WO2013100042A1 - Dispositif d'affichage à cristaux liquides - Google Patents

Dispositif d'affichage à cristaux liquides Download PDF

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Publication number
WO2013100042A1
WO2013100042A1 PCT/JP2012/083849 JP2012083849W WO2013100042A1 WO 2013100042 A1 WO2013100042 A1 WO 2013100042A1 JP 2012083849 W JP2012083849 W JP 2012083849W WO 2013100042 A1 WO2013100042 A1 WO 2013100042A1
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Prior art keywords
film
liquid crystal
crystal display
display device
retardation
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PCT/JP2012/083849
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English (en)
Japanese (ja)
Inventor
村田　浩一
章文 安井
松田　明
佐々木　靖
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東洋紡株式会社
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Application filed by 東洋紡株式会社 filed Critical 東洋紡株式会社
Priority to JP2013551787A priority Critical patent/JP5979156B2/ja
Publication of WO2013100042A1 publication Critical patent/WO2013100042A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements
    • G02B1/105—
    • 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
    • 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
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/50—Protective arrangements

Definitions

  • the present invention relates to a liquid crystal display device. Specifically, the present invention relates to a liquid crystal display device that has favorable visibility and is suitable for thinning.
  • a polarizing plate used in a liquid crystal display usually has a configuration in which a polarizer in which iodine is dyed on polyvinyl alcohol (PVA) or the like is sandwiched between two polarizer protective films.
  • a triacetyl cellulose (TAC) film is usually used.
  • TAC film used as the protective film is reduced for this purpose, sufficient mechanical strength cannot be obtained, and the moisture permeability becomes high and the polarizer is likely to deteriorate. Further, TAC films are very expensive, and there is a strong demand for inexpensive alternative materials.
  • Patent Documents 1 to 3 it has been proposed to use a polyester film instead of the TAC film so that the polarizing plate can be made thin so that high durability can be maintained even if the thickness is small as a polarizer protective film.
  • the polyester film is superior to the TAC film in durability, but unlike the TAC film, it has birefringence. Therefore, when it is used as a polarizer protective film, there is a problem that the image quality is deteriorated due to optical distortion. That is, since the polyester film having birefringence has a predetermined optical anisotropy (retardation), when used as a polarizer protective film, a rainbow-like color spot is generated when observed from an oblique direction, and the image quality is deteriorated. . Therefore, Patent Documents 1 to 3 take measures to reduce retardation by using a copolyester as the polyester. However, even in that case, the reduction of iridescent color spots was insufficient.
  • the present invention has been made to solve such a problem, and an object of the present invention is to cope with the thinning of the liquid crystal display device (that is, the polarizer protective film has sufficient mechanical strength), and the rainbow. It is to provide a liquid crystal display device in which the visibility is not deteriorated due to the colored spots.
  • a liquid crystal display device having a backlight light source and a liquid crystal cell disposed between two polarizing plates,
  • the backlight source is a white light source having a continuous emission spectrum;
  • the polarizing plate is composed of a polarizer protective film laminated on both sides of the polarizer, At least one of the polarizer protective films of the polarizing plate disposed on the outgoing light side with respect to the liquid crystal cell is a polyester film having a retardation of 3000 to 30,000 nm, and the polarized light disposed on the incident light side with respect to the liquid crystal cell.
  • a liquid crystal display device wherein at least one of the polarizer protective films of the plate is a cycloolefin resin film, a polyolefin resin film, or a (meth) acrylic resin film.
  • the liquid crystal display device according to any one of (1) to (4), wherein the white light source having the continuous emission spectrum is a white light emitting diode.
  • the polyester film has an easy adhesion layer.
  • the polyester film comprises at least three layers, contains an ultraviolet absorber in a layer other than the outermost layer, and has a light transmittance of 380 nm of 20% or less.
  • the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side with respect to the liquid crystal cell is an oriented polyester film having a retardation of 3000 to 30000 nm,
  • One or more layers selected from the group consisting of a hard cord layer, an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection antiglare layer are provided on the emission light side of the oriented polyester film.
  • the liquid crystal display device according to any one of (3) to (8), which is a laminated film in which an adhesion improving layer containing a polyolefin resin containing a polar group is laminated on at least one surface of the polypropylene film.
  • the adhesion improving layer is mainly made of a polypropylene resin containing a polar group.
  • the spectrum of transmitted light is a spectrum that approximates the light source at any observation angle, it is possible to ensure good visibility without rainbow-like color spots, and to reduce the thickness. Correspondence is possible.
  • the liquid crystal panel includes a rear module, a liquid crystal cell, and a front module in order from the backlight source side toward the image display side (viewing side or emission light side).
  • the rear module and the front module are generally composed of a transparent substrate, a transparent conductive film formed on the liquid crystal cell side surface, and a polarizing plate disposed on the opposite side.
  • the polarizing plate is disposed on the backlight source side in the rear module, and is disposed on the image display side (viewing side or emission light side) in the front module.
  • the liquid crystal display device of the present invention includes at least a backlight light source and a liquid crystal cell disposed between two polarizing plates. Moreover, you may have suitably other structures other than these, for example, a color filter, a lens film, a diffusion sheet, an antireflection film etc. suitably.
  • the configuration of the backlight light source may be an edge light method using a light guide plate, a reflection plate, or the like, or a direct type, but in the present invention, as a backlight light source of a liquid crystal display device, It is preferable to use a white light source having a continuous and broad emission spectrum.
  • the continuous and broad emission spectrum means an emission spectrum in which there is no wavelength at which the light intensity becomes zero in the wavelength region of at least 450 nm to 650 nm, preferably in the visible light region.
  • Examples of such a white light source having a continuous and broad emission spectrum include a white light emitting diode (white LED).
  • a white LED includes a phosphor type, that is, an element that emits white light by combining a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor and a phosphor, or an organic light emitting diode (Organic light-emitting). diode: OLED) and the like.
  • the phosphor include yttrium / aluminum / garnet yellow phosphor and terbium / aluminum / garnet yellow phosphor.
  • white light-emitting diodes that consist of a light-emitting element that combines a blue light-emitting diode using a compound semiconductor and a yttrium / aluminum / garnet-based yellow phosphor have a continuous and broad emission spectrum and light emission efficiency. Therefore, it is suitable as the backlight light source of the present invention.
  • the present invention is effective for energy saving by using a white LED or the like with lower power consumption as a light source.
  • the polarizing plate has a configuration in which both sides of a polarizer in which PVA or the like is dyed with iodine are sandwiched between two polarizer protective films.
  • the polarizing plate constituting the polarizing plate disposed on the emission light side.
  • a polyester film having a specific range of retardation is used as at least one of the child protective films.
  • a cycloolefin resin film, a polyolefin resin film, or a (meth) acrylic resin film is used as at least one of the polarizer protective films constituting the polarizing plate disposed on the incident light side.
  • the mechanism by which the occurrence of rainbow-like color spots is suppressed by the above embodiment is considered as follows.
  • a polyester film having birefringence is disposed on one side of the polarizer, the linearly polarized light emitted from the polarizer is disturbed when passing through the polyester film.
  • the transmitted light shows an interference color peculiar to retardation which is the product of birefringence and thickness of the polyester film. Therefore, if a discontinuous emission spectrum such as a cold cathode tube or a hot cathode tube is used as the light source, the transmitted light intensity varies depending on the wavelength, and a rainbow-like color spot is generated (see: 15th Micro Optical Conference Proceedings, No. 1). 30-31).
  • white light emitting diodes usually have a continuous and broad emission spectrum in a wavelength region of at least 450 nm to 650 nm, preferably in the visible light region.
  • the interference color spectrum of the transmitted light that has passed through the birefringent body has an envelope shape, it is possible to obtain a spectrum similar to the emission spectrum of the light source by controlling the retardation of the polyester film. In this way, by making the emission spectrum of the light source similar to the envelope shape of the interference color spectrum by the transmitted light that has passed through the birefringent body, visibility is not noticeable without rainbow-like color spots. It is thought to improve.
  • a white light emitting diode having a broad emission spectrum is used as a light source, so that the envelope shape of the spectrum of transmitted light can be approximated to the emission spectrum of the light source with only a relatively simple configuration, and as a result, liquid crystal It is thought that it is possible to suppress rainbow spots on the display.
  • the polyester film having the retardation in the specific range is preferably used as a polarizer protective film on the emission light side of the polarizing plate disposed on the emission light side with respect to the liquid crystal cell.
  • a polyester film is used for the polarizer protective film on the incident light side of the polarizing plate arranged on the emission light side with respect to the liquid crystal cell, the polarization characteristics of the liquid crystal cell may be changed.
  • the polarizer protective film on the incident light side of the polarizing plate disposed on the incident light side with respect to the liquid crystal cell is a cycloolefin resin film, a polyolefin resin film, or a (meth) acrylic resin film. is there.
  • a film made of the same polymer material may be used for the other polarizer protective film of the polarizing plate on the incident light side, but as represented by a TAC film, an acrylic film, a norbornene-based film, or the like. It is preferable to use a film having no birefringence.
  • a polyester film having a retardation in the above specific range as a polarizer protective film for the polarizing plate arranged on the incident light side as well as the emission light side with respect to the liquid crystal cell. Since thin rainbow spots may occur in some cases, it is preferable to use a cycloolefin resin film, a polyolefin resin film, or a (meth) acrylic resin film. As a result, the above rainbow spots are eliminated.
  • a polypropylene film is more effective in reducing the thickness of the liquid crystal display device because it is excellent in moisture resistance, dimensional stability, and mechanical strength.
  • the polarizing plate used in the present invention it is also preferable to apply various functional layers such as a hard coat on the surface for the purpose of preventing reflection, suppressing glare, and suppressing scratches.
  • various functional layers such as a hard coat on the surface for the purpose of preventing reflection, suppressing glare, and suppressing scratches.
  • These layers are preferably provided on the surface of the polyester film via an easy adhesion layer or directly.
  • an oriented polyester film is used for the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side with respect to the liquid crystal cell, and a hard cord layer and an antiglare layer are formed on the exit light side of the oriented polyester film. It is preferable to have at least one layer selected from the group consisting of an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection antiglare layer. This is because the polarizer protective film is in a position closest to outside light.
  • rainbow-like color spots are reduced by laminating a layer selected from the group consisting of a hard coat layer, an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection antiglare layer. Can also be expected.
  • the oriented polyester film used for the polarizer protective film preferably has a retardation of 3000 to 30000 nm.
  • the retardation is less than 3000 nm, when used as a polarizer protective film, it exhibits a strong interference color when observed from an oblique direction, so the envelope shape is different from the emission spectrum of the light source, and good visibility cannot be ensured.
  • the lower limit of the preferable retardation is 4500 nm or more, next preferably 5000 nm or more, more preferably 6000 nm or more, still more preferably 8000 nm or more, and still more preferably 10,000 nm or more.
  • the upper limit of retardation is 30000 nm. Even if a polyester film having a retardation of more than that is used, it is not only possible to substantially improve the visibility, but also because the film thickness becomes considerably thick and the handling property as an industrial material is reduced, it is preferable. Absent.
  • the retardation can be obtained by measuring the refractive index and thickness in the biaxial direction. Alternatively, it can be obtained using a commercially available automatic birefringence measuring device such as RETS100 (manufactured by Otsuka Electronics Co., Ltd.) or KOBRA-21ADH (Oji Scientific Instruments). In this document, retardation means in-plane retardation.
  • the oriented polyester film used in the present invention can be obtained by condensing dicarboxylic acid and diol.
  • dicarboxylic acid component that can be used for producing the polyester film include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1 , 5-Naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid , Hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succin
  • 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 film may each be used alone or in combination of two or more.
  • Specific polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and preferably polyethylene terephthalate and polyethylene naphthalate. These resins are excellent in transparency and excellent in thermal and mechanical properties, and the retardation can be easily controlled by stretching.
  • polyethylene terephthalate is the most suitable material because it has a large intrinsic birefringence and a large retardation can be obtained relatively easily even if the film is thin.
  • the polyester film preferably has a light transmittance of 20% or less at a wavelength of 380 nm.
  • the light transmittance at 380 nm is more preferably 15% or less, further preferably 10% or less, and particularly preferably 5% or less. If the light transmittance is 20% or less, the optical functional dye can be prevented from being deteriorated by ultraviolet rays.
  • the transmittance in the present invention is measured by a method perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500 type).
  • Setting the transmittance of the oriented polyester film at a wavelength of 380 nm to 20% or less means adding an ultraviolet absorber to the film, applying a coating solution containing the ultraviolet absorber to the film surface, and the type of the ultraviolet absorber. It can be achieved by appropriately adjusting the concentration and the thickness of the film.
  • the ultraviolet absorber used in the present invention is a known substance. Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, and an organic ultraviolet absorber is preferable from the viewpoint of transparency.
  • organic ultraviolet absorber examples include benzotriazole, benzophenone, cyclic imino ester, and the like, and combinations thereof, but are not particularly limited as long as the absorbance is within the range defined by the present invention. From the viewpoint of durability, benzotoazole and cyclic imino ester are particularly preferable. When two or more kinds of ultraviolet absorbers are used in combination, ultraviolet rays having different wavelengths can be absorbed simultaneously, so that the ultraviolet absorption effect can be further improved.
  • benzophenone ultraviolet absorber examples include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2 ′ -hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2 ′ -hydroxy-5 ′-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2,2 ′ -Dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (2′-Hydroxy-3′-tert-butyl-5′-methylphenyl) Nyl) -5-chlorobenzotri
  • cyclic imino ester UV absorbers examples include 2,2 ′-(1 , 4-phenylene) bis (4H-3,1-benzoxazinon-4-one), 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazine-4-one ON, 2-phenyl-3,1-benzoxazin-4-one, etc. However, it is not particularly limited thereto.
  • additives include inorganic particles, heat resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light proofing agents, flame retardants, thermal stabilizers, antioxidants, and antigelling agents. And surfactants.
  • a polyester film does not contain a particle
  • “Substantially free of particles” means, for example, in the case of inorganic particles, when the inorganic element is quantified by fluorescent X-ray analysis, the content is 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less. Means quantity.
  • the polyester film can be subjected to corona treatment, coating treatment, flame treatment, etc. in order to improve the adhesion to the polarizer.
  • an easy-adhesion layer mainly composed of at least one of a polyester resin, a polyurethane resin or a polyacrylic resin on at least one side of the polyester film.
  • the “main component” refers to a component that is 50% by mass or more of the solid components constituting the easy-adhesion layer.
  • the coating solution used for forming the easy-adhesion layer is preferably an aqueous coating solution containing at least one of a water-soluble or water-dispersible copolymerized polyester resin, an acrylic resin, and a polyurethane resin.
  • coating solutions include water-soluble or water-dispersible co-polymers disclosed in Japanese Patent No. 3567927, Japanese Patent No. 3589232, Japanese Patent No. 3589233, Japanese Patent No. 3900191, and Japanese Patent No. 4150982.
  • coating solutions include a polymerized polyester resin solution, an acrylic resin solution, and a polyurethane resin solution.
  • the easy-adhesion layer can be obtained by applying the coating solution on one or both sides of an unstretched or longitudinally uniaxially stretched film, drying at 100 to 150 ° C., and further stretching in the transverse direction.
  • the final coating amount of the easy adhesion layer is preferably controlled to 0.05 to 0.20 g / m 2 . If the coating amount is less than 0.05 g / m 2 , the adhesion with the resulting polarizer may be insufficient. On the other hand, when the coating amount exceeds 0.20 g / m 2 , blocking resistance may be lowered.
  • the application quantity of an easily bonding layer on both surfaces may be the same or different, and can be independently set within the above range.
  • particles to the easy-adhesion layer in order to impart slipperiness. It is preferable to use particles having an average particle size of 2 ⁇ m or less. When the average particle diameter of the particles exceeds 2 ⁇ m, the particles easily fall off from the easy adhesion layer.
  • particles to be included in the easy adhesion layer for example, titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride,
  • examples include inorganic particles such as calcium fluoride, and organic polymer particles such as styrene, acrylic, melamine, benzoguanamine, and silicone. These may be added alone to the easy-adhesion layer, or may be added in combination of two or more.
  • a known method can be used as a method for applying the coating solution.
  • reverse roll coating method gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, etc.
  • spray coating method air knife coating method, wire bar coating method, pipe doctor method, etc.
  • wire bar coating method wire bar coating method
  • pipe doctor method etc.
  • the average particle size of the above particles is measured by the following method. Take a picture of the particles with a scanning electron microscope (SEM) and take the largest diameter of 300-500 particles (between the two most distant points) at a magnification such that the size of one smallest particle is 2-5 mm. Distance) is measured, and the average value is taken as the average particle diameter.
  • SEM scanning electron microscope
  • the oriented polyester film can be manufactured according to a general polyester film manufacturing method.
  • 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.
  • the oriented polyester film may be either a uniaxially stretched film or a biaxially stretched film, but when the biaxially stretched film is used as a polarizer protective film, it is rainbow-like even when observed from directly above the film surface. However, it should be noted that rainbow-like color spots may be observed when observed from an oblique direction.
  • This phenomenon is that a biaxially stretched film is composed of refractive index ellipsoids having different refractive indexes in the running direction, width direction, and thickness direction, and the retardation becomes zero depending on the light transmission direction inside the film (refractive index ellipse). This is because there is a direction in which the body appears to be a perfect circle. Therefore, when the liquid crystal display screen is observed from a specific oblique direction, a point where the retardation becomes zero may be generated, and a rainbow-like color spot is generated concentrically around that point.
  • the angle ⁇ increases as the birefringence in the film increases, and the rainbow-like color increases. Spots are difficult to see.
  • the biaxially stretched film tends to reduce the angle ⁇ , and therefore the uniaxially stretched film is more preferable because rainbow-like color spots are less visible.
  • the present invention has biaxiality (biaxial symmetry) in a range that does not substantially cause rainbow-like color spots or a range that does not cause rainbow-like color spots in a viewing angle range required for a liquid crystal display screen. It is preferable.
  • the present inventors have made a ratio between the retardation of the oriented polyester film (in-plane retardation) and the retardation in the thickness direction (Rth).
  • Thickness direction retardation means an average of retardation obtained by multiplying two birefringences ⁇ Nxz and ⁇ Nyz by film thickness d when the film is viewed from the cross section in the thickness direction. The smaller the difference between the in-plane retardation and the thickness direction retardation, the more isotropic the birefringence action due to the observation angle, and the smaller the change in retardation due to the observation angle. Therefore, it is considered that rainbow-like color spots due to the observation angle are less likely to occur.
  • the ratio of the retardation of the oriented polyester film to the retardation in the thickness direction (Re / Rth) is preferably 0.2 or more, more preferably 0.5 or more, and further preferably 0.6 or more. As the ratio of the retardation to the retardation in the thickness direction (Re / Rth) is larger, the birefringence action is more isotropic, and the occurrence of iridescent color spots due to the observation angle is less likely to occur. In a complete uniaxial (uniaxial symmetry) film, the ratio of the retardation to the retardation in the thickness direction (Re / Rth) is 2. However, as described above, the mechanical strength in the direction orthogonal to the orientation direction is significantly lowered as the film approaches a complete uniaxial (uniaxial symmetry) film.
  • the ratio of the retardation of the oriented polyester film to the retardation in the thickness direction is preferably 1.2 or less, more preferably D or 1 or less.
  • the ratio of retardation to thickness direction retardation (Re / Rth) does not have to be 2, and 1.2 or less is sufficient. Further, even when the ratio is 1.0 or less, it is possible to satisfy the viewing angle characteristics (about 180 ° left and right and about 120 ° up and down) required for the liquid crystal display device.
  • the longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 130 ° C, particularly preferably 90 to 120 ° C.
  • the longitudinal draw ratio is preferably 1.0 to 3.5 times, particularly preferably 1.0 to 3.0 times.
  • the transverse draw ratio is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times.
  • the ratio of the longitudinal draw ratio and the transverse draw ratio In order to control the retardation within the above range, it is preferable to control the ratio of the longitudinal draw ratio and the transverse draw ratio. If the difference between the vertical and horizontal draw ratios is too small, it is difficult to increase the retardation, which is not preferable.
  • setting the stretching temperature low is a preferable measure for increasing the retardation.
  • the treatment temperature is preferably from 100 to 250 ° C., particularly preferably from 180 to 245 ° C.
  • the thickness unevenness of the polyester film is small. Since the stretching temperature and the stretching ratio greatly affect the thickness variation of the film, it is necessary to optimize the film forming conditions from the viewpoint of the thickness variation. In particular, when the longitudinal draw ratio is lowered to increase the retardation, the value of the longitudinal thickness unevenness may be increased. Since there is a region in which the value of the vertical thickness unevenness becomes very high in a specific range of the draw ratio, it is desirable to set the film forming conditions outside this range.
  • the thickness unevenness of the polyester film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. Is particularly preferred.
  • the retardation of the film can be controlled within a specific range by appropriately setting the stretching ratio, the stretching temperature, and the thickness of the film. For example, it becomes easier to obtain a higher retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is higher, the stretching temperature is lower, and the film is thicker. On the contrary, it becomes easier to obtain a lower retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is lower, the stretching temperature is higher, and the film thickness is thinner. Moreover, the higher the stretching temperature and the lower the total stretching ratio, the easier it is to obtain a film having a lower ratio of retardation to thickness direction (Re / Rth).
  • the lower the stretching temperature and the higher the total stretching ratio the easier it is to obtain a film with a higher ratio of retardation to thickness direction retardation (Re / Rth).
  • the final film forming conditions must be set in consideration of the physical properties necessary for processing in addition to the retardation control.
  • the thickness of the polyester film is arbitrary, but is preferably in the range of 15 to 300 ⁇ m, more preferably in the range of 15 to 200 ⁇ m. In principle, it is possible to obtain a retardation of 3000 nm or more even with a film having a thickness of less than 15 ⁇ m. However, in that case, the anisotropy of the mechanical properties of the film becomes remarkable, and it becomes easy to cause tearing, tearing, etc., and the practicality as an industrial material is remarkably lowered. A particularly preferable lower limit of the thickness is 25 ⁇ m. On the other hand, if the upper limit of the thickness of the polarizer protective film exceeds 300 ⁇ m, the thickness of the polarizing plate becomes too thick, which is not preferable.
  • the upper limit of the thickness is preferably 200 ⁇ m.
  • a particularly preferable upper limit of the thickness is 100 ⁇ m, which is about the same as a general TAC film.
  • Polyethylene terephthalate is preferable as the polyester used as the film substrate in order to control the retardation within the range of the present invention even in the above thickness range.
  • a method of blending the ultraviolet absorber into the polyester film a known method can be used in combination.
  • a master batch is prepared by blending the dried ultraviolet absorber and the polymer raw material in advance using a kneading extruder. It can be prepared and blended by, for example, a method of mixing a predetermined master batch and a polymer raw material during film formation.
  • the addition weight of the ultraviolet absorber added to the film is preferably 0.3 to 1.5%, more preferably 0.4 to 1.0%.
  • the concentration of the UV absorber in the master batch is preferably 5 to 30% by mass in order to uniformly disperse the UV absorber and mix it economically.
  • a condition for producing the master batch it is preferable to use a kneading extruder and to extrude at a temperature not lower than the melting point of the polyester raw material and not higher than 290 ° C. for 1 to 15 minutes. Above 290 ° C, the weight loss of the UV absorber is large, and the viscosity of the master batch is greatly reduced.
  • the residence time is 1 minute or less, uniform mixing of the ultraviolet absorber becomes difficult.
  • a stabilizer, a color tone adjusting agent, and an antistatic agent may be added.
  • the oriented polyester film has a multilayer structure of at least three layers, and an ultraviolet absorber is added to the intermediate layer of the film.
  • a film having a three-layer structure containing an ultraviolet absorber in the intermediate layer can be specifically produced as follows. Polyester pellets alone for the outer layer, master batches containing UV absorbers for the intermediate layer and polyester pellets are mixed at a predetermined ratio, dried, and then supplied to a known melt laminating extruder, which is slit-shaped. Extruded into a sheet form from a die and cooled and solidified on a casting roll to make an unstretched film.
  • a three-layer manifold or a merging block for example, a merging block having a square merging portion
  • a film layer constituting both outer layers and a film layer constituting an intermediate layer are laminated
  • An unstretched film is formed by extruding a three-layer sheet from the die and cooling with a casting roll.
  • the filter particle size (initial filtration efficiency 95%) of the filter medium used for high-precision filtration of the molten resin is preferably 15 ⁇ m or less. When the filter particle size of the filter medium exceeds 15 ⁇ m, removal of foreign matters of 20 ⁇ m or more tends to be insufficient.
  • Cycloolefin resin film, polyolefin resin film or (meth) acrylic resin film A cycloolefin resin film, a polyolefin resin film, or a (meth) acrylic resin film is used as at least one of the polarizer protective films constituting the polarizing plate disposed on the incident light side.
  • the cycloolefin resin film is a film made of a cycloolefin resin.
  • the cycloolefin resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin.
  • a cyclic olefin ring-opening (co) polymer a cyclic olefin addition polymer, a cyclic olefin and an ⁇ -olefin such as ethylene and propylene (and typically a random copolymer), And the graft polymer which modified these by unsaturated carboxylic acid or its derivative (s), and those hydrides, etc. are mentioned.
  • Various products such as norbornene resins are commercially available as cycloolefin resins.
  • trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL”, trade name “Essina” manufactured by Sekisui Chemical Co., Ltd.
  • the polyolefin resin film is a film made of a polyolefin resin.
  • Polyolefin resins include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene- ⁇ olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl. Examples thereof include one or a mixture of two or more selected from an acrylate copolymer, an ethylene-n-butyl acrylate copolymer, polypropylene (homopolymer, random copolymer, or block copolymer), and the like. Among these, a polypropylene film is more effective in reducing the thickness of a liquid crystal display device because it is excellent in moisture resistance, dimensional stability, and mechanical strength.
  • (Meth) acrylic resin film is a film made of (meth) acrylic resin.
  • the (meth) acrylic resin include (meth) acrylic resins described in JP-A 2010-055062, [0017] to [0043].
  • a (meth) acrylic resin is a methacrylic resin and an acrylic resin.
  • the (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher.
  • Tg glass transition temperature
  • the upper limit of Tg of the said (meth) acrylic-type resin is not specifically limited, From viewpoints of a moldability etc., Preferably it is 170 degrees C or less.
  • any appropriate (meth) acrylic resin can be adopted as the (meth) acrylic resin.
  • poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, And methyl methacrylate- (meth) acrylate norbornyl copolymer).
  • Preferable examples include C1-6 alkyl poly (meth) acrylates such as poly (meth) acrylate methyl. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).
  • the (meth) acrylic resin examples include, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and a (meth) acrylic resin having a ring structure in the molecule described in JP-A-2004-70296. Resins, high Tg (meth) acrylic resin systems obtained by intramolecular cross-linking and intramolecular cyclization reactions.
  • (Meth) acrylic resin having a lactone ring structure can also be used as the (meth) acrylic resin. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.
  • Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. And (meth) acrylic resins having a lactone ring structure described in JP-A-146084.
  • the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.
  • the content of the additive in the film is preferably 0 to 50% by weight, more preferably 1 to 50% by weight, still more preferably 2 to 40% by weight, and particularly preferably 3 to 30% by weight. If the content of the additive in the film is greater than 50% by weight, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited. These films may be stretched.
  • the thickness of the cycloolefin-based resin film, polyolefin-based resin film or (meth) acrylic resin film can be set as appropriate, but is generally about 1 to 500 ⁇ m from the viewpoint of workability such as strength and handling, and thin layer properties. is there.
  • the thickness is preferably 5 to 500 ⁇ m, more preferably 10 to 300 ⁇ m, still more preferably 20 to 200 ⁇ m.
  • the cycloolefin resin film, polyolefin resin film or (meth) acrylic resin film is preferably transparent and has a retardation of 200 nm or less. More preferably, it is 150 nm or less, More preferably, it is 100 nm or less. Particularly preferred retardation is 50 nm or less. If the retardation exceeds 200 nm, rainbow spots may be observed, which is not preferable. Since the retardation is preferably small from the viewpoint of rainbow spot observation, the lower limit is 0 or more.
  • At least one of the polarizer protective films of the polarizing plate disposed on the incident light side with respect to the liquid crystal cell is preferably a polypropylene film.
  • a polypropylene film is effective in reducing the thickness of a liquid crystal display device because it is excellent in moisture resistance, dimensional stability, mechanical strength, workability and operability.
  • the polypropylene film used in the present invention is made of a polypropylene resin.
  • the polypropylene-based resin is a resin mainly composed of polypropylene units and is generally crystalline.
  • a copolymer of a propylene unit and a comonomer copolymerizable therewith may be a coalescence.
  • the polypropylene film used in the present invention is preferably transparent and has a retardation of 200 nm or less. More preferably, it is 150 nm or less, More preferably, it is 100 nm or less. Particularly preferred retardation is 50 nm or less. If the retardation exceeds 200 nm, rainbow spots may be observed, which is not preferable.
  • the retardation is preferably small from the viewpoint of suppressing irises, and the lower limit is not particularly defined, but is practically 1 nm or more.
  • comonomer copolymerized with propylene a comonomer known in the technical field can be appropriately selected and used.
  • ethylene or an ⁇ -olefin having 4 to 20 carbon atoms can be used.
  • Specific examples of the ⁇ -olefin in this case include the following.
  • the copolymer may be a random copolymer or a block copolymer.
  • the propylene resin is, for example, a solution polymerization method using an inert solvent typified by a hydrocarbon compound such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, or a liquid monomer as a solvent. It can be produced by a bulk polymerization method or a gas phase polymerization method in which a gaseous monomer is polymerized as it is. Polymerization by these methods may be carried out batchwise or continuously.
  • an inert solvent typified by a hydrocarbon compound such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, or a liquid monomer as a solvent. It can be produced by a bulk polymerization method or a
  • the stereoregularity of the propylene-based resin may be any of isotactic, syndiotactic and atactic.
  • the propylene-based resin used in the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JISK7210, 0.1 to 200 g / 10 minutes, particularly 0.5 to 50 g. It is preferably in the range of / 10 minutes.
  • the propylene-based resin may be blended with known additives as long as the effects of the present invention are not impaired.
  • the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent.
  • Antioxidants include, for example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine light stabilizers, etc., and, for example, a phenolic antioxidant mechanism in one molecule A composite antioxidant having a unit having a phosphorus-based antioxidant mechanism can also be used.
  • the UV absorber include UV absorbers such as 2-sodium hydroxybenzophenone and hydroxyphenylbenzotriazole, and benzoate UV blockers.
  • the antistatic agent may be polymer type, oligomer type, or monomer type.
  • the lubricant include higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and salts thereof.
  • the nucleating agent include sorbitol nucleating agents, organophosphate nucleating agents, and polymer nucleating agents such as polyvinylcycloalkane.
  • fine particles having a spherical shape or a shape close thereto can be used regardless of inorganic type or organic type. A plurality of these additives may be used in combination.
  • the polypropylene film preferably has an adhesion improving layer containing a polyolefin resin containing a polar group on at least one surface thereof from the viewpoint of improving the adhesion with a polarizer or a polyvinyl alcohol-based adhesive.
  • the polyolefin resin containing a polar group contains olefin such as ethylene, propylene, butene, hexene, octene, methylpentene, and cyclic olefin in its skeleton.
  • the polyolefin resin containing a polar group is preferably a polypropylene resin containing a propylene monomer as a skeleton from the viewpoint of adhesiveness with the propylene resin.
  • the polyolefin resin may be a homopolymer using one kind of the above monomers or a copolymer using two or more kinds of monomers.
  • the polyolefin resin containing a polar group preferably contains at least one polar group.
  • polar groups include carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups, glycidyl groups, isocyanate groups, amino groups, imide groups, oxazoline groups, ester groups, ether groups, carboxylic acid metal bases, sulfonic acid metal bases, Examples thereof include phosphonic acid metal bases, tertiary amine bases, and quaternary amine bases.
  • the polyolefin resin may contain only one kind of polar group or two or more kinds. Among these polar groups, the polyolefin resin preferably contains a carboxylic acid group.
  • the polyolefin resin containing a polar group may be in a state where the polar group is directly introduced into the polymer chain of the polyolefin resin, or it is introduced into another resin, added and mixed.
  • the polyolefin resin can also be used after being modified by reacting a polar group (for example, a carboxylic acid group or a hydroxyl group) introduced into the terminal or inside of the molecular chain with a compound capable of reacting with these.
  • a carboxylic acid group can be introduced into the olefin resin by acid modification with maleic anhydride or the like.
  • the amount of acid modification is preferably 0.1 wt% or more.
  • the amount of acid modification is more preferably 0.2 wt% or more, and still more preferably 0.3 wt% or more.
  • the amount of acid modification is preferably 5 wt% or less.
  • the acid modification amount can be measured according to a measurement method shown in Examples described later.
  • the polar group-containing polyolefin resin contained in the adhesion improving layer may be a single kind or a composition in which two or more kinds are mixed. Further, the adhesion improving layer may further contain a polyolefin resin not containing a polar group or other types of resins.
  • the polyolefin resin containing a polar group is preferably contained in an amount of 10% by mass or more, more preferably 30% by mass or more, based on the total solid content of the adhesion improving layer.
  • the adhesion improving layer may be provided on one side of the polypropylene film or on both sides.
  • the thickness of the polypropylene film including the adhesion improving layer is not particularly limited, but is preferably 2 to 200 ⁇ m.
  • the thickness of the adhesion improving layer provided on one side of the polypropylene film is not particularly limited, but is preferably 1 to 100 ⁇ m.
  • the ratio of the thickness of the polypropylene film and the adhesion improving layer (polypropylene film / adhesion improving layer) is preferably 100/1 to 3/1, and more preferably 20/1 to 4/1. By doing in this way, the balance of the brightness fall and the adhesive improvement effect can be improved.
  • the method for producing a polypropylene film is not particularly limited as long as it satisfies the above-mentioned optical characteristics, but a method of forming a film by melt extrusion molding is preferable from the viewpoint of economy.
  • the film forming method by the melt extrusion method is not particularly limited, and may be, for example, either a T-die method or an inflation method. Moreover, although an unstretched film may be sufficient and a extending
  • a resin melted by an extruder is extruded from a die into a sheet shape, and the sheet is adhered to a cooling roll to be cooled and solidified to form a film.
  • the method of closely contacting the cooling roll is not particularly limited.
  • the resin melted by an extruder is extruded from a die into a sheet shape, and the sheet is pressed by a pressing roll, the pressing method by gas pressure and / or the suction method, and It is preferable that the film is formed by close contact with an electrostatic contact method and solidify by cooling. By this method, a film having high transparency and small retardation can be obtained.
  • the method for bringing the aforementioned sheet into close contact with the cooling roll and cooling and solidifying is not particularly limited.
  • a pressing method by gas pressure for example, a method such as a so-called air knife method of pressing by a gas pressure such as air, a vacuum chamber method of sucking and adhering with a decompression nozzle, an electrostatic adhesion method of adhering by electrostatic force, etc.
  • the method may be used alone or a plurality of methods may be used in combination. The latter is a preferred embodiment in that it can increase the thickness accuracy of the film obtained.
  • the polypropylene film may have a two-layer structure or a multilayer structure of three or more layers.
  • An adhesion improving layer may be provided on one side or both sides of the polypropylene film.
  • the multilayer structure it may be produced by a multilayer coextrusion method, or may be carried out by an extrusion lamination method or a dry lamination method.
  • the film may be subjected to surface activation treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, ozone treatment, etc. within the range not impairing the object of the present invention.
  • surface activation treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, ozone treatment, etc.
  • the thickness of the polypropylene film is preferably 5 to 500 ⁇ m, more preferably 10 to 300 ⁇ m, and still more preferably 20 to 200 ⁇ m.
  • the heat shrinkage rate at 120 ° C. for 30 minutes in the width direction and the longitudinal direction of the polypropylene film is preferably 1.0% or less, more preferably 0.8% or less.
  • the value of the thermal shrinkage rate exceeds 1.0% the film is greatly shrunk when heat processing is performed in a post-processing step or when it is used at a high temperature for a long time as a member such as a display application. This is not preferable because distortion of optical characteristics occurs, flatness deteriorates, wrinkles, curls, and the like occur.
  • the polypropylene film preferably has a retardation variation of 100 nm / m or less in the film width direction. If the variation in retardation is 100 nm / m or less, retardation is stable in the plane of the film even in a wide film corresponding to a large screen, and the occurrence of color spots can be suppressed.
  • the variation in retardation in the film width direction is more preferably 80 nm / m or less, further preferably 50 nm / m or less, and particularly preferably 20 nm / m or less.
  • the biaxial refractive index anisotropy ( ⁇ Nxy) of the polyester film was determined by the following method. Using two polarizing plates, the orientation axis direction of the film was determined, and a 4 cm ⁇ 2 cm rectangle was cut out so that the orientation axis directions were perpendicular to each other, and used as a measurement sample.
  • the biaxial refractive index (Nx, Ny) perpendicular to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractometer (Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
  • ) of the axis was defined as the anisotropy ( ⁇ Nxy) of the refractive index.
  • 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. From the product ( ⁇ Nxy ⁇ d) of refractive index anisotropy ( ⁇ Nxy) and film thickness d (nm), the retardation (Re) of the polyester film was determined.
  • the cycloolefin resin film, the polyolefin resin film, and the (meth) acrylic resin film were measured using RETS100 (manufactured by Otsuka Electronics Co., Ltd.).
  • the sample was cut out to have a size of 10 cm ⁇ 10 cm, placed so as to be perpendicular to the incident light, and measured at 400 nm to 800 nm.
  • the measurement spot diameter was 2 mm, and a 100 W halogen lamp was used as the light source.
  • an automatic tilt rotation stage was used, and the measurement mode was measured by one point measurement, and a retardation value at a wavelength of 589 nm was obtained.
  • ) and ⁇ Nyz (
  • Tear strength The tear strength of each PET film was measured according to JIS P-8116 using an Elmendorf tear tester manufactured by Toyo Seiki Seisakusho. The tearing direction was performed so as to be parallel to the orientation main axis direction of the film, and was determined as follows. The measurement in the direction of the orientation axis was performed with a molecular orientation meter (MOA-6004 type molecular orientation meter, manufactured by Oji Scientific Instruments). ⁇ : Tear strength is 50 mN or more ⁇ : Tear strength is less than 50 mN
  • Acid modification amount Resin flakes (10 to 17 mg / cm 2 ) were prepared by superheat pressing (230 ° C), and the flakes were extracted with acetone over 5 hours and then air-dried. Measured and calculated from the following formula.
  • 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 total dicarboxylic acid component) 46 mol% terephthalic acid, 46 mol% isophthalic acid and 8 mol% sodium 5-sulfonatoisophthalate, A water-dispersible sulfonic acid metal base-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as a glycol component (based on the entire glycol component) was prepared.
  • the thickness ratio (adhesion improving layer / polypropylene film) was 11/69 ⁇ m.
  • the film was adhered to the cooling roll during the cooling by an electrostatic adhesion method.
  • the surface temperature of the cooling roll was set to 20 ° C.
  • the film was wound up at a speed of 5 m / min.
  • Polypropylene adhesive resin Mitsubishi Chemical Corporation, Modic APP P504, melt flow rate: 5 g / 10 min (230 ° C.), acid modification amount 0 with a third extruder (PCM30 extruder: manufactured by Ikekai Tekko Co., Ltd.) .4 wt%) was used to obtain a polarizer protective film in the same manner as in Production Example 5. It turns out that the adhesiveness with respect to PVA is favorable.
  • 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 an ordinary 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 125 ° C. while being gripped by a clip, and stretched 4.0 times in the width direction.
  • the film was treated at a temperature of 225 ° C. for 30 seconds and further subjected to a relaxation treatment of 3% in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 50 ⁇ m.
  • the above-mentioned uniaxially oriented polyester film is attached to one side of a polarizer made of PVA and iodine so that the absorption axis of the polarizer and the main axis of orientation of the film are perpendicular to each other, and the TAC film (Fuji Film Co., Ltd.) Manufactured, with a thickness of 80 ⁇ m), and polarizing plate A was created.
  • the polypropylene film obtained in Production Example 4 is attached to one side of a polarizer made of PVA and iodine so that the absorption axis of the polarizer and the orientation main axis of the film are perpendicular to each other, and the TAC film (Fuji A polarizing plate B was prepared by pasting a film (trade name, 80 ⁇ m thickness).
  • the obtained polarizing plate A is placed on the emission light side of a liquid crystal display device using a white LED composed of a light emitting element combining a blue light emitting diode and a yttrium / aluminum / garnet yellow phosphor as a light source (Nichia Chemical, NSPW500CS). It installed so that a polyester film might become a visual recognition side. Furthermore, the obtained polarizing plate B was installed on the incident light side of the liquid crystal display device so that the polypropylene film was on the light source side, thereby manufacturing a liquid crystal display device.
  • Example 2 A uniaxially oriented PET film was obtained in the same manner as in Example 1 except that the thickness of the unstretched film was changed to about 100 ⁇ m.
  • a polarizing plate C was produced by attaching the polypropylene film obtained in Production Example 4 on both sides of a polarizer made of PVA and iodine so that the absorption axis of the polarizer and the orientation main axis of the film were perpendicular to each other.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate C was used as the polarizing plate on the incident light side of the liquid crystal cell and the uniaxially oriented polyester film having a thickness of 100 ⁇ m was used.
  • Example 3 An unstretched film produced by the same method as in Example 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then stretched 1.5 times in the running direction with a roll group having a difference in peripheral speed. After that, the film was stretched 4.0 times in the width direction in the same manner as in Example 1 to obtain a biaxially oriented PET film having a film thickness of about 50 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this biaxially oriented PET film was used.
  • Example 4 In the same manner as in Example 3, the film was stretched 2.0 times in the running direction and 4.0 times in the width direction to obtain a biaxially oriented PET film having a film thickness of about 50 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this biaxially oriented PET film was used.
  • Example 5 In the same manner as in Example 3, the film was stretched 3.3 times in the running direction and 4.0 times in the width direction to obtain a biaxially oriented PET film having a film thickness of about 75 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this biaxially oriented PET film was used.
  • Example 6 In the same manner as in Example 1, a uniaxially oriented PET film having a film thickness of 50 ⁇ m was obtained without using a PET resin (B) containing an ultraviolet absorber in the intermediate layer.
  • the obtained PET film has a high light transmittance of 380 nm, and there is a concern that the optical functional dye is deteriorated.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this uniaxially oriented PET film was used.
  • Example 7 In the same manner as in Example 3, the film was stretched 4.0 times in the running direction and 1.0 times in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 100 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this uniaxially oriented PET film was used.
  • Example 8 In the same manner as in Example 3, the film was stretched 3.5 times in the running direction and 3.7 times in the width direction to obtain a biaxially oriented PET film having a film thickness of about 250 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this biaxially oriented PET film was used.
  • the polyester film had Re of 4500 nm or more, but the Re / Rth ratio was less than 0.2, and therefore, very thin rainbow spots were observed in an oblique direction.
  • Example 9 In the same manner as in Example 1, the film was stretched 1.0 times in the running direction and 3.5 times in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 75 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this uniaxially oriented PET film was used.
  • Example 10 By using the same method as in Example 1 and changing the thickness of the unstretched film, a uniaxially oriented PET film having a thickness of about 275 ⁇ m was obtained. A liquid crystal display device was produced in the same manner as in Example 1 except that this uniaxially oriented PET film was used.
  • Example 11 It replaced with the polypropylene film of manufacture example 4, and was carried out similarly to Example 1 except having used the polypropylene film of manufacture example 5.
  • the polarizer was created so that the surface which has the adhesive property modification layer of a polypropylene film might become a polarizer side.
  • the number of cells in which the polyvinyl alcohol polymer layer was not peeled was 80, and the adhesiveness to PVA was good.
  • Example 12 The procedure was the same as Example 11 except that the polypropylene film of Production Example 6 was used instead of the polypropylene film of Production Example 5. As a result of the evaluation of adhesiveness, it was found that the number of cells in which the polyvinyl alcohol polymer layer was not peeled was 75, and the adhesiveness to PVA was good.
  • Example 13 Instead of the polypropylene film of Production Example 4, a biaxially stretched film (retardation: 55 nm) of norbornene-based resin (manufactured by ZEON Corporation, trade name: ZEONOR) having a thickness of 40 ⁇ m was used in the same manner as in Example 1. A liquid crystal display device was manufactured.
  • Example 14 A liquid crystal display device was produced in the same manner as in Example 1 except that a lactonized polymethyl methacrylate film (lactonization rate 20%, thickness 30 ⁇ m, retardation was 0 nm) was used instead of the polypropylene film of Production Example 4.
  • a lactonized polymethyl methacrylate film lactonization rate 20%, thickness 30 ⁇ m, retardation was 0 nm
  • Example 1 In the same manner as in Example 3, the film was stretched 3.6 times in the running direction and 4.0 times in the width direction to obtain a biaxially oriented PET film having a film thickness of about 38 ⁇ m.
  • a liquid crystal display device was produced in the same manner as in Example 1 except that this biaxially oriented PET film was used. The retardation of the polyester film was low, and rainbow-like color spots were observed when observed from an oblique direction.
  • Comparative Example 2 Using the same method as in Example 1, the thickness of the unstretched film was changed to obtain a uniaxially oriented PET film having a thickness of about 10 ⁇ m. A liquid crystal display device was produced in the same manner as in Example 1 except that this uniaxially oriented PET film was used. Retardation was also low, and iridescent spots were observed.
  • Example 3 The same procedure as in Example 1 was performed except that rainbow spots were observed using a cold cathode tube as the light source of the liquid crystal display device.
  • Table 1 below shows the results of the observation of rainbow spots and the physical properties of the films of the liquid crystal display devices of Examples 1 to 14 and Comparative Examples 1 to 3.
  • Example 7 has insufficient tear strength. This is because the polyester film of Example 7 has too high Re / Rth, and the polyester film of Comparative Example 2 is considered to be too thin.
  • liquid crystal display device of the present invention By using the liquid crystal display device of the present invention, it is possible to contribute to the reduction in thickness and cost of the LCD without reducing visibility due to rainbow-like color spots, and the industrial applicability is extremely high. .

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Polarising Elements (AREA)
  • Liquid Crystal (AREA)
  • Optical Filters (AREA)

Abstract

L'invention concerne un dispositif d'affichage à cristaux liquides permettant de faire face à un amincissement (en d'autres termes, des films protecteurs de polariseur possèdent une résistance mécanique suffisante), et dans lequel n'apparaissent pas de dégradations de la visibilité par une irrégularité de couleur à la façon d'un arc-en-ciel. Le dispositif de l'invention possède une source lumineuse de rétroéclairage, et des cellules de cristaux liquides disposées entre deux plaques de polarisation. La source lumineuse de rétroéclairage consiste en une source lumineuse blanche possédant un spectre de luminescence continu. Les plaques de polarisation sont configurées par stratification des deux côtés d'un polariseur des films protecteurs de polariseur. Au moins un des films protecteurs de polariseur de la plaque de polarisation placée côté lumière émise par rapport aux cellules de cristaux liquides, consiste en un film polyester possédant un retard optique de 3000 à 30000nm. Enfin, au moins un des films protecteurs de polariseur de la plaque de polarisation placée côté lumière incidente par rapport aux cellules de cristaux liquides, consiste en un film de résine cyclooléfine, un film de résine polyoléfine ou un film de résine (méth)acrylique possédant un retard optique de 3000 à 30000.
PCT/JP2012/083849 2011-12-28 2012-12-27 Dispositif d'affichage à cristaux liquides WO2013100042A1 (fr)

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JP2011287530 2011-12-28
JP2012169641 2012-07-31
JP2012-169641 2012-07-31

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WO2015037527A1 (fr) * 2013-09-10 2015-03-19 東洋紡株式会社 Dispositif d'affichage à cristaux liquides, plaque de polarisation et film protecteur de polariseur
US9798189B2 (en) 2010-06-22 2017-10-24 Toyobo Co., Ltd. Liquid crystal display device, polarizer and protective film
US10054816B2 (en) 2009-11-12 2018-08-21 Toyo Boseki Kabushiki Kaisha Method for improving visibility of liquid crystal display device, and liquid crystal display device using same
US10175494B2 (en) 2011-05-18 2019-01-08 Toyobo Co., Ltd. Polarizing plate suitable for liquid crystal display device capable of displaying three-dimensional images, and liquid crystal display device
US10180597B2 (en) 2011-05-18 2019-01-15 Toyobo Co., Ltd. Liquid crystal display device, polarizing plate, and polarizer protection film
WO2020162119A1 (fr) * 2019-02-08 2020-08-13 東洋紡株式会社 Film de polyester et son utilisation
WO2020162120A1 (fr) * 2019-02-08 2020-08-13 東洋紡株式会社 Écran pliable et équipement terminal portable
WO2020241279A1 (fr) * 2019-05-28 2020-12-03 東洋紡株式会社 Film en polyester, film stratifié et utilisation associée
WO2020241281A1 (fr) * 2019-05-28 2020-12-03 東洋紡株式会社 Film de polyester conducteur transparent et son utilisation
WO2020241278A1 (fr) * 2019-05-28 2020-12-03 東洋紡株式会社 Film multicouche et son utilisation
CN113874767A (zh) * 2019-05-30 2021-12-31 东洋纺株式会社 折叠型显示器
EP3978966A4 (fr) * 2019-05-30 2023-07-12 Toyobo Co., Ltd. Plaque de polarisation pour dispositif d'affichage pliable
US11926720B2 (en) 2019-05-28 2024-03-12 Toyobo Co., Ltd. Polyester film and application therefor

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US10948764B2 (en) 2009-11-12 2021-03-16 Keio University Method for improving visibility of liquid crystal display device, and liquid crystal display device using the same
US10054816B2 (en) 2009-11-12 2018-08-21 Toyo Boseki Kabushiki Kaisha Method for improving visibility of liquid crystal display device, and liquid crystal display device using same
US10503016B2 (en) 2010-06-22 2019-12-10 Toyobo Co., Ltd. Liquid crystal display device, polarizer and protective film
US9798189B2 (en) 2010-06-22 2017-10-24 Toyobo Co., Ltd. Liquid crystal display device, polarizer and protective film
US9897857B2 (en) 2010-06-22 2018-02-20 Toyobo Co., Ltd. Liquid crystal display device, polarizer and protective film
US10175494B2 (en) 2011-05-18 2019-01-08 Toyobo Co., Ltd. Polarizing plate suitable for liquid crystal display device capable of displaying three-dimensional images, and liquid crystal display device
US10180597B2 (en) 2011-05-18 2019-01-15 Toyobo Co., Ltd. Liquid crystal display device, polarizing plate, and polarizer protection film
JP2022105524A (ja) * 2013-09-10 2022-07-14 東洋紡株式会社 偏光子保護フィルム、偏光板及び液晶表示装置
CN105531610A (zh) * 2013-09-10 2016-04-27 东洋纺株式会社 液晶显示装置、偏光板和偏振片保护膜
TWI675226B (zh) * 2013-09-10 2019-10-21 東洋紡股份有限公司 液晶顯示裝置、偏光板及偏光鏡保護膜
JPWO2015037527A1 (ja) * 2013-09-10 2017-03-02 東洋紡株式会社 液晶表示装置、偏光板及び偏光子保護フィルム
JP2020115211A (ja) * 2013-09-10 2020-07-30 東洋紡株式会社 液晶表示装置、偏光板及び偏光子保護フィルム
KR102491441B1 (ko) * 2013-09-10 2023-01-20 도요보 가부시키가이샤 액정표시장치, 편광판 및 편광자 보호 필름
WO2015037527A1 (fr) * 2013-09-10 2015-03-19 東洋紡株式会社 Dispositif d'affichage à cristaux liquides, plaque de polarisation et film protecteur de polariseur
KR20210116714A (ko) * 2013-09-10 2021-09-27 도요보 가부시키가이샤 액정표시장치, 편광판 및 편광자 보호 필름
JP2018185535A (ja) * 2013-09-10 2018-11-22 東洋紡株式会社 液晶表示装置、偏光板及び偏光子保護フィルム
CN113396179A (zh) * 2019-02-08 2021-09-14 东洋纺株式会社 聚酯薄膜及其用途
US11934226B2 (en) 2019-02-08 2024-03-19 Toyobo Co., Ltd. Foldable display and portable terminal device
WO2020162120A1 (fr) * 2019-02-08 2020-08-13 東洋紡株式会社 Écran pliable et équipement terminal portable
WO2020162119A1 (fr) * 2019-02-08 2020-08-13 東洋紡株式会社 Film de polyester et son utilisation
US11997916B2 (en) 2019-02-08 2024-05-28 Toyobo Co., Ltd. Polyester film and use thereof
WO2020241281A1 (fr) * 2019-05-28 2020-12-03 東洋紡株式会社 Film de polyester conducteur transparent et son utilisation
WO2020241279A1 (fr) * 2019-05-28 2020-12-03 東洋紡株式会社 Film en polyester, film stratifié et utilisation associée
WO2020241278A1 (fr) * 2019-05-28 2020-12-03 東洋紡株式会社 Film multicouche et son utilisation
US11939499B2 (en) 2019-05-28 2024-03-26 Toyobo Co., Ltd. Multilayer film and use of same
US11899167B2 (en) 2019-05-28 2024-02-13 Toyobo Co., Ltd. Polyester film, laminated film, and use thereof
US11926720B2 (en) 2019-05-28 2024-03-12 Toyobo Co., Ltd. Polyester film and application therefor
CN113874767A (zh) * 2019-05-30 2021-12-31 东洋纺株式会社 折叠型显示器
EP3978966A4 (fr) * 2019-05-30 2023-07-12 Toyobo Co., Ltd. Plaque de polarisation pour dispositif d'affichage pliable
EP3978967A4 (fr) * 2019-05-30 2023-07-12 Toyobo Co., Ltd. Écran pliable

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