WO2023218820A1 - Procédé de fabrication de film polarisant - Google Patents

Procédé de fabrication de film polarisant Download PDF

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Publication number
WO2023218820A1
WO2023218820A1 PCT/JP2023/014364 JP2023014364W WO2023218820A1 WO 2023218820 A1 WO2023218820 A1 WO 2023218820A1 JP 2023014364 W JP2023014364 W JP 2023014364W WO 2023218820 A1 WO2023218820 A1 WO 2023218820A1
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Prior art keywords
film
stretching
liquid
resin
transmittance
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PCT/JP2023/014364
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English (en)
Japanese (ja)
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理 小島
周作 後藤
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日東電工株式会社
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Publication of WO2023218820A1 publication Critical patent/WO2023218820A1/fr

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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
    • 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
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/02—Details
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
    • 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
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • 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

Definitions

  • the present invention relates to a method for manufacturing a polarizing film.
  • polarizing films are arranged on both sides of a liquid crystal cell due to its image forming method.
  • displays equipped with organic electroluminescence (EL) panels (OLED) and displays using display panels using inorganic light-emitting materials such as quantum dots (QLED) have been proposed.
  • EL organic electroluminescence
  • QLED quantum dots
  • These panels have highly reflective metal layers and are prone to problems such as reflection of external light and background reflection. Therefore, it is known that these problems can be prevented by providing a circularly polarizing plate having a polarizing film and a ⁇ /4 plate on the viewing side (for example, Patent Document 1 and Patent Document 2).
  • the appearance of the polarizing film may affect the display characteristics of the image display device. For example, if streaks occur on a polarizing film, the streaks may be visible on an image display device.
  • the present invention has been made to solve the above problems, and its main purpose is to provide a polarizing film that has an excellent appearance and can contribute to improving the display characteristics of an image display device.
  • a method for manufacturing a polarizing film according to an embodiment of the present invention includes contacting a resin film containing iodine and having a first transmittance (T1) with a first liquid, and changing the transmittance of the resin film to a second transmittance (T2). ), and a second step of bringing the resin film into contact with a second liquid to lower the transmittance of the resin film to a third transmittance (T3), in this order.
  • the first transmittance (T1) may be 44% or more.
  • the resin film may contain a polyvinyl alcohol resin, and may be brought into contact with the first liquid to reduce the orientation of the resin film. 4.
  • the temperature of the first liquid may be 60°C or higher. 5.
  • the first liquid may be an aqueous boric acid solution. 6.
  • the moisture content of the resin film before being brought into contact with the first liquid may be 15% by weight or less.
  • the second liquid may contain water. 8.
  • a polarizing film having a thickness of 22 ⁇ m or less may be obtained.
  • a polarizing film with excellent appearance can be obtained.
  • 1 is a schematic cross-sectional view showing a schematic configuration of a laminate according to an embodiment of the present invention. It is a schematic diagram showing an example of drying using a heating roll. 1 is a schematic cross-sectional view showing a general configuration of a polarizing plate according to one embodiment of the present invention.
  • Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny” is the direction perpendicular to the slow axis in the plane (i.e., fast axis direction) "nz” is the refractive index in the thickness direction.
  • Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny” is the direction perpendicular to the slow axis in the plane (i.e., fast axis direction) "nz” is the refractive index in the thickness direction.
  • In-plane phase difference (Re) "Re( ⁇ )” is an in-plane retardation measured with light having a wavelength of ⁇ nm at 23°C.
  • Re(550) is an in-plane retardation measured with light having a wavelength of 550 nm at 23°C.
  • Phase difference in thickness direction (Rth) is a retardation in the thickness direction measured with light having a wavelength of ⁇ nm at 23°C.
  • Rth (550) is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C.
  • a method for manufacturing a polarizing film according to an embodiment of the present invention includes contacting a resin film containing iodine and having a first transmittance (T1) with a first liquid, and converting the transmittance into a second transmittance (T2).
  • the resin film may further include a second step of bringing the resin membrane into contact with a second liquid to lower its transmittance to a third transmittance (T3).
  • the above resin film is, for example, a laminate or a resin film (typically a polyvinyl alcohol resin layer) obtained by forming a resin layer (typically a polyvinyl alcohol resin layer) on a resin base material. (type resin film) is stretched and dyed with a dichroic substance (typically, iodine), and then dried.
  • a resin film typically a polyvinyl alcohol resin layer
  • a dichroic substance typically, iodine
  • FIG. 1 is a schematic cross-sectional view showing the general configuration of a laminated body according to one embodiment of the present invention.
  • the laminate 1 includes a thermoplastic resin base material (e.g., elongated) 2 and a polyvinyl alcohol (PVA) resin layer 3.
  • the laminate 1 is produced by forming a PVA-based resin layer 3 containing a PVA-based resin and a halide on a thermoplastic resin base material 2 .
  • the PVA resin layer 3 is formed by applying a coating liquid containing a PVA resin and a halide onto the thermoplastic resin base material 2 and drying it.
  • the thickness of the thermoplastic resin base material is preferably 20 ⁇ m to 300 ⁇ m, more preferably 50 ⁇ m to 200 ⁇ m. If it is less than 20 ⁇ m, it may be difficult to form a PVA-based resin layer. If it exceeds 300 ⁇ m, for example, in underwater stretching described below, it may take time for the thermoplastic resin base material to absorb water, and an excessive load may be required for stretching.
  • the water absorption rate of the thermoplastic resin base material is preferably 0.2% or more, more preferably 0.3% or more.
  • a thermoplastic resin base material absorbs water and can be plasticized by the water acting as a plasticizer. As a result, the stretching stress can be significantly reduced and the film can be stretched to a high magnification.
  • the water absorption rate of the thermoplastic resin base material is preferably 3.0% or less, more preferably 1.0% or less. According to such a water absorption rate, it is possible to prevent problems such as a significant decrease in the dimensional stability of the thermoplastic resin base material during production and deterioration in the quality of the polarizing film obtained.
  • thermoplastic resin base material Furthermore, it is possible to prevent the thermoplastic resin base material from breaking or the PVA resin layer from peeling off during underwater stretching.
  • the water absorption rate of the thermoplastic resin base material can be adjusted, for example, by introducing a modifying group into the constituent material. Note that the water absorption rate is a value determined according to JIS K 7209.
  • the glass transition temperature (Tg) of the thermoplastic resin base material is preferably 120°C or lower.
  • Tg is more preferably 100°C or less, and even more preferably 90°C or less.
  • the Tg of the thermoplastic resin base material is preferably 60°C or higher.
  • thermoplastic resin base material e.g., occurrence of unevenness, sagging, wrinkles, etc.
  • body can be created.
  • the resin layer can be stretched well at a suitable temperature (for example, about 60° C.).
  • the Tg of the thermoplastic resin base material can be adjusted, for example, by introducing a modifying group into the constituent material and heating it using a crystallizing material.
  • the glass transition temperature (Tg) is a value determined according to JIS K 7121.
  • thermoplastic resin may be employed as the 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. Can be mentioned. Among these, norbornene resins and amorphous polyethylene terephthalate resins are preferred.
  • amorphous (uncrystallized) polyethylene terephthalate resin is preferably used.
  • amorphous (hard to crystallize) polyethylene terephthalate resin is particularly preferably used.
  • Specific examples of the amorphous polyethylene terephthalate resin include copolymers further containing isophthalic acid and/or cyclohexane dicarboxylic acid as a dicarboxylic acid, and copolymers further containing cyclohexanedimethanol or diethylene glycol as a glycol.
  • a polyethylene terephthalate resin having an isophthalic acid unit is preferably used. This is because it has extremely excellent stretchability and can suppress crystallization during stretching. This is thought to be due to the fact that the introduction of the isophthalic acid unit imparts a large bend to the main chain.
  • Polyethylene terephthalate resin has a terephthalic acid unit and an ethylene glycol unit.
  • the content of the isophthalic acid unit is preferably 0.1 mol% or more, more preferably 1.0 mol% or more, based on the total of all repeating units. This is because a thermoplastic resin base material with extremely excellent stretchability can be obtained.
  • the content of isophthalic acid units is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all repeating units. This is because the degree of crystallinity can be favorably increased in the drying process described below.
  • the thermoplastic resin base material may be stretched in advance (for example, before forming the PVA-based resin layer).
  • the elongated thermoplastic resin base material is stretched in the lateral direction.
  • the lateral direction is preferably a direction perpendicular to the stretching direction of the laminate described below.
  • “orthogonal” also includes a case where they are substantially orthogonal.
  • substantially orthogonal includes a case where the angle is 90° ⁇ 5.0°, preferably 90° ⁇ 3.0°, and more preferably 90° ⁇ 1.0°.
  • the stretching temperature of the thermoplastic resin base material is preferably Tg-10°C to Tg+50°C with respect to the glass transition temperature (Tg) of the thermoplastic resin base material.
  • the stretching ratio of the thermoplastic resin base material is preferably 1.5 times to 3.0 times. Any suitable method may be employed as a method for stretching the thermoplastic resin base material. Specifically, fixed end stretching or free end stretching may be used. The stretching method may be a dry method or a wet method. Stretching may be performed in one step or in multiple steps. When performing multi-stage stretching, the stretching ratio is the product of the stretching ratios of each stage.
  • the above-mentioned coating liquid is typically a solution in which a PVA-based resin and a halide are dissolved in a solvent.
  • the solvent 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 content of the PVA resin in the coating liquid is preferably 3 parts by weight to 20 parts by weight based on 100 parts by weight of the solvent. According to such a range, a uniform coating film that adheres to the thermoplastic resin base material can be formed.
  • the content of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight based on 100 parts by weight of the PVA resin.
  • the PVA-based resin examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymer.
  • Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
  • Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer.
  • the degree of saponification of the PVA 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%. It is. By using a PVA resin having such a degree of saponification, a polarizing film with excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation. Note that the degree of saponification can be determined according to JIS K 6726-1994.
  • the average degree of polymerization of the PVA resin is usually 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. Note that the average degree of polymerization can be determined according to JIS K 6726-1994.
  • any suitable halide may be employed as the halide.
  • iodides such as potassium iodide, sodium iodide, and lithium iodide
  • chlorides such as sodium chloride.
  • potassium iodide is preferred.
  • a polarizing film having excellent optical properties can be obtained. Specifically, the crystallization of the PVA-based resin after the aerial auxiliary stretching described below is promoted, and the orientation of polyvinyl alcohol molecules is disturbed and the orientation is reduced in subsequent wet treatments (e.g., dyeing and underwater stretching described below). can be suppressed, and a polarizing film having excellent optical properties can be obtained.
  • the coating solution it is preferable to mix 5 parts by weight to 20 parts by weight of a halide, more preferably 10 parts by weight to 15 parts by weight, per 100 parts by weight of PVA-based resin.
  • the content of halide in the resulting PVA resin layer is preferably 5 parts by weight to 20 parts by weight, more preferably 10 parts by weight to 15 parts by weight, based on 100 parts by weight of PVA resin. It is. If the amount of halide relative to the PVA-based resin is large, for example, the halide may bleed out and the resulting polarizing film may become cloudy.
  • Additives may be added to the coating solution.
  • additives include plasticizers and surfactants.
  • plasticizer include polyhydric alcohols such as ethylene glycol and glycerin.
  • surfactant include nonionic surfactants. These are used, for example, for the purpose of improving the uniformity, dyeability, and stretchability of the resulting PVA-based resin layer.
  • Examples of methods for applying the above coating liquid include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.). It will be done.
  • the coating and drying temperature of the coating liquid is preferably 50°C or higher.
  • the thickness of the PVA resin layer is preferably 3 ⁇ m to 40 ⁇ m, more preferably 3 ⁇ m to 20 ⁇ m.
  • the thermoplastic resin base material Before forming the PVA-based resin layer, the thermoplastic resin base material may be subjected to surface treatment (for example, corona treatment, etc.), or an easily adhesive layer may be formed on the thermoplastic resin base material. By performing such a treatment, the adhesion between the thermoplastic resin base material and the PVA resin layer can be improved.
  • surface treatment for example, corona treatment, etc.
  • an easily adhesive layer may be formed on the thermoplastic resin base material.
  • thermoplastic resin base material can be stretched while suppressing crystallization, and this solves the problem that the stretchability is reduced due to excessive crystallization of the thermoplastic resin base material during stretching in boric acid water.
  • the laminate can be stretched to a higher magnification.
  • the coating temperature may be set low, which may cause a problem that crystallization of the PVA-based resin becomes relatively low and sufficient optical properties cannot be obtained.
  • auxiliary stretching the crystallinity of the PVA-based resin can be improved even when a thermoplastic resin is used.
  • problems such as a decrease in orientation and dissolution of the PVA resin can be prevented during subsequent wet processing. In this way, a polarizing film having excellent optical properties can be obtained.
  • the method of aerial auxiliary stretching may be fixed-end stretching (e.g., stretching using a tenter stretching machine) or free-end stretching (e.g., uniaxial stretching by passing the laminate between rolls with different circumferential speeds).
  • free end stretching is employed.
  • heating roll stretching may be employed, in which the laminate is stretched in the longitudinal direction by a difference in circumferential speed between heating rolls.
  • the aerial assisted stretching includes a zone stretching step in a thermal space (zone) and a heated roll stretching step.
  • the order of the zone stretching step and the heating roll stretching step is not limited, for example, the zone stretching step and the heating roll stretching step are performed in this order.
  • the ends of the film are held and the film is stretched by widening the distance between the tenters in the machine direction (the widening of the distance between the tenters becomes the stretching ratio).
  • the tenter distance in the width direction (perpendicular to the flow direction) is preferably set to be closer to the free end stretching than the stretching ratio in the flow direction.
  • the stretching ratio of the aerial auxiliary stretching is preferably 2.0 times to 3.5 times.
  • Aerial assisted stretching may be performed in one step or in multiple steps. In the case of multi-stage stretching, the stretching ratio is the product of the stretching ratios of each stage.
  • the stretching direction in the aerial auxiliary stretching is preferably substantially the same as the stretching direction in the underwater stretching described below.
  • the stretching temperature of the in-air auxiliary stretching is set to any appropriate value depending on, for example, the thermoplastic resin base material used, the stretching method, etc.
  • the stretching temperature is preferably at least the glass transition temperature (Tg) of the thermoplastic resin base material, more preferably at least Tg+10°C, even more preferably at least Tg+15°C.
  • the upper limit of the stretching temperature is preferably 170°C.
  • the above-mentioned underwater stretching is typically performed by immersing the laminate in a stretching bath. According to underwater stretching, it is possible to stretch the PVA resin layer at a temperature lower than the glass transition temperature (typically about 80° C.) of the thermoplastic resin base material and the PVA resin layer, and the PVA resin layer can be stretched at a temperature lower than the glass transition temperature (typically about 80° C.). It is possible to stretch to a high magnification while suppressing the stretching. As a result, a polarizing film having excellent optical properties can be obtained.
  • the underwater stretching method may be fixed-end stretching or free-end stretching (for example, a method of uniaxial stretching by passing the laminate through rolls having different circumferential speeds).
  • free end stretching is employed.
  • the laminate may be stretched in one step or in multiple steps.
  • the stretching ratio of the laminate described below is the product of the stretching ratios of each stage.
  • the stretching in water is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in boric acid water).
  • a boric acid aqueous solution as a stretching bath, it is possible to impart rigidity to the PVA-based resin layer to withstand tension applied during stretching, and water resistance that does not dissolve in water.
  • boric acid can generate a tetrahydroxyborate anion in an aqueous solution and crosslink with the PVA-based resin through hydrogen bonding.
  • rigidity and water resistance can be imparted to the PVA-based resin layer, which can be stretched well, and a polarizing film having excellent optical properties can be obtained.
  • the aqueous boric acid solution is preferably obtained by dissolving boric acid and/or a borate salt in water, which is a solvent.
  • the boric acid concentration is preferably 1 to 10 parts by weight, more preferably 2.5 to 6 parts by weight, even more preferably 3 to 5 parts by weight, based on 100 parts by weight of water. It is. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film with higher characteristics can be manufactured.
  • an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, etc. in a solvent can also be used.
  • iodide is added to the stretching bath (boric acid aqueous solution).
  • the stretching bath boric acid aqueous solution.
  • iodide By blending iodide, it is possible to suppress elution of iodine adsorbed to the PVA-based resin layer.
  • 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. can be mentioned.
  • the concentration of iodide is preferably 0.05 parts by weight to 15 parts by weight, more preferably 0.5 parts by weight to 8 parts by weight, based on 100 parts by weight of water.
  • the stretching temperature (the liquid temperature of the stretching bath) is preferably 40°C or higher, more preferably 60°C or higher. At such a temperature, it is possible to stretch to a high magnification while suppressing dissolution of the PVA-based resin layer.
  • the glass transition temperature (Tg) of the thermoplastic resin base material 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., there is a possibility that the stretching cannot be performed satisfactorily even if the plasticization of the thermoplastic resin base material by water is taken into account.
  • the stretching temperature is, for example, 70°C or lower, preferably 67°C or lower, and more preferably 65°C or lower. As the stretching temperature becomes higher, the solubility of the PVA-based resin layer becomes higher, and there is a possibility that excellent optical properties may not be obtained.
  • the immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.
  • the stretching ratio by underwater stretching is preferably 1.5 times or more, more preferably 3.0 times or more.
  • the total stretching 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. Yes, and more preferably 6.0 times or more.
  • Such a high stretching ratio can be achieved by employing an underwater stretching method (boric acid underwater stretching).
  • the above-mentioned dyeing is typically performed by adsorbing iodine to the PVA resin layer.
  • Iodine adsorption methods include, for example, immersing a PVA resin layer (laminate) in a dyeing solution containing iodine, coating the PVA resin layer with the dyeing solution, and applying the dyeing solution to the PVA resin layer.
  • the method of spraying is mentioned.
  • the method involves immersing the laminate in a dyeing solution (dyeing bath). This is because iodine can be adsorbed well.
  • the staining solution is preferably an iodine aqueous solution.
  • the amount of iodine blended is preferably 0.05 part by weight to 0.5 part by weight per 100 parts by weight of water.
  • iodide is added to the iodine aqueous solution.
  • Specific examples of iodides are as described above.
  • potassium iodide is used.
  • the amount of iodide to be blended is preferably 0.1 parts by weight to 10 parts by weight, more preferably 0.3 parts by weight to 5 parts by weight, based on 100 parts by weight of water.
  • the temperature of the dyeing solution during dyeing is preferably 20° C. to 50° C. in order to suppress dissolution of the PVA 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 resin layer.
  • the dyeing conditions can be set, for example, so that the resulting resin film has a single transmittance of 42% or more and a polarization degree of 85% or more.
  • staining conditions for example, it is preferable that the content ratio of iodine and potassium iodide in the iodine aqueous solution that is the staining solution is 1:5 to 1:20, more preferably 1:5 to 1. :10.
  • boric acid mixes into the dyeing bath and the boric acid concentration in the dyeing bath changes. Staining properties may become unstable.
  • the concentration of boric acid in the dyeing bath is adjusted to preferably 4 parts by weight or less, more preferably 2 parts by weight or less, based on 100 parts by weight of water. be done.
  • the concentration of boric acid in the dyeing bath is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, and even more preferably 0.5 parts by weight, based on 100 parts by weight of water. That's all.
  • the dyeing is performed in advance using a dyeing bath containing boric acid.
  • a dyeing bath containing boric acid According to such a form, the rate of change in boric acid concentration when boric acid is mixed into the dyeing bath can be reduced.
  • the amount of boric acid blended in advance in the dyeing bath (the content of boric acid not derived from the above treatment bath) is preferably 0.1 parts by weight to 2 parts by weight, more preferably 0.1 parts by weight to 2 parts by weight, based on 100 parts by weight of water. is from 0.5 parts by weight to 1.5 parts by weight.
  • insolubilization treatment is performed after the above-mentioned aerial auxiliary stretching and before underwater stretching and dyeing.
  • the insolubilization treatment is typically performed by immersing the PVA resin layer in a boric acid aqueous solution.
  • concentration of the aqueous boric acid solution in the insolubilization treatment is preferably 1 part by weight to 4 parts by weight per 100 parts by weight of water.
  • the temperature of the insolubilization treatment (the temperature of the boric acid aqueous solution) is preferably 20°C to 50°C.
  • crosslinking treatment is performed after dyeing and before underwater stretching.
  • the crosslinking treatment is typically performed by immersing the PVA resin layer in a boric acid aqueous solution.
  • the concentration of the boric acid aqueous solution in the crosslinking treatment is preferably 1 to 5 parts by weight per 100 parts by weight of water. It is preferable to mix iodide with the boric acid aqueous solution. By blending iodide, it is possible to suppress elution of iodine adsorbed to the PVA-based resin layer.
  • the amount of iodide to be blended is preferably 1 to 5 parts by weight per 100 parts by weight of water.
  • the temperature of the crosslinking treatment is preferably 20°C to 50°C.
  • washing is performed after stretching in water and before drying as described below.
  • Cleaning is typically performed by immersing the PVA resin layer in an aqueous potassium iodide solution.
  • the drying described above may be performed in any suitable manner and conditions.
  • the heating may be performed by heating the entire zone (zone heating method) or by heating the conveyance roll (heating roll method).
  • a heated roll method is employed, and more preferably both are employed.
  • heating curling of the laminate can be efficiently suppressed and a polarizing film with excellent quality can be manufactured.
  • by drying the laminate along a heating roll it is possible to efficiently promote crystallization of the thermoplastic resin base material and increase the degree of crystallinity, which is relatively low. Even at drying temperatures, the degree of crystallinity of the thermoplastic resin base material can be increased favorably.
  • thermoplastic resin base material has increased rigidity and is in a state where it can withstand shrinkage of the PVA resin layer due to drying, thereby suppressing curling. Furthermore, by using a heating roll, the laminate can be dried while maintaining it in a flat state, so that not only curling but also wrinkles can be suppressed.
  • the laminate By drying, the laminate can be shrunk in the width direction and its optical properties can be improved. This is because the orientation of PVA and PVA/iodine complex can be effectively improved.
  • the shrinkage rate of the laminate in the width direction upon drying is preferably 1% to 10%, more preferably 2% to 8%, and even more preferably 4% to 6%.
  • the laminate By using a heating roll, the laminate can be continuously contracted in the width direction while being conveyed, and high productivity can be achieved.
  • FIG. 2 is a schematic diagram showing an example of drying using a heating roll.
  • 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.
  • transport rolls R1 to R6 are arranged so as to alternately and continuously heat the surface of the PVA resin layer and the surface of the thermoplastic resin base material.
  • the transport rolls R1 to R6 may be arranged so as to continuously heat only the resin base material surface).
  • the drying conditions can be controlled by adjusting the heating temperature of the transport roll (temperature of the heating roll), the number of heating rolls, the contact time with the heating roll, etc.
  • the temperature of the heating roll is preferably 60°C to 120°C, more preferably 65°C to 100°C, even more preferably 70°C to 80°C. According to such a temperature, the degree of crystallinity of the thermoplastic resin can be increased to suppress curling, and at the same time, extremely excellent durability can be imparted to the laminate.
  • the temperature of the heating roll can be measured with a contact thermometer. In the illustrated example, six conveyance rolls are provided, but there is no particular restriction on the number of conveyance rolls as long as there is a plurality of conveyance rolls. Usually 2 to 40 conveyance rolls, preferably 4 to 30 conveyance rolls are provided.
  • the contact time (total contact time) between the laminate and the heating roll is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and even more preferably 1 to 10 seconds.
  • the heating roll may be provided within a heating furnace (for example, an oven) or may be provided on a normal production line (at room temperature). Preferably, it is provided in a heating furnace equipped with air blowing means.
  • a heating furnace equipped with air blowing means.
  • the temperature of hot air drying is preferably 30°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 10 m/s to 30 m/s. Note that the wind speed is the wind speed within the heating furnace, and can be measured with a mini-vane digital anemometer.
  • the moisture content of the resin film subjected to the first step described below is, for example, 15% by weight or less, preferably 12% by weight or less, more preferably 9% by weight or less, and still more preferably 6% by weight. % or less.
  • the moisture content of the resin film is, for example, 3% by weight or more.
  • the resin film that has undergone the above drying process can satisfy such a moisture content.
  • the resin film to be subjected to the first step described below preferably exhibits absorption dichroism at a wavelength of 380 nm to 780 nm.
  • the single transmittance (Ts) of the resin film is, for example, 42% or more, preferably 44% or more. As the transmittance increases, streaks tend to be more visible. On the other hand, the single transmittance (Ts) of the resin film is, for example, 49% or less. Note that the single transmittance is sometimes simply referred to as transmittance.
  • the transmittance of the resin film subjected to the first step described below may be referred to as a first transmittance (T1).
  • the degree of polarization (P) of the resin film subjected to the first step described below is, for example, 85% or more, preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. be. On the other hand, the degree of polarization of the resin film is, for example, 99.996% or less.
  • the above-mentioned single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction.
  • the degree of polarization is typically determined by the following formula based on parallel transmittance Tp and cross transmittance Tc measured using an ultraviolet-visible spectrophotometer and corrected for visibility.
  • Degree of polarization (%) ⁇ (Tp-Tc)/(Tp+Tc) ⁇ 1/2 ⁇ 100
  • the orientation of the resin film (PVA orientation) to be subjected to the first step described below is, for example, 0.20 or more, preferably 0.25 or more, and more preferably 0.30 or more.
  • the orientation of the resin film (PVA orientation) is, for example, 0.40 or less.
  • the thickness of the resin film subjected to the first step described below is, for example, 22 ⁇ m or less, may be 16 ⁇ m or less, may be 12 ⁇ m or less, may be 8 ⁇ m or less, and may be 6 ⁇ m or less. Good too. On the other hand, the thickness of the resin film is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more.
  • the resin film is brought into contact with the first liquid.
  • the resin film is immersed in the first liquid.
  • one side of the resin film may be supported (protected) by any suitable support base material.
  • the resin base material described above is used as the support base material.
  • the resin film is immersed in the first liquid without peeling the resin base material from the resin film (in the state of the above-mentioned laminate).
  • the protective layer described below is used as the supporting substrate.
  • the resin base material is peeled off from the resin film to produce a laminate of the protective layer and the resin film, and this laminate is immersed in the first liquid.
  • the resin film may be elongated or sheet-like.
  • the transmittance of the resin film is increased from the first transmittance (T1) to the second transmittance (T2).
  • T1 first transmittance
  • T2 second transmittance
  • the difference between the second transmittance (T2) and the first transmittance (T1) is preferably 1.5% or more, more preferably 3% or more, may be 5% or more, and may be 7% or more. It may be more than that.
  • the difference between the second transmittance (T2) and the first transmittance (T1) is preferably 10% or less.
  • the second transmittance (T2) is, for example, 45% or more, preferably 47% or more.
  • the second transmittance (T2) is preferably 55% or less.
  • the degree of polarization (P) of the resin film By contacting with the first liquid, the degree of polarization (P) of the resin film can be reduced.
  • the difference in the degree of polarization (P) of the resin film before and after contact with the first liquid is, for example, 10% to 20%.
  • the degree of polarization (P) of the resin film after contact with the first liquid is, for example, 65% to 97%.
  • the difference in orientation of the resin film (orientation of PVA) before and after contact with the first liquid is, for example, 0.05 to 0.2.
  • the orientation of the resin film after contact with the first liquid (orientation of PVA) is, for example, 0.10 to 0.30.
  • the temperature of the first liquid when it is brought into contact with the resin film is preferably 60°C or higher, may be 65°C or higher, may be 70°C or higher, or may be 75°C or higher.
  • the transmittance of the resin film can be favorably increased.
  • the temperature of the first liquid is, for example, 90°C or lower, preferably 85°C or lower.
  • the immersion time (contact time) in the first liquid is set depending on, for example, the temperature of the first liquid, the thickness of the resin film, the concentration of components contained in the first liquid, and the like.
  • the immersion time in the first liquid is, for example, 1 minute to 60 minutes, preferably 2 minutes to 30 minutes.
  • the first liquid typically contains an aqueous solvent (preferably water).
  • a boric acid aqueous solution is preferably used as the first liquid.
  • the concentration of the boric acid aqueous solution is preferably 3% by weight or more, and may be 4% by weight or more.
  • the concentration of the boric acid aqueous solution is, for example, 8% by weight or less, and may be 7% by weight or less.
  • the first liquid contains an iodine compound.
  • an iodine compound By including an iodine compound, the entry and exit of components originally contained in the resin film can be promoted.
  • Specific examples of the iodine compound include iodine, potassium iodide, and other iodides. These may be used alone or in combination of two or more.
  • the concentration of iodine in the first liquid is preferably 0.002% by weight or more.
  • the concentration of iodine in the first liquid is preferably 0.01% by weight or less, more preferably 0.005% by weight or less. Such a concentration can satisfactorily increase the transmittance of the resin film.
  • the concentration of iodide in the first liquid is, for example, 0.007% by weight or more, preferably 2% by weight or more.
  • the iodide concentration in the first liquid is preferably 10% by weight or less. Such a concentration can satisfactorily increase the transmittance of the resin film.
  • the resin film is brought into contact with the second liquid.
  • the resin film is immersed in the second liquid.
  • one side of the resin film is preferably supported (protected) by any suitable support base material. The details are as described above.
  • the resin film can be cleaned (eg, boric acid cleaning).
  • the hue of the resulting polarizing film can be adjusted by bringing it into contact with the second liquid.
  • the transmittance of the resin film can be lowered from the second transmittance (T2) to the third transmittance (T3).
  • the third transmittance (T3) corresponds to the single transmittance (Ts) of a polarizing film, which will be described later.
  • the processing conditions using the second liquid are adjusted depending on the desired optical properties (for example, single transmittance, degree of polarization) of the resulting polarizing film.
  • the difference between the second transmittance (T2) and the third transmittance (T3) is, for example, 0.1% to 10%.
  • the degree of polarization (P) of the resin film By bringing it into contact with the second liquid, the degree of polarization (P) of the resin film can be increased.
  • the difference in the degree of polarization (P) of the resin film before and after contact with the second liquid is, for example, 0.1% to 20%. Note that the degree of polarization (P) of the resin film after contact with the second liquid corresponds to the degree of polarization (P) of a polarizing film, which will be described later.
  • the orientation of the resin film By bringing it into contact with the second liquid, the orientation of the resin film (orientation of PVA) can be increased.
  • the difference in the orientation of the resin film (orientation of PVA) before and after contact with the second liquid is, for example, 0.01 to 0.10.
  • the orientation of the resin film after contact with the second liquid (orientation of PVA) is, for example, 0.15 to 0.35.
  • the temperature of the second liquid when it is brought into contact with the resin film is typically set to room temperature. For example, 15°C to 40°C.
  • the immersion time (contact time) in the second liquid is, for example, 1 second to 1 minute.
  • the second liquid typically contains an aqueous solvent (preferably water).
  • the second liquid may contain iodide such as potassium iodide. By containing iodide, the blue tint of the resulting polarizing film can be suppressed.
  • concentration of iodide in the second iodide solution is, for example, 0% to 6% by weight.
  • the resin film (polarizing film) that has undergone the second step may be dried.
  • the drying temperature is, for example, 30°C to 60°C.
  • the drying time is, for example, 15 seconds to 3 minutes.
  • the polarizing film obtained by the manufacturing method according to the embodiment of the present invention can exhibit absorption dichroism at any wavelength from 380 nm to 780 nm.
  • the single transmittance (Ts) of the polarizing film is preferably 42% or more, may be 44% or more, or may be 46% or more. Such a transmittance can contribute to reducing the power consumption of the mounted image display device. According to the manufacturing method according to the embodiment of the present invention, a polarizing film having both high transmittance and excellent appearance can be obtained.
  • the single transmittance (Ts) of the polarizing film is, for example, 55% or less, may be 50% or less, or may be 48% or less.
  • the degree of polarization (P) of the polarizing film is, for example, 70% or more, preferably 75% or more, and more preferably 85% or more. On the other hand, the degree of polarization of the polarizing film is, for example, 98% or less.
  • the orientation of the polarizing film is preferably 0.20 or more, more preferably 0.25 or more.
  • the orientation of the resin film is, for example, 0.35 or less.
  • the thickness of the polarizing film is, for example, 22 ⁇ m or less, may be 16 ⁇ m or less, may be 12 ⁇ m or less, may be 8 ⁇ m or less, or may be 6 ⁇ m or less.
  • the thickness of the polarizing film is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more.
  • a polarizing plate according to one embodiment of the present invention includes the above polarizing film and a protective layer or a retardation layer disposed on at least one side of the polarizing film.
  • FIG. 3 is a schematic cross-sectional view showing the general configuration of a polarizing plate according to one embodiment of the present invention.
  • a polarizing plate (a polarizing plate with a retardation layer) 100 includes a polarizing film 10 having a first main surface 10a and a second main surface 10b facing each other, and a first main surface 10a side (for example, the viewing side) of the polarizing film 10. , and a retardation layer 30 and an adhesive layer 40 arranged on the second main surface 10b side of the polarizing film 10.
  • the retardation layer 30 may be a single layer or may have a laminated structure in which two or more layers are laminated. Further, a second protective layer may be disposed between the polarizing film 10 and the retardation layer 30.
  • the polarizing plate may further include other functional layers.
  • the type, characteristics, number, combination, arrangement, etc. of functional layers that a polarizing plate may have can be appropriately set depending on the purpose.
  • the polarizing plate may further include a conductive layer or an isotropic substrate with a conductive layer.
  • a polarizing plate having a conductive layer or an isotropic substrate with a conductive layer is applied to, for example, a so-called inner touch panel type input display device in which a touch sensor is incorporated inside an image display panel.
  • the polarizing plate may further include another retardation layer.
  • the viewing side of the polarizing film 10 may include another retardation layer (typically, a layer imparting an (elliptical) circular polarization function, a super A layer imparting a high retardation) may be provided.
  • another retardation layer typically, a layer imparting an (elliptical) circular polarization function, a super A layer imparting a high retardation
  • the obtained polarizing plate polarizing plate with a retardation layer
  • an image display device that can be used outdoors.
  • Each member constituting the polarizing plate may be laminated via any appropriate adhesive layer (not shown).
  • the adhesive layer include an adhesive layer and a pressure-sensitive adhesive layer.
  • the retardation layer 30 may be bonded to the polarizing film 10 or the second protective layer via an adhesive layer (preferably using an active energy ray-curable adhesive), or may be attached to the polarizing film 10 or the second protective layer via an adhesive layer (preferably using an active energy ray-curable adhesive). It may be bonded to the polarizing film 10 or the second protective layer via an agent layer.
  • the retardation layer 30 has a laminated structure of two or more layers, the respective retardation layers are bonded together, for example, via an adhesive layer (preferably using an active energy ray-curable adhesive).
  • a release liner is practically bonded to the surface of the adhesive layer 40.
  • the release liner may be temporarily attached until the polarizer is ready for use.
  • the adhesive layer 40 can be protected and the polarizing plate can be formed into a roll.
  • the polarizing plate may be elongated or sheet-like.
  • "elongate shape” refers to an elongated shape whose length is sufficiently longer than its width, for example, an elongated shape whose length is 10 times or more, preferably 20 times or more as compared to its width. say.
  • the elongated polarizing plate can be wound into a roll.
  • the above-mentioned protective layer may be formed of any suitable film that can be used as a protective layer of a polarizing film.
  • suitable films such as triacetylcellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, and polysulfones.
  • TAC triacetylcellulose
  • polyesters polyvinyl alcohols
  • polycarbonates polyamides
  • polyimides polyethersulfones
  • polysulfones polysulfones.
  • polystyrene cycloolefin such as polynorbornene, polyolefin, (meth)acrylic, acetate, and other transparent resins.
  • the polarizing plate is typically placed on the viewing side of the image display device. Therefore, the protective layer 20 may be subjected to surface treatments such as hard coat (HC) treatment, antireflection treatment, antisticking treatment, and antiglare treatment, as necessary.
  • HC hard coat
  • antireflection treatment antisticking treatment
  • antiglare treatment antiglare treatment
  • the thickness of the protective layer is preferably 5 ⁇ m to 80 ⁇ m, more preferably 10 ⁇ m to 40 ⁇ m, even more preferably 10 ⁇ m to 30 ⁇ m.
  • the thickness of the protective layer is the thickness including the thickness of the surface treatment layer.
  • the second protective layer disposed between the polarizing film 10 and the retardation layer 30 is preferably optically isotropic.
  • optically isotropic means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. say.
  • the resin base material can be used as it is as a protective layer of a polarizing film. According to this embodiment, the number of manufacturing steps can be reduced.
  • the retardation layer 30 may be a single layer or may have a laminated structure (for example, a two-layer structure).
  • the retardation layer 30 may have any appropriate optical properties depending on the application and the like.
  • retardation layer 30 includes a first retardation layer that can function as a ⁇ /4 plate.
  • the in-plane retardation Re (550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and still more preferably 120 nm to 160 nm.
  • the Nz coefficient of the first retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3.
  • the first retardation layer may exhibit inverse dispersion wavelength characteristics in which the retardation value increases depending on the wavelength of the measurement light.
  • Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less.
  • the retardation layer 30 may be made of any suitable material as long as it satisfies the desired characteristics.
  • the retardation layer may be a resin film (stretched film), an oriented solidified layer of a liquid crystal compound, or a combination thereof.
  • Adhesive Layer Any suitable configuration may be adopted as the adhesive layer 40. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and blending ratio of monomers that form the base resin of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., adhesives can have desired characteristics depending on the purpose. can be prepared.
  • the base resin of the adhesive may be used alone or in combination of two or more types.
  • the base resin is preferably an acrylic resin (specifically, the adhesive layer is preferably composed of an acrylic adhesive).
  • the thickness of the adhesive layer 40 is, for example, 10 ⁇ m to 20 ⁇ m.
  • a polarizing plate can typically be obtained by laminating various layers such as a retardation layer on the polarizing film obtained through the first and second steps described above.
  • the thickness and moisture content of the resin film are values measured by the following measuring method. Furthermore, unless otherwise specified, "parts" and “%” in Examples and Comparative Examples are based on weight. 1. Thickness The thickness of 10 ⁇ m or less was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name “JSM-7100F”). Thickness exceeding 10 ⁇ m was measured using a digital micrometer (manufactured by Anritsu Corporation, product name “KC-351C”). 2.
  • Moisture content of resin film The amount of water contained in the resin film was determined by drying the resin film alone (the resin film peeled from the resin base material) at 120°C for 2 hours and measuring the weight change before and after drying. was determined, and the moisture content was calculated.
  • thermoplastic resin base material a long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 ⁇ m) having a water absorption rate of 0.75% and a Tg of about 75° C. was used.
  • One side of the resin base material was subjected to corona treatment.
  • 100 weight PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name "Gosefaimer Z410”) at a ratio of 9:1.
  • the laminate was immersed for 30 seconds in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. (insolubilization treatment).
  • an insolubilization bath boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water
  • the single transmittance of the resulting resin film was added to a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water) at a liquid temperature of 30°C. It was immersed for 60 seconds while adjusting the concentration so that (Ts) was 43% or more (staining).
  • the laminate was immersed in a cleaning bath (an 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. (cleaning). Thereafter, while drying in an oven maintained at 90°C, it was brought into contact with a SUS heating roll whose surface temperature was maintained at 75°C for about 2 seconds (drying). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%. In this way, a resin film having a thickness of 5.5 ⁇ m and a moisture content of 4.4% was formed on the resin base material.
  • HC-cycloolefin resin (COP) film was attached to one side of the obtained resin film (the side on which the resin base material was not placed) via an ultraviolet curable adhesive.
  • the resin base material was peeled off from the resin film to obtain a laminate of the HC-COP film and the resin film.
  • the HC-COP film is a film in which an HC layer (thickness: 2 ⁇ m) is formed on a cycloolefin resin (COP) film (thickness: 25 ⁇ m), and the films are bonded together with the COP film facing the resin film side.
  • the obtained laminate was immersed in a first liquid (aqueous solution) having a boric acid concentration of 6% and a potassium iodide concentration of 2% at 80° C. for 8 minutes. Thereafter, it was immersed in a water bath (second liquid) at room temperature for 15 seconds and then dried at 60° C. for 1 minute to obtain a polarizing plate having an HC-COP film and a polarizing film.
  • a first liquid aqueous solution
  • second liquid water bath
  • Example 2 A polarizing plate having an HC-COP film and a polarizing film was obtained in the same manner as in Example 1 except that an aqueous potassium iodide solution (2% concentration) was used as the second liquid.
  • Example 3 Same as Example 1 except that an aqueous solution with a boric acid concentration of 5% and an iodine concentration of 0.005% at 80°C was used as the first liquid, and the immersion time in the first liquid was 5 minutes. A polarizing plate having an HC-COP film and a polarizing film was obtained.
  • Example 4 A polarizing plate having an HC-COP film and a polarizing film was obtained in the same manner as in Example 3 except that an aqueous potassium iodide solution (2% concentration) was used as the second liquid.
  • Example 1 A polarizing plate having an HC-COP film and a polarizing film was obtained in the same manner as in Example 1 except that the treatment using the first liquid and the second liquid was not performed.
  • Example 2 Same as Example 1 except that an aqueous solution with a boric acid concentration of 4% and an iodine concentration of 0.003% at 50°C was used as the first liquid, and the immersion time in the first liquid was 30 minutes. A polarizing plate having an HC-COP film and a polarizing film was obtained.
  • the dyeing process is carried out in an aqueous solution at 30°C in which the weight ratio of iodine and potassium iodide is 1:7 and the iodine concentration is adjusted so that the single transmittance of the resulting resin film is 42% or more.
  • Stretched Next, a two-stage crosslinking treatment was adopted for the crosslinking treatment, and the first crosslinking treatment was performed in an aqueous solution containing boric acid and potassium iodide at 40° C. while being stretched.
  • the boric acid content of the aqueous solution for the first stage crosslinking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight.
  • the film was stretched while being treated in an aqueous solution containing boric acid and potassium iodide at 65°C.
  • the boric acid content of the aqueous solution for the second stage crosslinking treatment was 4.3% by weight, and the potassium iodide content was 5.0% by weight.
  • washing treatment was performed with a potassium iodide aqueous solution at 20°C.
  • the potassium iodide content of the aqueous solution for cleaning treatment was 2.6% by weight.
  • a resin film was obtained by drying at 70° C. for 5 minutes.
  • a 27 ⁇ m thick HC-COP film was attached to one side of the obtained resin film via an ultraviolet curable adhesive to obtain a laminate (polarizing plate) of the HC-COP film and the resin film.
  • Reference example 2 The laminate of Reference Example 1 was immersed in a first liquid (aqueous solution) having a boric acid concentration of 6% and an iodine concentration of 0.003% at 80° C. for 10 minutes. Thereafter, it was immersed in a water bath (second liquid) at room temperature for 15 seconds and then dried at 60° C. for 1 minute to obtain a polarizing plate having an HC-COP film and a polarizing film.
  • a first liquid aqueous solution
  • second liquid water bath
  • Ts, Tp, and Tc are Y values measured using a 2-degree visual field (C light source) according to JIS Z8701 and subjected to visibility correction.
  • the degree of polarization P was determined from the obtained Tp and Tc using the following formula.
  • Polarization degree P (%) ⁇ (Tp-Tc)/(Tp+Tc) ⁇ 1/2 ⁇ 100
  • the ratio b (a 0° /a 90°) of the intensity ratio a (when the incident angle is 0°) and the intensity ratio a (when the incident angle is 90° ) is calculated, and the orientation index is calculated.
  • c (1-b)/[(2b+1) ⁇ (-2)] was calculated.
  • the higher the value of c the higher the orientation of PVA.
  • a laminate for evaluation was produced using the obtained polarizing plate. Specifically, after laminating the following retardation layer to the polarizing film side of a polarizing plate via an acrylic adhesive layer (15 ⁇ m), A reflective sheet (manufactured by Toray Film Kako Co., Ltd., "Therapel DMS-X42") was laminated to obtain a laminate for evaluation. The reflectance of the reflective sheet was 88% when measured in SCI mode using a spectrophotometer (CM-2600d, manufactured by Konica Minolta). The appearance (presence or absence of streaks) of the obtained evaluation laminate when viewed from the polarizing plate side was visually observed. (Evaluation criteria) Good: No streaks are observed Bad: Streaks are visible
  • the oligomerized reaction liquid in the first reactor was transferred to the second reactor.
  • temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 240° C. and the pressure was 0.2 kPa in 50 minutes.
  • polymerization was allowed to proceed until a predetermined stirring power was reached.
  • nitrogen was introduced into the reactor to restore the pressure nitrogen was introduced into the reactor to restore the pressure, the produced polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets.
  • polyester carbonate resin pellets
  • a single-screw extruder manufactured by Toshiba Machine Co., Ltd., cylinder temperature setting: 250°C
  • T-die width 200mm, setting temperature: 250°C
  • a long resin film with a thickness of 135 ⁇ m was produced using a film forming apparatus equipped with a chill roll (set temperature: 120 to 130° C.), a winder and a winder.
  • the obtained elongated resin film was stretched in the width direction at a stretching temperature of 143° C. and a stretching ratio of 2.8 times to obtain a stretched film with a thickness of 47 ⁇ m.
  • the obtained stretched film had Re(550) of 143 nm, Re(450)/Re(550) of 0.86, and Nz coefficient of 1.12.
  • the three polarizing plates were arranged so that the absorption axes of adjacent polarizing plates were perpendicular to each other (three-plate cross method). Moreover, the first polarizing plate and the second polarizing plate were arranged in a state where they were bonded to a glass plate. (Evaluation criteria) Good: No streaks are observed Bad: Streaks are visible
  • the polarizing film according to the embodiment of the present invention is suitably used in image display devices such as, for example, liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

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

L'invention fournit un film polarisant qui présente une excellente apparence, et qui permet de contribuer à l'amélioration des caractéristiques d'affichage d'un dispositif d'affichage d'image. Selon un mode de réalisation, l'invention concerne un procédé de fabrication de film polarisant qui inclut dans l'ordre : une première étape au cours de laquelle un film de résine qui contient un iode, et qui possède une première transmittance (T1), est mis en contact avec un premier liquide, et la transmittance dudit film de résine est élevée au rang de seconde transmittance (T2); et une seconde étape au cours de laquelle ledit film de résine est mis en contact avec un second liquide, et la transmittance dudit film de résine est rabaissée au rang de troisième transmittance (T3).
PCT/JP2023/014364 2022-05-10 2023-04-07 Procédé de fabrication de film polarisant WO2023218820A1 (fr)

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JP2022077710A JP2023166876A (ja) 2022-05-10 2022-05-10 偏光膜の製造方法

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004013005A (ja) * 2002-06-10 2004-01-15 Fuji Photo Film Co Ltd 偏光膜の製造方法
CN112248611A (zh) * 2020-10-12 2021-01-22 深圳市盛波光电科技有限公司 一种偏光片的制备方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004013005A (ja) * 2002-06-10 2004-01-15 Fuji Photo Film Co Ltd 偏光膜の製造方法
CN112248611A (zh) * 2020-10-12 2021-01-22 深圳市盛波光电科技有限公司 一种偏光片的制备方法

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