WO2020175372A1

WO2020175372A1 - Manufacturing method for polarizer, manufacturing method for polarizing film, manufacturing method for laminated polarizing film, manufacturing method for image display panel, and manufacturing method for image display device

Info

Publication number: WO2020175372A1
Application number: PCT/JP2020/007068
Authority: WO
Inventors: 拓馬黒田; 山下　智弘; 尾込　大介; 麻未萩原
Original assignee: 日東電工株式会社
Priority date: 2019-02-26
Filing date: 2020-02-21
Publication date: 2020-09-03
Also published as: JP6772402B1; CN112041715A; KR20210130626A; JPWO2020175372A1

Abstract

This method is for manufacturing a polarizer by performing a drying step on a polyvinyl alcohol film after performing at least a dyeing step, a crosslinking step, and an extension step thereon, wherein: at least one processing bath contains a zinc ion; the drying step is for, by drying the polyvinyl alcohol film containing zinc while transferring the film by a plurality of rollers, manufacturing a polarizer having a thickness of not more than 20 µm and a moisture percentage of 13-19 wt%; the plurality of rollers include one or more third rollers provided between a first roller provided to the uppermost stream side and a second roller provided to the downmost stream side; and at least one of the one or more third rollers has a holding angle of not more than 90° between said roller and the polyvinyl alcohol film. The manufacturing method makes it possible to suppress abnormality of external appearance (polarization unevenness) and breakage generated in the drying step, and a thin-type polarizer having heating durability can be obtained.

Description

\¥0 2020/175372 1 ?<:17 2020/007068

Specification

Title of invention:

Polarizer manufacturing method, polarizing film manufacturing method, laminated polarizing film manufacturing method, image display panel manufacturing method, and image display device manufacturing method

Technical field

The present invention relates to a method for manufacturing a polarizer, a method for manufacturing a polarizing film, a method for manufacturing a laminated polarizing film, a method for manufacturing an image display panel, and a method for manufacturing an image display device.

Background technology

[0002] Conventionally, as a polarizer used in various image display devices such as liquid crystal display devices and organic solar display devices, it has been dyed because of its high transmittance and high polarization degree. Polyvinyl alcohol-based film is used. The polarizer is produced by subjecting a polyvinyl alcohol film to various treatments such as dyeing, crosslinking and stretching in a bath, followed by drying. Further, the above-mentioned polarizer is usually used as a polarizing film (polarizing plate) having a protective film such as triacetylcellulose bonded to one side or both sides thereof with an adhesive.

[0003] The polarizing film is used as a laminated polarizing film (optical laminated body) by laminating other optical layers, if necessary, and the polarizing film or the laminated polarizing film (optical laminated body) is a liquid crystal cell. It is used as the above various image display devices by laminating an image display cell such as an organic display device and an organic display device and a transparent plate such as a front plate and a touch panel on the viewing side via an adhesive layer.

[0004] On the other hand, it is known that the polarizer contains zinc from the viewpoint of improving the heating durability (Patent Documents 1 to 6). Further, in the drying step in the production of a polarizer, it is known that a polyvinyl alcohol-based film is dried while being conveyed by a plurality of holes to obtain a polarizer (Patent Documents 7 to 10). Prior art documents \¥0 2020/175372 2 (: 17 2020/007068 Patent Document

Patent Document 1: Japanese Patent Laid-Open No. 20 09 _ 4 2 4 5 7

Patent Document 2: Japanese Patent Laid-Open No. 20 09 _ 4 2 4 5 5

Patent Document 3: JP 2 0 0 6 _ 3 1 7 7 4 7 Publication

Patent Document 4: Japanese Patent Laid-Open No. 20 06 _ 4 7 9 7 8

Patent Document 5: Japanese Patent Laid-Open No. 2 0 4 _ 6 1 5 6 5

Patent Document 6: JP 20000 3 _ 2 7 0 4 3 9 Publication

Patent Document 7: JP 20 1 4 _ 1 9 9 2 8 4

Patent Document 8: JP 2 0 1 2-4 7 7 9 9 Publication

Patent Document 9: JP 2 0 1 2 _ 1 4 0 0 1 Publication

Patent Document 10: Japanese Patent Laid-Open No. 2 0 0 9 -1 6 3 2 0 2

Summary of the invention

Problems to be Solved by the Invention

[0006] In recent years, with the widespread use in various image display devices as described above (mobile devices such as mobile phones and tablet terminals, vehicle-mounted image display devices such as navigation devices and back monitors), There is a demand for higher quality and higher performance of the polarizing film, and in particular, a thin polarizer having heat resistance is desired.

[0007] On the other hand, the polarizer obtained by the manufacturing method disclosed in the above patent documents has good optical characteristics. However, when a thin polarizer containing zinc is produced by the method for producing a polarizer disclosed in the above-mentioned patent documents, the obtained polarizer has an abnormal appearance (polarized light) on its surface during the drying process. It has been found that there are problems such as non-uniformity) and insufficient heating durability despite the fact that the polarizer contains zinc.

In view of the circumstances as described above, the present invention is directed to the production of a polarizer capable of obtaining a thin polarizer having suppressed appearance abnormality (polarization unevenness) and breakage occurring in a drying step and having heating durability. The purpose is to provide a method. 〇 2020/175372 3 units (:171? 2020/007068 Means for solving problems

That is, the present invention relates to a method for producing a polarizer, which is obtained by subjecting a polyvinyl alcohol film to at least a dyeing step, a crosslinking step, and a stretching step, and then a drying step. At least one treatment bath in the step, the cross-linking step, and the stretching step contains zinc ions, and in the drying step, the polyvinyl alcohol-based film containing zinc is dried while being conveyed by a plurality of holes, It is a step of producing a polarizer having a thickness of 20 or less and a moisture content of 13% by weight or more and 19% by weight or less, wherein the plurality of holes are in the transport direction of the polyvinyl alcohol-based film. The first port provided on the most upstream side, the second port provided on the most downstream side in the conveying direction of the polyvinyl alcohol film, the first port and the second port At least one of the one or more third holes is provided between the polyvinyl alcohol-based film and the polyvinyl alcohol-based film. The present invention relates to a method for manufacturing a polarizer, which has an included angle of 90 ^° or less.

[0010] Further, the present invention provides a polarizing film characterized by including a step of attaching a transparent protective film to at least one surface of the polarizer obtained by the above-mentioned method for producing a polarizer with an adhesive layer interposed therebetween. Manufacturing method.

[001 1] The present invention also relates to a method for producing a laminated polarizing film, which comprises a step of laminating an optical layer on the polarizing film obtained by the method for producing a polarizing film.

[0012] Further, the present invention includes a step of laminating a polarizing film obtained by the method for producing a polarizing film or a laminated polarizing film obtained by the method for producing a laminated polarizing film to an image display cell. The present invention relates to a method of manufacturing an image display panel characterized by.

[0013] Further, the present invention provides an image display device including a step of providing a transparent plate on the polarizing film or laminated polarizing film side of the image display panel obtained by the method for producing an image display panel. Manufacturing method.

Effect of the invention 〇 2020/175372 4 (:171? 2020/007068

[0014] The details of the mechanism of action of the effect in the method for producing a polarizer of the present invention are unknown, but it is presumed as follows. However, the present invention may not be construed as being limited to this mechanism of action.

The method for producing a polarizer of the present invention is a method for producing a polarizer obtained by subjecting a polyvinyl alcohol-based film to at least a dyeing step, a crosslinking step, and a stretching step, followed by a drying step. At least one treatment bath in the dyeing step, the crosslinking step, and the stretching step contains zinc ions, and in the drying step, a polyvinyl alcohol-based film containing zinc is conveyed by a plurality of holes. While being dried, it is a step of producing a polarizer having a thickness of 20 or less and a moisture content of 13% by weight or more and 19% by weight or less, wherein the plurality of holes are polyvinyl alcohol. The first port provided on the most upstream side in the transport direction of the system film, the second port provided on the most downstream side in the transport direction of the polyvinyl alcohol film, the first port and the At least one of the one or more third rolls includes at least one third roll provided between the second rolls. The wrapping angle with the polyvinyl alcohol film is 90 ^° or less. In the present invention, by adjusting the water content of the thin polarizer obtained in the drying step to the above value, abnormal appearance (polarization unevenness) occurring in the drying step can be suppressed, and heating of the thin polarizer can be suppressed. The durability can be improved.

[0016] The reason for this is that a polarizer having a moisture content of a certain level or more is more flexible than a polarizer having a low moisture content, and therefore zinc deposited on the surface of the polyvinyl alcohol film during the drying step is a It is presumed that this is because abnormal appearance (polarization unevenness) due to surface deformation of the polarizer caused by being crushed by the mouth pressure) can be suppressed. Since the above-mentioned polarizer containing a moisture content below a certain level has a small total water content in the polarizer, it is estimated that the deterioration of the polarizer due to the water content in the polarizer due to the heat resistance test can be suppressed. Has heating durability. In particular, when a protective film with low moisture permeability is used as the protective film in the polarizing film, it is difficult for moisture in the polarizer to permeate to the outside. 〇 2020/175372 5 卩 (: 171-1? 2020 /007068

It is useful for such an embodiment.

Furthermore, the present invention avoids the influence of the mouth pressure as described above as much as possible, and suppresses the above-mentioned abnormal appearance (uneven polarization) by using a polyvinyl alcohol film and a mouth (conveying mouth). In order to reduce the contact time with the film, the angle of wrap between the mouth and the polyvinyl alcohol film is adjusted to a certain value or less. In particular, when the polarizer is dried, it is presumed that the appearance abnormality (polarization unevenness) can be suppressed by adjusting the angle of wrapping between the third film and the polyvinyl alcohol film to a certain value or less. The above-mentioned 1st and 2nd mouths are the mouths immediately after drying and immediately before the end of drying, and the influence of mouth pressure due to the angle of wrapping during the drying operation (treatment) is small. It is estimated that

[0018] In addition, according to the present invention, since the above-mentioned third mouth is provided in the drying step, the distance between adjacent mouths (idling distance) does not become excessively long. It is estimated that the polyvinyl alcohol-based film in the inside can suppress the occurrence of bending of the polarizer because the deflection is small.

[0019] Also, in the present invention, in the above-mentioned drying step, a contact distance of the polyvinyl alcohol-based film containing zinc to the third roll, and a total transport distance of the polyvinyl alcohol-based film containing zinc. By adjusting the ratio (contact distance / total transport distance) to 0.1 or less, the contact time between the polyvinyl alcohol film and the mouth (conveyor mouth) can be reduced. It is estimated that abnormal appearance (uneven polarization) due to surface deformation of the child can be further suppressed.

[0020] Further, the present invention provides the maximum distance between the plurality of mouths.

By adjusting the ratio (L _MAX /W ₁ ) of the width of the polyvinyl alcohol-based film containing zinc before the drying step () to 2 or less, the polyvinyl alcohol-based film between adjacent pores can be adjusted. It is presumed that it is possible to further suppress the occurrence of polyvinyl alcohol-based film breakage that occurs during the transport distance (idling distance) of.

[0021] The polarizer obtained by the production method of the present invention is made of a zinc-containing poly-amine before the drying step. 〇 2020/175372 6 卩 (：171? 2020 /007068

Ratio of the width (V) of vinyl alcohol film to the width ₂ ) of the polarizer obtained after the drying process

However, since it is 0.9 or more and less than 1, it is presumed that the shrinkage in the width direction of the polarizer during the drying process can be suppressed and the generation of wrinkles and the like at the ends of the polarizer can be suppressed.

Brief description of the drawings

[0022] [Fig. 1] Fig. 1 is a schematic view showing a wrapping angle between the mouth of the present invention and a polyvinyl alcohol film.

FIG. 2 is a conceptual diagram showing one embodiment in the drying step of the present invention.

FIG. 3 is a conceptual diagram showing a drying process used in Comparative Examples 3 and 7.

FIG. 4 is a conceptual diagram showing a drying step used in Comparative Example 4.

FIG. 5 is a conceptual diagram showing a drying step used in Example 5.

MODE FOR CARRYING OUT THE INVENTION

[0023] <Production Method of Polarizer>

The method for producing a polarizer of the present invention is a method for producing a polarizer obtained by subjecting a polyvinyl alcohol film to at least a dyeing step, a crosslinking step, and a stretching step, followed by a drying step. At least one treatment bath in the dyeing step, the crosslinking step, and the stretching step contains zinc ions, and the drying step is performed by drying a polyvinyl alcohol-based film containing zinc while being conveyed by a plurality of holes. Is a step of producing a polarizer having a thickness of 20 or less and a moisture content of 13% by weight or more and 19% by weight or less, wherein the plurality of holes are made of a polyvinyl alcohol film. The first port provided on the most upstream side in the transport direction, the second port provided on the most downstream side in the transport direction of the polyvinyl alcohol film, the first port and the second port At least one third of the one or more third mouths is provided between the mouth and the polyvinyl alcohol. The included angle with the system film is 90° or less.

[0024] The polyvinyl alcohol (eight)-based film has a light-transmitting property in the visible light region and is characterized by dispersing and adsorbing a dichroic substance such as iodine or a dichroic dye. 〇 2020/175372 7 卩(: 171-1? 2020/007068

It can be used without any restrictions. In addition, the octoline film, which is usually used as a raw fabric, preferably has a thickness of about 10 to 100,01, more preferably about 15 to 80^01, More preferably, the width is about 60 to about 60, and the width is preferably about 100 to 500,000!!.

[0025] Examples of the material of the polyvinyl alcohol film include polyvinyl alcohol and derivatives thereof. Examples of the polyvinyl alcohol derivatives include polyvinyl formal, polyvinyl acetal, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl esters thereof, acrylic amide, and the like. Examples include modified products. The polyvinyl alcohol preferably has an average degree of polymerization of about 100 to 100,000, more preferably about 1,100 to 100,000, and more preferably 2,0. It is even more preferable that it is about 0 to 4,500. The polyvinyl alcohol preferably has a saponification degree of about 80 to 100 mol %, and more preferably about 95 to 99.99 mol %. The average degree of polymerization and the degree of saponification can be determined according to the formula “3<6726.

[0026]The polyvinyl alcohol film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyols such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol, and condensates thereof. The amount of the additive used is not particularly limited, but is preferably about 20% by weight or less in the polyvinyl alcohol film.

[0027] The method for producing a polarizer of the present invention is a production method in which the polyvinyl alcohol-based film is subjected to at least a dyeing step, a crosslinking step, and a stretching step, and then a drying step. The process, and at least one treatment bath of the drawing process, contains zinc ions. By containing zinc ions in the at least one treatment bath, the polyvinyl alcohol-based film can contain zinc oxide, and the resulting polarizer contains zinc. 〇 2020/175372 8 (:171? 2020/007068

[0028] <Dyeing process>

The dyeing step is a treatment step of immersing the polyvinyl alcohol film in a dyeing bath (iodine solution), and adsorbing and orienting a dichroic substance such as iodine or a dichroic dye on the polyvinyl alcohol film. be able to. Usually, the iodine solution is preferably an aqueous iodine solution, and contains iodine and iodide as a dissolution aid. Examples of the iodide include lithium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, Examples thereof include titanium iodide. Among these, potassium iodide is preferable.

The concentration of iodine in the dyeing bath is preferably about 0.01 to 1% by weight, more preferably about 0.02 to 0.5% by weight. The concentration of the iodide in the dyeing bath is preferably about 0.01 to 100% by weight, more preferably about 0.05 to 5% by weight.

[0030] When the dyeing bath contains zinc ions, it is preferable to use a zinc salt. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; inorganic zinc salts such as zinc sulfate and zinc acetate. Among these, zinc sulfate is preferable. In the dyeing bath, the concentration of the zinc ion is preferably about 0.1 to 10% by weight, more preferably about 0.3 to 7% by weight, and about 0.5 to 3% by weight. Is more preferable.

[0031] The temperature of the dyeing bath is preferably about 10 to 50°, and about 15 to 4

More preferably, it is about 5 ^° . Further, the immersion time in the dyeing bath cannot be unconditionally determined because the degree of dyeing of the polyvinyl alcohol-based film is affected by the temperature of the dyeing bath, but it is about 10 to 300 seconds. Preferably

More preferably, it is about 20 to 240 seconds. The dyeing step may be performed only once, or may be performed multiple times as necessary.

In the crosslinking step, the polyvinyl alcohol-based fiber dyed in the dyeing step is used. 〇 2020/175372 9 (:171? 2020/007068

This is a treatment step of immersing the film in a treatment bath (crosslinking bath) containing a boron compound, in which the polyvinyl alcohol film is crosslinked by the boron compound and iodine molecules or dye molecules can be adsorbed to the crosslinked structure. Examples of the boron compound include boric acid, borate, and borax. The crosslinking bath is generally an aqueous solution, but may be, for example, a mixed solution of an organic solvent miscible with water and water. Further, the crosslinking bath may contain an iodide such as potassium iodide.

[0033] In the crosslinking bath, the concentration of the boron compound is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and about 2 to 5% by weight. Is more preferable. When using iodide such as potassium iodide in the crosslinking bath, the concentration of iodide such as potassium iodide in the crosslinking bath is preferably about 1 to 15% by weight, and 1.5 It is more preferably about 10 to 10% by weight.

[0034] When a zinc ion is contained in the crosslinking bath, it is preferable to use a zinc salt. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; inorganic zinc salts such as zinc sulfate and zinc acetate. Among these, zinc sulfate is preferable. In the crosslinking bath, the zinc ion concentration is preferably about 0.1 to 10% by weight, more preferably about 0.3 to 7% by weight, and about 0.5 to 3% by weight. Is more preferable.

[0035] The temperature of the crosslinking bath is preferably about 20 to 70 ^{°, and} more preferably about 30 to 60 ^° . Further, the immersion time in the crosslinking bath cannot be unconditionally determined because the degree of crosslinking of the polyvinyl alcohol film is affected by the temperature of the crosslinking bath, but it is preferably about 5 to 300 seconds. , 10 to 200 seconds is more preferable. The cross-linking step may be performed only once, or may be performed multiple times as necessary.

The stretching step is a treatment step of stretching a polyvinyl alcohol film in at least one direction at a predetermined ratio. Generally, polyvinyl alcohol 〇 2020/175372 10 (:171? 2020/007068

Uniaxially stretches the base film in the transport direction (longitudinal direction). The stretching method is not particularly limited, and any of a wet stretching method and a dry stretching method (a method for stretching between mouths, a method for stretching a heated mouth, a method for compressing stretching, etc.) can be adopted. It is preferable to use a wet-type elongation method. The stretching step may be performed only once, or may be performed multiple times as necessary. The stretching step may be performed at any stage in the production of the polarizer.

As the treatment bath (stretching bath) in the wet stretching method, usually, water or a solvent such as a mixed solution of water and an organic solvent miscible with water can be used. The stretching bath described above may contain an iodide such as potassium iodide. When an iodide such as potassium iodide is used in the stretching bath, the concentration of iodide such as potassium iodide in the stretching bath is preferably about 1 to 15% by weight, and 2 to 10% by weight. It is more preferable that the content is about wt %. Further, the treatment bath (stretching bath) may contain the boron compound in order to improve the degree of crosslinking, and in this case, the concentration of the boron compound in the stretching bath is 1 to 15% by weight. It is preferably about 10% by weight, and more preferably about 1.5 to 10% by weight.

[0038] When the drawing bath contains zinc ions, it is preferable to use a zinc salt. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; inorganic zinc salts such as zinc sulfate and zinc acetate. Among these, zinc sulfate is preferable. In the drawing bath, the zinc ion concentration is preferably about 0.1 to 10% by weight, more preferably about 0.3 to 7% by weight, and about 0.5 to 3% by weight. Is more preferable.

[0039] The temperature of the stretching bath is preferably about 25 to 80°, and 40 to 7

More preferably, it is about 5 ^° . The immersion time in the stretching bath cannot be unconditionally determined because the extent of stretching of the polyvinyl alcohol-based film is affected by the temperature of the stretching bath, but it may be about 10 to 800 seconds. Preferably

More preferably, it is about 30 to 500 seconds. The stretching treatment in the wet stretching method may be performed together with one or more treatment steps of the dyeing step, the crosslinking step, the swelling step described later, and the washing step described later. 〇 2020/175372 1 1 卩 (: 171-1? 2020 /007068

[0040] The total stretching ratio (cumulative stretching ratio) applied to the polyvinyl alcohol-based film can be appropriately set according to the purpose, but is preferably about 2 to 7 times, and 3 to 6.8 times. The degree is more preferable, and the range is more preferably 3.5 to 6.5 times.

[0041] The method for producing a polarizer of the present invention is a production method in which the polyvinyl alcohol film is subjected to at least the dyeing step, the crosslinking step, and the stretching step, and then a drying step. A swelling step may be performed before the dyeing step, and a washing step may be performed before the drying step.

[0042] <Swelling step>

The swelling step is a treatment step of immersing the polyvinyl alcohol film in a swelling bath, which can remove stains and blocking agents on the surface of the polyvinyl alcohol film, and swells the polyvinyl alcohol film. Therefore, uneven dyeing can be suppressed. For the swelling bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. In the swelling bath, a surfactant, alcohol, etc. may be appropriately added according to a conventional method.

[0043] The temperature of the swelling bath is preferably about 10 to 60°, and about 15 to 4

More preferably, it is about 5 ^° . The immersion time in the swelling bath cannot be unconditionally determined because the degree of swelling of the polyvinyl alcohol film is affected by the temperature of the swelling bath, but it is preferably about 5 to 300 seconds. , 10 to 200 seconds is more preferable. The swelling step may be performed only once, or may be performed multiple times as necessary.

The washing step is a treatment step of immersing the polyvinyl alcohol film in a washing bath, and foreign substances remaining on the surface of the polyvinyl alcohol film can be removed. For the washing bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. Further, iodide such as potassium iodide can be used in the cleaning bath, and in this case, the concentration of iodide such as potassium iodide in the cleaning bath should be about 1 to 10% by weight. Is preferable, about 2 to 4% by weight 〇 2020/175372 12 (:171? 2020/007068

Is more preferable, and it is still more preferable that it is about 1.6 to 3.8% by weight.

[0045] The temperature of the cleaning bath is preferably about 5 to 50 ^° , more preferably about 10 to 40°, and more preferably about 15 to 30 ^°. Even more preferable. Further, the immersion time in the cleaning bath cannot be unconditionally determined because the cleaning degree of the polyvinyl alcohol film is affected by the temperature of the cleaning bath.

It is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and further preferably about 3 to 20 seconds. The swelling step may be carried out only once, or may be carried out plural times as required.

In the drying step, a polyvinyl alcohol-based film containing zinc is dried while being conveyed by a plurality of holes, and has a thickness of 20 or less, and a moisture content of 13% by weight or more and 19% by weight or less. Wherein the plurality of holes are the first port provided on the most upstream side in the transport direction of the polyvinyl alcohol-based film and the direction in which the polyvinyl alcohol-based film is transported. A second port provided on the most downstream side, and one or more third ports provided between the first port and the second port, and the one or more At least one of the third holes has an included angle of 90° or less between the polyvinyl alcohol film and the polyvinyl alcohol film.

The plurality of ports are a plurality of transfer ports arranged inside a drying processing unit such as a dryer, an oven, and a heating furnace. The first mouth is provided in the drying treatment section, which is provided on the most upstream side in the transport direction of the polyvinyl alcohol-based film containing zinc, and the polyvinyl alcohol-containing film containing zinc is the first in the drying treatment section. It is a transport port that contacts with. Further, the second port is a polyvinyl alcohol-based film containing zinc, which is provided on the most downstream side in the transport direction of the polyvinyl alcohol-based film containing zinc in the drying processing unit. This is the transport port that comes into final contact with. Further, the third port is provided between the first port and the second port in the drying processing section. 〇 2020/175 372 13 卩 (: 171-1? 2020 /007068

One or more transfer ports provided.

[0048] The plurality of apertures have a substantially circular aperture shape, and the size thereof is not particularly limited, but for example, from the viewpoint of damage to the polarizer due to curvature during transportation, the diameter is 1 It is preferably about ◯ to 100 0 01 01, more preferably about 30 to 500 0 01. The plurality of mouths may be the same or different. Further, the plurality of holes may be a heating type hole (a heat type hole) or a non-heating type hole, but when the holes and the polarizer are in contact with each other. In addition, from the viewpoint that there is little concern that zinc will be deposited on the surface of the polarizer, the non-heating type mouthpiece is preferable.

[0049] In the third roll, at least one roll has an included angle of 90 ^° or less between the roll and the polyvinyl alcohol-based film containing zinc. Figure 1 shows a schematic diagram of the included angle. The wrapping angle is an angle 0 ( ^° ) formed when the polyvinyl alcohol-based film containing zinc is conveyed through the mouth. More specifically, it is an angle formed by the start point and the final point where the polyvinyl alcohol-based film containing zinc is in contact with the mouth with the center point of the mouth as the reference point. From the viewpoint of reducing the contact time between the polyvinyl alcohol-based film containing zinc and the mouth and suppressing the abnormal appearance (polarization unevenness) of the polarizer, the wrap angle is preferably smaller than 90 ^° , for example, , 80 ^° or less, preferably 70 ^° or less, more preferably 60 ^° or less, still more preferably 50 ^° or less. Further, from the viewpoint of suppressing abnormal appearance of the polarizer (polarization unevenness), the lower limit of the wrapping angle is not particularly limited. For example, it is possible to suppress scratches of the polarizer due to insufficient mouth rotation. From the viewpoint of, for example, 10 ^° or more, 30 ^° or more can be exemplified.

[0050] The number of the third holes cannot be unconditionally determined because it is affected by the temperature of the drying step and the drying time, but it is usually preferable to provide about 1 to 30 of the drying treatment section, It is preferable to provide about 2 to 20 pieces.

[0051] Also, in the drying step, the polyvinyl alcohol containing the zinc 〇 2020/175372 14 卩 (: 171-1? 2020 /007068

It is preferable that the ratio (contact distance/total transport distance) of the contact distance of the system film to the third roll and the total transport distance of the polyvinyl alcohol-based film containing zinc is not more than 0.1. .. From the viewpoint of reducing the contact time between the zinc-containing polyvinyl alcohol-based film and the mouth and further suppressing abnormal appearance of the polarizer (polarization mura), the above contact distance/total transport distance is It is preferably 0.09 or less. From the viewpoint of enhancing the transportability of the polyvinyl alcohol-based film, the above contact distance/total transport distance is preferably 0.01 or more, and more preferably 0.03 or more.

[0052] Further, in the drying step, a ratio of a maximum distance between the mouths of the plurality of mouths (a circle) and a width of the polyvinyl alcohol-based film containing zinc before the drying step (a circle ( L _MAX /W ₁ ) is preferably less than or equal to 2. The maximum distance between the mouths in the plurality of mouths means the distance between adjacent mouths (the upstream mouth and the downstream mouth). Between the position where the polyvinyl alcohol-based film containing zinc is separated from the upstream side hole, and the position where the polyvinyl alcohol-based film containing zinc is first contacted with the downstream side hole. Conveyance distance (idle distance) (It means the longest distance of !_. From the viewpoint of minimizing the bending of the polyvinyl alcohol film containing zinc during conveyance to prevent the resulting polarizer from bending. From

Is preferably 1.5 or less, and more preferably 1 or less. Further, from the viewpoint of suppressing the occurrence of bending of the polarizer, the lower limit value of ! _-MAX /W ₁ is not particularly limited, but for example, from the viewpoint of improving the transportability of the polyvinyl alcohol film. Therefore, it is possible to exemplify 0.01 or more and 0.2 or more.

[0053] The drying temperature is not particularly limited as long as the thickness of the obtained polarizer is 20 or less and the water content is 13% by weight or more and 19% by weight or less. but for example, preferably 1 5 to a 1 5 0 ^° 〇 about, and more preferably 2 0 to 1 0 0 ^° 〇 about, even more preferably from 2 5 5 0 ^° 〇 about .. The drying time cannot be generally determined because the drying degree of the polarizer is affected by the drying temperature, but it may be about 30 to 600 seconds. 〇 2020/175372 15 卩(: 171-1? 2020/007068

It is more preferably about 60 to 300 seconds. The drying step may be performed only once, or may be performed multiple times as necessary.

The polarizer obtained by the production method of the present invention has a thickness of 20 or less and a moisture content of 13% by weight or more and 19% by weight or less. The polarizer has a thickness of preferably 5 or more, more preferably 10 or more, in consideration of the transportability of the polyvinyl alcohol film and the polarizer, and the heating durability of the polarizing film. From the viewpoint of increasing the thickness, the thickness is preferably 19 or less. From the viewpoint of suppressing appearance anomalies (polarization unevenness) due to surface deformation of the polarizer, the polarizer preferably has a moisture content of 13.5% by weight or more, and 14% by weight or more. More preferably, and from the viewpoint of enhancing the heating durability of the polarizing film, the water content is preferably 18.5% by weight or less, and more preferably 18% by weight or less. The water content of the polarizer is calculated by the following formula based on the initial weight of the sample (polarizer) cut into a size of 100 square and the dry weight after drying ^at 120 ^° 〇 for 2 hours. It is calculated from

Moisture content (wt %) = {(initial weight-dry weight) / initial weight} X 1 〇〇

The polarizer has a ratio of the width of the polyvinyl alcohol-based film containing zinc before the drying step') to the width of the polarizer (\^/ ₂ ) obtained after the drying step.

Is preferably 0.9 or more and less than 1. From the viewpoint of suppressing the generation of wrinkles at the end of the polarizer in the drying process,

Is preferably 0.92 to 0.98, and more preferably 0.94 to 0.98.

The method for producing a polarizing film of the present invention includes a step of laminating a transparent protective film on at least one surface of the polarizer with an adhesive layer.

The transparent protective film is not particularly limited, and various transparent protective films conventionally used for polarizing films can be used. Examples of the material constituting the transparent protective film include transparency, mechanical strength, thermal stability, 〇 2020/175372 16 卩(: 171-1?2020/007068

A thermoplastic resin having excellent moisture barrier properties and isotropic properties is used. Examples of the thermoplastic resin include cellulose ester based resins such as triacetyl cellulose, polyester based resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone based resins, polysulfone based resins and polycarbonate based resins. Resins, Polyamide-based resins such as nylon and aromatic polyamides, Polyimide-based resins, Polyethylene-based resins such as polyethylene, polypropylene, ethylene-propylene copolymer, (meth)acrylic-based resins, cyclo-based nornorbornene Examples include cyclic polyolefin resins having a structure (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. Further, as the transparent protective film, a hardening layer formed of a thermosetting resin such as (meth)acrylic, urethane-based, acrylicurethane-based, epoxy-based, or silicone-based or an ultraviolet-curable resin can be used. .. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are preferable.

[0058] The thickness of the transparent protective film can be appropriately determined, but generally it is preferably about 1 to 500 from the viewpoint of workability such as strength and handleability, and thin layer property. It is more preferably about 1 to 300, and even more preferably about 5 to 100. Further, the thickness of the transparent protective film, from the viewpoint of reducing the moisture permeability of the transparent protective film, is preferably about 10 to 100, more preferably about 20 to 100, More preferably, it is about 30 to 1001.

[0059] The transparent protective film preferably has a water vapor transmission rate of 8 0 0 9 /( ² ·2 4) or less, from the viewpoint of suppressing deterioration of polarization performance in a high temperature or high temperature and high humidity environment. 0 9 / (01 ² · 2 4) or less is more preferable, and 20 0 9 / ( ² 2 4) or less is further preferable,

2 4 11) It is even more preferable that it is not more than. Further, the transparent protective film on one surface of the polarizer has a moisture permeability of not more than 20 09 / ( ² ·24). 〇 2020/175372 17 卩(: 171-1? 2020/007068

Is preferable, and it is more preferable that it is 150 9 /(01 ² ·2 4) or less. According to the moisture vapor permeability test (cup method) of 352, the sample cut into the diameter was set in a moisture vapor permeable cup containing approximately 159 calcium chloride. This can be calculated by measuring the weight increase of calcium chloride before and after leaving it in a thermostat with a temperature of 40° and humidity of 90% [¾ .1 ^to 1] and leaving it for 24 hours.

When the transparent protective films are attached to both sides of the polarizer, the transparent protective films on both sides may be the same or different.

As the transparent protective film, it is possible to use a retardation plate having a front phase difference of 40 n or more and/or a thickness direction retardation of 800°! or more. The front phase difference is usually controlled in the range of 40 to 200 n, and the thickness direction retardation is normally controlled in the range of 80 to 300!. When a retardation plate is used as the transparent protective film, the retardation plate also functions as a transparent protective film, so that the thickness can be reduced.

[0062] Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. Is mentioned. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150. The phase plate may be attached to a transparent protective film having no retardation.

[0063] The transparent protective film may be subjected to a surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, primer treatment, saponification treatment and the like.

[0064] The surface of the transparent protective film to which the polarizer is not attached may be subjected to a hard coat treatment, an antireflection treatment, a sticking prevention treatment, or a treatment for the purpose of diffusion or antiglare. The hard coat treatment, the antireflection layer, the antisticking layer, the treatment for the purpose of the diffusion layer or antiglare, etc. can be provided on the transparent protective film itself, or as a separate optical layer different from the transparent protective film. It can also be provided as a body part.

[0065] The transparent protective film includes an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, 〇 2020/175 372 18 卩 (: 171-1? 2020 /007068

It may contain any appropriate additive such as a release agent, an anti-coloring agent, a flame retardant, an antistatic agent, a pigment, a coloring agent and the like.

[0066] Examples of the adhesive include water-based adhesives, solvent-based adhesives, emulsion-based adhesives, solvent-free adhesives, active energy ray-curable adhesives (eg, ultraviolet ray-curable adhesives, electron beams Curable adhesive), thermosetting adhesive, and the like. From the viewpoint of having a desired viscosity before solidification or curing and excellent adhesiveness to the polarizer, the adhesive is preferably a water-based adhesive.

As the water-based adhesive, any suitable water-based adhesive can be adopted. A water-based adhesive containing an october resin is suitable. From the viewpoint of adhesiveness, the average degree of polymerization of the resin is preferably about 100 to 5,500, and more preferably about 1,000 to 4,500. .. The average saponification degree of the october resin is preferably about 85 mol% to 100 mol%, and more preferably about 90 mol% to 100 mol% from the viewpoint of adhesiveness. Is more preferred

[0068] From the viewpoint of excellent adhesion to the polarizer and the protective film and excellent durability, the octyl resin preferably contains an acetoacetyl group. The acetyl group-containing octane-based resin can be obtained, for example, by reacting the octane-based resin with diketene by an arbitrary method. The degree of acetoacetyl group modification of the acetoacetyl group-containing eight-system resin is typically at least 0.1 mol%, preferably about 0.1 mol% to 40 mol%, and 1 mol% to 2 mol% It is more preferably about 0 mol%, further preferably about 2 mol% to 7 mol%. The degree of acetoacetyl group modification is

It is the value measured by.

[0069] The resin (solid content) concentration of the water-based adhesive is preferably about 0.1 to 15% by weight, and more preferably about 0.5 to 10% by weight. Good

[0070] The application of the adhesive may be performed on either the transparent protective film or the polarizer, or may be applied to both. After bonding, apply a drying process and apply 〇 2020/175 372 19 卩 (: 171-1? 2020 /007068

An adhesive layer consisting of a dry layer is formed. The lamination of the polarizer and the transparent protective film can be performed with a mouth laminator or the like. After the drying step, it is possible to irradiate with an ultraviolet ray or an electron beam, if necessary. Although the thickness of the adhesive layer is not particularly limited, it is preferably about 30 to 500 n, more preferably about 100 to 100 mm.

The method for producing a laminated polarizing film (optical laminate) of the present invention includes a step of attaching an optical layer to the polarizing film.

The optical layer is not particularly limited, and examples thereof include a reflection plate, a semi-transmission plate, and a retardation plate (

1 or 2 or more optical layers that may be used for forming liquid crystal display devices such as a viewing angle compensation film, etc. can be used. As the laminated polarizing film, in particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by further laminating a reflecting plate or a semi-transmissive reflecting plate on the polarizing film, or a polarizing plate further laminating a retardation plate Examples thereof include an elliptically polarizing film or a circularly polarizing film, a wide viewing angle polarizing film obtained by further laminating a viewing angle compensation film on the polarizing film, or a polarizing film obtained by further laminating a brightness enhancement film on the polarizing film.

[0073] One or both surfaces of the polarizing film or the laminated polarizing film have an image display cell such as a liquid crystal cell or an organic semiconductor element, and a transparent side such as a front transparent plate or a touch panel on the viewing side. An adhesive layer for adhering other members such as a plate may be provided. A pressure-sensitive adhesive layer is suitable as the adhesive layer. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is used as the base polymer. Can be appropriately selected and used. In particular, a pressure-sensitive adhesive containing an acrylic polymer, which has excellent optical transparency, exhibits appropriate wettability, cohesiveness and adhesiveness, and has excellent weather resistance and heat resistance, is preferably used.

[0074] A pressure-sensitive adhesive layer is formed on one side or both sides of the polarizing film or the laminated polarizing film. 〇 2020/175372 20 (:171? 2020/007068

The attachment can be performed by an appropriate method. As the attachment of the pressure-sensitive adhesive layer, for example, a method of preparing a pressure-sensitive adhesive solution and directly applying it on the polarizing film or the laminated polarizing film by an appropriate developing method such as a casting method or a coating method, or Examples include a method of forming an adhesive layer on the separator and transferring it to the polarizing film or the laminated polarizing film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, the adhesive force, etc., and is generally 1 to 500, preferably 5 to 200, and 10 to 100. Is more preferable

[0075] It is preferable that the exposed surface of the pressure-sensitive adhesive layer is temporarily attached and covered with a separator for the purpose of preventing its contamination, etc. until it is put into practical use. As a result, it is possible to prevent the pressure-sensitive adhesive layer from being contaminated under normal handling conditions. Examples of the separator include plastic films, rubber sheets, paper, cloth, non-woven fabrics, nets, foamed sheets and metal foils, and appropriate thin sheets such as laminates thereof. It is possible to use those coated with an appropriate release agent such as a fluorine-based, fluorine-based or molybdenum sulfide.

The method for producing an image display panel of the present invention includes a step of adhering the polarizing film or the laminated polarizing film to an image display cell. Further, the method for manufacturing an image display device of the present invention includes a step of providing a transparent plate on the polarizing film or laminated polarizing film side (viewing side) of the image display panel.

[0077] Examples of the image display cell include a liquid crystal cell and an organic-semiconductor cell. The liquid crystal cell may be, for example, a reflective liquid crystal cell that uses external light, a transmissive liquid crystal cell that uses light from a light source such as a backlight, or both external light and light from a light source. Any of the transflective liquid crystal cells may be used. When the liquid crystal cell uses light from a light source, the image display device (liquid crystal display device) has a polarizing film disposed on the side opposite to the viewing side of the image display cell (liquid crystal cell). Will be placed. It is preferable that the polarizing film on the light source side and the liquid crystal cell are bonded together via an appropriate adhesive layer. 〇 2020/175372 21 卩 (: 171-1? 2020 /007068

Yes. The driving method of the liquid crystal cell is, for example, eight modes,

Any type can be used, such as a mode, a 1\1 mode, a 3\1\1 mode, or a bend orientation (type).

[0078] As the above-mentioned organic semiconductor 1_cell, for example, one in which a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light-emitting body (organic electroluminescence light-emitting body) is preferable. Used for. The organic light emitting layer is a laminated body of various organic thin films, for example, a laminated body of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, or the like. Various layer configurations can be adopted, such as a laminated body of these light emitting layers and an electron injection layer composed of a perylene derivative or a laminated body of a hole injection layer, a light emitting layer and an electron injection layer

[0079] Examples of the transparent plate disposed on the viewing side of the image display cell include a front transparent plate (window layer) and a touch panel. As the front transparent plate, a transparent plate having appropriate mechanical strength and thickness is used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin or a polycarbonate resin, or a glass plate is used. As the touch panel, for example, various touch panels such as a resistance film type, a capacitance type, an optical type, and an ultrasonic type, and a glass plate or a transparent resin plate having a touch sensor function are used. When a capacitance type touch panel is used as the transparent plate, it is preferable that a front transparent plate made of glass or a transparent resin plate is provided on the viewing side of the touch panel.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Average degree of polymerization is 2,400, degree of saponification is 99.9 mol%, thickness is 45, width is 26

A polyvinyl alcohol film was prepared. Polybi 〇 2020/175372 22 swelling (:171? 2020/007068) Nyl alcohol film is swelled by swelling for 30 seconds in a swelling bath (water bath) of 28° 〇 between mouths with different peripheral speed ratios, and conveying direction The film is stretched 2.4 times (swelling step) and then in a dyeing bath at 25°◦ (aqueous solution with iodine concentration of 0.03% by weight and potassium iodide concentration of 0.3% by weight). While soaking for 2 seconds and dyeing, the original polyvinyl alcohol film (polyvinyl alcohol film that has not been stretched at all in the transport direction) was stretched 3.7 times in the transport direction (dyeing process). Polyvinyl alcohol film was applied to a 40°C cross-linking bath (boric acid concentration 3.0% by weight, potassium iodide concentration 3.0% by weight).

, Zinc sulphate is an aqueous solution containing 3.6 wt% (concentration of zinc ion is 1.5 wt%), swelled for 20 seconds and stretched to 4.2 times in the transport direction based on the original polyvinyl alcohol film. Did (crosslinking step). Further, the obtained polyvinyl alcohol film was subjected to a drawing bath at 65°○ (boric acid concentration 4.0% by weight, potassium iodide concentration 5.0% by weight, zinc sulfate concentration 5.0% by weight (zinc ion After immersing in an aqueous solution (concentration: 2.0% by weight) for 50 seconds and stretching to 6.0 times in the transport direction based on the original polyvinyl alcohol film (stretching step), washing at 27°○ It was immersed in a bath (aqueous solution having a potassium iodide concentration of 2.5% by weight) for 5 seconds (washing step). A person who has the washed polyvinyl alcohol film with the arrangement of mouths as shown in Fig. 2 (total number of mouths is 10; maximum holding angle is 43° in the third mouth). It was used and dried at 25° for 2 minutes to prepare a polarizer. The ratio (contact distance/total transport distance) of the contact distance of the polyvinyl alcohol film to the third roll and the total transport distance of the polyvinyl alcohol film was 0.09. In addition, the ratio (L) of the maximum distance between the mouths of a plurality of mouths in the oven (the circle) and the width of the polyvinyl alcohol-based film containing zinc before the drying step (flame) _MAX /W ₁ ) was 0.2 1. The thickness of the obtained polarizer was 18 and the water content of the polarizer was 17.2% by weight.

Was 0.97.

As an adhesive, polyvinyl alcohol resin containing acetoacetyl group ( 〇 2020/175 372 23 卩 (: 171-1? 2020 /007068

An aqueous solution containing an average degree of polymerization of 1,200, a degree of saponification of 98.5 mol% and a degree of acetoacetylation of 5 mol%) and methylolmelamine in a weight ratio of 3:1 was used. Using this adhesive, as a second transparent protective film, a (meth)acrylic resin (modified acrylic resin having a lacton ring structure) on one surface (image display cell side surface) of the polarizer obtained above A transparent protective film with a thickness of 3001 consisting of a polymer (saturated water absorption is 0.

The moisture vapor transmission rate is 1 2 5 9 / ( ² ·

2 4 11)), (hereinafter, this film is referred to as “transparent film 8”), and as the first transparent protective film, a triacetyl film having a thickness of 40 and having a hard coat layer on the other surface (viewing side). Cellulose film (water vapor transmission rate is 3 4 4 9 / ( ² 2 4 11), made by Konica Minolta, product name “< 0 4 11 丫\^”) (Hereafter, this film is referred to as “transparent film mit”) After laminating with a mirror laminating machine, continue heating and drying in an oven (temperature is 88 ^° 〇, time is 10 minutes), and then a polarizing film with transparent protective films laminated on both sides of the polarizer. Was produced.

The polarizing film obtained above was cut to a size of 150×500 so that the absorption axis of the polarizer would be the long side, and one side of the polarizing film (the side of the transparent film 8 side) A glass plate (pseudo image display cell) is attached via an acrylic adhesive layer with a thickness of 200, and an acrylic acid monomer-free adhesive with a thickness of 200 is attached to the other surface of the polarizing film (the surface on the side of the transparent film). Agent (Nitto Denko Co., Ltd., trade name

Another glass plate was pasted together via the “3 9 8 6 8”) to produce a pseudo image display device.

[0084] [Evaluation of abnormal appearance (uneven polarization)]

The appearance of the polarizing film obtained above was visually evaluated according to the following criteria. The results are shown in Table 1.

◯: There is no abnormality in appearance, or polarization unevenness of less than 10 pieces/ ² occurs. X: 10 pieces / ² or more polarization unevenness occurs.

[0085] [Evaluation of Folding of Polarizer] 〇 2020/175372 24 (:171? 2020/007068

The appearance of the polarizer obtained above was visually evaluated according to the following criteria. The results are shown in Table 1.

◯: There is no visible bending of the polarizer.

X: Visible polarizer breaks.

[0086] [Evaluation of heating durability]

The pseudo image display device obtained above was allowed to stand for 500 hours in a hot air oven at a temperature of 95 ^° , and the appearance after charging (heating) was visually evaluated according to the following criteria. The results are shown in Table 1.

◯: There is no abnormality in appearance.

X: Visible unevenness occurs on the polarizer.

In the production of the polarizer, a polarizer was produced in the same manner as in Example 1 except that the drying temperature in the drying step was 35 ^° . The thickness of the obtained polarizer was 17, and the water content of the polarizer was 14.3% by weight.

Is 〇.

It was 9 5. Using the obtained polarizer, a polarization film and a pseudo image display device were produced by the same operation as in Example 1.

[0088] <Example 3>

Average degree of polymerization is 2,400, degree of saponification is 99.9 mol%, thickness is 30 and width is 26.

A polyvinyl alcohol film was prepared. The polyvinyl alcohol film was swelled by swelling for 30 seconds in a swelling bath (water bath) of 20° 〇 between the mouths with different peripheral speed ratios, and while being swollen, stretched 2.4 times in the transport direction (expansion). Wetting process), and then immerse in dyeing bath at 25 ^° 〇 (aqueous solution with iodine concentration of 0.045% by weight and potassium iodide concentration of 0.45% by weight) for 45 seconds for dyeing. However, the original polyvinyl alcohol film (polyvinyl alcohol film that has not been stretched at all in the transport direction) was stretched 3.7 times in the transport direction (dyeing process). Then, the dyed polyvinyl alcohol film is 〇 2020/175372 25 卩 (：171? 2020 /007068

Crosslinking bath at 0°○ (Boric acid concentration 3.0% by weight, potassium iodide concentration 3.0% by weight, zinc sulfate 3.6% by weight (zinc ion concentration 1.5% by weight) It was immersed in a water solution) for 20 seconds and stretched to 4.2 times in the transport direction based on the original polyvinyl alcohol film (crosslinking step). Further, the obtained polyvinyl alcohol film was applied to a drawing bath at 65°○ (boric acid concentration 4.0% by weight, potassium iodide concentration 5.0% by weight, zinc sulfate concentration 5.0% by weight (zinc It was immersed in an aqueous solution with an ion concentration of 2.0% by weight) for 50 seconds, and stretched to 6.0 times in the transport direction based on the original polyvinyl alcohol film (stretching step), then at 20 ^°. It was immersed for 5 seconds in a cleaning bath (a water solution having a potassium iodide concentration of 3.0% by weight) (cleaning step). Use the oven with the cleaned polyvinyl alcohol film and the arrangement of the mouths as shown in Figure 2 (total number of mouths is 10; maximum wrap angle is 43° in the third mouth). A polarizer was prepared by drying at 18°○ for 2 minutes. The ratio (contact distance/total transport distance) of the contact distance of the polyvinyl alcohol film to the third roll and the total transport distance of the polyvinyl alcohol film was 0.09. In addition, the ratio between the maximum distance between the holes in the multiple ovens (○) and the width of the polyvinyl alcohol-based film containing zinc before the drying step (○ (L _MAX /W ₁ ) Was 0.20. The thickness of the obtained polarizer was 12, the water content of the polarizer was 17.6% by weight, and the ratio ₂ /\^ was 097. A polarizing film and a pseudo image display device were produced in the same manner as in Example 1 by using the polarizer described above.

In the production of the polarizer, a polarizer was produced by the same operation as in Example 3 except that the drying temperature in the drying step was 25 ^° . The thickness of the obtained polarizer was 12, and the water content of the polarizer was 14.5% by weight.

Is 〇.

It was 95. Using the obtained polarizer, a polarization film and a pseudo image display device were produced by the same operation as in Example 1. 〇 2020/175 372 26 卩 (：171? 2020 /007068

[0090] <Example 5>

In the production of the polarizer, an oven having the arrangement of mouths as shown in Fig. 5 (total number of mouthpieces: 8; maximum wrap angle in the third mouthpiece is 88°) is shown in Fig. 5. A polarizer was prepared in the same manner as in Example 1, except that the polarizer was prepared by drying at 280° for 3 minutes. The ratio of the contact distance of the polyvinyl alcohol film to the third roll and the total transport distance of the polyvinyl alcohol film (contact distance/total transport distance) was 0.09. The thickness of the obtained polarizer was 18, the water content of the polarizer was 15.0% by weight,

It was .92. In addition, the maximum distance between the mouths in a plurality of mouths in the oven ((○) and the width of the polyvinyl alcohol film containing zinc before the drying step.

The ratio (L _MAX /W ₁ ) was 0.82. Using the obtained polarizer, a polarizing film and a pseudo image display device were produced in the same manner as in Example 1.

[0091] <Comparative Example 1>

In the production of the polarizer, a polarizer was produced by the same operation as in Example 1 except that the drying temperature in the drying step was 45 ^° . The thickness of the obtained polarizer was 17, and the water content of the polarizer was 12.5% by weight.

Is 〇.

It was 9 1. Using the obtained polarizer, a polarization film and a pseudo image display device were produced by the same operation as in Example 1.

[0092] <Comparative example 2>

In the production of the polarizer, a polarizer was produced in the same manner as in Example 1 except that the drying temperature in the drying step was set to 17 ^° . The thickness of the obtained polarizer was 18, and the water content of the polarizer was 19.1% by weight.

It was 9 8. Using the obtained polarizer, a polarization film and a pseudo image display device were produced by the same operation as in Example 1.

<Comparative Example 3> 〇 2020/175 372 27 卩 (: 171? 2020 /007068

In the fabrication of the polarizer, the drying process has an arrangement of the mouths (the total number of the mouthpieces is 18; the maximum wrap angle in the 3rd mouth is 176 ^° ). A polarizer was produced in the same manner as in Example 1 except that the polarizer was produced by using a bun and drying at 28 ^° for 5 minutes. In addition, the maximum distance (L _MAX ) between the mouths of the plurality of mouths in the oven and the width of the polyvinyl alcohol-based film containing zinc before the drying step (ratio with ◯ (L _MAX /W ₁ ) was 0.82. The thickness of the obtained polarizer was 17 and the water content of the polarizer was 14.3% by weight, and ₂ /\^ was 084. Using the obtained polarizer, a polarizing film and a pseudo image display device were produced in the same manner as in Example 1. Incidentally, the contact distance of the polyvinyl alcohol film with respect to the third hole and the total polyvinyl alcohol film The ratio to the transport distance (contact distance/total transport distance) was 0.13.

In the production of a polarizer, an oven with an arrangement of mouths as shown in Fig. 4 (total number of mouthpieces: 6; maximum holding angle in the third mouthpiece is 1 34°) is shown in Fig. 4. A polarizer was prepared in the same manner as in Example 1, except that the polarizer was prepared by drying at 31 ^° C for 3 minutes. The thickness of the obtained polarizer was 17 and the water content of the polarizer was 14.3% by weight.

Was 88. In addition, the maximum distance between mouths in multiple mouths

And the width (of the polyvinyl alcohol-based film containing zinc before drying step (L _MAX /W ₁ ) was 0.98. Using the obtained polarizer, the same procedure as in Example 1 was carried out. A polarizing film and a pseudo-image display device were manufactured by the operation, and the ratio of the contact distance of the polyvinyl alcohol film to the third roll and the total transport distance of the polyvinyl alcohol film (contact distance/total transport distance). ) Was 0.08.

[0095] <Comparative Example 5> 〇 2020/175 372 28 卩 (: 171? 2020 /007068

In the production of the polarizer, a polarizer was produced in the same manner as in Example 1 except that it was dried for 2 minutes at 25° in a drying oven having no mouth. The thickness of the obtained polarizer was 18, the water content of the polarizer was 17.4% by weight,

Was 0.81. Using the obtained polarizer, a polarizing film and a pseudo image display device were produced in the same manner as in Example 1.

[0096] <Comparative Example 6>

In the production of the polarizer, a polarizer was produced in the same manner as in Example 1 except that zinc sulfate was not used in the crosslinking bath and the stretching bath. The thickness of the obtained polarizer was 18, the water content of the polarizer was 17.2% by weight, and \^/ ₂ / was 0.96. Using the obtained polarizer, a polarizing film and a pseudo image display device were produced in the same manner as in Example 1.

Average degree of polymerization is 2,700, degree of saponification is 99.9 mol%, thickness is 75, width is 26.

Prepare a polyvinyl alcohol film, and adjust the concentration of the dyeing bath to 0.02 wt% iodine concentration and 0.2 wt% potassium iodide concentration. Using a heater having the following arrangement (total number of mouths is 18; maximum holding angle in the third mouth is 176°) and dried at 45° 〇 for 5 minutes. A polarizer was produced in the same manner as in Example 1 except that the above was produced. In addition, the ratio of the maximum distance between the mouths of multiple mouths in the oven (the circle and the width of the polyvinyl alcohol film containing zinc before the drying step)

Was 0.82. The thickness of the obtained polarizer was 28, the water content of the polarizer was 14.5% by weight, and the ratio ₂ /\^ was 086. Using the obtained polarizer, a polarizing film and a pseudo image display device were produced in the same manner as in Example 1.

[0098] The polarizers and pseudo images of Examples 2 to 5 and Comparative Examples 1 to 7 obtained above 〇 2020/175 372 29 卩 (: 171? 2020 /007068

Using a display device, the evaluations in [Evaluation of abnormal appearance (uneven polarization)], [Evaluation of breakage of polarizer] and [Evaluation of heating durability] were performed. The results are shown in Table 1.

[0099] [Table 1]

\¥0 2020/175 372 30 卩 (: 17 2020 /007068

Explanation of symbols

[0100] Polyvinyl alcohol film containing zinc

Mouth

0 Holding angle

!_ Running distance

Claims

\¥0 2020/175 372 31 卩(: 17 2020/007068 Claims

[Claim 1] A method for producing a polarizer obtained by subjecting a polyvinyl alcohol film to at least a dyeing step, a crosslinking step, and a stretching step, and then a drying step,

At least one treatment bath in the dyeing step, the crosslinking step, and the stretching step contains zinc ions,

In the drying step, a polyvinyl alcohol-based film containing zinc is dried while being conveyed by a plurality of holes, and has a thickness of 20 or less and a moisture content of 13% by weight or more and 19% by weight or less. Is a process of manufacturing a polarizer,

The plurality of mouths, the first mouth provided on the most upstream side in the transport direction of the polyvinyl alcohol-based film,

A second port provided on the most downstream side in the transport direction of the polyvinyl alcohol film,

Including one or more third rolls provided between the first roll and the second roll,

At least one of the one or more third holes has a wrap angle between the polyvinyl alcohol film and the polyvinyl alcohol film of 90 ^° or less. Manufacturing method.

[Claim 2] In the drying step, a ratio of a contact distance of the polyvinyl alcohol-based film containing zinc to the third roll and a total transport distance of the polyvinyl alcohol-based film containing zinc (contact The method for manufacturing a polarizer according to claim 1, wherein the distance/total transport distance) is 0.1 or less.

[Claim 3] The ratio (L _MAX /W) of the maximum distance between the holes in the plurality of holes (○) and the width (!) of the polyvinyl alcohol-based film containing zinc before the drying step. _The method for producing a polarizer according to claim 1, wherein ₁ ) is 2 or less. 〇 2020/175 372 32 (:171? 2020/007068

[Claim 4] The polarizer is a polyvinyl alcohol containing zinc before the drying step.

— Width of the ru-based film') and the width (\^ ₂ ) of the polarizer obtained after the drying process

The method for producing a polarizer according to any one of claims 1 to 3, characterized in that: 0.9 or more and less than 1.

[Claim 5] A method for producing a polarizer according to any one of claims 1 to 4, further comprising a step of laminating a transparent protective film on at least one surface of the polarizer with an adhesive layer. And a method for manufacturing a polarizing film.

6. The method for producing a polarizing film according to claim 5, wherein the adhesive forming the adhesive layer is a water-based adhesive.

[Claim 7] The transparent protective film manufacturing method of the polarizing film according to claim 5 or 6, wherein the moisture permeability 2 0 0 9 / ⁽² 2 4) below.

[Claim 8] A method for producing a laminated polarizing film, comprising a step of bonding an optical layer to the polarizing film obtained by the method for producing a polarizing film according to any one of claims 5 to 7.

[Claim 9] A polarizing film obtained by the method for producing a polarizing film according to any one of claims 5 to 7 in an image display cell, or obtained by the method for producing a laminated polarizing film according to claim 8. A method of manufacturing an image display panel, comprising the step of laminating the laminated polarizing film.

[Claim 10] An image display device comprising a step of providing a transparent plate on the polarizing film or laminated polarizing film side of the image display panel obtained by the method for producing an image display panel according to claim 9. Production method.