KR20230118957A - Polarizer set and liquid crystal panel - Google Patents

Abstract

(Problem) To provide a polarizing plate set in which warpage of a liquid crystal panel is suppressed.
(Solution Means) A set of polarizing plates including a front-side polarizing plate disposed on a viewing side of a liquid crystal cell and a rear-side polarizing plate disposed on a rear-side side of the liquid crystal cell, wherein the front-side polarizing plate and the rear-side polarizing plate include a polarizer, and The distance from the liquid crystal cell-side surface of the polarizer included in the polarizing plate to the liquid crystal cell-side surface of the front-side polarizing plate is L1 (μm), and from the liquid-crystal cell-side surface of the polarizer included in the back-side polarizing plate to the liquid-crystal cell-side surface of the back-side polarizing plate When the distance to is L2 (μm), at least one of L1 (μm) and L2 (μm) is 35 μm or less, and at least one selected from the front-side polarizing plate and the rear-side polarizing plate is on the liquid crystal cell side of the polarizer , A polarizing plate set having a resin layer having a water vapor transmission rate of 400 g/m 2 24 hr or less at a temperature of 40°C and a humidity of 90% RH.

Description

Polarizer set and liquid crystal panel

The present invention relates to a polarizing plate set and a liquid crystal panel.

BACKGROUND OF THE INVENTION In an image display device or the like, a liquid crystal panel in which polarizing plates are respectively disposed on the visual side and the back side of a liquid crystal cell is used. It is known that a liquid crystal panel may warp when used in a high-temperature environment (Patent Documents 1 and 2).

Patent Document 1 proposes reducing the warpage of a liquid crystal panel in a high-temperature environment by making the tensile elastic modulus of the protective layer in the polarizing plate on the side bent into a concave shape in the polarizing plate set satisfy a predetermined expression. . In Patent Literature 2, the distance from the surface of the polarizer of the front plate-integrated polarizing plate away from the front plate to the liquid crystal cell is larger than the distance from the surface of the polarizer on the back side closer to the front plate of the polarizer to the liquid crystal cell, under a high temperature environment. It is proposed to reduce the curvature of the liquid crystal panel in the case. Patent Document 3 proposes a liquid crystal display device in which a value calculated from the thickness, elastic modulus and dimensional change rate of the polarizer and the distance from the polarizer to the liquid crystal cell is set to a specific ratio in order to reduce the warpage of the liquid crystal panel generated during pressure defoaming. there is.

Patent Document 1: Japanese Unexamined Patent Publication No. 2018-72533 Patent Document 2: Japanese Unexamined Patent Publication No. 2017-83857 Patent Document 3: International Publication No. 2015/156250

When warping occurs in a high temperature (e.g., 85°C) environment, the polarizer (hereinafter referred to as a PVA polarizer) including a polyvinyl alcohol-based resin film, which is a component of the polarizer bonded to the panel, shrinks due to heating. There are many. The PVA polarizer tends to be particularly large in shrinkage in the stretching direction by heating. The curvature of the liquid crystal panel resulting from such a PVA polarizer can be reduced in some cases by the polarizing plate set described in the above Patent Literature.

On the other hand, if a liquid crystal television module is transported by ship, for example, and the backlight is turned on after unpacking, there has been a case where the problem that warpage occurs in the liquid crystal panel has occurred. While the size of liquid crystal televisions is increasing, in the case of polarizers for large liquid crystal televisions, due to the size of the area, the amount of warping increases with respect to slight dimensional changes of the front-side polarizing plate and the rear-side polarizing plate. It becomes very important compared to the use.

An object of the present invention is to provide a polarizing plate set in which warping of a liquid crystal panel is suppressed.

The present invention provides the following polarizing plate sets and liquid crystal panels.

[1] A polarizing plate set including a front-side polarizing plate disposed on the viewing side of a liquid crystal cell and a rear-side polarizing plate disposed on the rear side of the liquid crystal cell,

The front-side polarizing plate and the rear-side polarizing plate include polarizers,

The distance from the liquid crystal cell-side surface of the 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 from the liquid crystal cell-side surface of the polarizer included in the back-side polarizing plate When the distance to the surface of the back-side polarizing plate on the liquid crystal cell side is L2 (μm), 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 resin layer having a water vapor transmission rate of 400 g / m 2 / 24 hr or less at a temperature of 40 ° C. and a humidity of 90% RH on the liquid crystal cell side of the polarizer. Polarizer set.

[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] Both the front-side polarizing plate and the back-side polarizing plate have a resin layer on the liquid crystal cell side of the polarizer having a water vapor transmission rate of 400 g / m 2 / 24 hr or less at a temperature of 40 ° C. and a humidity of 90% RH, The polarizing plate set according to any one of [1] to [4].

[6] The polarizing plate set according to any one of [1] to [5], wherein both the front-side polarizing plate and the back-side polarizing plate include a cyclic cycloolefin-based 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 both the front-side polarizing plate and the back-side polarizing plate contain a triacetyl cellulose-based resin film on the side opposite to the liquid crystal cell of the polarizer.

[8] A liquid crystal panel comprising the polarizing plate set according to any one of [1] to [7] and a liquid crystal cell.

According to the present invention, it is possible to provide a polarizing plate set in which warping of a liquid crystal panel is suppressed.

1 is a schematic cross-sectional view showing the layer configuration of a polarizing plate set of the present invention.
2 is a schematic cross-sectional view showing another layer configuration of the polarizing plate set of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described referring drawings, this invention is not limited to the following embodiment. In all of the drawings below, each component is shown with appropriately adjusted scales for easy understanding, and the scale of each component shown in the drawings and the scale of the actual component do not necessarily match.

<Polarizer Set>

A polarizing plate set according to an aspect of the present invention will be described with reference to FIG. 1 . The polarizing plate set 1 shown in FIG. 1 is composed of a front-side polarizing plate 100 disposed on the viewing side of the liquid crystal cell 300 and a rear-side polarizing plate 200 disposed on the rear side of the liquid crystal cell 300. do. The front-side polarizing plate 100 and the back-side polarizing plate 200 may be of the same type or of different types. A liquid crystal panel can be produced by bonding a polarizing plate set to a liquid crystal cell.

The front-side polarizing plate 100 and the rear-side polarizing plate 200 may have, for example, a rectangular shape, preferably a rectangular shape having a long side and a short side, and more preferably a rectangular shape. The size of the front-side polarizing plate 100 and the rear-side polarizing plate 200 is preferably a rectangular 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 a long side of 800 mm or more and a short side of 450 mm or more. It is preferable to have a rectangular shape (equivalent to a 40-inch type). In addition, the size of the front-side polarizing plate 100 and the rear-side polarizing plate 200 is preferably a rectangular 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 a long side of 1300 mm or more and a short side of 700 mm or more. It is preferable that it is a rectangular shape (equivalent to a 60-inch type) having a short side.

The polarizer set 1 may be disposed in the liquid crystal cell so that the transmission axes of the front-side polarizer 100 and the rear-side polarizer 200 are substantially perpendicular to each other. The angle of the transmission axis of the rear-side polarizing plate 200 with respect to the transmission axis of the front-side polarizing plate 100 may be, for example, within the range of 90 ± 5 °, preferably within the range of 90 ± 1 °, more preferably It is within the range of 90±0.5°.

The planar view shapes of the front-side polarizing plate 100, the back-side polarizing plate 200, and the liquid crystal cell 300 may be, for example, a rectangular shape, preferably a rectangular shape having a long side and a short side, and more preferably is a rectangle. When the front-side polarizing plate 100, the back-side polarizing plate 200, and the liquid crystal cell 300 have a rectangular shape in plan view, the polarizing plate set 1 has a direction in which the absorption axis of the polarizer of the front-side polarizing plate 100 is the liquid crystal cell. may be arranged so that the direction of the absorption axis of the polarizer of the back-side polarizing plate 200 is substantially parallel to the direction of the short side of the liquid crystal cell, or the direction of the absorption axis of the polarizer of the front-side polarizing plate 100 is substantially parallel to the direction of the long side of It may be arranged so that it is substantially parallel to the direction of the short side of the liquid crystal cell, and the direction of the absorption axis of the polarizer of the back-side polarizing plate 200 is substantially parallel to the direction of the long side of the liquid crystal cell. Substantially parallel means that, for example, the angle between the absorption axis of the polarizing plate and the long side or short side of the liquid crystal cell may be 5° or less, preferably 3° or less, and more preferably 1° or less.

Both the front-side polarizing plate 100 and the rear-side polarizing plate 200 include a polarizer and a resin layer, although not shown. 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 the liquid crystal cell. The front-side polarizing plate 100 and the rear-side polarizing plate 200 may further include, for example, a bonding layer, a retardation layer, a protective film, and the like, in addition to a polarizer and a resin layer described later.

In the polarizing plate set 1, the distance from the liquid crystal cell 300-side surface of the polarizer included in the front-side polarizing plate 100 to the liquid crystal cell 300-side surface of the front-side polarizing plate 100 is L1 (μm) , and when the distance from the plane of the liquid crystal cell 300 side of the polarizer included in the back-side polarizing plate 200 to the plane of the liquid crystal cell 300 side of the back-side polarizing plate 200 is L2 (μm), L1 At least one of (μm) and L2 (μm) is 35 μm or less, and at least one selected from the front-side polarizing plate 100 and the back-side polarizing plate 200 is, on the liquid crystal cell side of the polarizer, a temperature of 40 ° C. and It has a resin layer (not shown) whose moisture permeability at a humidity of 90% RH (hereinafter also referred to as moisture permeability for simplicity) is 400 g/m 2 24 hr or less. The liquid crystal cell 300-side surface of the front-side polarizing plate 100 and the liquid crystal cell 300-side surface of the back-side polarizing plate 200 are included in the front-side polarizing plate 100 and the rear-side polarizing plate 200. The surface at the side of the liquid crystal cell of an adhesive layer (separate film is not included) is said.

According to the present inventors, the polarizer, which is a component of the polarizing plate bonded to the liquid crystal cell, gradually absorbs moisture when exposed to a high humidity environment for a long time, and then turns on the backlight and deforms the polarizer according to the movement of moisture over time, It was found that warping of the liquid crystal cell occurred with this deformation. For example, when liquid crystal television modules are transported by ship, humidity is high at the bottom of the ship, and the polarizing plate bonded to the liquid crystal cell is in a state where moisture is absorbed over a long period of time. In the method of simply reducing the shrinkage force of the polarizer or the polarizer after unpacking in that state, it is difficult to sufficiently prevent the intrusion of moisture from the outside, the amount of absorption of the polarizer increases, and as a result, the amount of deformation increases. As a result of intensive examination by the present inventors, at least one of the L1 (μm) and L2 (μm) is set to 35 μm or less, and at least one selected from the front-side polarizing plate and the back-side polarizing plate is on the liquid crystal cell side of the polarizer, It was discovered that there is a tendency for the amount of curvature of the liquid crystal panel to be easily reduced by having a resin layer having a water vapor transmission rate of 400 g/m 2 24 hr or less. It is estimated that this is because the energy of the strain stored in the liquid crystal cell side can be made smaller than the polarizer while suppressing the penetration of moisture from the liquid crystal cell side of the polarizer.

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

Both L1 (μm) and L2 (μm) are preferably 35 μm or less, more preferably 30 μm or less, still more preferably 25 μm or less, particularly preferably, from the viewpoint of the amount of warping of the liquid crystal panel. 20 μm or less.

The sum of L1 (μm) and L2 (μm) is preferably 60 μm or less, more preferably 50 μm or less, still more preferably 40 μm or less, from the viewpoint of the amount of warping of the liquid crystal panel.

L1 (μm) and L2 (μm) can be set to the same extent in order to make the distortion forces of the front-side polarizer and the rear-side polarizer on the liquid crystal cell equal and cancel each other out. The absolute value of the difference between L1 (μm) and L2 (μm) is preferably 3 μm or less, more preferably 2 μm or less, still more preferably 1 μm or less, from the viewpoint of the amount of warping of the liquid crystal panel. Especially preferably, it is 0.

[Polarizer]

A polarizer has a property of absorbing linearly polarized light having a vibration plane parallel to the absorption axis and transmitting linearly polarized light having a vibration plane orthogonal 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.

The polarizer may be a film in which iodine is adsorbed to a known polyvinyl alcohol-based resin. The polarizer includes, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin, a step of dyeing a polyvinyl alcohol-based resin with iodine and adsorbing iodine, a step of treating a polyvinyl alcohol-based resin adsorbed with iodine with an aqueous solution of boric acid, And it can be manufactured through the process of washing with water after treatment with boric acid aqueous solution.

A polyvinyl alcohol-type resin is obtained by saponifying a polyvinyl acetate-type resin. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and the other monomer copolymerizable with it other than the polyvinyl acetate which is a homopolymer of vinyl acetate is 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 acryl and methacryl. The same applies to "(meth)acrylate" and the like.

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

The thickness of the polarizer may be preferably 30 μm or less, more preferably 25 μm or less, still more preferably 20 μm or less, and particularly preferably 15 μm or less, from the viewpoint of low 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 the deformation of the polarizers of the front-side polarizer 100 and the back-side polarizer 200, it is preferable to use polarizers having substantially the same thickness for the front-side polarizer 100 and the rear-side polarizer 200.

[Resin Layer]

The resin layer may be disposed on one side or both sides of the polarizer, directly on the polarizer or through a bonding layer described later, to protect the polarizer, particularly the surface of the polarizer. The resin layer may be an optically transparent thermoplastic resin film or a coating film. When a plurality of resin layers are included in the front-side polarizing plate 100 and the back-side polarizing plate 200, the resin layers may be of the same type or different types.

A thermoplastic resin film may be bonded to one side or both sides of the polarizer. As the thermoplastic resin film, for example, a light-transmitting, preferably optically transparent thermoplastic resin film may be used. , polyolefin-based resins such as cyclic polyolefin-based resins (norbornene-based resins, etc.); cellulosic resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin; Ethylene-vinyl acetate type resin; polystyrene-based resin; polyamide-based resin; polyetherimide-based resins; (meth)acrylic resins such as polymethyl (meth)acrylate resin; polyimide-based resin; polyethersulfone-based resins; polysulfone-based resins; polyvinyl chloride-based resins; polyvinylidene chloride-based resins; polyvinyl alcohol-based resin; polyvinyl acetal-based resins; polyether ketone-based resins; polyether ether ketone-based resins; polyethersulfone-based resins; Polyamide-imide-type resin etc. are mentioned. A thermoplastic resin can be used individually or in mixture of 2 or more types. Among them, from the viewpoint of strength and light transmittance, a triacetyl cellulose-based resin film, a cyclic polyolefin-based resin film, and a (meth)acrylic-based resin film are preferable.

The thermoplastic resin film may or may not have a phase difference. The thermoplastic resin film, if necessary, contains a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, an optical brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, etc. may be

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. Moreover, it is usually 1 μm or more, preferably 5 μm or more, and more preferably 15 μm or more.

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

By forming a hard coat layer on the thermoplastic resin film, it can be set as a resin film with improved hardness and scratch resistance. 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 the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard coat layer may contain additives in order to improve strength. The additive is not limited, and includes inorganic fine particles, organic fine particles, or mixtures thereof.

The resin layer as a coating film may be a layer obtained by applying and curing a coating composition such as a composition used for the hard coat layer described above, a cation curable composition such as an epoxy resin, or a radical curable composition such as (meth)acrylate. Moreover, the resin layer which is a coating film may be a layer formed by using aqueous solution, such as a polyvinyl alcohol-type resin, as a coating composition, apply|coating this to the surface of a polarizer, and drying it. The resin layer, which is a coating film, may contain a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, an optical whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, and the like, if necessary.

The thickness of the resin layer serving as the coating film may be, for example, 30 µm or less, preferably 25 µm or less, more preferably 20 µm or less, still more preferably 15 µm, and particularly preferably 10 µm. The thickness of the resin layer serving as a coating film may be, for example, 0.1 μm or more.

[Resin layer having a moisture permeability of 400 g/m 2 24 hr or less]

At least one of the front-side polarizing plate 100 and the back-side polarizing plate 200 has a resin layer having a moisture permeability of 400 g/m 2 24 hr or less (hereinafter, also referred to as a low moisture permeability resin layer for simplicity) on the liquid crystal cell side of the polarizer. include In this specification, the moisture permeability can be measured according to the method described in the section of Examples to be described later.

The low moisture permeability resin layer has a moisture permeability of preferably 300 g/m2/24 hr or less, more preferably 200 g/m2/24 hr or less, still more preferably 100 g/m2/24 hr or less, from the viewpoint of the amount of curvature of the liquid crystal panel. It is m2*24 hr or less, Especially preferably, it includes the resin layer which is 80 g/m2*24 hr or less. The low moisture permeability resin layer may be, for example, 10 g/m 2 24 hr or more, preferably 30 g/m 2 24 hr or more.

It is preferable that both the front-side polarizing plate 100 and the back-side polarizing plate 200 include a low moisture permeability resin layer. When both the front-side polarizing plate 100 and the back-side polarizing plate 200 include a low moisture permeability resin layer, the low moisture permeability resin layers may be of the same type or different types. In addition to the thermoplastic resin film and coating film described above, the low moisture permeability resin layer may be a stretched thermoplastic resin film, a coating film prepared by a casting method, or a layer containing a cured product of a photocurable resin composition. As a low moisture permeability resin layer, Preferably it is a thermoplastic resin film containing resin which uses cyclic polyolefin as a main monomer.

[bonding layer]

The bonding layer may be a layer bonding the polarizer and the resin layer together. The bonding layer may be formed of an adhesive or a pressure-sensitive adhesive. Examples of the adhesive include active energy ray-curable adhesives such as ultraviolet curable adhesives, aqueous solutions of polyvinyl alcohol-based resins or aqueous solutions in which a crosslinking agent is blended, and water-based adhesives such as urethane emulsion adhesives. When bonding a thermoplastic resin film on both surfaces of a polarizer, the adhesive which forms two bonding layers may be of the same type or of a different type. For example, when bonding a thermoplastic resin film on both sides, one side may be bonded using a water-based adhesive and the other side may be bonded using an active energy ray-curable adhesive. The ultraviolet curable adhesive may be a mixture of a radically polymerizable (meth)acrylic compound and a radical photopolymerization initiator, or a mixture of a cationically polymerizable epoxy compound and a photocationic polymerization initiator. Moreover, a cationically polymerizable epoxy compound and a radically polymerizable (meth)acrylic compound may be used together, and a photocationic polymerization initiator and a photoradical polymerization initiator may be used together as an initiator. The thickness of the adhesive may be, for example, 0.1 μm or more and 5 μm or less.

In the case of using an active energy ray-curable adhesive, the adhesive is cured by irradiating an active energy ray after bonding. The light source of the active energy ray is not particularly limited, but an active energy ray (ultraviolet ray) having a luminous distribution at a wavelength of 400 nm or less is preferable, specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, and a black light. A lamp, a microwave excited mercury lamp, a metal halide lamp or the like is preferably used.

In order to improve the adhesion between the polarizer and the thermoplastic resin film, prior to bonding the polarizer and the thermoplastic resin film, corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, and primer are applied to the bonding surface of at least one of the polarizer and the thermoplastic resin film. You may perform surface treatment, such as a coating process and a saponification process.

When the bonding layer is formed of an adhesive, the thickness of the bonding layer may be, for example, 0.01 μm or more and 10 μm.

As the adhesive used for the bonding layer, it can be, for example, a pressure-sensitive adhesive (hereinafter also referred to as an adhesive).

The pressure-sensitive adhesive can be composed of a pressure-sensitive adhesive composition containing a resin such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether as a main component. Among them, from the viewpoints of transparency, weather resistance, heat resistance and storage modulus, it is preferably a pressure-sensitive adhesive composition having a (meth)acrylic resin as a base polymer. The pressure-sensitive adhesive composition may be of an active energy ray curing type or a thermosetting type.

Examples of the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include (meth)acrylates such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The polymer or copolymer which uses 1 type(s) or 2 or more types of acrylic acid ester as a monomer is used suitably. It is preferable to copolymerize a polar monomer to the base polymer. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycylate. and monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as dil (meth)acrylate.

The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. As a crosslinking agent, as a divalent or higher metal ion, Forming a carboxylic acid metal salt between carboxyl groups; As a polyamine compound, what forms an amide bond between carboxyl groups; Forming an ester bond between a carboxyl group as a polyepoxy compound or a polyol; As the polyisocyanate compound, those forming an amide bond between carboxyl groups are exemplified. Especially, a polyisocyanate compound is preferable.

In the case of forming the bonding layer with an adhesive, for example, a method of dissolving or dispersing the adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, and directly applying this to the bonding surface to form an adhesive layer, or a release treatment A pressure-sensitive adhesive layer may be formed in a sheet form on the separated film to which the is applied, and the adhesive layer may be transferred to a bonding surface.

The separation film may be a film made of polyethylene-based resins such as polyethylene, polypropylene-based resins such as polypropylene, and polyester-based resins such as polyethylene terephthalate. Especially, the stretched film of polyethylene terephthalate is preferable.

The pressure-sensitive adhesive may contain optional components such as glass fibers, glass beads, resin beads, fillers including metal powder or other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, and the like.

Examples of the antistatic agent include ionic compounds, conductive fine particles, and conductive polymers, but ionic compounds are preferably used.

The cation component constituting the ionic compound may be an inorganic cation or an organic cation.

Examples of organic cations include pyridinium cations, imidazolium cations, ammonium cations, sulfonium cations, phosphonium cations, piperidinium cations, and pyrrolidinium cations. Examples of inorganic cations include lithium ions and potassium ions. can

On the other hand, the anion component constituting the ionic compound may be an inorganic anion or an organic anion, but from the viewpoint of providing an ionic compound with excellent antistatic performance, an anion component containing a fluorine atom is preferable. As the anion component containing a fluorine atom, hexafluorophosphate anion [(PF ₆ ^- )], bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ^- ] anion, bis(fluoro rosulfonyl)imide anion [(FSO ₂ ) ₂ N ^- ] anion; and the like.

The thickness of the bonding layer formed of the pressure-sensitive adhesive may be, for example, 30 μm or less, preferably 25 μm or less, and more preferably 20 μm or less. The thickness of the bonding layer formed of the pressure-sensitive adhesive may be, for example, 1 μm or more, preferably 2 μm or more, and more preferably 3 μm or more.

In order to improve adhesion, surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, primer coating treatment, and saponification treatment may be performed on the bonding surface.

[Adhesive layer]

The pressure-sensitive adhesive layer may have a function of bonding the front-side polarizing plate 100 and the rear-side polarizing plate 200 to the liquid crystal cell 300 . As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, conventionally known pressure-sensitive adhesives can be used without particular limitation, and the pressure-sensitive adhesives exemplified in the bonding layer described above can be used. Moreover, an active energy ray-curable pressure-sensitive adhesive, a thermosetting pressure-sensitive adhesive, or the like may be used. The pressure-sensitive adhesive layer may have a separate film.

[Phase difference layer]

The front-side polarizer 100 and the rear-side polarizer 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 comprising two or more retardation layers. The retardation layer may be laminated on a polarizer or a linear polarizing plate through the aforementioned bonding layer.

As the retardation layer, a positive A layer such as a λ/4 layer or a λ/2 layer and a positive C layer can be used. The retardation layer may be formed of a liquid crystal cured layer containing a cured product of a polymerizable liquid crystal compound, or may be formed of a resin film exemplified as a material for the thermoplastic resin film described above. The film type retardation layer 130 may further contain an orientation layer or a substrate.

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

The thickness of the retardation layer may be, for example, 0.1 μm or more and 50 μm or less, preferably 1 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 15 μm or less.

[Protect Film]

The front-side polarizing plate 100 and the back-side polarizing plate 200 may have a protective film on the side opposite to the liquid crystal cell 300 . After the polarizing plate is bonded to a liquid crystal cell or another optical member, the protection film can be peeled off together with the pressure-sensitive adhesive layer it has, for example.

A protection film is comprised, for example of a base film and the adhesive layer laminated|stacked on it. The description of the bonding layer described above is applied to the pressure-sensitive adhesive layer. 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, and a polycarbonate-based resin. there is. Preferably, they are polyester-based resins, such as polyethylene terephthalate.

The thickness of the protective film is not particularly limited, but is preferably in the range of 20 μm or more and 200 μm or less, for example. When the thickness of the substrate is 20 μm or more, strength tends to be easily imparted to the front-side polarizing plate 100 and the back-side polarizing plate 200.

[Layer composition of the polarizer set]

A polarizing plate set according to an aspect of the present invention will be described with reference to FIG. 2 . The polarizing plate set 2 shown in FIG. 2 is composed of a front-side polarizing plate 101 disposed on the viewing side of the liquid crystal cell 300 and a rear-side polarizing plate 201 disposed on the rear side of the liquid crystal cell 300. do. The front-side polarizer 101 and the rear-side polarizer 201 each include polarizers 130 and 230 . The front-side polarizing plate 101 further includes a resin layer 110 , a low moisture permeability resin layer 150 , bonding layers 120 and 140 , and an adhesive layer 160 . In addition, as shown in FIG. 1 , the rear-side polarizing plate 201 further includes a resin layer 210 , a low moisture permeability resin layer 250 , bonding layers 220 and 240 , and an adhesive layer 260 .

[Method for producing polarizing plate]

The front-side polarizing plate and the back-side polarizing plate can be manufactured by, for example, bonding each layer with a bonding layer. In the case of bonding, it is preferable to perform a surface activation treatment such as corona treatment on one or both sides of the bonded surface in order to improve adhesion.

The pressure-sensitive adhesive layer can be prepared as a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet is prepared by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a pressure-sensitive adhesive liquid, forming a layer containing the pressure-sensitive adhesive in a sheet form on a release film subjected to release treatment, and the pressure-sensitive adhesive It can produce by the system etc. which bond another peeling film further on a layer. Each layer can be bonded by a method in which a pressure-sensitive adhesive sheet from which one release film is peeled off is bonded to one layer (e.g. polarizing plate), then the other release film is peeled off, and the other layer (e.g. liquid crystal cell) is bonded. .

As a method of coating the adhesive liquid on the release film, a conventional coating technique using a die coater, comma coater, reverse roll coater, gravure coater, rod coater, wire bar coater, doctor blade coater, air doctor coater, etc. may be employed. .

The release film is preferably composed of a plastic film and a release layer. As a plastic film, polyester films, such as a polyethylene terephthalate film, a polybutylene terephthalate film, and a polyethylene naphthalate film, and polyolefin films, such as a polypropylene film, are mentioned. In addition, the peeling layer can be formed of, for example, a composition for forming a peeling layer. The main component (resin) constituting the composition for forming a release layer is not particularly limited, but includes silicone resins, alkyd resins, acrylic resins, and long-chain alkyl resins.

[liquid crystal cell]

A liquid crystal cell has two cell substrates and a liquid crystal layer sandwiched between these substrates. The cell substrate is generally made of glass in many cases, but may be a plastic substrate. In addition, the liquid crystal cell itself used in the liquid crystal panel of the present invention can be composed of various types employed in this field (for example, known ones such as IPS mode, VA mode, and TN mode as drive modes).

[liquid crystal panel]

A liquid crystal panel can be produced by bonding a polarizing plate to a liquid crystal cell through an adhesive layer.

Example

Hereinafter, the present invention will be described in more detail by examples. "%" and "part" in the example are mass % and mass part unless otherwise specified.

[Measurement of thickness]

It was measured using a digital micrometer (MH-15M, manufactured by Nikon Corporation).

[Measurement of warp amount]

A glass panel in which two polarizing plates produced in Examples and Comparative Examples were bonded to a glass cell was left to stand for 72 hours at a temperature of 25° C. and a humidity of 90%, and then left at room temperature for 1 hour. Further, it was allowed to stand for 24 hours under conditions of a temperature of 40°C and a humidity of 55%.

The front-side polarizing plate was placed on the measuring table of a two-dimensional measuring instrument (NEXIV VMR-12072, manufactured by Nikon Co., Ltd.) with the front-side polarizing plate facing upward. Subsequently, the surface of the measurement table was focused, and using that as a reference, the four corners of the glass panel, the center of each of the four sides, and the center of the surface of the glass panel were focused. After measuring the distance from the focal point as a standard, the longest distance from the measuring table was obtained as an absolute value. The curvature where the edge of the panel was bent toward the viewing side of the glass panel was defined as positive warpage, and the warpage where the edge of the panel was bent toward the back side was defined as negative warpage. For Examples and Comparative Examples, two measurement samples were prepared and measured, and the average value of the longest distance was determined as the amount of warpage.

[Measurement of moisture permeability]

Regarding the low moisture permeability resin layer, using a constant temperature and humidity chamber, the water vapor transmission rate was measured by the moisture permeability test method (cup method, according to JIS Z 0208) under measurement conditions of a temperature of 40 ° C., a relative humidity of 90% RH, and a measurement time of 24 hours. It measured and made this the water vapor transmission rate.

<Example 1>

A polyvinyl alcohol film (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) with a thickness of 30 μm was longitudinally uniaxially stretched by about 5 times by dry stretching, and while maintaining the tension state, pure water at 60 ° C. After being immersed in for 1 minute, the weight ratio of iodine/potassium iodide/water was 0.05/5/100 and immersed in an aqueous solution at 28°C for 60 seconds. Then, it was immersed for 300 seconds in an aqueous solution at 72°C having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100. Subsequently, after washing with pure water at 26°C for 20 seconds, a drying treatment was performed at 65°C to obtain a polarizer having a thickness of 12 μm in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

Next, to an aqueous solution prepared by dissolving 3 parts by weight of carboxyl group-modified polyvinyl alcohol [“KL-318” manufactured by Kuraray Co., Ltd.] on both sides of the polarizer with respect to 100 parts by weight of water to prepare an aqueous solution of polyvinyl alcohol. A water-soluble polyamide epoxy resin [“Sumirez Resin (registered trademark) 650 (30)” manufactured by Sumitomo Chemical Co., Ltd., solid content concentration: 30% by weight] was mixed at a rate of 1.5 parts by weight with respect to 100 parts by weight of water An aqueous adhesive was applied to a thickness of 2 μm, and a triacetyl cellulose film [trade name “KC2UA” manufactured by Konica Minolta Co., Ltd.] (hereinafter also referred to as TAC) having a thickness of 25 μm was bonded as a resin layer, and a water-based adhesive was applied to the other side. A cyclic olefin-based resin film having a thickness of 13 μm [Nippon Zeon Co., Ltd., trade name “ZEONOR (registered trademark)”, in-plane retardation value Re = 0.8 nm at a wavelength of 590 nm] (hereinafter also referred to as COP) was used as a stratum layer. After bonding, a 5 μm-thick adhesive [a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive, manufactured by Lintec Co., Ltd.] is bonded to the COP side, and the layer configuration of TAC / adhesive layer / polarizer / adhesive layer / COP / adhesive layer A linear polarizing plate was obtained.

A front-side polarizing plate and a back-side polarizing plate were cut out from the produced polarizing plate, and a glass panel was produced as follows. First, the visual-side polarizing plate is 130 mm (in the direction of the absorption axis of the polarizer) × 90 mm (in the direction of the transmission axis of the polarizer), and the back-side polarizing plate is 90 mm (in the direction of the absorption axis of the polarizer) × 130 mm (in the direction of the transmission axis of the polarizer). It was tailored to be Further, the polarizer set was cut into a diagonal size of 7 inches such 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 back-side polarizing plate was parallel to the long side of the glass cell.

A pair of cut polarizing plates were bonded to the glass cell through 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 warpage was measured for the obtained glass panel. The results are shown in Table 1.

<Comparative Example 1>

A polarizing plate set was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive layer having a thickness of 5 μm used in Example 1 was changed to a pressure-sensitive adhesive layer having a thickness of 25 μm. L1 and L2 were each 40 μm. The results are shown in Table 1.

1, 2: polarizer set 100: front-side polarizer
110, 210: resin layer 120, 220: bonding layer
130, 230: polarizer 140, 240: bonding layer
150, 250: low moisture permeability resin layer 160, 260: adhesive layer
200: back-side polarizer 300: liquid crystal cell
L1, L2: Distance

Claims (8)

A polarizing plate set including a front-side polarizing plate disposed on a viewing side of a liquid crystal cell and a rear-side polarizing plate disposed on a rear side of the liquid crystal cell,
The front-side polarizing plate and the rear-side polarizing plate include polarizers,
The distance from the liquid crystal cell-side surface of the 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 from the liquid crystal cell-side surface of the polarizer included in the back-side polarizing plate When the distance to the surface of the rear-side polarizing plate on the liquid crystal cell side is L2 (μm), 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 resin layer having a water vapor transmission rate of 400 g / m 2 / 24 hr or less at a temperature of 40 ° C. and a humidity of 90% RH on the liquid crystal cell side of the polarizer A polarizing plate having set. The polarizing plate set according to claim 1 , wherein the sum of the L1 (μm) and the L2 (μm) is 60 μm or less. The polarizing plate set according to claim 1 or 2, wherein an absolute value of a difference between the L1 (μm) and the L2 (μm) is 3 μm or less. The polarizer set according to any one of claims 1 to 3, wherein polarizers included in the front-side polarizing plate and the rear-side polarizing plate have substantially the same thickness. The method according to any one of claims 1 to 4, wherein both the front-side polarizing plate and the back-side polarizing plate have a moisture permeability of 400 g on the liquid crystal cell side of the polarizer at a temperature of 40 ° C and a humidity of 90% RH. A polarizing plate set having a resin layer of /m 2 24 hr or less. The polarizing plate set according to any one of claims 1 to 5, wherein both the front-side polarizing plate and the rear-side polarizing plate include a cyclic cycloolefin-based resin film on the liquid crystal cell side of the polarizer. The polarizing plate set according to any one of claims 1 to 6, wherein both the front-side polarizing plate and the rear-side polarizing plate include a triacetyl cellulose-based resin film on a side of the polarizer opposite to the liquid crystal cell. A liquid crystal panel comprising the polarizing plate set according to any one of claims 1 to 7 and a liquid crystal cell.