KR20190016082A

KR20190016082A - Polarizer set

Info

Publication number: KR20190016082A
Application number: KR1020197000446A
Authority: KR
Inventors: 다카유키 시라이시
Original assignee: 스미또모 가가꾸 가부시키가이샤
Priority date: 2016-06-09
Filing date: 2017-05-29
Publication date: 2019-02-15
Also published as: WO2017212960A1; CN109313301A; TW201804222A; JP2017223940A

Abstract

An object of the present invention is to provide a polarizing plate set capable of reducing display unevenness caused by bending that is caused by a small amount of bending when placed in a humid environment and a high temperature environment.
The above object is achieved by a polarizing plate set comprising a front polarizing plate disposed on one side of a liquid crystal cell and a rear polarizing plate disposed on the other side of the liquid crystal cell, wherein the front polarizing plate comprises a first protective film and a first polarizer And the first protective film and the first polarizer are stacked in this order from the side farther from the liquid crystal cell, and the first protective film has a slow axis and has an orientation of 100 The film has a shrinkage ratio of 0.1 to 1.0% in the direction of the slow axis and a modulus of elasticity in the direction of the slow axis at 85 DEG C of 1000 to 3000 MPa when the film is time- And the absorption axis of the first polarizer is not less than 60 degrees and not more than 90 degrees, and the back-surface-side polarizer has a second polarizer.

Description

Polarizer set

The present invention relates to a polarizing plate set which can be used in various optical applications.

Polarizers are arranged on both sides of the liquid crystal cell due to the image forming system of the liquid crystal display apparatus.

For example, Patent Document 1 discloses a liquid crystal panel in which polarizers are arranged on the front side and back side of a liquid crystal cell. Further, Patent Document 2 discloses an optical laminate disposed on the front side and back side of a liquid crystal cell.

According to the liquid crystal panel disclosed in Patent Document 1 and the optical laminate disclosed in Patent Document 2, it is possible to reduce the warp of the liquid crystal panel by defining the relationship between the thickness of the polarizing film disposed on the front side and the polarizing film disposed on the back side It is being tried.

Japanese Patent Application Laid-Open No. S58-24299 Japanese Patent Application Laid-Open No. 2013-37115

Conventionally, attention is paid only to warping under a high-temperature environment, and warping of the liquid crystal panel does not become a problem as long as it is controlled. However, as the thickness of the liquid crystal cell became thinner, it was found that the warpage of the liquid crystal cell was remarkably confirmed even by the stress of the polarizing plate caused by a slight dimensional change caused under a humid environment (60 DEG C, 90%).

The invention disclosed in Patent Documents 1 and 2 has a large deflection of the liquid crystal panel in use under a humid condition. For this reason, there is a problem that the liquid crystal panel is peeled off from the touch panel or the backlight unit is dropped due to the warp.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a polarizing plate set capable of suppressing bending of a liquid crystal panel under a humid environment as well as bending of a liquid crystal panel under a high temperature environment.

The present invention includes the following.

[1] A polarizing plate set comprising a front side polarizing plate disposed on one side of a liquid crystal cell and a back side polarizing plate disposed on the other side of the liquid crystal cell,

Wherein the front polarizer comprises a first protective film and a first polarizer, and the first protective film and the first polarizer are stacked in this order from a side farther from the liquid crystal cell,

The first protective film has a shrinkage ratio of 0.1 to 1.0% in the direction of the slow axis when it is left standing for 100 hours in an environment of 85 占 폚 and humidity of 5%

The elastic modulus in the slow axis direction at 85 캜 is 1000 MPa to 3000 MPa,

The angle formed between the slow axis of the first protective film and the absorption axis of the first polarizer is 60 ° or more and 90 ° or less,

And the back-surface-side polarizer has a second polarizer.

[2] A polarizing plate set according to [1], wherein the ratio of the long side to the short side of the front side polarizing plate is 1.2: 1 to 2: 1.

[3] A polarizing plate set according to [1] or [2], wherein an absorption axis of the first polarizer in the front polarizer and an angle formed by short sides of the front polarizer are 0 ° ± 1 °.

[4] The polarizer set described in any one of [1] to [3], wherein the thickness of the first polarizer is 15 μm or less.

[5] The polarizing plate set described in any one of [1] to [4], wherein the first protective film has a thickness of 10 μm to 50 μm.

[6] The polarizing plate set described in any one of [1] to [5], wherein the back-surface-side polarizing plate further comprises a reflection-type polarizing plate.

[7] A liquid crystal display comprising a liquid crystal cell and a pair of polarizers disposed on both sides thereof,

Wherein the pair of polarizers is the polarizer set described in any one of [1] to [6]

A first polarizer, a liquid crystal cell, and a second polarizer are stacked in this order.

According to the present invention, it is possible to obtain a polarizing plate set in which the amount of warpage is small when placed in a humid environment and a high temperature environment, so that the polarizer is not broken.

1 is a schematic cross-sectional view illustrating one embodiment of a polarizing plate set of the present invention.
2 is a schematic view for explaining the relationship between the slow axis of the first protective film and the absorption axis of the first polarizer.
3 is a schematic view showing the relationship between the absorption axis of the first polarizer and the absorption axis of the second polarizer.
4 is a schematic view showing a measurement point of a deflection amount.

Hereinafter, the polarizing plate set according to the present invention will be described using appropriate drawings, but the present invention is not limited to these embodiments.

A polarizing plate set according to the present invention is a polarizing plate set comprising a front polarizing plate disposed on one side of a liquid crystal cell and a rear polarizing plate disposed on the other side,

When the first protective film has a slow axis and is allowed to stand in an environment at 85 캜 and a humidity of 5% for 100 hours, the first protective film has a shrinkage ratio of 0.1 to 1.0% in the slow axis direction

And the back-surface-side polarizer has a second polarizer.

In one aspect, the polarizer set of the present invention may have the structure illustrated in Fig. For example, a front-side polarizing plate 10 disposed on one side of the liquid crystal cell 30 and a rear-side polarizing plate 20 disposed on the other side. In one aspect, the front-side polarizing plate 10 has, for example, a first protective film 11, a first polarizer 12, and a first pressure-sensitive adhesive layer 13. In one embodiment, the back side polarizing plate 20 includes a second pressure sensitive adhesive layer 21, a back side protective film 22, a second polarizer 23, a third pressure sensitive adhesive layer 24, a reflection type polarizing plate 25 ). These layers may have additional layers as desired.

The front-side polarizing plate in the present invention is bonded to, for example, a face on the viewer side of the liquid crystal cell. On the other hand, the back-surface-side polarizing plate in the present invention is bonded to, for example, a surface opposite to the viewer-side surface of the liquid crystal cell. In one aspect, the back-surface-side polarizing plate may be bonded to the liquid crystal cell so as to be adjacent to a light source such as a backlight provided in the liquid crystal display device.

Although not shown in FIG. 1, for example, the polarizing plate set shown in FIG. 1, that is, the front-side polarizing plate 10 and the back-surface-side polarizing plate 20 may be provided with layers other than the above-described layers. In this case, the thickness of the newly provided layer is also included in the thickness of each polarizing plate. Further, the polarizers 12 and 23 and the protective films 11 and 22 are usually bonded through an adhesive layer. The thickness of the adhesive layer may also be included in the thickness of each polarizing plate.

In the present invention, the first protective film has a slow axis. In one embodiment, for example, when the polymer film used for the first protective film is stretched in one direction, the film surface inner shrinkage in which the refractive index becomes maximum in the stretching direction is generated. In the present invention, such an in-plane shaft may be a ground shaft. The stretching direction is not particularly limited, and stretching may be performed in the longitudinal direction of the polymer film used for the protective film.

Further, for example, when the polymer film is stretched in the long-side direction, the slow axis of the first protective film according to the present invention may be arranged at a predetermined angle with the absorption axis of the first polarizer, Accordingly, the stretched polymer film may be cut and used as the first protective film.

In a separate embodiment, for example, the polymer film used for the protective film may be stretched in the oblique direction so as to have a slow axis inclined at a predetermined angle with respect to the long-side direction.

In a separate embodiment, for example, when the polymer film used for the first protective film is subjected to biaxial stretching in the biaxial direction by the biaxial stretching, the film surface internal shrinkage occurring in the direction of expressing the optical axis, that is, Plane direction of the film may be a ground axis.

In the present invention, the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is not less than 60 ° and not more than 90 °.

For example, as shown in FIG. 2, the first protective film 11 has a slow axis 11b. The angle? Between the slow axis 11b and the absorption axis 12a of the first polarizer (not shown) is in the range of 60 to 90 degrees, more preferably in the range of more than 60 to less than 90 And more preferably in the range of 65 DEG to 80 DEG.

By having such an angular relationship, it is possible to reduce warping under a high temperature condition and a moist heat condition.

Since the present invention is a polarizing plate set including the front side polarizing plate and the back side polarizing plate having such angular relationship, the amount of warping under a high temperature condition and a moist heat condition is small. For example, when the back side polarizing plate and the backlight are bonded, Can be suppressed, and a polarizing plate set having good optical characteristics can be obtained.

In one embodiment, the angle formed by the absorption axis of the first polarizer and the short side of the front-side polarizing plate in the front-side polarizing plate is 0 占 쏙옙 1 占 and more preferably 0 占 0.5 占.

In one embodiment, the angle formed between the absorption axis of the second polarizer and the shorter side of the rear surface side polarizing plate in the rear surface side polarizing plate is 90 占 쏙옙 1 占 and more preferably 90 占 0.5 占.

In one aspect, the angle formed between the absorption axis of the first polarizer and the short side of the front-side polarizing plate in the front-side polarizing plate is 0 占 1 占 and the absorption axis of the second polarizing plate in the back- The angle formed by the short side of 90 ° ± 1 °.

3, the absorption axis 12a of the first polarizer 12 and the absorption axis 23a of the second polarizer 20 in the back-surface-side polarizing plate 20 are aligned with each other, The angle can be set in the range of 90 DEG +/- 1 DEG, and in other embodiments, in the range of 90 DEG +/- 0.5 DEG.

In another embodiment, the angle formed between the absorption axis of the first polarizer and the short side of the front-side polarizing plate in the front-side polarizing plate is 90 ° ± 1 °, for example, 90 ° ± 0.5 °. In this case, it is preferable that the angle formed by the absorption axis of the second polarizer and the short side of the back side polarizing plate in the back side polarizing plate is 0 占 1 占 and in other embodiments, 0 占 0.5 占 is preferable.

In one embodiment, the angle formed between the absorption axis of the first polarizer and the absorption axis of the second polarizer is 90 占占 1, more preferably 90 占 0.5 占. In the present invention, a state in which the absorption axis of the first polarizer and the absorption axis of the second polarizer are substantially orthogonal can be referred to as a polarizer arranged in a crossed-Nicol state.

For example, in the case where the absorption axis of the first polarizer and the absorption axis of the second polarizer are arranged in a crossed-Nicol state, in one embodiment, the absorption axis of the first polarizer and the short side of the front- The angle formed by the absorption axis of the second polarizer in the back side polarizing plate and the short side of the back side polarizing plate is 90 占占 1 占.

In some embodiments, when the absorption axis of the first polarizer and the absorption axis of the second polarizer are arranged in a crossed-Nicol state, the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is Is in the range of 60 DEG to less than 90 DEG, and more preferably in the range of 65 DEG to 80 DEG.

According to this embodiment, since the various axial directions of the front-side polarizing plate and the back-surface-side polarizing plate are hardly overlapped, it is considered that the contraction force that can be generated in each axial direction can be effectively dispersed. This makes it possible to suppress or reduce warpage that may occur in the front-side polarizing plate and the back-surface-side polarizing plate, for example, under a humid condition and a high temperature environment.

The polarizing plate set of the present invention can maintain the balance between deflection of the glass plate in the liquid crystal cell which can be caused by shrinkage that may occur in the front side polarizing plate and the back side polarizing plate and stresses caused by contraction of these polarizing plates. As described above, since the shrinking force of each polarizing plate and the warping of the glass plate can be balanced well, the polarizing plate set of the present invention can significantly reduce display unevenness attributable to warping of glass even under a humid condition and a high temperature environment .

For example, when the absorption axis of the second polarizer in the back side polarizing plate is provided in the long side direction, the stress at the time of contraction of the back side polarizing plate becomes dominant, and the glass may be warped. On the other hand, in the polarizing plate set of the present invention, since the front-side polarizing plate having a predetermined structure is used in combination with the back-side polarizing plate, the degree of the force acting on the glass can be made approximately the same on the front side and the back side.

All of the effects described above can be obtained even when the absorption axis of the second polarizer in the back side polarizing plate is provided in the short side direction, but is remarkable in the case where the absorption axis of the second polarizer is provided in the long side direction .

In the present invention, the absorption axis of the first polarizer in the front-side polarizer may be described as the absorption axis of the front-side polarizer, and the absorption axis of the second polarizer in the rear- The absorption axis of the polarizing plate may be used.

In one embodiment, the ratio of the long side to the short side of the front side polarizing plate is 1.2: 1 to 2: 1.

By having the long side and the short side ratio of the front side polarizing plate within such a range, the warping under the high temperature condition and the moist heat condition can be more effectively reduced.

In one embodiment, the thickness of the first polarizer of the front polarizer is 15 占 퐉 or less.

In one embodiment, the thickness of the second polarizer of the back side polarizing plate is 15 占 퐉 or less. The thickness of the first polarizer and the thickness of the second polarizer may be the same or different.

The thickness of each layer of the polarizing plate set in the present invention can be measured using a known measuring method in the related art.

Here, the exposure of the polarizing plate under high temperature conditions means that the polarizing plate or the like is exposed to the temperature of 70 占 폚 to 95 占 폚 for at least 30 to 60 minutes, for example. Preferably, the humidity at a high temperature condition is 10% or less.

Further, when the polarizing plate set according to the present invention is exposed under a high-temperature condition and the polarizing plate may have some warp, for example, the first protective film, the first polarizer and the first pressure-sensitive adhesive layer may be integrally bent . Similarly, for example, the second pressure-sensitive adhesive layer, the back-side protective film, the second polarizer, the third pressure-sensitive adhesive layer, and the reflection-type polarizer can be integrally bent.

Therefore, the back-side polarizing plate and the front-side polarizing plate in the present invention are usually not capable of delamination between at least one of these layers.

With respect to such bending, the present invention can be evaluated by measuring the amount of bending or the like. For example, the bending amount may be evaluated by measuring a bending amount under a humid condition, or may be evaluated by measuring a bending amount at a high temperature condition.

For example, in the case of measuring the amount of warp in the humid condition, the first pressure-sensitive adhesive layer of the front-side polarizing plate and the second pressure-sensitive adhesive layer of the back-surface-side polarizing plate are bonded to the front and back surfaces of the glass panel ) Was placed in an environment of 60 ° C and humidity of 90% for 250 hours, and then the laminate was placed so that the back-side polarizing plate was downward, and the relative height of lifting from the horizontal plane of the measuring table was measured.

In the present invention, the moist heat condition is preferably a temperature range of 40 to 70 캜, and represents a humidity of 40% to 90%.

For example, the warping amount of the laminate under the humid condition is less than 1.00 mm, more preferably not more than 0.8 mm.

With the polarizing plate set of the present invention, the warping in the humid condition can be in the above range. Further, since the bending in the humid condition is within the above-mentioned range, it is possible to obtain an effect that light leakage is unlikely to occur at the end of the liquid crystal display device when the liquid crystal display device is incorporated.

Similarly, for example, in the case of measuring the amount of warping of the laminate at a high temperature, the polarizer after the laminate is left in an environment of 85 ° C and a humidity of 5% for 250 hours, Is a measurement of the relative height of the inboard surface from a horizontal plane at the in-plane center.

For example, the amount of warping in a laminate at a high temperature condition is less than 1.00 mm, and more preferably 0.8 mm or less.

By showing the amount of deflection in such a range, for example, when embedded in a liquid crystal display device, light leakage at the end portion of the liquid crystal display device is unlikely to occur.

[Protection film]

The first protective film is a film laminated on the side opposite to the liquid crystal cell of the first polarizer, and in one embodiment, on the side opposite to the first pressure-sensitive adhesive layer in the first polarizer. Further, as described above, at least the first protective film has a slow axis.

In one aspect, the front-side polarizing plate may have a second protective film on a surface opposite to the first protective film in the first polarizer.

Further, in one embodiment, the back side protective film is a film laminated on a surface opposite to the third pressure sensitive adhesive layer in the second polarizer. At least two of the first protective film, the second protective film, and the back side protective film may be the same film or may be different films.

The protective film may be a polyolefin resin such as a thermoplastic resin having a light transmitting property (preferably optically transparent) such as a chain-like polyolefin resin (polypropylene resin), a cyclic polyolefin resin (norbornene resin or the like); Cellulose-based resins such as triacetylcellulose and diacetylcellulose; Polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; Acrylic resins such as (meth) acrylic resins; Polystyrene type resin; Polyvinyl chloride resins; Acrylonitrile-butadiene-styrene-based resin; Acrylonitrile-styrene series resin; Polyvinyl acetate resin; Polyvinylidene chloride resins; Polyamide based resin; A polyacetal-based resin; Modified polyphenylene ether-based resin; Polysulfone resins; Polyether sulfone type resin; Polyarylate resins; Polyamideimide series resin; A polyimide-based resin, or the like. Among them, a cellulose resin, a polyolefin resin or an acrylic resin is preferably used, and it is particularly preferable to use a cellulose resin from the viewpoint of the effect of reducing warping in an anti-wet heat environment.

Examples of the chain-like polyolefin-based resin include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more kinds of chain olefins.

The cyclic polyolefin-based resin is a generic name of a resin that is polymerized with a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include a ring-opening (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer (typically a random copolymer) of a cyclic olefin and a chain olefin such as ethylene or propylene, A graft polymer modified with a carboxylic acid or a derivative thereof, and a hydride thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used. In a preferred embodiment, the protective film according to the present invention comprises a cyclic polyolefin-based resin.

The cellulose-based resin is a resin in which part or all of the hydrogen atoms in the hydroxyl group of the cellulose obtained from the raw cellulose such as cotton linters and wood pulp (hardwood pulp, softwood pulp) and the like are substituted with an acetyl group, a propionyl group and / or a butyryl group , A cellulose organic acid ester, or a cellulose mixed organic acid ester. Examples thereof include acetic acid esters of cellulose, propionic acid esters, butyric acid esters, and mixed esters thereof.

A preferable specific example of the acrylic resin film is a film containing a methyl methacrylate resin. The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 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 containing methyl methacrylate as a main component and a polyfunctional monomer to be used if necessary in the presence of a radical polymerization initiator and a chain transfer agent to be used as required .

Examples of monofunctional monomers that can be copolymerized with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, Methacrylic acid esters other than methyl methacrylate such as 2-hydroxyethyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; Hydroxyacrylic esters such as methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate and butyl 2- (hydroxymethyl) acrylate; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrenes such as vinyltoluene and? -Methylstyrene; Unsaturated nitriles such as acrylonitrile and methacrylonitrile; Unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; And unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. These monomers may be used singly or in combination of two or more kinds.

Examples of polyfunctional monomers copolymerizable with methyl methacrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (Meth) acrylate, nonaethylene glycol di (meth) acrylate and tetradecaethylene glycol (meth) acrylate, esterified with acrylic acid or methacrylic acid at both terminal hydroxyl groups of ethylene glycol or its oligomer; Ester of propylene glycol or its oligomer with both terminal hydroxyl groups of acrylic acid or methacrylic acid; (Meth) acrylate, neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate and butanediol di (meth) acrylate esterified with acrylic acid or methacrylic acid; Bisphenol A, an alkylene oxide adduct of bisphenol A, or a halogen substituent thereof, esterified with acrylic acid or methacrylic acid; Trimethylol propane and pentaerythritol esterified with acrylic acid or methacrylic acid, and epoxy groups of glycidyl acrylate or glycidyl methacrylate added to these terminal hydroxyl groups are ring-opened; Dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid and halogen substituents of these, and alkylene oxide adducts thereof, and those in which epoxy groups of glycidyl acrylate or glycidyl methacrylate are ring- Aryl (meth) acrylate; And diaryl compounds such as divinyl benzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.

The methyl methacrylate resin may be a modified methyl methacrylate resin modified by reacting between the functional groups of the resin. Examples of the reaction include a condensation reaction in a polymer chain of a methyl ester group of methyl acrylate and a hydroxyl group of 2- (hydroxymethyl) acrylate, a condensation reaction of a carboxyl group of acrylic acid with a hydroxyl group of 2- (hydroxymethyl) And dehydration condensation reaction in the presence of water.

It is also useful to control the retardation value of the protective film to a value suitable for the liquid crystal display device. For example, in a liquid crystal display device of an in-plane switching (IPS) mode, it is preferable to use a film whose phase difference value is substantially zero. Substantially zero retardation value means that the in-plane retardation value at a wavelength of 590 nm is 10 nm or less, the absolute value of the retardation value in the thickness direction at a wavelength of 590 nm is 10 nm or less, and the retardation value at a wavelength of 480 to 750 nm And the absolute value of the retardation value in the thickness direction is 15 nm or less.

Depending on the mode of the liquid crystal display device, a suitable retardation value may be given by stretching and / or shrinking the protective film. However, in the present invention, stretching and / or shrinking is performed in a range in which the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is within a predetermined range.

The thickness of the protective film may be about 1 to 30 占 퐉, but is preferably 5 to 25 占 퐉, more preferably 5 to 20 占 퐉, from the viewpoints of strength and handleability. If the thickness is within this range, the polarizer is mechanically protected, so that the shrinkage of the polarizer can be suppressed even when exposed in a moist heat environment and a high temperature environment, and stable optical characteristics can be maintained.

The shrinkage percentage of the first protective film is preferably in the range of 0.1 to 1.0%. If the shrinkage ratio exceeds 1.0%, the first protective film can not suppress shrinkage of the polarizer, and problems such as peeling of the polarizing plate in a high temperature and high humidity environment may occur.

The value obtained by measuring the rate of dimensional change of the first protective film alone when the film is allowed to stand for 100 hours in an environment having a shrinkage factor of 85 deg. C and a humidity of 5% is employed.

In the present invention, the shrinkage percentage means the shrinkage percentage in the direction of the slow axis of the protective film. For example, the slow axis direction of the protective film may be substantially parallel to the long side direction or the short side direction of the protective film. It is preferable that the slow axis of the protective film has a predetermined angle, for example, 60 to 90 degrees with respect to the flow direction (MD direction).

The elastic modulus of the first protective film at 85 deg. C is in the range of 1000 to 3000 MPa. If it exceeds this range, the first protective film can not suppress shrinkage of the polarizer, and problems such as peeling of the polarizing plate in a high temperature, high temperature and high humidity environment may occur. In the present specification, the modulus of elasticity of the first protective film means the modulus of elasticity of the first protective film in the slow axis direction.

The sample was preheated in an environment of 85 ° C and a humidity of 5% for 10 minutes, and then subjected to a tensile test at a temperature of 85 ° C and a humidity of 5% under a tensile rate of 1 mm / min.

The protective film can be bonded to the polarizer through the adhesive layer. As the adhesive forming the adhesive layer, an aqueous adhesive or an active energy ray-curable adhesive can be used.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component emulsion type urethane emulsion adhesive, and the like. Among them, an aqueous adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. Examples of the polyvinyl alcohol-based resin include a polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and other monomers copolymerizable therewith, as well as a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate , Or a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl group thereof. The water-based adhesive may include a crosslinking agent such as an aldehyde compound, an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound or a polyvalent metal salt.

In the case of using the water-based adhesive, it is preferable to carry out a step of bonding the polarizer and the protective film, followed by drying to remove water contained in the water-based adhesive. After the drying step, a curing step for curing at a temperature of, for example, about 20 to 45 DEG C may be provided.

The active energy ray-curable adhesive is an adhesive that cures by irradiating active energy rays such as ultraviolet rays. For example, it includes a polymerizable compound and a photopolymerization initiator, a photoreactive resin, a binder resin, and a photoreactive crosslinking agent And the like. Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable acrylic monomer, a photocurable urethane monomer, and an oligomer derived from a photopolymerizable monomer. Examples of the photopolymerization initiator include those that generate active species such as neutral radicals, anion radicals, and catechol radicals upon irradiation with active energy rays such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy-based monomer and a photo-cationic polymerization initiator can be preferably used.

In the case of using an active energy ray-curable adhesive, a curing step of curing the active energy ray-curable adhesive is performed by bonding a polarizer and a protective film, then performing a drying step if necessary, and then irradiating with an active energy ray. Although a light source of an active energy ray is not particularly limited, ultraviolet rays having a light emission distribution at a wavelength of 400 nm or less are preferable. Specifically, low energy mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, chemical lamps, Mercury, and metal halide lamps.

In joining the polarizer and the protective film, saponification treatment, corona treatment, plasma treatment, or the like can be performed on the joint surface of at least one of them.

[Polarizer]

The polarizer is an absorption type polarizer which absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis). The first polarizer and the second polarizer used in the polarizing plate set of the present invention may be the same polarizer or different polarizers. For example, a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be suitably used. The polarizer may be, for example, a process of uniaxially stretching a polyvinyl alcohol-based resin film; A step of adsorbing a dichroic dye by staining a polyvinyl alcohol-based resin film with a dichroic dye; Treating a polyvinyl alcohol-based resin film adsorbed with a dichroic dye with an aqueous solution of boric acid; And a step of washing with water after treatment with an aqueous boric acid solution.

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

The saponification degree 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, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually about 1000 to 10000, preferably about 1500 to 5000. The average polymerization degree of the polyvinyl alcohol-based resin can be obtained according to JIS K 6726.

Such a polyvinyl alcohol-based resin film is used as a raw film of a polarizer (polarizing film). A method of producing a film of a polyvinyl alcohol-based resin is not particularly limited, and a known method is employed. Although the thickness of the polyvinyl alcohol based fabric film is not particularly limited, it is preferable to use a film having a thickness of about 5 to 35 μm in order to make the thickness of the polarizer 15 μm or less. More preferably, a fabric film having a thickness of 20 mu m or less is used.

The uniaxial stretching of the polyvinyl alcohol based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. In the case of uniaxial stretching after dyeing, the uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed in these plural steps.

In the uniaxial stretching, the uniaxial stretching may be performed between rolls different in the main speed, or may be uniaxially stretched using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air or wet stretching in which stretching is performed in a state in which the polyvinyl alcohol based resin film is swollen with a solvent. The stretching magnification is usually about 3 to 8 times.

As a method for dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye is employed. As the dichroic dye, iodine or a dichroic organic dye is used. It is preferable that the polyvinyl alcohol based resin film is subjected to immersion treatment in water before the dyeing treatment.

As a dyeing treatment by iodine, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in the aqueous solution may be about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide may be about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be about 20 to 40 캜. On the other hand, as a dyeing treatment with a dichroic organic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic organic dye is usually employed. The aqueous solution containing the dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing aid. The content of the dichroic organic dye in the aqueous solution may be about 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be about 20 to 80 캜.

As the boric acid treatment after dyeing with the dichroic dye, a method of immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid is usually employed. When iodine is used as the dichroic dye, it is preferable that the aqueous solution containing boric acid contains potassium iodide. The amount of boric acid in the boric acid-containing aqueous solution may be about 2 to 15 parts by weight per 100 parts by weight of water. The amount of potassium iodide in the aqueous solution may be about 0.1 to 15 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be 50 캜 or higher, for example, 50 캜 to 85 캜.

The polyvinyl alcohol-based resin film after treatment with boric acid is usually subjected to water washing treatment. The water washing treatment can be carried out, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 캜.

After washing with water, drying treatment is carried out to obtain a polarizer. The drying treatment can be performed using a hot-air dryer or a far-infrared heater. The thickness of the polarizer is preferably 15 占 퐉 or less, more preferably 10 占 퐉 or less. Setting the thickness of the polarizer to 15 m or less is advantageous for making a polarizing plate, and further, a liquid crystal display device thinner. The thickness of the polarizer is usually 4 占 퐉 or more. Further, the thickness of the polarizer can be appropriately adjusted so as not to deviate from the scope of the present invention.

[First and second pressure-sensitive adhesive layers]

As the pressure-sensitive adhesive for forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, conventionally known pressure-sensitive adhesives may be appropriately selected and the pressure-sensitive adhesive may be peeled off under a high temperature environment in which the polarizer is exposed, a moist heat environment, Any adhesive may be used as long as it does not cause adhesion.

For example, the first and second pressure-sensitive adhesive layers can be used for bonding various polarizing plates and liquid crystal cells.

Examples of the pressure-sensitive adhesive that can be used for the first and second pressure-sensitive adhesive layers include acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, and rubber pressure-sensitive adhesives. Acrylic pressure-sensitive adhesives are particularly preferable in terms of transparency, weather resistance, heat resistance and workability.

The first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer and / or the third pressure-sensitive adhesive layer may be made of the same kind of pressure-sensitive adhesives or different types of pressure-sensitive adhesives.

In a preferred embodiment, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are formed of an acrylic pressure-sensitive adhesive.

The pressure-sensitive adhesive may contain a filler, a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber, an antistatic agent, a silane coupling agent, and the like, which are composed of a tackifier, plasticizer, glass fiber, glass bead, metal powder, Various additives may be appropriately blended.

The pressure-sensitive adhesive layer is usually formed by applying a solution of a pressure-sensitive adhesive onto a release sheet and drying the pressure-sensitive adhesive. Coating on the release sheet can be carried out by, for example, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, a spraying method and the like. The release sheet provided with the pressure-sensitive adhesive layer is used according to a method of transferring the release sheet. The thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are usually about 3 to 30 μm, preferably 10 to 30 μm, and more preferably 10 to 25 μm. In a preferred embodiment, when the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have such a thickness, breakage of the polarizing plate can be suppressed, and light leakage at the end of the liquid crystal display device when embedded in the liquid crystal display device . Further, the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer can be appropriately adjusted so that the inter-layer thickness becomes a predetermined range, and the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be the same, It may be thick.

The storage elastic modulus of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at 80 캜 is preferably 0.015 MPa or more, and more preferably 0.03 MPa or more. If the storage modulus of the pressure-sensitive adhesive layer is less than 0.015 MPa, cohesive failure of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may occur, and if the cohesive failure is significant, the appearance of the polarizing plate may be adversely affected, Light leakage occurs at the end portion of the liquid crystal display device, and the display is adversely affected. Preferably, the storage elastic modulus of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at 80 캜 is 1.1 MPa or less, preferably 0.9 MPa or less. When the storage elastic modulus of the pressure-sensitive adhesive layer at 80 DEG C exceeds 1.1 MPa, the heat-resistant durability of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer and the glass or panel deteriorates, and bubbles are likely to be generated between the layers.

A separator may be provided to protect the surfaces of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer until they are bonded to another member. For example, a film made of a transparent resin such as polyethylene terephthalate is subjected to a treatment with a release agent such as silicone.

[Reflective Polarizer]

The reflection type polarizing plate is also referred to as a brightness enhancement film, and a polarization conversion element having a function of separating outgoing light from a light source (backlight) into transmission polarized light and reflected polarized light or scattered polarized light is used. As described above, by arranging the reflection type polarizing plate and the polarizer in a predetermined relationship, it is possible to improve the output efficiency of the linearly polarized light emitted from the polarizer by using the recursive light that is the reflected polarized light or the scattered polarized light. For example, the reflection type polarizing plate is laminated in contact with the third pressure sensitive adhesive layer.

The reflective polarizer may be, for example, an anisotropic reflective polarizer. An example of the anisotropic reflective polarizer is an anisotropic multi-layer film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction, and a specific example thereof is a DBEF manufactured by 3M (Japanese Patent Laid- 268505). This reflection type polarizing plate is a reflection type polarizing plate formed by stretching a multilayer laminate composed of at least two thin films having different refractive anisotropy. Therefore, such a reflection type polarizing plate has at least two layers of thin films, and at least two layers of stretched thin films are different in refractive index anisotropy.

Another example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a? / 4 plate, and a specific example thereof is PCF manufactured by Nitto Denko Corporation (JP-A-11-231130). Another example of the anisotropic reflective polarizer is a reflective grid polarizer, and specific examples thereof include a metal lattice reflective polarizer (such as U.S. Patent No. 6,288,840), a metal reflective reflective polarizer that emits reflected polarized light in a visible region by micro- (Japanese Patent Application Laid-open No. Hei 8-184701) which is obtained by adding fine particles to a polymer matrix.

An optical layer such as a hard coat layer, an antiglare layer, a light diffusion layer, and a retardation layer having a retardation value of 1/4 wavelength may be provided on the surface of the reflection type polarizing plate opposite to the first pressure sensitive adhesive layer. By forming the optical layer, the adhesion to the backlight tape and the uniformity of the display image can be improved. The thickness of the reflection type polarizing plate may be about 5 to 100 mu m, but is preferably 10 to 40 mu m, more preferably 10 to 30 mu m from the viewpoint of thinning of the polarizing plate.

In the polarizing plate set of the present invention, the surface of the reflection type polarizing plate on the side of the third pressure sensitive adhesive layer may be subjected to surface activation treatment. This surface activation treatment is performed prior to bonding of the reflective polarizing plate and the third pressure sensitive adhesive layer. This makes it possible to obtain a polarizing plate excellent in wet heat durability and high temperature durability which is less likely to be peeled off between the third pressure-sensitive adhesive layer and the reflective polarizing plate under humid and high temperature environments.

The surface activation treatment may be a hydrophilic treatment of the surface, a dry treatment or a wet treatment. Examples of the dry treatment include a discharge treatment such as a corona treatment, a plasma treatment, and a glow discharge treatment; Flame treatment; Ozone treatment; UV ozone treatment; Ultraviolet ray treatment, ionizing radiation treatment such as electron beam treatment, and the like. Examples of the wet treatment include an ultrasonic treatment using a solvent such as water or acetone, an alkali treatment, and an anchor coat treatment. These treatments may be performed alone or in combination of two or more.

Among them, the surface activation treatment is preferably a corona treatment and / or a plasma treatment, from the viewpoints of the effect of suppressing the peeling-off of the reflection type polarizing plate and the productivity of the polarizing plate under a humid environment. According to these surface activation treatments, even when the thickness of the reflection type polarizing plate is thin, for example, 30 m or less, peeling between the third pressure-sensitive adhesive layer and the reflection type polarizing plate under a humid environment can be effectively suppressed. The surface of the third pressure sensitive adhesive layer on the side of the brightness reflective type polarizing plate may also be subjected to surface activation treatment.

[Third Pressure Sensitive Adhesive Layer]

The third pressure-sensitive adhesive layer is a layer interposed between the second polarizer and the reflective polarizer. The third pressure sensitive adhesive layer is typically directly laminated to the polarizer so that the second polarizer and the third pressure sensitive adhesive layer are in contact with each other. The third pressure sensitive adhesive layer may be formed of the same material as the first pressure sensitive adhesive layer or the second pressure sensitive adhesive layer. Specifically, the third pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive composition containing a resin such as acrylic, rubber, urethane, ester, silicone or polyvinyl ether as a main component. Above all, a pressure-sensitive adhesive composition comprising an acrylic resin excellent in transparency, weather resistance, heat resistance and the like as a base polymer is suitable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type. The third pressure sensitive adhesive layer and the first pressure sensitive adhesive layer or the second pressure sensitive adhesive layer may be formed of the same material or different materials respectively.

The third pressure-sensitive adhesive layer preferably exhibits a storage elastic modulus of 0.15 to 1.2 MPa in a temperature range of 23 to 80 캜. This makes it possible to suppress the dimensional change easily caused by the contraction of the polarizer under the high-temperature and low-humidity environment, and to improve the durability of the polarizing plate. Further, even when a liquid crystal display device (for example, a liquid crystal display device for a small / medium-sized mobile terminal) equipped with a polarizing plate is placed under a high-temperature and humid environment, the movement of the polarizing plate is suppressed, and therefore the reliability of the liquid crystal display device can be enhanced.

Means that the storage modulus of 0.15 to 1.2 MPa in the temperature range of 23 to 80 캜 means that the storage modulus is within the above range even at any temperature within this range. Therefore, even when the storage elastic moduli at 23 deg. C and 80 deg. C are separately described, the respective storage elastic moduli are included in the above ranges.

Since the storage elastic modulus generally decreases with increasing temperature, when the storage elastic modulus at 23 deg. C and 80 deg. C falls within the above range, the storage elastic modulus within the above range can be regarded as the storage elastic modulus at this temperature range. The storage elastic modulus of the pressure-sensitive adhesive layer can be measured using a commercially available viscoelasticity measuring device, for example, a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC Co., as shown in Examples described later.

As a method for adjusting the storage elastic modulus to the above range, an oligomer, specifically, a urethane acrylate oligomer is further added to a pressure-sensitive adhesive composition comprising a base polymer and a crosslinking agent to prepare an active energy ray-curable pressure- Curable pressure-sensitive adhesive composition). More preferably, the active energy ray is irradiated to appropriately cure the pressure-sensitive adhesive layer.

The thickness of the third pressure sensitive adhesive layer may be 30 占 퐉 or less. Preferably 25 mu m or less, particularly preferably 20 mu m or less, particularly preferably 15 mu m or less. When the thickness of the third pressure sensitive adhesive layer is within this range, the dimensional change of the polarizing plate can be suppressed while maintaining good processability. In addition, the thickness of the third pressure sensitive adhesive layer can be appropriately adjusted so that the thickness of the interlayer may be within a predetermined range.

[Production method of front polarizing plate]

The front-side polarizing plate of the present invention includes, for example, bonding the first protective film to one side of the first polarizer through an adhesive layer. In this case, the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is a predetermined angle.

Further, for example, it includes bonding the first pressure-sensitive adhesive layer to the surface of the first polarizer opposite to the first protective film.

In one embodiment, the second polarizing film includes a second polarizing film and a second polarizing film which are bonded to a surface of the first polarizer opposite to the first polarizing film via an adhesive layer, And bonding the first pressure sensitive adhesive layer to the surface on the opposite side. Further, a separator may be attached to the outer surface of the first pressure-sensitive adhesive layer.

As described above, the front-side polarizing plate of the present invention can be manufactured in accordance with a known method in the related art, as long as the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is a predetermined angle .

[Production method of rear side polarizing plate]

In one embodiment, a reflective polarizing plate in which a third pressure-sensitive adhesive layer is laminated is formed on a second polarizer.

The back surface side polarizing plate of the present invention can be obtained, for example, by joining the back surface side protective film to one side of the second polarizer through the adhesive layer, A second pressure-sensitive adhesive layer is laminated on the side opposite to the first polarizer, a third pressure-sensitive adhesive layer is bonded to a surface opposite to the back-side protective film of the second polarizer, Type polarizing plate. By going through these steps, the back side polarizing plate in one embodiment is obtained. A separator may be attached to the outer surface of the second pressure sensitive adhesive layer, or the surface of the third pressure sensitive adhesive layer to be bonded to the reflective polarizing plate may be subjected to surface activation treatment.

The method of bonding the reflective polarizer to the third pressure-sensitive adhesive layer may be a sheet-to-sheet bonding method, or a sheet-roll composite bonding method as disclosed in Japanese Patent Application Laid-Open No. 2004-262071. In addition, it is possible to produce a long product, and in the case where the required quantity is large, a roll-to-roll bonding method is also useful.

As described above, the method for producing the back-surface-side polarizing plate of the present invention can be manufactured by a known method in the related art.

[Liquid crystal display device]

The polarizing plate set according to the present invention can be suitably applied to a liquid crystal display device. A liquid crystal display device includes a liquid crystal cell and a set of polarizing plates according to the present invention bonded to its surface.

The front-side polarizing plate may be bonded to the liquid crystal cell through the first pressure-sensitive adhesive layer, for example. The front-side polarizing plate according to the present invention is used as a polarizing plate disposed on the viewer side of the liquid crystal cell. For example, the liquid crystal display has a front polarizing plate so that the first protective film is an outermost layer.

Further, the back-surface-side polarizer according to the present invention is used as a polarizer disposed on the backlight side of the liquid crystal cell. The bonding of the back-surface-side polarizing plate to the liquid crystal cell can be performed, for example, through the second pressure-sensitive adhesive layer.

The driving method of the liquid crystal cell may be any conventionally known method, but is preferably an IPS mode. The liquid crystal display device using the polarizing plate according to the present invention is excellent in wet heat durability.

In the present invention, an organic electroluminescence display device can be obtained by bonding each polarizing plate to an organic electroluminescence display through a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples,% and parts representing the content or amount are based on the weight unless otherwise specified.

In addition, the thickness of the film was measured as follows.

(1) Measurement of Film Thickness

Quot; MH-15M " manufactured by Nikon Corporation.

[Production of Polarizer]

A polyvinyl alcohol film (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) having a thickness of 20 占 퐉 was uniaxially stretched by about 5 times by dry stretching and immersed in pure water at 60 占 폚 for one minute And then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain a polarizer having a thickness of 7 mu m in which iodine adsorbed and oriented on a polyvinyl alcohol film.

When used as the first polarizer in the front polarizing plate, the first polarizer was manufactured so that the angle formed by the absorption axis of the first polarizer and the short side of the front polarizing plate was 0 占 0.5 占.

On the other hand, when used as the second polarizer in the back side polarizing plate, the second polarizer was manufactured so that the angle formed by the absorption axis of the second polarizer and the short side of the back side polarizing plate was 90 占.

As the protective film, the following were used.

[Protective Film-1]

A triacetyl cellulose film produced by oblique stretching manufactured by Konica Minolta Corporation; Re (450) / Re (590) / Re (590) = 0.71, Re (450) / KC4UGR-HC (thickness 44 mu m, in-plane retardation value at wavelength 590 nm = 106 nm, thickness direction retardation at 75 nm, (550) = 0.96, Re (630) / Re (550) = 1.02) having a slow axis inclined at 45 ° with respect to the MD (flow direction) and having a shrinkage ratio of 0.2% And the elastic modulus in the direction of the slow axis was 2500 MPa.

[Protective Film-2]

A cycloolefin resin film (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 13 탆 was used. Retardation in the thickness direction (Rth (590)) = 3.4 nm at the wavelength of 590 nm and retardation in the thickness direction (Rth (483) at the wavelength of 483 nm) ) = 3.5 nm, and the thickness direction retardation (Rth (755)) at a wavelength of 755 nm = 2.8 nm.

[Protective Film-3]

(Thickness 20 占 퐉, in-plane retardation value at a wavelength of 590 nm = 1.2 nm, thickness direction retardation value at a wavelength of 590 nm = 1.3 nm) manufactured by Konica Minolta Corporation.

[Protective Film-4]

A stretched acrylic resin film; An in-plane retardation value at a wavelength of 590 nm = 3 nm, and a thickness direction retardation at a wavelength of 590 nm = -3 nm. The shrinkage rate was 0.1% in the slow axis direction and the elastic modulus in the slow axis direction at 85 DEG C was 1,800 MPa.

[Reflective Polarizer]

A brightness enhancement film (manufactured by 3M, trade name: Advanced Polarized Film, Version 3) having a thickness of 26 탆 was used.

[Preparation of waterborne adhesives]

3 parts of a carboxyl group-modified polyvinyl alcohol (KL-318, manufactured by Kabushiki Kaisha Kuraray Co., Ltd.) was dissolved in 100 parts of water. To the aqueous solution was added a polyamide epoxy additive (Sumi Chemical Industries, Reze Resin (registered trademark) 650 (30), aqueous solution having a solid concentration of 30%] was added to prepare an aqueous adhesive.

[Pressure-sensitive adhesive layer-1]

A commercially available pressure-sensitive adhesive sheet in which an acrylic pressure-sensitive adhesive layer having a thickness of 20 占 퐉 was laminated on the release-treated surface of a polyethylene terephthalate film (release film) having a thickness of 38 占 퐉 subjected to release molding was used. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.05 MPa at 23 캜 and 0.04 MPa at 80 캜.

[Pressure-sensitive adhesive layer-2]

An organic solvent solution obtained by adding a urethane acrylate oligomer and an isocyanate crosslinking agent to a copolymer of butyl acrylate and acrylic acid was applied to a releasable surface of a polyethylene terephthalate film (release film) having a thickness of 38 탆 subjected to releasing treatment, To a thickness of 5 탆 after drying, and dried to obtain a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer was laminated. The pressure-sensitive adhesive layer had a storage elastic modulus at 23 占 폚 of 0.40 MPa and a storage elastic modulus at 80 占 폚 of 0.18 MPa.

(Example 1)

[Production of Front-side Polarizer-1]

On one side of the first polarizer, a protective film-1 as a first protective film was laminated via an aqueous adhesive. A protective film-2 as a second protective film was laminated on the surface opposite to the surface on which the first protective film was laminated in the first polarizer, through an aqueous adhesive in the same manner.

After the lamination, the first protective film, the first polarizer and the second protective film were bonded by drying at 80 ° C for 5 minutes.

The first pressure-sensitive adhesive layer laminated on the release film was bonded to the surface of the second protective film opposite to the surface to which the first polarizer was bonded.

In Example 1, an angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer was 60 °.

[Production of Back-Side Polarizer-1]

On one side of the second polarizer, a protective film-3 as a back side protective film was laminated through an aqueous adhesive. After lamination, the laminate was dried at 80 DEG C for 5 minutes to join the back side protective film and the second polarizer. A pressure-sensitive adhesive layer-2 as a third pressure-sensitive adhesive layer laminated on a release film was bonded to the surface of the second polarizer opposite to the bonding surface with the back-side protective film.

A pressure-sensitive adhesive layer-1 as a second pressure-sensitive adhesive layer laminated on a release film was bonded to a surface of the back surface side protective film opposite to the bonding surface with the second polarizer.

Further, the absorption axis direction of the second polarizer and the longer side direction of the protective film were bonded so as to be parallel to each other.

Thus, a polarizer plate precursor A-1 was produced in which the second pressure-sensitive adhesive layer, the back-side protective film, the second polarizer and the third pressure-sensitive adhesive layer were laminated in this order.

The release film on the third pressure-sensitive adhesive layer in the polarizer plate precursor was peeled off. The third pressure-sensitive adhesive layer in the polarizer plate precursor A-1 and the brightness enhancement film were joined to form a second pressure-sensitive adhesive layer, a back-side protective film, a second polarizer, a third pressure- To obtain a back side polarizer.

Table 1 shows the relationship among various axis angles in the thus obtained polarizing plate.

Also in Examples 2 to 6 and Comparative Examples 1 to 5, a polarizing plate was produced in the same manner as described above. The relationship of the axis angles in the polarizing plate and the like are shown in Tables 1 and 2.

(Example 7)

"Front polarizing plate-2" is used as the front polarizing plate and "back polarizing plate-1" is used as the back polarizing plate.

[Production of front polarizing plate -2]:

A protective film-2 as a second protective film is laminated on one side of the first polarizer through an aqueous adhesive. After the lamination, the second protective film and the first polarizer are bonded by drying at 80 DEG C for 5 minutes. A protective film-4 as a first protective film is laminated on a surface of the first polarizer opposite to the surface on which the second protective film is laminated, via a UV-curable adhesive. After the lamination, ultraviolet light is irradiated to bond the first protective film and the first polarizer.

The first pressure-sensitive adhesive layer laminated on the release film is bonded to the surface of the second protective film opposite to the surface to which the first polarizer is bonded.

In the seventh embodiment, the angle formed by the slow axis of the first protective film and the absorption axis of the first polarizer is 60 °.

The polarizing plates are also manufactured in the same manner as in Example 7 for Examples 8 to 12 and Comparative Examples 6 to 10. The relationship of the axis angles in the polarizing plate and the like are shown in Tables 3 and 4.

Evaluation of properties of polarizer

The obtained polarizing plates were evaluated according to the following measuring methods.

(High Temperature / High Humidity Test)

Manufacture of test specimens

The front polarizing plate was cut into 155 mm long side × 96 mm short side (having the absorption axis of the polarizing plate in the short side direction).

The release film on the first pressure-sensitive adhesive layer on the cut front polarizing plate was peeled off and bonded to a glass plate having a thickness of 0.4 mm and a length of 160 mm x 102 mm on the longer side through the first pressure-sensitive adhesive layer. On the surface of the glass plate opposite to the surface bonded with the front-side polarizing plate, a long side 155 mm long × 96 mm long (with the absorption axis of the polarizing plate in the long side direction) through an acrylic pressure sensitive adhesive layer (second pressure sensitive adhesive layer) ) Was bonded to the back-side polarizing plate.

(Bending in a high temperature environment)

In the laminate having the configuration of the front side polarizing plate / the glass plate / the back side polarizing plate, the laminate was left for 250 hours under an environment of 85 캜 and 5% humidity such that the front polarizing plate was on the upper side. A sample was taken out from the high-temperature environment, and a laminate was placed on the measurement table of a two-dimensional measuring instrument (NEXIV (registered trademark) MR-12072, manufactured by Nikon Corporation) such that the front polarizing plate was on the upper side.

Subsequently, the surface of the measurement table was focused, and 25 points on the surface of the laminate having the configuration of the front side polarizing plate / glass plate / back side polarizing plate were focused on each of them, and the height from the reference focus Were measured. The difference between the maximum value and the minimum value of the height at the measurement point of 25 points was defined as the bending amount. Fig. 4 is a schematic view showing the measurement point of the deflection amount. Reference numeral 40 denotes a " measurement point ", reference numeral 50 denotes a polarizing plate, and reference numeral 60 denotes a glass plate.

The 25 "measurement points" are points in a region inside 7 mm from the end of the polarizing plate, and are disposed at intervals of about 20 mm in the short side direction and about 35 mm in the long side direction.

The determination was made as follows. The results are shown in Table 1 (Examples) and Table 2 (Comparative Examples). The results of Example 7 and the like are shown in Table 3 (Example) and Comparative Example 6, and the results are shown in Table 4 (Comparative Example). Further, in the examples, no lifting or peeling of the film was observed in any of the samples.

The case where the warping amount of a glass sample set at a high temperature environment was 0.8 mm or less was defined as "? &Quot;.

And " x " was taken when the warpage of the glass sample settled in a high-temperature environment was more than 0.8 mm.

(Warp in the humidity environment)

Side polarizing plate / glass / front-side polarizing plate, the front-side polarizing plate was placed on the upper side for 250 hours under the environment of 60 ° C and 90% humidity. The laminate was placed on the measurement target of a two-dimensional measuring instrument (NEXIV (registered trademark) MR-12072, manufactured by Nikon Corporation) such that the front-side polarizing plate was on the upper side. The measurement was carried out in the same manner as in the test in a high temperature environment.

The determination was made as follows. The results are shown in Table 1 (Examples) and Table 2 (Comparative Examples). Further, in the examples, no lifting or peeling of the film was observed in any of the samples.

&Quot;? &Quot; when the warpage of the glass sample settled under a humid environment was 0.8 mm or less.

The case where the warping amount of the glass sample settled under a humid environment was less than 1.0 mm was defined as "? &Quot;.

&Quot; x " was defined as a case where the warping amount of the glass sample settled under a humid environment was 1.0 mm or more.

From these results, the polarizing plate set of the present invention can obtain a thin polarizing plate set. Further, even when the polarizing plate is exposed under a humid environment under a high-temperature condition, warping of the laminated body including the polarizing plate is suppressed.

As described above, the polarizing plate set of the present invention is considered to be free from the peeling off of the touch panel and the detachment of the backlight unit because the amount of warping is small when the polarizing plate set of the present invention is placed in a humid environment or a high temperature environment. In addition, even when exposed under a high temperature / wet heat environment, display unevenness caused by warping is reduced.

According to the present invention, for example, a polarizer and a polarizer set in which warpage of a reflection-type polarizer is suppressed are provided.

10 front polarizer
11 First protective film
12 First polarizer
13 First pressure-sensitive adhesive layer
20 back polarizer
21 second pressure-sensitive adhesive layer
22 Backside protection film
23 second polarizer
24 Third pressure-sensitive adhesive layer
25 reflective polarizer
30 liquid crystal cell
40 measuring point
50 polarizer plate
60 glass plate

Claims

A polarizing plate set comprising a front-side polarizing plate disposed on one side of a liquid crystal cell and a back-side polarizing plate disposed on the other side,
Wherein the front polarizer comprises a first protective film and a first polarizer, and the first protective film and the first polarizer are stacked in this order from a side farther from the liquid crystal cell,
The first protective film has a shrinkage ratio of 0.1 to 1.0% in the direction of the slow axis when it is left standing for 100 hours in an environment of 85 占 폚 and humidity of 5%
The elastic modulus in the slow axis direction at 85 캜 is 1000 MPa to 3000 MPa,
The angle formed between the slow axis of the first protective film and the absorption axis of the first polarizer is 60 ° or more and 90 ° or less,
And the back-surface-side polarizer has a second polarizer.

The polarizing plate set according to claim 1, wherein a ratio of a long side to a short side of the front side polarizing plate is 1.2: 1 to 2: 1.

The polarizer set according to claim 1 or 2, wherein the absorption axis of the first polarizer in the front side polarizer and the short side of the front side polarizer are 0 ° ± 1 °.

The polarizing plate set according to any one of claims 1 to 3, wherein the thickness of the first polarizer is 15 占 퐉 or less.

The polarizing plate set according to any one of claims 1 to 4, wherein the thickness of the first protective film is 10 to 50 탆.

The polarizing plate set according to any one of claims 1 to 5, wherein the back-surface-side polarizing plate further comprises a reflection-type polarizing plate.

A liquid crystal cell and a pair of polarizers disposed on both sides thereof,
The pair of polarizing plates is the polarizing plate set according to any one of claims 1 to 6,
A first polarizer, a liquid crystal cell, and a second polarizer are stacked in this order.