etc.

[0055] [Liquid crystal layer] The liquid crystal layer 103 preferably has a layer containing a cured product of a polymerizable liquid crystal compound, and more preferably has a layer containing a cured product of a polymer obtained by polymerizing the polymerizable liquid crystal compound in an aligned state. The liquid crystal layer 103 may function as a retardation layer. Examples of the retardation layer include a layer that imparts a retardation of λ / 2, a layer that imparts a retardation of λ / 4 (positive A layer), and a positive C layer. The liquid crystal layer 103 may include an alignment layer and a substrate, which will be described later, or may have two or more liquid crystal layers, alignment layers, and substrates.

[0056] The polymerizable liquid crystal compound is a compound that has a polymerizable group and can be in a liquid crystal state. The polymerizable groups of the polymerizable liquid crystal compound react with each other to polymerize the polymerizable liquid crystal compound, thereby hardening the polymerizable liquid crystal compound.

[0057] (base material) The layer containing the cured product of the polymerizable liquid crystal compound is formed, for example, on an alignment layer provided on a substrate. The substrate may be a substrate having a function of supporting the alignment layer and formed in a long length. This substrate functions as a release support and can support a retardation layer or an alignment layer for transfer. Furthermore, it is preferable that the surface of the substrate has an adhesive strength sufficient to allow peeling. The substrate may be a film made of a light-transmitting (preferably optically transparent) thermoplastic resin, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin, etc.) or a cyclic polyolefin resin (norbornene resin, etc.); a cellulose resin such as triacetyl cellulose or diacetyl cellulose; a polyester resin such as polyethylene terephthalate or polybutylene terephthalate; a polycarbonate resin; a (meth)acrylic resin such as a methyl methacrylate resin; a polystyrene resin; a polyvinyl chloride resin; an acrylonitrile-butadiene-styrene resin; an acrylonitrile-styrene resin; a polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; a modified polyphenylene ether resin; a polysulfone resin; a polyethersulfone resin; a polyarylate resin; a polyamideimide resin; a polyimide resin; a maleimide resin, or the like.

[0058] The thickness of the substrate is not particularly limited, but is preferably in the range of, for example, 20 μm to 200 μm. When the thickness of the substrate is 20 μm or more, strength is imparted.

[0059] The substrate may be subjected to various anti-blocking treatments. Examples of the anti-blocking treatment include an easy-adhesion treatment, a treatment for kneading a filler or the like, and an embossing (knurling) treatment. By subjecting the substrate to such an anti-blocking treatment, it is possible to effectively prevent the substrates from sticking to each other when the substrates are wound up, that is, blocking, and it is possible to manufacture the optical film with high productivity.

[0060] (Alignment layer) The layer containing the cured product of the polymerizable liquid crystal compound is formed on the substrate via the alignment layer. That is, the substrate and the alignment layer are laminated in this order, and the layer containing the cured product of the polymerizable liquid crystal compound is laminated on the alignment layer.

[0061] The alignment layer is not limited to a vertical alignment layer, and may be an alignment layer that aligns the molecular axis of the polymerizable liquid crystal compound horizontally, or may be an alignment layer that aligns the molecular axis of the polymerizable liquid crystal compound at an angle. The alignment layer is preferably one that has solvent resistance that does not dissolve the composition containing the polymerizable liquid crystal compound described later by coating, etc., and has heat resistance in the heat treatment for removing the solvent and orienting the liquid crystal compound. Examples of the alignment layer include an alignment layer containing an orienting polymer, a photoalignment film, and a groove alignment layer that forms a concave-convex pattern or a plurality of grooves on the surface to provide alignment. The thickness of the alignment layer is usually in the range of 10 nm to 10,000 nm.

[0062] The alignment layer has a function of supporting the liquid crystal layer and may function as a releasable support. The alignment layer may be capable of supporting the liquid crystal layer to be transferred and may have an adhesive strength sufficient to allow the surface to be peeled off.

[0063] The resin used for the alignment layer is a resin obtained by polymerizing a polymerizable compound. The polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid crystal polymerizable non-liquid crystal compound that does not become a liquid crystal state. The polymerizable groups of the polymerizable compound react with each other to polymerize the polymerizable compound, thereby forming a resin. Such a resin is not particularly limited as long as it is used as an alignment layer for aligning a polymerizable liquid crystal compound at the liquid crystal layer formation stage, and is not included in the liquid crystal layer, and is a resin used as a material for a known alignment layer, and a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth)acrylate monomer under a polymerization initiator can be used. Specifically, examples of (meth)acrylate monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono 2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, urethane acrylate, etc. The resin may be one of these, or a mixture of two or more of them. After the liquid crystal layer is formed, the alignment layer can be peeled off and removed together with the substrate before or after the step of laminating the liquid crystal layer with other optical films or the like.

[0064] In addition, for the purpose of improving the peelability from the substrate and imparting film strength to the liquid crystal layer, an alignment layer can be included in the liquid crystal layer. When the liquid crystal layer includes an alignment layer, it is preferable to use a cured product obtained by curing a monofunctional or bifunctional (meth)acrylate monomer, imide monomer, or vinyl ether monomer as a resin used for the alignment layer. Examples of monofunctional (meth)acrylate monomers include alkyl (meth)acrylates having 4 to 16 carbon atoms, β-carboxyalkyl (meth)acrylates having 2 to 14 carbon atoms, alkylated phenyl (meth)acrylates having 2 to 14 carbon atoms, methoxypolyethylene glycol (meth)acrylates, phenoxypolyethylene glycol (meth)acrylates, and isobornyl (meth)acrylates. Examples of bifunctional (meth)acrylate monomers include 1,3-butanediol di(meth)acrylate; 1,3-butanediol (meth)acrylate; 1,6-hexanediol di(meth)acrylate; ethylene glycol di(meth)acrylate; diethylene glycol di(meth)acrylate; neopentyl glycol di(meth)acrylate; triethylene glycol di(meth)acrylate; tetraethylene glycol di(meth)acrylate; polyethylene glycol diacrylate; bis(acryloyloxyethyl)ether of bisphenol A; ethoxylated bisphenol A di(meth)acrylate; propoxylated neopentyl glycol di(meth)acrylate; ethoxylated neopentyl glycol di(meth)acrylate, and 3-methylpentanediol di(meth)acrylate. Examples of imide resins obtained by curing imide monomers include polyamide, polyimide, etc. The imide resin may be one of these, or a mixture of two or more of these. The resin forming the alignment layer may contain a monomer other than the monofunctional or bifunctional (meth)acrylate monomer, imide monomer, and vinyl ether monomer. The content of the diethyl ether monomer in the total monomers may be 50% by weight or more, preferably 55% by weight or more, and more preferably 60% by weight or more.

[0065] When the alignment layer is included in the liquid crystal layer 103, the thickness of the alignment layer is usually in the range of 10 nm to 10,000 nm, when the alignment of the liquid crystal layer 103 is in-plane alignment with respect to the film surface, the thickness of the alignment layer is preferably 10 nm to 1,000 nm, and when the alignment of the alignment layer is perpendicular to the film surface, the thickness of the alignment layer is preferably 100 nm to 10,000 nm. When the thickness of the alignment layer is within the above range, it is possible to improve the peelability of the substrate and provide an appropriate film strength.

[0066] (Polymerizable liquid crystal compound) The type of polymerizable liquid crystal compound used in this embodiment is not particularly limited, but can be classified into rod-shaped type (rod-shaped liquid crystal compound) and discotic type (discotic liquid crystal compound) based on their shape. Each type can be further classified into low molecular type and high molecular type. Note that a high molecular weight generally refers to a material with a degree of polymerization of 100 or more (Polymer Physics, Phase Transition Dynamics, Masao Doi, page 2, Iwanami Shoten, 1992).

[0067] In this embodiment, any of the polymerizable liquid crystal compounds may be used. Furthermore, two or more kinds of rod-shaped liquid crystal compounds, two or more kinds of discotic liquid crystal compounds, or a mixture of rod-shaped and discotic liquid crystal compounds may be used.

[0068] As the rod-shaped liquid crystal compound, for example, those described in claim 1 of JP-T-11-513019 can be preferably used. As the discotic liquid crystal compound, for example, those described in paragraphs

[0020] to

[0067] of JP-A-2007-108732 or paragraphs

[0013] to

[0108] of JP-A-2010-244038 can be preferably used.

[0069] Two or more kinds of polymerizable liquid crystal compounds may be used in combination. In that case, at least one kind has two or more polymerizable groups in the molecule. That is, the layer in which the polymerizable liquid crystal compound is hardened is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to show liquid crystallinity after the layer is formed.

[0070] The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. As the polymerizable group, for example, a functional group capable of an addition polymerization reaction, such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group, is preferable. More specifically, as the polymerizable group, for example, a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, etc. can be mentioned. Among them, a (meth)acryloyl group is preferable. Note that the (meth)acryloyl group is a concept that includes both a methacryloyl group and an acryloyl group.

[0071] The liquid crystallinity of the polymerizable liquid crystal compound may be thermotropic liquid crystal or lyotropic liquid crystal, and when the thermotropic liquid crystal is classified according to the degree of order, it may be nematic liquid crystal or smectic liquid crystal.

[0072] The layer containing the cured product of the polymerizable liquid crystal compound can be formed by coating a composition containing the polymerizable liquid crystal compound (hereinafter also referred to as a polymerizable liquid crystal composition) on, for example, an alignment layer, and irradiating it with active energy rays, as described below. The polymerizable liquid crystal composition may contain components other than the above-mentioned polymerizable liquid crystal compound. For example, the polymerizable liquid crystal composition preferably contains a polymerization initiator. The polymerization initiator used is selected, for example, from a thermal polymerization initiator or a photopolymerization initiator, depending on the type of polymerization reaction. For example, the photopolymerization initiator may be an α-carbonyl compound, an acyloin ether, an α-hydrocarbon substituted aromatic acyloin compound, Examples of the polymerization initiator include a polynuclear quinone compound, a combination of triaryl imidazole dimer and p-aminophenyl ketone. The amount of the polymerization initiator used is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, based on the total solid content in the coating liquid. The term "cured product" refers to a state in which the formed layer can exist independently without deformation or flow.

[0073] In addition, the polymerizable liquid crystal composition may contain a polymerizable monomer from the viewpoint of uniformity of the coating film and strength of the film. The polymerizable monomer may be a radically polymerizable or cationic polymerizable compound. Among them, a polyfunctional radically polymerizable monomer is preferable.

[0074] The polymerizable monomer is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. The amount of the polymerizable monomer used is preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 30% by mass or less, based on the total mass of the polymerizable liquid crystal compound.

[0075] The polymerizable liquid crystal composition may contain a surfactant from the viewpoint of uniformity of the coating film and strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine-based compounds are particularly preferable.

[0076] The polymerizable liquid crystal composition may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1,2-dimethoxyethane). Among these, alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

[0077] The polymerizable liquid crystal composition may also contain various alignment agents, such as a vertical alignment promoter such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment promoter such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. Furthermore, the polymerizable liquid crystal composition may also contain an adhesion improver, a plasticizer, a polymer, etc., in addition to the above components.

[0078] The active energy rays include ultraviolet rays, visible light, electron beams, and X-rays, and are preferably ultraviolet rays. 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 the wavelength range of 380 to 440 nm, a chemical lamp, a black light lamp, a microwave excited mercury lamp, and a metal halide lamp.

[0079] The irradiation intensity of ultraviolet light is usually 100 mW / cm for ultraviolet B waves (wavelength range 280 nm to 310 nm). 2 More than 3,000mW / cm 2 The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a cationic polymerization initiator or a radical polymerization initiator. The ultraviolet irradiation time is usually 0.1 seconds or more and 10 minutes or less, preferably 0.1 seconds or more and 5 minutes or less, more preferably 0.1 seconds or more and 3 minutes or less, and further preferably 0.1 seconds or more and 1 minute or less.

[0080] The ultraviolet light can be irradiated once or in multiple steps. The cumulative light dose at a wavelength of 365 nm is 700 mJ / cm2, depending on the polymerization initiator used. 2 More preferably, it is 1,100 mJ / cm or more. 2 More preferably, it is 1,300 mJ / cm or more. 2 It is more preferable that the integrated light amount is 2,000 mJ / cm or more. The integrated light amount is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the liquid crystal layer 103 and improving the heat resistance. The integrated light amount at a wavelength of 365 nm is 2,000 mJ / cm. 2 It is preferable to set the dose to 1,800 mJ / cm or less. 2 It is more preferable that the integrated light amount is set to the above value.

[0081] In this embodiment, the thickness of the liquid crystal layer 103 is preferably 0.5 μm or more. The thickness of the liquid crystal layer 103 is preferably 10 μm or less, and more preferably 5 μm or less. The above upper limit and lower limit can be arbitrarily combined. When the thickness of the liquid crystal layer 103 is equal to or greater than the lower limit, sufficient durability can be obtained. When the thickness of the liquid crystal layer 103 is equal to or less than the upper limit, it can contribute to making the laminate 100 thinner. When the liquid crystal layer 103 has a function of a retardation layer, the thickness of the liquid crystal layer 103 can be adjusted so as to obtain the desired in-plane retardation value and thickness direction retardation value of a layer that gives a retardation of λ / 4, a layer that gives a retardation of λ / 2, or a positive C layer. The liquid crystal layer 103 may include a plurality of liquid crystal layers each having different retardation characteristics. Each liquid crystal layer may be laminated via an adhesive or a pressure sensitive adhesive, or a composition containing a polymerizable liquid crystal compound may be applied to the surface of an already formed liquid crystal layer and then cured.

[0082] In this embodiment, the puncture strength of liquid crystal layer 103 may be, for example, 100 gf or less. When liquid crystal layer 103 is composed of two liquid crystal layers, the puncture strength of liquid crystal layer 103 composed of these two liquid crystal layers can be used as the puncture strength of liquid crystal layer 103. When liquid crystal layer 103 is composed of two or more liquid crystal layers and includes an adhesive layer and an alignment layer for bonding the liquid crystal layers together, the puncture strength of liquid crystal layer 103 can be used as the puncture strength of liquid crystal layer 103 including these layers.

[0083] The puncture strength of liquid crystal layer 103 (hereinafter simply referred to as "puncture strength") may be 95 gf or less, 90 gf or less, or 80 gf or less. The puncture strength of liquid crystal layer 103 is preferably 10 gf or more, and may be 30 gf or more, or 50 gf or more. Liquid crystal layer 103 having such a puncture strength can be obtained, for example, by reducing the thickness of the layers that constitute liquid crystal layer 103.

[0084] The piercing strength is the load applied to a piercing jig when the piercing jig is pierced perpendicularly into the liquid crystal layer 103 and the liquid crystal layer 103 is torn. The piercing strength 103 can be measured, for example, by a compression tester equipped with a load cell. Examples of the compression tester include a handy compression tester "KES-G5 type" manufactured by Kato Tech Co., Ltd. and a small tabletop tester "EZ Test (registered trademark)" manufactured by Shimadzu Corporation.

[0085] The puncture strength can be measured as follows. The liquid crystal layer is sandwiched between two sample stages with a circular hole of 15 mm or less in diameter through which the puncture tool can pass, and the puncture tool is pierced perpendicularly into the liquid crystal layer. The load on the puncture tool when the liquid crystal layer is torn is read. The puncture tool is a cylindrical rod equipped with a puncture needle whose tip that comes into contact with the liquid crystal layer is spherical or semispherical. The spherical or semispherical part at the tip has a diameter of 1 mmφ. The curvature of the tip is 0.5R. The puncture speed of the compression tester is 0.0033 cm / sec. The puncture strength is measured for 12 retardation layer test pieces, and the average value is calculated as the puncture strength.

[0086] The laminate 100 may have two or more liquid crystal layers having a function of a retardation layer. When the laminate 100 has two liquid crystal layers having a function of a retardation layer, the combination of the two layers is a combination of a layer that gives a retardation of λ / 4 and a positive C layer, or a combination of a layer that gives a retardation of λ / 4 and a retardation of λ / 2. It is preferable to combine with a layer that gives a difference. When the laminate contains two liquid crystal layers, the layers containing the cured product of the polymerizable liquid crystal compound of each liquid crystal layer may be laminated via an adhesive layer or a pressure-sensitive adhesive layer. From the viewpoint of making the laminate thinner, the thickness of the liquid crystal layer in which multiple layers are laminated is preferably 3 μm or more and 30 μm or less, more preferably 5 μm or more and 25 μm or less.

[0087] [Second adhesive layer] The laminate 100 has a second adhesive layer 104 on the side of the liquid crystal layer 103. The second adhesive layer 104 can attach the laminate 100 to an image display element or other optical members.

[0088] The adhesive, adhesive composition, thickness and preparation method used in the second adhesive layer are the same as those described in the section on the first adhesive layer. The separator film used in the second adhesive layer and optional components that may be contained therein are also the same as those described in the section on the first adhesive layer.

[0089] [Protection film] The laminate 100 may include a protective film for protecting its surface (typically, the surface of the thermoplastic resin film of the polarizing plate). The protective film is peeled off and removed together with the pressure-sensitive adhesive layer thereof after the polarizing plate is attached to, for example, an image display element or other optical members.

[0090] The protective film is, for example, composed of a base film and an adhesive layer laminated thereon. The adhesive layer is as described above. The resin constituting the base film may be, for example, a thermoplastic resin such as a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, or a polycarbonate-based resin. A polyester-based resin such as polyethylene terephthalate is preferred.

[0091] The thickness of the protective film is not particularly limited, but is preferably in the range of, for example, 20 μm to 200 μm. When the thickness of the substrate is 20 μm or more, the laminate 100 tends to be easily provided with strength.

[0092] Fig. 2 is a schematic cross-sectional view of a laminate according to another embodiment of the present invention. Laminate 200 shown in Fig. 2 includes, in this order, a protective film 207, a polarizing plate 203 having a thermoplastic resin film 202 and a polarizer 201, a first adhesive layer 204, a liquid crystal layer 205, and a second adhesive layer 206.

[0093] The liquid crystal layer 205 may include two or more liquid crystal layers and may include an adhesive for bonding the liquid crystal layers together. The second adhesive layer 206 may have a separator on the opposite side to the liquid crystal layer 205.

[0094] <Applications of laminates> The laminate can be used in various display devices. A display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light source. Examples of display devices include liquid crystal display devices, organic EL display devices, inorganic electroluminescence (hereinafter also referred to as inorganic EL) display devices, electron emission display devices (e.g., field emission display devices (also referred to as FEDs) and surface field emission displays (also referred to as SEDs)), electronic paper (display devices using electronic ink or electrophoretic elements, plasma display devices, projection display devices (e.g., grating light valve (also referred to as GLV) display devices, and display devices having digital micromirror devices (also referred to as DMDs)), and piezoelectric ceramic displays. Liquid crystal display devices include both transmissive liquid crystal display devices and semi-transmissive liquid crystal display devices. These display devices include, The laminate may be a display device that displays a two-dimensional image, or a stereoscopic display device that displays a three-dimensional image. The laminate can be effectively used in an organic EL display device or an inorganic EL display device.

[0095] <Method of manufacturing optical laminate> An example of a method for producing a laminate will be described with reference to FIGS. 3(A) to (E). The method for manufacturing the laminate includes a preparation step of preparing a liquid crystal layer and a polarizing plate [Figures 3(A) to (D)], a lamination step of bonding the liquid crystal layer to the polarizing plate via a first adhesive layer and providing a second adhesive layer on the side of the liquid crystal layer opposite the first adhesive layer to obtain a laminate [Figure 3(E)], a cutting step of cutting the laminate, and a polishing step of polishing the edge faces of the laminate.

[0096] A laminated film 300 including a liquid crystal layer 301, an alignment layer 302, and a base layer 303 as shown in Fig. 3(A), and a laminated film 400 including a liquid crystal layer 401, an alignment layer 402, and a base layer 403 as shown in Fig. 3(B) are prepared. As shown in Fig. 3(C), the liquid crystal layer 301 of the laminated film 300 and the liquid crystal layer 401 of the laminated film 400 are bonded together via an ultraviolet-curable adhesive layer 501, and then the laminated film 500 is obtained.

[0097] The adhesive constituting the adhesive layer 501 may be, for example, an active energy ray curable adhesive. One example of the method is to apply the adhesive to one or both of the bonding surfaces of the liquid crystal layer 301 and the liquid crystal layer 401, laminate the other bonding surface thereon, and cure the adhesive constituting the adhesive layer.

[0098] The adhesive constituting the adhesive layer can be applied by various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, or a gravure coater.

[0099] The method for curing the adhesive constituting the adhesive layer may be appropriately selected depending on the type of adhesive. When the adhesive is an active energy ray curable adhesive, the method of curing with active energy rays as described above is preferable. Either or both of the bonding surface of the liquid crystal layer 301 and the bonding surface of the liquid crystal layer 401 may be subjected to corona treatment, plasma treatment, or the like, or a primer layer may be formed.

[0100] 3(D), a laminated film 600 is prepared by laminating a protective film 604 to a polarizing plate 603 having a thermoplastic resin film 602 laminated to a polarizer 601. As shown in FIG. 3(E), a laminated film 500 from which the base layer 303 and the alignment layer 302 have been peeled is laminated to the polarizer 601 side of the laminated film 600 via a first adhesive layer 701, and a second adhesive layer 702 with a separator 703 is provided on the side opposite to the first adhesive layer 701 side of the laminated film 500 from which the base layer 403 and the alignment layer 402 have been peeled, thereby obtaining a laminate 700.

[0101] The composite retardation layer of the present invention may be a laminate as shown in Fig. 3(E) or a laminate from which the protective film 604 has been peeled off. Also, the composite retardation layer may be a laminate including any or all of the alignment layer 302, the base layer 303, the alignment layer 402, and the base layer 403 without peeling them off.

[0102] The laminated film can be cut into a predetermined size and shape for the laminate 700. Examples of the cutting method include a method using a Thomson blade or a laser cutter.

[0103] The end faces of the cut laminate 700 may be polished in order to remove any burrs that may occur on the end faces of the laminate during cutting, and from the standpoint of dimensional accuracy.

[0104] The method for polishing the end faces of the laminate includes, for example, the following steps. [a] a first step of stacking a plurality of laminates to obtain a laminate; and [b] A second step of cutting the end surface of the obtained laminate by moving a cutting tool having a cutting blade, which rotates around a rotation axis, relative to the laminate along the longitudinal direction of the end surface of the laminate.

[0105] [1st process] This process is a process of stacking a plurality of rectangular laminates to obtain a laminate. The size and number of the laminates to be stacked are not particularly limited, but according to the present invention, even if the laminate has a considerable height, the end faces of each laminate can be processed together in a good finished state, and the processing efficiency is excellent. The number of laminates to be stacked may be, for example, 100 to 500. The laminate may be obtained by cutting a long laminate, for example.

[0106] Referring to Fig. 4, which is a diagram for explaining the second step of cutting the end faces of the laminate, which will be described later, the laminate W obtained by stacking a plurality of laminates has four exposed end faces, and each end face is composed of an exposed end face of each of the stacked laminates. The plurality of laminates are stacked so that their four sides are aligned. The stacking of the laminates can be performed automatically or manually.

[0107] From the viewpoint of crack suppression, it is preferable that the cutting blade enters the laminate in a direction from the liquid crystal layer side to the polarizing plate side of the end face of the laminate. By entering the cutting blade in this manner, a laminate satisfying the above-mentioned formula (1) tends to be obtained. For example, in FIG. 4, when the cutting blade B enters in the rotation direction, it is preferable that the laminate is stacked with the liquid crystal layer side being the side into which the cutting blade B enters.

[0108] [Second process] In this step, the edge faces of the laminate obtained in the first step are cut with a cutting tool to obtain an edge-processed laminate.

[0109] With reference to the drawings, an edge processing device used in the second step of cutting the edge of a laminate according to the present invention will be described first. Fig. 4 is a side view (Fig. 4(A)) and a front view (Fig. 4(B)) showing an example of a cutting tool of the edge processing device used in the second step, Fig. 5 is a side view showing the angle of incidence of the cutting tool to the laminate when viewed from the direction of the rotation axis of the cutting tool, and Fig. 6 is an exploded view showing the details of the cutting part of the cutting tool shown in Fig. 4. Fig. 7 is a schematic perspective view showing an example of an edge processing device equipped with the cutting tool shown in Fig. 4.

[0110] The end surface processing device used in the second step may be, for example, as shown in FIG. 7, equipped with a support part 30 for pressing the laminate W from above and below to prevent the laminate W itself from moving during cutting and to fix the stacked laminates so that they do not shift, and two cutting tools (cutting rotors) 10 that can rotate around a rotation axis to cut the end surfaces of the laminate W.

[0111] The support unit 30 may include a flat substrate (moving means for the laminate W) 31, a gate-shaped frame 32 arranged on the substrate 31, a rotary table 33 arranged on the substrate 31 and rotatable about a central axis, and a cylinder 34 provided at a position facing the rotary table 33 on the frame 32 and movable up and down. The laminate W is sandwiched and fixed between the rotary table 33 and the cylinder 34 via a jig 35.

[0112] Two cutting tools 10 are provided on both sides of the substrate 31, facing each other. The cutting tools 10 are movable in the direction of the rotation axis in accordance with the size of the laminate W, and the substrate 31 is movable so as to pass between the two cutting tools 10. After fixing W to the support 30 and appropriately adjusting the position of the cutting tool 10 in the direction of the rotation axis, the cutting tools 10 are rotated about their rotation axes while moving the substrate 31 so that the laminate W passes between the opposing cutting tools 10. This allows the cutting tool 10 to be moved relative to the laminate W along the length direction of the end faces of the laminate W (parallel to the length direction) while the cutting blades of the cutting tool 10 are brought into contact with the opposing exposed end faces of the laminate W to perform cutting work to cut off these end faces.

[0113] 4, the cutting tool 10 can be a rotating body that is fixed to a support base 10a and can rotate about a rotation axis A. Although the cutting tool 10 is disk-shaped in FIG. 4 and other figures, the shape is not limited to this. The rotation axis A extends in a direction perpendicular to the end face of the laminate W to be cut.

[0114] The cutting tool 10 has an installation surface S perpendicular to the rotation axis A (hence parallel to the end face of the laminate W to be cut). On the installation surface S, a first group of cutting parts consisting of cutting parts 1a, 1b and 1c and a second group of cutting parts consisting of cutting parts 1d, 1e and 1f are provided, and each cutting part has a cutting blade B for cutting off the end face. Each cutting part is arranged around the rotation axis A. Each cutting part protrudes from the installation surface S toward the end face of the laminate W to be cut, and the cutting blade B is arranged on the top surface of the protruding cutting part. The cutting blade B of each cutting part is usually arranged to extend parallel to the installation surface S (hence parallel to the end face of the laminate W to be cut).

[0115] Referring to FIG. 4(B), the cutting parts 1a, 1b, and 1c constituting the first cutting part group come into contact with the end face of the laminate W in this order when the cutting tool 10 is rotated in its rotation direction (the direction of the arrow shown in FIG. 4(B)) and cut the end face. The cutting parts 1a, 1b, and 1c are arranged so that the distance from the installation surface S to the cutting blade B (the protruding height of the cutting blade B) increases as the cutting part is positioned further downstream in the rotation direction of the cutting tool 10. That is, the protruding height of the cutting blade B of the cutting part 1b is greater than the protruding height of the cutting blade B of the cutting part 1a, and the protruding height of the cutting blade B of the cutting part 1c is greater than the protruding height of the cutting blade B of the cutting part 1b. The same is true for the second cutting part group, and the cutting parts 1d, 1e, and 1f constituting the second cutting part group come into contact with the end face of the laminate W in this order and cut the end face when the cutting tool 10 is rotated in its rotation direction. The cutting portions 1d, 1e and 1f are arranged so that the protruding height of the cutting blade B is greater in the cutting portion located further downstream in the rotational direction of the cutting tool 10; that is, the protruding height of the cutting blade B of cutting portion 1e is greater than the protruding height of the cutting blade B of cutting portion 1d, and the protruding height of the cutting blade B of cutting portion 1f is greater than the protruding height of the cutting blade B of cutting portion 1e.

[0116] Also, referring to FIG. 4(B), the cutting parts 1a, 1b, and 1c constituting the first cutting part group are arranged so that the distance from the rotation axis A to the cutting blade B becomes shorter as the cutting part is located further downstream in the rotation direction of the cutting tool 10. That is, the distance from the rotation axis A to the cutting blade B in the cutting part 1b is shorter than that in the cutting part 1a, and the distance from the rotation axis A to the cutting blade B in the cutting part 1c is shorter than that in the cutting part 1b. The same is true for the second cutting part group, and the cutting parts 1d, 1e, and 1f constituting the second cutting part group are arranged so that the distance from the rotation axis A to the cutting blade B becomes shorter as the cutting part is located further downstream in the rotation direction of the cutting tool 10. That is, the distance from the rotation axis A to the cutting blade B in the cutting part 1e is shorter than that in the cutting part 1d, and the distance from the rotation axis A to the cutting blade B in the cutting part 1f is shorter than that in the cutting part 1e.

[0117] It is preferable that each cutting portion arranged on the installation surface S be arranged around the rotation axis A at equal intervals from each other.

[0118] Not limited to the example shown in FIG. 4, the cutting tool 10 may be arranged in n groups (n is 1 or more) on the installation surface S. 4, n is 2. n is, for example, an integer from 1 to 5, and preferably 2 or 3. In addition, not limited to the example shown in FIG. 4, the cutting portion group can have m cutting portions (m is an integer of 2 or more). In the example shown in FIG. 4, m is 3. m is, for example, an integer from 2 to 10, and preferably an integer from 3 to 7.

[0119] When the cutting tool 10 has two or more groups of cutting parts, the protruding height of the cutting blade B of the first cutting part (the most upstream side in the rotation direction) in the first group [cutting part 1a in FIG. 4B] and the distance from the rotation axis A to the cutting blade B are usually the same as those of the first cutting part [cutting part 1d in FIG. 4B] in the second group (and the third group and thereafter). The same is true for the second, third, .... For example, as in the example shown in FIG. 4, when the cutting tool 10 has two groups of cutting parts, it is preferable to arrange two cutting parts (cutting parts 1a and 1d, cutting parts 1b and 1e, and cutting parts 1c and 1f in the example shown in FIG. 4) having the same protruding height of the cutting blade B and the same distance from the rotation axis A to the cutting blade B at positions facing each other across the rotation axis A.

[0120] With reference to Fig. 4(B), when the installation surface S is viewed from the direction of the rotation axis A, the cutting blade B of each cutting part may be inclined inward with respect to the rotation direction of the cutting part. By making the cutting blade B a straight blade and extending the cutting blade B at an angle such that one end of the straight cutting blade B on the upstream side in the rotation direction is closer to the rotation axis A than the other end, the angle [θ1 in Fig. 4(B)] between the straight line passing through the rotation axis A and the center of the cutting blade B and the perpendicular line of the cutting blade B passing through the center of the cutting blade B can be set to 0 to 50 degrees. The angle θ1 can be selected in consideration of the height (thickness) of the laminate W, the material of the laminate, etc., and is more preferably 0 to 40 degrees, and even more preferably 0 to 35 degrees. By tilting the extension direction of the cutting blade B, the cutting blade B can be abutted against the end face of the laminate W at a gently inclined angle rather than horizontally, which tends to make it easier to suppress chipping, damage, and delamination of the end face of the laminate W during cutting, and also tends to make it easier to obtain an end face-processed laminate that is less susceptible to delamination.

[0121] 5(A) shows the incident angle θ2 of the cutting blade B with respect to the laminate W when a cutting tool 10 equipped with the cutting blade B with an angle θ1 of 0 degrees is viewed from the direction of the rotation axis A. The incident angle θ2 is the incident angle of the cutting blade B when the end of the cutting blade B in the outer direction of the rotation radius comes into contact with the surface of the laminate, and can be calculated by the following formula. θ2=sin-1 (Hx / R)-θ1 In the formula, Hx represents the height of the xth stack above the stack in the stack W located at the same height as the rotation axis A of the cutting tool 10, and R represents the radius of the cutting tool 10 (the distance from the rotation axis A to the outer end of the cutting tool 10 at the cutting blade B). The incident angle θ2 is set to 0 degrees when the cutting blade B is at the α position in FIG. 5(B), the positive side is when the cutting blade B is on the β side, and the negative side is when the cutting blade B is on the γ side. The incident angle θ2 may be, for example, -90 degrees or more and 90 degrees or less, and from the viewpoint of suppressing the number of cracks that occur around the edges of the liquid crystal layer, is preferably -30 degrees or more and 30 degrees or less, more preferably -15 degrees or more and 15 degrees or less, even more preferably -10 degrees or more and 10 degrees or less, and particularly preferably -5 degrees or more and 5 degrees or less.

[0122] In the cutting tool 10 shown in Fig. 6, the cutting parts 1a, 1b, 1d, and 1e other than the last cutting part in each cutting part group (the cutting part furthest downstream in the direction of rotation) are for rough cutting, and their cutting blades B can be made of, for example, polycrystalline diamond. The last cutting parts 1c and 1f in each cutting part group are for finishing, and their cutting blades B can be made of, for example, single crystal diamond. However, the material of the cutting blades B is not limited to these.

[0123] Referring to FIG. 6, the cutting part 1a (the same applies to the other cutting parts) can be attached to the installation surface S via the base 20. The base 20 can have, for example, a groove 22 on the side of a cylindrical body 21, the width of which is such that the cutting part 1a fits, and a flange 23 at the upper end. The installation surface S is provided with a mounting hole 11 having the same shape as the cross-sectional shape of the body 21, and further provided with a mounting groove 12 so as to divide the mounting hole 11 in half. When attaching the cutting part 1a, the cutting part 1a is fitted into the groove 22 of the base 20 and fixed with a mounting bolt 24. Then, when the body 21 of the base 20 to which the cutting part 1a is attached is fitted into the mounting hole 11, the flange 23 engages with the periphery of the mounting hole 11. Even when the body 21 is fitted into the mounting hole 11, the base 20 can be rotated, so that the direction of the cutting part 1a can be adjusted as desired. After the orientation of the cutting portion 1a has been determined, the mounting groove 12 is closed with a fastening bolt 13, thereby completing the mounting of the cutting portion 1a.

[0124] The size of the cutting tool 10 is not particularly limited, so long as the diameter (shortest diameter) of the circle traced by the cutting part as the cutting tool 10 rotates is the same as or longer than the height of the laminate W so that the end faces of all the stacked laminates can be cut at the same time.

[0125] 7, the end face processing method in this step will be described. First, using the end face processing device as described above, the laminate W is pressed and fixed from above and below by the rotary table 33 and cylinder 34 via the jig 35, and then two cutting tools 10 are placed on the outsides of two opposing end faces of the laminate W. At this time, the cutting tool 10 is placed in a position where its rotation axis A passes through the end faces of the laminate W (for example, a position where it passes through the center of the laminate W in the thickness direction).

[0126] Next, after appropriately adjusting the position of the cutting tool 10 in the direction of the rotation axis A, the two cutting tools 10 are rotated around their rotation axes A, and the cutting tools 10 are moved relative to the laminate W along the length direction of the end face of the laminate W (parallel to the length direction), so that the cutting blades B of the cutting tools 10 come into contact with the end face to cut off the end face. When using the end face processing device of FIG. 7, the position of the cutting tools 10 is fixed, and the substrate 31 is moved horizontally so that the laminate W passes between the facing cutting tools 10, thereby performing the above relative movement. At this time, the rotation direction of the cutting tools 10 is usually opposite to the movement direction of the laminate W. For example, in FIG. 7, when the laminate W is moved to the left, the rotation direction of the cutting tool 10 on the back side is clockwise as viewed from the laminate W side, and the rotation direction of the cutting tool 10 on the front side is counterclockwise as viewed from the laminate W side. This allows the end faces of each laminate to be cut to a good finish.

[0127] The above-mentioned relative movement can also be performed by horizontally moving the cutting tool 10 using a moving means (not shown) while fixing the position of the laminate W. However, from the viewpoint of drive control of the end face processing device, it is preferable to fix the position of the cutting tool 10 and perform cutting while horizontally moving the laminate W.

[0128] 7, it is extremely advantageous in terms of processing efficiency to use two cutting tools 10 for one laminate W to simultaneously cut two opposing end faces of the laminate W. However, it is also possible to perform cutting processing using one cutting tool for one laminate W.

[0129] In the cutting process by the relative movement of the cutting tool 10, first, the cutting parts 1a and 1d located on the outermost sides of the cutting tool 10 come into contact with the end face of the laminate W and cut off the end face. As the relative movement progresses, the cutting parts 1b and 1e located on the inner side of the cutting parts 1a and 1d come into contact with the laminate W. The cutting parts 1b and 1e are located closer to the cutting blade B than the cutting parts 1a and 1d. Because the protruding height is large, the end face cut by cutting parts 1a and 1d is cut even deeper. In this manner, cutting parts 1a, 1b, 1d and 1e cut the end face of the laminate W gradually deeper. Finally, cutting parts 1c and 1f, which are provided on the inside of cutting parts 1b and 1e and have cutting blades B with a greater protruding height than cutting parts 1b and 1e, cut the end face of the laminate W and perform a mirror finish.

[0130] The above-mentioned relative movement is usually performed from one end to the other end of the two end faces of the laminate W, thereby making it possible to cut the entire surfaces of the two end faces. The cutting depth in the depth direction of the end face cut by one of the multiple cutting parts constituting the cutting part group (the thickness of the polarizing plate end face to be cut off) and the total cutting depth in the depth direction of the end faces cut by the multiple cutting parts (the total thickness of the laminate end faces to be cut off) can be easily controlled by adjusting the protruding height of the cutting blade B of each cutting part constituting the cutting part group.

[0131] After the cutting of the two opposing end faces is completed, the laminate W is rotated by 90 degrees on the rotary table 33, and the remaining two end faces are subsequently machined in the same manner as above.

[0132] Here, in the present invention, the cutting process of the end face of the laminate W is carried out so that the number of times that the n groups of cutting parts abut against the end face of the laminate W (n times per one rotation of the cutting tool, hereinafter also referred to as the "number of abutments") is typically 500 to 1,000 times per 100 mm of longitudinal length of the end face.

[0133] The relative movement speed between the laminate W and the cutting tool 10 and the rotation speed of the cutting tool 10 are adjusted to satisfy the above-mentioned number of contacts. The relative movement speed can be selected, for example, from a range of 200 mm / min to 2000 mm / min (more typically, a range of 500 mm / min to 2000 mm / min). When the relative movement speed is within the above-mentioned range, the higher the relative movement speed, the smaller the maximum depth Dm of cracks that occur around the edge of the liquid crystal layer of the laminate tends to be.

[0134] The rotation speed of the cutting tool 10 can be selected, for example, from a range of 2000 rpm to 8000 rpm (more typically, a range of 2500 rpm to 6000 rpm). When the rotation speed of the cutting tool 10 is within the above range, a higher rotation speed tends to reduce the maximum depth Dm of cracks generated around the edge of the liquid crystal layer of the laminate.

[0135] The cutting depth in the depth direction of the end face cut by one of the cutting parts constituting the cutting part group (the thickness of the polarizing plate end face cut by the cutting part having one type of cutting blade B protruding height, hereinafter also referred to as "single cutting depth") is preferably 0.5 mm or less, more preferably 0.3 mm or less. Setting the cutting depth to 0.5 mm or less is advantageous in effectively suppressing peeling between layers during cutting processing, and in obtaining an end face processed laminate in which peeling between layers is unlikely to occur due to suppressing the decrease in impact resistance of the end face and the end face is finished in a good condition. The cutting depth for one time other than the "cutting depth during finishing" described later is preferably 0.2 mm or more. If the cutting depth for one time is less than 0.2 mm, it may not be possible to achieve an end face finish with a sufficiently good surface condition.

[0136] The total cutting depth in the depth direction of the end faces cut by the multiple cutting parts (the total thickness of the laminate end faces to be cut off, hereinafter also referred to as the "total cutting depth") is preferably 0.2 mm to 1.5 mm, more preferably 0.5 mm to 1.2 mm. If the total cutting depth is less than 0.2 mm, the dimensional accuracy will be poor and it may not be possible to achieve an end face finish with a sufficiently good surface condition. Furthermore, if the total cutting depth exceeds 1.5 mm, the cutting blade B will deteriorate significantly and the impact on the laminate end face will become large, which may cause defects such as cracks at the end of the laminate.

[0137] The cutting depth in the depth direction of the end face cut by the cutting part of the cutting blade B with the greatest protruding height (hereinafter also referred to as the "finishing cutting depth") is preferably 0.01 mm to 0.15 mm, more preferably 0.01 mm to 0.1 mm. It is generally difficult to perform cutting processing with an accuracy of less than 0.01 mm. If the finishing cutting depth exceeds 0.15 mm, the impact on the end face of the laminate becomes large, which may cause defects such as cracks at the end of the laminate. EXAMPLES

[0138] [Observation of cracks] The number N of cracks and maximum depth Dm of the laminate after edge polishing were measured using transmitted light with an optical microscope (VHX-500, 100x field of view). The crack with the deepest depth D among the observed cracks was taken as the maximum depth Dm. The number N of cracks was calculated by counting cracks with a depth of more than 20 μm in the entire edge region and converting it into the number per 10 mm of edge length. The side where the crack was confirmed was the short side of the cut laminate perpendicular to the slow axis of the first retardation layer, which is the first liquid crystal layer.

[0139] [Durability evaluation] The release film was peeled off from the adhesive layer side of the laminate prepared as described above, and the exposed adhesive layer was attached to a glass plate. Further, the protective film was peeled off to obtain an evaluation sample, and the following thermal shock environmental test was performed. (Thermal shock environmental test) The thermal shock environmental test was performed with the laminate attached to a glass plate using a thermal shock tester (product name "TSA-71L-A-3" sold by Espec Corporation) with one cycle consisting of 30 minutes of high temperature (85℃) and 30 minutes of low temperature (-40℃) holding time. The temperature transition time was set to 1 minute, and at 0 minutes of temperature transition time during the temperature transition, no outside air was introduced and no condensation was generated on the laminate. This cycle was repeated 50 and 150 times to perform the test. (judgement) After the thermal shock environmental test, the presence or absence of cracks was visually confirmed. Those that were unchanged from before the test and did not experience light leakage under crossed Nicols after the test were marked with an "O", those that experienced light leakage under crossed Nicols after 50 cycles of the test were marked with an "X", and those that experienced light leakage after 100 cycles of the test were marked with a "△".

[0140] [Puncture strength] The piercing inclination of the test piece of the composite retardation plate manufactured as described above was calculated. Using a small tabletop tester (manufactured by Shimadzu Corporation under the trade name "EZ Test") equipped with a piercing tool with a diameter of 1 mm and a tip curvature radius of 0.5R, the piercing strength per unit film thickness was measured as follows. The liquid crystal layer was sandwiched between two sample stands with a circular hole with a diameter of 15 mm or less through which the piercing tool could pass. The piercing tool was pierced vertically into the liquid crystal layer, and the load applied to the piercing tool when the liquid crystal layer was torn or cracked was read. The piercing speed was 0.0033 cm / sec. The piercing strength was measured for 12 retardation layer test pieces, and the average value was calculated as the piercing strength.

[0141] [Polarizer] A polyvinyl alcohol film having an average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more, and a thickness of 20 μm was immersed in pure water at 30° C., and then immersed in an aqueous solution having a mass ratio of iodine:potassium iodine:water of 0.02:2:100 at 30° C. to perform iodine dyeing (hereinafter, also referred to as the iodine dyeing step). The polyvinyl alcohol film that had undergone the iodine dyeing step was immersed in an aqueous solution having a mass ratio of potassium iodide:boric acid:water of 12:5:100 at 56.5° C. to perform iodine dyeing. The polyvinyl alcohol film that had been subjected to the boric acid treatment step was washed with pure water at 8°C and then dried at 65°C to obtain a polarizer (thickness after stretching: 8 μm) in which iodine was adsorbed and oriented in the polyvinyl alcohol. At this time, stretching was performed in the iodine dyeing step and the boric acid treatment step. The total stretching ratio in this stretching was 5.3 times.

[0142] [Polarizing plate] A hard-coated cycloolefin resin film (thickness 28 μm) and a saponified cellulose resin film (thickness 20 μm) were attached to the polarizer obtained as described above by nip rolls via a water-based adhesive. The resulting laminate was dried at 60° C. for 2 minutes while maintaining the tension at 430 N / m to obtain a polarizing plate having protective films on both sides. The water-based adhesive was prepared by adding 3 parts of carboxy-modified polyvinyl alcohol (Kuraray Poval KL318, manufactured by Kuraray Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez Resin 650, manufactured by Taoka Chemical Co., Ltd., aqueous solution with solid content concentration of 30%) to 100 parts of water.

[0143] The obtained polarizing plate was subjected to luminosity correction using a spectrophotometer (V7100, manufactured by JASCO Corporation) with respect to the obtained transmittance and polarization degree, using a 2-degree visual field (C light source) according to JIS Z 8701, to measure the luminosity-corrected single transmittance Ty and luminosity-corrected polarization degree Py. * and b * The measured luminosity-corrected single transmittance Ty was 42.1%, the luminosity-corrected polarization degree Py was 99.996%, and the single hue a * is -1.1, single hue b * was 3.7.

[0144] A protective film with an adhesive on a PET substrate was attached to the surface of the polarizing plate by bonding the surface-treated surface of the surface-treated cycloolefin resin film so that the adhesive surface of the PET substrate was aligned to obtain a polarizing plate with a protective film. The thickness was 109 μm.

[0145] [Adhesive] A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen inlet tube was charged with 97.0 parts by mass of n-butyl acrylate, 1.0 parts 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. The reaction solution was heated to 60°C while stirring under a nitrogen atmosphere, reacted for 6 hours, and then cooled to room temperature. The weight average molecular weight of a portion of the obtained solution was measured, and the production of a (meth)acrylic acid ester polymer of 1.8 million was confirmed.

[0146] 100 parts by mass (solid content equivalent; the same applies below) of the (meth)acrylic acid ester polymer obtained in the above process was mixed with 0.30 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate 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, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of the adhesive composition.

[0147] The coating solution was applied using an applicator to the release-treated surface (peel layer surface) of a separator (SP-PLR382190, manufactured by Lintec Corporation, thickness 38 μm) so that the dried thickness would be 15 μm (adhesive A) or 25 μm (adhesive B), 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, thereby obtaining an adhesive layer with a double-sided separator.

[0148] [First liquid crystal layer (first retardation layer)] The first liquid crystal layer (first retardation layer) was a layer that gave a retardation of λ / 4 and was composed of a layer of a cured nematic liquid crystal compound, an alignment film, and a transparent substrate. The total thickness of the layer of the cured nematic liquid crystal compound and the alignment layer was 2 μm.

[0149] [Second liquid crystal layer (second retardation layer)] As a composition for forming an alignment layer, 10.0 parts by mass of polyethylene glycol di(meth)acrylate (A-600 manufactured by Shin-Nakamura Chemical Co., Ltd.), 10.0 parts by mass of trimethylolpropane triacrylate (A-TMPT manufactured by Shin-Nakamura Chemical Co., Ltd.), 10.0 parts by mass of 1,6-hexanediol di(meth)acrylate (A-HD-N manufactured by Shin-Nakamura Chemical Co., Ltd.), and 1.50 parts by mass of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator were dissolved in 70.0 parts by mass of methyl ethyl ketone solvent to prepare a coating liquid for forming an alignment layer.

[0150] A long cyclic olefin resin film (manufactured by Zeon Corporation) having a thickness of 20 μm was prepared as a substrate film, and the obtained coating liquid for forming an alignment layer was applied to one side of the substrate film using a bar coater.

[0151] After the coating layer was heat-treated at 80°C for 60 seconds, it was exposed to ultraviolet light (UVB) at 220 mJ / cm 2 The composition for forming the alignment layer was polymerized and cured by irradiation to form an alignment layer 1 having a thickness of 2.3 μm on the substrate film.

[0152] As a composition for forming a retardation layer, 20.0 parts by mass of a photopolymerizable nematic liquid crystal compound (RMM28B manufactured by Merck) and 1.0 part by mass of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator were dissolved in 80.0 parts by mass of propylene glycol monomethyl ether acetate solvent to prepare a coating liquid for forming a retardation layer.

[0153] A coating solution for forming a retardation layer was applied onto the previously obtained alignment layer 1, and the coating layer was subjected to a heat treatment at a temperature of 80° C. for 60 seconds. Thereafter, ultraviolet rays (UVB) were applied at 220 mJ / cm 2 The composition for forming the retardation layer was polymerized and cured by irradiation to form a retardation layer having a thickness of 0.7 μm on the alignment layer. In this manner, a second retardation film (thickness 3 μm) consisting of the alignment layer 1 and the retardation layer 1 was obtained on the substrate film.

[0154] [Liquid crystal layer] The first liquid crystal layer and the second liquid crystal layer were bonded together with an ultraviolet-curing adhesive (1 μm thick) so that the liquid crystal layer surface (the surface opposite to the transparent substrate) of each layer was the bonding surface. Then, the ultraviolet-curing adhesive was irradiated with ultraviolet light to cure. In this manner, a retardation layer including two retardation layers, the first liquid crystal layer and the second liquid crystal layer, was produced. After the transparent substrate was peeled off from both sides of this retardation layer, the piercing strength of the retardation layer was measured. The piercing strength of the retardation layer was 70 gf. The thickness of the liquid crystal layer including the two layers, the first liquid crystal layer, the ultraviolet-curing adhesive layer, and the second liquid crystal layer, was 6 μm.

[0155] [Production Example 1] A polarizing plate with a protective film was laminated with adhesive A, which was obtained by peeling off one of the separators from a double-sided adhesive layer containing adhesive A, and then the other separator was peeled off. A liquid crystal layer containing two retardation layers, a first retardation layer and a second retardation layer, was laminated to adhesive A, and one separator was peeled off from a double-sided adhesive layer containing adhesive B, and adhesive B was laminated to obtain a laminated film having a layer structure of protective film / hard-coated cycloolefin resin film / polyvinyl alcohol film / cellulose resin film / adhesive A / first retardation layer / ultraviolet-curable adhesive layer / second retardation layer / adhesive B / separator. The thickness of the laminated film was 193 μm.

[0156] The laminated film was cut to a specified size and shape, and 300 sheets of the cut laminated film were stacked with the liquid crystal layer side facing up from the polarizing plate side (the side where the cutting blade enters), and the edges were polished using an edge processing device having the configuration shown in Figure 7 to a size of 150 mm x 78 mm under the polishing conditions shown in Table 1 below. The stack height was 57.9 mm, the radius of the cutting tool was 115 mm, and the inclination angle of the cutting blade was 0 degrees.

[0157] [Examples 1 to 4 and Comparative Example 1] The maximum depth and number of cracks were measured for each of the laminates obtained in Production Example 1 at the stacking positions shown in Table 1 according to the above-mentioned "Observation of Cracks", and then durability was evaluated. The results are shown in Table 1. In the table, the stacking number indicates the stacking position of the evaluated laminate from the side where the cutting blade entered.

[0158] [Table 1]

[0159] [Production Example 2] A laminate was obtained in the same manner as in Production Example 1, except that the polishing conditions were changed to those shown in Table 2.

[0160] [Examples 5 and 6, Comparative Example 2] The maximum depth and number of cracks were measured for each laminate at the stacking positions shown in Table 2 according to the above-mentioned "Observation of Cracks", and then durability was evaluated. The results are shown in Table 2.

[0161] [Table 2]

[0162] [Production Example 3] A laminate was obtained in the same manner as in Production Example 1, except that the polishing conditions were changed to those shown in Table 3.

[0163] [Comparative Example 3] The maximum depth and number of cracks were measured for each laminate at the stacking positions shown in Table 3 according to the above-mentioned "Observation of Cracks", and then durability evaluation was performed. The results are shown in Table 3.

[0164] [Table 3] [Explanation of symbols]

[0165] 1a, 1b, 1c, 1d, 1e, 1f cutting part, 10 cutting tool, 10a support base, 11 mounting hole, 12 mounting groove, 13 fastening bolt, 20 base, 21 body, 22 groove, 23 flange, 24 mounting bolt, 30 support, 31 substrate, 32 frame, 33 rotating table, 34 cylinder, 35 jig, A rotating shaft, B cutting blade, S installation surface, W laminate, R radius, Hx laminate height, 100, 200, 700 laminate, 101, 203, 603 polarizing plate, 102, 204, 701 first adhesive layer, 103, 205, 301, 401 liquid crystal layer, 104, 206, 702 second adhesive layer, 207, 604 protective film, 201, 601 polarizer, 202, 602 thermoplastic resin film, 300, 400, 500, 600 laminated film, 302, 402 alignment layer, 303, 403 substrate layer, 501 adhesive layer, 703 separator

Claims

1. A laminate having a polarizing plate, a first adhesive layer, a liquid crystal layer, and a second adhesive layer in this order, The polarizing plate comprises a polarizer and a thermoplastic resin film in this order. The liquid crystal layer has a layer containing a cured product of a polymerizable liquid crystal compound, The laminate has a crack in the edge region of the liquid crystal layer, All end faces of the laminate are polished end faces. The polished end face is a cut surface, The following equation (1'') is satisfied, A laminate in which the puncture strength of the liquid crystal layer is 100 gf or less. 78 ≤ N + (Dm × 1.34) < 111 (1'') [In the formula, N represents the number of cracks per 10 mm of end length of the laminate, where the depth from the end in a plan view is 20 μm or more. N is between 1 and 20, Dm represents the largest depth [μm] among the cracks counted as described above. Dm is between 20 μm and 80 μm.

2. The laminate according to claim 1, wherein the liquid crystal layer further comprises an alignment layer.

3. The laminate according to claim 1 or 2, wherein at least one end of the crack is located at the end of the liquid crystal layer intersecting the orientation direction of the polymerizable liquid crystal compound.

4. The laminate according to any one of claims 1 to 3, wherein the laminate is in the form of a single leaf.

5. An image display device having a laminate according to any one of claims 1 to 4.

Images