WO2022107376A1 - 偏光膜および偏光膜の製造方法 - Google Patents

偏光膜および偏光膜の製造方法 Download PDF

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Publication number
WO2022107376A1
WO2022107376A1 PCT/JP2021/023982 JP2021023982W WO2022107376A1 WO 2022107376 A1 WO2022107376 A1 WO 2022107376A1 JP 2021023982 W JP2021023982 W JP 2021023982W WO 2022107376 A1 WO2022107376 A1 WO 2022107376A1
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Prior art keywords
polarizing film
layer
film
resin
water
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PCT/JP2021/023982
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English (en)
French (fr)
Japanese (ja)
Inventor
理 小島
拓弥 南原
周作 後藤
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日東電工株式会社
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Priority to KR1020237012544A priority Critical patent/KR20230107792A/ko
Priority to CN202180078041.0A priority patent/CN116670547A/zh
Publication of WO2022107376A1 publication Critical patent/WO2022107376A1/ja

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    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/003—Light absorbing elements
    • 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

Definitions

  • the present invention relates to a polarizing film and a method for manufacturing a polarizing film.
  • a liquid crystal display device which is a typical image display device, has polarizing films arranged on both sides of a liquid crystal cell due to its image forming method.
  • a display (OLED) equipped with an organic electroluminescence (EL) panel and a display (QLED) using a display panel using an inorganic light emitting material such as a quantum dot have been proposed.
  • These panels have a highly reflective metal layer, and are liable to cause problems such as external light reflection and background reflection. Therefore, it is known to prevent these problems by providing a circular polarizing plate having a polarizing film and a ⁇ / 4 plate on the visual recognition side.
  • a method for producing a polarizing film for example, a method has been proposed in which a laminate having a resin base material and a polyvinyl alcohol (PVA) -based resin layer is stretched and then dyed to obtain a polarizing film on the resin base material.
  • PVA polyvinyl alcohol
  • Patent Document 1 Since such a method can obtain a thin polarizing film, it is attracting attention as it can contribute to the thinning of image display devices in recent years. However, the thin polarizing film has a poor appearance and may not have sufficient display characteristics when used in an image display device.
  • the present invention has been made to solve the above problems, and a main object thereof is to provide a polarizing film which is excellent in appearance and can contribute to improvement of display characteristics of an image display device.
  • a polarizing film is provided.
  • This polarizing film is composed of a resin film containing iodine, has a thickness of 7 ⁇ m or less, and has a reflectance Rc of light having a wavelength of 400 nm in the absorption axis direction with respect to a reflectance Rc 680 of light having a wavelength of 680 nm in the absorption axis direction on the surface.
  • the ratio of 400 (Rc 400 / Rc 680 ) is greater than 1.
  • the surface Rc 680 is 5% or less.
  • the surface Rc 400 is 4.8% or higher.
  • the polarizing film has a gradient distribution region at the end on the front surface side, in which the amount of iodine increases from the front surface to the back surface. In one embodiment, in the polarizing film, the amount of iodine on the front surface side is smaller than the amount of iodine on the back surface side. In one embodiment, the polarizing film has a simple substance transmittance of 42.0% or more and a degree of polarization of 99.98% or more. According to another aspect of the present invention, there is provided a method for manufacturing the above-mentioned polarizing film. This production method comprises washing the surface of a resin film containing iodine and having a water content of 15% by weight or less with water.
  • the iodine concentration of the resin film is 5% by weight or more.
  • the resin film is a resin layer formed on a resin substrate.
  • the manufacturing method comprises stretching the resin layer in water at 67 ° C. or lower.
  • the manufacturing method comprises heating the resin layer with a heating roll.
  • a polarizing plate is provided. The polarizing plate has the polarizing film and a protective layer or a retardation layer arranged on at least one side of the polarizing film.
  • a polarizing film having an excellent appearance by controlling the reflection characteristics of the surface. Further, such a polarizing film can contribute to the improvement of the display characteristics of the image display device.
  • Refractive index (nx, ny, nz) "Nx" is the refractive index in the direction in which the refractive index in the plane is maximized (that is, the direction of the slow phase axis), and "ny” is the direction orthogonal to the slow phase axis in the plane (that is, the direction of the phase advance axis). Is the refractive index of, and "nz” is the refractive index in the thickness direction.
  • In-plane phase difference (Re) “Re ( ⁇ )” is an in-plane phase difference measured with light having a wavelength of ⁇ nm at 23 ° C.
  • Re (550) is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C.
  • Phase difference in the thickness direction (Rth) is a phase difference in the thickness direction measured with light having a wavelength of ⁇ nm at 23 ° C.
  • Rth (550) is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C.
  • FIG. 1 is a schematic cross-sectional view of a polarizing film according to one embodiment of the present invention.
  • hatching is omitted in the cross section of the polarizing film in order to make the figure easier to see.
  • the polarizing film 10 has a first main surface (front surface) 10a and a second main surface (back surface) 10b.
  • the polarizing film 10 has an inclined distribution region in which the amount of iodine increases from the front surface 10a toward the back surface 10b at the end portion on the front surface 10a side.
  • the polarizing film 10 is made of a resin film containing iodine.
  • a resin film for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film is used.
  • PVA polyvinyl alcohol
  • the thickness of the polarizing film 10 is 7 ⁇ m or less, preferably 6 ⁇ m or less. A polarizing film having such a thickness tends to have a high iodine concentration. On the other hand, the thickness of the polarizing film is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more.
  • the polarizing film 10 preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm.
  • the simple substance transmittance (Ts) of the polarizing film 10 is preferably 41.0% or more, more preferably 42.0% or more, and further preferably 42.5% or more. On the other hand, the simple substance transmittance of the polarizing film 10 is, for example, 44.2% or less.
  • the degree of polarization (P) of the polarizing film 10 is preferably 99.95% or more, more preferably 99.98% or more, and further preferably 99.99% or more. On the other hand, the degree of polarization of the polarizing film 10 is, for example, 99.996% or less.
  • the simple substance transmittance is typically a Y value measured by using an ultraviolet-visible spectrophotometer and corrected for luminosity factor.
  • the degree of polarization is typically obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured by using an ultraviolet-visible spectrophotometer and corrected for luminosity factor.
  • Degree of polarization (%) ⁇ (Tp-Tc) / (Tp + Tc) ⁇ 1/2 ⁇ 100
  • the ratio (Rc 400 / Rc 680 ) of the reflectance Rc 400 of the light having a wavelength of 400 nm in the absorption axis direction to the reflectance Rc 680 of the light having a wavelength of 680 nm in the absorption axis direction of the surface 10a of the polarizing film 10 exceeds 1. It is preferably 1.3 or more, and more preferably 1.5 or more. By satisfying such a relationship, the reflected hue is well controlled and the appearance can be excellent. Specifically, redness is suppressed and the appearance can be excellent. As a result, for example, an image display device having excellent visibility can be provided.
  • the polarizing film 10 may be arranged so that the surface 10a thereof is on the viewing side of the image display device, or may be arranged so as to be on the side opposite to the viewing side. Get excellent.
  • the surface 10a of the polarizing film 10 so as to be on the visual side of the image display device, the appearance and display characteristics can be extremely excellent.
  • the Rc 400 / Rc 680 of the surface 10a of the polarizing film 10 is, for example, 2 or less.
  • the Rc 400 of the surface 10a of the polarizing film 10 is, for example, 4.8% or more, preferably 4.9% or more, more preferably 5% or more, and further preferably 5.3% or more.
  • the Rc 400 of the surface 10a of the polarizing film 10 is, for example, 6% or less.
  • the Rc 680 of the surface 10a of the polarizing film 10 is, for example, 5% or less, preferably 4.9% or less, more preferably 4.5% or less, and further preferably 4% or less.
  • the Rc 680 of the surface 10a of the polarizing film 10 is, for example, 3% or more.
  • the reflectance Rp 400 of light having a wavelength of 400 nm in the transmission axis direction of the surface 10a of the polarizing film 10 is, for example, 4.5% to 5%.
  • the reflectance Rp 680 of light having a wavelength of 680 nm in the transmission axis direction of the surface 10a of the polarizing film 10 is, for example, 4.3% to 4.8%.
  • Each of the above Rc and Rp is the ratio of the reflected light intensity to the incident light intensity when light is incident on the surface of the polarizing film (resin film) at a predetermined angle and the reflected light in the absorption axis direction and the transmission axis direction is detected. Is.
  • the amount of iodine on the front surface 10a side is smaller than the amount of iodine on the back surface 10b side.
  • the polarizing film 10 has a first region 11 and a second region 12 having different iodine distribution states in this order from the surface side.
  • the first region 11 is a gradient distribution region in which the amount of iodine increases from the front surface 10a to the back surface 10b.
  • Iodine is uniformly distributed in the second region 12.
  • "uniformity" means that, for example, the intensity derived from iodine (for example, iodine ion) detected by analysis is in the range of -20% to + 20% from the average value.
  • the thickness of the first region 11 is preferably 2% or more and 50% or less, and more preferably 10% or more and 40% or less of the thickness of the polarizing film 10.
  • the thickness of the first region 11 may be 20% or more of the thickness of the polarizing film 10.
  • the thickness of the first region 11 is preferably 100 nm or more and 2.7 ⁇ m or less, and more preferably 500 nm or more and 2 ⁇ m or less.
  • the thickness of the first region 11 may be 1 ⁇ m or more. According to such a range, for example, excellent optical characteristics (the above-mentioned simple substance transmittance and degree of polarization) and excellent appearance can be achieved.
  • the polarizing film may have a first region, a second region, and a third region having different iodine distribution states in this order from the surface side.
  • the polarizing film has a first region in which the amount of iodine increases from the front surface to the back surface, a second region in which iodine is uniformly distributed, and a third region in which the amount of iodine decreases from the front surface side to the back surface. It may have an area.
  • the polarizing film is obtained by washing the surface of a resin film containing iodine and having a predetermined water content with water.
  • the water content (before washing with water) of the resin film is 15% by weight or less, preferably 12% by weight or less, more preferably 9% by weight or less, and further preferably 6% by weight or less.
  • the water content of the resin film is, for example, 3% by weight or more.
  • the iodine concentration of the resin film is, for example, 5% by weight or more, 5.5% by weight or more, or 6% by weight or more.
  • the iodine concentration of the resin film is, for example, 8% by weight or less.
  • the thickness of the resin film is, for example, 7 ⁇ m or less, and may be 6 ⁇ m or less.
  • the thickness of the resin film is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more. It is one of the features of the present invention that an excellent appearance can be achieved in such an iodine concentration and thickness.
  • Resin film For the resin film having the above-mentioned predetermined water content, for example, a resin layer (typically, a polyvinyl alcohol-based resin layer) is formed on a resin base material to prepare a laminated body, and the laminated body (resin layer) is formed. ) Is stretched and stained with iodine (for example, dyed by adsorption of iodine), and then the laminate (resin layer) is dried.
  • iodine for example, dyed by adsorption of iodine
  • a PVA-based resin layer containing a polyvinyl alcohol (PVA) -based resin and a halide is formed on a thermoplastic resin base material (for example, a long shape) to form the laminated body.
  • a coating liquid containing a PVA-based resin and a halide is applied onto a thermoplastic resin base material and dried to prepare a laminate.
  • the thickness of the thermoplastic resin base material is preferably 20 ⁇ m to 300 ⁇ m, and 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 the later-described underwater stretching, it takes time for the thermoplastic resin base material to absorb water, and there is a possibility that an excessive load is 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 the water can act as a plasticizer to plasticize. As a result, the stretching stress can be significantly reduced and the drawing can be performed at 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. With such a water absorption rate, it is possible to prevent problems such as deterioration of the quality of the obtained polarizing film due to a significant decrease in the dimensional stability of the thermoplastic resin base material during production.
  • thermoplastic resin base material from breaking or the PVA-based resin layer from peeling off during stretching in water.
  • the water absorption rate of the thermoplastic resin base material can be adjusted, for example, by introducing a modifying group into the constituent material.
  • the water absorption rate is a value obtained 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 lower, still more preferably 90 ° C. or lower.
  • the Tg of the thermoplastic resin base material is preferably 60 ° C. or higher.
  • the thermoplastic resin base material when the coating liquid is applied and dried, the thermoplastic resin base material is prevented from being deformed (for example, unevenness, tarmi, wrinkles, etc.), and the lamination is good. You can make a body. Further, the stretching of the resin layer can be satisfactorily performed at a suitable temperature (for example, about 60 ° C.).
  • the Tg of the thermoplastic resin substrate can be adjusted, for example, by heating with a crystallization material that introduces a modifying group into the constituent material.
  • the glass transition temperature (Tg) is a value obtained according to JIS K7121.
  • thermoplastic resin can be adopted as the constituent material of the thermoplastic resin base material.
  • the thermoplastic resin 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-based resin and amorphous polyethylene terephthalate-based resin are preferable.
  • an amorphous (non-crystallized) polyethylene terephthalate resin is preferably used.
  • an amorphous (difficult to crystallize) polyethylene terephthalate resin is particularly preferably used.
  • Specific examples of the amorphous polyethylene terephthalate resin include a copolymer further containing isophthalic acid and / or a cyclohexanedicarboxylic acid as a dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol or diethylene glycol as a glycol.
  • a polyethylene terephthalate resin having an isophthalic acid unit is preferably used. This is because the stretchability is extremely excellent and crystallization during stretching can be suppressed. It is considered that this is because the introduction of the isophthalic acid unit gives a large bending to the backbone.
  • the polyethylene terephthalate resin has a terephthalic acid unit and an ethylene glycol unit.
  • the content ratio 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 having extremely excellent stretchability can be obtained.
  • the content ratio of the isophthalic acid unit is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all repeating units. This is because the crystallinity can be satisfactorily increased in the drying described later.
  • the thermoplastic resin base material may be stretched in advance (for example, before forming the PVA-based resin layer).
  • the elongated thermoplastic resin substrate is laterally stretched.
  • the lateral direction is preferably a direction orthogonal to the stretching direction of the laminate described later.
  • “orthogonal” includes a case where it is substantially orthogonal.
  • substantially orthogonal includes the case of 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 draw ratio of the thermoplastic resin base material is preferably 1.5 to 3.0 times. Any suitable method can be adopted as the method for stretching the thermoplastic resin base material. Specifically, it may be fixed-end stretching or free-end stretching. The stretching method may be a dry method or a wet method. Stretching may be performed in one step or in multiple steps. When performed in multiple stages, the draw ratio is the product of the draw ratios in each stage.
  • the coating liquid is typically a solution in which a PVA-based resin and a halide are dissolved in a solvent.
  • the solvent include water, dimethyl sulfoxide, 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 preferable.
  • the content of the PVA-based resin in the coating liquid is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. According to such a range, it is possible to form a uniform coating film in close contact with the thermoplastic resin base material.
  • the content 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-based resin.
  • Examples of the PVA-based resin include polyvinyl alcohol and ethylene-vinyl alcohol copolymers.
  • Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
  • the ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer.
  • the saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. Is.
  • a PVA-based resin having such a saponification degree a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.
  • the degree of saponification can be determined according to JIS K 6726-1994.
  • the average degree of polymerization of the PVA-based resin is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300.
  • the average degree of polymerization can be determined according to JIS K 6726-1994.
  • any suitable halide can be adopted.
  • iodides such as potassium iodide, sodium iodide and lithium iodide, and chlorides such as sodium chloride.
  • potassium iodide is preferable.
  • a polarizing film having excellent optical characteristics can be obtained. Specifically, the crystallization of the PVA-based resin after the aerial auxiliary stretching described later is promoted, and in the subsequent wet treatment (for example, staining described later, stretching in water), the orientation of the polyvinyl alcohol molecule is disturbed and the orientation is lowered. Is suppressed, and a polarizing film having excellent optical characteristics can be obtained.
  • the halide In the preparation of the coating liquid, it is preferable to add 5 parts by weight to 20 parts by weight of the halide with respect to 100 parts by weight of the PVA-based resin, and more preferably 10 parts by weight to 15 parts by weight.
  • the content of the halide in the obtained PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight, and more preferably 10 parts by weight to 15 parts by weight with respect to 100 parts by weight of the PVA-based resin. Is. If the amount of the halide with respect to the PVA-based resin is large, for example, the halide may bleed out and the obtained polarizing film may become cloudy.
  • Additives may be added to the coating liquid.
  • the additive include a plasticizer and a surfactant.
  • the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin.
  • the surfactant include nonionic surfactants. These are used, for example, for the purpose of improving the uniformity, dyeability, and stretchability of the obtained PVA-based resin layer.
  • Examples of the coating method of the coating liquid include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife coating method (comma coating method, etc.). Be done.
  • 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, and 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 surface-treated (for example, corona treatment or the like), or the easy-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-based resin layer can be improved.
  • the stretching is preferably performed by stretching the laminate in water after dry stretching (auxiliary stretching in the air).
  • auxiliary stretching it is possible to stretch while suppressing the crystallization of the thermoplastic resin base material, and it solves the problem that the stretchability is lowered due to excessive crystallization of the thermoplastic resin base material in boric acid water stretching.
  • the laminate can be stretched at a higher magnification. Further, when the thermoplastic resin base material is used, since the coating temperature can be set low, there may be a problem that the crystallization of the PVA-based resin is relatively low and sufficient optical characteristics cannot be obtained. On the other hand, by introducing the auxiliary stretching, the crystallinity of the PVA-based resin can be enhanced even when the thermoplastic resin is used.
  • the method of aerial auxiliary stretching may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). ..
  • free-end stretching is adopted.
  • a heating roll stretching method is adopted in which the laminated body is conveyed in the longitudinal direction thereof and is stretched by the difference in peripheral speed between the heating rolls.
  • the aerial auxiliary stretching includes a zone stretching step and a heating roll stretching step in a thermal space (zone).
  • the order of the zone stretching step and the heating roll stretching step is not limited, but for example, the zone stretching step and the heating roll stretching step are performed in this order.
  • the film in the tenter stretching machine, is stretched by grasping the end portion of the film and widening the distance between the tenters in the flow direction (the widening of the distance between the tenters is the stretching ratio).
  • the distance of the tenter in the width direction perpendicular to the flow direction
  • the draw ratio of the aerial auxiliary stretch is preferably 2.0 to 3.5 times.
  • the aerial auxiliary stretching may be performed in one step or in multiple steps. When performed in multiple stages, the draw ratio is the product of the draw ratios in each stage.
  • the stretching direction in the aerial auxiliary stretching is preferably substantially the same as the stretching direction in the underwater stretching described later.
  • the stretching temperature of the aerial auxiliary stretching is set to an arbitrary appropriate value depending on, for example, the thermoplastic resin base material used, the stretching method, and the like.
  • the stretching temperature is preferably Tg + 10 ° C. or higher, more preferably Tg + 10 ° C. or higher, and even more preferably Tg + 15 ° C. or higher, preferably equal to or higher than the glass transition temperature (Tg) of the thermoplastic resin substrate.
  • the upper limit of the stretching temperature is preferably 170 ° C.
  • the underwater stretching is typically performed by immersing the laminate in a stretching bath.
  • the thermoplastic resin base material or 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 can be crystallized. It can be stretched at a high magnification while suppressing it. As a result, a polarizing film having excellent optical characteristics can be obtained.
  • the method of underwater stretching may be fixed-end stretching or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds).
  • free-end stretching is adopted.
  • the stretching of the laminate may be carried out in one step or in multiple steps. In the case of performing in multiple stages, the draw ratio of the laminated body described later is the product of the draw ratios of each stage.
  • the underwater stretching is preferably carried out by immersing the laminate in a boric acid aqueous solution (boric acid water stretching).
  • boric acid aqueous solution as the stretching bath, it is possible to impart rigidity to withstand the tension applied during stretching and water resistance that does not dissolve in water to the PVA-based resin layer.
  • boric acid can generate a tetrahydroxyboric acid anion in an aqueous solution and crosslink with a PVA-based resin by hydrogen bonding.
  • the PVA-based resin layer can be imparted with rigidity and water resistance, can be stretched satisfactorily, and a polarizing film having excellent optical characteristics can be obtained.
  • the boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate 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 further preferably 3 parts by weight to 5 parts by weight with respect to 100 parts by weight of water. Is.
  • the boric acid concentration is preferably 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film having higher characteristics can be produced.
  • an aqueous solution obtained by dissolving a boron compound such as borax, glioxal, glutaraldehyde or the like in a solvent can also be used.
  • iodide is added to the above stretching bath (boric acid aqueous solution).
  • iodide By blending iodide, the elution of iodine adsorbed on the PVA-based resin layer can be suppressed.
  • iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide.
  • the concentration of iodide is preferably 0.05 parts by weight to 15 parts by weight, and more preferably 0.5 parts by weight to 8 parts by weight with respect to 100 parts by weight of water.
  • the stretching temperature (liquid temperature of the stretching bath) is preferably 40 ° C. or higher, more preferably 60 ° C. or higher. At such a temperature, the PVA-based resin layer can be stretched at a high magnification while suppressing dissolution.
  • 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., it may not be stretched well even in consideration of the plasticization of the thermoplastic resin base material by water.
  • the stretching temperature is, for example, 70 ° C. or lower, preferably 67 ° C. or lower, and more preferably 65 ° C.
  • the immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.
  • the stretching ratio by stretching in water is preferably 1.5 times or more, more preferably 3.0 times or more.
  • the total draw ratio of the laminated body is preferably 5.0 times or more, more preferably 5.5 times or more with respect to the original length of the laminated body. Yes, more preferably 6.0 times or more.
  • Such a high draw ratio can be achieved by adopting an underwater stretching method (boric acid underwater stretching).
  • the above dyeing is typically performed by adsorbing iodine on a PVA-based resin layer.
  • the iodine adsorption method include a method of immersing a PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA-based resin layer, and a method of applying the dyeing solution to the PVA-based resin layer.
  • a method of immersing the laminate in a dyeing solution (staining bath) is preferable. This is because iodine can be adsorbed well.
  • the stain solution is preferably an aqueous iodine solution.
  • the blending amount of iodine is preferably 0.05 part by weight to 0.5 part by weight with respect to 100 parts by weight of water.
  • iodide is added to the aqueous iodine solution.
  • Specific examples of iodide are as described above.
  • potassium iodide is used.
  • the blending amount of the iodide is preferably 0.1 part by weight to 10 parts by weight, and more preferably 0.3 part by weight to 5 parts by weight with respect to 100 parts by weight of water.
  • the liquid temperature at the time of dyeing the dyeing liquid is preferably 20 ° C.
  • the immersion time is preferably 5 seconds to 5 minutes, more preferably 30 seconds to 90 seconds in order to secure the transmittance of the PVA-based resin layer.
  • the dyeing conditions are set so that, for example, the single transmittance of the finally obtained polarizing film is 42.0% or more and the degree of polarization is 99.98% or more. can do.
  • a dyeing condition for example, the ratio of the content of iodine and potassium iodide in the iodine aqueous solution which is a dyeing solution is preferably 1: 5 to 1:20, and more preferably 1: 5 to 1. : 10.
  • boric acid When continuous dyeing is performed after a treatment in which the laminate is immersed in a treatment bath containing boric acid (for example, an insolubilization treatment described later), boric acid is mixed in the dyeing bath and the boric acid concentration in the dyeing bath changes. Dyeability may become unstable.
  • the boric acid concentration in the dyeing bath is adjusted to be preferably 4 parts by weight or less, more preferably 2 parts by weight or less with respect to 100 parts by weight of water. Will be done.
  • the boric acid concentration in the dyeing bath is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, and further preferably 0.5 part by weight with respect to 100 parts by weight of water. That is all.
  • dyeing is performed using a dyeing bath containing boric acid in advance.
  • the rate of change in boric acid concentration when boric acid is mixed in the dyeing bath can be reduced.
  • the amount of boric acid to be blended in the dyeing bath in advance is preferably 0.1 part by weight to 2 parts by weight, more preferably with respect to 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 water stretching and staining.
  • the insolubilization treatment is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution.
  • concentration of the boric acid aqueous solution in the insolubilization treatment is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water.
  • the temperature of the insolubilization treatment liquid temperature of the boric acid aqueous solution
  • the cross-linking treatment is typically performed by immersing a PVA-based resin layer in an aqueous boric acid solution.
  • the concentration of the boric acid aqueous solution in the crosslinking treatment is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. It is preferable to add iodide to the boric acid aqueous solution.
  • the elution of iodine adsorbed on the PVA-based resin layer can be suppressed.
  • Specific examples of iodide are as described above.
  • the blending amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water.
  • the temperature of the crosslinking treatment liquid temperature of the boric acid aqueous solution, preferably 20 ° C to 50 ° C.
  • the washing is typically performed by immersing the PVA-based resin layer in an aqueous solution of potassium iodide.
  • the drying can be carried out under any suitable method and conditions as long as a resin film having the above-mentioned predetermined moisture content can be obtained. Specifically, it may be performed by heating the entire zone (zone heating method) or by heating the transport roll (heating roll method). A heating roll method is preferably adopted, and more preferably both are adopted. By using the heating roll, it is possible to efficiently suppress the heating curl of the laminated body and produce a polarizing film having excellent quality. Specifically, by drying the laminated body along the heating roll, the crystallization of the thermoplastic resin base material can be efficiently promoted and the crystallinity can be increased, which is relatively low. Even at the drying temperature, the crystallinity of the thermoplastic resin substrate can be satisfactorily increased.
  • the rigidity of the thermoplastic resin base material is increased, and the PVA-based resin layer is in a state of being able to withstand shrinkage due to drying, and curling is suppressed. Further, by using the heating roll, the laminated body can be dried while being maintained 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 the optical characteristics can be improved. This is because the orientation of PVA and the PVA / iodine complex can be effectively enhanced.
  • the shrinkage rate of the laminate in the width direction due to drying is preferably 1% to 10%, more preferably 2% to 8%, still more preferably 4% to 6%.
  • the heating roll By using the heating roll, the laminated body can be continuously contracted in the width direction while being conveyed, and high productivity can be realized.
  • FIG. 2 is a schematic view showing an example of drying using a heating roll.
  • the laminate 200 is dried while being transported by the transport rolls R1 to R6 heated to a predetermined temperature and the 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 base material, and for example, one surface of the laminate 200 (for example, The transport rolls R1 to R6 may be arranged so as to continuously heat only the surface of the thermoplastic resin base material).
  • 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, and the like.
  • the temperature of the heating roll is preferably 60 ° C. to 120 ° C., more preferably 65 ° C. to 100 ° C., and even more preferably 70 ° C. to 80 ° C. According to such a temperature, the crystallinity of the thermoplastic resin can be increased to suppress curling, and the laminated body can be imparted with extremely excellent durability. In addition, the moisture content of the resin film can be satisfactorily achieved.
  • the temperature of the heating roll can be measured with a contact thermometer.
  • the number of transport rolls is usually 2 to 40, preferably 4 to 30.
  • 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 further preferably 1 to 10 seconds.
  • the heating roll may be provided in a heating furnace (for example, an oven) or in a normal production line (in a room temperature environment). Preferably, it is provided in a heating furnace provided with an air blowing means.
  • a heating furnace provided with an 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 hot air is preferably about 10 m / s to 30 m / s. The wind speed is the wind speed in the heating furnace and can be measured by a mini-vane type digital anemometer.
  • washing with water is performed, for example, by bringing water into contact with the surface of the resin film.
  • washing is performed by immersing the resin film in a water bath.
  • the back surface of the resin film is preferably protected by any suitable protective substrate.
  • the resin base material is used as the protective base material.
  • the resin film is immersed in a water bath without peeling the resin base material from the resin film (in the state of the above-mentioned laminated body).
  • the protective layer described below is used as the protective base material.
  • the resin base material is peeled off from the resin film to prepare a laminate of the protective layer and the resin film, and the laminate is immersed in a water bath.
  • the resin film may be long or single-wafered.
  • the temperature of the water bath is, for example, 20 ° C. or higher, preferably 25 ° C. or higher, more preferably 30 ° C. or higher, still more preferably 35 ° C. or higher, and particularly preferably 40 ° C. or higher. Is. With such a temperature, for example, a polarizing film satisfying the above reflectance can be produced in a short time.
  • the temperature of the water bath is preferably 60 ° C. or lower, more preferably 50 ° C. or lower. According to such a temperature, for example, the obtained polarizing film has excellent surface properties and can maintain excellent optical properties.
  • the immersion time (contact time) in the water bath is set according to, for example, the above temperature, the thickness of the resin film, and the like.
  • the immersion time in the water bath is preferably 15 seconds to 5 minutes, more preferably 30 seconds to 3 minutes.
  • the water bath (water to be contacted) may contain additives such as boric acid.
  • the polarizing film After washing with water, the polarizing film can be subjected to a drying treatment.
  • the drying temperature is, for example, 30 ° C to 60 ° C.
  • the drying time is, for example, 15 seconds to 3 minutes.
  • the polarizing plate according to one embodiment of the present invention has the above-mentioned polarizing film and a protective layer or a retardation layer arranged on at least one side of the polarizing film.
  • FIG. 3 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate according to the first embodiment of the present invention.
  • the polarizing plate (polarizing plate with a retardation layer) 100 has a polarizing film 10, a protective layer 20, a retardation layer 30, and an adhesive layer 40 in this order.
  • the protective layer 20 is arranged only on the back surface 10b side of the polarizing film 10, and the protective layer is not arranged on the front surface 10a side (for example, the visual recognition side), but practically, the polarizing film 10 is arranged.
  • the surface 10a is protected by any suitable protective material (not shown).
  • a protective material is laminated on 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.
  • FIG. 4 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate according to the second embodiment of the present invention.
  • the polarizing plate (polarizing plate with a retardation layer) 110 includes a protective layer 20 arranged on the back surface 10b side of the polarizing film 10, a polarizing film 10, a retardation layer 30 arranged on the front surface 10a side of the polarizing film 10, and an adhesive.
  • the layer 40 is provided in this order from the visual recognition side.
  • the present embodiment differs from the first embodiment in that the retardation layer 30 can function as a protective layer for the polarizing film 10 and the retardation layer 30 is arranged on the surface 10a side of the polarizing film 10.
  • the polarizing plate may further have other functional layers.
  • the types, characteristics, numbers, combinations, arrangements, and the like of the functional layers that the polarizing plate may have can be appropriately set according to the purpose.
  • the polarizing plate may further have 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 have another retardation layer.
  • the optical characteristics for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient
  • thickness, arrangement, and the like of the other retardation layers can be appropriately set according to the purpose.
  • another retardation layer typically, a layer that imparts a (elliptical) circular polarization function
  • a super A layer that imparts a high phase difference may be provided on the visual recognition side of the polarizing film 10.
  • Each member constituting the polarizing plate can be laminated via an arbitrary appropriate adhesive layer (not shown).
  • the adhesive layer include an adhesive layer and an adhesive layer.
  • the retardation layer 30 may be attached to the polarizing film 10 or the protective layer 20 via an adhesive layer (preferably using an active energy ray-curable adhesive), or an adhesive. It may be bonded to the polarizing film 10 or the protective layer 20 via the 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 film (separator) is practically attached to the surface of the adhesive layer 40.
  • the release film can be tacked temporarily until the polarizing plate is put into use.
  • the release film for example, the pressure-sensitive adhesive layer can be protected and a roll of the polarizing plate can be formed.
  • the polarizing plate may be long or single-lobed.
  • the term "long” refers to an elongated shape having a length sufficiently long with respect to the width, for example, an elongated shape having a length of 10 times or more, preferably 20 times or more with respect to the width.
  • the long polarizing plate can be wound in a roll shape.
  • the protective layer 20 can be formed of any suitable film that can be used as a protective layer for the polarizing film.
  • suitable film include cellulosic resins such as triacetylcellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, and polysulfones.
  • TAC triacetylcellulose
  • the above polarizing plate is typically arranged on the visual side of the image display device. Therefore, even if the protective layer 20 is subjected to surface treatment such as hard coat (HC) treatment, antireflection treatment, anti-sticking treatment, anti-glare treatment, etc., if necessary (for example, in the form shown in FIG. 4). good.
  • surface treatment such as hard coat (HC) treatment, antireflection treatment, anti-sticking treatment, anti-glare treatment, etc.
  • the thickness of the protective layer 20 is preferably 5 ⁇ m to 80 ⁇ m, more preferably 10 ⁇ m to 40 ⁇ m, and even more preferably 10 ⁇ m to 30 ⁇ m. When the surface treatment is applied, the thickness of the protective layer 20 is the thickness including the thickness of the surface treatment layer.
  • the protective layer arranged between the polarizing film 10 and the retardation layer 30 is preferably optically isotropic in one embodiment.
  • 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.
  • the resin substrate can be used as a protective layer for a polarizing film.
  • the manufacturing process can be reduced by using the resin base material as it is as the protective layer.
  • phase difference layer As the phase difference layer 30, any suitable configuration can be adopted.
  • the alignment solidification layer (liquid crystal alignment solidification layer) of the liquid crystal compound is used as the retardation layer 30.
  • the difference between nx and ny of the obtained retardation layer can be significantly increased as compared with the non-liquid crystal material, so that the thickness of the retardation layer for obtaining a desired in-plane retardation can be obtained.
  • the term "aligned solidified layer” refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and the oriented state is fixed.
  • the "oriented solidified layer” is a concept including an oriented cured layer obtained by curing a liquid crystal monomer as described later.
  • the rod-shaped liquid crystal compounds are typically oriented in a state of being aligned in the slow axis direction of the retardation layer (homogeneous orientation).
  • the thickness of the retardation layer is preferably 8 ⁇ m or less, and more preferably 5 ⁇ m or less, although it depends on the structure (whether it is a single layer or has a laminated structure). On the other hand, the thickness of the retardation layer is, for example, 1 ⁇ m or more.
  • the "thickness of the retardation layer” means the total thickness of each retardation layer. Specifically, the "thickness of the retardation layer” does not include the thickness of the adhesive layer.
  • the surface of a predetermined base material is subjected to an orientation treatment, and a coating liquid containing a liquid crystal compound is applied to the surface to orient the liquid crystal compound in a direction corresponding to the alignment treatment. It can be formed by fixing the orientation state.
  • the orientation treatment any appropriate orientation treatment can be adopted. Specific examples thereof include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of the mechanical orientation treatment include a rubbing treatment and a stretching treatment. Specific examples of the physical orientation treatment include magnetic field orientation treatment and electric field orientation treatment. Specific examples of the chemical alignment treatment include an orthorhombic vapor deposition method and a photoalignment treatment.
  • any appropriate conditions may be adopted depending on the purpose.
  • the orientation of the liquid crystal compound is performed by treating at a temperature indicating the liquid crystal phase according to the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes a liquid crystal state, and the liquid crystal compound is oriented according to the orientation treatment direction of the surface of the substrate.
  • the orientation state is fixed by cooling the liquid crystal compound oriented as described above.
  • the orientation state is fixed by subjecting the liquid crystal compound oriented as described above to a polymerization treatment or a crosslinking treatment.
  • liquid crystal compound and details of the method for forming the oriented solidified layer are described in Japanese Patent Application Laid-Open No. 2006-163343. The description of this publication is incorporated herein by reference.
  • the retardation layer 30 can function as, for example, a ⁇ / 4 plate.
  • the Re (550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and further preferably 110 nm to 160 nm.
  • the thickness of the retardation layer can be adjusted to obtain the desired in-plane retardation of the ⁇ / 4 plate.
  • the thickness thereof is, for example, 1.0 ⁇ m to 2.5 ⁇ m.
  • the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing film is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably 44. ° to 46 °.
  • the retardation layer preferably exhibits a reverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light.
  • the retardation layer 30 has, for example, a two-layer laminated structure in which the H layer and the Q layer are arranged in order from the polarizing film 10 side.
  • the H layer can typically function as a ⁇ / 2 plate
  • the Q layer can typically function as a ⁇ / 4 plate.
  • the Re (550) of the H layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, still more preferably 230 nm to 280 nm; and the Re (550) of the Q layer is preferably.
  • the thickness of the H layer can be adjusted to obtain the desired in-plane phase difference of the ⁇ / 2 plate.
  • the thickness thereof is, for example, 2.0 ⁇ m to 4.0 ⁇ m.
  • the thickness of the Q layer can be adjusted to obtain the desired in-plane phase difference of the ⁇ / 4 plate.
  • the thickness thereof is, for example, 1.0 ⁇ m to 2.5 ⁇ m.
  • the angle formed by the slow phase axis of the H layer and the absorption axis of the polarizing film is preferably 10 ° to 20 °, more preferably 12 ° to 18 °, and even more preferably 12 °.
  • the angle between the slow axis of the Q layer and the absorption axis of the polarizing film is preferably 70 ° to 80 °, more preferably 72 ° to 78 °, and even more preferably 72 °. It is ⁇ 76 °.
  • each layer for example, H layer and Q layer
  • the Nz coefficient of the retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3.
  • the retardation layer is preferably a liquid crystal oriented solidifying layer.
  • the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) in which the liquid crystal phase is a nematic phase.
  • a liquid crystal compound for example, a liquid crystal polymer or a liquid crystal monomer can be used.
  • the liquid crystal expression mechanism of the liquid crystal compound may be either lyotropic or thermotropic.
  • the liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.
  • the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the orientation state of the liquid crystal monomer can be fixed by polymerizing or cross-linking (that is, curing) the liquid crystal monomer. After the liquid crystal monomers are oriented, for example, the liquid crystal monomers are polymerized or crosslinked with each other, whereby the oriented state can be fixed.
  • the polymer is formed by polymerization, and the three-dimensional network structure is formed by crosslinking, but these are non-liquid crystal.
  • the formed retardation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change peculiar to a liquid crystal compound, for example.
  • the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.
  • the temperature range in which the liquid crystal monomer exhibits liquid crystal properties differs depending on the type. Specifically, the temperature range is preferably 40 ° C. to 120 ° C., more preferably 50 ° C. to 100 ° C., and most preferably 60 ° C. to 90 ° C.
  • any suitable liquid crystal monomer can be adopted as the liquid crystal monomer.
  • the polymerizable mesogen compounds described in Special Tables 2002-533742 WO00 / 37585
  • EP358208 US5211877
  • EP66137 US43884553
  • WO93 / 22397 EP0261712, DE19504224, DE4408171, and GB2280445
  • Specific examples of such a polymerizable mesogen compound include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767.
  • As the liquid crystal monomer a nematic liquid crystal monomer is preferable.
  • Adhesive Layer As the adhesive layer 40, any suitable configuration can be adopted. 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 the monomers forming the base resin of the pressure-sensitive adhesive, the blending amount of the cross-linking agent, the reaction temperature, the reaction time, etc., the pressure-sensitive adhesive having desired characteristics according to the purpose. Can be prepared.
  • the base resin of the pressure-sensitive adhesive may be used alone or in combination of two or more.
  • the base resin is preferably an acrylic resin (specifically, the pressure-sensitive adhesive layer is preferably composed of an acrylic pressure-sensitive adhesive).
  • the thickness of the pressure-sensitive adhesive layer is, for example, 10 ⁇ m to 20 ⁇ m.
  • Polarizing Plate A polarizing plate can be typically obtained by laminating various layers such as a retardation layer on a polarizing film after washing with water.
  • the resin base material of the laminate of the resin base material and the polarizing film after washing with water is used as it is as the protective layer 20, and the retardation layer 30 and the pressure-sensitive adhesive layer 40 are used on the resin base material.
  • the protective layer 20 is laminated on the resin film side of the laminate of the resin base material and the resin film, and the laminate obtained by peeling the resin base material from the resin film is washed with water to wash the protective layer 20 side. It can be obtained by sequentially laminating the retardation layer 30 and the pressure-sensitive adhesive layer 40.
  • the polarizing plate 100 is obtained by laminating the retardation layer 30 or the retardation layer 30 and the pressure-sensitive adhesive layer 40 on the laminate of the protective layer 20 and the resin film, and then washing with water. May be good.
  • the polarizing plate 110 shown in FIG. 4 is, for example, a laminate obtained by laminating a protective layer 20 on the resin film side of a laminate of the resin base material and the resin film and peeling the resin base material from the resin film. It can be obtained by washing with water and sequentially laminating the retardation layer 30 and the pressure-sensitive adhesive layer 40 on the polarizing film 10 side.
  • the thickness, the iodine concentration of the resin film, and the water content are values measured by the following measuring methods. Unless otherwise specified, "parts" and “%” in Examples and Comparative Examples are based on weight. 1. 1. The thickness of 10 ⁇ m or less was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name “JSM-7100F”). Thicknesses exceeding 10 ⁇ m were measured using a digital micrometer (manufactured by Anritsu, product name “KC-351C”). 2. 2. 2.
  • Moisture content of the resin film The amount of water contained in the resin film by drying the resin film alone (the resin film in a state of being peeled off from the resin substrate) at 120 ° C. for 2 hours and measuring the amount of weight change before and after drying. was calculated, and the water content was calculated.
  • thermoplastic resin base material an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 ⁇ m) having a long shape, a water absorption rate of 0.75%, and a Tg of about 75 ° C. was used.
  • One side of the resin substrate was corona-treated.
  • a PVA aqueous solution (coating liquid).
  • the 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, and a laminate was prepared.
  • the obtained laminate was stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching). Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C.
  • boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water
  • a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water
  • the total draw ratio is 5.5 in the vertical direction (longitudinal direction) between rolls having different peripheral speeds.
  • Uniaxial stretching was performed so as to double (stretching in water).
  • the laminate was immersed in a washing bath having a liquid temperature of 20 ° C.
  • 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 COP film is attached so as to be on the resin film side.
  • a cycloolefin resin (COP) film thinness 25 ⁇ m
  • the surface of a polyethylene terephthalate (PET) film was rubbed with a rubbing cloth and subjected to an orientation treatment.
  • the direction of the alignment treatment was set to be 15 ° when viewed from the visual recognition side with respect to the direction of the absorption axis of the polarizing film when the polarizing film was attached.
  • the liquid crystal coating liquid was applied to the alignment-treated surface with a bar coater, and the liquid crystal compound was oriented by heating and drying at 90 ° C. for 2 minutes.
  • the liquid crystal layer thus formed is irradiated with light of 1 mJ / cm 2 using a metal halide lamp to cure the liquid crystal layer, whereby a liquid crystal oriented solidified layer A (H layer) is formed on the PET film. did.
  • a liquid crystal oriented solidified layer B (Q layer) was formed.
  • Example 2 A polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that the laminate was washed with water by immersing the laminate in a water bath at 40 ° C. for 2 minutes.
  • Example 3 The laminate was immersed in a boric acid aqueous solution having a liquid temperature of 70 ° C. and stretched in water to prepare a resin film having a thickness of 5.4 ⁇ m, an iodine concentration of 6.6%, and a water content of 4.5%.
  • a polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that the mixture was washed with water by immersing it in a water bath at 25 ° C. for 5 minutes.
  • the polarizing plate B was not produced due to the surface texture (swelling) of the polarizing film after washing with water.
  • Example 4 The laminate was immersed in a boric acid aqueous solution having a liquid temperature of 67 ° C. and stretched in water to prepare a resin film having a thickness of 4.8 ⁇ m, an iodine concentration of 5.5%, and a water content of 4%.
  • a polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that the mixture was washed with water by immersing it in the water bath of 1 for 1 minute.
  • Example 5 The laminate was immersed in a boric acid aqueous solution having a liquid temperature of 67 ° C. and stretched in water to prepare a resin film having a thickness of 4.8 ⁇ m, an iodine concentration of 5.5%, and a water content of 4%.
  • a polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that the mixture was washed with water by immersing it in the water bath of No. 1 for 2 minutes.
  • Example 1 A polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that the resin film was not washed with water.
  • Example 3 A polarizing film and a polarizing plate were obtained in the same manner as in Example 3 except that the resin film was not washed with water.
  • Reference Example 2 A polarizing film and a polarizing plate were obtained in the same manner as in Reference Example 1 except that the laminate was not washed with water.
  • the incident angle of the light source was set to 5 °, and the measurement wavelength was set to 380 nm to 780 nm. 3. 3.
  • Surface properties The surface properties of the polarizing films of Examples and Comparative Examples (presence or absence of unevenness due to swelling of the resin film) were visually observed. (Evaluation criteria) Good: No unevenness is confirmed Defect: Unevenness is confirmed 4.
  • Polarizer hue (a * and b * ) The polarizing plates (circular polarizing plates) of Examples and Comparative Examples were laminated on an aluminum sheet, and the reflected hue was measured in SCE mode with a spectrophotometer (manufactured by Konica Minolta, cm-2600d).
  • the ionic strength of iodine in the thickness direction was measured for the polarizing films obtained in Example 1, Comparative Example 1 and Reference Example 2.
  • the measurement was performed using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) (manufactured by ION-TOF, product name: TOF-SIMS 5) and Bi 32+ as the primary ion .
  • TOF-SIMS time-of-flight secondary ion mass spectrometer
  • FIG. 5 graph in which the horizontal axis is converted into the thickness of the polarizing film
  • FIG. 5 it was confirmed that the polarizing film of Example 1 had a gradient distribution region in which the amount of iodine increased from the front surface to the back surface at the end portion on the front surface side.
  • the ionic strength of iodine on the vertical axis corresponds to the iodine concentration.
  • the polarizing film according to one embodiment of the present invention is suitably used for an image display device such as a liquid crystal display device, an organic EL display device, or an inorganic EL display device.
  • Polarizing film 10 Polarizing film 20 Protective layer 30 Phase difference layer 40 Adhesive layer 100 Polarizing plate 110 Polarizing plate

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PCT/JP2021/023982 2020-11-19 2021-06-24 偏光膜および偏光膜の製造方法 WO2022107376A1 (ja)

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Citations (6)

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WO2013111892A1 (ja) * 2012-01-23 2013-08-01 住友化学株式会社 偏光フィルムとその製造方法及び偏光板
JP2014102497A (ja) * 2012-10-22 2014-06-05 Nitto Denko Corp 偏光膜および偏光膜の製造方法
JP2014170223A (ja) * 2013-02-07 2014-09-18 Nitto Denko Corp 偏光膜を有する光学積層体
JP2016071349A (ja) * 2014-09-30 2016-05-09 住友化学株式会社 偏光性積層フィルム及び偏光板の製造方法
JP2018072711A (ja) * 2016-11-02 2018-05-10 日東電工株式会社 偏光板
JP2019053280A (ja) * 2017-09-13 2019-04-04 日東電工株式会社 偏光膜、偏光板、および偏光膜の製造方法

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JP2001343521A (ja) 2000-05-31 2001-12-14 Sumitomo Chem Co Ltd 偏光板及びその製造方法

Patent Citations (6)

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Publication number Priority date Publication date Assignee Title
WO2013111892A1 (ja) * 2012-01-23 2013-08-01 住友化学株式会社 偏光フィルムとその製造方法及び偏光板
JP2014102497A (ja) * 2012-10-22 2014-06-05 Nitto Denko Corp 偏光膜および偏光膜の製造方法
JP2014170223A (ja) * 2013-02-07 2014-09-18 Nitto Denko Corp 偏光膜を有する光学積層体
JP2016071349A (ja) * 2014-09-30 2016-05-09 住友化学株式会社 偏光性積層フィルム及び偏光板の製造方法
JP2018072711A (ja) * 2016-11-02 2018-05-10 日東電工株式会社 偏光板
JP2019053280A (ja) * 2017-09-13 2019-04-04 日東電工株式会社 偏光膜、偏光板、および偏光膜の製造方法

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