Classifications

• • 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
  • 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
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
• • 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
  • 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
  • G02F1/133531—Polarisers characterised by the arrangement of polariser or analyser axes

Definitions

• the present invention relates to a liquid crystal display device used for a monitor for a personal computer, a television and the like.
• Patent Document 1 discloses a viewing side and a backlight arranged above and below a liquid crystal cell of a liquid crystal display device.
• Patent Document 2 pays attention to the difference in contraction force between the absorption axis direction and the transmission axis direction of the polarizing plate, and warps the display device by reducing the contraction force of the polarizing plate in the main contraction direction at high temperature or high temperature and high humidity. Has improved.
• Patent Document 1 and Patent Document 2 have been studied for improvement by controlling the strain accompanying temperature change and the strain accompanying moisture absorption / desorption, a film having a low glass transition temperature such as a polyethylene terephthalate film is used. In this case, the influence of the residual strain (heat shrinkage rate) originally possessed by the film should not be taken into consideration.
• the problem to be solved by the present invention is to provide a liquid crystal display device capable of highly controlling curling of a laminate comprising a polarizing plate / liquid crystal cell / polarizing plate in the liquid crystal display device.
• a polarizing plate is usually laminated on one surface of a liquid crystal cell so that the transmission axis direction of the polarizer is parallel to the long side direction of the liquid crystal display device, and the polarizer absorbs on the other surface.
• Polarizers are stacked so that the axial direction is parallel to the long side of the liquid crystal display device.
• the problem of the form factor that curls are likely to occur due to the contraction of the polarizing plate having the longer side of the polarizer absorption axis having a large shrinkage force (the curl is In general, it tends to occur in the long side direction), and due to the influence of the asymmetrical configuration of the upper and lower polarizing plates in the liquid crystal panel, the liquid crystal panel has the polarizer transmission axis of the upper and lower polarizing plates arranged in crossed Nicols as the long side
• the present inventors have found that it is the essence of the problem to be convex toward the polarizing plate.
• the shrinkage force of a film is measured using a TMA or the like to set the initial length with a minimal load at a low temperature at the start of the test, and measure the force in the shrinking direction during temperature rise while maintaining the initial length. To do.
• thermal shrinkage due to an increase in the free volume / occupied volume of the polymer due to the temperature increase at the same time as the shrinkage due to the recovery of residual strain accompanying the conformational change of the polymer (hereinafter simply referred to as thermal shrinkage)
• thermal shrinkage In the temperature range near the glass transition temperature of the polyester film (for example, about Tg + 50 ° C.), the thermal shrinkage is less than the thermal expansion. It expands and no contractile force is observed.
• the representative present invention is as follows. Item 1.
• a liquid crystal display device having a liquid crystal cell, a polarizing plate A bonded to one surface of the liquid crystal cell, and a polarizing plate B bonded to the other surface of the liquid crystal cell
• the polarizing plate A has a structure in which the transmission axis direction of the polarizer is parallel to the long side direction of the liquid crystal display device, and a polyester film is laminated on at least one surface of the polarizer.
• the polarizing plate B has a structure in which the absorption axis direction of the polarizer is parallel to the long side direction of the liquid crystal display device, and a protective film is laminated on at least one surface of the polarizer.
• the contraction force F f in the long side direction of the liquid crystal display device of the polyester film and the contraction force F p in the long side direction of the liquid crystal display device of the polarizer included in the polarizing plate B satisfy the following formula (1): Liquid crystal display device.
• Item 4. Item 4. The liquid crystal display device according to any one of Items 1 to 3, wherein the polyester film has a thickness of 40 to 200 ⁇ m.
• Item 5. Item 5. The liquid crystal display device according to any one of items 1 to 4, wherein an inclination of an orientation main 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.
• the liquid crystal display device according to any one of items 1 to 5, wherein an inclination of the shrink main 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 7 In a liquid crystal panel having a liquid crystal cell, a polarizing plate A bonded to one surface of the liquid crystal cell, and a polarizing plate B bonded to the other surface of the liquid crystal cell, The polarizing plate A has a structure in which the transmission axis direction of the polarizer is parallel to the long side direction of the polarizing plate A, and a polyester film is laminated on at least one surface of the polarizer.
• the polarizing plate B has a structure in which the absorption axis direction of the polarizer is parallel to the long side direction of the polarizing plate B, and a protective film is laminated on at least one surface of the polarizer.
• the liquid crystal panel in which the contraction force F f in the long side direction of the polarizing plate A of the polyester film and the contraction force F p in the long side direction of the polarizing plate B of the polarizer included in the polarizing plate B satisfy the following formula (1).
• Item 10. Item 10. The liquid crystal panel according to any one of items 7 to 9, wherein the polyester film has a thickness of 40 to 200 ⁇ m.
• Item 11. Item 11. The liquid crystal panel according to any one of items 7 to 10, wherein an inclination of an orientation main axis 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.
• liquid crystal display device in which curling of a laminate (liquid crystal panel) composed of a polarizing plate / liquid crystal cell / polarizing plate generated in a high temperature or high temperature and high humidity environment is reduced.
• the screen of the liquid crystal display device is usually rectangular and has a long side and a short side.
• the “long side direction of the liquid crystal display device” is a direction parallel to the long side of the liquid crystal display device, and includes “long side direction of the polarizing plate A”, “long side direction of the polarizing plate B”, This is the same as “the long side direction of the polarizer of the polarizing plate B” and “the long side direction of the polyester film of the polarizing plate A”. Therefore, in this specification, “the long side direction of the liquid crystal display device” means “the long side direction of the polarizing plate A”, “the long side direction of the polarizing plate B”, and “the long side of the polarizer included in the polarizing plate B”.
• the “short-side direction of the liquid crystal display device” means a direction parallel to the short side of the liquid crystal display device and a direction perpendicular to the long-side direction.
• the liquid crystal display device of the present invention has at least a liquid crystal cell, a polarizing plate A bonded to one surface of the liquid crystal cell, and a polarizing plate B bonded to the other surface of the liquid crystal cell.
• a liquid crystal cell and a polarizing plate can usually be bonded together through an adhesion layer.
• the liquid crystal display device can include constituent members that are usually used in the liquid crystal display device, such as a backlight.
• the liquid crystal cell has a structure in which liquid crystal is sandwiched between two glass substrates.
• the thickness of the glass substrate constituting the liquid crystal cell may be 0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, or 0.25 mm or less. preferable.
• the transmission axis direction of the polarizer is parallel to the long side direction of the liquid crystal display device (that is, the transmission axis direction of the polarizer is parallel to the long side direction of the polarizing plate A). It has a structure in which a polyester film (used as a polarizer protective film) is laminated on at least one surface of the child.
• a protective film having a low retardation such as a TAC film, a cyclic olefin film, an acrylic film, or an optical compensation film can be laminated on the surface of the polarizer opposite to the surface on which the polyester film is laminated.
• the protective film having a low retardation can be, for example, a protective film having a retardation of 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, or 50 nm or less.
• the polarizing plate A has a structure in which a polyester film is laminated only on one side of the polarizer and a protective film or an optical compensation film is not laminated on the other side of the polarizer.
• the polyester film can be placed on the liquid crystal cell side of the polarizer, or on the distal side (outside) of the liquid crystal cell (or both sides), but on the distal side (outside) of the polarizer liquid crystal cell It is preferable to arrange.
• the transmission axis direction of the polarizer is parallel to the long side direction of the liquid crystal display device, but it is most preferable that the transmission axis direction be completely parallel, but this is a concept that allows a slight deviation. That is, the angle formed by the transmission axis direction of the polarizer and the long side direction of the liquid crystal display device is preferably 7 degrees or less, preferably 5 degrees or less, preferably 3 degrees or less, preferably 2 degrees or less, and 1 degree or less. Is preferred, most preferably 0 degrees.
• the absorption axis direction of the polarizer is parallel to the long-side direction of the liquid crystal display device (that is, the absorption axis of the polarizer is parallel to the long-side direction of the polarizing plate B). It is the structure where the protective film was laminated
• a protective film with low retardation such as a TAC film, a cyclic olefin film, an acrylic film, or an optical compensation film can be laminated on the protective film.
• the protective film having a low retardation can be, for example, a protective film having a retardation of 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, or 50 nm or less.
• a polyester film can also be laminated
• the polarizing plate B may have a structure in which a polyester film is laminated on one surface of a polarizer and the above-described protective film or optical compensation film is laminated on the other surface.
• the polarizing plate B is also a preferable embodiment in which a polyester film is laminated on only one side of the polarizer and a protective film or an optical compensation film is not laminated on the other side of the polarizer.
• the absorption axis direction of the polarizer be parallel to the long side direction of the liquid crystal display device, but it is most preferably completely parallel, but a slight deviation is allowed. That is, the angle formed between the absorption axis direction of the polarizer and the long side direction of the liquid crystal display device is preferably 7 degrees or less, preferably 5 degrees or less, preferably 3 degrees or less, preferably 2 degrees or less, and 1 degree or less. Is preferred, most preferably 0 degrees.
• the polarizing plate A may be used as either a polarizing plate on the viewing side or a polarizing plate on the backlight side from the liquid crystal cell, but is generally preferably disposed as a polarizing plate on the backlight side.
• the polarizing plate B may be used as either a polarizing plate on the viewing side or a polarizing plate on the backlight side of the liquid crystal cell, but is generally preferably disposed as a polarizing plate on the viewing side. 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 between them.
• F f / F p 0.1 ⁇ F f / F p ⁇ 2.
• the lower limit value of F f / F p is preferably 0.2 or 0.3.
• the upper limit value of F f / F p is 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, It is preferably 0.9, 0.8 or 0.7.
• F f indicates the shrinkage force in the long side direction of the liquid crystal display device of the polyester film of the polarizing plate A, and the thickness of the polyester film (mm) ⁇ elastic modulus (N / mm 2 ) ⁇ heat shrinkage rate (%) ⁇ 100. It is defined by x1000.
• F p indicates the contraction force of the polarizer of the polarizing plate B in the long side direction of the liquid crystal display device, and the thickness (mm) ⁇ elastic modulus (N / mm 2 ) ⁇ thermal contraction rate (%) of the polarizer of the polarizing plate B.
• ⁇ 100 ⁇ 1000 is defined.
• the elastic modulus and the thermal contraction rate are both values in the long side direction of the liquid crystal display device.
• the contraction force of the polarizing plate B is mainly expressed by the polarizer, and the contraction force changes depending on the thickness of the polarizer and the film forming conditions. Therefore, it is desirable to adjust the shrinkage force of the polyester film used for the polarizing plate A accordingly.
• the polyester film used for the polarizing plate A preferably has an elastic modulus in the long side direction of the liquid crystal display device of 1000 to 9000 N / mm 2 .
• the shrinkage force of the polyester film can be controlled by the elastic modulus, in order to increase the elastic modulus in the long side direction of the liquid crystal display device, it is highly oriented in the long side direction of the liquid crystal display device and the crystallinity is increased. Need to be high. Therefore, when the longitudinal direction of the elastic modulus is more than 9000 N / mm 2, since the problem of easily tearing becomes apparent, the upper limit is preferably 9000 N / mm 2, more preferably 8000 N / mm 2, More preferably, it is 7000 N / mm 2 .
• the lower limit of the elastic modulus is preferably 1000 N / mm 2, more preferably 1500 N / mm 2, further preferably 1800 N / mm 2.
• the elastic modulus can be measured by the method employed in the examples described later.
• the polyester film used for the polarizing plate A preferably has a thermal shrinkage of 0.1 to 5% in the long side direction of the liquid crystal display device at 30 ° C. for 30 minutes.
• the lower limit of the heat shrinkage rate is preferably 0.3% or more, preferably 0.4% or more, preferably 0.5% or more, and preferably 0.7% or more.
• the upper limit of the heat shrinkage rate is preferably 4% or less, preferably 3% or less, and preferably 2% or less. When the heat shrinkage rate is lower than 0.1%, that is, in the range of 0.01 to 0.099%, it is difficult to control the heat shrinkage rate without variation.
• thermal shrinkage rate can be measured by the method employed in the examples described later.
• the polyester film used for the polarizing plate A preferably has a thickness of 40 to 200 ⁇ m.
• the thickness of the polyester film is less than 40 ⁇ m, the polyester film is easily broken, and flatness is likely to be poor due to insufficient rigidity.
• the lower limit is substantially 40 ⁇ m.
• the film thickness exceeds 200 ⁇ m, the variation in the elastic modulus or heat shrinkage in the long side direction increases accordingly, which makes it difficult to control and increases the cost.
• the thickness of the polyester film can be measured by the method employed in the examples described later.
• the polyester film used for the polarizing plate A desirably has an inclination of 15 degrees or less between the orientation principal axis of the polyester film and the long side direction or the short side direction of the liquid crystal display device.
• the stretched polyester film usually has anisotropy of elastic modulus in the film plane, but the anisotropy of the elastic modulus and optical anisotropy of the stretched polyester film generally coincide. Therefore, with respect to the alignment main axis determined from the optical anisotropy, the narrow angle with the long side direction or the short side direction of the liquid crystal display device is set to 15 degrees or less so that the direction with the higher elastic modulus is the long side of the liquid crystal display device.
• the orientation main axis of the polyester film can be measured according to the measurement method employed in Examples described later.
• the polyester film used for the polarizing plate A preferably has a narrow angle of 15 degrees or less with respect to the major axis of the liquid crystal display device or the short side direction with respect to the shrink main axis of the polyester film.
• the stretched polyester film usually has anisotropy in heat shrinkage within the film plane, and the shrinkage main axis has an inclination.
• the narrow angle between the contraction main axis and 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.
• the narrow angle between the shrink main axis of the polyester film used for the polarizing plate A and the long side direction or the short side direction of the liquid crystal display device is preferably 15 degrees or less, more preferably 10 degrees or less, 9 degrees or less, or 8 degrees or less. preferable.
• the contraction main axis can be measured according to the measurement method employed in Examples described later.
• the polyester film used for the polarizing plate A preferably has in-plane retardation within a specific range from the viewpoint of suppressing rainbow spots observed on the screen of the liquid crystal display device.
• the lower limit of the in-plane retardation is preferably 3000 nm or more, 5000 nm or more, 6000 nm or more, 7000 nm or more, or 8000 nm or more.
• the upper limit of the in-plane retardation is preferably 30000 nm or less, more preferably 18000 nm or less, and further preferably 15000 nm or less.
• the polyester film when using a polyester film as a protective film also for the polarizing plate B, it is preferable that the polyester film also has in-plane retardation of the said range.
• the retardation of the polyester film can be obtained by measuring the biaxial refractive index and thickness, or can be obtained by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments).
• the refractive index can be obtained by an Abbe refractometer (measurement wavelength: 589 nm).
• the ratio of the in-plane retardation (Re) to the retardation in the thickness direction (Rth) (Re / Rth) of the polyester film used for the polarizing plate A is preferably 0.2 or more, preferably 0.3 or more, preferably Is 0.4 or more, preferably 0.5 or more, more preferably 0.5 or more, and still more preferably 0.6 or more.
• the ratio of the in-plane retardation to the thickness direction retardation (Re / Rth) is larger, the birefringence effect is more isotropic, and the occurrence of rainbow-like color spots due to the observation angle tends to be less likely to occur.
• the ratio of the retardation to the retardation in the thickness direction (Re / Rth) is 2.0. Therefore, the ratio of the retardation to the retardation in the thickness direction (Re / Rth)
• the upper limit is preferably 2.0.
• a preferable upper limit of Re / Rth is 1.2 or less.
• the thickness direction retardation means an average of retardation obtained by multiplying two birefringences ⁇ Nxz and ⁇ Nyz by the film thickness d when the film is viewed from the cross section in the thickness direction.
• the ratio (Re / Rth) of the in-plane retardation (Re) and the retardation in the thickness direction (Rth) is also in the above range. It is preferable.
• the polyester film used for the polarizing plate A preferably has a NZ coefficient of 2.5 or less, more preferably 2.0 or less, and even more preferably 1 from the viewpoint of suppressing iridescent color spots. .8 or less, more preferably 1.6 or less. And since a NZ coefficient will be 1.0 in a perfect uniaxial (uniaxial symmetry) film, the minimum of a NZ coefficient is 1.0. However, it should be noted that the mechanical strength in the direction perpendicular to the orientation direction tends to decrease significantly as the film approaches a perfect uniaxial (uniaxial symmetry) film. In addition, when using a polyester film as a protective film also for the polarizing plate B, it is preferable that the polyester film also has a NZ coefficient in the said range.
• the NZ coefficient is represented by
• the orientation axis of the film is obtained using a molecular orientation meter (MOA-6004 type molecular orientation meter, manufactured by Oji Scientific Instruments Co., Ltd.), and the biaxial refractive index (Ny, Nx, where the orientation axis direction and the direction perpendicular thereto are perpendicular) Ny> Nx) and the refractive index (Nz) in the thickness direction are determined by Abbe's refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm). The value obtained in this manner can be substituted for
• the value of Ny-Nx of the polyester film is preferably 0.05 or more, more preferably 0.07 or more, from the viewpoint of suppressing iridescent color spots. Preferably it is 0.08 or more, More preferably, it is 0.09 or more, Most preferably, it is 0.1 or more.
• the upper limit is not particularly defined, but in the case of a polyethylene terephthalate film, the upper limit is preferably about 1.5.
• the polyester film preferably has a Ny-Nx value within the above range.
• the polyester film used for the polarizing plate A can be obtained from any polyester resin.
• the type of the polyester resin is not particularly limited, and any polyester resin obtained by condensing dicarboxylic acid and diol can be used.
• the polyester film is also the same.
• dicarboxylic acid component examples include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, , 5-Naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic 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, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglu
• diol component examples 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-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, etc. Can be mentioned.
• the dicarboxylic acid component and the diol component constituting the polyester resin can be used alone or in combination of two or more.
• Suitable polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and more preferably polyethylene terephthalate and polyethylene naphthalate.
• other copolymer components may be included.
• These resins are excellent in transparency and excellent in thermal and mechanical properties.
• polyethylene terephthalate is a suitable material because it can achieve a high elastic modulus and the heat shrinkage rate is relatively easy to control.
• 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 in which the thermal shrinkage rate of the polyester film remains, an easy adhesion layer, a hard coat layer,
• the drying temperature can be set low, UV irradiation, This is an embodiment that is preferably performed by a method having a small thermal history such as electron beam irradiation.
• applying these functional layers during the process of forming the polyester film is more effective. This is a desirable embodiment.
• the polyester film used by this invention can be manufactured in accordance with the manufacturing method of a general polyester film.
• the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter.
• the method of performing heat processing is mentioned.
• a uniaxially stretched film or a biaxially stretched film may be used.
• MD is an abbreviation for Machine Direction, and may be referred to as a film flow direction, a longitudinal direction, and a longitudinal direction in this specification.
• TD is an abbreviation for Transverse Direction, and may be referred to as a width direction and a horizontal direction in this specification.
• the polyester film used as the polarizer protective film for the polarizing plate A adjusts the shrinkage force F f so that 0.1F p ⁇ F f ⁇ 2F p .
• the elastic modulus of the polyester film used as the polarizer protective film for the polarizing plate A is MD when the polarizer transmission axis direction (that is, the long side direction of the liquid crystal display device) coincides with the MD when the polyester film is formed.
• the elastic modulus of the polyester film coincides with the TD at the time of forming the polyester film
• the elastic modulus of the TD may be adjusted by a conventionally known method of the stretched polyester film. Specifically, when the direction is the stretching direction, the stretching ratio may be set high, and when the direction is the direction orthogonal to the stretching direction, the stretching ratio may be set low.
• the thermal shrinkage rate of the polyester film used as the polarizer protective film for the polarizing plate A is when the transmission axis direction of the polarizer (that is, the long side direction of the liquid crystal display device) matches the MD at the time of forming the polyester film. If the thermal shrinkage rate of MD coincides with the TD at the time of forming the polyester film, the thermal shrinkage rate of TD may be adjusted by a conventionally known method of stretched polyester film.
• the distance between the clip holding the film width direction end and the adjacent clip is expanded to the MD. It can be adjusted by shrinking to MD by reducing the clip interval or the clip interval.
• the film is stretched or shrunk to MD by adjusting the film pulling force. It is possible to adjust by.
• the thermal shrinkage rate changes during the heating and cooling process, so the film pulling force is adjusted to stretch or shrink the MD. It is also possible to make adjustments.
• the gap between the clip holding the film width direction end and the clip located on the opposite side of the width direction is expanded.
• it can be adjusted by stretching to TD or by shrinking to TD by reducing.
• MD or TD it is desirable to adjust the heat shrinkage rate within the target temperature range of the present invention.
• the inclination of the shrink main axis of the polyester film used as the polarizer protective film for the polarizing plate A is a cooling process after stretching and heat treatment by the polyester film tenter.
• it can be adjusted in an off-line process after film formation. Specifically, thermal stress due to shrinkage due to stretching and cooling that could not be completely removed by heat fixation in the cooling process has occurred, and depending on the balance between the two in the film flow direction, it is drawn in upstream or downstream. Retraction occurs, causing a phenomenon that the contraction main axis is tilted.
• the shrinkage force in the film flow direction in the cooling step (the sum of the shrinkage force accompanying stretching and the shrinkage force accompanying cooling) to be uniform.
• a conventionally known method may be used as a method for shrinking or stretching.
• care should be taken because the film shrinks freely in the width direction below the cut / separated temperature range and the thermal shrinkage rate below the temperature range becomes small.
• Shrinkage force The shrinkage force of the polarizer and the polyester film was calculated from the following equation.
• the film thickness, elastic modulus, and heat shrinkage rate are measured values described below.
• Contraction force (N / m) Film thickness (mm) ⁇ elastic modulus (N / mm 2 ) ⁇ heat shrinkage rate (%) ⁇ 100 ⁇ 1000
• the elastic modulus of the polarizer and the polyester film is a dynamic viscoelasticity measuring device manufactured by Seiko Instruments Inc. (DMS6100) according to JIS-K7244 (DMS) after standing for 168 hours in an environment of 25 ° C. and 50 RH%. Evaluation was carried out using. Measure the temperature dependence from 25 ° C to 120 ° C under the conditions of tension mode, drive frequency of 1 Hz, distance between chucks of 5 mm, and heating rate of 2 ° C / min, and calculate the average storage elastic modulus of 30 ° C to 100 ° C. Elastic modulus was used. The elastic modulus in the direction parallel to the long side direction of the liquid crystal display device was measured.
• the heat shrinkage rate in the present invention is defined as a value in a direction parallel to the long side direction of the liquid crystal display device among heat shrinkage rates calculated by the following calculation formula.
• Thermal shrinkage (length before treatment ⁇ length after treatment) / length before treatment ⁇ 100
• the inclination of the contraction main axis is an angle at which the thermal contraction rate measured every 1 ° is maximized, and is defined by a narrow angle from the long side direction or the short side direction. That is, the inclination of the contraction main axis is in the range of 0 to 45 °.
• orientation of the orientation axis of the polyester film is measured by measuring the orientation main axis using a molecular orientation meter (MOA-6004 type molecular orientation meter, manufactured by Oji Scientific Instruments Co., Ltd.). It was defined by a narrow angle from the direction. In other words, the inclination of the alignment main axis is in the range of 0 to 45 °.
• MOA-6004 type molecular orientation meter manufactured by Oji Scientific Instruments Co., Ltd.
• the maximum curl height was set to 5 mm or less as a favorable range. Although curl is a phenomenon that should be expressed by curvature, it is evaluated by height for simplicity. In addition, the curl phenomenon becomes bowl-shaped when the sample size increases with respect to the rigidity of the sample, and the phenomenon that the curvature does not become constant in the film may occur, but all the results of this example are constant. Have confirmed.
• the biaxial refractive index (the refractive index in the slow axis direction: Ny, the fast axis (the refractive index in the direction perpendicular to the slow axis direction): Nx), and the refractive index in the thickness direction ( Nz) was determined by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm). NZ coefficient was calculated
• the biaxial refractive index anisotropy ( ⁇ Nxy) was determined by the following method. Using a molecular orientation meter (MOA-6004 type molecular orientation meter, manufactured by Oji Scientific Instruments Co., Ltd.), determine the slow axis direction of the film, 4 cm so that the slow axis direction is parallel to the long side of the measurement sample.
• MOA-6004 type molecular orientation meter manufactured by Oji Scientific Instruments Co., Ltd.
• a rectangle of ⁇ 2 cm was cut out and used as a measurement sample.
• Abbe refracts the biaxial refractive index (the refractive index in the slow axis direction: Ny, the refractive index in the direction perpendicular to the slow axis direction: Nx), and the refractive index (Nz) in the thickness direction.
• ) of the biaxial refractive index difference was determined as a refractive index anisotropy ( ⁇ Nxy), which was obtained by a refractive index meter (NAGO-4T manufactured by Atago Co., Ltd., measurement wavelength 589 nm).
• the thickness d (nm) of the film was measured using an electric micrometer (manufactured by Fine Reef, Millitron 1245D), and the unit was converted to nm.
• Retardation (Re) was determined from the product ( ⁇ Nxy ⁇ d) of refractive index anisotropy ( ⁇ Nxy) and film thickness d (nm).
• ) and ⁇ Nyz (
• the obtained polyethylene terephthalate resin (A) had an intrinsic viscosity of 0.62 dl / g and contained substantially no inert particles and internally precipitated particles. (Hereafter, abbreviated as PET (A).)
• PET (B) 10 parts by weight of a dried UV absorber (2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), PET (A) containing no particles (inherent viscosity Was 0.62 dl / g) and 90 parts by mass were mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET (B)).
• a transesterification reaction and a polycondensation reaction were carried out by a conventional method, and as a dicarboxylic acid component (based on the whole dicarboxylic acid component) 46 mol% terephthalic acid, 46 mol% isophthalic acid and 8 mol% sodium 5-sulfonatoisophthalate, A water-dispersible sulfonic acid metal group-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol (relative to the entire glycol component) was prepared as a glycol component.
• Example 1 After drying 90 parts by mass of PET (A) resin pellets containing no particles as a raw material for the base film intermediate layer and 10 parts by mass of PET (B) resin pellets containing an ultraviolet absorber at 135 ° C. for 6 hours under reduced pressure (1 Torr) , And supplied to the extruder 2 (for the intermediate layer II layer). Also, the PET (A) was dried by a conventional method and supplied to the extruder 1 (for the outer layer I layer and the outer layer III) and dissolved at 285 ° C. .
• the unstretched film on which this coating layer was formed was guided to a tenter stretching machine, guided to a hot air zone at a temperature of 105 ° C. while being gripped by a clip, and stretched 4.0 times to TD.
• heat treatment was performed at a temperature of 180 ° C. for 30 seconds, and then the film cooled to 100 ° C. was stretched by 1% in MD, and then the clips holding both ends of the film cooled to 60 ° C. were opened.
• a jumbo roll made of a uniaxially oriented PET film having a film thickness of about 80 ⁇ m, and the resulting jumbo roll is equally divided into three slit rolls (L (left side), C ( Center), R (right side)).
• the polarizer protective film 1 was obtained from the slit roll located in R (the central part of the slit roll located in R was used as the polarizer protective film 1).
• a polarizer protective film 1 is attached to one side of a polarizer made of PVA, iodine and boric acid (the contraction force in the absorption axis direction of the polarizer is 5100 N / m) so that the transmission axis of the polarizer and the MD of the film are parallel to each other. I attached. Further, a TAC film (manufactured by Fuji Film Co., Ltd., thickness 80 ⁇ m) was attached to the opposite surface of the polarizer. In this manner, a polarizing plate (polarizing plate A) whose long side direction matches the transmission axis direction of the polarizer and a polarizing plate (polarizing plate B) whose long side direction matches the absorption axis direction of the polarizer were prepared.
• a liquid crystal panel was prepared by bonding through PSA so as to be on the opposite side.
• a liquid crystal display device was produced by incorporating this liquid crystal panel into a housing.
• Example 2 In the production of the polarizer protective film 1 of Example 1, a polarizer protective film 2 was obtained in the same manner as the polarizer protective film 1 except that the film cooled to 100 ° C. was stretched 2.5% in the longitudinal direction. .
• a liquid crystal display device was prepared 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 In the production of the polarizer protective film 1 of Example 1, a polarizer protective film 3 was obtained in the same manner as the polarizer protective film 1 except that the film cooled to 100 ° C. was stretched 4% in the longitudinal direction. In Example 1, the contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, except that the polarizer protective film 1 was replaced by the polarizer protective film 3 Example 1 In the same manner, a liquid crystal display device was produced.
• Example 4 Other than using a blend of 90% by mass of PET (A) and 10% by mass of PBT as a raw material for the I layer, the II layer, and the III layer, and that the film cooled to 100 ° C. was stretched by 4% in the longitudinal direction.
• the contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, and Example 1 was changed except that the polarizer protective film 1 was replaced by the polarizer protective film 4.
• the PBT used was NV5020 (0.52 dl / g) manufactured by Mitsubishi Engineering Plastics.
• Example 5 A polarizer protective film 5 was obtained in the same manner as the polarizer protective film 1 except that the film thickness after stretching was adjusted to 50 ⁇ m by adjusting the rotation speed of the casting roll.
• a liquid crystal display device was prepared 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 ° C. was stretched 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 ° C. was stretched 4% in the longitudinal direction.
• the contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, and Example 1 except that the polarizer protective film 1 was replaced with the polarizer protective film 7.
• a liquid crystal display device was produced.
• Example 8 A polarizer protective film 8 was obtained in the same manner as the polarizer protective film 1 except that the film thickness after stretching was 160 ⁇ m by adjusting the rotational speed of the casting roll.
• 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 ° C. was stretched 2.5% in the width direction. Next, the polarizer having a contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, and the polarizing axis was bonded so that the transmission axis of the polarizer and the TD of the polarizer protective film were parallel.
• a liquid crystal display device was obtained in the same manner as in Example 1 except that the plate A and the polarizing plate B were prepared and that the polarizer protective film 1 was replaced with the polarizer protective film 9.
• Example 10 A polarizer protective film 10 was obtained in the same manner as the polarizer protective film 1 except that 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 A polarizer protective film 11 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched 1.5% in MD.
• 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 in Example 1.
• Example 12 A polarizer protective film 12 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched by 2.5% in MD. The same as Example 1 except that the polarizer having a contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, and the polarizer protective film 1 was changed to the polarizer protective film 12. Thus, a liquid crystal display device was obtained.
• Example 13 Except for using a blend of 90% by mass of PET (A) and 10% by mass of PBT as a raw material for the I layer, the II layer, and the III layer, and making the film cooled to 100 ° C. into 3% stretched in MD.
• a polarizer protective film 13 was obtained in the same manner as the polarizer protective film 10.
• the PBT used was NV5020 (0.52 dl / g) manufactured by Mitsubishi Engineering Plastics.
• Example 14 Polarizer in the same manner as the polarizer protective film 10 except that the film thickness after stretching was adjusted to 50 ⁇ m by adjusting the rotation speed of the casting roll, and the film cooled to 100 ° C. was stretched 1.5% to MD. A protective film 14 was obtained. 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 A polarizer protective film 15 was obtained in the same manner as the polarizer protective film 14 except that the film cooled to 100 ° C. was stretched by 2% in MD.
• a liquid crystal display device was obtained in the same manner as in Example 1 except that the polarizer protective film 1 was replaced with the polarizer protective film 15.
• Example 16 A polarizer protective film 16 was obtained in the same manner as the polarizer protective film 14 except that the film cooled to 100 ° C. was stretched 5% in TD. Next, the polarizing plate A and the polarizing plate B were prepared by bonding so that the transmission axis of the polarizer and the TD direction of the polarizer protective film were parallel, and the polarizer protective film 1 was attached to the polarizer protective film 16. A liquid crystal display device was obtained in the same manner as in Example 1 except that it was replaced with.
• Example 17 A polarizer protective film 20 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched by 2% in MD.
• 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 A polarizer protective film 21 was obtained in the same manner as the polarizer protective film 10 except that the film cooled to 100 ° C. was stretched to 2.5% in MD.
• 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 in Example 1.
• a polarizer protective film 17 was obtained in the same manner as the polarizer protective film 1 except that the clips holding both ends of the film were opened at 95 ° C. in the cooling step after stretching and heat setting. Except that the polarizer protective film 1 was replaced with the polarizer protective film 17, and the polarizing plate A and the polarizing plate B were prepared by bonding so that the transmission axis of the polarizer and the TD of the polarizer protective film were parallel to each other.
• a liquid crystal display device was obtained in the same manner as in Example 1.
• a polarizer protective film 18 was obtained in the same manner as the polarizer protective film 14 except that the film cooled to 100 ° C. was stretched 0.8% in the width direction.
• the polarizer having a contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, and the polarizer protective film 1 was changed to the polarizer protective film 18, and the transmission axis and polarization of the polarizer
• 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 prepared by bonding so that the TD of the child protective film was parallel.
• a polarizer protective film 19 was obtained in the same manner as the polarizer protective film 8 except that the film cooled to 100 ° C. was stretched 0.3% in the width direction.
• the polarizer having a contraction force in the absorption axis direction was changed from a polarizer of 5100 N / m to a polarizer of 11200 N / m, and the polarizer protective film 1 was changed to the polarizer protective film 19, and the transmission axis and polarization of the polarizer
• 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 prepared by bonding so that the TD of the child protective film was parallel.
• 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 heat-treated for 30 minutes using a gear oven set at 100 ° C.
• the liquid crystal panel was observed after cooling for 10 minutes in an environment set at 50 ° C. and 50 RH%, no curl was observed in Examples 1 to 16, but curl was observed in Comparative Examples 1 to 3. .
• Table 1 shows the measurement results of each example.

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