JP2019079058A - Polarizing plate set - Google Patents

Abstract

An object of the present invention is to reduce the warpage of a liquid crystal panel in a high temperature environment and facilitate the manufacture of a liquid crystal display device, and to reduce the warpage of the liquid crystal panel in a room temperature environment and to reduce defects during actual use. A set of polarizing plates comprising a viewing-side polarizing plate disposed on the viewing side of a liquid crystal cell and a back-side polarizing plate disposed on the back side of the liquid crystal cell, wherein the viewing-side polarizing plate comprises: A first protective film, a first polarizer, and a second protective film are provided in this order, and the back-side polarizing plate includes a third protective film, a second polarizer, and a brightness enhancement film in this order. The difference obtained by subtracting the thickness of the back polarizer from the thickness of the viewing polarizer is 13 μm or less, and the difference of subtracting the thickness of the second polarizer from the thickness of the first polarizer is 0 μm. A set of polarizing plates exceeding 5 μm. [Selection] Figure 1

Description

  The present invention relates to a set of polarizers.

  Liquid crystal display devices are used in various display devices by taking advantage of features such as low power consumption, low voltage operation, and lightness and thinness. The liquid crystal panel constituting the liquid crystal display device has a configuration in which a pair of polarizing plates is laminated on both sides of a liquid crystal cell.

  Particularly in liquid crystal panels for mobile applications, in order to reduce power consumption while improving the brightness of the screen, the polarizing plate disposed on the back side of the liquid crystal cell may be provided with a brightness enhancement film. The brightness enhancement film is a film having a property of reflecting linearly polarized light of a predetermined polarization axis or circularly polarized light of a predetermined direction and transmitting other light when the backlight light of the liquid crystal display device or its reflected light is incident.

  However, when the rear side polarizing plate is provided with the brightness enhancement film, the liquid crystal panel is warped even in a normal temperature environment due to the difference in the members of the polarizing plate disposed above and below the liquid crystal cell. There is a problem that problems occur when the backlight unit and the cover glass are pasted together. In recent years, the fact that the thickness of the glass substrate that constitutes the liquid crystal cell is thin is also exacerbating this problem.

  For example, in Patent Document 1, the thickness of the triacetyl cellulose film to be bonded to each polarizer is made different between the polarizing plate disposed on the viewing side and the polarizing plate disposed on the back side. There is disclosed a method of reducing the warpage of a liquid crystal panel under a normal temperature environment.

  However, there is still room for improvement in reducing warpage in a normal temperature environment. Furthermore, Patent Document 1 mentioned above does not consider warpage in a high temperature environment with actual use in mind, and the polarizing plate described in Patent Document 1 has a problem that warpage is large in a severe environment. I have it.

JP 2002-207211 A

  It is an object of the present invention to reduce the warpage of a liquid crystal panel in a normal temperature environment and reduce the warpage of the liquid crystal panel in a high temperature environment while reducing the manufacturing trouble of the liquid crystal panel while facilitating the manufacture of the liquid crystal display. I assume.

[1] A set of polarizing plates comprising a viewing side polarizing plate disposed on the viewing side of the liquid crystal cell and a back side polarizing plate disposed on the back side of the liquid crystal cell,
The viewing side polarizing plate includes a first protective film, a first polarizer, and a second protective film in this order,
The back side polarizing plate includes a third protective film, a second polarizer, and a brightness enhancement film in this order,
The difference obtained by subtracting the thickness of the back side polarizing plate from the thickness of the viewing side polarizing plate is 13 μm or less,
A set of polarizing plates in which a difference obtained by subtracting the thickness of the second polarizer from the thickness of the first polarizer is more than 0 μm and not more than 5 μm.
[2] The thickness of the first polarizer is 7 μm or more and 15 μm or less,
The set of the polarizing plate according to [1], wherein the thickness of the second polarizer is 4 μm or more and 12 μm or less.
[3] The set of polarizing plates according to [1] or [2], wherein the thickness of the viewing side polarizing plate and the thickness of the back side polarizing plate are both 100 μm or less.
The liquid crystal panel which has a set of the polarizing plate in any one of [4] [1]-[3].

  According to the set of the polarizing plate of the present invention, the warpage of the liquid crystal panel in a high temperature environment can be reduced while the warpage of the liquid crystal panel in a normal temperature environment is reduced.

It is sectional drawing which shows an example of the set of the polarizing plate of this invention. It is sectional drawing which shows an example of the visual recognition side polarizing plate which comprises the set of the polarizing plate of this invention. It is sectional drawing which shows an example of the back side polarizing plate which comprises the set of the polarizing plate of this invention. It is sectional drawing which shows an example of the liquid crystal panel of this invention. It is a top view which shows the position which measured curvature amount of a glass sample.

  The set of polarizing plates and the liquid crystal panel of the present invention will be described with reference to the drawings as appropriate. The set of polarizing plates of the present invention has a viewing side polarizing plate disposed on the viewing side of the liquid crystal cell and a back side polarizing plate disposed on the back side of the liquid crystal cell.

  In one embodiment, the polarizing plate of the present invention has the members shown in FIG. The set of polarizing plates shown in FIG. 1 has a viewing side polarizing plate 1 and a back side polarizing plate 2. The viewing side polarizing plate 1 includes a first protective film 20, a first polarizer 10, a second protective film 21, and a first pressure-sensitive adhesive layer 40 in this order. The back side polarizing plate 2 includes a brightness enhancement film 30, a third pressure-sensitive adhesive layer 42, a second polarizer 11, a third protective film 22, and a second pressure-sensitive adhesive layer 41 in this order. The first pressure-sensitive adhesive layer 40 and the second pressure-sensitive adhesive layer 41 can be pressure-sensitive adhesive layers for bonding each polarizing plate to a liquid crystal cell, and are eventually incorporated into a liquid crystal display device Therefore, in the present invention, the thickness of the pressure-sensitive adhesive layer is included in the thickness of the polarizing plate.

  In addition, as shown in FIGS. 2 and 3, the separator on the first pressure-sensitive adhesive layer 40 and the second pressure-sensitive adhesive layer 41 is a separator until the set of polarizing plates of the present invention is bonded to the liquid crystal cell. 50 and separator 51 are preferably temporarily adhered and bonded, and on the first protective film 20 and the brightness enhancement film 30, the protective film 60 and the protect film 61 may be temporarily adhered and bonded. preferable. The separators 50 and 51 and the protect films 60 and 61 are peeled off in the process of manufacturing the liquid crystal display device, and thus are not finally incorporated into the liquid crystal display device. Therefore, in the present invention, the thicknesses of the separator and the protective film are not included in the thickness of the polarizing plate. Specifically, with respect to the thickness of each polarizing plate constituting the set of polarizing plates of the present invention, for example, the arrow 100 shown in FIG. For example, the arrow 200 shown in FIG. 3 is the thickness of the back side polarizing plate.

  In addition, in FIG. 1, the adhesive layer or the adhesive layer for bonding a polarizer and a protective film is abbreviate | omitted. That is, for example, an adhesive layer or a pressure-sensitive adhesive layer (not shown) is present between the first protective film 20 and the first polarizer. The viewing side polarizing plate and the back side polarizing plate may be provided with any layer other than that shown in FIG.

  In the set of polarizing plates of the present invention, the difference between the thickness of the viewing side polarizing plate and the thickness of the back side polarizing plate is 13 μm or less, preferably −2 to 13 μm, more preferably −2 to 10 μm More preferably, it is 1 to 10 μm. Furthermore, in the set of the polarizing plate of the present invention, the difference obtained by subtracting the thickness of the second polarizer of the back side polarizing plate from the thickness of the first polarizer of the polarizing plate of the viewing side is more than 0 μm and 10 μm or less And is preferably more than 0 μm and 7 μm, more preferably more than 0 μm and 5 μm or less, and may be 1 μm or more. The thickness of the first polarizer is preferably larger than the thickness of the second polarizer.

  By thus providing the polarizing plate and the polarizer with a thickness difference, it is possible to suppress the warpage of the liquid crystal panel in a high temperature environment while suppressing the warpage of the liquid crystal panel in a normal temperature environment. The reason is not clear, but it is considered that, as will be described later, coupled with the difference in thickness of the polarizer, it is possible to equalize the inflow and outflow of moisture of each member constituting the polarizing plate under a normal temperature environment. In addition, in a high temperature environment, when the brightness enhancement film is a stretched film, the contraction force of the back side polarizing plate and the contraction force of the viewing side polarizing plate can be made comparable to each other in the high temperature environment. It is believed that the warpage of can be reduced.

In the set of the polarizing plate of the present invention, the moisture content of the viewing side and the viewing side polarizing plate and the moisture content of the back side polarizing plate are preferably 5% or less, and may be 3% or less. In the present specification, the moisture content of the polarizing plate is a value measured by the loss on drying method. Specifically, the weight (weight before drying) when left to stand in an environment of 23 ° C. and 55% humidity for 3 days is measured, and then the weight when left to stand in an environment of 105 ° C. for 1 hour (after drying The weight of (1) is measured and calculated based on the following equation. The moisture content of the viewing side polarizing plate is preferably larger than the moisture content of the back side polarizing plate, and may be 0.2% or more.

Moisture content = 100 x [(weight before drying)-(weight after drying)] / weight before drying

  The sum of the thickness of the visible side polarizing plate and the thickness of the back side polarizing plate is preferably 200 μm or less, more preferably 170 μm or less. Although the lower limit is not limited, it is usually 100 μm or more. By setting it as the said range, control of the moisture in and out of a polarizing plate is easy.

  Each member which comprises the set of the polarizing plate of this invention is demonstrated. Hereinafter, the first polarizer and the second polarizer may be collectively referred to as a polarizer, and the first protective film, the second protective film, and the third protective film are collectively referred to as a protective film. Sometimes, the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, and the third pressure-sensitive adhesive layer are collectively referred to as an adhesive layer, and the separator and the protective film are collectively referred to as a surface protective film. There is.

(Polarizer)
The polarizer used in the present invention is usually a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing a polyvinyl alcohol resin film with a dichroic dye, a dichroic dye Is manufactured through a process of treating the adsorbed polyvinyl alcohol resin film with an aqueous solution of boric acid and a process of washing with water after the treatment with an aqueous solution of boric acid.

  As polyvinyl alcohol-type resin, what saponified polyvinyl acetate type resin can be used. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and, for example, polyvinyl formal modified with aldehydes, polyvinyl acetal or the like can also be used. The polymerization degree of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

What formed the polyvinyl alcohol-type resin into a film is used as a raw film of a polarizer. The polyvinyl alcohol-based resin can be formed into a film by a known method. The film thickness of the polyvinyl alcohol-based raw film is preferably about 5 to 35 μm, more preferably 5 to 20 μm, in consideration of setting the thickness of the obtained polarizer to 15 μm or less. When the film thickness of the raw film is 35 μm or more, it is necessary to increase the draw ratio at the time of producing the polarizer, and the dimensional shrinkage of the obtained polarizer tends to be large.
On the other hand, when the film thickness of the raw film is 5 μm or less, the handling property at the time of stretching is lowered, and defects such as cutting tend to occur easily during the production.

  The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after the dyeing of the dichroic dye. If uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, uniaxial stretching may be performed between rolls having different peripheral speeds, or uniaxial stretching may be performed using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the atmosphere, or may be wet stretching in which a polyvinyl alcohol resin film is swollen using a solvent and in a swollen state. The stretching ratio is usually about 3 to 8 times.

  As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. The polyvinyl alcohol-based resin film is preferably subjected to immersion treatment in water prior to the dyeing treatment.

When using iodine as a dichroic dye, the method of immersing and dye | staining a polyvinyl-alcohol-type resin film the aqueous solution containing an iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. In addition, the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C.
Moreover, the immersion time (staining time) to this aqueous solution is usually about 20 to about 1,800 seconds.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dye | staining a polyvinyl alcohol-type resin film the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably about 1 × 10 ⁻³ to 1 part by weight, per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (staining time) to this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid process after dyeing | staining with a dichroic dye can be normally performed by immersing the dyed polyvinyl alcohol-type resin film in boric-acid containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, this boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., and more preferably 60 to 80 ° C.

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

  After washing with water, drying treatment is performed to obtain a polarizer. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

By the drying process, the moisture content of the polarizer is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizer is lost, and the polarizer may be damaged or broken after it is dried.
When the water content exceeds 20% by weight, the heat stability of the polarizer may be poor.

  In addition, stretching, dyeing, boric acid treatment, washing with water, and drying of a polyvinyl alcohol-based resin film in the process of producing a polarizer may be performed, for example, according to the method described in JP-A-2012-159778. . In the method described in this document, a polyvinyl alcohol-based resin layer to be a polarizer is formed by coating a polyvinyl alcohol-based resin on a base film.

  It is also effective to reduce the contraction force of the polarizer itself, and the thickness of the first polarizer is preferably 15 μm or less, more preferably 7 to 15 μm, and further preferably 10 to 13 μm. preferable. Similarly, the thickness of the second polarizer is preferably 15 μm or less, more preferably 4 to 12 μm, and still more preferably 5 to 10 μm.

(Protective film)
The protective film is made of a resin film and can be made of a transparent resin film. In particular, it is preferable to use a material that is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like. In the present specification, a transparent resin film refers to a resin film having a single transmittance of 80% or more in the visible light range.

The resin for forming the protective film is not particularly limited, and, for example, methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile・ Butadiene / Styrene resin, Acrylonitrile / Styrene resin, Polyvinyl acetate resin, Polyvinylidene chloride resin, Polyamide resin, Polyacetal resin, Polycarbonate resin, Modified polyphenylene ether resin, Polybutylene tephthalate resin, Films made of polyethylene tephthalate resin, polysulfone resin, polyether sulfone resin, polyarylate resin, polyamideimide resin, polyimide resin and the like can be mentioned.
These resin films are a film produced by using a raw material resin, a uniaxially stretched film obtained by transverse stretching after film production, a biaxial stretched film obtained by longitudinally stretching after film production, and then transverse stretching, etc. be able to.

  These resins can be used alone or in combination of two or more. In addition, these resins may be used after any suitable polymer modification, and examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. And denaturing such as mixing including the case of

  Among these, as a material of a protective film, it is preferable to use methyl methacrylate resin, polyethylene terephthalate resin, polyolefin resin, or cellulose resin. The polyolefin resin mentioned here includes a chain-like polyolefin resin and a cyclic polyolefin resin.

  The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having 100% by weight of methyl methacrylate units is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

  The methyl methacrylate resin can be generally obtained by polymerizing a monofunctional monomer containing methyl methacrylate as a main component in the presence of a radical polymerization initiator. In the polymerization, if necessary, a polyfunctional monomer or a chain transfer agent may be coexistent.

  The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate and methacrylic acid 2. -Ethylhexyl and methacrylates other than methyl methacrylate such as 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-acrylate Ethylhexyl and acrylic esters such as 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, And hydroxyalkyl acrylic esters such as butyl 2- (hydroxymethyl) acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; vinyl toluene and α-methylstyrene Unsaturated styrenes such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenyl maleimide and cyclohexyl maleimide it can. Such monomers may be used alone or in combination of two or more.

  The polyfunctional monomer copolymerizable with methyl methacrylate is not particularly limited. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate Esterified with acrylic acid or methacrylic acid at both terminal hydroxyl groups of ethylene glycol or its oligomers such as tetraethylene glycol di (meth) acrylate, nona ethylene glycol di (meth) acrylate, and tetradecaethylene glycol di (meth) acrylate Those obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate Acrylic acid or methacrylic acid obtained by esterifying hydroxyl group of dihydric alcohol such as silylate and butanediol di (meth) acrylate; bisphenol A, alkylene oxide adduct of bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products Esterified with acrylic acid or methacrylic acid; those obtained by esterifying polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and glycidyl acrylate or glycidyl methacrylate at the terminal hydroxyl group of these polyhydric alcohols Those obtained by ring-opening addition of an epoxy group; dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, and halogen-substituted products thereof, and alkylene oxide adducts thereof, etc. Those with an epoxy group of glycidyl acrylate or glycidyl methacrylate by ring-opening addition; allyl (meth) acrylate; and aromatic divinyl compounds such as divinylbenzene and the like. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

  As the methyl methacrylate resin, a resin obtained by reaction between functional groups copolymerized with the resin is also used. As the reaction, for example, intramolecular demethanol condensation reaction of methyl ester group of methyl acrylate and hydroxyl group of methyl 2- (hydroxymethyl) acrylate or carboxyl group of acrylic acid and 2- (hydroxymethyl) acrylic The intramolecular dehydration condensation reaction of the hydroxyl group of methyl acid and the like can be mentioned.

  The polyethylene terephthalate resin means a resin in which 80 mol% or more of the repeating unit is composed of ethylene terephthalate, and may contain other dicarboxylic acid component and diol component. Other dicarboxylic acid components include, but are not limited to, for example, isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid Sebacic acid, 1,4-dicarboxycyclohexane and the like.

  Other diol components include, but are not limited to, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol Etc.

  These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. Also, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid can be used in combination. In addition, as another copolymerization component, a dicarboxylic acid component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond or the like, or a diol component may be used.

  Methods of producing polyethylene terephthalate resins include direct polycondensation of terephthalic acid and ethylene glycol (and optionally other dicarboxylic acids or other diols), dialkyl esters of terephthalic acid and ethylene glycol (and optionally, Transesterification with other dicarboxylic acid dialkyl esters or other diols followed by polycondensation, and ethylene glycol esters of terephthalic acid (and optionally other dicarboxylic acids) (and optionally) A method of polycondensing other diol ester in the presence of a catalyst is employed. Furthermore, if necessary, solid phase polymerization can be performed to improve the molecular weight or reduce low molecular weight components.

  Cyclic polyolefin resins are obtained, for example, by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst. It is preferable to use such a cyclic polyolefin resin because a protective film having a predetermined retardation value, which will be described later, can be easily obtained.

  As cyclic polyolefin resin, for example, ring-opening metathesis polymerization is carried out using norbornene or its derivative obtained by Diels-Alder reaction from cyclopentadiene and olefins or (meth) acrylic acid or its esters as a monomer, and subsequently Resin obtained by hydrogenation; ring-opening metathesis polymerization is carried out using tetracyclododecene or its derivative obtained by Diels-Alder reaction from dicyclopentadiene and olefins or (meth) acrylic acid or esters thereof as a monomer, Resin obtained by subsequent hydrogenation; ring-opening metathesis copolymerization of at least two monomers selected from norbornene, tetracyclododecene, derivatives thereof and other cyclic olefin monomers are similarly carried out, Resins obtained by hydrogenolysis; resins obtained by addition copolymerization of cyclic olefins and / or aromatic compounds having a vinyl group to cyclic olefins such as norbornene, tetracyclododecene, or derivatives thereof It can be mentioned.

  Typical examples of chain-like polyolefin resins are polyethylene resins and polypropylene resins. Among them, homopolymers of propylene or copolymers composed mainly of propylene and copolymerizable comonomers such as ethylene at a ratio of 1 to 20% by weight, preferably 3 to 10% by weight are preferred. It is preferably used.

  The polypropylene resin may contain an alicyclic saturated hydrocarbon resin. By containing the alicyclic saturated hydrocarbon resin, the retardation value can be easily controlled. The content of the alicyclic saturated hydrocarbon resin is advantageously 0.1 to 30% by weight with respect to the polypropylene-based resin, and a more preferable content is 3 to 20% by weight. If the content of the alicyclic saturated hydrocarbon resin is less than 0.1% by weight, the effect of controlling the retardation value is not sufficiently obtained, while if the content exceeds 30% by weight, the second There is a concern that bleeding out of the alicyclic saturated hydrocarbon resin may occur over time from the protective film of

  Cellulose-based resin means that part or all of hydrogen atoms in hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linta and wood pulp (hardwood pulp, softwood pulp) are substituted with acetyl group, propionyl group and / or butyryl group Or cellulose organic acid ester or cellulose mixed organic acid ester. For example, those composed of cellulose acetate, propionate, butyrate, mixed esters thereof and the like can be mentioned. Among them, triacetyl cellulose film, diacetyl cellulose film, cellulose acetate propionate film, and cellulose acetate butyrate film are preferable.

As a method of using methyl methacrylate resin, polyethylene terephthalate resin, polyolefin resin, and cellulose resin as the second protective film for adhering to the polarizer, a method corresponding to each resin may be appropriately selected. Well, it is not particularly limited.
For example, a resin dissolved in a solvent is cast on a metal band or drum, the solvent is removed by drying to obtain a film, and the resin is heated and kneaded above its melting temperature and extruded from a die. A melt extrusion method is employed to obtain a film by cooling. In this melt extrusion method, extrusion of a single layer film may be used, or coextrusion of a multilayer film may be used.

  It is possible to easily obtain commercially available films used as protective films, and in the case of methyl methacrylate resin films, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrilite (registered trademark), and the like under the respective trade names. Acryprene (registered trademark) (Mitsubishi Rayon Co., Ltd.), Deraglas (registered trademark) (Made by Asahi Kasei Co., Ltd.), Paragrass (registered trademark), COMO GLASS (registered trademark) (Mass, manufactured by Kuraray Co., Ltd.) (Registered trademark) (manufactured by Nippon Shokubai Co., Ltd.) and the like. In the case of polyolefin resin films, Zeonor (registered trademark) (Nippon Zeon Co., Ltd.), Arton (registered trademark) (JSR Corporation), etc. may be mentioned under the trade names. If it is a polyethylene terephthalate resin film, respectively, it is a brand name and Nova Clear (trademark) (made by Mitsubishi Chemical Corporation), Teijin A-PET sheet (made by Teijin Chemicals Co., Ltd.), etc. are mentioned. For polypropylene-based resin films, FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Sun Tox Co., Ltd.), Tosero (registered trademark) (manufactured by Tosoh Corp.), Toyobo Pyrene Film (Registered trademark) (made by Toyobo Co., Ltd.), Trefan (registered trademark) (made by Toray Film Processing Co., Ltd.), Nihon Polyace (made by Japan Polyace Co., Ltd.), and Taikei (registered trademark) FC (Futamura Chemical Co., Ltd.) And the like. In addition, as for the cellulose resin film, Fuji Tack (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.), etc. may be mentioned under the trade names.

  The protective film and the protective film used in the present invention can be provided with antiglare property (haze). The method for imparting the antiglare property is not particularly limited. For example, the method of mixing inorganic fine particles or organic fine particles into the above-mentioned raw material resin to form a film, the above-mentioned multilayer extrusion, A method of forming a two-layer film from a resin in which particles are mixed and a resin in which no particles are mixed on the other side, or a method of forming a three-layer film by turning the resin in which particles are mixed on the outside A method of coating an application liquid formed by mixing fine particles or organic fine particles with a curable binder resin and curing the binder resin to provide an antiglare layer is adopted.

  Moreover, a protective film can also contain an additive as needed. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistant agent, an impact modifier and the like.

  The thickness of the protective film is usually about 1 to 50 μm, preferably 10 to 40 μm, in view of strength and handleability.

  The protective film is preferably subjected to a saponification treatment, a corona treatment, a plasma treatment or the like prior to the bonding with the polarizer.

  The first protective film can further be provided with functional layers such as a conductive layer, a hard coat layer, and a low reflective layer. Moreover, the resin composition which has these functions can also be selected as binder resin which comprises the said glare-proof layer.

(Brightness improvement film)
In the back side polarizing plate, the brightness enhancement film is disposed on the side far from the liquid crystal cell in the second polarizer. The thickness of the brightness enhancement film is preferably 35 μm or less, more preferably 30 μm or less.

  As the brightness enhancement film, a polarization conversion element having a function of separating outgoing light from a light source (backlight) into transmission polarization and reflection polarization or scattering polarization is used. Such a brightness enhancement film can improve the output efficiency of linearly polarized light by utilizing the retroreflected light from the back light of the reflected polarized light or the scattered polarized light.

  As a brightness improving film, an anisotropic reflective polarizer is mentioned, for example. As an anisotropic reflective polarizer, there is an anisotropic multiplex thin film which transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. As an anisotropic multiplex thin film, the brand name "APF" and "DBEF" made from 3M company are mentioned, for example. Further, as an anisotropic reflective polarizer, a composite of a cholesteric liquid crystal layer and a λ / 4 plate can be mentioned. As such a complex, there is a trade name "PCF" manufactured by Nitto Denko Corporation. Anisotropic reflective polarizers include reflective grid polarizers. Examples of the reflective grid polarizer include metal grating reflective polarizers in which metal is finely processed to emit reflected polarized light even in a visible light region. Above all, a brightness improving film made of an anisotropic multiple thin film is preferable.

  You may form a functional layer in the surface on the opposite side to the bonding surface with the polarizing plate of a brightness enhancement film. Examples of the functional layer include a hard coat layer, an antiglare layer, a light diffusion layer, and a retardation layer having a retardation value of 1⁄4 wavelength, thereby improving adhesion to a backlight tape. And uniformity of the displayed image can be improved.

(Surface protection film)
The separator is a film that is temporarily attached to protect the surface until the viewing side polarizing plate and the back side polarizing plate are bonded to the liquid crystal cell. The separator is usually made of a thermoplastic resin film which has been subjected to a release treatment on one side, and the release treated surface is bonded to the first pressure-sensitive adhesive layer or the second pressure-sensitive adhesive layer. The thermoplastic resin constituting the separator can be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate. When the third pressure-sensitive adhesive layer provided in advance on the brightness enhancement film is provided, the surface is temporarily protected until the second polarizer is attached also to the surface of the third pressure-sensitive adhesive layer. For this purpose, the same separator as above can be stuck. The thickness of the separator is, for example, 10 to 50 μm.

  The protective film is composed of a resin film and an adhesive layer laminated thereon. The protect film is a film for protecting the surface of the viewing side polarizing plate and the back side polarizing plate, and can be temporarily attached on, for example, the first protective film or the brightness enhancement film. Usually, for example, after a polarizing plate with a protective film is bonded to a liquid crystal cell, the pressure-sensitive adhesive layer of the protective film is peeled off and removed. Therefore, the pressure-sensitive adhesive layer of the protect film is not included in the thickness of the polarizing plate in this specification.

  The resin constituting the resin film is, 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 Can. Preferably, polyester resins such as polyethylene terephthalate are used. The resin film may have a single-layer structure or a multi-layer structure, but preferably has a single-layer structure from the viewpoint of easiness of production and cost. The description about the 1st adhesive layer later mentioned and a 2nd adhesive layer is quoted about the adhesive layer which a protect film has.

(First pressure-sensitive adhesive layer, second pressure-sensitive adhesive layer)
An adhesive layer can be laminated on the surface of the polarizing plate. A polarizing plate can be bonded to the liquid crystal cell through the pressure-sensitive adhesive layer. In FIG. 1, the first pressure-sensitive adhesive layer 40 and the second pressure-sensitive adhesive layer 41 correspond to this. It is preferable that the thickness of the adhesive layer formed from an adhesive shall be 5-25 micrometers. More preferably, it is 10-25 micrometers.

  Examples of the pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer include acrylic polymers, silicone-based polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins Those having an epoxy-based, fluorine-based, natural rubber, rubber-based polymer such as synthetic rubber as a base polymer can be appropriately selected and used. As the pressure-sensitive adhesive, those which are particularly excellent in optical transparency, exhibit appropriate adhesion properties such as wettability, cohesion and adhesiveness, and are excellent in weather resistance, heat resistance and the like are preferable.

  In addition to this, various additives may be blended in the adhesive. The additives include silane coupling agents and antistatic agents.

  The storage elastic modulus of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 0.01 to 0.1 MPa at 23 to 80 ° C., and more preferably 0.02 to 0.06 MPa preferable. The phrase "showing a storage elastic modulus of 0.01 to 0.1 MPa at 23 to 80C" means that the storage elastic modulus takes a value in the above range at any temperature in this range. Since the storage elastic modulus usually decreases gradually with the temperature rise, if the storage elastic modulus at 23 ° C. and 80 ° C. falls within the above range, the pressure sensitive adhesive layer has a storage elastic modulus within the above range at this temperature. It can be seen to indicate the rate. The storage elastic modulus of the pressure-sensitive adhesive layer can be measured by a commercially available visco-elasticity measuring device, for example, a visco-elasticity measuring device “DYNAMIC ANALYZER RDA II” manufactured by REOMETRIC.

(Method of manufacturing polarizing plate)
The manufacturing method of the visual recognition side polarizing plate which comprises the polarizing plate of this invention, and a back side polarizing plate is demonstrated. The members described above can be bonded to each other, for example, by laminating them via an adhesive layer or a pressure-sensitive adhesive layer.

(Lamination of polarizer and protective film)
It is preferable to perform lamination | stacking with a protective film and a polarizer, for example by the method integrated using an adhesive agent. 0.01-35 micrometers is preferable, as for the thickness of the contact bonding layer formed from an adhesive agent, 0.01-10 micrometers is more preferable, More preferably, it is 0.01-5 micrometers. Within this range, no floating or peeling occurs between the protective film and the polarizer, and adhesion with no practical problem can be obtained.

  As the adhesive, for example, a solvent type adhesive, an emulsion type adhesive, a pressure sensitive adhesive, a remoistenable adhesive, a polycondensation type adhesive, a non-solvent type adhesive, a film adhesive, and a hot melt type adhesive Etc. Moreover, an adhesive layer can also be provided through an anchor coat layer as needed.

  Preferred adhesives include water soluble adhesives. The water-soluble adhesive includes, for example, one having a polyvinyl alcohol-based resin as a main component. The water-soluble adhesive may be a commercially available one, or a mixture of a commercially available adhesive and a solvent or an additive may be used. Examples of commercially available polyvinyl alcohol resins that can be used as water-soluble adhesives include KL-318 manufactured by Kuraray Co., Ltd.

  The water soluble adhesive can contain a crosslinker. As a kind of crosslinking agent, an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt and the like are preferable, and an epoxy compound is particularly preferable. As a commercial item of the crosslinking agent, for example, there are Glyoxal, and Violetase resin 650 (30) manufactured by Taoka Chemical Industry Co., Ltd., and the like.

  Moreover, another preferable adhesive includes an active energy ray-curable adhesive composed of a resin composition which is cured by irradiation of active energy rays. Examples of the active energy ray-curable adhesive layer include those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, those containing a binder resin and a photoreactive crosslinking agent, and the like. Examples of the polymerizable compound include photocurable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from the photopolymerizable monomers. Examples of the photopolymerization initiator include those containing a substance that generates active species such as radicals, cations or anions upon irradiation of active energy rays such as ultraviolet rays. As an active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, one containing a photocurable epoxy-based monomer and a photocationic polymerization initiator can be preferably used.

  When using an active energy ray curable adhesive, after bonding a polarizer and a protective film, a drying process is carried out as necessary, and then an active energy ray curable adhesive is obtained by irradiating an active energy ray. A curing step to cure is performed. The light source of the active energy ray is not particularly limited, but ultraviolet light having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, chemical lamp, black light lamp, micro A wave excitation mercury lamp, a metal halide lamp, etc. can be used.

  The adhesive may contain an additive. As an additive, an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow control agent, a plasticizer, an antifoamer etc. are mentioned.

(Lamination of a polarizer and a brightness enhancement film)

  It is preferable to use an adhesive layer for bonding of a polarizer and a brightness enhancement film. In FIG. 1, the third pressure-sensitive adhesive layer corresponds to this. It is preferable that the thickness of the adhesive layer formed from an adhesive be 3-20 micrometers. More preferably, it is 3 to 10 μm.

  Examples of the pressure-sensitive adhesive layer for laminating the polarizer and the brightness enhancement film include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy resins, fluorine What makes polymers, such as a rubber system of a system, natural rubber, and a synthetic rubber, etc. a base polymer can be selected suitably, and can be used. As the pressure-sensitive adhesive, those which are particularly excellent in optical transparency, exhibit appropriate adhesion properties such as wettability, cohesion and adhesiveness, and are excellent in weather resistance, heat resistance and the like are preferable.

  In addition to this, various additives may be blended in the adhesive. The additives include silane coupling agents and antistatic agents.

  The storage elastic modulus of the third pressure-sensitive adhesive layer is preferably 0.10 to 1.0 MPa at 23 to 80 ° C., and more preferably 0.15 to 0.8 MPa. When the storage elastic modulus at 23 to 80 ° C. is 0.10 to 1.0 MPa, the shrinkage force of the polarizer in a moist heat environment can be relaxed, and the warpage of the liquid crystal panel can be more effectively reduced. As a method of setting the storage elastic modulus of the third pressure-sensitive adhesive layer to 0.10 to 1.0 MPa, it is effective to blend a urethane acrylate-based oligomer into a normal pressure-sensitive adhesive composition. Preferably, such a urethane acrylate oligomer is blended and then cured by irradiation with an energy ray to exhibit high storage elastic modulus.

  The shape of the polarizing plate of the present invention is not particularly limited, but may be rectangular. When a polarizing plate is manufactured by a roll-to-roll method, it can be cut into a predetermined shape. The polarizing plate of the present invention may have a rectangular shape with a diagonal of 15 inches or less, may have a rectangular shape with a diagonal of 3 inches or more, or may have a rectangular shape with a diagonal of 7 inches or more.

(Method of manufacturing liquid crystal panel)
A liquid crystal panel can be obtained by bonding the set of polarizing plates of the present invention to both sides of a liquid crystal cell. The bonding is preferably performed via the first pressure-sensitive adhesive layer of the viewer-side polarizing plate and the second pressure-sensitive adhesive layer of the back-side polarizing plate. The liquid crystal panel of the present invention can be suitably applied to a liquid crystal display device. The viewing side polarizing plate is preferably bonded so that the absorption axis thereof is substantially parallel to the short side direction of the liquid crystal cell, and the back side polarizing plate is such that the absorption axis thereof is substantially parallel to the long side direction of the liquid crystal cell It is preferable to bond so that In the present specification, “substantially parallel” means, for example, that the angle formed is 0 ± 5 °, preferably 0 ± 1 °.

  The liquid crystal panel can be manufactured, for example, under an environment with a temperature of 18 to 28 ° C. and a relative humidity of 40 to 70%, since the movement of moisture into and out of the viewing side polarizing plate and the back side polarizing plate can be controlled and the effects of the present invention can be enhanced. Is preferred.

  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 in many cases, but may be a plastic substrate. In addition, the liquid crystal cell itself used for the liquid crystal panel of the present invention can be configured by various types adopted in this field. According to the set of polarizing plates of the present invention, warpage can be significantly reduced even if the thickness of the liquid crystal cell is 0.4 mm or less. In the present invention, the thickness of the liquid crystal cell includes the thickness of the liquid crystal layer and the pair of substrates sandwiching the liquid crystal layer.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not defined by these examples. In the examples,% and parts representing contents or amounts used are by weight unless otherwise specified. In addition, the evaluation method used in the Example is as follows.

(1) Thickness:
The measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) In-plane retardation Re and thickness direction retardation Rth:
It measured by the light of wavelength 590nm in 23 degreeC using the phase difference meter and KOBRA-WPR by Oji Scientific Instruments Co., Ltd. which make a principle a parallel Nicol rotation method.
(3) Storage modulus:
The storage elastic modulus (G ') of the pressure-sensitive adhesive is a cylindrical test piece having a diameter of 8 mm and a thickness of 1 mm made of the pressure-sensitive adhesive to be measured, and a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC CORPORATION) ) At a temperature of 23 ° C. or a temperature of 80 ° C., using an initial strain of 1 N according to a torsional shear method with a frequency of 1 Hz.

Each member was prepared as follows.
(Polarizer A)
A 30 μm thick polyvinyl alcohol film (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more) is uniaxially stretched about 5 times by dry stretching, and further kept in a tensed state to obtain pure water at 60 ° C. After immersion for 1 minute, it was immersed for 60 seconds at 28 ° C. in an aqueous solution of iodine / potassium iodide / water at a weight ratio of 0.05 / 5/100. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was 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 is adsorbed and oriented to a polyvinyl alcohol film.

(Polarizer B)
A 20 μm thick polyvinyl alcohol film (average polymerization degree about 2,400, saponification degree 99.9 mol% or more) is uniaxially stretched about 5 times by dry stretching, and further kept at a tension of 60 ° C. After soaking in pure water for 1 minute, it was immersed in an aqueous solution of iodine / potassium iodide / water at a weight ratio of 0.05 / 5/100 at 28 ° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds, and then dried at 65 ° C. to obtain a 7 μm-thick polarizer in which iodine is adsorbed and oriented to a polyvinyl alcohol film.

(Polarizer C)
A 20 μm thick polyvinyl alcohol film (average degree of polymerization: about 2,400, degree of saponification: 99.9 mol% or more) is uniaxially stretched by dry stretching to about 4.9 times and further kept in tension, 60 After immersing in pure water of 1 ° C. for 1 minute, it was immersed in an aqueous solution of iodine / potassium iodide / water at a weight ratio of 0.05 / 5/100 at 28 ° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a polarizer with a thickness of 8 μm in which iodine is adsorbed and oriented to a polyvinyl alcohol film.

(Pressure-sensitive adhesive layer A)
A commercially available pressure-sensitive adhesive sheet was used in which an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm was laminated on a release-treated surface of a polyethylene terephthalate film (separator) having a thickness of 38 μm subjected to a release treatment. No urethane acrylate oligomer is blended in the acrylic pressure-sensitive adhesive.
The storage elastic modulus of the pressure-sensitive adhesive layer obtained by removing the release film from the pressure-sensitive adhesive sheet was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C.

(Pressure-sensitive adhesive layer B)
A commercially available pressure-sensitive adhesive sheet was used in which an acrylic pressure-sensitive adhesive layer having a thickness of 15 μm was laminated on the release-treated surface of a polyethylene terephthalate film (separator) having a thickness of 38 μm subjected to a release treatment. No urethane acrylate oligomer is blended in the acrylic pressure-sensitive adhesive.
The storage elastic modulus of the pressure-sensitive adhesive layer obtained by removing the release film from the pressure-sensitive adhesive sheet was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C.

(Pressure-sensitive adhesive layer C)
An organic solvent solution in which a urethane acrylate oligomer and an isocyanate-based crosslinking agent are added to a copolymer of butyl acrylate and acrylic acid is treated with a 38 μm-thick polyethylene terephthalate film (separator) which has been subjected to a release treatment. The resultant was coated by a die coater to a dry thickness of 5 μm and dried to obtain a pressure-sensitive adhesive sheet on which a pressure-sensitive adhesive layer was laminated. The storage elastic modulus of the pressure-sensitive adhesive layer obtained by removing the release film from the pressure-sensitive adhesive sheet was 0.40 MPa at 23 ° C. and 0.18 MPa at 80 ° C.

(Protective film)
The following protective films were prepared.
Protective film A: Triacetylcellulose film (manufactured by Konica Minolta Co., Ltd.) having a thickness of 20 μm. In-plane retardation value at a wavelength of 590 nm = 1.2 nm, thickness direction retardation value at a wavelength of 590 nm = 1.3 nm)
Protective film B: Cycloolefin resin film (made by Nippon Zeon Co., Ltd.) having a thickness of 13 μm. In-plane retardation value at wavelength 590 nm = 0.8 nm, thickness direction retardation value at wavelength 590 nm = 3.4 nm, thickness direction retardation value at wavelength 483 nm = 3.5 nm, thickness direction retardation at wavelength 755 nm Value = 2.8 nm.
Protective film C: Cycloolefin resin film (made by Nippon Zeon Co., Ltd.) with a thickness of 23 μm.
Protective film D: A triacetyl cellulose film (Toppan Corporation TOHOEGAWA Optical Film, 25KCHC-TC) to which a surface with a thickness of 32 μm is hard-coated. The moisture permeability was 400 g / (m ² · 24 hr).

(Brightness improvement film)
A brightness enhancement film (manufactured by 3M, trade name ADvance D Polarize D Film, Version 3) having a thickness of 26 μm was used.

(Water-based adhesive)
In 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) is dissolved, and in the aqueous solution, a polyamide epoxy based additive (Suzumi Chemtex Co., Ltd.) which is a water-soluble epoxy compound And SMILEASE RESIN (registered trademark) 650 (30), an aqueous solution with a solid content concentration of 30%] was added to make a water-based adhesive.

(Production Example 1: Viewing Side Polarizer A)
The protective film B was bonded on one side of the polarizer A via a water-based adhesive. The protective film D was bonded to the other surface of the polarizer A via a water-based adhesive. The adhesive layer A laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the polarizer A in the said protective film B was bonded. The thickness of the viewing side polarizing plate A was 77 μm.

(Production Example 2: Viewing Side Polarizing Plate B)
The protective film C was bonded on one side of the polarizer A via a water-based adhesive. The protective film D was bonded to the other surface of the polarizer A via a water-based adhesive. The adhesive layer A laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the polarizer A in the said protective film C was bonded. The thickness of the viewing side polarizing plate B was 87 μm.

(Production Example 3: Viewing Side Polarizing Plate C)
The protective film A was bonded to one side of the polarizer B via a water-based adhesive. The protective film D was bonded to the other surface of the polarizer B via a water-based adhesive. The adhesive layer A laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the polarizer B in the said protective film A was bonded. The thickness of the viewing side polarizing plate C was 79 μm.

(Manufacturing example 4: back side polarizing plate A)
The protective film B was bonded on one side of the polarizer B via a water-based adhesive. The adhesive layer C laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the protective film B in the said polarizer B was bonded. The adhesive layer B laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the polarizer B in the said protective film B was bonded. The release film on the pressure-sensitive adhesive layer C was peeled off, and a brightness enhancement film was bonded thereto. The thickness of the back side polarizing plate A was 66 μm.

(Production example 5: back side polarizing plate B)
The protective film A was bonded to one side of the polarizer B via a water-based adhesive. The adhesive layer C laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the protective film A in the said polarizer B was bonded. The adhesive layer A laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the polarizer B in the said protective film A was bonded. The release film on the pressure-sensitive adhesive layer C was peeled off, and a brightness enhancement film was bonded thereto. The thickness of the back side polarizing plate A was 78 μm.

(Manufacturing example 6: back side polarizing plate C)
The protective film A was bonded to one side of the polarizer B via a water-based adhesive. The adhesive layer C laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the protective film A in the said polarizer B was bonded. The adhesive layer B laminated | stacked on the peeling film on the surface on the opposite side to the bonding surface with the polarizer B in the said protective film A was bonded. The release film on the pressure-sensitive adhesive layer C was peeled off, and a brightness enhancement film was bonded thereto. The thickness of the back side polarizing plate A was 73 μm.

(Production Example 7: Viewing Side Polarizing Plate D)
A viewing side polarizing plate D was produced in the same manner as in Production Example 1 except that a polarizer C was used instead of the polarizer A. The thickness of the viewing side polarizing plate D was 73 μm.

(Production Example 8: Viewing Side Polarizing Plate E)
A viewing side polarizing plate E was produced in the same manner as in Production Example 2 except that a polarizer C was used instead of the polarizer A. The thickness of the viewing side polarizing plate E was 83 μm.

(Production example 9: back side polarizing plate D)
A back side polarizing plate D was produced in the same manner as in Production Example 4 except that a polarizer C was used instead of the polarizer B. The thickness of the back side polarizing plate D was 67 μm.

(Production example 10: back side polarizing plate E)
A back side polarizing plate E was produced in the same manner as in Production Example 5 except that a polarizer C was used instead of the polarizer B. The thickness of the back side polarizing plate E was 79 μm.

(Production Example 11: Back side polarizing plate F)
A back side polarizing plate F was produced in the same manner as in Production Example 6 except that a polarizer C was used instead of the polarizer B. The thickness of the back side polarizing plate F was 74 micrometers.

Example 1
The viewing side polarizing plate A and the back side polarizing plate A were cut into a rectangular shape with a long side direction of 155.25 mm and a short side direction of 95.9 mm. In addition, about the visual recognition side polarizing plate, it cut | judged so that the absorption axis might become parallel to short side direction, and it cut | judged about the back side polarizing plate so that the absorption axis might become parallel to long side direction.

(Warpage of panel under normal temperature environment)
The release film on the pressure-sensitive adhesive layer A is peeled off from the cut-off viewing side polarizing plate A, and a 0.2 mm-thick non-alkali glass (corresponding to a liquid crystal cell substrate, long side direction 160 mm, short) through the pressure-sensitive adhesive layer A It is pasted together to one field of a side direction 102 mm.). The release film on the pressure-sensitive adhesive layer B was peeled off from the back side polarizing plate A that had been cut, and pasted onto the other surface of the non-alkali glass via the pressure-sensitive adhesive layer B. Thus, a laminate comprising the viewing side polarizing plate A / the glass plate / the back side polarizing plate A was obtained. Thereafter, the laminate was autoclaved. The absorption axes of the polarizing plates were orthogonal to each other. In each of the examples, the moisture content of the viewing side polarizing plate was 1.13%, the moisture content of the back side polarizing plate was 0.6%, and the difference between them was 0.53%.

The above laminate was allowed to stand in an environment of temperature 23 ° C. and humidity 55% RH for 24 hours. After that, the laminate was placed on the measurement table of a two-dimensional measuring device (manufactured by Nikon Corporation, NEXIV (registered trademark) VMZ-R4540) so that the viewing side polarizing plate A was on the upper side.
Then, the surface of the measurement table was focused, the point was used as a reference, the 25 points on the surface of the laminate were respectively focused, and the height from the reference focus was measured. The difference between the maximum value and the minimum value of the heights at the 25 measurement points was taken as the amount of warpage. The results are shown in Table 1 below. FIG. 5 is a schematic view showing measurement points of the amount of warpage. 70 is a "measurement point", 71 is a polarizing plate, 72 is a glass plate. The 25 "measurement points" are points in an area about 7 mm inward from the end of the polarizing plate, and the short side direction is about 20 mm apart, and the long side direction is about 35 mm apart.

(Warpage of panel under high temperature environment)
In preparing the above laminate, a laminate comprising the viewing side polarizing plate A / the glass plate / the back side polarizing plate A was obtained in the same manner except that alkali-free glass having a thickness of 0.4 mm was used. In each of the examples, the moisture content of the viewing side polarizing plate was 1.13%, the moisture content of the back side polarizing plate was 0.6%, and the difference between them was 0.53%.

The above laminate was allowed to stand in an environment of a temperature of 85 ° C. and a humidity of 5% RH for 250 hours. After that, the laminate was placed on the measurement table of a two-dimensional measuring device (manufactured by Nikon Corporation, NEXIV (registered trademark) VMZ-R4540) so that the viewing side polarizing plate A was on the upper side.
Then, in the same manner as in the measurement of the warp of the panel under the normal temperature environment, focus on the surface of the measurement table, reference it there, focus on 25 points on the surface of the laminate respectively, and focus on the reference The height of the The difference between the maximum value and the minimum value of the heights at the 25 measurement points was taken as the amount of warpage. The results are shown in Table 1 below.

(Examples 2-4, comparative examples 1-2)
As shown in Table 1 below, combinations of the viewing side polarizing plate and the back side polarizing plate were measured for warping of the panel under normal temperature environment of each laminate and warping of the panel under high temperature environment. The results are summarized in Table 1 below. In Examples 1 to 4, the size of the warp of the liquid crystal panel was 0.4 mm or less both in the normal temperature environment and in the high temperature environment. In Comparative Examples 1 to 3, the magnitude of the warpage of the liquid crystal panel exceeded 0.4 mm under either a normal temperature environment or a high temperature environment.

(Examples 5 to 13)
As shown in Table 2 below, the combination of the viewing side polarizing plate and the back side polarizing plate is measured under the normal temperature environment when the warp of the panel under the normal temperature environment of each laminate and the warp of the panel under the high temperature environment are measured. Also in the high temperature environment, the size of the warp of the liquid crystal panel is 0.4 mm or less.

[Table 2]
--------------------------------
Viewing Side Polarizing Plate Back Side Polarizing Plate Viewing Side Polarizing Plate Back Side Polarizer
偏光 Polarizer Polarizer Thickness difference
No. Thickness No. Thickness Thickness thickness thickness difference
[μm] [μm] [μm] [μm] [μm] [μm]
--------------------------------
Example 5 A 77 D 67 10 12 8 4
Example 6 D 43 A 66 7 8 7 1
Example 7 B 87 E 79 8 12 8 4
Example 8 E 83 B 78 5 8 7 1
Example 9 A 77 F 74 3 12 8 4
Example 10 D 73 C 73 0 8 7 1
Example 11 A 77 E 79 -2 12 8 4
Example 12 D 73 B 78 -5 8 7 1
--------------------------------

  According to the set of the polarizing plate of the present invention, it is possible to reduce the warpage of the liquid crystal panel under the normal temperature environment while reducing the warpage of the liquid crystal panel under the high temperature environment.

DESCRIPTION OF SYMBOLS 1 visual recognition side polarizing plate 2 back side polarizing plate 10 1st polarizer 11 2nd polarizer 20 1st protective film 21 2nd protective film 22 3rd protective film 30 brightness improving film 40 1st adhesive Layer 41 Second pressure-sensitive adhesive layer 42 Third pressure-sensitive adhesive layer 50, 51 Separator 60, 60 Protect film 70 Measurement location 71 Polarizing plate 72 Glass plate 100 Thickness of viewing side polarizing plate 200 Thickness of back side polarizing plate

Claims (4)

A set of polarizing plates comprising a viewing side polarizing plate disposed on the viewing side of the liquid crystal cell and a back side polarizing plate disposed on the back side of the liquid crystal cell,
The viewing side polarizing plate includes a first protective film, a first polarizer, and a second protective film in this order,
The back side polarizing plate includes a third protective film, a second polarizer, and a brightness enhancement film in this order,
The difference obtained by subtracting the thickness of the back side polarizing plate from the thickness of the viewing side polarizing plate is 13 μm or less,
A set of polarizing plates in which a difference obtained by subtracting the thickness of the second polarizer from the thickness of the first polarizer is more than 0 μm and not more than 10 μm. The thickness of the first polarizer is 7 μm or more and 15 μm or less,
The set of the polarizing plate of Claim 1 whose thickness of a said 2nd polarizer is 4 micrometers-12 micrometers. The set of the polarizing plate of Claim 1 or 2 whose thickness of the said visual recognition side polarizing plate and the thickness of the said back side polarizing plate are all 100 micrometers or less. The liquid crystal panel which has a set of the polarizing plate in any one of Claims 1-3.

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