TWI787418B - Polarizing plate with adhesive layer - Google Patents

Abstract

The present invention provides a thin and very excellent moisture resistance polarizing plate with an adhesive layer. The polarizing plate with an adhesive layer of the present invention has: a polarizer, a protective film arranged on one side of the polarizer, and an adhesive layer arranged on the other side of the polarizer. The iodine content of the polarizer is 10% to 25% by weight, the adhesive layer contains a conductive agent, and the conductive agent contains an inorganic cationic salt.

Description

Polarizing plate with adhesive layer

The invention relates to a polarizing plate attached with an adhesive layer.

Background of the invention In a representative image display device, that is, a liquid crystal display device, due to its image formation method, polarizers (in essence, polarizers including polarizers) are arranged on both sides of the liquid crystal cell. Polarizers are typically produced by dyeing a polyvinyl alcohol (PVA)-based resin film with a dichroic substance such as iodine. In recent years, the demand for thinner image display devices has greatly increased. Therefore, further thinning of the polarizer is required. However, the thinner the polarizer is, the more it has the problem of moisture resistance that the optical properties tend to decrease under high temperature and high humidity environment.

prior art literature patent documents Patent Document 1: Japanese Patent Laid-Open No. 2012-247574 Patent Document 2: Japanese Patent Laid-Open No. 2017-102476 Patent Document 3: Japanese Patent Laid-Open No. 2015-094906 Patent Document 4: Japanese Patent Laid-Open No. 2015-094907

Summary of the invention The problem to be solved by the invention The present invention is made to solve the above-mentioned problems, and its main purpose is to provide a thin polarizing plate with an adhesive layer having very excellent moisture resistance.

MEANS TO SOLVE THE PROBLEM A polarizing plate with an adhesive layer of the present invention has a polarizer, a protective film disposed on one side of the polarizer, and an adhesive layer disposed on the other side of the polarizer. The iodine content of the polarizer is 10% to 25% by weight, the adhesive layer contains a conductive agent, and the conductive agent contains an inorganic cationic salt. In one embodiment, the above-mentioned inorganic cation salt is a lithium salt. In one embodiment, the anion constituting the anion part of the above-mentioned inorganic cationic salt is selected from the anions represented by the following general formulas (1) to (4): (1): (C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10), (2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10), (3): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (l is an integer from 1 to 10), (4): (C _p F _2p+1 SO ₂ )N ^- (C _q F _2q+1 SO ₂ ), (p, q are 1 to 10 integer). In one embodiment, the content of the inorganic cation salt is 0.01 parts by weight to 5 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer. In one embodiment, the conductive agent further includes an organic cation salt. In one embodiment, the content of the organic cation salt is 0.1 parts by weight to 10 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer. In one embodiment, the polarizer has a thickness of 3 μm or less.

Invention effect According to the present invention, by introducing a conductive agent containing an inorganic cationic salt (preferably lithium salt) into the adhesive layer, excellent moisture resistance can be achieved even if a thin polarizer with a very high iodine content is used.

form for carrying out the invention Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

A. Outline of polarizing plate with adhesive layer Fig. 1 is a schematic cross-sectional view of a polarizing plate with an adhesive layer according to an embodiment of the present invention. The polarizing plate 100 with an adhesive layer in the illustrated example has: a polarizer 10 , a protective film 20 disposed on one side of the polarizer 10 , and an adhesive layer 30 disposed on the other side of the polarizer. The adhesive layer 30 is typically the outermost layer on the image display device side. In an embodiment of the present invention, the iodine content of the polarizer is 10% by weight to 25% by weight. Also, the adhesive layer includes a conductive agent, and the conductive agent includes an inorganic cation salt.

In actual use, on the adhesive layer 30, a separator (not shown) is temporarily adhered in a detachable state, which can protect the adhesive layer until actual use, and can be formed into a roll. Another protective film (not shown) can also be disposed between the polarizer 10 and the adhesive layer 30 according to requirements. A retardation film (not shown) may also be disposed between the polarizer 10 and the adhesive layer 30 or outside the protective film 20 according to requirements. The optical characteristics of the retardation film (such as refractive index ellipsoid, in-plane retardation, thickness direction retardation, Nz coefficient, wavelength dispersion characteristics), the number of sheets arranged, the combination, the angle between the slow axis and the absorption axis of the polarizer, etc., can be Make appropriate settings according to the purpose.

The polarizer, the protective film, and the adhesive layer constituting the polarizing plate with the adhesive layer will be specifically described below.

B. Polarizer B-1. Composition and characteristics of polarizer The top part of the polarizer is made of polyvinyl alcohol (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. Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually more than 85 mol% 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 a PVA-based resin having such a degree of saponification, a polarizer excellent in durability can be obtained. When the degree of saponification is too high, gelation may occur.

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 1000-10000, preferably 1200-4500, more preferably 1500-4300. In addition, the average degree of polymerization can be obtained according to JIS K 6726-1994.

In one embodiment, the PVA-based resin film may also be a PVA-based resin layer formed on a substrate. The laminate of the base material and the PVA-based resin layer can be produced by, for example, the following methods: a method of applying a coating solution containing the above-mentioned PVA-based resin to the base material; laminating a PVA-based resin film on the base material; method etc.

The iodine content of the polarizer can be properly set to have sufficient polarizing performance and the best monomer transmittance. As mentioned above, the iodine content is 10% by weight to 25% by weight, and preferably 15% by weight to 25% by weight. According to an embodiment of the present invention, by employing a specific adhesive layer described later in a polarizing plate including the polarizer having an extremely high iodine content, it is possible to realize very excellent moisture resistance which was difficult to achieve in the past. More specifically, in a polarizing plate including a polarizer having an extremely high iodine content, changes in single transmittance, degree of polarization, and hue under high-temperature and high-humidity environments can be significantly suppressed. "Iodine content" in this specification means the amount of all iodine contained in a polarizer (PVA-type resin film). More specifically, iodine exists in polarizers in the form of iodide ions (I ^- ), iodine molecules (I ₂ ), polyiodide ions (I ₃ ^- , I ₅ ^- ), and the iodine content in this specification means Contains the amount of iodine in all such forms. The iodine content can be calculated using a calibration curve method such as fluorescent X-ray analysis. In addition, polyiodide ions exist in the state of forming a PVA-iodine complex in the polarizer. By forming the complex, absorption dichroism can be exhibited in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ions (PVA·I ₃ ^- ) has an absorption peak near 470nm; the complex of PVA and pentaiodide ions (PVA·I ₅ ^- ) has an absorption peak near 600nm peak. As a result, polyiodide ions can absorb light in a wide range of visible light depending on their morphology. On the other hand, iodide ion (I ^- ) has an absorption peak around 230 nm, which is not substantially related to the absorption of visible light. Therefore, the presence of polyiodide ions in the complex state with PVA is mainly related to the absorption performance of the polarizer.

The upper limit of the thickness of the polarizer is 5 μm in one embodiment, 3 μm in another embodiment, and 2 μm in another embodiment. The lower limit of the thickness is 0.5 μm in one embodiment, 0.6 μm in another embodiment, 0.8 μm in another embodiment, 1 μm in another embodiment, and 0.6 μm in another embodiment. 2 μm. According to the embodiment of the present invention, even with a thin polarizer, desired single transmittance and polarization can be achieved.

The single transmittance (Ts) of the polarizer is preferably 30.0%~43.0%, more preferably 35.0%~41.0%. The degree of polarization of the polarizer is preferably above 99.9%, more preferably above 99.95%, and more preferably above 99.98%. By setting the single transmittance low and the degree of polarization high, the contrast can be improved, and the black display can be displayed even blacker, so an image display device with excellent image quality can be realized. In addition, the single transmittance is a value measured by a spectrophotometer with an integrating sphere. The single transmittance is the Y value obtained by measuring the 2-degree field of view (C light source) of JIS Z8701 and correcting the optical performance. For example, an ultraviolet-visible spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, Product name: V7100) was measured.

In the embodiment of the present invention, even if the iodine content of the above-mentioned polarizer is extremely high, the change of optical characteristics under high temperature and high humidity environment as described in the examples later is significantly suppressed. Moreover, the hue change under high temperature and high humidity environment is also suppressed. The excellent effect can be realized by using the adhesive layer introduced with the conductive agent containing the above-mentioned inorganic cation salt in combination with the above-mentioned polarizer. In more detail, we presume that the iodine complexes in the polarizer are stabilized due to the bonding of inorganic cations (such as lithium ions) from the conductive agent in the adhesive layer to the iodine complexes, resulting in inhibition of iodine (especially Such as I ₃ ^- , I ₅ ^- polyiodide ions) are reduced under high temperature and high humidity environment, so as to achieve the above excellent effect. It can solve the newly discovered problem caused by actually making very thin (for example, less than 3 μm in thickness) polarizers that were difficult to manufacture in the past, and it is an unexpected and excellent effect.

B-2. Manufacturing method of polarizer B-2-1. Outline of manufacturing method The polarizer can be manufactured by a manufacturing method including at least stretching and dyeing a PVA-based resin film. Typically, the manufacturing method includes a step of preparing a PVA-based resin film, a stretching step, a swelling step, a dyeing step, a crosslinking step, a washing step, and a drying step. Each step of supplying the PVA-based resin film can be performed in any appropriate order and timing. Therefore, each step can be carried out in the above order, or can be carried out in a different order. One step can also be performed multiple times according to the need. In addition, steps other than the above (for example, an insolubilization step) may be performed at any appropriate timing. In addition, in the case of a PVA-based resin layer in which a PVA-based resin film is formed on a base material, a laminate of the base material and the PVA-based resin layer can be used in the above step.

Each step is described below, but as mentioned above, each step can be performed in any and appropriate order, and is not limited by the order of description.

B-2-2. Extended steps In the stretching step, the PVA-based resin film representing the top is uniaxially stretched to 3 to 7 times. The stretching direction may be the long side direction (MD direction) of the film, or may be the width direction (TD direction) of the film. The stretching method may be dry stretching, wet stretching, or a combination thereof. Also, the PVA-based resin film may be stretched during the crosslinking step, swelling step, dyeing step, and the like. In addition, the extending direction may correspond to the absorption axis direction of the obtained polarizer.

B-2-3. Swelling step The swelling step is usually performed 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 contain arbitrary and appropriate other components other than water. Examples of other components include solvents such as alcohols, additives such as surfactants, iodides, and the like. 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, titanium iodide and the like. Potassium iodide is preferably used. The temperature of the swelling bath is, for example, 20°C~45°C. In addition, the immersion time is, for example, 10 seconds to 300 seconds.

B-2-4. Dyeing procedure The dyeing step is a step of dyeing the PVA-based resin film with a dichroic substance. This is preferably done by allowing it to adsorb a dichroic substance. The adsorption method can be, for example, a method of immersing the PVA resin film in a dye solution containing a dichroic substance, a method of applying the dye solution to the PVA resin film, and spraying the dye solution onto the PVA system. method of resin film, etc. Ideally, it is a method of immersing a PVA-based resin film in a dyeing solution. Because it can adsorb dichroic substances well.

Examples of the aforementioned dichroic substances include iodine and dichroic dyes. And preferably iodine. When iodine is used as the dichroic substance, iodine aqueous solution should be used as the dyeing solution. The iodine content of the iodine aqueous solution is preferably 0.04 to 5.0 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is advisable to mix iodide in the iodine aqueous solution. Potassium iodide is preferably used as the iodide. The iodide content 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 any and appropriate value, for example, 20°C~50°C. When immersing the PVA-based resin film in the dyeing solution, the immersion time is, for example, 5 seconds to 5 minutes.

B-2-5. Cross-linking step In the crosslinking step, boron compounds are generally used as crosslinking agents. Examples of boron compounds include boric acid and borax. And preferably boric acid. In the crosslinking step, the boron compound is usually used in the form of an aqueous solution.

When a boric acid aqueous solution is used, 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. It is also possible to make the boric acid aqueous solution contain iodides such as potassium iodide; zinc compounds such as zinc sulfate and zinc chloride.

The crosslinking step can be performed by any and appropriate method. For example, a method of immersing a PVA-based resin film in an aqueous solution of a boron-containing compound, a method of applying an aqueous solution of a boron-containing compound to a PVA-based resin film, or spraying an aqueous solution of a boron-containing compound onto a PVA-based resin film Methods. And it is better to immerse in the aqueous solution of boron-containing compound.

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

B-2-6. Washing step The washing step represents that the upper line is performed after the crosslinking step. The cleaning step represents the above method and is performed by immersing the PVA-based resin film in a cleaning solution. A representative example of the cleaning solution is pure water. Potassium iodide can also be added to pure water.

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

B-2-7. 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 should use heat drying. When heat drying is performed, the heating temperature is, for example, 30°C to 100°C. Also, the drying time is, for example, 20 seconds to 10 minutes.

C. Protective film Any suitable resin film is used for the protective film (and, if present, another protective film). Examples of materials for forming the resin film include (meth)acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins such as norbornene resins, and olefin resins such as polypropylene. , polyester resins such as polyethylene terephthalate resins, polyamide resins, polycarbonate resins and their copolymer resins, etc. In addition, "(meth)acrylic resin" means an acrylic resin and/or a methacrylic resin.

In one embodiment, a (meth)acrylic resin having a glutarimide structure is used as the (meth)acrylic resin. (Meth)acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) are described, for example, in the following documents: JP-A-2006-309033, JP-A-2006-317560 Gazette, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492, JP-A-2006-337493, JP-A 2006-337569, JP-A 2007-009182, JP-A 2009-161744, and JP-A 2010-284840. These descriptions are incorporated by reference in this specification.

When a polarizer is manufactured using a laminate of a base material and a PVA-based resin layer, it can be used as a protective film without peeling off the base material. Moreover, after peeling off a base material, you may bond a polarizer and a protective film together.

Any suitable optically functional film may also be used as the protective film (and, if present, another protective film) according to the purpose. Examples of optical functional films include retardation films and reflective polarizers (brightness enhancement films).

D. Adhesive layer The polarizing plate with an adhesive layer according to the embodiment of the present invention is typically as above, a protective film is arranged on one side of the polarizer, and an adhesive layer is arranged on the other side of the polarizer. That is, in this embodiment, the protective film is not arranged on the other side of the polarizer, and the adhesive layer is directly arranged on the polarizer.

D-1. Adhesive composition The adhesive composition constituting the adhesive layer includes a base polymer and a conductive agent.

D-1-1. Base polymer Typical examples of base polymers include (meth)acrylic polymers ((meth)acrylic resins). A (meth)acrylic polymer typically contains a monomer unit derived from an alkyl (meth)acrylate as a main component. Alkyl (meth)acrylate is an alkyl ester of (meth)acrylic acid. The alkyl group forming the alkyl ester may be, for example, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl , Decyl, Isodecyl, Dodecyl, Isomyristyl, Lauryl, Tridecyl, Pentadecyl, Hexadecyl, Heptadecyl, Octadecyl. These may 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 suitable copolymerization component according to purpose. Copolymerization components can be, for example, monomers containing hydroxyl groups, monomers containing carboxyl groups, monomers containing acid anhydride groups, monomers containing sulfonic acid groups, monomers containing phosphoric acid groups, (N-substituted) amide monomers, Alkylaminoalkyl (meth)acrylate monomer, alkoxyalkyl (meth)acrylate monomer, succinimide monomer, maleimide monomer, Iconimide Amine-based monomers, vinyl monomers, cyano(meth)acrylate monomers, epoxy-containing (meth)acrylic monomers, diol-based (meth)acrylate monomers, silane-based monomers Monomer, polyfunctional monomer. By adjusting the type, amount, combination, and copolymerization ratio (weight ratio) of the copolymerization components, a base polymer (ultimately an adhesive layer) having desired characteristics can be obtained. Relative to 100% by weight of the total monomer components, the ratio of the copolymerization component in the total monomer components is preferably 0% by weight to 20% by weight, more 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 representatively 500,000-3 million, preferably 700,000-2.7 million, more preferably 800,000-2.5 million. When the weight average molecular weight is too small, heat resistance may be insufficient. If the weight-average molecular weight is too large, workability may deteriorate, or a large amount of diluent solvent may be required for viscosity adjustment for coating, which may increase costs. In addition, weight average molecular weight means the value calculated by polystyrene conversion measured by GPC (gel permeation chromatography; Gel Permeation Chromatography).

D-1-2. Conductive agent The conductive agent includes inorganic cation salts as described above. Inorganic cation salts are in particular inorganic cation-anion salts. Representative examples of cations constituting the cation portion of the inorganic cation salt include alkali metal ions. Specific examples include lithium ions, sodium ions, and potassium ions. Lithium ions are preferred. Therefore, preferred inorganic cation salts are lithium salts.

The anions constituting the anion part of the inorganic cationic salt are, for example, 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 general formula (1 )~(4): (1): (C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10), (2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10), (3): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (l is an integer from 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). Fluorine-containing anions are preferred, and fluorine-containing imide anions are more preferred.

The fluorine-containing imide anion includes, for example, an imide anion having a perfluoroalkyl group. Specific examples include (CF ₃ SO ₂ )(CF ₃ CO)N ^- , and anions represented by general formulas (1), (2) and (4): (1): (C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10), (2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 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). And preferably (CF ₃ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- and other (perfluoroalkylsulfonyl) imides represented by general formula (1), especially (CF ₃ Bis(trifluoromethanesulfonyl)imide represented by SO ₂ ) ₂ N ^- is suitable. Therefore, the preferred inorganic cation salt that can be used in the embodiment of the present invention is lithium bis(trifluoromethanesulfonyl)imide.

With respect to 100 parts by weight of the base polymer, the content of the inorganic cationic 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, preferably 0.7 Parts by weight~1.5 parts by weight are better. As long as the content of the inorganic cation salt is within the range, the moisture resistance of a thin polarizer with a high iodine content (resulting in a polarizer containing the polarizer) can be significantly improved.

The conductive agent may further include organic cationic salts according to requirements. By using the inorganic cation salt in combination with the organic cation salt, the surface resistance value can be further reduced without overflowing the inorganic cation salt.

Organic cation salts are in particular organic cation-anion salts. Representative examples of the cation constituting the cation portion of the organic cation salt include an organic onium substituted with an organic group to form an onium ion. The onium in the organic onium includes, for example, nitrogen-containing onium, sulfur-containing onium, and phosphonium-containing onium. And nitrogen-containing onium 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 can be exemplified by a caldium cation. Phosphonium-containing oniums include, for example, phosphonium cations. The organic group in the organic onium includes, for example, an alkyl group, an alkoxy group, and an alkenyl group. Specific examples of preferable organic onium include tetraalkylammonium cations, alkylpiperidinium cations, and alkylpyrrolidinium cations. And the ethylmethylpyrrolidinium cation is more preferable. The anion constituting the anion portion of the organic cation salt is as described for the anion constituting the anion portion of the inorganic cation salt. Therefore, the preferred organic cation salt that can be used in the embodiment of the present invention is pyrrolidinium salt, and more preferably ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

With respect to 100 parts by weight of the base polymer, 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, preferably 0.5 parts by weight. Parts by weight~1.5 parts by weight are better. If the content of the organic cation salt is within the above-mentioned range, the combination effect of the above-mentioned organic cation salt and inorganic cation salt will be remarkable.

D-1-3. Silane coupling agent The adhesive composition may further contain a silane coupling agent. Durability can be improved by using silane coupling agents. As the silane coupling agent, those having arbitrary and appropriate functional groups can be used. Specific examples of the functional group include a vinyl group, an epoxy group, an amino group, a mercapto group, a (meth)acryloxy group, an acetoacetyl group, an isocyanate group, a styryl group, and a polysulfide group. Specifically, vinyl-containing silane coupling agents such as vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, etc.; Oxypropoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4- Epoxy cyclohexyl) ethyl trimethoxysilane and other epoxy-containing silane coupling agents; γ-aminopropyl trimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyl dimethyl Oxysilane, N-(2-aminoethyl) 3-aminopropylmethyldimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethylbutylene) propylamine, Amino-containing silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane; mercapto-containing silane coupling agents such as γ-mercaptopropylmethyldimethoxysilane; p-styrene trimethoxysilane Silane coupling agents containing styrene groups; silane coupling agents containing (meth)acrylic groups such as γ-acryloxypropyl trimethoxysilane and γ-methacryloxypropyl triethoxysilane ; 3-isocyanate propyltriethoxysilane and other silane coupling agents containing isocyanate groups; bis(triethoxysilylpropyl) tetrasulfide and other silane coupling agents containing polysulfide groups, etc.

D-1-4. Others The adhesive composition (resulting in the adhesive layer) may further contain arbitrary and appropriate additives. Specific examples of additives include cross-linking agents, silane coupling agents, heavy-duty enhancers, antioxidants, antistatic agents, cross-linking retarders, emulsifiers, colorants, powders such as pigments, 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 appropriately set according to the purpose.

Any appropriate method can be used for the method of forming the adhesive layer. A representative example of the formation method includes the method of applying the above-mentioned adhesive composition to a separator or the like that has undergone peeling treatment, drying and removing the polymerization solvent, etc. to form an adhesive layer, and then transferring it to a polarizer. method; or, a method of applying the above-mentioned adhesive composition to a polarizer, drying and removing the polymerization solvent, etc., to form an adhesive layer on the polarizer. In addition, when coating the adhesive, one or more solvents other than the polymerization solvent can be added as needed.

Details of the adhesive composition are described in, for example, JP-A-2014-48497. In this specification, the description of this publication is cited as a reference.

D-2. Composition and characteristics of the adhesive layer The thickness of the adhesive layer is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm. As long as the thickness of the adhesive layer is within the above range, the effect of improving the moisture resistance brought by the inorganic cationic salt is remarkable.

The surface resistance value (initial) of the adhesive layer is preferably 5.0×10 ¹¹ Ω·□ or less, preferably 1.0×10 ¹¹ Ω·□ or less, more preferably 5.0×10 ¹⁰ Ω·□ or less. The lower limit of the surface resistance value of the adhesive layer may be, for example, 5.0×10 ⁹ Ω·□. As long as the surface resistance value of the adhesive layer is within the above range, there is an advantage that static unevenness can be easily suppressed. Example

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. The measuring method of each characteristic is as follows. In addition, unless otherwise noted, "parts" and "%" in the examples are based on weight.

(1) Iodine content For the polarizers of the polarizing plates with the adhesive layer obtained in Examples and Comparative Examples, a fluorescent X-ray analyzer (manufactured by Rigaku, trade name "ZSX-PRIMUS II") was used to measure the diameter: ψ20mm) measured fluorescent X-ray intensity (kcps). On the other hand, the thickness (μm) of the polarizer was measured using a spectroscopic film thickness meter (manufactured by Otsuka Electronics Co., Ltd., trade name "MCPD-3000"). From the obtained fluorescent X-ray intensity and thickness, the iodine content (% by weight) was determined by the following formula. (Iodine concentration) = 20.5 x (fluorescent X-ray intensity) / (film thickness) In addition, the coefficient when calculating the iodine content will vary depending on the measuring device, and the coefficient can be obtained using an appropriate calibration curve. (2) Transmittance variation ΔTs of a single element The polarizing plates obtained in Examples and Comparative Examples with an adhesive layer were attached to an alkali-free glass with a thickness of 1.3 mm through the adhesive layer to prepare test samples. Then, this test sample was humidified for 500 hours under conditions of 65° C. and 90% RH (humidification test). The single transmittance Ts ₀ before the test and the single transmittance Ts ₅₀₀ after the humidification test were respectively measured with an ultraviolet-visible spectrophotometer (manufactured by JASCO Co., Ltd., product name: V7100) with an integrating sphere. Then, the change amount ΔTs of the single element transmittance was obtained from the single element transmittance Ts ₀ before humidification and the single element transmittance Ts ₅₀₀ after the humidification test using the following formula. ΔTs(%)=Ts ₅₀₀ -Ts ₀ (3) Amount of change in polarization degree ΔP For the polarizing plates with adhesive layer obtained in the examples and comparative examples, use an ultraviolet-visible spectrophotometer with an integrating sphere (JASCO Co., Ltd. Manufactured by the company, product name: V7100) to measure the single transmittance Ts, the parallel transmittance Tp, and the orthogonal transmittance Tc. These Ts, Tp and Tc are the Y values obtained by measuring with the 2-degree field of view (C light source) of JIS Z8701 and correcting the optical performance. The degree of polarization P was obtained from the obtained Tp and Tc by the following formula. Degree of polarization P(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100 Then, the amount of change in degree of polarization ΔP is obtained by the following formula. ΔP(%)=P ₅₀₀ -P ₀ Here, P ₀ is the degree of polarization before humidification, and P ₅₀₀ is the degree of polarization after being placed in an environment of 65°C and 90%RH for 500 hours. (4) Hue change Δab For the polarizing plates with the adhesive layer obtained in Examples and Comparative Examples, a value and b value were measured with an ultraviolet-visible spectrophotometer with integrating sphere (JASCO V-7100). And take it as a ₀ value and b ₀ value. And calculate the a ₅₀₀ value and b ₅₀₀ value after humidifying for 500 hours under the conditions of 65°C and 90%RH. From these equivalent values, the amount of color change Δab was obtained by the following formula. Δab={(a ₅₀₀ -a ₀ ) ² +(b ₅₀₀ -b ₀ ) ² } ^1/2 (5) Surface resistance value The separation film of the polarizing plate with the adhesive layer obtained in the examples and comparative examples was peeled off Thereafter, the surface resistance value (Ω·□) (initial) of the adhesive surface was measured using MCP-HT450 manufactured by Mitsubishi Chemical Analytech. After humidifying the polarizing plate with the adhesive layer at 65°C and 90%RH for 48 hours, measure the surface resistance value of the adhesive surface in the same way (after the humidity test). In addition, the humidity test was carried out by putting the polarizing plate with the adhesive layer into a constant temperature and humidity machine at 65° C. and 90% RH.

[Example 1] (The base polymer for preparing the adhesive composition) A monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was fed into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. Then, 0.1 part of 2,2´-azobisisobutyronitrile as a polymerization initiator was fed together with ethyl acetate to 100 parts of the above-mentioned monomer mixture (solid content), and nitrogen gas was introduced while slowly stirring. After nitrogen substitution, the liquid temperature in the flask was maintained at about 60° C., and polymerization reaction was performed for 7 hours. Then, ethyl acetate was added to the obtained reaction liquid to adjust the solid content concentration to 30%. In the above-mentioned manner, a solution of an acrylic polymer (A-1) (base polymer) having a weight average molecular weight of 1.4 million was prepared.

(preparation of adhesive composition) With respect to 100 parts of the solid content of the above-mentioned acrylic polymer (A-1) solution, lithium bis(trifluoromethanesulfonyl)imide (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) 1.0 and 0.7 parts of ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Tokyo Chemical Industry Co., Ltd.), trimethylolpropane diisocyanate (Mitsui Chemicals Co., Ltd.) as a crosslinking agent Preparation: 0.095 part of TAKENATE D110N), 0.3 part of dibenzoyl peroxide, 0.2 part of organosilane as silane coupling agent (manufactured by Soken Chemical Co., Ltd.: A100), and silane coupling agent containing thiol group (manufactured by Shin-Etsu Chemical Industry Co., Ltd.: X41-1810) 0.2 part, heavy industry enhancer (Kaneka Corporation, Silyl SAT10) 0.03 part, and antioxidant (BASF Corporation, Irganox 1010) 0.3 part, and an adhesive composition (solution) was prepared.

(Making polarizers) The thermoplastic resin substrate is an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg of 75°C. Apply corona treatment to one side of the substrate, and coat polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mole%) and acetylene at a ratio of 9:1 on the corona treatment surface at 25°C Acetyl modified PVA (polymerization degree 1200, acetyl acetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200") and then dried , and a PVA-based resin layer with a thickness of 11 μm was formed to produce a laminate. The obtained laminate was stretched 4.5 times in the air in a direction perpendicular to the long side direction of the laminate at 140° C. using a tenter stretcher (stretching treatment). Next, the laminate was dipped in a dyeing bath (an aqueous solution having 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 cleaning bath (pure water) at a liquid temperature of 25° C. for 6 seconds (first cleaning process). Next, it was immersed in a crosslinking bath (an 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 (crosslinking treatment). Next, the laminate was immersed in a cleaning bath (aqueous solution having a potassium iodide concentration of 1% by weight) at a liquid temperature of 25° C. for 3 seconds (second cleaning treatment). Then, the laminate was dried in an oven at 60° C. for 21 seconds (drying treatment). As described above, a laminate (polarizing plate) having a PVA-based resin layer (polarizer) having a thickness of 1.2 μm was produced. The iodine content of the polarizer of the obtained polarizing plate was 20.9% by weight, and the single transmittance was 40.3%.

(Making polarizing plate with adhesive layer) Apply the above-mentioned adhesive composition evenly on the surface of the polyethylene terephthalate film (separator) treated with a polysiloxane-based release agent with a spray coating machine, and circulate it with air at 155°C Dry in a constant temperature oven for 2 minutes to form an adhesive layer with a thickness of 20 μm on the surface of the separator. Then, the adhesive layer is transferred onto the surface of the polarizer of the above-mentioned polarizer to obtain a polarizer with an adhesive layer.

The obtained polarizing plate with the adhesive layer attached was used for the evaluation of (2)-(5) above. List the results in Table 1.

[Example 2] An adhesive composition was prepared in the same manner as in Example 1 except that only 0.2 parts of A100 was used as the silane coupling agent. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the adhesive composition was used. The obtained polarizing plate with the adhesive layer attached was subjected to the same evaluation as in Example 1. List the results in Table 1.

[Example 3] An adhesive composition was prepared in the same manner as in Example 1, except that only 1.0 part of lithium bis(trifluoromethanesulfonyl)imide was used as the conductive agent. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the adhesive composition was used. The obtained polarizing plate with the adhesive layer attached was subjected to the same evaluation as in Example 1. List the results in Table 1.

[Example 4] An adhesive composition was prepared in the same manner as in Example 1 except that only 1.0 part of lithium bis(trifluoromethanesulfonyl)imide was used as the conductive agent and only 0.2 part of A100 was used as the silane coupling agent. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the adhesive composition was used. The obtained polarizing plate with the adhesive layer attached was subjected to the same evaluation as in Example 1. List the results in Table 1.

[Comparative example 1] An adhesive composition was prepared in the same manner as in Example 1, except that only 0.7 part of ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide was used as the conductive agent. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the adhesive composition was used. The obtained polarizing plate with the adhesive layer attached was subjected to the same evaluation as in Example 1. List the results in Table 1.

[Comparative example 2] Except using only 0.7 parts of ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide as the conductive agent and only 0.2 parts of A100 as the silane coupling agent, an adhesive was prepared in the same manner as in Example 1. agent composition. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the adhesive composition was used. The obtained polarizing plate with the adhesive layer attached was subjected to the same evaluation as in Example 1. List the results in Table 1.

[Comparative example 3] An adhesive composition was prepared in the same manner as in Example 1 except that no conductive agent was used. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the adhesive composition was used. The obtained polarizing plate with the adhesive layer attached was subjected to the same evaluation as in Example 1. List the results in Table 1.

[Table 1]

It can be clearly seen from Table 1 that the polarizing plate with the adhesive layer of the embodiment of the present invention has excellent monomer transmittance change, polarization degree change and hue change after the humidity test, and has very excellent moisture resistance .

Industrial availability The polarizer of the present invention can be widely used on LCD panels of LCD TVs, LCD monitors, mobile phones, digital cameras, digital video cameras, handheld game consoles, car navigation, photocopiers, printers, fax machines, clocks, microwave ovens, etc. .

10‧‧‧polarizer 20‧‧‧Protective film 30‧‧‧adhesive layer 100‧‧‧Polarizing plate with adhesive layer

FIG. 1 is a schematic cross-sectional view illustrating a polarizing plate with an adhesive layer according to an embodiment of the present invention.

10‧‧‧polarizer

20‧‧‧Protective film

30‧‧‧adhesive layer

100‧‧‧Polarizing plate with adhesive layer

Claims (7)

A polarizing plate with an adhesive layer, comprising: a polarizer, a protective film arranged on one side of the polarizer, and an adhesive layer arranged on the other side of the polarizer; the iodine content of the polarizer is 15% by weight ~25% by weight; the adhesive layer contains a conductive agent; and the conductive agent contains an inorganic cationic salt. The polarizing plate with an adhesive layer as claimed in claim 1, wherein the inorganic cation salt is a lithium salt. A polarizing plate with an adhesive layer as claimed in claim 1 or 2, wherein the anion constituting the anion part of the aforementioned inorganic cation salt is selected from the anions shown in the following general formulas (1) to (4): (1): ( C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10), (2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10), ( 3): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (l is an integer from 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 polarizing plate with an adhesive layer according to claim 1 or 2, wherein the content of the inorganic cation salt is 0.01 to 5 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer. The polarizing plate with an adhesive layer according to claim 1 or 2, wherein the conductive agent further includes an organic cationic salt. A polarizing plate with an adhesive layer as claimed in claim 5, wherein relative to 100 parts by weight of the base polymer of the aforementioned adhesive layer, the aforementioned organic The content of the cationic salt is 0.1 parts by weight to 10 parts by weight. The polarizing plate with an adhesive layer according to claim 1 or 2, wherein the thickness of the polarizer is 3 μm or less.

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