TWI569051B - A method of manufacturing a polarizing member, a polarizing member, a polarizing plate, an optical film, and an image display device - Google Patents

Description

Polarizer manufacturing method, polarizing member, polarizing plate, optical film and image display device Technical field

The present invention relates to a method of manufacturing a polarizing member and a polarizing member produced by the manufacturing method. Further, the present invention relates to a polarizing plate, an optical film, and a liquid crystal display device using the polarizer, the polarizing plate, the optical film, an organic EL display device, and an image display device such as a PDP.

Background technique

The liquid crystal display device is used for personal computers, TVs, monitors, mobile phones, PDAs, and the like. Conventionally, as a polarizing material for a liquid crystal display device or the like, a polyvinyl alcohol-based film which has been subjected to dyeing treatment is used because of its high transmittance and high degree of polarization. In the polarizing member, a polyvinyl alcohol-based film is placed in a bath to be subjected to various treatments such as swelling, dyeing, crosslinking, and drawing, followed by washing treatment and drying. Further, the polarizer is usually used in the form of a polarizing plate in which a protective film such as triacetyl cellulose is bonded to one or both sides of the adhesive.

In recent years, liquid crystal display devices have been inferior in performance and thinner, and the polarizer has also been required to be thinner. For example, the thickness is 10 μm or less The polarizer can be formed by coating a polyvinyl alcohol-based resin solution on a thermoplastic resin substrate and drying it to form a laminate having a polyvinyl alcohol-based resin layer, and then performing a dyeing process and a drawing process on the laminated body. It is produced (Patent Document 1). In addition, a method of producing a polarizing material has been proposed in which an aqueous solution containing a polyvinyl alcohol-based resin is applied to a thermoplastic resin substrate to dry the water to form a polyvinyl alcohol-based resin layer having a thickness of ten μm, and then used. In the drawing device of the oven, the laminated body having the thermoplastic resin substrate and the polyvinyl alcohol-based resin layer is heated and air-drawn, and then the drawn laminated body is immersed in the dyeing bath to make polyvinyl alcohol. The resin layer adsorbs a coloring matter, and a polarizing material in which a dichroic substance having a thickness of several μm is oriented is manufactured in the manufacturing industry (Patent Document 2).

Prior art literature Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2009-098653

Patent Document 2: Japanese Patent No. 4751881

Summary of invention

Usually, when iodine is used as the dichroic substance in the dyeing procedure, the iodine complex in the polarizer absorbs light in the visible light region and exhibits polarization characteristics (polarization degree). Therefore, in order to suppress the light leakage of the polarizer, it is conceivable to increase the amount of the iodine complex in the polarizer. Therefore, in the method of producing the thin polarizer, in order to secure high polarization characteristics, it is preferable to perform a dyeing process on the laminated body (having a thermoplastic resin substrate and a polyvinyl alcohol-based resin layer). A dye bath for setting the concentration of the dichroic substance (iodine or the like) is also used.

On the other hand, when the dyeing procedure is performed on the laminate, and other procedures are performed, the iodine used in the dyeing procedure is brought to the treatment procedure (treatment bath) after the dyeing procedure, so that the treatment bath after the dyeing procedure is contaminated with iodine, thereby reducing The characteristics of the obtained polarizer (monomer transmittance, polarization). In particular, in the dyeing procedure, in order to increase the amount of iodine complex in the polarizer, when the dye bath is used to increase the iodine concentration, the iodine complex in the polyvinyl alcohol molecule is increased, and is relatively brought to the subsequent processing of the dyeing process. The amount of iodine in the procedure (treatment bath) also increased. Therefore, the treatment bath after the dyeing process is contaminated with iodine, and excess iodine which does not form a complex is present, thereby lowering the characteristics (monomer penetration rate, polarization degree) of the obtained polarizer.

An object of the present invention is to provide a polarizing member having a thickness of 10 μm or less by performing at least a dyeing procedure and a drawing procedure on a laminate including a polyvinyl alcohol-based resin layer formed on a thermoplastic resin substrate. It is characterized in that, in the dyeing procedure, even when a dye bath having a high concentration of a dichroic substance is used, the characteristics (monomer transmittance, polarization degree) of the polarizer can be satisfied.

It is an object of the present invention to provide a polarizing member obtained by the manufacturing method, and to provide a polarizing plate and an optical film using the polarizing member. Another object of the present invention is to provide an image display device using the polarizer, the polarizing plate, and the optical film.

The inventors of the present invention have conducted intensive studies in order to solve the above problems, and as a result, it has been found that the method of manufacturing a polarizer described below can be used. The foregoing objects are achieved, thereby completing the present invention.

In other words, the present invention relates to a method for producing a polarizer, which comprises at least a dyeing procedure and a drawing procedure for a laminate including a polyvinyl alcohol-based resin layer formed on a thermoplastic resin substrate, and a laminated thickness of 10 μm. The following polarizer is characterized in that In at least one of the procedures after the dyeing procedure, treatment with a treatment bath containing a water-soluble antioxidant is applied at least once. The method for producing the polarizing member described above is suitable when the dyeing program is an iodine dyeing program.

In the method for producing a polarizing member, it is preferable that at least one of ascorbic acid, erythorbic acid, chlorogenic acid, citric acid, rosmarinic acid, and the like is contained as the water-soluble antioxidant.

In the method for producing a polarizing member, at least one of the processes after the dyeing process preferably includes a crosslinking process in the crosslinking bath. Further, the crosslinking bath preferably contains the aforementioned water-soluble antioxidant.

In the method for producing a polarizer, it is preferable that the treatment liquid containing the water-soluble antioxidant treatment bath has an absorbance of about 10 or less at a wavelength of about 350 nm when measured in a 5-fold diluted solution.

In the above method of manufacturing a polarizing member, the drawing process may include an air assist drawing process performed before the dyeing process, and a wet drawing process performed after the dyeing process. The treatment bath used in the aforementioned wet drawing procedure is preferably used as a crosslinking bath.

In the above method of manufacturing a polarizing member, the drawing process may include a dry drawing process performed before the dyeing process.

In addition, the present invention relates to a method of manufacturing by the foregoing. Polarized parts.

Further, the present invention relates to a polarizing plate characterized in that it has a transparent protective film on at least one side of the polarizing member.

Further, the present invention relates to an optical film characterized by comprising the aforementioned polarizer or polarizing plate.

Further, the present invention relates to an image display device comprising the polarizing member, a polarizing plate or an optical film.

In the method of producing a polarizer, when a large amount of iodide ions (I ₃ ^- ) are present in the treatment bath after the dyeing process, I ₃ ^- is introduced into the polyvinyl alcohol-based resin in a state of poor orientation to form a polyvinyl alcohol-based resin - Iodine complex. Therefore, the orientation of the obtained polarizer is lowered, and the characteristics of the polarizer are lowered. In the method for producing a polarizer according to the present invention, the layered body including the polyvinyl alcohol-based resin layer is subjected to a dyeing procedure, and then treated with a treatment bath containing a water-soluble antioxidant. The water-soluble antioxidant has a reducing ability for the iodine remaining as an impurity in the treatment bath after the dyeing bath, and the iodide ion (I ₃ ^- ) in the treatment bath can be reduced to exhibit no absorption in the visible light region (380-780 nm). I ^- . As a result, according to the production method of the present invention, the characteristics of the obtained polarizer can be prevented from being lowered.

Form for implementing the invention <Thermoplastic resin substrate>

The thermoplastic resin substrate used in the production method of the present invention will be described. As the thermoplastic resin substrate, a material which has been conventionally used as a transparent protective film for a polarizing member can be used. As a material constituting the thermoplastic resin substrate, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, water barrier properties, isotropic properties, and stretchability can be used. Specific examples of the thermoplastic resin include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether oxime resins; and polyfluorene resins. Polycarbonate resin; polyamine resin such as nylon or aromatic polyamide; polyimine resin; polyethylene, polypropylene, ethylene. Polyolefin resin such as propylene copolymer; ring system or even Cyclic polyolefin resin with olefin structure An olefin resin; a (meth)acrylic resin; a polyarylate resin; a polystyrene resin; a polyvinyl alcohol resin; and a mixture thereof. Further, in order to improve the adhesion to the polyvinyl alcohol-based resin layer, a thin layer such as a primer layer (primer layer) may be formed on the thermoplastic resin substrate.

The thermoplastic resin is roughly classified into a resin which is in a crystalline state in which the polymer is regularly arranged, and an amorphous or amorphous resin which is irregularly arranged in a polymer or which is arranged in a very small portion of a polymer. The former is called a crystalline state, and the latter is called an amorphous or amorphous state. Correspondingly, a thermoplastic resin which forms a crystalline state is called a crystalline resin, and a thermoplastic resin which does not have such a property is called an amorphous resin. On the other hand, whether it is a crystalline resin or an amorphous resin, a resin which is not in a crystalline state or a resin which does not reach a crystalline state is called an amorphous or amorphous resin. Here, the amorphous or amorphous resin is different from the amorphous resin which does not form a crystalline state.

As the crystalline resin, for example, polyethylene (PE), poly An olefin-based resin of propylene (PP) or an ester-based resin containing polyethylene terephthalate (PET) or polybutylene terephthalate (PBT). One of the characteristics of the crystalline resin is that it generally has a property of promoting polymer alignment and crystallization in a heating or drawing orientation. The physical properties of the resin vary depending on the degree of crystallization. On the other hand, even a crystalline resin such as polypropylene (PP) or polyethylene terephthalate (PET) can suppress crystallization by blocking the polymer arrangement caused by heat treatment and drawing orientation. . These polypropylene (PP) and polyethylene terephthalate (PET), which are inhibited by crystallization, are called amorphous polypropylene and amorphous polyethylene terephthalate, and are respectively subjected to They are collectively referred to as an amorphous olefin resin or an amorphous ester resin.

Taking polypropylene (PP) as an example, amorphous polypropylene (PP) which has been inhibited from crystallization can be produced by forming a random structure having no stereoregularity. Further, polyethylene terephthalate (PET) is exemplified by copolymerization of a modified group such as isophthalic acid or 1,4-cyclohexanedimethanol as a polymerization monomer, that is, Amorphous polyethylene terephthalate (PET) which has been inhibited from crystallization can be produced by copolymerizing a molecule which inhibits the crystallization of polyethylene terephthalate (PET).

The thickness of the thermoplastic resin substrate (before drawing) can be appropriately determined by a trade-off, and is usually about 10 to 500 μm in terms of workability such as strength and handleability and thickness of the layer. Especially 20~300μm is preferred, and 30~200μm is better. It is particularly preferable that the thickness of the thermoplastic resin substrate is 50 to 150 μm.

<Polyvinyl alcohol resin>

The method for manufacturing a polarizing member of the present invention is for forming a film comprising a film before A laminate of a polyvinyl alcohol-based resin layer on a thermoplastic resin substrate. The polyvinyl alcohol-based resin to be used is not particularly limited, and a polyvinyl alcohol-based resin which has a light-transmitting property in a visible light region and which disperses and adsorbs a dichroic substance such as iodine or a dichroic dye can be used.

As the polyvinyl alcohol-based resin, a polyvinyl alcohol-based resin which has been conventionally used for a polarizing member is preferably used. The polyvinyl alcohol-based resin is polyvinyl alcohol or a derivative thereof. Examples of the polyvinyl alcohol derivative include, in addition to polyethylene formaldehyde and polyvinyl acetal, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl esters thereof. , modified substances such as acrylamide. The degree of polymerization of the polyvinyl alcohol is preferably from about 100 to 10,000, more preferably from 1,000 to 10,000. Polyvinyl alcohol having a degree of saponification of about 80 to 100 mol% is usually used.

The polyvinyl alcohol-based resin may further contain an additive such as a plasticizer or a surfactant. Examples of the plasticizer include a polyhydric alcohol and a condensate thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer or the like to be used is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol-based resin.

<Laminated body>

The layered body used in the present invention can be obtained by applying an aqueous solution containing a polyvinyl alcohol-based resin to the thermoplastic resin substrate and drying it to form a polyvinyl alcohol-based resin layer. In the coating, the thermoplastic resin substrate and the polyvinyl alcohol-based resin layer are laminated with a primer layer or the thermoplastic resin substrate and the polyvinyl alcohol-based resin layer are directly laminated to obtain a substrate layer and a hydrophilic polymer. A layered body in the state of layer integration.

The aqueous solution can be prepared by dissolving a powder of a polyvinyl alcohol-based resin, a pulverized product, a cut product, or the like in appropriately heated water (hot water). The concentration of the aqueous solution is about 2 to 20% by weight, preferably 4 to 10% by weight. When the aqueous solution is applied onto a thermoplastic resin substrate, a roll coating method such as a bar coating method, a reverse coating method, or a gravure coating method, a spin coating method, a screen coating method, a spray coating method, a dipping method, or a spray can be appropriately selected. Law and so on. When the thermoplastic resin substrate has a primer layer, the aqueous solution is applied to the undercoat layer, and when the undercoat layer is not provided, the aqueous solution is directly applied to the substrate layer. In addition, the drying temperature is usually 50 to 200 ° C, preferably 80 to 150 ° C, and the drying time is usually about 5 to 30 minutes.

The polyvinyl alcohol-based resin layer is formed to have a thickness such that the thickness of the obtained polarizer is 10 μm or less in consideration of the draw ratio of the drawing treatment to the laminate. Usually, the thickness of the polyvinyl alcohol-based resin layer is 3 to 20 μm, and preferably 5 to 15 μm.

<Processing program>

In the method for producing a polarizer according to the present invention, at least the dyeing process and the drawing process are performed on the laminated body. Further, the method for producing a polarizing member of the present invention can carry out a crosslinking procedure. In the dyeing procedure, the crosslinking procedure, and the drawing procedure, each treatment bath of the dyeing bath, the crosslinking bath, and the drawing bath can be used. When a treatment bath is used, a treatment liquid (aqueous solution or the like) corresponding to each procedure is used.

<staining procedure>

The dyeing process is carried out by iodine or a dichroic dye. The layer is oriented on the polyvinyl alcohol-based resin layer of the laminate. The staining procedure can be performed with the drawing program. Dyeing usually by immersing the above laminated body in a dyeing solution And proceed. The staining solution is generally an iodine solution. As the iodine aqueous solution used as the iodine solution, an aqueous solution containing iodine and an iodide as a dissolution aid and containing an iodide ion or the like can be used. As the iodide, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, iodide may be used. Titanium, etc. For such iodides, potassium iodide is preferred. The iodide used in the present invention is also the same as described above when used in other procedures.

The iodine concentration in the iodine solution is about 0.01 to 10% by weight, preferably 0.02 to 5% by weight, more preferably 0.1 to 1.0% by weight. The iodide concentration to be used is preferably about 0.1 to 10% by weight, more preferably 0.2 to 8% by weight. When iodine dyeing is performed, the temperature of the iodine solution is usually about 20 to 50 ° C, and preferably 25 to 40 ° C. The immersion time is usually about 10 to 300 seconds, and preferably in the range of 20 to 240 seconds. Further, for the dyeing time, any time can be immersed until a prescribed degree of polarization or transmittance can be achieved.

<drawing procedure>

The drawing procedure can be either a dry drawing method or a wet drawing method. The drawing process typically performs uniaxial drawing on the aforementioned laminate. The uniaxial drawing may be either longitudinal drawing of the longitudinal direction of the laminated body or lateral stretching of the width direction of the laminated body. The lateral drawing can also be stretched in the width direction while being contracted in the longitudinal direction. Examples of the transverse stretching method include a fixed-end uniaxial drawing method in which one end is fixed by a tenter, or a free-end uniaxial drawing method in which one end is not fixed. Examples of the longitudinal stretching method include a roll stretching method, a compression drawing method, and a drawing method using a tenter. The drawing process can also be divided into many The stage is carried out. In addition, the drawing process can be performed by performing biaxial drawing, diagonal drawing, or the like.

An advantage of the dry drawing method is that the temperature range at the time of drawing the above laminated body can be expanded. The dry stretching method is usually carried out by heating the laminate to a temperature of about 50 to 200 ° C, preferably 80 to 180 ° C, and more preferably 100 to 160 ° C. If the aforementioned drawing procedure includes a dry drawing procedure, the dry drawing procedure should be carried out before the dyeing procedure.

The treatment liquid used in the wet drawing method may contain iodide. When the treatment liquid contains iodide, the concentration of the iodide used is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight. The treatment temperature of the wet drawing method is usually 25 ° C or more, and preferably 30 to 85 ° C, more preferably 50 to 70 ° C. The immersion time is usually 10 to 800 seconds, and preferably about 30 to 500 seconds. In addition, the staining procedure can be carried out together with the crosslinking procedure.

The drawing procedure is carried out under the condition that the total drawing ratio is 4 to 8 times with respect to the original length of the laminated body. The total draw ratio should be 5-7 times. It should be noted that the program other than the drawing program has a pull delay, and the total draw ratio refers to the cumulative draw ratio including the draw of the programs. The total draw ratio can be appropriately determined in consideration of the draw ratio of other programs and the like. When the total draw ratio is low, the orientation is insufficient, and it is difficult to obtain a polarizer having high optical characteristics (polarity). On the other hand, when the total draw ratio is too high, the draw fracture is liable to occur, and the polarizer becomes too thin, which may cause a decrease in workability in the subsequent procedure.

The aforementioned drawing procedure can be carried out in the air assisted drawing process as described in Japanese Patent No. 4751481 (Patent Document 2). program. The drawing temperature of the air-assisted drawing procedure should be preset to 60-180 ° C, and the temperature set to 95-150 ° C is better. Moreover, the draw ratio of the air assisted drawing program should be set to 1.3 to 4 times, and it is preferably set to 1.5 to 3 times. In addition, the processing temperature of the wet drawing process after the air assisted drawing process is preferably 50 to 80 ° C, and 60 to 70 ° C is better, the immersion time is preferably 5 to 120 seconds, and 10 to 60 seconds is better. In addition, the drawing ratio of the wet drawing process should be set at a total stretching ratio of 4 to 7 times, preferably 5 to 6 times.

When the aforementioned drawing procedure includes an air-assisted drawing procedure and a wet drawing procedure, it is preferred to implement an air-assisted drawing procedure before the dyeing procedure and a wet drawing procedure after the dyeing procedure. At this time, the treatment bath for the wet drawing procedure doubles as a crosslinking bath, and a crosslinking procedure is carried out together with the wet drawing procedure.

<Crosslinking procedure>

The crosslinking procedure is carried out using a boron compound as a crosslinking agent. The cross-linking procedure can be carried out together with the dyeing procedure and the drawing procedure. The cross-linking process can be performed several times. Examples of the boron compound include boric acid, borax, and the like. The boron compound is generally used in the form of an aqueous solution or a water-organic solvent mixed solution. An aqueous boric acid solution is usually used. The boric acid concentration of the boric acid aqueous solution is about 1 to 10% by weight, and preferably 2 to 7% by weight. In order to impart heat resistance by the degree of crosslinking, it is preferred to set the boric acid concentration. An iodide such as potassium iodide may be contained in an aqueous solution of boric acid or the like. When the boric acid aqueous solution contains iodide, the concentration of the iodide used is preferably about 0.1 to 10% by weight, more preferably 0.5 to 8% by weight.

The crosslinking procedure can be carried out by immersing the above-mentioned laminate in an aqueous solution of boric acid or the like. The processing temperature of the cross-linking process is usually above 25 ° C, and It is preferably 30 to 85 ° C and more preferably in the range of 30 to 60 ° C. The processing time is usually 5 to 800 seconds, and it is preferably about 8 to 500 seconds.

<Other Programs>

In the method for producing a polarizer according to the present invention, the layered body can be subjected to a dyeing process and a drawing process, and a crosslinking process can be carried out. Further, the swelling procedure can be performed before the dyeing procedure is performed on the laminated body. Further, an insolubilization procedure can be performed before the dyeing procedure is performed on the laminate. The purpose of the insolubilization procedure is to carry out an insolubilization treatment for inactivating the polyvinyl alcohol layer at least in the dyeing process.

<insolubilization procedure>

The insolubilization process can be carried out by immersing the polyvinyl alcohol-based resin layer of the above-mentioned laminate in a solution containing a boron compound such as boric acid or borax. The foregoing solution is generally used in the form of an aqueous solution or a water-organic solvent mixed solution. An aqueous boric acid solution is usually used. The boric acid aqueous solution has a boric acid concentration of 1 to 4% by weight. The treatment temperature of the insolubilization process is usually 25 ° C or higher, preferably 30 to 85 ° C, and more preferably 30 to 60 ° C. The processing time is usually 5 to 800 seconds, and preferably about 8 to 500 seconds.

Further, the method for producing a polarizing member of the present invention may have a dyeing program, a drawing program, and may have a crosslinking program, and after performing the programs, a washing program may be carried out.

The washing procedure can be carried out using a potassium iodide solution. The potassium iodide concentration of the potassium iodide solution is usually from 0.5 to 10% by weight, further from 0.5 to 8% by weight, and further from 1 to 6% by weight.

For the washing procedure using potassium iodide solution, the processing temperature Usually 15~60 °C, and 25~40 °C is preferred. The immersion time is usually about 1 to 120 seconds, and is preferably in the range of 3 to 90 seconds. The stage of the washing procedure using the potassium iodide solution is not particularly limited as long as it is before the drying process.

Further, as a washing program, a water washing program can be carried out. The water washing procedure is usually carried out by immersing the polyvinyl alcohol-based film in pure water such as deionized water or distilled water. The water washing temperature is usually 5 to 50 ° C, preferably 10 to 45 ° C, and more preferably in the range of 15 to 40 ° C. The immersion time is usually 5 to 300 seconds, and preferably about 10 to 240 seconds.

The water washing procedure may also be a combination of a washing procedure using a potassium iodide solution and a water washing procedure, and a solution in which a liquid alcohol such as methanol, ethanol, isopropanol, butanol or propanol is blended may be suitably used.

After the above respective procedures were carried out, a drying procedure was finally carried out to manufacture a polarizing member. The drying procedure appropriately sets the drying time and the drying temperature in accordance with the moisture content required for the obtained polarizing member (film). The drying temperature is usually controlled at 20 to 150 ° C, preferably in the range of 40 to 100 ° C. When the drying temperature is too low, the drying time becomes long and the production cannot be performed efficiently, which is not preferable. When the drying temperature is too high, the obtained polarizer deteriorates and deteriorates in optical characteristics and hue. The heating and drying time is usually about 1 to 5 minutes.

<Water-soluble antioxidant>

The method of producing a polarizing member of the present invention is carried out by at least one treatment bath containing a water-soluble antioxidant in at least one of the procedures after the dyeing procedure.

The above treatment using a treatment bath containing a water-soluble antioxidant is performed by the respective procedures performed on the laminate after the dyeing process. At least one of the baths used contains a water-soluble antioxidant, or a treatment procedure using the treatment liquid containing a water-soluble antioxidant is additionally carried out. The above treatment using a treatment bath containing a water-soluble antioxidant is preferably carried out together with a crosslinking procedure and/or a drawing procedure.

Further, the aforementioned cross-linking program or drawing program can be performed by performing a merging process of a plurality of programs at the same time. When a combined procedure for simultaneously performing a plurality of programs is performed, the bath used in the combined procedure may contain a water-soluble antioxidant. Further, when the respective procedures of the cross-linking program and the drawing program are multi-stage programs, at least one of the multi-stage programs may contain a water-soluble antioxidant.

Examples of the water-soluble antioxidant include ascorbic acid (vitamin C), erythorbic acid, thiosulfuric acid, sulfurous acid, chlorogenic acid, citric acid, rosmarinic acid, and the like. The salt may, for example, be an alkali metal salt such as a sodium salt or a potassium salt. Among them, ascorbic acid, isoascorbate, thiosulfate, and sulfite are preferred. These water-soluble antioxidants may be used alone or in combination of two or more.

The amount of the water-soluble antioxidant added is determined according to the contamination concentration of the dichroic substance (iodine or dichroic dye) contained in each treatment bath after the dyeing process. When the contamination concentration of the dichroic substance in the pollution treatment bath is high, the amount of the added water-soluble antioxidant is also increased. Usually, in each treatment bath, it is preferred to add a water-soluble antioxidant to a concentration of 0.005 to 1% by weight, more preferably 0.005 to 0.5% by weight. When the concentration of the water-soluble antioxidant is less than 0.005% by weight, the ratio of the water-soluble antioxidant in the contamination treatment bath is reduced, and the characteristics of the obtained polarizer cannot be sufficiently suppressed (monomer penetration) Reduction in rate, degree of polarization). On the other hand, when the concentration of the water-soluble antioxidant exceeds 1% by weight, the ratio of the water-soluble antioxidant in the bath increases, and the polarizing member obtained is decolored, and the transmittance is improved, which causes concern about the iodine of the dye bath. The necessity of increasing the concentration, but in terms of optical characteristics, there is no problem such as reduction.

The polarizing member obtained by the production method of the present invention is formed on a thermoplastic resin substrate. The thermoplastic resin substrate can be directly used as a transparent protective film of a polarizing plate. On the other hand, the transparent protective film can be attached to the side of the non-thermoplastic resin substrate. Further, after the thermoplastic resin substrate is peeled off from the polarizing member, the transparent protective film may be attached to both sides of the polarizing member.

As the material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, water barrier property, and isotropic property can be used. Specific examples of such a thermoplastic resin include cellulose resins such as triacetyl cellulose, polyester resins, polyether oxime resins, polyfluorene resins, polycarbonate resins, polyamide resins, and polyimide resins. Polyolefin resin, (meth)acrylic resin, cyclic polyolefin resin A mixture of an olefinic resin, a polyarylate resin, a polystyrene resin, a polyvinyl alcohol resin, and the like. Further, a transparent protective film is bonded to one side of the polarizer by an adhesive, and the other side can be made of (meth)acrylic, urethane, urethane, epoxy or oxime. A thermosetting resin such as oxygen or an ultraviolet curable resin.

The thickness of the transparent protective film can be appropriately determined by weight, and is usually about 1 to 500 μm in terms of handling properties such as strength and handling properties and thin layer properties. It is preferably 1 to 300 μm, more preferably 5 to 200 μm. Transparent guarantee It is especially desirable when the protective film is 10 to 100 μm.

Further, when a transparent protective film is provided on both sides of the polarizing member, a protective film formed of the same polymer material may be used for the front and back surfaces, and a protective film formed of a different polymer material or the like may be used.

As the transparent protective film, a phase difference plate having a front phase difference of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled within the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled within the range of 80 to 300 nm. When a phase difference plate is used as the transparent protective film, the phase difference plate also has a function of a transparent protective film, so that it can be made thinner.

Examples of the phase difference plate include a birefringent film formed by subjecting a polymer material to uniaxial or biaxial stretching treatment, an oriented film of a liquid crystal polymer, and a material obtained by supporting an alignment layer of a liquid crystal polymer with a film. The thickness of the phase difference plate is also not particularly limited, and is usually about 20 to 150 μm.

Further, the film having the phase difference described above can be additionally bonded to a transparent protective film having no phase difference to impart the above functions.

The transparent protective film may also be subjected to surface modification treatment before applying the adhesive. Specific treatments include corona treatment, plasma treatment, primer treatment, saponification treatment and the like.

The surface of the transparent protective film on which the polarizing member is not bonded may be subjected to a hard coating treatment, an anti-reflection treatment, a treatment for preventing sticking or diffusion, or even anti-glare.

The bonding process of the polarizing member and the transparent protective film can be used Adhesive. Examples of the adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, and an aqueous polyester. The above-mentioned adhesive is usually used in the form of an adhesive formed of an aqueous solution, and usually contains 0.5 to 60% by weight of a solid component. In addition to the above, examples of the adhesive of the polarizer and the transparent protective film include an ultraviolet curing adhesive, an electron beam curing adhesive, and the like. The adhesive for the electron beam curing type polarizing plate exhibits appropriate adhesion to the above various transparent protective films. In particular, the acrylic resin which is difficult to satisfy the adhesiveness also exhibits good adhesion. Further, the adhesive used in the present invention may contain a metal compound filler.

The polarizing plate of the present invention is produced by laminating the transparent protective film and a polarizing member using the above-mentioned adhesive. The adhesive may be applied to either the transparent protective film or the polarizing member, or may be applied to both. After bonding, a drying process is performed to form an adhesive layer composed of a coated dry layer. The bonding of the polarizing member and the transparent protective film can be carried out by a roll laminator or the like. The thickness of the adhesive layer is not particularly limited and is usually about 30 to 1000 nm.

The polarizing plate of the present invention can be used in combination with other optical layers to form an optical film in practical use. The optical layer is not particularly limited. For example, one or two or more reflective plates, semi-transmissive plates, phase difference plates (including 1/2, 1/4 wavelength plates, etc.), viewing angle compensation films, and the like can be used to form a liquid crystal display device. An optical layer that is used isochronously. In particular, the polarizing plate of the present invention further comprises a reflective polarizing plate or a semi-transmissive polarizing plate which is formed by a reflective plate or a semi-transmissive reflecting plate, and an elliptically polarizing plate or a circular polarizing plate which is formed by laminating a phase difference plate on the polarizing plate. a wide viewing angle polarizing plate formed by recombining a viewing angle compensation film on a polarizing plate, Or a polarizing plate formed by thickening a film on a polarizing plate.

An optical film in which the optical layer is laminated on a polarizing plate can be formed by sequentially laminating layers in a manufacturing process of a liquid crystal display device or the like. However, the optical film is laminated in advance to have excellent quality stability and assembly operation. Further, the advantages of the manufacturing procedure of the liquid crystal display device or the like can be improved. The laminate can be suitably bonded using an adhesive layer or the like. When the polarizing plate or other optical film is bonded, the optical axis thereof can be set to an appropriate arrangement angle according to the target phase difference characteristic or the like.

The polarizing plate or the optical film laminated with at least one polarizing plate may be provided with an adhesive layer for bonding to other members such as a liquid crystal cell. The adhesive for forming the adhesive layer is not particularly limited, and may be appropriately selected, for example, an acrylic polymer, a siloxane polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine or a rubber. The polymer is a binder of the base polymer. In particular, it is preferable to use an adhesive such as an acrylic adhesive which is excellent in optical transparency, and exhibits excellent wettability, adhesion properties of adhesion and adhesion, and excellent weather resistance and heat resistance.

Attaching an adhesive layer to one or both sides of the polarizing plate or the optical film can be carried out in an appropriate manner. For example, a solvent in which a base polymer or a composition thereof is dissolved or dispersed in a single one or a mixture of a suitable solvent such as toluene or ethyl acetate, and a binder solution of about 10 to 40% by weight is prepared. And the solution is directly attached to the polarizing plate or the optical film by a suitable expansion method such as casting or coating; or, an adhesive layer is formed on the separator according to the foregoing, and then transferred to a polarizing plate or optically The way on the film, etc.

The adhesive layer may also be formed by stacking layers of different compositions or types, such as a superimposed layer on one or both sides of the polarizing plate or the optical film. Further, when it is provided on both sides, an adhesive layer having a different composition, type, thickness, or the like may be provided on the front and back surfaces of the polarizing plate or the optical film. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use, adhesion, etc., and is usually 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

For the exposed surface of the adhesive layer, in order to prevent its contamination, the separator is temporarily adhered to cover it until it is supplied for practical use. Thereby, it is possible to prevent contact with the adhesive layer in a normal treatment state. As the separator, in addition to the above thickness conditions, a conventionally applicable separator such as a plastic film, a rubber sheet, paper, cloth, non-woven fabric, net, foamed sheet or metal foil, laminate thereof, or the like can be used. A suitable thin layer body, if necessary, a separator obtained by coating treatment with a suitable stripping agent such as a halogen-based or long-chain alkyl group, a fluorine-based or a molybdenum sulfide.

Further, in the present invention, each of the polarizing plate-forming polarizing material, the transparent protective film, the optical film, and the like, and the adhesive layer may be, for example, a salicylate-based compound or a benzophenol-based compound. An ultraviolet absorbing ability or the like is imparted to a method such as a method of treating an ultraviolet absorber such as a benzotriazole-based compound, a cyanoacrylate-based compound or a nickel-salted salt-based compound.

The polarizing plate or the optical film of the present invention can be suitably used for formation of various devices such as a liquid crystal display device. The formation of the liquid crystal display device can be carried out in accordance with a conventional manner. That is, the liquid crystal display device is generally constituted by a liquid crystal cell, a polarizing plate or an optical film, and an illumination system used as needed. The components are appropriately assembled and incorporated in a drive circuit or the like. In the present invention, in addition to the use of the polarizing plate or the optical film of the present invention, it is not particularly limited and may be carried out in a conventional manner. For the liquid crystal cell, any type of liquid crystal cell such as a TN type, an STN type, or a π type can also be used.

A liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a liquid crystal display device in which a backlight or a reflecting plate is used for a liquid crystal display device of an illumination system can be formed. At this time, the polarizing plate or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When a polarizing plate or an optical film is provided on both sides, the same may be the same or different. Further, when forming a liquid crystal display device, one or two or more layers such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. may be disposed at appropriate positions. component.

Example

Hereinafter, the present invention will be specifically described by way of examples and comparative examples.

Example 1-1 (Process (1)) (layered body)

As the thermoplastic resin substrate, amorphous polyethylene terephthalate (NOVACLEAR, manufactured by Mitsubishi Plastics Co., Ltd.) having a thickness of 100 μm and a glass transition temperature of 80 ° C was used. An aqueous solution containing polyvinyl alcohol (average degree of polymerization 4200, saponification degree: 99.2%) at a concentration of 5% by weight was applied onto the thermoplastic resin substrate, and then dried at 60 ° C for 5 minutes to form a polyvinyl alcohol having a thickness of 10 μm. Layer, and get a layered body.

In each of the examples, the following procedures were carried out on the above laminated body in the following order.

(air assisted drawing procedure)

The laminate was longitudinally drawn to 1.8 times in an environment of 120 ° C using a drawing device equipped in an oven.

(insolubilization procedure)

The treatment solution of the insoluble bath used an aqueous solution containing 3% by weight of boric acid. The laminate which was subjected to the above-described aerial assisted drawing was transferred to an insolubilizing bath, and immersed in the treatment liquid adjusted to 30 ° C for 30 seconds.

(dyeing procedure)

As the treatment liquid for the dyeing bath, an iodine dyeing solution containing 0.3 parts by weight of iodine and 2 parts by weight of potassium iodide with respect to 100 parts by weight of water is used. The layered body subjected to the above insolubilization treatment was transferred to a dyeing bath, and immersed in the above iodine dyeing solution adjusted to 30 ° C to dye the polyvinyl alcohol layer.

(Crosslinking procedure / containing water-soluble antioxidants)

As the treatment liquid for the crosslinking bath, a mixed aqueous solution (1A) containing 3% by weight of boric acid, 3% by weight of potassium iodide, and 0.1% by weight of ascorbic acid as a water-soluble antioxidant was used. The laminate which had been subjected to the above treatment was transferred to a crosslinking bath, and immersed in the above mixed aqueous solution (1A) adjusted to 30 ° C for 30 seconds.

(wet drawing procedure)

As the treatment liquid for the draw bath, a mixed aqueous solution (1B) containing 4% by weight of boric acid and 5% by weight of potassium iodide was used. The laminated body subjected to the above treatment is transferred to a drawing bath, immersed in a mixed aqueous solution (1B) adjusted to 70 ° C for 30 seconds, and uniaxially drawn to a total stretching through a plurality of sets of rolls having different peripheral speeds. The magnification is 5.5 times the original length.

(washing procedure)

As the treatment liquid for the washing bath, an aqueous solution containing 4% by weight of potassium iodide was used. The layered body subjected to the above treatment was transferred to a washing bath, and immersed in the treatment liquid adjusted to 30 ° C for 5 seconds.

(drying procedure)

Next, the laminate subjected to the above washing treatment was taken out from the washing bath, and dried by a warm air at 60 ° C for 4 minutes to prepare a polarizing member on a thermoplastic resin substrate. The polyvinyl alcohol layer (polarizer) which was integrally drawn with the thermoplastic resin substrate had a thickness of 5 μm.

Examples 1-2 to 4 and Comparative Examples 1-1 to 3

Except that the concentration of the water-soluble antioxidant (ascorbic acid) blended in the mixed aqueous solution (1A) used in the treatment liquid of the crosslinking bath in Example 1-1 was changed as shown in Table 1, 1 The polarizer is made under the same conditions. In addition, Table 1 also shows the elapsed time of the continuous implementation of the process (1).

Example 2-1 (Process (2)) (layered body)

As the thermoplastic resin substrate, amorphous polyethylene terephthalate (NOVACLEAR, manufactured by Mitsubishi Plastics Co., Ltd.) having a thickness of 100 μm and a glass transition temperature of 80 ° C was used. An aqueous solution containing polyvinyl alcohol (average degree of polymerization 4200, saponification degree: 99.2%) at a concentration of 5% by weight was applied onto the thermoplastic resin substrate, and then dried at 60 ° C for 5 minutes to form a polyvinyl alcohol having a thickness of 10 μm. Layer, and get a layered body.

In each of the examples, the above laminated body is implemented in the following order. List each program.

(air assisted drawing procedure)

The laminate was longitudinally stretched to 1.8 times in an environment of 120 ° C using a drawing device equipped in an oven.

(insolubilization procedure)

The treatment liquid of the insoluble bath used an aqueous solution containing 3 wt% of boric acid. The laminate which was subjected to the above-described aerial assisted drawing was transferred to an insolubilizing bath, and immersed in the treatment liquid adjusted to 30 ° C for 30 seconds.

(dyeing procedure)

As the treatment liquid for the dyeing bath, an iodine dyeing solution containing 0.3 parts by weight of iodine and 2 parts by weight of potassium iodide with respect to 100 parts by weight of water is used. The layered body subjected to the above insolubilization treatment was transferred to a dyeing bath, and immersed in the above iodine dyeing solution adjusted to 30 ° C to dye the polyvinyl alcohol layer.

(cross-linking procedure)

As the treatment liquid for the crosslinking bath, a mixed aqueous solution (2A) containing 3% by weight of boric acid and 3% by weight of potassium iodide was used. The laminate which had been subjected to the above treatment was transferred to a crosslinking bath, and immersed in the above mixed aqueous solution (2A) adjusted to 30 ° C for 30 seconds.

(wet drawing procedure / containing water-soluble antioxidants)

As the treatment liquid for the drawing bath, a mixed aqueous solution (2B) containing 4% by weight of boric acid, 5% by weight of potassium iodide, and 0.02% by weight of ascorbic acid as a water-soluble antioxidant was used. The laminated body subjected to the above treatment is transferred to a drawing bath, immersed in a mixed aqueous solution (2B) adjusted to 70 ° C for 30 seconds, and passed through a plurality of sets of rolls having different peripheral speeds, and uniaxially drawn to the total stretching ratio. Length of 5.5 Times.

(washing procedure)

As the treatment liquid for the washing bath, an aqueous solution containing 4% by weight of potassium iodide was used. The layered body subjected to the above treatment was transferred to a washing bath, and immersed in the treatment liquid adjusted to 30 ° C for 5 seconds.

(drying procedure)

Next, the laminate subjected to the above washing treatment was taken out from the washing bath, and dried by a warm air at 60 ° C for 4 minutes to prepare a polarizing member on a thermoplastic resin substrate. The polyvinyl alcohol layer (polarizer) which was integrally drawn with the thermoplastic resin substrate had a thickness of 5 μm.

Example 2-2, Comparative Example 2-1~2

Except that the water-soluble antioxidant (ascorbic acid) and the concentration of the mixed aqueous solution (2B) used in the treatment bath of the drawing bath in Example 2-1 were changed as shown in Table 1, 1 The polarizer is made under the same conditions. In addition, Table 1 also shows the elapsed time of continuous implementation of the process (2).

Example 3-1 (Process (3)) (layered body)

As the thermoplastic resin substrate, amorphous polyethylene terephthalate (NOVACLEAR, manufactured by Mitsubishi Plastics Co., Ltd.) having a thickness of 100 μm and a glass transition temperature of 80 ° C was used. An aqueous solution containing polyvinyl alcohol (average degree of polymerization 4200, saponification degree: 99.2%) at a concentration of 5% by weight was applied onto the thermoplastic resin substrate, and then dried at 60 ° C for 5 minutes to form a polyvinyl alcohol having a thickness of 10 μm. Layer, and get a layered body.

In each of the examples, the above laminated body is implemented in the following order. List each program.

(air assisted drawing procedure)

The laminate was longitudinally stretched to 1.8 times in an environment of 120 ° C using a drawing device equipped in an oven.

(insolubilization procedure)

The treatment liquid of the insoluble bath used an aqueous solution containing 3 wt% of boric acid. The laminate which was subjected to the above-described aerial assisted drawing was transferred to an insolubilizing bath, and immersed in the treatment liquid adjusted to 30 ° C for 30 seconds.

(dyeing procedure)

As the treatment liquid for the dyeing bath, an iodine dyeing solution containing 0.3 parts by weight of iodine and 2 parts by weight of potassium iodide with respect to 100 parts by weight of water is used. The laminate which was subjected to the above insolubilization treatment was transferred to a dye bath, and immersed in the above iodine dyeing solution adjusted to 30 ° C to dye the polyvinyl alcohol layer.

(wet drawing procedure / containing water-soluble antioxidants)

As the treatment liquid for the draw bath, a mixed aqueous solution (3A) containing 4% by weight of boric acid, 5% by weight of potassium iodide, and 0.02% by weight of ascorbic acid as a water-soluble antioxidant was used. The laminated body subjected to the above treatment is transferred to a drawing bath, immersed in a mixed aqueous solution (3A) adjusted to 70 ° C for 30 seconds, and passed through a plurality of sets of rolls having different peripheral speeds, and uniaxially drawn to the total stretching ratio. The original length is 5.5 times.

(washing procedure)

As the treatment liquid for the washing bath, an aqueous solution containing 4% by weight of potassium iodide was used. The layered body subjected to the above treatment was transferred to a washing bath, and immersed in the treatment liquid adjusted to 30 ° C for 5 seconds.

(drying procedure)

Next, the laminate subjected to the above washing treatment was taken out from the washing bath, and dried by a warm air at 60 ° C for 4 minutes to prepare a polarizing member on a thermoplastic resin substrate. The polyvinyl alcohol layer (polarizer) which was integrally drawn with the thermoplastic resin substrate had a thickness of 5 μm.

Example 3-2, Comparative Example 3-1~2

Except that the water-soluble antioxidant (ascorbic acid) and the concentration of the mixed aqueous solution (3A) used in the treatment liquid of the drawing bath in Example 3-1 were changed as shown in Table 1, 1 The polarizer is made under the same conditions. In addition, Table 1 also shows the elapsed time of continuous implementation of the process (3).

Example 4-1 (Process (4)) (layered body)

As the thermoplastic resin substrate, a cycloolefin polymer (ARTON, manufactured by JSR Corporation) having a thickness of 100 μm was used. An aqueous solution containing polyvinyl alcohol (average degree of polymerization 1800, saponification degree: 99.2%) at a concentration of 10% by weight was applied onto the thermoplastic resin substrate, and then dried at 60 ° C for 5 minutes to form a polyvinyl alcohol having a thickness of 10 μm. Layer, and get a layered body.

In each of the examples, the following procedures were carried out on the above laminated body in the following order.

(dry drawing procedure)

The laminate was stretched laterally to 4 times in an environment of 140 ° C by a tenter method.

(dyeing procedure)

The treatment liquid for the dyeing bath is used in an amount of 100 parts by weight relative to water. Iodine dyeing solution of 0.5 parts by weight of iodine and 4 parts by weight of potassium iodide. The laminate which was subjected to the above dry drawing was conveyed to a dyeing bath, and immersed in the above iodine dyeing solution adjusted to 30 ° C to dye the polyvinyl alcohol layer.

(cross-linking procedure)

As the treatment liquid for the crosslinking bath, a mixed aqueous solution (4A) containing 5% by weight of boric acid, 5% by weight of potassium iodide, and 0.02% by weight of ascorbic acid as a water-soluble antioxidant was used. The layered body subjected to the above treatment was transferred to a crosslinking bath, and immersed in the above mixed aqueous solution (4A) adjusted to 60 ° C for 60 seconds.

(washing procedure)

As the treatment liquid for the washing bath, an aqueous solution containing 4% by weight of potassium iodide was used. The layered body subjected to the above treatment was transferred to a washing bath, and immersed in the treatment liquid adjusted to 30 ° C for 5 seconds.

(drying procedure)

Next, the laminate subjected to the above washing treatment was taken out from the washing bath, and dried by a warm air at 60 ° C for 4 minutes to prepare a polarizing member on a thermoplastic resin substrate. The polyvinyl alcohol layer (polarizer) which was integrally drawn with the thermoplastic resin substrate had a thickness of 3 μm.

Comparative Example 4-1~2

Except that the water-soluble antioxidant (ascorbic acid) and the concentration of the mixed aqueous solution (3A) used in the treatment bath of the drawing bath in Example 4-1 were changed as shown in Table 1, 1 The polarizer is made under the same conditions. In addition, Table 1 also shows the elapsed time of the continuous implementation of the process (4).

<Production of polarizing plate>

Triethyl fluorene cellulose (FUJIFILM Corporation) via adhesive TD80UL) was applied to the surface of the polyvinyl alcohol layer of the laminate (the polyvinyl alcohol layer (polarizer) formed on the thermoplastic resin substrate) obtained in the above Examples and Comparative Examples, and dried at 80 ° C. 5 minutes. As the above-mentioned binder, a 3% by weight aqueous solution of polyvinyl alcohol resin (GOHSEFIMER Z200 manufactured by Nippon Synthetic Co., Ltd.) was used.

(Evaluation)

The optical characteristics of the polarizing members obtained in the examples and the comparative examples were measured by the following methods. The results are shown in Table 1.

"Iodine concentration of adding bath (treatment liquid)"

It is described that each process is continuously carried out (except that in the examples, it is assumed that the value of the water-soluble antioxidant is not added, for example, in Example 1, it is assumed to be the same iodine concentration as in Comparative Example 1). The iodine concentration in each of the added baths is for reference. The iodine concentration was measured by measuring the absorbance of the solution from the vicinity of the wavelength of 350 nm of the I ₃ ^- ion when the solution of each treatment bath was diluted 5 times.

The calculation formula was determined by measuring the absorbance of a solution having a constant iodine concentration to prepare a calibration curve. The calibration curve is as follows.

Iodine concentration [%] = (0.51 × absorbance (5 times diluted solution)) / 100

<Absorbance of adding bath (treatment liquid)>

After each process was carried out continuously (after the lapse of time), the solution of each bath was diluted 5 times, and the absorption spectrum at an optical path length of 10 mm was measured using a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation). It is derived from the absorbance near the wavelength of 350 nm of the I ₃ ^- ion. Further, the absorbances shown in Table 1 were obtained by diluting the aqueous solution of each of the addition baths to 5 times. In addition, even if it was impossible to measure by 5 times dilution, it was further diluted, and the obtained measured value was multiplied by the dilution ratio, and the absorbance at the time of 5-fold dilution was calculated.

Further, the solution of the treatment bath containing a water-soluble antioxidant preferably has an absorbance at a wavelength of around 350 nm of 10 or less. More preferably, the absorbance is varied depending on the temperature required for the treatment bath to which the antioxidant is added, so that the higher the temperature of the treatment bath, the lower the absorbance. For example, when the temperature of the treatment bath is 30 ° C, the absorbance is preferably 10 or less, and at 70 ° C, the absorbance is preferably 2 or less. The particularly good absorbance corresponding to the aforementioned temperature can be set by a pretest.

<Method for measuring optical characteristics>

The monomer transmittance (Ts) and the degree of polarization (P) of the polarizer were measured by a spectrophotometer (V7100, manufactured by JASCO Corporation) with an integrating sphere.

In addition, the degree of polarization is overlapped by overlapping the two polarizing elements with the same polarization axis parallel to each other (parallel transmittance: Tp), and the transmission axis of the two is perpendicular to each other. The transmittance at the time (vertical transmittance: Tc) is obtained by applying the following formula.

Polarization P(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

Each transmittance is set to 100% by the Glan-Taylor prism polarizer, and then corrected for luminosity by the 2 degree field of view (C light source) of JIS Z8701. The value is expressed.

In Table 1, "initial" means a state in which the characteristics have not been lowered by the iodide ion (I ₃ ^- ) in the bath after the preparation of the solution, and particularly, the iodide ion concentration is 0.01% or less. Even in the initial state, a part of potassium iodide added to the light absorption system bath forms I ₃ ^- ions.

From the comparison of the "initial" of each of the examples 1 to 4 and the comparative examples 1 to 4-1, it is understood that the embodiment satisfies the same optical as the "initial" even when the polarizing member is manufactured for a long period of time. Characteristics (polarity and monomer penetration). Further, in the examples and comparative examples, the dyeing procedure was carried out so that the polarizing degree of the polarizing member was 99.99, and the transmittance at the same polarizing degree was compared as a characteristic. Therefore, if it is a polarizer of the same transmittance, the degree of polarization will be lowered.

Claims (12)

A method for producing a polarizing member is characterized in that a laminate comprising a polyvinyl alcohol-based resin layer formed on a thermoplastic resin substrate is subjected to at least a dyeing procedure and a drawing procedure to produce a polarizer having a thickness of 10 μm or less. In the at least one procedure after the dyeing process, the treatment is carried out at least once with a treatment bath containing a water-soluble antioxidant; wherein the water-soluble antioxidant comprises ascorbic acid, isoascorbate, sulfurous acid, chlorogenic acid At least one of rosmarinic acid and salts thereof. The method for producing a polarizing member according to claim 1, wherein the dyeing procedure is an iodine dyeing procedure. The method of producing a polarizing member according to claim 1, wherein at least one of the processes after the dyeing process comprises a crosslinking process in a crosslinking bath. The method for producing a polarizing member according to claim 3, wherein the crosslinking bath contains the water-soluble antioxidant. The method for producing a polarizing material according to the first aspect of the invention, wherein the treatment liquid of the treatment bath containing a water-soluble antioxidant has an absorbance at a wavelength of about 350 nm of 10 or less when measured in a 5-fold diluted solution. The method of manufacturing a polarizing member according to any one of claims 1 to 5, wherein the drawing process comprises an air assist drawing process performed before the dyeing process, and a wet type performed after the dyeing process. Extension process sequence. The method for producing a polarizing member according to claim 6, wherein the treatment bath used in the wet drawing process doubles as a crosslinking bath. The method of manufacturing a polarizing member according to any one of claims 1 to 5, wherein the drawing process comprises a dry drawing process performed before the dyeing process. A polarizing member is produced by the manufacturing method according to any one of claims 1 to 8. A polarizing plate characterized by having a transparent protective film on at least one side of a polarizing member according to claim 9 of the patent application. An optical film characterized by having a polarizing member as in claim 9 or a polarizing plate as in claim 10 of the patent application. An image display device comprising the polarizing member of claim 9 of the patent application, the polarizing plate of claim 10 or the optical film of claim 11 of the patent application.