WO2023210443A1 - ポリエチレンテレフタレート系樹脂フィルム、これを用いた偏光板、透明導電性フィルム、タッチパネル、及び、画像表示装置 - Google Patents

ポリエチレンテレフタレート系樹脂フィルム、これを用いた偏光板、透明導電性フィルム、タッチパネル、及び、画像表示装置 Download PDF

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WO2023210443A1
WO2023210443A1 PCT/JP2023/015482 JP2023015482W WO2023210443A1 WO 2023210443 A1 WO2023210443 A1 WO 2023210443A1 JP 2023015482 W JP2023015482 W JP 2023015482W WO 2023210443 A1 WO2023210443 A1 WO 2023210443A1
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Prior art keywords
film
polyethylene terephthalate
terephthalate resin
resin film
less
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English (en)
French (fr)
Japanese (ja)
Inventor
尭永 阿部
薫 澤田
友香 池田
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Toyobo Co Ltd
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Toyobo Co Ltd
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Priority to KR1020247037767A priority Critical patent/KR20250002486A/ko
Priority to CN202380036085.6A priority patent/CN119137513A/zh
Priority to JP2024517222A priority patent/JPWO2023210443A1/ja
Publication of WO2023210443A1 publication Critical patent/WO2023210443A1/ja
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/86—Arrangements for improving contrast, e.g. preventing reflection of ambient light
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/10—OLED displays
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/8793—Arrangements for polarized light emission
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2367/00—Polyesters, e.g. PET, i.e. polyethylene terephthalate

Definitions

  • the present invention relates to a polyethylene terephthalate resin film, a polarizing plate using the same, a transparent conductive film, a touch panel, and an image display device such as a liquid crystal display device or an organic EL display device.
  • a polarizing plate used in a liquid crystal display is usually composed of a polarizer made of polyvinyl alcohol (PVA) dyed with iodine, sandwiched between two polarizer protective films.
  • PVA polyvinyl alcohol
  • TAC triacetyl cellulose
  • LCDs have become thinner, there has been a demand for thinner polarizing plates.
  • TAC film is very expensive, and although polyester film has been proposed as an inexpensive alternative material (Patent Documents 1 to 3), there is a problem in 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 exhibits an interference color characteristic of the retardation, which is the product of the 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 a light source, the intensity of transmitted light varies depending on the wavelength, resulting in rainbow-like color spots.
  • a white light source with a continuous and wide emission spectrum such as a white light emitting diode
  • a backlight light source and use an oriented polyester film with 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, by focusing on the envelope shape of the interference color spectrum due to transmitted light transmitted through a birefringent material, by controlling the retardation of the oriented polyester film, it is possible to obtain a spectrum similar to the emission spectrum of the light source. It made it possible to suppress iridescence.
  • Polyethylene terephthalate resin films with a certain retardation for the purpose of suppressing iridescence are used for various purposes such as polarizer protective films, base materials for transparent conductive films such as touch panels, and surface cover films. It has been found that because of its orientation, it tends to tear in the direction parallel to the slow axis, and that breakage during slitting may reduce productivity. Furthermore, due to the increase in cutting resistance associated with oriented crystallization, the cut portion is elongated during slitting, resulting in ridges at the end of the product roll, which may impair the quality of the product. Further, as the cutting resistance increases, the film is scraped at the cut portion, and the resulting fine powder becomes foreign matter, which may impair the quality of the product.
  • an object of the present invention is to provide a polyethylene terephthalate resin film that has excellent processability and can particularly effectively suppress the occurrence of breakage and ridges during slitting.
  • Another object of the present invention is to provide a polarizing plate, a transparent conductive film, a touch panel, and an image display device such as a liquid crystal display device or an organic EL display device using the polyethylene terephthalate resin film.
  • the present inventors have found that, for polyethylene terephthalate resin films having retardation within a specific range, the mesophase orientation parameter of polyethylene terephthalate resin films measured by ATR-FTIR method can be controlled to a value above a certain value.
  • the inventors have discovered that the above-mentioned problems can be solved, and have completed the present invention.
  • Representative examples of the present invention are as follows.
  • Item 1. A polyethylene terephthalate resin film that satisfies (1) and (2) below.
  • the polyethylene terephthalate resin film has a retardation of 3,000 to 30,000 nm.
  • the mesophase orientation parameter of the polyethylene terephthalate resin film measured by the ATR-FTIR method is 0.275 or more, expressed by the following formula.
  • the polyethylene terephthalate resin film according to item 1 or 2 which further satisfies the following (5). (5) Item 4.
  • the breaking strength in the slow axis direction is 450 MPa or less.
  • a polarizing plate comprising a polyethylene terephthalate resin film according to any one of Items 1 to 4 laminated on at least one surface of a polarizer as a polarizer protective film.
  • Item 6. Item 5.
  • An image display device comprising the polarizing plate according to item 5.
  • Section 7. A liquid crystal display device comprising a backlight 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 item 5.
  • Section 8. Item 5.
  • An organic EL display device comprising the polarizing plate according to item 5.
  • Item 9. A touch panel comprising the transparent conductive film according to item 9.
  • Item 11. An image display device comprising a polyethylene terephthalate resin film according to any one of items 1 to 4 as a scattering prevention film or a surface protection film on the viewing side of the image display panel.
  • a polyethylene terephthalate resin film that has excellent processing suitability and can particularly effectively suppress the occurrence of breakage, ridges, and foreign matter during slitting. Further, it is possible to provide a polarizing plate, a transparent conductive film, a touch panel, and an image display device such as a liquid crystal display device or an organic EL display device using the polyethylene terephthalate resin film.
  • Polyethylene terephthalate resin film The polyethylene terephthalate resin film of the present invention preferably has a retardation of 3000 nm or more and 30000 nm or less. If the retardation is 3000 nm or more, it is possible to suppress the occurrence of interference colors and ensure good visibility when observed from an oblique direction.
  • a preferred lower limit of retardation is 4000 nm, and a second preferred lower limit is 5000 nm.
  • the upper limit of retardation is preferably 30,000 nm. Even if a polyethylene terephthalate resin film having a retardation higher than that is used, no further improvement in visibility can be obtained, and the film becomes considerably thicker, resulting in poor handling as an industrial material.
  • a preferable upper limit is 10,000 nm, a more preferable upper limit is 9,000 nm, and an even more preferable upper limit is 8,000 nm.
  • the refractive index difference in the film plane is preferably 0.08 or more.
  • a film that is strongly stretched in one direction and has a large in-plane refractive index difference can obtain sufficient retardation even with a thinner film, and is preferable from the viewpoint of thinning the film, more preferably 0.09 or more, and even more preferably 0. .10 or more, particularly preferably 0.105 or more, and most preferably 0.11 or more.
  • the present invention is suitably applied to such a film with a large difference in refractive index.
  • the refractive index difference of the film is preferably 0. 15 or less, more preferably 0.145 or less, even more preferably 0.14 or less, even more preferably 0.135 or less, particularly preferably 0.13, most preferably 0.125 or less.
  • the retardation of the present invention can be determined by measuring the refractive index and film thickness in two axial directions within the film plane, or by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.). It can also be found using The measurement wavelength of the refractive index is 589 nm.
  • the polyethylene terephthalate resin film of the present invention has a mesophase orientation parameter of 0.275 or more, which is an index of the degree of orientation of an oriented intermediate phase (mesophase) in the slow axis direction in the plane of the film. This is preferable from the viewpoint of reducing the cutting resistance during cutting by suppressing oriented crystallization, and suppressing the occurrence of breakage, ridges, and foreign matter during slitting.
  • the mesophase orientation parameter of the present invention is preferably 0.275 or more, more preferably 0.280 or more, even more preferably 0.285 or more, particularly preferably 0.290 or more.
  • the mesophase orientation parameter is preferably 0.500 or less, more preferably 0.450 or less, and even more preferably It is 0.400 or less, even more preferably 0.370 or less, particularly preferably 0.360 or less, and most preferably 0.355 or less.
  • the mesophase orientation parameter of the polyethylene terephthalate resin film is expressed by the following formula (1).
  • (Mesophase orientation parameter) R slow / R fast ... (1)
  • R slow (absorbance at 1457 cm -1 in the slow axis direction) / (absorbance at 795 cm -1 in the slow axis direction)
  • R fast (1457 cm -1 in the fast axis direction ) 1 )/(absorbance at 795 cm ⁇ 1 in the fast axis direction).
  • the absorbance at 1457 cm -1 and the absorbance at 795 cm -1 were determined by Fourier transform infrared spectroscopy (ATR-FTIR) using a commercially available Fourier transform infrared spectrophotometer such as FTS 60A/896 (Varian). ).
  • the absorbance peak at 1457 cm -1 is the absorbance peak derived from the amorphous phase appearing at 1454 cm -1 and the meso phase (also called an oriented intermediate phase) appearing at 1463 cm -1 .
  • the dichroic ratio of the absorbance peak at 1457 cm ⁇ 1 reflects the orientation anisotropy of the mesophase.
  • the absorbance peaks at 1454 cm -1 and 1463 cm -1 both reflect the conformational combination of the methylene group and the ester bond, and the absorbance peak at 1454 cm -1 indicates that the methylene group is in the gauche (relaxed state) and the ester bond is in the trans (
  • the absorbance peak at 1463 cm ⁇ 1 corresponds to a combination in which the methylene group is trans and the ester bond is gauche.
  • the absorbance at 795 cm -1 reflects the out-of-plane vibration of the benzene ring, and since the absorbance does not change depending on the degree of orientation of the film surface or the pressure of the anvil during ATR measurement, the absorbance at other wave numbers does not change. It can be used for standardization.
  • the absorbance at 1457 cm -1 does not necessarily mean the absorbance exactly at 1457 cm -1 , but indicates the absorbance at the top of the peak observed around 1457 cm -1 (1452 cm -1 to 1462 cm -1 ). If no clear peak top is observed, the absorbance at 1457 cm ⁇ 1 can be read.
  • the absorbance at 795 cm -1 does not necessarily mean the absorbance at exactly 795 cm -1 , but indicates the absorbance at the top of the peak observed around 795 cm -1 (790 cm -1 to 800 cm -1 ). , if no clear peak top is observed, the absorbance at 795 cm ⁇ 1 can be read. Details of the measurement method will be described later in Examples.
  • the processability of a polyethylene terephthalate resin film is affected by crystals that grow in the orientation direction as it is stretched.
  • the polyethylene terephthalate resin film of the present invention has increased orientation anisotropy within the film plane for the purpose of suppressing iridescence, and crystals grow preferentially in the slow axis direction corresponding to the main stretching direction. .
  • the growth of crystals not only increases the cutting resistance in the fast axis direction perpendicular to the slow axis direction, but also embrittles the polyethylene terephthalate resin film.
  • polyethylene terephthalate resin films made by known methods may produce fine powder due to film abrasion or ridges at the end of the product roll due to film stretching in the cut portion during slitting, which may cause refraction.
  • the orientation anisotropy is increased by controlling the mesophase orientation parameter, which is an index of the degree of amorphous orientation in the slow axis direction in the film plane, within the above range, Effectively suppresses embrittlement of polyethylene terephthalate resin film and increase in cutting resistance, and prevents generation of fine powder due to abrasion of the polyethylene terephthalate resin film in the cut portion during slitting, and ridges at the end of the product roll due to film elongation.
  • the occurrence of can be effectively suppressed.
  • the present invention exhibits an excellent effect when the slow axis direction is in the TD direction and is preferably applied, but even when the slow axis direction is in the MD direction, the effect of suppressing the generation of ears and fine powder is high, This also applies to those in which the slow axis direction is in the MD direction.
  • the polyethylene terephthalate resin film of the present invention has an elastic modulus of 8,600 MPa or less in the slow axis direction within the film plane, which further reduces the cutting resistance in the fast axis direction, and the polyethylene terephthalate resin film in the portion cut during slitting is This is preferable from the viewpoint of further suppressing the generation of fine powder due to scraping of the resin film and the generation of ridges at the end of the product roll due to elongation of the film.
  • the elastic modulus of the polyethylene terephthalate resin film in the slow axis direction is preferably 8,600 MPa or less, more preferably 8,500 MPa or less, still more preferably 8,400 MPa or less, particularly preferably 8,300 MPa or less.
  • the lower limit is not particularly limited, but from the viewpoint of maintaining sufficient orientation anisotropy to suppress iridescence, it is preferably 5400 MPa or more, more preferably 5450 MPa or more, even more preferably 5500 MPa or more, and particularly preferably 5550 MPa or more.
  • the ratio of the elastic modulus in the slow axis direction and the fast axis direction in the film plane is 3.6 or less, which further reduces cutting resistance in the fast axis direction, This is preferable from the viewpoint of further suppressing the generation of fine powder due to the abrasion of the polyethylene terephthalate resin film in the cut portion during slitting and the generation of ridges at the ends of the product roll due to film elongation.
  • the ratio of the elastic modulus in the slow axis direction and the fast axis direction of the polyethylene terephthalate resin film is preferably 3.6 or less, more preferably 3.5 or less, still more preferably 3.4 or less, particularly preferably 3. 3 or less.
  • the lower limit is not particularly limited, but from the viewpoint of maintaining sufficient orientation anisotropy to suppress iridescence, it is preferably 2.0 or more, more preferably 2.5 or more, even more preferably 2.6 or more, and particularly preferably 2. .7 or higher.
  • the elastic modulus in the fast axis direction is preferably 2000 MPa or more, more preferably 2300 MPa or more, even more preferably 2350 MPa or more, particularly preferably 2400 MPa or more, and most preferably 2450 MPa or more.
  • the upper limit is preferably 4300 MPa or less, more preferably 4200 MPa or less, even more preferably 4100 MPa or less, even more preferably 4000 MPa or less, particularly preferably 3500 MPa or less, and most preferably 3000 MPa or less.
  • the value obtained for the elastic modulus can vary greatly depending on the measurement method.
  • the elastic modulus is defined as the value of the slope of the stress-strain curve obtained by a tensile test at the initial stage of stretching, but in addition to the face shape of the chuck used for measurement, the pressing force and reserve force, the strain interval used to calculate the slope
  • the value of the elastic modulus changes greatly depending on the For example, regarding the nominal stress-nominal strain curve shown in FIG. 1 (measured by a method compliant with JIS K7161, which will be described later in the examples), the strain interval (nominal strain: 0.
  • the elastic modulus is calculated to be 6986 MPa, but in the range of nominal strain: 0.0005 to 0.0100, the elastic modulus is 6469 MPa, and in the range of nominal strain: 0.0005 to 0.0200, the elastic modulus is calculated as 6986 MPa.
  • the elastic modulus is 5149 MPa, and the elastic modulus is 2590 MPa in the range of nominal strain: 0.0005 to 0.0500.
  • the value of the storage modulus obtained by dynamic viscoelasticity measurement can be used, but the obtained value varies greatly depending on the measurement temperature.
  • Figure 2 shows the temperature dependence of the storage modulus of the same sample measured in Figure 1 using a dynamic viscoelasticity measuring device (DMS6100) manufactured by Seiko Instruments in accordance with JIS-K7244 (the measurement conditions were , tension mode, driving frequency 1 Hz, distance between chucks 5 mm, temperature increase rate 2 °C/min, measurement temperature range 20 °C to 230 °C).
  • the elastic modulus at 20°C is 6958 MPa
  • the elastic modulus at 60°C is 6425 MPa
  • the elastic modulus at 100°C is 4533 MPa
  • the elastic modulus at 140°C is 1028 MPa
  • the elastic modulus at 180°C is 719 MPa
  • the elastic modulus at 220°C is 6958 MPa.
  • the elastic modulus is 497 MPa. It is also common to adopt the average value in a specific section, but for example, the average elastic modulus in the 20°C to 60°C section is 6718 MPa, the average elastic modulus in the 20°C to 100°C section is 6244 MPa, and the average elastic modulus in the 20°C to 140°C section.
  • the average elastic modulus in the 20°C to 180°C range is 3930 MPa
  • the average elastic modulus in the 20°C to 220°C range is 3254 MPa
  • the average elastic modulus in the 100°C to 220°C range is 1264 MPa.
  • the value of the elastic modulus varies greatly depending on the measurement method, but the scope of the claims of the present invention is based on the value measured by a method compliant with JIS K7161 Section 10.3.2. The details of the measurement method will be described later in Examples.
  • the polyethylene terephthalate resin film of the present invention has a breaking strength of 450 MPa or less in the slow axis direction within the film plane, which further reduces the cutting resistance in the fast axis direction, and the polyethylene terephthalate resin film in the portion cut during slitting is This is preferable from the viewpoint of further suppressing the generation of fine powder due to scraping of the resin film and the generation of ridges at the end of the product roll due to elongation of the film.
  • the breaking strength of the polyethylene terephthalate resin film in the slow axis direction is more preferably 440 MPa or less, still more preferably 430 MPa or less, particularly preferably 420 MPa or less.
  • the lower limit is not particularly limited, but from the viewpoint of maintaining sufficient orientation anisotropy to suppress iridescence, it is preferably 220 MPa or more, more preferably 230 MPa or more, even more preferably 240 MPa or more, and particularly preferably 250 MPa or more.
  • the polyethylene terephthalate resin film of the present invention has a rigid amorphous fraction of 33% by mass or more, which further suppresses embrittlement of the polyethylene terephthalate resin film and causes breakage starting from the cut portion during slitting. This is preferable from the viewpoint of further suppressing the generation of fine powder due to scraping of the polyethylene terephthalate resin film.
  • the rigid amorphous fraction of the polyethylene terephthalate resin film is more preferably 34% by mass or more, still more preferably 35% by mass or more, particularly preferably 36% by mass or more.
  • the upper limit is preferably 60% by mass, but 50% by mass or less or 45% by mass or less is also sufficient and is a more preferable range.
  • the rigid amorphous fraction is expressed by the following formula (2).
  • amorphous regions can be further differentiated by the temperature dependence of their molecular motions: mobile amorphous, in which molecular motion is released at the glass transition temperature (Tg), and mobile amorphous, in which molecular motion is frozen even at temperatures above Tg. It has been reported that it can be divided into rigid and amorphous. It is known that in the case of polyethylene terephthalate, this rigid amorphous crystal remains amorphous up to a temperature of around 200°C.
  • this rigid amorphous exists in the boundary region between the crystal and the mobile amorphous, and it is thought that the rigid amorphous fraction increases as the degree of crystallinity increases.
  • the inventors investigated and found that by controlling the rigid amorphous fraction within the above range, the embrittlement of the polyethylene terephthalate resin film due to crystallization can be prevented even when the in-plane orientation anisotropy of the film is increased. It has been found that this can be more effectively suppressed, making it easier to suppress the generation of fine powder caused by breakage originating from the cut portion during slitting and by scraping of the polyethylene terephthalate resin film.
  • the rigid amorphous fraction is indirectly determined using the values of the mobile amorphous fraction and the mass fraction crystallinity.
  • the mobile 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 according to JIS K7112. Details will be described later in Examples.
  • the movable amorphous fraction is preferably 24.5% by mass or more, more preferably 25% by mass or more, still more preferably 25.5% by mass or more, and particularly preferably is 26% by mass or more.
  • the upper limit is preferably 36% by mass or less, more preferably 35.5% by mass or less, further preferably 35% by mass or less, particularly preferably 34.5% by mass or less.
  • the mass fraction crystallinity is preferably 41% by mass or less, more preferably 40% by mass or less, It is more preferably 39% by mass or less, particularly preferably 38% by mass or less.
  • the lower limit is 27% by mass or more, more preferably 28% by mass or more, even more preferably 29% by mass or more, particularly preferably 30% by mass or more.
  • the polyethylene terephthalate resin film of the present invention can be manufactured based on a general polyester film manufacturing method.
  • a non-oriented polyethylene terephthalate resin is melted and extruded into a sheet, stretched in the longitudinal direction using a speed difference between rolls at a temperature higher than the glass transition temperature, and then stretched horizontally in a tenter.
  • An example of this method is to stretch the film in the same direction and then heat treat it.
  • a simultaneous biaxial stretching machine may be used to simultaneously or sequentially stretch in the longitudinal and transverse directions within a tenter.
  • the conditions for forming a polyethylene terephthalate resin film will be specifically explained. As a result of the inventors' studies day and night, we found that by preheating the film at a sufficiently high temperature to sufficiently soften the film, and then stretching it at a moderately lower temperature, the amorphous molecular chains during stretching can be reduced. It has been found that it is possible to promote orientation and effectively increase mesophase orientation parameters.
  • the stretching temperature is preferably at least 5° C. lower than the preheating temperature.
  • the upper limit of the stretching temperature is more preferably 10°C or more lower than the preheating temperature, even more preferably 15°C or more lower, and particularly preferably 20°C or more lower.
  • the lower limit of the stretching temperature is more preferably -60°C or higher, even more preferably -55°C or higher, and particularly preferably -50°C or higher.
  • the preheating temperature is preferably 100°C or higher, more preferably 105°C or higher, even more preferably 108°C or higher, particularly preferably 110°C or higher.
  • the preheating temperature is preferably 150°C or lower, more preferably 140°C or lower, even more preferably 135°C or lower, particularly preferably 130°C or lower. If the preheating temperature is too low, it will be difficult to advance the orientation of amorphous molecular chains, and it will tend to be difficult to sufficiently increase the mesophase orientation parameter. On the other hand, if the preheating temperature is too high, thickness unevenness tends to occur during stretching.
  • the preheating time varies depending on the heating method, but for example, in the case of heating with hot air from a tenter, it is preferably 1 to 120 seconds, more preferably 2 to 60 seconds, and the appropriate time is set by taking into account the thickness of the film, wind speed, etc. can.
  • the stretching temperature is preferably 85°C or higher, more preferably 88°C or higher, and still more preferably 90°C or higher.
  • the stretching temperature is preferably 105°C or lower, more preferably 102°C or lower, even more preferably 100°C or lower. If the stretching temperature is too high, the stretching stress will be insufficient, resulting in uneven thickness, and it will also tend to be difficult to sufficiently increase the mesophase orientation parameter. On the other hand, if the stretching temperature is too low, crystals tend to grow excessively, making it difficult to sufficiently increase the mesophase orientation parameter.
  • the present inventors have discovered that by controlling the stretching temperature within the above range, it is possible to effectively increase the mesophase orientation parameter while suppressing thickness unevenness even when the preheating temperature is increased. .
  • the above conditions are preferably applied to stretching at least in the main stretching direction.
  • main stretching is performed in the longitudinal direction using the speed difference between the rolls, the above conditions do not necessarily need to be applied because the strain rate is generally sufficiently large and the orientation of amorphous molecular chains tends to proceed. .
  • the longitudinal stretching ratio is preferably 0.7 times, more preferably 0.8 times or more, still more preferably 0.9 times or more, particularly preferably is 0.95 times or more.
  • the longitudinal stretching ratio is preferably 1.5 times or less, more preferably 1.3 times or less, even more preferably 1.2 times or less, particularly preferably 1.1 times or less, and most preferably 1.05 times or less.
  • longitudinal stretching may not be performed, that is, the longitudinal stretching ratio may be 1.
  • the transverse stretching ratio is preferably 4.0 to 7.0 times.
  • the lower limit of the transverse stretching ratio is more preferably 4.5 times, still more preferably 4.7 times, particularly preferably 5.0 times.
  • the upper limit of the transverse stretching ratio is more preferably 6.5 times, still more preferably 6.0 times, particularly preferably 5.7 times, and most preferably 5.5 times.
  • the transverse stretching ratio is preferably 0.7 times or more, more preferably 1.0 times or more, and even more preferably 1.3 times. More preferably, it is 1.5 times or more, particularly preferably 1.7 times or more, and most preferably 2.0 times or more.
  • the transverse stretching ratio is preferably 3.0 times or less, more preferably 2.7 times or less, even more preferably 2.5 times or less.
  • the film of the present invention when used as a polarizer protective film to make a polarizing plate laminated with a polarizer made of PVA stretched in the length direction, the polarizing plate is likely to tear or crack in the length direction.
  • the lateral stretching ratio is more than 1 times. From the viewpoint of suppressing the relaxation of amorphous molecular chains during stretching and increasing the rigid amorphous fraction, it is preferable to increase the longitudinal stretching ratio.
  • the longitudinal stretching ratio is preferably 4.0 times or more, more preferably 4.5 times or more, still more preferably 4.7 times or more, particularly preferably 5.0 times or more.
  • the longitudinal stretching ratio is preferably 7.0 times, more preferably 6.5 times, particularly preferably 6.0 times. It is 0 times. It is possible to effectively increase the rigid amorphous fraction by setting the longitudinal and transverse stretching ratios within the above ranges, but on the other hand, as the stretching ratio in the slow axis direction increases, crystal growth becomes dominant and mesophase orientation occurs. It tends to be difficult to sufficiently increase the parameters. Therefore, in order to promote the orientation of the amorphous molecular chains during stretching and control the mesophase orientation parameter within the above range, it is necessary to preheat at a sufficiently high temperature as described above and then heat it to a moderately lower temperature. It is preferable to carry out the stretching.
  • the ratio of the longitudinal stretch ratio to the transverse stretch ratio, the stretching temperature, and the thickness of the film In order to control the retardation within the above range, it is preferable to control the ratio of the longitudinal stretch ratio to the transverse stretch ratio, the stretching temperature, and the thickness of the film. If the difference between the longitudinal and lateral stretching ratios is too small, it tends to be difficult to increase the retardation.
  • the rigid amorphous fraction In order to effectively suppress the embrittlement of the polyethylene terephthalate resin film due to crystallization during heat treatment, it is preferable to increase the rigid amorphous fraction. Specifically, it is preferable to suppress the relaxation of amorphous molecular chains during stretching, and it is preferable to increase the strain rate during stretching in the slow axis direction of the film.
  • the strain rate is preferably 13%/sec or more, more preferably 15%/sec or more, particularly preferably 17%/sec or more.
  • the upper limit is preferably 60%/sec from the viewpoint of film formability.
  • the strain rate is a parameter expressed as (nominal strain (%) in stretching in the slow axis direction)/(required time (sec) in stretching in the slow axis direction), and the nominal strain (%) is determined by ((deformation amount (mm))/(initial length (mm))) ⁇ 100.
  • the heat treatment temperature during the high temperature treatment is preferably at least 5° C. higher than the heat treatment temperature during the low temperature treatment.
  • the lower limit of the temperature of the high-temperature treatment is more preferably 10°C or more higher than the low-temperature treatment, even more preferably 15°C or more higher, and 20°C or more higher. Particularly preferred.
  • the upper limit temperature of the high-temperature treatment is more preferably the temperature of the low-temperature treatment +80°C or less, further preferably the temperature of the low-temperature treatment +75°C or less, particularly preferably the temperature of the low-temperature treatment +70°C or less, and the temperature of the low-temperature treatment +65°C or less. is most preferable.
  • the heat treatment temperature during the high temperature treatment is preferably 150°C or higher, more preferably 160°C or higher, particularly preferably 170°C or higher, and most preferably 180°C or higher.
  • the heat treatment temperature during high temperature treatment is preferably 220°C or lower, more preferably 210°C or lower, particularly preferably 200°C or lower. It is.
  • the heat treatment temperature during the low temperature treatment is preferably 100°C or higher, more preferably 110°C or higher, particularly preferably 120°C or higher, and most preferably 130°C or higher.
  • the heat treatment temperature during low temperature treatment is preferably 170°C or lower, more preferably 160°C or lower, and particularly preferably 150°C or lower. below °C.
  • the time for the high temperature treatment is preferably 1 second or more, more preferably 3 seconds or more, even more preferably 5 seconds or more, particularly preferably 7 seconds or more.
  • the time for the high temperature treatment is preferably 60 seconds or less, more preferably 40 seconds or less, even more preferably 30 seconds or less.
  • the preferred time range for low temperature treatment is also the same as the preferred time range for high temperature treatment.
  • the temperature range for low-temperature processing will apparently be passed for a certain amount of time; however, for stable production, it is necessary to lower the temperature of low-temperature processing.
  • a method in which the material is passed through an oven at a temperature that can be maintained is preferred.
  • the film After the low-temperature treatment, the film is cooled to a temperature at which it can be rolled up, and if necessary, the ends in the width direction are cut and rolled up.
  • relaxation treatment may be performed between heat treatment and cooling.
  • the relaxation process is performed by shrinking in at least one of the TD direction and the MD direction.
  • the relaxation rate is preferably 0.1 to 5%, more preferably 0.2 to 4%.
  • the relaxation treatment may be performed during high-temperature treatment, between high-temperature treatment and low-temperature treatment, during low-temperature treatment, or during cooling, and may be performed over multiple steps.
  • the present inventors performed preheating at a sufficiently high temperature and then stretching at a lower temperature, and simultaneously carried out the heat treatment in two stages: high temperature treatment followed by low temperature treatment. By doing so, it is possible to effectively increase the mesophase orientation parameter, and it is possible to prevent breakage starting from the cut part during slitting, fine powder due to scraping of the polyethylene terephthalate resin film, and product roll edges due to film elongation.
  • the present inventors have discovered that this method is effective in suppressing the standing ears of the ears, and have completed the present invention.
  • the monomer units of the polyethylene terephthalate resin constituting the polyethylene terephthalate resin film be ethylene terephthalate.
  • the content of ethylene terephthalate units is preferably 90 mol% or more, more preferably 95 mol% or more.
  • the copolymerization component may include a known acid component or glycol component.
  • a particularly preferred 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 relatively easily obtain a large retardation even if the film is thin.
  • the light transmittance of the polyethylene terephthalate resin film of the present invention at a wavelength of 380 nm may be set to 20% or less.
  • the light transmittance at 380 nm is more preferably 15% or less, further preferably 10% or less, particularly preferably 5% or less.
  • the transmittance in the present invention is measured in a direction perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500 model).
  • the ultraviolet absorber used in the present invention is a known substance.
  • the ultraviolet absorber include organic ultraviolet absorbers and inorganic ultraviolet absorbers, and organic ultraviolet absorbers are preferred from the viewpoint of transparency.
  • organic ultraviolet absorbers include benzotriazole-based, benzophenone-based, cyclic iminoester-based, and combinations thereof, but there is no particular limitation as long as the absorbance is within the above range.
  • benzotoazole type and cyclic imino ester type are particularly preferable.
  • benzophenone UV absorbers examples include 2-[2'-hydroxy-5'-(methacryloyloxymethyl)phenyl]-2H-benzotriazole, 2-[2' -Hydroxy-5'-(methacryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(methacryloyloxypropyl)phenyl]-2H-benzotriazole, 2,2'-dihydroxy- 4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2-( 2'-Hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(5-chloro(2H)-
  • additives include inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light stabilizers, flame retardants, heat stabilizers, antioxidants, and antigelation agents. , surfactants, etc. Further, in order to achieve high transparency, it is also preferable that the polyethylene terephthalate resin film does not substantially contain particles.
  • substantially no particles means, for example, in the case of inorganic particles, the content is 50 ppm or less, preferably 10 ppm or less, particularly preferably below the detection limit when the inorganic element is quantified by fluorescent X-ray analysis. means.
  • the ultraviolet absorber into the polyethylene terephthalate resin film in the present invention a combination of known methods can be employed, but for example, using a kneading extruder in advance, the dried ultraviolet absorber and polymer raw material are combined. It can be blended by a method of preparing a masterbatch by blending the above, and mixing the predetermined masterbatch and polymer raw materials during film formation.
  • the concentration of the ultraviolet absorber in the masterbatch is preferably 5 to 30% by mass in order to uniformly disperse the ultraviolet absorber and to mix it economically.
  • the masterbatch is preferably prepared using a kneading extruder at an extrusion temperature of at least the melting point of the polyethylene terephthalate raw material and at most 290° C. for 1 to 15 minutes. At 290° C. or higher, the amount of the ultraviolet absorber decreases significantly and the viscosity of the masterbatch decreases significantly. If the extrusion time is less than 1 minute, uniform mixing of the ultraviolet absorbent tends to be difficult. At this time, a stabilizer, a color tone adjusting agent, and an antistatic agent may be added as necessary.
  • the film may have a multilayer structure of at least three layers, and an ultraviolet absorber may be added to the intermediate layer of the film.
  • an ultraviolet absorber may be 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 produced as follows. Single pellets of polyethylene terephthalate resin for the outer layer, and pellets of polyethylene terephthalate resin and a masterbatch containing an ultraviolet absorber for the intermediate layer are mixed in a predetermined ratio, dried, and then put into a known extruder for melt lamination. The material is supplied, extruded into a sheet through a slit die, and cooled and solidified on a casting roll to produce an unstretched film.
  • the film layers constituting both outer layers and the film layer constituting the intermediate layer are laminated using two or more extruders, a three-layer manifold or a merging block (for example, a merging block having a square merging part),
  • the three-layer sheet is extruded from the die and cooled with a casting roll to form an unstretched film.
  • the filtration particle size (initial filtration efficiency of 95%) of the filter medium used for high-precision filtration of molten resin is preferably 15 ⁇ m or less. When the filtration particle size of the filter medium exceeds 15 ⁇ m, removal of foreign matter of 20 ⁇ m or more tends to be insufficient.
  • polyethylene terephthalate resin film of the present invention can be subjected to corona treatment, coating treatment, flame treatment, etc. in order to improve the adhesiveness of the film surface.
  • the film of the present invention in order to improve the adhesion of the surface of the polyethylene terephthalate resin film, it is preferable that the film of the present invention has an easy-to-adhesion layer (adhesion-modifying coating layer) on at least one side.
  • the easily bonding layer can be appropriately selected from conventionally known materials, but preferably has at least one type of polyester resin, polyurethane resin, or polyacrylic resin as its main component.
  • the term "main component” refers to a component that accounts for 50% by mass or more of the solid components constituting the easily adhesive layer.
  • the coating liquid used to form the easily adhesive layer is preferably an aqueous coating liquid containing at least one of water-soluble or water-dispersible copolymerized polyester resins, acrylic resins, and polyurethane resins.
  • these coating liquids include water-soluble or water-dispersible coating liquids disclosed in Japanese Patent No. 3567927, Japanese Patent No. 3589232, Japanese Patent No. 3589233, Japanese Patent No. 3900191, Japanese Patent No. 4150982, etc.
  • Examples include polymerized polyester resin solutions, acrylic resin solutions, and polyurethane resin solutions.
  • the easily adhesive layer can be obtained, for example, by applying the coating solution on one or both sides of an unstretched film or 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 adhesive layer is preferably controlled to 0.05 to 0.20 g/m 2 . If the coating amount is less than 0.05 g/m 2 , the adhesiveness may be insufficient. On the other hand, if the coating amount exceeds 0.20 g/m 2 , blocking resistance may decrease.
  • the final thickness of the easily adhesive layer obtained after stretching is preferably 1 ⁇ m or less, more preferably 0.5 ⁇ m or less, and even more preferably 0.2 ⁇ m. It is as follows.
  • the coating amounts of the easily adhesive layer on both sides may be the same or different, and each can be set independently within the above range. .
  • particles to the easy-adhesion layer in order to impart slipperiness. It is preferable to use particles having an average particle diameter of 2 ⁇ m or less. When the average particle diameter of the particles exceeds 2 ⁇ m, the particles tend to fall off from the coating layer.
  • particles to be included in the adhesive layer include 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 to the adhesive layer singly or in combination of two or more.
  • a known method can be used. For example, reverse roll coating method, gravure coating method, kiss coating method, roll brushing method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, etc. Or it can be done in combination.
  • Particles are photographed using a scanning electron microscope (SEM), and the maximum diameter of 300 to 500 particles (between the two furthest points) is distance), and the average value is taken as the average particle size.
  • SEM scanning electron microscope
  • Functions such as a hard coat layer, an antireflection layer, a low reflection layer, an antiglare layer, a light diffusion layer, a lens layer, a prism layer, etc. are formed on at least one surface of the polyethylene terephthalate resin film of the present invention via an easily adhesive layer. It is also a preferred embodiment to laminate layers.
  • the thickness of the polyethylene terephthalate resin film of the present invention is arbitrary, it is preferably in the range of 25 to 300 ⁇ m. Even with a film having a thickness of less than 25 ⁇ m, it is theoretically possible to obtain a retardation of 3000 nm or more. However, in this case, the anisotropy of the mechanical properties of the film becomes significant, and there is a tendency for the film to tear, tear, etc. easily.
  • More preferable thicknesses of the polyethylene terephthalate resin film of the present invention are listed as upper limits of 200 ⁇ m, 150 ⁇ m, 120 ⁇ m, 100 ⁇ m, 90 ⁇ m, 80 ⁇ m, 75 ⁇ m, and 70 ⁇ m.
  • the lower limits are listed as 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, and 50 ⁇ m.
  • the polyethylene terephthalate resin film of the present invention can be used for various purposes, and the optimal thickness range can be selected from the above range depending on the purpose.
  • the upper limit of the thickness can be selected to be 120 ⁇ m or less, and the lower limit is as described above.
  • the thickness may be more preferably 65 ⁇ m or less, more preferably 60 ⁇ m or less, and particularly preferably 55 ⁇ m or less.
  • the preferable ranges are the same as those listed for the polarizer protective film.
  • the lower limit of the thickness can be selected from the above lower limits to a value of 40 ⁇ m or more, and the upper limit of the thickness is , a value of 150 ⁇ m or more can be selected from the above upper limit values.
  • the thickness unevenness of the film is small. Since the stretching temperature and the stretching ratio have a large effect on the thickness unevenness of the film, it is preferable to optimize the film forming conditions also from the viewpoint of thickness unevenness. In particular, when the longitudinal stretching ratio is lowered in order to increase retardation, longitudinal thickness unevenness may become worse. Since there is a region in which longitudinal thickness unevenness becomes extremely poor in a certain specific range of stretching ratio, it is desirable to set 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, even more preferably 4.0% or less, and even more preferably 3.0% or less. It is particularly preferable that there be.
  • the polyethylene terephthalate resin film of the present invention preferably has an Nz coefficient expressed by
  • the Nz coefficient can be determined as follows.
  • the orientation axis direction of the film was determined using a molecular orientation meter (Oji Scientific Instruments Co., Ltd., MOA-6004 type molecular orientation meter), and the refractive index of the two axes (ny, nx, However, ny>nx) and the refractive index in the thickness direction (nz) are determined using an Abbe refractometer (manufactured by Atago, NAR-4T, measurement wavelength 589 nm).
  • the Nz coefficient can be determined by substituting nx, ny, and nz thus obtained into the formula expressed as
  • the Nz coefficient is more preferably 1.65 or less, still more preferably 1.63 or less.
  • the lower limit of the Nz coefficient is preferably 1.2. Further, in order to maintain the mechanical strength of the film, the lower limit of the Nz coefficient is preferably 1.3 or more, more preferably 1.4 or more, still more preferably 1.45 or more.
  • the ratio of retardation (Re) to thickness direction retardation (Rth) (Re/Rth) of the polyethylene terephthalate resin film is preferably 0.2 or more, more preferably 0.5 or more, and even more preferably 0.6. That's all. The larger the ratio (Re/Rth) is, the more preferable it is.
  • 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 determining nx, ny, nz and the film thickness d (nm), and calculating the average value of ( ⁇ Nxz ⁇ d) and ( ⁇ Nyz ⁇ d). Note that nx, ny, and nz are determined using an Abbe refractometer (manufactured by Atago Corporation, NAR-4T, measurement wavelength 589 nm).
  • the surface roughness (SRa) (JIS B0601:1994) of the polyethylene terephthalate resin film is preferably 0.05 ⁇ m or less, more preferably 0.01 ⁇ m or less, and even more preferably 0. It is .005 ⁇ m or less.
  • SRa is preferably 0.0001 ⁇ m or more, more preferably 0.0005 ⁇ m or more to ensure the slipperiness of the film.
  • the ten-point average surface roughness (SRz) (JIS B0601:1994) of the polyethylene terephthalate resin film is preferably 1.0 ⁇ m or less, more preferably 0.70 ⁇ m or less, on at least one side, and more preferably on both sides. It is preferably 0.50 ⁇ m or less, particularly preferably 0.30 ⁇ m or less, and most preferably 0.2 ⁇ m or less.
  • SRz is preferably 0.001 ⁇ m or more, more preferably 0.005 ⁇ m or more.
  • the phenomenon of increased surface roughness is often caused by coarse particles such as particle aggregates and catalyst residues. It is possible to prevent the film from falling off and causing scratches on the film surface, and it is also possible to prevent this from becoming bright spots or dark spots that degrade image quality. Further, deterioration in image clarity and contrast can also be suppressed.
  • the surface is an easily adhesive layer or other coating layer
  • methods such as filtering the coating solution with a filter after preparing it or installing a filter in the line that sends the coating solution to the coating die are adopted. It is preferable.
  • the number of foreign particles with a long diameter of 100 ⁇ m or more in the polyethylene terephthalate resin film is 2 or less.
  • the major axis of the foreign matter observed as such is 100 ⁇ m or more. Examples of foreign substances in the film include aggregates of lubricant particles.
  • the film In addition to removing aggregates using a filter with a small pore size during film formation, it is also preferable to form the film into a multilayer structure and use lubricant particles only in the surface layer. Also preferred is a method in which lubricant particles are not used in the film, but are used in the adhesive coating on the surface.
  • degraded resin products can also become foreign substances in the film.
  • Hard foreign objects in the molten resin can be removed with the filter described above, but gel-like foreign objects caused by thermal deterioration of the molten resin can be deformed to some extent at the molten resin temperature, so even if the pores are larger than the filter's pore size, the filter cannot be used.
  • large heat-degraded substances they may be cut off by the filter and the number of foreign substances may increase.
  • heat-degraded resin products generated in the line after the filter are included in the film as they are. These foreign substances not only cannot follow the stretching orientation of the surrounding resin in the stretching process, but also disturb the stretching orientation of the surrounding resin, and appear as bright spots when measured using crossed nicols.
  • the filter may create voids between the film and the resin during stretching and become foreign objects in the film.
  • the pore size of the filter does not mean that foreign matter larger than that size will not pass through, but even foreign matter larger than the pore size will pass through to a certain degree.
  • the number of foreign substances having a long diameter of 100 ⁇ m or more in the polyethylene terephthalate resin film is one or less, and preferably zero, that is, there is no foreign substance.
  • the number of foreign substances having a long diameter of 50 ⁇ m or more in the polyethylene terephthalate resin film is preferably 5 or less, more preferably 3 or less, still more preferably 1 or less, and particularly preferably 0.
  • the number of foreign particles with a long diameter of 20 ⁇ m or more in the polyethylene terephthalate resin film is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less, particularly preferably 1 or less, and most preferably 0. It is.
  • the portion where the resin remains in the path through which the molten resin passes In order to reduce the foreign matter in the film, it is preferable to minimize the portion where the resin remains in the path through which the molten resin passes. Specifically, in the extruder, it is preferable to minimize the steps between screw elements, between the blocks of the barrel, and at the joints of the piping. Further, it is preferable to design the piping, the filter housing, the filter element, the flow path of the mouthpiece, etc. to reduce resin retention, and to reduce the roughness of the inner walls of these areas.
  • the haze of the polyethylene terephthalate resin film is preferably 5% or less, more preferably 3% or less, even more preferably 2% or less, particularly preferably 1.5% or less.
  • the lower limit of haze is preferably 0.01% or more, more preferably 0.1% or more.
  • SRa and SRz are SRa and SRz, respectively, of the surface of the original polyethylene terephthalate resin film before coating with a functional layer such as a low-reflection layer, which will be described later. If so, use the value for the easily adhesive layer side. The same goes for Hayes.
  • Haze can be measured using a turbidity meter (NHD2000, manufactured by Nippon Denshoku Kogyo) in accordance with JIS-K7105.
  • turbidity meter manufactured by Nippon Denshoku Kogyo
  • the intrinsic viscosity (IV) of the resin constituting the film is preferably 0.45 to 1.5 dL/g.
  • the IV is preferably 0.5 to 1.5 dL/g.
  • the lower limit of IV is more preferably 0.53 dL/g, still more preferably 0.55 L/g.
  • the upper limit of IV is more preferably 1.2 dL/g, further preferably 1 dL/g, particularly preferably 0.8 dL/g.
  • the lower limit of IV is preferably 0.45 dL/g, more preferably 0.48 dL/g, even more preferably 0.5 dL/g, and particularly preferably 0.53 dL/g.
  • the upper limit of IV is more preferably 1 dL/g, more preferably 0.8 dL/g, even more preferably 0.75 dL/g, particularly preferably 0.7 dl/g.
  • the film will have excellent mechanical strength such as impact resistance, and it can be manufactured efficiently without placing a large load on equipment.
  • IV is measured by dissolving 0.2 g of the sample in 50 ml of a mixed solvent of phenol/1,1,2,2-tetrachloroethane (60/40 (weight ratio)) and using an Ostwald viscometer at 30°C. This is what I did.
  • the amount of antimony atoms in the residue insoluble in the mixed solvent of parachlorophenol and tetrachloroethane is preferably 50 mg or less, and preferably 30 mg or less, per 1 kg of resin constituting the film.
  • the amount is more preferably 20 mg or less, even more preferably 10 mg or less, and most preferably 5 mg or less.
  • the amount of antimony atoms in the residue is preferably as small as possible, but the lower limit is preferably 0.1 mg, more preferably over 0.5 mg, and even more preferably over 1 mg.
  • the polarizer protective film is preferably formed of a resin polymerized using an antimony compound as a catalyst, particularly a polyester resin.
  • antimony compound used as a catalyst examples include antimony trioxide, antimony pentoxide, antimony acetate, and antimony glycoxide, and antimony trioxide (Sb 2 O 3 ) is preferable.
  • a titanium compound catalyst such as tetrabutoxy titanate, or an aluminum catalyst such as basic aluminum acetate and a hindered phenol-containing phosphate ester (for example, Irganox 1222) may be used in combination.
  • an aluminum catalyst such as basic aluminum acetate and a hindered phenol-containing phosphate ester (for example, Irganox 1222) may be used in combination.
  • a polymerization stabilizer such as trimethyl phosphate and phosphoric acid
  • magnesium compounds such as magnesium acetate
  • calcium compounds such as calcium acetate.
  • the amount of antimony atoms in the residue insoluble in the mixed solvent of the resin used when manufacturing the film should be below the above level. is preferred.
  • Examples of methods for reducing the amount of antimony atoms in the residue insoluble in the mixed solvent of the polyester resin to below the above level include the following methods, and these methods can be used alone or in combination.
  • the amount of antimony added to the polyester resin after polymerization is preferably 300 ppm or less, more preferably 250 ppm or less, still more preferably 220 ppm or less, particularly preferably 200 ppm or less. Note that the lower limit of the amount of antimony is preferably 30 ppm, more preferably 50 ppm, particularly 80 ppm.
  • Adding the antimony compound as a solution or slurry in ethylene glycol is preferably 300 ppm or less, more preferably 250 ppm or less, still more preferably 220 ppm or less, particularly preferably 200 ppm or less. Note that the lower limit of the amount of antimony is preferably 30 ppm, more preferably 50 ppm, particularly 80 ppm.
  • the concentration of the antimony compound is preferably 10% by mass or less, more preferably 7% by mass or less, particularly 5% by mass or less.
  • the maximum temperature for polymerization of the polyester resin is preferably 290°C or lower, more preferably 285°C or lower.
  • the amount added is preferably 15 to 120 ppm, more preferably 20 to 100 ppm, and even more preferably 25 to 80 ppm in terms of phosphorus atomic weight, relative to the polyester resin after polymerization.
  • the magnesium atomic weight or calcium atomic weight is preferably 30 to 120 ppm, more preferably 40 to 100 ppm.
  • the phosphorus compound is added after the magnesium compound or the calcium compound is added, and at that time, it is preferable to add the phosphorus compound in multiple stages.
  • the polyethylene terephthalate resin film of the present invention can be used as a polarizer protective film.
  • the polarizing plate of the present invention has a structure in which a polarizer protective film made of the polyethylene terephthalate resin film of the present invention is laminated on at least one surface of a polarizer.
  • the polarizer may be made of polyvinyl alcohol (PVA) dyed with iodine.
  • a film without birefringence such as TAC film, acrylic film, or norbornene film
  • a polarizer protective film, optical compensation film, etc. be not laminated on the other surface.
  • a coating layer such as a hard coat layer may be laminated on the polarizer on the other surface. It is also a preferred embodiment to apply various hard coats to the surface of the polarizing plate used in the present invention for the purpose of preventing reflections, suppressing glare, suppressing scratches, and the like.
  • the polarizing plate of the present invention can be used as a component of an image display device such as a liquid crystal display device or an organic EL display device, as described later.
  • a liquid crystal panel is composed of a rear module, a liquid crystal cell, and a front module in the order from the side facing the backlight source to the image display side (viewing side).
  • the rear module and the front module generally include 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
  • the polarizing plate is arranged on the side where an image is displayed (viewing side).
  • the liquid crystal display device of the present invention includes at least a backlight source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates.
  • a backlight source two polarizing plates
  • a liquid crystal cell disposed between the two polarizing plates.
  • at least one of the two polarizing plates is the polarizing plate of the present invention described above.
  • the structure of the backlight may be an edge light type in which the constituent members are a light guide plate, a reflection plate, etc., or a direct type type.
  • the backlight light source installed in the liquid crystal display device of the present invention is not particularly limited, but has a peak top of the emission spectrum in each wavelength region 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.
  • a white light source can preferably be used. Examples of such light sources include, for example, a white light source using quantum dot technology, and a phosphor type using a blue LED and a phosphor that has emission peaks in the R (red) and G (green) regions when excited by excitation light.
  • a white LED light source a three-wavelength white LED light source, a white LED light source combining a red laser, a blue light emitting diode, and a fluoride phosphor (also referred to as "KSF") that is at least K 2 SiF 6 :Mn 4+ as a phosphor.
  • KSF fluoride phosphor
  • conventionally used light emitting diodes that emit blue or ultraviolet light using compound semiconductors and phosphors (such as yttrium-aluminum-garnet-based yellow phosphors and terbium-aluminum-garnet-based yellow phosphors) are also available.
  • a phosphor-type white LED in which a phosphor-type white LED is also preferably used.
  • the arrangement of the polarizer protective film made of the polyethylene terephthalate resin film of the present invention in a liquid crystal display device is not particularly limited; In the case of a liquid crystal display device with a polarizing plate placed on the viewing side), a polarizer protective film on the incident light side of the polarizing plate placed on the incident light side, and/or a polarizer protective film placed on the outgoing light side of the polarizing plate placed on the incident light side. It is preferable that the polarizer protective film on the exit light side of the plate is a polarizer protective film made of the polyethylene terephthalate resin film of the present invention.
  • a particularly preferred embodiment is one in which the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side is the polyethylene terephthalate resin film of the present invention.
  • the polarizer protective film made of 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 polarizer protective film made of the polyethylene terephthalate resin film of the present invention in locations where polarizing properties are required, it may not be used as a protective film for the polarizing plate in such specific locations. preferable.
  • the screen size of the liquid crystal display device of the present invention is not particularly limited, but preferably 32 inches (diagonal length: 32 inches) or more, and more preferably 42 inches or more. Particularly preferred is a size of 50 or more.
  • Organic EL Display Device It is preferable that a circularly polarizing plate is disposed on the viewing side of the organic EL display device. External light is reflected by the metal electrode of the organic EL cell and emitted to the viewing side, and when viewed from the outside, the display surface of the organic EL display device may appear mirror-like. In order to block such specular reflection of external light, a circularly polarizing plate is preferably disposed on the viewing side of the organic EL cell. For example, a 1/4 wavelength plate (1/4 wavelength layer) laminated on the polarizing plate of the present invention described above can be used as a circularly polarizing plate for an organic EL display device.
  • a touch panel usually has one or more transparent conductive films.
  • a transparent conductive film has a structure in which a transparent conductive layer is laminated on a base film.
  • the polyethylene terephthalate resin film of the present invention can be used as the base film.
  • the type and method of the touch panel are not particularly limited, but examples include a resistive touch panel and a capacitive touch panel.
  • the transparent conductive layer may be directly laminated on the base film, but it can also be laminated via an easily adhesive layer and/or various other layers.
  • other layers include a hard coat layer, an index matching (IM) layer, and a low refractive index layer.
  • IM index matching
  • the IM layer itself has a laminated structure of a high refractive index layer/low refractive index layer (the transparent conductive thin film side is the low refractive index layer), and by using this, when viewing the liquid crystal display screen, the ITO Patterns can be made more difficult to see.
  • the transparent conductive layer on the base film can be formed from a conductive metal oxide.
  • the conductive metal oxide constituting the transparent conductive layer is not particularly limited, and may be selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, and tungsten.
  • a conductive metal oxide of at least one selected metal is used.
  • the metal oxide may further contain metal atoms shown in the above group, if necessary.
  • Preferred transparent conductive layers are, for example, tin-doped indium oxide (ITO) layers and antimony-doped tin oxide (ATO) layers, preferably ITO layers.
  • the transparent conductive layer may be Ag nanowires, Ag ink, a self-assembled conductive film of Ag ink, a mesh electrode, CNT ink, or a conductive polymer.
  • the thickness of the transparent conductive layer is not particularly limited.
  • a transparent conductive layer can be formed according to a known procedure. For example, vacuum evaporation, sputtering, and ion plating can be used.
  • the transparent conductive film of the present invention may be patterned by removing a portion of the transparent conductive layer in the plane.
  • a transparent conductive film patterned with a transparent conductive layer has a pattern forming area where the transparent conductive layer is formed on the base film, and a pattern opening where the transparent conductive layer is not formed on the base film.
  • Examples of the shape of the pattern forming portion include a stripe shape and a square shape.
  • the polyethylene terephthalate resin film of the present invention can be used as a shatterproof film or a surface protection film by being laminated on the viewing side of an image display panel.
  • 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. A rectangle of 2 cm x 2 cm was cut out and used as a sample for measurement.
  • the refractive index of two orthogonal axes (refractive index in the slow axis direction: ny, refractive index in the direction perpendicular to the slow axis direction: nx), and the refractive index in the thickness direction (nz) are Abbe refracted.
  • ) was determined using a refractive index meter (manufactured by Atago Corporation, NAR-4T, measurement wavelength 589 nm), and was defined as the anisotropy of the refractive index ( ⁇ Nxy).
  • the thickness d (nm) of the film was measured using an electric micrometer (Millitron 1245D, manufactured by Finereuf Co., Ltd.), and the unit was converted into nm.
  • Retardation (Re) was determined from the product ( ⁇ Nxy ⁇ d) of the refractive index anisotropy ( ⁇ Nxy) and the film thickness d (nm).
  • the mesophase orientation parameter of the polyethylene terephthalate resin film is expressed by the above equation (1), and the total Absorbance A at 1457 cm -1 in the slow axis direction obtained by Fourier transform infrared spectroscopy (ATR-FTIR) using reflectometry 1457-slow , Absorbance A 795-slow at 795 cm -1 in the slow axis direction , the absorbance A 1457-fast at 1457 cm ⁇ 1 in the fast axis direction, and the absorbance A 795-fast at 795 cm ⁇ 1 in the fast axis direction.
  • ATR-FTIR Fourier transform infrared spectroscopy
  • ATR-FTIR measurements were performed with a polarizer inserted in the optical system, using a diamond crystal as the ATR prism, and at an incident angle of 45 degrees.
  • the slow axis of the film is arranged so as to be parallel to the transmission axis of the polarizer inserted in the optical system, and the infrared absorption spectrum A slow ( ⁇ ) was obtained.
  • the fast axis of the film was arranged so that it is parallel to the transmission axis of the polarizer inserted in the optical system, the infrared absorption spectrum A fast ( ⁇ ) was obtained.
  • the number of integrations was 64 for both the sample and the background, and the measurement was performed with a wave number resolution of 2 cm -1 and a measurement wave number range of 650 to 4000 cm -1 .
  • the penetration depth into the sample varies depending on the wave number and the baseline is curved .
  • Baseline correction was performed by multiplying by the ratio ⁇ MAX / ⁇ of the maximum wave number ⁇ MAX (cm ⁇ 1 ) within the measurement range and each wave number ⁇ (cm ⁇ 1 ).
  • the absorbance at 1456.253 cm -1 was taken as A 1457-slow or A 1457-fast
  • the absorbance at 792.7415 cm -1 was taken as A 795-slow or A 795-fast.
  • the absorbance refers to the absolute value of absorption intensity at a corresponding wave number in an infrared absorption spectrum after baseline correction.
  • the slow axis direction of the film was determined using a molecular orientation meter (MOA-6004 type molecular orientation meter, manufactured by Oji Scientific Instruments Co., Ltd.). The direction perpendicular to the slow axis direction in the plane of the film was defined as the fast axis direction.
  • the elastic modulus in the slow axis direction was evaluated by a tensile test based on section 10.3.2 of JIS K7161.
  • the test piece was cut into a rectangular shape of 180 mm x 10 mm with the slow axis direction obtained when measuring the retardation (Re) as the long side.
  • the thickness of the film was measured using an electric micrometer (Millitron 1245D, manufactured by Finereuf Co., Ltd.).
  • a tensile test was conducted by gripping the area from the marked line to the short side with a chuck so that the long side direction of the test piece was the tensile direction.
  • a precision universal testing machine manufactured by Shimadzu Corporation, Autograph AGX-V was used, the distance between the chucks was 100 mm, and the tensile speed was 100 mm/min.
  • Each measured value of load (N) was converted into nominal stress (MPa) by dividing by the initial cross-sectional area (mm 2 ) of the test piece.
  • the stroke amount (mm) of the distance between the chucks at the time of obtaining each measured value of the load was divided by the initial distance between the chucks of 100 mm to convert it into a nominal strain.
  • the slope of the nominal stress-nominal strain curve between two points of nominal strain 0.0005 and 0.0025 was calculated to obtain the elastic modulus (MPa) in the slow axis direction.
  • the chuck used was a pneumatic type (manufactured by A&D, parallel clamping type air jaw J-JFA1-1KN-09 with face J-FFA3W-1KN attached), and the air pressure was 0.5 MPa.
  • the measurement was performed without applying any reserve force for the purpose of removing slack in the test piece.
  • Breaking strength in the slow axis direction was evaluated by a tensile test based on JIS C2318, Section 7.2. In the nominal stress-nominal strain curve obtained by measuring the elastic modulus in the slow axis direction, the load at break (N) is divided by the cross-sectional area (mm 2 ) of the test piece. The breaking strength (MPa) was obtained.
  • Planar orientation coefficient ( ⁇ P) Using the refractive index value obtained when measuring the retardation (Re), the value obtained by (nx+ny)/2-nz was defined as the planar orientation coefficient ( ⁇ P).
  • Rigid amorphous fraction The rigid amorphous fraction is expressed by the above formula (2), and is indirectly calculated from the values of the mobile amorphous fraction and the mass fraction crystallinity.
  • the mobile amorphous fraction is calculated from the reversible heat capacity difference ⁇ Cp (J/(g ⁇ K)) at Tg of the reversible heat capacity curve obtained by temperature modulation DSC measurement using a differential scanning calorimeter (TA Instrument, Q100). , (( ⁇ Cp of sample)/( ⁇ Cp of completely amorphous)) ⁇ 100 (mass%).
  • TA Instrument, Q100 differential scanning calorimeter
  • ⁇ Cp of sample/( ⁇ Cp of completely amorphous) ⁇ 100 (mass%).
  • completely amorphous ⁇ Cp 0.4052 (J/(g ⁇ K)).
  • the sample was weighed at 2.0 ⁇ 0.2 mg in an aluminum pan, and measured in MDSC (registered trademark) heat only mode at an average temperature increase rate of 5.0° C./min and a modulation period of 60 seconds. Measurement data were collected at a sampling frequency of 5 Hz. Additionally, indium was used to calibrate temperature and calorific value, and sapphire was used to
  • Tg a method for calculating Tg and ⁇ Cp.
  • plot the first derivative F'(T) of the temperature T of the reversible heat capacity curve F(T) take the moving average for every 2401 points, perform smoothing processing, and then calculate the temperature value at the peak top.
  • Tg was determined by reading.
  • T1 corresponds to the start temperature of glass transition
  • T2 corresponds to the end temperature of glass transition
  • the height at the extreme end with a position 100 mm inside from the end as a reference (0 mm) was measured as the amount of protrusion, and the average value of the amount of protrusion at both ends was determined.
  • the winding tension is the tension when winding the film into a roll around a cylindrical core
  • the winding contact pressure is the tension when winding the film while pressing the touch roll against it. This is the winding contact pressure of the roll.
  • the amount of ear protrusion was within 1.0 mm.
  • the amount of ear protrusion was within 2.0 mm.
  • the amount of ear protrusion was greater than 2.0 mm.
  • 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 has a white LED as a backlight source, which is a light emitting element that is a combination of a blue light emitting diode and a yttrium-aluminum-garnet-based yellow phosphor.
  • a white image was displayed on the liquid crystal display device thus produced, and visual observation was performed from the front and diagonally of the display, and the occurrence of iridescence was determined as follows.
  • the viewing angle was defined as the angle between a line drawn from the center of the screen of the display in the normal direction (perpendicularly) and a line connecting the center of the display and the position of the eye at the time of observation.
  • ⁇ No iridescence was observed within the observation angle range of 0 to 60 degrees.
  • ⁇ Some faint iridescent spots were observed in the observation angle range of 0 to 60 degrees.
  • ⁇ Rainbow spots were clearly observed in the observation angle range of 0 to 60 degrees.
  • the same operation was performed 150 times continuously at intervals of 2 ⁇ m in the width direction of the film, that is, over 0.3 mm in the width direction of the film, and the data was imported into the analysis device.
  • the center surface average roughness (SRa) and the ten-point average surface roughness (SRz) were determined using an analyzer. Note that the measurement was performed three times, and the average value was used.
  • a polarizing plate for inspection is placed on the surface of the produced polarizing plate on the high Re polarizer protective film side so as to be in a crossed nicol state with the produced polarizing plate.
  • the polarizing plate for inspection should be a TAC film with no retardation on both sides, and should be free of scratches and foreign matter. In this state, an inspection is performed using a Nikon universal projector V-12 (projection lens 50x, transmitted illumination light flux switching knob 50x, transmitted light inspection).
  • the number of parts with a long axis of 100 ⁇ m or more, 50 ⁇ m or more of less than 100 ⁇ m, and 20 ⁇ m or more of less than 50 ⁇ m is counted, and the total number of each on the entire surface of the polarizing plate is determined.
  • the defective part due to the foreign matter detected by the above method was cut out from the polarizing plate, and the major axis was determined by observing with increased magnification using a polarizing microscope.
  • the high Re polarizer protective film surface of the polarizing plate was placed upward, so that the polarization direction was parallel to the polarization direction of the polarizer on the light source side of the polarizing microscope.
  • the obtained polyethylene terephthalate resin (A) had an intrinsic viscosity of 0.62 dl/g, and contained substantially no inert particles or internally precipitated particles. (Hereafter abbreviated as PET(A).)
  • Example 1 After drying 90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing ultraviolet absorber as raw materials for the base film intermediate layer at 135° C. for 6 hours under reduced pressure (1 Torr). , supplied to extruder 2 (for intermediate layer II layer), and dried PET (A) by a conventional method and supplied to extruder 1 (for outer layer I layer and outer layer III layer), and melted at 285 ° C. did.
  • the adhesion-modifying coating solution was applied to 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 , and then dried at 80° C. for 20 seconds. .
  • a cartridge filter with a 95% separation particle size of 10 ⁇ m was installed in the line for sending the coating liquid 1 to the coating die to remove particle aggregates.
  • the unstretched film with this coated layer formed thereon is introduced into a tenter stretching machine, and while the edges of the film are held with clips, the film is introduced into a hot air zone at a temperature of 138°C for preheating, and then the film is stretched 5.0 times in the width direction. , and stretched at a temperature of 90° C. and a strain rate of 17.2%/sec. Next, while maintaining the stretched width in the width direction, it is heat-treated in a hot air zone at a temperature of 210°C, then introduced into a hot air zone at a temperature of 160°C, and further subjected to a 3% relaxation treatment in the width direction, so that the film thickness is approximately A 65 ⁇ m uniaxially oriented PET film was obtained.
  • the difference between the inner diameter of the gasket at the joint part of the flange of the pipe through which the molten resin passes and the inner diameter of the pipe is 50 ⁇ m or less, and the amount of resin extruded is 1.2 times the amount set at the start of operation.
  • Example 2 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 was introduced into a tenter stretching machine, and while holding the edges of the film with clips, it was introduced into a hot air zone at a temperature of 132°C to preheat it. Thereafter, it was stretched at a temperature of 90° C. and a strain rate of 17.2%/sec so as to be 5.0 times larger in the width direction.
  • Example 3 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 except for changing the film thickness was introduced into a tenter stretching machine, and the film was heated at a temperature of 130° C. while holding the ends of the film with clips. After being guided into a hot air zone and preheated, it was stretched at a temperature of 90° C. and a strain rate of 20.0%/sec so as to be 5.8 times the width in the width direction.
  • Example 4 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 except for changing the film thickness was introduced into a tenter stretching machine, and while holding the edges of the film with clips, the film was heated at a temperature of 120°C. After being guided into a hot air zone and preheated, it was stretched at a temperature of 102° C. and a strain rate of 39.3%/sec so as to be 5.6 times the width in the width direction.
  • Example 5 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 except for changing the film thickness was introduced into a tenter stretching machine, and the film was heated at a temperature of 100° C. while holding the ends of the film with clips. After being guided into a hot air zone and preheated, it was stretched at a temperature of 90° C. and a strain rate of 25.2%/sec so as to be 4.5 times the width in the width direction.
  • the film is heat treated in a hot air zone at a temperature of 200°C, then introduced into a hot air zone at a temperature of 160°C, and further subjected to a 3% relaxation treatment in the width direction, so that the film thickness is approximately A 60 ⁇ m uniaxially oriented PET film was obtained.
  • Example 1 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 except for changing the film thickness was introduced into a tenter stretching machine, and the film was heated at a temperature of 100° C. while holding the ends of the film with clips. After being guided into a hot air zone and preheated, it was stretched at a temperature of 100° C. and a strain rate of 34.6%/sec so as to be 5.0 times the width in the width direction.
  • the film is heat treated in a hot air zone at a temperature of 180°C, then introduced into a hot air zone at a temperature of 180°C, and further subjected to a 3% relaxation treatment in the width direction, so that the film thickness is approximately A 60 ⁇ m uniaxially oriented PET film was obtained.
  • Example 2 A uniaxially oriented PET film having a film thickness of approximately 65 ⁇ m was obtained in the same manner as in Example 2 except that the temperature during stretching was 80° C.
  • Example 4 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 except for changing the film thickness was introduced into a tenter stretching machine, and while holding the edges of the film with clips, the film was heated to 115°C. After being guided into a hot air zone and preheated, it was stretched at a temperature of 102° C. and a strain rate of 39.3%/sec so as to be 5.6 times the width in the width direction.
  • the film is heat treated in a hot air zone at a temperature of 180°C, then introduced into a hot air zone at a temperature of 180°C, and further subjected to a 3% relaxation treatment in the width direction, so that the film thickness is approximately A 25 ⁇ m uniaxially oriented PET film was obtained.
  • Example 5 An unstretched film (with a coated layer already formed) produced in the same manner as in Example 1 except for changing the film thickness was introduced into a tenter stretching machine, and while holding the edges of the film with clips, the film was heated to 90°C. After being guided into a hot air zone and preheated, it was stretched at a temperature of 90° C. and a strain rate of 25.2%/sec so as to be 4.5 times the width in the width direction.
  • the film is heat treated in a hot air zone at a temperature of 200°C, then introduced into a hot air zone at a temperature of 160°C, and further subjected to a 3% relaxation treatment in the width direction, so that the film thickness is approximately A 60 ⁇ m uniaxially oriented PET film was obtained.
  • Table 1 shows the results of measurements on the PET films obtained in Examples and Comparative Examples.
  • a polyethylene terephthalate resin film that has excellent processability and can particularly effectively suppress the occurrence of breakage and ridges during slitting. Further, it is possible to provide a polarizing plate, a transparent conductive film, a touch panel, and an image display device such as a liquid crystal display device or an organic EL display device using the polyethylene terephthalate resin film.

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