KR20110131114A - A liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to decrease the non-uniformity of a display by preventing a liquid crystal panel from being bent at moisture and heat environment. CONSTITUTION: A liquid crystal cell(10) includes a liquid crystal layer(15) interposed between two cell substrates(11,12). A front polarization plate(20) is laminated on the vision side of the liquid crystal cell through a first adhesive layer(41). A rear polarization plate(30) is laminated on the opposite side to the vision side of the liquid crystal cell through a second adhesive layer(42). A backlight unit(60) is arranged outside the rear polarization plate. The front polarization plate includes a polarization film(31) and a pair of transparent protection films(32,33).

Description

Liquid Crystal Display {A LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device in which the warpage of the liquid crystal panel is reduced.

In recent years, liquid crystal display devices are rapidly spreading as information display devices such as mobile phones, portable information terminals, computer monitors, televisions, etc., taking advantage of low power consumption, low voltage, light weight, and thinness. With the development of liquid crystal technology, liquid crystal display devices of various modes have been proposed, and problems of liquid crystal display such as response speed, contrast and narrow viewing angle have been solved. However, since a polarizing plate is used for the liquid crystal display device, when the liquid crystal panel is placed in a moist heat environment, the polarizing plate is warped due to absorption of water, which causes a problem of display unevenness.

In JP 2007-292966-A, it is proposed to improve the curvature of a liquid crystal panel under high temperature, high humidity by adjusting the dimensional change rate of the polarizing plate bonded to both surfaces of a liquid crystal cell. Moreover, in JP 2003-50313-A, it is proposed to improve the curvature of a liquid crystal panel in a wet heat environment by using the polarizing plate in which the adhesive layer which shows a specific clip characteristic was formed. However, in these improvements, it was necessary to perform pretreatment such as heat treatment on the polarizing plate, or the improvement of display unevenness due to the warpage of the liquid crystal panel after being placed in a wet heat environment was insufficient.

On the other hand, a retardation film comprising a three-layer structure formed with a skin layer containing a (meth) acrylic resin composition containing rubber particles on both sides of the core layer containing styrene resin, and provides a negative intrinsic birefringence, and the polarizing plate and There is also an attempt to apply to a liquid crystal display device in combination. For example, in JP 2009-258589-A, a transparent protective film is bonded to one side of the polarizing film via an adhesive, and on both sides of the core layer containing the styrene resin described above via an adhesive layer on the other side of the polarizing film. The retardation film of the three-layered structure in which the skin layer containing the (meth) acrylic-type resin composition containing a rubber particle was formed is bonded together, and it is set as a composite polarizing plate, and it is described to apply this to a liquid crystal display device. In JP 2009-258589-A, the pressure-sensitive adhesive layer for bonding the retardation film of the three-layer structure to the polarizing film is formed from a high elastic adhesive having a storage modulus of 0.1 MPa or more at a temperature of 80 ° C., thereby improving durability against temperature change. It was.

An object of the present invention is to provide a liquid crystal display device having a small warpage and a small display unevenness even after being placed in a moist heat environment. The present inventors first laminate a transparent protective film on one side of the polarizing film via an adhesive, and on the other side of the polarizing film, laminating a biaxial retardation film having a positive intrinsic birefringence through the adhesive, and on the outside of the biaxial retardation film Especially the composite polarizing plate which laminates the retardation film of the 3-layered structure in which the skin layer containing the (meth) acrylic-type resin composition containing a rubber particle was formed on both surfaces of the core layer containing said styrene resin via an adhesive layer. A patent application was found (JP 2010-217870-A), which was found to provide excellent viewing angle characteristics when applied to an IPS mode liquid crystal display device. However, the durability in the harsher environment that assumed a practical place such as a moist heat environment could not be satisfied yet.

Further, as a result of further research, when the composite polarizing plate proposed in the above JP 2010-217870-A is arranged on the back side of the liquid crystal cell and another polarizing plate is arranged on the front side (viewing side) of the liquid crystal cell, the front side polarizing plate 50 degreeC, respectively about the adhesive layer which adhere | attaches a liquid crystal cell, the adhesive layer which adhere | attaches a back side polarizing plate and a liquid crystal cell, and the biaxial retardation film in the back side polarizing plate, and the retardation film of the said three-layered structure, respectively. It has been found that adjusting the storage modulus at is effective in suppressing warpage of the liquid crystal panel after being placed in a moist heat environment and improving display unevenness, thereby completing the present invention.

That is, this invention includes the following.

[1] a liquid crystal cell having two cell substrates and a liquid crystal layer sandwiched therebetween, a front side polarizing plate laminated on the viewing side of the liquid crystal cell via a first adhesive layer, and a second side opposite to the viewing side of the liquid crystal cell A back side polarizing plate laminated through the pressure-sensitive adhesive layer, and a backlight unit disposed outside the back side polarizing plate,

The front side polarizing plate has a polarizing film and a pair of transparent protective films disposed on both sides thereof, and is laminated on the liquid crystal cell via the first pressure sensitive adhesive layer on one of the transparent protective films,

A back side polarizing plate is a polarizing film, the 1st transparent protective film arrange | positioned at one side of this polarizing film, the 2nd transparent protective film arrange | positioned at the other side of this polarizing film, and the said polarizing film of the 2nd transparent protective film It has a phase difference film laminated | stacked through the 3rd adhesive layer on the opposite side, and is laminated | stacked on the said liquid crystal cell through the said 2nd adhesive layer in the phase difference film side,

The retardation film includes a three-layered structure in which a skin layer containing a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer containing a styrene resin,

The first pressure sensitive adhesive layer, the second pressure sensitive adhesive layer, and the third pressure sensitive adhesive layer each have a storage modulus at 50 ° C. in a range of 0.01 MPa or more and 0.1 MPa or less.

[2] The liquid crystal display device according to the above [1], wherein the transparent protective film located on the liquid crystal cell side of the front polarizing plate has a thickness direction retardation in the range of -10 to 10 nm.

[3] The liquid crystal display device according to [1] or [2], wherein the transparent protective film located on the liquid crystal cell side of the front polarizing plate contains cellulose resin or polyolefin resin.

[4] any one of the above [1] to [3], between the second transparent protective film constituting the back side polarizing plate, that is, the polarizing film and the retardation film (there is a side closer to the liquid crystal cell from the polarizing film). The transparent protective film located at contains polyolefin resin, the in-plane retardation is in the range of 30-150 nm, the in-plane slow axis direction, the in-plane fastening axis direction, and the thickness direction When the refractive index of is n _x , n _y and n _z , respectively, the Nz coefficient defined by Equation 1 below has refractive index anisotropy in a range of more than 1 and less than 2,

The retardation film which comprises a back side polarizing plate has the refractive index anisotropy whose in-plane retardation exists in the range of 20-120 nm, and whose Nz coefficient defined by following formula (1) is more than -2 and less than -0.5.

&Quot; (1) "

Nz = (n _x -n _z ) / (n _x -n _y )

In addition, the in-plane slow axis direction and the in-plane fast axis direction are orthogonal to each other in plane.

According to the present invention, since the warpage of the liquid crystal panel is small even after being placed in a moist heat environment, a liquid crystal display device with less display unevenness can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows the layer structure of the liquid crystal display device which concerns on this invention.

Referring to FIG. 1, the liquid crystal display device of the present invention includes a liquid crystal cell 10, a front side polarizing plate 20 stacked on a viewing side of the liquid crystal cell via a first adhesive layer 41, and a viewing side of the liquid crystal cell. The back side polarizing plate 30 laminated | stacked through the 2nd adhesive layer 42 on the opposite side to this, and the backlight unit 60 arrange | positioned on the outer side (namely, opposite to the liquid crystal cell 10) of this back side polarizing plate It is to be provided. The liquid crystal cell 10, the front side polarizing plate 20 laminated on the viewing side of the liquid crystal cell via the first pressure sensitive adhesive layer 41, and the back side laminated on the opposite side of the liquid crystal cell via the second pressure sensitive adhesive layer 42. The liquid crystal panel 50 is formed with the polarizing plate 30.

The front side polarizing plate 20 disposed on the viewing side of the liquid crystal cell 10 has a polarizing film 21 and a pair of transparent protective films 22 and 23 laminated on both surfaces thereof through an adhesive (not shown). Have As for the back side polarizing plate 30 arrange | positioned on the opposite side to the visual recognition side of the liquid crystal cell 10 (that is, the backlight unit 60 side), the polarizing film 31 and the one side (side far from a liquid crystal cell are The first transparent protective film 32 laminated through an adhesive (not shown) and the second transparent protective film 33 laminated through an adhesive (not shown) on the other side of the polarizing film. The phase difference film 35 is laminated on the liquid crystal cell side of the second transparent protective film 33 via the third pressure sensitive adhesive layer 43. This retardation film 35 has a three-layer structure in which skin layers 37 and 37 containing a (meth) acrylic resin composition containing rubber particles are formed on both surfaces of the core layer 36 containing styrene resin. It is.

A liquid crystal display device is constructed by combining the liquid crystal panel 50 and the backlight unit 60, but when the liquid crystal display device is placed in a moist heat environment, warpage occurs in the liquid crystal panel 50, and a part of the liquid crystal panel 50 is formed. Is abnormally close to the backlight unit 60, or in extreme cases, the display unevenness may occur due to contact. In addition, the liquid crystal panel 50 is fixed with a case or a gold frame so as not to collapse to the visual side, and when the liquid crystal display device is placed in a moist heat environment, warpage occurs in the liquid crystal panel 50, and a part of the liquid crystal panel 50 is caused. There was a case where the display unevenness occurred in contact with the case or the gold frame which fixed it.

Therefore, in this invention, the 2nd adhesive layer for bonding the 1st adhesive layer 41 for bonding the front side polarizing plate 20 to the liquid crystal cell 10, and the back side polarizing plate 30 to the liquid crystal cell 10 is carried out. (42) and the storage elastic modulus G 'at 50 degreeC of the transparent adhesive film 33 which comprises the back side polarizing plate 30, and the 3rd adhesive layer 43 for bonding the retardation film 35 are all 0.01 MPa. It consists of a comparatively soft thing in the range of 0.1 MPa or less. The relationship is that the storage modulus at 50 ° C. of the first pressure sensitive adhesive layer 41 is G ₁ ′, the storage modulus at 50 ° C. of the second pressure sensitive adhesive layer 42 is G ₂ ′, and the third pressure sensitive adhesive layer 43 when the storage elastic modulus at 50 ℃ to G ₃ ', corresponds to that satisfies the equation 2 to 4 below.

<Equation 2>

0.01 MPa≤G ₁ '≤0.1 MPa

&Quot; (3) &quot;

0.01 MPa≤G ₂ '≤0.1 MPa

<Equation 4>

0.01 MPa≤G ₃ '≤0.1 MPa

EMBODIMENT OF THE INVENTION Hereinafter, each member which comprises the liquid crystal display device of this invention is explained in full detail in order, referring the code | symbol attached to FIG.

[Liquid crystal cell]

The liquid crystal cell 10 has two cell substrates 11 and 12 and a liquid crystal layer 15 sandwiched between these substrates. The cell substrates 11 and 12 are generally made of glass, but may be plastic substrates. In addition, the liquid crystal cell 10 itself in the liquid crystal display device of this invention can be comprised with the various thing used in this field | area.

[Polarizing film]

The polarizing films 21 and 31 which comprise the front side polarizing plate 20 and the back side polarizing plate 30 are the process of uniaxially stretching a polyvinyl alcohol-type resin film, and a polyvinyl alcohol-type resin film as a dichroic dye. It manufactures through the process of adsorb | sucking a dichroic dye by dyeing | staining, the process of processing the polyvinyl alcohol-type resin film to which the dichroic dye was adsorbed by boric acid aqueous solution, and the process of washing with water after the process by aqueous boric acid solution.

Polyvinyl alcohol-type resin can be manufactured by saponifying a polyvinyl acetate type resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers copolymerizable with it, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. As another monomer copolymerizable with vinyl acetate, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamide which has an ammonium group, etc. are mentioned, for example.

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

What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method of forming a polyvinyl alcohol-type resin into a film is not specifically limited, It can form into a film by a well-known method. The film thickness of the polyvinyl alcohol-based resin master film is, for example, about 10 to 150 μm, preferably about 10 to 100 μm.

Uniaxial stretching of a polyvinyl alcohol-type resin film can be performed before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. When performing uniaxial stretching after dyeing, this uniaxial stretching may be performed before boric acid treatment, or may be performed during boric acid treatment. Of course, uniaxial stretching can also be performed in several steps shown here. As uniaxial stretching, the method of extending | stretching uniaxially between rolls from which a circumferential speed differs, the method of extending | stretching uniaxially using a heat roll, etc. can be used. In addition, uniaxial stretching may be performed by dry extending | stretching extending | stretching in air | atmosphere, or it may be performed by wet extending | stretching extending | stretching in the state which expanded the polyvinyl alcohol-type resin film using solvents, such as water. The draw ratio is usually about 3 to 8 times.

Dyeing by the dichroic dye of a polyvinyl alcohol-type resin film can be performed by the method of immersing a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye, for example. As a dichroic dye, an iodine or a dichroic organic dye is used specifically ,. In addition, the polyvinyl alcohol-based resin film is preferably subjected to a treatment in which the polyvinyl alcohol-based resin film is swelled by swelling in water before dyeing treatment.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is used normally.

The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is about 20-40 degreeC normally. In addition, the immersion time (dyeing time) in this aqueous solution is about 20 to 1,800 second normally.

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

The boric acid treatment after dyeing with a dichroic dye can be performed by the method of immersing the dyed polyvinyl alcohol-type resin film in boric-acid containing aqueous solution. The content of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When using iodine as a dichroic dye, it is preferable that this boric acid containing aqueous solution contains potassium iodide. The content of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. Immersion time in boric acid containing aqueous solution is about 60 to 1,200 second normally, Preferably it is 150 to 600 second, More preferably, it is 200 to 400 second. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

The polyvinyl alcohol-type resin film after a boric acid process is water-washed normally. A water washing process can be performed by the method of immersing the polyvinyl alcohol-type resin film processed by boric acid, for example in water. The temperature of water in a water washing process is about 5-40 degreeC normally. In addition, immersion time is about 1 to 120 second normally.

After water washing, a drying process is performed and a polarizing film is obtained. A drying process can be performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying treatment, the moisture content in the polarizing film is reduced to the practical level. The moisture content is about 5 to 20 weight% normally, Preferably it is 8 to 15 weight%. When the moisture content is less than 5% by weight, the flexibility of the polarizing film may be lost, resulting in damage or breakage after drying. Moreover, when moisture content exceeds 20 weight%, there exists a tendency for thermal stability to run short.

As described above, the polarizing film in which the dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin film can be produced. The polarizing film obtained can make the thickness about 5-40 micrometers, for example.

[Transparent protective film located in side far from liquid crystal cell]

In each of the front side polarizing plate 20 and the back side polarizing plate 30, the transparent protective films 22 and 32 located on the side far from the liquid crystal cell 10 are materials excellent in transparency, mechanical strength, thermal stability, moisture shielding, and the like. It is preferable that it consists of. As such a material, for example, acrylic resin which has methyl methacrylate type resin as a representative example, chain polyolefin resin which has polypropylene resin as a representative example, cyclic polyolefin resin, cellulose resin, polyethylene terephthalate resin, Polybutylene terephthalate resin, polyvinyl chloride resin, styrene resin, acrylonitrile styrene copolymer resin, acrylonitrile butadiene styrene copolymer resin, polyvinyl acetate resin, polyvinylidene chloride resin , Polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polysulfone resin, polyether sulfone resin, polyarylate resin, polyamideimide resin, polyimide System resin, etc. are mentioned.

These resins can be used individually or in combination of 2 or more types, respectively.

Moreover, resin which performed arbitrary polymer modification about these resin can also be used as a material for transparent protective films. As polymer modification, the copolymerization, crosslinking, molecular terminal modification, stereoregularity control, the mixing including the case where the reaction of heterogeneous polymers is mentioned, etc. are mentioned, for example.

Of the above resins, methyl methacrylate resin, polypropylene resin, cellulose resin or polyethylene terephthalate resin is preferably used as a material for the transparent protective films 22 and 32 located on the side far from the liquid crystal cell 10. do.

Methyl methacrylate type resin is a polymer containing 50 weight% or more of methyl methacrylate units. Content of the methyl methacrylate unit becomes like this. Preferably it is 70 weight% or more, and 100 weight% may be sufficient as it. The polymer whose methyl methacrylate unit is 100 weight% is obtained by superposing | polymerizing methyl methacrylate independently.

Methyl methacrylate type resin can be normally obtained by superposing | polymerizing the monofunctional monomer which has methyl methacrylate as a main component in the coexistence of a radical polymerization initiator and a chain transfer agent. In some cases, a monofunctional monomer may be blended with a component that can be copolymerized with methyl methacrylate and copolymerized. In some cases, a small amount of the polyfunctional monomer may be copolymerized depending on the purpose.

As a monofunctional monomer copolymerizable with methyl methacrylate, for example, 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 esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate and 2-ethylhexyl acrylate; Acrylic acid hydroxyalkyl esters such as hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrenes such as vinyltoluene and α-methylstyrene; Unsaturated nitriles such as acrylonitrile and methacrylonitrile; Unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; Unsaturated imides, such as phenyl maleimide and cyclohexyl maleimide, etc. are mentioned. Each of these monomers may be used alone or in combination with one or more of them.

As a polyfunctional monomer copolymerizable with methyl methacrylate, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di Esterification of both terminal hydroxyl groups of ethylene glycol such as (meth) acrylate or oligomer thereof with acrylic acid or methacrylic acid; Esterification of both terminal hydroxyl groups of propylene glycol or an oligomer thereof with acrylic acid or methacrylic acid; Esterified hydroxyl groups of dihydric alcohols such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate and butanedioldi (meth) acrylate with acrylic acid or methacrylic acid; Esterification of both terminal hydroxyl groups of bisphenol A, alkylene oxide adducts of bisphenol A, or halogen substituents thereof with acrylic acid or methacrylic acid; Esters of polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid; Ring-opening addition of an epoxy group of glycidyl acrylate or glycidyl methacrylate to the terminal hydroxyl group of the compound having two or more hydroxyl groups; Dicyclic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen substituents thereof, or an alkylene oxide adduct thereof, wherein the epoxy group of glycidyl acrylate or glycidyl methacrylate is ring-opened; Allyl (meth) acrylate; Aromatic divinyl compounds, such as divinylbenzene, etc. are mentioned. When copolymerizing a polyfunctional monomer, among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are used preferably.

The modified resin can be used by reacting the functional period of the methyl methacrylate resin. As a reaction of this functional period, the deethanol condensation reaction in the polymer chain of the methyl ester of methyl acrylate and the hydroxyl group of methyl 2- (hydroxymethyl) acrylate, and the carboxyl group of acrylic acid and methyl 2- (hydroxymethyl) acrylate And dehydration condensation reaction in the polymer chain with a hydroxyl group.

Methyl methacrylate resin can obtain a commercial item easily. Examples of commercially available products include "Semipex" sold by Sumitomo Kagaku Co., Ltd., "Acrypt" sold by Mitsubishi Rayon Co., Ltd., and "" sold by Asahi Kasei Co., Ltd. respectively. Del Pet "," Parapet "sold by Kuraray Co., Ltd.," Arch Reviewer "sold by Nihon Shokubai Co., Ltd., etc. are mentioned.

Polypropylene resin is a polymer of the linear olefin monomer which has propylene as a main component, and is usually a linear olefin resin in which 80 weight% or more of a repeating unit consists of propylene. The polypropylene-based resin may be a homopolymer of propylene, or may be a copolymer obtained by copolymerizing a comonomer copolymerizable therein with 1 to 20% by weight, preferably 3 to 10% by weight, based on propylene.

In the case of using a propylene-based copolymer, ethylene, 1-butene and 1-hexene are preferable as comonomers copolymerizable with propylene. Especially, since the polypropylene resin which is comparatively excellent in transparency is obtained, it is preferable to copolymerize ethylene in the ratio of 1 to 20 weight%, Preferably it is 3 to 10 weight%. By making the copolymerization ratio of ethylene into 1 weight% or more, the effect which raises transparency appears. On the other hand, when the copolymerization ratio of ethylene exceeds 20 weight%, melting | fusing point of resin will become low and the heat resistance calculated | required by a transparent protective film may be impaired.

It is preferable that content of the component (CXS component: CXS is abbreviation of cold xylene soluble) soluble in xylene at 20 degreeC is 1 weight% or less, and, as for polypropylene resin, it is more preferable that it is 0.5 weight% or less. Among the polypropylene resins, a homopolymer of propylene having a CXS component of 1% by weight or less and even 0.5% by weight or less is one of preferred examples.

Polypropylene resin can obtain a commercial item easily. Examples of commercially available products include "Prime Polypro" sold by Prime Polymer Co., Ltd., "Novatech" and "Wintech" sold by Nippon Polypro Co., Ltd., Sumitomo Kagaku Co., Ltd. respectively. "Sumitomo Noblen" sold by Sun Aroma Co., Ltd., "Sun Aroma" sold by Sun Aroma Co., Ltd., and the like.

The cellulose resin may be an organic acid ester or mixed organic acid ester of cellulose in which part or all of the hydrogen atoms in the hydroxyl group of the cellulose are substituted with acetyl, propionyl and / or butyryl groups. For example, what consists of an acetate ester of cellulose, a propionic acid ester, butyric acid ester, these mixed ester, etc. is mentioned. Especially, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, etc. are preferable.

Polyethylene terephthalate resin is 80 mol% or more of a repeating unit is resin comprised from ethylene terephthalate, and may contain the other dicarboxylic acid component and / or another diol component. As another dicarboxylic acid component, for example, isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, 1, 4- dicarboxy cyclohexane etc. are mentioned. Examples of other diol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Can be.

These other dicarboxylic acid components and other diol components can also be used in combination of 2 or more type as needed. You may use together hydroxycarboxylic acid, such as p-hydroxy benzoic acid and p- (beta) -hydroxyethoxy benzoic acid. Moreover, as another copolymerization component, the dicarboxylic acid component or diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, etc. can also be used.

As a method for producing a polyethylene terephthalate-based resin, a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as necessary), dialkyl esters and ethylene glycol of terephthalic acid (and other dicaca as necessary) Polycondensation of a dialkyl ester or another diol) of a carboxylic acid with a transesterification reaction, an ethylene glycol ester of terephthalic acid (and other dicarboxylic acid if necessary) (and other diol ester if necessary) in the presence of a catalyst The method of polycondensation under the above is used. Further, if necessary, further solid phase polymerization may be performed to increase the molecular weight or to reduce the low molecular weight component.

The method according to each resin can select suitably the method of forming the above resin into the transparent protective film for polarizing plates. For example, a solvent casting method in which a resin dissolved in a solvent is cast in a metal band or drum, and the solvent is dried to obtain a film, and the resin is heated and kneaded above its melting temperature, kneaded, and extruded and cooled from a die. The melt extrusion method etc. which obtain a film can be used. In the melt extrusion method, a single layer film may be extruded, or a multilayer film may be coextruded.

The film of these resin can obtain a commercial item easily. Examples of commercially available films include methyl methacrylate-based resin films, each of which is sold by Sumitomo Chemical Co., Ltd. under the trade name, and "Acrylite" sold by Mitsubishi Rayon Co., Ltd. And "Acreprene", "Deragrass" sold by Asahi Kasei Co., Ltd., "Paragras" and "Comograss" sold by Kuraray, Nippon Shokubai Co., Ltd. "Arc Reviewer". In the case of a polyethylene terephthalate resin film, there are "Nova Clear" sold by Mitsubishi Chemical Industries, Ltd., "A-PET sheet" sold by Teijin Kasei Co., Ltd. as a brand name, respectively. In the case of the polypropylene resin film, "Pilmax CPP film" sold by FILMAX under the brand name, "Suntox" sold by Suntox Co., Ltd., and Tosello Co., Ltd., respectively. "Tocelo", "Toyobo Pyrene Film" sold by Toyobo Seki Co., Ltd., "Tepan" sold by Toray Film Co., Ltd., "" sold by Nihon Polyace Co., Ltd. Nihon Polyace, and Daiko FC sold by Futamura Kagaku Co., Ltd. In addition, in the case of a cellulose resin film, "Fujitag TD" sold by Fujifilm Co., Ltd., "Konika Minolta TAC film KC" sold by Konica Minolta Opt Co., etc. are mentioned, respectively.

Haze can be provided and the anti-glare property can be expressed to the transparent protective film 22 arrange | positioned far from the liquid crystal cell 10 and becomes a visual recognition side. As a method of providing a haze, for example, a method of mixing inorganic fine particles or organic fine particles into a raw material resin constituting the transparent protective film to form a film, and a resin in which fine particles are mixed and a fine particle are not mixed by multilayer extrusion. A method of forming a layer film or forming a three-layer film using resin mixed with fine particles as an outer layer, coating a coating liquid obtained by mixing inorganic fine particles or organic fine particles with a curable binder resin on one side of the film, curing the binder resin to be antiglare The method of installing a layer, etc. are used.

Examples of the inorganic fine particles used for imparting haze include silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate, and the like. Can be. Examples of the organic fine particles include crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, polyimide particles, and the like.

When providing haze to a transparent protective film, it is preferable to make the haze value become in 6 to 45% of range. When the haze value of a transparent protective film is less than 6%, sufficient anti-glare effect may not appear. On the other hand, when haze value exceeds 45%, the screen of the liquid crystal display device in which this transparent protective film was arrange | positioned may become cloudy, and may cause the fall of image quality. Haze is a value defined as the ratio of the diffuse transmittance to the total light transmittance, and can be measured using a haze meter commercially available in accordance with JIS K 7136. As a commercially available haze meter, "HM-150" etc. which are sold from Murakami Shikisai Kijutsu Co., Ltd., etc. are mentioned, for example. In the case of measuring a haze value, in order to prevent curvature of a film, it is preferable to use the measurement sample which bonded the film surface to the glass substrate so that an anti-glare surface might be the surface using an optically transparent adhesive, for example.

A functional layer including a conductive layer, a hard coating layer, a low reflection layer, and the like disposed on the outer side of the transparent protective film 22 that is disposed far from the liquid crystal cell and becomes the visible side and the transparent protective film 32 that becomes the backlight side. Can be installed. As a coating liquid containing binder resin which comprises the said anti-glare layer, you may select the resin composition which can express such a function.

[Transparent protective film located in liquid crystal cell side]

In the front side polarizing plate 20 and the back side polarizing plate 30 shown in FIG. 1, resin which comprises the transparent protective films 23 and 33 located in the side near the liquid crystal cell 10 from the polarizing films 21 and 31. FIG. As a material, the same thing as what was demonstrated about the transparent protective films 22 and 32 located in the side far from the liquid crystal cell 10 can be used above. Especially, since control of retardation value is easy and availability is easy, polyolefin resin containing cellulose resin, linear polyolefin resin, or cyclic polyolefin resin is used preferably.

The cyclic polyolefin-based resin herein is obtained by polymerizing an alicyclic olefin (sometimes referred to as a "norbornene-based monomer") such as norbornene or another cyclopentadiene derivative in the presence of a catalyst. When such cyclic polyolefin type resin is used, the transparent protective film which has a predetermined retardation value mentioned later is easy to be obtained. Norbornene is a compound in which one carbon-carbon bond of norbornane is a double bond, and is named bicyclo [2,2,1] hept-2-ene according to the IUPAC nomenclature. Examples of norbornene derivatives include tri-substituted, 4-substituted, and 4,5-disubstituted groups having the double bond position of norbornene at 1,2-position. Furthermore, dicyclopentadiene, dimethanooctahydronaphthalene, etc. can also be set as the monomer which comprises cyclic polyolefin type resin.

The cyclic polyolefin-based resin may or may not have a norbornane ring in its structural unit. As a norbornene-type monomer which forms cyclic polyolefin type resin which does not have a norbornane ring in a structural unit, it becomes a 5-membered ring by ring opening, for example, norbornene, dicyclopentadiene, 1- or 4 -Methyl norbornene, 4-phenylnorbornene, etc. are mentioned. When the cyclic polyolefin resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer.

Examples of the cyclic polyolefin-based resin include ring-opening metathesis polymerization of norbornene or a derivative thereof obtained by Diels-Alder reaction from cyclopentadiene and olefins or (meth) acrylic acid or esters thereof as monomers, followed by hydrogen Resin obtained by addition; Resin obtained by ring-opening metathesis polymerization of dicyclopentadiene and olefins or (meth) acrylic acid or esters thereof by a Diels-Alder reaction as a monomer to undergo ring-opening metathesis polymerization, followed by hydrogenation; Resins obtained by ring-opening metathesis copolymerization of likewise at least two monomers selected from norbornene, tetracyclododecene, derivatives thereof and other cyclic olefin monomers, followed by hydrogenation; The resin etc. which are obtained by addition-copolymerizing the aromatic compound which has a chain | strand olefin and / or a vinyl group to cyclic olefins, such as norbornene, tetracyclo dodecene, or derivatives thereof, are mentioned.

Cyclic polyolefin resin can obtain a commercial item easily. Examples of commercially available products are produced from TOPAS ADVANCED POLYMERS GmbH under the trade name, respectively, and sold from TOPAS sold by Polyplastics Co., Ltd. and JSR Co., Ltd. in Japan. "Aton", "Zeonor" and "Zeonex" sold by Nihon Xeon Co., Ltd., "Apel" sold by Mitsui Kagaku Co., Ltd., etc. are mentioned. Films of these cyclic polyolefin resins and stretched films thereof are also commercially available. For example, "Zenonor Film" sold by Nihon Xeon Co., Ltd. under the trade names, "Aton Film" sold by JSR Co., Ltd., There are "S thinner" sold by Sekisui Kagaku Kogyo Co., Ltd.

Typical examples of the chain polyolefin resins are polyethylene resins and polypropylene resins. Among them, homopolymers of propylene or copolymers mainly composed of propylene and copolymerizable with comonomers, for example, ethylene copolymerized at a ratio of 1 to 20% by weight, preferably 3 to 10% by weight, are preferably used. do.

The method according to each resin can select suitably the method of forming into a film from cellulose resin, polyolefin resin, etc .. For example, a solvent casting method in which a resin dissolved in a solvent is cast on a metal band or drum, and the solvent is dried to remove a film to obtain a film. The resin is heated and kneaded above its melting temperature, extruded from a die, and cooled by a cooling drum. The melt extrusion method etc. which obtain a film by this can be used. Among them, the melt extrusion method is preferably used for the polyolefin resin from the viewpoint of productivity. On the other hand, a cellulose resin is generally formed into a film by the solvent casting method.

When the liquid crystal cell 10 is in the in-plane switching (IPS) mode, the liquid crystal cell 10 of the front side polarizing plate 20 in order not to damage the wide viewing angle characteristic inherent in the IPS mode liquid crystal cell. It is preferable that the thickness direction retardation Rth of the transparent protective film 23 located in the side exists in the range of -10-10 nm. Thickness direction retardation Rth is a value obtained by multiplying the film thickness by the value which subtracted the refractive index of the thickness direction from the in-plane average refractive index, and is represented by following formula (5). In addition, in-plane retardation Re is a value obtained by multiplying the thickness of a film by the in-plane refractive index difference, and is represented by following formula (6). From these relations, the Nz coefficient defined by Equation 1 may be expressed by Equation 7 below.

<Equation 5>

Rth = ((n _x + n _y / 2-n _z ) × d

<Equation 6>

Re = (n _x -n _y ) × d

<Equation 7>

Nz = Rth / Re + 0.5

(Wherein n _x , n _y and n _z are as defined above, n _x is the refractive index in the in-plane slow axis direction, n _y is the refractive index in the in-plane fast axis direction (direction perpendicular to the slow axis in plane), n _z is the refractive index in the thickness direction, d is the thickness of the film)

Here, the retardation value may be a value at any wavelength in the range of about 500 to 650 nm which is near the center of visible light, but in this specification, the retardation value at wavelength 590 nm is taken as a standard. Thickness direction retardation Rth and in-plane retardation Re can be measured using various commercially available retarders.

As a method of controlling the thickness direction retardation Rth of a resin film in the range of -10-10 nm, the method of making the distortion which remains in the thickness direction as small as possible when a film is produced is mentioned. For example, in the above-mentioned solvent casting method, the method etc. which relieve residual shrinkage distortion of the thickness direction which generate | occur | produces when drying this flexible resin solution by heat processing can be used. On the other hand, in the above-mentioned melt extrusion method, the distance from the die to the cooling drum is shortened as much as possible in order to prevent the resin film from being stretched between the die and the cooling, and the extrusion amount and the cooling drum are rotated. The method of controlling a speed | rate so that a film may not be stretched, etc. can be used. Moreover, similarly to the solvent casting method, the method of alleviating the distortion which remains in the obtained film by heat processing can also be used.

[Transparent protective film 33 located on the liquid crystal cell side from the polarizing film of the back side polarizing plate]

In the back side polarizing plate 30 used by this invention, it is preferable that the transparent protective film 33 located in the side near the liquid crystal cell 10 from the polarizing film 31 contains polyolefin resin.

Here, polyolefin resin is resin containing structural units derived from linear olefins, such as ethylene and a propylene, or alicyclic olefins, such as norbornene and other cyclopentadiene derivatives, as mentioned above. The polyolefin resin may be a copolymer using two or more kinds of monomers. As for the cyclic polyolefin resin and the chain polyolefin resin which are examples of the polyolefin resin, the same explanation as in the above-mentioned [transparent protective film located on the liquid crystal cell side] is applied. Especially, as polyolefin resin, cyclic polyolefin resin which is resin which mainly contains the structural unit derived from alicyclic olefin is used preferably.

Moreover, the film containing the mixed resin containing 2 or more types of polyolefin resin, and the film containing the mixed resin of polyolefin resin and another thermoplastic resin can also be used for this transparent protective film 33. For example, as mixed resin containing 2 or more types of polyolefin resin, the mixture of cyclic polyolefin resin and chain polyolefin resin as mentioned above is mentioned. When using the mixed resin of polyolefin resin and another thermoplastic resin, the other thermoplastic resin is suitably selected according to the objective. Specific examples include polyvinyl chloride resins, cellulose resins, polystyrene resins, acrylonitrile / butadiene / styrene copolymer resins, acrylonitrile / styrene copolymer resins, (meth) acrylic resins, polyvinyl acetate resins, and polyvinyl chloride resins. Den-based resin, polyamide-based resin, polyacetal-based resin, polycarbonate-based resin, modified polyphenylene ether-based resin, polybutylene terephthalate-based resin, polyethylene terephthalate-based resin, polyphenylene sulfide-based resin, poly Sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyarylate resin, liquid crystalline resin, polyamideimide resin, polyimide resin, polytetrafluoroethylene resin and the like. These thermoplastic resins can be used individually or in combination of 2 or more types, respectively.

When using the mixed resin of polyolefin resin and another thermoplastic resin, content of another thermoplastic resin is about 50 weight% or less with respect to the whole resin normally, and about 40 weight% or less is preferable. By carrying out content of another thermoplastic resin in this range, the absolute value of a photoelastic coefficient is small, it can show the favorable wavelength dispersion characteristic, and the film excellent in durability, mechanical strength, and transparency can be obtained.

The film containing polyolefin resin may contain other components, such as a residual solvent, a stabilizer, a plasticizer, anti-aging agent, an antistatic agent, a ultraviolet absorber, as needed in the range which does not impair the objective of this invention. Moreover, in order to make surface roughness small, you may contain a leveling agent.

The transparent protective film 33 constituting the back side polarizing plate 30 contains the above-described polyolefin-based resin, and its in-plane retardation Re is in the range of 30 to 150 nm, and Nz defined by the above formula (1). It is preferable that the coefficient has refractive index anisotropy in the range of more than 1 and less than 2. Nz coefficient having refractive index anisotropy in the range of more than 1 and less than 2 means that the following expression (8) is satisfied.

<Equation 8>

1 <(n _x -n _z ) / (n _x -n _y ) <2

The polyolefin resin film having refractive index anisotropy as described above can be obtained by known monoaxial stretching, tenter transverse stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like, and the draw ratio and In addition to adjusting the stretching speed appropriately, various temperatures such as preheating temperature, stretching temperature, heat set temperature, cooling temperature, and the like at the time of stretching can be appropriately selected.

It is preferable that the thickness of the extending | stretched polyolefin resin film used as the transparent protective film 33 exists in the range of 20-80 micrometers, and it is more preferable to exist in the range which is 40-80 micrometers. If the thickness of the film is less than 20 µm, the film is difficult to handle, and a predetermined retardation value tends to be difficult to express. On the other hand, if the thickness exceeds 80 µm, the workability is deteriorated and the transparency is lowered or obtained. The weight of a polarizing plate may become large.

[Adhesion of polarizing film and protective film]

In the bonding of the polarizing film 21 and the transparent protective films 22 and 23 in the front side polarizing plate 20, and the bonding of the polarizing film 31 and the transparent protective films 32 and 33 in the back side polarizing plate 30, Usually an adhesive is used. The adhesive layer which bonds a polarizing film and a transparent protective film can be about 0.01-30 micrometers in thickness, Preferably it is 0.01-10 micrometers, More preferably, it is 0.03-5 micrometers. When the thickness of an adhesive bond layer exists in this range, lifting and peeling do not generate | occur | produce between the transparent protective film laminated | stacked and a polarizing film, and the adhesive force which is satisfactory practically is obtained.

In formation of an adhesive bond layer, an appropriate adhesive agent can be used suitably according to the kind and objective of a to-be-adhered body, and anchor coating agent can also be used as needed. Examples of the adhesive include a solvent adhesive, an emulsion adhesive, a pressure-sensitive adhesive, a rehumidifying adhesive, a polycondensation adhesive, a solvent-free adhesive, a film adhesive, a hot melt adhesive, and the like.

One of the preferred adhesives includes an aqueous adhesive, ie, an adhesive component dissolved or dispersed in water. Examples of the adhesive component soluble in water include polyvinyl alcohol resins. Moreover, the urethane type resin which has a hydrophilic group is mentioned as an example of the adhesive component which can be disperse | distributed in water. Aqueous adhesives can be prepared by mixing these adhesive components with water with additional additives blended as needed. Examples of commercially available polyvinyl alcohol-based resins that can be aqueous adhesives include "KL-318" (trade name), which is a carboxyl group-modified polyvinyl alcohol sold by Kuraray Co., Ltd.

The aqueous adhesive may contain a crosslinking agent as necessary. Examples of the crosslinking agent include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, polyvalent metal salts, and the like. When polyvinyl alcohol-type resin is used as an adhesive component, aldehyde compounds including glyoxal, methylol compounds including methylolmelamine, water-soluble epoxy resins and the like are preferably used as the crosslinking agent.

Here, the water-soluble epoxy resin is a poly obtained by reacting epichlorohydrin with a polyamide polyamine which is a reaction product of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid. Amide epoxy resins. As an example of the commercial item of water-soluble epoxy resin, "Sumirez resin 650 (30)" (brand name) etc. which are sold from Sumica Chemtex Co., Ltd. are mentioned.

A polarizing plate can be obtained by apply | coating an aqueous adhesive to the adhesive surface of a polarizing film and / or a transparent protective film, bonding both, and performing a drying process. Prior to the adhesion, it is also effective to increase the wettability by applying an easy adhesion treatment such as a saponification treatment, a corona discharge treatment or a plasma treatment to the transparent protective film. Drying temperature can be made into about 60-100 degreeC, for example. After the drying treatment, curing for about 1 to 10 days at a temperature slightly higher than room temperature, for example, at a temperature of about 30 to 50 ° C. is preferable in further increasing the adhesive force.

As another preferable adhesive agent, the curable adhesive composition containing the epoxy compound hardened | cured by irradiation of an active energy ray or heating is mentioned. A curable epoxy compound is what has at least 2 epoxy group in a molecule | numerator here. In this case, adhesion of a polarizing film and a transparent protective film can be performed by the method of irradiating or heating an active energy ray with respect to the application layer of this adhesive composition, and hardening the curable epoxy compound contained in an adhesive agent. Hardening of an epoxy compound is generally performed by cationic polymerization of an epoxy compound. In addition, it is preferable to perform this hardening by irradiation of an active energy ray from a productivity viewpoint.

From the viewpoint of weather resistance, refractive index, cationic polymerizability and the like, it is preferable that the epoxy compound contained in the curable adhesive composition does not contain an aromatic ring in the molecule. As an epoxy compound which does not contain an aromatic ring in a molecule | numerator, a hydrogenated epoxy compound, an alicyclic epoxy compound, an aliphatic epoxy compound, etc. can be illustrated. Although the epoxy compound preferably used for such a curable adhesive composition is demonstrated in detail in Unexamined-Japanese-Patent No. 2004-245925, the outline is also demonstrated here.

The hydrogenated epoxy compound may be obtained by glycidyl etherifying a hydrogenated polyhydroxy compound obtained by selectively performing a hydrogenation reaction on an aromatic polyhydroxy compound which is a raw material of an aromatic epoxy compound in the presence of a catalyst and under pressure. . As an aromatic polyhydroxy compound which is a raw material of an aromatic epoxy compound, For example, bisphenols, such as bisphenol A, bisphenol F, bisphenol S; Novolak-type resins such as phenol novolak resin, cresol novolak resin and hydroxybenzaldehyde phenol novolak resin; Polyfunctional compounds, such as tetrahydroxy diphenylmethane, tetrahydroxy benzophenone, and a polyvinyl phenol, etc. are mentioned. Glycidyl etherization can be carried out by subjecting such an aromatic polyhydroxy compound to a hydrogenation reaction and reacting epichlorohydrin with the resulting hydrogenated polyhydroxy compound. Preferred hydrogenated epoxy compounds include glycidyl ethers of hydrogenated bisphenol A.

An alicyclic epoxy compound is a compound which has at least one epoxy group couple | bonded with an alicyclic ring in a molecule | numerator. The "epoxy group bonded to an alicyclic ring" means a crosslinked oxygen atom -O- in the structure represented by the following formula, in which m is an integer of 2 to 5.

Is a compound, which groups are bonded to the different chemical structure of the (CH ₂₎ removal of one or a plurality of hydrogen atoms in the form of _m in the formula, it can be a cycloaliphatic epoxy compound. In addition, (CH _{2) m} 1 one or a plurality of hydrogen atoms to form a cycloaliphatic sikhwan is, it is a straight chain alkyl group such as methyl group or ethyl group may be appropriately substituted. Among the alicyclic epoxy compounds, epoxy compounds having an oxabicyclohexane ring (m = 3 in the above formula) or an oxabicycloheptan ring (m = 4 in the above formula) are preferable because they exhibit excellent adhesion. Is used. Hereinafter, the specific example of an alicyclic epoxy compound is given. Here, a compound name is given first as an example, and the chemical formula corresponding to each is shown after that, The same code | symbol is attached | subjected to a compound name and the corresponding chemical formula.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,

B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,

C: ethylene bis (3,4-epoxycyclohexanecarboxylate),

D: bis (3,4-epoxycyclohexylmethyl) adipate,

E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,

F: diethylene glycol bis (3,4-epoxycyclohexylmethyl ether),

G: ethylene glycol bis (3,4-epoxycyclohexylmethyl ether)

H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrisspiro [5.2.2.5.2.2] henic acid,

I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,

J: 4-vinylcyclohexene dioxide,

K: limonene dioxide,

L: bis (2,3-epoxycyclopentyl) ether,

M: dicyclopentadiene dioxide and the like.

The aliphatic epoxy compound may be a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. More specifically, diglycidyl ether of propylene glycol; Diglycidyl ether of 1,4-butanediol; Diglycidyl ether of 1,6-hexanediol; Triglycidyl ether of glycerin; Triglycidyl ether of trimethylolpropane; Polyglycidyl ether of polyether polyol (for example, diglycidyl ether of polyethylene glycol) obtained by adding alkylene oxide (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols, such as ethylene glycol, propylene glycol, and glycerin Etc. can be mentioned.

In the curable adhesive composition, an epoxy compound may be used individually by 1 type, and may use 2 or more types together. Especially, it is preferable that this epoxy compound contains the alicyclic epoxy compound which has at least one epoxy group couple | bonded with an alicyclic ring in a molecule | numerator.

The epoxy compound used in the curable adhesive composition typically has an epoxy equivalent in the range of 30 to 3,000 g / equivalent, and the epoxy equivalent is preferably in the range of 50 to 1,500 g / equivalent. When the epoxy compound whose epoxy equivalent is less than 30 g / equivalent is used, the flexibility of the polarizing plate after hardening may fall, or adhesive strength may fall. On the other hand, in the compound which has an epoxy equivalent exceeding 3,000 g / equivalent, compatibility with the other component contained in an adhesive composition may fall.

From the viewpoint of reactivity, cationic polymerization is preferably used as the curing reaction of the epoxy compound. For this purpose, it is preferable to mix | blend a cationic polymerization initiator with the curable adhesive composition containing an epoxy compound. The cationic polymerization initiator generates cationic species or Lewis acids by irradiation or heating of active energy rays such as visible light, ultraviolet light, X-rays and electron beams, and initiates the polymerization reaction of epoxy groups. From the viewpoint of workability, it is preferable that the potential be imparted to the cationic polymerization initiator. Hereinafter, a cationic species or Lewis acid is generated by irradiation of an active energy ray, and a cationic polymerization initiator for initiating the polymerization reaction of an epoxy group is called a "photo cationic polymerization initiator", and a cationic species or Lewis acid is generated by heat to generate an epoxy group. The cationic polymerization initiator for initiating the polymerization reaction is referred to as "thermal cationic polymerization initiator".

The method of hardening an adhesive composition by irradiation of an active energy ray using a photocationic polymerization initiator enables hardening at normal temperature, the need to consider the distortion by the heat resistance or expansion of a polarizing film is reduced, It is advantageous in that a polarizing film can be adhere | attached favorably. Moreover, since a photocationic polymerization initiator acts catalytically in light, even if it mixes with an epoxy compound, it is excellent in storage stability and workability.

As a photocationic polymerization initiator, For example, Aromatic diazonium salt; Onium salts, such as an aromatic iodonium salt and an aromatic sulfonium salt, an iron- arene complex, etc. are mentioned. The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of epoxy compounds, Preferably it is 1 weight part or more, More preferably, it is 15 weight part or less.

When the compounding quantity of a photocationic polymerization initiator is less than 0.5 weight part with respect to 100 weight part of epoxy compounds, hardening becomes inadequate and there exists a tendency for the mechanical strength and adhesive strength of hardened | cured material to fall.

On the other hand, when the compounding quantity of a photocationic polymerization initiator exceeds 20 weight part with respect to 100 weight part of epoxy compounds, since the ionic substance in hardened | cured material increases, the hygroscopicity of hardened | cured material may become high and durability performance may fall.

When using a photocationic polymerization initiator, curable adhesive composition can contain a photosensitizer further as needed. By using a photosensitizer, the reactivity of cationic polymerization can be improved and the mechanical strength and adhesive strength of hardened | cured material can be improved. As a photosensitizer, a carbonyl compound, an organic sulfur compound, a persulfide, a redox type compound, an azo compound, a diazo compound, a halogen compound, a photoreductive dye etc. are mentioned, for example. When mix | blending a photosensitizer, it is preferable to make the quantity into the range of 0.1-20 weight part with respect to 100 weight part of curable adhesive compositions.

On the other hand, as the thermal cationic polymerization initiator, benzylsulfonium salt, thiophenium salt, thiolanium salt, benzyl ammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, amineimide and the like can be given.

The curable adhesive composition containing the epoxy compound is preferably cured by photocationic polymerization as described above, but may be cured by the presence of the above thermal cationic polymerization initiator and by thermal cationic polymerization, and may be photocationic polymerization and thermal cationic polymerization. You can also use together. When using photocationic polymerization and thermal cationic polymerization together, it is preferable to contain both a photocationic polymerization initiator and a thermal cationic polymerization initiator in curable adhesive composition.

Moreover, curable adhesive composition may further contain the compound which accelerate | stimulates cationic polymerization, such as an oxetane compound and a polyol compound. Oxetane compounds are compounds having a four-membered ring ether in the molecule. When compounding an oxetane compound, the amount is 5 to 95 weight% normally in curable adhesive composition, Preferably it is 5 to 50 weight%. In addition, the polyol compound may be an alkylene glycol including ethylene glycol, hexamethylene glycol, polyethylene glycol, or the like or an oligomer thereof, polyester polyol, polycaprolactone polyol, polycarbonate polyol, or the like. When mix | blending a polyol compound, the quantity is 50 weight% or less normally, Preferably it is 30 weight% or less in curable adhesive composition.

In addition, the curable adhesive composition may contain other additives such as ion traps, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, antifoaming agents, and the like, as long as the adhesive properties are not impaired. It may contain. Examples of the ion trapping agent include inorganic compounds including powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, mixed systems thereof, and the like. Hindered phenol type antioxidant etc. are mentioned.

The curable adhesive composition containing the epoxy compound is coated on the adhesive side of the polarizing film or the transparent protective film, or both sides thereof, and then bonded at the side where the adhesive is coated, and uncured by irradiating or heating the active energy ray. The cured adhesive layer can be cured to bond the polarizing film and the transparent protective film. As a coating method of an adhesive agent, various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, can be used, for example.

Although this curable adhesive composition can be basically used as a non-solvent type | mold adhesive which does not contain a solvent substantially, since each coating system has the optimal viscosity range, respectively, you may contain a solvent for viscosity adjustment. It is preferable that it is an organic solvent which melt | dissolves each component including an epoxy compound satisfactorily, without reducing the optical performance of a polarizing film, For example, hydrocarbons represented by toluene, esters represented by ethyl acetate, etc. can be used. Can be.

When hardening an adhesive composition by irradiation of an active energy ray, although the above-mentioned various things can be used as an active energy ray, ultraviolet-ray is used preferably because it is easy to handle and control of the amount of irradiation light etc. is also easy. Irradiation intensity and irradiation amount of an active energy ray, for example, ultraviolet rays, may be suitably maintained in a range that does not affect various optical performances including polarization degree of the polarizing film and various optical performances including transparency and phase difference characteristics of the transparent protective film. Determined appropriately.

When hardening an adhesive composition with heat, it can heat by a generally known method. Usually, heating is performed more than the temperature which the thermal cationic polymerization initiator mix | blended with curable adhesive composition generate | occur | produces a cationic species and a Lewis acid, and specific heating temperature is about 50-200 degreeC, for example.

[Retardation film]

The retardation film 35 arrange | positioned at the liquid crystal cell 10 side of the back side polarizing plate 30 has the (meth) acrylic-type resin composition in which the core layer 36 contains a styrene resin, and contains rubber particle in the both surfaces. Skin layers 37 and 37 are formed.

The styrenic resin constituting the core layer 36 may not only be a homopolymer of styrene or a derivative thereof, but may also be a binary or more copolymer of styrene or a derivative thereof with another copolymerizable monomer. Here, a styrene derivative is a compound in which another group couple | bonded with styrene, For example, alkyl, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2, 4- dimethyl styrene, o-ethyl styrene, p-ethyl styrene, Substituent styrene which the hydroxyl group, the alkoxy group, the carboxyl group, and halogen groups were introduce | transduced into the benzene nucleus of styrene, such as styrene and hydroxy styrene, tert- butoxy styrene, vinyl benzoic acid, o-chloro styrene, and p-chloro styrene, etc. are mentioned. Can be. Ternary copolymers as disclosed in JP 2003-50316-A or JP 2003-207640-A can also be used. The styrene resin is preferably a copolymer of styrene or a styrene derivative with at least one monomer selected from acrylonitrile, maleic anhydride, methyl methacrylate and butadiene. It is preferable that the styrene resin which comprises the core layer 36 is heat resistant, and generally, the glass transition temperature ("Tg") is 100 degreeC or more. More preferable Tg of styrene resin is 120 degreeC or more.

It is preferable to set the core layer 36 containing styrene resin so that the thickness may be 10-100 micrometers. When the thickness is less than 10 micrometers, sufficient retardation value may be hard to express by extending | stretching. On the other hand, when the thickness exceeds 100 µm, the impact strength of the film tends to be weak, and the retardation change due to external stress tends to be large, and white dropout or the like tends to occur when applied to a liquid crystal display device. Display performance tends to be degraded.

The skin layers 37 and 37 arrange | positioned on both surfaces of the core layer 36 containing said styrene resin contain the (meth) acrylic-type resin composition in which rubber particle is mix | blended with (meth) acrylic-type resin. Here, as (meth) acrylic-type resin, the homopolymer of methacrylic acid alkylester or acrylate alkylester, the copolymer of methacrylic acid alkylester, and acrylate alkylester etc. are mentioned, for example. Specific examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate and propyl methacrylate. Specific examples of the alkyl acrylate include methyl acrylate, ethyl acrylate and propyl acrylate. As this (meth) acrylic-type resin, what is marketed as a general purpose (meth) acrylic-type resin can be used. The (meth) acrylic resins include those called impact-resistant (meth) acrylic resins and those called high heat-resistant (meth) acrylic resins having a glutaric anhydride structure and a lactone ring structure in the main chain.

It is preferable that the rubber particle mix | blended with (meth) acrylic-type resin is an acryl-type. Acrylic rubber particles are particles having rubber elasticity obtained by polymerizing an alkyl acrylate such as butyl acrylate or 2-ethylhexyl acrylate as a main component and polymerizing in the presence of a polyfunctional monomer. Such rubber elastic particles may be formed in a single layer, or may be a multilayer structure having at least one rubber elastic layer. As the acrylic rubber particles having a multi-layer structure, the particles having rubber elasticity as described above are used as nuclei, the surroundings are covered with a hard alkyl methacrylate polymer, and the hard alkyl methacrylate polymer is used as the nucleus. And the periphery thereof covered with an acrylic polymer having rubber elasticity as described above, a periphery of the hard core covered with an acrylic polymer having rubber elasticity, and a periphery thereof covered with a hard alkyl methacrylate polymer. Can be. These rubber particles are usually in the range of 50 to 400 nm in average diameter of the particles formed of the elastic layer.

Content of the said rubber particle in the (meth) acrylic-type resin composition which comprises the skin layer 37 is about 5-50 weight part normally per 100 weight part of (meth) acrylic-type resin. Since (meth) acrylic-type resin and acryl-type rubber particle | grains are marketed in the state which mixed these, the commercial item can be used. As an example of the commercial item of the (meth) acrylic-type resin in which the acryl-type rubber particle was mix | blended, "HT55X", "Technology S001" etc. which are sold from Sumitomo Chemical Co., Ltd. are mentioned. Such a (meth) acrylic-based resin composition generally has a Tg of 160 ° C or lower, but the preferable Tg is 120 ° C or lower, and more preferably 110 ° C or lower.

It is preferable that the skin layers 37 and 37 containing the (meth) acrylic resin composition in which rubber particles, preferably acrylic rubber particles are blended, have a thickness of 10 to 100 µm. If the thickness is to be less than 10 m, the film forming tends to be difficult. On the other hand, when thickness exceeds 100 micrometers, there exists a tendency which can not ignore the retardation of this (meth) acrylic-type resin layer.

As described above, in the retardation film 35 used in the present invention, the core layer 36 containing styrene-based resin preferably has a Tg of 120 ° C. or higher, and on the other hand, a (meth) acrylic resin composition containing rubber particles It is preferable that the skin layer 37 containing the Tg is 120 degrees C or less, and also 110 degrees C or less. It is preferable that both Tg do not overlap and the core layer 36 containing a styrene resin has higher Tg than the skin layer 37 containing the (meth) acrylic-type resin composition in which rubber particle was mix | blended.

In order to manufacture the retardation film 35 used for this invention, the (meth) acrylic-type resin composition in which styrene resin and rubber particle were mix | blended is coextruded, for example, the film of a three-layer structure is formed into a film, and it extends | stretches after that. Can be. In addition, after producing a film of each single layer, the method of heat | fusing by heat-lamination and extending | stretching it is also possible.

In this retardation film 35, the three-layer structure in which the skin layers 37 and 37 containing the (meth) acrylic-type resin composition in which rubber particle was mix | blended was formed in both surfaces of the core layer 36 containing styrene resin. do. In this three-layer structure, the skin layers 37 and 37 disposed on both surfaces are usually almost the same thickness. Thus, by setting it as a three-layer structure, the skin layers 37 and 37 containing the (meth) acrylic-type resin composition in which rubber particle was mix | blended function as a protective layer, and it becomes excellent in mechanical strength and chemical-resistance.

In-plane retardation is provided to the retardation film 35 comprised as mentioned above by extending | stretching. Stretching can be performed by known all-day stretching, tenter transverse stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like, and stretching can be performed to obtain a desired retardation value.

In the retardation film 35 used in the present invention, the in-plane retardation Re is in the range of 20 to 120 nm, and it is preferable that the Nz coefficient defined by Equation (1) has refractive index anisotropy in the range of more than -2 and less than -0.5. Do. The Nz coefficient having refractive index anisotropy in the range of more than -2 and less than -0.5 means that the following equation (9) is satisfied.

&Quot; (9) &quot;

-2 <(n _x -n _z ) / (n _x -n _y ) <-0.5

[Production of Back Side Polarizing Plate]

The back side polarizing plate 30 is configured by laminating the phase difference film 35 on the transparent protective film 33 surface via the third pressure sensitive adhesive layer 43. Although the method of laminating | stacking the retardation film 35 is not specifically limited, Usually, the 3rd adhesive layer 43 is formed in the surface of the transparent protective film 33 or the retardation film 35 first. Such an adhesive layer can be formed not only by the method of apply | coating and drying the adhesive solution which mainly uses the base polymer as mentioned above to the transparent protective film 33 or the retardation film 35, but also performed the mold release process. The adhesive layer formed on the release process surface of the support film (separator) (an adhesive with a separator) is prepared, and it also forms by the method of bonding it to the surface of the transparent protective film 33 or the retardation film 35 in the adhesive layer side. Can be. In addition, as another method, after forming an adhesive layer on the said separator first, the method etc. which transfer on the polarizing plated transparent protective film 33 or the retardation film 35 can also be used. In this way, the separator containing the resin film in which the process was performed by mold release agents, such as a silicone type, can also be laminated | stacked on the adhesive layer formed.

Moreover, when forming an adhesive layer on the surface of the transparent protective film 33 or the retardation film 35, for improving adhesiveness to the adhesive layer forming surface of the transparent protective film 33 or the retardation film 35 as needed. Treatment, for example, corona treatment, or the like, may be carried out, and the same treatment may be performed on the surface of the pressure-sensitive adhesive layer bonded to the transparent protective film 33 or the retardation film 35.

Bonding of the transparent protective film 33 and the retardation film 35 is performed by the technique known conventionally, For example, the slow axis of a retardation film is orthogonal to the polarization transmission axis of a polarizing film using a bonding roll etc. It is performed by the method of laminating so that it may become parallel, or the method of laminating so that the slow axis of retardation film may become a predetermined angle with respect to the polarization transmission axis of a polarizing film.

[Adhesive layer]

The first adhesive layer 41 is laminated on the transparent protective film 23 serving as the liquid crystal cell side of the front side polarizing plate 20 described above, and the second adhesive layer 41 is disposed on the phase difference film 35 serving as the liquid crystal cell side of the back side polarizing plate 30. The adhesive layer 42 is laminated. In addition, the transparent protective film 33 and the retardation film 35 which comprise the back side polarizing plate 30 are adhere | attached through the 3rd adhesive layer 43 as mentioned above. The 1st adhesive layer 41 and the 2nd adhesive layer 42 are provided in order to bond the front side polarizing plate 20 and the back side polarizing plate 30 to both sides of the liquid crystal cell 10, respectively.

Although the adhesive which forms each adhesive layer may be excellent in optical transparency and the adhesive characteristic including wettability, cohesion, adhesiveness, etc. may be suitably given, the thing excellent in durability etc. is further used preferably. Specifically, the adhesive (acrylic adhesive) containing acrylic resin is used suitably as an adhesive which forms an adhesive layer.

Acrylic resin contained in an acrylic adhesive is resin which makes alkyl acrylate esters, such as butyl acrylate, ethyl acrylate, isooctyl acrylate, and 2-ethylhexyl acrylate, the main monomer. The polar monomer is usually copolymerized with this acrylic resin. A polar monomer is a compound which has a polymerizable unsaturated bond and a polar functional group. Here, it is common that a polymerizable unsaturated bond is derived from a (meth) acryloyl group, and a polar functional group may be a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc. As a specific example of a polar monomer, the carboxyl group-containing monomer which has (meth) acrylic acid as a representative example, the hydroxyl group containing monomer which has 2-hydroxypropyl (meth) acrylic acid or 2-hydroxyethyl (meth) acrylic acid as a representative example, ( Amide group-containing monomers having meth) acrylamide as a representative example, epoxy group-containing monomers having 2-N, N-dimethylaminoethyl (meth) acrylate and glycidyl (meth) acrylate as representative examples.

In addition, a crosslinking agent is mix | blended with an acrylic adhesive normally with acrylic resin.

Representative examples of the crosslinking agent include an isocyanate compound having at least two isocyanate groups (-NCO) in the molecule.

Various additives may further be mix | blended with an adhesive. As a preferable additive, a silane coupling agent, an antistatic agent, etc. are mentioned. A silane coupling agent is effective in raising adhesive force with glass. Antistatic agents are effective in reducing or preventing the generation of static electricity. Generally, when a polarizing plate is affixed to a liquid crystal cell through an adhesive layer, after peeling the surface protection film (separator) which covered and adhered and protected the adhesive layer until then, it bonds to a liquid crystal cell, but peels off the surface protection film. The static electricity generated at the time of occurrence causes defective alignment of the liquid crystal in the liquid crystal cell, and this phenomenon may cause display failure of the liquid crystal display device. As means for reducing or preventing the generation of such static electricity, the combination of the antistatic agent to the pressure-sensitive adhesive is effective.

[Storage Modulus of Adhesive]

In the present invention, the first pressure-sensitive adhesive layer 41, the second pressure-sensitive adhesive layer 42, and the third pressure-sensitive adhesive layer 43 are all configured to have a storage elastic modulus at 50 ° C in a range of 0.01 MPa or more and 0.1 MPa or less. Thus, by making all the pressure-sensitive adhesive layers relatively soft, even if the liquid crystal display device is exposed to a moist heat environment, the stress applied to the liquid crystal cell can be alleviated due to the dimensional change of the polarizing plate, and the curvature of the liquid crystal panel is suppressed. If the storage modulus at 50 ° C. of any one of the pressure-sensitive adhesive layers exceeds 0.1 MPa, the stress applied to the liquid crystal cell due to the dimensional change of the polarizing plate cannot be sufficiently relaxed, and the liquid crystal panel is warped when placed in a moist heat environment. There is a fear that display unevenness may occur due to this increase. On the other hand, when the storage elastic modulus is less than 0.01 MPa, there exists a tendency for sufficient adhesive force to become difficult to be obtained. Various methods are used to make the storage modulus at 50 ° C. to be 0.01 MPa or more and less than 0.1 MPa. However, for example, the desired storage modulus can be achieved by adjusting the amount of the crosslinking agent.

The pressure-sensitive adhesive layers 41, 42, and 43 prepare a pressure-sensitive adhesive composition in which the pressure-sensitive adhesive component as described above is dissolved in an organic solvent, and directly apply the pressure-sensitive adhesive layer to the surface of the film on which the pressure-sensitive adhesive layer should be formed, and dry remove the solvent. The above-mentioned pressure-sensitive adhesive composition is applied to the mold release treatment surface of the base film including the resin film subjected to the releasing treatment or by the coating method, and the solvent is dried to remove the pressure-sensitive adhesive layer and adhered to the surface of the target film. It can be formed by a transfer method. When the adhesive layers 41, 42, 43 are formed on the surface of the target film by the direct coating method of the former, the resin film (also called a separator) by which the mold release process was performed was bonded to the surface, and an adhesive layer is used until use. It is customary to protect the surface temporarily. The latter transfer method is widely used in view of the handleability of the pressure-sensitive adhesive composition, which is an organic solvent solution. It is also preferable that it can.

(Back light unit)

The backlight unit 60 includes a light source member for supplying light for display to the liquid crystal cell 10 at least. This light source member has a form called a side light type composed of a light guide plate and a light source disposed on one side or an opposing side of the light guide plate, but a plurality of light sources and light disposed on the side (the side facing the liquid crystal cell 10). It may be a type called a direct type composed of a diffusion plate. In any form, the light reflection layer is normally provided in the form of a sheet or an application layer on the rear surface of the light source member (side away from the liquid crystal cell 10). Moreover, one layer or multiple layers may be arrange | positioned at the light output side (side toward the liquid crystal cell 10) of a light source member, such as a light collecting sheet and a diffusion film. The backlight unit 60 itself has each member described herein, and can be any configuration used in this field.

[Example]

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, parts and% indicating the content to the amount of use are based on weight unless otherwise specified. In addition, the measurement of each physical property in the following examples was performed by the following method.

(1) retardation value and Nz coefficient

Using a retarder "KOBRA-21ADH" based on the parallel Nicole rotation method manufactured by Oji Keisukuki Co., Ltd., the light was irradiated with a wavelength of 590 nm at a temperature of 23 ° C, and the in-plane retardation was measured. At the same time, the thickness direction retardation or Nz coefficient was measured.

(2) storage modulus of pressure-sensitive adhesive

The storage elastic modulus (G ') of an adhesive manufactures the cylindrical test piece of diameter 8mm X thickness 1mm from the adhesive of a measurement object, and uses a dynamic viscoelasticity measuring apparatus (dynamic analyzer RDA II: product made from REOMETRIC). It was measured under conditions of initial distortion of 1 N and a temperature of 50 ° C. by a torsional shearing method with a frequency of 1 Hz.

In addition, the following two types of adhesive sheets were used in the following examples.

(3) Adhesive Sheet A:

A pressure-sensitive adhesive layer containing an acrylic copolymer mainly composed of butyl acrylate and an isocyanate-based crosslinking agent is formed on a release treated surface of a polyethylene terephthalate film having a thickness of 38 μm and subjected to a release treatment (called “separator”) to a thickness of 25 μm. Commercially available adhesive with separator. The storage elastic modulus of this adhesive layer was 0.04 MPa at 50 degreeC.

(4) Adhesive Sheet B:

The release treatment surface of the 38-micrometer-thick polyethylene terephthalate film (called "separator") subjected to the release treatment contains an acrylic copolymer mainly composed of butyl acrylate, an ultraviolet curable component, and an isocyanate-based crosslinking agent. An adhesive with a commercially available separator, on which a hard adhesive layer having a thickness of 25 µm cured is formed. The storage elastic modulus of this adhesive layer was 0.97 MPa at 50 degreeC.

Example 1

(a) Preparation of Water-Based Adhesives

3 parts of carboxyl group-modified polyvinyl alcohol ("KL-318" obtained from Kurare) was dissolved with respect to 100 parts of water, and the polyamide epoxy resin [Sumika Chemtech Co., Ltd.] which is a water-soluble epoxy compound in the aqueous solution. 1.5 parts of "Sumirez resin 650 (30)" obtained from the above, and aqueous solution of 30% of solid content concentration] were added, and the water-based adhesive agent was manufactured.

(b) Preparation of retardation film

Styrene-maleic anhydride copolymer resin ("Dairy D332" (trade name), Tg = 131 degreeC sold from Nova Chemical Co., Ltd.) is made into the core layer, and about 20% of acrylic rubber particles of 200 nm of average particle diameters are mix | blended. Three-layer co-extrusion of methacryl-based resin (resin used in "Technology SO01" (trade name) sold by Sumitomo Chemical Co., Ltd., Tg = 105 ° C) as a skin layer was carried out on both sides of the core layer. The resin 3-layer film in which the skin layer was formed was obtained. This resin 3-layer film was stretched and the retardation film was produced. In-plane retardation of this retardation film was 55.0 nm, and Nz coefficient was -1.1.

(c) transparent protective film

The saponification process was performed to "TD80UL" (brand name) which is a 80-micrometer-thick triacetyl cellulose film obtained from FUJIFILM, and each of the liquid crystal cell 10 of the front side polarizing plate 20 and the back side polarizing plate 30 was carried out. It was set as the transparent protective films 22 and 32 arrange | positioned at the side remote from the side. In addition, "KC4UEW" (brand name) which is a 40-micrometer-thick triacetyl cellulose film obtained from Konica Minolta Opto Co., Ltd. had in-plane retardation of 0.7 nm and thickness direction retardation of -0.1 nm. The saponification process was performed to this and it was set as the transparent protective film 23 arrange | positioned at the liquid crystal cell 10 side of the front side polarizing plate 20. In addition, the 35.8 micrometer-thick cyclic polyolefin type resin film obtained from Nippon Xeon Co., Ltd. had 76.2 nm of in-plane retardation and 1.37 of Nz coefficient. This was made into the 2nd transparent protective film 33 arrange | positioned between the polarizing film 31 and the retardation film 35 in the back side polarizing plate 30. As shown in FIG.

(d) Preparation of Polarizer

The above-mentioned triacetylcellulose film "TD80UL" having a thickness of 80 µm was bonded to one side of a polarized film having a thickness of about 28 µm in which iodine was adsorbed and oriented on the polyvinyl alcohol film, through the water-based adhesive prepared in (a) above. On the other side, the above-mentioned 40-micrometer-thick triacetylcellulose film "KC4UEW" was bonded through the same water-based adhesive agent, and then dried at 80 degreeC for 5 minutes, and the front side polarizing plate 20 was produced.

In addition, a triacetyl cellulose film "TD80UL" having a thickness of 80 µm was bonded to one side of the same polarizing film as above through the same water-based adhesive, and the above-mentioned thickness 35.8 µm through the same water-based adhesive on the other side. The cyclic polyolefin resin film was bonded, and dried at 80 degreeC for 5 minutes after that. Moreover, the slow axis absorbs the retardation film produced by said (b) on the cyclic polyolefin type resin film (2nd transparent protective film 33) through the said adhesive sheet A (thing which peeled separator). It bonded together so that it might become orthogonal to an axis | shaft, and produced the back side polarizing plate 30.

(e) Preparation of polarizing plate with pressure-sensitive adhesive layer

The triacetylcellulose film "KC4UEW" (transparent protective film 23) side of 40 micrometers in thickness of the front side polarizing plate 20 produced by said (d) side, and the phase difference film 35 side of the back side polarizing plate 30 The above-mentioned adhesive sheet A was bonded each to the, and the polarizing plate with an adhesive layer was produced.

Among these, the absorption axis was made long in the front side polarizing plate with an adhesive layer, and the absorption axis was made in the short direction with the back side polarizing plate with an adhesive layer, respectively, and it was wide 32 type size (32-inch diagonal (about 81 cm), width 71 cm *) About 40 cm in height].

(f) Fabrication and Evaluation of Liquid Crystal Display

Wide 32 type [diagonal 32 inches (approximately 81cm), width approximately 71cm X approximately 40cm in height] of IPS mode of Panasonic Corporation make LCD TV "VIERA" (model number: Viera TH-L32X1) It decompose | disassembles and peels the polarizing plate upper and lower liquid crystals, The cross nicol state is carried out to the front side (view side) and the back side (backlight side) of the liquid crystal cell instead of these original polarizing plates with the adhesive layer produced by said (e). The separator was peeled from each adhesive layer so that it might become, and it bonded at the adhesive layer side, and the liquid crystal panel 50 was produced. At this time, it arrange | positioned so that the absorption axis of the front side polarizing plate 20 might become parallel with the orientation direction at the time of the voltageless application (black display) of the liquid crystal molecule in the liquid crystal cell 10. The backlight 60 was further attached to this liquid crystal panel, and it was set as the liquid crystal display device. The backlight of this liquid crystal display is turned on, and 30 minutes later, the contrast ratio at the position of azimuth angle 135 degrees and polar angle 60 degrees using the display viewing angle characteristic measurement evaluation apparatus "EZ contrast 88XL" by ELDIM Corporation ( White luminance / black luminance) was measured. Here, the azimuth angle is an angle when the right side of the screen is set to O ° and the counterclockwise direction is positive when viewed from the viewer side. The azimuth angle 135 ° means the upper left direction of the screen, and the polar angle means the inclination from the screen normal direction. . As a result, the contrast ratio was 326.

(g) Wet heat environment test of liquid crystal panel

The liquid crystal panel 50 produced in said (f) was put out for 96 hours in 40 degreeC and the environment of 95% of relative humidity, and it was taken out, and it was left to stand for 1 day in the environment of the temperature of 22 degreeC and 55% of relative humidity. When this IPS mode liquid crystal display device was reassembled using this liquid crystal panel, the backlight was lighted, and the screen was observed after 1 hour, display unevenness was not observed.

Comparative Example 1 (equivalent to Example 4 of JP 2010-217870-A)

The liquid crystal panel 50 was produced similarly except having used the adhesive sheet B as the 1st adhesive layer 41 of the front side polarizing plate, and the 2nd adhesive layer 42 of the back side polarizing plate, and liquid crystal display The device was assembled and evaluated in the same manner. Contrast ratio was the same as Example 1, but display unevenness was observed 1 hour after the backlight was turned on as a result of the wet heat environment test.

Comparative Example 2

Except having used the adhesive sheet B as the 1st adhesive layer 41 of the front side polarizing plate in Example 1, the liquid crystal panel 50 was produced similarly, the liquid crystal display device was assembled and evaluated similarly. Contrast ratio was the same as Example 1, but display unevenness was observed 1 hour after the backlight was turned on as a result of the wet heat environment test.

Comparative Example 3

Except having used the adhesive sheet B as the 2nd adhesive layer 42 of the back side polarizing plate in Example 1, the liquid crystal panel 50 was produced similarly, the liquid crystal display device was assembled and evaluated similarly. Contrast ratio was the same as Example 1, but display unevenness was observed 1 hour after the backlight was turned on as a result of the wet heat environment test.

About the above Example and the comparative example, the structure of the three adhesive layers and the wet heat environment test result were put together in Table 1.

10... … Liquid crystal cell
11, 12... … Cell substrate
15... … Liquid crystal layer
20... … Front side polarizer
21 ... … Polarizing film
22, 23... … Transparent protective film
30... … Back side polarizer
31... … Polarizing film
32, 33... … Transparent protective film
35 ... … Retardation film
36... … Core layer
37 ... … Skin layer
41... … 1st adhesive layer
42 ... … 2nd adhesive layer
43 ... … Third pressure sensitive adhesive layer
50... … Liquid crystal panel
60 ... … Backlight unit

Claims (4)

A liquid crystal cell having two cell substrates and a liquid crystal layer sandwiched therebetween,
Front side polarizing plate laminated on the viewing side of the liquid crystal cell through the first pressure-sensitive adhesive layer,
A back side polarizing plate laminated on the side opposite to the viewing side of the liquid crystal cell through the second pressure sensitive adhesive layer, and
A backlight unit disposed outside the rear polarizer;
The front side polarizing plate has a polarizing film and a pair of transparent protective films disposed on both sides thereof, and is laminated on the liquid crystal cell via the first pressure sensitive adhesive layer on one of the transparent protective films,
A back side polarizing plate is a polarizing film, the 1st transparent protective film arrange | positioned at one side of this polarizing film, the 2nd transparent protective film arrange | positioned at the other side of this polarizing film, and the said polarizing film of the 2nd transparent protective film It has a phase difference film laminated | stacked through the 3rd adhesive layer on the opposite side, and is laminated | stacked on the said liquid crystal cell through the 2nd adhesive layer in the phase difference film side,
The retardation film includes a three-layer structure in which a skin layer containing a (meth) acrylic resin composition containing rubber particles is formed on both surfaces of a core layer containing a styrene resin,
The first pressure sensitive adhesive layer, the second pressure sensitive adhesive layer, and the third pressure sensitive adhesive layer each have a storage modulus at 50 ° C. in a range of 0.01 MPa or more and 0.1 MPa or less. The liquid crystal display device according to claim 1, wherein the transparent protective film located on the liquid crystal cell side of the front polarizing plate has a thickness direction retardation in a range of −10 to 10 nm. The liquid crystal display device according to claim 1 or 2, wherein the transparent protective film located on the liquid crystal cell side of the front polarizing plate contains cellulose resin or polyolefin resin. The said 2nd transparent protective film which comprises a back side polarizing plate contains polyolefin resin, The in-plane retardation is in the range of 30-150 nm, The in-plane ground in any one of Claims 1-3. When the refractive indexes in the axial direction, in-plane fastening axis direction, and thickness direction are n _x , n _y, and n _z , respectively, the Nz coefficient defined by Equation 1 below is more than 1 but less than 2 Has refractive index anisotropy in the range of
The retardation film which comprises a back side polarizing plate has the refractive index anisotropy whose in-plane retardation exists in the range of 20-120 nm, and whose Nz coefficient defined by following formula (1) is more than -2 and less than -0.5.
<Equation 1>
Nz = (n _x -n _z ) / (n _x -n _y )

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