CN111443417B - Liquid crystal display device having a light shielding layer - Google Patents

Liquid crystal display device having a light shielding layer Download PDF

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Publication number
CN111443417B
CN111443417B CN202010291214.4A CN202010291214A CN111443417B CN 111443417 B CN111443417 B CN 111443417B CN 202010291214 A CN202010291214 A CN 202010291214A CN 111443417 B CN111443417 B CN 111443417B
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liquid crystal
polarizing plate
display device
crystal display
film
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CN111443417A (en
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藤田敦史
村田浩一
佐佐木靖
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Toyobo Co Ltd
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Toyobo Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/133531—Polarisers characterised by the arrangement of polariser or analyser axes

Abstract

Providing: a liquid crystal display device capable of highly controlling curling of a laminate formed of a polarizing plate/a liquid crystal cell/a polarizing plate in the liquid crystal display device. A liquid crystal display device comprising a liquid crystal cell, a polarizing plate A attached to one surface of the liquid crystal cell, and a polarizing plate B attached to the other surface of the liquid crystal cell, wherein the polarizing plate A has the following structure: the polarizing plate B has the following structure, and a polyester film is laminated on at least one side of the polarizing plate B: the absorption axis direction of the polarizer is parallel to the longitudinal direction of the liquid crystal display device, a protective film is laminated on at least one side of the polarizer, and the shrinkage force F of the polyester film in the longitudinal direction of the liquid crystal display device f Contraction force F in the longitudinal direction of the liquid crystal display device of the polarizing plate of polarizing plate B p Satisfies the requirement of F being more than or equal to 0.1 f /F p ≤2。

Description

Liquid crystal display device having a light shielding layer
The present application is a divisional application of application number 201780021586.1 and entitled "liquid crystal display device" having application date 2017, 03, 24.
Technical Field
The present invention relates to a liquid crystal display device used for a display of a personal computer, a television, or the like.
Background
In order to reduce the weight of liquid crystal display devices, glass substrates have been studied to reduce the thickness of glass substrates to 0.7mm to 0.5mm, and further to 0.3mm, and it is considered that further reduction in thickness will be performed in the future. Since the glass substrate in the liquid crystal display device has an effect of suppressing curling caused by thermal behavior of the polarizing plate, the curling suppressing effect is greatly reduced as the thickness of the glass substrate is reduced, and the problem of warpage of the laminate formed of polarizing plate/liquid crystal cell/polarizing plate in the liquid crystal display device is remarkable.
Conventionally, there have been proposed a lot of studies for suppressing curling of a laminate formed of a polarizing plate/a liquid crystal cell/a polarizing plate, and for example, patent document 1 proposes: among the polarizing plates disposed on the upper and lower visual sides and the backlight side of the liquid crystal cell of the liquid crystal display device, the elastic modulus in the longitudinal direction of each polarizing plate is controlled, and the difference in the elastic modulus of the upper and lower polarizing plates is set in consideration of the difference in the placement environments of the upper and lower polarizing plates, thereby improving the warpage of the liquid crystal display device. In addition, patent document 2 focuses on the difference in contraction force between the absorption axis direction and the transmission axis direction of the polarizing plate, and reduces the contraction force of the polarizing plate in the contraction main direction at high temperature or high temperature and high humidity, thereby improving the warpage of the display device.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2006-267503
Patent document 2: WO2014-204165
Disclosure of Invention
Problems to be solved by the invention
However, in patent documents 1 and 2, improvement studies have been made on controlling strain with temperature change and strain with moisture absorption/desorption, and in the case of using a film having a low glass transition temperature such as a polyethylene terephthalate film, consideration should be given to the effect of residual strain (heat shrinkage) originally possessed by the film.
That is, the present invention aims to provide: a liquid crystal display device capable of highly controlling curling of a laminate formed of a polarizing plate/a liquid crystal cell/a polarizing plate in the liquid crystal display device.
Solution for solving the problem
In general, a liquid crystal display device has a polarizing plate laminated on one surface of a liquid crystal cell so that the transmission axis direction of a polarizing plate is parallel to the longitudinal direction of the liquid crystal display device, and a polarizing plate laminated on the other surface so that the absorption axis direction of the polarizing plate is parallel to the longitudinal direction of the liquid crystal display device. As a result of intensive studies using various commercially available liquid crystal display devices, the present inventors have found that: the problem is essentially that the polarizing plate having a large shrinkage force and a long polarizing plate absorbing axis direction is shrunk to easily cause a curl in a form factor (curl is generally easily generated in the long side direction), and the influence of an asymmetric configuration of the upper and lower polarizing plates in the liquid crystal panel causes the liquid crystal panel to become convex on the polarizing plate side having a long polarizing plate transmitting axis of the polarizing plates disposed in the upper and lower polarizing plates of the cross prism.
Further, as a result of intensive studies, it has been revealed that the shrinkage force in the longitudinal direction of the polarizing plate in which the transmission axis of the polarizing plate is a long side can be controlled according to the residual strain of the protective film, and the curl of the liquid crystal display device can be controlled by the shrinkage force.
Here, a method for measuring the shrinkage force of the polarizing plate will be described. In general, the shrinkage force of the film is as follows: using TMA or the like, the initial length was set at a low temperature state at the start of the test and under a very small load, and the force in the contraction direction during the temperature increase was measured while maintaining the initial length. However, in the heating process, shrinkage (hereinafter, abbreviated as thermal shrinkage) occurs due to recovery of residual strain caused by conformational change of the polymer, and thermal expansion (hereinafter, abbreviated as thermal expansion) occurs due to an increase in free volume and occupied volume of the polymer by heating, and therefore, in a temperature region around the glass transition temperature (for example, about-tg+50℃) of the polyester film, there is often a relationship of thermal shrinkage < thermal expansion, and therefore, expansion occurs as a whole of the film, and the shrinkage force cannot be observed.
The results of the study showed that even in the case where no shrinkage force was generated during TMA warming, shrinkage force was generated during TMA cooling. This is because the strain caused by thermal expansion changes reversibly, and therefore returns to the original state after the temperature is raised and cooled, but the thermal stress is generated during the cooling because the cooling is performed in a small-sized state in accordance with the degree of thermal shrinkage that has been contracted during the temperature raising. That is, the strain of the thermal stress can be converted into the thermal shrinkage of the film, and the shrinkage force after cooling is expressed by the following formula. The heat shrinkage in the present invention includes a change in the moisture content in the heat treatment.
Force of contraction (N/m)
=film thickness (mm) ×elastic modulus (N/mm 2 ) X heat shrinkage (%) 100 x 1000
That is, representative invention is as follows.
Item 1.
A liquid crystal display device comprising a liquid crystal cell, a polarizing plate A attached to one surface of the liquid crystal cell, and a polarizing plate B attached to the other surface of the liquid crystal cell, characterized in that,
the polarizing plate a has the following structure: the direction of the light transmission axis of the polarizing plate is parallel to the long side direction of the liquid crystal display device, a polyester film is laminated on at least one side of the polarizing plate,
the polarizing plate B has the following structure: the absorption axis direction of the polarizer is parallel to the longitudinal direction of the liquid crystal display device, a protective film is laminated on at least one side of the polarizer,
shrinkage force F in the longitudinal direction of the liquid crystal display device of the polyester film f Contraction force F in the longitudinal direction of the liquid crystal display device of the polarizing plate of polarizing plate B p The following formula (1) is satisfied.
F is more than or equal to 0.1 f /F p ≤2
(wherein, the shrinkage force F f (N/m) is the thickness (mm) of the polyester film. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F p (N/m) the thickness (mm) of the polarizing plate of polarizing plate B. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000. )
Item 2.
The liquid crystal display device according to item 1, wherein the polyester film has elasticity in a longitudinal direction of the liquid crystal display deviceModulus of 1000-9000N/mm 2 。
Item 3.
The liquid crystal display device according to item 1 or 2, wherein the polyester film has a heat shrinkage of 0.1 to 5% in the longitudinal direction of the liquid crystal display device.
Item 4.
The liquid crystal display device according to any one of claims 1 to 3, wherein the thickness of the polyester film is 40 to 200. Mu.m.
Item 5.
The liquid crystal display device according to any one of claims 1 to 4, wherein an inclination angle of the orientation major axis 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.
Item 6.
The liquid crystal display device according to any one of claims 1 to 5, wherein the tilt angle of the main shrinkage axis of the polyester film with respect to the longitudinal direction or the short direction of the liquid crystal display device is 15 degrees or less.
Item 7.
A liquid crystal panel having a liquid crystal cell, a polarizing plate A attached to one surface of the liquid crystal cell, and a polarizing plate B attached to the other surface of the liquid crystal cell,
the polarizing plate a has the following structure: the direction of the light transmission axis of the polaroid is parallel to the long side direction of the polaroid A, a polyester film is laminated on at least one side of the polaroid,
The polarizing plate B has the following structure: the absorption axis direction of the polarizer is parallel to the long side direction of the polarizer B, a protective film is laminated on at least one side of the polarizer,
shrinkage force F of the polyester film in the longitudinal direction of the polarizing plate A f Shrinkage force F in the longitudinal direction of the polarizing plate B p The following formula (1) is satisfied.
F is more than or equal to 0.1 f /F p ≤2
(wherein, the shrinkage force F f (N/m) is the thickness (mm) of the polyester film. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100×1000, shrinkage force F p (N/m) the thickness (mm) of the polarizing plate of polarizing plate B. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000. )
Item 8.
The liquid crystal panel according to item 7, wherein the polyester film has an elastic modulus in the longitudinal direction of the polarizing plate A of 1000 to 9000N/mm 2 。
Item 9.
The liquid crystal panel according to item 7 or 8, wherein the heat shrinkage in the longitudinal 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 claims 7 to 9, wherein the thickness of the polyester film is 40 to 200 μm.
Item 11.
The liquid crystal panel according to any one of claims 7 to 10, wherein an inclination angle of the major axis of orientation of the polyester film with respect to a long side direction or a short side direction of the liquid crystal panel is 15 degrees or less.
Item 12.
The liquid crystal panel according to any one of claims 1 to 5, wherein the tilt angle of the principal axis of shrinkage of the polyester film with respect to the longitudinal direction or the short direction of the liquid crystal panel is 15 degrees or less.
ADVANTAGEOUS EFFECTS OF INVENTION
The following liquid crystal display device may be provided: the curl of a laminate (liquid crystal panel) formed of a polarizing plate/liquid crystal cell/polarizing plate, which is generated under a high temperature or high temperature and high humidity environment, is reduced.
Detailed Description
The screen of the liquid crystal display device is generally rectangular and has long sides and short sides. In the present specification, the "longitudinal direction of the liquid crystal display device" means a direction parallel to the longitudinal direction of the liquid crystal display device, and is the same as the "longitudinal direction of the polarizing plate a", "longitudinal direction of the polarizing plate B", "longitudinal direction of the polarizing plate B", "longitudinal direction of the polyester film of the polarizing plate a". Thus, in the present specification, the "longitudinal direction of the liquid crystal display device" may be interchangeably referred to as "longitudinal direction of the polarizing plate a", "longitudinal direction of the polarizing plate B", "longitudinal direction of the polarizing plate provided in the polarizing plate B", and "longitudinal direction of the polyester film provided in the polarizing plate a". The term "short side direction of the liquid crystal display device" refers to a direction parallel to the short side of the liquid crystal display device and a direction perpendicular to the long side direction.
The liquid crystal display device of the present invention includes at least: a liquid crystal unit, a polarizing plate A adhered to one surface of the liquid crystal unit, and a polarizing plate B adhered to the other surface of the liquid crystal unit. The liquid crystal cell and the polarizing plate may be generally attached by an adhesive layer. The liquid crystal display device may include constituent members used in a general liquid crystal display device such as a backlight, in addition to the liquid crystal cell, the polarizing plate a, and the polarizing plate B. The liquid crystal cell has a structure in which liquid crystal is sandwiched between 2 glass substrates. In one embodiment, the thickness of the glass substrate constituting the liquid crystal cell is preferably 0.7mm or less, 0.6mm or less, 0.5mm or less, 0.4mm or less, 0.3mm or less, or 0.25mm or less.
The polarizing plate a has the following structure: the polarizing plate has a light-transmitting axis direction parallel to the longitudinal direction of the liquid crystal display device (that is, the same meaning as the light-transmitting axis direction of the polarizing plate is parallel to the longitudinal direction of the polarizing plate a), and a polyester film (used as a polarizing plate protective film) is laminated on at least one side of the polarizing plate. A protective film or an optical compensation film having a low retardation such as a TAC film, a cyclic olefin film or an acrylic film may be laminated on the surface opposite to the surface of the polarizing plate on which the polyester film is laminated. Here, the protective film having a low retardation may be, for example, a protective film having a retardation of 500nm or less, 400nm or less, 300nm or less, 200nm or less, 100nm or less, or 50nm or less. In the polarizing plate a, a polyester film is laminated only on one surface of the polarizing plate, and a protective film and an optical compensation film are not laminated on the other surface of the polarizing plate. The polyester film may be disposed on either (or both) of the liquid crystal cell side of the polarizing plate and the liquid crystal cell on the distal end side (outer side), but is preferably disposed on the distal end side (outer side) of the liquid crystal cell of the polarizing plate.
The polarizing plate is preferably perfectly parallel to the longitudinal direction of the liquid crystal display device, but is a concept that allows a small amount of deviation. That is, the angle between the light transmission axis direction of the polarizing plate and the longitudinal 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, preferably 1 degree or less, and most preferably 0 degree.
The polarizing plate B has the following structure: the polarizing plate has an absorption axis parallel to the longitudinal direction of the liquid crystal display device (that is, the same meaning as the absorption axis of the polarizing plate and the longitudinal direction of the polarizing plate B), and a protective film is laminated on at least one surface of the polarizing plate. A protective film or an optical compensation film having a low retardation such as a TAC film, a cyclic olefin film or an acrylic film may be laminated on the protective film. Here, the protective film having a low retardation may be, for example, a protective film having a retardation of 500nm or less, 400nm or less, 300nm or less, 200nm or less, 100nm or less, or 50nm or less. Further, a polyester film as a protective film may be laminated on the polarizing plate. In the case of using a polyester film, it is preferable that the polyester film is laminated on the liquid crystal cell of the polarizing plate at the distal end side.
The polarizing plate B may have the following structure: a polyester film is laminated on one surface of the polarizing plate, and the protective film and the optical compensation film are laminated on the other surface. In addition, in the polarizing plate B, a polyester film is laminated only on one surface of the polarizing plate, and a protective film and an optical compensation film are not laminated on the other surface of the polarizing plate.
The absorption axis direction of the polarizing plate is most desirably perfectly parallel to the longitudinal direction of the liquid crystal display device, but allows a small deviation. That is, the angle between the absorption axis direction of the polarizing plate and the longitudinal 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, preferably 1 degree or less, and most preferably 0 degree.
The polarizing plate a may be used for both a visible-side polarizing plate and a backlight-side polarizing plate depending on the liquid crystal cell, and is preferably disposed as a backlight-side polarizing plate. The polarizing plate B may be used for both a visible-side polarizing plate and a backlight-side polarizing plate depending on the liquid crystal cell, and is generally preferably disposed as a visible-side polarizing plate. That is, a liquid crystal display device having a backlight source, a polarizing plate a, a liquid crystal cell, and a polarizing plate B in this order is preferable. The liquid crystal display device may include other members therebetween.
In the liquid crystal display device of the present invention, F is desirably 0.1.ltoreq.F f /F p ≤2。F f /F p The lower limit of (2) is preferably 0.2 or 0.3.F (F) f /F p The upper limit of (2) 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.ltoreq.F is preferred 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 /F p F is less than or equal to 0.8 or 0.3 f /F p ≤0.7。
Here, F f The shrinkage force in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate A was measured by the thickness (mm) of the polyester film X the elastic modulus (N/mm 2 ) X heat shrinkage (%) 100 x 1000. F (F) p The shrinkage force in the longitudinal direction of the liquid crystal display device of the polarizing plate B was measured by the thickness (mm) of the polarizing plate B. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000. Force of contraction F f And F p In the formula (1), the elastic modulus and the heat shrinkage are values in the longitudinal direction of the liquid crystal display device. The shrinkage force of the polarizing plate B is mainly expressed by the polarizing plate, and varies according to the thickness of the polarizing plate and the film forming conditions. Accordingly, it is desirable to adjust the shrinkage force of the polyester film used in the polarizing plate a according to the shrinkage force.
The polyester film used in the polarizing plate A preferably has an elastic modulus in the longitudinal direction of 1000 to 9000N/mm 2 . The shrinkage force of the polyester film can be controlled by the elastic modulus, but in order to increase the elastic modulus in the longitudinal direction of the liquid crystal display device, it is necessary to highly orient the polyester film in the longitudinal direction of the liquid crystal display device and to increase the crystallinity. Therefore, the elastic modulus in the longitudinal direction exceeds 9000N/mm 2 In the case of (2), the problem of easy breakage is remarkable, and therefore, the upper limit is preferably 9000N/mm 2 More preferably 8000N/mm 2 More preferably 7000N/mm 2 . On the other hand, when the orientation is low and the crystallinity is low, the film is deformed by the irregularities of the roll due to uneven thickness when wound around the roll, resulting in poor flatness. Thus, the lower limit of the elastic modulus is preferably 1000N/mm 2 More preferably 1500N/mm 2 Further preferably 1800N/mm 2 . The elastic modulus can be measured by the method used in examples described later.
The polyester film used in the polarizing plate a preferably has a heat shrinkage of 0.1 to 5% in the longitudinal direction of the liquid crystal display device when heat-treated at 100 ℃ for 30 minutes. The lower limit of the heat shrinkage is preferably 0.3% or more, preferably 0.4% or more, preferably 0.5% or more, preferably 0.7% or more. The upper limit of the heat shrinkage is preferably 4% or less, more preferably 3% or less, and still more preferably 2% or less. When the heat shrinkage is less than 0.1%, that is, in the range of 0.01 to 0.099%, it is difficult to control the heat shrinkage without fluctuation. When the heat shrinkage is more than 5%, as will be described later, the crystallinity and the glass transition temperature must be further reduced, and thus, defects such as poor flatness become evident. The heat shrinkage can be measured by the method used in examples described later.
The polyester film used in the polarizing plate A preferably has a thickness of 40 to 200. Mu.m. If the thickness of the polyester film is less than 40 μm, the film is liable to be broken, and the film is liable to have poor flatness due to insufficient rigidity. In the case of the thin film, the elastic modulus and the heat shrinkage ratio in the longitudinal direction must be increased in accordance with the thickness, but there is an upper limit in each parameter as described above, and therefore, the lower limit is substantially 40 μm. In addition, when the film thickness exceeds 200 μm, the variation in the elastic modulus and the heat shrinkage in the longitudinal direction becomes large in accordance with the variation, which makes control difficult and increases the cost. The thickness of the polyester film can be measured by the method used in examples described later.
The polyester film used in the polarizing plate a preferably has an inclination angle of 15 degrees or less between the major axis of orientation of the polyester film and the long side direction or the short side direction of the liquid crystal display device. The stretched polyester film generally has anisotropy of elastic modulus in the film plane, but the anisotropy of elastic modulus of the stretched polyester film generally coincides with the optical anisotropy. Therefore, by setting the tilt angle to the long side direction or the short side direction of the liquid crystal display device to 15 degrees or less with respect to the alignment principal axis determined from the optical anisotropy, the direction with a high elastic modulus approaches the long side direction or the short side direction of the liquid crystal display device, and therefore, it is effective for suppressing curling of the laminate formed of the polarizing plate/liquid crystal cell/polarizing plate as the object of the present invention. When the tilt angle between the alignment main axis and the long side direction or the short side direction of the liquid crystal display device exceeds 15 degrees, the tendency of curling in the tilt direction becomes remarkable. The inclination angle 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 used in examples described later.
The polyester film used in the polarizing plate a preferably has an inclination angle of 15 degrees or less with respect to the longitudinal direction or the short direction of the liquid crystal display device with respect to the principal axis of shrinkage of the polyester film. The stretched polyester film generally has anisotropy of heat shrinkage in the film surface and has an inclination angle on the principal axis of shrinkage. When the inclination angle of the shrink main shaft to the long side direction or the short side direction is larger than 15 degrees, the tendency of curling in the oblique direction becomes remarkable, which is not preferable. Therefore, the tilt angle of the principal axis of shrinkage of the polyester film used in the polarizing plate a with respect to 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. The shrinkage principal axis can be measured according to the measurement method adopted in the examples described later.
From the viewpoint of suppressing the rainbow unevenness observed on the screen of the liquid crystal display device, the polyester film used in the polarizing plate a is preferably in a specific range of in-plane retardation. The lower limit of the in-plane retardation is preferably 3000nm or more, 5000nm or more, 6000nm or more, 7000nm or more, or 8000nm or more. The upper limit of the in-plane retardation is preferably 30000nm or less, more preferably 18000nm or less, and still more preferably 15000nm or less. In the case where a polyester film is also used as the protective film for the polarizing plate B, it is preferable that the polyester film also has the in-plane retardation in the above range.
The retardation of the polyester film may be obtained by measuring the refractive index and thickness in the biaxial directions, or may be obtained by using a commercially available automatic birefringence measuring apparatus such as KOBRA-21ADH (ojiscientific instruments co., ltd.). The refractive index can be obtained by an Abbe refractometer (measurement wavelength 589 nm).
The polyester film used in the polarizing plate a preferably has a ratio (Re/Rth) of the in-plane retardation (Re) to the retardation in the thickness direction (Rth) of 0.2 or more, preferably 0.3 or more, preferably 0.4 or more, preferably 0.5 or more, more preferably 0.5 or more, and still more preferably 0.6 or more. The greater the ratio (Re/Rth) of the in-plane retardation amount to the thickness direction retardation amount, the more isotropic the effect of birefringence is, and the occurrence of iridescent stains due to the observation angle tends to be less likely to occur. In the completely uniaxial (1-axis-symmetric) film, the ratio (Re/Rth) of the retardation amount to the retardation amount in the thickness direction becomes 2.0, and therefore the upper limit of the ratio (Re/Rth) of the retardation amount to the retardation amount in the thickness direction is preferably 2.0. The upper limit of Re/Rth is preferably 1.2 or less. The thickness-direction retardation is an average of the retardation obtained by multiplying 2 birefringence Δ Nxz and Δ Nyz when the film is viewed from a thickness-direction cross section by the film thickness d. In the case where a polyester film is also used as the protective film in the polarizing plate B, the ratio (Re/Rth) of the in-plane retardation (Re) to the retardation (Rth) in the thickness direction of the polyester film is preferably in the above range.
The NZ coefficient of the polyester film used in the polarizing plate a is preferably 2.5 or less, more preferably 2.0 or less, further preferably 1.8 or less, and further preferably 1.6 or less, from the viewpoint of further suppressing iridescent stains. In addition, in the completely uniaxial (uniaxial) film, the NZ coefficient is 1.0, and therefore, the lower limit of the NZ coefficient is 1.0. However, as the film approaches a perfect uniaxial (uniaxial symmetry), the mechanical strength in the direction perpendicular to the orientation direction tends to be significantly reduced, and therefore, attention is required. In the case where a polyester film is used as the protective film for the polarizing plate B, the NZ coefficient of the polyester film is preferably within the above range.
The NZ coefficient is represented by |ny-nz|/|ny-nx|, where Ny represents the refractive index of the polyester film in the slow axis direction, nx represents the refractive index in the direction orthogonal to the slow axis (the refractive index in the fast axis direction), and NZ represents the refractive index in the thickness direction. The orientation axis of the film was determined by a molecular orientation meter (Ojiscientific instruments Co., ltd., MOA-6004 type molecular orientation meter), and the refractive index (Ny, nx, where Ny > Nx) of the biaxial orientation axis direction and the direction perpendicular thereto and the refractive index (Nz) of the thickness direction were determined by an Abbe refractometer (ATAGO CO., LTD, manufactured by NAR-4T, measurement wavelength 589 nm). The value thus obtained may be substituted into |ny-nz|/|ny-nx| to obtain the Nz coefficient.
In addition, from the viewpoint of further suppressing iridescent stains, the value of ny—nx of the polyester film used in the polarizing plate a is preferably 0.05 or more, more preferably 0.07 or more, still more preferably 0.08 or more, still more preferably 0.09 or more, and most preferably 0.1 or more. The upper limit is not particularly limited, but in the case of a polyethylene terephthalate film, the upper limit is preferably about 1.5. In the case where a polyester film is used as the protective film for the polarizing plate B, it is also preferable that the value of ny—nx of the polyester film is in the above range.
The polyester film used in the polarizing plate a may be obtained from any polyester resin. The type of the polyester resin is not particularly limited, and any polyester resin obtained by condensing a dicarboxylic acid with a diol may be used. In the case where a polyester film is used as the protective film for the polarizing plate B, the same applies to the polyester film.
Examples of the dicarboxylic acid component that can be used for producing the polyester resin include terephthalic acid, isophthalic acid, phthalic acid, 2, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylsulfone carboxylic acid, anthracene dicarboxylic acid, 1, 3-cyclopentanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3-diethylsuccinic acid, glutaric acid, 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.
Examples of the diol component that can be used for producing the polyester resin include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1, 2-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, decamethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.
The dicarboxylic acid component and the diol component constituting the polyester resin may each be 1 or 2 or more. Examples of suitable polyester resins constituting the polyester film include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and more preferably polyethylene terephthalate and polyethylene naphthalate, which may further contain other copolymerization components. These resins are excellent in transparency and also excellent in thermal characteristics and mechanical characteristics. In particular, polyethylene terephthalate is a suitable material because it can achieve a high elastic modulus and can control the heat shrinkage more easily.
When it is necessary to highly increase the heat shrinkage of the polyester film, it is desirable to add a copolymerization component to make the crystallinity moderately low. In addition, since the ratio of elastic strain to permanent strain is high for deformations in the vicinity of the glass transition temperature or less, it is generally difficult to highly increase the heat shrinkage. Therefore, the incorporation of a component having a low glass transition temperature is also a preferred embodiment, if necessary. Specifically, propylene glycol, 1, 3-propane diol, and the like are mentioned.
(imparting functional layer)
The polarizing plate a used in the liquid crystal display device of the present invention is desirably integrated with the glass plate of the liquid crystal cell in a state where the thermal shrinkage rate of the polyester film remains, and therefore, when the functional layers such as the easy-to-adhere layer, the hard coat layer, the antiglare layer, the antireflection layer, the low reflection layer, the low antireflection layer, the antireflection antiglare layer, the antistatic layer, and the like are provided, it is desirable to perform the method by setting the drying temperature to be low or by using a method in which the thermal history such as UV irradiation or electron beam irradiation is small. In order to impart these functional layers in the polyester film forming step, the polarizing plate a and the glass plate of the liquid crystal cell can be integrated without impairing the increased heat shrinkage, and thus a more preferable embodiment is obtained.
(method for producing oriented polyester film)
The polyester film used in the present invention can be produced according to a general production method of a polyester film. For example, the following methods can be mentioned: a polyester resin is melted and extruded into a sheet-like unoriented polyester, which is stretched in the machine direction by a speed difference of rolls at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter, and heat-treated. Either uniaxially or biaxially stretched films. MD is an abbreviation for machine direction, and may be referred to as a film conveyance direction, a longitudinal direction, and a longitudinal direction in the present specification. TD is abbreviated as transverseddirection, and is sometimes referred to as a width direction or a transverse direction in this specification.
The polyester film used as the protective film for the polarizing plate in the polarizing plate a preferably adjusts the shrinkage force F f Make it 0.1F p ≤F f ≤2F p 。
(method for adjusting elastic modulus of polyester film)
When the elastic modulus of the polyester film used as the polarizer protective film in the polarizing plate a is equal to the MD in the case of film formation of the polyester film, the elastic modulus of the MD may be adjusted by a conventionally known method of stretching the polyester film, and when the elastic modulus of the polyester film is equal to the TD in the case of film formation of the polyester film, the elastic modulus of the TD may be adjusted by a conventionally known method of stretching the polyester film.
Specifically, when the direction is the stretching direction, the stretching ratio may be set high, and when the direction is the direction perpendicular to the stretching direction, the stretching ratio may be set low.
(method for adjusting Heat shrinkage of polyester film)
When the heat shrinkage ratio of the polyester film used as the protective film for the polarizing plate a and the light transmission axis direction of the polarizing plate (i.e., the longitudinal direction of the liquid crystal display device) are identical to the MD at the time of film formation of the polyester film, the heat shrinkage ratio of the MD may be adjusted by a conventionally known method of stretching the polyester film, and when the heat shrinkage ratio of the polyester film is identical to the TD at the time of film formation of the polyester film, the heat shrinkage ratio of the TD may be adjusted by a conventionally known method of stretching the polyester film.
In the case of adjusting the heat shrinkage ratio of the MD of the polyester film, for example, in the cooling process after stretching and heat fixing, a method of stretching in the MD by expanding the interval between the clamp for clamping the end portion in the film width direction and the adjacent clamp is performed; the jig interval is narrowed so as to be contracted in the MD, whereby adjustment is possible. In addition, in the case where the film is cut or separated from the jig for holding the end portion in the width direction of the film during cooling after stretching and heat fixing, the force for collecting the film is adjusted to stretch or shrink the film in the MD, and thus the film can be adjusted. In the off-line process after film formation, when the temperature is raised to provide a functional layer or the like, the heat shrinkage rate changes during the temperature raising and cooling process, and therefore, the film-taking force is adjusted to be stretched or shrunk in the MD, and the adjustment may be performed.
In the case of adjusting the heat shrinkage ratio of the TD of the polyester film, for example, in the cooling process after stretching and heat fixing, a method of stretching along the TD by expanding the interval between the clamp for clamping the end in the width direction of the film and the clamp located on the opposite side in the width direction; the adjustment can be performed by performing the shrinkage so as to shrink along TD.
In either MD or TD, it is desirable to adjust the heat shrinkage in the target temperature range of the present invention.
(method for adjusting the tilt angle of the shrink Main shaft of polyester film)
The inclination angle of the principal axis of shrinkage of the polyester film used as the polarizer protective film of the polarizing plate a can be adjusted in a cooling process after stretching and heat treatment by a tenter or in an off-line process after film formation of the polyester film as disclosed in PCT/JP2014/073451 (WO 2015/037527). Specifically, in the cooling step, shrinkage due to stretching removed by the incomplete heat fixation and thermal stress due to cooling occur, and the phenomenon of shrinkage main shaft tilting occurs due to the upstream side introduction or downstream side introduction caused by the balance of both in the film conveying direction. In order to reduce the inclination angle of the shrink spindle, it is necessary to adjust the shrink force in the film conveying direction (the sum of the shrink force due to stretching and the shrink force due to cooling) in the cooling step so as to be uniform. In order to make it uniform, it is desirable to shrink it in the film conveying direction in a temperature region where the shrinkage force is high; or, stretching is performed in the film conveying direction in a temperature region where the shrinkage force is low in the film conveying direction. The method for performing the shrinkage or stretching may be a conventionally known method. When cutting or separating the film end, the film is free to shrink in the width direction in a temperature region or less where cutting and separation are performed, and the heat shrinkage rate in the temperature region or less is small, and therefore care is required.
(method for adjusting the tilt angle of the orientation Main shaft of a polyester film)
The tilt angle of the orientation principal axis of the polyester film used as the polarizing plate protective film in the polarizing plate a may be adjusted by a conventionally known method for stretching the polyester film as disclosed in japanese patent application publication 2014-11438 (japanese patent application laid-open publication 2015-136922) or japanese patent application publication 2012-552162 (WO 2013/031511). In order to adjust the inclination angle of the orientation main axis, it is preferable to make uniform the shrinkage force in the film conveying direction in the stretching and heat setting section. In the stretching/heat setting section by the tenter, since there is a distribution of shrinkage force in the film conveying direction due to residual stress of MD stretching and poisson stress of TD stretching, introduction to the upstream side or downstream side occurs, and therefore, an inclination angle (so-called bow phenomenon) occurs on the orientation principal axis. In order to make the shrinkage force in the film conveying direction uniform, a conventionally known method may be used. Specifically, the stretching conditions required for satisfying the optical characteristics required for stretching the polyester-based polarizer protective film are satisfied by considering the balance of stretching ratios in MD and TD, the temperature-increasing conditions of the tenter dimension, and shrinkage due to the reduction of the distance between adjacent jigs during stretching and heat fixing.
Examples
The present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples described below, and may be implemented with appropriate modifications within the scope of the gist of the present invention, and these are included in the scope of the present invention.
(1) Force of contraction
The shrinkage force of the polarizer and the polyester film was calculated by the following formula. The film thickness, elastic modulus, and heat shrinkage were measured values described below.
Force of contraction (N/m)
=film thickness (mm) ×elastic modulus (N/mm 2 ) X heat shrinkage (%) 100 x 1000
(2) Film thickness
The thickness (mm) of the polarizer and the polyester film was measured as follows: after standing at 25℃for 168 hours in 50RH%, measurement was performed by an electrometer (Fine Liu off Co., ltd., miritor 1245D) to convert the unit into mm.
(3) Modulus of elasticity
The elastic modulus of the polarizer and polyester film is as follows: after standing at 25℃for 168 hours in 50RH%, evaluation was performed by a dynamic viscoelasticity measuring device (DMS 6100) manufactured by Seiko Instruments Inc. according to JIS-K7244 (DMS). Under the conditions of a stretching mode, a driving frequency of 1Hz, a distance between chucks of 5mm and a heating rate of 2 ℃/min, the temperature dependence at 25-120 ℃ is measured, and the average storage modulus at 30-100 ℃ is taken as the elastic modulus. The elastic modulus was measured in a direction parallel to the longitudinal direction of the liquid crystal display device.
(4) Heat shrinkage and inclination angle of main shrinkage shaft
The heat shrinkage rates of the polarizer and the polyester film and the inclination angles of the shrinkage principal axes are as follows: after standing at 25℃for 168 hours in a 50RH% environment, a circle having a diameter of 80mm was drawn, and the diameter of the circle was measured by an Image size measuring instrument (Image measuring information 6500 manufactured by Keyence Corporation) at 1℃intervals, and the measured diameter was used as the length before treatment. Then, after heat treatment was performed for 30 minutes in a gill aging oven set at 100 ℃, the heat treatment was performed for 10 minutes in an environment set at room temperature of 25 ℃, and then the heat treatment was evaluated at 1 ° intervals by the same method as before the treatment, to obtain a length after the treatment.
The heat shrinkage ratio in the present invention is a value defined by a value in a direction parallel to a longitudinal direction of the liquid crystal display device among the heat shrinkage ratios calculated by the following calculation formulas.
Heat shrinkage = (length before treatment-length after treatment)/length before treatment×100
The inclination angle of the shrinkage main axis is defined as the inclination angle from the longitudinal direction or the short direction, and the inclination angle is the angle at which the heat shrinkage rate measured at 1 ° becomes maximum. That is, the inclination angle of the shrink main shaft is in the range of 0 to 45 °.
(5) Inclination angle of orientation principal axis
The tilt angle of the orientation main axis of the polyester film was measured by a molecular orientation meter (ojiscientific instruments co., ltd. Model MOA-6004), and the orientation main axis was defined as the tilt angle from the long side direction or the short side direction. That is, the tilt angle of the alignment main axis is in the range of 0 to 45 °.
(6) Height of curl
In the production of the liquid crystal panel produced in each example described later, an evaluation liquid crystal panel was produced in the same manner except that "the 50-inch-sized IPS type liquid crystal cell using a glass substrate having a thickness of 0.4 mm" was replaced with "a glass plate having a length of 125mm in the short side direction, a length of 220mm in the long side direction, and a thickness of 0.4 mm". Next, the liquid crystal panel for evaluation was subjected to heat treatment with a gill aging oven set at 100 ℃ for 30 minutes, and then cooled in an environment set at room temperature of 25 ℃ and 50% rh for 10 minutes, and then the convex side was placed downward on a horizontal plane, and the height at 4 was measured with measurement, and the maximum value was taken as the curl height. In addition, the maximum curl height is set to 5mm or less as a good range. Curl is a phenomenon that should be expressed in terms of curvature, but for simplicity, it is highly evaluated. Further, the curl phenomenon became bowl-shaped when the sample size became large with respect to the rigidity of the sample, and the phenomenon of non-constant curvature was sometimes generated in the film, but the results of the present example confirm that the curvature was constant in all.
(7) Refractive index of polyester film
The slow axis direction of the film was determined by using a molecular orientation meter (molecular orientation meter model MOA-6004, manufactured by ojiscientific instruments co., ltd.), and a rectangle of 4cm×2cm was cut so that the slow axis direction was parallel to the long side of the sample for measurement, to obtain the sample for measurement. For this sample, refractive indices (refractive index in the slow axis direction: ny, fast axis (refractive index in the direction orthogonal to the slow axis direction: nx), and refractive index in the thickness direction (Nz)) of two orthogonal axes were determined by an Abbe refractometer (ATAGO CO., LTD, manufactured by NAR-4T, measurement wavelength 589 nm). These values were used to determine the NZ coefficient.
(8) Delay (Re)
The retardation is a parameter defined by the product (Δnxy×d) of the refractive index anisotropy (Δnxy= |nx-ny|) of the orthogonal biaxial directions on the film and the film thickness d (nm), and is a criterion indicating the optical isotropy and anisotropy. The anisotropy of refractive index (Δnxy) of biaxial was determined by the following method. The slow axis direction of the film was determined by using a molecular orientation meter (molecular orientation meter model MOA-6004, manufactured by ojiscientific instruments co., ltd.), and a rectangle of 4cm×2cm was cut so that the slow axis direction was parallel to the long side of the sample for measurement, to obtain the sample for measurement. For this sample, the refractive index of the perpendicular biaxial (refractive index in the slow axis direction: ny, refractive index in the direction perpendicular to the slow axis direction: nx) and the refractive index in the thickness direction (Nz) were obtained by an Abbe refractometer (ATAGO CO., LTD, manufactured by NAR-4T, measurement wavelength 589 nm), and the absolute value of the refractive index difference (|Nx-Ny|) of the biaxial was used as the refractive index anisotropy (. DELTA.Nxy). The thickness D (nm) of the film was measured by an electrometer (Fine Liu off co., mittoron 1245D, manufactured by Fine Liu off co.), and the unit was converted to nm. The retardation (Re) was obtained from the product (ΔNxy×d) of the anisotropy of refractive index (ΔNxy) and the thickness d (nm) of the film.
(9) Thickness direction retardation (Rth)
The thickness-direction retardation is a parameter representing an average of retardation amounts obtained by multiplying 2 birefringence Δ Nxz (= |nx-nz|) and Δ Nyz (= |ny-nz|) by the film thickness d, respectively, when viewed from a cross section in the film thickness direction. By the same method as the measurement of retardation, nx, ny, nz and film thickness d (nm) were obtained, and the average value of (Δ Nxz ×d) and (Δ Nyz ×d) was calculated to obtain the retardation in the thickness direction (Rth).
PREPARATION EXAMPLE 1-polyester A
The esterification reaction tank was warmed up, and 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged at 200℃and 0.017 parts by mass of antimony trioxide, 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine as a catalyst were charged while stirring. Then, the temperature was raised under pressure, the esterification reaction was carried out under pressure at 0.34MPa and 240℃to return the esterification reaction tank to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was raised to 260℃over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added thereto. Then, after 15 minutes, the resultant esterification reaction product was transferred to a polycondensation reaction tank, and after 15 minutes, the polycondensation reaction was carried out at 280℃under reduced pressure.
After the completion of the polycondensation reaction, the mixture was filtered with a NASLON filter having a 95% cutoff diameter of 5. Mu.m, extruded into strands from a nozzle, cooled and solidified with cooling water previously subjected to filtration (pore diameter: 1 μm or less), and cut into pellets. The intrinsic viscosity of the obtained polyethylene terephthalate resin (A) was 0.62dl/g, and the polyethylene terephthalate resin was substantially free of inactive particles and internal precipitated particles. (hereinafter abbreviated as PET (A))
PREPARATION EXAMPLE 2-polyester B
10 parts by mass of dried ultraviolet absorber (2, 2' - (1, 4-phenylene) bis (4H-3, 1-benzoxazin-4-one) and 90 parts by mass of PET (A) (intrinsic viscosity of 0.62 dl/g) containing no particles were mixed and a kneading extruder was used to obtain ultraviolet absorber-containing polyethylene terephthalate resin (B).
(hereinafter abbreviated as PET (B))
Preparation example 3 preparation of adhesion modified coating liquid
A water-dispersible metal sulfonate group-containing copolyester resin having a composition of 46 mol% of terephthalic acid, 46 mol% of isophthalic acid and 8 mol% of sodium 5-sulfoisophthalate as a dicarboxylic acid component (based on the whole dicarboxylic acid component), 50 mol% of ethylene glycol and 50 mol% of neopentyl glycol as a diol component (based on the whole diol component) was produced by a conventional method by conducting transesterification and polycondensation. Then, after 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 a nonionic surfactant were mixed, the mixture was heated and stirred to 77 ℃, 5 parts by mass of the above-mentioned water-dispersible metal sulfonate group-containing copolyester resin was added, and stirring was continued until the mass of the resin disappeared, and then the aqueous resin dispersion was cooled to room temperature to obtain a uniform water-dispersible copolyester resin liquid having a solid content of 5.0% by mass. Further, 3 parts by mass of aggregated silica particles (SILYSIA CHEMICALLTD. Manufactured by FUJI SILYSIA CHEMICALLTD. SILYSIA 310) were dispersed in 50 parts by mass of water, and then 0.54 parts by mass of an aqueous dispersion of SILYSIA 310 was added to 99.46 parts by mass of the water-dispersible copolyester resin liquid, and 20 parts by mass of water was added with stirring, to obtain an adhesive modified coating liquid.
Example 1
90 parts by mass of a PET (A) resin pellet containing no particles and 10 parts by mass of a PET (B) resin pellet containing an ultraviolet absorber, which are raw materials for an intermediate layer of a base film, were dried at 135℃for 6 hours under reduced pressure (1 Torr), and then supplied to an extruder 2 (for an intermediate layer II), and further PET (A) was dried by a conventional method and supplied to an extruder 1 (for an outer layer I and an outer layer III), respectively, and melted at 285 ℃. The 2 polymers were each filtered through a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particles 95% cut), laminated with 2 kinds of 3-layer joint blocks, extruded from the pipe head into a sheet, and then wound on a casting drum (casting drum) having a surface temperature of 30 ℃ by an electrostatic casting method to be cooled and solidified, thereby producing an unstretched film. At this time, the ratio of the thicknesses of the layer I, layer II, and layer III was 10:80:10, the discharge amount of each extruder was adjusted.
Next, the coating weight after drying was set to 0.08g/m by the reverse roll method 2 The above-mentioned bonding methodThe coating liquid was applied to both sides of the unstretched PET film, and then dried at 80℃for 20 seconds.
The unstretched film having the coating layer formed thereon was introduced into a tenter stretcher, and the end of the film was clamped by a clamp and introduced into a hot air zone at 105℃to stretch the film to 4.0 times in TD. Subsequently, the film cooled to 100℃was subjected to heat treatment at 180℃for 30 seconds, then stretched 1% in MD, then opened with clamps holding both ends of the film cooled to 60℃and taken up at a tension of 350N/m, and a huge roll of a uniaxially oriented PET film having a film thickness of about 80 μm was collected, and the obtained huge roll was subjected to 3-division to obtain 3 slit rolls (L (left side), C (center) and R (right side)). The polarizer protective film 1 was obtained from the slit roll located at R (the center portion of the slit roll located at R was used as the polarizer protective film 1).
On one side of a polarizing plate (the shrinkage force in the absorption axis direction of the polarizing plate is 5100N/m) containing PVA, iodine and boric acid, a polarizing plate protective film 1 was adhered so that the transmission axis of the polarizing plate became parallel to the MD of the film. Further, a TAC film (manufactured by Fujifilm Corporation and having a thickness of 80 μm) was adhered to the opposite surface of the polarizing plate. Thus, a polarizing plate (polarizing plate a) having a longitudinal direction aligned with the transmission axis direction of the polarizing plate and a polarizing plate (polarizing plate B) having a longitudinal direction aligned with the absorption axis direction of the polarizing plate were produced. A polarizing plate B was attached to the visible side of an IPS liquid crystal cell using a glass substrate having a thickness of 0.4mm and a polarizing plate a was attached to the light source side of the IPS liquid crystal cell having a 50 inch size by PSA so that the polarizing plate protective film 1 was located on the distal side (opposite side) from the liquid crystal cell, respectively, to produce a liquid crystal panel. The liquid crystal panel is mounted in a case, thereby manufacturing a liquid crystal display device.
Example 2
A polarizer protective film 2 was obtained in the same manner as in the polarizer protective film 1 of example 1 except that the film cooled to 100 ℃ was stretched by 2.5% in the longitudinal direction in the film formation of the polarizer protective film 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 2 in example 1.
Example 3
A polarizer protective film 3 was obtained in the same manner as in the polarizer protective film 1 in example 1 except that the film cooled to 100 ℃ was stretched by 4% in the longitudinal direction in the film formation of the polarizer protective film 1. In example 1, a liquid crystal display device was produced in the same manner as in example 1 except that a polarizing plate having a shrinkage force in the absorption axis direction of 5100N/m was replaced with a polarizing plate of 11200N/m and a polarizing plate protective film 1 was replaced with a polarizing plate protective film 3.
Example 4
A polarizer protective film 4 was produced in the same manner as in the polarizer protective film 1, except that a blend of 90 mass% PET (a) and 10 mass% PBT was used as the raw material of the I layer, the II layer, and the III layer, and the film cooled to 100 ℃ was stretched by 4% in the longitudinal direction. In example 1, a liquid crystal display device was produced in the same manner as in example 1 except that a polarizing plate having a shrinkage force in the absorption axis direction of 5100N/m was replaced with a polarizing plate of 11200N/m and the polarizing plate protective film 1 was replaced with a polarizing plate protective film 4. As the PBT, mitsubishi Engineering-Plastics Corporation NV5020 (0.52 dl/g) was used.
Example 5
The same procedure as for the polarizer protective film 1 was conducted except that the rotation speed of the casting roll was adjusted so that the thickness of the stretched film was 50. Mu.m, to obtain a polarizer protective film 5. 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 5 in example 1.
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 ℃ was stretched by 2.5% in the longitudinal direction. 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 in example 1.
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 ℃ was stretched by 4% in the longitudinal direction.
In example 1, a liquid crystal display device was produced in the same manner as in example 1 except that a polarizing plate having a shrinkage force in the absorption axis direction of 5100N/m was replaced with a polarizing plate of 11200N/m and the polarizing plate protective film 1 was replaced with a polarizing plate protective film 7.
Example 8
The same procedure as for the polarizer protective film 1 was conducted except that the rotation speed of the casting roll was adjusted so that the thickness of the stretched film became 160. Mu.m, to obtain a polarizer protective film 8. 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 8 in example 1.
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 ℃ was stretched by 2.5% in the width direction. Next, a polarizing plate having a shrinkage force in the absorption axis direction of 5100N/m was replaced with a polarizing plate of 11200N/m; a polarizing plate A and a polarizing plate B are manufactured by pasting the polarizing plates in such a way that the transmission axis of the polarizing plates is parallel to the TD of the polarizing plate protective film; 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 in the polarizer protective film 1 except that the film was stretched 4.0 times in MD and 1.0 times in TD. 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 in example 1.
Example 11
The same procedure as for the polarizer protective film 10 was followed except that the film cooled to 100℃was stretched by 1.5% in MD to obtain a polarizer protective film 11. 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
The same procedure as for the polarizer protective film 10 was followed except that the film cooled to 100℃was stretched by 2.5% in MD to obtain a polarizer protective film 12.
A polarizer with a shrinkage force in the absorption axis direction of 5100N/m was replaced with a 11200N/m polarizer; 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 12.
Example 13
As a raw material for the I layer, the II layer, and the III layer, a blend of 90 mass% of PET (a) and 10 mass% of PBT was used; and, the film cooled to 100℃was stretched by 3% in MD, and a polarizer protective film 13 was obtained in the same manner as in the polarizer protective film 10.
A polarizer with a shrinkage force in the absorption axis direction of 5100N/m was replaced with a 11200N/m polarizer; 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 13. As the PBT, mitsubishi Engineering-Plastics Corporation NV5020 (0.52 dl/g) was used.
Example 14
The same procedure as for the polarizer protective film 10 was conducted except that the rotation speed of the casting roll was adjusted so that the thickness of the stretched film was 50. Mu.m, and the film cooled to 100℃was stretched by 1.5% in the MD, to obtain a polarizer protective film 14. 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 14.
Example 15
The film cooled to 100℃was stretched by 2% in the MD, and a polarizer protective film 15 was obtained in the same manner as in the polarizer protective film 14. 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
The same procedure as for the polarizer protective film 14 was conducted except that the film cooled to 100℃was stretched 5% in TD, to obtain a polarizer protective film 16. Then, a polarizing plate A and a polarizing plate B are manufactured by pasting the polarizing plates in such a way that the transmission axis of the polarizing plates is parallel to the TD direction of the polarizing plate protective film; 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 16.
Example 17
The same procedure as for the polarizer protective film 10 was followed except that the film cooled to 100℃was stretched by 2% in MD to obtain a polarizer protective film 20. 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 20 in example 1.
Example 18
The same procedure as for the polarizer protective film 10 was followed except that the film cooled to 100℃was stretched by 2.5% in MD to obtain a polarizer protective film 21. 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 21.
Comparative example 1
A polarizer protective film 17 was obtained in the same manner as in the polarizer protective film 1 except that the clamps for clamping both ends of the film were opened at 95 ℃ in the cooling step after stretching and heat fixing. The polarizer protective film 1 is replaced with a polarizer protective film 17; a liquid crystal display device was obtained in the same manner as in example 1, except that the polarizing plate a and the polarizing plate B were manufactured by bonding such that the transmission axis of the polarizing plate and the TD of the polarizing plate protective film were parallel.
Comparative example 2
The same procedure as for the polarizer protective film 14 was followed except that the film cooled to 100℃was stretched by 0.8% in the width direction, to obtain a polarizer protective film 18. A polarizer with a shrinkage force in the absorption axis direction of 5100N/m was replaced with a 11200N/m polarizer; and, the polarizer protective film 1 is replaced with a polarizer protective film 18; a liquid crystal display device was obtained in the same manner as in example 1, except that the polarizing plate a and the polarizing plate B were manufactured by bonding such that the transmission axis of the polarizing plate and the TD of the polarizing plate protective film were parallel.
Comparative example 3
The same procedure as for the polarizer protective film 8 was followed except that the film cooled to 100℃was stretched by 0.3% in the width direction, to obtain a polarizer protective film 19. A polarizer with a shrinkage force in the absorption axis direction of 5100N/m was replaced with a 11200N/m polarizer; and, the polarizer protective film 1 is replaced with a polarizer protective film 19; a liquid crystal display device was obtained in the same manner as in example 1, except that the polarizing plate a and the polarizing plate B were manufactured by bonding such that the transmission axis of the polarizing plate and the TD of the polarizing plate protective film were parallel.
The liquid crystal panels of the liquid crystal display devices of examples 1 to 18 and the liquid crystal panels of the liquid crystal display devices of comparative examples 1 to 3 were subjected to heat treatment for 30 minutes using a gill aging oven set at 100 ℃, and then cooled for 10 minutes in an environment set at room temperature of 25 ℃ and 50RH%, and as a result, the liquid crystal panels were observed, and as a result, no curl was observed in examples 1 to 16, but curl was observed in comparative examples 1 to 3.
The measurement results of each example are shown in table 1.
TABLE 1
Figure BDA0002450459680000251
Industrial applicability
According to the present invention, a liquid crystal display device in which curl of a laminate formed of a polarizing plate/a liquid crystal cell/a polarizing plate is highly controlled can be provided.

Claims (52)

1. A liquid crystal display device comprising a liquid crystal cell, a polarizing plate A attached to one surface of the liquid crystal cell, and a polarizing plate B attached to the other surface of the liquid crystal cell, characterized in that,
the polarizer A has the following structure: the direction of the light transmission axis of the polarizing plate is parallel to the long side direction of the liquid crystal display device, a polyester film is laminated on the far side of the polarizing plate and the liquid crystal unit,
the polarizing plate B has the following structure: the absorption axis direction of the polarizer is parallel to the longitudinal direction of the liquid crystal display device, a protective film is laminated on at least one side of the polarizer,
shrinkage force F in the longitudinal direction of the liquid crystal display device of the polyester film f Contraction force F in the longitudinal direction of the liquid crystal display device of the polarizing plate of polarizing plate B p Satisfies the following formula (1),
f is more than or equal to 0.1 f /F p ≤2
Wherein the shrinkage force F f (N/m) is the thickness (mm) of the polyester film. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F f Wherein the elastic modulus and the heat shrinkage are values in the longitudinal direction of the liquid crystal display device of the polyester film, the heat shrinkage is a shrinkage when heat-treated at 100 ℃ for 30 minutes,
force of contraction F p (N/m) the thickness (mm) of the polarizing plate of polarizing plate B. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F p In the formula (I), the elastic modulus and the heat shrinkage are values in the longitudinal direction of the liquid crystal display device of the polarizing plate, and the heat shrinkage is a shrinkage rate when heat treatment is performed at 100 ℃ for 30 minutes.
2. The liquid crystal display device according to claim 1, wherein the polyester film of the polarizing plate A has an elastic modulus in a longitudinal direction of 1000 to 9000N/mm 2 。
3. The liquid crystal display device according to claim 1 or 2, wherein the heat shrinkage in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate a is 0.1 to 5%.
4. The liquid crystal display device according to claim 1, wherein the polarizing plate a has a thickness of a polyester film of 40 to 160 μm.
5. The liquid crystal display device according to claim 1, wherein an inclination angle of an alignment main axis of the polyester film of the polarizing plate a with respect to a long side direction or a short side direction of the liquid crystal display device is 15 degrees or less.
6. The liquid crystal display device according to claim 1, wherein the polarizing plate a has a tilt angle of a principal axis of shrinkage of the polyester film with respect to a long side direction or a short side direction of the liquid crystal display device of 15 degrees or less.
7. The liquid crystal display device according to claim 1, wherein the polarizing plate a has the following structure: a TAC film, a cyclic olefin film, or an acrylic film is laminated on the liquid crystal cell side of the polarizing plate.
8. The liquid crystal display device according to claim 1, wherein the polarizing plate a has the following structure: a protective film or an optical compensation film is not laminated on the liquid crystal cell side of the polarizing plate.
9. The liquid crystal display device according to claim 1, wherein the polarizing plate B has the following structure: a TAC film, a cyclic olefin film, or an acrylic film is laminated on the liquid crystal cell side of the polarizing plate.
10. The liquid crystal display device according to claim 1, wherein the polarizing plate B has the following structure: a protective film or an optical compensation film is not laminated on the liquid crystal cell side of the polarizing plate.
11. The liquid crystal display device according to claim 1, wherein a thickness of a glass substrate constituting the liquid crystal cell is 0.6mm or less.
12. The liquid crystal display device according to claim 1, wherein a thickness of a glass substrate constituting the liquid crystal cell is less than 0.5mm.
13. The liquid crystal display device according to claim 1, wherein a thickness of a glass substrate constituting the liquid crystal cell is 0.4mm or less.
14. The liquid crystal display device according to claim 1, wherein a thickness of a glass substrate constituting the liquid crystal cell is 0.3mm or less.
15. The liquid crystal display device according to claim 1, wherein a thickness of a glass substrate constituting the liquid crystal cell is 0.25mm or less.
16. The liquid crystal display device according to claim 1, wherein the polarizing plate B is a polarizing plate on a visible side starting from a liquid crystal cell, and the polarizing plate a is a polarizing plate on a backlight light source side starting from a liquid crystal cell.
17. The liquid crystal display device according to claim 1, wherein the F f /F p F is 0.1 to or less f /F p ≤1.0。
18. The liquid crystal display device according to claim 1, wherein the F f /F p F is 0.1 to or less f /F p <1.0。
19. The liquid crystal display device according to claim 1, wherein the F f /F p F is 0.1 to or less f /F p ≤0.9。
20. The liquid crystal display device according to claim 1, wherein the F f /F p F is 0.1 to or less f /F p ≤0.8。
21. The liquid crystal display device according to claim 1, wherein the F f /F p F is 0.2-F f /F p ≤0.8。
22. The liquid crystal display device according to claim 1, wherein,the F is f /F p F is 0.3 to less than or equal to F f /F p ≤0.7。
23. The liquid crystal display device according to claim 1, wherein the polyester film of the polarizing plate A has an elastic modulus in a longitudinal direction of 1800 to 7000N/mm 2 。
24. The liquid crystal display device according to claim 1, wherein the heat shrinkage in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate a is 0.1 to 3%.
25. The liquid crystal display device according to claim 1, wherein the heat shrinkage in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate a is 0.1 to 2%.
26. The liquid crystal display device according to claim 1, wherein the heat shrinkage in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate a is 0.1 to 1.5%.
27. The liquid crystal display device according to claim 1, wherein the heat shrinkage in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate a is 0.1 to 1%.
28. The liquid crystal display device according to claim 1, wherein an inclination angle of a major axis of orientation of the polyester film of the polarizing plate a with respect to a long side direction or a short side direction of the liquid crystal display device is 10 degrees or less.
29. The liquid crystal display device according to claim 1, wherein an inclination angle of a major axis of orientation of the polyester film of the polarizing plate a with respect to a long side direction or a short side direction of the liquid crystal display device is 8 degrees or less.
30. The liquid crystal display device according to claim 1, wherein an in-plane retardation amount of the polyester film is 3000nm or more and 30000nm or less.
31. The liquid crystal display device according to claim 1, wherein an in-plane retardation amount of the polyester film is 6000nm or more and 15000nm or less.
32. The liquid crystal display device according to claim 1, wherein a ratio Re/Rth of an in-plane retardation Re to a retardation Rth in a thickness direction of the polyester film is 0.5 or more and 2.0 or less.
33. The liquid crystal display device according to claim 1, wherein a ratio Re/Rth of an in-plane retardation Re to a retardation Rth in a thickness direction of the polyester film is 0.5 or more and 1.2 or less.
34. The liquid crystal display device according to claim 1, wherein a difference between a refractive index of the polyester film in a slow axis direction and a refractive index in a fast axis direction is 0.05 or more.
35. The liquid crystal display device according to claim 1, wherein a difference between a refractive index of the polyester film in a slow axis direction and a refractive index in a fast axis direction is 0.07 or more.
36. The liquid crystal display device according to claim 1, wherein a difference between a refractive index of the polyester film in a slow axis direction and a refractive index in a fast axis direction is 0.08 or more.
37. The liquid crystal display device according to claim 1, wherein a difference between a refractive index of the polyester film in a slow axis direction and a refractive index in a fast axis direction is 0.09 or more.
38. The liquid crystal display device according to claim 1, wherein a difference between a refractive index of the polyester film in a slow axis direction and a refractive index in a fast axis direction is 0.1 or more.
39. The liquid crystal display device according to claim 1, wherein the polyester film of the polarizing plate a is uniaxially stretched, and is stretched again in the same direction as the uniaxial stretching during cooling after heat fixing.
40. The liquid crystal display device according to claim 1, wherein the polyester film of the polarizing plate a is uniaxially stretched, and is further stretched in the same direction as the uniaxial stretching during cooling after heat fixing, and the direction of the stretching is parallel to the light transmission axis direction of the polarizing plate a.
41. The liquid crystal display device according to claim 1, wherein the polyester film is uniaxially stretched, and is stretched again in the same direction as the uniaxial stretching during cooling after heat fixing,
the polarizing plate A satisfies the following characteristics (A1) to (A2),
(A1) The stretching direction of the polyester film is parallel to the light transmission axis of the polaroid A,
(A2) A TAC film, a cyclic olefin film or an acrylic film as a protective film or an optical compensation film, or a protective film or an optical compensation film not laminated is laminated on a liquid crystal cell side surface of a polarizing plate included in the polarizing plate A,
the polarizing plate B satisfies the following characteristics (B1) to (B2),
(B1) A TAC film, a cyclic olefin film or an acrylic film as a protective film or an optical compensation film, or a protective film or an optical compensation film not laminated is laminated on a liquid crystal cell side surface of a polarizing plate provided in the polarizing plate B,
(B2) A TAC film, a cyclic olefin film, or an acrylic film as a protective film or an optical compensation film is laminated on a surface of the polarizing plate B on the side of the polarizing plate that is distal from the liquid crystal cell.
42. The liquid crystal display device according to claim 1, wherein the polyester film is uniaxially stretched, re-stretched in the same direction as the uniaxial stretching during cooling after heat fixing, and is denoted as a polyester film A, and polarizing plates A and B are manufactured using the polyester film A, respectively,
The polarizing plate A satisfies the following characteristics (A1) to (A2),
(A1) The stretching direction of the polyester film A is parallel to the light transmission axis of the polaroid provided by the polaroid A,
(A2) A TAC film, a cyclic olefin film or an acrylic film as a protective film or an optical compensation film, or a protective film or an optical compensation film not laminated is laminated on a liquid crystal cell side surface of a polarizing plate included in the polarizing plate A,
the polarizing plate B satisfies the following characteristics (B1) to (B3),
(B1) A TAC film, a cyclic olefin film or an acrylic film as a protective film or an optical compensation film, or a protective film or an optical compensation film not laminated is laminated on a liquid crystal cell side surface of a polarizing plate provided in the polarizing plate B,
(B2) The polyester film A is laminated on a surface of a polarizing plate of the polarizing plate B, which is far from the liquid crystal unit,
(B3) In the above (B2), the stretching direction of the polyester film A of the polarizing plate B is parallel to the light transmission axis of the polarizing plate B,
shrinkage force F in the longitudinal direction of a liquid crystal display device of a polyester film A included in a polarizing plate A f Contraction force F in longitudinal direction of liquid crystal display device of polarizer with polarizer B p Satisfies the following formula (1),
f is more than or equal to 0.1 f /F p ≤1.0
Wherein the shrinkage force F f (N/m) is the thickness (mm) of the polyester film A of the polarizing plate A. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F f In the formula (A), the elastic modulus and the thermal shrinkage are both the liquid crystal of the polyester film A of the polarizing plate ADisplaying the value of the device in the longitudinal direction, wherein the heat shrinkage is the shrinkage when heat treatment is carried out at 100 ℃ for 30 minutes,
force of contraction F p (N/m) the thickness (mm) of the polarizing plate of polarizing plate B. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F p In the formula (I), the elastic modulus and the heat shrinkage are values in the longitudinal direction of the liquid crystal display device of the polarizing plate, and the heat shrinkage is a shrinkage rate when heat treatment is performed at 100 ℃ for 30 minutes.
43. The liquid crystal display device according to claim 1, wherein the polarizing plate A satisfies the following characteristics (A1) to (A2),
(A1) The polyester film is stretched again in the same direction as the uniaxial stretching in the cooling process after the heat fixing, the stretching direction is parallel to the light transmission axis of the polaroid A,
the polyester film has an in-plane retardation Re of 6000nm to 15000nm, a ratio Re/Rth of Re to Rth of thickness of 1.2 or less, an Nz coefficient of 1.8 or less, a difference between a refractive index in a slow axis direction and a refractive index in a fast axis direction of 0.09 or more,
(A2) A TAC film, a cyclic olefin film or an acrylic film as a protective film or an optical compensation film, or a protective film or an optical compensation film not laminated is laminated on a liquid crystal cell side surface of a polarizing plate included in the polarizing plate A,
the polarizing plate B satisfies the following characteristics (B1) to (B3),
(B1) A TAC film, a cyclic olefin film or an acrylic film as a protective film or an optical compensation film, or a protective film or an optical compensation film not laminated is laminated on a liquid crystal cell side surface of a polarizing plate provided in the polarizing plate B,
(B2) A polyester film, or a TAC film, a cyclic olefin film, or an acrylic film as a protective film or an optical compensation film is laminated on a surface of the polarizing plate B on a side of the polarizing plate on a distal end side from the liquid crystal cell,
(B3) In the above (B2), when a polyester film is laminated on the surface of the polarizing plate B having a polarizing plate on the side of the distal end from the liquid crystal cell, the polyester film of the polarizing plate B is uniaxially stretched, and is stretched again in the same direction as the uniaxial stretching in the cooling process after the heat fixing, the direction of the stretching being parallel to the light transmission axis of the polarizing plate B having a polarizing plate,
The polyester film of the polarizing plate B has an in-plane retardation Re of 6000nm to 15000nm, a ratio Re/Rth of the in-plane retardation Re to a retardation Rth in the thickness direction of 1.2 or less, an Nz coefficient of 1.8 or less, a difference between a refractive index in the slow axis direction and a refractive index in the fast axis direction of 0.09 or more,
shrinkage force F in the longitudinal direction of a liquid crystal display device of a polyester film included in a polarizing plate A f Contraction force F in longitudinal direction of liquid crystal display device of polarizer with polarizer B p Satisfies the following formula (1),
f is more than or equal to 0.1 f /F p ≤1.0
Wherein the shrinkage force F f (N/m) is the thickness (mm) of the polyester film of the polarizing plate A. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F f Wherein the elastic modulus and the heat shrinkage ratio are values in the longitudinal direction of the liquid crystal display device of the polyester film of the polarizing plate A, the heat shrinkage ratio being a shrinkage ratio when heat-treated at 100 ℃ for 30 minutes,
force of contraction F p (N/m) the thickness (mm) of the polarizing plate of polarizing plate B. Times. The elastic modulus (N/mm) 2 ) X heat shrinkage (%) 100 x 1000, shrinkage force F p In the formula (I), the elastic modulus and the heat shrinkage are values in the longitudinal direction of the liquid crystal display device of the polarizing plate, and the heat shrinkage is a shrinkage rate when heat treatment is performed at 100 ℃ for 30 minutes.
44. The liquid crystal display device according to claim 43, wherein the in-plane retardation of the polyester film used in the polarizing plate A is 8000nm or more,
in the above (B2), when a polyester film is laminated on the surface of the polarizing plate B on the side of the polarizing plate on the far side from the liquid crystal cell, the retardation in-plane of the polyester film of the polarizing plate B is 8000nm or more.
45. The liquid crystal display device according to claim 43, wherein the difference between the refractive index in the slow axis direction and the refractive index in the fast axis direction of the polyester film used in the polarizing plate A is 0.1 or more,
in the above (B2), when a polyester film is laminated on the surface of the polarizing plate B on the far side from the liquid crystal cell, the difference between the refractive index of the polyester film in the slow axis direction and the refractive index in the fast axis direction is 0.1 or more.
46. The liquid crystal display device according to claim 43, wherein the Nz coefficient of the polyester film used in the polarizing plate A is 1.6 or less,
in the above (B2), when a polyester film is laminated on the surface of the polarizing plate B on the side of the polarizing plate that is distal from the liquid crystal cell, the Nz coefficient of the polyester film of the polarizing plate B is 1.6 or less.
47. The liquid crystal display device according to claim 43, wherein the thickness of the polyester film used in the polarizing plate A is 80. Mu.m,
In the above (B2), when a polyester film is laminated on the surface of the polarizing plate B on the side of the polarizing plate on the far side from the liquid crystal cell, the thickness of the polyester film of the polarizing plate B is 80. Mu.m.
48. The liquid crystal display device according to claim 43, wherein the polyester film used in the polarizing plate A is a polyethylene terephthalate film,
in the above (B2), when a polyester film is laminated on the surface of the polarizing plate B on the side of the polarizing plate that is distal from the liquid crystal cell, the polyester film of the polarizing plate B is a polyethylene terephthalate film.
49. The liquid crystal display device according to claim 1, wherein the thickness of the polyester film of the polarizing plate a is 80 to 160 μm.
50. The liquid crystal display device according to any one of claims 41 to 43, wherein a retardation of the protective film formed of the TAC film, the cyclic olefin film or the acrylic film is 500nm or less.
51. The liquid crystal display device according to any one of claims 41 to 43, wherein the formula (1) is 0.1.ltoreq.F f /F p <1.0。
52. The liquid crystal display device according to any one of claims 1 or 41 to 43, wherein the formula (1) is 0.1.ltoreq.F f /F p ≤0.94。
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