JP5243343B2 - Polarizer outer surface protective film, polarizing plate, and liquid crystal display element - Google Patents

Description

  The present invention relates to a polarizer outer surface protective film, a polarizing plate including the polarizer outer surface protective film, and a liquid crystal display device including the polarizing plate.

  In recent years, liquid crystal display devices (LCDs) are widely used in place of CRTs because of their thinness and light weight and low power consumption. The field of use of liquid crystal display elements is expanding from small products such as conventional calculators and watches to large products such as automotive instruments, PC monitors, and televisions.

  As shown in FIG. 5, a general liquid crystal display element 21 arranged in a liquid crystal display device has a liquid crystal cell 27 in which a liquid crystal layer 27 is sandwiched between transparent medium layers 26 (for example, glass) on both sides, and has a polarization ability. A polarizing plate 22 having a polarizing plate protective film 23 bonded to both surfaces of the polarizer 24, and a structure in which the liquid crystal cell 25 is sandwiched from above and below by the polarizing plate 22 through an adhesive layer 28. ing. Thus, the polarizer 24 is protected by the polarizer protective film 23 from the viewpoint of improving the strength and facilitating handling.

  In general, polyvinyl alcohol (PVA), which is a hydrophilic resin, is used as a material for the polarizer, and the PVA film is uniaxially stretched and then dyed with iodine or a dichroic dye, or dyed. Is then stretched and then crosslinked with a boron compound to form a polarizer. The polarizer protective film is required to have properties such as optical transparency and low birefringence, a smooth surface, and excellent adhesion to a polarizer made of PVA. Therefore, triacetyl cellulose (TAC) is generally used. Triacetyl cellulose is saponified with an alkali (the ester group is converted to a hydroxyl group that is a hydrophilic group) and then adhered to a polarizer composed of polyvinyl alcohol that is a hydrophilic resin. As a technique for improving various required characteristics of triacetyl cellulose as described above, for example, formation of a predetermined resin layer on a triacetyl cellulose layer (Japanese Patent Laid-Open Nos. 9-113728 and 9-281333). Proposed. However, since triacetyl cellulose is expensive, development of an inexpensive alternative material having equivalent properties is required.

  The polarizer protective film disposed on the inner surface side (the side closer to the liquid crystal cell) of the liquid crystal display element is particularly required to have a small birefringence (non-orientation). There is no suitable substitute for acetylcellulose. On the other hand, as a required characteristic of the polarizer protective film disposed on the outer surface side of the liquid crystal display element (the side away from the liquid crystal cell, that is, the position of the uppermost layer and the lowermost layer 23 in FIG. 5), the presence or absence of birefringence However, since transparency becomes a more important position, development of alternative materials other than triacetylcellulose is expected.

  As general-purpose resin materials having high transparency that can be substituted for triacetyl cellulose, acrylic resins, polycarbonate resins, polypropylene resins, cycloolefin resins, polyethylene terephthalate resins, and the like are conceivable. However, since these resins do not have a hydrophilic group, there is an inconvenience that adhesiveness with polyvinyl alcohol, which is a hydrophilic resin constituting a polarizer, is inferior. Cannot be used as Therefore, in addition to having high transparency, development of a novel polarizer outer surface protective film for facilitating adhesion with a polarizer made of polyvinyl alcohol and disposed on the outer surface side of a liquid crystal display element is desired. It is rare.

Japanese Laid-Open Patent Publication No. 9-11728 JP-A-9-281333

  The present invention has been made in view of these disadvantages, and is a novel material disposed on the outer surface side of a liquid crystal display element that has high transparency and is subjected to an easy adhesion treatment for a polarizer made of polyvinyl alcohol. The object is to provide a polarizer outer surface protective film, a polarizing plate provided with such a polarizer outer surface protective film, and a liquid crystal display element.

The invention made to solve the above problems is
A polarizer outer surface protective film disposed on the outer surface side of the liquid crystal display element,
A transparent synthetic resin base material layer;
A hydrophilic resin layer laminated on the inner surface side of the base material layer ,
This hydrophilic resin layer is composed of a composition containing an acrylic-modified polyester-based resin and a urethane-based resin .

  According to the polarizer outer surface protective film, high transparency required as a film for protecting the polarizer located on the outer surface side of the liquid crystal display element is obtained by using a transparent synthetic resin as a constituent material of the base material layer. It is done. Moreover, the said polarizer outer surface protective film is polyvinyl which is also a hydrophilic resin by laminating | stacking a hydrophilic resin layer on the inner surface side of a base material layer so that adhesion | attachment with the polarizer which consists of polyvinyl alcohol may be made easy. Adhesiveness with a polarizer made of alcohol is dramatically improved. That is, since the hydrophilic resin layer formed by such an easy adhesion treatment has high chemical affinity with polyvinyl alcohol, which is also a hydrophilic resin, the adhesion with the polarizer is effectively improved. Moreover, since this hydrophilic resin layer has hydrophilicity in itself, it can be used in an adhesion process with a polarizer without performing a saponification treatment like that performed on triacetyl cellulose constituting a conventional polarizer protective film. It is possible to provide. In the present specification, the “inner surface” means the central liquid crystal cell side in the liquid crystal display element in which the liquid crystal cell is sandwiched between a pair of polarizing plates, and the “outer surface” means the opposite side. .

  The synthetic resin constituting the base material layer in the polarizer outer surface protective film is at least one selected from the group consisting of acrylic resins, polycarbonate resins, polypropylene resins, cycloolefin resins, and polyethylene terephthalate resins. It's okay. By using these synthetic resins, a polarizer outer surface protective film having high transparency and appropriate strength for protecting the polarizer can be obtained.

By using a composition in which the hydrophilic resin layer contains an acrylic-modified polyester resin and a urethane resin, the transparency, toughness, heat resistance inherent in the polyester resin, and synthetic resins (for example, acrylic resins, While taking advantage of properties such as adhesiveness to polyethylene terephthalate resin, etc., the side chain is modified with a radically polymerizable vinyl monomer derived from acrylic acid having a hydrophilic group, thereby providing adhesion to hydrophilic resin. Further, it becomes possible to further impart adhesiveness and flexibility to the synthetic resin by blending the urethane resin, and the initial adhesiveness is remarkably superior to that of the hydrophilic resin layer made of other compositions.

In addition, since the acrylic-modified polyester resin is modified so as to have a hydrophilic group in the side chain, the main chain (carbon chain) of the hydrophilic resin has chemical affinity with the synthetic resin of the base material layer. At the same time, the hydrophilic resin side chains are modified to impart hydrophilicity, thereby increasing the chemical affinity for the polyvinyl alcohol constituting the polarizer and stably bonding the layers of the polarizing plate. Is possible.

  In the polarizer outer surface protective film, the hydrophilic resin layer may have a thickness of 0.01 μm or more and 3 μm or less. By making the thickness of the hydrophilic resin layer 0.01 μm or more, facilitation of adhesion of a polarizer made of polyvinyl alcohol is promoted. On the other hand, by setting the thickness of the hydrophilic resin layer to 3 μm or less, a sufficiently thin polarizer outer surface protective film can be obtained, and an increase in the thickness of the polarizing plate can be suppressed.

  The polarizer outer surface protective film includes an antireflection layer (including, for example, an antiglare layer, an antireflection layer, or a low refractive index layer) or a hard coat layer laminated on the outer surface side of the base material layer. It may be. Furthermore, when the polarizer outer surface protective film provided with the antireflection layer is disposed on the display surface side of the liquid crystal display element, the antireflection function can be exhibited together with the protection of the polarizer. In addition, since the polarizer outer surface protective film further includes a hard coat layer, the protective function of the polarizer can be enhanced.

  A polarizing plate can be constituted by laminating the polarizer outer surface protective film on the outer surface side of a polarizer made of polyvinyl alcohol and laminating the polarizer inner surface protective film on the inner surface side of the polarizer. In such a polarizing plate, a polarizer and a polarizer outer surface protective film are obtained by using a polarizer outer surface protective film provided with a base material layer subjected to an easy adhesion treatment for polyvinyl alcohol on the outer surface side of the polarizer. The adhesion and durability of adhesion are improved, and the strength and handling of the polarizing plate are improved. In addition, when a polarizer inner surface protective film made of cellulose ester, which has been conventionally used, is used on the inner surface side of the polarizer, it has a small birefringence, so that the performance of liquid crystal molecules is not affected. A protective function can be exhibited.

  By laminating the polarizing plate on at least one surface side of the liquid crystal cell, a liquid crystal display element can be configured. In such a liquid crystal display element, since the adhesiveness between the polarizer and the polarizer outer surface protective film and the adhesive durability are high, and the strength and handling property of the polarizing plate are excellent, various characteristics of the liquid crystal display element are long. It is demonstrated stably over a period of time, improving reliability.

  As described above, the polarizer outer surface protective film of the present invention is a transparent synthetic resin base whose inner surface is surface-treated with a hydrophilic resin so as to facilitate adhesion with a polarizer made of polyvinyl alcohol. Since the material layer is provided, high transparency is obtained, and adhesion with a polarizer made of polyvinyl alcohol, which is also a hydrophilic resin, is dramatically improved. Moreover, the intensity | strength of such a polarizing plate and a handleability improve by providing a polarizing plate with the said polarizer outer surface protective film. Furthermore, when the liquid crystal display element includes the polarizing plate, desired characteristics are stably exhibited over a long period of time.

It is typical sectional drawing of the polarizer outer surface protection film by this invention. It is typical sectional drawing of the polarizing plate provided with the polarizer outer surface protective film by this invention of FIG. It is a schematic diagram which shows the apparatus for manufacturing the polarizing plate by this invention of FIG. It is typical sectional drawing of the liquid crystal display element provided with the polarizing plate by this invention of FIG. It is a schematic diagram which shows the structure of the general liquid crystal display element by a prior art.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

  The polarizer outer surface protective film 1 in FIG. 1 has a transparent synthetic resin base layer 2 and a hydrophilic resin layer 3. The polarizer outer surface protective film 1 is used as a protective film for a polarizer for improving resistance to impact and handleability, and is disposed on the outer surface side (A direction side shown in the figure) of the liquid crystal display element. The

  The resin constituting the base layer 2 made of transparent resin is not particularly limited as long as it has high transparency required as a polarizer outer surface protective film of a liquid crystal display element, but typically an acrylic resin. , Selected from the group consisting of polycarbonate resins, polypropylene resins, cycloolefin resins and polyethylene terephthalate resins. Since these synthetic resins have excellent optical transparency and impact strength, they can be disposed on the outer layer side of the liquid crystal display element instead of triacetyl cellulose. The base material layer 2 may contain other optional components as long as the transparency and desired strength are not impaired, but preferably contains 90% by mass or more, more preferably 98% by mass or more of the synthetic resin as described above. . Examples of optional components here include ultraviolet absorbers, stabilizers, lubricants, processing aids, plasticizers, impact resistance aids, phase difference reducing agents, matting agents, antibacterial agents, and fungicides.

  The acrylic resin used for the base material layer 2 is a resin having a skeleton derived from acrylic acid or methacrylic acid. Examples of acrylic resins include, but are not limited to, poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, and methyl methacrylate- (meth) acrylic acid esters. Copolymer, methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer, polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate- Cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer), and the like. Among these acrylic resins, poly (meth) acrylate C1-6 alkyl such as poly (meth) methyl acrylate is preferable, and methyl methacrylate resin is more preferable.

  The polycarbonate resin used for the base material layer 2 is a resin composed of a compound called poly-4,4′-isopropylidene-diphenyl carbonate. This polycarbonate resin is produced from bisphenol A and carbonyl chloride in the interfacial polycondensation method, and is produced from bisphenol A and diphenyl carbonate in the transesterification method.

  The polypropylene resin used for the base material layer 2 is a resin having a skeleton derived from propylene. Although it does not specifically limit as an example of a polypropylene resin, Copolymer of propylene homopolymer or propylene, and 1 or more types of monomers selected from the group which consists of ethylene and a C4-C12 alpha olefin. A polymer etc. are mentioned.

  The cycloolefin-based resin used for the base material layer 2 is a resin having a skeleton derived from cycloolefin. Examples of cycloolefin-based resins are not particularly limited, but resins obtained by subjecting ring-opening (co) polymers of norbornene-based monomers to polymer modification such as maleic acid addition and cyclopentadiene addition as necessary are hydrogenated And a resin obtained by addition polymerization of a norbornene monomer and a resin obtained by addition polymerization of a norbornene monomer and an olefin monomer such as ethylene and α-olefin.

  Examples of norbornene monomers used to obtain a ring-opening (co) polymer of norbornene monomers include, for example, norbornene, 2-norbornene, 5-methyl-2-norbornene, and 5,5-dimethyl-2-norbornene. 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-2-norbornene, 5-cyano-2-norbornene, 5-methyl-5-methoxycarbonyl -2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5-methyl-norbornene and the like. As the polymerization catalyst used for the ring-opening polymerization, a tungsten, molybdenum, or chromium catalyst called a metathesis polymerization catalyst is preferably used.

  The polyethylene terephthalate resin used for the base material layer 2 is a polymer obtained by the reaction of terephthalic acid and ethylene glycol. The polyethylene terephthalate resin may contain other comonomers, but those having a repeating unit of polyethylene terephthalate of 80 mol% or more are preferably used. Polyethylene terephthalate is prepared by, for example, charging dimethyl terephthalate and ethylene glycol into a reactor, carrying out a transesterification reaction while gradually raising the internal temperature, and then transferring the reaction product to the polymerization reactor to carry out the polymerization reaction under high temperature vacuum. Can be generated by doing.

  The thickness of the base material layer 2 is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 100 μm or less. By setting the thickness of the base material layer 2 to 10 μm or more, appropriate strength and rigidity can be obtained, and it becomes possible to produce a film stably and easily, and handling property when forming the hydrophilic resin layer 3 is also improved. It becomes good. On the other hand, by setting the thickness of the base material layer 2 to 200 μm or less, the line speed, productivity, controllability, etc. at the time of manufacture are enhanced.

  As the base material layer 2, one having an arithmetic average surface roughness (Ra) of 0.02 or more and 0.06 or less can be used. Further, the base material layer 2 can be subjected to a mat treatment as necessary. The arithmetic average surface roughness (Ra) of the base material layer subjected to such a mat treatment is preferably 0.07 or more and 2 or less, more preferably 0.1 or more and 1 or less. By controlling the surface roughness of the base material layer in such a range, scratches are prevented in the processing after the film raw fabric is manufactured, and the handleability is improved. Furthermore, when the base material layer is located on the uppermost surface (display surface side) of the liquid crystal display element, high antireflection performance can be obtained, and when located on the lowermost layer, sticking with other layers is effective. To be prevented. Moreover, generally, when winding up the manufactured film original fabric, it is necessary to prevent blocking by embossing (knurling) both ends in the width direction of the film. When a knurling process is performed on a film, the processing points at both ends of the film cannot be used, so that part must be cut and discarded. In the film winding operation, masking may be performed with a protective film in order to prevent damage. However, by making the arithmetic average surface roughness of the base material layer within the predetermined range as described above, blocking can be prevented without performing a knurling treatment, so that the manufacturing process is simplified and the film width direction is reduced. Both end portions can be used, and a long winding can be performed without causing film failure. Moreover, when the base material layer has an appropriate surface roughness, scratches during winding are effectively suppressed, and masking as described above becomes unnecessary.

  The retardation value (Re) of the base material layer 2 is preferably −15 nm to 15 nm, more preferably −5 nm to 5 nm. Since the base material layer has such a small retardation, the action of converting the polarization direction of the transmitted light by the polarizer outer surface protective film provided with this base material layer is suppressed, and the polarization direction of the polarizer in the transmission axis direction of the polarizer is suppressed. The influence which a polarizer outer surface protective film exerts on optimization and controllability can be suppressed. Here, the “retardation value (Re)” means the fast axis direction and the slow axis direction orthogonal to the crystal axis direction on the plane of the base layer, and the thickness of the base layer. Is a value calculated by Re = (ny−nx) d, where d is the refractive index in the x-direction and y-direction is nx and ny (nx ≠ ny).

  Although the manufacturing method of the base material layer 2 is not particularly limited, for example, additives such as a synthetic resin flake raw material and a plasticizer are mixed by a conventionally known mixing method to obtain a thermoplastic resin composition in advance, and then an optical film. Can be manufactured. This thermoplastic resin composition can be obtained, for example, by pre-blending with a mixer such as an omni mixer and then extruding and kneading the resulting mixture. In this case, the kneader used for extrusion kneading is not particularly limited, and for example, a conventionally known kneader such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used. .

  Examples of the film forming method for the base material layer 2 include known methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these, the solution casting method (solution casting method) and the melt extrusion method are preferable. At this time, a thermoplastic resin composition extruded and kneaded in advance may be used, or another additive such as a synthetic resin and a plasticizer is separately dissolved in a solvent to obtain a uniform mixed solution, and then a solution cast. You may use for the film forming process of a method (solution casting method) and a melt extrusion method.

  Solvents used in the solution casting method (solution casting method) include, for example, chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, and isopropanol And alcohol solvents such as n-butanol and 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether, etc. It is done. These solvents may be used alone or in combination of two or more. Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

  Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature of the film during melt extrusion is preferably 150 ° C. or higher and 350 ° C. or lower, more preferably 200 ° C. or higher and 300 ° C. or lower. When film-forming by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded into a film shape is wound to obtain a roll film. Under the present circumstances, it is also possible to set it as a uniaxial stretching process by adjusting the temperature of a winding roll suitably, and adding extending | stretching to an extrusion direction. It is also possible to add steps such as sequential biaxial stretching and simultaneous biaxial stretching by adding a step of stretching the film in a direction perpendicular to the extrusion direction.

  The base material layer 2 may be an unstretched film or a stretched film. When extending | stretching, a uniaxially stretched film may be sufficient and a biaxially stretched film may be sufficient. When a biaxially stretched film is used, it may be biaxially stretched simultaneously or sequentially biaxially stretched. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

  As the stretching temperature when the stretching step is performed, it is preferably performed in the vicinity of the glass transition temperature of the thermoplastic resin composition of the film raw material, specifically, (glass transition temperature-30) ° C. to (glass transition temperature + 100) ° C. It is preferable to carry out at (Glass transition temperature−20) ° C. to (Glass transition temperature + 80) ° C. When the stretching temperature is lower than (glass transition temperature-30) ° C., a sufficient stretching ratio cannot be obtained, which is not preferable. If the stretching temperature is higher than (glass transition temperature + 100) ° C., resin flow occurs, and stable stretching cannot be performed.

  The draw ratio defined by the area ratio can be preferably in the range of 1.1 to 25 times, more preferably in the range of 1.3 to 10 times. If the draw ratio is less than 1.1, it is not preferable because it does not lead to an improvement in toughness accompanying the drawing. When the draw ratio is larger than 25, the effect of increasing the draw ratio is not recognized.

  The stretching speed (one direction) is preferably in the range of 10 to 20000% / min, more preferably in the range of 100 to 10000% / min. If it is slower than 10% / min, it takes time to obtain a sufficient draw ratio, and the production cost is increased, which is not preferable. If it is faster than 20000% / min, the stretched film may be broken, which is not preferable. Furthermore, in order to stabilize the optical isotropy and mechanical properties of the base material layer 2, heat treatment (annealing) or the like can be performed after the stretching treatment.

  Although it does not specifically limit as a plasticizer, The functional group which can interact with a synthetic resin by a hydrogen bond etc. is generated so that a haze may be generated in the base material layer 2, or it may not bleed out or volatilize from the base material layer 2. It is preferable to have. Examples of such plasticizers include, but are not limited to, phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers. Glycolate plasticizers, citrate plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, and the like.

  The hydrophilic resin constituting the hydrophilic resin layer 3 is not particularly limited as long as it is a resin having a chemical affinity with the synthetic resin of the base material layer and the polyvinyl alcohol constituting the polarizer, Those in which the side chain is modified with a hydrophilic group are preferred. As a method for hydrophilic modification of a hydrophilic resin, a monomer having a hydrophilic functional group may be (co) polymerized in advance, or a monomer that becomes a main chain is (co) polymerized and then hydrophilic. The side chain may be formed by graft polymerization of a monomer having a group. The hydrophilic resin is preferably formed from a material selected from the group consisting of a polyester resin, an acrylic resin, a urethane resin, and an epoxy resin. These resins may be a single polymer or a copolymer of two or more. As the hydrophilic resin, for example, a resin having a weight average molecular weight of 300 to 30,000 can be used.

  The polyester resin constituting the hydrophilic resin layer 3 is produced by esterification (transesterification) and polycondensation of a dicarboxylic acid and a diol according to a known method. Examples of the dicarboxylic acid include aromatic dicarboxylic acids or esters such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, succinic acid, sebacic acid, and dodecanedioic acid. Hydroxycarboxylic acids such as hydroxybenzoic acid or their esters can be used. Examples of the diol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, bisphenols, and the like.

  As the polyester resin, it is preferable to impart hydrophilicity by copolymerizing a component having a hydrophilic group in addition to the dicarboxylic acid and the diol. Examples of the component having such a hydrophilic group include dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, and diol components such as diethylene glycol, triethylene glycol, and polyethylene glycol. These components having a hydrophilic group can be used, for example, in a proportion of 2 mol% to 80 mol% with respect to the dicarboxylic acid or diol. The component which comprises these polyester-type resin can be used individually or in combination of multiple types.

  The acrylic resin constituting the hydrophilic resin layer 3 can be synthesized by polymerizing a reactive polymer having a skeleton derived from acrylic acid or methacrylic acid. Examples of such reactive polymers include those having a carboxyl group such as acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxyphenyl acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxybutyl (meta ), Acrylate, 2-hydroxypropyl (meth) acrylate, those having a hydroxyl group such as 3-hydroxypropyl (meth) acrylate, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, Those having an amide group such as N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, those having a glycidyl group such as glycidyl (meth) acrylate, 7-amino-3,7-dimethyloctyl (meth) a In addition to those having an amino group such as relate and 2-dimethylaminoethyl (meth) acrylate, p-chlorostyrene, chloromethylstyrene, divinylbenzene, 4-vinylpyridine, vinyloxazoline, maleic anhydride, and the like can be given. .

  Examples of copolymer components other than the above that constitute the acrylic resin include acrylic ester, methacrylic ester, propylene, vinyl chloride, cellulose, ethylene, ethyleneimine, vinyl alcohol, peptide, and vinyl. Pyridine-based, diene-based, fluorine-based, acrylonitrile-based, and the like can be mentioned. From the viewpoints of versatility and coating properties, it is preferable to include acrylate-based and methacrylic ester-based. The component which comprises these acrylic resins can be used individually or in combination of multiple types.

  The urethane resin constituting the hydrophilic resin layer 3 can be synthesized from a polyhydroxyl compound, diisocyanate and a low molecular weight chain extender containing at least two hydrogen atoms that react with the diisocyanate by a known method. For example, after synthesizing a relatively high molecular weight polyurethane in a solvent, water is added little by little to phase inversion emulsification, and the solvent is removed by decompression, or polyethylene glycol or carboxyl group is introduced as a hydrophilic group in the polymer. There is a method in which the urethane prepolymer dissolved or dispersed in water is added and reacted with a chain extender.

  Examples of polyhydroxyl compounds used in the production of urethane resins include carboxylic acids such as phthalic acid, adipic acid, dimerized linolenic acid and maleic acid; glycols such as ethylene glycol, propylene glycol, butylene glycol and diethylene glycol; Polyester polyols obtained by dehydration condensation reaction from methylolpropane, hexanetriol, glycerin, trimethylolethane, pentaerythritol, etc .; polyoxypropylene glycol, polyoxybutylene glycol, polytetramethylene glycol, polyoxypropylene triol, polyoxyethylene poly Polyoxyethylene triol, sorbitol, pentaerythritol, sucrose, starch, phosphoric acid and other inorganic acids as initiators Oxypropylene polyol, polyether polyol such as polyoxypropylene polyoxyethylene polyol, acrylic polyol, a derivative of castor oil, tall oil derivatives, other hydroxyl compounds. These polyhydroxyl compounds can be used alone or in combination of two or more.

  Examples of diisocyanates used in the production of urethane resins include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tetramethylene. Diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4 '-Biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'- Phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate. These diisocyanates can be used singly or in combination.

  Examples of chain extenders used in the production of urethane resins include ethylene glycol, 1,4-butanediol, trimethylolpropane, triisopropanolamine, N, N-bis (2-hydroxypropyl) aniline, hydroquinone-bis. Polyols such as (β-hydroxyethyl) ether, resorcinol-bis (β-hydroxyethyl) ether, ethylenediamine, propylenediamine, hexamethylenediamine, phenylenediamine, tolylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminodiphenylmethane, diaminodicyclohexyl Examples include methane, piperazine, isophoronediamine, polyamines such as diethylenetriamine and dipropylenetriamine, hydrazines, and water. These chain extenders can be used alone or in combination of two or more.

  The synthetic reaction in the production of the urethane-based resin can be performed in the presence of a catalyst such as an organic tin compound, organic bismuth, or amine, and among these, it is particularly preferable to perform in the presence of an organic tin compound. Specific examples of organic tin compounds include stannous acetate, stannous octoate, stannous laurate, stannous oleate and the like; dibutyltin acetate, dibutyltin dilaurate, dibutyltin maleate , Dialkyltin salts of carboxylic acids such as dibutyltin di-2-ethylhexoate, dilauryltin diacetate, dioctyltin diacetate; trialkyl hydroxides such as trimethyltin hydroxide, tributyltin hydroxide, trioctyltin hydroxide Tin: Dialkyltin oxide such as dibutyltin oxide, dioctyltin oxide and dilauryltin oxide; Dialkyltin chloride such as dibutyltin dichloride and dioctyltin dichloride, etc., and these may be used alone. More than one species may be used in combination.

  The epoxy resin constituting the hydrophilic resin layer 3 can be synthesized by polymerizing a monomer having an epoxy group. Examples of such monomers include glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether. Furthermore, as a monomer copolymerizable with these monomers, vinyl ester, unsaturated carboxylic acid ester, unsaturated carboxylic acid amide, unsaturated nitrile, allyl compound, unsaturated hydrocarbon or vinyl silane compound is used. . Specific examples thereof include vinyl propionate, vinyl chloride, vinyl bromide, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, butyl maleate, malein Octyl acid, butyl fumarate, octyl fumarate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, polyethylene glycol dimethacrylate Ester, polyethylene glycol diacrylate, acrylamide, methacrylamide, methylol acrylamide, butoxymethylol acrylamide, unsaturated nitrile Acrylonitrile, allyl acetate, allyl methacrylate, allyl acrylate, diallyl itaconate, ethylene, propylene, hexane, octene, styrene, vinyl toluene, butadiene, dimethylvinylmethoxysilane, dimethylethylethoxysilane, methylvinyldimethoxysilane, methyl Examples thereof include vinyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. The component which comprises these epoxy resins can be used individually or in combination of multiple types.

  In hydrophilic modification of a hydrophilic resin, when a hydrophilic side chain is formed by (co) polymerizing a monomer as a main chain and then graft polymerizing the hydrophilic monomer, a hydrophilic radical polymerizable vinyl monomer is used. Is preferably graft polymerized. In this case, the radical polymerizable vinyl monomer can be used in a proportion of 10 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the total of the main chain components.

Examples of such hydrophilic radically polymerizable vinyl monomers include —CH ₂ —CH (R) —OH (wherein —R is —H or —CH ₃ ), —COOX (wherein X Is H, an alkali metal or a secondary or tertiary amino group), —O— (CH ₂ —CH (R) —O) _n — (wherein —R is —H or —CH ₃ , n is positive of an _{integer), - Y-N (R} 1) (R 2) (- Y- is -C (= O) - or -CH _{2 -,} -R 1, -R ₂ is -H or, A lower alkyl group which may have a hydroxyl group, a sulfonyl group, an acyl group, an amino group, an alkali metal salt or a quaternary ammonium salt), -N ⁺ -(R ₃ ) (R ₄ ) (R ₅ ) _{(wherein, -R 3, -R 4, -R} 5 is -CH ₃ or _{-C 2 H 5), - CH} 2 -CH (O) CH (O forming the sides of the carbon and epoxy ring) can be used having a hydrophilic group such as.

  Specific examples of hydrophilic radically polymerizable vinyl monomers include hydroxyacrylic acid esters such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate, ethylene glycol acrylate, ethylene glycol methacrylate, and polyethylene glycol. Glycol esters such as acrylate, polyethylene glycol methacrylate, acrylamide compounds such as acrylamide, methacrylamide, methylolacrylamide, methoxymethylolacrylamide, glycidyl acrylate compounds such as glycidyl acrylate, glycidyl methacrylate, vinyl pyridine, vinyl imidazole, vinyl pyrrolidone, etc. Nitrogen-containing vinyl compounds, acrylic acid, methacrylate Acid, maleic anhydride, itaconic acid, unsaturated acids and salts thereof such as crotonic acid, amino alkyl acrylate, a cationic monomer such as amino alkyl methacrylate and quaternary ammonium salts.

  In the hydrophilic modification of the hydrophilic resin, in addition to these radical polymerizable vinyl monomers, other vinyl monomers may be copolymerized. Examples of other copolymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate; vinyl halides such as vinyl chloride and vinyl bromide; methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid Unsaturated carboxylic acid esters such as methyl, ethyl methacrylate and butyl methacrylate; vinyl silanes such as dimethylvinylmethoxysilane and γ-methacryloxypropyltrimethoxysilane; olefins such as ethylene, propylene, styrene and butadiene, and diolefin compounds. Can be mentioned.

  Among the hydrophilic resins constituting the hydrophilic resin layer 3, the side chain is modified by a radical polymerizable vinyl monomer derived from acrylic acid having a hydrophilic group (hereinafter referred to as “acrylic radical polymerizable vinyl monomer”). A composition comprising a polyester resin (hereinafter referred to as “acrylic-modified polyester resin” or simply “modified polyester-based resin”) and a urethane resin is most preferable. By using such a composition, while taking advantage of the properties such as transparency, toughness, heat resistance inherent to the polyester resin, and adhesion to synthetic resins (for example, acrylic resins, polyethylene terephthalate resins, etc.) By the above modification, it is possible to impart adhesiveness to the hydrophilic resin, and it is possible to further impart adhesiveness and flexibility to the synthetic resin by blending the urethane resin.

  The weight average molecular weights of the acrylic radical polymerizable vinyl monomer and the urethane resin are typically 1000 or more and 15000 or less, preferably 2000 or more and 10,000 or less.

  The mass ratio of the acrylic-modified polyester resin and the urethane resin in the composition is preferably in the range of 60:40 to 90:10, and more preferably in the range of 70:30 to 80:20. By making the mass ratio of the acrylic-modified polyester resin and urethane resin in such a range, the base material layer is configured while keeping the physical properties of the hydrophilic resin layer such as transparency, water resistance and heat resistance good. It is possible to optimize the adhesive strength to the synthetic resin and the polyvinyl alcohol constituting the polarizer.

As the hydrophilic group possessed by the acrylic radical polymerizable vinyl monomer which is a modifying component of the acrylic modified polyester resin, those exemplified as the hydrophilic group of the above hydrophilic radical polymerizable vinyl monomer can be used. That is, typical hydrophilic groups possessed by the acrylic radical polymerizable vinyl monomer include —CH ₂ —CH (R) —OH, —COOX, —O— (CH ₂ —CH (R) —O) _n —. ^{_{, -Y-N (R 1)}} (R 2), - N + - (R 3) (R 4) (R 5), - CH 2 -CH (O) CH 2 ( defined as above) include It is done.

  As the acrylic radical polymerizable vinyl monomer, the acrylic monomers listed as specific examples of the above hydrophilic radical polymerizable vinyl monomer can be used. That is, specific examples of the acrylic radical polymerizable vinyl monomer include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, ethylene glycol acrylate, ethylene glycol methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate. Acrylamide, methacrylamide, methylol acrylamide, methoxymethylol acrylamide, glycidyl acrylate, glycidyl methacrylate, acrylic acid, methacrylic acid, aminoalkyl acrylate, aminoalkyl methacrylate ester and the like. These acrylic radical polymerizable vinyl monomers may be used alone or in combination of two or more kinds.

  In addition to the acrylic radical-polymerizable vinyl monomer, the acrylic-modified polyester-based resin may be obtained by copolymerizing the above copolymerizable other vinyl monomer. When the other vinyl monomer is copolymerized, for example, 1 to 70 parts by mass of the other vinyl monomer can be used with respect to 100 parts by mass of the acrylic radical polymerizable vinyl monomer.

  In the acrylic modified polyester resin, the mass ratio of the acrylic radical polymerizable vinyl monomer to the polyester resin forming the main chain is preferably 50 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the polyester resin. More preferably, it is at least 120 parts by mass. By setting the mass ratio of the acrylic radical polymerizable vinyl monomer to the polyester resin in such a range, the chemical affinity of the hydrophilic resin layer to the base material layer and the chemical affinity of the hydrophilic resin layer to the polarizer are set. Can be improved in a well-balanced manner.

  The acrylic-modified polyester resin is, for example, an aqueous solution containing a water-soluble or water-dispersible polyester resin obtained by copolymerizing a component having a hydrophilic group such as a dicarboxylic acid component such as 5-sodium sulfoisophthalic acid and polyvinyl alcohol, or It can be produced by making an aqueous dispersion and then copolymerizing an acrylic radical polymerizable vinyl monomer (and any other copolymerizable vinyl monomer). As another method, the acrylic-modified polyester resin is prepared, for example, as an aqueous solution or aqueous dispersion containing the above water-soluble or water-dispersible polyester resin and colloidal silica having a particle diameter of 4 nm to 100 nm. Then, it can be produced by copolymerizing an acrylic radical polymerizable vinyl monomer or the like.

  In the method for producing an acrylic-modified polyester resin using the above polyvinyl alcohol, for example, a proportion (solid content ratio) of 10 to 500 parts by mass of polyvinyl alcohol with respect to 100 parts by mass of the water-soluble or water-dispersible polyester. The reaction can be carried out with Moreover, in the manufacturing method of acrylic modified polyester-type resin using said colloidal silica, the ratio (solid state) of colloidal silica is 5 mass parts or more and 200 mass parts or less with respect to 100 mass parts of water-soluble or water-dispersible polyester, for example. The reaction can be carried out at a fractional ratio).

  As a polymerization method for synthesizing the acrylic-modified polyester resin, for example, in a water solution or water dispersion of the water-soluble or water-dispersible polyester and polyvinyl alcohol or colloidal silica, a polymerization initiator and, if necessary, A method of completing a polymerization reaction by adding a small amount of an emulsifying dispersant, gradually adding an acrylic radical polymerizable vinyl monomer while stirring at a temperature of about 70 ° C., and aging for several hours.

  A general radical polymerization initiator can be used as the polymerization initiator used in the production of the acrylic-modified polyester resin. Examples of polymerization initiators include water-soluble peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide, oil-soluble peroxides such as benzoyl peroxide and t-butyl hydroperoxide, and azodiisobutyronitrile. An azo compound is mentioned.

  As described above, the hydrophilic resin constituting the hydrophilic resin layer 3 is formed from a resin such as a polyester resin, an acrylic resin, a urethane resin, or an epoxy resin, and these resins are hydrophilic. By being modified, the chemical affinity for the polyvinyl alcohol constituting the polarizer is enhanced, the adhesion between the hydrophilic resin layer and the polarizer is enhanced, and at the same time, these resins and the substrate layer are further combined. Coupled with the good chemical compatibility with the synthetic resin to be formed, stable bonding of the respective layers of the polarizing plate becomes possible. Note that by using a combination of a polyester-based resin and a urethane-based resin as a resin for forming the hydrophilic resin layer, the flexibility of the layer is increased, and the strength and the adhesive force are improved.

  Since the hydrophilic resin itself has a certain degree of hydrophilicity, the hydrophilic resin layer 3 formed of this resin can be subjected to a bonding process with a polarizer without performing a saponification treatment. The hydrophilic resin formed with polyester resin is further saponified with alkali to produce a hydroxyl group, which is a hydrophilic group, thereby increasing hydrophilicity and affinity / adhesion with a polarizer made of polyvinyl alcohol. The property is further improved.

  The hydrophilic resin layer 3 can be formed by applying a water-based emulsion or an aqueous solution (hereinafter referred to as “water-based emulsion or the like”) containing a hydrophilic resin to the base layer 2 and drying. The solid content of the aqueous emulsion or the like is usually 10% by mass or more and 50% by mass or less. Water is used as the main solvent for the aqueous emulsion and the like, but a small amount of an organic solvent miscible with water may be used. Examples of such organic solvents include lower alcohols, polyhydric alcohols and alkyl ethers or alkyl esters thereof. Water-based emulsions, etc. are formed by using known dip coating methods, air knife coating methods, curtain coating methods, roller coating methods, wire bar coating methods, gravure coating methods, extrusion coating methods (die coating methods), etc. 2 can be applied. Subsequently, the hydrophilic resin layer 3 can be formed by drying the applied aqueous emulsion or the like.

  It is preferable to add a crosslinking agent to the aqueous emulsion or the like for forming the hydrophilic resin layer 3 as necessary. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, active vinyl compounds, active halogen compounds, isoxazole, dialdehyde starch, isocyanate compounds, and silane coupling agents. These crosslinking agents may be used alone or in combination of two or more. The addition amount of the crosslinking agent is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 15% by mass or less with respect to the total amount of the hydrophilic resin. In the water-based emulsion for forming the hydrophilic resin layer, if necessary, other resin components such as amino group-containing resin, surfactant, slip agent, dye, UV absorber, matting agent, Preservatives, thickeners, film-forming aids, antistatic agents, antioxidants and the like may be added.

  The thickness of the hydrophilic resin layer 3 is preferably 0.01 μm or more and 3 μm or less, more preferably 0.03 μm or more and 2 μm or less, and most preferably 0.04 μm or more and 1 μm or less. By making the thickness of the hydrophilic resin layer 3 0.01 μm or more, adhesion between the hydrophilic resin and the polyvinyl alcohol constituting the polarizer is ensured. Further, by setting the thickness of the hydrophilic resin layer 4 to 3 μm or less, the thickness of the polarizer outer surface protective film 1 can be kept sufficiently thin, and the thickness of the entire polarizing plate including the polarizer outer surface protective film 1 can be increased. Can be suppressed.

  In the polarizer outer surface protective film 1, the surface of the base material layer 2 on the side not subjected to surface treatment with a hydrophilic resin is arbitrarily selected from various functional layers such as an antiglare layer, an antireflection layer, an antiglare layer, and a low refractive index. It may be covered with an antireflection layer such as a layer, an antistatic layer, a hard coat layer (cured resin layer), an optical compensation layer, or the like. For example, when the polarizer outer surface protective film further includes an antiglare layer (antireflection layer), an antiglare function can be exhibited in addition to a protective function for the polarizer. Moreover, the protective function with respect to a polarizer is strengthened because a polarizer outer surface protective film further includes a hard coat layer.

  As such an antiglare layer, for example, a technique for forming an uneven structure on the film surface by an embossing method or a coating liquid in which particles are mixed in a binder matrix forming material is applied to the film surface, A technique for forming a concavo-convex structure by dispersing particles can be used. Moreover, as a hard-coat layer, what was formed, for example from active ray curable resin can be used. Examples of such actinic radiation curable resins include urethane acrylate resins, polyester acrylate resins, epoxy acrylate resins, polyol acrylate resins, and epoxy resins.

  As described above, the polarizer outer surface protective film according to the present invention includes a base material layer whose inner surface is surface-treated with a hydrophilic resin so as to facilitate adhesion with a polarizer made of polyvinyl alcohol. As a result, the affinity and adhesiveness with polyvinyl alcohol, which is a hydrophilic resin constituting the polarizer, are effectively improved.

  The polarizing plate 4 of FIG. 2 includes the polarizer outer surface protective film 1 of FIG. 1 on the outer surface side (the side in the A direction shown in the figure) of the polarizer 6 made of polyvinyl alcohol, It has the structure provided with the polarizer inner surface protective film 5 which consists of a cellulose ester used from. The polarizer 6 and the polarizer outer surface protective film 1 and the polarizer 6 and the polarizer inner surface protective film 5 are bonded by an adhesive (not shown).

  As the polarizer 6, a polyvinyl alcohol resin film that is dyed with a dichroic substance (for example, iodine or dichroic dye) and uniaxially stretched is used. The degree of polymerization of polyvinyl alcohol constituting the polyvinyl alcohol resin film is preferably 500 or more, more preferably 1000 or more, as in the case of the vinyl alcohol polymer constituting the hydrophilic resin. The polyvinyl alcohol resin film can be formed by a known method (for example, a casting method or casting method in which a solution obtained by dissolving a resin in water or an organic solvent is cast into a film). The thickness of the polarizer 6 varies depending on the purpose and application of the LCD in which the polarizing plate 4 is used, but is typically 5 μm or more and 100 μm or less. The polarizer 6 may contain an optional component other than the polyvinyl alcohol resin and the dichroic material as long as the polarizing function and the optical transparency are not impaired.

  As a typical manufacturing method of the polarizer 6, a series of manufacturing processes including swelling, dyeing, crosslinking, stretching, washing with water, and drying processes are employed for the polyvinyl alcohol resin film. In each processing step except the drying step, the treatment is performed by immersing the polyvinyl alcohol resin film in a solution bath used in each step. The order, number of times, and the presence / absence of each treatment of swelling, dyeing, crosslinking, stretching, washing and drying can be appropriately set according to the purpose, materials used, conditions and the like. For example, the stretching process may be performed before the dyeing process or may be performed simultaneously with the swelling process. Moreover, it is preferable to perform the crosslinking treatment before and after the stretching treatment.

  The swelling step in the series of manufacturing steps of the polarizer 6 can be performed by immersing the polyvinyl alcohol resin film in a treatment bath filled with water. Glycerin, potassium iodide, or the like can be appropriately added to the treatment bath. Typically, the temperature of the treatment bath in the swelling process is about 20 to 60 ° C., and the immersion time in the treatment bath is about 0.1 to 10 minutes. The dyeing step can be performed by immersing the polyvinyl alcohol resin film in a treatment bath containing a dichroic substance such as iodine. As a solvent used for the solution of the treatment bath, water is generally used. The dichroic substance is used at a ratio of 0.1 to 1.0 part by mass with respect to 100 parts by mass of the solvent. Typically, the temperature of the treatment bath in the dyeing process is about 20 to 70 ° C., and the immersion time is about 1 to 20 minutes.

  The crosslinking step can be performed by immersing the dyed polyvinyl alcohol resin film in a treatment bath containing a crosslinking agent. Examples of the crosslinking agent include boron compounds such as boric acid, glyoxal, and glutaraldehyde. As a solvent used for the solution of the treatment bath, water is generally used. Typically, the temperature of the treatment bath in the crosslinking step is about 20 to 70 ° C., and the immersion time is about 1 second to 15 minutes. The stretching process may be performed at any stage. The draw ratio of the polyvinyl alcohol resin film is preferably 5 times or more. As the stretching method, for example, a wet stretching method can be employed. As the solution of the treatment bath in this case, a solution in which various metal salts, iodine, boron or zinc compounds are added to water or an organic solvent is preferable.

  The washing step can be performed by immersing the polyvinyl alcohol resin film that has been subjected to various treatments in a washing bath. By this water washing step, unnecessary residues of the polyvinyl alcohol resin film can be washed away. The washing bath may be pure water or an aqueous solution of iodide (potassium iodide, sodium iodide, etc.). The temperature of the washing bath is preferably 10 to 60 ° C. Typically, the immersion time is 1 second to 1 minute. The number of times of washing with water may be one time or multiple times. As a drying process, natural drying, ventilation drying, and heat drying are employable, for example. Typically, the drying temperature is 20-80 ° C and the drying time is 1-10 minutes. The polarizer 6 can be manufactured by performing each of the above steps.

  Conventionally used polarizer inner surface protective film 5 made of cellulose ester, cellulose ester flake raw material and plasticizer, dissolved in methylene chloride to form a viscous liquid, to which the plasticizer is dissolved to form a dope, It is cast from a melt extruder onto a continuously rotating metal belt such as stainless steel, dried, peeled off from the belt in a dry state, dried, wound up and manufactured. As the cellulose ester, those selected from the group consisting of triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate are preferable, and triacetyl cellulose is particularly preferable.

  When the hydrophilic resin constituting the hydrophilic resin layer 3 of the polarizer outer surface protective film 1 is formed using a polyester-based resin, before the adhesion to the polarizer 6 is performed, the hydrophilic resin layer 3 is made of alkali. More preferably, it is subjected to a saponification treatment. By this saponification, the ester group is converted into a hydroxyl group which is a hydrophilic group, and thereby, the chemical affinity between the polarizer outer surface protective film 1 and the polarizer 6 formed of polyvinyl alcohol which is a hydrophilic resin. And the mutual adhesiveness is remarkably improved.

  As the alkaline aqueous solution used for the saponification treatment, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, or the like can be used. The concentration of these metal hydroxides is generally 5% by mass or more and 40% by mass or less. Moreover, it is preferable that the temperature of a saponification process is 10 degreeC or more and 80 degrees C or less. When the concentration of the metal hydroxide is 5% by mass or less or when the temperature of the saponification treatment is 10 ° C. or less, the time required for the saponification treatment becomes long, which is not preferable. The saponification treatment is performed by immersing the polarizer outer surface protective film 1 in an alkaline aqueous solution bath as described above for an appropriate time.

  The polarizer outer surface protective film 1 subjected to saponification treatment and the polarizer 6 made of polyvinyl alcohol are bonded together by an apparatus 7 schematically shown in FIG. The apparatus 7 for laminating a plurality of films shown in FIG. 3 includes a nip 8 for supplying a polarizer 6, a nip 9 for supplying a polarizer outer surface protective film 1, and an adhesive. And a nip 11 for pressing and joining the polarizer 6 and the polarizer outer surface protective film 1 through an adhesive.

  Examples of the adhesive used for bonding the hydrophilic resin layer 3 of the polarizer outer surface protective film 1 and the polarizer 6 by the device 7 include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, and butyl acrylate. And vinyl-based latex. Usually, these adhesives are used as an aqueous solution. The solid content concentration in the resin solution of the adhesive is preferably from 0.1 to 15% by mass in consideration of coating property and storage stability. Moreover, as a viscosity of the resin solution of an adhesive agent, the range of 1-50 mPa * s is preferable, for example.

  In the apparatus 7, the film-like polarizer 6 supplied from the nip 8 and the polarizer outer surface protective film 1 supplied from the nip 9 are sent in a direction toward the nip 11, and an appropriate amount is sandwiched between these films. Then, the polarizer 6 and the hydrophilic resin layer 3 of the polarizer outer surface protective film 1 are bonded by pressing at the nip 11, and the polarizer outer surface protective film is attached to one surface of the polarizer 6. A structure in which 1 is laminated is obtained.

  Subsequently, the polarizing plate 4 is obtained by laminating | stacking the polarizer inner surface protective film 5 also on the surface of the polarizer 6 in which the polarizer outer surface protective film 1 is not laminated | stacked using the same means. The polarizer inner surface protective film 5 is subjected to a saponification treatment with an alkali in advance before the adhesion to the polarizer 6 to convert the ester group of triacetyl cellulose into a hydroxyl group. The thickness of the laminated polarizing plate 4 is typically 10 μm or more and 100 μm or less.

  As described above, according to the polarizing plate having the polarizer outer surface protective film according to the present invention, the base layer made of synthetic resin disposed on the outer surface side of the polarizer made of polyvinyl alcohol is subjected to an easy adhesion treatment. Therefore, the adhesiveness and peeling durability between the polarizer made of polyvinyl alcohol and the polarizer outer surface protective film are enhanced, thereby improving the strength and handleability of the polarizing plate. Further, by using a polarizer inner surface protective film made of cellulose ester having a small birefringence (that is, non-orientated) on the inner surface side of the polarizer, the polarizer can be obtained without affecting the performance of the liquid crystal molecules. The protective function can be provided.

  The liquid crystal display element 12 of FIG. 4 has the liquid crystal layer 15 sandwiched between transparent medium layers 14 (for example, glass) on both sides of the liquid crystal cell 13 via the adhesive layer 16 and the polarizing plate 4 of FIG. It is comprised by bonding together (it consists of the base material layer 2, the hydrophilic resin layer 3, the polarizer inner surface protective film 5, and the polarizer 6). The polarizer outer surface protective film (base material layer 2 and hydrophilic resin layer 3) according to the present invention is disposed exclusively on the outer surface side of the polarizer 6, and the polarizer inner surface protective film 5 made of a cellulose ester that has been conventionally used is provided. It arrange | positions at the inner surface side of the polarizer 6 (the side of A direction shown in figure is an outer surface side). The materials constituting the liquid crystal layer 15, the transparent medium layer 14, and the adhesive layer 16 of the liquid crystal cell 13 are not particularly limited, and known materials can be used. In the liquid crystal display element, the polarizing plate 4 of FIG. 2 (the polarizing plate according to the present invention) is used on one side of the liquid crystal cell, and another polarizing plate according to the prior art is used on the other side of the liquid crystal cell. Good.

  Since the liquid crystal display element provided with the polarizing plate in which the polarizer outer surface protective film according to the present invention is disposed, the polarizer outer surface protective film has been subjected to an easy adhesion treatment, and therefore, the adhesion between the polarizer and the polarizer outer surface protective film, The durability against peeling is high, and the strength and handling of the polarizing plate are excellent. Therefore, various characteristics of the liquid crystal display element are continuously and stably exhibited over a long period of time, and the reliability of the entire device is improved.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

[Formation of base layer made of acrylic resin]
100 parts by mass of a methyl methacrylate / methyl acrylate copolymer (9: 1 molar ratio), 1 part by mass of [2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole], 400 parts by mass of methylene chloride and 100 parts by mass of methanol were charged in an airtight container and dissolved with stirring at 80 ° C. under pressure to obtain a dope composition. This dope composition is filtered, cooled, and then uniformly cast on an endless stainless steel band, after the solvent is evaporated until peeling is possible, the film is peeled off from the endless stainless steel band and further dried. An acrylic resin film (transparent synthetic resin base layer) having a thickness of 30 μm was obtained. This acrylic resin film is designated as Sample A1.

[Formation of base layer made of polyethylene terephthalate resin]
An ethylene glycol slurry to which beaded silica was added was prepared, and this ethylene glycol slurry was heat-treated at 190 ° C. for 2 hours. Subsequently, this was subjected to a transesterification reaction with dimethyl terephthalate, followed by polycondensation to obtain ethylene terephthalate pellets. Produced. Next, the resin obtained from the pellets was vacuum-dried at 180 ° C. for 3 hours, and then supplied to an extruder and melted by heating at 310 ° C. Subsequently, the resin melted from the extruder was extruded into a sheet and cooled and solidified on a casting drum having a surface temperature of 30 ° C., thereby producing an unstretched film. Next, the above-mentioned unstretched film was stretched 4 times in the longitudinal direction at 100 ° C. by roll stretching, and further stretched 4 times in the width direction at 110 ° C. using a tenter. Subsequently, this biaxially stretched film was crystallized by heat treatment at 235 ° C. (crystallization temperature) for 5 seconds to produce a polyethylene terephthalate resin film having a thickness of 40 μm. This polyethylene terephthalate resin film is designated as sample A2.

[Formation of hydrophilic resin layer made of polyester resin]
Using a carboxylic acid component consisting of 50% by mass of dimethyl terephthalate, 42% by mass of dimethyl isophthalate, and 8% by mass of 5-sodium sulfoisophthalic acid, and a glycol component consisting of 50% by mass of ethylene glycol and 50% by mass of neopentyl glycol, After performing the transesterification reaction at around 200 ° C. for 3 hours using zinc acetate and antimony trioxide as a catalyst, the pressure inside the reaction system was gradually reduced to 0.2 mmHg while raising the temperature to 260 ° C. to obtain a predetermined viscosity. The polycondensation was carried out until 100 parts by mass of the obtained polyester resin was uniformly dispersed in 150 parts by mass of water at around 70 ° C. to obtain an aqueous emulsion of a polyester resin having a solid content of 40% by mass. Aqueous emulsion of this polyester resin 25% by weight, polyvinyl alcohol 10% aqueous solution 25% by weight, acrylic acid 3.5% by weight, butyl methacrylate 1.5% by weight, ammonium persulfate 0.2% by weight, water 44.8 An aqueous emulsion of a modified polyester resin was obtained by charging mass% in a reactor and reacting at about 70 ° C. for 3 hours. Next, the aqueous emulsion of the modified polyester resin was applied on the surface of the acrylic resin film of Sample A1, heated and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. . This polarizer protective film is designated as Sample B1. Moreover, this water-based emulsion of the modified polyester resin was applied onto the surface of the polyethylene terephthalate resin film of Sample A2 and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B2.

[Formation of hydrophilic resin layer made of polyester resin / urethane resin]
With respect to the aqueous emulsion of the modified polyester resin obtained above, an aqueous urethane having a solid content of 40% by mass (“Aron Neotan UE-1300” manufactured by Toagosei Co., Ltd.) has a solid content ratio of both. Blending was carried out to 75:25 to obtain a water-based emulsion of a polyester resin / urethane resin mixed system. Next, this aqueous emulsion was applied onto the surface of the acrylic resin film of Sample A1, heated and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B3. Moreover, this water-based emulsion was apply | coated on the surface of the polyethylene terephthalate resin film of sample A2, and it dried and obtained the polarizer protective film which has a hydrophilic resin layer with a thickness of 0.3 micrometer. This polarizer protective film is designated as Sample B4.

[Formation of hydrophilic resin layer made of acrylic resin]
30 parts by mass of 2-hydroxyethyl acrylate 70% by mass and 30% by mass of methyl acrylate, 3 parts by mass of hydroxypivalate ester neopentylglycol diacrylate, urethane acrylate oligomer (manufactured by Nippon Kayaku Co., Ltd. “KAYARAD” UX-4101 ”) 3 parts by mass, benzoyl peroxide 0.3 parts by mass, isocyanate compound (“ Sumidule N-75 ”manufactured by Sumitomo Bayer Urethane Co., Ltd.) 1.5 parts by mass, silicone-based surface activity By blending 3 parts by mass of the agent and 50 parts by mass of water, an aqueous emulsion of an acrylic resin was obtained. This acrylic resin aqueous emulsion was applied on the surface of the acrylic resin film of Sample A1 and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B5. Further, this aqueous emulsion of acrylic resin was applied on the surface of the polyethylene terephthalate resin film of Sample A2, heated and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B6.

[Formation of hydrophilic resin layer made of urethane resin]
Aqueous urethane having a solid content of 40% by mass (“Aron Neotan UE-1300” manufactured by Toagosei Co., Ltd.), 25% by mass of a 10% aqueous solution of polyvinyl alcohol, 5% by mass of hydroxyethyl methacrylate, 0. An aqueous emulsion of urethane resin was obtained by charging 2% by mass and 44.8% by mass of water into a reactor and reacting at about 70 ° C. for 3 hours. This urethane resin aqueous emulsion was applied on the surface of the acrylic resin film of Sample A1, and then heated and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B7. Further, this urethane resin aqueous emulsion was applied onto the surface of the polyethylene terephthalate resin film of Sample A2 and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B8.

[Formation of hydrophilic resin layer made of epoxy resin]
30 parts by mass of a copolymer of 70% by mass of glycidyl acrylate and 30% by mass of vinyl propionate, 3 parts by mass of diacrylate of hydroxypivalate ester neopentyl glycol, urethane acrylate oligomer (“KAYARAD manufactured by Nippon Kayaku Co., Ltd.) "UX-4101") 3 parts by mass, 0.3 parts by mass of benzoyl peroxide, 1.5 parts by mass of isocyanate compound ("Sumidule N-75" manufactured by Sumitomo Bayer Urethane Co., Ltd.), silicone surfactant 3 An aqueous emulsion of an epoxy resin was obtained by blending 50 parts by mass of water and 50 parts by mass of water. This epoxy resin aqueous emulsion was applied on the surface of the acrylic resin film of Sample A1 and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B9. Moreover, this epoxy resin aqueous emulsion was applied on the surface of the polyethylene terephthalate resin film of Sample A2, heated and dried to obtain a polarizer protective film having a hydrophilic resin layer having a thickness of 0.3 μm. This polarizer protective film is designated as Sample B10.

[Formation of polarizer]
A polyvinyl alcohol film having a thickness of 200 μm was uniaxially stretched (temperature 110 ° C., stretch ratio 5 times) to obtain a film having a thickness of 40 μm. This film was immersed in an aqueous solution containing 0.15 g of iodine and 10 g of potassium iodide for 60 seconds, and then immersed in an aqueous solution at 68 ° C. containing 12 g of potassium iodide and 7.5 g of boric acid. This was washed with water and dried to obtain a polarizer.

[Example 1-10]
Each of the polarizer protective films of Samples B1 to B10 and the polarizer is cut into a size of 18 cm × 5 cm, and these are overlapped via an adhesive that is a polyvinyl alcohol aqueous solution having a solid content concentration of 2 mass%. Bonding was performed while removing excess adhesive and bubbles using a roller. This was inserted into a laminator pressurized to 2 kg / cm ² and further dried at 80 ° C. to obtain laminates 1 to 10 (respectively, examples 1 to 10). In this bonding, each of the hydrophilic resin layers of Samples B1 to B10 and the polarizer were bonded.

[Comparative Examples 1 and 2]
The acrylic resin film of sample A1 or the polyethylene terephthalate resin film of sample A2 and the polarizer were bonded together by the same means as in Examples 1 to 10 to obtain laminates 11 and 12.

  The laminates 1 to 12 obtained above were evaluated for the properties regarding initial adhesion and durability by the following methods. These evaluation results are shown in Table 1.

(1) Initial adhesion The two layers of the laminate were peeled off by hand, and evaluated according to the following three stages according to the degree of occurrence of material destruction.
Extremely good (）): Material destruction occurs in most parts.
Good (O): Material destruction occurs in about half of the area.
Slightly poor (Δ): Some material destruction occurs, but the peeled area between the sample and the polarizer is large.
Poor (x): The sample and the polarizer are completely peeled off.

(2) Durability The laminate was allowed to stand at 75 ° C. under a condition of 90% RH for 500 hours, the appearance change was observed, and the width of peeling from the end portion was measured. The evaluation criteria were as follows.
Very good (◎): less than 0.1 mm Good (◯): 0.1 mm or more and 0.5 mm or less Slightly poor (Δ): 0.5 mm or more and 1.5 mm or less Defect (x): 1.5 mm or more

  From the result of Table 1, it turned out that the laminated bodies 1 to 10 of Examples 1 to 10 have good initial adhesiveness and excellent peeling durability under severe conditions. In particular, the initial adhesiveness in Examples 3 and 4 using materials B3 and B4 formed from an aqueous emulsion containing a modified polyester resin and a urethane resin was remarkably excellent. On the other hand, the laminates 11 and 12 of Comparative Examples 1 and 2 were found to have poor initial adhesion and poor peeling durability. Thus, the protective film for the outer surface of the polarizer according to the present invention is provided with a base material layer whose one surface is surface-treated with a hydrophilic resin. Compared with the film which consists of a layer, the adhesive force with respect to polyvinyl alcohol and peeling durability are improved dramatically.

  Since the liquid crystal display element using the polarizing plate provided with the polarizer outer surface protective film according to the present invention is securely bonded between the polarizer outer surface protective film and the polarizer, the liquid crystal display element and the liquid crystal display element are provided. Reliability of the entire electronic equipment is increased. Therefore, such a liquid crystal display element can be used in various fields ranging from small products such as calculators and watches to large products such as automobile meters, PC monitors, and televisions.

DESCRIPTION OF SYMBOLS 1 Polarizer outer surface protection film 2 by this invention Transparent synthetic resin base material layer 3 Hydrophilic resin layer 4 Polarizing plate 5 Polarizer inner surface protective film 6 made of cellulose ester Polarizer 7 Apparatus 8 for producing a polarizing plate Nip 9 Nip 10 Adhesive supply means 11 Nip 12 Liquid crystal display element 13 Liquid crystal cell 14 Transparent medium layer 15 Liquid crystal layer 16 Adhesive layer 21 Liquid crystal display element 22 Polarizer 23 Polarizer protective film 24 Polarizer 25 Liquid crystal cell 26 Transparent medium layer 27 Liquid crystal layer 28 Adhesive layer

Claims (6)

A polarizer outer surface protective film disposed on the outer surface side of the liquid crystal display element,
A transparent synthetic resin base material layer;
A hydrophilic resin layer laminated on the inner surface side of the base material layer ,
This hydrophilic resin layer is comprised from the composition containing acrylic modified polyester resin and urethane resin, The polarizer outer surface protective film characterized by the above-mentioned.   The synthetic resin constituting the base material layer is at least one selected from the group consisting of acrylic resins, polycarbonate resins, polypropylene resins, cycloolefin resins, and polyethylene terephthalate resins. Polarizer outer surface protective film. The polarizer outer surface protective film according to claim 1, wherein the hydrophilic resin layer has a thickness of 0.01 μm or more and 3 μm or less. The polarizer outer surface protective film according to claim 1 , further comprising an antireflection layer or a hard coat layer laminated on the outer surface side of the base material layer. A polarizer made of polyvinyl alcohol;
The polarizer outer surface protective film according to any one of claims 1 to 4 , which is laminated on an outer surface of the polarizer,
A polarizer comprising: a polarizer inner surface protective film laminated on an inner surface of the polarizer. A liquid crystal cell;
A liquid crystal display device comprising: the polarizing plate according to claim 5 laminated on at least one surface side of the liquid crystal cell.

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