TWI741008B - Polarizing plate set and liquid crystal panel - Google Patents

Abstract

The present invention provides a polarizing plate set capable of reducing warping of liquid crystal panel in high temperature environments.

The polarizing plate set comprises a front 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. When a laminate in which the front side polarizing plate and the back side polarizing plate are bonded to a glass plate such that the absorption axis of the front side polarizing plate and the absorption axis of the back side polarizing plate are orthogonal to each other is heated at 85℃ for 250 hours, and a tensile elastic modulus in the polarizing plate transmission axis direction at 85℃ and a tensile elastic modulus in the polarizing plate absorption axis direction at 85℃ are taken as Et and Ea, respectively, the protective film in the polarizing plate on the side where the laminate is warped in a concave shape satisfies Ea, Et/Ea ≧ 1.1.

Description

Polarizing plate set and LCD panel

The present invention relates to a set of polarizing plates and liquid crystal panels.

Liquid crystal display devices have features such as low power consumption, low-voltage operation, light weight, and thin profile, and can be used in various display elements. 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.

The method proposed in Japanese Patent Application Laid-Open No. 2013-37115 (Reference 1) is to make the polarizing film contained in the front side of the optical laminate more The thickness is 5 μm or more, and the polarizing film and the reflective polarizing film contained in the optical laminate arranged on the opposite side to the front side are laminated to prevent warping of the liquid crystal panel in a high temperature environment. These methods are effective when a liquid crystal cell with a large thickness (for example, 0.5 mm or more, and even 0.7 mm or more) and a reflective polarizing film with a large thickness (for example, 50 μm or more) are used. However, in addition to becoming thinner and weaker in rigidity of the components constituting the polarizing plate, it is not sufficient for thin liquid crystal cells to prevent the warpage of the liquid crystal panel in a high-temperature environment.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2013-37115 A

The purpose of the present invention is to provide a polarizing plate set, which can reduce the warpage of the liquid crystal panel in a high temperature environment.

[1] A set of polarizing plates, which has a front-side polarizing plate arranged on the observation side of a liquid crystal cell and a back-side polarizing plate arranged on the back of the liquid crystal cell, and the absorption axis of the front-side polarizing plate and the aforementioned The absorption axis of the back side polarizing plate is orthogonal to the laminated body obtained by bonding the front side polarizing plate and the back side polarizing plate to the glass plate. When heated at 85°C for 250 hours, the 85°C polarizing plate penetrates the axis direction When the tensile elastic modulus and the tensile elastic modulus in the direction of the polarizing plate absorption axis at 85°C are set to Et and Ea, respectively, the protective film of the polarizing plate on the side where the laminate is warped into a concave shape satisfies the following (1) .

Et/Ea≧1.1 (1)

[2] The set of polarizing plates according to [1], wherein the front side polarizing plate and the back side polarizing plate each have a polarizing plate formed of a polyvinyl alcohol-based resin film, and the thickness of the polarizing plate is equal It is 15 μm or less.

[3] The polarizing plate set according to [2], wherein the front-side polarizing plate is provided with a cured layer of an active energy ray curable resin composition on at least one surface of the polarizing plate.

[4] The polarizing plate set according to [2] or [3], wherein the front-side polarizing plate is provided with a protective film on one side of the polarizer and an active energy ray-curable resin on the other side The hardened layer of the composition.

[5] The polarizing plate set according to any one of [2] to [4], wherein the thickness of the polarizing plate provided in the front side polarizing plate and the polarizing plate provided in the back side polarizing plate The difference in thickness is less than 5μm.

[6] A liquid crystal panel comprising the polarizing plate set according to any one of [1] to [5], and a liquid crystal cell, wherein the thickness of the liquid crystal panel is 0.4 mm or less.

With the polarizing plate set of the present invention, the warpage of the liquid crystal panel in a high temperature environment can be reduced.

1‧‧‧hardened layer

2‧‧‧Polarizer

10、11‧‧‧Protective film

20、21‧‧‧Adhesive layer

30、31‧‧‧Adhesive layer

40‧‧‧Brightness improvement film

70‧‧‧Glass plate

80‧‧‧Measurement point

402‧‧‧Polarizer

100, 101, 400‧‧‧Front side polarizing plate

200, 201, 401‧‧‧Back side polarizing plate

300‧‧‧LCD unit

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

Fig. 2 is a cross-sectional view showing an example of the liquid crystal panel of the present invention.

Figure 3 is a schematic cross section of the evaluation sample after heat treatment.

Fig. 4 is a plan view showing the position after measuring the amount of warpage of the evaluation sample.

While referring to the drawings as appropriate, the polarizing plate set and liquid crystal panel of the present invention will be described. The polarizing plate set of the present invention has a front-side polarizing plate arranged on the observation side of the liquid crystal cell and a back-side polarizing plate arranged 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 polarizing plate set shown in FIG. 1(a) has a front-side polarizing plate 100 and a back-side polarizing plate 200. The front side polarizing plate 100 is formed by laminating a protective film 10 on one side of the polarizer 2 through the adhesive layer 30, and on the other side of the polarizer 2 is layered a cured layer 1 of an active energy ray-curable adhesive. In addition, an adhesive layer 20 is laminated on the hardened layer 1 described above.

The back side polarizing plate 200 has a protective film 11 laminated on one side of the polarizer 2 through the adhesive layer 31, and a brightness improvement film 40 laminated on the protective film 11 through the adhesive layer 21. In addition, an adhesive layer 20 is layered on the other area of the aforementioned polarizer 2.

In addition, the polarizing plate set shown in FIG. 1(b) has a front-side polarizing plate 101 and a back-side polarizing plate 201. The front side polarizing plate 101 is formed by laminating a protective film 10 on one side of the polarizer 2 through the adhesive layer 30, and on the other side of the polarizer 2 is layered a cured layer 1 of an active energy ray-curable adhesive. In addition, an adhesive layer 20 is laminated on the hardened layer 1 described above.

The back side polarizing plate 201 is formed by laminating the protective film 11 on one side of the polarizer 2 through the adhesive layer 31, and laminating the brightness improvement film 40 on the other side of the polarizer 2 through the adhesive layer 21. In addition, an adhesive layer 20 is laminated on the protective film 11 described above.

In the polarizing plate set shown in FIG. 1, the adhesive layer 20 may be, for example, an adhesive layer for laminating a polarizing plate on a liquid crystal cell.

In the polarizing plate set of the present invention, the front side polarizing plate and the back side polarizing plate are preferably provided with a protective film on only one side of the polarizer.

In the polarizing plate set of the present invention, the shapes of the front side polarizing plate and the back side polarizing plate are not particularly limited, and they may be rectangular. When the shape of the polarizing plate is rectangular, the absorption axis of the front side polarizing plate is preferably parallel to the short side, and the absorption axis of the back side polarizing plate is preferably parallel to the long side.

In the polarizing plate set of the present invention, when the laminate having the front side polarizing plate and the back side polarizing plate is heated, the tensile elastic modulus in the direction of the transmission axis of the polarizing plate at 85°C will be set at 85°C. When the tensile elastic modulus in the absorption axis direction of the polarizing plate is set to Et and Ea, respectively, the protective film of the polarizing plate having the side warped in a concave shape satisfies the following (1). The tensile modulus can be measured by the method described in the examples described later.

Et/Ea≧1.1 (1)

Et/Ea is more preferably 1.15 or more, and even more preferably 1.20 or more. Et/Ea may be 2.8 or less.

When the edge of the laminate is warped toward the front side of the polarizing plate, the polarizing plate on the side that is warped into a concave shape is the front side polarizing plate, and when the edge of the laminate is warped toward the back side of the polarizing plate, it is warped into a concave shape. The polarizing plate on the side is the back side polarizing plate. For details, refer to Figure 3 for description. FIG. 3 shows a schematic cross section of a laminate obtained by bonding the front-side polarizing plate 400 and the back-side polarizing plate 401 to the glass plate 70, respectively, after heat treatment. In Figure 3(a), the polarizing plate warped in a concave shape refers to the back side polarizing plate 401, and in Figure 3(b), the polarizing plate warped in a concave shape refers to the front side polarizing plate 400. The polarizing plate on the side that is warped into a concave shape may be a front-side polarizing plate or a back-side polarizing plate. In addition to the polarizers that have been stretched, most of the back-side polarizing plates have brightness improvement films that have also been stretched. Therefore, when the absorption axis of the back-side polarizing plate is the long side direction, the back-side polarizing plate The shrinking force during heating is often greater than that of the front side polarizing plate.

Although there are no special restrictions on the shape of the polarizing plate and the shape of the glass plate when adhering to the glass plate, a rectangular shape is preferred. In this case, the front side polarizing plate and the back side polarizing plate can be made the same size. When bonding the polarizing plate to the glass plate, the absorption axis of the front side polarizing plate and the absorption axis of the back side polarizing plate are bonded in an orthogonal manner. At this time, when the polarizing plate is rectangular, the absorption axis of the front side polarizing plate is preferably parallel to the short side, and the absorption axis of the back side polarizing plate is preferably parallel to the long side.

The thickness of the glass plate can be made, for example, 100 μm or more and 400 μm or less. When the thickness is in this range, it is easy to discriminate whether the front-side polarizing plate and the back-side polarizing plate are the polarizing plates that are warped in a concave shape.

The polarizing plate on the side that is warped into a concave shape can also have protective films on both sides of the polarizer. In this case, it is better that at least one of the protective films meets the formula (1), and the liquid crystal cell laminated in the distance polarizer is better It is more preferable for the protective film on the far side to satisfy the formula (1), and it is even more preferable for any protective film to satisfy the formula (1).

The tensile modulus Et in the direction of the penetration axis at 85°C is preferably 500 MPa or more and 10,000 MPa or less, and may also be 1,000 MPa or more and 8,000 MPa or less. The tensile modulus Ea in the direction of the absorption axis at 85°C is preferably 500 MPa or more and 10,000 MPa or less, and may be 1,000 MPa or more and 8,000 MPa or less.

The components constituting the polarizing plate set of the present invention will be explained.

(Polarizer)

The polarizer used in the present invention is usually produced through the following steps: the step of uniaxially stretching the polyvinyl alcohol-based resin film, and dyeing the polyvinyl alcohol-based resin film with a dichroic dye to make it adsorb dichroic The step of dyeing, the step of treating the polyvinyl alcohol resin film on which the dichroic dye has been adsorbed with an aqueous solution of boric acid, and the step of washing with water after the treatment of the aqueous solution of boric acid.

As the polyvinyl alcohol-based resin film, a polyvinyl acetate-based resin saponified can be used. In addition to polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl acetate resin includes copolymers of vinyl acetate and other copolymerizable monomers. Other monomers that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

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

The thing obtained by forming a polyvinyl alcohol-type resin into a film can be used as a raw material film of a polarizer. The method of forming a polyvinyl alcohol-based resin into a film can be formed by a known method. The thickness of the polyvinyl alcohol-based raw material film is preferably about 5 to 35 μm, and more preferably about 5 to 20 μm, considering that the thickness of the obtained polarizer is 15 μm or less. When the film thickness of the raw material film is 35 m or more, it is necessary to increase the stretching ratio during the production of the polarizer, and there is a tendency that the size shrinkage of the obtained polarizer becomes larger.

On the other hand, when the film thickness of the raw material film is 5 μm or less, the handleability at the time of applying stretching is lowered, and problems such as cutting are likely to occur during production.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before the dyeing of the dichroic dye, at the same time as the dyeing, or after the dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the boric acid treatment. In addition, uniaxial stretching may be performed in several stages of these processes.

In the case of uniaxial extension, uniaxial extension can be performed between rollers with different peripheral speeds, or a heated roller can be used for uniaxial extension. In addition, the uniaxial stretching may be dry stretching in the atmosphere, or wet stretching in which the polyvinyl alcohol-based resin film is stretched in an expanded state using a solvent. The stretching ratio is usually about 3 to 8 times.

The method of dyeing the polyvinyl alcohol-based resin film with a dichroic dye may be a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye, for example. Specifically, iodine or a dichroic dye can be used as a dichroic dye. In addition, the polyvinyl alcohol-based resin film system is preferably subjected to an immersion treatment in water before the dyeing treatment.

When iodine is used as a dichroic dye, usually a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide for dyeing can be adopted. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of the water system. In addition, the content of potassium iodide per 100 parts by weight of water is usually about 0.5 to 20 parts by weight. The temperature of the aqueous solution used in dyeing is usually about 20 to 40°C.

Furthermore, the time for immersion in the aqueous solution (dyeing time) is usually about 20 to 1,800 seconds.

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

The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid.

The amount of boric acid in the aqueous solution containing boric acid is usually about 2 to 15 parts by weight per 100 parts by weight of water, and preferably 5 to 12 parts by weight. When iodine is used as a 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 per 100 parts by weight of water, and preferably 5 to 12 parts by weight. The immersion time in an aqueous solution containing boric acid 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 above 50°C, preferably 50 to 85°C, and more preferably 60 to 80°C.

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

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

After drying, the moisture content of the polarizer can be reduced to a practical level. The moisture content is usually 5 to 20% by weight, and preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the polarizer may lose flexibility, and the polarizer may be damaged or cracked after drying.

In addition, when the moisture content is higher than 20% by weight, the thermal stability of the polarizer may deteriorate.

In addition, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol resin film in the manufacturing process of the polarizer can be carried out in accordance with the method described in, for example, Japanese Patent Laid-Open No. 2012-159778. In the method described in this document, a polyvinyl alcohol-based resin layer is formed as a polarizer by coating a polyvinyl alcohol-based resin on a base film.

Reducing the shrinkage force of the polarizer itself is also effective for reducing warpage in high temperature environments. The thickness of the polarizer with the front side polarizing plate and the back side polarizing plate is preferably 15μm or less, and more than 4 to 13μm. Better, and more preferably 5 to 10 μm.

The difference between the thickness of the polarizer included in the front-side polarizing plate and the thickness of the polarizer included in the back-side polarizing plate is preferably 5 m or less, and may be 3 m or less. When the protective film of the polarizing plate on the side that is warped into a concave shape satisfies the formula (1), the thickness difference of the polarizer can be reduced as described above, and the influence on the warpage of the liquid crystal panel under a high temperature environment becomes smaller.

(Protective film)

The protective film is composed of a resin film, and may be composed of a transparent resin film. In particular, it is preferably composed of materials with excellent transparency, mechanical strength, thermal stability, and moisture shielding properties. The transparent resin film in this specification refers to a resin film with a monomer transmittance of 80% or more in the visible light range.

When the two-area protective film of the polarizer is layered, the protective film may be the same or different from each other. In addition, the protective film in the front-side polarizing plate and the protective film in the back-side polarizing plate may be the same or different from each other.

The resin forming the protective film is not particularly limited. Examples include: methyl methacrylate resins, polyolefin resins, cyclic olefin resins, polyvinyl chloride resins, cellulose resins, and styrene resins. , Acrylonitrile/butadiene/styrene resin, acrylonitrile/styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate Ester-based resins, modified polyphenylene ether-based resins, polybutylene terephthalate-based resins, polyethylene terephthalate-based resins, polyether-based resins, polyether-based resins, and polyarylate-based resins , Polyimide-based resin and polyimide-based resin film formed.

These resins can be used alone or in combination of two or more kinds. Moreover, these resins can also be used after any suitable polymer modification. Examples of such polymer modification include: copolymerization, crosslinking, molecular end modification, stereoregularity control, and the inclusion of heterogeneous polymers that react with each other. The mixing of time, etc.

Among these, the material of the protective film is preferably methyl methacrylate resin, polyethylene terephthalate resin, polyolefin resin, or cellulose resin. The polyolefin resin referred to here includes chain polyolefin resin and cyclic polyolefin resin.

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

This methyl methacrylate resin is usually obtained by polymerizing a monofunctional monomer having methyl methacrylate as a main component in the presence of a radical polymerization initiator. During polymerization, it may coexist with a multifunctional monomer or a chain transfer agent as needed.

The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and methyl methacrylate. Methacrylates other than methyl methacrylate such as benzyl acrylate, 2-ethylhexyl methacrylate and 2-hydroxy ethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, Acrylates such as cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; 2-(hydroxymethyl)methyl acrylate, 3-(hydroxyethyl) ) Hydroxyalkyl acrylates such as methyl acrylate, ethyl 2-(hydroxymeth)acrylate and butyl 2-(hydroxymeth)acrylate; unsaturated acids such as methacrylic acid and acrylic acid; chlorostyrene and bromobenzene Halogenated styrenes such as ethylene; substituted styrenes such as vinyl toluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; And unsaturated amides such as phenyl maleimide and cyclohexyl maleimide. These monomers may be used alone or in combination of two or more kinds.

The polyfunctional monomers that can be copolymerized with methyl methacrylate are not particularly limited. Examples include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylenediacrylate. Ethylene glycol such as alcohol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate and tetradecaethylene glycol di(meth)acrylate, etc. The two terminal hydroxyl groups of its oligomer are esterified with acrylic acid or methacrylate; the two terminal hydroxyl groups of propylene glycol or its oligomer are esterified with acrylic acid or methacrylate; neopentyl glycol di(meth)acrylate, The hydroxyl groups of diols such as hexanediol di(meth)acrylate and butanediol di(meth)acrylate are esterified with acrylic acid or methacrylate; alkylene oxide addition of bisphenol A and bisphenol A The two terminal hydroxyl groups of these halogen substitutions are esterified with acrylic acid or methacrylic acid; the polyols such as trimethylolpropane and isoprene erythritol are esterified with acrylic acid or methacrylic acid, and these polyhydric alcohols are esterified with acrylic acid or methacrylic acid. The terminal hydroxyl group of alcohol is added by ring opening of the epoxy group of dehydrated glyceryl acrylate or dehydrated methacrylate; succinic acid, adipic acid, terephthalic acid, phthalic acid, etc. Dibasic acids such as halogen substituted products and these alkylene oxide adducts, etc. are added by ring opening of the epoxy group of dehydrated glyceryl acrylate or dehydrated glyceryl methacrylate; (meth)acrylic acid allyl Esters; and aromatic divinyl compounds such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

Further, the methyl methacrylate-based resin may be modified by reaction between functional groups copolymerized with the resin. Examples of this reaction include: intra-polymer chain demethanol condensation reaction between the methyl acrylate group of methyl acrylate and the hydroxyl group of methyl 2-(hydroxymeth)acrylate, or the carboxyl group of acrylic acid and methyl 2-(hydroxymethyl)acrylate The dehydrogenation condensation reaction within the polymer chain of the hydroxyl group of the ester, etc.

Polyethylene terephthalate resin means that more than 80 mol (mol)% of the repeating unit is a resin composed of ethylene terephthalate, and it may also contain other dicarboxylic acid components and diols. Element. Other dicarboxylic acid components are not particularly limited. Examples include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxybenzene Base) ethane, adipic acid, sebacic acid and 1,4-dicarboxycyclohexane, etc.

Other glycol components are not particularly limited. Examples include propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, and polyethylene glycol. Alcohol, polypropylene glycol and polybutylene glycol, etc.

These dicarboxylic acid components or diol components can be used in combination of two or more types as necessary. In addition, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-hydroxyethoxybenzoic acid may be used in combination. In addition, as other copolymerization components, a dicarboxylic acid component or a diol component containing a small amount of amide bonds, urethane bonds, ether bonds, or carbonate bonds can be used.

The method for producing polyethylene terephthalate resin can be a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as necessary) to make p-benzene Dialkyl dicarboxylic acid and ethylene glycol (and other dialkyl esters of dicarboxylic acid or other diols as required) are subjected to a method of polycondensation after transesterification, and terephthalic acid (and as required Other dicarboxylic acid) glycol esters (and other glycol esters if necessary) are polycondensed in the presence of a catalyst. In addition, if necessary, solid-phase polymerization may be performed to increase the molecular weight or reduce the low-molecular-weight components.

The cyclic polyolefin resin is obtained by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst. The use of such a cyclic polyolefin-based resin is preferable because it is easy to obtain a protective film having a predetermined retardation value described later.

Cyclic polyolefin resins include, for example, norbornene or its derivatives obtained by Diels-Alder reaction of cyclopentadiene and olefins or (meth)acrylic acid or its esters as a monomer for easy ring opening. The resin obtained by metathesis polymerization and then hydrogenation; the tetracyclododecene or its derivatives obtained by the Diels-Alder reaction of dicyclopentadiene with olefins or (meth)acrylic acid or its esters is used as A resin obtained by ring-opening metathesis polymerization of monomers followed by hydrogenation; at least two monomers selected from norbornene, tetracyclododecene, derivatives of these, and other cyclic olefin monomers are similarly processed The resin obtained by ring-opening metathesis copolymerization and then hydrogenation; such as norbornene, tetracyclododecene or their derivatives, such as cyclic olefins and chain olefins and/or aromatic compounds with vinyl groups. Resin etc. obtained by copolymerization.

Typical examples of chain polyolefin resins are polyethylene resins and polypropylene resins. Among them, a homopolymer of propylene, or propylene as the main body and copolymerizable with comonomers, such as ethylene, are copolymerized in a ratio of 1 to 20% by weight, preferably 3 to 10% by weight. The copolymer is suitable.

The polyolefin resin may contain an alicyclic saturated hydrocarbon resin. By containing 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 relative to the polyolefin resin, and the 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 cannot be sufficiently obtained. On the other hand, if the content exceeds 30% by weight, the alicyclic saturated resin may bleed from the protective film over time. Concerns about hydrocarbon resins.

Cellulose resin refers to some or all of the hydrogen atoms in the hydroxyl group of cellulose obtained from raw material cellulose such as cotton linter or wood pulp (hardwood pulp, conifer pulp) through acetyl, acryl and/or butyryl Substituted cellulose organic acid ester or cellulose mixed organic acid ester. For example, those formed from cellulose acetate, propionate, butyrate, and mixed esters of these can be cited. Among them, triacetyl cellulose film, diacetyl cellulose film, cellulose acetate propionate film, and cellulose acetate butyrate film are preferred.

The method of making the second protective film of methyl methacrylate resin, polyethylene terephthalate resin, polyolefin resin and cellulose resin into the polarizer, as long as it is suitable to choose and match each other The resin method is sufficient, and there is no particular limitation. For example, it is possible to use a solvent casting method in which the resin that has been dissolved in a solvent is cast on a metal belt or drum, and the solvent is dried and removed to obtain a film, and the resin is heated to a temperature above its melting temperature and kneaded, then extruded from a die and Melt extrusion method to obtain a film by cooling. In this melt extrusion method, the extrusion of a single-layer film or the simultaneous extrusion of a multi-layer film may be used.

Commercial products can be easily obtained by using a film as a protective film. For methyl methacrylate resin films, the trade names are Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrylite (registered trademark), and ACRYPREN. (Registered trademark) (above, manufactured by Mitsubishi Rayon Co. Ltd), Delaglas (registered trademark) (manufactured by Asahi Kasei Co., Ltd.), Paraglas (registered trademark), Comograss (registered trademark) (above, Kuraray Co., Ltd.) and Acryviewa (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.), etc. In the case of polyolefin-based resin films, the trade names may be Zeonor (registered trademark) (Japan Zeon Co., Ltd.), Arton (registered trademark) (JSR Co., Ltd.), and the like. If it is a polyethylene terephthalate resin, the trade names are Nova Clear (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET board (manufactured by Teijin Chemical Co., Ltd.), etc. . If it is a polypropylene resin film, the trade names are FILMAX CPP film (manufactured by FILMAX), SUNTOX (registered trademark) (manufactured by SUN/TOX Co., Ltd.), Tohcello (registered trademark) (Tocello Co., Ltd.) Toyobo Piren Film (registered trademark) (manufactured by Toyobo Co., Ltd.), Torayfan (registered trademark) (manufactured by Toray Film Processing Co., Ltd.), Japan Poriesu (manufactured by Japan Poriesu Co., Ltd.), and Taihe (registered trademark) FC (manufactured by Futamura Chemical Co., Ltd.), etc. In addition, if it is a cellulose resin film, the trade names are Fujitac (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC Film KC (manufactured by Konica Minolta Co., Ltd.), etc. .

The protective film and protective film used in the present invention can impart anti-glare properties (Haze, haze). The method of imparting anti-glare properties is not particularly limited. For example, a method of mixing inorganic particles or organic particles with the aforementioned raw material resin and forming a film, using the aforementioned multilayer extrusion, and a resin that has mixed particles on one side can be used. A method of forming a two-layer film with the other resin that is not mixed with fine particles, or a method of forming a three-layer film with the resin of mixed particles as the outer side, and mixing inorganic fine particles or organic fine particles in a curable adhesive resin. The finished coating liquid is applied to one side of the film, and the adhesive resin is cured to provide an anti-glare layer.

In addition, the protective film may contain additives as needed. Examples of additives include slip agents, anti-caking agents, heat stabilizers, antioxidants, antistatic agents, light fastness agents, impact resistance improvers, and the like.

Generally, in terms of strength or usability, the thickness of the protective film is about 1 to 50 μm, and preferably 10 to 40 μm.

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

On the protective film of the polarizing plate on the front side, functional layers such as a conductive layer, a hard coat layer, and a low reflection layer can be additionally provided. In addition, the binder resin constituting the anti-glare layer may also be a resin composition having such functions.

The protective film that satisfies the formula (1) may be produced by stretching a resin film, for example. The stretching method is not particularly limited, and it may be a uniaxially stretched film obtained by lateral stretching after film formation, a biaxially stretched film obtained by longitudinal stretching and then lateral stretching after film formation, and the like. The stretch magnification can be made 1.01 or more and 5.00 or less, and can also be 1.01 or more and 3.00 or less.

(Brightness improvement film)

The back side polarizing plate preferably has a brightness improving film on the far side from the liquid crystal cell in the polarizer. The thickness of the brightness improving film is preferably 35 μm or less, and more preferably 30 μm or less.

The brightness improvement film is used as a polarization conversion element having a function of separating light emitted from a light source (backlight) into penetrating polarized light and reflected polarized light or scattered polarized light. Such a brightness improvement film can utilize the re-returned light from the back light of reflected polarized light or scattered polarized light to improve the emission efficiency of linearly polarized light.

Examples of the brightness improving film include anisotropic reflective polarizers. Examples of the anisotropic reflective polarizer include an anisotropic multiple film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. Examples of the anisotropic multiple film include the trade name "APF" manufactured by 3M Corporation. In addition, the anisotropic reflective polarizer includes a composite of a cholesteric liquid crystal layer and a λ/4 plate. As such a compound, the trade name "PCF" manufactured by Nitto Denko Co., Ltd. can be cited. In addition, the anisotropic reflective polarizer can be a reflective grating polarizer. Examples of the reflective grating polarizer include metal lattice reflective polarizers that can emit reflected polarized light even in the visible light region by applying microfabrication to metal. Among them, a brightness improvement film formed of an anisotropic multiple thin film is preferred.

It is also possible to form a functional layer on the surface opposite to the adhesion surface of the polarizing plate of the brightness improving film. The functional layer includes, for example, a hard coat layer, an anti-glare layer, a light diffusion layer, a retardation layer having a retardation value of 1/4 wavelength, etc., which can improve the adhesion with the backlight band or display The uniformity of the image.

(Adhesive layer)

An adhesive layer can also be laminated on the surface of the polarizing plate. The polarizing plate can be adhered to the liquid crystal cell through the adhesive layer. The adhesive layer 20 in Figure 1 corresponds to this layer.

The thickness of the adhesive layer formed by the adhesive is preferably 5 to 25 μm, and more preferably 10 to 25 μm.

The adhesive layer for bonding the front-side polarizing plate to the liquid crystal cell and the adhesive layer for bonding the back-side polarizing plate to the liquid crystal cell may be the same or different.

In addition, the brightness improvement film and the protective film or the polarizer can also be laminated by the adhesive layer. The adhesive layer 21 in Figure 1 corresponds to this layer. The thickness of the adhesive layer formed by the adhesive is preferably 1 to 20 μm, and more preferably 1 to 10 μm.

The adhesive forming the adhesive layer can be suitably selected and used: for example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate/vinyl chloride copolymer, Modified polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber, and other rubber-based polymers as matrix polymers. In particular, the adhesive is preferably one that is excellent in optical transparency, exhibits moderate wettability, cohesiveness, adhesive properties, weather resistance, heat resistance, and the like.

Various other additives can also be formulated in the adhesive. Examples of additives include silane coupling agents and antistatic agents.

(Adhesive layer)

The lamination of the protective film and the polarizer or the lamination of the brightness improvement film and the polarizer can be performed, for example, by using an adhesive to integrate them. The thickness of the adhesive layer formed by the adhesive is preferably 0.01 to 35 μm, more preferably 0.01 to 10 μm, and more preferably 0.01 to 5 μm. As long as it is within this range, floating or peeling between the protective film or the brightness improving film and the polarizer can be prevented, and an adhesive force that is practically problem-free can be obtained.

Adhesives include, for example, solvent-based adhesives, emulsion-type adhesives, pressure-sensitive adhesives, remoisturizing adhesives, polycondensation-type adhesives, solvent-free adhesives, film-like adhesives, and hot-melt adhesives. Furthermore, if necessary, an adhesive layer may be provided through the anchor coating.

Preferable adhesives include water-soluble adhesives. This water-soluble adhesive includes, for example, a polyvinyl alcohol-based resin as a main component. As the water-soluble adhesive, a commercially available one may be used, or a commercially available adhesive mixed with a solvent or an additive may be used. Commercially available polyvinyl alcohol-based resins of water-soluble adhesives include KL-318 manufactured by Kuraray Co., Ltd. and the like.

The water-soluble adhesive may contain a crosslinking agent. The types of crosslinking agents are preferably amine compounds, aldehyde compounds, trimethylol compounds, epoxy compounds, isocyanate compounds, and polyvalent metal salts, and epoxy compounds are particularly preferred. Commercial products of the crosslinking agent include, for example, glyoxal or Sumirez resin 650 (30) manufactured by Taoka Chemical Industry Co., Ltd., and the like.

In addition, another preferable adhesive includes an active energy ray curable adhesive formed of a resin composition that is cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive 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. The polymerizable compound may include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, or oligomers derived from photopolymerizable monomers. . The photopolymerization initiator may include a substance containing active species such as free radicals, cations, or anions generated by irradiation of active energy rays such as ultraviolet rays. The active energy ray curable adhesive containing a polymerizable compound and a photopolymerization initiator is preferably one containing a photocurable epoxy-based monomer and a photocationic polymerization initiator.

When an active energy ray curable adhesive is used, after bonding the polarizer and the protective film, a drying step may be performed as necessary, and then a step of curing the active energy ray curable adhesive by irradiation with active energy rays is performed. Although there are no special restrictions on the light source of the active energy line, it is better to have ultraviolet light with a luminous distribution below the wavelength of 400nm. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, and microwaves can be used. Exciting mercury lamps, metal halide lamps, etc.

The above-mentioned adhesive may also contain additives. Examples of additives include ion trapping agents, antioxidants, chain transfer agents, sensitizers, adhesive excipients, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, and the like.

(Cured layer of active energy ray-curable resin composition)

The hardened layer of the active energy ray hardening resin composition can be used as a protective layer to protect the surface of the polarizer. Compared with general protective films, the cured layer of the active energy ray-curable resin composition can be thinner, so it is effective for thinning the polarizing plate. The cured layer 1 of the active energy ray-curable resin composition in Fig. 1 corresponds to this.

In the polarizing plate set of the present invention, the polarizing plate (especially the front side polarizing plate) is preferably provided with a hardened layer of active energy ray curable resin composition on at least one side of the polarizer, and it is preferred that the polarizer is close to the liquid crystal It is more preferable to have a hardened layer of active energy ray hardening resin composition on the side of the unit. In this case, since the distance between the polarizer and the liquid crystal cell can be reduced, the force of deformation of the liquid crystal cell accompanying the shrinkage of the polarizer is reduced, and the influence on the warpage of the liquid crystal panel in a high temperature environment is smaller. In this regard, the distance from the surface of the polarizer of the front-side polarizer near the liquid crystal cell to the surface of the liquid crystal cell near the surface of the polarizer of the front-side polarizer is preferably 30 μm or less, for example, It is more preferably less than 25μm.

The thickness of the cured layer of the active energy ray-curable resin composition is preferably 0.01 to 20 μm, more preferably 0.01 to 10 μm, and even more preferably 0.01 to 5 μm.

The active energy ray-curable resin composition forming the hardened layer of the active energy ray-curable resin composition can be the same as the above-mentioned active energy ray-curable adhesive. The active energy ray curable resin composition and the active energy ray curable adhesive may be the same or different from each other.

(Method of manufacturing polarizing plate)

The members described above can be laminated to each other through an adhesive layer or an adhesive layer, for example. In addition, a method of manufacturing a polarizing plate using a release film can also be adopted.

Hereinafter, the method of manufacturing the front-side polarizing plate and the back-side polarizing plate of the polarizing plate of the present invention will be explained by taking the set of polarizing plates shown in Fig. 1(a) as an example.

(Method of manufacturing front-side polarizing plate)

The release film, the polarizer 2 and the protective film 10 are prepared, and the protective film is adhered to one side of the polarizer through the adhesive, and the release film is laminated on the other side of the polarizer through the volatile liquid. Of course, the adhesion of the protective film and the polarizer and the stacking of the release film and the polarizer can also be performed in sequence.

Examples of volatile liquids include water or a mixture of water and hydrophilic liquids. The hydrophilic liquid system preferably does not remain after the heat treatment in the second step. Examples include methanol, ethanol, 1-butanol, tetrahydrofuran, acetone, acetonitrile, N,N-dimethylformamide, and dimethylformamide. Glycine, formic acid, acetic acid, etc. Antistatic agents and other additives can also be added to volatile liquids.

The resin forming the release film is not particularly limited. Examples include: methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, and styrene resin. , Acrylonitrile/butadiene/styrene resin, acrylonitrile/styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate Ester-based resins, modified polyphenylene ether-based resins, polybutylene terephthalate-based resins, polyethylene terephthalate-based resins, polyether-based resins, polyether-based resins, and polyarylate-based resins , Polyimide-based resin and polyimide-based resin film formed.

When bonding the protective film to the polarizer, in order to improve the adhesion, the bonding surface of the polarizer and/or the protective film can be treated with plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment Easy to handle. In addition, the same treatment as the protective film on the release film can be used to improve the wettability of the volatile liquid.

When an active energy ray-curable adhesive is used as an adhesive, the adhesive is cured by irradiating the active energy ray, and then heat treatment is performed to volatilize and remove the volatile liquid. When the water-based adhesive is used as the adhesive, heat treatment is performed to bond the polarizer and the protective film while volatilizing and removing the volatile liquid. In terms of simplifying the steps, it is better to use an aqueous adhesive.

The drying temperature is preferably 30 to 90°C. If the temperature is lower than 30°C, the drying time may be longer and the appearance may be poor. In addition, if the drying temperature exceeds 90°C, there may be a concern that the polarization performance of the polarizer may be deteriorated due to heat. The drying time can be set to about 10 to 1,000 seconds, and from the viewpoint of productivity, 60 to 750 seconds is preferable, and 150 to 600 seconds is more preferable.

By laminating the release film through the layer formed by the volatile liquid on the polarizer, the heating temperature in this step can be increased to, for example, more than 60°C and about 90°C or less. That is, setting the heating temperature to a higher temperature not only prevents cracking of the polarizer, but also reduces the shrinkage of the polarizer due to the high-temperature heating, thereby obtaining a single-sided protective polarizer with high dimensional stability. By reducing the shrinkage rate of the single-sided protective polarizing plate, when the polarizing plate is used to manufacture a liquid crystal panel, the warpage of the liquid crystal panel can be further reduced.

In order to volatilize the volatile liquid used in the laminate of the polarizer and the release film by heating, the moisture permeability of at least one of the protective film and the release film should be 400g/m ² ‧24 hours or more, and 420g/m ^2. More than 24 hours is better. When the water vapor permeability is in this range, the volatile liquid can be efficiently volatilized and removed in the second step, so that the productivity can be improved.

The active energy ray curable resin composition is coated on the base film so that the cured layer 1 of the active energy ray curable resin composition is laminated on the polarizer 2. Next, the release film is peeled and removed from the single-sided protective polarizing plate, and the polarizer 2 in the single-sided protective polarizing plate and the active energy ray curable resin composition on the base film are laminated. The active energy ray-curable resin composition is cured by irradiating active energy rays to form the cured layer 1. The base film is peeled and removed, and the adhesive layer 20 is formed on the hardened layer 1 to obtain the hardened layer 1/polarizer 2/adhesive layer 30/protection composed of the adhesive layer 20/active energy ray curable resin composition The film 10 is formed on the front side polarizing plate.

(Manufacturing method of back side polarizing plate)

Prepare the release film, the polarizer 2 and the protective film 11 by the same method as the manufacturing method of the front side polarizing plate. The protective film is adhered to one side of the polarizer 2 through the adhesive, and the release film is passed through the volatile liquid. Laminated on the other side of the polarizer 2. After adhering the polarizer 2 and the protective film 11 to remove the volatile liquid, the release film is peeled off to obtain a single-sided protective polarizing plate.

By letting the brightness improving film pass through the adhesive layer to be laminated on the protective film in the single-sided protective polarizing plate, and laminating the adhesive layer 20 on the polarizer 2, the adhesive layer 20/polarizer 2/adhesive The back side polarizing plate formed by the agent layer 31/protective film 11/adhesive agent layer 21/brightness improving film 40.

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

(Method of manufacturing liquid crystal panel)

The liquid crystal panel can be obtained by bonding the polarizing plate set of the present invention on both sides of the liquid crystal cell respectively. The adhesion is preferably performed separately through the adhesive layer of the front side polarizing plate and through the adhesive layer of the back side polarizing plate. In addition, it is preferable that the front side polarizing plate system is laminated on the observation side of the liquid crystal cell, and the back side polarizing plate system is laminated on the back surface of the liquid crystal cell. The liquid crystal panel of the present invention can be applied to liquid crystal display devices. The front-side polarizing plate is preferably bonded so that its absorption axis is approximately parallel to the short-side direction of the liquid crystal cell, and the back-side polarizing plate is bonded so that its absorption axis is approximately parallel to the long-side direction of the liquid crystal cell. good. In this specification, "approximately parallel" means that, for example, the angle formed is 0±5°, and preferably 0±1°.

The liquid crystal cell has two cell substrates and a liquid crystal layer sandwiched between the substrates. The unit substrate is usually made of glass, but it can also be a plastic substrate. In addition, the liquid crystal cell itself used in the liquid crystal panel of the present invention can also be made of various materials used in this field. With the polarizing plate set of the present invention, even if the thickness of the liquid crystal cell is 0.4 mm or less, the warpage can be significantly reduced. The thickness of the liquid crystal cell in the present invention includes the thickness of the liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer.

[Example]

Hereinafter, the present invention will be described in more detail with examples, but the present invention is not limited to the scope of these examples. In the examples, it means the content or usage amount in% and parts, and it is based on weight unless otherwise specified. In addition, the evaluation method used in the examples is as follows.

(1) Thickness:

It is measured using a digital micrometer MH-15M manufactured by Nikon Co., Ltd.

(2) Tensile elasticity

A test piece with a width of 15 mm and a length of 150 mm was cut out from the film. Next, the upper and lower clamps of a tensile testing machine [AUTOGRAPH (registered trademark) AG-1S testing machine manufactured by Shimadzu Corporation] equipped with a constant temperature bath were used to clamp the long sides of the test piece so that the gap between the clamps became 100 mm. The two ends of the direction were stretched at a tensile speed of 50 mm/min in an environment of 85°C to create a stress-strain curve, and the tensile modulus of elasticity at 85°C was calculated.

(3) Water permeability

The water vapor transmission rate is measured according to JIS Z 0208. The temperature and humidity conditions are set to 40 degrees and 90% RH.

(4) Judgment of the polarizing plate on the side that is warped into a concave shape and measurement of the amount of warpage in a high-temperature environment

A sample for evaluation with a back-side polarizing plate/glass plate/front-side polarizing plate is allowed to stand in an environment of 85°C for 250 hours, and the front side polarizing plate is placed on the upper side for measurement by a binary measuring device On stage. For the binary measuring device, "NEXIV (registered trademark) VMR-12072" manufactured by Nikon Co., Ltd. was used. Next, focus on the surface of the measurement table, and use this as a reference, and focus on each of 25 points on the evaluation sample surface, and measure the height from the focus as the reference. The difference between the maximum value and the minimum value of the height of the 25 measurement points was used as the amount of warpage, and the warpage of the edge warpage of the evaluation sample on the front side polarizer side was set as positive warpage, and the back side polarizer side was evaluated The warpage of the edge warpage of the sample is set as negative warpage. In the case of positive warpage, the polarizing plate on the side that is warped into a concave shape is the front side polarizing plate, and in the case of negative warpage, the polarizing plate on the side that is warped into a concave shape is the back side polarizing plate.

Specifically, the point 80 shown in Fig. 4 is taken as the measurement point. The 25 points shown in Fig. 4 are points in the area 7 mm inside the edge of the polarizing plate. The short side direction is set at an interval of about 20 mm, and the long side direction is set at an interval of about 35 mm. In addition, reference numeral 402 in Figure 4 denotes a polarizing plate, and 70 denotes a glass plate.

[Production Example 1] Production of Polarizer

A polyvinyl alcohol film with a thickness of 20μm (average degree of polymerization is about 2,400, saponification degree of 99.9 mol% or more) is uniaxially stretched to about 4 times by dry stretching, and it is immersed at 40°C while keeping it tight. After 40 seconds in pure water, it was immersed in an aqueous solution with a weight ratio of iodine/potassium iodide/water of 0.052/5.7/100 at 28°C for 30 seconds for dyeing. Then, it was immersed in an aqueous solution with a weight ratio of potassium iodide/boric acid/water of 11.0/6.2/100 at 70°C for 120 seconds. Then, after washing with pure water at 8°C for 15 seconds, maintaining a tension of 300N, drying at 60°C for 50 seconds, and then drying at 75°C for 20 seconds, the polyvinyl alcohol film has adsorbed oriented iodine. Polarizer with a thickness of 7μm.

[Production example 2] Production of water-based adhesive

With respect to 100 parts by weight of water, 3 parts by weight of carboxyl modified polyvinyl alcohol (trade name "KL-318" available from Kuraray Co., Ltd.) is dissolved, and polyamide, which is a water-soluble epoxy resin, is added to this aqueous solution. Epoxy-based additives (trade name "Sumirez Resin (registered trademark) 650(30)", 30% by weight solid content aqueous solution purchased from Taoka Chemical Industry Co., Ltd.) 1.5 parts by weight, were prepared into a water-based adhesive.

[Manufacturing Example 3] Active energy ray curable resin composition

As a polymer compound, 50 parts by mass of oxetane compound (bifunctional) (OXT221), 35 parts by mass of alicyclic epoxy compound (bifunctional) (CEL2021P), and aromatic epoxy compound (trifunctional) (TECHMORE 15 parts by mass of VG3101L and 2.25 parts by mass of triarylsulfonium hexafluorophosphate as a photocationic polymerization initiator were mixed to obtain an active energy ray curable resin composition.

[Protective film A, B, C, D, E and release film F, G]

Prepare the following 5 types of protective films and 2 types of release films.

Protective film A: 25KCHCN-TC. A saponified film made by Toppan Printing Co., Ltd. with a hard-coated tri-acetyl cellulose film. The thickness is 32μm, and the moisture permeability is 450g/m ² ‧24 hours.

Protective film B: ZT12. Cyclic polyolefin resin film made by Japan's ZEON Co., Ltd. The thickness is 20μm, and it is made by stretching on one axis in the horizontal direction.

Protective film C: Zero Tack (registered trademark). KONICA MINOLTA Co., Ltd.'s triacetin-based cellulose membrane is saponified. The thickness is 20 μm.

Protective film D: KC2UAW. KONICA MINOLTA Co., Ltd.'s triacetin-based cellulose membrane is saponified. The thickness is 25 μm.

Protective film E: ZEONOR (registered trademark). Cyclic polyolefin resin film made by Japan's ZEON Co., Ltd. The thickness is 20 μm.

Release film F: TD80UL. A triacetyl cellulose film made by Fujifilm Co., Ltd. The thickness is 80μm, and the moisture permeability is 502g/m ² ‧24 hours.

Release film G: Polymethyl methacrylate film manufactured by Sumitomo Chemical Co., Ltd. The thickness is 80μm, and the moisture permeability is 50g/m ² ‧24 hours.

[Example 1]

[Production of front side polarizing plate A]

While continuously conveying the polarizer obtained in Manufacturing Example 1, the protective film A was continuously unwound from the roll of the protective film A, and the release film G was continuously rolled up from the roll of the release film G. Next, the water-based adhesive is injected between the polarizer and the protective film A, and pure water is also injected between the polarizer and the release film G, and the protective film A/water-based adhesive/polarizer/pure water/ The laminated film formed by the peeling film G is peeled. Next, the laminated film is transported, and the water-based adhesive is dried by a heating treatment at 80°C for 300 seconds in a drying oven, and the pure water between the polarizer and the release film G is volatilized and removed to obtain a single side with a release film Protect the polarizer. The peeling film G was peeled off from the single-sided protective polarizing plate with a peeling film, and the single-sided protective polarizing plate was obtained.

On the other hand, on one side of a cyclic polyolefin resin film [ZEONOR (registered trademark), manufactured by Japan ZEON Co., Ltd.] with a thickness of 50 μm, the active energy ray-curable resin composition prepared in Manufacturing Example 3 was applied to make The film thickness after curing becomes approximately 3 μm. The above-mentioned single-sided protective polarizer polarizer is adhered to the coated surface, and an ultraviolet irradiation device is used (the irradiation lamp is "D VALVE" manufactured by Fusion UV Systems) to achieve a cumulative light intensity of 200 mJ/cm ² from 280 to 320 nm. Ultraviolet rays are irradiated from the side of the cyclic polyolefin resin film to cure the active energy ray-curable resin composition. The cyclic polyolefin resin film is peeled off, and corona treatment is applied to the cured layer of the active energy ray-curable resin composition. The adhesive layer [trade name "# KT" manufactured by Lintec Co., Ltd.). The thickness is 20 μm. 〕 Bonded to the hardened layer. In this way, the front-side polarizing plate A was made up of protective film A/water-based adhesive layer/polarizer/cured layer of active energy ray curable resin composition/adhesive layer.

[Production of Polarizing Plate B on the Back Side]

The polarizer obtained in Manufacturing Example 1 was continuously conveyed, the protective film B was continuously unwound from the roll of the protective film B, and the release film F was continuously rolled up from the roll of the release film F. Next, the water-based adhesive is injected between the polarizer and the corona-treated protective film B, and pure water is poured between the polarizer and the release film F, and the protective film B/water-based adhesive/polarizer is formed by a bonding roller. /Pure water/Laminated film formed by release film F. Next, the laminated film is transported, and the water-based adhesive is dried by a heating treatment at 80°C for 300 seconds in a drying oven, and the pure water between the polarizer and the release film F is volatilized and removed to obtain a single side with a release film Protect the polarizer. The peeling film F was peeled from the single-sided protective polarizing plate with a peeling film, and the single-sided protective polarizing plate was obtained.

The adhesive layer [trade name "# L2" manufactured by Lintec Co., Ltd.). The thickness is 5 μm. ] It is bonded to the protective film B of the aforementioned single-sided protective polarizing plate, and a brightness improvement film [trade name "Advanced Polarized Film manufactured by 3M", version 3) is bonded to the adhesive layer. The thickness is 26 μm. ]). Then, the adhesive layer [trade name "# KT" manufactured by Lintec Co., Ltd.. The thickness is 20μm.] is adhered to the polarizer. In this way, a brightness improvement film/adhesive layer/protective film B/ The back side polarizing plate B composed of an aqueous adhesive layer/polarizer/adhesive layer.

[Production of evaluation samples]

The front side polarizing plate A was cut into a rectangular shape with a transmission axis direction of 155.25 mm and an absorption axis direction of 95.90 mm, and the back side polarizing plate B was cut into a rectangular shape with an absorption axis direction of 155.25 μm and a transmission axis direction of 95.90 mm. Next, a glass plate (made by Corning Co., model: EAGLE XG (registered trademark)) with a thickness of 0.4 mm was prepared so that the absorption axis of the front side polarizing plate and the back side polarizing plate were orthogonal to each other. The front side polarizing plate and the back side polarizing plate are bonded to the glass plate through separate adhesive layers.

The amount of warpage in a high-temperature environment was measured for the obtained evaluation sample, and the results are shown in Table 1. The polarizing plate warped in a concave shape is the back side polarizing plate, and the protective film B is 85°C. The tensile elastic modulus in the transmission axis direction of the back side polarizing plate is 2,190 MPa, and the absorption axis direction of the back side polarizing plate is The tensile modulus of elasticity is 1,786MPa.

[Example 2]

The front polarizing plate A used in Example 1 was used for the front polarizing plate. The back side polarizing plate is produced in the production of the back side polarizing plate B, except that the protective film B is changed to the protective film C, and the release film F is changed to the release film G, and the rest is made in the same way as the back side polarizing plate B. The back side polarizing plate C is composed of brightness improvement film/adhesive layer/protective film C/water-based adhesive layer/polarizer/adhesive layer. Then, except that the back side polarizing plate B was changed to the back side polarizing plate C of the example, the same operation as in Example 1 was carried out to produce an evaluation sample.

The amount of warpage in a high-temperature environment was measured for the obtained evaluation sample, and the results are shown in Table 1. The polarizing plate warped in a concave shape is the back side polarizing plate, and the protective film C is 85°C. The tensile elastic modulus in the transmission axis direction of the back side polarizing plate is 3,260 MPa, and the absorption axis direction of the back side polarizing plate is lower than The tensile modulus of elasticity is 2,890 MPa.

[Example 3]

The front polarizing plate A used in Example 1 was used for the front polarizing plate. The back side polarizing plate is used in the production of the back side polarizing plate C, except that the protective film C is changed to the protective film D, the rest is produced in the same way as the back side polarizing plate C, and it is made of a brightness improvement film/adhesive layer/ Protective film D/water-based adhesive layer/polarizer/adhesive layer composed of back side polarizing plate D. Then, except that the back-side polarizing plate B was changed to the back-side polarizing plate D of the example, the same operation as in Example 1 was performed to produce an evaluation sample.

The amount of warpage in a high-temperature environment was measured for the obtained evaluation sample, and the results are shown in Table 1. The polarizing plate warped into a concave shape is the back side polarizing plate, and the protective film D is 85°C. The tensile elastic modulus in the transmission axis direction of the back side polarizing plate is 3,460 MPa, and the absorption axis direction of the back side polarizing plate is lower than The tensile modulus of elasticity is 3,031 MPa.

[Comparative Example 1]

The front polarizing plate A used in Example 1 was used for the front polarizing plate. The back side polarizing plate is used in the production of the back side polarizing plate B, except that the protective film B is changed to the protective film E, and the rest is made in the same way as the back side polarizing plate B, and is made of a brightness improvement film/adhesive layer/protection The back side polarizing plate E composed of film E/water-based adhesive layer/polarizer/adhesive layer. Then, except that the back-side polarizing plate B was changed to the back-side polarizing plate E of the example, the same operation as in Example 1 was performed to produce an evaluation sample.

The amount of warpage in a high-temperature environment was measured for the obtained evaluation sample, and the results are shown in Table 1. The polarizing plate warped in a concave shape is the back side polarizing plate, and the protective film E is 85°C. The tensile elastic modulus in the transmission axis direction of the back side polarizing plate is 1,767 MPa, and the absorption axis direction of the back side polarizing plate is less than The tensile modulus of elasticity is 1,813 MPa.

As shown in Table 1, when the tensile elastic modulus Et and Ea of the protective film in the polarizing plate on the side that is warped into a concave shape satisfy Et/Ea≧1.1, the amount of warpage in a high-temperature environment can be reduced.

[Possibility of industrial application]

The polarizing plate set of the present invention is useful because it can reduce the warpage of the liquid crystal panel in a high-temperature environment.

1‧‧‧hardened layer

2‧‧‧Polarizer

10、11‧‧‧Protective film

20、21‧‧‧Adhesive layer

30、31‧‧‧Adhesive layer

40‧‧‧Brightness improvement film

100、101‧‧‧Front side polarizing plate

200、201‧‧‧Back side polarizing plate

Claims (9)

A set of polarizing plates, comprising a polarizing plate arranged on the front side of the observation side of a liquid crystal cell and a back side polarizing plate arranged on the back side of the liquid crystal cell; wherein the front side polarizing plate and the back side polarizing plate are both It has a polarizer formed of a polyvinyl alcohol-based resin film, and the thickness of the polarizer is 15μm or less; the front side polarizer is a single-sided protective polarizer with a protective film on only one side of the polarizer, and the back side polarizer The plate is a single-sided protective polarizer with a protective film on only one side of the polarizer; from the surface of the polarizer on the front side polarizer near the liquid crystal cell to the polarizer of the liquid crystal cell near the polarizer on the front side polarizer The distance of the side surface is 30 μm or less; the front side polarizing plate and the back side polarizing plate are bonded to the glass plate so that the absorption axis of the front side polarizing plate and the absorption axis of the back side polarizing plate are orthogonal to each other. When the resulting laminate is heated at 85°C for 250 hours, the tensile elastic modulus in the penetration axis direction of the polarizing plate at 85°C and the tensile elastic modulus in the absorption axis direction of the polarizing plate at 85°C are set to Et and Ea, respectively. The protective film in the polarizing plate on the side of the laminated body that is warped into a concave shape satisfies the following (1) Et/Ea≧1.1 (1); Polarizing plate. The polarizing plate set described in the first item of the scope of patent application, wherein the front side polarizing plate and the back side polarizing plate are both rectangular with a diagonal of 15 inches or less. According to the set of polarizing plate described in item 1 or 2 of the scope of patent application, the front-side polarizing plate is provided with a hardened layer of an active energy ray curable resin composition on at least one side of the polarizing plate. The set of polarizing plates described in item 1 or 2 of the scope of patent application, wherein the front-side polarizing plate is provided with a protective film on only one side of the polarizer and an active energy ray curable resin composition on the other side The hardened layer. The set of polarizing plates described in item 3 of the scope of patent application, wherein the front-side polarizing plate is provided with a protective film on only one side of the polarizer, and curing of an active energy ray-curable resin composition on the other side Floor. The set of polarizing plates described in claim 1 or 2, wherein the difference between the thickness of the polarizing plate provided on the front side polarizing plate and the thickness of the polarizing plate provided on the back side polarizing plate is a size Below 5μm. The polarizing plate set described in claim 3, wherein the difference between the thickness of the polarizing plate provided on the front side polarizing plate and the thickness of the polarizing plate provided on the back side polarizing plate is 5 μm or less . The set of polarizing plates described in item 4 of the scope of patent application, wherein the thickness of the polarizing plate provided on the front side polarizing plate is the same as the thickness of the back side The size of the difference in thickness of the polarizers included in the polarizing plate is 5 μm or less. A liquid crystal panel is provided with a polarizing plate set according to any one of items 1 to 8 in the scope of patent application, and a liquid crystal cell, the thickness of the liquid crystal cell is 0.4 mm or less.

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