WO2018186243A1 - Polarizer production method - Google Patents

Polarizer production method Download PDF

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Publication number
WO2018186243A1
WO2018186243A1 PCT/JP2018/012567 JP2018012567W WO2018186243A1 WO 2018186243 A1 WO2018186243 A1 WO 2018186243A1 JP 2018012567 W JP2018012567 W JP 2018012567W WO 2018186243 A1 WO2018186243 A1 WO 2018186243A1
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WIPO (PCT)
Prior art keywords
polarizer
dyeing
weight
solution
iodide
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PCT/JP2018/012567
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French (fr)
Japanese (ja)
Inventor
聡司 三田
森　拓也
浩明 澤田
友斗 猿橋
池田　哲朗
Original Assignee
日東電工株式会社
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Application filed by 日東電工株式会社 filed Critical 日東電工株式会社
Priority to JP2019511176A priority Critical patent/JP6817420B2/en
Priority to KR1020197026493A priority patent/KR102263513B1/en
Priority to CN201880020660.2A priority patent/CN110462467B/en
Publication of WO2018186243A1 publication Critical patent/WO2018186243A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • 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
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/02—Chemical treatment or coating of shaped articles made of macromolecular substances with solvents, e.g. swelling agents
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements

Definitions

  • the present invention relates to a method for manufacturing a polarizer.
  • a polarizer is used in an image display device such as a liquid crystal display device.
  • a polarizer is typically manufactured by dyeing a polyvinyl alcohol (PVA) resin film with a dichroic substance such as iodine (for example, Patent Documents 1 and 2).
  • PVA polyvinyl alcohol
  • iodine for example, Patent Documents 1 and 2.
  • the thickness of the resin film is also thin, so that it may not be sufficiently dyed. Therefore, a method capable of dyeing a resin film more efficiently is demanded.
  • iodine is sublimated in the dyeing process and the iodine concentration in the dyeing solution decreases with time. This is particularly noticeable in dyeing solutions containing high concentrations of iodine. Furthermore, in the dyeing process, iodine is transferred to the PVA resin film, so that the iodine concentration in the dyeing solution is lowered. Therefore, in order to perform the dyeing process stably and continuously, it is necessary to appropriately adjust the iodine concentration in the dyeing solution.
  • the present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a method for producing a polarizer capable of dyeing a PVA resin film more efficiently.
  • the polarizer manufacturing method of the present invention includes a step of dyeing a polyvinyl alcohol-based resin film with a solution containing an oxidant for iodide and iodine ions.
  • This oxidizing agent is an ionic compound composed of a cation and an anion, and the standard electrode potential of either the anion or cation is larger than the standard electrode potential of iodine ion.
  • the standard electrode potential of the anion or cation is 0.55 V or more.
  • the iodide content in the solution is 1 to 40 parts by weight with respect to 100 parts by weight of the solvent.
  • the content of the oxidizing agent in the solution is 0.1 to 10 parts by weight with respect to 100 parts by weight of the solvent.
  • the molar ratio of the iodide to the oxidant is 2/1 to 50/1.
  • the oxidizing agent contains a trivalent iron ion as a cation.
  • the oxidizing agent is at least one selected from the group consisting of ferric sulfate, ferric chloride, and ferric nitrate.
  • the thickness of the polarizer obtained by the manufacturing method of the above-mentioned polarizer is 10 micrometers or less.
  • a PVA resin film can be dyed more efficiently.
  • the PVA resin film is dyed using a solution containing an oxidant for iodide and iodine ions.
  • iodine ions are oxidized in the solution by the oxidizing agent to form polyiodine ions (for example, I 3 ⁇ ions), and the content of polyiodine ions contained in the solution can be increased efficiently.
  • the PVA resin film can be dyed more efficiently.
  • the content of polyiodine ions can be increased without using solid iodine. Therefore, adverse effects on the environment and the human body due to iodine at the time of preparing the staining solution can be prevented.
  • the method for producing a polarizer of the present invention includes a step of dyeing a PVA resin film with a solution containing an oxidant for iodide and iodine ions (hereinafter also referred to as a dyeing solution).
  • This oxidizing agent is an ionic compound composed of a cation and an anion, and the standard electrode potential of either the anion or cation is larger than the standard electrode potential of iodine ion.
  • iodine ions can be oxidized to form polyiodine ions.
  • a polarizer can be manufactured by, for example, subjecting a PVA resin film to a swelling process, a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process.
  • Examples of the PVA resin forming the PVA resin film include polyvinyl alcohol and ethylene-vinyl alcohol copolymer.
  • Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
  • the ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer.
  • the saponification degree of the PVA resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.99 mol%, more preferably 99.0 mol% to 99.99 mol%. is there.
  • the degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizer having excellent durability can be obtained.
  • the average degree of polymerization of the PVA resin can be appropriately selected according to the purpose.
  • the average degree of polymerization is usually 1000 to 10,000, preferably 1200 to 4500, and more preferably 1500 to 4300.
  • the average degree of polymerization can be determined according to JIS K 6726-1994.
  • the thickness of the PVA resin film is not particularly limited, and can be set according to a desired thickness of the polarizer.
  • the thickness of the PVA resin film is, for example, 0.5 ⁇ m to 200 ⁇ m.
  • the dyeing solution used in the present invention can dye a PVA resin film very efficiently. Therefore, for example, even if a PVA-type resin film is less than 10 micrometers, it can dye
  • the PVA resin film may be a PVA resin layer formed on a substrate.
  • the laminated body of a base material and a resin layer can be obtained by the method of apply
  • Any appropriate resin substrate can be used as the substrate, and for example, a thermoplastic resin substrate can be used.
  • the polarizer can be produced, for example, by subjecting the PVA resin film to a swelling process, a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process.
  • a swelling process for example, by subjecting the PVA resin film to a swelling process, a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process.
  • Each process is performed at any appropriate timing.
  • any step other than the dyeing step may be omitted, a plurality of steps may be performed simultaneously, and each step may be performed a plurality of times.
  • each step will be described.
  • the swelling process is usually performed before the dyeing process.
  • the swelling process may be performed together with the dyeing process in the same immersion bath.
  • a swelling process is performed by immersing a PVA-type resin film in a swelling bath, for example.
  • Any appropriate liquid can be used as the swelling bath.
  • water such as distilled water or pure water is used.
  • the swelling bath may contain any appropriate other component other than water. Examples of other components include alcohols and other solvents, surfactants and other additives, and iodides.
  • Examples of the 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. Etc. Preferably, potassium iodide is used.
  • the temperature of the swelling bath is, for example, 20 ° C. to 45 ° C.
  • the immersion time is, for example, 10 seconds to 300 seconds.
  • the PVA-based resin film is stretched at any appropriate stretch ratio depending on the desired performance and thickness.
  • the PVA resin film is uniaxially stretched 3 to 7 times the original length.
  • the stretching direction may be the longitudinal direction (MD direction) of the film or the width direction (TD direction) of the film.
  • the stretching method may be dry stretching, wet stretching, or a combination thereof.
  • stretch a PVA-type resin film when performing a bridge
  • the stretching direction can correspond to the absorption axis direction of the obtained polarizer.
  • the PVA resin film is dyed with a solution containing an oxidant for iodide and iodine ions.
  • This oxidizing agent is an ionic compound composed of a cation and an anion.
  • the standard electrode potential of either an anion or cation is larger than the standard electrode potential of iodine ion.
  • polyiodine ions are formed by oxidation of iodine ions.
  • the content of polyiodine ions contained in the dyeing solution is increased, and the PVA resin film can be efficiently dyed.
  • the content of polyiodine ions in the dyeing solution can be increased with a small amount of iodine used. Therefore, the amount of iodine used in the stage of preparing the staining solution can be reduced, and adverse effects due to the high concentration of iodine on the environment and the human body when preparing the staining solution can be prevented.
  • the iodine content in a dyeing solution can be adjusted by adding the oxidizing agent with respect to an iodine ion in a dyeing solution. Therefore, the content of polyiodine ions in the staining solution can be appropriately adjusted more easily.
  • the content of iodide contained in the dyeing solution is preferably 1 to 40 parts by weight, more preferably 3 to 30 parts by weight with respect to 100 parts by weight of the solvent. If the iodide content is in the above range, sufficient polyiodine ions can be formed in the dyeing solution.
  • the iodide those exemplified above can be used. Potassium iodide is preferred.
  • an ionic compound composed of a cation and an anion is used as an oxidizing agent for iodine ions.
  • a standard electrode potential is known as an index of oxidizing power or reducing power in the redox reaction.
  • the ionic compound used as the oxidizing agent has a standard electrode potential of either an anion or cation larger than the standard electrode potential of iodine ions.
  • the standard electrode potential of the anion or cation is larger than the standard electrode potential (0.536 V) of iodine ion.
  • the standard electrode potential of the anion or cation is preferably 0.55 V or more, more preferably 0.60 V or more. It is because it can function suitably as an oxidizing agent for iodine ions.
  • the standard electrode potential of an anion or cation is, for example, 2.00 V or less.
  • anion or cation examples include Fe 3+ (0.771 V), Ag + (0.7991 V), Ag 2+ (1.980 V), Au + (1.83 V), Au 3+ (1.52 V), and Co. Cations such as 3+ (1.92 V), Cu 2+ (0.559 V), Mn 3+ (1.5 V), Pt 2+ (1.188 V), Br 3- (1.0503 V), ClO 3 ⁇ (0.622 V ), ClO 2 ⁇ (0.681V), ClO ⁇ (0.890V), Cr 2 O 7 2 ⁇ (1.36V), NO 3 ⁇ (0.835V, 0.94V, 0.9557V), MnO 4 - anions such as (0.56 V). Trivalent iron ions (Fe 3+ ) are preferred.
  • Trivalent iron ions are present in the dyeing solution as divalent iron ions after oxidation of iodine ions. Trivalent iron ions and divalent iron ions can be incorporated into the PVA-based resin film in the dyeing process. These iron ions have the action of dehydrating PVA. Therefore, it is possible to suppress the action of polyiodine ions that escape from the PVA resin film in the subsequent steps. As a result, it is preferable because the dyeability of the PVA resin film can be further improved.
  • the standard electrode potential is a value in an aqueous solution with a standard pressure of 1 atm and 25 ° C.
  • the standard electrode potential in an aqueous solution with a standard pressure of 1 atm and 25 ° C. is described in, for example, Electrochemical Handbook 6th Edition, Electrochemical Society, publisher Maruzen Publishing Co., Ltd. In this specification, the values described in the electrochemical handbook are used.
  • the oxidant may be an ionic compound in which an electrode reaction at a desired standard electrode potential occurs in the staining solution, and any appropriate compound can be used.
  • a compound containing Fe 3+ as a cation such as ferric sulfate, ferric chloride or ferric nitrate, a compound containing MnO 4 ⁇ as an anion such as potassium permanganate, Cu 2+ such as copper chloride or copper sulfate And the like. Since it contains Fe 3+ , it is preferable to use at least one compound selected from the group consisting of ferric sulfate, ferric chloride, and ferric nitrate. Only one type of oxidizing agent may be used, or two or more types may be used in combination.
  • the content of the oxidizing agent in the dyeing solution is preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 4 parts by weight with respect to 100 parts by weight of the solvent.
  • the content of the oxidizing agent in the dyeing solution can be determined according to the content of iodide contained in the dyeing solution.
  • the molar ratio of iodide to oxidizing agent can be set to any appropriate value, for example, 2/1 to 50/1, preferably 10/1 to 50/1. If the molar ratio of iodide and oxidizing agent is within the above range, the oxidizing agent can sufficiently function as an oxidizing agent for iodine ions.
  • Iodide and oxidizing agent can be used in any appropriate combination.
  • a combination using potassium iodide as the iodide and ferric sulfate as the oxidizing agent is preferable in that a polarizer having excellent characteristics such as durability can be obtained.
  • any appropriate solvent can be used, and water is usually used.
  • the dyeing solution may contain any appropriate other compound in addition to the iodide and the oxidizing agent.
  • the staining solution may further contain iodine.
  • the iodine content in the dyeing solution is, for example, 1 part by weight or less with respect to 100 parts by weight of the solvent.
  • the content ratio of iodine ions (I ⁇ ) and polyiodine ions (I 3 ⁇ ) contained in the dyeing solution is preferably such that the content ratio of iodine ions is large.
  • the content ratio of iodine ions is large, the sublimation amount of iodine from the staining solution can be reduced. Therefore, it is possible to suppress the environment caused by the sublimation of iodine and the influence on the human body.
  • the content ratio of iodine ions and polyiodine ions contained in the staining solution can be evaluated based on the intensity of absorbance of the staining solution.
  • the amount of iodine sublimation in the dyeing solution is less than 1000 ⁇ g / L, preferably 430 ⁇ g / L or less. Moreover, the amount of iodine sublimation is, for example, 250 ⁇ g / L or less.
  • the staining solution used in the present invention contains iodide and an oxidizing agent. Thereby, said iodine sublimation amount can be realized. In the present specification, the amount of iodine sublimation can be obtained by the method described in Examples.
  • Examples of the dyeing method include a method of immersing the PVA resin film in the dyeing solution, a method of applying the dyeing solution to the PVA resin film, and a method of spraying the dyeing solution on the PVA resin film. . Since it can dye
  • the liquid temperature during dyeing of the dyeing solution can be set to any appropriate value, for example, 20 ° C. to 50 ° C.
  • the immersion time is, for example, 1 second to 1 minute.
  • a boron compound is usually used as a crosslinking agent.
  • the boron compound include boric acid and borax. Preferably, it is a boric acid.
  • the boron compound is usually used in the form of an aqueous solution.
  • the boric acid concentration of the boric acid aqueous solution is, for example, 2% by weight to 15% by weight, and preferably 3% by weight to 13% by weight.
  • the boric acid aqueous solution may further contain an iodide such as potassium iodide, or a zinc compound such as zinc sulfate or zinc chloride.
  • the crosslinking step can be performed by any appropriate method. For example, a method of immersing a PVA resin film in an aqueous solution containing a boron compound, a method of applying an aqueous solution containing a boron compound to a PVA resin film, or a method of spraying an aqueous solution containing a boron compound onto a PVA resin film is given. It is done. It is preferable to immerse in an aqueous solution containing a boron compound.
  • the temperature of the solution used for crosslinking is, for example, 25 ° C. or higher, preferably 30 ° C. to 85 ° C., more preferably 40 ° C. to 70 ° C.
  • the immersion time is, for example, 5 seconds to 800 seconds, and preferably 8 seconds to 500 seconds.
  • the washing step is performed using water or an aqueous solution containing the above iodide. Typically, it is performed by immersing a PVA resin film in an aqueous potassium iodide solution.
  • the temperature of the aqueous solution in the washing step is, for example, 5 ° C. to 50 ° C.
  • the immersion time is, for example, 1 second to 300 seconds.
  • the drying step can be performed by any appropriate method.
  • natural drying, ventilation drying, reduced pressure drying, heat drying and the like can be mentioned, and heat drying is preferably used.
  • the heating temperature is, for example, 30 ° C. to 100 ° C.
  • the drying time is, for example, 10 seconds to 10 minutes.
  • the thickness of the polarizer obtained by the production method of the present invention is, for example, 0.5 ⁇ m to 80 ⁇ m, preferably 0.6 ⁇ m to 20 ⁇ m. In one embodiment, the thickness of the polarizer is preferably 0.8 ⁇ m to 10 ⁇ m. The thickness of the polarizer is more preferably 5 ⁇ m or less, further preferably 3 ⁇ m or less, and particularly preferably 2 ⁇ m or less.
  • the dyeing solution used by this invention can dye
  • the single transmittance of the polarizer obtained by the production method of the present invention is, for example, 30% or more.
  • the theoretical upper limit of the single transmittance is 50%, and the practical upper limit is 46%.
  • the single transmittance (Ts) is a Y value obtained by measuring the JIS Z8701 field of view (C light source) and correcting the visibility.
  • C light source For example, a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, Product name: V7100).
  • the polarization degree of the polarizer is, for example, 99.0% or more.
  • the iodine content of the polarizer obtained by the production method of the present invention is, for example, 5 to 30 parts by weight, preferably 8 to 25 parts by weight.
  • thermoplastic resin substrate an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 ⁇ m) having a water absorption of 0.75% and Tg of 75 ° C. was used.
  • IPA copolymerized PET film thickness: 100 ⁇ m
  • One side of the substrate was subjected to corona treatment, and polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6) were applied to this corona-treated surface.
  • the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).
  • a dyeing solution at 30 ° C. (an aqueous solution in which 3.4 parts by weight of potassium iodide and 0.8 parts by weight of ferric sulfate n-hydrate were added to 100 parts by weight of water) for 30 seconds. It was immersed and dyed (dyeing treatment).
  • the molar ratio of iodide to oxidizing agent in the dyeing solution was 13.3 / 1.
  • the ferric sulfate n hydrate added to the dyeing solution it confirmed that it was an average 6.7 hydrate by iodine titration. Therefore, the molar ratio with iodide was calculated by setting the average molecular weight of ferric sulfate n-hydrate to 520. Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking treatment).
  • the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C.
  • a boric acid aqueous solution an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water
  • a cleaning bath an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water
  • cleaning treatment an oven at 50 ° C. for 120 seconds to obtain a laminate 1 having a PVA resin layer (polarizer) having a thickness of 5 ⁇ m.
  • Example 2 An aqueous solution in which 1.7 parts by weight of potassium iodide and 0.4 parts by weight of ferric sulfate n-hydrate are added to 100 parts by weight of water (molar ratio of iodide and oxidizing agent in the dyeing solution).
  • Example 3 A laminate was produced in the same manner as in Example 1. The obtained long laminate was stretched in the air 4.5 times in a direction orthogonal to the longitudinal direction of the laminate at 140 ° C. using a tenter stretching machine. Next, the laminate was added to a dyeing solution at 30 ° C. (an aqueous solution in which 6.0 parts by weight of potassium iodide and 0.8 parts by weight of ferric sulfate n-hydrate were added to 100 parts by weight of water). It was immersed for 2 seconds and dyed (dyeing treatment). The molar ratio of iodide to oxidizing agent in the dyeing solution was 23.5 / 1.
  • the laminated body 4 having a PVA resin layer (polarizer) having a thickness of 1.5 ⁇ m was obtained in the same manner as in Example 3 except that.
  • Example 8 A laminate 8 having a PVA resin layer (polarizer) having a thickness of 1.0 ⁇ m was obtained in the same manner as in Example 5 except that a laminate having a PVA resin layer having a thickness of 5 ⁇ m was used.
  • Example 9 A laminate 9 having a PVA resin layer (polarizer) having a thickness of 0.8 ⁇ m was obtained in the same manner as in Example 5 except that a laminate having a PVA resin layer having a thickness of 4 ⁇ m was used.
  • a PVA resin layer having a thickness of 1.5 ⁇ m (polarized light) was used in the same manner as in Example 4 except that the dyeing solution was an aqueous solution in which 7 parts by weight of potassium iodide and 1 part by weight of iodine were added to 100 parts by weight of water.
  • the laminated body 10 which has a child) was obtained.
  • the single transmittance, dyeability, and iodine sublimation amount of the dye solution of the PVA resin layer (polarizer) were evaluated by the following methods. The results are shown in Table 1.
  • the single unit transmittance The single unit transmittance of the laminate was measured using a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, product name: V7100).
  • Dyeability The dyeability of the PVA-based resin layer (polarizer) of the obtained laminate was evaluated with a dyeing index calculated from the following formula. A higher dyeing index indicates that the dye is sufficiently dyed and has a high function as a polarizer.
  • the staining index is 0.4 or more, it indicates that it has a sufficient function as a polarizer.
  • the dyeing index is preferably 1.5 or more, more preferably 2.0 or more, and further preferably 2.5 or more. 3. Iodine sublimation amount of staining solution 20 mL of the staining solution used in each Example and Reference Example was injected into a Tedlar bag (manufactured by GL Sciences Inc.) containing 2 L of nitrogen. Subsequently, it heated with the dryer of 30 degreeC for 24 hours. Thereafter, 1.5 L of gas in the Tedlar bag was collected in a hydrazine absorbing solution (hydrazine aqueous solution, hydrazine concentration: 0.05% by weight) using an impinger.
  • a hydrazine absorbing solution hydrazine aqueous solution, hydrazine concentration: 0.05% by weight
  • the hydrazine absorption liquid was diluted 1000 times with pure water, and quantitative analysis was performed using an ion chromatography apparatus (product name: ICS-3000, manufactured by Thermo Scientific).
  • the measurement conditions were as follows. ⁇ Measurement conditions> Separation column: Dionex Ion Pac AS18-fast (4 mm x 150 mm) Guard column: Dionex Ion Pac AG18-fast (4mm x 30mm) Removal system: Dionex AERS-500 (external mode) Detector: Electrical conductivity detector Eluent: KOH aqueous solution (eluent generator EGCII) Eluent flow rate: 1.2 mL / min Sample injection volume: 250 ⁇ L
  • the polarizers obtained in Examples 1 to 9 were all well dyed and functioned satisfactorily as a polarizer.
  • the dyeing index is 1.5 or more, and the dye sublimation amount of the dyeing solution is 250 ⁇ g / L or less, thereby suppressing the environmental load and the influence on the human body. It was possible.
  • the production method of the present invention can dye a PVA resin film more efficiently, and can provide a sufficiently dyed polarizer even if it is thin.
  • the polarizer obtained by the production method of the present invention can be used in liquid crystal panels such as liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copy machines, printers, fax machines, watches, and microwave ovens. Can be widely applied.

Abstract

The purpose of the present invention is to provide a polarizer production method with which dyeing can be performed more efficiently. This polarizer production method includes a step in which a solution including an iodide and an oxidant of iodine ions is used to dye a polyvinyl alcohol resin film. The oxidant is an ionic compound which comprises a cation and an anion. The standard electrode potential of any one among the anion and the cation is greater than that of iodine ions. As a result of using such a solution to perform dyeing, the polyvinyl alcohol resin film can be dyed more efficiently.

Description

偏光子の製造方法Manufacturing method of polarizer
　本発明は、偏光子の製造方法に関する。 The present invention relates to a method for manufacturing a polarizer.
　液晶表示装置等の画像表示装置には、偏光子が用いられている。近年、画像表示装置の薄型化の要望が高まっている。そのため、偏光子についても、より薄型化が進められている。偏光子は、代表的には、ポリビニルアルコール（ＰＶＡ）系樹脂フィルムをヨウ素等の二色性物質で染色することにより製造される（例えば、特許文献１および２）。厚みの薄い偏光子を製造する場合、樹脂フィルムの厚さも薄くなるため、十分に染色できない場合がある。そのため、樹脂フィルムをより効率よく染色可能な方法が求められている。 A polarizer is used in an image display device such as a liquid crystal display device. In recent years, there has been an increasing demand for thinner image display devices. For this reason, thinner polarizers are also being promoted. A polarizer is typically manufactured by dyeing a polyvinyl alcohol (PVA) resin film with a dichroic substance such as iodine (for example, Patent Documents 1 and 2). In the case of manufacturing a thin polarizer, the thickness of the resin film is also thin, so that it may not be sufficiently dyed. Therefore, a method capable of dyeing a resin film more efficiently is demanded.
　また、染色工程において、ヨウ素が昇華し染色溶液中のヨウ素濃度が時間と共に減少することが知られている。これは高濃度のヨウ素を含む染色溶液において特に顕著である。さらに、染色工程ではＰＶＡ系樹脂フィルムにヨウ素を移行させるため、染色溶液中のヨウ素濃度が低下する。そのため、染色工程を安定的かつ連続的に行うためには、染色溶液中のヨウ素濃度を適宜調整する必要がある。低下したヨウ素濃度を調製時のヨウ素濃度に戻すためには、染色工程で用いる染色溶液よりも高濃度のヨウ素が含まれた溶液を添加する必要がある。高濃度のヨウ素は、環境および人体への悪影響が懸念される。そのため、より簡便に染色溶液中のヨウ素含有量を調整する方法が求められている。 Also, it is known that iodine is sublimated in the dyeing process and the iodine concentration in the dyeing solution decreases with time. This is particularly noticeable in dyeing solutions containing high concentrations of iodine. Furthermore, in the dyeing process, iodine is transferred to the PVA resin film, so that the iodine concentration in the dyeing solution is lowered. Therefore, in order to perform the dyeing process stably and continuously, it is necessary to appropriately adjust the iodine concentration in the dyeing solution. In order to return the lowered iodine concentration to the iodine concentration at the time of preparation, it is necessary to add a solution containing iodine at a higher concentration than the staining solution used in the staining step. High concentrations of iodine are a concern for adverse effects on the environment and the human body. Therefore, a method for adjusting the iodine content in the dyeing solution more easily is demanded.
特許第５０４８１２０号公報Japanese Patent No. 5048120 特開２０１３－１５６３９１号公報JP 2013-156391 A
　本発明は、上記従来の課題を解決するためになされたものであり、その主たる目的は、ＰＶＡ系樹脂フィルムをより効率よく染色可能な偏光子の製造方法を提供することにある。 The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a method for producing a polarizer capable of dyeing a PVA resin film more efficiently.
　本発明の偏光子製造方法は、ポリビニルアルコール系樹脂フィルムを、ヨウ化物およびヨウ素イオンに対する酸化剤を含む溶液を用いて染色する工程を含む。この酸化剤は、カチオンとアニオンとからなるイオン性化合物であって、該アニオンまたはカチオンのいずれか一方の標準電極電位がヨウ素イオンの標準電極電位よりも大きい。
　１つの実施形態においては、上記アニオンまたはカチオンの標準電極電位は０．５５Ｖ以上である。
　１つの実施形態においては、上記溶液におけるヨウ化物の含有量は、溶媒１００重量部に対して１重量部～４０重量部である。
　１つの実施形態においては、上記溶液における酸化剤の含有量は、溶媒１００重量部に対して０．１重量部～１０重量部である。
　１つの実施形態においては、上記ヨウ化物と上記酸化剤とのモル比は２／１～５０／１である。
　１つの実施形態においては、上記酸化剤がカチオンとして３価の鉄イオンを含む。
　１つの実施形態においては、上記酸化剤は硫酸第二鉄、塩化第二鉄、および、硝酸第二鉄からなる群より選択される少なくとも１種である。
　１つの実施形態においては、上記偏光子の製造方法により得られる偏光子の厚みは１０μｍ以下である。 The polarizer manufacturing method of the present invention includes a step of dyeing a polyvinyl alcohol-based resin film with a solution containing an oxidant for iodide and iodine ions. This oxidizing agent is an ionic compound composed of a cation and an anion, and the standard electrode potential of either the anion or cation is larger than the standard electrode potential of iodine ion.
In one embodiment, the standard electrode potential of the anion or cation is 0.55 V or more.
In one embodiment, the iodide content in the solution is 1 to 40 parts by weight with respect to 100 parts by weight of the solvent.
In one embodiment, the content of the oxidizing agent in the solution is 0.1 to 10 parts by weight with respect to 100 parts by weight of the solvent.
In one embodiment, the molar ratio of the iodide to the oxidant is 2/1 to 50/1.
In one embodiment, the oxidizing agent contains a trivalent iron ion as a cation.
In one embodiment, the oxidizing agent is at least one selected from the group consisting of ferric sulfate, ferric chloride, and ferric nitrate.
In one embodiment, the thickness of the polarizer obtained by the manufacturing method of the above-mentioned polarizer is 10 micrometers or less.
　本発明によれば、ＰＶＡ系樹脂フィルムをより効率良く染色することができる。具体的には、ＰＶＡ系樹脂フィルムを、ヨウ化物およびヨウ素イオンに対する酸化剤を含む溶液を用いて染色する。その結果、溶液中でヨウ素イオンが酸化剤により酸化され、ポリヨウ素イオン（例えば、Ｉ３ －イオン）が形成され、溶液に含まれるポリヨウ素イオンの含有量を効率良く高めることができる。この溶液を染色溶液として用いることにより、ＰＶＡ系樹脂フィルムをより効率良く染色することができる。また、本発明の製造方法によれば、固体のヨウ素を用いることなくポリヨウ素イオンの含有量を高めることができる。そのため、染色溶液調製時のヨウ素による環境および人体への悪影響をも防止し得る。 According to the present invention, a PVA resin film can be dyed more efficiently. Specifically, the PVA resin film is dyed using a solution containing an oxidant for iodide and iodine ions. As a result, iodine ions are oxidized in the solution by the oxidizing agent to form polyiodine ions (for example, I 3 − ions), and the content of polyiodine ions contained in the solution can be increased efficiently. By using this solution as a dyeing solution, the PVA resin film can be dyed more efficiently. Moreover, according to the production method of the present invention, the content of polyiodine ions can be increased without using solid iodine. Therefore, adverse effects on the environment and the human body due to iodine at the time of preparing the staining solution can be prevented.
　以下、本発明の好ましい実施形態について説明するが、本発明はこれらの実施形態には限定されない。 Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
　本発明の偏光子の製造方法は、ＰＶＡ系樹脂フィルムを、ヨウ化物およびヨウ素イオンに対する酸化剤を含む溶液（以下、染色溶液ともいう）を用いて染色する工程を含む。この酸化剤は、カチオンとアニオンとからなるイオン性化合物であって、該アニオンまたはカチオンのいずれか一方の標準電極電位がヨウ素イオンの標準電極電位よりも大きい。この酸化剤により、ヨウ素イオンが酸化され、ポリヨウ素イオンが形成され得る。この染色溶液を用いて染色することにより、ＰＶＡ系樹脂フィルムをより効率よく染色することができる。染色工程の詳細については、後述する。偏光子は、例えば、ＰＶＡ系樹脂フィルムを、膨潤工程、染色工程、架橋工程、延伸工程、洗浄工程、乾燥工程に供することにより製造することができる。 The method for producing a polarizer of the present invention includes a step of dyeing a PVA resin film with a solution containing an oxidant for iodide and iodine ions (hereinafter also referred to as a dyeing solution). This oxidizing agent is an ionic compound composed of a cation and an anion, and the standard electrode potential of either the anion or cation is larger than the standard electrode potential of iodine ion. With this oxidizing agent, iodine ions can be oxidized to form polyiodine ions. By dyeing with this dyeing solution, the PVA resin film can be dyed more efficiently. Details of the dyeing process will be described later. A polarizer can be manufactured by, for example, subjecting a PVA resin film to a swelling process, a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process.
　ＰＶＡ系樹脂フィルムを形成するＰＶＡ系樹脂としては、例えば、ポリビニルアルコール、エチレン－ビニルアルコール共重合体が挙げられる。ポリビニルアルコールは、ポリ酢酸ビニルをケン化することにより得られる。エチレン－ビニルアルコール共重合体は、エチレン－酢酸ビニル共重合体をケン化することにより得られる。ＰＶＡ系樹脂のケン化度は、通常８５モル％以上１００モル％未満であり、好ましくは９５．０モル％～９９．９９モル％、さらに好ましくは９９．０モル％～９９．９９モル％である。ケン化度は、ＪＩＳ　Ｋ　６７２６－１９９４に準じて求めることができる。このようなケン化度のＰＶＡ系樹脂を用いることによって、耐久性に優れた偏光子を得ることができる。 Examples of the PVA resin forming the PVA resin film include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.99 mol%, more preferably 99.0 mol% to 99.99 mol%. is there. The degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizer having excellent durability can be obtained.
　ＰＶＡ系樹脂の平均重合度は、目的に応じて適切に選択され得る。平均重合度は、通常１０００～１００００であり、好ましくは１２００～４５００、さらに好ましくは１５００～４３００である。なお、平均重合度は、ＪＩＳ　Ｋ　６７２６－１９９４に準じて求めることができる。 The average degree of polymerization of the PVA resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10,000, preferably 1200 to 4500, and more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.
　ＰＶＡ系樹脂フィルムの厚みは、特に制限はなく、所望の偏光子の厚みに応じて設定され得る。ＰＶＡ系樹脂フィルムの厚みは、例えば、０．５μｍ～２００μｍである。本発明で用いる染色溶液は、ＰＶＡ系樹脂フィルムを非常に効率良く染色することができる。したがって、例えば、ＰＶＡ系樹脂フィルムが１０μｍ未満であっても短時間で十分に染色することができ、偏光子として十分に機能し得る特性を付与することができる。 The thickness of the PVA resin film is not particularly limited, and can be set according to a desired thickness of the polarizer. The thickness of the PVA resin film is, for example, 0.5 μm to 200 μm. The dyeing solution used in the present invention can dye a PVA resin film very efficiently. Therefore, for example, even if a PVA-type resin film is less than 10 micrometers, it can dye | stain sufficiently in a short time, and the characteristic which can fully function as a polarizer can be provided.
　１つの実施形態においては、ＰＶＡ系樹脂フィルムは、基材上に形成されたＰＶＡ系樹脂層であってもよい。基材と樹脂層との積層体は、例えば、上記ＰＶＡ系樹脂を含む塗布液を基材に塗布する方法、基材にＰＶＡ系樹脂フィルムを積層する方法等により得ることができる。基材としては、任意の適切な樹脂基材を用いることができ、例えば、熱可塑性樹脂基材を用いることができる。 In one embodiment, the PVA resin film may be a PVA resin layer formed on a substrate. The laminated body of a base material and a resin layer can be obtained by the method of apply | coating the coating liquid containing the said PVA-type resin to a base material, the method of laminating | stacking a PVA-type resin film on a base material, etc., for example. Any appropriate resin substrate can be used as the substrate, and for example, a thermoplastic resin substrate can be used.
　上記の通り、偏光子は、例えば、ＰＶＡ系樹脂フィルムを、膨潤工程、染色工程、架橋工程、延伸工程、洗浄工程、乾燥工程に供することにより製造することができる。各工程は任意の適切なタイミングで行われる。また、必要に応じて、染色工程以外の任意の工程が省略されていてもよく、また複数の工程を同時に行ってもよく、それぞれの工程を複数回行ってもよい。以下、各工程について説明する。 As described above, the polarizer can be produced, for example, by subjecting the PVA resin film to a swelling process, a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process. Each process is performed at any appropriate timing. Further, if necessary, any step other than the dyeing step may be omitted, a plurality of steps may be performed simultaneously, and each step may be performed a plurality of times. Hereinafter, each step will be described.
　膨潤工程は、通常、染色工程の前に行われる。膨潤工程は、同じ浸漬浴の中で染色工程とともに行われてもよい。膨潤工程は、例えば、ＰＶＡ系樹脂フィルムを膨潤浴に浸漬することにより行われる。膨潤浴としては、任意の適切な液体を用いることができ、例えば、蒸留水、純水等の水が用いられる。膨潤浴は、水以外の任意の適切な他の成分を含んでいてもよい。他の成分としては、アルコール等の溶媒、界面活性剤等の添加剤、ヨウ化物等が挙げられる。ヨウ化物としては、例えば、ヨウ化カリウム、ヨウ化リチウム、ヨウ化ナトリウム、ヨウ化亜鉛、ヨウ化アルミニウム、ヨウ化鉛、ヨウ化銅、ヨウ化バリウム、ヨウ化カルシウム、ヨウ化錫、ヨウ化チタン等が挙げられる。好ましくは、ヨウ化カリウムが用いられる。膨潤浴の温度は、例えば、２０℃～４５℃である。また、浸漬時間は、例えば、１０秒～３００秒である。 The swelling process is usually performed before the dyeing process. The swelling process may be performed together with the dyeing process in the same immersion bath. A swelling process is performed by immersing a PVA-type resin film in a swelling bath, for example. Any appropriate liquid can be used as the swelling bath. For example, water such as distilled water or pure water is used. The swelling bath may contain any appropriate other component other than water. Examples of other components include alcohols and other solvents, surfactants and other additives, and iodides. Examples of the 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. Etc. Preferably, potassium iodide is used. The temperature of the swelling bath is, for example, 20 ° C. to 45 ° C. The immersion time is, for example, 10 seconds to 300 seconds.
　延伸工程において、ＰＶＡ系樹脂フィルムは、所望の性能および厚みに応じて、任意の適切な延伸倍率で延伸される。代表的には、ＰＶＡ系樹脂フィルムは、元長に対して３倍～７倍に一軸延伸される。延伸方向は、フィルムの長手方向（ＭＤ方向）であってもよく、フィルムの幅方向（ＴＤ方向）であってもよい。延伸方法は、乾式延伸であってもよく、湿式延伸であってもよく、これらを組み合せてもよい。また、架橋工程、膨潤工程、染色工程等を行う際にＰＶＡ系樹脂フィルムを延伸してもよい。なお、延伸方向は、得られる偏光子の吸収軸方向に対応し得る。 In the stretching step, the PVA-based resin film is stretched at any appropriate stretch ratio depending on the desired performance and thickness. Typically, the PVA resin film is uniaxially stretched 3 to 7 times the original length. The stretching direction may be the longitudinal direction (MD direction) of the film or the width direction (TD direction) of the film. The stretching method may be dry stretching, wet stretching, or a combination thereof. Moreover, when performing a bridge | crosslinking process, a swelling process, a dyeing process, etc., you may extend | stretch a PVA-type resin film. The stretching direction can correspond to the absorption axis direction of the obtained polarizer.
　染色工程では、ＰＶＡ系樹脂フィルムを、ヨウ化物およびヨウ素イオンに対する酸化剤等を含む溶液を用いて染色する。この酸化剤は、カチオンとアニオンとからなるイオン性化合物である。このアニオンまたはカチオンのいずれか一方の標準電極電位はヨウ素イオンの標準電極電位よりも大きい。上記の通り、この染色溶液では、ヨウ素イオンが酸化されることによりポリヨウ素イオンが形成される。その結果、染色溶液に含まれるポリヨウ素イオンの含有量が高くなり、効率良くＰＶＡ系樹脂フィルムを染色することができる。さらに、ヨウ素を水もしくはヨウ化物を含む水溶液に添加して染色溶液を調製する場合に比べて、少ないヨウ素使用量で染色溶液中のポリヨウ素イオンの含有量を高めることができる。そのため、染色溶液を調製する段階におけるヨウ素の使用量を低減することができ、染色溶液調製時の環境および人体への高濃度のヨウ素による悪影響をも防止し得る。また、本発明では、染色溶液中にヨウ素イオンに対する酸化剤を添加することにより、染色溶液中のヨウ素含有量を調整することができる。そのため、より簡便に染色溶液中のポリヨウ素イオンの含有量を適切に調整することができる。 In the dyeing step, the PVA resin film is dyed with a solution containing an oxidant for iodide and iodine ions. This oxidizing agent is an ionic compound composed of a cation and an anion. The standard electrode potential of either an anion or cation is larger than the standard electrode potential of iodine ion. As described above, in this staining solution, polyiodine ions are formed by oxidation of iodine ions. As a result, the content of polyiodine ions contained in the dyeing solution is increased, and the PVA resin film can be efficiently dyed. Furthermore, compared with the case where a dyeing solution is prepared by adding iodine to water or an aqueous solution containing iodide, the content of polyiodine ions in the dyeing solution can be increased with a small amount of iodine used. Therefore, the amount of iodine used in the stage of preparing the staining solution can be reduced, and adverse effects due to the high concentration of iodine on the environment and the human body when preparing the staining solution can be prevented. Moreover, in this invention, the iodine content in a dyeing solution can be adjusted by adding the oxidizing agent with respect to an iodine ion in a dyeing solution. Therefore, the content of polyiodine ions in the staining solution can be appropriately adjusted more easily.
　染色溶液に含まれるヨウ化物の含有量は、溶媒１００重量部に対して好ましくは１重量部～４０重量部であり、より好ましくは３重量部～３０重量部である。ヨウ化物の含有量が上記の範囲であれば、染色溶液中に十分なポリヨウ素イオンを形成することができる。ヨウ化物としては、上記で例示したものを用いることができる。好ましくはヨウ化カリウムである。 The content of iodide contained in the dyeing solution is preferably 1 to 40 parts by weight, more preferably 3 to 30 parts by weight with respect to 100 parts by weight of the solvent. If the iodide content is in the above range, sufficient polyiodine ions can be formed in the dyeing solution. As the iodide, those exemplified above can be used. Potassium iodide is preferred.
　本発明ではヨウ素イオンに対する酸化剤として、カチオンとアニオンとからなるイオン性化合物を用いる。酸化還元反応における酸化力または還元力の指標として、標準電極電位が知られている。酸化剤として用いるイオン性化合物は、アニオンまたはカチオンのいずれか一方の標準電極電位がヨウ素イオンの標準電極電位よりも大きい。具体的には、上記アニオンまたはカチオンの標準電極電位は、ヨウ素イオンの標準電極電位（０．５３６Ｖ）よりも大きい。上記アニオンまたはカチオンの標準電極電位は、好ましくは０．５５Ｖ以上であり、より好ましくは０．６０Ｖ以上である。ヨウ素イオンに対する酸化剤として好適に機能し得るからである。また、アニオンまたはカチオンの標準電極電位は、例えば、２．００Ｖ以下である。 In the present invention, an ionic compound composed of a cation and an anion is used as an oxidizing agent for iodine ions. A standard electrode potential is known as an index of oxidizing power or reducing power in the redox reaction. The ionic compound used as the oxidizing agent has a standard electrode potential of either an anion or cation larger than the standard electrode potential of iodine ions. Specifically, the standard electrode potential of the anion or cation is larger than the standard electrode potential (0.536 V) of iodine ion. The standard electrode potential of the anion or cation is preferably 0.55 V or more, more preferably 0.60 V or more. It is because it can function suitably as an oxidizing agent for iodine ions. The standard electrode potential of an anion or cation is, for example, 2.00 V or less.
　上記アニオンまたはカチオンとしては、例えば、Ｆｅ３＋（０．７７１Ｖ）、Ａｇ＋（０．７９９１Ｖ）、Ａｇ２＋（１．９８０Ｖ）、Ａｕ＋（１．８３Ｖ）、Ａｕ３＋（１．５２Ｖ）、Ｃｏ３＋（１．９２Ｖ）、Ｃｕ２＋（０．５５９Ｖ）、Ｍｎ３＋（１．５Ｖ）、Ｐｔ２＋（１．１８８Ｖ）等のカチオン、Ｂｒ３－（１．０５０３Ｖ）、ＣｌＯ３ －（０．６２２Ｖ）、ＣｌＯ２ －（０．６８１Ｖ）、ＣｌＯ－（０．８９０Ｖ）、Ｃｒ２Ｏ７ ２－（１．３６Ｖ）、ＮＯ３ －（０．８３５Ｖ、０．９４Ｖ、０．９５５７Ｖ）、ＭｎＯ４ －（０．５６Ｖ）等のアニオンが挙げられる。好ましくは三価の鉄イオン（Ｆｅ３＋）である。三価の鉄イオンは、ヨウ素イオンを酸化した後、二価の鉄イオンとして染色溶液中に存在する。三価の鉄イオンおよび二価の鉄イオンは、染色工程においてＰＶＡ系樹脂フィルムに取り込まれ得る。これらの鉄イオンはＰＶＡを脱水する作用を有する。そのため、その後の工程でポリヨウ素イオンがＰＶＡ系樹脂フィルムから抜け出す作用を抑制することできる。その結果、ＰＶＡ系樹脂フィルムの染色性がさらに向上し得るため好ましい。本明細書において、標準電極電位は標準圧力が１ａｔｍ、２５℃の水溶液における値をいう。標準圧力が１ａｔｍ、２５℃の水溶液における標準電極電位は、例えば、電気化学便覧　第６版　電気化学会編　発行元　丸善出版株式会社に記載されている。本明細書においては、上記電気化学便覧に記載の値を用いる。 Examples of the anion or cation include Fe 3+ (0.771 V), Ag + (0.7991 V), Ag 2+ (1.980 V), Au + (1.83 V), Au 3+ (1.52 V), and Co. Cations such as 3+ (1.92 V), Cu 2+ (0.559 V), Mn 3+ (1.5 V), Pt 2+ (1.188 V), Br 3- (1.0503 V), ClO 3 − (0.622 V ), ClO 2 − (0.681V), ClO − (0.890V), Cr 2 O 7 2− (1.36V), NO 3 − (0.835V, 0.94V, 0.9557V), MnO 4 - anions such as (0.56 V). Trivalent iron ions (Fe 3+ ) are preferred. Trivalent iron ions are present in the dyeing solution as divalent iron ions after oxidation of iodine ions. Trivalent iron ions and divalent iron ions can be incorporated into the PVA-based resin film in the dyeing process. These iron ions have the action of dehydrating PVA. Therefore, it is possible to suppress the action of polyiodine ions that escape from the PVA resin film in the subsequent steps. As a result, it is preferable because the dyeability of the PVA resin film can be further improved. In this specification, the standard electrode potential is a value in an aqueous solution with a standard pressure of 1 atm and 25 ° C. The standard electrode potential in an aqueous solution with a standard pressure of 1 atm and 25 ° C. is described in, for example, Electrochemical Handbook 6th Edition, Electrochemical Society, publisher Maruzen Publishing Co., Ltd. In this specification, the values described in the electrochemical handbook are used.
　上記酸化剤としては、所望の標準電極電位となる電極反応が染色溶液中で起こるイオン性化合物であればよく、任意の適切な化合物を用いることができる。例えば、硫酸第二鉄、塩化第二鉄、硝酸第二鉄等のＦｅ３＋をカチオンとして含む化合物、過マンガン酸カリウム等のＭｎＯ４ －をアニオンとして含む化合物、塩化銅、硫酸銅等のＣｕ２＋をカチオンとして含む化合物等が挙げられる。Ｆｅ３＋を含むことから、硫酸第二鉄、塩化第二鉄、および、硝酸第二鉄からなる群より選択される少なくとも１種の化合物を用いることが好ましい。酸化剤は１種のみを用いてもよく、２種以上を組み合せて用いてもよい。 The oxidant may be an ionic compound in which an electrode reaction at a desired standard electrode potential occurs in the staining solution, and any appropriate compound can be used. For example, a compound containing Fe 3+ as a cation such as ferric sulfate, ferric chloride or ferric nitrate, a compound containing MnO 4 − as an anion such as potassium permanganate, Cu 2+ such as copper chloride or copper sulfate And the like. Since it contains Fe 3+ , it is preferable to use at least one compound selected from the group consisting of ferric sulfate, ferric chloride, and ferric nitrate. Only one type of oxidizing agent may be used, or two or more types may be used in combination.
　染色溶液における酸化剤の含有量は、溶媒１００重量部に対して好ましくは０．１重量部～１０重量部であり、より好ましくは０．５重量部～４重量部である。染色溶液における酸化剤の含有量は、染色溶液に含まれるヨウ化物の含有量に応じて決定され得る。 The content of the oxidizing agent in the dyeing solution is preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 4 parts by weight with respect to 100 parts by weight of the solvent. The content of the oxidizing agent in the dyeing solution can be determined according to the content of iodide contained in the dyeing solution.
　ヨウ化物と酸化剤とのモル比は、任意の適切な値に設定することができ、例えば、２／１～５０／１であり、好ましくは１０／１～５０／１である。ヨウ化物と酸化剤とのモル比が上記の範囲内であれば、酸化剤がヨウ素イオンに対する酸化剤として十分に機能し得る。 The molar ratio of iodide to oxidizing agent can be set to any appropriate value, for example, 2/1 to 50/1, preferably 10/1 to 50/1. If the molar ratio of iodide and oxidizing agent is within the above range, the oxidizing agent can sufficiently function as an oxidizing agent for iodine ions.
　ヨウ化物と酸化剤とは、任意の適切な組み合わせで用いることができる。例えば、ヨウ化物としてヨウ化カリウムを、酸化剤として硫酸第二鉄を用いる組み合わせが、耐久性等の優れた特性を有する偏光子が得られるという点から好ましい。 Iodide and oxidizing agent can be used in any appropriate combination. For example, a combination using potassium iodide as the iodide and ferric sulfate as the oxidizing agent is preferable in that a polarizer having excellent characteristics such as durability can be obtained.
　染色溶液の溶媒としては、任意の適切な溶媒を用いることができ、通常、水が用いられる。 As the solvent for the staining solution, any appropriate solvent can be used, and water is usually used.
　上記染色溶液は、ヨウ化物および酸化剤以外にも任意の適切な他の化合物を含んでいてもよい。例えば、染色溶液はヨウ素をさらに含んでいてもよい。染色溶液がヨウ素をさらに含む場合、染色溶液におけるヨウ素含有量は、例えば、溶媒１００重量部に対して１重量部以下である。 The dyeing solution may contain any appropriate other compound in addition to the iodide and the oxidizing agent. For example, the staining solution may further contain iodine. When the dyeing solution further contains iodine, the iodine content in the dyeing solution is, for example, 1 part by weight or less with respect to 100 parts by weight of the solvent.
　染色溶液に含まれるヨウ素イオン（Ｉ－）とポリヨウ素イオン（Ｉ３ －）との含有比率は、ヨウ素イオンの含有比率が大きい方が好ましい。ヨウ素イオンの含有比率が大きい場合、染色溶液からのヨウ素の昇華量が低減され得る。そのため、ヨウ素が昇華することによる環境、および、人体への影響を抑制することができる。染色溶液に含まれるヨウ素イオンおよびポリヨウ素イオンの含有比率は、染色溶液の吸光度の強度により評価することができる。 The content ratio of iodine ions (I − ) and polyiodine ions (I 3 − ) contained in the dyeing solution is preferably such that the content ratio of iodine ions is large. When the content ratio of iodine ions is large, the sublimation amount of iodine from the staining solution can be reduced. Therefore, it is possible to suppress the environment caused by the sublimation of iodine and the influence on the human body. The content ratio of iodine ions and polyiodine ions contained in the staining solution can be evaluated based on the intensity of absorbance of the staining solution.
　染色溶液のヨウ素昇華量は、少ないほど好ましい。例えば、ヨウ素昇華量は１０００μｇ／Ｌ未満であり、好ましくは４３０μｇ／Ｌ以下である。また、ヨウ素昇華量は、例えば、２５０μｇ／Ｌ以下である。上記の通り、本発明で用いる染色溶液はヨウ化物と酸化剤とを含む。これにより、上記のヨウ素昇華量が実現され得る。なお、本明細書において、ヨウ素昇華量は実施例に記載の方法で得ることができる。 The smaller the amount of iodine sublimation in the dyeing solution, the better. For example, the amount of iodine sublimation is less than 1000 μg / L, preferably 430 μg / L or less. Moreover, the amount of iodine sublimation is, for example, 250 μg / L or less. As described above, the staining solution used in the present invention contains iodide and an oxidizing agent. Thereby, said iodine sublimation amount can be realized. In the present specification, the amount of iodine sublimation can be obtained by the method described in Examples.
　染色方法としては、例えば、上記染色溶液にＰＶＡ系樹脂フィルムを浸漬させる方法、ＰＶＡ系樹脂フィルムに当該染色溶液を塗工する方法、当該染色溶液をＰＶＡ系樹脂フィルムに噴霧する方法等が挙げられる。良好に染色することができることから、好ましくは染色溶液にＰＶＡ系樹脂フィルムを浸漬させる方法である。 Examples of the dyeing method include a method of immersing the PVA resin film in the dyeing solution, a method of applying the dyeing solution to the PVA resin film, and a method of spraying the dyeing solution on the PVA resin film. . Since it can dye | stain favorably, Preferably it is the method of immersing a PVA-type resin film in a dyeing solution.
　染色溶液の染色時の液温は、任意の適切な値に設定することができ、例えば、２０℃～５０℃である。染色溶液にＰＶＡ系樹脂フィルムを浸漬させる場合、浸漬時間は、例えば、１秒～１分である。 The liquid temperature during dyeing of the dyeing solution can be set to any appropriate value, for example, 20 ° C. to 50 ° C. When the PVA resin film is immersed in the dyeing solution, the immersion time is, for example, 1 second to 1 minute.
　架橋工程においては、通常、架橋剤としてホウ素化合物が用いられる。ホウ素化合物としては、例えば、ホウ酸、ホウ砂等が挙げられる。好ましくは、ホウ酸である。架橋工程においては、ホウ素化合物は、通常、水溶液の形態で用いられる。 In the crosslinking step, a boron compound is usually used as a crosslinking agent. Examples of the boron compound include boric acid and borax. Preferably, it is a boric acid. In the crosslinking step, the boron compound is usually used in the form of an aqueous solution.
　ホウ酸水溶液を用いる場合、ホウ酸水溶液のホウ酸濃度は、例えば、２重量％～１５重量％であり、好ましくは３重量％～１３重量％である。ホウ酸水溶液には、ヨウ化カリウム等のヨウ化物、硫酸亜鉛、塩化亜鉛等の亜鉛化合物をさらに含有させてもよい。 When a boric acid aqueous solution is used, the boric acid concentration of the boric acid aqueous solution is, for example, 2% by weight to 15% by weight, and preferably 3% by weight to 13% by weight. The boric acid aqueous solution may further contain an iodide such as potassium iodide, or a zinc compound such as zinc sulfate or zinc chloride.
　架橋工程は、任意の適切な方法により行うことができる。例えば、ホウ素化合物を含む水溶液にＰＶＡ系樹脂フィルムを浸漬する方法、ホウ素化合物を含む水溶液をＰＶＡ系樹脂フィルムに塗布する方法、または、ホウ素化合物を含む水溶液をＰＶＡ系樹脂フィルムに噴霧する方法が挙げられる。ホウ素化合物を含む水溶液に浸漬することが好ましい。 The crosslinking step can be performed by any appropriate method. For example, a method of immersing a PVA resin film in an aqueous solution containing a boron compound, a method of applying an aqueous solution containing a boron compound to a PVA resin film, or a method of spraying an aqueous solution containing a boron compound onto a PVA resin film is given. It is done. It is preferable to immerse in an aqueous solution containing a boron compound.
　架橋に用いる溶液の温度は、例えば、２５℃以上であり、好ましくは３０℃～８５℃、さらに好ましくは４０℃～７０℃である。浸漬時間は、例えば、５秒～８００秒であり、好ましくは８秒～５００秒である。 The temperature of the solution used for crosslinking is, for example, 25 ° C. or higher, preferably 30 ° C. to 85 ° C., more preferably 40 ° C. to 70 ° C. The immersion time is, for example, 5 seconds to 800 seconds, and preferably 8 seconds to 500 seconds.
　洗浄工程は、水、または、上記ヨウ化物を含む水溶液を用いて行われる。代表的には、ヨウ化カリウム水溶液にＰＶＡ系樹脂フィルムを浸漬させることにより行う。洗浄工程における水溶液の温度は、例えば、５℃～５０℃である。浸漬時間は、例えば、１秒～３００秒である。 The washing step is performed using water or an aqueous solution containing the above iodide. Typically, it is performed by immersing a PVA resin film in an aqueous potassium iodide solution. The temperature of the aqueous solution in the washing step is, for example, 5 ° C. to 50 ° C. The immersion time is, for example, 1 second to 300 seconds.
　乾燥工程は、任意の適切な方法により行うことができる。例えば、自然乾燥、送風乾燥、減圧乾燥、加熱乾燥等が挙げられ、加熱乾燥が好ましく用いられる。加熱乾燥を行う場合、加熱温度は、例えば、３０℃～１００℃である。また、乾燥時間は、例えば、１０秒～１０分間である。 The drying step can be performed by any appropriate method. For example, natural drying, ventilation drying, reduced pressure drying, heat drying and the like can be mentioned, and heat drying is preferably used. In the case of performing heat drying, the heating temperature is, for example, 30 ° C. to 100 ° C. The drying time is, for example, 10 seconds to 10 minutes.
　本発明の製造方法により得られる偏光子の厚みは、例えば、０．５μｍ～８０μｍであり、好ましくは０．６μｍ～２０μｍである。１つの実施形態においては、偏光子の厚みは、好ましくは０．８μｍ～１０μｍである。偏光子の厚みは、より好ましくは５μｍ以下であり、さらに好ましくは３μｍ以下であり、特に好ましくは２μｍ以下である。上記の通り、本発明で用いる染色溶液は、効率良くＰＶＡ系樹脂フィルムを染色することができる。そのため、厚みが薄い偏光子であっても所望の単体透過率を十分に付与することができる。 The thickness of the polarizer obtained by the production method of the present invention is, for example, 0.5 μm to 80 μm, preferably 0.6 μm to 20 μm. In one embodiment, the thickness of the polarizer is preferably 0.8 μm to 10 μm. The thickness of the polarizer is more preferably 5 μm or less, further preferably 3 μm or less, and particularly preferably 2 μm or less. As above-mentioned, the dyeing solution used by this invention can dye | stain a PVA-type resin film efficiently. Therefore, a desired single transmittance can be sufficiently imparted even with a thin polarizer.
　本発明の製造方法により得られる偏光子の単体透過率は、例えば、３０％以上である。なお、単体透過率の理論上の上限は５０％であり、実用的な上限は４６％である。また、単体透過率（Ｔｓ）は、ＪＩＳ　Ｚ８７０１の２度視野（Ｃ光源）により測定して視感度補正を行なったＹ値であり、例えば、積分球付き分光光度計（日本分光株式会社製、製品名：Ｖ７１００）を用いて測定することができる。また、偏光子の偏光度は、例えば、９９．０％以上である。 The single transmittance of the polarizer obtained by the production method of the present invention is, for example, 30% or more. The theoretical upper limit of the single transmittance is 50%, and the practical upper limit is 46%. Further, the single transmittance (Ts) is a Y value obtained by measuring the JIS Z8701 field of view (C light source) and correcting the visibility. For example, a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, Product name: V7100). The polarization degree of the polarizer is, for example, 99.0% or more.
　本発明の製造方法により得られる偏光子のヨウ素含有量は、例えば、５重量部～３０重量部であり、好ましくは８重量部～２５重量部である。上記の方法により偏光子を製造することにより、偏光子に含まれるヨウ素含有量を高めることができる。 The iodine content of the polarizer obtained by the production method of the present invention is, for example, 5 to 30 parts by weight, preferably 8 to 25 parts by weight. By producing a polarizer by the above method, the iodine content contained in the polarizer can be increased.
　以下、実施例によって本発明を具体的に説明するが、本発明はこれら実施例によって限定されるものではない。 Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.
［実施例１］
　熱可塑性樹脂基材として、吸水率０．７５％、Ｔｇ７５℃の非晶質のイソフタル酸共重合ポリエチレンテレフタレート（ＩＰＡ共重合ＰＥＴ）フィルム（厚み：１００μｍ）を用いた。基材の片面に、コロナ処理を施し、このコロナ処理面に、ポリビニルアルコール（重合度４２００、ケン化度９９．２モル％）およびアセトアセチル変性ＰＶＡ（重合度１２００、アセトアセチル変性度４．６％、ケン化度９９．０モル％以上、日本合成化学工業社製、商品名「ゴーセファイマーＺ２００」）を９：１の比で含む水溶液を２５℃で塗布および乾燥して、厚み１１μｍのＰＶＡ系樹脂層を形成し、積層体を作製した。
　得られた積層体を、１２０℃のオーブン内で周速の異なるロール間で縦方向（長手方向）に２．０倍に自由端一軸延伸した（空中補助延伸）。
　次いで、積層体を、液温３０℃の不溶化浴（水１００重量部に対して、ホウ酸を４重量部配合して得られたホウ酸水溶液）に３０秒間浸漬させた（不溶化処理）。
　次いで、積層体を３０℃の染色溶液（水１００重量部に対し、ヨウ化カリウム３．４重量部、および、硫酸第二鉄ｎ水和物０．８重量部を添加した水溶液）に３０秒間浸漬させ、染色した（染色処理）。染色溶液におけるヨウ化物と酸化剤とのモル比は、１３．３／１であった。なお、染色溶液に添加した硫酸第二鉄ｎ水和物については、ヨウ素滴定により平均６．７水和物であることを確認した。したがって、硫酸第二鉄ｎ水和物の平均分子量を５２０として、ヨウ化物とのモル比を算出した。
　次いで、液温３０℃の架橋浴（水１００重量部に対して、ヨウ化カリウムを３重量部配合し、ホウ酸を３重量部配合して得られたホウ酸水溶液）に３０秒間浸漬させた（架橋処理）。
　その後、積層体を、液温７０℃のホウ酸水溶液（水１００重量部に対して、ホウ酸を４重量部配合し、ヨウ化カリウムを５重量部配合して得られた水溶液）に浸漬させながら、周速の異なるロール間で縦方向（長手方向）に総延伸倍率が５．５倍となるように一軸延伸を行った（水中延伸）。
　その後、積層体を液温３０℃の洗浄浴（水１００重量部に対して、ヨウ化カリウム４重量部を配合して得られた水溶液）に１０秒間浸漬させた（洗浄処理）。
　その後、５０℃のオーブンで１２０秒間乾燥させ、厚み５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体１を得た。 [Example 1]
As a thermoplastic resin substrate, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption of 0.75% and Tg of 75 ° C. was used. One side of the substrate was subjected to corona treatment, and polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6) were applied to this corona-treated surface. %, A saponification degree of 99.0 mol% or more, an aqueous solution containing 9: 1 ratio of Nippon Gosei Kagaku Kogyo Co., Ltd., trade name “Gosefimer Z200”) was applied and dried at 25 ° C. to a thickness of 11 μm. A PVA resin layer was formed to prepare a laminate.
The obtained laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (air-assisted stretching).
Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Subsequently, the laminate was added to a dyeing solution at 30 ° C. (an aqueous solution in which 3.4 parts by weight of potassium iodide and 0.8 parts by weight of ferric sulfate n-hydrate were added to 100 parts by weight of water) for 30 seconds. It was immersed and dyed (dyeing treatment). The molar ratio of iodide to oxidizing agent in the dyeing solution was 13.3 / 1. In addition, about the ferric sulfate n hydrate added to the dyeing solution, it confirmed that it was an average 6.7 hydrate by iodine titration. Therefore, the molar ratio with iodide was calculated by setting the average molecular weight of ferric sulfate n-hydrate to 520.
Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking treatment).
Thereafter, the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C. However, uniaxial stretching was performed between the rolls having different peripheral speeds in the longitudinal direction (longitudinal direction) so that the total stretching ratio was 5.5 times (in-water stretching).
Thereafter, the laminate was immersed for 10 seconds in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. (cleaning treatment).
Thereafter, it was dried in an oven at 50 ° C. for 120 seconds to obtain a laminate 1 having a PVA resin layer (polarizer) having a thickness of 5 μm.
［実施例２］
　染色溶液を水１００重量部に対し、ヨウ化カリウム１．７重量部、および、硫酸第二鉄ｎ水和物０．４重量部を添加した水溶液（染色溶液におけるヨウ化物と酸化剤とのモル比＝１３．３／１）とした以外は実施例１と同様にして、厚み５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体２を得た。 [Example 2]
An aqueous solution in which 1.7 parts by weight of potassium iodide and 0.4 parts by weight of ferric sulfate n-hydrate are added to 100 parts by weight of water (molar ratio of iodide and oxidizing agent in the dyeing solution). A laminate 2 having a PVA resin layer (polarizer) having a thickness of 5 μm was obtained in the same manner as in Example 1 except that the ratio = 13.3 / 1).
［実施例３］
　実施例１と同様にして、積層体を作製した。
　得られた長尺の積層体を、テンター延伸機を用いて、１４０℃で積層体の長手方向と直交する方向に４．５倍空中延伸した。
　次いで、積層体を、３０℃の染色溶液（水１００重量部に対し、ヨウ化カリウム６．０重量部、および、硫酸第二鉄ｎ水和物０．８重量部を添加した水溶液）に３０秒間浸漬させ、染色した（染色処理）。染色溶液におけるヨウ化物と酸化剤とのモル比は、２３．５／１であった。
　次いで、液温６０℃の架橋浴（水１００重量部に対して、ヨウ化カリウムを３重量部配合し、ホウ酸を３重量部配合して得られたホウ酸水溶液）に３５秒間浸漬させた（架橋処理）。
　次いで、積層体を液温２５℃の洗浄浴（水１００重量部に対して、ヨウ化カリウムを４重量部配合して得られた水溶液）に１０秒間浸漬させた（洗浄処理）。
　その後、６０℃のオーブンで１２０秒間乾燥させ、厚み２．５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体３を得た。 [Example 3]
A laminate was produced in the same manner as in Example 1.
The obtained long laminate was stretched in the air 4.5 times in a direction orthogonal to the longitudinal direction of the laminate at 140 ° C. using a tenter stretching machine.
Next, the laminate was added to a dyeing solution at 30 ° C. (an aqueous solution in which 6.0 parts by weight of potassium iodide and 0.8 parts by weight of ferric sulfate n-hydrate were added to 100 parts by weight of water). It was immersed for 2 seconds and dyed (dyeing treatment). The molar ratio of iodide to oxidizing agent in the dyeing solution was 23.5 / 1.
Subsequently, it was immersed in a crosslinking bath having a liquid temperature of 60 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 35 seconds. (Crosslinking treatment).
Next, the laminate was immersed for 10 seconds in a washing bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 25 ° C. (cleaning treatment).
Then, it was dried in an oven at 60 ° C. for 120 seconds to obtain a laminate 3 having a PVA resin layer (polarizer) having a thickness of 2.5 μm.
［実施例４］
　厚み７μｍのＰＶＡ系樹脂層を形成した積層体を用いたこと、および、染色溶液に含まれるヨウ化カリウムを３０重量部（染色溶液におけるヨウ化物と酸化剤とのモル比＝４６．９／１）としたこと以外は実施例３と同様にして、厚み１．５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体４を得た。 [Example 4]
Use of a laminate in which a PVA resin layer having a thickness of 7 μm was used, and 30 parts by weight of potassium iodide contained in the dyeing solution (molar ratio of iodide and oxidizing agent in the dyeing solution = 46.9 / 1) The laminated body 4 having a PVA resin layer (polarizer) having a thickness of 1.5 μm was obtained in the same manner as in Example 3 except that.
［実施例５］
　染色溶液に含まれるヨウ化カリウムを１５．０重量部（染色溶液におけるヨウ化物と酸化剤とのモル比＝２３．５／１）としたこと以外は実施例４と同様にして、厚み１．５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体５を得た。 [Example 5]
A thickness of 1.5 parts in the same manner as in Example 4 except that the potassium iodide contained in the dyeing solution was 15.0 parts by weight (molar ratio of iodide to oxidizing agent in the dyeing solution = 23.5 / 1). A laminate 5 having a 5 μm PVA resin layer (polarizer) was obtained.
［実施例６］
　染色溶液に含まれるヨウ化カリウムを１０．０重量部（染色溶液におけるヨウ化物と酸化剤とのモル比＝１５．６／１）としたこと以外は実施例４と同様にして、厚み１．５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体６を得た。 [Example 6]
Thickness of 1. in the same manner as in Example 4 except that 10.0 parts by weight of potassium iodide contained in the dyeing solution (molar ratio of iodide to oxidizing agent in the dyeing solution = 15.6 / 1) was used. A laminate 6 having a 5 μm PVA resin layer (polarizer) was obtained.
［実施例７］
　染色溶液に含まれるヨウ化カリウムを７．０重量部（染色溶液におけるヨウ化物と酸化剤とのモル比＝１１．０／１）としたこと以外は実施例４と同様にして、厚み１．５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体７を得た。 [Example 7]
Thickness of 1. in the same manner as in Example 4 except that 7.0 parts by weight of potassium iodide contained in the dyeing solution (molar ratio of iodide to oxidizing agent in the dyeing solution = 11.0 / 1) was used. A laminate 7 having a PVA resin layer (polarizer) of 5 μm was obtained.
［実施例８］
　厚み５μｍのＰＶＡ系樹脂層を形成した積層体を用いたこと以外は実施例５と同様にして、厚み１．０μｍのＰＶＡ系樹脂層（偏光子）を有する積層体８を得た。 [Example 8]
A laminate 8 having a PVA resin layer (polarizer) having a thickness of 1.0 μm was obtained in the same manner as in Example 5 except that a laminate having a PVA resin layer having a thickness of 5 μm was used.
［実施例９］
　厚み４μｍのＰＶＡ系樹脂層を形成した積層体を用いたこと以外は実施例５と同様にして、厚み０．８μｍのＰＶＡ系樹脂層（偏光子）を有する積層体９を得た。 [Example 9]
A laminate 9 having a PVA resin layer (polarizer) having a thickness of 0.8 μm was obtained in the same manner as in Example 5 except that a laminate having a PVA resin layer having a thickness of 4 μm was used.
（参考例）
　染色溶液を水１００重量部に対し、ヨウ化カリウム７重量部、および、ヨウ素１重量部を添加した水溶液とした以外は実施例４と同様にして、厚み１．５μｍのＰＶＡ系樹脂層（偏光子）を有する積層体１０を得た。 (Reference example)
A PVA resin layer having a thickness of 1.5 μm (polarized light) was used in the same manner as in Example 4 except that the dyeing solution was an aqueous solution in which 7 parts by weight of potassium iodide and 1 part by weight of iodine were added to 100 parts by weight of water. The laminated body 10 which has a child) was obtained.
　実施例１～９および参考例で得られた積層体を用いて、ＰＶＡ系樹脂層（偏光子）の単体透過率、染色性、および、染色溶液のヨウ素昇華量を以下の方法により評価した。結果を表１に示す。
１．単体透過率
　積分球付き分光光度計（日本分光株式会社製、製品名：Ｖ７１００）を用いて、積層体の単体透過率を測定した。
２．染色性（染色指数）
　得られた積層体のＰＶＡ系樹脂層（偏光子）の染色性を下記式から算出した染色指数で評価した。染色指数が高いほど、十分に染色されており、偏光子として高い機能を有することを示す。染色指数が０．４以上であれば偏光子として十分な機能を有することを示す。染色指数は、好ましくは１．５以上であり、より好ましくは２．０以上であり、さらに好ましくは２．５以上である。
Figure JPOXMLDOC01-appb-C000001
 ３．染色溶液のヨウ素昇華量
　窒素２Ｌを入れたテドラーバック（ジーエルサイエンス社製）に、各実施例および参考例で用いた染色溶液２０ｍＬを注入した。次いで、３０℃の乾燥機で２４時間加温した。その後、インピンジャーを用いて、テドラーバック内のガス１．５Ｌをヒドラジン吸収液（ヒドラジン水溶液、ヒドラジン濃度：０．０５重量％）に捕集した。次いで、ヒドラジン吸収液を純水で１０００倍に希釈し、イオンクロマトグラフィー装置（Ｔｈｅｒｍｏ　Ｓｃｉｅｎｔｉｆｉｃ社製、製品名：ＩＣＳ－３０００）を用いて定量分析を行った。測定条件は以下の通りにして行った。
 
＜測定条件＞
分離カラム：Ｄｉｏｎｅｘ　Ｉｏｎ　Ｐａｃ　ＡＳ１８－ｆａｓｔ（４ｍｍ×１５０ｍｍ）
ガードカラム：Ｄｉｏｎｅｘ　Ｉｏｎ　Ｐａｃ　ＡＧ１８－ｆａｓｔ（４ｍｍ×３０ｍｍ）
除去システム：Ｄｉｏｎｅｘ　ＡＥＲＳ－５００（エクスターナルモード）
検出器：電気伝導度検出器
溶離液：ＫＯＨ水溶液（溶離液ジェネレーターＥＧＣＩＩ）
溶離液流量：１．２ｍＬ／ｍｉｎ
試料注入量：２５０μＬ Using the laminates obtained in Examples 1 to 9 and Reference Example, the single transmittance, dyeability, and iodine sublimation amount of the dye solution of the PVA resin layer (polarizer) were evaluated by the following methods. The results are shown in Table 1.
1. Single unit transmittance The single unit transmittance of the laminate was measured using a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, product name: V7100).
2. Dyeability (dyeing index)
The dyeability of the PVA-based resin layer (polarizer) of the obtained laminate was evaluated with a dyeing index calculated from the following formula. A higher dyeing index indicates that the dye is sufficiently dyed and has a high function as a polarizer. If the staining index is 0.4 or more, it indicates that it has a sufficient function as a polarizer. The dyeing index is preferably 1.5 or more, more preferably 2.0 or more, and further preferably 2.5 or more.
Figure JPOXMLDOC01-appb-C000001
 3. Iodine sublimation amount of staining solution 20 mL of the staining solution used in each Example and Reference Example was injected into a Tedlar bag (manufactured by GL Sciences Inc.) containing 2 L of nitrogen. Subsequently, it heated with the dryer of 30 degreeC for 24 hours. Thereafter, 1.5 L of gas in the Tedlar bag was collected in a hydrazine absorbing solution (hydrazine aqueous solution, hydrazine concentration: 0.05% by weight) using an impinger. Subsequently, the hydrazine absorption liquid was diluted 1000 times with pure water, and quantitative analysis was performed using an ion chromatography apparatus (product name: ICS-3000, manufactured by Thermo Scientific). The measurement conditions were as follows.

<Measurement conditions>
Separation column: Dionex Ion Pac AS18-fast (4 mm x 150 mm)
Guard column: Dionex Ion Pac AG18-fast (4mm x 30mm)
Removal system: Dionex AERS-500 (external mode)
Detector: Electrical conductivity detector Eluent: KOH aqueous solution (eluent generator EGCII)
Eluent flow rate: 1.2 mL / min
Sample injection volume: 250 μL
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　実施例１～９で得られた偏光子は、いずれも良好に染色されており、偏光子として十分に機能するものであった。また、実施例３～５、８および９では染色指数が１．５以上であり、かつ、染色溶液のヨウ素昇華量が２５０μｇ／Ｌ以下であり、環境負荷および人体への影響をも抑えることができるものであった。 The polarizers obtained in Examples 1 to 9 were all well dyed and functioned satisfactorily as a polarizer. In Examples 3 to 5, 8 and 9, the dyeing index is 1.5 or more, and the dye sublimation amount of the dyeing solution is 250 μg / L or less, thereby suppressing the environmental load and the influence on the human body. It was possible.
　本発明の製造方法は、より効率良くＰＶＡ系樹脂フィルムを染色することができ、薄型であっても十分に染色された偏光子を提供することができる。本発明の製造方法により得られる偏光子は、液晶テレビ、液晶ディスプレイ、携帯電話、デジタルカメラ、ビデオカメラ、携帯ゲーム機、カーナビゲーション、コピー機、プリンター、ファックス、時計、電子レンジ等の液晶パネルに幅広く適用させることができる。 The production method of the present invention can dye a PVA resin film more efficiently, and can provide a sufficiently dyed polarizer even if it is thin. The polarizer obtained by the production method of the present invention can be used in liquid crystal panels such as liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copy machines, printers, fax machines, watches, and microwave ovens. Can be widely applied.

Claims (8)

  1. 　ポリビニルアルコール系樹脂フィルムを、ヨウ化物およびヨウ素イオンに対する酸化剤を含む溶液を用いて染色する工程を含む偏光子の製造方法であって、
    　該酸化剤が、カチオンとアニオンとを含むイオン性化合物であって、該アニオンまたはカチオンのいずれか一方の標準電極電位がヨウ素イオンの標準電極電位よりも大きい、偏光子の製造方法。     A method for producing a polarizer comprising a step of dyeing a polyvinyl alcohol-based resin film with a solution containing an oxidant for iodide and iodine ions,
    The method for producing a polarizer, wherein the oxidizing agent is an ionic compound containing a cation and an anion, and the standard electrode potential of either the anion or cation is larger than the standard electrode potential of iodine ion.
  2. 　前記アニオンまたはカチオンの標準電極電位が０．５５Ｖ以上である、請求項１に記載の偏光子の製造方法。 The method for producing a polarizer according to claim 1, wherein a standard electrode potential of the anion or cation is 0.55 V or more.
  3. 　前記溶液におけるヨウ化物の含有量が、溶媒１００重量部に対して１重量部～４０重量部である、請求項１または２に記載の偏光子の製造方法。 3. The method for producing a polarizer according to claim 1, wherein the iodide content in the solution is 1 to 40 parts by weight with respect to 100 parts by weight of the solvent.
  4. 　前記溶液における酸化剤の含有量が、溶媒１００重量部に対して０．１重量部～１０重量部である、請求項１～３のいずれかに記載の偏光子の製造方法。 4. The method for producing a polarizer according to claim 1, wherein the content of the oxidizing agent in the solution is 0.1 to 10 parts by weight with respect to 100 parts by weight of the solvent.
  5. 　前記ヨウ化物と前記酸化剤とのモル比が２／１～５０／１である、請求項１～４のいずれかに記載の偏光子の製造方法。 The method for producing a polarizer according to any one of claims 1 to 4, wherein a molar ratio of the iodide to the oxidizing agent is 2/1 to 50/1.
  6. 　前記酸化剤がカチオンとして３価の鉄イオンを含む、請求項１から５のいずれかに記載の偏光子の製造方法。 The method for producing a polarizer according to any one of claims 1 to 5, wherein the oxidizing agent contains a trivalent iron ion as a cation.
  7. 　前記酸化剤が硫酸第二鉄、塩化第二鉄、および、硝酸第二鉄からなる群より選択される少なくとも１種である、請求項６に記載の偏光子の製造方法。 The method for producing a polarizer according to claim 6, wherein the oxidizing agent is at least one selected from the group consisting of ferric sulfate, ferric chloride, and ferric nitrate.
  8. 　偏光子の厚みが１０μｍ以下である、請求項１～７のいずれかに記載の偏光子の製造方法。 The method for producing a polarizer according to any one of claims 1 to 7, wherein the thickness of the polarizer is 10 µm or less.
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