WO2018181655A1 - Liquid crystal display device, polarizing plate, and polarizer protective film - Google Patents

Liquid crystal display device, polarizing plate, and polarizer protective film Download PDF

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Publication number
WO2018181655A1
WO2018181655A1 PCT/JP2018/013103 JP2018013103W WO2018181655A1 WO 2018181655 A1 WO2018181655 A1 WO 2018181655A1 JP 2018013103 W JP2018013103 W JP 2018013103W WO 2018181655 A1 WO2018181655 A1 WO 2018181655A1
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WIPO (PCT)
Prior art keywords
film
protective film
polyethylene terephthalate
liquid crystal
polarizer protective
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PCT/JP2018/013103
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French (fr)
Japanese (ja)
Inventor
尭永 阿部
章太 早川
村田　浩一
向山　幸伸
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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 JP2019510094A priority Critical patent/JP7261738B2/en
Priority to CN202111479126.8A priority patent/CN114325916B/en
Priority to KR1020197029819A priority patent/KR102343137B1/en
Priority to CN201880019761.8A priority patent/CN110446954B/en
Publication of WO2018181655A1 publication Critical patent/WO2018181655A1/en
Priority to JP2023007808A priority patent/JP2023041758A/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
    • B29C55/08—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique transverse to the direction of feed
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

  • the present invention relates to a liquid crystal display device, a polarizing plate and a polarizer protective film.
  • a polarizing plate used in a liquid crystal display device is usually configured by sandwiching a polarizer obtained by dyeing iodine in polyvinyl alcohol (PVA) or the like between two polarizer protective films.
  • PVA polyvinyl alcohol
  • TAC triacetyl cellulose
  • TAC films are very expensive, and polyester films have been proposed as inexpensive alternative materials (Patent Documents 1 to 3), but there is a problem that rainbow-like color spots are observed.
  • the polarization state of the linearly polarized light emitted from the backlight unit or the polarizer changes when passing through the polyester film.
  • the transmitted light shows an interference color peculiar to retardation which is a product of birefringence and thickness of the oriented polyester film. Therefore, when 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, resulting in a rainbow-like color spot (see: Proceedings of the 15th Micro Optical Conference Proceedings, Paragraphs 30-31).
  • a white light source having a continuous and broad emission spectrum such as a white light emitting diode as a backlight light source, and further using an oriented polyester film having a certain retardation as a polarizer protective film.
  • Patent Document 4 White light emitting diodes have a continuous and broad emission spectrum in the visible light region. Therefore, focusing on the envelope shape of the interference color spectrum due to the transmitted light that has passed through the birefringent body, it becomes possible to obtain a spectrum similar to the emission spectrum of the light source by controlling the retardation of the oriented polyester film. It has become possible to suppress rainbow spots.
  • White light-emitting diodes consisting of light-emitting elements that combine blue light-emitting diodes and yttrium / aluminum / garnet-based yellow phosphors (YAG-based yellow phosphors) have been widely used as backlight sources for liquid crystal display devices. It has been.
  • the emission spectrum of this white light source is widely used as a backlight light source because it has a broad spectrum in the visible light region and is excellent in luminous efficiency.
  • this white LED as a backlight light source, the color can be reproduced only about 20% of the spectrum recognizable by human eyes.
  • the emission spectrum of a white light source has a clear peak shape in each wavelength region of R (red), G (green), and B (blue).
  • Liquid crystal display devices that are compatible with the development have been developed.
  • a white light source using quantum dot technology a phosphor type white LED light source using a phosphor and a blue LED having a clear emission peak in the R (red) and G (green) regions by excitation light, three wavelengths
  • Various types of light sources were used, such as a white LED light source of the system, a fluoride phosphor (also referred to as “KSF”) whose composition formula is K 2 SiF 6 : Mn 4 +, and a white LED light source using a blue LED.
  • KSF fluoride phosphor
  • Liquid crystal display devices that support a wide color gamut have been developed. In the case of such a liquid crystal display device that supports a wide color gamut, it is said that it is possible to reproduce colors of 60% or more of the spectrum that can be recognized by the human eye.
  • Each of these white light sources has a narrow peak half-value width compared to a light source composed of a white light-emitting diode using a conventional YAG-based yellow phosphor, and is composed of a polyethylene terephthalate resin film having retardation as a constituent member of a polarizing plate. It was newly found that when used as a polarizer protective film, rainbow spots may occur depending on the type of light source.
  • a polyethylene terephthalate resin film as a polarizer protective film, which is a constituent member of a polarizing plate, in a liquid crystal display device that supports a wide color gamut or when it is thinned
  • the representative present invention is as follows.
  • Item 1 A polarizer protective film comprising a polyethylene terephthalate resin film that satisfies the following (1) and (2).
  • Retardation is 3000 nm or more and 30000 nm or less
  • Item 2. The polarizer protective film according to Item 1, wherein the polyethylene terephthalate resin film further satisfies the following (3).
  • the degree of orientation of the (100) plane with respect to the film plane measured by X-ray diffraction is 0.7 or less.
  • Item 4. A liquid crystal display device having a backlight source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates, wherein at least one of the two polarizing plates is the polarizing plate according to item 3. Liquid crystal display device.
  • a polyethylene terephthalate-based resin film which is a constituent member of a polarizing plate
  • polarizer protective film which is a constituent member of a polarizing plate
  • the polyethylene terephthalate resin film used for the polarizer protective film of the present invention preferably has a retardation of 3000 nm or more and 30000 nm or less.
  • the preferred lower limit of retardation is 4000 nm, and the next preferred lower limit is 5000 nm.
  • the upper limit of retardation is preferably 30000 nm. Even if a polyethylene terephthalate-based resin film having a retardation higher than that is used, the effect of further improving visibility is not substantially obtained, the thickness of the film is considerably increased, and the handleability as an industrial material is lowered.
  • a preferable upper limit is 10,000 nm, a more preferable upper limit is 9000 nm, and a still more preferable upper limit is 8000 nm.
  • Retardation can be obtained by measuring the biaxial refractive index and film thickness in the film plane, or by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments). it can.
  • the measurement wavelength of the refractive index is 589 nm.
  • the difference in refractive index in the film plane of the polyethylene terephthalate resin film is preferably 0.08 or more, more preferably 0.09 or more, and still more preferably. 0.10 or more.
  • the upper limit of the refractive index difference is preferably 0.15 or less. It is preferable that the film is strongly stretched in one direction and has a large refractive index difference in the film plane from the viewpoint of further suppressing rainbow spots.
  • the refractive index in the slow axis direction and the refractive index in the fast axis direction are determined by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
  • the polyethylene terephthalate resin film used for the polarizer protective film of the present invention has a rigid amorphous fraction of 33 wt% or more, and suppresses rainbow spots observed from an oblique direction.
  • the rigid amorphous fraction of the polyethylene terephthalate resin film is preferably 33 wt% or more, more preferably 34 wt% or more, more preferably 35 wt% or more, and further preferably 36 wt% or more.
  • the upper limit is preferably 60 wt%, but about 50 wt% or 45 wt% is sufficient.
  • wt% is synonymous with mass%.
  • the higher order structure of a polymer is divided into a crystal and an amorphous structure.
  • the amorphous region can be further distinguished by the temperature dependence of the molecular motion, and the molecular motion is frozen even at temperatures above the Tg and the movable amorphous state where the molecular motion is released at the glass transition point (Tg).
  • Tg glass transition point
  • the rigid amorphous fraction is indirectly determined using the values of the movable amorphous fraction and the mass fraction crystallinity.
  • the movable amorphous fraction is determined from the reversible heat capacity difference ⁇ Cp at Tg of the reversible heat capacity curve obtained by temperature modulation DSC measurement using a differential scanning calorimeter (TA Instrument, Q100).
  • the mass fraction crystallinity is calculated from the density value obtained using a density gradient tube in accordance with JIS K7112. Details will be described later in Examples.
  • the degree of orientation of the benzene ring in the polyethylene terephthalate-based resin film with respect to the film surface can be evaluated using the degree of orientation of the (100) plane almost parallel to the benzene ring as an index.
  • the polyethylene terephthalate resin film used for the polarizer protective film of the present invention has an orientation degree of 0.7 or less with respect to the film surface of the (100) plane measured by X-ray diffraction. Is preferable from the viewpoint of suppressing rainbow spots observed from an oblique direction.
  • the degree of orientation of the (100) plane of the polyethylene terephthalate resin film is preferably 0.7 or less, more preferably 0.68 or less, more preferably 0.66 or less, and still more preferably 0.64. It is as follows.
  • the lower limit is preferably 0.40.
  • the degree of orientation of the (100) plane with respect to the film surface is an index indicating the orientation around the molecular chain axis of the polyethylene terephthalate crystal, and the lower the value, the more random the orientation around the molecular chain axis. The more the orientation around the molecular chain axis is random, the more rainbow spots observed from the oblique direction are suppressed.
  • the intensity of X-rays scattered by crystals is mainly measured, but X-rays scattered by amorphous (oriented amorphous) that are oriented and have regularity are measured. Intensity is also included in the measurement.
  • the (100) plane refers to a specific crystal plane in the crystal lattice, but the degree of orientation of the (100) plane relative to the film plane is an index of the degree of orientation of the benzene ring in the crystal and oriented amorphous with respect to the film plane. Equivalent to.
  • the polyethylene terephthalate resin film which is a protective film of the present invention, can be manufactured by using a general polyester film manufacturing method.
  • a non-oriented polyethylene terephthalate resin melted from a polyethylene terephthalate resin and extruded into a sheet shape is stretched in the machine direction at a temperature equal to or higher than the glass transition temperature by using a speed difference of a roll, and then stretched by a tenter.
  • stretching to a direction and giving heat processing is mentioned.
  • the film forming conditions of the polyethylene terephthalate resin film will be specifically described.
  • the longitudinal stretching temperature and the transverse stretching temperature are preferably 100 to 130 ° C, particularly preferably 110 to 125 ° C.
  • the longitudinal draw ratio is preferably 0.7 to 1.5 times, particularly preferably 0.7 to 1.0 times.
  • the lower limit of the transverse draw ratio is preferably 4.5 times, more preferably 4.7 times, and particularly preferably 5.0 times.
  • the upper limit of the transverse draw ratio is preferably 7.0 times, more preferably 6.5 times, particularly preferably 6.0 times, and most preferably 5.5 times.
  • the transverse draw ratio is preferably 1.0 to 3.0 times, more preferably 2.0 to 3.0 times. is there. From the viewpoint of suppressing relaxation of the amorphous molecular chain during stretching and increasing the rigid amorphous fraction, it is preferable to increase the longitudinal stretching ratio.
  • the lower limit of the longitudinal draw ratio is preferably 4.5 times, more preferably 4.7 times, and particularly preferably 5.0 times. If the longitudinal draw ratio exceeds 7.0 times, the film tends to tear in the machine direction and the productivity is lowered. Therefore, the upper limit of the longitudinal draw ratio is preferably 7.0 times, more preferably 6.5 times, particularly Preferably it is 6.0 times.
  • the rigid amorphous fraction In order to suppress the orientation of the benzene ring with respect to the film surface accompanying crystallization during heat treatment, it is preferable to increase the rigid amorphous fraction. Specifically, it is preferable to suppress relaxation of amorphous molecular chains during stretching, and it is preferable to increase the strain rate in stretching in the slow axis direction of the film.
  • the strain rate is preferably 13% / sec or more, more preferably 15% / sec or more, and particularly preferably 17% / sec or more. From the viewpoint of film formability, the upper limit of the strain rate is preferably 60% / sec.
  • the strain rate is an amount expressed by (nominal strain (%) in stretching in the slow axis direction) / (required time (sec) in stretching in the slow axis direction), and nominal strain (%) Is obtained by ((deformation amount (mm)) / (initial length (mm))) ⁇ 100.
  • the lower limit of the heat treatment temperature is preferably 150 ° C, more preferably 160 ° C, particularly preferably 170 ° C, and most preferably 180 ° C.
  • the upper limit of the heat treatment temperature is preferably 220 ° C., more preferably 210 ° C., and particularly preferably 200 from the viewpoint of preventing rigid crystallization and reducing the degree of orientation of the (100) plane of the crystal with respect to the film surface. ° C.
  • the polyethylene terephthalate resin constituting the polyethylene terephthalate resin film 85 mol% or more of the monomer units are preferably ethylene terephthalate.
  • the ethylene terephthalate unit is preferably 90 mol% or more, more preferably 95 mol% or more.
  • a particularly preferable polyethylene terephthalate resin is polyethylene terephthalate which is a homopolymer.
  • Polyethylene terephthalate is the most suitable material because it has a large intrinsic birefringence and can easily obtain a large retardation even when the film is thin.
  • the protective film of the present invention desirably 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).
  • the ultraviolet absorber used in the present invention is a known substance.
  • 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.
  • the organic ultraviolet absorber include benzotriazole, benzophenone, cyclic imino ester, and combinations thereof, but are not particularly limited as long as the absorbance is within the range defined by the present invention.
  • benzotriazole type and cyclic imino ester type are particularly preferable.
  • benzophenone ultraviolet absorber examples include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2 ′.
  • cyclic imino ester UV absorbers examples include 2,2 ′-(1,4-phenylene).
  • 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.
  • the polyethylene terephthalate resin film does not substantially contain particles.
  • “Substantially free of particles” means, for example, in the case of inorganic particles, a content that is 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less when inorganic elements are quantified by fluorescent X-ray analysis. means.
  • the ultraviolet absorber and the polymer raw material that have been dried using a kneading extruder in advance are used.
  • 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 kneading extruder is used, and the extrusion temperature is preferably from 1 to 15 minutes at a temperature not lower than the melting point of the polyethylene terephthalate raw material and not higher than 290 ° C. Above 290 ° C, the weight loss of the UV absorber is large, and the viscosity of the master batch is greatly reduced. If the extrusion time is 1 minute or less, uniform mixing of the UV absorber becomes difficult. At this time, if necessary, a stabilizer, a color tone adjusting agent, and an antistatic agent may be added.
  • the 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. Polyethylene terephthalate resin pellets alone for the outer layer, master batches containing UV absorbers for the intermediate layer and polyethylene terephthalate resin pellets are mixed at a predetermined ratio, dried, and then fed to a known melt laminating extruder. The unstretched film is produced by feeding, extruding into a sheet from a slit-shaped die, and cooling and solidifying on a casting roll.
  • 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.
  • the polyethylene terephthalate resin film of the present invention can be subjected to corona treatment, coating treatment, flame treatment, etc. in order to improve the adhesion to the polarizer.
  • At least one surface of the film of the present invention has an easy-adhesion layer mainly composed of at least one of a polyester resin, a polyurethane resin or a polyacrylic resin.
  • 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 of the present invention is preferably an aqueous coating solution containing at least one of water-soluble or water-dispersible copolymerized polyester resin, acrylic resin, and 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 a uniaxially stretched film in the longitudinal direction, 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 0.2 g / m 2 . If the coating amount is significantly less than 0.05 g / m 2 , adhesion with the obtained polarizer may be insufficient. On the other hand, if the coating amount significantly exceeds 0.2 g / m 2 , blocking resistance may be lowered.
  • the coating amount of the easy-adhesion layers on both surfaces may be the same or different, and can be independently set within the above range. .
  • particles it is preferable to add 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 significantly exceeds 2 ⁇ m, the particles easily fall off from the coating 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 at a magnification such that the size of one smallest particle is 2-5 mm, the maximum diameter of 300-500 particles (between the two most distant points) Distance) is measured, and the average value is taken as the average particle diameter.
  • SEM scanning electron microscope
  • the thickness of the polyethylene terephthalate resin film of the present invention is arbitrary, but is preferably in the range of 30 to 300 ⁇ m, more preferably in the range of 40 to 200 ⁇ m. Even in the case of a film having a thickness of less than 30 ⁇ m, it is possible in principle to obtain a retardation of 3000 nm or more. 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 45 ⁇ m.
  • 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 120 ⁇ m, more preferably 100 ⁇ m or less, still more preferably 80 ⁇ m or less, even more preferably 65 ⁇ m or less, even more preferably 60 ⁇ m or less, and even more preferably. Is 55 ⁇ m or less.
  • the thickness of the polarizer protective film is preferably in the range of 30 to 65 ⁇ m.
  • the thickness unevenness of the 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, if the longitudinal stretching ratio is lowered to increase the retardation, the longitudinal thickness unevenness may be deteriorated. Since there is a region where the vertical thickness unevenness becomes very bad 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 film of the present invention is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. It is particularly preferred.
  • the polyethylene terephthalate resin film used for the polarizer protective film preferably has an Nz coefficient represented by
  • the Nz coefficient can be obtained as follows.
  • the orientation axis direction 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, However, ny> nx) and the refractive index (nz) in the thickness direction are determined by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
  • the Nz coefficient can be obtained by substituting nx, ny, and nz obtained in this way into an expression represented by
  • the Nz coefficient is more preferably 1.65 or less, and still more preferably 1.63 or less.
  • the lower limit value of the Nz coefficient is 1.2. In order to maintain the mechanical strength of the film, the lower limit value of the Nz coefficient is preferably 1.3 or more, more preferably 1.4 or more, and further preferably 1.45 or more.
  • the polyethylene terephthalate resin film has a ratio (Re / Rth) of retardation (Re) to thickness direction retardation (Rth) of preferably 0.2 or more, more preferably 0.5 or more, and still more preferably 0.6. That's it. The larger the ratio (Re / Rth), the better.
  • the upper limit is preferably 2.0 or less, more preferably 1.8 or less.
  • ) and ⁇ Nyz (
  • the thickness direction retardation (Rth) can be determined by calculating nx, ny, nz and the film thickness d (nm) and calculating the average value of ( ⁇ Nxz ⁇ d) and ( ⁇ Nyz ⁇ d).
  • nx, ny, and nz are obtained by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
  • the polarizing plate of the present invention has a structure in which a polarizer protective film is bonded to at least one surface of a polarizer in which polyvinyl alcohol (PVA) or the like is dyed with iodine.
  • PVA polyvinyl alcohol
  • the other polarizer protective film it is preferable to use a film having no birefringence such as a TAC film, an acrylic film, and a norbornene-based film.
  • the other polarizer protective film does not necessarily need to exist.
  • a liquid crystal panel includes a rear module, a liquid crystal cell, and a front module in order from the side facing the backlight light source toward the image display side (viewing 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 arranged on the side facing the backlight light source in the rear module, and is arranged on the side (viewing side) displaying the image 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. Of the two polarizing plates, at least one polarizing plate is preferably the polarizing plate of the present invention described above.
  • the configuration of the backlight may be an edge light method using a light guide plate or a reflection plate as a constituent member, or a direct type.
  • the backlight light source of the liquid crystal display device is not particularly limited, but a phosphor type white LED is preferable. That is, it 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.
  • the phosphor include yttrium / aluminum / garnet yellow phosphor and terbium / aluminum / garnet yellow phosphor.
  • the white light source which has the peak top of an emission spectrum in each wavelength range of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less is also preferable.
  • a white light source using quantum dot technology a phosphor type white LED light source using a phosphor and a blue LED each having an emission peak in the R (red) and G (green) regions by excitation light
  • a three-wavelength method White LED light source, white LED light source combined with red laser, and other white LED using blue LED and fluoride phosphor (also referred to as “KSF”) whose composition formula is K 2 SiF 6 : Mn 4 + Examples include a light source. These are attracting attention as backlight light sources for liquid crystal display devices that support a wide color gamut.
  • the arrangement of the polarizer protective film of the present invention having the specific retardation in the liquid crystal display device is not particularly limited.
  • the polarizing plate disposed on the incident light side (light source side), the liquid crystal cell, and the outgoing light side visible
  • a polarizer protective film on the incident light side of the polarizing plate arranged on the incident light side and / or a polarizing plate arranged on the outgoing light side is a polarizer protective film made of a polyethylene terephthalate resin film having the specific retardation.
  • a particularly preferred embodiment is an embodiment in which the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side is a polyethylene terephthalate resin film having the specific retardation.
  • a polyethylene terephthalate resin film is disposed at a position other than the above, the polarization characteristics of the liquid crystal cell may be changed. Since it is not preferable to use the polymer film of the present invention at a place where polarization characteristics are required, it is preferably used as a protective film for a polarizing plate at such a specific position.
  • 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 (refractive index in the slow axis direction: ny, refractive index in the direction perpendicular to the slow axis direction: nx), and 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).
  • the rigid amorphous fraction is expressed by the above formula (1) and is indirectly calculated from the values of the movable amorphous fraction and the mass fraction crystallinity.
  • the movable amorphous fraction is the reversible heat capacity difference ⁇ Cp (J / (g ⁇ K)) at the Tg of the reversible heat capacity curve obtained by temperature modulation DSC measurement using a differential scanning calorimeter (TA Instrument, Q100). It is a parameter defined by the following formula.
  • Movable amorphous fraction (( ⁇ Cp of sample) / ( ⁇ Cp of completely amorphous)) ⁇ 100 (wt%)
  • ⁇ Cp 0.4052 (J / (g ⁇ K)
  • the sample was weighed in an aluminum pan at 2.0 ⁇ 0.2 mg, and measured in an MDSC (registered trademark) heat-only mode at an average heating rate of 5.0 ° C./min and a modulation period of 60 sec. Measurement data was collected at a sampling frequency of 5 Hz.
  • indium was used for temperature and calorie calibration, and sapphire was used for specific heat calibration.
  • Tg and ⁇ Cp the calculation method of Tg and ⁇ Cp is shown.
  • Tg the temperature value at the peak top
  • the Tg was determined by reading.
  • a straight line G (T) passing through two points of point A (Tg-15, F (Tg-15)) and point B (Tg + 15, F (Tg + 15)) was obtained.
  • Tg the temperature at which F (T) ⁇ G (T) is minimum
  • T2 corresponds to the glass transition end temperature
  • a value of ⁇ Cp F (T2) ⁇ F (T1).
  • the mass fraction crystallinity ⁇ was calculated by the following equation using the density value d (g / cm 3 ) obtained using a water / calcium nitrate density gradient tube according to JIS K7112.
  • ⁇ (dc / d) ⁇ ((d ⁇ da) / (d ⁇ dc)) ⁇ 100 (wt%)
  • dc density of complete crystal
  • da density of completely amorphous
  • dc 1.498 (g / cm 3 )
  • da 1.335 (g / cm 3 ).
  • the control object is a reflection ⁇
  • measurement method FT
  • start position 15,000 degrees
  • end position 90.000 degrees
  • J ( ⁇ ) I ( ⁇ ) ⁇ (1-exp ( ⁇ 2 ⁇ t / sin ⁇ )) / (1-exp ( ⁇ 2 ⁇ t / (sin ⁇ cos (90 ⁇ ))))
  • ⁇ is the linear absorption coefficient of CuK ⁇ ray
  • ⁇ 9.02 (/ cm)
  • t is the sample thickness (cm)
  • ⁇ corresponds to half of the 2 ⁇ fixed angle at the time of measurement. .915 degrees.
  • J ( ⁇ ′) (15 ⁇ ⁇ ′ ⁇ 165) was fitted with a pseudo-Forked function to obtain diffraction intensity profiles K ( ⁇ ′) for all ⁇ ′.
  • the degree of orientation of the (100) plane relative to the film plane was calculated by / 180.
  • a polyethylene terephthalate-based resin film prepared by the method described later 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.
  • a commercially available TAC film was attached to the surface to prepare a polarizing plate. The obtained polarizing plate was replaced with a polarizing plate on the outgoing light side originally present in a commercially available liquid crystal display device (REGZA 43J10X manufactured by Toshiba Corporation).
  • the polarizing plate was replaced so that the polyethylene terephthalate resin film was on the viewing side so that the absorption axis of the polarizing plate coincided with the absorption axis direction of the polarizing plate originally attached to the liquid crystal display device.
  • the liquid crystal display device includes a light source that emits excitation light and a backlight light source that includes a KSF phosphor.
  • emission spectrum of the backlight source of this liquid crystal display device was measured using a multi-channel spectrometer PMA-12 manufactured by Hamamatsu Photonics, emission spectra having peak tops in the vicinity of 448 nm, 533 nm, and 630 nm were observed.
  • the half-value width of was 2 nm to 49 nm.
  • the exposure time for spectrum measurement was 20 msec.
  • a white image was displayed on the liquid crystal display device thus manufactured, and visual observation was performed from the front of the display and from an oblique direction, and the occurrence of rainbow spots was determined as follows.
  • the observation angle was an angle formed by a line drawn in the normal direction (vertical) from the center of the display screen and a line connecting the center of the display and the position of the eye at the time of observation.
  • ⁇ Some thin rainbow spots were observed in the observation angle range of 0 to 60 degrees.
  • X Iridoids were clearly observed in the observation angle range of 0 to 60 degrees.
  • 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.
  • 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 has been formed is guided to a tenter stretching machine, and the edge of the film is held by a clip, guided to a hot air zone at a temperature of 130 ° C., and a strain rate of 13 so as to be 5.5 times in the width direction.
  • the film was stretched at 8% / sec.
  • heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Example 2 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 120 ° C. while being gripped by a clip, so that the width is 5.5 times the width direction.
  • the film was stretched at a strain rate of 18.3% / sec.
  • heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Example 3 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 118 ° C. while being gripped by a clip, so that the width becomes 5.0 times in the width direction.
  • the film was stretched at a strain rate of 34.6% / sec.
  • heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Example 4 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 107 ° C. while being gripped by a clip, so that the width becomes 5.0 times in the width direction.
  • the film was stretched at a strain rate of 34.6% / sec.
  • heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Example 5 An unstretched film produced by the same method as in Example 1 except that the thickness was changed was guided to a tenter stretching machine, and the end of the film was guided by a clip while being guided to a hot air zone at a temperature of 125 ° C. The film was stretched at a strain rate of 18.3% / sec so as to be 5 times. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 180 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 50 ⁇ m.
  • Example 6 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 130 ° C. while being gripped by a clip, so that the width is 5.5 times. The film was stretched at a strain rate of 13.8% / sec. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 200 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Example 7 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 120 ° C. while being gripped by a clip, so as to be 6.0 times in the width direction. The film was stretched at a strain rate of 20.8% / sec. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 180 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 50 ⁇ m.
  • Example 1 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the end of the film is guided to a hot air zone at a temperature of 90 ° C. while being gripped by a clip, so that the width becomes 4.0 times in the width direction.
  • the film was stretched at a strain rate of 12.5% / sec.
  • heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Example 2 The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 130 ° C. while being gripped by a clip, so that the width is 5.5 times. The film was stretched at a strain rate of 13.8% / sec. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 240 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 ⁇ m.
  • Table 1 shows the measurement results of the PET films obtained in Examples and Comparative Examples.
  • the liquid crystal display device, polarizing plate and polarizer protective film of the present invention even if the wavelength spectrum of the backlight light source is diversified by widening the color gamut of the liquid crystal display device or the polarizer protective film is thinned, the rainbow Spots can be suppressed.

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Abstract

The present invention addresses the problem of providing a liquid crystal display device, a polarizing plate, and a polarizer protective film, wherein the occurrence of rainbow spots can be suppressed even when the polarizer protective film is thinned, and the wavelength spectra of a backlight source is diversified by widening the color gamut of the liquid crystal display device. A polarizer protective film formed from a polyethylene terephthalate-based resin film, said polarizer protective film characterized in that the polyethylene terephthalate-based resin film satisfies the following (1) and (2): (1) the polyethylene terephthalate-based resin film has a retardation of 3,000-30,000 nm; and (2) the rigid amorphous fraction is at least 33 wt%.

Description

液晶表示装置、偏光板および偏光子保護フィルムLiquid crystal display device, polarizing plate and polarizer protective film
　本発明は、液晶表示装置、偏光板および偏光子保護フィルムに関する。 The present invention relates to a liquid crystal display device, a polarizing plate and a polarizer protective film.
　液晶表示装置（ＬＣＤ）に使用される偏光板は、通常ポリビニルアルコール（ＰＶＡ）などにヨウ素を染着させた偏光子を２枚の偏光子保護フィルムで挟んだ構成であり、偏光子保護フィルムとしては通常トリアセチルセルロース（ＴＡＣ）フィルムが用いられている。近年、ＬＣＤの薄型化に伴い、偏光板の薄層化が求められるようになっている。しかし、このために保護フィルムとして用いられているＴＡＣフィルムの厚みを薄くすると、充分な機械強度を得ることが出来ず、また透湿性が悪化するという問題が発生する。また、ＴＡＣフィルムは非常に高価であり、安価な代替素材としてポリエステルフィルムが提案されているが（特許文献１～３）、虹状の色斑が観察されるという問題があった。 A polarizing plate used in a liquid crystal display device (LCD) is usually configured by sandwiching a polarizer obtained by dyeing iodine in polyvinyl alcohol (PVA) or the like between two polarizer protective films. In general, a triacetyl cellulose (TAC) film is used. In recent years, with the thinning of LCDs, there has been a demand for thinner polarizing plates. However, if the thickness of the TAC film used as the protective film is reduced for this purpose, sufficient mechanical strength cannot be obtained and moisture permeability deteriorates. TAC films are very expensive, and polyester films have been proposed as inexpensive alternative materials (Patent Documents 1 to 3), but there is a problem that rainbow-like color spots are observed.
　偏光子の片側に複屈折性を有する配向ポリエステルフィルムを配した場合、バックライトユニット、または、偏光子から出射した直線偏光はポリエステルフィルムを通過する際に偏光状態が変化する。透過した光は配向ポリエステルフィルムの複屈折と厚さの積であるリタデーションに特有の干渉色を示す。そのため、光源として冷陰極管や熱陰極管などの不連続な発光スペクトルを用いると、波長によって異なる透過光強度を示し、虹状の色斑となる（参照：第１５回マイクロオプティカルカンファレンス予稿集、第３０～３１項）。 When an oriented polyester film having birefringence is arranged on one side of the polarizer, the polarization state of the linearly polarized light emitted from the backlight unit or the polarizer changes when passing through the polyester film. The transmitted light shows an interference color peculiar to retardation which is a product of birefringence and thickness of the oriented polyester film. Therefore, when 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, resulting in a rainbow-like color spot (see: Proceedings of the 15th Micro Optical Conference Proceedings, Paragraphs 30-31).
　上記の問題を解決する手段として、バックライト光源として白色発光ダイオードのような連続的で幅広い発光スペクトルを有する白色光源を用い、更に偏光子保護フィルムとして一定のリタデーションを有する配向ポリエステルフィルムを用いることが提案されている（特許文献４）。白色発光ダイオードは、可視光領域において連続的で幅広い発光スペクトルを有する。そのため、複屈折体を透過した透過光による干渉色スペクトルの包絡線形状に着目すると、配向ポリエステルフィルムのリタデーションを制御することで、光源の発光スペクトルと相似なスペクトルを得ることが可能となり、これにより虹斑を抑制することを可能とした。 As means for solving the above problems, it is possible to use a white light source having a continuous and broad emission spectrum such as a white light emitting diode as a backlight light source, and further using an oriented polyester film having a certain retardation as a polarizer protective film. It has been proposed (Patent Document 4). White light emitting diodes have a continuous and broad emission spectrum in the visible light region. Therefore, focusing on the envelope shape of the interference color spectrum due to the transmitted light that has passed through the birefringent body, it becomes possible to obtain a spectrum similar to the emission spectrum of the light source by controlling the retardation of the oriented polyester film. It has become possible to suppress rainbow spots.
特開２００２－１１６３２０号公報JP 2002-116320 A 特開２００４－２１９６２０号公報JP 2004-219620 A 特開２００４－２０５７７３号公報JP 2004-205773 A ＷＯ２０１１／１６２１９８WO2011 / 162198
　液晶表示装置のバックライト光源として、青色発光ダイオードとイットリウム・アルミニウム・ガーネット系黄色蛍光体（ＹＡＧ系黄色蛍光体）とを組み合わせた発光素子からなる白色発光ダイオード（白色ＬＥＤ）が、従来から広く用いられている。この白色光源の発光スペクトルは、可視光領域で幅広いスペクトルを有しているとともに、発光効率にも優れるため、バックライト光源として汎用されている。しかし、この白色ＬＥＤをバックライト光源とした液晶表示装置では、人間の目が認識可能なスペクトルの２０％程度しか色を再現することが出来ない。 White light-emitting diodes (white LEDs) consisting of light-emitting elements that combine blue light-emitting diodes and yttrium / aluminum / garnet-based yellow phosphors (YAG-based yellow phosphors) have been widely used as backlight sources for liquid crystal display devices. It has been. The emission spectrum of this white light source is widely used as a backlight light source because it has a broad spectrum in the visible light region and is excellent in luminous efficiency. However, in a liquid crystal display device using this white LED as a backlight light source, the color can be reproduced only about 20% of the spectrum recognizable by human eyes.
　一方、近年の色域拡大要求の高まりから、白色光源の発光スペクトルが、Ｒ（赤）、Ｇ（緑）、Ｂ（青）の各波長領域に、それぞれ明確なピーク形状を有する、広色域化に対応した液晶表示装置が開発されている。例えば、量子ドット技術を利用した白色光源、励起光によりＲ（赤）、Ｇ（緑）の領域に明確な発光ピークを有する蛍光体と青色ＬＥＤを用いた蛍光体方式の白色ＬＥＤ光源、３波長方式の白色ＬＥＤ光源、組成式がＫ２ＳｉＦ６：Ｍｎ４＋であるフッ化物蛍光体（「ＫＳＦ」ともいう）等と青色ＬＥＤを用いた白色ＬＥＤ光源等、様々な種類の光源を用いた、広色域化対応の液晶表示装置が開発されている。このような広色域化対応の液晶表示装置の場合、人間の目が認識可能なスペクトルの６０％以上の色を再現することが可能になると言われている。 On the other hand, due to the recent increase in demand for color gamut, the emission spectrum of a white light source has a clear peak shape in each wavelength region of R (red), G (green), and B (blue). Liquid crystal display devices that are compatible with the development have been developed. For example, a white light source using quantum dot technology, a phosphor type white LED light source using a phosphor and a blue LED having a clear emission peak in the R (red) and G (green) regions by excitation light, three wavelengths Various types of light sources were used, such as a white LED light source of the system, a fluoride phosphor (also referred to as “KSF”) whose composition formula is K 2 SiF 6 : Mn 4 +, and a white LED light source using a blue LED. Liquid crystal display devices that support a wide color gamut have been developed. In the case of such a liquid crystal display device that supports a wide color gamut, it is said that it is possible to reproduce colors of 60% or more of the spectrum that can be recognized by the human eye.
　これらの白色光源は、いずれも従来のＹＡＧ系黄色蛍光体を用いた白色発光ダイオードからなる光源と比較してピークの半値幅が狭く、リタデーションを有するポリエチレンテレフタレート系樹脂フィルムを偏光板の構成部材である偏光子保護フィルムとして用いた場合に、光源の種類によっては虹斑が発生する場合があることが新たにわかった。 Each of these white light sources has a narrow peak half-value width compared to a light source composed of a white light-emitting diode using a conventional YAG-based yellow phosphor, and is composed of a polyethylene terephthalate resin film having retardation as a constituent member of a polarizing plate. It was newly found that when used as a polarizer protective film, rainbow spots may occur depending on the type of light source.
　また、偏光子保護フィルムの更なる薄膜化の要望が強くなっており、そのような場合にも、表示画面を斜め方向から観察した場合の虹斑をより抑制することのできるポリエチレンテレフタレート系樹脂フィルム（偏光子保護フィルム）が求められている。 In addition, there is a strong demand for further thinning of the polarizer protective film, and in such a case, a polyethylene terephthalate resin film that can further suppress rainbow spots when the display screen is observed from an oblique direction. (Polarizer protective film) is desired.
　すなわち、本発明では、偏光板の構成部材である偏光子保護フィルムとしてポリエチレンテレフタレート系樹脂フィルムを、広色域化対応の液晶表示装置に使用した場合や、薄膜化した場合にも、虹斑の発生を抑制でき、視認性が改善された液晶表示装置、偏光板、偏光子保護フィルムを提供することを課題とする。 That is, in the present invention, when using a polyethylene terephthalate resin film as a polarizer protective film, which is a constituent member of a polarizing plate, in a liquid crystal display device that supports a wide color gamut or when it is thinned, It is an object of the present invention to provide a liquid crystal display device, a polarizing plate, and a polarizer protective film that can suppress generation and have improved visibility.
　本発明者らは、鋭意検討した結果、ポリエチレンテレフタレート系樹脂フィルムが特定範囲のリタデーションを有していることに加え、剛直非晶分率を一定以上に制御することにより上記課題が解決されることを見出した。 As a result of intensive studies, the present inventors have solved that the above problems can be solved by controlling the rigid amorphous fraction above a certain level in addition to the polyethylene terephthalate resin film having a specific range of retardation. I found.
　代表的な本発明は、以下の通りである。
項１．
下記の（１）及び（２）を満たすポリエチレンテレフタレート系樹脂フィルムからなる偏光子保護フィルム。
（１）リタデーションが３０００ｎｍ以上３００００ｎｍ以下である
（２）次式で表される剛直非晶分率が３３ｗｔ％以上である
       （剛直非晶分率（ｗｔ％））＝１００－（可動非晶分率（ｗｔ％））－（質量分率結晶化度（ｗｔ％））
項２．
前記ポリエチレンテレフタレート系樹脂フィルムが更に下記（３）を満たす、項１に記載の偏光子保護フィルム。
（３）Ｘ線回折で測定した（１００）面のフィルム面に対する配向度が０．７以下である
項３．
偏光子の少なくとも一方の面に項１又は２に記載の偏光子保護フィルムが積層された偏光板。
項４．
バックライト光源、２つの偏光板、及び前記２つの偏光板の間に配された液晶セルを有する液晶表示装置であって、前記２つの偏光板のうち、少なくとも一方が項３に記載の偏光板である、液晶表示装置。 The representative present invention is as follows.
Item 1.
A polarizer protective film comprising a polyethylene terephthalate resin film that satisfies the following (1) and (2).
(1) Retardation is 3000 nm or more and 30000 nm or less (2) Rigid amorphous fraction represented by the following formula is 33 wt% or more (rigid amorphous fraction (wt%)) = 100− (movable amorphous fraction) Rate (wt%))-(mass fraction crystallinity (wt%))
Item 2.
Item 2. The polarizer protective film according to Item 1, wherein the polyethylene terephthalate resin film further satisfies the following (3).
(3) The degree of orientation of the (100) plane with respect to the film plane measured by X-ray diffraction is 0.7 or less.
The polarizing plate by which the polarizer protective film of claim | item 1 or 2 was laminated | stacked on the at least one surface of the polarizer.
Item 4.
A liquid crystal display device having a backlight source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates, wherein at least one of the two polarizing plates is the polarizing plate according to item 3. Liquid crystal display device.
　本発明によれば、偏光板の構成部材である偏光子保護フィルムとしてポリエチレンテレフタレート系樹脂フィルムを、広色域化対応の液晶表示装置に使用した場合や、薄膜化した場合にも、虹斑の発生を抑制でき、視認性が改善された液晶表示装置、偏光板、偏光子保護フィルムを提供することができる。 According to the present invention, when a polyethylene terephthalate-based resin film is used as a polarizer protective film, which is a constituent member of a polarizing plate, in a liquid crystal display device compatible with a wide color gamut, or when it is thinned, rainbow spots Generation | occurence | production can be suppressed and the liquid crystal display device, polarizing plate, and polarizer protective film whose visibility was improved can be provided.
１．偏光子保護フィルム
　本発明の偏光子保護フィルムに用いられるポリエチレンテレフタレート系樹脂フィルムは、３０００ｎｍ以上３００００ｎｍ以下のリタデーションを有することが好ましい。リタデーションが３０００ｎｍ未満では、偏光子保護フィルムとして用いた場合、斜め方向から観察した時に強い干渉色を呈し、良好な視認性を確保することができない。好ましいリタデーションの下限値は４０００ｎｍ、次に好ましい下限値は５０００ｎｍである。 1. Polarizer Protective Film The polyethylene terephthalate resin film used for the polarizer protective film of the present invention preferably has a retardation of 3000 nm or more and 30000 nm or less. When the retardation is less than 3000 nm, when used as a polarizer protective film, a strong interference color is exhibited when observed from an oblique direction, and good visibility cannot be ensured. The preferred lower limit of retardation is 4000 nm, and the next preferred lower limit is 5000 nm.
　一方、リタデーションの上限は３００００ｎｍが好ましい。それ以上のリタデーションを有するポリエチレンテレフタレート系樹脂フィルムを用いたとしても更なる視認性の改善効果は実質的に得られず、フィルムの厚みも相当に厚くなり、工業材料としての取り扱い性が低下する。好ましい上限値は１００００ｎｍであり、より好ましい上限値は９０００ｎｍであり、さらにより好ましい上限値は８０００ｎｍである。 On the other hand, the upper limit of retardation is preferably 30000 nm. Even if a polyethylene terephthalate-based resin film having a retardation higher than that is used, the effect of further improving visibility is not substantially obtained, the thickness of the film is considerably increased, and the handleability as an industrial material is lowered. A preferable upper limit is 10,000 nm, a more preferable upper limit is 9000 nm, and a still more preferable upper limit is 8000 nm.
　リタデーションは、フィルム面内における２軸方向の屈折率とフィルム厚みを測定して求めることもできるし、ＫＯＢＲＡ－２１ＡＤＨ（王子計測機器株式会社）といった市販の自動複屈折測定装置を用いて求めることもできる。屈折率の測定波長は５８９ｎｍで測定する。 Retardation can be obtained by measuring the biaxial refractive index and film thickness in the film plane, or by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments). it can. The measurement wavelength of the refractive index is 589 nm.
　ポリエチレンテレフタレート系樹脂フィルムのフィルム面内における屈折率差（遅相軸方向の屈折率－進相軸方向の屈折率）は、０．０８以上が好ましく、より好ましくは０．０９以上、さらに好ましくは０．１０以上である。前記屈折率差の上限は０．１５以下が好ましい。一方向に強く延伸され、フィルム面内における屈折率差が大きいほうが、虹斑をより抑制する観点から好ましい。なお、遅相軸方向の屈折率及び進相軸方向の屈折率は、アッベ屈折率計（アタゴ社製、ＮＡＲ－４Ｔ、測定波長５８９ｎｍ）によって求める。 The difference in refractive index in the film plane of the polyethylene terephthalate resin film (refractive index in the slow axis direction-refractive index in the fast axis direction) is preferably 0.08 or more, more preferably 0.09 or more, and still more preferably. 0.10 or more. The upper limit of the refractive index difference is preferably 0.15 or less. It is preferable that the film is strongly stretched in one direction and has a large refractive index difference in the film plane from the viewpoint of further suppressing rainbow spots. The refractive index in the slow axis direction and the refractive index in the fast axis direction are determined by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
　本発明の偏光子保護フィルムに用いるポリエチレンテレフタレート系樹脂フィルムは、特定範囲のリタデーションを有することに加え、剛直非晶分率が３３ｗｔ％以上であることが、斜め方向から観察される虹斑を抑制する観点から好ましい。ポリエチレンテレフタレート系樹脂フィルムの剛直非晶分率は３３ｗｔ％以上が好ましく、より好ましくは３４ｗｔ％以上であり、より好ましくは３５ｗｔ％以上であり、さらに好ましくは３６ｗｔ％以上である。上限は６０ｗｔ％が好ましいが、５０ｗｔ％または４５ｗｔ％程度でも十分である。ここで、剛直非晶分率は下記の（１）式で表される。
（剛直非晶分率（ｗｔ％））＝１００－（可動非晶分率（ｗｔ％））－（質量分率結晶化度（ｗｔ％））・・・（１）
なお、本明細書において、ｗｔ％は質量％と同義である。 In addition to having a specific range of retardation, the polyethylene terephthalate resin film used for the polarizer protective film of the present invention has a rigid amorphous fraction of 33 wt% or more, and suppresses rainbow spots observed from an oblique direction. From the viewpoint of The rigid amorphous fraction of the polyethylene terephthalate resin film is preferably 33 wt% or more, more preferably 34 wt% or more, more preferably 35 wt% or more, and further preferably 36 wt% or more. The upper limit is preferably 60 wt%, but about 50 wt% or 45 wt% is sufficient. Here, the rigid amorphous fraction is expressed by the following equation (1).
(Rigid amorphous fraction (wt%)) = 100- (movable amorphous fraction (wt%))-(mass fraction crystallinity (wt%)) (1)
In the present specification, wt% is synonymous with mass%.
　従来、高分子の高次構造は結晶と非晶に分かれていると考えられてきた。しかし近年、非晶領域はその分子運動の温度依存性により更に区別可能であり、ガラス転移点（Ｔｇ）で分子運動が解放される可動非晶と、Ｔｇ以上の温度でも分子運動が凍結された剛直非晶に分けられることが報告されている。この剛直非晶は、ポリエチレンテレフタレートの場合、２００℃近傍の温度まで非晶のまま保持されることが知られている。よって、剛直非晶分率が大きいほど、フィルムの延伸や熱処理に伴う結晶化が進行し難いと考えられる。ポリエチレンテレフタレート系樹脂フィルムでは、厚みやリタデーションが同じ場合には、そのベンゼン環が分子鎖軸まわりにランダムに配向しているほど、偏光子保護フィルムに用いた際に斜め方向から観察される虹斑が抑制される。一方で、ポリエチレンテレフタレート系樹脂フィルムでは、結晶化に伴いベンゼン環がフィルム面に対し平行に配向することが知られている。既知の方法により製膜されたポリエチレンテレフタレート系樹脂フィルムでは、前述のフィルム面内における屈折率差を大きくすると、ベンゼン環のフィルム面に対する配向度も同時に大きくなり、十分な虹斑抑制効果を得ることができない場合があった。本発明者らが検討したところ、剛直非晶分率を上記範囲に制御することで、フィルム面内における屈折率差を大きくした際にも結晶化に伴うベンゼン環の配向を効果的に抑制し、斜め方向から観察される虹斑が抑制可能となることを見出した。 Conventionally, it has been considered that the higher order structure of a polymer is divided into a crystal and an amorphous structure. However, in recent years, the amorphous region can be further distinguished by the temperature dependence of the molecular motion, and the molecular motion is frozen even at temperatures above the Tg and the movable amorphous state where the molecular motion is released at the glass transition point (Tg). It has been reported that it can be divided into rigid amorphous. In the case of polyethylene terephthalate, this rigid amorphous is known to remain amorphous up to a temperature close to 200 ° C. Therefore, it is considered that as the rigid amorphous fraction increases, crystallization associated with film stretching or heat treatment does not proceed easily. In polyethylene terephthalate-based resin films, when the thickness and retardation are the same, the more the benzene rings are oriented randomly around the molecular chain axis, the more rainbow spots are observed from oblique directions when used for a polarizer protective film. Is suppressed. On the other hand, in a polyethylene terephthalate resin film, it is known that a benzene ring is oriented in parallel to the film surface with crystallization. In a polyethylene terephthalate resin film formed by a known method, increasing the refractive index difference in the above-described film plane also increases the degree of orientation of the benzene ring with respect to the film surface, thereby obtaining a sufficient rainbow-spot suppression effect. There was a case that could not be. As a result of studies by the present inventors, by controlling the rigid amorphous fraction within the above range, the orientation of the benzene ring accompanying crystallization is effectively suppressed even when the refractive index difference in the film plane is increased. It has been found that rainbow spots observed from an oblique direction can be suppressed.
　上記（１）式で、剛直非晶分率は、可動非晶分率および質量分率結晶化度の値を用いて間接的に求められる。可動非晶分率は、示差走査熱量計（ＴＡ　Ｉｎｓｔｒｕｍｅｎｔ社製、Ｑ１００）を用いた温度変調ＤＳＣ測定で得られる可逆熱容量曲線のＴｇにおける可逆熱容量差ΔＣｐから求められる。一方、質量分率結晶化度は、ＪＩＳ　Ｋ７１１２に従い密度勾配管を用いて得られた密度の値により算出される。詳細は実施例で後述する。 In the above equation (1), the rigid amorphous fraction is indirectly determined using the values of the movable amorphous fraction and the mass fraction crystallinity. The movable amorphous fraction is determined from the reversible heat capacity difference ΔCp at Tg of the reversible heat capacity curve obtained by temperature modulation DSC measurement using a differential scanning calorimeter (TA Instrument, Q100). On the other hand, the mass fraction crystallinity is calculated from the density value obtained using a density gradient tube in accordance with JIS K7112. Details will be described later in Examples.
　ポリエチレンテレフタレート系樹脂フィルム中のベンゼン環のフィルム面に対する配向度は、ベンゼン環にほぼ平行な（１００）面のフィルム面に対する配向度を指標として評価できる。本発明の偏光子保護フィルムに用いるポリエチレンテレフタレート系樹脂フィルムは、特定範囲のリタデーションを有することに加え、Ｘ線回折で測定した（１００）面のフィルム面に対する配向度が０．７以下であることが斜め方向から観察される虹斑を抑制する観点から好ましい。ポリエチレンテレフタレート系樹脂フィルムの（１００）面のフィルム面に対する配向度は０．７以下が好ましく、より好ましくは０．６８以下であり、より好ましくは０．６６以下であり、さらに好ましくは０．６４以下である。下限は０．４０が好ましい。（１００）面のフィルム面に対する配向度は、ポリエチレンテレフタレートの結晶の分子鎖軸まわりの配向を示す指標であり、この値が低いほど分子鎖軸まわりの配向がランダムであることを表している。この分子鎖軸まわりの配向がランダムであるほど、斜め方向から観察される虹斑が抑制される。 The degree of orientation of the benzene ring in the polyethylene terephthalate-based resin film with respect to the film surface can be evaluated using the degree of orientation of the (100) plane almost parallel to the benzene ring as an index. In addition to having a specific range of retardation, the polyethylene terephthalate resin film used for the polarizer protective film of the present invention has an orientation degree of 0.7 or less with respect to the film surface of the (100) plane measured by X-ray diffraction. Is preferable from the viewpoint of suppressing rainbow spots observed from an oblique direction. The degree of orientation of the (100) plane of the polyethylene terephthalate resin film is preferably 0.7 or less, more preferably 0.68 or less, more preferably 0.66 or less, and still more preferably 0.64. It is as follows. The lower limit is preferably 0.40. The degree of orientation of the (100) plane with respect to the film surface is an index indicating the orientation around the molecular chain axis of the polyethylene terephthalate crystal, and the lower the value, the more random the orientation around the molecular chain axis. The more the orientation around the molecular chain axis is random, the more rainbow spots observed from the oblique direction are suppressed.
　高分子のＸ線回折測定においては、主として結晶により散乱されたＸ線の強度が測定されるが、配向し規則性を有するようになった非晶（配向非晶）により散乱されたＸ線の強度もまた測定値に含まれる。一般に（１００）面とは結晶格子中の特定の結晶面を指すが、前記（１００）面のフィルム面に対する配向度とは、結晶および配向非晶におけるベンゼン環のフィルム面に対する配向度の指標に相当する。 In the X-ray diffraction measurement of polymers, the intensity of X-rays scattered by crystals is mainly measured, but X-rays scattered by amorphous (oriented amorphous) that are oriented and have regularity are measured. Intensity is also included in the measurement. In general, the (100) plane refers to a specific crystal plane in the crystal lattice, but the degree of orientation of the (100) plane relative to the film plane is an index of the degree of orientation of the benzene ring in the crystal and oriented amorphous with respect to the film plane. Equivalent to.
　（１００）面のフィルム面に対する配向度は、Ｘ線回折装置（株式会社リガク社製、ＲＩＮＴ２１００ＰＣ）を用いて、広角Ｘ線回折測定により得られた（１００）面の回折強度プロファイルの半値幅を用いて、下記の式で定義されるパラメーターである。詳細は実施例で後述する。
　（１００）面のフィルム面に対する配向度＝（１８０－半値幅）／１８０ The degree of orientation of the (100) plane with respect to the film plane is the half width of the diffraction intensity profile of the (100) plane obtained by wide-angle X-ray diffraction measurement using an X-ray diffractometer (RINT2100PC, manufactured by Rigaku Corporation). It is a parameter defined by the following formula. Details will be described later in Examples.
Degree of orientation of (100) plane with respect to the film plane = (180−half width) / 180
　本発明の保護フィルムであるポリエチレンテレフタレート系樹脂フィルムは、一般的なポリエステルフィルムの製造方法を利用して製造することができる。例えば、ポリエチレンテレフタレート系樹脂を溶融し、シート状に押出し成形された無配向ポリエチレンテレフタレート系樹脂をガラス転移温度以上の温度において、ロールの速度差を利用して縦方向に延伸した後、テンターにより横方向に延伸し、熱処理を施す方法が挙げられる。 The polyethylene terephthalate resin film, which is a protective film of the present invention, can be manufactured by using a general polyester film manufacturing method. For example, a non-oriented polyethylene terephthalate resin melted from a polyethylene terephthalate resin and extruded into a sheet shape is stretched in the machine direction at a temperature equal to or higher than the glass transition temperature by using a speed difference of a roll, and then stretched by a tenter. The method of extending | stretching to a direction and giving heat processing is mentioned.
　ポリエチレンテレフタレート系樹脂フィルムの製膜条件を具体的に説明すると、縦延伸温度、横延伸温度は１００～１３０℃が好ましく、特に好ましくは１１０～１２５℃である。
フィルム幅方向（ＴＤ方向）に遅相軸を有するフィルムを製造する場合、縦延伸倍率は０．７～１．５倍が好ましく、特に好ましくは０．７倍～１．０倍である。また、延伸中の非晶分子鎖の緩和を抑制し剛直非晶分率を高める観点からは、横延伸倍率は高くすることが好ましい。横延伸倍率の下限は４．５倍が好ましく、より好ましくは４．７倍であり、特に好ましくは５．０倍である。一方、横延伸倍率が７．０倍を超えると、フィルムが横方向に裂けやすくなり生産性が低下する。従って、横延伸倍率の上限は７．０倍が好ましく、より好ましくは６．５倍であり、特に好ましくは６．０倍、最も好ましくは５．５倍である。 The film forming conditions of the polyethylene terephthalate resin film will be specifically described. The longitudinal stretching temperature and the transverse stretching temperature are preferably 100 to 130 ° C, particularly preferably 110 to 125 ° C.
When a film having a slow axis in the film width direction (TD direction) is produced, the longitudinal draw ratio is preferably 0.7 to 1.5 times, particularly preferably 0.7 to 1.0 times. Further, from the viewpoint of suppressing relaxation of the amorphous molecular chain during stretching and increasing the rigid amorphous fraction, it is preferable to increase the transverse stretching ratio. The lower limit of the transverse draw ratio is preferably 4.5 times, more preferably 4.7 times, and particularly preferably 5.0 times. On the other hand, if the transverse draw ratio exceeds 7.0 times, the film tends to tear in the transverse direction and productivity is lowered. Accordingly, the upper limit of the transverse draw ratio is preferably 7.0 times, more preferably 6.5 times, particularly preferably 6.0 times, and most preferably 5.5 times.
　一方、フィルム縦方向（ＭＤ方向）に遅相軸を有するフィルムを製造する場合、横延伸倍率は好ましくは１．０～３．０倍であり、より好ましくは２．０～３．０倍である。延伸中の非晶分子鎖の緩和を抑制し剛直非晶分率を高める観点からは、縦延伸倍率は高くすることが好ましい。縦延伸倍率の下限は４．５倍が好ましく、より好ましくは４．７倍、特に好ましくは５．０倍である。縦延伸倍率が７．０倍を超えると、フィルムが縦方向に裂けやすくなり生産性が低下することから、縦延伸倍率の上限は７．０倍が好ましく、より好ましくは６．５倍、特に好ましくは６．０倍である。 On the other hand, when producing a film having a slow axis in the film longitudinal direction (MD direction), the transverse draw ratio is preferably 1.0 to 3.0 times, more preferably 2.0 to 3.0 times. is there. From the viewpoint of suppressing relaxation of the amorphous molecular chain during stretching and increasing the rigid amorphous fraction, it is preferable to increase the longitudinal stretching ratio. The lower limit of the longitudinal draw ratio is preferably 4.5 times, more preferably 4.7 times, and particularly preferably 5.0 times. If the longitudinal draw ratio exceeds 7.0 times, the film tends to tear in the machine direction and the productivity is lowered. Therefore, the upper limit of the longitudinal draw ratio is preferably 7.0 times, more preferably 6.5 times, particularly Preferably it is 6.0 times.
　リタデーションを上記範囲に制御するためには、縦延伸倍率と横延伸倍率の比率や、延伸温度、フィルムの厚みを制御することが好ましい。縦横の延伸倍率の差が小さすぎるとリタデーションを高くすることが難しくなり好ましくない。 In order to control the retardation within the above range, it is preferable to control the ratio between the longitudinal draw ratio and the transverse draw ratio, the draw temperature, and the film thickness. If the difference between the vertical and horizontal draw ratios is too small, it is difficult to increase the retardation, which is not preferable.
　熱処理時の結晶化に伴うベンゼン環のフィルム面に対する配向を抑制するためには、剛直非晶分率を増大させることが好ましい。具体的には、延伸中の非晶分子鎖の緩和を抑制することが好ましく、フィルムの遅相軸方向への延伸における歪み速度を大きくすることが好ましい。歪み速度は１３％／ｓｅｃ以上が好ましく、より好ましくは１５％／ｓｅｃ以上、特に好ましくは１７％／ｓｅｃ以上である。製膜性の観点から、歪み速度の上限は６０％／ｓｅｃが好ましい。ここで、歪み速度は（遅相軸方向への延伸における公称歪み（％））／（遅相軸方向への延伸における所要時間（ｓｅｃ））で表される量であり、公称歪み（％）は（（変形量（ｍｍ））／（初期長（ｍｍ）））×１００により求められる。 In order to suppress the orientation of the benzene ring with respect to the film surface accompanying crystallization during heat treatment, it is preferable to increase the rigid amorphous fraction. Specifically, it is preferable to suppress relaxation of amorphous molecular chains during stretching, and it is preferable to increase the strain rate in stretching in the slow axis direction of the film. The strain rate is preferably 13% / sec or more, more preferably 15% / sec or more, and particularly preferably 17% / sec or more. From the viewpoint of film formability, the upper limit of the strain rate is preferably 60% / sec. Here, the strain rate is an amount expressed by (nominal strain (%) in stretching in the slow axis direction) / (required time (sec) in stretching in the slow axis direction), and nominal strain (%) Is obtained by ((deformation amount (mm)) / (initial length (mm))) × 100.
　続く熱処理においては、配向結晶化を促進しリタデーションを高める観点から、熱処理温度の下限は１５０℃が好ましく、より好ましくは１６０℃であり、特に好ましくは１７０℃、最も好ましくは１８０℃である。一方、剛直非晶の結晶化を防ぎ、結晶の（１００）面のフィルム面に対する配向度を下げる観点から、熱処理温度の上限は２２０℃が好ましく、より好ましくは２１０℃であり、特に好ましくは２００℃である。 In the subsequent heat treatment, from the viewpoint of promoting oriented crystallization and increasing retardation, the lower limit of the heat treatment temperature is preferably 150 ° C, more preferably 160 ° C, particularly preferably 170 ° C, and most preferably 180 ° C. On the other hand, the upper limit of the heat treatment temperature is preferably 220 ° C., more preferably 210 ° C., and particularly preferably 200 from the viewpoint of preventing rigid crystallization and reducing the degree of orientation of the (100) plane of the crystal with respect to the film surface. ° C.
　ポリエチレンテレフタレート系樹脂フィルムを構成するポリエチレンテレフタレート系樹脂は、モノマーユニットの８５モル％以上がエチレンテレフタレートであることが好ましい。エチレンテレフタレート単位は９０モル％以上が好ましく、より好ましくは９５モル％以上である。なお、共重合成分としては、公知の酸成分、グリコール成分を含んでもよい。ポリエチレンテレフタレート系樹脂として、特に好ましいものは、ホモポリマーであるポリエチレンテレフタレートである。 In the polyethylene terephthalate resin constituting the polyethylene terephthalate resin film, 85 mol% or more of the monomer units are preferably ethylene terephthalate. The ethylene terephthalate unit is preferably 90 mol% or more, more preferably 95 mol% or more. In addition, as a copolymerization component, you may contain a well-known acid component and a glycol component. A particularly preferable polyethylene terephthalate resin is polyethylene terephthalate which is a homopolymer.
　これらの樹脂は透明性に優れるとともに、熱的、機械的特性にも優れており、延伸加工によって容易にリタデーションを制御することができる。ポリエチレンテレフタレートは、固有複屈折が大きく、フィルムの厚みが薄くても比較的容易に大きなリタデーションが得ることができ、最も好適な素材である。 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 can easily obtain a large retardation even when the film is thin.
　また、ヨウ素色素などの光学機能性色素の劣化を抑制することを目的として、本発明の保護フィルムは、波長３８０ｎｍの光線透過率が２０％以下であることが望ましい。３８０ｎｍの光線透過率は１５％以下がより好ましく、１０％以下がさらに好ましく、５％以下が特に好ましい。前記光線透過率が２０％以下であれば、光学機能性色素の紫外線による変質を抑制することができる。なお、本発明における透過率は、フィルムの平面に対して垂直方法に測定したものであり、分光光度計（例えば、日立Ｕ－３５００型）を用いて測定することができる。 Also, for the purpose of suppressing deterioration of optical functional dyes such as iodine dyes, the protective film of the present invention desirably 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).
　本発明の保護フィルムの波長３８０ｎｍの透過率を２０％以下にするためには、紫外線吸収剤の種類、濃度、及びフィルムの厚みを適宜調節することが望ましい。本発明で使用される紫外線吸収剤は公知の物質である。紫外線吸収剤としては、有機系紫外線吸収剤と無機系紫外線吸収剤が挙げられるが、透明性の観点から有機系紫外線吸収剤が好ましい。有機系紫外線吸収剤としては、ベンゾトリアゾール系、ベンゾフェノン系、環状イミノエステル系等、及びその組み合わせが挙げられるが本発明の規定する吸光度の範囲であれば特に限定されない。しかし、耐久性の観点からはベンゾトリアゾール系、環状イミノエステル系が特に好ましい。２種以上の紫外線吸収剤を併用した場合には、別々の波長の紫外線を同時に吸収させることができるので、より紫外線吸収効果を改善することができる。 In order to reduce the transmittance at a wavelength of 380 nm of the protective film of the present invention to 20% or less, it is desirable to appropriately adjust the type, concentration, and thickness of the ultraviolet absorber. 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. Examples of the organic ultraviolet absorber include benzotriazole, benzophenone, cyclic imino ester, and combinations thereof, but are not particularly limited as long as the absorbance is within the range defined by the present invention. However, from the viewpoint of durability, benzotriazole type and cyclic imino ester type 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.
　ベンゾフェノン系紫外線吸収剤、ベンゾトリアゾール系紫外線吸収剤、アクリロニトリル系紫外線吸収剤としては例えば２－［２'－ヒドロキシ－５' －（メタクリロイルオキシメチル）フェニル］－２Ｈ－ベンゾトリアゾール、２－［２' －ヒドロキシ－５' －（メタクリロイルオキシエチル）フェニル］－２Ｈ－ベンゾトリアゾール、２－［２' －ヒドロキシ－５' －（メタクリロイルオキシプロピル）フェニル］－２Ｈ－ベンゾトリアゾール、２，２'－ジヒドロキシ－４，４'－ジメトキシベンゾフェノン、２，２'，４，４'－テトラヒドロキシベンゾフェノン、２，４－ジ－ｔｅｒｔ－ブチル－６－（５－クロロベンゾトリアゾール－２－イル）フェノール、２－（２'－ヒドロキシ－３'－ｔｅｒｔ－ブチル－５'－メチルフェニル）－５－クロロベンゾトリアゾール、２－（５－クロロ（２Ｈ）－ベンゾトリアゾール－２－イル）－４－メチル－６－（ｔｅｒｔ－ブチル）フェノール、２，２'－メチレンビス（４－（１，１，３，３－テトラメチルブチル）－６－（２Ｈ－ベンゾトリアゾール－２－イル）フェノールなどが挙げられる。環状イミノエステル系紫外線吸収剤としては例えば２，２’－（１，４－フェニレン）ビス（４Ｈ－３，１－ベンズオキサジノン－４－オン）、２－メチル－３，１－ベンゾオキサジン－４－オン、２－ブチル－３，１－ベンゾオキサジン－４－オン、２－フェニル－３，１－ベンゾオキサジン－４－オンなどが挙げられる。しかし特にこれらに限定されるものではない。 Examples of the benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber and acrylonitrile ultraviolet absorber 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) 5-chlorobenzotriazole, 2- (5-chloro (2H) -benzotriazol-2-yl) -4-methyl-6- (tert-butyl) phenol, 2,2′-methylenebis (4- (1,1 , 3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol, etc. Examples of cyclic imino ester UV absorbers include 2,2 ′-(1,4-phenylene). Bis (4H-3,1-benzoxazinon-4-one), 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazin-4-one, 2-phenyl -3,4-benzoxazin-4-one, etc., but is not particularly limited thereto.
　また、紫外線吸収剤以外に、本発明の効果を妨げない範囲で、触媒以外の各種の添加剤を含有させることも好ましい様態である。添加剤として、例えば、無機粒子、耐熱性高分子粒子、アルカリ金属化合物、アルカリ土類金属化合物、リン化合物、帯電防止剤、耐光剤、難燃剤、熱安定剤、酸化防止剤、ゲル化防止剤、界面活性剤等が挙げられる。また、高い透明性を奏するためにはポリエチレンテレフタレート系樹脂フィルムに実質的に粒子を含有しないことも好ましい。「粒子を実質的に含有させない」とは、例えば無機粒子の場合、ケイ光Ｘ線分析で無機元素を定量した場合に５０ｐｐｍ以下、好ましくは１０ｐｐｍ以下、特に好ましくは検出限界以下となる含有量を意味する。 In addition to the ultraviolet absorber, it is also preferable to include various additives other than the catalyst as long as the effects of the present invention are not hindered. Examples of 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. In order to achieve high transparency, it is preferable that the polyethylene terephthalate resin film does not substantially contain particles. “Substantially free of particles” means, for example, in the case of inorganic particles, a content that is 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less when inorganic elements are quantified by fluorescent X-ray analysis. means.
　また、本発明におけるポリエチレンテレフタレート系樹脂フィルムに紫外線吸収剤を配合する方法としては、公知の方法を組み合わせて採用し得るが、例えば予め混練押出機を用い、乾燥させた紫外線吸収剤とポリマー原料とをブレンドしマスターバッチを作製しておき、フィルム製膜時に所定の該マスターバッチとポリマー原料を混合する方法などによって配合することができる。 In addition, as a method of blending the ultraviolet absorber with the polyethylene terephthalate resin film in the present invention, a known method can be used in combination. For example, the ultraviolet absorber and the polymer raw material that have been dried using a kneading extruder in advance are used. Can be blended by, for example, a method of mixing a predetermined master batch and a polymer raw material at the time of film formation.
　この時マスターバッチの紫外線吸収剤濃度は紫外線吸収剤を均一に分散させ、且つ経済的に配合するために５～３０質量％の濃度にするのが好ましい。マスターバッチを作製する条件としては混練押出機を用い、押し出し温度はポリエチレンテレフタレート系原料の融点以上、２９０℃以下の温度で１～１５分間で押し出すのが好ましい。２９０℃以上では紫外線吸収剤の減量が大きく、また、マスターバッチの粘度低下が大きくなる。押し出し時間１分以下では紫外線吸収剤の均一な混合が困難となる。この時、必要に応じて安定剤、色調調整剤、帯電防止剤を添加しても良い。 At this time, 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. As a condition for producing the master batch, a kneading extruder is used, and the extrusion temperature is preferably from 1 to 15 minutes at a temperature not lower than the melting point of the polyethylene terephthalate raw material and not higher than 290 ° C. Above 290 ° C, the weight loss of the UV absorber is large, and the viscosity of the master batch is greatly reduced. If the extrusion time is 1 minute or less, uniform mixing of the UV absorber becomes difficult. At this time, if necessary, a stabilizer, a color tone adjusting agent, and an antistatic agent may be added.
　また、本発明ではフィルムを少なくとも３層以上の多層構造とし、フィルムの中間層に紫外線吸収剤を添加することが好ましい。中間層に紫外線吸収剤を含む３層構造のフィルムは、具体的には次のように作製することができる。外層用としてポリエチレンテレフタレート系樹脂のペレット単独、中間層用として紫外線吸収剤を含有したマスターバッチとポリエチレンテレフタレート系樹脂のペレットを所定の割合で混合し、乾燥したのち、公知の溶融積層用押出機に供給し、スリット状のダイからシート状に押出し、キャスティングロール上で冷却固化せしめて未延伸フィルムを作る。すなわち、２台以上の押出機、３層のマニホールドまたは合流ブロック（例えば角型合流部を有する合流ブロック）を用いて、両外層を構成するフィルム層、中間層を構成するフィルム層を積層し、口金から３層のシートを押し出し、キャスティングロールで冷却して未延伸フィルムを作る。なお、発明では、光学欠点の原因となる、原料のポリエチレンテレフタレート系樹脂中に含まれている異物を除去するため、溶融押し出しの際に高精度濾過を行うことが好ましい。溶融樹脂の高精度濾過に用いる濾材の濾過粒子サイズ（初期濾過効率９５％）は、１５μｍ以下が好ましい。濾材の濾過粒子サイズが１５μｍを超えると、２０μｍ以上の異物の除去が不十分となりやすい。 In the present invention, it is preferable that the 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. Polyethylene terephthalate resin pellets alone for the outer layer, master batches containing UV absorbers for the intermediate layer and polyethylene terephthalate resin pellets are mixed at a predetermined ratio, dried, and then fed to a known melt laminating extruder. The unstretched film is produced by feeding, extruding into a sheet from a slit-shaped die, and cooling and solidifying on a casting roll. That is, using two or more extruders, 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. In the invention, in order to remove foreign substances contained in the raw material polyethylene terephthalate resin, which cause optical defects, it is preferable to perform high-precision filtration during melt extrusion. The filter particle size (initial filtration efficiency 95%) of the filter medium used for high-precision filtration of the molten resin is preferably 15 μm or less. When the filter particle size of the filter medium exceeds 15 μm, removal of foreign matters of 20 μm or more tends to be insufficient.
　さらに、本発明のポリエチレンテレフタレート系樹脂フィルムには、偏光子との接着性を良好にするためにコロナ処理、コーティング処理や火炎処理等を施したりすることも可能である。 Furthermore, the polyethylene terephthalate resin film of the present invention can be subjected to corona treatment, coating treatment, flame treatment, etc. in order to improve the adhesion to the polarizer.
　本発明においては、偏光子との接着性を改良のために、本発明のフィルムの少なくとも片面に、ポリエステル樹脂、ポリウレタン樹脂またはポリアクリル樹脂の少なくとも１種類を主成分とする易接着層を有することが好ましい。ここで、「主成分」とは易接着層を構成する固形成分のうち５０質量％以上である成分をいう。本発明の易接着層の形成に用いる塗布液は、水溶性又は水分散性の共重合ポリエステル樹脂、アクリル樹脂及びポリウレタン樹脂の内、少なくとも１種を含む水性塗布液が好ましい。これらの塗布液としては、例えば、特許第３５６７９２７号公報、特許第３５８９２３２号公報、特許第３５８９２３３号公報、特許第３９００１９１号公報、特許第４１５０９８２号公報等に開示された水溶性又は水分散性共重合ポリエステル樹脂溶液、アクリル樹脂溶液、ポリウレタン樹脂溶液等が挙げられる。 In the present invention, in order to improve the adhesion to the polarizer, at least one surface of the film of the present invention has an easy-adhesion layer mainly composed of at least one of a polyester resin, a polyurethane resin or a polyacrylic resin. Is preferred. Here, 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 of the present invention is preferably an aqueous coating solution containing at least one of water-soluble or water-dispersible copolymerized polyester resin, acrylic resin, and polyurethane resin. Examples of these 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. Examples thereof include a polymerized polyester resin solution, an acrylic resin solution, and a polyurethane resin solution.
　易接着層は、前記塗布液を縦方向の１軸延伸フィルムの片面または両面に塗布した後、１００～１５０℃で乾燥し、さらに横方向に延伸して得ることができる。最終的な易接着層の塗布量は、０．０５～０．２ｇ／ｍ２に管理することが好ましい。塗布量が０．０５ｇ／ｍ２を著しく下回ると、得られる偏光子との接着性が不十分となる場合がある。一方、塗布量が０．２ｇ／ｍ２を著しく超えると、耐ブロッキング性が低下する場合がある。ポリエチレンテレフタレート系樹脂フィルムの両面に易接着層を設ける場合は、両面の易接着層の塗布量は、同じであっても異なっていてもよく、それぞれ独立して上記範囲内で設定することができる。 The easy-adhesion layer can be obtained by applying the coating solution on one or both sides of a uniaxially stretched film in the longitudinal direction, 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 0.2 g / m 2 . If the coating amount is significantly less than 0.05 g / m 2 , adhesion with the obtained polarizer may be insufficient. On the other hand, if the coating amount significantly exceeds 0.2 g / m 2 , blocking resistance may be lowered. When providing an easy-adhesion layer on both surfaces of the polyethylene terephthalate resin film, the coating amount of the easy-adhesion layers on both surfaces may be the same or different, and can be independently set within the above range. .
　易接着層には易滑性を付与するために粒子を添加することが好ましい。微粒子の平均粒径は２μｍ以下の粒子を用いることが好ましい。粒子の平均粒径が２μｍを著しく超えると、粒子が被覆層から脱落しやすくなる。易接着層に含有させる粒子としては、例えば、酸化チタン、硫酸バリウム、炭酸カルシウム、硫酸カルシウム、シリカ、アルミナ、タルク、カオリン、クレー、リン酸カルシウム、雲母、ヘクトライト、ジルコニア、酸化タングステン、フッ化リチウム、フッ化カルシウム等の無機粒子や、スチレン系、アクリル系、メラミン系、ベンゾグアナミン系、シリコーン系等の有機ポリマー系粒子等が挙げられる。これらは、単独で易接着層に添加されてもよく、２種以上を組合せて添加することもできる。 It is preferable to add particles to the easy-adhesion layer in order to impart slipperiness. It is preferable to use particles having an average particle size of 2 μm or less. When the average particle diameter of the particles significantly exceeds 2 μm, the particles easily fall off from the coating layer. As 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.
　また、塗布液を塗布する方法としては、公知の方法を用いることができる。例えば、リバースロール・コート法、グラビア・コート法、キス・コート法、ロールブラッシュ法、スプレーコート法、エアナイフコート法、ワイヤーバーコート法、パイプドクター法、などが挙げられ、これらの方法を単独であるいは組み合わせて行うことができる。 Further, as a method for applying the coating solution, a known method can be used. For example, 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. can be mentioned. Or it can carry out in combination.
　なお、上記の粒子の平均粒径の測定は次の方法により行う。粒子を走査型電子顕微鏡（ＳＥＭ）で写真を撮り、最も小さい粒子１個の大きさが２～５ｍｍとなるような倍率で、３００～５００個の粒子の最大径（最も離れた２点間の距離）を測定し、その平均値を平均粒径とする。 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 at a magnification such that the size of one smallest particle is 2-5 mm, the maximum diameter of 300-500 particles (between the two most distant points) Distance) is measured, and the average value is taken as the average particle diameter.
　本発明のポリエチレンテレフタレート系樹脂フィルムの厚みは任意であるが、３０～３００μｍの範囲が好ましく、より好ましくは４０～２００μｍの範囲である。３０μｍを下回る厚みのフィルムでも、原理的には３０００ｎｍ以上のリタデーションを得ることは可能である。しかし、その場合にはフィルムの力学特性の異方性が顕著となり、裂け、破れ等を生じやすくなり、工業材料としての実用性が著しく低下する。特に好ましい厚みの下限は４５μｍである。一方、偏光子保護フィルムの厚みの上限は、３００μｍを超えると偏光板の厚みが厚くなりすぎてしまい好ましくない。偏光子保護フィルムとしての実用性の観点からは厚みの上限は１２０μｍが好ましく、より好ましくは１００μｍ以下、さらにより好ましくは８０μｍ以下、さらにより好ましくは６５μｍ以下、さらにより好ましくは６０μｍ以下、さらにより好ましくは５５μｍ以下である。一般に、薄膜化の観点からは、偏光子保護フィルムの厚みは３０～６５μｍの範囲とすることが好ましい。 The thickness of the polyethylene terephthalate resin film of the present invention is arbitrary, but is preferably in the range of 30 to 300 μm, more preferably in the range of 40 to 200 μm. Even in the case of a film having a thickness of less than 30 μm, it is possible in principle to obtain a retardation of 3000 nm or more. 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 45 μm. On the other hand, if the upper limit of the thickness of the polarizer protective film exceeds 300 μm, the thickness of the polarizing plate becomes too thick, which is not preferable. From the viewpoint of practicality as a polarizer protective film, the upper limit of the thickness is preferably 120 μm, more preferably 100 μm or less, still more preferably 80 μm or less, even more preferably 65 μm or less, even more preferably 60 μm or less, and even more preferably. Is 55 μm or less. In general, from the viewpoint of thinning, the thickness of the polarizer protective film is preferably in the range of 30 to 65 μm.
　リタデーションの変動を抑制する為には、フィルムの厚み斑が小さいことが好ましい。延伸温度、延伸倍率はフィルムの厚み斑に大きな影響を与えることから、厚み斑の観点からも製膜条件の最適化を行う必要がある。特にリタデーションを高くするために縦延伸倍率を低くすると、縦厚み斑が悪くなることがある。縦厚み斑は延伸倍率のある特定の範囲で非常に悪くなる領域があることから、この範囲を外したところで製膜条件を設定することが望ましい。 In order to suppress the fluctuation of retardation, it is preferable that the thickness unevenness of the 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, if the longitudinal stretching ratio is lowered to increase the retardation, the longitudinal thickness unevenness may be deteriorated. Since there is a region where the vertical thickness unevenness becomes very bad in a specific range of the draw ratio, it is desirable to set the film forming conditions outside this range.
　本発明のフィルムの厚み斑は５．０％以下であることが好ましく、４．５％以下であることがさらに好ましく、４．０％以下であることがよりさらに好ましく、３．０％以下であることが特に好ましい。 The thickness unevenness of the film of the present invention is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. It is particularly preferred.
　偏光子保護フィルムに用いるポリエチレンテレフタレート系樹脂フィルムは、｜ｎｙ－ｎｚ｜／｜ｎｙ－ｎｘ｜で表されるＮｚ係数が１．７以下であることが好ましい。Ｎｚ係数は次のようにして求めることができる。分子配向計（王子計測器株式会社製、ＭＯＡ－６００４型分子配向計）を用いてフィルムの配向軸方向を求め、配向軸方向とこれに直交する方向の二軸の屈折率（ｎｙ、ｎｘ、但しｎｙ＞ｎｘ）、及び厚さ方向の屈折率（ｎｚ）をアッベ屈折率計（アタゴ社製、ＮＡＲ－４Ｔ、測定波長５８９ｎｍ）によって求める。こうして求めたｎｘ、ｎｙ、ｎｚを、｜ｎｙ－ｎｚ｜／｜ｎｙ－ｎｘ｜で表される式に代入して、Ｎｚ係数を求めることができる。Ｎｚ係数はより好ましくは１．６５以下、さらに好ましくは１．６３以下である。Ｎｚ係数の下限値は、１．２である。また、フィルムの機械的強度を保つためには、Ｎｚ係数の下限値は１．３以上が好ましく、より好ましくは１．４以上、さらに好ましくは１．４５以上である。 The polyethylene terephthalate resin film used for the polarizer protective film preferably has an Nz coefficient represented by | ny-nz | / | ny-nx | of 1.7 or less. The Nz coefficient can be obtained as follows. The orientation axis direction 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, However, ny> nx) and the refractive index (nz) in the thickness direction are determined by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm). The Nz coefficient can be obtained by substituting nx, ny, and nz obtained in this way into an expression represented by | ny−nz | / | ny−nx |. The Nz coefficient is more preferably 1.65 or less, and still more preferably 1.63 or less. The lower limit value of the Nz coefficient is 1.2. In order to maintain the mechanical strength of the film, the lower limit value of the Nz coefficient is preferably 1.3 or more, more preferably 1.4 or more, and further preferably 1.45 or more.
　ポリエチレンテレフタレート系樹脂フィルムは、そのリタデーション（Ｒｅ）と厚さ方向リタデーション（Ｒｔｈ）の比（Ｒｅ／Ｒｔｈ）が、好ましくは０．２以上、より好ましくは０．５以上、さらに好ましくは０．６以上である。上記比（Ｒｅ／Ｒｔｈ）が大きいほど好ましい。上限は２．０以下が好ましく、より好ましくは１．８以下である。なお、厚さ方向リタデーションとは、フィルム厚さ方向断面から見たときの２つの複屈折△Ｎｘｚ（＝｜ｎｘ－ｎｚ｜）、△Ｎｙｚ（＝｜ｎｙ－ｎｚ｜）にそれぞれフィルム厚さｄを掛けて得られるリタデーションの平均を示すパラメーターである。ｎｘ、ｎｙ、ｎｚとフィルム厚みｄ（ｎｍ）を求め、（△Ｎｘｚ×ｄ）と（△Ｎｙｚ×ｄ）との平均値を算出して厚さ方向リタデーション（Ｒｔｈ）を求めることができる。なお、ｎｘ、ｎｙ、ｎｚは、アッベ屈折率計（アタゴ社製、ＮＡＲ－４Ｔ、測定波長５８９ｎｍ）によって求める。 The polyethylene terephthalate resin film has a ratio (Re / Rth) of retardation (Re) to thickness direction retardation (Rth) of preferably 0.2 or more, more preferably 0.5 or more, and still more preferably 0.6. That's it. The larger the ratio (Re / Rth), the better. The upper limit is preferably 2.0 or less, more preferably 1.8 or less. The thickness direction retardation means two birefringences ΔNxz (= | nx−nz |) and ΔNyz (= | ny−nz |) when viewed from the cross section in the film thickness direction. Is a parameter indicating the average retardation obtained by multiplying by. The thickness direction retardation (Rth) can be determined by calculating nx, ny, nz and the film thickness d (nm) and calculating the average value of (ΔNxz × d) and (ΔNyz × d). In addition, nx, ny, and nz are obtained by an Abbe refractometer (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
２．偏光板
　本発明の偏光板は、ポリビニルアルコール（ＰＶＡ）などにヨウ素を染着させた偏光子の少なくとも一方の面に偏光子保護フィルムを貼り合わせた構造を有し、いずれかの偏光子保護フィルムが前述した本発明の偏光子保護フィルムであることが好ましい。他方の偏光子保護フィルムには、ＴＡＣフィルムやアクリルフィルム、ノルボルネン系フィルムに代表されるような複屈折が無いフィルムを用いることが好ましい。また、他方の偏光子保護フィルムは必ずしも存在する必要はない。本発明に用いられる偏光板には、写り込み防止やギラツキ抑制、キズ抑制などを目的として、種々のハードコートを表面に塗布することも好ましい様態である。 2. Polarizing plate The polarizing plate of the present invention has a structure in which a polarizer protective film is bonded to at least one surface of a polarizer in which polyvinyl alcohol (PVA) or the like is dyed with iodine. Is preferably the above-described polarizer protective film of the present invention. As the other polarizer protective film, it is preferable to use a film having no birefringence such as a TAC film, an acrylic film, and a norbornene-based film. Moreover, the other polarizer protective film does not necessarily need to exist. For the polarizing plate used in the present invention, it is also preferable to apply various hard coats on the surface for the purpose of preventing reflection, suppressing glare, and suppressing scratches.
３．液晶表示装置
　一般に、液晶パネルは、バックライト光源に対向する側から画像を表示する側（視認側）に向かう順に、後面モジュール、液晶セルおよび前面モジュールから構成されている。後面モジュールおよび前面モジュールは、一般に、透明基板と、その液晶セル側表面に形成された透明導電膜と、その反対側に配置された偏光板とから構成されている。ここで、偏光板は、後面モジュールでは、バックライト光源に対向する側に配置され、前面モジュールでは、画像を表示する側（視認側）に配置されている。 3. 2. Liquid Crystal Display Device Generally, a liquid crystal panel includes a rear module, a liquid crystal cell, and a front module in order from the side facing the backlight light source toward the image display side (viewing 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. Here, the polarizing plate is arranged on the side facing the backlight light source in the rear module, and is arranged on the side (viewing side) displaying the image in the front module.
　本発明の液晶表示装置は少なくとも、バックライト光源と、２つの偏光板の間に配された液晶セルとを構成部材とする。また、これら以外の他の構成、例えばカラーフィルター、レンズフィルム、拡散シート、反射防止フィルムなどを適宜有しても構わない。前記２つの偏光板のうち、少なくとも一方の偏光板が前述した本発明の偏光板であることが好ましい。 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. Of the two polarizing plates, at least one polarizing plate is preferably the polarizing plate of the present invention described above.
　バックライトの構成としては、導光板や反射板などを構成部材とするエッジライト方式であっても、直下型方式であっても構わない。 The configuration of the backlight may be an edge light method using a light guide plate or a reflection plate as a constituent member, or a direct type.
　液晶表示装置のバックライト光源としては、特に限定されないが、蛍光体方式の白色ＬＥＤが好ましい。すなわち化合物半導体を使用した青色光、もしくは紫外光を発する発光ダイオードと蛍光体を組み合わせることにより白色を発する素子のことである。蛍光体としては、イットリウム・アルミニウム・ガーネット系の黄色蛍光体やテルビウム・アルミニウム・ガーネット系の黄色蛍光体等がある。 The backlight light source of the liquid crystal display device is not particularly limited, but a phosphor type white LED is preferable. That is, it 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. Examples of the phosphor include yttrium / aluminum / garnet yellow phosphor and terbium / aluminum / garnet yellow phosphor.
　また、バックライト光源としては、４００ｎｍ以上４９５ｎｍ未満、４９５ｎｍ以上６００ｎｍ未満、及び６００ｎｍ以上７８０ｎｍ以下の各波長領域にそれぞれ発光スペクトルのピークトップを有する白色光源も好ましい。例えば、量子ドット技術を利用した白色光源、励起光によりＲ（赤）、Ｇ（緑）の領域にそれぞれ発光ピークを有する蛍光体と青色ＬＥＤを用いた蛍光体方式の白色ＬＥＤ光源、３波長方式の白色ＬＥＤ光源、赤色レーザーを組み合わせた白色ＬＥＤ光源、その他、例えば組成式がＫ２ＳｉＦ６：Ｍｎ４＋であるフッ化物蛍光体（「ＫＳＦ」ともいう）等と青色ＬＥＤを用いた白色ＬＥＤ光源等が挙げられる。これらは、広色域対応の液晶表示装置のバックライト光源として注目されているものである。 Moreover, as a backlight light source, the white light source which has the peak top of an emission spectrum in each wavelength range of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less is also preferable. For example, a white light source using quantum dot technology, a phosphor type white LED light source using a phosphor and a blue LED each having an emission peak in the R (red) and G (green) regions by excitation light, and a three-wavelength method White LED light source, white LED light source combined with red laser, and other white LED using blue LED and fluoride phosphor (also referred to as “KSF”) whose composition formula is K 2 SiF 6 : Mn 4 + Examples include a light source. These are attracting attention as backlight light sources for liquid crystal display devices that support a wide color gamut.
　当該特定のリタデーションを有する本発明の偏光子保護フィルムの液晶表示装置内における配置は特に限定されないが、入射光側（光源側）に配される偏光板と、液晶セルと、出射光側（視認側）に配される偏光板とを配された液晶表示装置の場合、入射光側に配される偏光板の入射光側の偏光子保護フィルム、及び／又は出射光側に配される偏光板の射出光側の偏光子保護フィルムが当該特定のリタデーションを有するポリエチレンテレフタレート系樹脂フィルムからなる偏光子保護フィルムであることが好ましい。特に好ましい態様は、出射光側に配される偏光板の射出光側の偏光子保護フィルムを当該特定のリタデーションを有するポリエチレンテレフタレート系樹脂フィルムとする態様である。上記以外の位置にポリエチレンテレフタレート系樹脂フィルムを配する場合は、液晶セルの偏光特性を変化させてしまう場合がある。偏光特性が必要とされる箇所には本発明の高分子フィルムを用いることは好ましくない為、このような特定の位置の偏光板の保護フィルムとして使用されることが好ましい。 The arrangement of the polarizer protective film of the present invention having the specific retardation in the liquid crystal display device is not particularly limited. However, the polarizing plate disposed on the incident light side (light source side), the liquid crystal cell, and the outgoing light side (visible) In the case of a liquid crystal display device provided with a polarizing plate arranged on the side), a polarizer protective film on the incident light side of the polarizing plate arranged on the incident light side and / or a polarizing plate arranged on the outgoing light side It is preferable that the polarizer protective film on the emission light side is a polarizer protective film made of a polyethylene terephthalate resin film having the specific retardation. A particularly preferred embodiment is an embodiment in which the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side is a polyethylene terephthalate resin film having the specific retardation. When a polyethylene terephthalate resin film is disposed at a position other than the above, the polarization characteristics of the liquid crystal cell may be changed. Since it is not preferable to use the polymer film of the present invention at a place where polarization characteristics are required, it is preferably used as a protective film for a polarizing plate at such a specific position.
　以下、実施例を挙げて本発明をより具体的に説明するが、本発明は、下記実施例によって制限を受けるものではなく、本発明の趣旨に適合し得る範囲で適宜変更を加えて実施することも可能であり、それらは、いずれも本発明の技術的範囲に含まれる。なお、以下の実施例における物性の評価方法は以下の通りである。 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and is implemented with appropriate modifications within a range that can be adapted to the gist of the present invention. These are all included in the technical scope of the present invention. In addition, the evaluation method of the physical property in the following examples is as follows.
（１）リタデーション（Ｒｅ）
　リタデーションとは、フィルム上の直交する二軸の屈折率の異方性（△Ｎｘｙ＝｜ｎｘ－ｎｙ｜）とフィルム厚みｄ（ｎｍ）との積（△Ｎｘｙ×ｄ）で定義されるパラメーターであり、光学的等方性、異方性を示す尺度である。二軸の屈折率の異方性（△Ｎｘｙ）は、以下の方法により求めた。分子配向計（王子計測器株式会社製、ＭＯＡ－６００４型分子配向計）を用いて、フィルムの遅相軸方向を求め、遅相軸方向が測定用サンプル長辺と平行になるように、４ｃｍ×２ｃｍの長方形を切り出し、測定用サンプルとした。このサンプルについて、直交する二軸の屈折率（遅相軸方向の屈折率：ｎｙ，遅相軸方向と直交する方向の屈折率：ｎｘ）、及び厚さ方向の屈折率（ｎｚ）をアッベ屈折率計（アタゴ社製、ＮＡＲ－４Ｔ、測定波長５８９ｎｍ）によって求め、前記二軸の屈折率差の絶対値（｜ｎｘ－ｎｙ｜）を屈折率の異方性（△Ｎｘｙ）とした。フィルムの厚みｄ（ｎｍ）は電気マイクロメータ（ファインリューフ社製、ミリトロン１２４５Ｄ）を用いて測定し、単位をｎｍに換算した。屈折率の異方性（△Ｎｘｙ）とフィルムの厚みｄ（ｎｍ）の積（△Ｎｘｙ×ｄ）より、リタデーション（Ｒｅ）を求めた。 (1) Retardation (Re)
Retardation is a parameter defined by the product (ΔNxy × d) of the biaxial refractive index anisotropy (ΔNxy = | nx−ny |) on the film and the film thickness d (nm). Yes, it is a scale showing optical isotropy and anisotropy. The biaxial refractive index anisotropy (ΔNxy) 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. A rectangle of × 2 cm was cut out and used as a measurement sample. For this sample, Abbe refracts the biaxial refractive index (refractive index in the slow axis direction: ny, refractive index in the direction perpendicular to the slow axis direction: nx), and refractive index (nz) in the thickness direction. The absolute value (| nx−ny |) of the biaxial refractive index difference was determined as a refractive index anisotropy (ΔNxy), 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 (ΔNxy × d) of refractive index anisotropy (ΔNxy) and film thickness d (nm).
（２）剛直非晶分率
　剛直非晶分率は、前記（１）式で表され、可動非晶分率および質量分率結晶化度の値から間接的に算出される。
　可動非晶分率は、示差走査熱量計（ＴＡ　Ｉｎｓｔｒｕｍｅｎｔ社製、Ｑ１００）を用いた温度変調ＤＳＣ測定により得られた可逆熱容量曲線のＴｇにおける可逆熱容量差ΔＣｐ（Ｊ／（ｇ・Ｋ））を用いて下記式で定義されるパラメーターである。
　　可動非晶分率＝（（試料のΔＣｐ）／（完全非晶のΔＣｐ））×１００（ｗｔ％）
ポリエチレンテレフタレートの場合、完全非晶のΔＣｐ＝０．４０５２（Ｊ／（ｇ・Ｋ））である。試料はアルミニウムパン内に２．０±０．２ｍｇで秤量し、ＭＤＳＣ（登録商標）ヒートオンリーモードで、平均昇温速度５．０℃／ｍｉｎ、変調周期６０ｓｅｃで測定した。測定データは５Ｈｚのサンプリング周波数で収集した。また、温度および熱量の校正にはインジウムを、比熱の校正にはサファイアを用いた。 (2) Rigid amorphous fraction The rigid amorphous fraction is expressed by the above formula (1) and is indirectly calculated from the values of the movable amorphous fraction and the mass fraction crystallinity.
The movable amorphous fraction is the reversible heat capacity difference ΔCp (J / (g · K)) at the Tg of the reversible heat capacity curve obtained by temperature modulation DSC measurement using a differential scanning calorimeter (TA Instrument, Q100). It is a parameter defined by the following formula.
Movable amorphous fraction = ((ΔCp of sample) / (ΔCp of completely amorphous)) × 100 (wt%)
In the case of polyethylene terephthalate, it is completely amorphous ΔCp = 0.4052 (J / (g · K)). The sample was weighed in an aluminum pan at 2.0 ± 0.2 mg, and measured in an MDSC (registered trademark) heat-only mode at an average heating rate of 5.0 ° C./min and a modulation period of 60 sec. Measurement data was collected at a sampling frequency of 5 Hz. In addition, indium was used for temperature and calorie calibration, and sapphire was used for specific heat calibration.
　以下、ＴｇおよびΔＣｐの算出方法を示す。まず、可逆熱容量曲線Ｆ（Ｔ）の温度Ｔの１次導関数Ｆ’（Ｔ）をプロットし、２４０１点毎の移動平均を取って平滑化処理を行ったのち、ピークトップにおける温度の値を読み取ることでＴｇを求めた。次に、点Ａ（Ｔｇ－１５，Ｆ（Ｔｇ―１５））および点Ｂ（Ｔｇ＋１５，Ｆ（Ｔｇ＋１５））の２点を通る直線Ｇ（Ｔ）を求めた。続いて、Ｔｇ－１５≦Ｔ≦Ｔｇ＋１５の範囲でＦ（Ｔ）－Ｇ（Ｔ）が最小となる温度をＴ１、最大となる温度をＴ２とした。ここで、Ｔ１はガラス転移の開始温度、Ｔ２はガラス転移の終了温度に相当することから、ΔＣｐ＝Ｆ（Ｔ２）－Ｆ（Ｔ１）によりΔＣｐの値を得た。 Hereinafter, the calculation method of Tg and ΔCp is shown. First, after plotting the first derivative F ′ (T) of the temperature T of the reversible heat capacity curve F (T), taking a moving average every 2401 points and performing a smoothing process, the temperature value at the peak top is calculated. The Tg was determined by reading. Next, a straight line G (T) passing through two points of point A (Tg-15, F (Tg-15)) and point B (Tg + 15, F (Tg + 15)) was obtained. Subsequently, in the range of Tg−15 ≦ T ≦ Tg + 15, the temperature at which F (T) −G (T) is minimum is T1, and the maximum temperature is T2. Here, since T1 corresponds to the glass transition start temperature and T2 corresponds to the glass transition end temperature, a value of ΔCp was obtained by ΔCp = F (T2) −F (T1).
　質量分率結晶化度χは、ＪＩＳ　Ｋ７１１２に従い水／硝酸カルシウム系の密度勾配管を用いて得られた密度の値ｄ（ｇ／ｃｍ３）を用いて、次式により算出した。
  χ＝（ｄｃ／ｄ）×（（ｄ－ｄａ）／（ｄ－ｄｃ））×１００（ｗｔ％）
  但し、ｄｃ：完全結晶の密度、ｄａ：完全非晶の密度
　ポリエチレンテレフタレートの場合、ｄｃ＝１．４９８（ｇ／ｃｍ３）、ｄａ＝１．３３５（ｇ／ｃｍ３）である。 The mass fraction crystallinity χ was calculated by the following equation using the density value d (g / cm 3 ) obtained using a water / calcium nitrate density gradient tube according to JIS K7112.
χ = (dc / d) × ((d−da) / (d−dc)) × 100 (wt%)
However, dc: density of complete crystal, da: density of completely amorphous In the case of polyethylene terephthalate, dc = 1.498 (g / cm 3 ) and da = 1.335 (g / cm 3 ).
（３）（１００）面のフィルム面に対する配向度
　（１００）面のフィルム面に対する配向度は、Ｘ線回折装置（株式会社リガク社製、ＲＩＮＴ２１００ＰＣ）を用いて、広角Ｘ線回折測定により得られた（１００）面の回折強度プロファイルの半値幅を用いて下記の式で定義されるパラメーターである。
（１００）面のフィルム面に対する配向度＝（１８０－半値幅）／１８０
　測定はＲＩＮＴ２１００ＰＣに装着できるＲＩＮＴ２０００ゴニオメータと極点用多目的試料台を取り付け、シュルツ反射法により行った。サンプルは直径５ｃｍの円形状に切り出し、遅相軸方向がβ＝９０および２７０度方向と一致するよう試料台に取り付けた。測定条件の詳細は、管電圧＝４０ｋＶ、管電流＝４０ｍＡ、２θ固定角度＝２５．８３０度、発散縦制限＝１．２ｍｍ、発散スリット＝１度、散乱スリット１度、受光スリット０．３０ｍｍであり、β＝０および１８０度のそれぞれに移動させた状態において、制御対象を反射αとし、測定方法＝ＦＴ、開始位置＝１５．０００度、終了位置＝９０．０００度、ステップ幅＝０．５００度、計数時間＝２．０ｓｅｃとして測定した。 (3) Degree of orientation of (100) plane with respect to film plane The degree of orientation of (100) plane with respect to the film plane is obtained by wide-angle X-ray diffraction measurement using an X-ray diffractometer (RINT2100PC, manufactured by Rigaku Corporation). It is a parameter defined by the following formula using the half width of the diffraction intensity profile of the (100) plane.
Degree of orientation of (100) plane with respect to the film plane = (180−half width) / 180
The measurement was performed by the Schulz reflection method with a RINT 2000 goniometer that can be attached to the RINT 2100 PC and a multipurpose sample stand for poles. The sample was cut into a circular shape with a diameter of 5 cm, and attached to the sample stage so that the slow axis direction coincided with the β = 90 and 270 degree directions. Details of the measurement conditions are as follows: tube voltage = 40 kV, tube current = 40 mA, 2θ fixed angle = 25.830 degrees, divergence length limit = 1.2 mm, divergence slit = 1 degree, scattering slit 1 degree, and light receiving slit 0.30 mm. Yes, in a state where β = 0 and 180 degrees are moved, the control object is a reflection α, measurement method = FT, start position = 15,000 degrees, end position = 90.000 degrees, step width = 0.0.0. Measurement was performed at 500 degrees and counting time = 2.0 sec.
　以下、（１００）面のフィルム面に対する配向度の算出方法を示す。まず、β＝０および１８０度における回折強度プロファイルＩ（α）（１５≦α≦９０）について、次式により入射Ｘ線の吸収に対する補正を行い、それぞれのβにおける回折強度プロファイルＪ（α）（１５≦α≦９０）を得た。
       Ｊ（α）＝Ｉ（α）×（１－ｅｘｐ（－２μｔ／ｓｉｎθ））／（１－ｅｘｐ（－２μｔ／（ｓｉｎθｃｏｓ（９０－α））））
　ここでμはＣｕＫα線の線吸収係数で、ポリエチレンテレフタレートの場合μ＝９．０２（／ｃｍ）であり、ｔはサンプル厚み（ｃｍ）、θは測定時の２θ固定角度の半分に相当する１２．９１５度である。得られたＪ（α）（１５≦α≦９０）について、横軸をα’（β＝０度のときα’＝α、β＝１８０度のときα’＝１８０－α）、縦軸を各α’における回折強度とすることでβ＝０および１８０度における回折強度プロファイルを接続し、回折強度プロファイルＪ（α’）（１５≦α’≦１６５）を得た。但し、α’＝９０度における回折強度は、β＝０度での値とβ＝１８０度での値の平均値を用いた。続いて、Ｊ（α’）（１５≦α’≦１６５）を擬フォークト関数でフィッティングすることで、全てのα’に対する回折強度プロファイルＫ（α’）を得た。Ｋ（α’）からα’＝０および１８０度での回折強度を結ぶ直線をベースラインとして差し引き、得られた回折強度プロファイルＬ（α’）の半値幅を用いて、（１８０－半値幅）／１８０により（１００）面のフィルム面に対する配向度を算出した。 Hereinafter, a method for calculating the degree of orientation of the (100) plane with respect to the film surface will be described. First, with respect to the diffraction intensity profile I (α) (15 ≦ α ≦ 90) at β = 0 and 180 degrees, the incident X-ray absorption is corrected by the following equation, and the diffraction intensity profile J (α) ( 15 ≦ α ≦ 90) was obtained.
J (α) = I (α) × (1-exp (−2 μt / sin θ)) / (1-exp (−2 μt / (sin θ cos (90−α))))
Here, μ is the linear absorption coefficient of CuKα ray, and in the case of polyethylene terephthalate, μ = 9.02 (/ cm), t is the sample thickness (cm), and θ corresponds to half of the 2θ fixed angle at the time of measurement. .915 degrees. For the obtained J (α) (15 ≦ α ≦ 90), the horizontal axis is α ′ (α ′ = α when β = 0 °, α ′ = 180−α when β = 180 °), and the vertical axis is By setting the diffraction intensity at each α ′, the diffraction intensity profiles at β = 0 and 180 degrees were connected to obtain a diffraction intensity profile J (α ′) (15 ≦ α ′ ≦ 165). However, as the diffraction intensity at α ′ = 90 degrees, the average value of the value at β = 0 degrees and the value at β = 180 degrees was used. Subsequently, J (α ′) (15 ≦ α ′ ≦ 165) was fitted with a pseudo-Forked function to obtain diffraction intensity profiles K (α ′) for all α ′. A straight line connecting diffraction intensities at α ′ = 0 and 180 degrees is subtracted from K (α ′) as a base line, and the half-value width of the obtained diffraction intensity profile L (α ′) is used (180−half-value width). The degree of orientation of the (100) plane relative to the film plane was calculated by / 180.
（４）虹斑観察
　ＰＶＡとヨウ素からなる偏光子の片側に後述する方法で作成したポリエチレンテレフタレート系樹脂フィルムを偏光子の吸収軸とフィルムの配向主軸が垂直になるように貼り付け、その反対の面に市販のＴＡＣフィルムを貼り付けて偏光板を作成した。得られた偏光板を、市販の液晶表示装置（東芝社製のＲＥＧＺＡ　４３Ｊ１０Ｘ）に元々存在した出射光側の偏光板と置き換えた。なお、偏光板の吸収軸が、元々液晶表示装置に貼付されていた偏光板の吸収軸方向と一致するように、ポリエチレンテレフタレート系樹脂フィルムが視認側になるよう偏光板を置き換えた。前記液晶表示装置は、励起光を出射する光源とＫＳＦ蛍光体を含むバックライト光源を有する。この液晶表示装置のバックライト光源の発光スペクトルを、浜松ホトニクス製　マルチチャンネル分光器　ＰＭＡ－１２を用いて測定したところ、４４８ｎｍ、５３３ｎｍ、６３０ｎｍ付近にピークトップを有する発光スペクトルが観察され、各ピークトップの半値幅は２ｎｍ～４９ｎｍであった。なお、スペクトル測定の際の露光時間は２０ｍｓｅｃとした。このようにして作製した液晶表示装置に白画像を表示させ、ディスプレイの正面、および、斜め方向から目視観察を行って、虹斑の発生について、以下のように判定した。なお、観察角度は、ディスプレイの画面の中心から法線方向（垂直）に引いた線と、ディスプレイ中心と観察時の眼の位置とを結ぶ線とのなす角とした。
　◎　：　観察角度０～６０度の範囲で、虹斑は観察されなかった。
　○　：　観察角度０～６０度の範囲で、一部薄い虹斑が観察された。
　×　：　観察角度０～６０度の範囲で、明確に虹斑が観察された。 (4) Iridescent observation A polyethylene terephthalate-based resin film prepared by the method described later 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. A commercially available TAC film was attached to the surface to prepare a polarizing plate. The obtained polarizing plate was replaced with a polarizing plate on the outgoing light side originally present in a commercially available liquid crystal display device (REGZA 43J10X manufactured by Toshiba Corporation). The polarizing plate was replaced so that the polyethylene terephthalate resin film was on the viewing side so that the absorption axis of the polarizing plate coincided with the absorption axis direction of the polarizing plate originally attached to the liquid crystal display device. The liquid crystal display device includes a light source that emits excitation light and a backlight light source that includes a KSF phosphor. When the emission spectrum of the backlight source of this liquid crystal display device was measured using a multi-channel spectrometer PMA-12 manufactured by Hamamatsu Photonics, emission spectra having peak tops in the vicinity of 448 nm, 533 nm, and 630 nm were observed. The half-value width of was 2 nm to 49 nm. The exposure time for spectrum measurement was 20 msec. A white image was displayed on the liquid crystal display device thus manufactured, and visual observation was performed from the front of the display and from an oblique direction, and the occurrence of rainbow spots was determined as follows. The observation angle was an angle formed by a line drawn in the normal direction (vertical) from the center of the display screen and a line connecting the center of the display and the position of the eye at the time of observation.
A: No iris was observed in the observation angle range of 0 to 60 degrees.
○: Some thin rainbow spots were observed in the observation angle range of 0 to 60 degrees.
X: Iridoids were clearly observed in the observation angle range of 0 to 60 degrees.
（製造例１－ポリエステルＡ）
　エステル化反応缶を昇温し２００℃に到達した時点で、テレフタル酸を８６．４質量部およびエチレングリコール６４．６質量部を仕込み、撹拌しながら触媒として三酸化アンチモンを０．０１７質量部、酢酸マグネシウム４水和物を０．０６４質量部、トリエチルアミン０．１６質量部を仕込んだ。ついで、加圧昇温を行いゲージ圧０．３４ＭＰａ、２４０℃の条件で加圧エステル化反応を行った後、エステル化反応缶を常圧に戻し、リン酸０.０１４質量部を添加した。さらに、１５分かけて２６０℃に昇温し、リン酸トリメチル０．０１２質量部を添加した。次いで１５分後に、高圧分散機で分散処理を行い、１５分後、得られたエステル化反応生成物を重縮合反応缶に移送し、２８０℃で減圧下重縮合反応を行った。 (Production Example 1-Polyester A)
When the temperature of the esterification reactor was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged and 0.017 parts by mass of antimony trioxide as a catalyst while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were charged. Subsequently, the pressure was raised and the esterification reaction was performed under the conditions of a gauge pressure of 0.34 MPa and 240 ° C., and then the esterification reaction vessel was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, it heated up to 260 degreeC over 15 minutes, and 0.012 mass part of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to polycondensation reaction at 280 ° C. under reduced pressure.
　重縮合反応終了後、９５％カット径が５μｍのナスロン製フィルターで濾過処理を行い、ノズルからストランド状に押出し、予め濾過処理（孔径：１μｍ以下）を行った冷却水を用いて冷却、固化させ、ペレット状にカットした。得られたポリエチレンテレフタレート樹脂（Ａ）の固有粘度は０．６２ｄｌ／ｇであり、不活性粒子及び内部析出粒子は実質上含有していなかった。（以後、ＰＥＴ（Ａ）と略す。） After completion of the polycondensation reaction, it is filtered through a NASRON filter with a 95% cut diameter of 5 μm, extruded into a strand from a nozzle, and cooled and solidified using cooling water that has been filtered (pore diameter: 1 μm or less) in advance. And cut into pellets. 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).)
（製造例２－ポリエステルＢ）
　乾燥させた紫外線吸収剤（２，２’－（１，４－フェニレン）ビス（４Ｈ－３，１－ベンズオキサジノン－４－オン）１０質量部、粒子を含有しないＰＥＴ（Ａ）（固有粘度が０．６２ｄｌ／ｇ）９０質量部を混合し、混練押出機を用い、紫外線吸収剤含有するポリエチレンテレフタレート樹脂（Ｂ）を得た。（以後、ＰＥＴ（Ｂ）と略す。） (Production Example 2-Polyester 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)).
（製造例３－接着性改質塗布液の調整）
　常法によりエステル交換反応および重縮合反応を行って、ジカルボン酸成分として（ジカルボン酸成分全体に対して）テレフタル酸４６モル％、イソフタル酸４６モル％および５－スルホナトイソフタル酸ナトリウム８モル％、グリコール成分として（グリコール成分全体に対して）エチレングリコール５０モル％およびネオペンチルグリコール５０モル％の組成の水分散性スルホン酸金属塩基含有共重合ポリエステル樹脂を調製した。次いで、水５１．４質量部、イソプロピルアルコール３８質量部、ｎ－ブチルセルソルブ５質量部、ノニオン系界面活性剤０．０６質量部を混合した後、加熱撹拌し、７７℃に達したら、上記水分散性スルホン酸金属塩基含有共重合ポリエステル樹脂５質量部を加え、樹脂の固まりが無くなるまで撹拌し続けた後、樹脂水分散液を常温まで冷却して、固形分濃度５．０質量％の均一な水分散性共重合ポリエステル樹脂液を得た。さらに、凝集体シリカ粒子（富士シリシア（株）社製、サイリシア３１０）３質量部を水５０質量部に分散させた後、上記水分散性共重合ポリエステル樹脂液９９．４６質量部にサイリシア３１０の水分散液０．５４質量部を加えて、撹拌しながら水２０質量部を加えて、接着性改質塗布液を得た。 (Production Example 3-Adjustment of Adhesive Modification Coating Solution)
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. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, 0.06 parts by mass of a nonionic surfactant were mixed and then heated and stirred. After adding 5 parts by mass of a water-dispersible sulfonic acid metal base-containing copolymer polyester resin and continuing to stir until the resin is no longer agglomerated, the resin water dispersion is cooled to room temperature to obtain a solid content concentration of 5.0% by mass. A uniform water-dispersible copolymerized polyester resin liquid was obtained. Furthermore, after dispersing 3 parts by mass of aggregated silica particles (Silicia 310, manufactured by Fuji Silysia Co., Ltd.) in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolyester resin solution was mixed with 99.46 parts by mass of the silicia 310. 0.54 parts by mass of the aqueous dispersion was added, and 20 parts by mass of water was added with stirring to obtain an adhesive modified coating solution.
（実施例１）
　基材フィルム中間層用原料として粒子を含有しないＰＥＴ（Ａ）樹脂ペレット９０質量部と紫外線吸収剤を含有したＰＥＴ（Ｂ）樹脂ペレット１０質量部を１３５℃で６時間減圧乾燥（１Ｔｏｒｒ）した後、押出機２（中間層ＩＩ層用）に供給し、また、ＰＥＴ（Ａ）を常法により乾燥して押出機１（外層Ｉ層および外層ＩＩＩ用）にそれぞれ供給し、２８５℃で溶解した。この２種のポリマーを、それぞれステンレス焼結体の濾材（公称濾過精度１０μｍ粒子９５％カット）で濾過し、２種３層合流ブロックにて、積層し、口金よりシート状にして押し出した後、静電印加キャスト法を用いて表面温度３０℃のキャスティングドラムに巻きつけて冷却固化し、未延伸フィルムを作った。この時、Ｉ層、ＩＩ層、ＩＩＩ層の厚さの比は１０：８０：１０となるように各押し出し機の吐出量を調整した。 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. . After filtering these two kinds of polymers with a filter medium made of a sintered stainless steel (nominal filtration accuracy of 10 μm particles 95% cut), laminating them in a two-kind / three-layer confluence block, and extruding them into a sheet form from a die, The film was wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method, and then cooled and solidified to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the thickness ratio of the I layer, the II layer, and the III layer was 10:80:10.
　次いで、リバースロール法によりこの未延伸ＰＥＴフィルムの両面に乾燥後の塗布量が０．０８ｇ／ｍ２になるように、上記接着性改質塗布液を塗布した後、８０℃で２０秒間乾燥した。 Next, after applying the adhesive property-modifying coating solution on the both sides of this unstretched PET film by a reverse roll method so that the coating amount after drying was 0.08 g / m 2 , the coating was dried at 80 ° C. for 20 seconds. .
　この塗布層を形成した未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１３０℃の熱風ゾーンに導き、幅方向に５．５倍となるよう、歪み速度１３．８％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 The unstretched film on which this coating layer has been formed is guided to a tenter stretching machine, and the edge of the film is held by a clip, guided to a hot air zone at a temperature of 130 ° C., and a strain rate of 13 so as to be 5.5 times in the width direction. The film was stretched at 8% / sec. Next, heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
（実施例２）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１２０℃の熱風ゾーンに導き、幅方向に５．５倍となるよう、歪み速度１８．３％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 (Example 2)
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 120 ° C. while being gripped by a clip, so that the width is 5.5 times the width direction. The film was stretched at a strain rate of 18.3% / sec. Next, heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
（実施例３）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１１８℃の熱風ゾーンに導き、幅方向に５．０倍となるよう、歪み速度３４．６％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 (Example 3)
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 118 ° C. while being gripped by a clip, so that the width becomes 5.0 times in the width direction. The film was stretched at a strain rate of 34.6% / sec. Next, heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
（実施例４）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１０７℃の熱風ゾーンに導き、幅方向に５．０倍となるよう、歪み速度３４．６％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 Example 4
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 107 ° C. while being gripped by a clip, so that the width becomes 5.0 times in the width direction. The film was stretched at a strain rate of 34.6% / sec. Next, heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
（実施例５）
　厚みを変えた以外は実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１２５℃の熱風ゾーンに導き、幅方向に５．５倍となるよう、歪み速度１８．３％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約５０μｍの一軸配向ＰＥＴフィルムを得た。 (Example 5)
An unstretched film produced by the same method as in Example 1 except that the thickness was changed was guided to a tenter stretching machine, and the end of the film was guided by a clip while being guided to a hot air zone at a temperature of 125 ° C. The film was stretched at a strain rate of 18.3% / sec so as to be 5 times. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 180 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 50 μm.
（実施例６）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１３０℃の熱風ゾーンに導き、幅方向に５．５倍となるよう、歪み速度１３．８％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度２００℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 (Example 6)
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 130 ° C. while being gripped by a clip, so that the width is 5.5 times. The film was stretched at a strain rate of 13.8% / sec. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 200 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
（実施例７）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１２０℃の熱風ゾーンに導き、幅方向に６．０倍となるよう、歪み速度２０．８％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約５０μｍの一軸配向ＰＥＴフィルムを得た。 (Example 7)
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 120 ° C. while being gripped by a clip, so as to be 6.0 times in the width direction. The film was stretched at a strain rate of 20.8% / sec. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 180 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 50 μm.
（比較例１）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度９０℃の熱風ゾーンに導き、幅方向に４．０倍となるよう、歪み速度１２．５％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度１８０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 (Comparative Example 1)
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the end of the film is guided to a hot air zone at a temperature of 90 ° C. while being gripped by a clip, so that the width becomes 4.0 times in the width direction. The film was stretched at a strain rate of 12.5% / sec. Next, heat treatment was performed in a hot air zone at a temperature of 180 ° C. while maintaining the width stretched in the width direction, and 3% relaxation treatment was further performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
（比較例２）
　実施例１と同じ方法で作製された未延伸フィルムをテンター延伸機に導き、フィルムの端部をクリップで把持しながら、温度１３０℃の熱風ゾーンに導き、幅方向に５．５倍となるよう、歪み速度１３．８％／ｓｅｃで延伸した。次に、幅方向に延伸された幅を保ったまま、温度２４０℃の熱風ゾーンで熱処理し、さらに幅方向に３％の緩和処理を行い、フィルム厚み約６０μｍの一軸配向ＰＥＴフィルムを得た。 (Comparative Example 2)
The unstretched film produced by the same method as in Example 1 is guided to a tenter stretching machine, and the edge of the film is guided to a hot air zone at a temperature of 130 ° C. while being gripped by a clip, so that the width is 5.5 times. The film was stretched at a strain rate of 13.8% / sec. Next, while maintaining the width stretched in the width direction, heat treatment was performed in a hot air zone at a temperature of 240 ° C., and 3% relaxation treatment was performed in the width direction to obtain a uniaxially oriented PET film having a film thickness of about 60 μm.
　実施例、比較例で得られたＰＥＴフィルムについて測定した結果を表１に示す。 Table 1 shows the measurement results of the PET films obtained in Examples and Comparative Examples.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明の液晶表示装置、偏光板および偏光子保護フィルムであれば、液晶表示装置の広色域化によるバックライト光源の波長スペクトルの多様化や、偏光子保護フィルムの薄膜化した場合でも、虹斑を抑制することができる。 With the liquid crystal display device, polarizing plate and polarizer protective film of the present invention, even if the wavelength spectrum of the backlight light source is diversified by widening the color gamut of the liquid crystal display device or the polarizer protective film is thinned, the rainbow Spots can be suppressed.

Claims (4)

  1. 下記の（１）及び（２）を満たすポリエチレンテレフタレート系樹脂フィルムからなる偏光子保護フィルム。
    （１）リタデーションが３０００ｎｍ以上３００００ｎｍ以下である
    （２）次式で表される剛直非晶分率が３３ｗｔ％以上である
           （剛直非晶分率（ｗｔ％））＝１００－（可動非晶分率（ｗｔ％））－（質量分率結晶化度（ｗｔ％））     A polarizer protective film comprising a polyethylene terephthalate resin film that satisfies the following (1) and (2).
    (1) Retardation is 3000 nm or more and 30000 nm or less (2) Rigid amorphous fraction represented by the following formula is 33 wt% or more (rigid amorphous fraction (wt%)) = 100− (movable amorphous fraction) Rate (wt%))-(mass fraction crystallinity (wt%))
  2. 前記ポリエチレンテレフタレート系樹脂フィルムが更に下記（３）を満たす、請求項１に記載の偏光子保護フィルム。
    （３）Ｘ線回折で測定した（１００）面のフィルム面に対する配向度が０．７以下である     The polarizer protective film according to claim 1, wherein the polyethylene terephthalate resin film further satisfies the following (3).
    (3) The degree of orientation of the (100) plane with respect to the film surface measured by X-ray diffraction is 0.7 or less.
  3. 偏光子の少なくとも一方の面に請求項１又は２に記載の偏光子保護フィルムが積層された偏光板。 The polarizing plate by which the polarizer protective film of Claim 1 or 2 was laminated | stacked on the at least one surface of the polarizer.
  4. バックライト光源、２つの偏光板、及び前記２つの偏光板の間に配された液晶セルを有する液晶表示装置であって、
    前記２つの偏光板のうち、少なくとも一方が請求項３に記載の偏光板である、液晶表示装置。     A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates,
    A liquid crystal display device, wherein at least one of the two polarizing plates is the polarizing plate according to claim 3.
PCT/JP2018/013103 2017-03-31 2018-03-29 Liquid crystal display device, polarizing plate, and polarizer protective film WO2018181655A1 (en)

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