TW202017994A - Polarizer production method - Google Patents

Abstract

In order to provide a method whereby polarizers having excellent reliability in high-temperature environments can be easily and inexpensively produced, this polarizer production method includes: at least the stretching and dyeing of a polyvinyl alcohol-based resin film; and, after dyeing, the coating or spraying of the polyvinyl alcohol-based resin film, using a processing liquid that includes citric acid and lithium hydroxide. The processing liquid has a pH in the range of 2.5-6.0 and has a buffering action in said pH range.

Description

Manufacturing method of polarizer

The invention relates to a method for manufacturing polarizers.

Background of the invention In a typical image display device, that is, a liquid crystal display device, due to its image forming method, polarizers (essentially, polarizers including polarizers) are arranged on both sides of the liquid crystal cell. The polarizer can be manufactured by dyeing a polyvinyl alcohol (PVA) resin film with a dichroic substance such as iodine (for example, Patent Documents 1 and 2). In recent years, the demand for thinner image display devices has greatly increased. Therefore, further thinning of the polarizer is also required. However, the thinner the polarizer is, the more the reliability will be reduced under high temperature and high humidity environment.

Prior technical literature Patent Literature Patent Document 1: Japanese Patent No. 5048120 Patent Document 2: Japanese Patent Laid-Open No. 2013-156391

Summary of the invention Problems to be solved by invention The present invention was made to solve the above-mentioned problems, and its main object is to provide a method for easily and inexpensively producing a polarizer having high reliability even in a high-temperature environment.

Means to solve the problem The manufacturing method of the polarizer of the present invention includes at least stretching and dyeing the polyvinyl alcohol-based resin film, and includes: coating or spraying a treatment liquid on the polyvinyl alcohol-based resin film after the dyeing, the treatment liquid including citric acid and Lithium hydroxide. The pH of the treatment liquid is in the range of 2.5 to 6.0, and has a buffering effect in the pH range. In one embodiment, the polyvinyl alcohol-based resin film is a polyvinyl alcohol-based resin layer formed by applying a coating solution containing a polyvinyl alcohol-based resin to a substrate, and the substrate and the polyethylene The layered system of alcohol resin layer is used for stretching and dyeing. Another aspect of the present invention is to provide a method for manufacturing a polarizing plate with an adhesive layer. The manufacturing method is a manufacturing method of a polarizing plate with a polarizer, a protective film and an adhesive layer with an adhesive layer, the protective film is disposed on one side of the polarizer, and the adhesive layer is disposed on the other side of the polarizer One side; the manufacturing method includes the following steps: manufacturing a polarizer using the above method; attaching a protective film to one side of the polarizer manufactured by the manufacturing method; and forming an adhesion containing a lithium salt on the other side of the polarizer剂层。 Agent layer.

Invention effect The manufacturing method according to the present invention can provide a polarizer with high reliability even in a thin type under high temperature and high humidity environment. In the manufacturing method of the present invention, after the polyvinyl alcohol-based resin is dyed, a treatment solution containing citric acid and lithium hydroxide is applied or sprayed onto the polyvinyl alcohol-based resin film. As a result, a polarizer with high reliability in a high-temperature environment can be obtained. Moreover, this manufacturing method requires no special equipment and no complicated operations, so that the polarizer as described above can be manufactured simply and inexpensively.

In addition, the polarizing plate with an adhesive layer with an adhesive layer containing a lithium salt as a conductive agent may suffer from the problem that the desired conductive performance of the adhesive layer is impaired. Specifically, we believe that the lithium ions contained in the adhesive layer can stabilize the iodine complex more than other cations (such as potassium ions) contained in the polarizer. The lithium ions in the adhesive layer will exchange with other cations (such as potassium ions) contained in the polarizer, so that the lithium ions contained in the adhesive layer will be reduced, and the desired conductive performance of the adhesive layer will be damaged over time. situation. In the present invention, a polarizing plate is produced using a polarizing member treated with a processing solution containing citric acid and lithium hydroxide. In this way, the lithium ions contained in the treatment liquid will first take up the polarizer, so the lithium ion contained in the adhesive layer and other cations contained in the polarizer can be suppressed from excessive exchange reaction, and the desired characteristics of the adhesive layer can be maintained.

Forms for carrying out the invention The embodiments of the present invention are described below, but the present invention is not limited by these embodiments.

A. Manufacturing method of polarizer A-1. Overview of the manufacturing method of polarized parts The method of manufacturing a polarizer according to an embodiment of the present invention includes at least stretching and dyeing a polyvinyl alcohol (PVA) resin film. Representatively, the manufacturing method includes a step of preparing a PVA-based resin film, an extension step, a swelling step, a dyeing step, a cross-linking step, a washing step, and a drying step. Each step of supplying the PVA-based resin film can be performed in an arbitrary and appropriate order and timing. Therefore, each step may be performed in the above order, or may be performed in an order different from the above. One step can also be carried out multiple times according to needs. In addition, the steps other than the above (for example, the insolubilization step) can be performed at an arbitrary and appropriate timing, and steps other than the dyeing step can be omitted.

A-1-2. PVA resin film Examples of the PVA-based resin forming the PVA-based resin film include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying the ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based 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 degree of saponification can be obtained in accordance with JIS K 6726-1994. By using the PVA-based resin with the degree of saponification, a polarizer with excellent durability can be obtained. When the degree of saponification is too high, there is a risk of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average polymerization degree is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. In addition, the average degree of polymerization can be obtained in accordance with JIS K 6726-1994.

The thickness of the PVA-based resin film is not particularly limited, and can be set according to the desired thickness of the polarizer. The thickness of the PVA-based resin film is, for example, 10 μm to 200 μm.

In one embodiment, the PVA-based resin film may be a PVA-based resin layer formed on the substrate. The laminate of the base material and the PVA-based resin layer can be produced by, for example, the following method: a method of applying the coating solution containing the above-mentioned PVA-based resin to the base material, and stacking the PVA-based resin film on the base material Methods, etc. In such cases, the laminate of the base material and the PVA-based resin layer can be used for the stretching step, swelling step, dyeing step, cross-linking step, washing step, etc.

Each step is described below, but as described above, each step can be performed in an arbitrary and appropriate order, and is not limited by the described order.

A-2. Coating or spraying treatment liquid The manufacturing method of the present invention includes applying or spraying a treatment liquid containing citric acid and lithium hydroxide to a PVA-based resin film after dyeing. The treatment liquid can be applied or sprayed after dyeing, and can also be carried out at an arbitrary and appropriate timing. Specifically, the coating or spraying of the treatment liquid may be performed before the crosslinking step or may be performed after the crosslinking step; it may be performed before the washing step or may be performed after the washing step. When the stretching step is performed after the dyeing step, the coating or spraying of the treatment liquid may be performed before the stretching step or may be performed after the stretching step. When the swelling step is performed after the dyeing step, the coating or spraying of the treatment liquid may be performed before the swelling step or may be performed after the swelling step. When the insolubilization step is performed after the dyeing step, the coating or spraying of the treatment liquid may be performed before the insolubilization step or may be performed after the insolubilization step. Representatively, the coating or spraying of the treatment liquid may be performed after the washing step and before the drying step, or may be performed between the first drying step and the second drying step when the drying step is performed in two stages.

The treatment liquid used in the present invention is an aqueous solution containing citric acid and lithium hydroxide. For example, the treatment liquid containing citric acid has a buffering effect in a wider pH range than other buffering materials. As a result, it can have a more excellent anti-tarnish effect in a high-temperature environment. In addition, the pH of the treatment liquid can be adjusted to a desired range by including lithium hydroxide. The pH of the treatment liquid is in the range of 2.5 to 6.0, and the treatment liquid has a buffering effect in this range. The pH of the treatment liquid should be 3.0 to 5.7, more preferably 3.5 to 4.8.

The concentration of citric acid in the treatment liquid is preferably 0.05% by weight to 5% by weight, and preferably 0.1% by weight to 0.5% by weight.

The manufacturing method of the present invention can significantly suppress the discoloration of the polarizer in a high-temperature environment by applying or spraying the treatment liquid to the PVA-based resin film. I think this is because the buffering effect of the treatment liquid in the predetermined pH range can suppress the generation of protons in the PVA-based resin, and as a result, the generation of multiple double bonds (polyalkylation) in the PVA-based resin in a high-temperature environment can be suppressed. Suppression of discoloration. In consideration of manufacturing efficiency, the contact with the processing liquid can usually be performed by immersing the PVA-based resin film in the processing liquid. However, the polarizer manufactured by the manufacturing method including the immersion in the treatment liquid swells when the PVA-based resin film is immersed, so the state of the iodine complex in the PVA-based resin film tends to change, and there is polarized light before and after the immersion The absorption spectrum of the piece is prone to change. On the other hand, by coating or spraying the PVA-based resin film, the problem of changes in the absorption spectrum of the polarizer before and after the immersion during immersion can be prevented, and the polyenelation of PVA can be further satisfactorily prevented.

The treatment liquid can be applied or sprayed onto the PVA-based resin film by any appropriate method. Examples of the coating mechanism include a reverse coater, a gravure coater (direct, reverse, or indirect), a bar reverse coater, a roll coater, a die coater, a bar coater, and a bar coater. The spraying mechanism may be, for example, any appropriate spraying device (for example, a pressure nozzle type or a rotating disc type).

A-3. Extension steps In the stretching step, the PVA-based resin film is uniaxially stretched or biaxially stretched 3 to 7 times on behalf of the upper system. The extending direction may be the long-side direction (MD direction) of the film, the width direction (TD direction) of the film, or both the long-side direction and the width direction. The stretching method may be dry stretching, wet stretching, or a combination of these. In addition, the PVA-based resin film may be stretched during the cross-linking step, swelling step, dyeing step, and the like. In addition, the extending direction may correspond to the direction of the absorption axis of the obtained polarizer.

A-4. Swelling procedure The swelling step is usually carried out before the dyeing step. The swelling step can be performed, for example, by immersing the PVA-based resin film in a swelling bath. The swelling bath can usually use distilled water, pure water and other water. The swelling bath may also contain any suitable other ingredients than water. Other components include solvents such as alcohols, additives such as surfactants, and iodides. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Potassium iodide should be used. The temperature of the swelling bath is, for example, 20°C to 45°C. In addition, the immersion time is, for example, 10 seconds to 300 seconds.

A-5. Dyeing procedure The dyeing step is a step of dyeing the PVA-based resin film with a dichroic substance. It should be carried out by making it absorb dichroic substances. Examples of the adsorption method include a method of immersing the PVA-based resin film in a dyeing solution containing a dichroic substance, a method of applying the dyeing solution to the PVA-based resin film, and spraying the dyeing solution to the PVA-based resin Resin film method, etc. It is desirable to immerse the PVA-based resin film in the dyeing solution. Because it can absorb dichroic substances well.

Examples of the dichroic substance include iodine and dichroic dyes. And iodine is appropriate. When iodine is used as the dichroic substance, an aqueous iodine solution is preferably used as the dyeing solution. The iodine content of the iodine aqueous solution is preferably 0.04 to 5.0 parts by weight relative to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is appropriate to mix iodide in the iodine aqueous solution. Potassium iodide should be used as iodide. The content of iodide is preferably 0.3 to 15 parts by weight relative to 100 parts by weight of water.

The liquid temperature of the dyeing liquid during dyeing can be set to an arbitrary and appropriate value, for example, 20°C to 50°C. When the PVA-based resin film is immersed in the dyeing liquid, the immersion time is, for example, 5 seconds to 5 minutes.

A-6. Cross-linking steps In the cross-linking step, a boron compound is usually used as a cross-linking agent. Examples of boron compounds include boric acid and borax. And boric acid is suitable. In the cross-linking step, the boron compound is usually used in the form of an aqueous solution.

When using a boric acid aqueous solution, the boric acid concentration of the boric acid aqueous solution is, for example, 1% by weight to 15% by weight, preferably 1% by weight to 10% by weight. The aqueous solution of boric acid can also contain iodides such as potassium iodide, zinc compounds such as zinc sulfate and zinc chloride.

The cross-linking step can be carried out by any suitable method. For example, a method of immersing a PVA-based resin film in an aqueous solution containing a boron compound, a method of applying an aqueous solution of a boron-containing compound to the PVA-based resin film, or spraying an aqueous solution of a boron-containing compound onto the PVA-based resin film Methods. It is suitable to be immersed in the aqueous solution containing boron compound.

The temperature of the solution used for crosslinking is, for example, above 25°C, preferably 30°C to 85°C, and more preferably 40°C to 70°C. The dipping time is, for example, 5 seconds to 800 seconds, preferably 8 seconds to 500 seconds.

A-7. Washing steps The washing step means that the upper part is carried out after the cross-linking step. The washing step is representatively performed by immersing the PVA-based resin film in the washing solution. A representative example of the cleaning solution can be pure water. Potassium iodide can also be added in pure water.

The temperature of the cleaning solution is, for example, 5°C to 50°C. The dipping time is, for example, 1 second to 300 seconds.

A-8. Drying step The drying step can be performed by any appropriate method. Examples of drying methods include natural drying, air drying, reduced-pressure drying, and heating drying. And it should be heated and dried. When heating and drying, the heating temperature is, for example, 30°C to 100°C. In addition, the drying time is, for example, 20 seconds to 10 minutes.

B. Polarizer The thickness of the polarizer manufactured by the manufacturing method of the present invention is preferably 80 μm or less in one embodiment, 20 μm or less in another embodiment, and 10 μm or less in another embodiment. It is preferably 5 μm or less in one embodiment, 3 μm or less in another embodiment, and 2 μm or less in another embodiment. The thickness of the polarizer is preferably 0.5 μm or more in one embodiment, 0.6 μm or more in another embodiment, and 0.8 μm or more in another embodiment. According to the manufacturing method of the present invention, even if it is a thin polarizer, the desired monomer transmittance can be achieved as described later, and the change in the monomer transmittance under a high-temperature environment can be significantly suppressed.

The polarizer manufactured by the manufacturing method of the present invention will contain lithium. The lithium content (Li _POL ) of the polarizer is preferably 0.3% by weight or more, and more preferably 0.35% by weight or more. When the lithium content (Li _POL ) is in the above range, it can be suitably used for a method of manufacturing a polarizing plate with an adhesive layer described later. Specifically, by using a polarizer having the lithium content, even if a polarizing plate having an adhesive layer containing a lithium salt as a conductive agent is formed, the adhesive layer can still suitably maintain desired characteristics. The lithium content (Li _POL ) of the polarizer is, for example, 10% by weight or less. The lithium content of the polarizer can be measured by ICP-MS.

From the viewpoint of imparting sufficient polarizing performance and optimal transmittance, the iodine content of the polarizer manufactured by the manufacturing method of the present invention can be set appropriately according to the thickness of the polarizer. For example, when the thickness of the polarizer is greater than 5 μm and less than 10 μm, the iodine content is preferably 3.5% by weight to 8.0% by weight; when the thickness of the polarizer is greater than 3 μm and less than 5 μm, the iodine content is preferably 5.0% by weight to 13.0% by weight %; when the thickness of the polarizer is less than 3 μm, the iodine content should be 10.0% by weight to 25.0% by weight. The "iodine content" in this specification means the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, the iodine iodide ion (I ^-) is present in the form of a polarizer and the like, and the iodine content of the present specification is meant that molecular iodine (I _2), polyiodide ions _{^{(I 3 - -, I 5}} ) Contains the amount of iodine in all these forms. The iodine content can be calculated using a calibration curve method such as fluorescent X-ray analysis. In addition, the polyiodide ion exists in the state where the PVA-iodine complex is formed in the polarizer. By forming the complex, the absorption dichroism can be exhibited in the wavelength range of visible light. Specifically, the complexes (PVA · I ₃ ^-) PVA and tri-iodide ions having a light absorption peak around 470nm; PVA complexes with five iodide ions (PVA · I ₅ ^-) having a light absorption near 600nm peak. As a result, the polyiodide ion can absorb light in a wide range of visible light according to its morphology. On the other hand, an iodide ion (I ^-) having a light absorption peak around 230nm, which absorption of visible light associated with insubstantial. Therefore, the polyiodide ion existing in the complex state with PVA is mainly related to the absorption performance of the polarizer.

The single transmittance (Ts) of the polarizer produced by the manufacturing method of the present invention is preferably 30.0%~43.0%, and more preferably 35.0%~41.0%. The polarization degree of the polarizer is preferably 99.9% or more, preferably 99.95% or more, and more preferably 99.98% or more. By setting the transmittance of the monomer lower and the polarization degree higher, the contrast can be improved, and the black display can be displayed more black, so an image display device with excellent image quality can be realized. In addition, the unit transmittance is the value measured by a spectrophotometer with an integrating sphere. The unit transmittance is the Y value measured with a 2 degree field of view (C light source) of JIS Z 8701 and corrected for optical performance. For example, a spectrophotometer with an integrating sphere (manufactured by Nippon Spectroscopy Co., Ltd., product name: V7100) can be used. ) To be measured.

The absolute value of the change in monomer transmittance ΔTsa of the polarizer produced by the manufacturing method of the present invention after being left in an environment of 85° C. for 500 hours is preferably 5.0% or less, and more preferably 3.0% or less. The polarizer manufactured by the manufacturing method of the present invention can achieve the above-mentioned desired monomer transmittance and polarization degree, and at the same time, the variation of the monomer transmittance in a high-temperature environment is significantly suppressed. Therefore, a polarizer whose color change is suppressed in a high-temperature environment can be realized. As a result, the polarizer is also suitable for applications requiring heat resistance. In my opinion, the excellent effect is to apply or spray a treatment liquid having a predetermined pH and buffering effect on the polyvinyl alcohol-based resin film in the step after dyeing of the polarizer manufacturing method as described above, thereby preventing the resulting polarized light The parts are polyalkylated under high temperature environment and achieved. It can solve the newly discovered problems of making very thin polarizers (such as those with a thickness of 7 μm or less) that were very difficult to manufacture in the past, and it is actually an unexpectedly excellent effect. In addition, the amount of change in the transmittance of the monomer ΔTsa is preferably a negative value (that is, less than 0.0%). Also, the amount of change in single-piece transmittance can be represented by the following formula _{ΔTsa: ΔTsa (%) = Tsa 500} -Ts 0 Here, Ts ₀ transmittance of a monomer before the heating test, Tsa ₅₀₀ is placed in an environment of 85 ℃ Monomer transmittance after 500 hours. In addition, in this specification, when the single cell transmittance is only described as Ts, it means the single cell transmittance Ts ₀ before heating.

The absolute value of the change in monomer transmittance ΔTsb after the polarizer produced by the manufacturing method of the present invention is left at 60° C. and 90% RH for 500 hours is preferably 3.5% or less, and more preferably 3.0% or less. The polarizer manufactured by the manufacturing method of the present invention can achieve the above-mentioned desired monomer transmittance and polarization degree, and at the same time, the change amount of the monomer transmittance under a high humidity environment is also significantly suppressed. Therefore, a polarizer whose color change is suppressed even in a high-humidity environment can be realized. In addition, the change amount ΔTsb of the transmittance of the monomer is preferably a positive value (that is, greater than 0.0%). Also, the amount of change in single-piece transmittance can be represented by the following formula _{ΔTsb: ΔTsb (%) = Tsb 500} -Ts 0 Here, Ts ₀ as described before for the single transmittance of the heating test, Tsb ₅₀₀ as 60 ℃, 90 Monomer transmittance after 500 hours of storage in %RH environment.

C. Manufacturing method of polarizing plate with adhesive layer An embodiment of the present invention provides a method for manufacturing a polarizing plate with an adhesive layer. The method for manufacturing a polarizing plate with an adhesive layer of the present invention is a method for manufacturing a polarizing plate having a polarizer, a protective film and an adhesive layer, the protective film is disposed on one side of the polarizer, and the adhesive layer is disposed on the The other side of the polarizer. The manufacturing method includes the following steps: manufacturing a polarizer using the method described in item A above; bonding a protective film on one side of the polarizer manufactured by the manufacturing method; and forming a lithium salt-containing one on the other side of the polarizer Adhesive layer.

C-1. Making polarizer The polarizer can be produced by the method described in item A above. As mentioned above, the polarizer produced by the method described in item A will contain lithium. Since the adhesive layer containing the lithium salt is formed on the polarizer, it is possible to reduce the time-varying changes in the characteristics of the adhesive layer. As a result, excellent moisture resistance can be achieved.

C-2. Laminating protective film Next, a protective film is attached to one side of the polarizer. Any suitable protective resin film can be used for the protective film. Examples of resin film forming materials include (meth)acrylic resins, cellulose resins such as diacetyl cellulose and triethyl cellulose, cycloolefin resins such as norbornene resins, and olefin resins such as polypropylene. , Ester resins such as polyethylene terephthalate resins, polyamide resins, polycarbonate resins and copolymer resins thereof. In addition, "(meth)acrylic resin" means acrylic resin and/or methacrylic resin.

In one embodiment, the (meth)acrylic resin is a (meth)acrylic resin having a glutarimide structure. (Meth)acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) are described, for example, in the following documents: Japanese Patent Laid-Open No. 2006-309033, Japanese Patent Laid-Open No. 2006-317560 Gazette, Japanese Unexamined Patent Publication No. 2006-328329, Japanese Unexamined Patent Publication No. 2006-328334, Japanese Unexamined Patent Publication No. 2006-337491, Japanese Unexamined Patent Publication No. 2006-337492, Japanese Unexamined Patent Publication No. 2006-337493, Japanese Unexamined Patent Publication 2006-337569, JP 2007-009182, JP 2009-161744, and JP 2010-284840. These descriptions are cited as references in this specification.

The protective film is attached to the polarizer through an arbitrary and appropriate adhesive layer.

In addition, when using a laminate of a base material and a PVA-based resin layer to manufacture a polarizer, it can be used as a protective film without peeling the base material. In addition, any appropriate optical functional film may be used as a protective film (and another protective film in the presence of it) according to the purpose. Examples of optically functional films include phase difference films and reflective polarizers (brightness enhancing films).

C-3. Formation of adhesive layer Any suitable method can be used for the method of forming the adhesive layer. Representative examples of the forming method include the following methods: a method of applying an adhesive composition to a separation member subjected to peeling treatment, etc., and drying and removing the polymerization solvent, etc. to form an adhesive layer, and then transferring it to a polarizer Or, a method of applying the adhesive composition to the polarizer, drying and removing the polymerization solvent, etc. to form an adhesive layer on the polarizer. In addition, when applying the adhesive, one or more solvents other than the polymerization solvent may be additionally added according to needs.

C-3-1. Adhesive composition The adhesive composition constituting the adhesive layer includes a base polymer and a lithium salt.

C-3-2. Base polymer Representative examples of the base polymer include (meth)acrylic polymers ((meth)acrylic resins). The (meth)acrylic polymer represents a monomer unit derived from an alkyl (meth)acrylate as a main component. (Meth)acrylic acid alkyl esters are (meth)acrylic acid alkyl esters. Examples of the alkyl group forming the alkyl ester include straight-chain or branched-chain alkyl groups having 1 to 18 carbon atoms. Specific examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl , Decyl, isodecyl, dodecyl, isomyristyl, lauryl, thirteen, fifteen, sixteen, seventeen, and eighteen. These can be used alone or in combination. The average carbon number of the alkyl group contained in the alkyl (meth)acrylate is preferably 3-9.

The base polymer may also contain monomer units derived from any appropriate copolymerization components depending on the purpose. Examples of the copolymerization component include hydroxyl group-containing monomers, carboxyl group-containing monomers, acid anhydride group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, (N-substituted) amide-based monomers, (Meth)acrylic acid alkylaminoalkyl-based monomer, (meth)acrylic acid alkoxyalkyl-based monomer, succinimide-based monomer, maleimide-based monomer, Iconamide Amine monomer, vinyl monomer, cyano (meth)acrylate monomer, epoxy-containing (meth)acrylic monomer, diol (meth)acrylate monomer, silane Series monomer, multifunctional monomer. By adjusting the type, quantity, combination, and copolymerization ratio (weight ratio) of the copolymerization components, a base polymer (finally an adhesive layer) having desired characteristics can be prepared. Relative to 100% by weight of the total monomer component, the ratio of the copolymerization component in the total monomer component is preferably 0% by weight to 20% by weight, preferably 0.1% by weight to 15% by weight, more preferably 0.1% by weight to 10% by weight .

The weight average molecular weight of the base polymer is typically 500,000 to 3 million, preferably 700,000 to 2.7 million, and more preferably 800,000 to 2.5 million. If the weight average molecular weight is too small, heat resistance may be insufficient. If the weight average molecular weight is too large, the handleability may deteriorate. In addition, for coating, viscosity adjustment requires a large amount of dilution solvent, which may increase the cost. In addition, the weight average molecular weight refers to a value measured by GPC (gel permeation chromatography; Gel Permeation Chromatography) and calculated in terms of polystyrene.

C-3-3. The lithium salt adhesive composition contains a lithium salt (lithium-anion salt). As mentioned above, the lithium salt can function as a conductive agent. Constituting the anion of the ionic portion of the can for example such as ^{Cl -, Br -, I -} , AlCl 4 -, Al 2 Cl 7 -, BF 4 -, PF 6 -, ClO 4 -, NO 3 -, CH 3 COO -, CF 3 _{^{COO -, CH 3 SO 3 -}} , CF 3 SO 3 -, (CF 3 SO 2) 3 C -, AsF 6 -, SbF 6 -, NbF 6 -, TaF 6 -, (CN) 2 N -, C 4 _{^{F 9 SO 3 -, C 3}} F 7 COO -, (CF 3 SO 2) (CF 3 CO) N -, - O 3 S (CF 2) 3 SO 3 -, and the following formula (1) - ( 4) _{anion: (1) :( C n F} 2n +1 SO 2) 2 N - (n is an integer of 1 to _{10), (2): CF 2} (C m F 2m SO 2) 2 N - ( m is an integer of 1 to ^{10), (3): - O} 3 S (CF 2) l SO 3 - (l is an integer of 1 to _{10), (4) :( C p} F 2p +1 SO 2) N - (C _q F _{2q +1} SO ₂ ), (p, q are integers from 1 to 10). The anion is preferably a fluorine-containing anion, and a fluorine-containing imide anion is more preferable.

Examples of fluorine-containing amide imide anions include amide imide anions having a perfluoroalkyl group. Specific examples may be cited as described above _{(CF 3 SO 2) (CF} 3 CO) N -, and the general formula (1), (2) and (4) _{anion: (1) :( C n F} 2n + 1 SO _{2) 2} N ^- (n is an integer of 1 to _{10), (2): CF 2} (C m F 2m SO 2) 2 N - (m is an integer of 1 to _{10), (4) :( C p} F ^{_{2p + 1 SO 2) N -}} (C q F 2q + 1 SO 2), (p, q is an integer of 1 to 10). And Yi is _{(CF 3 SO 2) 2 N} -, (C 2 F 5 SO 2) 2 N - like the formula (1) (perfluoroalkyl sulfonic acyl) (PEI), but also to (CF ₃ SO ₂ ) ₂ N ^- preferably bis(trifluoromethanesulfonyl) amide imide. Therefore, the preferred lithium salt that can be used in the embodiments of the present invention is lithium bis(trifluoromethanesulfonyl)amideimide.

The content of the lithium salt in the adhesive composition (resulting in the adhesive layer) is preferably 0.01 to 5 parts by weight, preferably 0.5 to 3 parts by weight, 0.7 parts by weight relative to 100 parts by weight of the base polymer Parts ~ 1.5 parts by weight is better. As long as the content of the lithium salt is within the range, the moisture resistance of a thin polarizer with a high iodine content (the result is a polarizing plate including the polarizer) can be significantly improved.

C-3-4. Organic cationic salt The adhesive composition may also contain organic cationic salts as needed. By using lithium salt in combination with organic cation salt, the surface resistance value can be lowered without causing the lithium salt to overflow.

The organic cation salt is specifically an organic cation-anion salt. The cation constituting the cation portion of the organic cation salt can be exemplified by organic onium in which an onium ion is formed by substitution with an organic group. Examples of the onium in the organic onium include nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium. Nitrogen-containing and sulfur-containing onium are preferred. Examples of the nitrogen-containing onium include ammonium cations, piperidinium cations, pyrrolidinium cations, pyridinium cations, cations having a dihydropyrrole skeleton, cations having a pyrrole skeleton, imidazolium cations, tetrahydropyrimidinium cations, dihydropyrimidine Onium cation, pyrazolium cation, pyrazolinium cation. Ammonium cations, piperidinium cations, and pyrrolidinium cations are preferred, and pyrrolidinium cations are more preferred. The sulfur-containing onium may, for example, be a cation. Examples of the phosphonium-containing phosphonium include phosphonium cations. Examples of the organic group in the organic onium include alkyl groups, alkoxy groups, and alkenyl groups. Specific examples of preferred organic oniums include tetraalkylammonium cations, alkylpiperidinium cations, and alkylpyrrolidinium cations. And ethyl methyl pyrrolidinium cation is better. The anions constituting the anion portion of the organic cation salt are as described for the anions constituting the anion portion of the lithium salt. Therefore, a preferred organic cationic salt that can be used in the embodiment of the present invention is a pyrrolidinium salt, and more preferably ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)amideimide.

The content of the organic cationic salt in the adhesive composition (resulting in the adhesive layer) is preferably 0.1 to 10 parts by weight, preferably 0.3 to 3 parts by weight, 0.5 based on 100 parts by weight of the base polymer Part by weight ~ 1.5 parts by weight is better. If the content of the organic cationic salt is within the above range, the combined effect of the organic cationic salt and the lithium salt is remarkable.

C-3-5. Silane coupling agent The adhesive composition may further contain a silane coupling agent. The durability can be improved by using silane coupling agent. The silane coupling agent may use any functional group that is suitable. Specific examples of the functional group include a vinyl group, an epoxy group, an amine group, a mercapto group, a (meth)acryl oxy group, an acetyl acetyl group, an isocyanate group, a styryl group, and a polysulfide group. Specific examples include vinyl-containing silane coupling agents such as vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, and vinyl tributoxy silane; γ-ring Oxypropyloxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyl diethoxysilane, 2-(3,4- Epoxy cyclohexyl) ethyl trimethoxy silane and other epoxy-containing silane coupling agent; γ-aminopropyl trimethoxy silane, N-β-(aminoethyl)-γ-aminopropyl methyl dimethyl Oxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane and other amine-containing silane coupling agents; γ-mercaptopropylmethyldimethoxysilane and other thiol-containing silane coupling agents; p-styrene trimethoxysilane Silane coupling agent containing styrene group; silane coupling with (meth)acryloyl group containing γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, etc. Agents; 3-isocyanate propyl triethoxysilane and other silane coupling agents containing isocyanate groups; bis (triethoxysilyl propyl) tetrasulfide and other polysulfide groups containing silane coupling agents.

C-3-6. Other The adhesive composition (as a result, the adhesive layer) may further contain arbitrary and appropriate additives. Specific examples of additives include crosslinking agents, silane coupling agents, heavy industry lifters, antioxidants, antistatic agents, crosslinking retarders, emulsifiers, colorants, pigments and other powders, dyes, surfactants, and plasticizers , Tackifier, surface lubricant, leveling agent, softener, anti-aging agent, light stabilizer, ultraviolet absorber, polymerization inhibitor, inorganic filler, organic filler, metal powder, granular, foil, etc. . The quantity, type, amount and combination of additives can be set appropriately according to the purpose.

Any appropriate method can be used for the method of forming the adhesive layer. Representative examples of the forming method include the following method: applying the above-mentioned adhesive composition to a separation member subjected to peeling treatment, etc., and drying and removing the polymerization solvent, etc. to form an adhesive layer, and transferring it to the polarizer Method; or, a method of applying the adhesive composition to the polarizer, drying and removing the polymerization solvent, etc. to form an adhesive layer on the polarizer. In addition, when applying the adhesive, one or more solvents other than the polymerization solvent may be additionally added according to needs.

The details of the adhesive composition are described in Japanese Patent Laid-Open No. 2014-48497, for example. In this specification, the description of this publication is used as a reference. Examples

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. In addition, the measuring method of each characteristic is as follows.

[Example 1] As the thermoplastic resin substrate, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) with a water absorption of 0.75% and a Tg of 75°C is used. Corona treatment was applied on one side of the substrate, and the corona treatment surface was coated with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetonitrile at a ratio of 9:1 at 25°C. Acetoyl modified PVA (degree of polymerization 1200, degree of modification of acetylacetal 4.6%, saponification degree of 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200") and dried. A PVA-based resin layer with a thickness of 11 μm was formed to produce a laminate. Using a tenter stretching machine, the obtained laminate was stretched in air at a temperature of 140° C. in the direction orthogonal to the longitudinal direction of the laminate by 4.5 times (stretching treatment). Next, the laminate was immersed in a dyeing bath (aqueous solution with an iodine concentration of 1.4% by weight and a potassium iodide concentration of 9.8% by weight) at a liquid temperature of 25° C. for 12 seconds to perform dyeing (dyeing treatment). Next, the laminate was immersed in a washing bath (pure water) at a liquid temperature of 25°C for 6 seconds (first washing treatment). Then, it was immersed in a cross-linking bath (aqueous solution with a boron concentration of 1% by weight and a potassium iodide concentration of 1% by weight) at a liquid temperature of 60°C for 16 seconds (cross-linking treatment). Next, the laminate was immersed in a washing bath (aqueous solution of potassium iodide concentration of 1% by weight) at a liquid temperature of 25°C for 3 seconds (second washing treatment). Then, the laminate was dried in an oven at 60°C for 21 seconds (first drying treatment). Next, using a bar coater, the treatment liquid (0.15 parts by weight of citric acid and 0.01 parts by weight of lithium hydroxide was added to 50 parts by weight of water, and the pH was measured after stirring for 10 minutes, and then 50 parts by weight of ethanol was added to prepare the treatment liquid , PH=2.9) applied to the PVA-based resin layer of the laminate, and applied to a film thickness of 7 μm (wet state). Finally, the laminate was dried in an oven at 60°C for 60 seconds to obtain a laminate having a PVA-based resin layer (polarizer) with a thickness of 1.2 μm.

[Example 2] As the treatment liquid, a treatment liquid (pH=4.2) prepared in the same manner as in Example 1 was used except that the amount of lithium hydroxide added was 0.04 parts by weight, except that the treatment liquid was obtained in the same manner as in Example 1. Laminated body of polarizer.

[Example 3] As the treatment liquid, a treatment liquid (pH=5.8) prepared in the same manner as in Example 1 was used except that the amount of lithium hydroxide added was 0.08 parts by weight, except that the treatment liquid was obtained in the same manner as in Example 1. Laminated body of polarizer.

(Comparative example 1) As the treatment liquid, a treatment liquid (pH=2.0) prepared in the same manner as in Example 1 except that lithium hydroxide was not added was used, and a laminate having a polarizer was obtained in the same manner as in Example 1.

(Comparative example 2) As the treatment liquid, a treatment liquid (pH=13.0) prepared in the same manner as in Example 1 was used except that citric acid was not added and the amount of lithium hydroxide added was 0.2 parts by weight, except that Example 1 was used. In the same manner, a laminate with a polarizer is obtained.

(Comparative example 3) As the treatment liquid, a treatment liquid (pH=11.0) prepared in the same manner as in Example 1 was used except that the amount of lithium hydroxide added was 0.2 parts by weight, except that the treatment liquid was obtained in the same manner as in Example 1. Laminated body of polarizer.

The adhesive composition prepared by the following method is uniformly applied on the surface of the polyethylene terephthalate film (separator) treated with the silicone-based stripping agent by a spray coating machine, and An air circulation constant temperature oven at 155°C was dried for 2 minutes, and an adhesive layer with a thickness of 20 μm was formed on the surface of the separator. Then, the adhesive layer was transferred to the surface of the polarizer of the laminate prepared in each of Examples and Comparative Examples to prepare a polarizing plate with an adhesive layer. The obtained polarizing plate with an adhesive layer was used for the following evaluation. The results are listed in Table 1. (Base polymer for preparing adhesive composition) A monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was fed into a 4-neck flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. Then, with respect to 100 parts of the above monomer mixture (solid content), 0.12 parts of 2,2´-azobisisobutyronitrile as a polymerization initiator was fed together with ethyl acetate, and nitrogen gas was introduced while slowly stirring After nitrogen substitution, the temperature of the liquid in the flask was maintained at about 60°C, and polymerization reaction was carried out for 7 hours. Then, ethyl acetate was added to the prepared reaction liquid to adjust the solid content concentration to 30%. In the above manner, a solution of acrylic polymer (A-1) (base polymer) having a weight average molecular weight of 1.4 million was prepared. (Preparation of adhesive composition) Relative to 100 parts of the solid content of the acrylic polymer (A-1) solution, lithium bis(trifluoromethanesulfonyl)amideimide (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) 1.0 is mixed as a conductive agent Parts and ethyl methyl pyrrolidinium bis(trifluoromethanesulfonyl) amide imide (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.7 parts, trimethylolpropane diisocyanate sucralate as a crosslinking agent (Mitsui Chemical Company Manufacture: TAKENATE D110N) 0.095 parts and 0.3 parts of dibenzoyl peroxide, 0.2 parts of organic silane (manufactured by Kken Chemical Co., Ltd.: A100) as a silane coupling agent and silane coupling agent (manufactured by Shin-Etsu Chemical Industry Co., Ltd.: X41-1810) 0.2 parts, heavy industry lifter (manufactured by KANEKA CORPORATION, Silyl SAT10) 0.03 parts, and antioxidant (manufactured by BASF, Irganox 1010) 0.3 parts, to prepare an adhesive composition (solution).

(1) Heating reliability test The polarizing plate with an adhesive layer prepared in each example and comparative example was attached to a 1.3mm thick alkali-free glass, and an ultraviolet visible light spectrophotometer (Japan Spectroscopy Co., Ltd. was used) The product name "V7100" manufactured by the company) measures the single transmittance (Ts ₀ ) of the thin polarizing film. After that, the sample was put into an oven at 85°C for 500 hours. Using the sample taken out, the monomer transmittance (Tsa ₅₀₀ ) was similarly measured with an ultraviolet-visible light spectrophotometer, and ΔTsa was determined by the following formula. ΔTsa (%) = Tsa _500- Ts ₀ and the examples and comparative examples were evaluated according to the following criteria. ○: The absolute value of ΔTsa is within 3.0% △: The absolute value of ΔTsa is within 5.0% ×: The absolute value of ΔTsa is greater than 5.0% (2) The humidification reliability evaluation is attached to each of the examples and comparative examples The polarizer with adhesive layer is attached to the alkali-free glass with a thickness of 1.3mm. Then, the single-piece transmittance (Ts ₀ ) of the thin polarizing film was measured using an ultraviolet visible light spectrophotometer (manufactured by Japan Spectroscopy Co., Ltd., product name "V7100"). After that, the sample was put into a constant temperature and humidity chamber at 60°C and 90% Rh for 500 hours. Using the sample taken out, the single-piece transmittance (Tsb ₅₀₀ ) was similarly measured with an ultraviolet visible light spectrophotometer, and ΔTsb was determined by the following formula. ΔTsb (%) = Tsb _500- Ts ₀ and the examples and comparative examples were evaluated according to the following criteria. ○: The absolute value of ΔTsb is within 3.0% △: The absolute value of ΔTsb is within 3.5% ×: The absolute value of ΔTsb is greater than 3.5% (3) Appearance of polarizer The adhesives prepared in each example and comparative example The layered polarizer is attached to the alkali-free glass with a thickness of 1.3mm. After that, it was put into a constant temperature and humidity tank at 98%RH at 20°C for 120 hours, and the appearance was evaluated. Visually compare the polarizing plates before and after input, and evaluate according to the following criteria. ○: No change in appearance was observed △: A slight change in appearance was observed, but the change in appearance was restored after being left at room temperature for 6 hours ×: The change in appearance (discoloration, unevenness) was obvious. Even after being left at room temperature for 6 hours, the appearance change has not completely recovered

[Table 1]

It is obvious from Table 1 that the polarizer manufactured by the manufacturing method of the embodiment of the present invention still has excellent reliability of heating and humidification even when it is made into a polarizing plate with an adhesive layer containing an adhesive layer containing a conductive agent . Also, the appearance is good even after being placed in a humidified environment.

Industrial availability The manufacturing method of the present invention can easily and inexpensively manufacture a polarizing member whose color change is suppressed under a high-temperature environment. The polarizer manufactured by the manufacturing method of the present invention can be widely used in LCD TVs, LCD monitors, mobile phones, digital cameras, digital cameras, handheld game consoles, car navigation, photocopiers, printers, fax machines, clocks, On a liquid crystal panel such as a microwave oven.

Claims (3)

A method for manufacturing a polarizer, comprising at least stretching and dyeing a polyvinyl alcohol-based resin film; And the manufacturing method includes: coating or spraying a treatment liquid on the polyvinyl alcohol-based resin film after the dyeing, the treatment liquid including citric acid and lithium hydroxide; And the pH of the treatment liquid is in the range of 2.5 to 6.0, and the treatment liquid has a buffering effect in the pH range. The manufacturing method according to claim 1, wherein the polyvinyl alcohol-based resin film is a polyvinyl alcohol-based resin layer formed by applying a coating solution containing a polyvinyl alcohol-based resin to a substrate, and the substrate and The laminated system of the polyvinyl alcohol-based resin layer is used for stretching and dyeing. A method for manufacturing a polarizer with an adhesive layer is a method for manufacturing a polarizer with a polarizer, a protective film and an adhesive layer, the protective film is disposed on one side of the polarizer, and the adhesive The agent layer is arranged on the other side of the polarizer; The manufacturing method includes the following steps: Use the method of claim 1 or 2 to manufacture polarizers; A protective film is attached to one side of the polarizer manufactured by this manufacturing method; and An adhesive layer containing a lithium salt is formed on the other side of the polarizer.