Polarizing plate set and liquid crystal panel

Abstract

To provide a polarizing plate set with which warp of a liquid crystal panel is suppressed.SOLUTION: Provided is a polarizing plate set 1 that includes a front-side polarizing plate 100 arranged on the visible side of a liquid crystal cell 300 and a rear-side polarizing plate 200 arranged on the rear side of the liquid crystal cell, the front-side polarizing plate and the rear-side polarizing plate including a polarizer. When it is assumed that the distance from a surface on liquid crystal cell side of the polarizer included in the front-side polarizing plate to a surface on the liquid crystal cell side of the front-side polarizing plate is L1 (μm) and the distance from a surface on liquid crystal cell side of the polarizer included in the rear-side polarizing plate to a surface on the liquid crystal cell side of the rear-side polarizing plate is L2 (μm), at least one of L1 (μm) and L2 (μm) is 35 μm or less, and at least one of the front-side and the rear-side polarizing plates that is selected includes a resin layer on the liquid crystal cell side of the polarizer, the moisture vapor permeability of which, at temperature 40°C and humidity 90%HR, is 400 g / m2-24hr or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polarizing plate set and a liquid crystal panel. [Background technology]

[0002] A liquid crystal panel in which a polarizing plate is arranged on each of the viewing side and the back side of a liquid crystal cell is used in an image display device, etc. It is known that the liquid crystal panel may warp when used in a high-temperature environment (Patent Documents 1 and 2).

[0003] Patent Document 1 proposes reducing warping of a liquid crystal panel in a high-temperature environment by making the tensile modulus of elasticity of the protective layer of the polarizing plate on the concavely warped side of a polarizing plate set satisfy a predetermined formula. Patent Document 2 proposes reducing warping of a liquid crystal panel in a high-temperature environment by making the distance from the surface of the polarizer of a front plate-integrated polarizing plate farther from the front plate to the liquid crystal cell greater than the distance from the surface of the polarizer of a rear-side polarizing plate closer to the front plate to the liquid crystal cell. Patent Document 3 proposes a liquid crystal display device in which values ​​calculated from the thickness, elastic modulus, and dimensional change rate of the polarizer and the distance from the polarizer to the liquid crystal cell are set to specific ratios in order to reduce warping of a liquid crystal panel that occurs during pressurized degassing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-72533 A [Patent Document 2] JP 2017-83857 A [Patent Document 3] International Publication No. 2015 / 156250 Summary of the Invention [Problem to be solved by the invention]

[0005] Warping occurs in a high-temperature (e.g., 85°C) environment because a polarizer containing a polyvinyl alcohol-based resin film (hereinafter also referred to as a PVA polarizer), which is a component of a polarizing plate attached to a panel, shrinks due to heating. PVA polarizers tend to shrink significantly in the stretching direction due to heating. Such warping of liquid crystal panels caused by PVA polarizers can sometimes be reduced by using the polarizing plate set described in the above patent document.

[0006] On the other hand, when an LCD TV module is shipped, for example, by sea, and the backlight is turned on after unpacking, a problem occurs in which the LCD panel warps. As LCD TVs become larger, the polarizing plates for large LCD TVs have a large area, so the amount of warping increases with even a slight change in the dimensions of the front and back polarizing plates, and suppressing this warping is extremely important compared to applications with smaller areas.

[0007] An object of the present invention is to provide a polarizing plate set that suppresses warping of a liquid crystal panel. [Means for solving the problem]

[0008] The present invention provides the following polarizing plate set and liquid crystal panel. [1] A polarizing plate set including a front-side polarizing plate arranged on the viewing side of a liquid crystal cell and a back-side polarizing plate arranged on the back side of the liquid crystal cell, the front-side polarizing plate and the rear-side polarizing plate each include a polarizer; where L1 (μm) is a distance from a liquid crystal cell side surface of a polarizer included in the front-side polarizing plate to a liquid crystal cell side surface of the front-side polarizing plate, and L2 (μm) is a distance from the liquid crystal cell side surface of a polarizer included in the back-side polarizing plate to a liquid crystal cell side surface of the back-side polarizing plate, at least one of L1 (μm) and L2 (μm) is 35 μm or less, At least one selected from the front-side polarizing plate and the back-side polarizing plate has a moisture permeability of 400 g / m at a temperature of 40° C. and a humidity of 90% RH on the liquid crystal cell side of the polarizer. 2A polarizing plate set with a resin layer of 24 hours or less. [2] The polarizing plate set according to [1], wherein the sum of L1 (μm) and L2 (μm) is 60 μm or less. [3] The polarizing plate set according to [1] or [2], wherein the absolute value of the difference between L1 (μm) and L2 (μm) is 3 μm or less. [4] The polarizing plate set according to any one of [1] to [3], wherein the polarizers included in the front-side polarizing plate and the back-side polarizing plate have substantially the same thickness. [5] The front-side polarizing plate and the back-side polarizing plate each have a moisture permeability of 400 g / m at a temperature of 40° C. and a humidity of 90% RH on the liquid crystal cell side of the polarizer. 2 The polarizing plate set according to any one of [1] to [4], having a resin layer of 24 hr or less. [6] The polarizing plate set according to any one of [1] to [5], wherein the front-side polarizing plate and the back-side polarizing plate each contain a cyclic cycloolefin resin film on the liquid crystal cell side of the polarizer. [7] The polarizing plate set according to any one of [1] to [6], wherein the front-side polarizing plate and the back-side polarizing plate each contain a triacetyl cellulose-based resin film on the side of the polarizer opposite to the liquid crystal cell. [8] A liquid crystal panel comprising the polarizing plate set according to any one of [1] to [7] and a liquid crystal cell. Effect of the Invention

[0009] According to the present invention, it is possible to provide a polarizing plate set that suppresses warping of a liquid crystal panel. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing a layer structure of a polarizing plate set of the present invention. [Diagram 2] FIG. 4 is a schematic cross-sectional view showing another layer structure of the polarizing plate set of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0012] <Polarizing plate set> A polarizing plate set according to one embodiment of the present invention will be described with reference to Fig. 1. Polarizing plate set 1 shown in Fig. 1 is composed of front-side polarizing plate 100 arranged on the viewing side of liquid crystal cell 300, and back-side polarizing plate 200 arranged on the back side of liquid crystal cell 300. Front-side polarizing plate 100 and back-side polarizing plate 200 may be of the same type or different types. A liquid crystal panel can be produced by bonding the polarizing plate set to a liquid crystal cell.

[0013] The shape of the front-side polarizing plate 100 and the rear-side polarizing plate 200 may be, for example, a square shape, preferably a square shape having a long side and a short side, more preferably a rectangle. The size of the front-side polarizing plate 100 and the rear-side polarizing plate 200 is preferably a square shape (equivalent to a 32-inch type) having a long side of 660 mm or more and a short side of 370 mm or more, and preferably a square shape (equivalent to a 40-inch type) having a long side of 800 mm or more and a short side of 450 mm or more. Furthermore, the size of the front-side polarizing plate 100 and the rear-side polarizing plate 200 is preferably a square shape (equivalent to a 50-inch type) having a long side of 1000 mm or more and a short side of 550 mm or more, and preferably a square shape (equivalent to a 60-inch type) having a long side of 1300 mm or more and a short side of 700 mm or more.

[0014] Polarizer set 1 can be disposed in the liquid crystal cell such that the transmission axes of front-side polarizer 100 and back-side polarizer 200 are substantially perpendicular to each other. The angle of the transmission axis of back-side polarizer 200 relative to the transmission axis of front-side polarizer 100 may be, for example, within a range of 90±5°, preferably within a range of 90±1°, and more preferably within a range of 90±0.5°.

[0015] The planar shape of the front-side polarizing plate 100, the back-side polarizing plate 200, and the liquid crystal cell 300 may be, for example, a square shape, preferably a square shape having a long side and a short side, and more preferably a rectangle. When the planar shape of the front-side polarizing plate 100, the back-side polarizing plate 200, and the liquid crystal cell 300 is a rectangle, the polarizing plate set 1 may be arranged so that the absorption axis direction of the polarizer of the front-side polarizing plate 100 is approximately parallel to the long side direction of the liquid crystal cell, and the absorption axis direction of the polarizer of the back-side polarizing plate 200 is approximately parallel to the short side direction of the liquid crystal cell, or the absorption axis direction of the polarizer of the front-side polarizing plate 100 is approximately parallel to the short side direction of the liquid crystal cell, and the absorption axis direction of the polarizer of the back-side polarizing plate 200 is approximately parallel to the long side direction of the liquid crystal cell. "Almost parallel" means, for example, that the angle between the absorption axis of the polarizing plate and the long side or short side of the liquid crystal cell is 5° or less, preferably 3° or less, and more preferably 1° or less.

[0016] Both the front-side polarizing plate 100 and the back-side polarizing plate 200 include a polarizer and a resin layer, which are not shown in the figure. In addition, both the front-side polarizing plate 100 and the back-side polarizing plate 200 include an adhesive layer (not shown) for bonding the front-side polarizing plate 100 and the back-side polarizing plate 200 to a liquid crystal cell. The front-side polarizing plate 100 and the back-side polarizing plate 200 may further include, for example, an attachment layer, a retardation layer, a protection film, and the like, in addition to the polarizer and the resin layer described below.

[0017] In polarizing plate set 1, when the distance from the liquid crystal cell 300 side surface of a polarizer contained in front-side polarizing plate 100 to the liquid crystal cell 300 side surface of front-side polarizing plate 100 is L1 (μm), and the distance from the liquid crystal cell 300 side surface of a polarizer contained in back-side polarizing plate 200 to the liquid crystal cell 300 side surface of back-side polarizing plate 200 is L2 (μm), at least one of L1 (μm) and L2 (μm) is 35 μm or less, and at least one selected from front-side polarizing plate 100 and back-side polarizing plate 200 has a moisture permeability of 400 g / m at a temperature of 40° C. and a humidity of 90% RH (hereinafter, for simplicity, also referred to as moisture permeability) on the liquid crystal cell side of the polarizer. 2The surface of front-side polarizing plate 100 facing liquid crystal cell 300 and the surface of back-side polarizing plate 200 facing liquid crystal cell 300 refer to the surfaces of pressure-sensitive adhesive layers (excluding separate films) contained in front-side polarizing plate 100 and back-side polarizing plate 200 facing the liquid crystal cell.

[0018] The present inventors have found that the polarizer, which is a component of the polarizing plate attached to the liquid crystal cell, gradually absorbs moisture when exposed to a high humidity environment for a long time, and then, after the backlight is turned on and time passes, the polarizer is deformed due to the movement of moisture, and this deformation causes warping of the liquid crystal cell. For example, when a liquid crystal television module is transported by sea, the humidity is high at the bottom of the ship, and the polarizing plate attached to the liquid crystal cell is in a moisture-absorbing state for a long time. After unpacking in this state, it is difficult to sufficiently prevent moisture from entering from the outside by simply reducing the contraction force of the polarizer or the contraction force of the polarizing plate, and the amount of water absorption of the polarizer increases, resulting in a large amount of deformation. As a result of extensive research by the present inventors, it has been found that at least one of the above L1 (μm) and L2 (μm) is 35 μm or less, and at least one selected from the front side polarizing plate and the back side polarizing plate has a moisture permeability of 400 g / m on the liquid crystal cell side of the polarizer. 2 It was found that the amount of warping of the LCD panel tends to be reduced by having a resin layer of 24 hr or less. This is presumably because it is possible to reduce the strain energy that accumulates on the LCD cell side of the polarizer while suppressing the intrusion of moisture from the LCD cell side of the polarizer.

[0019] At least one of L1 (μm) and L2 (μm) is preferably 30 μm or less, more preferably 25 μm or less, and further preferably 20 μm or less, from the viewpoint of the amount of warping of the liquid crystal panel. In this specification, the amount of warping can be measured according to the method described in the Examples section below.

[0020] From the viewpoint of the amount of warping of the liquid crystal panel, both L1 (μm) and L2 (μm) are preferably 35 μm or less, more preferably 30 μm or less, further preferably 25 μm or less, and particularly preferably 20 μm or less.

[0021] From the viewpoint of the amount of warping of the liquid crystal panel, the sum of L1 (μm) and L2 (μm) is preferably 60 μm or less, more preferably 50 μm or less, and further preferably 40 μm or less.

[0022] In order to equalize and cancel the distortion forces exerted on the liquid crystal cell by the front-side polarizing plate and the rear-side polarizing plate, L1 (μm) and L2 (μm) can be set to the same extent. From the viewpoint of the amount of warping of the liquid crystal panel, the absolute value of the difference between L1 (μm) and L2 (μm) is preferably 3 μm or less, more preferably 2 μm or less, even more preferably 1 μm or less, and particularly preferably 0.

[0023] [Polarizer] A polarizer has the property of absorbing linearly polarized light with a vibration plane parallel to its absorption axis and transmitting linearly polarized light with a vibration plane perpendicular to the absorption axis (parallel to the transmission axis). A laminate of a polarizer and a resin layer is also called a linear polarizing plate.

[0024] The polarizer may be a film in which iodine is adsorbed to a known polyvinyl alcohol-based resin. The polarizer may be produced, for example, through a process of uniaxially stretching a polyvinyl alcohol-based resin, a process of dyeing the polyvinyl alcohol-based resin with iodine to adsorb the iodine, a process of treating the polyvinyl alcohol-based resin to which iodine has been adsorbed with an aqueous boric acid solution, and a process of washing with water after the treatment with the aqueous boric acid solution.

[0025] Polyvinyl alcohol resins are obtained by saponifying polyvinyl acetate resins. As polyvinyl acetate resins, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers copolymerizable therewith are used. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfone compounds, and (meth)acrylamide compounds having an ammonium group. In this specification, "(meth)acryl" means at least one selected from acrylic and methacrylic. The same applies to "(meth)acrylate" and the like.

[0026] The degree of saponification of the polyvinyl alcohol resin is usually about 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and polyvinyl formal, polyvinyl acetal, etc. modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol resin is usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.

[0027] The thickness of the polarizer is preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and particularly preferably 15 μm or less, from the viewpoint of the smaller water absorption. The thickness of the polarizer is usually 2 μm or more, preferably 3 μm or more, and may be, for example, 5 μm or more. In order to cancel out the deformations of the polarizers of the front-side polarizing plate 100 and the back-side polarizing plate 200, it is preferable to use polarizers of substantially the same thickness for the front-side polarizing plate 100 and the back-side polarizing plate 200.

[0028] [Resin layer] The resin layer is disposed on one or both sides of the polarizer directly or via a bonding layer described later, and can have the function of protecting the polarizer, particularly the surface of the polarizer. The resin layer can be an optically transparent thermoplastic resin film or coating. When the front-side polarizing plate 100 and the back-side polarizing plate 200 contain multiple resin layers, the resin layers may be the same or different.

[0029] The thermoplastic resin film can be laminated on one or both sides of the polarizer. The thermoplastic resin film may be, for example, a light-transmitting, preferably optically transparent, thermoplastic resin film, and examples thereof include polyolefin resins such as linear polyolefin resins (polyethylene resins, polypropylene resins, polymethylpentene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; ethylene-vinyl acetate resins; polystyrene resins; polyamide resins; polyetherimide resins; (meth)acrylic resins such as polymethyl (meth)acrylate resins; polyimide resins; polyethersulfone resins; polysulfone resins; polyvinyl chloride resins; polyvinylidene chloride resins; polyvinyl alcohol resins; polyvinyl acetal resins; polyether ketone resins; polyether ether ketone resins; polyethersulfone resins; polyamideimide resins, etc. The thermoplastic resins may be used alone or in combination of two or more. Among them, from the viewpoints of strength and light transmittance, triacetyl cellulose-based resin films, cyclic polyolefin-based resin films, and (meth)acrylic-based resin films are preferred.

[0030] The thermoplastic resin film may or may not have a retardation. The thermoplastic resin film may contain, as necessary, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, etc.

[0031] The thickness of the thermoplastic resin film may be, for example, 60 μm or less, and is preferably 50 μm or less, more preferably 40 μm or less, from the viewpoint of reducing the distance between the polarizer and the liquid crystal cell, and is usually 1 μm or more, preferably 5 μm or more, and further preferably 15 μm or more.

[0032] A surface treatment layer (coating layer) such as a hard coat layer, an antireflection layer or an antistatic layer can be formed on the surface of the thermoplastic resin film opposite to the polarizer.

[0033] By providing a hard coat layer on a thermoplastic resin film, a resin film with improved hardness and scratch resistance can be obtained. The hard coat layer can be formed from a cured product of a composition for forming a hard coat layer containing an active energy ray curable resin. Examples of ultraviolet ray curable resins 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 include inorganic fine particles, organic fine particles, and mixtures thereof.

[0034] The resin layer as a coating film may be a layer formed by applying and curing a coating composition such as the composition used in the hard coat layer described above, a cationic curable composition such as an epoxy resin, or a radical curable composition such as a (meth)acrylate. The resin layer as a coating film may be a layer formed by using an aqueous solution of a polyvinyl alcohol resin or the like as a coating composition, applying the aqueous solution to the surface of a polarizer, and drying the aqueous solution. The resin layer as a coating film may contain a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, etc., as necessary.

[0035] The thickness of the resin layer, which is a coating film, may be, for example, 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less, further preferably 15 μm, and particularly preferably 10 μm. The thickness of the resin layer, which is a coating film, may be, for example, 0.1 μm or more.

[0036] [Moisture permeability is 400g / m 2 Resin layer less than 24 hours At least one of the front-side polarizing plate 100 and the back-side polarizing plate 200 has a moisture permeability of 400 g / m on the liquid crystal cell side of the polarizer. 2 The moisture permeability in this specification can be measured according to the method described in the Examples section below.

[0037] From the viewpoint of the warping amount of the liquid crystal panel, the low moisture permeability resin layer preferably has a moisture permeability of 300 g / m 2 - 24hr or less, preferably 200g / m 2 24hr or less, more preferably 100g / m 2 24hr or less, and 80g / m 2 The low moisture permeability resin layer has a moisture permeability of, for example, 10 g / m 2 24hr or more, preferably 30g / m 2 -24 hours or more.

[0038] It is preferable that both the front-side polarizing plate 100 and the back-side polarizing plate 200 include a low-moisture-permeable resin layer. When both the front-side polarizing plate 100 and the back-side polarizing plate 200 include a low-moisture-permeable resin layer, the low-moisture-permeable resin layers may be the same or different. In addition to the above-mentioned thermoplastic resin film and coating film, the low-moisture-permeable resin layer may be a stretched thermoplastic resin film, a coating film prepared by a casting method, a layer containing a cured product of a photocurable resin composition, etc. The low-moisture-permeable resin layer is preferably a thermoplastic resin film made of a resin having a cyclic polyolefin as a main monomer.

[0039] [Lamination layer] The lamination layer can be a layer that bonds the polarizer and the resin layer. The lamination layer can be formed from an adhesive or a pressure-sensitive adhesive. Examples of the adhesive include an active energy ray curable adhesive such as an ultraviolet-curable adhesive, an aqueous solution of a polyvinyl alcohol-based resin or an aqueous solution in which a crosslinking agent is blended therewith, and a water-based adhesive such as a urethane-based emulsion adhesive. When a thermoplastic resin film is laminated on both sides of a polarizer, the adhesives forming the two lamination layers may be the same or different. For example, when a thermoplastic resin film is laminated on both sides, one side may be laminated using an aqueous adhesive, and the other side may be laminated using an active energy ray curable adhesive. The ultraviolet-curable adhesive can 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. In addition, a cationic polymerizable epoxy compound and a radically polymerizable (meth)acrylic compound can be used in combination, and a photocationic polymerization initiator and a photoradical polymerization initiator can be used in combination as an initiator. The thickness of the adhesive may be, for example, not less than 0.1 μm and not more than 5 μm.

[0040] 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.

[0041] 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, at least one of the bonding surfaces of the polarizer and the thermoplastic resin film may be subjected to a surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, primer coating treatment, or saponification treatment.

[0042] When the attachment layer is formed from an adhesive, the thickness of the attachment layer may be, for example, 0.01 μm or more and 10 μm or less.

[0043] The adhesive used in the attachment layer can be, for example, a pressure-sensitive adhesive (hereinafter, also referred to as an adhesive).

[0044] The adhesive can be composed of an adhesive composition mainly composed of a resin such as a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin. Among them, from the viewpoints of transparency, weather resistance, heat resistance, and storage modulus, an adhesive composition having a (meth)acrylic resin as a base polymer is preferable. The adhesive composition may be of an active energy ray curing type or a heat curing type.

[0045] 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.

[0046] 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.

[0047] When the attachment layer is formed from an adhesive, for example, an adhesive liquid is prepared by dissolving or dispersing an adhesive composition in an organic solvent such as toluene or ethyl acetate, and this is directly applied to the attachment surface to form an adhesive layer, or a sheet-like adhesive layer is formed on a release-treated separate film, and then the sheet is transferred to the attachment surface.

[0048] 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, etc. Among them, a stretched film of polyethylene terephthalate is preferable.

[0049] The adhesive may contain optional components such as glass fibers, glass beads, resin beads, fillers made of metal powders or other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbing agents, antistatic agents, and the like.

[0050] 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.

[0051] The thickness of the adhesive layer formed from the adhesive may be, for example, 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less. The thickness of the adhesive layer formed from the adhesive may be, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more.

[0052] In order to improve adhesion, the bonding surface may be subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, primer coating treatment, saponification treatment or the like.

[0053] [Adhesive layer] The adhesive layer can have a function of bonding the front-side polarizing plate 100 and the back-side polarizing plate 200 to the liquid crystal cell 300. As the adhesive constituting the adhesive layer, any conventionally known adhesive can be used without particular limitation, and the adhesives exemplified in the bonding layer above can be used. In addition, active energy ray curable adhesives, thermosetting adhesives, etc. may also be used. The adhesive layer can have a separate film.

[0054] [Phase difference layer] The front-side polarizing plate 100 and the back-side polarizing plate 200 may include a retardation layer between the polarizer and the liquid crystal cell. The retardation layer may be a single layer or a retardation layer laminate consisting of two or more retardation layers. The retardation layer may be laminated on the polarizer or the linear polarizing plate via the above-mentioned bonding layer.

[0055] The retardation layer may be a positive A layer such as a λ / 4 layer or a λ / 2 layer, or a positive C layer. The retardation layer may be formed from a liquid crystal cured layer containing a cured product of a polymerizable liquid crystal compound, or may be formed from a resin film exemplified as the material of the thermoplastic resin film described above. The film-like retardation layer 130 may further include an alignment layer and a substrate.

[0056] The retardation layer preferably includes a λ / 4 layer, more preferably includes a λ / 4 layer and at least one of a λ / 2 layer and a positive C layer. When the retardation layer includes a λ / 2 layer, it can be laminated so that the λ / 2 layer and the λ / 4 layer are laminated in order from the polarizer side. When the retardation layer includes a positive C layer, it may be laminated so that the λ / 4 layer and the positive C layer are laminated in order from the polarizer side, or it may be laminated so that the positive C layer and the λ / 4 layer are laminated in order from the polarizer side.

[0057] The thickness of the retardation layer may be, for example, from 0.1 μm to 50 μm, preferably from 1 μm to 30 μm, and more preferably from 0.5 μm to 15 μm.

[0058] [Protection film] Front-side polarizing plate 100 and back-side polarizing plate 200 may have a protective film on the side opposite to liquid crystal cell 300. The protective film can be peeled off and removed together with the pressure-sensitive adhesive layer it has, for example, after the polarizing plate is attached to a liquid crystal cell or other optical members.

[0059] The protective film is composed of, for example, a base film and an adhesive layer laminated thereon. The above description of the laminating layer applies to the adhesive layer. The resin constituting the base film can 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 preferable.

[0060] 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, strength tends to be easily imparted to front-side polarizing plate 100 and back-side polarizing plate 200.

[0061] [Layer structure of polarizing plate set] A polarizing plate set according to one embodiment of the present invention will be described with reference to FIG. 2. Polarizing plate set 2 shown in FIG. 2 is composed of front-side polarizing plate 101 arranged on the viewing side of liquid crystal cell 300, and rear-side polarizing plate 201 arranged on the rear side of liquid crystal cell 300. Front-side polarizing plate 101 and rear-side polarizing plate 201 each include polarizers 130 and 230. Front-side polarizing plate 101 further includes resin layer 110, low-moisture-permeable resin layer 150, attachment layers 120 and 140, and adhesive layer 160. In addition, rear-side polarizing plate 201 further includes resin layer 210, low-moisture-permeable resin layer 250, attachment layers 220 and 240, and adhesive layer 260, as shown in FIG. 1.

[0062] [Method of manufacturing polarizing plate] The front-side polarizing plate and the back-side polarizing plate can be produced, for example, by bonding each layer with a bonding layer. When bonding, it is preferable to subject one or both of the bonding surfaces to a surface activation treatment such as a corona treatment in order to improve adhesion.

[0063] The adhesive layer can be prepared as an adhesive sheet. The adhesive sheet can be produced by, for example, dissolving or dispersing an adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, forming a layer of the adhesive in a sheet shape on a release film that has been subjected to a release treatment, and then laminating another release film on the adhesive layer. The layers can be laminated by a method in which the adhesive sheet from which one release film has been peeled is laminated to one layer (e.g., a polarizing plate), and then the other release film is peeled off, and the other layer (e.g., a liquid crystal cell) is laminated.

[0064] The adhesive liquid can be applied to the release film by using a conventional coating technique such as a die coater, comma coater, reverse roll coater, gravure coater, rod coater, wire bar coater, doctor blade coater, or air doctor coater.

[0065] The release film is preferably composed of a plastic film and a release layer. Examples of the plastic film include polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, and polyolefin films such as polypropylene film. The release layer can be formed, for example, from a composition for forming a release layer. The main component (resin) constituting the composition for forming a release layer is not particularly limited, but includes silicone resin, alkyd resin, acrylic resin, and long-chain alkyl resin.

[0066] [Liquid crystal cell] The liquid crystal cell has two cell substrates and a liquid crystal layer sandwiched between the substrates. The cell substrate is generally made of glass, but may be a plastic substrate. The liquid crystal cell itself used in the liquid crystal panel of the present invention may be made of various types of liquid crystal cells used in this field (for example, known driving modes such as IPS mode, VA mode, TN mode, etc.).

[0067] [Liquid crystal panel] A liquid crystal panel can be produced by attaching a polarizing plate to a liquid crystal cell via a pressure-sensitive adhesive layer. EXAMPLES

[0068] The present invention will be described in more detail below with reference to examples. In the examples, "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[0069] [Thickness measurement] The measurements were made using a digital micrometer (MH-15M, manufactured by Nikon Corporation).

[0070] [Measurement of warpage] The glass panel in which the two polarizing plates produced in the examples and comparative examples were attached to a glass cell was left at a temperature of 25°C and a humidity of 90% for 72 hours, then left at room temperature for 1 hour, and further left at a temperature of 40°C and a humidity of 55% for 24 hours. The front polarizing plate was placed on the measurement table of a two-dimensional measuring instrument (NEXIV VMR-12072, manufactured by Nikon Corporation) with the front polarizing plate facing up. Next, the surface of the measurement table was focused, and the focus was set on the four corners of the glass panel, the center of each of the four sides, and the center of the glass panel surface, using that as a reference. After measuring the distance from the reference focus, the longest absolute distance from the measurement table was determined. Warping of the edge of the panel on the viewing side of the glass panel was determined as positive warping, and warping of the edge of the panel on the rear side was determined as negative warping. Two measurement samples were prepared for each of the examples and comparative examples, and measurements were performed, and the average value of the longest distance was determined as the amount of warping.

[0071] [Measurement of moisture permeability] The water vapor transmission rate of the low moisture-permeable resin layer was measured using a thermo-hygrostat under the conditions of a temperature of 40°C, a relative humidity of 90% RH, and a measurement time of 24 hours by a moisture transmission test method (cup method, conforming to JIS Z 0208), and this was taken as the moisture transmission rate.

[0072] <Example 1> A 30 μm thick polyvinyl alcohol film (average degree of polymerization about 2400, saponification degree 99.9 mol% or more) was uniaxially stretched longitudinally by about 5 times by dry stretching, and then, while maintaining tension, was immersed in pure water at 60°C for 1 minute, and then immersed in an aqueous solution at 28°C with a weight ratio of iodine / potassium iodide / water of 0.05 / 5 / 100 for 60 seconds. Thereafter, it was immersed in an aqueous solution at 72°C with a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 for 300 seconds. It was then washed with pure water at 26°C for 20 seconds, and then dried at 65°C to obtain a 12 μm thick polarizer in which iodine was adsorbed and aligned in the polyvinyl alcohol film.

[0073] Next, 3 parts by weight of carboxyl-modified polyvinyl alcohol (Kuraray Co., Ltd.'s "KL-318") was dissolved in 100 parts by weight of water to prepare a polyvinyl alcohol aqueous solution. The aqueous solution was mixed with 1.5 parts by weight of water-soluble polyamide epoxy resin (Sumitomo Chemical Co., Ltd.'s "Sumirez Resin (registered trademark) 650 (30)", solid content concentration 30 wt%) in a ratio of 100 parts by weight of water to prepare a polyvinyl alcohol aqueous solution. The aqueous solution was applied to both sides of the polarizer to a thickness of 2 μm, and a 25 μm-thick triacetyl cellulose film (Konica Amino Co., Ltd.'s "Konica Amino Co., Ltd." was then formed as a resin layer. On one side was laminated a 13 μm thick cyclic olefin resin film (manufactured by Zeon Corporation under the trade name "KC2UA" hereafter also referred to as TAC) and on the other side was laminated a 13 μm thick cyclic olefin resin film (manufactured by Zeon Corporation under the trade name "ZEONOR (registered trademark)" with an in-plane retardation value Re of 0.8 nm at a wavelength of 590 nm) (hereinafter also referred to as COP) as a resin layer. Thereafter, a 5 μm thick adhesive (an adhesive layer made of an acrylic adhesive, manufactured by Lintec Corporation) was laminated on the COP side to obtain a linear polarizing plate having a layer structure of TAC / adhesive layer / polarizer / adhesive layer / COP / adhesive layer.

[0074] The front-side polarizing plate and the rear-side polarizing plate were cut out from the produced polarizing plate to produce glass panels as follows. First, the viewing-side polarizing plate was cut to a size of 130 mm (polarizer absorption axis direction) x 90 mm (polarizer transmission axis direction), and the rear-side polarizing plate was cut to a size of 90 mm (polarizer absorption axis direction) x 130 mm (polarizer transmission axis direction). Further, the front-side polarizing plate was cut to a diagonal size of 7 inches so that the absorption axis of the front-side polarizing plate was parallel to the short side of the glass cell, and the absorption axis of the rear-side polarizing plate was parallel to the long side of the glass cell, to obtain a polarizing plate set.

[0075] The cut pair of polarizing plates was attached to a glass cell via an adhesive layer so that the short sides of the two polarizing plates were parallel to the short sides of the glass cell. The thickness of the glass cell used was 0.4 mm. L1 and L2 were each 20 μm. The amount of warping of the obtained glass panel was measured. The results are shown in Table 1.

[0076] <Comparative Example 1> A polarizing plate set was produced in the same manner as in Example 1, except that the adhesive layer having a thickness of 25 μm was used instead of the adhesive layer having a thickness of 5 μm used in Example 1. L1 and L2 were each 40 μm. The results are shown in Table 1.

[0077] [Table 1] [Explanation of symbols]

[0078] 1,2 polarizing plate set, 100 front side polarizing plate, 110,210 resin layer, 120,220 bonding layer, 130,230 polarizer, 140,240 bonding layer, 150,250 low moisture permeable resin layer, 160,260 adhesive layer, 200 rear side polarizing plate, 300 liquid crystal cell, L1,L2 distance

Claims

1. A polarizing plate set including a front-side polarizing plate arranged on a viewing side of a liquid crystal cell and a rear-side polarizing plate arranged on a rear side of the liquid crystal cell, the front-side polarizing plate and the rear-side polarizing plate each include a polarizer; when the distance from the liquid crystal cell side surface of a polarizer included in the front-side polarizing plate to the liquid crystal cell side surface of the front-side polarizing plate is L1 (μm), and the distance from the liquid crystal cell side surface of a polarizer included in the back-side polarizing plate to the liquid crystal cell side surface of the back-side polarizing plate is L2 (μm), both of L1 (μm) and L2 (μm) are 20 μm or less, The front-side polarizing plate and the rear-side polarizing plate each have a moisture permeability of 400 g / m at a temperature of 40° C. and a humidity of 90% RH on the liquid crystal cell side of the polarizer. ２ -Having a resin layer of 24 hr or less, the front-side polarizing plate and the back-side polarizing plate further include an adhesive layer on the liquid crystal cell side of the resin layer, The absolute value of the difference between L1 (μm) and L2 (μm) is 3 μm or less, the polarizers included in the front-side polarizing plate and the back-side polarizing plate have substantially the same thickness, the front-side polarizing plate and the rear-side polarizing plate are rectangular in shape having long sides and short sides, the absorption axis of the front-side polarizing plate is parallel to the short side, and the absorption axis of the rear-side polarizing plate is parallel to the long side.

2. A polarizing plate set including a front polarizing plate arranged on a viewing side of a liquid crystal cell and a rear polarizing plate arranged on a rear side of the liquid crystal cell, the front-side polarizing plate and the rear-side polarizing plate each include a polarizer; when the distance from the liquid crystal cell side surface of a polarizer included in the front-side polarizing plate to the liquid crystal cell side surface of the front-side polarizing plate is L1 (μm), and the distance from the liquid crystal cell side surface of a polarizer included in the back-side polarizing plate to the liquid crystal cell side surface of the back-side polarizing plate is L2 (μm), both of L1 (μm) and L2 (μm) are 20 μm or less, each of the front-side polarizing plate and the back-side polarizing plate has a resin layer on the liquid crystal cell side of the polarizer, the resin layer having a moisture permeability of 400 g / m 2 ·24 hr or less at a temperature of 40° C. and a humidity of 90% RH; the front-side polarizing plate and the back-side polarizing plate further include an adhesive layer on the liquid crystal cell side of the resin layer, The absolute value of the difference between L1 (μm) and L2 (μm) is 3 μm or less, the polarizers included in the front-side polarizing plate and the back-side polarizing plate have substantially the same thickness, the front-side polarizing plate and the rear-side polarizing plate are rectangular in shape having long sides and short sides, the absorption axis of the front-side polarizing plate is parallel to the long side, and the absorption axis of the rear-side polarizing plate is parallel to the short side.

3. The polarizing plate set according to claim 1 , wherein the sum of L1 (μm) and L2 (μm) is 40 μm or less.

4. The polarizing plate set according to any one of claims 1 to 3, wherein each of the front-side polarizing plate and the back-side polarizing plate comprises a cyclic cycloolefin resin film on the liquid crystal cell side of the polarizer.

5. The polarizing plate set according to any one of claims 1 to 4, wherein each of the front-side polarizing plate and the back-side polarizing plate comprises a triacetyl cellulose-based resin film on the side of the polarizer opposite to the liquid crystal cell.

6. A liquid crystal panel comprising the polarizing plate set according to any one of claims 1 to 5 and a liquid crystal cell.

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