JP2010079177A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device, having excellent long-term stability of display characteristics depending on a temperature change and a humidity change. <P>SOLUTION: The liquid crystal display device includes: a liquid crystal cell; a viewing side polarizing plate; a backlight side polarizing plate. In the device, a first retardation film satisfying the formulas (1) X1>0 and X2>0 is provided in one of spaces between a polarizer of the viewing side polarizing plate and the liquid crystal cell and between a polarizer of the backlight side polarizing plate and the liquid crystal cell, and a second retardation film satisfying the formulas (2) Y1>0 and Y2<0 is provided in the other thereof, and the lag axes of the respective retardation films are orthogonal to each other (wherein X1 indicates a dimensional change rate in the phase lag axial direction of the first retardation film, X2 indicates a dimensional change rate in the phase advance axial direction of the first retardation film, Y1 indicates a dimensional change rate in the phase lag axial direction of the second retardation film, and Y2 indicates a dimensional change in the phase advance axial direction of the second retardation film). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device excellent in display performance using a retardation film in which a dimensional change rate due to temperature change and humidity change is adjusted.

  In a liquid crystal display device, polarizing plates including retardation films are usually arranged on both sides of a liquid crystal cell, but the environmental temperature and humidity change (for example, change from 60% RH at 25 ° C. to 90% RH at 60 ° C.). Then, Re or Rth of the retardation film in the polarizing plate changes, and there is a problem that display performance changes.

In order to solve the above problem, for example, Patent Document 1 discloses a retardation plate in which at least two retardation plates are laminated, and the dimensional change rate in the slow axis direction (X1)> the dimensional change in the fast axis direction. A retardation plate with a rate (X2) and a retardation plate with a dimensional change rate in the slow axis direction (Y1) <a dimensional change rate in the fast axis direction (Y2) are laminated so that the slow axis is in the same direction. A phase difference plate has been proposed. Further, a phase difference plate having a dimensional change rate in the slow axis direction (X1)> a dimensional change rate in the fast axis direction (X2) is provided on one side of the liquid crystal cell, and a dimensional change rate in the slow axis direction on the other side ( Y1) A liquid crystal display device has been proposed in which retardation plates having a dimensional change rate (Y2) in the fast axis direction are arranged so that the slow axis is in the same direction.
According to this proposal, by laminating a retardation film of X1> X2 and a retardation film of Y1 <Y2, or by arranging the two types of films so that their slow axes are in the same direction (nx−ny) ) Change, that is, Re change. However, when this durability test is actually performed, not only Re change but also Rth change occurs, so there is a problem that display performance changes, and further improvement is desired at present. .

JP 2006-392111 A

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, the present invention suppresses Rth change by arranging retardation films (expanding film and contracting film) having different dimensional change rates when the environmental temperature and humidity are changed on both sides of the liquid crystal cell, and at the same time, By using a phase difference film that has approximately the same dimensional change rate in the axial direction and the fast axis direction, it is possible to suppress changes in display performance by suppressing Re changes, and a liquid crystal display device that does not cause corner unevenness. The purpose is to provide.

In order to solve the above-mentioned problems, the present inventors diligently studied the Re / Rth change factor of the retardation film in the polarizing plate. As a result, (1) irreversible Re / Rth estimated to be caused by the chemical bond change. It was found that the change is represented by the sum of (2) reversible Re / Rth change caused by expansion and contraction of the film.
Further, the reversible Re / Rth change caused by the expansion and contraction of the film in (2) is the change in dimensions (direction and size) of the slow axis and the fast axis of the retardation film and the photoelastic coefficient. It was found that the change direction (+/−) was different depending on the case.
As a result of further diligent investigations by the present inventors based on the above findings, phase difference films (expanding film and contracting film) having different dimensional change rates when the environmental temperature and humidity change are changed on both sides of the liquid crystal cell. In addition to suppressing the Rth change by disposing the film, the change in display performance is suppressed by using the retardation film having the same dimensional change rate in the slow axis direction and the fast axis direction to suppress the Re change. It was found that it is possible to provide a liquid crystal display device that is free from corner unevenness.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A liquid crystal cell, a viewing side polarizing plate provided on the viewing side of the liquid crystal cell, and a backlight side polarizing plate provided on the backlight side of the liquid crystal cell,
Any one between the polarizer of the viewing-side polarizing plate and the liquid crystal cell and between the polarizer of the backlight-side polarizing plate and the liquid crystal cell satisfies the following formula (1). A liquid crystal display device having a retardation film and a second retardation film satisfying the following formula (3) on the other side, wherein the slow axes of the retardation films are orthogonal to each other: .
X1> 0, X2> 0 ... Formula (1)
Y1 <0, Y2 <0 Formula (3)
However, in said Formula (1) and (2), X1 represents the dimensional change rate of the slow axis direction of a 1st phase difference film. X2 represents the dimensional change rate in the fast axis direction of the first retardation film. Y1 represents the rate of dimensional change in the slow axis direction of the second retardation film. Y2 represents the rate of dimensional change in the fast axis direction of the second retardation film.
<2> The liquid crystal display device according to <1>, wherein the first retardation film satisfies the following formula (2) and the second retardation film satisfies the following formula (4).
| X1-X2 | <0.1 (2)
| Y1-Y2 | <0.1 (4)
However, in said formula (3) and (4), X1, X2, Y1, and Y2 represent the same meaning as the above.

  According to the present invention, conventional problems can be solved, and retardation films having different dimensional change rates (expanding retardation film and shrinking retardation film) when the environmental temperature and humidity change are provided on both sides of the liquid crystal cell. In addition to suppressing the Rth change by disposing the film, the change in display performance can be suppressed by using the retardation film in which the dimensional change rate in the slow axis direction and the fast axis direction are approximately equal to each other. This can provide a liquid crystal display device that is free from corner unevenness.

Hereinafter, the liquid crystal display device of the present invention will be described in detail.
In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
In this specification, “parallel” or “orthogonal (vertical)” means that the angle is within a strict angle ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °.
Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction.
The “slow axis direction” means a direction in which the refractive index is maximum, and the “fast axis direction” means a direction perpendicular to the slow axis direction. The measurement wavelength of the refractive index is a value in the visible light region (λ = 550 nm) unless otherwise specified.

In the description of the present embodiment, the in-plane retardation value Re of the measurement object (film) is defined by the following formula (A), and is KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). ), Light having a wavelength λ is incident in the normal direction of the film. In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.
Re = (nx−ny) × d Expression (A)
However, in the mathematical formula (A), nx and ny represent the refractive indexes in the slow axis direction and the fast axis direction in the plane of the measurement object, respectively. D represents the thickness of the measurement object.

When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, the thickness direction retardation value Rth is calculated by the following method.
Rth is the Re in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis) (in the absence of the slow axis, any direction in the film plane) The light of wavelength λnm is incident from each inclined direction in steps of 10 degrees from the normal direction to 50 ° on one side with respect to the film normal direction of the rotation axis), and a total of 6 points are measured. KOBRA 21ADH or WR is calculated based on the retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (B) and formula (C) based on the value, the assumed value of the average refractive index, and the input film thickness value.

... Formula (B)

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In the formula (B), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is orthogonal to nx and ny. Represents the refractive index in the direction.
Rth = ((nx + ny) / 2-nz) × d (C)

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth is calculated by the following method.
Rth is a step of 10 ° from −50 ° to + 50 ° with respect to the normal direction of the film, using Re as an in-plane slow axis (determined by KOBRA 21ADH or WR) as an inclination axis (rotation axis). Then, 11 points of light having a wavelength of λ nm are incident from the inclined direction, and KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value. To do.
In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness.

  The liquid crystal display device of the present invention has a liquid crystal cell, a viewing side polarizing plate provided on the viewing side of the liquid crystal cell, and a backlight side polarizing plate provided on the backlight side of the liquid crystal cell, It has other members as needed.

In the present invention, the following formula (1) is applied to either one between the polarizer of the viewing side polarizing plate and the liquid crystal cell and between the polarizer of the backlight side polarizing plate and the liquid crystal cell. The second retardation film satisfying the following formula (2) is included on the other side, and the slow axis of each retardation film is orthogonal. In this way, when the environmental temperature and humidity are changed, the Rth change can be suppressed by arranging the retardation films having different dimensional change rates on both sides of the liquid crystal cell.
X1> 0, X2> 0 ... Formula (1)
Y1 <0, Y2 <0 Formula (2)
However, in said Formula (1) and (2), X1 represents the dimensional change rate of the slow axis direction of a 1st phase difference film. X2 represents the dimensional change rate in the fast axis direction of the first retardation film. Y1 represents the rate of dimensional change in the slow axis direction of the second retardation film. Y2 represents the rate of dimensional change in the fast axis direction of the second retardation film.

Furthermore, it is preferable that the first retardation film satisfies the following formula (3) and the second retardation film satisfies the following formula (4). Thereby, Re change can be suppressed by using a retardation film in which the dimensional change rate between the slow axis direction and the fast axis direction is substantially equal.
| X1-X2 | <0.1% Formula (3)
| Y1-Y2 | <0.1% ... Formula (4)
However, in said formula (3) and (4), X1, X2, Y1, and Y2 represent the same meaning as the above.

The dimensional change rate of the retardation film becomes a positive value when the film expands and becomes a negative value when the film shrinks.
Here, the dimensional change rate is 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction, 12.0 cm in the slow axis direction, and 3.2.0 in the fast axis direction. Cut out each with a size of 0 cm, and let stand at 25 ° C. and 60% RH for 2 hours or more, and measure the dimensions of the slow axis direction and the fast axis direction with a pin gauge (manufactured by Shinto Kagaku Co., Ltd.) (L1). Thereafter, the film is heated at 60 ° C. and 90% RH for 120 hours, and the dimensions of the film are again measured with a pin gauge (L2). The dimensional change rate can be obtained from [(L2-L1) / L1] × 100.

  Therefore, in the liquid crystal display device of the present invention, the first and second retardation films satisfy the above formula, so that changes in Rth and Re can be suppressed even when the environmental temperature and humidity change, and the display performance. This prevents the occurrence of corner unevenness.

<First and second retardation films>
As the first and second retardation films, known materials are appropriately selected and manufactured so as to satisfy the above formula (1) or formula (2), but a film made of a thermoplastic resin is preferable. It is.
The first retardation film and the second retardation film can be obtained by stretching the thermoplastic resin film. Examples of the stretching include a uniaxial stretching method in the flow direction (slow axis direction) and a biaxial stretching method in which the slow axis direction and a direction perpendicular to the slow axis direction (fast axis direction) are stretched. The draw ratio is usually about 1.01 to 3 times.

  There is no restriction | limiting in particular as a thermoplastic resin in the said thermoplastic resin film, According to the objective, it can select suitably, For example, Polyester, such as a polystyrene and polycarbonate; Polypropylene; Polyester, such as a polyethylene terephthalate and a polyethylene naphthalate; Polyvinyl Cellulose esters such as alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose; cellulose acylate, polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylene oxide, polyallylsulfone , Polyvinyl alcohol, polyamide, polyimide, polyvinyl chloride, cyclic Li olefin resin, or their binary, ternary various copolymers, graft copolymers, and the like blends.

  Among these, a cellulose acylate film is preferable, and cellulose acetate propionate (CAP) and triacetyl cellulose (TAC) are particularly preferable.

-Cellulose acylate film-
As said cellulose acylate film, what is described, for example in Unexamined-Japanese-Patent No. 2008-3126 etc. can be used.
Specifically, the basic principle of the cellulose acylate synthesis method is described in Ueda et al., Wood Chemistry, 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst.
In order to obtain the cellulose acylate, specifically, a cellulose raw material such as cotton linter or wood pulp is pretreated with an appropriate amount of acetic acid, and then esterified by introducing it into a pre-cooled carboxylated mixed solution. Synthesize the rate (total of acyl substitution at the 2nd, 3rd and 6th positions is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After completion of the esterification reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide). Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain the desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added to the cellulose acylate solution), the cellulose acylate is separated, washed and stabilized, and the like. Can be obtained.

In the cellulose acylate film, it is preferable that the polymer component constituting the film is substantially composed of the specific cellulose acylate. “Substantially” means 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the polymer component.
The cellulose acylate is preferably used in the form of particles. 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible.

  The cellulose acylate is obtained by acylating a hydroxyl group of cellulose, and the substituent can be any from an acetyl group having 2 carbon atoms to an acyl group having 22 carbon atoms. Examples of the method for measuring the degree of substitution include a method according to ASTM D-817-91 and an NMR method.

  In the cellulose acylate, the degree of substitution of cellulose with a hydroxyl group is not particularly limited. However, when used for polarizing plate protective films and optical films, the higher the degree of acyl substitution, the better the moisture permeability and hygroscopicity of the film. preferable. For this reason, it is preferable that the acyl substitution degree to the hydroxyl group of a cellulose is 2.50-3.00. Furthermore, the degree of substitution is preferably 2.70 to 2.96, more preferably 2.80 to 2.94.

Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms is not particularly limited and may be an aliphatic group or an allyl group. A mixture of the above may also be used. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, Examples include oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl groups. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are preferable, and acetyl, propionyl and butanoyl are more preferable.
Among these, acetyl groups, mixed esters of acetyl groups and propyl groups are preferred, and acetyl groups are particularly preferred from the viewpoints of ease of synthesis, cost, ease of control of substituent distribution, and the like.

  The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . When the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This is described in detail in JP-A-9-95538.

  Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 4.0, more preferably 2.0 to 3.5, and even more preferably 2.3 to 3.4. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (narrow molecular weight distribution) can be synthesized. When used in the production of the cellulose acylate of the present invention, its moisture content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. It is a cellulose acylate having a rate. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the water content of the cellulose acylate in the present invention, it is necessary to dry it, and the method is not particularly limited as long as the desired water content is obtained. These cellulose acylates of the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

  The cellulose acylate can be used by mixing two or more different types of cellulose acylates such as a substituent, a substitution degree, a polymerization degree, and a molecular weight distribution.

  For the cellulose acylate film, a plasticizer, an ultraviolet absorber, a deterioration preventing agent, a retardation (optical anisotropy) developing agent, a retardation (optical anisotropy) reducing agent, a matting agent (fine particles), if necessary. It is preferable to add a peeling accelerator, an infrared absorber or the like.

〔Polarizer〕
The polarizing plate includes at least a retardation film and a polarizer, and further includes other members as necessary.

-Polarizer-
The polarizer is manufactured by Optiva Inc. And a polarizer composed of a binder and iodine or a dichroic dye are preferable.
The iodine and dichroic dye exhibit polarization performance by being oriented in a binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly such as liquid crystal.
Commercially available polarizers are made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. It is common.
In addition, commercially available polarizers have iodine or dichroic dye distributed about 4 μm from the polymer surface (about 8 μm on both sides), and a thickness of at least 10 μm is necessary to obtain sufficient polarization performance. is there. The penetrability can be controlled by the solution concentration of iodine or dichroic dye, the temperature of the bath, and the immersion time.
Therefore, as described above, the lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of the light leakage phenomenon that occurs when the polarizing plate is used in a liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less. When the thickness is 20 μm or less, the light leakage phenomenon is not observed on a 17-inch liquid crystal display device.

The binder of the polarizer may be cross-linked. As the binder for the polarizer, a polymer that can be crosslinked by itself may be used. Applying light, heat, or pH change to a polymer having a functional group, or a polymer obtained by introducing a functional group into the polymer, reacting the functional group to crosslink between the polymers to form a polarizer. it can.
Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent. It can be formed by cross-linking between binders by introducing a bonding group derived from the cross-linking agent between binders using a cross-linking agent which is a compound having high reaction activity.
In general, the crosslinking can be carried out by applying a coating liquid containing a crosslinkable polymer or a mixture of a polymer and a crosslinking agent on a support and then heating. Since it is only necessary to ensure durability at the stage of the final product, the crosslinking treatment may be performed at any stage until the final polarizing plate is obtained.

As described above, as the binder of the polarizer, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used.
There is no restriction | limiting in particular as said polymer, According to the objective, it can select suitably, For example, polymethylmethacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylol acrylamide) , Polyvinyltoluene, chlorosulfonated polyethylene, nitrocellulose, chlorinated polyolefin (eg polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethylcellulose, polypropylene, polycarbonate and copolymers thereof (eg acrylic acid / methacrylic) Acid copolymer, styrene / maleimide copolymer, styrene / vinyl toluene copolymer, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer It is included. A silane coupling agent may be used as the polymer.
Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are preferred. Particularly preferred.

The saponification degree of the polyvinyl alcohol and modified polyvinyl alcohol is preferably 70% to 100%, more preferably 80% to 100%, and still more preferably 95% to 100%.
The degree of polymerization of the polyvinyl alcohol is preferably 100 to 5,000.
The modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification. In the copolymerization modification, COONa, Si (OH) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ Na, C ₁₂ H ₂₅ can be introduced as a modifying group. In chain transfer modification, COONa, SH, or SC ₁₂ H ₂₅ can be introduced as a modifying group.
The degree of polymerization of the modified polyvinyl alcohol is preferably 100 to 3,000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509, and JP-A-9-316127.
Further, unmodified polyvinyl alcohol having a saponification degree of 85 to 95% and alkylthio-modified polyvinyl alcohol are particularly preferable.
Furthermore, two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The crosslinking agent is described in US Reissue Patent 23297 and can be used in the present invention. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent.
When a large amount of the crosslinking agent for the binder is added, the wet heat resistance of the polarizer can be improved. However, when 50 mass% or more of a crosslinking agent is added to the binder, the orientation of iodine or the dichroic dye is lowered. The addition amount of the crosslinking agent is preferably 0.1% by mass to 20% by mass and more preferably 0.5% by mass to 15% by mass with respect to the binder.
The binder contains some crosslinking agent that has not reacted even after the crosslinking reaction has been completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less and more preferably 0.5% by mass or less in the binder.
When the crosslinking agent is contained in the binder in an amount exceeding 1.0% by mass, there may be a problem in durability. That is, when a polarizer having a large amount of residual crosslinking agent is incorporated in a liquid crystal display device and used for a long time or left in a high-temperature and high-humidity atmosphere for a long time, the degree of polarization may decrease.

Examples of the dichroic dye include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, and anthraquinone dyes. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).
Examples of the dichroic dye include C.I. I. Direct Yellow 12, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 48, C.I. I. Direct Blue 67, C.I. I. Direct Blue 90, C.I. I. Direct Green 59, C.I. I. Acid Red 37 and the like.
With respect to the dichroic dye, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, There are descriptions in 1-265205 and JP-A-7-261024.

  The dichroic dye is used as a free acid or a salt such as an alkali metal salt, an ammonium salt, or an amine salt. By blending two or more types of dichroic dyes, polarizers having various hues can be produced. A polarizer using a compound (pigment) that exhibits a black color when the polarization axes are orthogonal to each other, or a polarizer or a polarizing plate in which various dichroic molecules are blended so as to exhibit a black color, have both a single plate transmittance and a polarization rate. Excellent and preferred.

  The polarizer is preferably dyed with iodine or a dichroic dye after stretching a film made of a binder in the longitudinal direction (MD direction) of the polarizer.

In the case of the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air.
Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times.
The stretching step may be performed in several steps. By dividing into several times, it is possible to stretch more uniformly even at high magnification.
Before stretching, a slight stretching may be performed horizontally or vertically (a degree that prevents shrinkage in the width direction). Stretching can be performed by performing tenter stretching in biaxial stretching in different steps. The biaxial stretching is the same as the stretching method performed in normal film formation.

When the polarizing plate is used in a liquid crystal display device, either between the polarizer of the viewing side polarizing plate and the liquid crystal cell and between the polarizer of the backlight side polarizing plate and the liquid crystal cell, It has 1 phase difference film, and has the 2nd phase difference film on the other, and is arranged so that the slow axis of each phase contrast film may intersect perpendicularly.
An adhesive may be used for bonding the polarizer and the retardation film, for example, polyvinyl alcohol resin (including modified polyvinyl alcohol by acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) or boron An aqueous compound solution can be used as an adhesive. Among these, polyvinyl alcohol resin is preferable.
The thickness of the adhesive layer is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 5 μm after drying.

When the polarizing plate is used in a liquid crystal display device, an antireflection layer is preferably provided on the viewing side surface, and the antireflection layer may also be used as a protective layer on the viewing side of the polarizer.
From the viewpoint of suppressing a change in tint depending on the viewing angle of the liquid crystal display device, the internal haze of the antireflection layer is preferably 50% or more. Specific examples of these are described in JP-A No. 2001-33783, JP-A No. 2001-343646, and JP-A No. 2002-328228.

In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizer is preferably high and the degree of polarization is preferably high.
The transmittance of the polarizer of the present invention is preferably in the range of 30% to 50%, more preferably in the range of 35% to 50%, and in the range of 40% to 50% in the light with a wavelength of 550 nm. It is particularly preferable that
The degree of polarization is preferably in the range of 90% to 100%, more preferably in the range of 95% to 100%, and particularly preferably in the range of 99% to 100% in light having a wavelength of 550 nm. .

[Liquid Crystal Display]
The liquid crystal display device of the present invention includes at least the polarizing plate and a liquid crystal cell, and further includes other members as necessary.

As the liquid crystal cell, for example, TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), OCB (Optical Liquid Crystal). , VA (Vertical Aligned), HAN (Hybrid Aligned Nematic) and other display mode liquid crystal cells can be used. Among these, the VA mode is particularly preferable.
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). (2) Liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) in order to enlarge the viewing angle. (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary Collection 58- 59 (1998)), and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Production Example 1)
-Production of retardation film (1)-
--- Production of cellulose acylate film by band casting machine--
(1) Cellulose acylate 7.8 parts by mass of sulfuric acid and carboxylic acid were added to 100 parts by mass of cellulose, acylated at 40 ° C., and then aged at 40 ° C. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone to obtain cellulose triacetate.

(2) Dissolution <1-1> Cellulose Acylate Solution The following composition was put into a mixing tank, stirred to dissolve each component, and further heated to 90 ° C. for about 10 minutes. It filtered with the sintered metal filter of the hole diameter of 10 micrometers.
-Cellulose acylate solution-
Cellulose acylate: 100.0 parts by mass Triphenyl phosphate (TPP): 8.0 parts by mass Biphenyl diphenyl phosphate (BDP): 4.0 parts by mass Methylene chloride: 403.0 parts by mass-Methanol ... 60.2 parts by mass

<1-2> Matting Agent Dispersion Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a disperser to prepare a matting agent dispersion.
-Matting agent dispersion-
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd. 2.0 parts by mass Methylene chloride 72.4 parts by mass Methanol 10.8 parts by mass Cellulose acylate Solution ... 10.3 parts by mass

<1-3> Additive Solution Next, the following composition containing the cellulose acylate solution prepared by the above method was put into a mixing tank and dissolved by stirring while heating to prepare an additive solution.
-Additive solution-
UV1: 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole)) and UV2: 2 (2′-hydroxy-3 ′, 5′-di-amylphenyl) -5 -Chlorbenzotriazole)) ... 20.0 parts by massMethylene chloride ... 58.3 parts by massMethanol ... 8.7 parts by massCellulose acylate solution ... 12.8 parts by mass

  100 parts by mass of the cellulose acylate solution, 1.35 parts by mass of the matting agent dispersion, and an additive solution in an amount such that the addition amount of the retardation developer is 2.2 parts by mass, and triphenyl phosphate ( A dope for film formation was prepared by mixing a plasticizer solution in an amount of 7.8 parts by mass of TPP) and 3.9 parts by mass of biphenyldiphenyl phosphate (BDP). The addition ratio of the additive is shown in parts by mass when the amount of cellulose acylate is 100 parts by mass.

  The above dope was cast with a band casting machine. The film stripped from the band with a residual solvent amount of 55% is stretched in the machine direction at a stretch ratio of 5% in the section from stripping to the tenter, and then stretched in the width direction at a stretch ratio of 40% using the tenter. Then, after shrinking (relaxing) in the width direction by 7% immediately after transverse stretching, the film was detached from the tenter to form a cellulose acylate film. The residual solvent amount of the film when the tenter was removed was 12%. Both ends were cut off in front of the winding part to make a width of 2000 mm and wound up as a roll film having a length of 4000 m.

<Measurement of ΔRe and ΔRth>
About the produced cellulose acylate film (retardation film (1)), the result of measuring Re retardation value and Rth retardation value at a wavelength of 590 nm at 25 ° C. and 60% RH with KOBRA WR (manufactured by Oji Scientific Instruments) Re = 50 nm and Rth = 120 nm, respectively. For the retardation film, Rth (λ) was calculated with an average refractive index of 1.48. Thereafter, thermostatting was performed for 120 hours under conditions of 60 ° C. and 90 RH%, and Re and Rth of the film were measured again. As a result, Re = 51 nm and Rth = 111 nm (ΔRe = + 1 nm, ΔRth = −9 nm).

<Measurement of dimensional change rate>
The obtained retardation film (1) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2), leave at 25 ° C. and 60% RH for 2 hours or longer, and measure the dimension of the film in the slow axis direction of sample 2 and the dimension of the film in the fast axis direction of sample 1 It measured with the pin gauge (made by Shinto Kagaku Co., Ltd.) (L1). Thereafter, thermostatting was performed for 120 hours under the conditions of 60 ° C. and 90% RH, and the dimensions of the film were again measured with a pin gauge (L2). And the dimensional change rate was calculated | required from [(L2-L1) / L1] * 100. It was -0.27% in the slow axis direction and -0.24% in the fast axis direction (the film was contracted).

<Measurement of elastic modulus>
The obtained retardation film (1) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2) and conditioned in an environment of 25 ° C. and 60% RH for 24 hours. The elastic modulus was measured according to the method described in JIS K7127 for sample 2 in the slow axis direction and for sample 1 in the fast axis direction. Tensilon manufactured by A & D Co., Ltd. was used as the tensile tester, the test piece was 50 mm × 10 mm, the distance between chucks was 30 mm, and the test speed was 30 mm / min.

<Measurement of photoelastic coefficient>
The obtained retardation film (1) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out with a size of 0.0 cm (sample 2), sample 2 is applied with tensile stress in the slow axis direction, sample 1 is applied with tensile stress in the fast axis direction, and the retardation at that time is determined by ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Production Example 2)
-Production of retardation film (2)-
In Production Example 1, a cellulose acylate solution was produced in the same manner as in Production Example 1 except that the addition amount of the retardation enhancer was adjusted to 2.9 parts by mass when the cellulose acylate solution was produced.
The above dope was cast with a band casting machine. The film stripped from the band with a residual solvent amount of 75% is stretched in the longitudinal direction at a stretch ratio of 8% in the section from stripping to the tenter, and then stretched in the width direction at a stretch ratio of 50% using the tenter. Then, after shrinking (relaxing) in the width direction by 7% immediately after transverse stretching, the film was detached from the tenter to form a cellulose acylate film. The residual solvent amount of the film when the tenter was removed was 20%.

<Measurement of ΔRe and ΔRth>
With respect to the produced cellulose acylate film (retardation film (2)), the Re retardation value and the Rth retardation value at a wavelength of 590 nm at 25 ° C. and 60% RH were Re = 50 nm and Rth = 120 nm, respectively.
For the retardation film (2), Rth (λ) was calculated with an average refractive index of 1.48. Thereafter, thermostatting was performed for 120 hours under conditions of 60 ° C. and 90% RH, and Re and Rth of the film were measured again. As a result, Re = 55 nm and Rth = 113 nm (ΔRe = + 6 nm, ΔRth = −7 nm).

<Measurement of dimensional change rate>
The obtained retardation film (2) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2), leave at 25 ° C. and 60% RH for 2 hours or longer, and measure the dimension of the film in the slow axis direction of sample 2 and the dimension of the film in the fast axis direction of sample 1 It measured with the pin gauge (made by Shinto Kagaku Co., Ltd.) (L1). Thereafter, the film was heated at 60 ° C. and 90% RH for 120 hours, and the dimensions of the film were again measured with a pin gauge (L2). And the dimensional change rate was calculated | required from [(L2-L1) / L1] * 100. As a result, the dimensional change rate was −0.15% in the slow axis direction and −0.26% in the fast axis direction (the film was contracted).

<Measurement of elastic modulus>
The obtained retardation film (2) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2) and conditioned in an environment of 25 ° C. and 60% RH for 24 hours. The elastic modulus was measured according to the method described in JIS K7127 for sample 2 in the slow axis direction and for sample 1 in the fast axis direction. Tensilon manufactured by A & D Co., Ltd. was used as the tensile tester, the test piece was 50 mm × 10 mm, the distance between chucks was 30 mm, and the test speed was 30 mm / min.

<Measurement of photoelastic coefficient>
The obtained retardation film (2) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out with a size of 0.0 cm (sample 2), sample 2 is applied with tensile stress in the slow axis direction, sample 1 is applied with tensile stress in the fast axis direction, and the retardation at that time is determined by ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Production Example 3)
-Production of retardation film (3)-
<1-1> Cellulose ester solution Methylene chloride and ethanol were added to the pressure dissolution tank, and the cellulose ester was added to the pressure dissolution tank containing the solvent while stirring. This was heated and completely dissolved with stirring, and a plasticizer and an ultraviolet absorber were further added and dissolved. This was designated as Azumi Filter Paper No. Filtered using 244.

-Cellulose ester solution-
-Cellulose ester ... 73.0 parts by mass-Additive 1 represented by the following structural formula ... 25.0 parts by mass
・ Ultraviolet absorber (Tinubin 109, manufactured by Ciba Specialty Chemicals Co., Ltd.) ・ ・ ・ 1.3 mass part ・ Ultraviolet absorber (Tinbin 171; manufactured by Ciba Specialty Chemicals Co., Ltd.) ・ ・ ・ 0.6 mass part・ Methylene chloride: 300.0 parts by mass ・ Ethanol: 60.0 parts by mass

<1-2> Matting Agent Dispersion Solution The following was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.
-Fine particle dispersion-
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd., 11.0 parts by mass, ethanol, 89.0 parts by mass

<1-3> The following cellulose ester was added to a dissolution tank containing methylene chloride, heated and completely dissolved, and then dissolved in Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244. The fine particle dispersion was slowly added thereto while sufficiently stirring the filtered cellulose ester solution. Furthermore, it disperse | distributed with an attritor and this was filtered with Nippon Seisen Co., Ltd. finemet NF, and the fine particle addition liquid was prepared.
-Fine particle additive solution-
-Fine particle dispersion: 1.0 part by mass-Methylene chloride: 99.0 parts by mass-Cellulose ester: 4.0 parts by mass 100 parts by mass of the cellulose ester solution and 2 parts by mass of the fine particle addition liquid In addition, the mixture was sufficiently mixed with an in-line mixer (manufactured by Toray Industries, Inc., static type in-tube mixer Hi-Mixer, SWJ). Next, the belt was cast uniformly on a stainless steel band support having a width of 2 m using a belt casting apparatus. On the stainless steel band support, the solvent was evaporated until the residual solvent amount became 110%, and the stainless steel band support was peeled off. Tension was applied to the difference in peeling so that the longitudinal draw ratio was 1.0 times. Next, stretching was performed so that the stretching ratio in the width direction was 1.3 times at a residual solvent amount of 20% by mass at the start of tenter stretching and a temperature of 130 ° C. After stretching, the width is maintained for a few seconds, the tension in the width direction is relaxed, the width is released, and further, transported in a drying zone set at 125 ° C. for 30 minutes for drying. A phase difference film (3) was produced.

<Measurement of ΔRe and ΔRth>
With respect to the produced cellulose ester film (retardation film (3)), the Re retardation value and the Rth retardation value at 590 nm at 25 ° C. and 60% RH were Re = 50 nm and Rth = 120 nm, respectively. In the retardation film (3), Rth (λ) was calculated with an average refractive index of 1.48. Thereafter, thermostatting was performed for 120 hours under conditions of 60 ° C. and 90% RH, and Re and Rth of the film were measured again. As a result, Re = 52 nm and Rth = 128 nm (ΔRe = −3 nm, ΔRth = + 8 nm).

<Measurement of dimensional change rate>
The obtained retardation film (3) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2), leave at 25 ° C. and 60% RH for 2 hours or longer, and measure the dimension of the film in the slow axis direction of sample 2 and the dimension of the film in the fast axis direction of sample 1 It measured with the pin gauge (made by Shinto Kagaku Co., Ltd.) (L1). Thereafter, the film was heated at 60 ° C. and 90% RH for 120 hours, and the dimensions of the film were again measured with a pin gauge (L2). And the dimensional change rate was calculated | required from [(L2-L1) / L1] * 100. As a result, the dimensional change rate was 0.20% in the slow axis direction and 0.26% in the fast axis direction (the film was stretched).

<Measurement of elastic modulus>
The obtained retardation film (3) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2) and conditioned in an environment of 25 ° C. and 60% RH for 24 hours. The elastic modulus was measured according to the method described in JIS K7127 for sample 2 in the slow axis direction and for sample 1 in the fast axis direction. Tensilon manufactured by A & D Co., Ltd. was used as the tensile tester, the test piece was 50 mm × 10 mm, the distance between chucks was 30 mm, and the test speed was 30 mm / min.

<Measurement of photoelastic coefficient>
The obtained retardation film (3) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out with a size of 0.0 cm (sample 2), sample 2 is applied with tensile stress in the slow axis direction, sample 1 is applied with tensile stress in the fast axis direction, and the retardation at that time is determined by ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Production Example 4)
-Production of retardation film (4)-
A PF film (made of polycarbonate) manufactured by Kaneka Chemical Co., Ltd. was stretched uniaxially at 155 ° C. (stretching ratio: 1.5 times), and the resulting film was subjected to oven temperature (using a coaxial biaxial stretching machine). Preheating temperature, stretching temperature, heat setting temperature) 140 ° C, film feeding speed 1m / min, chuck movement accuracy within ± 1%, longitudinal stretching ratio 1.41 times, transverse stretching ratio 1.41 times, simultaneous biaxial stretching Then, a retardation film (4) was produced.

<Measurement of ΔRe and ΔRth>
With respect to the produced retardation film (4), the Re retardation value and the Rth retardation value at a wavelength of 590 nm at 25 ° C. and 60% RH were Re = 50 nm and Rth = 120 nm, respectively. In the retardation film (4), Rth (λ) was calculated with an average refractive index of 1.48. Thereafter, thermostatting was performed for 120 hours under conditions of 60 ° C. and 90% RH, and Re and Rth of the film were measured again. As a result, Re = 50 nm and Rth = 128 nm (ΔRe = 0 nm, ΔRth = + 8 nm).

<Measurement of dimensional change rate>
The obtained retardation film (4) is 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2) and leave at 25 ° C. and 60% RH for 2 hours or longer. It measured with the pin gauge (made by Shinto Kagaku Co., Ltd.) (L1). Thereafter, the film was heated at 60 ° C. and 90% RH for 120 hours, and the dimensions of the film were again measured with a pin gauge (L2). And the dimensional change rate was calculated | required from [(L2-L1) / L1] * 100. As a result, the dimensional change rate was 0.24% in the slow axis direction and 0.22% in the fast axis direction (the film was stretched).

<Measurement of elastic modulus>
The obtained retardation film (4) is 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2) and conditioned in an environment of 25 ° C. and 60% RH for 24 hours. The elastic modulus was measured according to the method described in JIS K7127 for sample 2 in the slow axis direction and for sample 1 in the fast axis direction. Tensilon manufactured by A & D Co., Ltd. was used as the tensile tester, the test piece was 50 mm × 10 mm, the distance between chucks was 30 mm, and the test speed was 30 mm / min.

<Measurement of photoelastic coefficient>
The obtained retardation film (4) is 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out with a size of 0.0 cm (sample 2), sample 2 is applied with tensile stress in the slow axis direction, sample 1 is applied with tensile stress in the fast axis direction, and the retardation at that time is determined by ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Production Example 5)
-Production of retardation film (5)-
In Production Example 4, a retardation film (5) was prepared in the same manner as in Production Example 4 except that the PF film (polycarbonate resin) manufactured by Kaneka Chemical Industry Co., Ltd. was changed to a ZEONOR film manufactured by Nippon Zeon Co., Ltd. Produced.

<Measurement of ΔRe and ΔRth>
With respect to the produced retardation film (5), the Re retardation value and the Rth retardation value at a wavelength of 590 nm at 25 ° C. and 60% RH were Re = 50 nm and Rth = 120 nm, respectively. For the retardation film (5), Rth (λ) was calculated with an average refractive index of 1.48. Thereafter, thermostatting was performed for 120 hours under conditions of 60 ° C. and 90% RH, and Re and Rth of the film were measured again. As a result, Re = 46 nm and Rth = 128 nm (ΔRe = −4 nm, ΔRth = + 8 nm).

<Measurement of dimensional change rate>
The obtained retardation film (5) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2), leave at 25 ° C. and 60% RH for 2 hours or longer, and measure the dimension of the film in the slow axis direction of sample 2 and the dimension of the film in the fast axis direction of sample 1 It measured with the pin gauge (made by Shinto Kagaku Co., Ltd.) (L1). Thereafter, the film was heated at 60 ° C. and 90% RH for 120 hours, and the dimensions of the film were again measured with a pin gauge (L2). And the dimensional change rate was calculated | required from [(L2-L1) / L1] * 100. As a result, the dimensional change rate was 0.18% in the slow axis direction and 0.25% in the fast axis direction (the film was stretched).

<Measurement of elastic modulus>
The obtained retardation film (5) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out at a size of 0.0 cm (sample 2) and conditioned in an environment of 25 ° C. and 60% RH for 24 hours. The elastic modulus was measured according to the method described in JIS K7127 for sample 2 in the slow axis direction and for sample 1 in the fast axis direction. Tensilon manufactured by A & D Co., Ltd. was used as the tensile tester, the test piece was 50 mm × 10 mm, the distance between chucks was 30 mm, and the test speed was 30 mm / min.

<Measurement of photoelastic coefficient>
The obtained retardation film (5) was 3.0 cm in the slow axis direction, 12.0 cm in the fast axis direction (sample 1), 12.0 cm in the slow axis direction, and 3 in the fast axis direction. Cut out with a size of 0.0 cm (sample 2), sample 2 is applied with tensile stress in the slow axis direction, sample 1 is applied with tensile stress in the fast axis direction, and the retardation at that time is determined by ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

(Production Example 6)
-Production of polarizing plates (1) to (5)-
A polyvinyl alcohol (PVA) film having a thickness of 80 μm was dyed by being immersed in an aqueous iodine solution having an iodine concentration of 0.05 mass% at 30 ° C. for 60 seconds. Next, the film was longitudinally stretched 5 times the original length while immersed in an aqueous boric acid solution having a boric acid concentration of 4% by mass for 60 seconds, and then dried at 50 ° C. for 4 minutes to obtain a polarized light having a thickness of 20 μm. A membrane was obtained.
Each of the prepared retardation films and a commercially available cellulose acylate film were immersed in an aqueous sodium hydroxide solution at 55 ° C. at 1.5 mol / liter, and then the sodium hydroxide was sufficiently washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at 0.005 mol / liter at 35 ° C. for 1 minute, it was immersed in water to sufficiently wash away the diluted sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
The polarizing plates (1) to (5) were bonded together using a polyvinyl alcohol-based adhesive so as to sandwich the polarizing film between each of the prepared retardation films subjected to saponification treatment as described above and a commercially available cellulose acylate film. Produced.
Here, as the commercially available cellulose acylate film, Fujitac TD80UL (manufactured by FUJIFILM Corporation) was used.

Example 1
A polarizing plate (1) on the rear side, a polarizing plate (3) on the front side, and a liquid crystal TV KDL-40J5000 manufactured by Sony, with an adhesive on the viewing side and the backlight side of the liquid crystal cell so that the absorption axis is crossed Nicol. A liquid crystal display device was manufactured by pasting through (SK2057, manufactured by Soken Chemical Co., Ltd.).
About the obtained liquid crystal display device, the viewing angle characteristic of black luminance, the viewing angle characteristic of blackness, and the corner unevenness were evaluated as follows. The results are shown in Table 1.

<Evaluation of display performance change>
Using a contrast measuring instrument (ELDIM, EZContrast) in an environment of 25 ° C. and 60% RH, the black viewing angle characteristics and the black viewing angle characteristics were measured. Thereafter, the liquid crystal display device was placed in an environment of 60 ° C. and 90% RH for 5 days, and then a black luminance field of view using a contrast measuring instrument (ELZIM, EZContrast) in an environment of 25 ° C. and 60% RH. Angular characteristics and black viewing angle characteristics were measured and evaluated according to the following criteria.
[Evaluation criteria for viewing angle characteristics of black luminance]
○: Black luminance change at 60 ° polar angle and 45 ° azimuth angle is less than 30% △: Black luminance change at 60 ° polar angle and 45 ° azimuth angle is 30% to less than 50% ×: 60 ° polar angle, azimuth angle 45 degree black luminance change is more than 50% [Evaluation criteria of black viewing angle characteristics]
○: Color change (Δu′v ′) at 60 ° polar angle and 45 ° azimuth is less than 0.03 Δ: Color change (Δu′v ′) at 60 ° polar angle and 45 ° azimuth is 0. 03 or more and less than 0.05 ×: Color change (Δu′v ′) at a polar angle of 60 degrees and an azimuth angle of 45 degrees is 0.05 or more

<Evaluation of corner unevenness>
The presence or absence of unevenness (corner unevenness) occurring on the four sides of the panel after heating was measured with a two-dimensional color luminance meter CA200 (manufactured by Konica Minolta Co., Ltd.) and evaluated according to the following criteria.
〔Evaluation criteria〕
○: Difference between the maximum light leakage luminance at the four corners and the luminance of Fresh Δ luminance is less than 0.1 cd / m ² Δ: Difference between the maximum light leakage luminance at the four corners and the luminance of Freshch Δ luminance is 0.1 cd / m ² or more and less than 0.5 cd / m ² ×: Difference Δ between the maximum light leakage luminance at the four corners and the brightness of Freshch is 0.5 cd / m ² or more

(Example 2)
The polarizing plate (3) on the rear side and the polarizing plate (1) on the front side are adhesives on the liquid crystal cell viewing side and the backlight side, respectively, so that the absorption axis is crossed Nicol in the Sony liquid crystal TV KDL-40J5000. A liquid crystal display device was manufactured by pasting via SK2057 (manufactured by Soken Chemical Co., Ltd.).
Next, the obtained liquid crystal display device was evaluated in the same manner as in Example 1 for black luminance viewing angle characteristics, black viewing angle characteristics, and corner unevenness. The results are shown in Table 1.

(Example 3)
The polarizing plate (2) on the rear side and the polarizing plate (3) on the front side are adhesives on the liquid crystal cell viewing side and the backlight side, respectively, so that the absorption axis is crossed Nicol in the Sony liquid crystal TV KDL-40J5000. A liquid crystal display device was manufactured by pasting via SK2057 (manufactured by Soken Chemical Co., Ltd.).
Next, the obtained liquid crystal display device was evaluated in the same manner as in Example 1 for black luminance viewing angle characteristics, black viewing angle characteristics, and corner unevenness. The results are shown in Table 1.

(Comparative Example 1)
The polarizing plate (1) on the rear side and the polarizing plate (1) on the front side are adhesives on the liquid crystal cell viewing side and the backlight side, respectively, so that the absorption axis is crossed Nicol in the liquid crystal TV KDL-40J5000 manufactured by Sony. A liquid crystal display device was manufactured by pasting via SK2057 (manufactured by Soken Chemical Co., Ltd.).
Next, the obtained liquid crystal display device was evaluated in the same manner as in Example 1 for black luminance viewing angle characteristics, black viewing angle characteristics, and corner unevenness. The results are shown in Table 1.

(Comparative Example 2)
The polarizing plate (3) on the rear side and the polarizing plate (3) on the front side are adhesive on the liquid crystal cell viewing side and the backlight side, respectively, so that the absorption axis is crossed Nicol in the Sony liquid crystal TV KDL-40J5000. A liquid crystal display device was manufactured by pasting via SK2057 (manufactured by Soken Chemical Co., Ltd.).
Next, the obtained liquid crystal display device was evaluated in the same manner as in Example 1 for black luminance viewing angle characteristics, black viewing angle characteristics, and corner unevenness. The results are shown in Table 1.

(Comparative Example 3)
The polarizing plate (4) on the rear side and the polarizing plate (5) on the front side are adhesive on the liquid crystal cell viewing side and the backlight side so that the absorption axis is crossed nicols on the Sony liquid crystal TV KDL-40J5000. A liquid crystal display device was manufactured by pasting via SK2057 (manufactured by Soken Chemical Co., Ltd.).
Next, the obtained liquid crystal display device was evaluated in the same manner as in Example 1 for black luminance viewing angle characteristics, black viewing angle characteristics, and corner unevenness. The results are shown in Table 1.

  The liquid crystal display device of the present invention has an Rth change by arranging retardation films (expanding retardation film and shrinking retardation film) having different dimensional change rates when the environmental temperature and humidity are changed on both sides of the liquid crystal cell. In addition, by using a retardation film that has approximately the same dimensional change rate in the slow axis direction and the fast axis direction, it is possible to suppress changes in display performance by suppressing Re changes, resulting in corner unevenness. Therefore, it is suitable for liquid crystal display devices in various display modes such as TN, IPS, FLC, AFLC, OCB, STN, VA, and HAN.

Claims (2)

A liquid crystal cell, a viewing side polarizing plate provided on the viewing side of the liquid crystal cell, and a backlight side polarizing plate provided on the backlight side of the liquid crystal cell,
Any one between the polarizer of the viewing-side polarizing plate and the liquid crystal cell and between the polarizer of the backlight-side polarizing plate and the liquid crystal cell satisfies the following formula (1). A liquid crystal display device comprising: a retardation film, and a second retardation film satisfying the following formula (2) on the other side; and the slow axes of the retardation films are orthogonal to each other.
X1> 0, X2> 0 ... Formula (1)
Y1 <0, Y2 <0 Formula (2)
However, in said Formula (1) and (2), X1 represents the dimensional change rate of the slow axis direction of a 1st phase difference film. X2 represents the dimensional change rate in the fast axis direction of the first retardation film. Y1 represents the rate of dimensional change in the slow axis direction of the second retardation film. Y2 represents the rate of dimensional change in the fast axis direction of the second retardation film. 2. The liquid crystal display device according to claim 1, wherein the first retardation film satisfies the following formula (3) and the second retardation film satisfies the following formula (4).
| X1-X2 | <0.1% Formula (3)
| Y1-Y2 | <0.1% ... Formula (4)
However, in said formula (3) and (4), X1, X2, Y1, and Y2 represent the same meaning as the above.