TW201809757A - Set of polarizing plates - Google Patents

Abstract

The present invention not only reduces the bending of a liquid crystal panel in a high temperature environment, so as to facilitate the manufacture of the liquid crystal display device, and at the same time also reduces the bending of the liquid crystal panel in a normal temperature environment, so as to reduce defects in actual use. The set of polarizing plates of the present invention consists of 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, wherein, the viewing side polarizing plate, in the following order, has a first protective film, a first polarizer, and a second protective film; the back side polarizing plate, in the following order, has a third protective film, a second polarizer, and a brightness enhancement film; the difference obtained by subtracting the thickness of the back side polarizing plate from the thickness of the viewing side polarizing plate is 13 [mu]m or less; the difference obtained by subtracting the thickness of the second polarizer from the thickness of the first polarizer exceeds 0 [mu]m and is 5 [mu]m or less.

Description

Polarizer set

The present invention relates to a set of polarizing plates.

The liquid crystal display device is used in various display devices because of its low power consumption, low voltage operation, light weight, and thinness. The liquid crystal panel constituting the liquid crystal display device has a configuration in which a pair of polarizing plates are laminated on both sides of the liquid crystal cell.

In particular, in a liquid crystal panel for portable use, in order to suppress the power consumption while improving the brightness of the screen, the polarizing plate disposed on the back side of the liquid crystal cell may have a brightness enhancement film. The brightness enhancement film is a film that reflects the linearly polarized light of a predetermined polarization axis or the circularly polarized light of a predetermined direction when the backlight of the liquid crystal display device is incident, and allows other light to penetrate.

However, when the back 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, and the backlight unit or the cover is used. There is a problem of missing when the glass is attached to the liquid crystal panel. Recently, the thickness of the glass substrate constituting the liquid crystal cell is gradually thinned, and this problem is further accelerated.

For example, in Patent Document 1, it is disclosed that the polarizing plate disposed on the viewing side and the polarizing plate disposed on the back side are different in thickness of the cellulose triacetate film bonded to each of the polarizing plates, thereby reducing the liquid crystal panel. The method of warping in a normal temperature environment.

However, there is still room for improvement in the reduction of warpage in a normal temperature environment. Further, Patent Document 1 does not disclose warpage in a high-temperature environment that is often noticed in actual use, and the polarizing plate described in Patent Document 1 has a problem that warpage is large in a severe environment.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-207211

The object of the present invention is to reduce the warpage of the liquid crystal panel in a normal temperature environment, to facilitate the manufacture of the liquid crystal display device, and to reduce the warpage of the liquid crystal panel in a high temperature environment, thereby reducing the lack of use in actual use.

[1] A set of polarizing plates comprising a viewing side polarizing plate disposed on a viewing side of a liquid crystal cell, and a back side polarizing plate disposed on a back side of the liquid crystal cell, wherein the viewing side polarizing plate , with the first protective film and the first polarized light in sequence a sheet and a second protective film; the back side polarizing plate is provided with a third protective film, a second polarizer, and a brightness enhancement film in this order; and a difference between a thickness of the front side polarizing plate and a thickness of the back side polarizing plate is 13 μm or less; the difference between the thickness of the first polarizer and the thickness of the second polarizer is more than 0 μm and 10 μm or less.

[2] The kit of polarizing plates according to [1], wherein the thickness of the first polarizer is 7 μm or more and 15 μm or less, and the thickness of the second polarizer is 4 μm or more and 12 μm or less.

[3] The kit of polarizing plates according to [1], wherein the thickness of the viewing-side polarizing plate and the thickness of the back-side polarizing plate are both 100 μm or less.

[4] A liquid crystal panel having the kit of the polarizing plate according to any one of [1] to [3].

According to the set of the polarizing plate of the present invention, not only the warpage of the liquid crystal panel under a normal temperature environment but also the warpage of the liquid crystal panel in a high temperature environment can be reduced.

1‧‧‧ viewing side polarizer

2‧‧‧Back side polarizer

10‧‧‧1st polarizer

11‧‧‧2nd polarizer

20‧‧‧1st protective film

21‧‧‧2nd protective film

22‧‧‧3rd protective film

30‧‧‧Brightness lifting film

40‧‧‧1st adhesive layer

41‧‧‧2nd adhesive layer

42‧‧‧3rd adhesive layer

50, 51‧‧‧ separator

60, 61‧‧‧ protective film

70‧‧‧Measurement

71‧‧‧Polar plate

72‧‧‧ glass plate

100‧‧‧ Viewing side polarizer thickness

200‧‧‧ Thickness of the back side polarizer

Fig. 1 is a cross-sectional view showing an example of a set of polarizing plates of the present invention.

Fig. 2 is a cross-sectional view showing an example of a viewing-side polarizing plate constituting a kit of the polarizing plate of the present invention.

Fig. 3 is a cross-sectional view showing an example of a back side polarizing plate constituting a kit of the polarizing plate of the present invention.

Fig. 4 is a cross-sectional view showing an example of a liquid crystal panel of the present invention.

Fig. 5 is a plan view showing the position at which the amount of warpage of the glass sample is measured.

The set of polarizing plates and the liquid crystal panel of the present invention will be described with reference to the appropriate drawings. The kit 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 member shown in Fig. 1. 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 is provided with the first protective film 20, the first polarizer 10, the second protective film 21, and the first adhesive layer 40 in this order. The back side polarizing plate 2 is provided with a brightness enhancement film 30, a third adhesive layer 42, a second polarizer 11, a third protective film 22, and a second adhesive layer 41 in this order. The first adhesive layer 40 and the second adhesive layer 41 may be a pressure-sensitive adhesive layer for bonding the polarizing plates to the liquid crystal cell, and are finally assembled in the liquid crystal display device. In the present invention, the thickness of the adhesive layer is included in the thickness of the polarizing plate.

Further, as shown in FIG. 2 and FIG. 3, the first adhesive layer 40 and the second adhesive layer 41 are applied until the set of the polarizing plate of the present invention is bonded to the liquid crystal cell. Preferably, the separator 50 and the separator 51 are temporarily attached to the first protective film 20 and the brightness enhancement film. In the case of 30, it is preferable to temporarily attach the protective film 60 and the protective film 61 in advance. Since the separators 50 and 51 and the protective films 60 and 61 are peeled off during the manufacturing process of the liquid crystal display device, they are not assembled to the liquid crystal display device. Therefore, in the present invention, the thickness of the separator and the pellicle are not counted in the thickness of the polarizing plate. Specifically, the thickness of each of the polarizing plates constituting the kit of the polarizing plate of the present invention is, for example, the arrow mark 100 shown in FIG. 2 is the thickness of the viewing-side polarizing plate, and the back-side polarizing plate is used for the viewing-side polarizing plate. For example, the arrow mark 200 shown in FIG. 3 is the thickness of the back side polarizing plate.

In addition, in the first figure, the adhesive layer or the adhesive layer for bonding the polarizer and the protective film is omitted. That is, for example, an adhesive layer or an 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 those shown in Fig. 1.

In the kit of the polarizing plate of the present invention, the difference between the thickness of the polarizing plate on the viewing side and the thickness of the polarizing plate on the back side is 13 μm or less, preferably -2 to 13 μm, particularly preferably -2 to 10 μm, more preferably 1 to 10 μm. Further, in the kit of the polarizing plate of the present invention, the difference between the thickness of the first polarizer included in the viewing-side polarizing plate and the thickness of the second polarizer included in the back-side polarizing plate is more than 0 μm and 10 μm or less. It is preferably more than 0 μm and 7 μm or less, and more preferably more than 0 μm and not more than 5 μm, and may be 1 μm or more. The thickness of the first polarizer is preferably larger than the thickness of the second polarizer.

Thus, by making the polarizing plate and the polarizer have a thickness Poor, not only can reduce the warpage of the liquid crystal panel in a high temperature environment, but also suppress the warpage of the liquid crystal panel under normal temperature environment. Although the reason is still inconclusive, as will be described later, it is considered that the difference in thickness between the polarizer and the polarizer can affect the entry and exit of moisture of the members constituting the polarizing plate in a normal temperature environment. In addition, when the brightness enhancement film is a stretched film in a high-temperature environment, the contraction force of the back side polarizing plate can be made equal to the contraction force of the viewing side polarizing plate in a high temperature environment, so that the warpage of the liquid crystal panel can be reduced. .

In the kit of the polarizing plate of the present invention, the moisture content of 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 a drying reduction method. Specifically, the weight (weight before drying) after being left for 3 days in an environment of a temperature of 23° C. and a humidity of 55% was measured, and then the weight (weight after drying) after standing for 1 hour in an environment of 105° C. was measured. And the value calculated according to the following formula. The moisture content of the viewing side polarizing plate is preferably greater than the moisture content of the back side polarizing plate, and may be 0.2% or more.

Moisture rate = 100 × [(weight before drying) - (weight after drying)] / weight before drying

Further, the sum of the thickness of the viewing-side polarizing plate and the thickness of the back-side polarizing plate is preferably 200 μm or less, and particularly preferably 170 μm or less. The lower limit is not particularly limited, but is usually 100 μm or more. By setting it as the said range, it is easy to control the moisture of the entrance and exit of a polarizing plate.

The members constituting the kit of the polarizing plate of the present invention will be described. Hereinafter, the first polarizer and the second polarizer are collectively referred to as a polarizer. The first protective film, the second protective film, and the third protective film may be collectively referred to as a protective film, and the first adhesive layer, the second adhesive layer, and the third adhesive layer may be collectively referred to as an adhesive layer. The separator and the protective film are collectively referred to as a surface protective film.

(polarizer)

The polarizer used in the present invention is usually obtained by the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film, and dyeing a polyvinyl alcohol-based resin film with a dichroic dye to obtain a dichroic dye The step of adsorbing, the step of treating the polyvinyl alcohol-based resin film to which the dichroic dye is adsorbed by the aqueous solution of boric acid, and the step of performing water washing after the treatment with the aqueous solution of boric acid.

As the polyvinyl alcohol-based resin, a polyvinyl acetate-based resin can be used for saponification. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers copolymerizable therewith, in addition to the polyvinyl acetate of a homopolymer of vinyl acetate. Examples of the other monomer 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. The polyvinyl alcohol-based resin may be modified, and for example, an aldehyde-modified polyvinyl formal or polyvinyl acetal may be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually from about 1,000 to 10,000, preferably from about 1,500 to 5,000.

When a polyvinyl alcohol resin is formed into a film, it is available As a preform film of a polarizer. A method of forming a film of a polyvinyl alcohol-based resin can be carried out by a conventional method. When the thickness of the obtained polarizer is 15 μm or less, the film thickness of the polyvinyl alcohol-based raw material film is preferably about 5 to 35 μm, and more preferably 5 to 20 μm. When the film thickness of the seed material film is 35 μm or more, the stretching ratio is increased in the production of the polarizer, and the size shrinkage of the obtained polarizer tends to increase. On the other hand, when the film thickness of the seed material film is 5 μm or less, the handleability at the time of stretching is lowered, and there is a tendency that the cutting or the like is likely to occur during production.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. This uniaxial extension can be carried out prior to boric acid treatment or boric acid treatment when uniaxially extending after dyeing. In addition, uniaxial stretching can also be performed in a plurality of stages.

In the case of uniaxial stretching, it is possible to extend the uniaxially between the rolls having different peripheral speeds, or to extend the uniaxially by using a hot roll. Further, the uniaxial stretching may be a dry stretching in which stretching is performed in the atmosphere, or may be a wet stretching in which a solvent is used and the polyvinyl alcohol-based resin film is swollen. The stretching ratio is usually about 3 to 8 times.

A method of dyeing a polyvinyl alcohol-based resin film by a dichroic dye can be, for example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. The dichroic dye may specifically be iodine or a dichroic dye. The polyvinyl alcohol-based resin film is preferably subjected to immersion in water beforehand before the dyeing treatment.

When iodine is used as the dichroic dye, the polyvinyl alcohol-based resin film is usually immersed in an aqueous solution containing iodine and potassium iodide. The method of dyeing. The content of iodine in the aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. Further, 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. Further, the immersion time (dyeing time) in the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye and dyed is usually used. The content of the dichroic dye in the aqueous solution is usually from about 1 × 10 ^-4 to 10 parts by weight, preferably from about 1 × 10 ^-3 to about 1 part by weight, per 100 parts by weight of the water. The aqueous solution may also contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The temperature of the aqueous solution of the dichroic dye used for dyeing is usually about 20 to 80 °C. Further, the immersion time (dyeing time) in the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing by the dichroic dye is usually carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid.

The amount of boric acid in the aqueous solution containing boric acid is usually from about 2 to 15 parts by weight, preferably from 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide. The amount of potassium iodide in the aqueous solution containing boric acid 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. When immersed in an aqueous solution containing boric acid The interval 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 aqueous solution containing boric acid is usually 50 ° C or higher, preferably 50 to 85 ° C, and particularly preferably 60 to 80 ° C.

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

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

By the drying treatment, the moisture content of the polarizer is lowered to a practical level. The moisture content is usually from 5 to 20% by weight, preferably from 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 drying. Further, when the moisture content is more than 20% by weight, the thermal stability of the polarizer may be deteriorated.

Further, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol-based resin film in the production step of the polarizer can be carried out according to, for example, the method described in JP-A-2012-159778. In the method described in this document, a polyvinyl alcohol-based resin layer which is a polarizer is formed by applying a polyvinyl alcohol-based resin to a base film.

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

(protective film)

The protective film is composed of a resin film and can be composed of a transparent resin film. It is particularly excellent in materials such as transparency, mechanical strength, thermal stability, and moisture shielding properties. In the present specification, the transparent resin film means a resin film having a monomer transmittance of 80% or more in the visible light region.

The resin that forms the protective film is not particularly limited, and examples thereof include a methyl methacrylate resin, a polyolefin resin, a cyclic olefin resin, a polyvinyl chloride resin, a cellulose resin, and a styrene resin. Acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamine resin, polyacetal resin, polycarbonate Resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyfluorene resin, polyether oxime resin, polyarylate resin, A film composed of a polyamidoximine-based resin and a polyimine-based resin. These resin films may be films formed from a raw material resin, or uniaxially stretched films obtained by lateral stretching after film formation, or longitudinally stretched after film formation, and then laterally extended. Biaxially stretched film, etc.

These resins may be used singly or in combination of two or more. Further, these resins may be used after any suitable polymer modification, and the polymer may be modified, for example, by copolymerization, crosslinking, molecular terminal modification, stereoregular control, and inclusion of accompanying phases. Heterogeneous polymerization The modification of the mixing of the substances in response to each other.

Among these, a material of the protective film is preferably a methyl methacrylate resin, a polyethylene terephthalate resin, a polyolefin resin, or a cellulose resin. Here, the polyolefin resin includes a chain polyolefin resin and a cyclic polyolefin resin.

The methyl methacrylate-based resin is a polymer containing 50% by weight or more of a methyl methacrylate unit. The content of the methyl methacrylate unit is preferably 70% by weight or more, and may be 100% by weight. The methyl methacrylate unit is a 100% by weight polymer, which is a methyl methacrylate homopolymer obtained by separately polymerizing methyl methacrylate.

The methyl methacrylate-based resin can be usually obtained by polymerizing a monofunctional monomer having methyl methacrylate as a main component in the presence of a radical polymerization initiator. When polymerizing, a polyfunctional monomer or a chain transfer agent may coexist as needed.

The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and A. Methyl acrylates other than methyl methacrylate such as benzyl acrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, Acrylates such as cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; methyl 2-(hydroxymethyl)acrylate, 3-(hydroxyethyl) ) hydroxyalkyl acrylates such as methyl acrylate, ethyl 2-(hydroxymethyl) acrylate, and butyl 2-(hydroxymethyl) acrylate; insufficient methacrylic acid and acrylate And acids; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyl toluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; maleic anhydride And unsaturated anhydrides such as citraconic anhydride; and unsaturated quinoids such as phenyl maleimide and cyclohexylmethyleneimine. These monomers may be used alone or in combination of two or more.

The polyfunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and di(a). Base) triethylene glycol acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecyl glycol di(meth)acrylate, etc. by acrylic acid Or methacrylic acid esterifying the hydroxyl groups at both ends of ethylene glycol or its oligomer; esterifying the terminal hydroxyl groups of propylene glycol or its oligomer by acrylic acid or methacrylic acid; di(methyl) a pentyl glycol acrylate, a hexanediol di(meth)acrylate, and a butylene glycol di(meth)acrylate, etc. by esterifying a hydroxyl group of a glycol with acrylic acid or methacrylic acid; Acrylic acid or methacrylic acid which esterifies bisphenol A, an alkylene oxide adduct of bisphenol A, or a terminal hydroxyl group of such a halogen substituent; a trimethylol group by acrylic acid or methacrylic acid Polyols such as propane and neopentyl alcohol are esterified; and glycidyl acrylate or glycidyl methacrylate is used. The oxy ring is added to the terminal hydroxyl group of the polyol; the epoxy group of glycidyl acrylate or glycidyl methacrylate is ring-opened and added to succinic acid, adipic acid, and terephthalic acid. a diprotonic acid such as phthalic acid or a halogen-substituted product thereof, and an alkylene oxide adduct thereof; (meth)acrylic acid Propyl ester; and an aromatic divinyl compound such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate can be preferably used.

The methyl methacrylate-based resin may be modified by further performing a reaction between the functional groups copolymerized with the resin. The reaction may, for example, be an intramolecular decopolymerization condensation reaction of a methyl ester group of methyl acrylate with a hydroxyl group of methyl 2-(hydroxymethyl) acrylate, or a carboxyl group and 2-(hydroxymethyl) group of acrylic acid. A polymer chain internal dehydration condensation reaction of a hydroxyl group of methyl acrylate.

The polyethylene terephthalate resin means a resin composed of ethylene terephthalate in an amount of 80 mol% or more of the repeating unit, and may contain other dicarboxylic acid component and diol component. The other dicarboxylic acid component is not particularly limited, and examples thereof include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxydiphenyl ketone, and bis(4-carboxyphenyl) Alkane, adipic acid, sebacic acid, and 1,4-dicarboxycyclohexane.

The other diol component is not particularly limited, and examples thereof include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, and polyethylene glycol. , polypropylene glycol, and polytetramethylene glycol.

These dicarboxylic acid components or diol components may be used in combination of two or more kinds as needed. Further, a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p-β-hydroxyethoxybenzoic acid may be used in combination. Further, as the other copolymerization component, a dicarboxylic acid component or a diol component containing a small amount of a guanamine bond, a urethane bond, an ether bond, or a carbonate bond may be used.

A method for producing a polyethylene terephthalate resin: a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as needed); a method in which a dialkyl ester of formic acid and ethylene glycol (and optionally a dialkyl ester of a dicarboxylic acid or other diol) are subjected to a transcondensation reaction, followed by a polycondensation; and in the presence of a catalyst, a p-benzoic acid A method of polycondensation of a glycol ester of formic acid (and other dicarboxylic acids as needed) (and other glycol esters as needed). Further, solid phase polymerization may be carried out as needed to increase the molecular weight or reduce the low molecular weight component.

The cyclic polyolefin-based resin is obtained by, for example, polymerizing a cyclic olefin monomer such as norbornene or another cyclopentadiene derivative in the presence of a catalyst. It is preferable to use such a cyclic polyolefin-based resin to easily obtain a protective film having a predetermined retardation value to be described later.

Examples of the cyclic polyolefin-based resin include those obtained from cyclopentadiene and olefins or (meth)acrylic acid or an ester thereof by Diels-Alder Reaction. Terpene or a derivative thereof, which is subjected to ring-opening shift polymerization as a monomer, and then obtained by hydrogenation; by dimes-Adel reaction from dicyclopentadiene to olefins or (methyl) a tetracyclododecene or a derivative thereof obtained by using acrylic acid or an ester thereof, which is subjected to ring-opening shift polymerization as a monomer, and then obtained by hydrogenation; and is selected from the group consisting of norbornene and tetracyclic At least two monomers of an alkene, such a derivative, and other cyclic olefin monomers, similarly subjected to ring-opening shift copolymerization, and then obtained by hydrogenation; a chain olefin and/or having ethylene Aromatic compound, addition copolymerization in, for example, norbornene, A resin obtained by a cyclic olefin such as tetracyclododecene or a derivative thereof.

Typical examples of the chain polyolefin resin are a polyethylene resin and a polypropylene resin. Among them, a homopolymer of propylene or a comonomer which is propylene-based and copolymerized with propylene in a ratio of 1 to 20% by weight, preferably 3 to 10% by weight, such as ethylene, may be preferably used. Copolymerized copolymer.

The polypropylene resin may contain an alicyclic saturated hydrocarbon resin. The retardation value is easily controlled by containing an alicyclic saturated hydrocarbon resin. The content of the alicyclic saturated hydrocarbon resin is preferably from 0.1 to 30% by weight, particularly preferably from 3 to 20% by weight, based on the polypropylene resin. When the content of the alicyclic saturated hydrocarbon resin is less than 0.1% by weight, the effect of controlling the retardation value cannot be sufficiently obtained. On the other hand, when the content exceeds 30% by weight, the alicyclic saturated hydrocarbon resin may pass over time. The second protective film seeps out.

Cellulose-based resin means a part or all of hydrogen atoms in the hydroxyl group of cellulose obtained from raw material cellulose such as cotton linters or wood pulp (broadwood pulp, coniferous wood pulp) via ethyl ketone, propyl ketone and/or Or a cellulose organic acid ester or a cellulose mixed organic acid ester substituted by a butyl group. For example, it is composed of cellulose acetate, propionate, butyrate, and a mixed ester of these. Among them, a cellulose triacetate film, a cellulose diacetate film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like are preferable.

The methyl methacrylate resin, the polyethylene terephthalate resin, the polyolefin resin, and the cellulose resin are formed into a second protective film for the polarizer, and can be appropriately selected. The method of each resin is not particularly limited. For example, it can be used: it will dissolve in solution. The resin of the agent is cast on a metal belt or a drum, and the solvent is dried and removed to obtain a solvent casting method of the film; and the resin is heated to a temperature above the melting temperature and kneaded, extruded from the mold and cooled to obtain a melt extrusion of the film. System of law. In the melt extrusion method, extrusion of a single layer film or simultaneous extrusion of a multilayer film may be employed.

Commercially available products can be easily obtained by using a film as a protective film, and the methyl methacrylate resin film is represented by a product name, and is Sumipex (manufactured by Sumitomo Chemical Co., Ltd.) and Acrylite (registered trademark). ), Acryplen (registered trademark) (above is manufactured by Mitsubishi Rayon Co., Ltd.), Delaglas (registered trademark) (made by Asahi Kasei Co., Ltd.), Paraglas (registered trademark), Comoglas (registered trademark) (above, manufactured by Kuraray Co., Ltd.) ), and Acryviewa (registered trademark) (made by Nippon Shokubai Co., Ltd.). The polyolefin resin film is represented by a product name, and may be, for example, Zeonor (registered trademark) (manufactured by Zeon Japan Co., Ltd.), Arton (registered trademark) (manufactured by JSR Co., Ltd.), or the like. The polyethylene terephthalate resin film is represented by a trade name, and includes Novaclear (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET Sheet (Teijin Chemical Co., Ltd.) System) and so on. The polypropylene resin film is represented by a product name, and is a FILMAX CPP film (manufactured by FILMAX Co., Ltd.), Sun Tox (registered trademark) (manufactured by Sun Tox Co., Ltd.), and Tohcello (registered trademark) (Tohcello). Co., Ltd.), Toyobo Pylen Film (registered trademark) (manufactured by Toyobo Co., Ltd.), Torayfan (registered trademark) (manufactured by Toray Advanced Film Co., Ltd.), Nihon Polyace (registered trademark), (Nihon Polyace Co., Ltd.) System), and Taige FC (registration) Trademark) (made by Futamura Chemical Co., Ltd.). In addition, the cellulose-based resin film is represented by a product name, and includes Fujitac (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), and KC2UA and Konica Minolta TAC Film KC (Konica Minolta Co., Ltd.). System) and so on.

The protective film used in the present invention can be imparted with anti-glare property (haze), and the method for imparting anti-glare property is not particularly limited. For example, inorganic fine particles or organic fine particles may be mixed in the raw material resin to form a film. Method; a method of performing two-layer film formation by using the above-mentioned multilayer extrusion and a resin in which one particle is mixed with another resin which is not mixed with particles; or a method in which a resin in which particles are mixed is externally and three-layer film is formed And a method in which a coating liquid obtained by mixing inorganic fine particles or organic fine particles in a curable adhesive resin is applied to one side of the film, and the adhesive resin is cured to provide an antiglare layer.

Further, the protective film may contain an additive as needed. Examples of the additive include a lubricant, an anti-caking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light stabilizer, and an impact modifier.

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

The protective film is preferably subjected to a saponification treatment, a corona treatment, a plasma treatment or the like before being bonded to the polarizer.

In the first protective film, a functional layer such as a conductive layer, a hard coat layer, or a low reflection layer may be further provided. Further, a resin composition having such functions may be selected as the binder resin constituting the antiglare layer.

(brightness lifting film)

The back side polarizing plate is provided with a brightness enhancement film on the side of the second polarizer away from the liquid crystal cell. The thickness of the brightness enhancement film is preferably 35 μm or less, and particularly preferably 30 μm or less.

As the brightness enhancement film, a polarization conversion element having a function of separating emitted light from a light source (backlight) into a polarized light and a reflected polarized or scattered polarized light can be used. The brightness enhancement film can improve the emission efficiency of the linear polarization by utilizing the return light from the backlight which reflects the polarized light or scatters the polarized light.

Examples of the brightness enhancement film include an anisotropic reflective polarizer. The anisotropic reflective polarizer includes an anisotropic multiple film which transmits linearly polarized light in one vibration direction and linearly polarized light in the other vibration direction. Examples of the anisotropic multiple film include the trade names "APF" and "DBEF" manufactured by 3M Company. Further, examples of the anisotropic reflective polarizer include a composite of a cholesteric liquid crystal layer and a λ/4 plate. The product name "PCF" manufactured by Nitto Denko Corporation is exemplified for the composite. Further, examples of the anisotropic reflective polarizer include a reflective grating polarizer. The reflective grating polarizer may be a finely processed metal, and a metal square reflective polarizer that reflects polarized light may be emitted even in a visible light region. Among them, a brightness enhancement film composed of an anisotropic multiple film is preferred.

A functional layer can be formed on the opposite side of the bonding surface of the brightness enhancement film and the polarizing plate. Examples of the functional layer include a hard coat layer, an antiglare layer, a light diffusion layer, and a phase difference layer having a phase difference of 1/4 wavelength, thereby improving adhesion to the backlight tape or improving display Image uniformity.

(surface protective film)

The separator is used to protect the surface of the film and the back side polarizing plate until the viewing side polarizing plate and the back side polarizing plate are bonded to the liquid crystal cell. The separator is usually composed 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 adhesive layer or the second adhesive layer. The thermoplastic resin film constituting the separator may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, or a polyester system such as polyethylene terephthalate or polyethylene naphthalate. Resin, etc. When the third adhesive layer previously provided on the brightness enhancement film is provided, the surface of the third adhesive layer may be preliminarily attached to the surface in order to temporarily protect the surface of the third adhesive layer until the second polarizer is bonded thereto. Separator. The thickness of the separator is, for example, 10 to 50 μm.

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

The resin constituting the resin film may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, or a polyester resin such as polyethylene terephthalate or polyethylene naphthalate. A thermoplastic resin such as a polycarbonate resin. Preferably, it is a polyester system such as polyethylene terephthalate. Resin. The resin film may have a single layer structure or a multilayer structure, and is preferably a single layer structure from the viewpoints of ease of production and production cost. The description of the first adhesive layer or the second adhesive layer to be described later will be given to the adhesive layer of the protective film.

(first adhesive layer, second adhesive layer)

On the surface of the polarizing plate, an adhesive layer can be laminated. The polarizing plate can be attached to the liquid crystal cell via the adhesive layer. In the first drawing, the first adhesive layer 40 and the second adhesive layer 41 correspond to this. The thickness of the adhesive layer formed of the adhesive is preferably 5 to 25 μm. More preferably, it is 10 to 25 μm.

The adhesive for forming the first adhesive layer and the second adhesive layer can be appropriately selected and used, for example, as an acrylic polymer, a polyoxymethylene polymer, a polyester, a polyurethane, a polyamide, or a poly A polymer such as a vinyl ether, a vinyl acetate/vinyl chloride copolymer, a modified polyolefin, an epoxy-based, a fluorine-based, a natural rubber, or a synthetic rubber is used as a base polymer. The adhesive is particularly excellent in optical transparency, and exhibits excellent wettability, cohesiveness and adhesion properties, and excellent weather resistance and heat resistance.

Among the adhesives, various other additives can be added. Examples of the additive include a decane coupling agent and an antistatic agent.

The first adhesive layer and the second adhesive layer have a storage modulus of elasticity of preferably 0.01 to 0.1 MPa, particularly preferably 0.02 to 0.06 MPa at 23 to 80 °C. The phrase "storage elastic modulus of 0.01 to 0.1 MPa at 23 to 80 ° C" means that the storage elastic modulus is a value of the above range at any temperature in this range. Store elastic modulus, usually with temperature The storage modulus is gradually decreased. Therefore, if the storage elastic modulus at 23 ° C and 80 ° C is in the above range, it can be considered that the adhesive layer exhibits the storage elastic modulus of the above range in the temperature of this range. The storage elastic modulus of the adhesive layer can be measured by a commercially available viscoelasticity measuring device such as a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC.

(Method of manufacturing polarizing plate)

A method of manufacturing the viewing-side polarizing plate and the back-side polarizing plate constituting the polarizing plate of the present invention will be described. The members described above may be laminated to each other via, for example, an adhesive layer or an adhesive layer.

(layer of polarizer and protective film)

The laminate of the protective film and the polarizer is preferably, for example, a method in which it is integrated by using an adhesive. The thickness of the adhesive layer formed of the adhesive is preferably from 0.01 to 35 μm, more preferably from 0.01 to 10 μm, still more preferably from 0.01 to 5 μm. If it is in this range, no floating or peeling will occur between the protective film and the polarizer, and an adhesive force which is practically problem-free can be obtained.

Examples of the subsequent agent include a solvent-based adhesive, an emulsified adhesive, a pressure-sensitive adhesive, a rewetting adhesive, a polycondensation adhesive, a solventless adhesive, a film adhesive, and a hot melt adhesive. Wait. In addition, it may be desirable to provide an adhesive layer via a fixed anchor coating layer.

A preferred water-based adhesive is exemplified as the preferred adhesive. As the water-soluble adhesive, for example, a polyvinyl alcohol-based resin is mainly contained. A commercially available product may be used as the water-soluble adhesive, and a solvent or an additive may be used in a commercially available adhesive. For the commercially available polyvinyl alcohol-based resin which can be a water-soluble adhesive, for example, Kuraray Co., Ltd. KL-318 and so on.

A water soluble adhesive, which may contain a crosslinking agent. The type of the crosslinking agent is preferably an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, or a polyvalent metal salt, and particularly preferably an epoxy compound. Commercial products of the crosslinking agent include, for example, Glyoxal, Sumirez Resin 650 (30) manufactured by Tajika Chemical Industry Co., Ltd., and the like.

Further, another preferable adhesive agent is an active energy ray-curable adhesive comprising a resin composition which is cured by irradiation with an active energy ray. Examples of the active energy ray-curable adhesive layer include those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, and those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, or a photopolymerizable monomer. Oligomers. The photopolymerization initiator may be one which contains an active species such as a radical, a cation, or an anion by irradiation with an active energy ray such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.

When the active energy ray-curable adhesive is used, after the polarizer and the protective film are bonded, a drying step may be performed as needed, and then the active energy ray is irradiated to harden the active energy ray-curable adhesive. The light source of the active energy ray is not particularly limited, and is preferably an ultraviolet ray having a light-emitting distribution at a wavelength of 400 nm or less. Specifically, Use low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, fluorescent lamps for insect traps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like.

The above adhesive may contain an additive. Examples of the additive include an ion trapping agent, an antioxidant, a chain transfer agent, a sensitizer, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent.

(Lamination of polarizer and brightness enhancement film)

When the polarizer is bonded to the brightness enhancement film, it is preferred to use an adhesive layer. In Fig. 1, the third adhesive layer corresponds to this. The thickness of the adhesive layer formed of the adhesive is preferably from 3 to 20 μm. More preferably, it is 3 to 10 μm.

The adhesive layer of the polarizer and the brightness enhancement film is bonded, and, for example, an acrylic polymer, a polyoxymethylene polymer, a polyester, a polyurethane, a polyamide, a polyvinyl ether can be appropriately selected and used. A polymer such as a vinyl acetate/vinyl chloride copolymer, a modified polyolefin, an epoxy-based, a fluorine-based, a natural rubber, or a synthetic rubber is used as a base polymer. The adhesive is particularly excellent in optical transparency, and exhibits excellent wettability, cohesiveness and adhesion properties, and excellent weather resistance and heat resistance.

Among the adhesives, various other additives can be added. Examples of the additive include a decane coupling agent and an antistatic agent.

The third adhesive layer has a storage elastic modulus of preferably 0.10 to 1.0 MPa, particularly preferably 0.15 to 0.8 MPa at 23 to 80 °C. 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 hot and humid environment can be alleviated, and the liquid crystal panel can be more effectively reduced. Warping. In the method of setting the storage elastic modulus of the third adhesive layer to 0.10 to 1.0 MPa, it is effective to prepare the urethane acrylate oligomer in a usual adhesive composition. It is preferred to formulate such a urethane acrylate-based oligomer and to illuminate the energy ray to harden it, and exhibit a high storage elastic modulus.

The shape of the polarizing plate of the present invention is not particularly limited and may be a rectangle. When the polarizing plate is manufactured in a roll-to-roll manner, 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 Å or less, a rectangular shape having a diagonal of 3 吋 or more, or a rectangular shape having a diagonal of 7 吋 or more.

(Manufacturing method of liquid crystal panel)

A liquid crystal panel can be obtained by attaching the sets of the polarizing plates of the present invention to both sides of the liquid crystal cell. The bonding is preferably carried out via the first adhesive layer of the viewing-side polarizing plate and the second adhesive layer via the back-side polarizing plate. The liquid crystal panel of the present invention can be preferably applied to a liquid crystal display device. The viewing side polarizing plate is preferably attached such that its absorption axis is substantially parallel to the short side direction of the liquid crystal cell, and the back side polarizing plate is preferably such that its absorption axis is substantially parallel to the longitudinal direction of the liquid crystal cell. Come to fit. In the present specification, the term "substantially parallel" means that the angle formed is, for example, 0 ± 5 °, preferably 0 ± 1 °.

The liquid crystal panel is preferably manufactured, for example, at a temperature of 18 to 28 ° C and a relative humidity of 40 to 70%, from the viewpoint of controlling the moisture in and out of the viewing side polarizing plate and the back side polarizing plate, and further improving the effect of the present invention. Go on.

The liquid crystal cell has a liquid crystal layer between two unit substrates and a substrate sandwiched between them. The unit substrate is generally made of glass or a plastic substrate. Others, the liquid crystal cell itself used in the liquid crystal panel of the present invention can be constituted by various types employed in the field. According to the kit of the polarizing plate of the present invention, even if the thickness of the liquid crystal cell is 0.4 mm or less, warpage can be remarkably reduced. In the present invention, the thickness of the liquid crystal cell includes a liquid crystal layer and a thickness of the substrate sandwiched by one of the liquid crystal layers.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention should not be construed as limited. In the examples, the % and the parts of the content and the amount used are based on weight unless otherwise specified. Further, the evaluation methods used in the examples are as follows.

(1) Thickness: Measured using a Digital Micrometer MH-15M manufactured by Nikon Co., Ltd.

(2) In-plane retardation value Re and thickness direction retardation value Rth: A phase difference meter based on the principle of parallel polarization rotation method, KOBRA-WPR manufactured by Oji Scientific Instruments Co., Ltd., at a wavelength of 590 nm at 23 ° C Light was measured.

(3) Storage elastic modulus: The storage elastic modulus (G') of the adhesive is a cylindrical test piece of 8 mm in diameter × 1 mm in thickness composed of an adhesive to be measured, and a dynamic viscoelasticity measuring device (Dynamic) is used. Analyzer RDA II: manufactured by REOMETRIC Co., Ltd., with a torsional shear at a frequency of 1 Hz In the method, the initial strain was set to 1 N, and the measurement was carried out under the conditions of a temperature of 23 ° C or a temperature of 80 ° C.

Each member was prepared as described below.

(Polarizer A)

By dry stretching, a polyvinyl alcohol film having a thickness of 30 μm (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 5 times, and then kept tight, and impregnated with pure water at 60 ° C. After a minute, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 8.5/8.5/100 at 72 ° C for 300 seconds. Then, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having a thickness of 12 μm in the form of iodine adsorbed on the polyvinyl alcohol film.

(Polarizer B)

By dry stretching, a polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 5 times, and then kept tight, and impregnated with pure water at 60 ° C. After a minute, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 8.5/8.5/100 at 72 ° C for 300 seconds. Then, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having a thickness of 7 μm in the form of iodine adsorbed on the polyvinyl alcohol film.

(Polarizer C)

By dry stretching, a polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 4.9 times. Then, it was kept in a tight state, immersed in pure water at 60 ° C for 1 minute, and then immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 8.5/8.5/100 at 72 ° C for 300 seconds. Then, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having a thickness of 8 μm in the form of iodine adsorbed on the polyvinyl alcohol film.

(Adhesive layer A)

Use: A commercially available adhesive sheet having an acrylic adhesive layer having a thickness of 20 μm in a release-treated area of a polyethylene terephthalate film (separator) having a thickness of 38 μm which had been subjected to release treatment. In the acrylic adhesive, the urethane acrylate oligomer was not formulated. The storage elastic modulus of the adhesive layer after removing the release film from the adhesive sheet was 0.05 MPa at 23 ° C and 0.04 MPa at 80 ° C.

(Adhesive layer B)

Use: A commercially available adhesive sheet having an acrylic pressure-sensitive adhesive layer having a thickness of 15 μm in a release-treated area layer of a polyethylene terephthalate film (separator) having a thickness of 38 μm which had been subjected to release treatment. In the acrylic adhesive, the urethane acrylate oligomer was not formulated. The storage elastic modulus of the adhesive layer after removing the release film from the adhesive sheet was 0.05 MPa at 23 ° C and 0.04 MPa at 80 ° C.

(adhesive layer C)

An organic solvent solution of an urethane acrylate oligomer and an isocyanate crosslinking agent is added to a copolymer of butyl acrylate and acrylic acid, and the thickness after drying is 5 μm by a die coater. Coating The release-treated surface of the polyethylene terephthalate film (separator) having a thickness of 38 μm which had been subjected to mold release treatment was dried and dried to obtain an adhesive sheet in which an adhesive layer was laminated. The storage elastic modulus of the adhesive layer after removing the release film from the adhesive sheet was 0.40 MPa at 23 ° C and 0.18 MPa at 80 ° C.

(protective film)

The following protective film was prepared.

Protective film A: a cellulose triacetate film (manufactured by Konica Minolta Co., Ltd.) having a thickness of 20 μm. The phase difference value in the in-plane of the wavelength of 590 nm is 1.2 nm, and the retardation value in the thickness direction of the wavelength of 590 nm is 1.3 nm.

Protective film B: a cycloolefin-based resin film (manufactured by Zeon Japan Co., Ltd.) having a thickness of 13 μm. In the in-plane retardation of wavelength 590 nm, the retardation value is 0.8 nm, the thickness difference in the thickness direction at a wavelength of 590 nm is 3.4 nm, the retardation in the thickness direction at a wavelength of 483 nm is 3.5 nm, and the retardation in the thickness direction at a wavelength of 755 nm is 2.8. Nm.

Protective film C: a cycloolefin-based resin film (manufactured by Zeon Japan Co., Ltd.) having a thickness of 23 μm.

Protective film D: a cellulose triacetate film (manufactured by Toppan TOMOEGAWA Optical Film Co., Ltd., 25KCHC-TC) having a surface of 32 μm in thickness. The moisture permeability is 400 g / (m ² ‧ 24 hr).

(brightness lifting film)

A brightness enhancement film (manufactured by 3M Company, trade name ADvanceD PolarizeD Film, Version 3) having a thickness of 26 μm was used.

(water system adhesive)

3 parts of carboxy-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts of water, and 1.5 parts of a polyamine-based epoxy-based additive belonging to a water-soluble epoxy compound was added to the aqueous solution ( Sumirez Resin (registered trademark) 650 (30) manufactured by Sumika Chemtex Co., Ltd., and an aqueous solution having a solid concentration of 30%) is used as a water-based adhesive.

(Manufacturing Example 1: viewing side polarizing plate A)

The protective film B is bonded to one surface of the polarizer A via a water-based adhesive. The protective film D is bonded to the other surface of the polarizer A via a water-based adhesive. The adhesive layer A laminated on the release film is bonded to the surface of the protective film B opposite to the bonding surface of the polarizer A. The thickness of the viewing side polarizing plate A was 77 μm.

(Manufacturing Example 2: viewing side polarizing plate B)

The protective film C is bonded to one surface of the polarizer A via a water-based adhesive. The protective film D is bonded to the other surface of the polarizer A via a water-based adhesive. The adhesive layer A laminated on the release film is bonded to the surface of the protective film C opposite to the bonding surface of the polarizer A. The thickness of the viewing side polarizing plate B was 87 μm.

(Manufacturing Example 3: viewing side polarizing plate C)

The protective film A is bonded to one surface of the polarizer B via a water-based adhesive. The protective film D is bonded to the other surface of the polarizing plate B via a water-based adhesive. The adhesive layer A laminated on the release film is bonded to the surface of the protective film A opposite to the bonding surface of the polarizer B. The thickness of the viewing side polarizing plate C was 79 μm.

(Manufacturing Example 4: Back side polarizing plate A)

The protective film B is bonded to one surface of the polarizer B via a water-based adhesive. The adhesive layer C laminated on the release film is bonded to the surface of the polarizer B opposite to the bonding surface of the protective film B. The adhesive layer B laminated on the release film is bonded to the surface of the protective film B opposite to the bonding surface of the polarizer B. The release film on the adhesive layer C was peeled off, and the brightness enhancement film was bonded thereto. The thickness of the back side polarizing plate A was 66 μm.

(Manufacturing Example 5: Back side polarizing plate B)

The protective film A is bonded to one surface of the polarizer B via a water-based adhesive. The adhesive layer C laminated on the release film is bonded to the surface of the polarizer B opposite to the bonding surface of the protective film A. The adhesive layer A laminated on the release film is bonded to the surface of the protective film A opposite to the bonding surface of the polarizer B. The release film on the adhesive layer C was peeled off, and the brightness enhancement film was bonded thereto. The thickness of the back side polarizing plate B was 78 μm.

(Manufacturing Example 6: Back side polarizing plate C)

The protective film A is bonded to one surface of the polarizer B via a water-based adhesive. The adhesive layer C laminated on the release film is bonded to the surface of the polarizer B opposite to the bonding surface of the protective film A. The adhesive layer B laminated on the release film is bonded to the surface of the protective film A opposite to the bonding surface of the polarizer B. The release film on the adhesive layer C was peeled off, and the brightness enhancement film was bonded thereto. The thickness of the back side polarizing plate C was 73 μm.

(Manufacturing Example 7: viewing side polarizing plate D)

The viewing-side polarizing plate D was produced in the same manner as in Production Example 1 except that the polarizer C was used instead of the polarizer A. The thickness of the viewing side polarizing plate D was 73 μm.

(Manufacturing Example 8: viewing side polarizing plate E)

The viewing-side polarizing plate E was produced in the same manner as in Production Example 2 except that the polarizer C was used instead of the polarizer A. The thickness of the viewing side polarizing plate E was 83 μm.

(Manufacturing Example 9: Back side polarizing plate D)

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

(Manufacturing Example 10: Back side polarizing plate E)

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

(Manufacturing Example 11: Back side polarizing plate F)

The back side polarizing plate F was produced in the same manner as in Production Example 6 except that the polarizer C was used instead of the polarizer B. The thickness of the back side polarizing plate F was 74 μm.

(Example 1)

The viewing-side polarizing plate A and the back-side polarizing plate A were cut into a rectangular shape having a longitudinal direction of 155.25 mm and a short-side direction of 95.9 mm. In addition, the viewing-side polarizing plate is cut such that its absorption axis is parallel to the short-side direction, and the back-side polarizing plate is cut so that its absorption axis is parallel to the longitudinal direction.

(warpage of the panel under normal temperature conditions)

Peeling off the adhesive layer A from the cut side polarizing plate A The film was peeled off and bonded to one surface of an alkali-free glass (corresponding to a liquid crystal cell substrate, which is a rectangle of 160 mm in the longitudinal direction and 102 mm in the short side direction) via the adhesive layer A. The release film on the adhesive layer B is peeled off from the cut back side polarizing plate A, and bonded to the other surface of the alkali-free glass via the adhesive layer B. In this way, a laminated body composed of the viewing-side polarizing plate A/glass plate/back side polarizing plate A was obtained. This laminate was then autoclaved. The absorption axes of the respective polarizing plates are orthogonal. Furthermore, in any of the embodiments, the moisture content of the viewing-side polarizing plate was 1.13%, and the moisture content of the back-side polarizing plate was 0.6%, and the difference between the two was 0.53%.

The laminate was allowed to stand in an environment of a temperature of 23 ° C and a humidity of 55% RH for 24 hours. Then, the laminated body was placed on a measuring stand of a two-dimensional measuring instrument (manufactured by Nikon Co., Ltd., NEXIV (registered trademark) VMZ-R4540) so that the viewing-side polarizing plate A was on the upper side.

Then, the focus was focused on the surface of the measurement table, and the focus was focused on 25 points on the surface of the laminate, and the height from the reference focus was measured. The difference between the maximum value and the minimum value of the height of the measurement point of 25 points is set as the amount of warpage. The results are shown in Table 1 below. Fig. 5 is a schematic view showing the measurement points of the amount of warpage. 70 is a "measurement point", 71 is a polarizing plate, and 72 is a glass plate. The 25 "measurement points" are points in a region of about 7 mm inside from the end portion of the polarizing plate, and the short-side direction is arranged at intervals of about 20 mm, and the longitudinal direction is arranged at intervals of about 35 mm.

(warpage of the panel in a high temperature environment)

In the production of the above-mentioned laminated body, except that the alkali-free glass having a thickness of 0.4 mm was used, everything was the same, and the polarizing plate A/glass plate from the viewing side was obtained. / Laminate formed by the back side polarizing plate A. Furthermore, in any of the embodiments, the moisture content of the viewing-side polarizing plate was 1.13%, and the moisture content of the back-side polarizing plate was 0.6%, and the difference between the two was 0.53%.

The laminate was allowed to stand in an environment of a temperature of 85 ° C and a humidity of 5% RH for 250 hours. Then, the laminated body was placed on a measuring stand of a two-dimensional measuring instrument (manufactured by Nikon Co., Ltd., NEXIV (registered trademark) VMZ-R4540) so that the viewing-side polarizing plate A was on the upper side.

Then, in the same manner as the above-described measurement of the warpage of the panel in a normal temperature environment, the focus is focused on the surface of the measurement table, and the focus is focused on 25 points on the surface of the laminate, and the measurement is performed as a reference. The focus of the benchmark is the height. The difference between the maximum value and the minimum value of the height of the measurement point of 25 points is set as the amount of warpage. The results are shown in Table 1 below.

(Examples 2 to 4, Comparative Examples 1 to 3)

The combination of the viewing-side polarizing plate and the back-side polarizing plate was set as shown in Table 1 below, and the warpage of the panel in a normal temperature environment of each laminated body and the warpage of the panel in a high-temperature environment were measured. The results are summarized in Table 1 below. In Examples 1 to 4, the warpage of the liquid crystal panel was 0.4 mm or less in a normal temperature environment and a high temperature environment. In Comparative Examples 1 to 3, the warpage of the liquid crystal panel exceeded 0.4 mm regardless of the environment under a normal temperature environment or a high temperature environment.

(Examples 5 to 13)

The combination of the viewing-side polarizing plate and the back-side polarizing plate is as shown in the second table below, and when the warpage of the panel in a normal temperature environment and the warpage of the panel in a high-temperature environment are measured, Normal temperature environment and high temperature ring Under the circumstances, the size of the warpage of the liquid crystal panel is 0.4 mm or less.

[Industrial Applicability]

According to the set of the polarizing plate of the present invention, not only the warpage of the liquid crystal panel in a high temperature environment but also the warpage of the liquid crystal panel under a normal temperature environment can be reduced.

Claims (4)

A set of polarizing plates comprising a viewing side polarizing plate disposed on a viewing side of a liquid crystal cell and a back side polarizing plate disposed on a back side of the liquid crystal cell, wherein the viewing side polarizing plate is sequentially a first protective film, a first polarizer, and a second protective film; the back side polarizing plate includes a third protective film, a second polarizer, and a brightness enhancement film in this order; and the thickness of the viewing-side polarizing plate is subtracted from the thickness The difference in thickness of the back side polarizing plate is 13 μm or less, and the difference between the thickness of the first polarizer and the thickness of the second polarizer is more than 0 μm and 10 μm or less. The kit of polarizing plates according to claim 1, wherein the first polarizer has a thickness of 7 μm or more and 15 μm or less, and the second polarizer has a thickness of 4 μm or more and 12 μm or less. The kit of polarizing plates according to claim 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. A liquid crystal panel having a set of polarizing plates according to any one of claims 1 to 3.