JP2009151048A - Liquid crystal display device and polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which does not cause the leakage of light which occurs to the peripheral part of a screen when black is displayed, because of variations in temperature and humidity and continuous lighting in the liquid crystal display device itself, prevents a polarizing plate from being exfoliated, and is excellent in durability. <P>SOLUTION: The liquid crystal display device includes a polarizing plate (PL) including at least a polarizer (20) and a phase difference film (F); and a liquid crystal cell (LC) including at least a glass substrate (12), wherein the polarizer (PL) is bonded to the surface of the glass substrate (12) with an adhesive layer (14). In this case, the phase difference film (F) is arranged between the polarizer (20) and the adhesive layer (14). Further, the product of the photoelastic coefficient and thickness of the adhesive layer (14) is -2.0×10<SP>-5</SP>to -8.5×10<SP>-5</SP>nm/Pa, the product of the photoelastic coefficient and thickness of the glass substrate (12) is 0.14×10<SP>-5</SP>to 0.28×10<SP>-5</SP>nm/Pa, and the product of the photoelastic coefficient and thickness of the phase difference film (F) is -0.05×10<SP>-5</SP>to +0.05×10<SP>-5</SP>nm/Pa. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device used for a personal computer monitor, a television, and the like, and a polarizing plate used therefor.

Liquid crystal display devices (hereinafter referred to as LCDs) are thin and lightweight, and have low power consumption, so that they are widely used in place of CRTs. The demand for polarizing plates is rapidly increasing with the spread of LCDs. The field of use is also expanding from small products such as conventional calculators and watches to large products such as automotive instruments, PC monitors, and televisions. Since the display device is often in use for a long time at all times, the polarizing plate is required to have durability so as not to deteriorate the display performance of the LCD even when used for a long time.
However, when the polarizing plate is processed under high temperature and high humidity conditions, an internal stress is generated in the polarizing plate, and the absorption axis at the peripheral edge of the polarizing plate is distorted, which causes the display performance of the LCD to deteriorate. Yes. In particular, in an LCD in which the transmission axis of a pair of polarizing plates, such as a TN (Twisted Nematic) type LCD, is arranged at 45 ° and 135 ° (crossed Nicols) when the horizontal direction of the screen is 0 °, the polarizing plate The absorption axis at the peripheral edge is likely to be distorted and the light transmittance is changed. As a result, a light leakage phenomenon is likely to occur during black display.

Regarding light leakage by the TN liquid crystal system, means for softening the pressure-sensitive adhesive and imparting stress relaxation has been proposed (see Patent Document 1).
Moreover, the technique which improves the said light leak phenomenon is disclosed by producing the polarizing plate using the acrylate-type adhesive for polarizing plates containing the component which has a positive photoelastic coefficient (refer patent document 2).
Japanese Patent Laid-Open No. 9-137143 JP-T-2004-516359

However, since the acrylate pressure-sensitive adhesive having a stress relaxation function disclosed in Patent Document 1 generally has high flexibility, bubbles are generated by stress generated when used for a long time or under high temperature and high humidity. The liquid crystal display function has a fatal problem such as peeling off. In addition, when a highly flexible adhesive layer is used, when the polarizing plate adhesive product is cut, it is difficult to cut the adhesive with high accuracy, and the product is contaminated. There is also. Moreover, according to the pressure-sensitive adhesive composition to which stress relaxation properties are imparted, light leakage during black display can be suppressed to some extent for small liquid crystal display devices, but large liquid crystal display devices such as large liquid crystal televisions However, the required performance has not been reached.
In addition, using the adhesive disclosed in Patent Document 2, a polarizing plate including a retardation film having an in-plane retardation Re has an absorption axis of 45 degrees with respect to a cell edge (display surface left-right direction). When a liquid crystal display device (for example, a TN mode liquid crystal display device) is manufactured by bonding to a liquid crystal cell, there is a problem that light leakage during black display is not reduced.

  Therefore, the present invention provides a liquid crystal display device with excellent durability that does not leak light at the periphery of the screen during black display due to temperature and humidity changes or continuous lighting of the liquid crystal display device, and there is no peeling of the polarizing plate. It is an object to provide a polarizing plate useful for that.

  As a result of intensive studies to solve the above problems, the present inventors have found that light leakage at the time of black display generated by leaving the liquid crystal display device under high temperature and high humidity and performing heat treatment is sandwiched between polarizers. It has been found that this is caused by the occurrence of uneven retardation due to internal stress in the member. In particular, for the purpose of optical compensation, when a retardation film having in-plane retardation is disposed between a glass substrate of a liquid crystal cell and a polarizer, uneven retardation generated in the retardation film can be reduced. It is difficult to cancel with a member (for example, a protective film disposed between a polarizer and a retardation layer), and as a result, even if the adhesive disclosed in Patent Document 2 is used, light leakage is improved. I found it impossible. As a result of further studies, the uneven retardation that occurs in each of the retardation films is canceled out by the members positioned closer to the liquid crystal cell than the retardation film with respect to the polarizer. The present inventors have obtained knowledge that the influence of the above can be reduced, and have further studied based on this knowledge, thereby completing the present invention.

That is, the means for solving the above problems are as follows.
[1] A liquid crystal display device comprising a polarizing plate including at least a polarizer and a retardation film, and a liquid crystal cell including at least a glass substrate, wherein the polarizing plate is bonded to the surface of the glass substrate by an adhesive layer. The retardation film is disposed between the polarizer and the pressure-sensitive adhesive layer, and the product of the photoelastic coefficient and the thickness of the pressure-sensitive adhesive layer is −2.0 × 10 ⁻⁵ to −8. 5 × 10 ⁻⁵ nm / Pa, the product of the photoelastic coefficient and the thickness of the glass substrate is 0.14 × 10 ^{−5 to} 0.28 × 10 ⁻⁵ nm / Pa, and A product of a photoelastic coefficient and a thickness of a retardation film is −0.05 × 10 ⁻⁵ to + 0.05 × 10 ⁻⁵ nm / Pa.
[2] The ratio of the absolute value of the product of the photoelastic coefficient and the thickness of each of the pressure-sensitive adhesive layer and the glass substrate (pressure-sensitive adhesive layer / glass substrate) is 9.0 to 35.0, The liquid crystal display device according to [1].
[3] The liquid crystal display device of [1] or [2], wherein the retardation film is made of a film containing an alicyclic hydrocarbon-based polymer, or has at least the film.
[4] The liquid crystal display device according to [1] or [2], wherein the retardation film is made of or contains at least a film containing a lactone ring-containing polymer.
[5] The liquid crystal display according to any one of [1] to [4], wherein the retardation film has at least a support composed of a polymer film and a retardation film formed from a curable composition. apparatus.
[6] The liquid crystal display device according to [5], wherein the retardation film contains discotic molecules fixed in an aligned state.
[7] Any one of [1] to [6], wherein the pressure-sensitive adhesive layer is a layer formed from a composition containing at least one acrylate polymer and at least one crosslinking agent. Liquid crystal display device.
[8] The liquid crystal display device according to any one of [1] to [7], wherein the polarizer is disposed with a transmission axis of 45 degrees with respect to a horizontal direction of the display surface of the liquid crystal cell. .
[9] The liquid crystal display device according to any one of [1] to [8], wherein a display mode of the liquid crystal cell is a TN mode.
[10] A polarizing plate comprising at least a polarizer, a retardation film and an adhesive layer in this order,
The product of the photoelastic coefficient and the thickness of the pressure-sensitive adhesive layer is −2.0 × 10 ⁻⁵ to −8.5 × 10 ⁻⁵ nm / Pa, and the photoelastic coefficient and the thickness of the retardation film are A polarizing plate characterized by having a product of −0.05 × 10 ⁻⁵ to + 0.05 × 10 ⁻⁵ nm / Pa.

  According to the present invention, there is no light leakage that occurs in the periphery of the screen during black display due to temperature and humidity changes or continuous lighting of the liquid crystal display device, and there is no peeling of the polarizing plate, etc., and an excellent liquid crystal display device, A polarizing plate useful for that can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the liquid crystal display device of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).

When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured 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.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Rth can also be calculated from the following formula (21) and formula (22) based on the value, the assumed value of the average refractive index, and the input film thickness value.

式中、上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。
また式中、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘ及びｎｙに直交する方向の屈折率を表し、ｄは膜厚を表す。

In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In the formula, 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, nz represents the refractive index in the direction orthogonal to nx and ny, d represents a film thickness.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) and the tilt axis (rotating axis). In each of the 10 degree steps, light of wavelength λ nm is incident from the inclined direction and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the input film thickness value, KOBRA 21ADH or WR is calculated.
In the above measurement, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and 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. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  In the present specification, the measurement wavelength is 550 nm unless otherwise specified for the measurement wavelength of retardation.

First, the operation of the present invention will be described.
A liquid crystal display device (for example, a TN mode liquid crystal display device) in which a polarizing plate is bonded to a liquid crystal cell with its absorption axis at 45 degrees with respect to the cell edge (left and right direction of the display surface) is placed under high temperature and high humidity. If left standing and wet heat treated, light leakage occurs during black display. This is because uneven retardation occurs in various members disposed between the pair of polarizers due to internal stress. For example, a viewing angle compensated TN mode LCD includes a viewing angle compensation retardation film (which may also serve as a polarizing plate protective film), an adhesive, and cell glass between a pair of polarizers. . If the original in-plane retardation of each member is so small that it can be ignored, additivity is established for the mura retardation generated in each member. For example, the adhesive described in Patent Document 2 should be used. Thus, the uneven retardation generated in each member can be canceled out. However, since the retardation film originally has in-plane retardation Re, additivity is not established between the uneven retardation generated in the retardation film and the uneven retardation generated in another member. As a result, it is difficult to cancel the mura retardation generated in the retardation film with the mura retardation generated in other members. In the present invention, the influence of the mura retardation generated in the retardation film is eliminated by canceling the mura retardation between the members positioned closer to the liquid crystal cell than the retardation film with respect to the polarizer. As a result, light leakage during black display due to uneven retardation generated in the liquid crystal display device is reduced.

FIG. 1 is a schematic sectional view of a part of an example of the liquid crystal display device of the present invention. FIG. 1 is a schematic diagram and does not accurately show the relative relationship between the thicknesses of the members of an actual liquid crystal display device.
The liquid crystal display device of FIG. 1 includes a display surface side polarizing plate PL, a backlight side polarizing plate (not shown), and a TN mode liquid crystal cell LC disposed therebetween. The liquid crystal cell LC includes a liquid crystal layer 10 and a glass substrate 12, and the polarizing plate PL is bonded to the glass substrate 12 with an adhesive layer 14. The polarizing plate PL has a protective film 22 on the display surface side surface of the polarizer 20 and a retardation film F on the liquid crystal cell side surface. The retardation film F includes a support 18 made of a polymer film, and a liquid crystal composition. And a liquid crystal cured layer 16 comprising: The transmission axis of the polarizer 20 of the polarizing plate PL is 45 ° or 135 ° when the horizontal direction of the display surface is 0 °, and is orthogonal to the transmission axis of the polarizer of the backlight side polarizing plate. It has become.

  In the liquid crystal display device in FIG. 1, the positive and negative photoelastic coefficients of the glass substrate 12 and the pressure-sensitive adhesive layer 14 are opposite to each other. Specifically, the photoelastic coefficient of the glass substrate 12 is positive, and the photoelastic coefficient of the pressure-sensitive adhesive layer 14 is negative. Here, the TN mode liquid crystal display device of FIG. 1 is kept at a high temperature and high humidity for a predetermined time (for example, 1000 hours in an environment of a temperature of 60 ° C. and 90% relative humidity or 1000 hours in an environment of 80 ° C. dry). If left untreated, uneven retardation occurs in each member due to internal stress. Its size is proportional to the product of each thickness and the photoelastic coefficient. Since the original in-plane retardation Re of the glass substrate 12 and the pressure-sensitive adhesive layer 14 is small enough to be ignored, additivity is established for the mura retardation generated in each member. Moreover, since the positive and negative signs of the photoelastic coefficients of the glass substrate 12 and the pressure-sensitive adhesive layer 14 are opposite to each other, the mura retardations generated in each of the glass substrate 12 and the pressure-sensitive adhesive layer 14 cancel each other due to their additivity. The mura retardation originally generated in the retardation film F having the in-plane retardation Re is not additive in relation to the mura retardation generated in other members, but the mura retardation of the retardation film F By canceling the uneven retardation between the glass substrate 12 and the pressure-sensitive adhesive layer 14 before being affected, the influence of the uneven retardation of the retardation film F is eliminated. In particular, when the product of the photoelastic coefficient and the thickness of the pressure-sensitive adhesive layer 14 and the glass substrate 12 is adjusted to a predetermined range, which will be described later, the generated mura retardation can be canceled almost completely. As a result, a liquid crystal display device having excellent durability in which light leakage does not occur during black display even when left at high temperature and high humidity for a long time.

The photoelastic coefficient of the glass substrate used for the liquid crystal cell is generally about 2 × 10 ⁻¹² to 4 × 10 ⁻¹² Pa ⁻¹ , and the thickness is generally 0.3 to 1. It is about 0 mm. Accordingly, the product of the photoelastic coefficient and the thickness of the glass substrate of the liquid crystal cell is generally about 0.14 × 10 ^{−5 to} 0.28 × 10 ⁻⁵ nm / Pa. In order to cancel the uneven retardation having a size proportional to the product and obtain the effect of the present invention, the product of the photoelastic coefficient and the thickness of the pressure-sensitive adhesive layer is −2.0 × 10 ^{−5 to} − It is preferably 8.5 × 10 ⁻⁵ nm / Pa, and more preferably −3.0 × 10 ⁻⁵ to −6.0 × 10 ⁻⁵ nm / Pa. In the normal pressure-sensitive adhesive layer for polarizing plate, the product of the photoelastic coefficient and the thickness is about −1.25 × 10 ⁻⁵ nm / Pa. In the present invention, the product of the photoelastic coefficient and the thickness is compared with the conventional one. And the said effect is acquired by utilizing a negatively big adhesive layer.

The photoelastic coefficient is defined by birefringence (Δn) generated when stress (σ) is applied, and is defined by the following equation.
Photoelastic coefficient (C) = Δn / σ Formula (1-1)
In the present specification, unless otherwise described, the measurement method of the photoelastic coefficient in the in-plane direction is performed as follows. Using an ellipsometer M-220 manufactured by JASCO Corporation in an environment of 25 ° C. and 60%, measurement is performed by applying a tensile force to a 2 cm square sample in the range of 0 to 10 N (measurement wavelength is 630 nm). When the load area changes due to deformation of the sample, the area is corrected and an accurate stress is calculated.
Moreover, it is preferable that the photoelastic coefficient of each member is the said range in the wavelength of 400-700 nm, Especially, the photoelastic coefficient in 630 nm can be used as a standard.

<Adhesive layer>
In the present invention, the pressure-sensitive adhesive layer is formed using a material having a negative photoelastic coefficient. Any pressure-sensitive adhesive can be used as long as the material exhibits a negative photoelastic coefficient. Moreover, even if it is an adhesive having a positive photoelastic coefficient by itself, any adhesive that exhibits a negative elastic modulus as a mixture mixed with other adhesives and additives can be used in the present invention. it can. That is, the pressure-sensitive adhesive usable in the present invention is not limited, and is a rubber-based pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, vinyl alkyl ether-based pressure-sensitive adhesive, polyvinyl alcohol-based pressure-sensitive adhesive, polyvinyl Any of pyrrolidone-based adhesive, polyacrylamide-based adhesive, cellulose-based adhesive, and the like can be used. Among them, those that are excellent in optical transparency, exhibit appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and are excellent in weather resistance, heat resistance, and the like are preferably used. Examples of the pressure-sensitive adhesive exhibiting such characteristics include acrylate-based pressure-sensitive adhesives. In this specification, the term “acrylate-based pressure-sensitive adhesive” includes any pressure-sensitive adhesive containing an acrylate-acrylate polymer (a copolymer formed from a composition containing an acrylate monomer) as an essential component. Used in. An acrylate polymer is a polymer containing units derived from monomers selected from alkyl (meth) acrylates. The “(meth) acrylic acid alkyl ester” means an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester. The ester portion of the (meth) acrylic acid ester is preferably a linear or branched alkyl group having 2 to 20 carbon atoms. Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Examples include isooctyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (meth) acrylate, and lauryl (meth) acrylate. These are generally used for acrylate-based pressure-sensitive adhesives, and these monomers usually have a negative intrinsic birefringence at 25 ° C. and 60%, and acrylate-based polymers formed from these monomers are In general, it has a negative photoelastic coefficient. For example, a pressure-sensitive adhesive made of only butyl acrylate exhibits a photoelastic coefficient of about −500 × 10 ⁻¹² Pa ⁻¹ .

  The acrylic polymer may be a homopolymer or a copolymer. Moreover, as an adhesive, only 1 type of an acrylic polymer may be used, and 2 or more types may be used. In the embodiment of the copolymer, the copolymerization monomer is selected from the viewpoint of improvement in adhesion and heat resistance. Examples of copolymerized monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, (meth ) Hydroxyl group-containing monomers such as 8-hydroxyoctyl acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate; (meth) acrylic acid , Carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and other carboxyl group-containing monomers; maleic anhydride, itaconic anhydride and other acid anhydride group-containing monomers; acrylic Acid capro Tone adducts such as styrene sulfonic acid and allyl sulfonic acid, 2- (meth) acrylamide-2methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, etc. Examples thereof include sulfonic acid group-containing monomers; phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

  In addition, (N-substituted) amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Monomer; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid t-butylaminoethyl and other (meth) acrylic acid alkylaminoalkyl monomers; (meth) acrylic (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acid and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- ( (Meta) acryloyl- - oxy octamethylene succinimide, also including succinimide-based monomers such as N- acryloyl morpholine and the like as a monomer Examples of the reforming purposes.

  Further, as modifying monomers, vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N- Vinyl monomers such as vinylcarboxylic acid amides, styrene, α-methylstyrene, N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; (Meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid meth Glycol acrylic ester monomers such as polypropylene glycol; acrylic acid ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate may also be used. it can.

  Among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used from the viewpoints of adhesion to a liquid crystal cell and durability for optical film applications. These monomers serve as reaction points with the crosslinking agent. Further, as will be described later, it is preferable to copolymerize a monomer having negative intrinsic birefringence (for example, styrene) with (meth) acrylic acid esters because the pressure-sensitive adhesive has a large negative photoelastic coefficient.

  The average molecular weight of the acrylic polymer is not particularly limited, but the weight average molecular weight is preferably about 300,000 to 2.5 million. The acrylic polymer can be produced by various known methods. For example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80 ° C., and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene and the like are generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by weight.

  Moreover, it is preferable to use a crosslinking agent together with an adhesive such as an acrylic polymer. That is, the pressure-sensitive adhesive layer is preferably formed from a pressure-sensitive adhesive composition containing at least one acrylic polymer pressure-sensitive adhesive and at least one crosslinking agent. A polyfunctional compound can be used as the crosslinking agent. Examples of the polyfunctional compound include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, and a peroxide crosslinking agent. These crosslinking agents can be used alone or in combination of two or more. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. can give. An atom in the organic compound that is covalently or coordinately bonded includes an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

  The blending ratio of the base polymer such as acrylic polymer and the crosslinking agent is not particularly limited. Usually, about 0.001-20 mass parts of crosslinking agents (solid content) are preferable with respect to 100 mass parts of base polymer (solid content).

  Furthermore, the pressure-sensitive adhesive may include a tackifier, a plasticizer, glass fiber, glass beads, metal powder, other inorganic powders, a pigment, a colorant, a filler, an antioxidant, if necessary. UV absorbers, silane coupling agents, and the like, and various additives can be appropriately used without departing from the scope of the present invention. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  As the additive, a silane coupling agent is preferable, and about 0.001 to 10 parts by mass of the silane coupling agent (solid content) is preferable with respect to 100 parts by mass of the base polymer (solid content). It is preferable to mix about 005-5 mass parts. As the silane coupling agent, those conventionally known can be used without particular limitation. For example, epoxy groups such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane -Containing silane coupling agent, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine Amino group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, (meth) acrylic group-containing silane coupling agents such as 3-methacryloxypropyltriethoxysilane, and isocyanates such as 3-isocyanatopropyltriethoxysilane It can be exemplified containing silane coupling agent.

  In order to increase the photoelastic coefficient of the pressure-sensitive adhesive layer to be negative and to be within the above range, a material having a negative photoelastic coefficient is used, the pressure-sensitive adhesive layer is thickened, and a material having a large negative photoelastic coefficient. There is a method of using. In order not to excessively increase the thickness of the pressure-sensitive adhesive layer, it is preferable to use a material having a negative photoelastic coefficient. In general, a copolymer of a monomer having negative intrinsic birefringence (for example, styrene) and (meth) acrylic acid esters is preferable because it is a pressure-sensitive adhesive having a negative photoelastic coefficient. However, since the pressure-sensitive adhesive is usually used at room temperature, it is preferable to appropriately adjust the type and amount of the compound used so that Tg does not exceed room temperature.

The pressure-sensitive adhesive layer can be prepared by preparing the pressure-sensitive adhesive composition as a coating solution, applying the coating solution to a surface using a bar coater or the like, and drying the coating solution. When drying, it may be heated as desired, or may be left at a predetermined temperature for a predetermined time for aging after drying. The pressure-sensitive adhesive layer may be directly formed on the surface of the polarizing plate or the glass substrate by coating, or may be once formed on the surface of the peelable substrate and then transferred to the surface of the polarizing plate or the glass substrate.
In addition, when apply | coating an adhesive composition to a polarizing plate or the glass surface, it is important that a component does not remain on a glass surface at the time of rework, and that each component does not phase-separate. The phase separation is caused by the compatibility of each component, and the better the compatibility of each component, the more difficult it is to cause phase separation. In addition, when judging the presence or absence of a phase separation, it can confirm by observing a pressure sensitive adhesive by microscope after 80 degreeCdry1000h or 60 degreeC90% 1000h processing.

<Glass substrate>
In the present invention, as a glass substrate of the liquid crystal cell, a glass substrate used in various ordinary displays can be used. As described above, these glass substrates usually have a photoelastic coefficient of 2 × 10 ⁻¹² to 4 × 10 ⁻¹² Pa ⁻¹ and a thickness of about 0.3 to 1.0 mm. That is, the product of the photoelastic coefficient and the thickness of the glass substrate of the liquid crystal cell is about 0.14 × 10 ^{−5 to} 0.28 × 10 ⁻⁵ nm / Pa.
Since it is necessary to form a metal or oxide thin film on the surface of a glass substrate, the following characteristics are required.
(1) When an alkali metal oxide is contained, the alkali metal ions diffuse into the thin film and deteriorate the film characteristics, so that the alkali metal ions are not substantially contained.
(2) Since it is exposed to a high temperature in the thin film formation process, it has a high strain point in order to minimize the deformation caused by glass deformation and glass structural stabilization.
(3) Sufficient chemical durability against various chemicals used for semiconductor formation. In particular, it has durability against buffered hydrofluoric acid (BHF) mainly composed of hydrofluoric acid, ammonium fluoride, etc. for etching SiO _x and SiN _x .
(4) There shall be no defects (bubbles, striae, inclusions, pits, scratches, etc.) inside and on the surface.

Corning # 1737, Asahi Glass AN635, and AN100 glass are widely used as materials satisfying the above required characteristics. These photoelastic coefficients are 3 × 10 ⁻¹² Pa ⁻¹ . The lower the photoelastic coefficient of the glass, the smaller the occurrence of uneven retardation. The photoelastic coefficient of the glass substrate can be adjusted to a desired range by adding an additive. For example, BaO is an additive that increases the photoelastic coefficient. The amount of these additives added will be determined so that the specific gravity and expansion coefficient of the glass substrate together with the desired photoelastic coefficient do not become excessively high.

<Phase difference film>
The retardation film of the liquid crystal display device of the present invention may be a single layer structure film or a laminated structure film. Various retardation films used for optical compensation of a TN mode liquid crystal display device or the like can be used. As an example, a retardation film having a support composed of a polymer film and a retardation film formed from a curable composition (for example, a curable liquid crystal composition) can be mentioned. The retardation film having this configuration uses a birefringent polymer film having in-plane retardation Re as a support, and there is a form in which Re of the support is also used for optical compensation together with Re of the retardation film. However, any aspect may be sufficient. In addition, in order to prevent the light leakage from worsening due to the uneven retardation that occurs in the polymer film as the support, even though the uneven retardation has been canceled in the glass substrate and the pressure-sensitive adhesive layer, The absolute value of the elastic modulus is preferably as small as possible. Specifically, it is preferably about −5 × 10 ⁻¹² to + 5 × 10 ⁻¹² Pa ⁻¹ , and −3 × 10 ⁻¹² to + 3 × 10 ⁻¹² Pa. More preferably, it is about ^-1 . When the photoelastic coefficient is within this range, the effect of the mura retardation generated on the support on the image is not a practical problem. Considering that the thickness of the retardation film is usually about 30 to 100 μm, in the present invention, the product of the photoelastic coefficient and the thickness of the retardation film is −0.05 × 10 ⁻⁵ to + 0.05 × 10. ⁻⁵ nm / Pa, preferably about −0.03 × 10 ⁻⁵ to + 0.03 × 10 ⁻⁵ nm / Pa.
In the embodiment where the retardation film is a laminate of two or more layers, the product of the photoelastic coefficient and the thickness of the entire laminate is adjusted within the above range. However, many retardation films formed by curing a curable composition such as a liquid crystal composition have little contribution to the photoelastic coefficient, and if the polymer film exhibits a photoelastic coefficient in the above range, its surface Even if the retardation film is formed, it has been confirmed that the photoelastic coefficient of the retardation film as a whole is equal to the photoelastic coefficient of the polymer film as the support.

  The retardation film (particularly in the example of the retardation film described above) may be a protective film for a polarizer. Of course, a protective film for the polarizer may be separately disposed between the polarizer and the retardation film. However, when a protective film is separately arranged, it is preferable to consider the retardation film including the protective film and adjust the product of the photoelastic coefficient and thickness of the entire laminate to the above range.

Examples of the polymer film having a photoelastic coefficient in the above range include films containing the following polymers as main components.
(Alicyclic hydrocarbon polymer)
As the norbornene-based addition (co) polymer, those disclosed in JP-A No. 10-7732, JP-A No. 2002-504184, US2004229157A1 or International Publication No. 2004 / 070463A1 may be used. it can. It is obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and conjugated dienes such as ethylene, propylene, butene, butadiene and isoprene; non-conjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. As this norbornene type addition (co) polymer, a commercial item can also be used. Specifically, grades such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C), or APL6015T (Tg145 ° C), which are sold under the trade name of Apel from Mitsui Chemicals, Inc. and have different glass transition temperatures (Tg), are used. There is. Pellets such as TOPAS 8007, 6013, and 6015 are sold by Polyplastics Co., Ltd. Furthermore, Appear 3000 is marketed by Promerus.

  Norbornene-based polymer hydrides are disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-1159767, or As disclosed in Japanese Patent Application Laid-Open No. 2004-309979 and the like, it is possible to use those produced by hydrogenation after addition polymerization or metathesis ring-opening polymerization of a polycyclic unsaturated compound. Specifically, JSR Co., Ltd. is sold under the trade name Arton G or Arton F, and from Zeon Japan, Zeonor ZF14, ZF16, Zeonex 250 or Zeonex 280. These are commercially available under the trade name and can be used.

(Lactone ring-containing polymer)
The lactone ring-containing polymer has a lactone ring structure in the polymer, and preferably has a lactone ring structure represented by the following general formula (1).

^{Wherein, R 1, R 2, R} 3 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue referred to here may contain an oxygen atom. 1-15 are preferable, as for carbon number of an organic residue, 1-12 are more preferable, 1-8 are more preferable, and 1-5 are still more preferable. Examples of the organic residue include a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, and the like, and an alkyl group is preferable. Examples of the substituent include an alkyl group, an aryl group, and an alkoxy group. R ¹ , R ² and R ³ are more preferably a hydrogen atom, a methyl group, an ethyl group or a propyl group, still more preferably a hydrogen atom, a methyl group or an ethyl group, still more preferably a hydrogen atom or a methyl group. It is.

  The content ratio of the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. Especially preferably, it is 10-50 mass%. If the content of the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is 5% by mass or more, sufficient heat resistance, solvent resistance, and surface hardness tend to be obtained. . Further, when the content ratio of the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is 90% by mass or less, higher moldability tends to be easily obtained.

  The lactone ring-containing polymer may have a structure other than the lactone ring structure represented by the general formula (1). The structure other than the lactone ring structure represented by the general formula (1) is not particularly limited, but a (meth) acrylic acid ester and a hydroxyl group-containing monomer as will be described later as a method for producing a lactone ring-containing polymer. A polymer structural unit (repeating structural unit) constructed by polymerizing at least one selected from unsaturated carboxylic acids and monomers represented by the following general formula (2a) is preferable.

(Wherein R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an acetate group, a cyano group, a —CO—R ⁵ group, or —CO—O. represents -R ⁶ group, the organic residue R ⁵ and R ⁶ represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. having 1 to 20 carbon atoms, the organic residue in the formula (1) Reference can be made to the description.
The content ratio of the structure other than the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is a polymer structural unit (repeated structural unit) constructed by polymerizing (meth) acrylic acid ester. In this case, it is preferably 10 to 95% by mass, more preferably 10 to 90% by mass, further preferably 40 to 90% by mass, and particularly preferably 50 to 90% by mass, and is constructed by polymerizing a hydroxyl group-containing monomer. In the case of a polymer structural unit (repeating structural unit), preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, particularly preferably 0 to 10% by mass. . In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing an unsaturated carboxylic acid, it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, particularly Preferably it is 0-10 mass%. In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing the monomer represented by the general formula (2a), it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and still more preferably. Is 0 to 15% by mass, particularly preferably 0 to 10% by mass.

  The method for producing the lactone ring-containing polymer is not particularly limited, but preferably, after the polymer (a) having a hydroxyl group and an ester group in the molecular chain is obtained by the polymerization step, the obtained polymer ( This is a method of performing a lactone cyclization condensation step in which a lactone ring structure is introduced into a polymer by heat-treating a).

  In the polymerization step, for example, a polymer having a hydroxyl group and an ester group in a molecular chain is obtained by performing a polymerization reaction using a monomer composition containing a monomer represented by the following general formula (1a). Obtainable.

(In the formula, R ⁷ and R ⁸ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. For the organic residue having 1 to 20 carbon atoms, the organic group in the above general formula (1)). (See description of residues.)
Examples of the monomer represented by the general formula (1a) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- ( Hydroxymethyl) n-butyl acrylate, tert-butyl 2- (hydroxymethyl) acrylate, and the like. Among these, methyl 2- (hydroxymethyl) acrylate and 2- (hydroxymethyl) ethyl acrylate are preferable, and methyl 2- (hydroxymethyl) acrylate is particularly preferable in that the effect of improving heat resistance is high. As for the monomer represented by the general formula (1a), only one type may be used, or two or more types may be used in combination.

  The content ratio of the monomer represented by the general formula (1a) in the monomer composition to be subjected to the polymerization step is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and even more preferably 10 to 10% by mass. 60% by mass, particularly preferably 10 to 50% by mass. If the content ratio of the monomer represented by the general formula (1a) in the monomer composition to be subjected to the polymerization step is 5% by mass or more, sufficient heat resistance, solvent resistance, and surface hardness are easily obtained. Tend. If the content of the monomer represented by the general formula (1a) in the monomer composition to be subjected to the polymerization step is 90% by mass or less, it is possible to sufficiently prevent gelation during lactone cyclization. And a polymer having higher moldability tends to be obtained.

  The monomer composition used for the polymerization step may contain a monomer other than the monomer represented by the general formula (1a). Such a monomer is not particularly limited, and for example, (meth) acrylic acid ester, a hydroxyl group-containing monomer, an unsaturated carboxylic acid, and a monomer represented by the general formula (2a) are preferable. It is done. Only one type of monomer other than the monomer represented by the general formula (1a) may be used, or two or more types may be used in combination.

  The (meth) acrylic acid ester is not particularly limited as long as it is a (meth) acrylic acid ester other than the monomer represented by the general formula (1a). For example, methyl acrylate, ethyl acrylate, and acrylic acid n -Acrylic acid esters such as butyl, isobutyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid methacrylic acid esters such as tert-butyl, cyclohexyl methacrylate, benzyl methacrylate; and the like. These may be used alone or in combination of two or more. Among these, methyl methacrylate is particularly preferable from the viewpoint of excellent heat resistance and transparency.

  When a (meth) acrylic acid ester other than the monomer represented by the general formula (1a) is used, the content ratio in the monomer composition to be subjected to the polymerization step is sufficient to exert the effect of the present invention. And preferably 10 to 95% by mass, more preferably 10 to 90% by mass, still more preferably 40 to 90% by mass, and particularly preferably 50 to 90% by mass.

  The hydroxyl group-containing monomer is not particularly limited as long as it is a hydroxyl group-containing monomer other than the monomer represented by the general formula (1a). For example, α-hydroxymethyl styrene, α-hydroxyethyl styrene, 2 -2- (hydroxyalkyl) acrylic acid ester such as methyl (hydroxyethyl) acrylate; 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxyethyl) acrylic acid; and the like. Or two or more of them may be used in combination.

  In the case of using a hydroxyl group-containing monomer other than the monomer represented by the general formula (1a), the content ratio in the monomer composition to be subjected to the polymerization step is sufficient to exert the effect of the present invention. The content is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, further preferably 0 to 15% by mass, and particularly preferably 0 to 10% by mass.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid and the like. These may be used alone or in combination of two or more. May be. Among these, acrylic acid and methacrylic acid are preferable in that the effects of the present invention are sufficiently exhibited.

  In the case of using an unsaturated carboxylic acid, the content ratio in the monomer composition to be subjected to the polymerization step is preferably 0 to 30% by mass, more preferably 0 to 20%, in order to sufficiently exhibit the effects of the present invention. It is 0 mass%, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 mass%.

  Examples of the monomer represented by the general formula (2a) include styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, and vinyl acetate. These are used alone. Or two or more of them may be used in combination. Among these, styrene and α-methylstyrene are particularly preferable in that the effects of the present invention are sufficiently exhibited.

  When using the monomer represented by the general formula (2a), the content ratio in the monomer composition to be subjected to the polymerization step is preferably 0 to 30 mass in order to sufficiently exhibit the effects of the present invention. %, More preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, particularly preferably 0 to 10% by mass.

  The form of the polymerization reaction for polymerizing the monomer composition to obtain a polymer having a hydroxyl group and an ester group in the molecular chain is preferably a polymerization form using a solvent, and solution polymerization is particularly preferred. .

  The polymerization temperature and polymerization time vary depending on the type of monomer used, the ratio of use, etc., but preferably the polymerization temperature is 0 to 150 ° C. and the polymerization time is 0.5 to 20 hours, more preferably polymerization. The temperature is 80 to 140 ° C. and the polymerization time is 1 to 10 hours.

  In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, an aromatic hydrocarbon solvent such as toluene, xylene, or ethylbenzene; a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone ketone; an ether system such as tetrahydrofuran. A solvent; etc. are mentioned, Only 1 type of these may be used and 2 or more types may be used together. Moreover, since the residual volatile matter of the lactone ring containing polymer finally obtained will increase when the boiling point of the solvent to be used is too high, a thing with a boiling point of 50-200 degreeC is preferable.

  During the polymerization reaction, a polymerization initiator may be added as necessary. Although it does not specifically limit as a polymerization initiator, For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-tert-butyl peroxide, lauroyl peroxide, benzoyl peroxide, tert-butylperoxyisopropyl carbonate, tert-amyl Organic peroxides such as peroxy-2-ethylhexanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2, Azo compounds such as 4-dimethylvaleronitrile), and the like. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited as long as it is appropriately set according to the combination of the monomers used and the reaction conditions.

  When performing the polymerization, it is preferable to control the concentration of the produced polymer in the polymerization reaction mixture to be 50% by mass or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the produced polymer in the polymerization reaction mixture exceeds 50% by mass, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by mass or less. . The concentration of the produced polymer in the polymerization reaction mixture is more preferably 45% by mass or less, and further preferably 40% by mass or less. In addition, since productivity will fall when the density | concentration of the polymer in a polymerization reaction mixture is too low, it is preferable that the density | concentration of the polymer in a polymerization reaction mixture is 10 mass% or more, and is 20 mass% or more. It is more preferable.

  The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and the polymerization solvent may be added continuously or intermittently. By controlling the concentration of the produced polymer in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed, and in particular, to increase the lactone ring content and improve the heat resistance. Even when the ratio of the hydroxyl group to the ester group in the molecular chain is increased, gelation can be sufficiently suppressed. The polymerization solvent to be added may be the same type of solvent used during the initial charging of the polymerization reaction or may be a different type of solvent, but is the same as the solvent used during the initial charging of the polymerization reaction. It is preferable to use different types of solvents. Further, the polymerization solvent to be added may be only one type of solvent or a mixed solvent of two or more types.

  The polymerization reaction mixture obtained when the above polymerization step is completed usually contains a solvent in addition to the obtained polymer, but it is necessary to completely remove the solvent and take out the polymer in a solid state. Rather, it is preferably introduced into the subsequent lactone cyclization condensation step in a state containing a solvent. If necessary, after taking out in a solid state, a solvent suitable for the subsequent lactone cyclization condensation step may be added again.

  The polymer obtained in the polymerization step is a polymer (a) having a hydroxyl group and an ester group in the molecular chain, and the weight average molecular weight of the polymer (a) is preferably 1,000 to 2,000,000. 000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, particularly preferably 50,000 to 500,000. The polymer (a) obtained in the polymerization step is subjected to heat treatment in the subsequent lactone cyclization condensation step, whereby a lactone ring structure is introduced into the polymer to become a lactone ring-containing polymer.

  The reaction for introducing the lactone ring structure into the polymer (a) is a reaction in which a hydroxyl group and an ester group present in the molecular chain of the polymer (a) are cyclized and condensed to form a lactone ring structure by heating. The cyclized condensation produces alcohol as a by-product. By forming the lactone ring structure in the molecular chain of the polymer (in the main skeleton of the polymer), high heat resistance is imparted. If the reaction rate of the cyclization condensation reaction leading to the lactone ring structure is insufficient, the heat resistance will not be improved sufficiently, or the condensation reaction will occur during the molding process due to the heat treatment during molding, and the resulting alcohol will be contained in the molded product. It is not preferable because it is present as bubbles or silver streaks.

  The lactone ring-containing polymer obtained in the lactone cyclization condensation step preferably has a lactone ring structure represented by the general formula (1).

  The method for heat-treating the polymer (a) is not particularly limited, and a known method can be used. For example, you may heat-process the polymerization reaction mixture containing the solvent obtained by the superposition | polymerization process as it is. Moreover, you may heat-process using a ring-closing catalyst as needed in presence of a solvent. Further, the heat treatment can be performed using a heating furnace or reaction apparatus having a vacuum apparatus or a devolatilizing apparatus for removing volatile components, an extruder having a devolatilizing apparatus, or the like.

  In carrying out the cyclization condensation reaction, in addition to the polymer (a), another thermoplastic resin may coexist. Further, when performing the cyclization condensation reaction, if necessary, an esterification catalyst or a transesterification catalyst such as p-toluenesulfonic acid generally used as a catalyst for the cyclization condensation reaction may be used. Organic carboxylic acids such as propionic acid, benzoic acid, acrylic acid, and methacrylic acid may be used as a catalyst. As disclosed in JP-A-61-254608 and JP-A-61-261303, basic compounds, organic carboxylates, carbonates and the like may be used.

  In carrying out the cyclization condensation reaction, it is preferable to use an organic phosphorus compound as a catalyst as disclosed in JP-A No. 2001-151814. By using an organophosphorus compound as a catalyst, the cyclization condensation reaction rate can be improved, and coloring of the resulting lactone ring-containing polymer can be greatly reduced. Furthermore, by using an organophosphorus compound as a catalyst, it is possible to suppress a decrease in molecular weight that can occur when a devolatilization step described later is used in combination, and to impart excellent mechanical strength.

  Although the usage-amount of the catalyst used in the case of a cyclization condensation reaction is not specifically limited, Preferably it is 0.001-5 mass% with respect to a polymer (a), More preferably, it is 0.01-2.5 mass%. More preferably, it is 0.01-1 mass%, Most preferably, it is 0.05-0.5 mass%. If the amount of the catalyst used is 0.001% by mass or more, the reaction rate of the cyclization condensation reaction tends to be sufficiently improved, whereas if it is 5% by mass or less, coloring and crosslinking are prevented. There is a tendency that good melt formability is easily obtained.

  The addition timing of the catalyst is not particularly limited, and it may be added at the beginning of the reaction, during the reaction, or both.

  The cyclization condensation reaction is preferably performed in the presence of a solvent, and a devolatilization step is preferably used in combination with the cyclization condensation reaction. In this case, a mode in which the devolatilization step is used throughout the cyclization condensation reaction and a mode in which the devolatilization step is not used throughout the entire cyclization condensation reaction and are used only in a part of the process. In the method using the devolatilization step in combination, the alcohol produced as a by-product in the condensation cyclization reaction is forcibly devolatilized and removed, so that the equilibrium of the reaction is advantageous for the production side.

  The devolatilization step refers to a step of removing volatile components such as a solvent and residual monomers and alcohol produced as a by-product by a cyclocondensation reaction leading to a lactone ring structure, if necessary under reduced pressure heating conditions. If this removal treatment is insufficient, the residual volatile components in the produced resin increase, resulting in problems such as coloration due to alteration during molding, or molding defects such as bubbles or silver streaks.

  In the case of a form in which a devolatilization step is used throughout the cyclization condensation reaction, the apparatus to be used is not particularly limited, but a devolatilization apparatus comprising a heat exchanger and a devolatilization tank in order to perform the present invention more effectively. It is preferable to use an extruder with a vent or an extruder with the devolatilizer and the extruder arranged in series, more preferably using a devolatilizer comprising a heat exchanger and a devolatilizer tank or an extruder with a vent. preferable.

  In the case of using a devolatilizer comprising the heat exchanger and a devolatilizer, the reaction treatment temperature is preferably in the range of 150 to 350 ° C, more preferably in the range of 200 to 300 ° C. If the reaction treatment temperature is 150 ° C. or higher, the cyclization condensation reaction tends to proceed sufficiently and the residual volatile content tends to be suppressed, and if it is 350 ° C. or lower, coloring and decomposition tend to be prevented.

  When using a devolatilizer comprising the heat exchanger and the devolatilization tank, the pressure during the reaction treatment is preferably in the range of 931 to 1.33 hPa (700 to 1 mmHg), and 798 to 66.5 hPa (600 to 50 mmHg). The range of is more preferable. If the pressure is 931 hPa or more, there is a tendency to sufficiently prevent the remaining volatile components including alcohol, and if it is 1.33 hPa or less, industrial implementation tends to be easier.

  When using the extruder with a vent, one or a plurality of vents may be used, but it is preferable to have a plurality of vents.

  The reaction processing temperature in the case of using the vented extruder is preferably in the range of 150 to 350 ° C, more preferably in the range of 200 to 300 ° C. If the said temperature is 150 degreeC or more, there exists a tendency for a cyclization condensation reaction to fully advance and it becomes easy to suppress a residual volatile matter amount, and if it is 350 degrees C or less, it exists in the tendency which is easy to prevent coloring and decomposition | disassembly.

  When using the extruder with a vent, the pressure during the reaction treatment is preferably in the range of 931 to 1.33 hPa (700 to 1 mmHg), and more preferably in the range of 798 to 13.3 hPa (600 to 10 mmHg). If the pressure is 931 hPa or more, there is a tendency to sufficiently prevent the remaining volatile components including alcohol, and if it is 1.33 hPa or less, industrial implementation tends to be easier.

  In the case of using the devolatilization step throughout the cyclization condensation reaction, as described later, the physical properties of the lactone ring-containing polymer obtained may be deteriorated under severe heat treatment conditions. It is preferable to use a catalyst for a dealcoholization reaction and under a mild condition as much as possible using an extruder with a vent.

  In the case of using the devolatilization step throughout the entire cyclization condensation reaction, preferably, the polymer (a) obtained in the polymerization step is introduced into the cyclization condensation reactor system together with the solvent. If necessary, it may be passed through the reactor system such as a vented extruder once again.

  You may perform the form used together only in a part of process, without using a devolatilization process over the whole process of cyclization condensation reaction. For example, the apparatus for producing the polymer (a) is further heated, and if necessary, a part of the devolatilization step is used together to advance the cyclization condensation reaction to some extent in advance, followed by the devolatilization step. Is a form in which a cyclization condensation reaction is simultaneously used to complete the reaction.

  In the form in which the devolatilization step is used throughout the cyclization condensation reaction described above, for example, when the polymer (a) is heat-treated at a high temperature close to 250 ° C. or higher using a twin-screw extruder. Depending on the difference in thermal history, partial decomposition or the like may occur before the cyclization condensation reaction occurs, and the physical properties of the resulting lactone ring-containing polymer may be deteriorated. Therefore, if the cyclization condensation reaction is allowed to proceed to some extent before the cyclization condensation reaction using the devolatilization step at the same time, the latter reaction conditions can be relaxed and the physical properties of the resulting lactone ring-containing polymer deteriorated. Is preferable. As a particularly preferred embodiment, the devolatilization step is started after a lapse of time from the start of the cyclization condensation reaction, that is, the hydroxyl group and the ester group present in the molecular chain of the polymer (a) obtained in the polymerization step. A form in which a cyclization condensation reaction is performed in advance to increase the cyclization condensation reaction rate to some extent and then a cyclization condensation reaction using a devolatilization step in combination is performed. Specifically, for example, a cyclization condensation reaction is allowed to proceed to a certain reaction rate in the presence of a solvent in advance using a kettle-type reactor, and then a reactor equipped with a devolatilizer, for example, a heat Preferred is a mode in which the cyclization condensation reaction is completed with a devolatilizer comprising an exchanger and a devolatilization tank, an extruder with a vent, or the like. Particularly in this form, it is more preferable that a catalyst for the cyclization condensation reaction is present.

  As described above, the hydroxyl group and ester group present in the molecular chain of the polymer (a) obtained in the polymerization step are preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent. The method of carrying out the cyclization condensation reaction using the steps at the same time is a preferred form in obtaining a lactone ring-containing polymer in the present invention. With this form, a lactone ring-containing polymer having a higher glass transition temperature, a higher cyclization condensation reaction rate, and excellent heat resistance can be obtained. In this case, as a measure of the cyclization condensation reaction rate, the mass reduction rate between 150 and 300 ° C. in the dynamic TG measurement is preferably 2% or less, more preferably 1.5% or less. Preferably it is 1% or less.

  The reactor that can be employed in the cyclization condensation reaction that is performed in advance before the cyclization condensation reaction using the devolatilization process at the same time is not particularly limited, but preferably an autoclave, a kettle reactor, a heat exchanger, and a devolatilization tank A vented extruder suitable for a cyclocondensation reaction in which a devolatilization step is simultaneously used can also be used. More preferred are autoclaves and kettle reactors. However, even when using a reactor such as an extruder with a vent, by adjusting the temperature condition, barrel condition, screw shape, screw operating condition, etc. It is possible to carry out the cyclization condensation reaction in the same state as the reaction state in the kettle reactor.

  In the case of the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization step at the same time, preferably, a mixture containing the polymer (a) obtained in the polymerization step and the solvent is used as (i). Examples thereof include a method in which a catalyst is added and subjected to a heat reaction, (ii) a method in which the reaction is performed without a catalyst, and a method in which the above (i) or (ii) is performed under pressure.

  The “mixture containing the polymer (a) and the solvent” introduced into the cyclization condensation reaction in the lactone cyclization condensation step may be the polymerization reaction mixture obtained in the polymerization step as it is, or once It means that a solvent suitable for the cyclocondensation reaction may be added again after removing the solvent.

  The solvent that can be re-added in the cyclization condensation reaction that is carried out in advance before the cyclization condensation reaction simultaneously used in the devolatilization step is not particularly limited, and examples thereof include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; Ketones such as methyl ethyl ketone and methyl isobutyl ketone; chloroform, DMSO, tetrahydrofuran and the like may be used, but the same type of solvent that can be used in the polymerization step is preferable.

  Examples of the catalyst to be added in the method (i) include esterification catalysts or transesterification catalysts such as p-toluenesulfonic acid, basic compounds, organic carboxylates, and carbonates that are generally used. Is preferably the above-described organophosphorus compound. The addition timing of the catalyst is not particularly limited, and it may be added at the beginning of the reaction, during the reaction, or both. The amount of the catalyst to be added is not particularly limited, but is preferably 0.001 to 5% by mass, more preferably 0.01 to 2.5% by mass, and still more preferably 0.01% with respect to the mass of the polymer (a). -1% by mass, particularly preferably 0.05-0.5% by mass. The heating temperature and heating time of method (i) are not particularly limited, but the heating temperature is preferably room temperature or higher, more preferably 50 ° C. or higher, and the heating time is preferably 1 to 20 hours, more preferably 2 to 10 hours. If the heating temperature is low or the heating time is short, the cyclization condensation reaction rate is lowered, which is not preferable. Further, if the heating time is too long, the resin may be colored or decomposed, which is not preferable.

  Examples of the method (ii) include a method of heating the polymerization reaction mixture obtained in the polymerization step as it is using a pressure-resistant kettle or the like. The heating temperature is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. The heating time is preferably 1 to 20 hours, more preferably 2 to 10 hours. If the heating temperature is low or the heating time is short, the cyclization condensation reaction rate is lowered, which is not preferable. Further, if the heating time is too long, the resin may be colored or decomposed, which is not preferable.

  Both the above methods (i) and (ii) have no problem even under pressure depending on conditions.

  In the case of the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization step at the same time, there is no problem even if part of the solvent volatilizes spontaneously during the reaction.

  The mass reduction rate between 150 and 300 ° C. in the dynamic TG measurement at the end of the cyclization condensation reaction performed in advance before the cyclization condensation reaction simultaneously using the devolatilization step, that is, immediately before the start of the devolatilization step is 2% or less is preferable, More preferably, it is 1.5% or less, More preferably, it is 1% or less. If the mass reduction rate is 2% or less, when the cyclization condensation reaction is performed simultaneously with the devolatilization step, the cyclization condensation reaction rate increases to a sufficiently high level, and the resulting lactone ring-containing polymer There is a tendency to improve the physical properties. In addition, when performing said cyclization condensation reaction, in addition to a polymer (a), you may coexist other thermoplastic resins.

  The hydroxyl group and ester group present in the molecular chain of the polymer (a) obtained in the polymerization step were subjected to a cyclization condensation reaction in advance to increase the cyclization condensation reaction rate to some extent, and then the devolatilization step was simultaneously used in combination. In the case of a form in which a cyclization condensation reaction is performed, a polymer obtained by a cyclization condensation reaction performed in advance (a polymer in which at least a part of a hydroxyl group and an ester group present in a molecular chain are subjected to a cyclization condensation reaction) and a solvent, The devolatilization step may be used as it is, and may be introduced into the cyclization condensation reaction. If necessary, the polymer (a polymer obtained by cyclization condensation reaction of at least a part of hydroxyl groups and ester groups present in the molecular chain) may be used. You may introduce | transduce into the cyclocondensation reaction which used the devolatilization process together after passing through other processes, such as adding a solvent again after isolating a compound.

  The devolatilization step is not limited to being completed at the same time as the cyclization condensation reaction, and may be completed after a lapse of time from the completion of the cyclization condensation reaction.

  The lactone ring-containing polymer has a weight average molecular weight of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000.

  The lactone ring-containing polymer preferably has a mass reduction rate of 150% to 300 ° C in dynamic TG measurement of 1% or less, more preferably 0.5% or less, and even more preferably 0.3% or less. is there.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, it is possible to avoid the disadvantage that bubbles and silver streaks enter the molded product after molding. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has sufficiently high heat resistance.

The lactone ring-containing polymer preferably has a coloring degree (YI) in a 15% by mass chloroform solution of 6 or less, more preferably 3 or less, still more preferably 2 or less, and most preferably 1 or less. If the degree of coloring (YI) is 6 or less, coloring tends to be prevented and higher transparency tends to be obtained.

  The lactone ring-containing polymer preferably has a 5% mass reduction temperature in thermal mass spectrometry (TG) of 280 ° C. or higher, more preferably 290 ° C. or higher, and still more preferably 300 ° C. or higher. The 5% mass loss temperature in thermal mass spectrometry (TG) is an indicator of thermal stability. If this is 280 ° C. or higher, sufficient thermal stability is likely to be exhibited.

  The lactone ring-containing polymer has a glass transition temperature (Tg) of preferably 115 ° C. or higher, more preferably 125 ° C. or higher, further preferably 130 ° C. or higher, more preferably 135 ° C. or higher, and most preferably 140 ° C. or higher. .

  The total amount of residual volatile components contained in the lactone ring-containing polymer is preferably 5000 ppm or less, more preferably 2000 ppm or less. If the total amount of residual volatile components is 5000 ppm or less, molding defects such as coloring, foaming, and silver streaking due to deterioration during molding tend to be more effectively prevented.

  The lactone ring-containing polymer preferably has a total light transmittance of 85% or more, more preferably 88% or more, and still more preferably a molded product obtained by injection molding, as measured by a method according to ASTM-D-1003. Is 90% or more. Total light transmittance is a measure of transparency.

<Polymer film production method>
In the present invention, a polymer film used as a support for a retardation film or a protective film for a polarizer can be produced by various methods.
For example, the above polymer and, if desired, other polymers and additives may be mixed by a conventionally known mixing method, a polymer composition is prepared in advance, and manufactured using various film forming methods. it can. The polymer composition can be prepared by, for example, pre-blending with a mixer such as an omni mixer and then extruding and kneading the resulting mixture. In this case, the kneader used for extrusion kneading is not particularly limited. For example, a conventionally known kneader such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used. .

  Examples of the film forming method include known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these, the solution casting method (solution casting method) and the melt extrusion method are preferable. At this time, the thermoplastic resin composition extruded and kneaded in advance as described above may be used, or after other thermoplastic resins and other additives are separately dissolved in the solution to obtain a uniform mixed solution. The film may be subjected to a film forming process such as a solution casting method (solution casting method) or a melt extrusion method.

  Solvents used in the solution casting method (solution casting method) include, for example, chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, and isopropanol , N-butanol, 2-butanol and the like alcohol solvents; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether, etc. Is mentioned. These solvents may be used alone or in combination of two or more.

  Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

Examples of the melt extrusion method include a T-die method and an inflation method. In this case, the film forming temperature is preferably 150 to 350 ° C., more preferably 200 to 300 ° C.
When the film is formed by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and a film that has been extruded into a film can be obtained as a take-up roll. At this time, it is possible to adjust the temperature of the winding roll as appropriate and apply stretching in the extruding direction to achieve a uniaxial stretching step. Moreover, it is also possible to add processes, such as a sequential biaxial stretching and simultaneous biaxial stretching, by adding the process of extending | stretching a film in the direction perpendicular | vertical to an extrusion direction.

  In the present invention, the polymer film used as the support for the retardation film or the protective film for the polarizer may be an unstretched film or a stretched film. When extending | stretching, a uniaxially stretched film may be sufficient and a biaxially stretched film may be sufficient. When a biaxially stretched film is used, it may be biaxially stretched simultaneously or sequentially biaxially stretched. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

  The polymer film may be produced by a hot press method. The hot press stretching method is a method in which biaxial stretching is simultaneously performed in a die using a press compressive force, and is a method of performing tensile stretching. By press-stretching, the plane orientation of the molecular chain of the film sheet can be promoted, and the linear expansion coefficient can be increased while maintaining transparency.

(Retardation film (discotic compound))
The retardation film used in the present invention may have a retardation film formed from a curable composition (preferably a curable liquid crystal composition). The retardation film is preferably formed on a polymer film (or an alignment layer formed thereon) as a support. The alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, or formation of a layer having a microgroup. Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known, but an alignment layer formed by rubbing the surface of a polymer layer is particularly preferable. The rubbing treatment is preferably performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. As the polymer used for the alignment layer, polyimide, polyvinyl alcohol, a polymer having a polymerizable group described in JP-A-9-152509, and the like can be preferably used. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

  The retardation film is formed from a composition containing a liquid crystal compound. It is particularly preferable that the liquid crystal compound has a discotic compound (discotic liquid crystal). The discotic liquid crystal molecule has a disk-like core portion like the triphenylene derivative of D-1, and has a structure in which side chains extend radially therefrom. Further, in order to fix the once aligned state, it is also preferable to further introduce a group that reacts with heat, light or the like. Preferred examples of the discotic liquid crystal are described in JP-A-8-50206.

  The discotic liquid crystal molecules have a pretilt angle in the rubbing direction in the vicinity of the alignment layer and are aligned almost parallel to the film plane. On the opposite air surface side, the discotic liquid crystal molecules stand in a form that is nearly perpendicular to the surface. Oriented. The tilt angle of the discotic liquid crystal molecules near the alignment layer and near the air interface can be controlled by the type of the discotic liquid crystal material, the type of the alignment layer material, the rubbing conditions, and the use of additives. The discotic liquid crystal layer as a whole can be hybrid-aligned, and this layer structure can realize a wide viewing angle of a liquid crystal display device using a protective film.

In general, the retardation film is prepared by preparing a solution in which a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) are dissolved in a solvent, and applying the solution to the surface of the alignment layer, followed by drying. Then, after heating to the discotic nematic phase formation temperature, it can be polymerized by irradiation with UV light or the like, and further cooled. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystal compound is preferably 70 to 300 ° C, particularly preferably 70 to 170 ° C.
The alignment state of the liquid crystal is preferably as uniform as possible, and is preferably a solidified layer fixed in the alignment state.

In addition, the compound other than the liquid crystal compound added to the composition for forming a retardation film has compatibility with the discotic compound and can give a preferable change in tilt angle to the liquid crystal compound or does not inhibit the alignment. As long as any compound can be used. Among these, additives for controlling the orientation on the air interface side such as polymerizable monomers (eg, compounds having vinyl group, vinyloxy group, acryloyl group and methacryloyl group), fluorine-containing triazine compounds, cellulose acetate, cellulose acetate Mention may be made of polymers such as pionate, hydroxypropylcellulose and cellulose acetate butyrate. These compounds are generally used in an amount of 0.1 to 50% by mass, preferably 0.1 to 30% by mass, based on the discotic compound.
The thickness of the retardation film is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

  The retardation film may be a non-liquid crystalline polymer layer prepared by dissolving a non-liquid crystalline compound in a solvent, applying the solution on a support, and heating and drying. In this case, for example, the non-liquid crystalline compound is excellent in heat resistance, chemical resistance, transparency, and has high rigidity, so polyamide, polyimide, polyester, polyether ketone, polyaryl ether ketone, polyamide imide, polyester imide, etc. These polymers can be used. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is preferable because of its high transparency, high orientation, and high stretchability.

  The retardation film can also be produced by stretching a laminate of a non-liquid crystal layer and a support made of a polymer film from 1.05 times to 1.50 times in the tenter transverse axis.

<Polarizing plate>
In the present invention, at least one polarizing plate having at least a polarizer and a retardation film is used. In the transmissive liquid crystal display device, the polarizing plates on the display surface side and the backlight side may be polarizing plates including a retardation film. In the liquid crystal display device, the retardation film is disposed between the polarizer and the liquid crystal cell.

As a preferable range of the polarizing performance of the polarizing plate used in the present invention, 40.0 ≦ TT ≦ 45, 0, 30.0 ≦ PT in the order of single plate transmittance TT, parallel transmittance PT, and orthogonal transmittance CT, respectively. ≦ 40.0, CT ≦ 2.0, and more preferable ranges are 41.0 ≦ TT ≦ 44.5, 34 ≦ PT ≦ 39.0, CT ≦ 1.3 (the unit is%). .
The polarizing plate used in the present invention preferably has a smaller change amount in the polarizing plate durability test. Specifically, the change amount ΔCT (%) of the orthogonal single plate transmittance and the polarization degree change amount ΔP when left at 60 ° C. and 95% RH for 500 hours are at least one of the following formulas (j) and (k): It is preferred that at least one is satisfied.
(J) −6.0 ≦ ΔCT ≦ 6.0
(K) -10.0 ≦ ΔP ≦ 0.0
Here, the amount of change is a value obtained by subtracting the measured value before the test from the measured value after the test.
Satisfying this requirement ensures stability during use or storage of the polarizing plate.
The single plate transmittance TT, parallel transmittance PT, and orthogonal transmittance CT of the polarizing plate can be measured by UV3100PC (manufactured by Shimadzu Corporation) or the like. For example, it can be measured in the wavelength range of 380 nm to 780 nm, and the single plate, parallel, and orthogonal transmittance can be determined by the average value of 10 measurements.
In addition, the polarizing plate durability test is performed in the following manner in two types of forms in which (1) only the polarizing plate and (2) the polarizing plate are attached to glass via an adhesive. For the measurement of only the polarizing plate, two orthogonal and identical ones were prepared and measured so that the optical compensation film was sandwiched between the two polarizers. Two samples (about 5 cm × 5 cm) are prepared by attaching a polarizing plate on a glass so that the optical compensation film is on the glass side. In single-plate transmittance measurement, the sample is set with the film side facing the light source. Each of the two samples is measured, and the average value is taken as the transmittance of the single plate.

  Examples of the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. The iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film.

For the protective film on the liquid crystal cell side surface of the polarizer, it is preferable to use a polymer film similar to that used as a support for the retardation film.
On the other hand, for the protective film on the outer surface of the polarizer (the surface opposite to the liquid crystal cell side), various polymer films can be used in addition to the polymer film. For example, a cellulose acylate film described in detail below. Etc. can be used.

(Cellulose acylate film)
The cellulose acylate film can be formed using a specific cellulose acylate as a raw material. The cellulose acylate used for increasing the optical anisotropy and for decreasing the optical anisotropy may be used properly. The raw material cotton and the synthesis method of the cellulose acylate are described in detail in JIII Journal of Technical Disclosure No. 2001-1745 (issued on March 15, 2001, pages 7-12, JIII). And synthetic methods can be adopted.

  The cellulose acylate film can be produced by any method as long as the cellulose acylate film is usually produced, but it is particularly preferred to produce the cellulose acylate film by a solvent cast method. In the solvent cast method, a film can be produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.

  The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state. Regarding casting and drying methods in the solvent casting method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,37,069, 2,273,070, British Patent 6,407,331, No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

  The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

  A plasticizer can be added to the cellulose acylate film in order to improve mechanical properties or increase the drying rate. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.

The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose acylate, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.
Degradation inhibitors (for example, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines) may be added to the cellulose acylate film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 to 1 of the solution (dope) to be prepared from the viewpoint that the effect of addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferable that it is mass%, and it is further more preferable that it is 0.01-0.2 mass%. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

(Preparation method of polarizing plate)
The polarizing plate can be produced, for example, as follows.
First, the polymer film used as a protective film is surface-treated if necessary. When a cellulose acylate film is used, alkali treatment is effective. A polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution is prepared. A polarizing plate is obtained by bonding the surface-treated surface of the protective film to both surfaces using an adhesive.
Instead of the alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed. Examples of the adhesive used to bond the protective film-treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.

Moreover, it is preferable that the polarizing plate has a pressure-sensitive adhesive layer on the surface because it can be easily bonded to the glass substrate of the liquid crystal cell. For example, in a mode in which the polarizing plate has a configuration of protective film / polarizer / retardation film, the pressure-sensitive adhesive layer is formed on the surface of the retardation film. In an embodiment in which the retardation film has a support made of a polymer film and a retardation film made of a liquid crystal composition formed thereon, the pressure-sensitive adhesive layer is formed on the surface of the retardation film. preferable. In one embodiment of the polarizing plate, a product of a photoelastic coefficient and a thickness of the pressure-sensitive adhesive layer is in a range of −2.0 × 10 ⁻⁵ to −8.5 × 10 ⁻⁵ nm / Pa, and The product of the photoelastic coefficient and the thickness of the retardation film is in the range of −0.05 × 10 ⁻⁵ to + 0.05 × 10 ⁻⁵ nm / Pa.
Of course, the adhesive layer may not be formed in advance, and may be formed on any surface when the polarizing plate and the liquid crystal cell glass substrate are bonded.

  The polarizing plate may have a protective film on one side and a separate film on the other side. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to protect the adhesive bond layer which bonds a polarizing plate to the glass substrate of a liquid crystal cell, and is used for the surface side which bonds a polarizing plate to the glass substrate of a liquid crystal cell.

<Liquid crystal display device>
The transmissive liquid crystal display device has a liquid crystal cell and two polarizing plates arranged on both sides thereof, and the liquid crystal cell carries a liquid crystal between two electrode substrates. Furthermore, one retardation film may be disposed between the liquid crystal cell and one polarizing plate, or two retardation films may be disposed between the liquid crystal cell and both polarizing plates. In the liquid crystal display device of the present invention, the liquid crystal cell substrate and the pressure-sensitive adhesive layer adjacent to the liquid crystal cell substrate satisfy the above relationship, and the effect can be obtained on either the display surface side or the backlight side. Preferably, the display surface side that is more influenced by the use environment preferably satisfies the above relationship, and more preferably both satisfy the above relationship.
The liquid crystal cell is preferably in the TN mode, VA mode, OCB mode, IPS mode or ECB mode, and in particular, the TN mode in which the direction of the polarization axis is 45 ° or 135 ° with respect to the screen action direction. High effects can be obtained in the OCB mode.

  When the polarizing plate is bonded to the liquid crystal cell of various modes, it is preferable that the distance between the central point of the polarizing plate and the central point of the liquid crystal cell is 0 to 10 mm in the direction of the polarizing plate surface. It is more preferable to bond at 5 mm. Here, the center point of the polarizing plate means a point where the diagonal lines intersect when two diagonal lines of the polarizing plate are drawn. Similarly, the center point of the liquid crystal cell means the diagonal line of the liquid crystal cell. It means the point where diagonal lines intersect when two lines are drawn. By laminating as described above, the strain applied to the cell and the polarizing plate can be evenly dispersed, and the effect of improving the unevenness of the present adhesive becomes more prominent. The distance in the polarizing plate surface direction is a distance that considers only the component in the polarizing plate surface direction without considering the distance in the thickness direction of the polarizing plate.

  Moreover, the distance of the said polarizing plate surface direction of each 4 sides of a polarizing plate and each 4 sides corresponding to the glass which comprises the liquid crystal cell on which this polarizing plate was bonded is 0.0-5.0 mm. It is preferable that Here, the side of the polarizing plate and the corresponding side of the glass mean the side closest to the distance. Here, the distance on all four sides is preferably 0.0 to 5.0 mm, and more preferably 0 to 2.0 mm. By setting it as the said range, the retardation which generate | occur | produces with the stress of each member can be canceled, and the cancellation effect of the uneven retardation by an adhesive layer and a board | substrate becomes more remarkable. The distance in the polarizing plate surface direction has the same meaning as described above.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples. “Part” means “part by mass”.

<Production of retardation film>
(Preparation of polymer film 1 for support)
-Preparation of ring-opening polymerized cyclic polyolefin dope The following composition was placed in a mixing tank, stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 µm and a sintered metal filter having an average pore size of 10 µm.
―――――――――――――――――――――――――――――――――
Cyclic polyolefin solution A
―――――――――――――――――――――――――――――――――
Arton G (manufactured by JSR Corporation) 150 parts by mass Methylene chloride 550 parts by mass Ethanol 50 parts by mass ――――――――――――――――――――――――――――― ―――

Next, the following composition containing the ring-opening polymerization cyclic polyolefin solution A prepared by the above method was put into a disperser to prepare a mat agent dispersion.
――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride 75 parts by mass Ethanol 5 parts by mass Cyclic polyolefin solution A 10 parts by mass ――――――――――――― ――――――――――――――――――――

100 parts by mass of the cyclic polyolefin solution and 1.1 parts by mass of the matting agent dispersion were mixed to prepare a dope for film formation.
The above dope was cast using a band casting machine. The film peeled off from the band with a residual solvent amount of about 22% by mass was stretched in the width direction at a stretch rate of 10% using a tenter. Thereafter, the film was transferred from the tenter conveyance to the roll conveyance, and further dried at a temperature of 120 ° C. to 140 ° C. while longitudinally stretching to prepare a cyclic polyolefin film, which was wound up. The thickness of the produced cyclic polyolefin film was 100 μm, Re (550) was 8 nm, and Rth (550) was 80 nm. The photoelastic coefficient was 3 × 10 ⁻¹² Pa ⁻¹ (photoelastic coefficient × thickness was + 0.03 × 10 ⁻⁵ nm / Pa).
This film was subjected to glow discharge treatment (frequency 3000 Hz, 4200 V high frequency voltage applied between the upper and lower electrodes, treatment for 20 seconds) between brass upper and lower electrodes (argon gas atmosphere).
This was used as polymer film 1.

(Preparation of polymer film 2 for support)
“Zeonor ZF-14” (manufactured by ZEON Corporation, thickness 100 μm) was longitudinally stretched at a supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 10% in a longitudinal uniaxial stretching machine. Thereafter, in a tenter stretching machine, a biaxially stretched film was produced by transverse stretching at a supply air temperature of 140 ° C. and a film film surface temperature of 130 ° C. to produce a biaxially stretched film. The thickness of the obtained film was 80 μm, Re (550) was 6 nm, and Rth (550) was 85 nm. The photoelastic coefficient was 5 × 10 ⁻¹² Pa ⁻¹ (photoelastic coefficient × thickness was + 0.04 × 10 ⁻⁵ nm / Pa).
This film was subjected to glow discharge treatment (frequency 3000 Hz, 4200 V high frequency voltage applied between the upper and lower electrodes, treatment for 20 seconds) between brass upper and lower electrodes (argon gas atmosphere).
This was used as polymer film 2.

(Preparation of polymer film 3 for support)
In a 30 L reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, 8000 g of methyl methacrylate (MMA), 2000 g of methyl 2- (hydroxymethyl) acrylate (MHMA), and 10,000 g of 4-methyl -2-pentanone (methyl isobutyl ketone, MIBK) and 5 g of n-dodecyl mercaptan were charged, and the temperature was raised to 105 ° C. while passing nitrogen, and when refluxed, 5.0 g of tertiary butyl par While adding oxyisopropyl carbonate (manufactured by Akzo Kayaku Co., Ltd., trade name: Kaya-Carbon Bic-75), a solution comprising 10.0 g of tertiary butyl peroxyisopropyl carbonate and 230 g of MIBK was added dropwise over 2 hours. Solution under reflux (about 105-120 ° C.) Polymerization was performed, and further aging was performed for 4 hours.

  To the obtained polymer solution, 30 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 120 ° C.) for 5 hours. A condensation reaction was performed. Subsequently, the polymer solution obtained by the above cyclization condensation reaction was vented with a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4 It is introduced into a type screw twin screw extruder (φ = 29.75 mm, L / D = 30) at a processing rate of 2.0 kg / hour in terms of resin amount, and cyclization condensation reaction and devolatilization are carried out in the extruder. A transparent pellet (1A) was obtained by extrusion.

When the obtained pellet (1A) was measured for dynamic TG, a mass loss of 0.17% by mass was detected. Moreover, the weight average molecular weight of the pellet was 133,000, the melt flow rate was 6.5 g / 10 min, and the glass transition temperature was 131 ° C.
The obtained pellet (1A) and acrylonitrile-styrene (AS) resin (manufactured by Toyo Styrene Co., Ltd .; trade name Toyo AS AS20) were mixed with a single screw extruder (φ = 30 mm) at a weight ratio of 1A / AS resin = 90/10. By using and kneading, transparent pellets were obtained. The obtained pellet had a glass transition temperature of 127 ° C.

This pellet was dissolved in methyl ethyl ketone, and a 360 μm film was prepared by a solution casting method. This film was hot press-stretched for 10 minutes at a glass transition temperature of + 10 ° C. (137 ° C.) at an area ratio of 2 to obtain a lactone ring-containing polymer film. The thickness of this film was 90 μm, Re (550) was 9 nm, and Rth (550) was 85 nm. The photoelastic coefficient was −5 × 10 ⁻¹² Pa ⁻¹ (photoelastic coefficient × thickness was −0.05 × 10 ⁻⁵ nm / Pa).
The produced film was subjected to glow discharge treatment (frequency 3000 Hz, 4200 V high frequency voltage applied between the upper and lower electrodes, treatment for 20 seconds) between the upper and lower electrodes made of brass (argon gas atmosphere).
This was used as polymer film 3.

(Preparation of polymer film 4 for support)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
───────────────────────────────────
Cellulose acetate solution composition (parts by mass) Inner layer Outer layer ───────────────────────────────────
Cellulose acetate with an acetylation degree of 60.9% 100 100
Triphenyl phosphate (plasticizer) 7.8 7.8
Biphenyl diphenyl phosphate (plasticizer) 3.9 3.9
Methylene chloride (first solvent) 293 314
Methanol (second solvent) 71 76
1-butanol (third solvent) 1.5 1.6
Silica (particle size 20 nm) 0 0.8
The following retardation increasing agent 1.4 1.4
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The obtained inner layer dope and outer layer dope were cast on a drum cooled to 0 ° C. using a three-layer co-casting die. The film having a residual solvent amount of 70% by mass is peeled off from the drum, both ends are fixed with a pin tenter, and the film is dried at 80 ° C. while being transported at a draw ratio of 110% in the transport direction, so that the residual solvent amount becomes 10%. Where it was dried at 110 ° C. Then, it dried for 30 minutes at the temperature of 140 degreeC, and obtained the cellulose acetate film. The thickness of this film was 80 μm, Re (550) was 6 nm, and Rth (550) was 83 nm. The photoelastic coefficient was 13 × 10 ⁻¹² Pa ⁻¹ (photoelastic coefficient × thickness was + 0.10 × 10 ⁻⁵ nm / Pa).
One side of the cellulose acetate film was coated with 25 ml / m ² of 1.5N potassium hydroxide in isopropyl alcohol and dried at 25 ° C. for 5 seconds. The surface of the film was dried by washing with running water for 10 seconds and blowing air at 25 ° C. In this way, only one surface of the cellulose acetate film was saponified.
This was used as polymer film 4.

(Formation of coating layer)
-Formation of alignment film On each film produced above, a coating solution having the following composition was applied at 24 mL / m ² with a # 14 wire bar coater. The film was dried for 120 seconds with hot air at 100 ° C. to form a film. Next, rubbing treatment was performed on the surface of this film to obtain an alignment film. The rubbing treatment was performed in the 0 ° direction with the longitudinal direction (conveying direction) of the film being 0 °.
(Composition of alignment film coating solution)
The following modified polyvinyl alcohol 40 parts by mass Water 728 parts by mass Methanol 228 parts by mass Glutaraldehyde (crosslinking agent) 2 parts by mass Citric acid ester (AS3, Sankyo Chemical Co., Ltd.) 0.69 parts by mass

-Formation of liquid crystal cured layer The coating liquid for retardation films of the following composition was prepared.
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Coating solution composition ────────────────────────────────────
The following discotic liquid crystal compound (1) 41 parts by mass ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass cellulose acetate butyrate (CAB551-0.2, Eastman Chemical) 0.14 parts by mass cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.22 parts by mass fluoroaliphatic group-containing polymer (Megafac F780, manufactured by Dainippon Ink) 0.45 parts by mass light Polymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.35 parts by mass sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 parts by mass Methyl ethyl ketone 200 parts by mass ───────── ────────────────────────────

The first coating liquid is conveyed at 20 m / min on the rubbing surface of the alignment film by rotating the wire bar # 3.4 at 781 rpm in the same direction as the film conveying direction. It applied continuously to the alignment film surface of the roll film. In the process of continuously heating from room temperature to 100 ° C., the solvent was dried, and then heated in a drying zone at 135 ° C. for about 120 seconds to align the molecules of the discotic liquid crystal compound. Next, it is transported to a drying zone at 100 ° C., and irradiated with ultraviolet rays with an illuminance of 600 mW for 4 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m), and the crosslinking reaction proceeds, The molecules of the tick liquid crystal compound were fixed in the alignment state to form an optically anisotropic layer (first optically anisotropic layer). Thereafter, the film was allowed to cool to room temperature and wound into a cylindrical shape to obtain a roll-like retardation film.
In the manner as described above, each of the films (polymer films 1 to 4) prepared as described above and retardation films 1 to 4 which are laminates of retardation films were prepared. In addition, the photoelastic coefficient as a whole of the retardation films 1 to 4 was equal to each of the polymer films 1 to 4 not forming the retardation film.

<Preparation of adhesive>
An acrylate pressure-sensitive adhesive was prepared according to the following procedure.
・ Acrylate polymer (A1)
In a reaction vessel equipped with a cooling tube, a nitrogen introducing tube, a thermometer and a stirrer, 100 parts of butyl acrylate, 3 parts of acrylic acid, and 0.3 part of 2,2′-azobisisobutyronitrile were mixed with ethyl acetate. In addition, a solid content concentration of 30% was made to react at 60 ° C. for 4 hours under a nitrogen gas stream to obtain an acrylate polymer (A1) solution.

・ Acrylate polymer (A2)
An acrylate polymer (A2) solution was obtained in the same manner except that A1 butyl acrylate was changed to benzyl acrylate.

-Preparation of acrylate-based pressure-sensitive adhesive layer (B1) Next, 0.2 part of trimethylolpropane tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., coronate L), aluminum chelate compound (ALCH) per 100 parts of the acrylate-based polymer (A1). -TR) 0.8 part and 0.1 part of 3-glycidoxypropyltrimethoxysilane were added, and the coating liquid for adhesive layers was prepared. This coating solution was applied to a separate film surface-treated with a silicone release agent using a die coater and dried at 150 ° C. for 3 hours to form an acrylate pressure-sensitive adhesive layer (B1).
The used crosslinking agent, Coronate L (Nippon Polyurethane), as shown in Table 1 below, is a crosslinking agent having two or more aromatic rings, and ALCH-TR (Kawaken) is an aluminum chelate compound.

  The addition amount and / or coating amount of the crosslinking agent is changed, and the acrylic polymer 2 is used together with the acrylic polymer 1 (B13), and the pressure-sensitive adhesive layers (B2 to B14) shown in Table 1 below are respectively separated films. Formed on top.

(Measurement of photoelastic coefficient of adhesive layer)
Using an ellipsometer M-220 manufactured by JASCO at an ambient temperature and humidity of 25 ° C. and 60%, a tensile force is applied to the adhesive sample having a thickness of 0.5 μm and a 2 cm square from 0 to 10 N from both ends, and the wavelength is 630 nm. The photoelastic coefficient was measured. When the load area of the sample changed due to deformation, the amount of deformation was measured with a measure, the area was corrected, and an accurate stress was calculated.

<Liquid crystal display device (TV for evaluation)>
The liquid crystal display device (TV for evaluation) of the present invention was produced according to the following procedure.
A 120 μm-thick polyvinyl alcohol film was immersed in an aqueous solution containing 1 part by mass of iodine, 2 parts by mass of potassium iodide, and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer. As the polarizing plate protective film, a commercially available TD80 (manufactured by FUJIFILM Corporation) was used.
LW-2601DFK (manufactured by Bidesign) was purchased as a TN mode liquid crystal cell for evaluation, and prepared by peeling off the front and back polarizing plates.
This cell was disassembled, and the product of the photoelastic coefficient and the thickness of the glass substrate was measured and found to be 0.21 × 10 ⁻⁵ nm / Pa.

(Preparation of polarizing plate for TN mode evaluation)
After TD80 was immersed in an aqueous sodium hydroxide solution at a concentration of 1.5 mol / L and 55 ° C., the sodium hydroxide was sufficiently washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at a concentration of 0.005 mol / L for 1 minute 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 saponification treatment was performed in the same manner for the polymer films of the retardation films 1 to 4 produced above. The obtained saponified film was bonded using a polyvinyl alcohol adhesive so as to sandwich the polarizer, and a polarizing plate was produced. In addition, about retardation film 1-4, each of the polymer films 1-4 which are a support body, and the polarizer were made to contact and bonded together.
Next, a separate film having any one of the pressure-sensitive adhesive layers B1 to B14 is formed on the surface of any one of the produced polarizing plates with TD80 / polarizer / any of optical films 1 to 4 / pressure-sensitive adhesive layers B1 to B14. After laminating so as to be in the order of either / separator film, the film was aged at 25 ° C. and 60% RH for 7 days to prepare polarizing plates having combinations shown in Table 2 below. Each obtained polarizing plate was used as a front side polarizing plate and a rear side polarizing plate, respectively.

Each of the produced polarizing plates for evaluation was evaluated for light leakage by the following method.
Each of the produced polarizing plates was cut into a screen size. For each of the cut polarizing plates, the transmission axis of the polarizing plate with respect to the display surface of the liquid crystal cell for evaluation, 45 ° for the front side polarizing plate and 135 ° for the rear side polarizing plate (however, the horizontal direction of the display surface is 0 °) The vertical direction was 90 °), and the transmission axes of the polarizing plates were attached to both sides of the panel with the front and rear orthogonal. In this way, a liquid crystal TV for evaluation was produced.
Each liquid crystal TV for evaluation was autoclaved at a temperature of 50 ° C. and a pressure of 0.5 MPa for 30 minutes, and then treated at 80 ° C. dry for 1000 hours. Then, after storing at 25 ° C. and 60% for 24 hours, the presence or absence of light leakage in the vicinity was visually observed and evaluated. The evaluation criteria are shown below.
(Evaluation criteria)
5: When light leakage was not observed 4: Light leakage was slightly observed but there was no problem in practical use 3: Light leakage was observed to be weak but there was no problem in practical use 2: Light In the case where the occurrence of leakage is strongly observed but there is no problem in practical use 1: In the case where the occurrence of light leakage is observed at a level having a practical problem, the peeling state of the polarizing plate after the wet heat treatment was observed. The obtained results are shown in Table 2 below. The light leakage before the wet heat treatment was evaluated as “5” with no problem in any sample.

It is a cross-sectional schematic diagram about a part of an example of the liquid crystal display device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal layer 12 Glass substrate 14 Adhesive layer 16 Liquid crystal cured layer 18 Support body 20 Polarizer 22 Protective film LC Liquid crystal cell F Phase difference film PL Polarizing plate

Claims (10)

A liquid crystal display device having a polarizing plate including at least a polarizer and a retardation film and a liquid crystal cell including at least a glass substrate, wherein the polarizing plate is bonded to the surface of the glass substrate by an adhesive layer. The retardation film is disposed between the polarizer and the pressure-sensitive adhesive layer, and the product of the photoelastic coefficient and the thickness of the pressure-sensitive adhesive layer is −2.0 × 10 ⁻⁵ to −8.5 ×. 10 ⁻⁵ nm / Pa, the product of the photoelastic coefficient and the thickness of the glass substrate is 0.14 × 10 ^{−5 to} 0.28 × 10 ⁻⁵ nm / Pa, and the retardation film A liquid crystal display device, wherein a product of a photoelastic coefficient and a thickness is −0.05 × 10 ⁻⁵ to + 0.05 × 10 ⁻⁵ nm / Pa. The ratio of the absolute value of the product of the photoelastic coefficient and the thickness of each of the pressure-sensitive adhesive layer and the glass substrate (pressure-sensitive adhesive layer / glass substrate) is 9.0 to 35.0. 2. A liquid crystal display device according to 1. The liquid crystal display device according to claim 1, wherein the retardation film is made of a film containing an alicyclic hydrocarbon-based polymer or has at least the film. The liquid crystal display device according to claim 1, wherein the retardation film is made of a film containing a lactone ring-containing polymer or has at least the film. 5. The liquid crystal display device according to claim 1, wherein the retardation film has at least a support made of a polymer film and a retardation film formed of a curable composition. . The liquid crystal display device according to claim 5, wherein the retardation film contains discotic molecules fixed in an aligned state. The said adhesive layer is a layer formed from the composition containing at least 1 sort (s) of an acrylate-type polymer and at least 1 sort (s) of a crosslinking agent, The any one of Claims 1-6 characterized by the above-mentioned. Liquid crystal display device. The liquid crystal display device according to any one of claims 1 to 7, wherein the polarizer is arranged with a transmission axis of 45 degrees with respect to a horizontal direction of the display surface of the liquid crystal cell. The liquid crystal display device according to claim 1, wherein a display mode of the liquid crystal cell is a TN mode. A polarizing plate comprising at least a polarizer, a retardation film and an adhesive layer in this order,
The product of the photoelastic coefficient and the thickness of the pressure-sensitive adhesive layer is −2.0 × 10 ⁻⁵ to −8.5 × 10 ⁻⁵ nm / Pa, and the photoelastic coefficient and the thickness of the retardation film are A polarizing plate characterized by having a product of −0.05 × 10 ⁻⁵ to + 0.05 × 10 ⁻⁵ nm / Pa.

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