TWI753462B - Manufacturing method of polarizer - Google Patents

Abstract

An object of the present invention is to provide a method that can easily manufacture a polarizer having a non-polarizing portion that can realize multifunctional and high-functionalization of electronic components such as an image display device, and that can manufacture a desired non-polarizing light with high accuracy shape of the department. As a solution, the method for manufacturing a polarizer of the present invention includes bringing an alkaline solution into contact with the exposed portion in a state where the resin film containing the dichroic substance is at least partially exposed and covered with the surface protective film. In one embodiment, when the contact is to be performed, the exposed portion is subjected to surface modification treatment. In yet another embodiment, the contact angle between the exposed portion and the alkaline solution is 50 degrees or less.

Description

Manufacturing method of polarizer

Field of Invention

The present invention relates to a manufacturing method of a polarizer. More specifically, the present invention relates to a method for manufacturing a polarizer having a non-polarizing portion.

Background of the Invention

Video display devices such as mobile phones and notebook personal computers (PCs) are equipped with internal electronic components such as cameras. Various studies have been conducted for the purpose of improving the camera performance of such an image display device (for example, Patent Documents 1 to 6). However, due to the rapid spread of smart phones and touch panel type information processing devices, further improvements in camera performance and the like have been demanded. Moreover, in order to respond to the diversification and high functionality of the image display device, a polarizing plate having partial polarizing performance is required. When it is desired to manufacture an image display device and/or its parts at an allowable cost in order to realize these requirements industrially and commercially, various research matters remain in order to confirm such a technology. prior art literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2011-81315 Patent Document 2: Japanese Patent Laid-Open No. 2007-241314 Patent Document 3: Specification of US Patent Application Publication No. 2004/0212555 Patent Document 4: Korean Laid-Open Patent Publication No. 10-2012-0118205 Patent Document 5: Korean Patent Publication No. 10-1293210 Patent Document 6: Japanese Patent Laid-Open No. 2012-137738

Summary of Invention The problem to be solved by the invention

The present invention has been made in order to solve the above-mentioned problems, and its main object is to provide a method for producing a polarizer capable of realizing the multi-functionalization and high-functioning of electronic components such as image display devices, and which can be performed with high accuracy and simplicity. Manufacture the desired shape of the non-polarized portion. means of solving problems

The inventors of the present invention discovered that by using a resin film containing a dichroic substance (hereinafter, also referred to as a resin film) in a state where at least a part of the resin film containing the dichroic substance is exposed and covered with a surface protection film, the exposed portion is brought into contact with an alkaline solution. The present invention can be accomplished by performing a surface modification treatment on the exposed portion and/or making the contact angle between the exposed portion and the alkaline solution 50 degrees or less when contacting with the above-mentioned manufacturing method.

The method for producing a polarizer of the present invention includes bringing an alkaline solution into contact with the exposed portion in a state where the resin film containing the dichroic substance is at least partially exposed and covered with the surface protective film. When the above-mentioned contact is to be performed, the above-mentioned exposed portion is subjected to surface modification treatment. In one embodiment, the method for producing a polarizer of the present invention includes subjecting the resin film covered with the surface protective film to a surface modification treatment. In one embodiment, the above-mentioned surface modification treatment is corona treatment. In one embodiment, the above-mentioned surface modification treatment is to apply a surface modification agent. In one embodiment, the surface modifier is an organosilane compound. In one Embodiment, the contact angle of the said exposed part and the said alkaline solution is 50 degrees or less. Another method of manufacturing a polarizer of the present invention includes bringing an alkaline solution into contact with the exposed portion in a state in which the resin film containing a dichroic substance is at least partially exposed by the surface protection film, and the exposed portion is exposed. The contact angle between the part and the alkaline solution is 50 degrees or less. In one embodiment, the alkaline solution further contains an additive. In one embodiment, the contacting is performed by conveying the resin film and immersing the resin film in the alkaline solution in a state where the surface of the resin film opposite to the surface protection film is covered with the other surface protection film. According to another aspect of the present invention, a polarizer can be provided. The polarizer has a circular non-polarizing portion with a diameter of 2.9 mm or less. In one embodiment, the circularity of the non-polarized portion is 0.060 mm or less. Invention effect

The production method of the present invention includes bringing an alkaline solution into contact with the exposed portion in a state where the resin film containing the dichroic substance is at least partially exposed and covered with the surface protective film. In one embodiment, the exposed portion is subjected to surface modification treatment when the contact is to be performed. In another embodiment, the contact angle between the exposed portion and the alkaline solution is 50 degrees or less. The manufacturing method of this invention forms a non-polarization part by contacting an alkaline solution. Depending on the required shape of the exposed portion (resultingly, the non-polarized portion), the alkaline solution may not be sufficiently brought into contact with the exposed portion. For example, when a polarizer having a non-polarizing portion having a complex shape and/or small size is manufactured, the surface tension of the alkaline solution may prevent the alkaline solution from sufficiently contacting the resin film especially at the end of the exposed portion. According to the invention of the present application, by adopting the above-described configuration, when the alkaline solution is brought into contact with the exposed portion, the alkaline solution can be sufficiently spread to the end of the exposed portion, and the formation can be performed with high accuracy and simplicity. Desired shape of the non-polarized part. Furthermore, by adopting the above-mentioned configuration (especially, surface modification treatment), even if no additives (for example, organic solvents such as alcohols) are added to the alkaline solution, the above-mentioned excellent effects can be achieved. As a result, it is possible to manufacture a polarizer having a non-polarizing portion of a desired shape without providing a drainage facility for additives (eg, organic solvents). Accordingly, the manufacturing method of the present invention is also preferable from the viewpoints of cost reduction in manufacturing facilities and environmental concerns.

Form for carrying out the invention

Hereinafter, one embodiment of the present invention will be described, but the present invention is not limited to these embodiments.

A. Manufacturing method of polarizer The production method of the present invention includes bringing an alkaline solution into contact with the exposed portion in a state where the resin film containing the dichroic substance is at least partially exposed and covered with the surface protective film. The non-polarized portion can be formed by bringing the alkaline solution into contact with the exposed portion. In one embodiment, the following polarizing film laminate is used: it includes a resin film containing a dichroic substance and a surface protection film arranged on one side of the resin film, and has a surface containing a dichroic substance exposed on the side. The exposed part of the resin film.

FIG. 1 is a schematic cross-sectional view of a polarizing film laminate used in an embodiment of the present invention. The polarizing film laminate 100 is formed by laminating a surface protective film 50 on the resin film 10 containing a dichroic substance so as to be releasable. The surface protection film 50 has through holes 61 . The polarizing film laminate 100 has an exposed portion 51 where the resin film 10 is exposed from the through hole 61 . The surface protection film 50 is laminated on the resin film 10 so as to be releasable through any appropriate adhesive. In one embodiment, the surface protection film can also be provided as a laminate with an adhesive layer. In this case, for the sake of convenience, the surface protective film on the layered body is sometimes referred to as a base film. In the illustrated example, the protective film 20 is laminated on the surface of the resin film 10 on which the surface protective film 50 is not laminated. The protective film 20 can be used as it is as a protective film of the polarizing plate described later. On the surface of the polarizing film laminate 100 on which the surface protection film 50 having the through holes is not laminated (the outer side of the protection film 20 in the illustrated example), other surface protection films 30 may be laminated in a releasable manner.

The polarizing film laminate is represented by a long strip. By using the elongated polarizing film laminate, for example, a step of contacting with an alkaline solution and a step of contacting with another treatment liquid (eg, a step of contacting an acidic solution) can be continuously performed by immersion. As a result, the productivity of the polarizer can be further improved.

(resin film containing dichroic substances) The above-mentioned resin film containing dichroic substances is a film that can be used as a polarizer. As said dichroic substance, iodine, an organic dye, etc. are mentioned, for example. These may be used alone or in combination of two or more. Preferably, iodine is used. As will be described later, by contacting the iodine complex with an alkaline solution, the iodine complex is reduced and the iodine content is reduced. As a result, a non-polarized portion can be formed, which has appropriate properties as a corresponding portion in a camera system.

Any appropriate resin can be used as the resin for forming the above-mentioned resin film. Preferably, a polyvinyl alcohol-based resin (hereinafter, referred to as "PVA-based resin") can be used. As PVA-type resin, a polyvinyl alcohol and an ethylene-vinyl alcohol copolymer are mentioned, for example. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be calculated|required based on JIS K 6726-1994. By using a PVA-based resin having such a degree of saponification, a polarizer having excellent durability can be obtained. When the degree of saponification is too high, there is a possibility of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. In addition, the average degree of polymerization can be calculated|required based on JISK6726-1994.

The thickness of the dichroic substance-containing resin film can be set to any appropriate value. The thickness is preferably 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less, and particularly preferably less than 10 μm. On the other hand, the thickness is preferably 0.5 μm or more, and more preferably 1 μm or more. With such a thickness, the non-polarized portion can be formed favorably by bringing it into contact with an alkaline solution. Furthermore, the time for contacting the alkaline solution can be shortened. Moreover, the thickness of the part which makes contact with an alkaline solution becomes thinner than other parts. By using a thin resin, the thickness difference between the part in contact with the alkaline solution and the part not in contact can be reduced, and bonding with other components such as a protective film can be performed satisfactorily.

As mentioned above, the above-mentioned resin film containing a dichroic substance is a film that can be used as a polarizer. Specifically, it is preferable that the resin film can be subjected to various treatments such as swelling treatment, stretching treatment, dyeing treatment using the above-mentioned dichroic substance, cross-linking treatment, washing treatment, drying treatment, etc., so as to be able to function as a polarizer. state. When performing various treatments, the resin film may also be a resin layer formed on the substrate. The laminate of the base material and the resin layer can be obtained, for example, by a method of applying a coating liquid containing the above-mentioned resin film-forming material to a base material, a method of laminating a resin film on a base material, and the like.

The above-mentioned dyeing treatment system can be performed, for example, by immersing a resin film in a dyeing liquid. As the dyeing solution, an aqueous iodine solution is preferably used. The blending amount of iodine is relative to 100 parts by weight of water, preferably 0.04 parts by weight to 5.0 parts by weight. In order to improve the solubility of iodine in water, it is better to prepare iodide in an aqueous solution of iodine. As the iodide, potassium iodide can be suitably used. The blending amount of the iodide is based on 100 parts by weight of water, preferably 0.3 parts by weight to 15 parts by weight.

In the above-mentioned stretching treatment, a typical method is to uniaxially stretch the resin film by 3 times to 7 times. Also, the extending direction may correspond to the direction of the absorption axis of the resulting polarizer.

(Surface Protection Film) The purpose of using the surface protection film is to temporarily protect the resin film in the step of contacting with an alkaline solution described later. Thus, the surface protective film can be clearly distinguished from the protective film of the polarizer (eg, the protective film 20 of the illustrated example). For example, in the surface protection film, a through hole is formed in a portion corresponding to the desired shape of the non-polarized portion (specifically, a portion corresponding to the exposed portion). In one embodiment, the surface protective film has a base film composed of any appropriate resin; and a laminate of an adhesive layer provided on one side of the base film, and has the base film and the adhesive. A through-hole through the layer.

As a material for forming the base film, any appropriate forming material can be used. For example, polyester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polyethylene and polypropylene, polyamide-based resins, Polycarbonate resins, these copolymer resins, and the like. In one embodiment, polyester-based resins (especially polyethylene terephthalate-based resins) are preferred. As long as it is such a material, when used as an elongated polarizing film laminate, it has the advantages that the elastic modulus is sufficiently high and the through-hole is not easily deformed even when tension is applied during transportation and/or lamination.

The thickness of the base film can be set to any appropriate value. For example, when used as an elongated polarizing film laminate, it has the advantage that the through-holes are not easily deformed even if tension is applied during transportation and/or bonding, so the thickness of the base film may be 30 μm to 150 μm. In the production method of the present invention, even when a relatively thick base film is used, a non-polarizing portion of a desired shape can be formed with high precision.

The modulus of elasticity of the base film is preferably 2.2kN/mm ² to 4.8kN/mm ² . As long as the elastic modulus of the base film is in such a range, when used as a long polarizing film laminate, for example, there is an advantage that the through-holes are not easily deformed even when tension is applied during conveyance and/or bonding. In addition, the elastic modulus is measured according to JIS K 6781.

The tensile elongation of the base film is preferably 90% to 170%. As long as the tensile elongation of the base film is in this range, for example, when it is used as a long polarizing film laminate, there is an advantage that it is not easily broken during transportation. In addition, the tensile elongation was measured based on JIS K 6781.

As the adhesive constituting the adhesive layer, any appropriate adhesive can be adopted as long as the effects of the present invention can be obtained. As a matrix resin of an adhesive, an acrylic resin, a styrene resin, and a silicone resin are mentioned, for example. Acrylic resins are preferred from the viewpoints of chemical resistance, adhesion to prevent the immersion of the treatment liquid during immersion, and freedom of adherends. Moreover, an adhesive agent may contain a crosslinking agent, As a crosslinking agent which can be contained in an adhesive agent, an isocyanate compound, an epoxy compound, and an aziridine compound are mentioned, for example. The adhesive system may contain, for example, a silane coupling agent. The formulation recipe of the adhesive can be appropriately set according to the purpose.

The adhesive layer can be obtained using any appropriate method. Specific examples include a method of applying an adhesive solution on a base film and drying, and a method of forming an adhesive layer on a release film and transferring the adhesive layer to the base film. Examples of coating methods include roll coating methods such as reverse roll coating and gravure coating, spin coating methods, screen coating methods, fountain coating methods, dipping methods, and spray methods. .

The thickness of the adhesive layer is preferably 5 μm to 60 μm, preferably 5 μm to 30 μm. When the thickness is too thin, the adhesiveness becomes insufficient and air bubbles or the like enter the adhesive interface. When the thickness is too thick, defects such as extrusion of the adhesive are likely to occur. When the surface protective film is a laminate with an adhesive layer, the thickness of the adhesive layer can be adjusted to an appropriate range together with the thickness of the base film.

Any appropriate shape can be adopted for the plan view shape of the through hole of the surface protection film according to the purpose. Specific examples include a circle, an ellipse, a square, a rectangle, and a rhombus. As described above, when the manufacturing method of the present invention is used, a non-polarizing portion of a desired shape can be formed with high precision. Therefore, the shape of the through hole of the surface protection film may be a more complicated shape (for example, a star shape).

In one embodiment, the through-holes of the surface protection film may be smaller in size. For example, when a circular through hole is provided, the diameter may be 2.9 mm or less.

The through holes of the surface protection film, for example, can be removed by mechanical punching (such as punching, engraving blade punching, plotter, water jet) or by removing predetermined parts of the surface protection film (such as laser ablation (laser ablation). ablation) or chemical dissolution).

The polarizing film lamination system is as described above, and another surface protection film (specifically, the surface protection film 30 in FIG. 1 ) may be further laminated on the side where the surface protection film is not disposed. Other surface protection films can be formed using any appropriate forming materials. For example, the above-mentioned surface protective film-forming material may be used, and other resins such as polyolefin (eg, polyethylene) may also be used. By using another surface protection film, in the step of contacting the alkaline solution, the resin film can be more appropriately protected, and as a result, the non-polarized portion can be formed more favorably. Similar to the above-mentioned surface protection films, other surface protection films can be laminated on the polarizing film laminate (in the example, the protection film 20) through any appropriate adhesive, or in the form of a laminate of the substrate film and the adhesive layer. supply.

(Contact with alkaline solution) By bringing the alkaline solution into contact with the resin film (specifically, the exposed portion), the resin film can be decolorized, and a non-polarized portion can be formed by the decolorization. As described above, as the resin film containing a dichroic substance, an iodine-containing resin film is preferably used. When iodine is contained as a dichroic substance, the iodine content can be reduced by bringing an alkaline solution into contact with the exposed portion, and as a result, the non-polarized portion can be selectively formed only in the exposed portion. Therefore, it is possible to selectively form a non-polarized portion in a desired portion of the resin film with very high production efficiency without causing a complicated operation. In addition, when iodine remains in the non-polarized part, even if the iodine complex is destroyed to form the non-polarized part, the iodine complex is formed again with the use of the polarizer, and there is a possibility that it does not have the characteristics required for the non-polarized part. possibility. In the present embodiment, since the content of iodine itself is low, the transparency of the non-polarized portion can be maintained more favorably than when the iodine complex is decomposed by laser light or the like to form the non-polarized portion.

The formation of the non-polarized portion using an alkaline solution will be described in more detail. After touching the exposed portion, the alkaline solution penetrates into the exposed portion. The iodine complex contained in the exposed portion is reduced by the alkali contained in the alkaline solution and becomes an iodide ion. When the iodine complex is reduced to an iodide ion, the polarization performance of the exposed portion is substantially eliminated, and a non-polarized portion is formed in the exposed portion. Moreover, the transmittance of an exposed part improves by reduction of an iodine complex. The iodine which becomes the iodide ion moves from the exposed part to the solvent of the alkaline solution. In this way, a non-polarized portion is selectively formed in a predetermined portion of the resin film, and this non-polarized portion is stable even under humidified conditions. In addition, by adjusting the material for forming the surface protective film, the thickness and mechanical properties, the concentration of the alkaline solution, and the time during which the alkaline solution is brought into contact with the exposed portion, it is possible to prevent the alkaline solution from permeating into the undesired portion (in terms of the result). Non-polarized parts are formed for unnecessary parts).

The step of bringing the alkaline solution into contact with the exposed portion can be performed by any appropriate means. For example, dropping of an alkaline solution, coating, spraying, immersion in an alkaline solution, etc. are mentioned. As described above, by using the surface protection film, since the content of the dichroic substance does not decrease in the portion other than the exposed portion, the non-polarized portion can be formed only in the desired portion by immersing in the alkaline solution. The immersion in an alkaline solution is preferably carried out by using a long polarizing film laminate in which the above-mentioned surface protective film is laminated on one side of the above-mentioned resin film and the other surface protective film is laminated on the other side, and the film is conveyed. The polarizing film laminate is immersed in an alkaline solution. Thereby, since continuous processing can be performed under roller conveyance, the polarizer which has a non-polarizing part can be manufactured at low cost and high productivity. However, at this time, when the transmittance of the non-polarized part is locally lowered due to poor decolorization treatment, and the risk of floating island defects is increased, as in the present invention, the exposed part is subjected to surface modification treatment when it is about to be contacted, and /Or making the contact angle between the exposed part and the alkaline solution 50 degrees or less (it is particularly preferable to perform surface modification treatment on the exposed part during contact), the floating island defect can be effectively reduced.

Any appropriate basic compound can be used as the basic compound contained in the above-mentioned basic solution. Examples of the basic compound include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide, inorganic alkali metal salts such as sodium carbonate, and sodium acetate. and other organic alkali metal salts, ammonia water, etc. The alkaline compound contained in the alkaline solution is preferably an alkali metal hydroxide, more preferably sodium hydroxide, potassium hydroxide, and lithium hydroxide. By using the alkaline solution containing the hydroxide of an alkali metal, the iodine complex can be efficiently ionized, and the non-polarizing portion can be formed more simply. These basic compounds may be used alone or in combination of two or more.

Any appropriate solvent can be used as the solvent of the above-mentioned alkaline solution. Specifically, alcohols, such as water, ethanol, and methanol, ether, benzene, chloroform, and these mixed solvents are mentioned. Since the dichroic substance migrates well to the solvent, the solvent system is preferably water or alcohol.

The concentration of the above-mentioned alkaline solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, preferably 0.1N to 2.5N. When the concentration of the alkaline solution is in such a range, the content of the dichroic substance can be efficiently reduced and the content of the dichroic substance can be prevented from decreasing in parts other than the exposed portion.

The liquid temperature of the above-mentioned alkaline solution is, for example, 20°C to 50°C. The time during which the alkaline solution is brought into contact with the exposed portion can be set according to the thickness of the resin film, the type of the alkaline compound contained in the alkaline solution, and the concentration of the alkaline solution, for example, 5 seconds to 30 minutes.

After the above-mentioned alkaline solution is in contact with the exposed portion (after forming the non-polarized portion), it can be removed by any appropriate means as necessary. As a specific example of the removal method of an alkaline solution, wiping off with a wiping cloth (waste) etc., suction removal, natural drying, heat drying, blow drying, drying under reduced pressure, washing, etc. are mentioned. The drying temperature when the alkaline solution is removed by drying is, for example, 20°C to 100°C.

When the above-mentioned contact is to be performed, the exposed portion is subjected to surface modification treatment. By being subjected to the surface modification treatment, the alkaline solution can be easily wetted and expanded, and the non-polarized portion can be uniformly formed. As a result, it is possible to form a non-polarized portion of a desired shape with high accuracy. Furthermore, by performing the surface modification treatment, it is not necessary to add additives (for example, organic solvents such as alcohols) to the alkaline solution, and a non-polarized portion of a desired shape can be formed with high precision. As a result, drainage facilities for additives (eg, organic solvents) can be omitted. Accordingly, the manufacturing method of the present invention is also preferable from the viewpoints of cost reduction in manufacturing facilities and environmental concerns.

The surface modification treatment of the exposed portion can be performed at any appropriate stage. The surface modification treatment of the resin film may be performed on the entire resin film, or may be performed only on a required portion (for example, a portion corresponding to an exposed portion). In one embodiment, the surface modification treatment is performed on the exposed portion. Specifically, the exposed portion of the resin film covered with the surface protection film is subjected to surface modification treatment. Furthermore, in another embodiment, the surface modification treatment is performed on the entire resin film. Specifically, the resin film subjected to the surface modification treatment is covered with a surface protection film. Since the surface modification treatment can be easily applied to a desired portion, it is preferable to subject the resin film covered with the surface protection film to the surface modification treatment.

As a surface modification treatment method, any appropriate method can be used. For example, corona treatment, plasma treatment, vacuum UV irradiation, and coating of a diluent obtained by diluting a surface modifier such as a silane coupling agent with any appropriate solvent, etc. are mentioned. As the surface modification treatment, corona treatment or a diluted solution of coating a surface modification agent is preferred.

The corona treatment can be carried out using any suitable conditions. For example, the corona discharge electron irradiation amount is preferably 10 to 500 W/m ² /min, more preferably 30 to 300 W/m ² /min.

As the surface modifier, any appropriate surface modifier can be used. For example, a silane coupling agent etc. are mentioned. Examples of the silane coupling agent include organosilane compounds having at least one functional group selected from the group consisting of epoxy groups, acryl groups, methacryloyl groups, amine groups, isocyanate groups, and mercapto groups. . As for the surface modifier system, only one type may be used, or two or more types may be used in combination.

Specifically, as the organosilane compound having an epoxy group, for example, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethyl dimethyl Oxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, etc. . As an organosilane compound which has an acrylyl group, 3-acryloyloxypropyl trimethoxysilane, 3-acryloyloxypropyl triethoxysilane, etc. are mentioned, for example. Examples of organosilane compounds having a methacryloyl group include 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, - Methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, etc. Examples of organosilane compounds having an amino group include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene) Propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, etc. As an organosilane compound which has an isocyanate group, 3-isocyanate propyl triethoxy silane, 3-isocyanate propyl trimethoxy silane, etc. are mentioned, for example. As an organosilane compound which has a mercapto group, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. are mentioned, for example.

As a silane coupling agent, a commercial item can also be used. As a commercial item, "KBM series", "KBE series" by Shin-Etsu Chemical Co., Ltd., etc. are mentioned.

As the solvent, any appropriate solvent can be used. For example, when a silane coupling agent is used, water, methanol, ethanol, or the like can be suitably used. As a coating method, any appropriate method can be used. For example, reverse roll coating, roll coating methods such as gravure coating, spin coating methods, screen coating methods, fountain coating methods, dipping methods, and spray methods are exemplified.

The content of the surface modifier in the diluent can be set to any appropriate value. The content of the surface modifier is, for example, 0.1 parts by weight to 10 parts by weight, preferably 1 part by weight to 5 parts by weight, with respect to 100 parts by weight of the solvent. When the content of the surface modifier is within the above-mentioned range, the exposed portion can have appropriate wettability. When the content of the surface modifier is too small, a sufficient surface modification effect may not be obtained. Moreover, when the content of the surface modifier is too large, the appearance of the obtained polarizer may be defective.

In one embodiment, the contact angle between the exposed portion and the alkaline solution is 50 degrees or less. By setting the contact angle to be 50 degrees or less, the alkaline solution can be sufficiently contacted (overwhelmed) to the end of the exposed portion. The contact angle between the exposed portion and the alkaline solution is preferably 40 degrees or less, more preferably 35 degrees or less. When the contact angle of the exposed part and the alkaline solution is in such a range, the affinity of the exposed part and the alkaline solution can be further improved, and the alkaline solution can be brought into better contact with the exposed part. In addition, the contact angle of an exposed part and an alkaline solution can be measured by the drop method at 25 degreeC using a contact angle meter.

Arbitrary appropriate methods can be mentioned as a method of making the contact angle of an exposed part and an alkaline solution 50 degrees or less. For example, surface modification of a resin film (for example, an exposed part), addition of arbitrary appropriate additives to an alkaline solution, etc. are mentioned. These methods may be used alone or in combination of two or more.

The surface modification of the resin film is as described above as the surface modification treatment.

As an additive in an alkaline solution, any appropriate additive can be used, for example, a surfactant etc. are mentioned. Examples of the surfactant include anionic surfactants such as sodium alkyl sulfate and sodium alkylsulfonate, and cationic surfactants such as alkyltrimethylammonium chloride and dialkyldimethylammonium chloride. , Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene sorbitan fatty acid esters, etc., and zionic surfactants. Preferred are stearyltrimethylammonium chloride and cetyltrimethylammonium chloride. By using these surfactants, the contact angle can be reduced more favorably. Only one type of surfactant may be used, or two or more types may be used in combination.

The addition amount of the additive in the alkaline solution can be set to any appropriate value so that the contact angle becomes 50 degrees or less. The addition amount is relative to 100 parts by weight of the solvent of the alkaline solution, for example, 0.1 parts by weight to 10 parts by weight, preferably 0.5 parts by weight to 3 parts by weight. When the addition amount is too small, the contact angle may not be made sufficiently small. When the addition amount is too large, the appearance of the obtained polarizer may be defective.

(Other steps) The manufacturing method of the polarizer of the present invention may further include any appropriate steps in addition to the step of bringing the alkaline solution into contact with the exposed portion. As other steps, for example, a step of bringing it into contact with an acidic solution, a washing step, and the like can be mentioned.

The production method of the present invention may further include a step of contacting the acidic solution. By further including the step of contacting the acid solution, the non-polarized portion of the desired size can be stably maintained even under humidified conditions. The step of contacting the acidic solution can be performed after the step of contacting the alkaline solution, for example.

Any appropriate acidic compound can be used as the acidic compound contained in the acidic solution. Examples of the acidic compound include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride, and organic acids such as formic acid, oxalic acid, citric acid, acetic acid, and benzoic acid. The concentration of the acidic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, preferably 0.1N to 2.5N.

Regarding the solvent used in the acidic solution, the liquid temperature of the acidic solution, the contact time with the acidic solution, and the contact method, the same conditions as those used in the step of contacting the alkaline solution described above can be employed.

The production method of the present invention may further include a washing step. The washing step may be performed only once, or may be performed a plurality of times. The cleaning step may be performed at any appropriate stage of the manufacturing steps of the polarizer. For example, the resin film that has been brought into contact with the alkaline solution can be washed with any appropriate liquid, and then brought into contact with the acidic solution; or after the step of bringing into contact with the alkaline solution and the acidic solution, Use any suitable liquid for the wash step.

Any appropriate liquid can be used as the liquid used for cleaning. For example, pure water, alcohols, such as methanol and ethanol, acidic aqueous solution, and these mixed solvents etc. are mentioned. In addition, the temperature of the liquid to be used can be set to any appropriate temperature.

B. Polarizer with non-polarizing part Using the polarizer obtained by the method of the present invention, a non-polarizing portion having a desired shape and size can be formed with high precision. Therefore, the polarizer of the present invention can have excellent functionality and design.

A polarizer having a non-polarizing portion can be applied to, for example, an image display device including a camera. Even if the non-polarizing portion of a small size is formed, the camera can sufficiently exhibit the photographing function, and the obtained image display device can also have an excellent appearance.

In one embodiment, the non-polarized portion is circular and its diameter is 2.9 mm or less. Even if the polarizer of the present invention has such a small-sized non-polarizing portion, it can be formed into a desired shape with high accuracy.

When the non-polarized portion is circular, the circularity of the non-polarized portion is preferably 0.060 mm or less, more preferably 0.030 mm or less. When the circularity is within the above-mentioned range, the non-polarized portion is close to a true circle and can be formed with high accuracy. Therefore, even when a small non-polarized portion is required as a camera portion, for example, it is possible to prevent the camera performance from being lowered due to insufficient discoloration. The above roundness refers to the difference between the radius of the circle whose concentric circumscribed deviation sum becomes the smallest and the radius of the inscribed circle relative to the shape of the measured non-polarized part (the true circle using the least square center method). Spend).

The plan view shape of the non-polarization portion can be any appropriate shape as long as it does not adversely affect the camera performance of the video display device. In addition, the transmittance of the non-polarized part (for example, the transmittance measured by using light with a wavelength of 550 nm at 23° C.) is preferably 50% or more, preferably 60% or more, more preferably 75% or more, particularly preferably above 90%. In such a transmittance, the transparency required as a non-polarized part can be ensured. As a result, when the polarizer is arranged so that the non-polarized portion corresponds to the camera portion of the video display device, it is possible to prevent adverse effects on the imaging performance of the camera.

The non-polarized portion is preferably capable of significantly suppressing the occurrence of floating island defects, and more preferably substantially free of floating island defects. The so-called floating island defect refers to a portion with low transmittance due to poor decolorization in the non-polarized portion. Among the relative transmittances measured per pixel (representatively, 5 μm×5 μm) of the non-polarized portion, the minimum relative transmittance is, for example, 60.0% or more, or preferably 65.0% or more. In addition, the occurrence rate of the floating island defect in the non-polarized portion is, for example, 0.8% or less. Here, the relative transmittance refers to a 256-level tone with the average brightness of the discolored part (non-polarized part) set to 100% and the average brightness of the non-bleeded part (part other than the non-polarized part) to 0%. A gray scale (gray scale) represents a non-polarized portion and is converted into transmittance. In order to suppress the floating island defect, surface modification treatment is effective, and corona treatment can be particularly effective.

C. Polarizing plate The polarizer system can be practically provided as a polarizing plate. The polarizing plate has: a polarizer; and a protective film arranged on at least one side of the polarizer. In practice, the polarizing plate system has an adhesive layer as the outermost layer. Typically, the adhesive layer is the outermost layer on the side of the image display device. The release film can be temporarily adhered to the adhesive layer in a releasable manner.

Examples of materials for forming the protective film include cellulose-based resins such as cellulose diacetate and cellulose triacetate, (meth)acrylic-based resins, cycloolefin-based resins, olefin-based resins such as polypropylene, and polyolefin resins. Ester-based resins such as ethylene phthalate-based resins, polyamide-based resins, polycarbonate-based resins, these copolymer resins, and the like. The thickness of the protective film is preferably 10 μm to 100 μm. The protective film is typically laminated on a polarizer through an adhesive layer (specifically, an adhesive layer and an adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive and an active energy ray-curable adhesive. The adhesive layer is represented by an acrylic adhesive.

The polarizing plate may further have any appropriate optical function layer according to the purpose. Typical examples of the optical functional layer include retardation films (optical compensation films) and surface treatment layers. Moreover, the said protective film may have an optical compensation function (specifically, it may have an appropriate refractive index ellipsoid, in-plane retardation, and thickness direction retardation according to the purpose).

The surface treatment layer may be arranged on the visible side of the polarizing plate. Typical examples of the surface treatment layer include a hard coat layer, an antireflection layer, and an antiglare layer.

D. Video display device The image display device of the present invention includes the above-described polarizer. As an image display device, a liquid crystal display device and an organic electroluminescent element are mentioned, for example. Specifically, the liquid crystal display device includes a liquid crystal panel, and the liquid crystal panel includes: a liquid crystal cell; and the polarizer disposed on one side or both sides of the liquid crystal cell. The organic EL element is provided with an organic EL panel in which the above-mentioned polarizer is arranged on the viewing side. The polarizer can be arranged so as to correspond to the camera portion of the image display device on which the non-polarized portion is mounted. Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. In addition, the evaluation method used in this Example is as follows. [roundness] Roundness was determined using the least squares center method. The measurement system used an ultra-high-speed flexible image processing system (manufactured by KEYENCE, trade name: XG-7500). The non-polarized part of the polarizer was imaged using a camera (measurement distance: 250 mm, measurement angle: 90°). Edge detection is performed from the captured image, and a circle (hereinafter, also referred to as a non-polarized portion approximate circle) is drawn. Next, using the least squares method, the true circles (inscribed circles and circumscribed circles) of the approximate circles in the contact non-polarized portion and their centers are calculated. The distance (specifically, the radius) from the center of each calculated true circle to the periphery of the approximate circle of the non-polarized portion is measured, and the difference (roundness) between the part where the distance becomes the largest and the part where the distance becomes the smallest is calculated. When the roundness is 0.060 mm or less, it can be suitably used in applications such as video display devices. [Minimum relative transmittance at non-polarized portion (evaluation of floating island defects)] Draw an inscribed circle using the center and minimum radius of the circle calculated by the above roundness measurement. Next, the average brightness value of the polarizer portion is defined as 0%, and the average brightness value in the inscribed circle is defined as 100%, and the brightness value in the inscribed circle is obtained for each pixel (about 5 μm×about 5 μm) and calculated. relative transmittance. The lowest relative transmittance within the inscribed circle is defined as the minimum relative transmittance. When the representative minimum transmittance is less than 60.0%, this part can be regarded as a floating island defect.

[Example 1] A circular through hole having a diameter of 1.9 mm was formed in a resin film (PET resin film, thickness 38 μm, thickness of the adhesive layer: 5 μm) to which the adhesive was adhered using a pinnacle blade to obtain a through hole having a diameter of 1.9 mm. the surface protective film. The obtained surface protective film was pasted on the polarizer side surface of a polarizer (polarizer (transmittance 42.3%, thickness 5 μm)/protective film (thickness 25 μm)) with a total thickness of 30 μm through an adhesive layer to obtain Polarizing film laminate. The exposed part of the obtained polarizing film laminate was subjected to corona discharge treatment (corona discharge electron irradiation amount: 100 W/m ² /min) using a desktop corona treatment apparatus (manufactured by Kasuga Electric). After the corona discharge treatment, the contact angle between the exposed portion and water was measured by the droplet method using a contact angle meter (manufactured by Kyowa Interface Science). The value of the measured contact angle was 28 degrees. Next, an alkaline solution (aqueous sodium hydroxide solution, 0.1 mol/L (0.1 N)) at room temperature was dropped onto the exposed portion of the polarizing film laminate and left to stand for 1 minute. Next, the sodium hydroxide aqueous solution dripped was removed using a wiping cloth, and the polarizer which has a non-polarization part was obtained. The circularity and minimum relative transmittance of the non-polarized portion of the obtained polarizer were measured. The results are shown in Table 1. Furthermore, an image showing the state of the non-polarized portion is shown in FIG. 2 .

[Example 2] A diluent was obtained by mixing 1 weight part of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM-303) and 99 parts by weight of a solvent (ethanol). A polarizer having a non-polarizing portion was obtained in the same manner as in Example 1, except that the obtained diluent was applied to the exposed portion and dried instead of the corona treatment. After the dilution liquid was applied and dried, the contact angle of the exposed portion with water was measured by the droplet method using a contact angle meter (manufactured by Kyowa Interface Science). The value of the measured contact angle was 45 degrees. The circularity and minimum relative transmittance of the non-polarized portion of the obtained polarizer were measured. The results are shown in Table 1. Furthermore, an image showing the state of the non-polarized portion is shown in FIG. 2 .

[Example 3] A circular through hole with a diameter of 2.8 mm was formed in a long resin film (PET resin film, thickness 38 μm, thickness of the adhesive layer: 5 μm) with an etching blade to obtain a through hole with a diameter of 2.8 mm. the surface protective film. In addition, the above-mentioned long-shaped adhesive-adhering resin film is directly used as another surface protection film. By roll-to-roll, stick the above-mentioned surface protective film on the polarizer side surface of the long polarizing plate (polarizer (transmittance 42.3%, thickness 5 μm)/protective film (thickness 25 μm)) with a total thickness of 30 μm, and The above-mentioned other surface protection films were bonded together on the protective film side surface of the polarizing plate to obtain an elongated polarizing film laminate. While conveying the obtained elongated polarizing film laminate, corona discharge treatment (corona discharge electron irradiation amount: 120 W/m) was performed on the exposed portion of the polarizing film laminate using a corona treatment apparatus (manufactured by Kasuga Electric). ² /min). After the corona discharge treatment, the contact angle between the exposed portion and water was measured by the droplet method using a contact angle meter (manufactured by Kyowa Interface Science). The value of the measured contact angle was 32 degrees. Next, the polarizing film laminate with the adhesive resin film facing downward was conveyed, and immersed in an alkaline solution (sodium hydroxide aqueous solution, 2 mol/L (2N)) at room temperature for 15 seconds. Next, the adhered aqueous sodium hydroxide solution is washed and dried to obtain a polarizer having a non-polarized portion. The circularity and minimum relative transmittance of the non-polarized portion of the obtained polarizer were measured. The results are shown in Table 1. Furthermore, an image showing the state of the non-polarized portion is shown in FIG. 2 . In addition, the defect rate at the time of continuous production of 53 rolls (long-shaped polarizing film laminate) under the same conditions is shown in FIG. 3 together with the results of Comparative Example 2. FIG. In addition, a roundness of 0.040 mm or more or a minimum relative transmittance of less than 60.0% was judged to be defective.

[Comparative Example 1] A polarizer having a non-polarizing portion was obtained in the same manner as in Example 1, except that the surface modification treatment was not performed on the exposed portion. The contact angle of the untreated exposed portion with water was 62 degrees. The circularity and minimum relative transmittance of the non-polarized portion of the obtained polarizer were measured. The results are shown in Table 1. Furthermore, a video showing the state of the non-polarized portion is shown in FIG. 2 .

[Comparative Example 2] A polarizer having a non-polarizing portion was obtained in the same manner as in Example 3 except that the surface modification treatment was not performed on the exposed portion. The contact angle of the untreated exposed portion with water was 63 degrees. The circularity and minimum relative transmittance of the non-polarized portion of the obtained polarizer were measured. The results are shown in Table 1. Furthermore, a video showing the state of the non-polarized portion is shown in FIG. 2 . In addition, the defect rate in the case of continuous production of 14 rolls (long-shaped polarizing film laminate) under the same conditions is shown in FIG. 3 together with the results of Example 3.

[Table 1] Contact angle (∘) Roundness (mm) Minimum relative transmittance (%) Example 1 28 0.014 72.4 Example 2 45 0.008 65.2 Example 3 32 0.014 74.3 Comparative Example 1 62 0.087 73.4 Comparative Example 2 63 0.015 5.6

As is clear from Table 1, when the manufacturing method of the example of the present invention is used, a non-polarized portion having excellent roundness and minimum relative transmittance (floating island defect) can be obtained. Specifically, in Examples 1 and 2 in which the exposed portion is subjected to surface modification treatment and the step of contacting the alkaline solution is performed, although the non-polarized portion has a small size of 1.9 mm in diameter, it can be formed with high precision The required non-polarizing part. On the other hand, in Comparative Example 1 in which the contact step with the alkaline solution was performed without performing the surface modification treatment, the shape of the non-polarized portion was deformed, and there was room for improvement. Moreover, when Example 3 is compared with the comparative example 2, it becomes clear that by performing a surface modification process, a floating island defect can be suppressed and a defect rate can be reduced remarkably. Industrial Utilization Possibilities

The polarizer of the present invention is suitable for use in image display devices (liquid crystal display devices, organic EL devices) with cameras, such as mobile phones such as smart phones, notebook PCs, and tablet PCs.

10: Resin film 20: Protective film 30: Surface protection film 50: Surface protection film 51: exposed part 61: Through hole 100: polarizing film laminate

FIG. 1 is a schematic cross-sectional view of a polarizing film laminate used in an embodiment of the present invention. 2 is an image showing the state of the non-polarized portion of the polarizers obtained in Examples 1 to 3 and Comparative Examples 1 to 2. FIG. 3 is a graph showing the degree of occurrence of defective rates in Example 3 and Comparative Example 2 in comparison.

10: Resin film

20: Protective film

30: Surface protection film

50: Surface protection film

51: exposed part

61: Through hole

100: polarizing film laminate

Claims (3)

A method for manufacturing a polarizer, comprising: in a state where a resin film containing a dichroic substance is covered by a surface protective film in a manner of at least a part of which is exposed, contacting an alkaline solution with the exposed part; and the exposed part and the alkali The contact angle of the sexual solution is 50 degrees or less. The method for producing a polarizer according to claim 1, wherein the alkaline solution further contains an additive. The method for producing a polarizer according to claim 1 or 2, wherein the contacting is performed in a state where the surface of the resin film on the opposite side to the surface protection film is covered with another surface protection film, and the resin film is conveyed while being dipped in the surface protection film. performed with the aforementioned alkaline solution.

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