KR20200040922A - Liquid crystal display device - Google Patents

Abstract

The present invention provides a liquid crystal display device capable of highly controlling the curl of a laminate composed of a polarizing plate / liquid crystal cell / polarizing plate in a liquid crystal display device.
A liquid crystal display device having a liquid crystal cell, a polarizing plate A attached to one side of a liquid crystal cell, and a polarizing plate B attached to the other side of a liquid crystal cell, wherein in the polarizing plate A, the direction of the transmission axis of the polarizer is a long side of the liquid crystal display device. Parallel to the direction, a structure in which a polyester film is laminated on at least one side of the polarizer. In the polarizing plate B, the absorption axis direction of the polarizer is parallel to the long side direction of the liquid crystal display, and a protective film is laminated on at least one side of the polarizer. Structure, the contraction force F _{f in} the long side direction of the liquid crystal display device of the polyester film, and the contraction force F _p in the long side direction of the liquid crystal display device of the polarizer of the polarizing plate B satisfies the expression of 0.1≤ F _f / F _p ≤2 It is a liquid crystal display device characterized in that.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device used in a PC monitor, a television, and the like.

In order to reduce the weight of the liquid crystal display device, there is a tendency to thin the glass substrate, and conventional 0.7 mm to 0.5 mm or less, furthermore 0.3 mm, etc. are being considered, and it is thought that further thinning will proceed in the future. Since the glass substrate in a liquid crystal display has an effect of suppressing curl due to the enumeration movement of a polarizing plate, the curl suppression effect significantly decreases with the decrease in the thickness of the glass substrate, and is present in the liquid crystal display. The problem of curvature of a laminate composed of a polarizing plate / liquid crystal cell / polarizing plate to be said is currently being developed.

Conventionally, many studies have been proposed to suppress curl of a laminate composed of a polarizing plate / liquid crystal cell / polarizing plate. For example, in Patent Document 1, a viewing side disposed above and below a liquid crystal cell of a liquid crystal display device is provided. In the polarizing plate on the backlight side, by controlling the elastic modulus in the long side direction of each polarizing plate, and also taking into account the difference in the environment in which the upper and lower polarizing plates are placed, the elastic modulus of the upper and lower polarizing plates is different to improve the curvature of the liquid crystal display device. Is proposing. In addition, Patent Document 2 focuses on the difference between the shrinking force in the absorption axis direction and the transmission axis direction of the polarizing plate, and improves the warp of the display device by reducing the shrinking force of the shrinking main polarizing plate at high temperature or high temperature and high humidity. .

Japanese Patent Publication No. 2006-267503 WO2014-204165A

However, in Patent Literature 1 or Patent Literature 2, improvement studies have been conducted by controlling the warpage accompanying temperature changes and the warpage caused by moisture absorption and moisture absorption, while the glass transition temperature of polyethylene terephthalate films and the like is low. The effect of residual distortion (heat shrinkage) of the film, which should be considered when using the film, was not taken into account.

That is, the problem to be solved by the present invention is to provide a liquid crystal display device capable of highly controlling the curl of a laminate composed of a polarizing plate / liquid crystal cell / polarizing plate in a liquid crystal display device.

In a liquid crystal display device, a polarizing plate is usually laminated on one surface of a liquid crystal cell so that the direction of the transmission axis of the polarizer is parallel to the long side direction of the liquid crystal display, and on the other surface, the direction of the absorption axis of the polarizer is liquid crystal display. The polarizing plates are laminated so as to be parallel to the long side direction of the device. As a result of careful examination using various commercially available liquid crystal display devices, the problem of shape factors that tends to cause curling due to shrinkage of the polarizing plate having a long shrinkage polarizer absorption axis direction (curls generally occur in the long direction) However, by the influence of the asymmetrical configuration of the upper and lower polarizing plates in the liquid crystal panel, the present inventors believe that the liquid crystal panel is convex toward the polarizing plate side where the polarizer transmission axis of the upper and lower polarizing plates arranged in cross nicol is a long side. Found.

In addition, as a result of careful examination, it becomes clear that the contraction force in the long direction of the polarizing plate where the polarizer transmission axis becomes a long side can be controlled by the residual warping of the protective film, and the contraction force controls the curl of the liquid crystal display device. I knew what I could do.

Here, a method for measuring the shrinkage force of the polarizing plate will be described. In general, the shrinkage force of the film is set using a TMA or the like, the initial length is set to a minimum load at a low temperature state of the start of the test, and the force in the shrinking direction during heating is measured while maintaining the length of the initial length. However, during the temperature increase process, shrinkage due to recovery of residual distortion accompanying the change in the polymer composition (hereinafter referred to as thermal contraction only) and thermal expansion due to an increase in the free volume and the occupied volume of the polymer due to the temperature increase (hereinafter referred to as thermal shrinkage) Since only the thermal expansion occurs), in the temperature range around the glass transition temperature of the polyester film (for example, about ∼Tg + 50 ° C), the film generally expands due to the fact that it is a relationship of thermal contraction <thermal expansion. , No shrinkage force is observed.

As a result of the examination, it became clear that the shrinkage force occurred in the TMA cooling process even if the shrinkage force did not occur during the TMA heating process. This is because the warpage caused by thermal expansion is a reversible change, so it returns to the original state after the temperature increase cooling, but due to the fact that it is cooled in a state with a small size as the heat shrinkage contracted during the temperature increase process, thermal stress occurs in the cooling process. . That is, the warpage of the thermal stress can be replaced with the thermal contraction rate of the film, and the shrinkage force after cooling is expressed by the following equation. In addition, the thermal contraction rate in this invention contains the change of the moisture content during heat processing.

Shrinking force (N / m)

= Film thickness (mm) × Elastic modulus (N / mm) × Heat shrinkage ratio (%) ÷ 100 × 1000

That is, the typical present invention is as follows.

Item 1.

A liquid crystal display device comprising a liquid crystal cell, a polarizing plate A attached to one side of a liquid crystal cell, and a polarizing plate B attached to the other side of a liquid crystal cell,

The polarizing plate A has a structure in which the transmission axis direction of the polarizer is parallel to the long side direction of the liquid crystal display, and a polyester film is laminated on at least one side of the polarizer.

The polarizing plate B has a structure in which the absorption axis direction of the polarizer is parallel to the long side direction of the liquid crystal display, and a protective film is laminated on at least one side of the polarizer,

A liquid crystal display device characterized in that the contraction force F _{f in} the long direction of the liquid crystal display of the polyester film and the contraction force F _p in the long direction of the liquid crystal display of the polarizer of the polarizing plate B satisfy the following formula (1).

Equation (1) 0.1≤F _f / F _p ≤2

(However, the shrinkage force F _f (N / m) is the thickness (mm) of the polyester film x elastic modulus (N / mm) x heat shrinkage ratio (%) ÷ 100 x 1000, and the shrinkage force F _p (N / m) is The thickness of the polarizer of the polarizing plate B is (mm) x modulus (N / mm) x heat shrinkage (%) ÷ 100 x 1000.)

Item 2.

The liquid crystal display device according to claim 1, wherein the elastic modulus in the long direction of the liquid crystal display device of the polyester film is 1000 to 9000 N / mm 2.

Section 3.

The liquid crystal display device according to item 1 or 2, wherein the heat shrinkage in the long side direction of the liquid crystal display device of the polyester film is 0.1 to 5%.

Item 4.

The liquid crystal display device according to any one of items 1 to 3, wherein the thickness of the polyester film is 40 to 200 μm.

Clause 5.

The liquid crystal display device according to any one of items 1 to 4, wherein an inclination of the main axis of alignment of the polyester film with respect to a long side direction or a short side direction of the liquid crystal display device is 15 degrees or less.

Clause 6.

The liquid crystal display device according to any one of items 1 to 5, wherein the inclination of the main axis of shrinkage of the polyester film with respect to the long side direction or the short side direction of the liquid crystal display device is 15 degrees or less.

Section 7.

A liquid crystal panel comprising a liquid crystal cell, a polarizing plate A attached to one side of a liquid crystal cell, and a polarizing plate B attached to the other side of a liquid crystal cell,

The polarizing plate A has a structure in which the transmission axis direction of the polarizer is parallel to the long side direction of the polarizing plate A, and a polyester film is laminated on at least one side of the polarizer.

The polarizing plate B has a structure in which the absorption axis direction of the polarizer is parallel to the long side direction of the polarizing plate B, and a protective film is laminated on at least one side of the polarizer,

A liquid crystal panel in which the contraction force F _f of the polarizing plate A of the polyester film in the long side direction and the contracting force F _p of the polarizing plate B of the polarizer of the polarizing plate B satisfy the following formula (1).

Equation (1) 0.1≤F _f / F _p ≤2

(However, the shrinkage force F _f (N / m) is the thickness (mm) of the polyester film x elastic modulus (N / mm) x heat shrinkage ratio (%) ÷ 100 x 1000, and the shrinkage force F _p (N / m) is The thickness of the polarizer of the polarizing plate B is (mm) x modulus (N / mm) x heat shrinkage (%) ÷ 100 x 1000.)

Item 8.

The liquid crystal panel according to item 7, wherein the elastic modulus in the long direction of the polarizing plate A of the polyester film is 1000 to 9000 N / mm 2.

Item 9.

The liquid crystal panel according to item 7 or 8, wherein the heat shrinkage in the long direction of the polarizing plate A of the polyester film is 0.1 to 5%.

Item 10.

The liquid crystal panel according to any one of items 7 to 9, wherein the thickness of the polyester film is 40 to 200 μm.

Clause 11.

The liquid crystal panel according to any one of items 7 to 10, wherein the inclination of the main axis of the alignment of the polyester film with respect to the long side direction or the short side direction of the liquid crystal panel is 15 degrees or less.

Item 12.

The liquid crystal panel according to any one of items 1 to 5, wherein the inclination of the shrinkage principal axis of the polyester film with respect to the long side direction or the short side direction of the liquid crystal panel is 15 degrees or less.

It is possible to provide a liquid crystal display device with reduced curl of a laminate (liquid crystal panel) made of a polarizing plate / liquid crystal cell / polarizing plate generated under a high temperature or high temperature and high humidity environment.

The screen of the liquid crystal display is usually rectangular, and has long sides and short sides. In the present specification, the "long side direction of the liquid crystal display device" is a direction parallel to the long side of the liquid crystal display device, "long side direction of the polarizing plate A", "long side direction of the polarizing plate B", "long side direction of the polarizer of the polarizing plate B" It is the same as "," the long side direction of the polyester film of the polarizing plate A. " Therefore, in the present specification, the "long side direction of the polarizing plate A", "long side direction of the polarizing plate B", "long side direction of the polarizer of the polarizing plate B", "polyester of the polarizing plate A" means "long side direction of the polarizing plate B" It can also be read in the direction of the long side of the film. The "short side direction of the liquid crystal display device" means a direction parallel to the short side of the liquid crystal display device and means a direction perpendicular to the long side direction.

The liquid crystal display device of the present invention has at least a liquid crystal cell, a polarizing plate A affixed to one side of the liquid crystal cell, and a polarizing plate B affixed to the other side of the liquid crystal cell. The liquid crystal cell and the polarizing plate can usually be pasted through an adhesive layer. In addition to a liquid crystal cell, a polarizing plate A, and a polarizing plate B, a liquid crystal display device may include a structural member commonly used in a liquid crystal display device such as a backlight. The liquid crystal cell has a structure in which liquid crystal is sandwiched between two glass substrates. In one embodiment, the thickness of the glass substrate constituting the liquid crystal cell is preferably 0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, or 0.25 mm or less.

In the polarizing plate A, the direction of the transmission axis of the polarizer is parallel to the long side direction of the liquid crystal display (ie, the direction of the transmission axis of the polarizer is parallel to the direction of the long side of the polarizing plate A), and a polyester film (polarizer on at least one side of the polarizer) It is used as a protective film) has a laminated structure. A protective film or optical compensation film having low retardation such as a TAC film, a cyclic olefin film, or an acrylic film can be laminated on a surface opposite to the surface on which the polyester film of the polarizer is laminated. Here, the protective film having low retardation may be, for example, a protective film having a retardation of 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, or 50 nm or less. Moreover, the polarizing plate A is also one of the preferable structures in which a polyester film is laminated on only one side of the polarizer, and a protective film or an optical compensation film is not laminated on the other side of the polarizer. The polyester film can be disposed on one side (or both sides) of the liquid crystal cell side of the polarizer and the distal side (outside) of the liquid crystal cell, but is disposed on the distal side (outside) of the polarizer liquid crystal cell. It is preferred.

Although the direction of the transmission axis of the polarizer is parallel to the long side direction of the liquid crystal display device, it is most preferably perfectly parallel, but is a concept that allows slight deviation. That is, the angle between the transmission axis direction of the polarizer and the long side direction of the liquid crystal display device is preferably 7 degrees or less, preferably 5 degrees or less, preferably 3 degrees or less, preferably 2 degrees or less, and 1 degree or less Is preferred, and most preferably 0 degrees.

In the polarizing plate B, the absorption axis direction of the polarizer is parallel to the long side direction of the liquid crystal display (that is, the absorption axis direction of the polarizer is parallel to the long side direction of the polarizing plate B), and a protective film is laminated on at least one side of the polarizer Structure. A protective film or an optical compensation film having low retardation such as a TAC film, a cyclic olefin film, or an acrylic film can be laminated on the protective film. Here, the protective film having low retardation may be, for example, a protective film having a retardation of 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, or 50 nm or less. Moreover, a polyester film can also be laminated | stacked on a polarizer as a protective film. When using a polyester film, it is preferable to laminate | stack on the distal side with the liquid crystal cell of a polarizer.

The polarizing plate B may have a structure in which a polyester film is laminated on one side of the polarizer and the above-described protective film or optical compensation film is laminated on the other side. Moreover, the polarizing plate B is also one of the preferable forms in which a polyester film is laminated on only one side of the polarizer, and a protective film or an optical compensation film is not laminated on the other side of the polarizer.

Although it is most preferable that the direction of the absorption axis of the polarizer is parallel to the long side direction of the liquid crystal display, it is most preferably parallel, but allows slight misalignment. That is, the angle between the absorption axis direction of the polarizer and the long side direction of the liquid crystal display device is preferably 7 degrees or less, preferably 5 degrees or less, preferably 3 degrees or less, preferably 2 degrees or less, and 1 degree or less Is preferred, and most preferably 0 degrees.

The polarizing plate A may be used for either the viewing side polarizing plate or the backlight side polarizing plate than the liquid crystal cell, but is generally preferably disposed as the backlight side polarizing plate. The polarizing plate B may be used for either the viewing side polarizing plate or the backlight side polarizing plate than the liquid crystal cell, but is generally preferably disposed as the viewing side polarizing plate. That is, a liquid crystal display device having a backlight light source, a polarizing plate A, a liquid crystal cell, and a polarizing plate B in this order is preferable. Moreover, the liquid crystal display device may include another member between them.

In the liquid crystal display device of the present invention, it is preferable that 0.1 ≤ F _f / F _p ≤ 2. It is preferable that the lower limit of F _f / F _p is 0.2 or 0.3. The upper limit of F _f / F _p is preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8 or 0.7. In one embodiment, 0.1≤F _f / F _p ≤1.0, 0.1≤F _f / F _p <1.0, 0.1≤F _f / F _p ≤0.9, 0.1≤F _f / F _p ≤0.8, 0.2≤F _f it / F of _p ≤0.8, or 0.3≤F _f / F _p ≤0.7 is preferred.

Here, F _f refers to the shrinking force in the long side direction of the liquid crystal display device of the polyester film of the polarizing plate A, and is defined as polyester film thickness (mm) × elastic modulus (N / mm) × heat shrinkage ratio (%) ÷ 100 × 1000 do. F _p indicates the contraction force in the long side direction of the liquid crystal display of the polarizer of the polarizing plate B, and is defined as the thickness (mm) × elastic modulus (N / mm) × thermal shrinkage (%) ÷ 100 × 1000 of the polarizer of the polarizing plate B. In the equations of the shrinkage forces F _f and F _p , both the modulus of elasticity and thermal contraction are values in the long direction of the liquid crystal display. The shrinking force of the polarizing plate B is mainly expressed by the polarizer, and the shrinking force varies depending on the thickness of the polarizer or film forming conditions. Therefore, it is preferable to adjust the shrinkage force of the polyester film used for the polarizing plate A accordingly.

The polyester film used for the polarizing plate A preferably has a modulus of elasticity of 1000 to 9000 N / mm 2 in the long side direction of the liquid crystal display device. The shrinkage force of the polyester film can be controlled by the elastic modulus, but in order to increase the elastic modulus in the long side direction of the liquid crystal display device, it is necessary to highly align it in the long side direction of the liquid crystal display device and further increase the crystallinity. Therefore, when the elastic modulus in the long side direction exceeds 9000 N / mm 2, problems such as cracking are present, and the upper limit is preferably 9000 N / mm 2, more preferably 8000 N / mm 2, more preferably Is 7000N / ㎟. On the other hand, when the orientation is low and the crystallinity is low, the film is deformed due to unevenness of the roll due to the thickness variation when wound on the roll, and remains flat. Therefore, the lower limit of the elastic modulus is preferably 1000 N / mm 2, more preferably 1500 N / mm 2, and even more preferably 1800 N / mm 2. The modulus of elasticity can be measured by the method employed in Examples described later.

The polyester film used for the polarizing plate A preferably has a heat shrinkage of 0.1 to 5% in the long direction of the liquid crystal display device at a heat treatment of 100 ° C for 30 minutes. The lower limit of the heat shrinkage ratio is preferably 0.3% or more, preferably 0.4% or more, preferably 0.5% or more, and preferably 0.7% or more. The upper limit of the heat shrinkage rate is preferably 4% or less, preferably 3% or less, and preferably 2% or less. When the heat shrinkage is lower than 0.1%, that is, in the range of 0.01 to 0.099%, it is difficult to control the heat shrinkage without unevenness. In addition, in order to increase the heat shrinkage ratio to more than 5%, it is necessary to further lower the crystallinity and glass transition temperature as described later, whereby problems such as poor flatness become remarkable. The heat shrinkage rate can be measured by the method employed in Examples described later.

It is preferable that the polyester film used for polarizing plate A has a thickness of 40-200 micrometers. When the thickness of the polyester film is less than 40 µm, it is fragile, and it is liable to be poor in planarity due to insufficient rigidity. Moreover, in the case of thinness, it is necessary to increase the elastic modulus or heat shrinkage in the long side accordingly, but as described above, since each parameter also has an upper limit, the practically 40 µm is the lower limit. Moreover, when the film thickness is more than 200 µm, the unevenness in the elastic modulus or thermal contraction rate in the long side direction increases accordingly, and the control is difficult and the cost increases. The thickness of the polyester film can be measured by the method employed in Examples described later.

The polyester film used for the polarizing plate A preferably has an inclination between the main axis of orientation of the polyester film and the long side direction or the short side direction of the liquid crystal display device of 15 degrees or less. The stretched polyester film usually has an anisotropy of elastic modulus in the film plane, but anisotropy and optical anisotropy of the elastic modulus of the stretched polyester film generally coincide. Therefore, for the orientation main axis judged from the optical anisotropy, by setting the angle of incidence with the long side direction or the short side direction of the liquid crystal display device to be 15 degrees or less, the direction with high elastic modulus is the long side direction or the short side direction of the liquid crystal display device. As it approaches, it is effective in suppressing the curl of the laminate composed of the polarizing plate / liquid crystal cell / polarizing plate which is the object of the present invention. When the orientation main axis has a narrow angle with the long side direction or the short side direction of the liquid crystal display device exceeding 15 degrees, the tendency for curl to occur in an oblique direction becomes remarkable. The inclination is more preferably 10 degrees or less, 9 degrees or less, or 8 degrees or less. The orientation principal axis of the polyester film can be measured according to the measurement method employed in Examples described later.

It is preferable that the polyester film used for the polarizing plate A has a narrow angle of 15 degrees or less with respect to the shrinkage principal axis of the polyester film with the long side direction or the short side direction of the liquid crystal display device. The stretched polyester film usually has anisotropy of heat shrinkage in the film plane, and also has a slope on the shrinkage main axis. When the narrowing angle between the contracted main axis and the long side direction or the short side direction is larger than 15 degrees, the tendency for curl to occur in an oblique direction becomes remarkable, which is not preferable. Therefore, the narrow angle between the shrinkage principal axis of the polyester film used for the polarizing plate A and the long side direction or the short side direction of the liquid crystal display device is preferably 15 degrees or less, more preferably 10 degrees or less, 9 degrees or less, or 8 degrees or less. Do. The shrinkage principal axis can be measured according to the measurement method employed in Examples described later.

The polyester film used for the polarizing plate A preferably has an in-plane retardation in a specific range from the viewpoint of suppressing rainbow unevenness observed on the screen of the liquid crystal display device. The lower limit of in-plane retardation is preferably 3000 nm or more, 5000 nm or more, 6000 nm or more, 7000 nm or more, or 8000 nm or more. The upper limit of the in-plane retardation is preferably 30000 nm or less, more preferably 18000 nm or less, still more preferably 15000 nm or less. Moreover, when using a polyester film as a protective film also for polarizing plate B, it is preferable that the polyester film also has in-plane retardation of the said range.

The retardation of the polyester film can also be obtained by measuring the refractive index and thickness in the biaxial direction, or by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.). In addition, the refractive index can be obtained with an Abbe's refractive index meter (measurement wavelength: 589 nm).

The polyester film used for the polarizing plate A has a ratio (Re / Rth) of in-plane retardation (Re) to retardation (Rth) in the thickness direction, preferably 0.2 or more, preferably 0.3 or more, preferably 0.4 Above, it is more preferably 0.5 or more, and still more preferably 0.6 or more. The larger the ratio (Re / Rth) of the in-plane retardation and the thickness-direction retardation, the more birefringent action is to increase the isotropy, which tends to make it difficult to generate rainbow-colored stains depending on the viewing angle. In a complete uniaxial (single-axis symmetry) film, the ratio (Re / Rth) of the retardation and the thickness direction retardation is 2.0, so the upper limit of the ratio (Re / Rth) of the retardation and the thickness direction retardation is 2.0 is preferred. The preferred upper limit of Re / Rth is 1.2 or less. Moreover, the thickness direction retardation means the average of the retardation obtained by multiplying the film thickness d by two birefringence (DELTA) Nxz and (DELTA) Nyz when the film is viewed from the cross section in the thickness direction. Moreover, when using a polyester film as a protective film also for polarizing plate B, it is preferable that the ratio (Re / Rth) of the in-plane retardation (Re) and the thickness direction retardation (Rth) is also the said polyester film in the said range. .

The polyester film used for the polarizing plate A has a NZ coefficient of preferably 2.5 or less, more preferably 2.0 or less, still more preferably 1.8 or less, even more preferably from the viewpoint of suppressing rainbow-colored stains more. It is 1.6 or less. In addition, since the NZ coefficient is 1.0 in a complete uniaxial (single axis symmetry) film, the lower limit of the NZ coefficient is 1.0. However, care should be taken as the mechanical strength in the direction perpendicular to the orientation tends to decrease remarkably as it approaches the complete uniaxial (uniaxially symmetric) film. Moreover, when using a polyester film as a protective film also for polarizing plate B, it is preferable that the polyester film also has a NZ coefficient in the said range.

The NZ coefficient is represented by | Ny-Nz | / | Ny-Nx |, where Ny is the refractive index in the slow axis direction of the polyester film, and Nx is the refractive index in the direction orthogonal to the slow axis (advanced axis). The refractive index in the (방향 相 進) direction) and Nz represent the refractive index in the thickness direction. The orientation axis of the film is obtained by using a molecular orientation system (MOA-6004 molecular orientation system manufactured by Oji Scientific Instruments Co., Ltd.), and the refractive index of two axes (Ny, Nx, Ny> in the direction perpendicular to the orientation axis direction) Nx) and the refractive index (Nz) in the thickness direction are determined by Abbe's refractive index meter (manufactured by Atago, NAR-4T, measurement wavelength: 589 nm). The NZ coefficient can be obtained by substituting the value thus obtained for | Ny-Nz | / | Ny-Nx |.

Moreover, as for the polyester film used for the polarizing plate A, from the viewpoint of suppressing rainbow-colored stain more, the value of Ny-Nx of the polyester film is preferably 0.05 or more, more preferably 0.07 or more, even more preferably Is 0.08 or more, even more preferably 0.09 or more, and most preferably 0.1 or more. Although the upper limit is not particularly determined, in the case of a polyethylene terephthalate-based film, the upper limit is preferably about 1.5. When using a polyester film as a protective film also for polarizing plate B, it is preferable that the value of Ny-Nx also exists in the said polyester film in the said range.

The polyester film used for polarizing plate A can be obtained from arbitrary polyester resins. The type of the polyester resin is not particularly limited, and any polyester resin obtained by condensing dicarboxylic acid and diol can be used. Moreover, when using a polyester film as a protective film also for polarizing plate B, the polyester film is also the same.

Examples of the dicarboxylic acid component usable in the production of the polyester resin include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,4-naphthalene Dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfoniccarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclophene tandicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2, 2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecanedicarboxylic acid and the like.

Diol components that can be used in the production of polyester resins include, for example, ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and deca Methylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxy And phenyl) sulfones.

As the dicarboxylic acid component and the diol component constituting the polyester resin, either one or two or more of them can be used. Suitable polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and more preferably polyethylene terephthalate and polyethylene. Although naphthalate is mentioned, these may further contain other copolymerization components. These resins are excellent in transparency and excellent in thermal and mechanical properties. Particularly, polyethylene terephthalate is a suitable material in that it can achieve a high modulus of elasticity and control heat shrinkage is relatively easy.

When it is necessary to increase the thermal contraction rate of a polyester film highly, it is preferable to add a copolymerization component to appropriately lower the crystallinity. Moreover, since the ratio of elastic warping or permanent warping is high for deformations below the glass transition temperature, it is generally difficult to increase the thermal contraction rate to a high level. Therefore, it is also a preferable embodiment to introduce a component having a low glass transition temperature, if necessary. Specifically, it is propylene glycol, 1,3-propanediol, and the like.

(Grant of functional layer)

Since the polarizing plate A used in the liquid crystal display device of the present invention is preferably integrated with the glass plate of the liquid crystal cell in a state in which the thermal contraction rate of the polyester film remains, the easily bonding layer, the hard coat layer, and the anti-glare layer When providing functional layers such as an antireflection layer, a low reflection layer, a low antireflection layer, and an antireflection antiglare layer, an antistatic layer, the drying temperature is set to be low, or a method having a small thermal history such as UV irradiation or electron beam irradiation is performed. This is a preferred embodiment. Moreover, providing these functional layers during the film forming process of the polyester film is a more preferable embodiment because it becomes possible to integrate the polarizing plate A with the glass plate of the liquid crystal cell without impairing the increased heat shrinkage.

(Method for producing oriented polyester film)

The polyester film used in this invention can be manufactured according to the manufacturing method of a general polyester film. For example, the non-oriented polyester formed by melting the polyester resin and extruding into a sheet form is stretched in the longitudinal direction using a difference in the speed of the roll at a temperature equal to or higher than the glass transition temperature, followed by a tenter. The method of extending | stretching in a horizontal direction and performing heat processing is mentioned. It may be a uniaxially stretched film or a biaxially stretched film. In addition, MD is an abbreviation of Machine Direction, and in this specification, it may be called a film flow direction, a longitudinal direction, and a vertical direction. In addition, TD is an abbreviation of Transverse Direction, and in this specification, it may be called a width direction and a horizontal direction.

It is preferable to adjust the shrinkage force F _f so that the polyester film used as a polarizer protective film for the polarizing plate A becomes 0.1F _p ≤ F _f ≤ 2F _p .

(How to adjust the elastic modulus of the polyester film)

The elastic modulus of the polyester film used as the polarizer protective film for the polarizing plate A is the elastic modulus of MD when the polarizer transmission axis direction (i.e., the long side direction of the liquid crystal display device) coincides with the MD at the time of film formation of the polyester film. When it matches with TD at the time of film formation of an ester film, you may adjust the elastic modulus of TD by the conventionally well-known method of a stretched polyester film.

Specifically, if the direction is the stretching direction, the stretching magnification is high, and when the direction is the direction perpendicular to the stretching direction, the stretching magnification may be set low.

(How to adjust the heat shrinkage rate of polyester film)

The thermal contraction rate of the polyester film used as a polarizer protective film for the polarizing plate A is the thermal contraction rate of MD when the transmissive axis direction of the polarizer (that is, the long side direction of the liquid crystal display device) matches the MD at the time of film formation of the polyester film. When the TD at the time of forming the polyester film is consistent, the heat shrinkage rate of the TD may be adjusted by a conventionally known method of a stretched polyester film.

When adjusting the thermal contraction rate of MD of a polyester film, it extends to MD by expanding the space | interval between the clip which grasps the edge part of the film width direction and the adjacent clip in the cooling process after extending | stretching and heat fixing, for example. It can be adjusted by shrinking with MD or by reducing the clip spacing. In the cooling process after stretching and heat fixing, when the film is cut or separated from the clip gripping the end portion in the width direction of the film, the film is stretched or contracted to MD by adjusting the force of pulling the film. Can be adjusted. In the off-line process after film formation, when the temperature is increased for the purpose of imparting a functional layer or the like, since the heat shrinkage rate changes during the temperature-cooling process, it can also be adjusted by adjusting the force of drawing the film and stretching or shrinking it with MD.

When adjusting the thermal contraction rate of the TD of the polyester film, for example, in the cooling process after stretching and heat fixing, the gap between the clip gripping the edge in the width direction of the film and the clip located on the opposite side of the width direction is enlarged. This can be adjusted by stretching to TD or shrinking to TD by shrinking.

Moreover, in either case of MD or TD, it is preferable to adjust the heat shrinkage rate in the temperature range targeted by the present invention.

(How to adjust the tilt of the shrinkage axis of the polyester film)

The slope of the shrinkage principal axis of the polyester film used as the polarizer protective film of the polarizing plate A, as disclosed in PCT / JP2014 / 073451 (WO2015 / 037527), is a cooling process after stretching and heat treatment by a tenter of the polyester film, or , It is possible to adjust in the offline process after film production. Specifically, shrinkage accompanying stretching and heat stress due to cooling occurs in the cooling process, which cannot be removed by heat setting, and is drawn upstream according to the balance of both in the film flow direction. Alternatively, the attraction to the downstream side occurs, and the phenomenon that the main axis of the contraction is inclined occurs. In order to reduce the inclination of the shrinkage main axis, it is necessary to adjust so that the shrinking force in the film flow direction in the cooling process (the sum of the shrinking force with stretching and the shrinking force with cooling) becomes uniform. In order to make it uniform, it is preferable to contract in the film flow direction at a temperature region where the shrinking force is high in the film flow direction, or stretch in the film flow direction at a temperature region where the shrinking force is low in the film flow direction. The method of shrinking or stretching may be a conventionally known method. In addition, when cutting or separating the end of the film, care must be taken in that the heat shrinkage ratio below the temperature range is reduced by shrinking freely in the width direction below the cut and separated temperature range.

(How to adjust the tilt of the orientation main axis of the polyester film)

Adjustment of the inclination of the orientation main axis of the polyester film used as the polarizer protective film for the polarizing plate A is disclosed in Japanese Patent Application No. 2014-11438 (Special 2015-136922) or Japanese Patent Application 2012-552162 (WO2013 / 031511). As described, a conventionally known method may be used as the stretched polyester film. In order to adjust the inclination of the orientation main axis, it is preferable to make the shrinking force in the film flow direction in the stretching and heat fixing section uniform. In the stretching / heat fixing section by the tenter, the distribution of shrinkage force in the film flow direction is present due to the residual stress due to MD stretching and the Poisson stress of TD stretching, and attraction to the upstream or downstream side occurs. Due to this, a tilt occurs on the main axis of the orientation (so-called Boeing phenomenon). In order to make the shrinking force in the film flow direction uniform, a conventionally known method may be used. Specifically, after satisfying the stretching conditions necessary to satisfy the optical properties required for the stretched polyester-based polarizer protective film, during the stretching conditions in consideration of the balance of the stretching ratio of MD and TD and the tenter dimension, stretching and heat fixing This can be achieved by shrinking by reducing the distance between adjacent clips.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples, and may be carried out by appropriately adding changes in a range suitable for the gist of the present invention. And all of them are included in the technical scope of the present invention.

(1) Shrinking force

The shrinkage force of the polarizer and the polyester film was calculated by the following equation. In addition, the film thickness, modulus of elasticity, and heat shrinkage are measured values described below.

Shrinking force (N / m)

= Film thickness (mm) × Elastic modulus (N / mm) × Heat shrinkage ratio (%) ÷ 100 × 1000

(2) Film thickness

The thickness (mm) of the polarizer and the polyester film was measured using an electric micrometer (Minetron 1245D manufactured by FineLoop Co., Ltd.) after standing for 168 hours in an environment of 50RH% at 25 ° C, and the unit was mm. Converted.

(3) Elastic modulus

The modulus of elasticity of the polarizer and the polyester film was evaluated using a dynamic viscoelasticity measuring device (DMS6100) manufactured by Seiko Instruments in accordance with JIS-K7244 (DMS) after standing for 168 hours in an environment of 25 ° C and 50RH%. The temperature dependence of 25 ° C to 120 ° C was measured under the conditions of tensile mode, driving frequency of 1 Hz, distance between chucks of 5 mm, and heating rate of 2 ° C / min, and the average of the storage modulus of 30 ° C to 100 ° C was taken as the elastic modulus. . Moreover, the elastic modulus of the direction parallel to the long side direction of the liquid crystal display device was measured.

(4) Heat shrinkage rate and slope of shrinkage main axis

The heat shrinkage of the polarizer and the polyester film and the inclination of the shrinkage principal axis were drawn at a circle of 80 mm in diameter after standing for 168 hours in an environment of 50 RH% at 25 ° C, and the diameter of the circle was measured using an image dimensional measuring device (image measurer IM6500 manufactured by KEYENCE). Then, it was measured every 1 ° and was taken as the length before treatment. Next, heat treatment is performed for 30 minutes using a gear oven set at 100 ° C, and then cooled for 10 minutes in an environment set at room temperature of 25 ° C, and then evaluated every 1 ° in the same manner as before treatment. Length.

The heat shrinkage rate in the present invention is defined as a value in a direction parallel to the long side direction of the liquid crystal display device, among the heat shrinkage rates calculated by the following calculation formula.

  Heat shrinkage ratio = (length before treatment-length after treatment) / length before treatment x 100

The inclination of the contraction main axis is an angle at which the thermal contraction rate measured every 1 ° becomes the maximum, and is defined as a narrow angle from the long side direction or the short side direction. That is, the inclination of the shrinking main axis is in the range of 0 to 45 °.

(5) tilt of the orientation main axis

The tilt of the orientation main axis of the polyester film is measured using a molecular orientation system (Oji Scientific Instruments Co., Ltd., MOA-6004 type molecular orientation system), and is defined as the narrow angle from the long side direction or the short side direction. did. That is, the inclination of the orientation main axis is in the range of 0 to 45 °.

(6) curl height

In the production of the liquid crystal panel made in each of the examples described below, the "50-inch size IPS type liquid crystal cell using a glass substrate with a thickness of 0.4 mm" is referred to as "125 mm in the short-side direction, 220 mm in the long-side direction, and 0.4 in thickness. A liquid crystal panel for evaluation was produced in the same manner except that it was replaced with "mm glass plate". Next, the liquid crystal panel for evaluation was subjected to heat treatment for 30 minutes using a gear oven set at 100 ° C, and then cooled for 10 minutes in an environment set at room temperature 25 ° C 50RH%, and then the convex side was turned down. It was placed on a horizontal surface, and the height of four corners was measured with a measure, and the maximum value was taken as the curl height. Moreover, the maximum curl height was set to 5 mm or less in a favorable range. Curl is a phenomenon that must be expressed in curvature, but for convenience, evaluation is performed at a height. In addition, the curling phenomenon becomes a bowl shape when the sample size increases with respect to the stiffness of the sample, and a phenomenon may occur in which the curvature is not constant in the film, but the results of this example confirm that the curvature is constant.

(7) Refractive index of polyester film

Using a molecular orientation system (manufactured by Oji Scientific Instruments Co., Ltd., MOA-6004 type molecular orientation system), the direction of the slow axis of the film was determined, and the length of the slow axis was parallel to the long side of the sample for measurement. The rectangle was cut out and used as a sample for measurement. For this sample, the refractive index of the orthogonal biaxial axis (refractive index in the ground axis direction: Ny, the true axis (refractive index in the direction orthogonal to the ground axis direction): Nx), and the refractive index (Nz) in the thickness direction were determined by the Abbe refractometer (Atta It was calculated | required by the yarn manufacture, NAR-4T, measurement wavelength 589nm). NZ coefficients were obtained using these values.

(8) Retardation (Re)

Retardation is a parameter defined by the product of orthogonal biaxial refractive index (ΔNxy = | Nx-Ny |) and film thickness d (nm) (△ Nxy × d) on the film, and shows optical isotropy and anisotropy. It is a measure. The anisotropy (ΔNxy) of the biaxial refractive index was determined by the following method. Using a molecular orientation system (manufactured by Oji Scientific Instruments Co., Ltd., MOA-6004 type molecular orientation system), the direction of the slow axis of the film was determined, and the length of the slow axis was parallel to the long side of the sample for measurement. The rectangle was cut out and used as a sample for measurement. For this sample, an Abbe refractometer (manufactured by Atago Corporation, NAR) was used to measure the refractive index of the two axes orthogonal (the refractive index in the direction of the ground axis: Ny, the refractive index in the direction perpendicular to the slow axis: Nx), and the refractive index (Nz) in the thickness direction. -4T, measurement wavelength 589nm), and the absolute value (| Nx-Ny |) of the refractive index difference between the two axes was defined as the anisotropy (ΔNxy) of the refractive index. The thickness d (nm) of the film was measured using an electric micrometer (manufactured by FineLoop, Millitron 1245D), and the unit was converted to nm. The retardation (Re) was calculated | required from the product ((triangle | delta) Nxyxd) of the anisotropy ((triangle | delta) Nxy) of refractive index and the film thickness d (nm).

(9) Thickness direction retardation (Rth)

The thickness direction retardation is the average of the retardation obtained by multiplying the film thickness d by two birefringences ΔNxz (= | Nx-Nz |) and ΔNyz (= | Ny-Nz |), respectively, as viewed from the cross section in the film thickness direction. Is a parameter indicating Nx, Ny, Nz and film thickness d (nm) were obtained in the same manner as the measurement of retardation, and the average values of (ΔNxz × d) and (△ Nyz × d) were calculated to calculate the thickness direction retardation (Rth). I got it.

(Production Example 1-Polyester A)

When the esterification reaction tube was heated to reach 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were added while stirring, 0.017 parts by mass of antimony trioxide as a catalyst, and 0.064 parts by mass of magnesium acetate tetrahydrate. , 0.16 parts by mass of triethylamine was added. Subsequently, the pressure was elevated to carry out a pressure esterification reaction under conditions of gauge pressure of 0.34 MPa and 240 ° C, and then the esterification reaction tube was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Moreover, it heated up to 260 degreeC over 15 minutes, and 0.012 mass parts of trimethyl phosphate was added. Subsequently, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tube, and polycondensation reaction was carried out under reduced pressure at 280 ° C.

After completion of the polycondensation reaction, filtration is performed with a filter made by Naslon, which has a 95% cut diameter of 5 µm, extruded from the nozzle into a strand, and cooled using cooling water that has been previously subjected to filtration treatment (hole diameter: 1 µm or less). , Solidified, and cut into pellets. The obtained polyethylene terephthalate resin (A) had an intrinsic viscosity of 0.62 dl / g, and substantially no inert particles and internal precipitated particles (hereinafter abbreviated as PET (A)).

(Production Example 2-polyester B)

10 parts by mass of the dried ultraviolet absorbent (2,2 '-(1,4-phenylene) bis (4H-3,1-benzooxazin-4-one), PET (A) containing no particles (unique viscosity 0.62 dl / g) 90 parts by mass were mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder. (Hereinafter abbreviated as PET (B)).

(Production Example 3-Adjustment of adhesive-modified coating liquid)

Transesterification and polycondensation reactions were carried out by a conventional method, and as a dicarboxylic acid component (relative to the entire dicarboxylic acid component), 46 mol% of terephthalic acid, 46 mol% of isophthalic acid, and 5-sulfonatoisophthalate 8 A water-dispersible sulfonic acid metal base-containing copolymer polyester resin having a composition of 50 mol% of ethylene glycol and 50 mol% of neopentyl glycol as a mol% and glycol component (relative to the entire glycol component) was prepared. Subsequently, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, and 0.06 parts by mass of nonionic surfactant were mixed, stirred with heating, and reached 77 ° C., and the water-dispersible sulfonic acid After adding 5 parts by mass of the metal base-containing copolymer polyester resin, stirring is continued until the lump of the resin disappears, and then the resin aqueous dispersion is cooled to room temperature, and the uniform water-dispersible copolymer polyester resin solution having a solid content concentration of 5.0 mass% Got In addition, after dispersing 3 parts by mass of aggregated silica particles (Filixia Co., Ltd., Silisia 310) in 50 parts by mass of water, 0.54 parts of water dispersion of Silisia 310 in 99.46 parts by mass of the water-dispersible copolymer polyester resin solution. 20 parts by mass of water was added while stirring, and an adhesive-modified coating solution was obtained.

(Example 1)

As a raw material for the base film intermediate layer, 90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing ultraviolet absorbers were dried under reduced pressure at 135 ° C. for 6 hours (1 Torr). Then, it was supplied to the extruder 2 (for the middle layer II layer), and the PET (A) was dried by a conventional method, and then supplied to the extruder 1 (for the outer layer I layer and the outer layer III layer), respectively, and dissolved at 285 ° C. Each of these two polymers was filtered with a filter medium (nominal filtration accuracy of 10 µm particles, 95% cut) of a stainless sintered body, and laminated with two types of three-layer confluence blocks to form a sheet from custody. After extruding as, it was wound around a casting drum having a surface temperature of 30 ° C. and cooled and solidified using an electrostatic application cast method to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thicknesses of the layers I, II, and III was 10:80:10.

Subsequently, the adhesive-modified coating solution was applied on both surfaces of this unstretched PET film by a reverse roll method so that the applied amount after drying was 0.08 g / m 2, and then dried at 80 ° C. for 20 seconds.

The unstretched film on which this coating layer was formed was guided to a tenter stretching machine, and the end of the film was gripped with a clip, guided to a hot-air zone at a temperature of 105 ° C, and stretched 4.0 times with TD. Next, heat treatment is performed at a temperature of 180 ° C for 30 seconds, and then the film cooled to 100 ° C is stretched by 1% with MD, and then the clip holding both ends of the film cooled to 60 ° C is opened. With a tension of 350 N / m, a jumbo roll made of a uniaxially oriented PET film with a film thickness of about 80 μm was taken, and the obtained jumbo roll was divided into three equal parts, and three slit rolls (L (left), C (center)) , R (right)). The polarizer protective film 1 was obtained from the slit roll located in R (the central part of the slit roll located in R was used as the polarizer protective film 1).

A polarizer protective film 1 was attached to one side of a polarizer made of PVA, iodine and boric acid (the shrinkage force of the polarizer in the absorption axis direction is 5100 N / m) so that the transmission axis of the polarizer and the MD of the film were parallel. Moreover, a TAC film (Fujifilm Co., Ltd. product, thickness 80 µm) was attached to the opposite side of the polarizer. In this way, a polarizing plate (polarizing plate A) in which the long side direction coincides with the transmission axis direction of the polarizer, and a polarizing plate (polarizing plate B) in which the long side direction coincides with the absorption axis direction of the polarizer. A polarizing plate B on the viewer side and a polarizing plate A on the light source side of the 50-inch IPS liquid crystal cell using a 0.4 mm thick glass substrate, so that the polarizer protective film 1 is distal to the liquid crystal cell (opposite side). A liquid crystal panel was produced by pasting through PSA. A liquid crystal display device was produced by putting this liquid crystal panel in a case.

(Example 2)

In the film formation of the polarizer protective film (1) of Example 1, the polarizer protective film (2) was obtained like the polarizer protective film (1) except that the film cooled to 100 degreeC was stretched by 2.5% in the longitudinal direction. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with a polarizer protective film 2.

(Example 3)

In the film formation of the polarizer protective film 1 of Example 1, the polarizer protective film 3 was obtained like the polarizer protective film 1 except having made the film cooled to 100 degreeC stretch 4% in the longitudinal direction. In Example 1, except that the polarizer having a shrinkage force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 3, the same procedure as in Example 1 was carried out. A liquid crystal display device was made.

(Example 4)

As a raw material for the Ⅰ, Ⅱ and Ⅲ layers, except that a blend of PET (A) 90% by mass and PBT 10% by mass was used, and the film cooled to 100 ° C was stretched 4% in the longitudinal direction. The polarizer protective film 4 was produced in the same manner as the polarizer protective film 1. In Example 1, except that the polarizer having a shrinkage force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 4, the same procedure as in Example 1 was carried out. A liquid crystal display device was made. Moreover, PBT used NV5020 (0.52 dl / g) manufactured by Mitsubishi Engineering Plastics.

(Example 5)

By adjusting the rotational speed of the casting roll, a polarizer protective film 5 was obtained in the same manner as the polarizer protective film 1 except that the film thickness after stretching was 50 μm. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with a polarizer protective film 5.

(Example 6)

A polarizer protective film 6 was obtained in the same manner as the polarizer protective film 5 except that the film cooled to 100 ° C. was stretched by 2.5% in the longitudinal direction. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1, except that the polarizer protective film 1 was replaced with the polarizer protective film 6.

(Example 7)

A polarizer protective film 7 was obtained in the same manner as the polarizer protective film 5 except that the film cooled to 100 ° C. was stretched 4% in the longitudinal direction.

In Example 1, except that the polarizer having a shrinkage force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 7, the same procedure as in Example 1 was carried out. A liquid crystal display device was made.

(Example 8)

By adjusting the rotational speed of the casting roll, the polarizer protective film 8 was obtained in the same manner as the polarizer protective film 1 except that the film thickness after stretching was 160 μm. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with a polarizer protective film 8.

(Example 9)

A polarizer protective film (9) was obtained in the same manner as the polarizer protective film (8), except that the film cooled to 100 ° C was stretched 2.5% in the width direction. Next, the polarizer having a shrinking force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarization plate A and the polarizing plate B were made by bonding so that the transmission axis of the polarizer and the TD of the polarizer protective film were parallel, and , A liquid crystal display device was obtained in the same manner as in Example 1, except that the polarizer protective film 1 was replaced with the polarizer protective film 9.

(Example 10)

A polarizer protective film (10) was obtained in the same manner as the polarizer protective film (1), except that it was stretched 4.0 times by MD and 1.0 times by TD. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with the polarizer protective film 10.

(Example 11)

A polarizer protective film 11 was obtained in the same manner as the polarizer protective film 10, except that the film cooled to 100 ° C was stretched 1.5% by MD. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1, except that the polarizer protective film 1 was replaced with the polarizer protective film 11.

(Example 12)

A polarizer protective film 12 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched by 2.5% with MD.

A liquid crystal display device in the same manner as in Example 1, except that the polarizer having a shrinking force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 12 Got

(Example 13)

As a raw material for the Ⅰ, Ⅱ and Ⅲ layers, a polarizer except that a blend of 90% by mass of PET (A) and 10% by mass of PBT was used, and the film cooled to 100 ° C was stretched by 3% with MD. A polarizer protective film 13 was obtained in the same manner as the protective film 10.

A liquid crystal display device in the same manner as in Example 1, except that the polarizer having a contraction force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 13 Got Moreover, PBT used NV5020 (0.52 dl / g) manufactured by Mitsubishi Engineering Plastics.

(Example 14)

By adjusting the rotational speed of the casting roll, the film thickness after stretching was set to 50 µm, and the film cooled to 100 ° C. was stretched 1.5% in MD, similarly to the polarizer protective film 10, and the polarizer protective film 14 Got The liquid crystal display device was obtained like Example 1 except having replaced the polarizer protective film 1 with the polarizer protective film 14.

(Example 15)

A polarizer protective film 15 was obtained in the same manner as the polarizer protective film 14 except that the film cooled to 100 ° C was stretched by 2% with MD. A liquid crystal display device was obtained in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with the polarizer protective film 15.

(Example 16)

A polarizer protective film 16 was obtained in the same manner as the polarizer protective film 14 except that the film cooled to 100 ° C was stretched 5% in TD. Next, except that the polarizing plate A and the polarizing plate B were made by pasting so that the transmission axis of the polarizer and the TD direction of the polarizing protective film are parallel, and the polarizing protective film 1 was replaced with the polarizing protective film 16, it was carried out. A liquid crystal display device was obtained in the same manner as in Example 1.

(Example 17)

A polarizer protective film 20 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched by 2% with MD. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with a polarizer protective film 20.

(Example 18)

A polarizer protective film 21 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched by 2.5% with MD. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with a polarizer protective film 21.

(Comparative Example 1)

A polarizer protective film 17 was obtained in the same manner as the polarizer protective film 1 except that the clip holding both ends of the film was opened at 95 ° C in the cooling step after stretching and heat fixing. A liquid crystal was used in the same manner as in Example 1, except that the polarizer protective film 1 was replaced with the polarizer protective film 17, and the transmission axis of the polarizer and the TD of the polarizer protective film were parallel to each other to make polarizing plates A and B. A display device was obtained.

(Comparative Example 2)

A polarizer protective film 18 was obtained in the same manner as the polarizer protective film 14 except that the film cooled to 100 ° C. was stretched 0.8% in the width direction. A polarizer having a contraction force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 18, the transmission axis of the polarizer and the TD of the polarizer protective film A liquid crystal display device was obtained in the same manner as in Example 1, except that the polarizing plates A and B were produced by pasting together so that they were parallel.

(Comparative Example 3)

A polarizer protective film 19 was obtained in the same manner as the polarizer protective film 8 except that the film cooled to 100 ° C was stretched 0.3% in the width direction. A polarizer having a contraction force in the absorption axis direction of 5100 N / m was changed to a polarizer having 11200 N / m, and the polarizer protective film 1 was replaced with a polarizer protective film 19, the transmission axis of the polarizer and the TD of the polarizer protective film A liquid crystal display device was obtained in the same manner as in Example 1, except that the polarizing plates A and B were produced by pasting together so that they were parallel.

The liquid crystal panel of the liquid crystal display device of Examples 1-18, and the liquid crystal panel of the liquid crystal display device of Comparative Examples 1-3 are heat-processed for 30 minutes using the gear oven set to 100 degreeC, and after that, it is room temperature. After cooling for 10 minutes in an environment set at 25 ° C. and 50 RH%, the liquid crystal panel was observed. In Examples 1 to 18, curls were not observed, but in Comparative Examples 1 to 3, curls were observed.

Table 1 shows the measurement results of each example.

[Table 1]

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the liquid crystal display device which highly controlled the curl of the laminated body which consists of a polarizing plate / liquid crystal cell / polarizing plate.

Claims (10)

A liquid crystal display device comprising a liquid crystal cell, a polarizing plate A attached to one side of a liquid crystal cell, and a polarizing plate B attached to the other side of a liquid crystal cell,
The polarizing plate A has a structure in which the transmission axis direction of the polarizer is parallel to the long side direction of the liquid crystal display, and a polyester film is laminated on the distal side with the liquid crystal cell of the polarizer,
The polarizing plate B has a structure in which the absorption axis direction of the polarizer is parallel to the long side direction of the liquid crystal display, and a protective film is laminated on at least one side of the polarizer,
A liquid crystal display device characterized in that the contraction force F _{f in} the long direction of the liquid crystal display of the polyester film and the contraction force F _p in the long direction of the liquid crystal display of the polarizer of the polarizing plate B satisfy the following formula (1):
Equation (1) 0.1≤F _f / F _p ≤2
(However, the shrinkage force F _f (N / m) is the thickness (mm) of the polyester film x elastic modulus (N / mm) x heat shrinkage ratio (%) ÷ 100 x 1000, and the shrinkage force F _p (N / m) is The thickness of the polarizer of the polarizing plate B (mm) × elastic modulus (N / mm 2) × heat shrinkage (%) ÷ 100 × 1000). According to claim 1,
A liquid crystal display device characterized in that the elastic modulus in the long side direction of the liquid crystal display device of the polyester film is 1000 to 9000 N / mm 2. The method of claim 1 or 2,
A liquid crystal display device characterized in that the heat shrinkage in the long side direction of the liquid crystal display device of the polyester film is 0.1 to 5%. The method according to any one of claims 1 to 3,
The liquid crystal display device, characterized in that the thickness of the polyester film is 40 ~ 200㎛. The method according to any one of claims 1 to 4,
The inclination of the main axis of alignment of the polyester film is 15 degrees or less. The method according to any one of claims 1 to 5,
The inclination of the shrinkage principal axis of the polyester film is 15 degrees or less, characterized in that the liquid crystal display device. The method according to any one of claims 1 to 6,
The polarizing plate A is a liquid crystal display device having a structure in which a TAC film, a cyclic olefin film, or an acrylic film is laminated on the liquid crystal cell side of the polarizer. The method according to any one of claims 1 to 6,
The polarizing plate A has a structure in which a protective film or an optical compensation film is not laminated on the liquid crystal cell side of the polarizer. The method according to any one of claims 1 to 8,
The polarizing plate B is a liquid crystal display device having a structure in which a TAC film, a cyclic olefin film, or an acrylic film is laminated on the liquid crystal cell side of the polarizer. The method according to any one of claims 1 to 8,
The polarizing plate B has a structure in which a protective film or an optical compensation film is not laminated on the liquid crystal cell side of the polarizer.