WO2022158235A1 - Procédé de fabrication de film polarisant - Google Patents

Procédé de fabrication de film polarisant Download PDF

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Publication number
WO2022158235A1
WO2022158235A1 PCT/JP2021/047761 JP2021047761W WO2022158235A1 WO 2022158235 A1 WO2022158235 A1 WO 2022158235A1 JP 2021047761 W JP2021047761 W JP 2021047761W WO 2022158235 A1 WO2022158235 A1 WO 2022158235A1
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Prior art keywords
based resin
pva
film
stretching
treatment
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PCT/JP2021/047761
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English (en)
Japanese (ja)
Inventor
直樹 藤本
理 小島
周作 後藤
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日東電工株式会社
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Application filed by 日東電工株式会社 filed Critical 日東電工株式会社
Priority to KR1020237024444A priority Critical patent/KR20230129451A/ko
Priority to CN202180091354.XA priority patent/CN116710819A/zh
Publication of WO2022158235A1 publication Critical patent/WO2022158235A1/fr

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    • 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
    • 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
    • B29C55/06—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique parallel with the direction of feed
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2329/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
    • C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
    • C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Definitions

  • the present invention relates to a method for manufacturing a polarizing film.
  • the present invention has been made to solve the conventional problems described above, and its main purpose is to provide a polarizing film capable of reducing the power consumption of an organic EL display device.
  • a polyvinyl alcohol-based resin film subjecting a polyvinyl alcohol-based resin film to dyeing treatment and stretching treatment, and bringing an aqueous solvent into contact with the surface of the polyvinyl alcohol-based resin film, in this order, and having a wavelength of ⁇ nm
  • the ratio of the transmittance after contact to the transmittance of the polyvinyl alcohol resin film before contact with the aqueous solvent has a relationship of ⁇ Ts (415)> ⁇ Ts (470)> ⁇ Ts (550) is provided.
  • the temperature of the aqueous solvent is 20°C to 70°C.
  • the water content of the polyvinyl alcohol-based resin film with which the aqueous solvent is brought into contact is 15% by weight or less.
  • the polyvinyl alcohol-based resin film with which the aqueous solvent is brought into contact has a thickness of 12 ⁇ m or less.
  • subjecting the polyvinyl alcohol-based resin film to dyeing treatment and stretching treatment is a polyvinyl alcohol-based resin containing a halide and a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate.
  • the manufacturing method is a method for manufacturing a polarizing film having a haze of 1% or less.
  • a polyvinyl alcohol (PVA) resin film that has undergone dyeing treatment and stretching treatment is subjected to contact treatment with an aqueous solvent.
  • a polarizing film obtained by such a manufacturing method can more positively transmit light on the short wavelength side than light on the long wavelength side. Therefore, by using such a polarizing film, even when the amount of blue light emission, which consumes a large amount of power, is reduced, it is possible to suppress the decrease in luminance in the short wavelength region, and as a result, the organic EL display device can be It is possible to achieve both energy saving and high luminance.
  • FIG. 4 is a schematic diagram showing an example of drying shrinkage treatment using a heating roll.
  • A. Method for producing polarizing film comprises subjecting a polyvinyl alcohol (PVA) resin film to dyeing treatment and stretching treatment (step I), and contacting with an aqueous solvent (step II), in this order, the ratio of the transmittance after contact to the transmittance of the polyvinyl alcohol resin film before contact with the aqueous solvent at a wavelength of ⁇ nm ( ⁇ Ts ( ⁇ )) satisfies the relationship ⁇ Ts(415)> ⁇ Ts(470)> ⁇ Ts(550).
  • PVA polyvinyl alcohol
  • step II aqueous solvent
  • I ⁇ , I 2 , I 3 ⁇ , PVA-I 3 -complex , PVA-I 5 -complex , etc. I ⁇ , I 2 and I 3 - has absorption in the ultraviolet region (for example, wavelengths around 290 nm to 360 nm), and PVA-I 3 -complex and PVA-I 5 -complex have absorptions around wavelengths of 470 nm and 600 nm, respectively.
  • step I the PVA-based resin film is subjected to dyeing treatment and stretching treatment, whereby a PVA-based resin film exhibiting absorption dichroism at any wavelength of 380 nm to 780 nm (hereinafter referred to as "unbleached original film" (sometimes referred to as ).
  • the unbleached original film is typically in a state capable of functioning as a polarizing film.
  • the transmittance of the unbleached original film is preferably 41.0% or more, more preferably 42.0% or more, and still more preferably 42.5%. That's it.
  • the transmittance of the unbleached original film is preferably 46.0% or less, more preferably 45.0% or less.
  • the degree of polarization of the unbleached original film is preferably 98.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more.
  • the degree of polarization of the unbleached original film is preferably 99.998% or less.
  • the transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction.
  • the degree of polarization is typically obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction.
  • Degree of polarization (%) ⁇ (Tp-Tc)/(Tp+Tc) ⁇ 1/2 ⁇ 100
  • the transmittance of a thin polarizing film is typically the polarizing film (surface refractive index: 1.53) and the protective layer (protective film) ( A laminate with a refractive index of 1.50) is measured using an ultraviolet-visible spectrophotometer.
  • the reflectance at each layer interface may change, resulting in a change in the measured transmittance. .
  • the transmittance measurements may be corrected according to the refractive index of the surface of the protective layer that is in contact with the air interface.
  • the transmittance correction value C is expressed by the following formula using the reflectance R 1 (transmission axis reflectance) of polarized light parallel to the transmission axis at the interface between the protective layer and the air layer.
  • R 0 ((1.50 ⁇ 1) 2 /(1.50+1) 2 ) ⁇ (T 1 /100)
  • R 1 ((n 1 ⁇ 1) 2 /(n 1 +1) 2 ) ⁇ (T 1 /100)
  • R 0 is the transmission axis reflectance when a protective layer having a refractive index of 1.50 is used
  • n 1 is the refractive index of the protective layer used
  • T 1 is the transmittance of the polarizing film. is.
  • the correction amount C is approximately 0.2%.
  • the transmittance when using a polarizing film with a surface refractive index of 1.53 and a protective layer with a refractive index of 1.50 It is possible to convert to a rate.
  • the amount of change in the correction value C when the transmittance T1 of the polarizing film is changed by 2 % is 0.03% or less, and the transmittance of the polarizing film is equal to the correction value C has a limited effect on the value of
  • the protective layer has absorption other than surface reflection, appropriate correction can be performed according to the amount of absorption.
  • the transmittance (Ts 415 ) of the unbleached original film at a wavelength of 415 nm can be, for example, less than 40%.
  • the moisture content of the unbleached original film is typically 15% by weight or less, preferably 12% by weight or less, more preferably 10% by weight or less, and even more preferably 1% to 5% by weight. If the moisture content of the unbleached original film is within this range, it is possible to prevent dissolution, wrinkles, and the like from occurring during contact with the aqueous solvent in step II.
  • the thickness of the unbleached original film is typically 25 ⁇ m or less, preferably 12 ⁇ m or less, more preferably 1 ⁇ m to 12 ⁇ m, even more preferably 1 ⁇ m to 7 ⁇ m, still more preferably 2 ⁇ m to 5 ⁇ m.
  • step I the single-layer PVA-based resin film is subjected to dyeing treatment and stretching treatment, whereby an unbleached original film can be produced.
  • a laminate of two or more layers including a PVA-based resin layer may be subjected to dyeing treatment and stretching treatment to prepare an unbleached original film.
  • the unbleached base film prepared using a laminate of two or more layers avoids the occurrence of wrinkles and the like even after contact with an aqueous solvent, and has excellent optical properties (typically, single transmittance and degree of polarization) can be preferably maintained.
  • A-1-1 Production of an unbleached original film using a laminate of two or more layers
  • a PVA-based resin film containing a halide and a PVA-based resin is elongated. It can be carried out by dyeing and stretching in the state of a laminate with a thermoplastic resin substrate having a shape.
  • the unbleached original film is a laminate obtained by forming a PVA-based resin layer (PVA-based resin film) containing a halide and a PVA-based resin on one side of a long thermoplastic resin substrate.
  • the laminate is subjected to an auxiliary aerial stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment that shrinks by 2% or more in the width direction by heating while being conveyed in the longitudinal direction, in this order.
  • the content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
  • the drying shrinkage treatment is preferably performed using a heating roll, and the temperature of the heating roll is preferably 60°C to 120°C.
  • the shrinkage ratio in the width direction of the laminate due to drying shrinkage treatment is preferably 2% or more. According to such a production method, it is possible to obtain an unbleached raw film having a high degree of orientation of the PVA-based resin and excellent optical properties.
  • A-1-1-1 Production of Laminate Any appropriate method can be adopted as a method for producing a laminate of a thermoplastic resin substrate and a PVA-based resin layer.
  • a coating liquid containing a halide and a PVA-based resin is applied to the surface of the thermoplastic resin substrate and dried to form a PVA-based resin layer on the thermoplastic resin substrate.
  • the content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
  • any appropriate method can be adopted as the method of applying the coating liquid. Examples thereof include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.).
  • the coating/drying temperature of the coating liquid is preferably 50° C. or higher.
  • the thickness of the PVA-based resin layer is preferably 3 ⁇ m to 40 ⁇ m, more preferably 3 ⁇ m to 20 ⁇ m.
  • the thermoplastic resin substrate Before forming the PVA-based resin layer, the thermoplastic resin substrate may be surface-treated (for example, corona treatment, etc.), or an easy-adhesion layer may be formed on the thermoplastic resin substrate. By performing such treatment, the adhesion between the thermoplastic resin substrate and the PVA-based resin layer can be improved.
  • surface-treated for example, corona treatment, etc.
  • an easy-adhesion layer may be formed on the thermoplastic resin substrate.
  • the thickness of the thermoplastic resin substrate is preferably 20 ⁇ m to 300 ⁇ m, more preferably 50 ⁇ m to 200 ⁇ m. If the thickness is less than 20 ⁇ m, it may be difficult to form the PVA-based resin layer. If it exceeds 300 ⁇ m, for example, in the later-described underwater stretching treatment, it may take a long time for the thermoplastic resin substrate to absorb water, and an excessive load may be required for stretching.
  • the thermoplastic resin substrate preferably has a water absorption of 0.2% or more, more preferably 0.3% or more.
  • Thermoplastic resin substrates can absorb water and be plasticized with the water acting like a plasticizer. As a result, the stretching stress can be greatly reduced, and the film can be stretched at a high draw ratio.
  • the water absorption rate of the thermoplastic resin substrate is preferably 3.0% or less, more preferably 1.0% or less.
  • thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material.
  • the water absorption is a value determined according to JIS K 7209.
  • the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 120°C or less.
  • Tg The glass transition temperature of the thermoplastic resin substrate.
  • the temperature is preferably 100° C. or lower, more preferably 90° C. or lower.
  • the glass transition temperature of the thermoplastic resin substrate is preferably 60°C or higher.
  • the PVA-based resin layer can be satisfactorily stretched at a suitable temperature (for example, about 60°C).
  • the glass transition temperature of the thermoplastic resin substrate can be adjusted, for example, by heating using a crystallization material that introduces a modifying group into the constituent material.
  • the glass transition temperature (Tg) is a value determined according to JIS K 7121.
  • thermoplastic resin can be adopted as a constituent material of the thermoplastic resin base material.
  • thermoplastic resins include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. is mentioned. Among these, norbornene-based resins and amorphous polyethylene terephthalate-based resins are preferred.
  • an amorphous (not crystallized) polyethylene terephthalate resin is preferably used.
  • amorphous (difficult to crystallize) polyethylene terephthalate resin is particularly preferably used.
  • Specific examples of amorphous polyethylene terephthalate resins include copolymers further containing isophthalic acid and/or cyclohexanedicarboxylic acid as dicarboxylic acids, and copolymers further containing cyclohexanedimethanol or diethylene glycol as glycols.
  • the thermoplastic resin base material is composed of a polyethylene terephthalate resin having an isophthalic acid unit.
  • a thermoplastic resin substrate is extremely excellent in stretchability and can suppress crystallization during stretching. This is probably because the introduction of the isophthalic acid unit gives the main chain a large bend.
  • a polyethylene terephthalate-based resin has a terephthalic acid unit and an ethylene glycol unit.
  • the isophthalic acid unit content is preferably 0.1 mol % or more, more preferably 1.0 mol % or more, relative to the total of all repeating units. This is because a thermoplastic resin base material having extremely excellent stretchability can be obtained.
  • the isophthalic acid unit content is preferably 20 mol % or less, more preferably 10 mol % or less, relative to the total of all repeating units.
  • the degree of crystallinity can be favorably increased in the drying shrinkage treatment described later.
  • the thermoplastic resin substrate may be stretched in advance (before forming the PVA-based resin layer). In one embodiment, it is stretched in the transverse direction of the elongated thermoplastic resin substrate.
  • the lateral direction is preferably a direction perpendicular to the stretching direction of the laminate described below.
  • perpendicular also includes the case of being substantially perpendicular.
  • substantially orthogonal includes 90° ⁇ 5.0°, preferably 90° ⁇ 3.0°, more preferably 90° ⁇ 1.0°.
  • the stretching temperature of the thermoplastic resin substrate is preferably Tg-10°C to Tg+50°C with respect to the glass transition temperature (Tg).
  • the draw ratio of the thermoplastic resin substrate is preferably 1.5 to 3.0 times.
  • thermoplastic resin base material Any appropriate method can be adopted as a method for stretching the thermoplastic resin base material.
  • the drawing may be fixed end drawing or free end drawing.
  • the stretching method may be a dry method or a wet method.
  • the stretching of the thermoplastic resin substrate may be performed in one step or in multiple steps. When performing in multiple stages, the above-mentioned draw ratio is the product of the draw ratios in each step.
  • the coating liquid contains a halide and a PVA-based resin, as described above.
  • the coating liquid is typically a solution in which the halide and the PVA-based resin are dissolved in a solvent.
  • solvents include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Among these, water is preferred.
  • the concentration of the PVA-based resin in the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, it is possible to form a uniform coating film in close contact with the thermoplastic resin substrate.
  • the content of the halide in the coating liquid is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
  • Additives may be added to the coating liquid.
  • additives include plasticizers and surfactants.
  • plasticizers include polyhydric alcohols such as ethylene glycol and glycerin.
  • Surfactants include, for example, nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the obtained PVA-based resin layer.
  • any appropriate resin can be adopted as the PVA-based resin.
  • Examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymers.
  • Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
  • An ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer.
  • the degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. .
  • the degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a degree of saponification, an unbleached original film having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.
  • the average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose.
  • the average degree of polymerization is usually 1,000 to 10,000, preferably 1,200 to 4,500, more preferably 1,500 to 4,300.
  • the average degree of polymerization can be determined according to JIS K 6726-1994.
  • halide any appropriate halide can be adopted as the halide.
  • examples include iodide and sodium chloride.
  • Iodides include, for example, potassium iodide, sodium iodide, and lithium iodide. Among these, potassium iodide is preferred.
  • the amount of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA resin, and more preferably 10 parts by weight to 15 parts by weight with respect to 100 parts by weight of the PVA resin. Department. If the amount of the halide exceeds 20 parts by weight with respect to 100 parts by weight of the PVA-based resin, the halide may bleed out and the finally obtained unbleached original film may become cloudy.
  • the orientation of the polyvinyl alcohol molecules in the PVA-based resin layer increases. orientation may be disturbed and the orientation may be lowered.
  • the laminate is stretched in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin substrate.
  • the film is stretched, the tendency of the degree of orientation to decrease is remarkable.
  • the stretching of a single PVA film in boric acid water is generally carried out at 60° C.
  • the stretching of a laminate of A-PET (thermoplastic resin substrate) and a PVA-based resin layer is It is carried out at a high temperature of about 70° C., and in this case, the orientation of PVA at the initial stage of stretching may be lowered before it is increased by stretching in water.
  • the crystallization of the PVA-based resin in the PVA-based resin layer of the laminate after auxiliary stretching can be promoted.
  • the PVA-based resin layer is immersed in a liquid, the disturbance of the orientation of the polyvinyl alcohol molecules and the deterioration of the orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide.
  • This makes it possible to improve the optical properties of the unbleached base film obtained through a treatment step in which the laminate is immersed in a liquid, such as dyeing treatment and stretching treatment in water.
  • A-1-1-2 Aerial Auxiliary Stretching
  • a two-stage stretching method combining dry stretching (auxiliary stretching) and stretching in boric acid solution is selected.
  • auxiliary stretching such as two-step stretching, it is possible to stretch while suppressing crystallization of the thermoplastic resin substrate, and excessive crystallization of the thermoplastic resin substrate in the subsequent stretching in boric acid water. It is possible to solve the problem that stretchability is reduced by stretching, and stretch the laminate at a higher magnification.
  • the stretching method of the in-air auxiliary stretching may be fixed edge stretching (e.g., a method of stretching using a tenter stretching machine) or free edge stretching (e.g., a method of uniaxially stretching the laminate through rolls having different peripheral speeds).
  • free-end drawing may be positively employed in order to obtain high optical properties.
  • the in-air stretching process includes a heating roll stretching step in which the laminate is stretched by a peripheral speed difference between heating rolls while being conveyed in the longitudinal direction.
  • the air drawing process typically includes a zone drawing process and a hot roll drawing process.
  • the order of the zone stretching process and the heating roll stretching process is not limited, and the zone stretching process may be carried out first, or the heating roll stretching process may be carried out first.
  • the zone drawing step may be omitted. In one embodiment, the zone drawing step and the heated roll drawing step are performed in this order.
  • the laminate is stretched by gripping the ends of the laminate and widening the distance between the tenters in the machine direction in a tenter stretching machine (the widening of the distance between the tenters is the stretching ratio). At this time, the distance between the tenters in the width direction (perpendicular to the machine direction) is set to be arbitrarily close.
  • the draw ratio in the machine direction can be set to be closer to the free end draw.
  • the shrinkage ratio in the width direction is calculated by (1/stretching ratio) 1/2 .
  • Aerial auxiliary stretching may be performed in one step or in multiple steps. When it is carried out in multiple stages, the draw ratio is the product of the draw ratios in each step.
  • the stretching direction in the in-air auxiliary stretching is preferably substantially the same as the stretching direction in the underwater stretching.
  • the draw ratio in the in-air auxiliary drawing is preferably 2.0 to 3.5 times.
  • the maximum draw ratio when the auxiliary drawing in the air and the drawing in water are combined is preferably 5.0 times or more, more preferably 5.5 times or more, and still more preferably 6.0 times the original length of the laminate. That's it.
  • the term "maximum draw ratio" refers to the draw ratio immediately before the laminate breaks, and is 0.2 lower than the draw ratio at which the laminate breaks.
  • the stretching temperature for the in-air auxiliary stretching can be set to any appropriate value depending on the material for forming the thermoplastic resin base material, the stretching method, and the like.
  • the stretching temperature is preferably the glass transition temperature (Tg) of the thermoplastic resin substrate or higher, more preferably the glass transition temperature (Tg) of the thermoplastic resin substrate + 10°C or higher, and particularly preferably Tg + 15°C or higher.
  • the upper limit of the stretching temperature is preferably 170°C.
  • the crystallization index of the PVA-based resin after auxiliary stretching in air is preferably 1.3 to 1.8, more preferably 1.4 to 1.7.
  • an insolubilization treatment is performed after the auxiliary stretching treatment in the air and before the stretching treatment in water or the dyeing treatment.
  • the insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution.
  • the insolubilization treatment imparts water resistance to the PVA-based resin layer, and prevents deterioration of the orientation of the PVA when immersed in water.
  • the concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water.
  • the liquid temperature of the insolubilizing bath is preferably 20°C to 50°C.
  • the dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic substance (typically iodine). Specifically, it is carried out by allowing the PVA-based resin layer to adsorb iodine.
  • adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of coating the PVA-based resin layer with the dyeing solution, and a method of applying the dyeing solution to the PVA-based resin layer.
  • a spraying method and the like can be mentioned.
  • a preferred method is to immerse the laminate in a dyeing solution (dyeing bath). This is because iodine can be well adsorbed.
  • the staining solution is preferably an iodine aqueous solution.
  • the amount of iodine compounded is preferably 0.05 to 0.5 parts by weight per 100 parts by weight of water.
  • an iodide to the iodine aqueous solution.
  • iodides include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. etc.
  • potassium iodide is preferred.
  • the amount of iodide compounded is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, per 100 parts by weight of water.
  • the liquid temperature of the dyeing liquid during dyeing is preferably 20° C. to 50° C. in order to suppress the dissolution of the PVA-based resin.
  • the immersion time is preferably 5 seconds to 5 minutes, more preferably 30 seconds to 90 seconds, in order to ensure the transmittance of the PVA-based resin layer.
  • the dyeing conditions can be set so that the single transmittance of the finally obtained unbleached raw film has a desired value.
  • the content ratio of iodine and potassium iodide in the aqueous iodine solution is preferably 1:5 to 1:10.
  • the boric acid contained in the treatment bath is mixed into the dyeing bath.
  • the boric acid concentration in the dyeing bath may change over time, resulting in unstable dyeability.
  • the upper limit of the boric acid concentration in the dyeing bath is preferably 4 parts by weight, more preferably 2 parts by weight with respect to 100 parts by weight of water. adjusted.
  • the lower limit of the boric acid concentration in the dyeing bath is preferably 0.1 parts by weight, more preferably 0.2 parts by weight, and still more preferably 0.5 parts by weight with respect to 100 parts by weight of water. is.
  • the dyeing process is performed using a dyeing bath pre-blended with boric acid. This can reduce the rate of change in boric acid concentration when the boric acid in the treatment bath is mixed into the dyeing bath.
  • the amount of boric acid blended in advance in the dyeing bath (that is, the content of boric acid not derived from the treatment bath) is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of water. , more preferably 0.5 to 1.5 parts by weight.
  • A-1-1-5 A-1-1-5.
  • Crosslinking Treatment If necessary, a crosslinking treatment is applied after the dyeing treatment and before the underwater stretching treatment.
  • the cross-linking treatment is typically performed by immersing the PVA-based resin layer in an aqueous solution of boric acid.
  • the cross-linking treatment imparts water resistance to the PVA-based resin layer, and prevents deterioration of the orientation of the PVA when immersed in high-temperature water in the subsequent underwater stretching.
  • the concentration of the boric acid aqueous solution is preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.
  • the amount of iodide compounded is preferably 1 to 5 parts by weight per 100 parts by weight of water. Specific examples of iodides are as described above.
  • the liquid temperature of the cross-linking bath is preferably 20°C to 50°C.
  • thermoplastic resin substrate and the PVA-based resin layer can be stretched at a temperature lower than the glass transition temperature (typically, about 80° C.), and the PVA-based resin layer undergoes its crystallization. It can be stretched at a high magnification while suppressing the As a result, an unbleached original film having excellent optical properties can be produced.
  • any appropriate method can be adopted as the method for stretching the laminate. Specifically, fixed-end stretching or free-end stretching (for example, a method of uniaxially stretching a laminate by passing it between rolls having different peripheral speeds) may be used. Free-end drawing is preferably chosen.
  • the laminate may be stretched in one step or in multiple steps. When the stretching is performed in multiple stages, the draw ratio (maximum draw ratio) of the laminate described below is the product of the draw ratios in each step.
  • the stretching in water is preferably carried out by immersing the laminate in an aqueous boric acid solution (stretching in boric acid water).
  • an aqueous boric acid solution as the stretching bath, the PVA-based resin layer can be imparted with rigidity to withstand tension applied during stretching and water resistance that does not dissolve in water.
  • boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with a PVA-based resin through hydrogen bonding.
  • rigidity and water resistance can be imparted to the PVA-based resin layer, which can be satisfactorily stretched, and an unbleached base film having excellent optical properties can be produced.
  • the boric acid aqueous solution is preferably obtained by dissolving boric acid and/or a borate salt in water as a solvent.
  • the boric acid concentration is preferably 1 part by weight to 10 parts by weight, more preferably 2.5 parts by weight to 6 parts by weight, and particularly preferably 3 parts by weight to 5 parts by weight with respect to 100 parts by weight of water. is.
  • an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.
  • an iodide is added to the stretching bath (boric acid aqueous solution).
  • iodide elution of iodine adsorbed on the PVA-based resin layer can be suppressed.
  • Specific examples of iodides are as described above.
  • the concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight of water.
  • the stretching temperature (liquid temperature of the stretching bath) is preferably 40°C to 85°C, more preferably 60°C to 75°C. At such a temperature, the film can be stretched at a high magnification while suppressing dissolution of the PVA-based resin layer.
  • the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60° C. or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is lower than 40° C., it may not be possible to stretch well even if the plasticization of the thermoplastic resin base material by water is considered.
  • the higher the temperature of the stretching bath the higher the solubility of the PVA-based resin layer, which may make it impossible to obtain excellent optical properties.
  • the immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.
  • the draw ratio by underwater drawing is preferably 1.5 times or more, more preferably 3.0 times or more.
  • the total draw ratio of the laminate is preferably 5.0 times or more, more preferably 5.5 times or more, relative to the original length of the laminate.
  • A-1-1-7 Drying Shrinkage Treatment
  • a laminate of a long thermoplastic resin base material and a PVA-based resin film is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction.
  • the moisture content is preferably 12% by weight or less, and further preferably. It is preferred to dry to 10% by weight or less, even more preferably 1% to 5% by weight.
  • the drying shrinkage treatment may be performed by zone heating performed by heating the entire zone, or by heating the transport roll (using a so-called heating roll) (heating roll drying method). Preferably both are used.
  • heating roll heating roll drying method
  • the crystallization of the thermoplastic resin substrate can be efficiently promoted to increase the degree of crystallinity, which is relatively low. Even at the drying temperature, the degree of crystallinity of the thermoplastic resin substrate can be favorably increased.
  • the thermoplastic resin base material has increased rigidity and is in a state capable of withstanding shrinkage of the PVA-based resin layer due to drying, thereby suppressing curling.
  • the layered product can be dried while being maintained in a flat state, so that not only curling but also wrinkling can be suppressed.
  • the laminate can be shrunk in the width direction by drying shrinkage treatment, thereby improving the optical properties. This is because the orientation of PVA and PVA/iodine complex can be effectively enhanced.
  • the shrinkage ratio of the laminate in the width direction due to drying shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%.
  • FIG. 1 is a schematic diagram showing an example of drying shrinkage treatment.
  • the laminate 200 is dried while being transported by transport rolls R1 to R6 heated to a predetermined temperature and guide rolls G1 to G4.
  • the transport rolls R1 to R6 are arranged so as to alternately and continuously heat the surface of the PVA-based resin layer and the surface of the thermoplastic resin substrate.
  • the transport rolls R1 to R6 may be arranged so as to continuously heat only the plastic resin substrate surface).
  • the drying conditions can be controlled by adjusting the heating temperature of the transport rolls (the temperature of the heating rolls), the number of heating rolls, the contact time with the heating rolls, and so on.
  • the temperature of the heating roll is preferably 60°C to 120°C, more preferably 65°C to 100°C, and particularly preferably 70°C to 80°C.
  • the degree of crystallinity of the thermoplastic resin can be favorably increased, curling can be favorably suppressed, and an optical laminate having extremely excellent durability can be produced.
  • the temperature of the heating roll can be measured with a contact thermometer. In the illustrated example, six transport rolls are provided, but there is no particular limitation as long as the number of transport rolls is plural. Conveying rolls are usually 2 to 40, preferably 4 to 30 in number.
  • the contact time (total contact time) between the laminate and the heating roll is preferably 1 to 300 seconds, more preferably 1 to 20 seconds, still more preferably 1 to 10 seconds.
  • the heating roll may be provided in a heating furnace (for example, an oven), or may be provided in a normal production line (under room temperature environment). Preferably, it is provided in a heating furnace equipped with air blowing means.
  • a heating furnace equipped with air blowing means.
  • the temperature for hot air drying is preferably 20°C to 100°C.
  • the hot air drying time is preferably 1 second to 300 seconds.
  • the wind speed of the hot air is preferably about 10m/s to 30m/s. The wind speed is the wind speed in the heating furnace and can be measured with a mini-vane digital anemometer.
  • A-1-1-8 Other Treatments
  • a washing treatment is performed after the underwater stretching treatment and before the drying shrinkage treatment.
  • the cleaning treatment is typically performed by immersing the PVA-based resin layer in an aqueous solution of potassium iodide.
  • the contact between the unbleached original film and the aqueous solvent in step II may be performed by contacting only one side of the unbleached original film with the aqueous solvent, or by contacting both sides with the aqueous solvent. . Therefore, in one embodiment, the unbleached original film produced using the laminate can be subjected to step II as it is as the laminate of [unbleached original film/thermoplastic resin substrate]. In another embodiment, a protective layer is attached to the surface of the unbleached original film of the laminate of [unbleached original film/thermoplastic resin substrate] to form [protective layer/unbleached original film/thermoplastic resin substrate].
  • any suitable function is provided on the substrate side of the laminate of [unbleached base film/thermoplastic resin substrate] or on the protective layer side of the laminate of [protective layer/unbleached base film].
  • a layer provided with a layer can also be subjected to step II.
  • a long PVA-based resin film is dyed and stretched (typically, uniaxially stretched using a roll stretcher in an aqueous boric acid solution), and then the moisture content is preferably 15% by weight or less, more preferably is 12% by weight or less, more preferably 10% by weight or less, and even more preferably 1% to 5% by weight.
  • the dyeing is performed by, for example, immersing the PVA-based resin film in an iodine aqueous solution.
  • the draw ratio of the uniaxial drawing is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or may be performed while dyeing.
  • the PVA-based resin film is subjected to swelling treatment, cross-linking treatment, washing treatment, and the like. For example, by immersing the PVA-based resin film in water and washing it with water before dyeing, it is possible not only to wash away stains and anti-blocking agents on the surface of the PVA-based resin film, but also to swell the PVA-based resin film for dyeing. Unevenness and the like can be prevented.
  • the contact between the unbleached original film and the aqueous solvent in step II may be performed by contacting only one surface of the unbleached original film with the aqueous solvent, or by contacting both surfaces with the aqueous solvent. may be broken. Therefore, in one embodiment, the unbleached original film produced using the single-layer PVA-based resin film can be subjected to step II as it is.
  • a protective layer is attached to one side of the unbleached original film to prepare a laminate of [protective layer/unbleached original film], and the laminate can be subjected to step II.
  • the laminate of [protective layer/unbleached original film] provided with any suitable functional layer (retardation layer, adhesive layer, etc.) on the protective layer side is subjected to step II. can also
  • step II the surface of the PVA-based resin film (unbleached original film) that has undergone step I is brought into contact with an aqueous solvent. Upon contact with an aqueous solvent, polyiodine ions forming I ⁇ , I 2 , I 3 - and PVA-I 3 -complexes preferentially over polyiodine ions forming PVA-I 5 -complexes to the unbleached original.
  • the transmittance increase rate ( ⁇ Ts( ⁇ )) at the wavelength ⁇ nm satisfies the relationship ⁇ Ts (415) > ⁇ Ts (470) > ⁇ Ts (550) can satisfy
  • the aqueous solvent can be, for example, water or a mixture of water and a water-soluble organic solvent.
  • Preferred examples of the water-soluble organic solvent include lower monoalcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol, and polyhydric alcohols such as glycerin and ethylene glycol.
  • the method of contact with the aqueous solvent is not particularly limited, and any suitable method such as immersion, spraying, coating, etc. can be used. Immersion is preferred from the viewpoint of bringing the entire surface of the unbleached original film into contact with the aqueous solvent uniformly.
  • the contact time with the aqueous solvent and the temperature of the aqueous solvent during contact can be appropriately set according to desired Ts 415 , Ts 470 and Ts 550 and the like. Increasing the contact time or increasing the temperature of the aqueous solvent tends to increase the transmittance (particularly Ts 415 ).
  • the contact time can be, for example, 10 minutes or less, preferably 60 seconds to 9 minutes, more preferably 60 seconds to 4 minutes.
  • the temperature of the aqueous solvent can be preferably 20°C to 70°C, more preferably 30°C to 65°C, even more preferably 40°C to 60°C.
  • drying treatment may be performed after contact with the aqueous solvent.
  • the drying temperature can be, for example, 20°C to 100°C, preferably 30°C to 80°C.
  • the moisture content of the dried polarizing film is typically 15% by weight or less, preferably 12% by weight or less, more preferably 10% by weight or less, and still more preferably 1% to 5% by weight. is.
  • the polarizing film obtained by the method for producing a polarizing film described in Section A is composed of a PVA-based resin film containing a dichroic substance (typically iodine), and has a wavelength range of at least 415 nm to 550 nm. It has a higher transmittance than the original bleaching film.
  • the transmittance increase rate ( ⁇ Ts( ⁇ )) at the wavelength ⁇ nm satisfies the relationship ⁇ Ts(415)> ⁇ Ts(470)> ⁇ Ts(550).
  • the transmittance increase rate ( ⁇ Ts(415)) at a wavelength of 415 nm exceeds, for example, 1.05, preferably 1.1 or more, and more preferably 1.10 to 2.2. If ⁇ Ts(415) is within this range, it is possible to reduce the amount of blue light emission that consumes a large amount of power, thereby contributing to energy saving of the organic EL display device.
  • Ts 415 and Ts 550 of the polarizing film can be any suitable value depending on the purpose.
  • Ts 415 can be, for example, 40% or more, preferably 41% or more, more preferably 42% or more, and can be, for example, 80% or less, preferably 60% or less, more preferably 50% or less.
  • Ts 550 may be, for example, 40% or more, preferably 42% or more, more preferably 43% or more, and may be, for example, 70% or less, preferably 60% or less, more preferably 50% or less.
  • the polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm.
  • the transmittance of the polarizing film (single transmittance: Ts) is preferably 41% or more, more preferably 42% or more, and still more preferably 42.5% or more.
  • the transmittance of the polarizing film is, for example, 65% or less, preferably 50% or less, more preferably 48% or less.
  • the polarization degree of the polarizing film is, for example, 40.0% or more, preferably 90.0% or more, more preferably 94.0% or more, still more preferably 96.0% or more, and still more It is preferably 99.0% or more, still more preferably 99.5% or more, and preferably 99.998% or less.
  • the above transmittance and degree of polarization are obtained in the same manner as the transmittance and degree of polarization of the unbleached original film.
  • the haze of the polarizing film is preferably 1% or less, more preferably 0.8% or less, and even more preferably 0.6% or less. If the haze is within this range, an organic EL display device with a high contrast ratio can be obtained.
  • the iodine concentration in the polarizing film is preferably 3% by weight or more, more preferably 4% to 10% by weight, and more preferably 4% to 8% by weight.
  • "iodine concentration” means the total amount of iodine contained in the polarizing film. More specifically, iodine exists in the form of I ⁇ , I 2 , I 3 ⁇ , PVA-I 3 -complex , PVA-I 5 -complex , etc. in the polarizing film. , means the concentration of iodine including all these forms.
  • the iodine concentration can be calculated, for example, from the fluorescent X-ray intensity and film (polarizing film) thickness obtained by fluorescent X-ray analysis.
  • the thickness of the polarizing film is typically 25 ⁇ m or less, preferably 12 ⁇ m or less, more preferably 1 ⁇ m to 12 ⁇ m, even more preferably 1 ⁇ m to 7 ⁇ m, still more preferably 2 ⁇ m to 5 ⁇ m.
  • Ts, Tp, and Tc of the PVA-based resin film were defined as Ts, Tp, and Tc of the PVA-based resin film, respectively.
  • Ts, Tp and Tc are Y values measured with a 2-degree field of view (C light source) according to JIS Z8701 and subjected to visibility correction.
  • the refractive index of the protective layer was 1.53, and the refractive index of the surface of the polarizing film opposite to the protective layer was 1.53. From the obtained Tp and Tc, the degree of polarization P was determined by the following formula.
  • Degree of polarization P (%) ⁇ (Tp-Tc)/(Tp+Tc) ⁇ 1/2 ⁇ 100
  • the measured Ts at wavelengths of 415 nm, 470 nm and 550 nm were defined as Ts 415 , Ts 470 and Ts 550 , respectively.
  • Equivalent measurement can be performed with a spectrophotometer such as "V-7100" manufactured by JASCO Corporation, and equivalent measurement results can be obtained using any spectrophotometer. has been confirmed.
  • (3) Moisture content The unbleached raw film immediately after drying (when the laminate is stretched, the stretched substrate is peeled off) is cut into a size of 100 mm ⁇ 100 mm or more, and the weight before processing is measured with an electronic balance. .
  • Moisture content [%] (weight before treatment - weight after treatment) / weight before treatment x 100 (4) Haze Measured according to JISK7136 using a product name "Haze meter (NDH-5000" manufactured by Nippon Denshoku Industries Co., Ltd.).
  • Example 1-1 Preparation of polarizing film and polarizing plate A long roll of PVA-based resin film (manufactured by Kuraray, product name "PE3000") having a thickness of 30 ⁇ m was stretched 2.2 times in the transport direction while being immersed in a water bath at 30°C. While immersed in an aqueous solution of 0.04% by weight of iodine and 0.3% by weight of potassium at 30° C. for dyeing, the film was stretched 3 times with respect to the unstretched film (original length).
  • PVA-based resin film manufactured by Kuraray, product name "PE3000”
  • a PVA-based resin aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “GOSEFIMER (registered trademark) Z-200”, resin concentration: 3% by weight) was applied to one side of the obtained unbleached raw film a1.
  • An olefin film (Zeonor, manufactured by Nippon Zeon Co., Ltd., thickness: 25 ⁇ m) was laminated to obtain an optical laminate having a structure of [unbleached original film a1/protective layer].
  • a protective layer provided with a hard coat layer may be used.
  • a protective layer for example, a cycloolefin film with a hard coat layer (manufactured by ZEON, product name "G-Film , total thickness of 27 ⁇ m (film thickness of 25 ⁇ m+hard coat layer thickness of 2 ⁇ m), and the like.
  • the above optical layered body was cut into a size of 45 mm ⁇ 50 mm and attached to a glass plate via an acrylic pressure-sensitive adhesive layer (thickness 15 ⁇ m) so that the unbleached base film side surface was exposed. was immersed in for 31 hours. Then, by drying at 50° C. for 5 minutes, a polarizing plate having a structure of [polarizing film A1/protective layer] was obtained.
  • Example 1-2 A polarizing plate having a structure of [polarizing film A2/protective layer] was obtained in the same manner as in Example 1-1, except that instead of immersing in water at 23° C. for 31 hours, it was immersed in water at 55° C. for 9 minutes. rice field.
  • Example 1-3 A polarizing plate having a structure of [polarizing film A3/protective layer] was obtained in the same manner as in Example 1-1, except that instead of immersing in water at 23° C. for 31 hours, it was immersed in water at 60° C. for 4 minutes. rice field.
  • Example 1-4 A polarizing plate having a structure of [polarizing film A4/protective layer] was obtained in the same manner as in Example 1-1, except that instead of immersing in water at 23° C. for 31 hours, it was immersed in water at 65° C. for 3 minutes. rice field.
  • Example 2-1 A long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 ⁇ m) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to corona treatment.
  • Polyvinyl alcohol degree of polymerization: 4,200, degree of saponification: 99.2 mol%
  • acetoacetyl-modified PVA manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER" were mixed at a ratio of 9:1, and 100 parts by weight of PVA-based resin.
  • aqueous PVA solution (coating solution).
  • the above PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 ⁇ m, thereby producing a laminate.
  • the resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
  • the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C.
  • crosslinking treatment After that, while immersing the laminate in an aqueous solution of boric acid (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70° C., the laminate was moved vertically (longitudinally) between rolls with different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment). After that, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).
  • a washing bath aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water
  • the above optical layered body was cut into a size of 45 mm ⁇ 50 mm, and attached to a glass plate so that the unbleached original film side surface became an exposed surface via an acrylic pressure-sensitive adhesive layer (thickness 15 ⁇ m). for 9 minutes. Then, by drying at 50° C. for 5 minutes, a polarizing plate having a structure of [polarizing film B1/protective layer] was obtained.
  • Example 2-2 A polarizing plate having a structure of [polarizing film B2/protective layer] was obtained in the same manner as in Example 2-1, except that instead of immersing in water at 50°C for 9 minutes, it was immersed in water at 55°C for 3 minutes. rice field.
  • Example 2-3 A polarizing plate having a structure of [polarizing film B3/protective layer] was obtained in the same manner as in Example 2-1, except that instead of immersing in water at 50°C for 9 minutes, it was immersed in water at 60°C for 2 minutes. rice field.
  • Example 2-4 A polarizing plate having a structure of [polarizing film B4/protective layer] was obtained in the same manner as in Example 2-1, except that instead of immersing in water at 50°C for 9 minutes, it was immersed in water at 60°C for 3 minutes. rice field.
  • the transmittance increase rate ( ⁇ Ts ( ⁇ )) of the PVA-based resin film at the wavelength ⁇ nm is ⁇ Ts (415) > ⁇ Ts (470 )> ⁇ Ts(550), and the rate of increase in transmittance at a wavelength of 415 nm is large.
  • the polarizing film obtained by such a manufacturing method has practically acceptable optical properties (typically, single transmittance and degree of polarization) and has an increased transmittance for short-wavelength light.
  • the polarizing film of the present invention can be suitably used in image display devices such as liquid crystal display devices and EL display devices, particularly organic EL display devices.

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Abstract

L'invention fournit un procédé de fabrication de film polarisant qui inclut dans l'ordre : une étape au cours de laquelle un film de résine à base d'alcool polyvinylique est soumis à un traitement de coloration et à un traitement d'étirage ; et une étape au cours de laquelle un solvant aqueux est mis en contact avec la surface de ce film de résine à base d'alcool polyvinylique. La proportion （ΔＴｓ（λ）） de la transmittance du film de résine à base d'alcool polyvinylique après contact avec le solvant aqueux vis-à-vis de sa transmittance avant contact à λｎｍ de longueur d'onde, satisfait la relation ΔＴｓ（４１５）＞ΔＴｓ（４７０）＞ΔＴｓ（５５０）.
PCT/JP2021/047761 2021-01-22 2021-12-23 Procédé de fabrication de film polarisant WO2022158235A1 (fr)

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Publication number Priority date Publication date Assignee Title
WO2017130585A1 (fr) * 2016-01-28 2017-08-03 コニカミノルタ株式会社 Plaque polarisante, procédé de production de plaque polarisante, et dispositif d'affichage à cristaux liquides
JP2020073997A (ja) * 2014-06-25 2020-05-14 住友化学株式会社 光吸収異方性膜、３次元光吸収異方性膜及びその製造方法
JP2021004946A (ja) * 2019-06-25 2021-01-14 日東電工株式会社 偏光板の製造方法

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JP2002311239A (ja) 2001-04-16 2002-10-23 Nitto Denko Corp １／４波長板、円偏光板及び表示装置
JP2002372622A (ja) 2001-06-14 2002-12-26 Nitto Denko Corp 複合位相差板、円偏光板及び液晶表示装置、有機ｅｌ表示装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020073997A (ja) * 2014-06-25 2020-05-14 住友化学株式会社 光吸収異方性膜、３次元光吸収異方性膜及びその製造方法
WO2017130585A1 (fr) * 2016-01-28 2017-08-03 コニカミノルタ株式会社 Plaque polarisante, procédé de production de plaque polarisante, et dispositif d'affichage à cristaux liquides
JP2021004946A (ja) * 2019-06-25 2021-01-14 日東電工株式会社 偏光板の製造方法

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