WO2011129531A2 - Polarising plate and a liquid-crystal display device comprising the same - Google Patents

Abstract

The present invention relates to a polarising plate and to a liquid-crystal display device comprising the same. More specifically, the present invention relates to a polarising plate which comprises, with respect to 100 parts by weight of a water-soluble polyamide epoxy resin, between 1 and 100 parts by weight (based on solids content) of an acetoacetyl-modified poly(vinyl alcohol) resin, and also comprises an adhesive layer of an adhesive composition having a pH of at least 5, thereby increasing the force of bonding between the functional group of the adhesive composition in the adhesive layer and a protective film (acrylic or propylene based) and a polarizer functional group and hence making it possible to improve durability and reliability by maintaining an adhesive force between the polarizer and the protective film even under high temperature and highly humid conditions. The present invention also relates to a liquid-crystal display device comprising the polarising plate.

Description

Polarizing plate and liquid crystal display including the same

The present invention relates to a polarizing plate which is excellent in adhesive strength with a polarizer and a protective film even under high temperature and high humidity conditions, thereby improving durability.

Liquid crystal display devices have low power consumption, operate at low voltage, are light weight, and are used in various display devices utilizing features such as thin shapes.

The liquid crystal display device is composed of many materials such as a liquid crystal cell, a polarizing plate, a retardation film, a light collecting sheet, a diffusion film, a light guide plate, and a light reflection sheet. By reducing the number of films or sheets formed therein or by reducing the thickness of the films or sheets, improvements in research aiming to improve productivity, light weight, brightness, and the like have been actively conducted.

In addition, a liquid crystal display device is required to a product that can withstand the strict durability conditions depending on the application. For example, the liquid crystal display device for an automobile navigation system may have a high temperature and humidity in a vehicle, so that the temperature and humidity conditions are stricter than that of a general television or personal computer monitor. In this case, the polarizer used in the product also requires high durability (temperature and humidity durability).

The polarizing plate usually has a structure in which a transparent protective film is laminated on both surfaces or one side of a polarizer made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented.

The polarizer is produced by a method of longitudinally uniaxial stretching and dyeing with a dichroic dye on a polyvinyl alcohol-based resin film, followed by boric acid treatment to perform a crosslinking reaction, and washing with water and drying. As the dichroic dye, iodine or a dichroic organic dye is used. A polarizing plate is manufactured by stacking a protective film on both surfaces or one side of the polarizer thus manufactured, and introduces the manufactured polarizing plate into the liquid crystal display device.

As a protective film, the cellulose acetate-type resin film represented by triacetyl cellulose is used abundantly, and thickness is about 30-120 micrometers normally. In addition, the protective film often uses an adhesive made of an aqueous solution of polyvinyl alcohol-based resin when laminated.

When the polarizing plate which laminated | stacked the cellulose-type protective film which consists of triacetylcellulose through the adhesive which consists of aqueous solution of polyvinyl alcohol-type resin on both surfaces or one side of the polarizer in which a dichroic dye is adsorption-oriented is used for a long time under moist heat conditions, Polarization performance deteriorates or a protective film and a polarizer peel easily.

In addition, the cellulose-based protective film has a low heat and moisture resistance has a disadvantage in that the polarizing plate applied to the polarizing plate performance, such as polarization degree, color under high temperature or high humidity conditions.

Therefore, there have been attempts to constitute at least one protective film with various resins other than cellulose acetate.

For example, Japanese Patent Laid-Open No. 8-43812 discloses that at least one of the protective films is made of thermoplastic norbornene-based resin having a function of retardation film in a polarizing plate in which protective films are laminated on both surfaces of the polarizer.

Further, Japanese Laid-Open Patent Publication No. 2002-174729 has a protective film made of an amorphous polyolefin resin laminated on one side of a polarizer made of a polyvinyl alcohol resin film adsorbed and oriented with iodine or dichroic organic dye, and the other. The surface has described the polarizing plate in which the protective film which consists of resin different from amorphous polyolefin resin, such as cellulose acetate type resin, was laminated | stacked.

Further, Japanese Laid-Open Patent Publication No. 2004-334168 discloses a polarizing plate in which a protective film made of cycloolefin resin is laminated with a polyvinyl alcohol polarizer via an adhesive containing a urethane adhesive and a polyvinyl alcohol resin.

However, amorphous polyolefin resins (cycloolefin resins), such as norbornene resins, are generally expensive as resins which have been put to practical use in recent years. In addition, amorphous polyolefin resins are easily eroded by organic solvents such as acetone, toluene and ethyl acetate. Since such an organic solvent is used for manufacture of an adhesive agent, it may remain in an adhesive agent.

In addition, under high temperature or high humidity conditions, there is a problem that the adhesive strength between the polarizer and the protective film is low to satisfy the demand for durability reliability.

The present invention provides a polarizing plate including an adhesive layer which is not only excellent in adhesion but also maintains excellent adhesion with a polarizer and a protective film (acrylic or propylene) under high temperature and high humidity. There is this.

Another object of the present invention is to provide a liquid crystal display device including the polarizing plate.

The present invention includes 1 to 100 parts by weight (based on solids content) of acetoacetyl group-modified polyvinyl alcohol-based resin based on 100 parts by weight of a water-soluble polyamide epoxy resin, and includes an adhesive layer made of an adhesive composition having a pH of 5 or more. It provides a polarizing plate.

The adhesive layer may be made of an adhesive composition having a pH of 9 to 12.

The adhesive layer may be made of an adhesive composition having a solid content of 3 to 20 parts by weight based on 100 parts by weight of the solvent.

The polarizing plate may include a polarizer, an adhesive layer laminated on one surface of the polarizer, and an acrylic or propylene protective film laminated on the adhesive layer.

The polarizing plate may be further laminated on the other side of the polarizer by the adhesive composition acrylic, cellulose, polyolefin-based or polyester-based protective film.

An acrylic, cellulose, polyolefin-based or polyester-based protective film may be further laminated by an adhesive layer including a water-soluble polyvinyl alcohol-based resin on the other side of the polarizer.

The acetoacetyl group-modified polyvinyl alcohol-based resin may include 1 to 50 parts by weight (based on solids content) based on 100 parts by weight of the water-soluble polyamide epoxy resin.

The acrylic or propylene protective film surface laminated on the adhesive layer may be treated by at least one method selected from the group consisting of corona, plasma and primer.

The adhesive composition may comprise a basic compound.

In addition, the present invention provides a liquid crystal display device including the polarizing plate.

The polarizing plate of the present invention not only has excellent adhesive strength but also has excellent adhesive strength with a polarizer and a protective film (particularly, acrylic or propylene protective film) under high temperature and high humidity conditions, thereby improving durability.

In addition, the polarizing plate of the present invention can be usefully applied to the existing polarizing plate manufacturing process can be applied without additional processes or equipment.

In addition, the present invention may be useful when the polarizing plate or the liquid crystal display including the polarizing plate is transported through or used in a high temperature and high humidity region such as a tropical region, an area adjacent to the sea, and near the equator.

In addition, the present invention can be effectively used even if the distance between the polarizer and the backlight is reduced by using a backlight with a large amount of heat generation for better clarity or thinning the liquid crystal display.

1 is a structure of a polarizing plate according to an example of the present invention,

Figure 2 shows a test method for hot water resistance of the polarizing plate.

[Description of the code]

1: Sample 1a: end of protective film

2: area where no polarizer is present 3: portion where color is missing at the periphery of the sample

4: polarizer 5: gripping portion

The present invention relates to a polarizing plate that is excellent in solvent resistance and excellent in adhesive strength with a polarizer and a protective film even under high temperature and high humidity conditions, thereby improving durability.

Hereinafter, the present invention will be described in detail.

The polarizing plate of the present invention includes a polarizer, an adhesive layer laminated on one side of the polarizer, and a protective film (acrylic or propylene) laminated on the adhesive layer.

The adhesive layer is composed of an adhesive composition containing a water-soluble polyamide epoxy resin and an acetoacetyl group-modified polyvinyl alcohol-based resin.

The water-soluble polyamide epoxy resin included in the adhesive composition constituting the adhesive layer is not particularly limited, but specifically, a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid are reacted. Resin obtained by making epichlorohydrin react with the obtained polyamide polyamine can be used.

As an example, Sumirez Resin 650 (Sumitomo Chemical Co., Ltd.), Sumirez Resin 675 (Sumitomo Chemical Co., Ltd.), and WS-525 (Nipbon PMC Co., Ltd.) may be used.

The adhesive layer of the present invention may have excellent adhesion even when using an acrylic or propylene protective film having a low adhesive strength of the protective film.

Specifically, the adhesion between the epoxy functional group of the polyamide epoxy resin compound contained in the adhesive composition and the nucleophilic functional group on the protective film surface is high.

In addition, since the polyamide epoxy resin compound contains a large amount of electrophilic functional groups and is activated by hydrogen chloride, reactivity with nucleophilic functional groups on the surface of the protective film may be further increased. In this case, if the adhesive composition is in the basic condition, since the activation of the nucleophilic functional group on the surface of the protective film may be increased, the adhesion may be further improved.

The adhesive layer of the present invention is excellent in adhesion not only to the protective film but also to the polarizer.

Specifically, the epoxy group of the polyamide epoxy resin compound contained in the adhesive composition may ring-open to form a hydrophilic group, and the hydrophilic group and the hydroxyl group on the surface of the polarizer (polyvinyl alcohol (PVA)) may be hydrogen-bonded to improve the adhesion of the polarizer. .

In addition, the acetoacetyl group-modified polyvinyl alcohol (PVA) -based resin contained in the adhesive composition serves to improve adhesion to protective films such as polyvinyl alcohol (PVA) -based polarizers and cellulose films.

Acetoacetyl group-modified polyvinyl alcohol (PVA) -based resins are more excellent in terms of improving durability because they contain highly reactive functional groups than modified polyvinyl alcohol resins such as carboxyl group modification, methylol group modification, amino group modification, and the like.

Acetoacetyl group-modified polyvinyl alcohol-type resin can be obtained by making polyvinyl alcohol-type resin and diketene react by a well-known method. Specifically, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid, and then adding diketene thereto, and dissolving the polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane in advance and then diketene It can be obtained by a method of adding the above, or a method of directly bringing diketene gas or liquid diketene into contact with the polyvinyl alcohol-based resin. The acetoacetyl group-modified polyvinyl alcohol-based resin is not particularly limited as long as the acetoacetyl group modification is 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, most preferably 2 It is good to be 7 mol%. When the degree of denaturation of the acetoacetyl group is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient and inadequate. If the degree of modification of the acetoacetyl group exceeds 40 mol%, the effect of improving the water resistance may be insignificant.

Examples of products include Z-100, Z-200, Z-200H, Z-210, Z-220, and Z-320 (Japan Synthetic Chemical Gohsefimer).

The content of acetoacetyl group-modified polyvinyl alcohol-based resin is slightly different depending on the type of protective film to be bonded, and specifically, acetoacetyl group-modified polyvinyl alcohol-based resin 1 to 100 based on 100 parts by weight of the water-soluble polyamide epoxy resin. Part by weight (based on solids content), preferably 10 to 50 parts by weight. If the content is less than 1 part by weight, the adhesiveness with the polyvinyl alcohol polarizer is not good. If the content is more than 100 parts by weight, the adhesiveness with the protective film, particularly acrylic or polyolefin crab protective film is poor. The problem of peeling occurs.

In addition, the adhesive layer consists of an adhesive composition with a pH of 5 or more. It is preferable that the said adhesive composition is pH 9-12 which is basic conditions in consideration of process convenience, such as applicability | paintability of an adhesive agent. PH adjustment of the adhesive composition is not specifically limited, it is preferable to use for example a basic compound, such as NaOH, KOH, NH ₄ OH. The more basic the pH of the adhesive composition, the higher the reactivity of the functional group of the protective film (particularly acrylic or propylene protective film) and the functional group of the adhesive composition to improve the adhesion.

Although the form of an adhesive composition is not specifically limited, It is preferable that it is liquid form in order to form a uniform adhesive bond layer on the surface of the polarizer which is a to-be-adhered body, or a protective film. Such liquid adhesives may be used in the form of a solution or a dispersion of various solvents. In consideration of the coating properties of the substrate, a solution type is preferable. In view of stability, a solution or dispersion of water is preferable.

In addition, for the purpose of shortening the drying step, a water / alcohol mixed solvent may be used which is easily mixed with water in the adhesive solution and which contains an alcohol solvent having a lower boiling point than water. The boiling point of the alcohol solvent is preferably 100 ° C. or lower, preferably 80 ° C. or lower, and more preferably 70 ° C. or lower.

In addition, the adhesive composition may contain additives generally used in the art without departing from the object of the present invention. Specifically, the additives include antifoaming agents, leveling agents, coloring agents (dyes and pigments), fluorescent brighteners, ultraviolet absorbers, antioxidants, fillers, plasticizers, antistatic agents, heat stabilizers, surfactants, desiccants, deodorants, antibacterial agents, preservatives, antifoaming agents, and the like. This can be used.

The adhesive layer is composed of an adhesive composition having a solid content of 3 to 20 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the solvent. If the solid content is less than 3 parts by weight, the adhesive force between the propylene-based protective film and the polarizer is poor, and if it exceeds 20 parts by weight, the viscosity of the adhesive composition is high, resulting in poor processability and poor coating properties.

The present invention laminates an acrylic or propylene protective film on the adhesive layer with a polarizer protective film.

Specifically, the acrylic protective film may be polymethyl (meth) acrylate, polyethyl (meth) acrylate, or the like.

Although it does not specifically limit as (meth) acrylic-type resin, For example, poly (meth) acrylic acid ester, such as poly (meth) methacrylate, methyl methacrylate (meth) acrylic acid copolymer, methyl methacrylate (meth) ) Acrylic acid ester copolymer, methacrylic acid methyl-acrylic acid ester- (meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin etc.), the polymer which has alicyclic hydrocarbon group (for example, methacrylic acid Methyl-methacrylic acid cyclohexyl copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) etc. are mentioned.

Preferably alkyl of poly (meth) acrylic acid C ₁ to C ₆ , such as methyl poly (meth) acrylate, particularly preferably methyl methacrylate is the main component (50 to 100% by weight, preferably 70 to 100% by weight) Methyl methacrylate type resin used is mentioned.

As a specific example of the said (meth) acrylic-type resin, the ring structure is carried out in the molecule | numerator of the I-film by the Japan Xeon Co., Ltd., Acripet VH by the Mitsubishi Rayon company, Acripet VRL20A, and Unexamined-Japanese-Patent No. 2004-70296. The (meth) acrylic-type resin which has, high glass transition temperature (Tg) (meth) acrylic-type resin obtained by intramolecular crosslinking and intramolecular cyclization reaction is mentioned. Moreover, the (meth) acrylic-type resin which has the lactone ring structure of Unexamined-Japanese-Patent No. 2002-120326 or Unexamined-Japanese-Patent No. 2002-254544 is mentioned.

The propylene protective film includes a propylene resin. The propylene-based resin is usually made of propylene monomer and exhibits crystallinity, and may be a homopolymer of propylene monomer, or a copolymer with a comonomer copolymerizable with propylene monomer.

The comonomer copolymerized with propylene may be, for example, ethylene or an α-olefin having 4 to 20 carbon atoms. α-olefins are specifically 1-butene, 2-methyl-1-propene (above C ₄ ); 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene (above C ₅ ); 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3- Dimethyl-1-butene (above C ₆ ); 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3-ethyl-1-butene (above C ₇ ); 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl- 1-pentene, 2-propyl-1-pentene, 2,3-diethyl-1-butene (more than C ₈ ); 1-nonene (C ₉ ); 1-decene (C ₁₀ ); 1-undecene (C ₁₁ ); 1-dodecene (C ₁₂ ); 1-tridecene (C ₁₃ ); 1-tetradecene (C ₁₄ ); 1-pentadecene (C ₁₅ ); 1-hexadecene (C ₁₆ ); 1-heptadecene (C ₁₇ ); 1-octadecene (C ₁₈ ); 1-nonadecene (C ₁₉ ) and the like.

Preferred among the α-olefins are α-olefins having 4 to 12 carbon atoms, specifically 1-butene, 2-methyl-1-propene; 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene; 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3- Dimethyl-1-butene; 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3-ethyl-1-butene; 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl- 1-pentene, 2-propyl-1-pentene, 2,3-diethyl-1-butene; 1-nonene; 1-decene; 1-undecene; 1-dodecene, etc. are mentioned. In consideration of the copolymerizability, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and 1-butene and 1-hexene are more preferable.

In this case, the copolymer may be applied to both random copolymer or block copolymer. Preferred copolymers include propylene / ethylene copolymers and propylene / 1-butene copolymers. The content of ethylene monomers or 1-butene monomers of propylene / ethylene copolymers or propylene / 1-butene copolymers is described, for example, in the method described on page 616 of the Polymer Analysis Handbook (1995, published by Kinokunishoten). Can be obtained by performing infrared (IR) spectrum measurement.

Moreover, in consideration of the transparency and the workability improvement as a protective film of a polarizing plate, it is preferable to form a random copolymer with arbitrary unsaturated hydrocarbons mainly using propylene. The random copolymer is preferably a copolymer of propylene and ethylene.

In the case of a copolymer, it is preferable that the copolymerization ratio of an unsaturated hydrocarbon is 1 to 10 weight%, More preferably, it is 3 to 7 weight%. Processability and transparency can be improved by making the copolymerization ratio of an unsaturated hydrocarbon monomer into 1 weight% or more. However, when the copolymerization ratio exceeds 10% by weight, the melting point of the resin is lowered and heat resistance tends to be deteriorated. Moreover, when copolymerizing two or more types of comonomers and propylene, it is preferable that the content of all the comonomers contained in a copolymer is the said range.

The propylene resin can be produced by a method of homopolymerizing propylene using a known polymerization catalyst or copolymerizing propylene with other copolymerizable comonomers. Known polymerization catalysts include, for example, (1) Ti-Mg catalysts composed of a solid catalyst component containing magnesium, titanium and halogen as essential components; (2) a catalyst system in which a solid catalyst component containing magnesium, titanium, and halogen as an essential component is combined with an organoaluminum compound and, if necessary, a third component such as an electron donating compound; (3) metallocene catalysts;

In the production of propylene-based resins used as the protective film according to the present invention among these catalyst systems, it is preferable to use a catalyst obtained by combining an organoaluminum compound and an electron donating compound in a solid catalyst component having magnesium, titanium and halogen as essential components It is common.

Specific examples of the organoaluminum compound include triethyl aluminum, triisobutyl aluminum, a mixture of triethyl aluminum and diethyl aluminum chloride, tetraethyl alumoxane, and the like, and preferably as an electron donating compound, cyclohexylethyldimethoxysilane , Tert-butylpropyldimethoxysilane, tert-butylethyldimethoxysilane, dicyclopentyldimethoxysilane and the like can be used. As a solid catalyst component which has magnesium, titanium, and halogen as an essential component, the catalyst system as described in Unexamined-Japanese-Patent No. 61-218606, Unexamined-Japanese-Patent No. 61-287904, Unexamined-Japanese-Patent No. 7-216017, etc. is mentioned, for example. Can be used. In addition, as the metallocene catalyst, for example, the catalyst system described in Korean Patent No. 2587251, Korean Patent No. 2627669, and Korean Patent No. 2668732 may be used.

The propylene resin may be a known polymerization method, specifically, a solution polymerization method using an inert solvent represented by a hydrocarbon compound such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, and xylene; Block polymerization method using a liquid monomer as a solvent; And a gas phase polymerization method for polymerizing a monomer of a gas as it is. Such polymerization can be carried out batchwise or continuously.

In addition, the stereoregularity of the propylene-based resin may be isotactic, syndiotactic, atactic, and the like. In consideration of heat resistance, syndiotactic or isotactic polypropylene resins are preferred.

The propylene resin can be used by mixing a known additive in a range that does not inhibit the effect according to the present invention. The additives include, for example, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents and antiblocking agents. Such additives may be used in combination of two or more.

Antioxidants include, for example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine light stabilizers and the like. Moreover, the complex antioxidant containing the monomer which has both the phenolic antioxidant and phosphorus antioxidant group in 1 molecule can also be used. Examples of the ultraviolet absorber include ultraviolet absorbers such as 2-hydroxybenzophenone series and hydroxyphenylbenzotriazole series, and benzoate sunscreen agents. The antistatic agent can be used in both polymer type, oligomer type and monomer type. Lubricants include, for example, higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and salts thereof. Examples of the nucleating agent include polymer-based nucleating agents such as sorbitol-based nucleating agents, organophosphate-based nucleating agents, and polyvinylcycloalkanes. Antiblocking agents are fine particles of spherical or near spherical shape and can be used in both inorganic and organic systems.

The propylene resin used in the present invention preferably has a melt flow rate (MFR) of 0.1 to 200 g / 10 minutes, preferably 0.5 to 50 g / 10 minutes, measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K 7210. . The polypropylene resin in the melt flow rate range can produce a uniform film-like material without applying a large load to the extruder.

The present invention is to form a film of the above acrylic resin or propylene resin to use as a protective film of the polarizer. The protective film is preferably transparent and substantially free of frontal phase difference. For example, a propylene-based film having substantially no frontal phase difference can be produced by extrusion molding from molten resin, a solvent casting method by applying a resin dissolved in an organic solvent onto a flat plate, and removing the solvent to form a film.

The polarizer protective film according to the present invention is a film excellent in transparency and small in phase difference. Specifically, transparency has a total haze value of 10% or less, preferably 7% or less, which is measured according to JIS K 7105. The front phase difference value RO is usually 20 nm or less, preferably 10 nm or less, more preferably 7 nm or less, and even more preferably 5 nm or less.

The acrylic or propylene protective film has a thickness of 5 to 200 μm, preferably 10 to 150 μm.

The acrylic or propylene protective film surface laminated on the adhesive layer may be treated by at least one method selected from the group consisting of corona, plasma and primer. Preferably, corona treatment is preferable.

Corona treatment is a process of activating a resin film disposed between electrodes by applying and discharging a high voltage between the electrodes. Corona treatment varies depending on the type of electrode, electrode spacing, voltage, humidity, type of resin film to be used, and the like. For example, it is preferable to set the electrode spacing to 1 to 5 mm and the moving speed to about 3 to 20 m / min. After the corona discharge treatment, an adhesive layer is formed on the treated surface and the polarizer is bonded.

In addition, the polarizing plate of the present invention may be further laminated on the other side of the polarizer by the adhesive layer acrylic, cellulose, polyolefin-based or polyester-based protective film.

Specific examples thereof include acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; Cellulose resins such as diacetyl cellulose and triacetyl cellulose; Polyolefin resins such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefin-based and ethylene-propylene copolymers; A protective film containing these etc. can be mentioned. The manufacturing method of the protective film is the same as the method of manufacturing the propylene-based protective film.

The bonding easy process can be performed to the surface joined with the polarizer of a protective film. Examples of the easy treatment for bonding include dry treatment such as plasma treatment, corona treatment, chemical treatment such as alkali treatment (soap treatment), and coating treatment for forming an easy adhesive layer.

The thickness of the adhesive layer is usually about 0.01 to 10 µm, preferably 0.05 to 5 µm, and most preferably 0.1 to 1 µm. The surface which is not bonded to the polarizer of the protective film may be subjected to a treatment for the purpose of hard coat treatment, antireflection treatment, sticking prevention, diffusion or antiglare.

The bonding method may be a conventional method in the art, for example, using a casting method, a meyer bar coating method, a gravure coating method, a die coating method, a dip coating method, a spray coating method, or the like on the bonding surface of the polarizer or the protective film. After apply | coating an adhesive composition, the method of joining these is mentioned. In the casting method, the adhesive composition is applied to the bonding surface while the polarizer or the protective film is generally moved in the vertical direction, the horizontal direction, or the inclined direction between the two.

) To apply. After the adhesive composition is applied, the polarizer or the protective film is sandwiched by nip roll or the like.

After bonding the polarizer and the protective film may be a drying treatment. The drying treatment is carried out, for example, by spraying hot air, and the drying temperature is appropriately selected in the range of 40 to 100 ° C, preferably 60 to 100 ° C. Drying time may be about 20 to 1,200 seconds. After drying, curing is preferably performed at room temperature or slightly higher, for example, at a temperature of 20 to 50 ° C. for about 12 to 600 hours. The thickness of an adhesive bond layer after drying is 0.001-5 micrometers normally, Preferably it is 0.01 micrometer-2 micrometers, More preferably, it is 0.01-1 micrometer or less. When the thickness of an adhesive bond layer exceeds 5 micrometers, it will be easy to produce the external appearance problem of a polarizing plate.

On the other side of the polarizer, the protective film is bonded to one surface, a surface treatment layer such as a hard coating layer, an antireflection layer, an antiglare layer, an antistatic layer may be further laminated as necessary. In addition, the optical functional film may be further laminated by the pressure-sensitive adhesive layer. As the optical functional film, for example, an optical compensation film in which a liquid crystalline compound or a polymer compound thereof is oriented on the surface of a substrate, reflective polarization that transmits polarized light of any kind and reflects polarized light having a property opposite thereto. Separation film, retardation film containing polycarbonate resin, retardation film containing cyclic polyolefin-based resin, anti-glare function film having an uneven shape on the surface, an additional film subjected to the surface anti-reflection treatment, a reflection film having a reflection function on the surface, The semi-transmissive reflective film etc. which have a reflection function and a transmission function together are mentioned.

In addition, by the adhesive layer containing a water-soluble polyvinyl alcohol-based resin on the other side of the polarizer, an acrylic, cellulose-based, polyolefin-based or polyester-based protective film may be laminated.

The water-soluble polyvinyl alcohol-based resin is not particularly limited, but partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, acetacetyl-modified polyvinyl alcohol, methylol-modified polyvinyl alcohol, amino-modified polyvinyl alcohol Etc. can be used.

The polarizer is a dichroic dye adsorbed on the stretched polyvinyl alcohol-based film.

The polyvinyl alcohol-based resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate-based resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with this besides the polyvinyl acetate which is a homopolymer of vinyl acetate are mentioned. As another monomer copolymerizable with vinyl acetate, an unsaturated carboxylic acid type, an unsaturated sulfonic acid type, an olefin type, a vinyl ether type, an acrylamide type monomer which has an ammonium group, etc. are mentioned. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. Saponification degree of polyvinyl alcohol-type resin is 85-100 mol% normally, Preferably it is 98 mol% or more. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizer. The film formation method of polyvinyl alcohol-type resin is not specifically limited, A well-known method can be used. The film thickness of the raw film is not particularly limited, and may be, for example, 10 to 150 µm.

A polarizer is normally manufactured through the process of uniaxially stretching the above-mentioned polyvinyl alcohol-type film, the process of dyeing and adsorbing with a dichroic dye, the process of treating with boric acid aqueous solution, and the process of washing with water and drying.

The process of uniaxially stretching a polyvinyl alcohol-based film may be performed before dyeing, may be performed simultaneously with dyeing, or may be performed after dyeing. When the uniaxial stretching is performed after dyeing, it may be performed before boric acid treatment, or may be performed during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these multiple steps. For uniaxial stretching, rolls or heat rolls with different circumferential speeds can be used. In addition, uniaxial stretching may be dry stretching extending | stretching in air | atmosphere, and wet extending | stretching extending | stretching in the state swollen with a solvent may be sufficient. The draw ratio is usually 3 to 8 times.

As a process of dyeing a stretched polyvinyl alcohol-type film with a dichroic dye, the method of immersing a polyvinyl alcohol-type film in the aqueous solution containing a dichroic dye can be used, for example. As a dichroic dye, iodine or a dichroic dye is used. In addition, the polyvinyl alcohol-based film is preferably swelled by dipping in water before dyeing.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type film in the dyeing aqueous solution containing iodine and potassium iodide can be used normally. Usually, the content of iodine in the aqueous solution for dyeing is 0.01 to 1 part by weight based on 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight based on 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) is usually 20 to 1,800 seconds.

On the other hand, when using a dichroic organic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type film in the aqueous dyeing solution containing a water-soluble dichroic organic dye can be used normally. The content of the dichroic organic dye in the aqueous solution for dyeing is preferably 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 part by weight based on 100 parts by weight of water. This dyeing aqueous solution may further contain inorganic salts such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution for dyeing is usually 20 to 80 ° C, and the immersion time (dyeing time) is usually 10 to 1,800 seconds.

Boric acid treatment of the dyed polyvinyl alcohol-based film can be carried out by immersing in a boric acid-containing aqueous solution. Usually, the content of boric acid in the aqueous solution containing boric acid is 2 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide, and the content thereof is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight with respect to 100 parts by weight of water. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C, and the immersion time is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably. Preferably it is 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol-based film is usually washed with water and dried. Washing treatment can be performed by immersing the boric acid-treated polyvinyl alcohol-based film in water. The temperature of the water of a washing | cleaning process is 5-40 degreeC normally, and immersion time is 1-120 second normally. A polarizer can be obtained by drying after washing with water. The drying treatment can usually be carried out using a hot air dryer or a far infrared heater. The drying treatment temperature is usually 30 to 100 ° C, preferably 50 to 80 ° C, and the drying time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

The thickness of the polarizer produced as described above is 5 to 40㎛.

Polarizing plate according to the present invention is an acrylic or propylene protective film as shown in Figure 1 (a) as an example; An adhesive layer of an adhesive composition comprising a water-soluble polyamide epoxy clock resin and an acetoacetyl group-modified polyvinyl alcohol-based resin; Polarizer; An adhesive layer of an adhesive composition comprising a water-soluble polyvinyl alcohol-based resin; And it may be laminated in the order of the protective film.

In addition, as an example, as shown in Figure 1 (b) acrylic or propylene-based protective film; An adhesive layer of an adhesive composition comprising a water-soluble polyamide epoxy clock resin and an acetoacetyl group-modified polyvinyl alcohol-based resin; Polarizer; An adhesive layer of an adhesive composition comprising a water-soluble polyamide epoxy clock resin and an acetoacetyl group-modified polyvinyl alcohol-based resin; And it may be laminated in the order of the protective film.

In addition, as an example, as shown in Figure 1 (c) acrylic or propylene-based protective film; An adhesive layer of an adhesive composition comprising a water-soluble polyamide epoxy clock resin and an acetoacetyl group-modified polyvinyl alcohol-based resin; Polarizer; An adhesive layer of an adhesive composition comprising a water-soluble polyamide epoxy clock resin and an acetoacetyl group-modified polyvinyl alcohol-based resin; And it may be laminated in the order of the acrylic or propylene protective film.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

Preparation Example 1 Polarizer Preparation

A 75 μm thick polyvinyl alcohol film having an average degree of polymerization of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched by about 5 times dry, and immersed in water (distilled water) at 60 ° C. for 1 minute while maintaining the stretched state. After immersion for 60 seconds in an aqueous solution of 28 ℃ having a weight ratio of iodine / potassium iodide / distilled water of 0.05 / 5/100. Thereafter, the weight ratio of potassium iodide / boric acid / distilled water was immersed in an aqueous solution of 72 ° C. having 8.5 / 8.5 / 100 for 300 seconds, washed with distilled water at 26 ° C. for 20 seconds, and dried at 65 ° C. to give iodine a PVA film. Adsorbed oriented polarizers were prepared.

Preparation Example 2 Preparation of Protective Film

The triacetyl cellulose film KC8UX (Konica, T) was saponified, and an acrylic film, I-film (Aeon, Japan), a propylene film, Sumitomonoblen W151 (Sumitomo Chemical Co., Ltd.) and Zeonoa (Zeon, Japan) was subjected to a corona discharge treatment of 0.3 to 1.5 kV on each joint surface.

Acrylic Protective Film

Example 1

(1) Preparation of Adhesive Composition

An aqueous solution having a solid content of 10% by weight was prepared by dissolving acetoacetyl group-modified polyvinyl alcohol-based resin (Cosenol Z200, Nippon Synthetic Chemical Co., Ltd.) having a degree of saponification of 99.2 mol% in water (distilled water).

30 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin aqueous solution (solid content) prepared above was mixed with 100 parts by weight of the water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight). . Thereafter, an aqueous KOH solution was added so that the pH of the mixture was 9 to prepare an adhesive composition. The adhesive composition was such that the total solid content was maintained at 10 parts by weight with respect to 100 parts by weight of water (solvent).

(2) Bonding Polarizer and Protective Film (Manufacture of Polarizing Plate)

After applying the adhesive composition on both sides of the polarizer manufactured in Preparation Example 1 so that the dry film thickness is 0.1㎛, the acrylic protective film (Japan Xeon, I-film) was bonded using a nip roll. The bonded polarizing plate was dried in a hot air dryer at 80 ° C. for 5 minutes to prepare a polarizing plate.

Example 2

In the same manner as in Example 1, after applying the adhesive composition on one side of the polarizer, an acrylic protective film (Japan Xeon, I-film) is bonded, the other side is a water-soluble polyvinyl alcohol adhesive composition After coating, a triacetyl cellulose protective film (Konica, KC8UX) was bonded to prepare a polarizing plate.

Example 3

The same procedure as in Example 1 was carried out, but a polarizing plate was prepared by bonding zeanoa (Japan Zeon) with an acrylic protective film on one surface of the polarizer.

Example 4

The same process as in Example 1, except that a pH 11 is applied to the adhesive composition to prepare a polarizing plate.

Example 5

Aqueous acetoacetyl group-modified polyvinyl alcohol-based resin solution (solid content) based on 100 parts by weight of water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight) 5 parts by weight of a mixed adhesive composition was applied to prepare a polarizing plate.

Example 6

Aqueous acetoacetyl group-modified polyvinyl alcohol-based resin solution (solid content) based on 100 parts by weight of water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight) 100 parts by weight of the mixed adhesive composition was applied to prepare a polarizing plate.

Example 7

The same procedure as in Example 1, except that a pH 5 adhesive composition was applied to prepare a polarizing plate.

Example 8

The same procedure as in Example 1, except that a pH 7 adhesive composition was prepared to prepare a polarizing plate.

Example 9

The same procedure as in Example 1 was carried out, but the polarizing plate was prepared by applying an adhesive composition having a pH of 4.

Comparative Example 1

The same process as in Example 1, except that 100 parts by weight of the water (solvent) was applied to the adhesive composition having a total solid content of 1 part by weight to prepare a polarizing plate.

Comparative Example 2

The same procedure as in Example 1, except that 100 parts by weight of water (solvent) was applied to the adhesive composition having a total solid content of 30 parts by weight to prepare a polarizing plate.

Comparative Example 3

Aqueous acetoacetyl group-modified polyvinyl alcohol-based resin solution (solid content) based on 100 parts by weight of water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight) 200 parts by weight of the mixed adhesive composition was applied to prepare a polarizing plate.

Comparative Example 4

Except for the water-soluble polyamide epoxy resin, it was carried out in the same manner as in Example 1, a polarizer was prepared by applying an adhesive composition containing 100 parts by weight of an aqueous solution of acetoacetyl group-modified polyvinyl alcohol-based resin (solid content).

Comparative Example 5

A polarizing plate was prepared in the same manner as in Example 1 except that an adhesive composition containing 100 parts by weight of a water-soluble polyamide epoxy clock resin was applied except for an aqueous solution of acetoacetyl group-modified polyvinyl alcohol-based resin.

Comparative Example 6

Except for the water-soluble polyamide epoxy resin, the same composition as in Example 1, except that 100 parts by weight of an aqueous solution of acetoacetyl-modified polyvinyl alcohol-based resin (solid content) glyoxal is mixed with 10 parts by weight of the adhesive composition To prepare a polarizing plate.

Comparative Example 7

Except for the water-soluble polyamide epoxy resin, the adhesive composition containing glyoxal mixed with 10 parts by weight based on 100 parts by weight of an aqueous solution of acetoacetyl-modified polyvinyl alcohol-based resin (solid content) was applied in the same manner as in Example 2. To prepare a polarizing plate.

Comparative Example 8

In the same manner as in Example 1, a polarizing plate was prepared by applying an adhesive composition using a carboxyl group-modified polyvinyl alcohol-based resin aqueous solution (Kurare, KL-318) in place of the acetoacetyl group-modified polyvinyl alcohol-based resin aqueous solution. .

Table 1 below shows the composition and physical properties of the adhesive composition prepared in Examples 1 to 9 and Comparative Examples 1 to 8.

TABLE 1

Propylene protective film

Example 10

(1) Preparation of Adhesive Composition

An aqueous solution having a solid content of 10% by weight was prepared by dissolving acetoacetyl group-modified polyvinyl alcohol-based resin (Cosenol Z200, Nippon Synthetic Chemical Co., Ltd.) having a degree of saponification of 99.2 mol% in water (distilled water).

30 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin aqueous solution (solid content) prepared above was mixed with 100 parts by weight of the water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight). . Thereafter, an aqueous KOH solution was added so that the pH of the mixture was 9 to prepare an adhesive composition. The adhesive composition was such that the total solid content was maintained at 10 parts by weight with respect to 100 parts by weight of water (solvent).

(2) Bonding Polarizer and Protective Film (Manufacture of Polarizing Plate)

After applying the adhesive composition on both sides of the polarizer prepared in Preparation Example 1 so that the dry film thickness is 0.1㎛, propylene-based protective film (Sumitomo Co., Ltd., Sumitomonoblen W151) was bonded using a nip roll. . The bonded polarizing plate was dried in a hot air dryer at 80 ° C. for 5 minutes to prepare a polarizing plate.

Example 11

In the same manner as in Example 10, after applying the adhesive composition on one side of the polarizer, a propylene-based protective film (Sumitomo Co., Ltd., Sumitomonoblen W151) is bonded, the other side water-soluble polyvinyl alcohol After applying the adhesive composition, a triacetyl cellulose protective film (Konica, KC8UX) was bonded to prepare a polarizing plate.

Example 12

In the same manner as in Example 10, after applying the adhesive composition on one side of the polarizer, a propylene-based protective film (Sumitomo Co., Ltd., Sumitomonoblen W151) is bonded, the other side water-soluble polyvinyl alcohol After applying the adhesive composition, an acrylic protective film (Xeon, Japan Zeona) was bonded to prepare a polarizing plate.

Example 13

The same procedure as in Example 10, except that a pH 5 adhesive composition was applied to prepare a polarizing plate.

Example 14

The same procedure as in Example 10, except that a pH 12 adhesive composition was applied to prepare a polarizing plate.

Example 15

Aqueous acetoacetyl group-modified polyvinyl alcohol-based resin solution (solid content) based on 100 parts by weight of water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight) 5 parts by weight of a mixed adhesive composition was applied to prepare a polarizing plate.

Example 16

Aqueous acetoacetyl group-modified polyvinyl alcohol-based resin solution (solid content) based on 100 parts by weight of water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight) 100 parts by weight of the mixture was mixed, and an adhesive composition having a pH of 11 was applied to prepare a polarizing plate.

Example 17

The same procedure as in Example 10, except that a pH 7 adhesive composition was applied to prepare a polarizing plate.

Example 18

The same procedure as in Example 10, except that a pH 11 is applied to the adhesive composition to prepare a polarizing plate.

Comparative Example 9

Aqueous acetoacetyl group-modified polyvinyl alcohol-based resin solution (solid content) based on 100 parts by weight of water-soluble polyamide epoxy clock resin (SR-650, Sumitomo Chemical Co., Ltd., 30% by weight) 200 parts by weight of the mixed adhesive composition was applied to prepare a polarizing plate.

Comparative Example 10

The same procedure as in Example 10, except that a pH 4 adhesive composition was applied to prepare a polarizing plate.

Comparative Example 11

A polarizing plate was prepared in the same manner as in Example 10, except that the water-soluble polyamide epoxy clock resin was coated with an adhesive composition containing 100 parts by weight of an aqueous solution of acetoacetyl group-modified polyvinyl alcohol-based resin (solid content).

Comparative Example 12

A polarizing plate was prepared in the same manner as in Example 10 except that an adhesive composition containing 100 parts by weight of a water-soluble polyamide epoxy clock resin was applied except for an aqueous solution of acetoacetyl-modified polyvinyl alcohol-based resin.

Comparative Example 13

Example 10, except that the water-soluble polyamide epoxy resin, except for 100 parts by weight of the aqueous solution of acetoacetyl-modified polyvinyl alcohol-based resin (solids content) to apply an adhesive composition containing glyoxal 10 parts by weight To prepare a polarizing plate.

Comparative Example 14

Except for the water-soluble polyamide epoxy resin, the adhesive composition containing glyoxal mixed with 10 parts by weight of 100 parts by weight of an aqueous solution of acetoacetyl-modified polyvinyl alcohol-based resin (solid content) was applied in the same manner as in Example 11. To prepare a polarizing plate.

Comparative Example 15

In the same manner as in Example 10, a polarizing plate was prepared by applying an adhesive composition using a carboxyl group-modified polyvinyl alcohol-based resin solution (Kurare, KL-318) in place of the aqueous solution of acetoacetyl group-modified polyvinyl alcohol-based resin. .

Table 2 below shows the composition and physical properties of the adhesive composition prepared in Examples 10 to 18 and Comparative Examples 9 to 15.

TABLE 2

Test Example

The physical properties of the adhesive compositions and polarizing plates prepared in Examples 1 to 18 and Comparative Examples 1 to 15 were measured by the following methods, and the results are shown in Tables 3 and 4 below.

(1) Adhesive force (cutter evaluation)

After leaving the prepared polarizing plate at room temperature for 1 hour, a cutter blade was placed between each film (between the polarizer and the polarizer protective film) of the polarizing plate, and the method of entering the blade when pushing the blade was evaluated by the following criteria. .

(Double-circle): The blade of a cutter does not enter between any films.

(Circle): When pushing on a blade, it stops when a blade enters 1-2 mm between at least one film.

(Triangle | delta): When pushing on a blade, it stops when a blade enters 3-5 mm between at least one film.

X: When pushing on a blade, a blade enters in between at least one film.

 (2) hot water resistance

The prepared polarizing plate was allowed to stand for 24 hours in an environment of 23 ° C. and a relative humidity of 55%, and then hot water resistance was tested. First, the polarizing plate was cut | disconnected in the rectangular shape of 5 cm x 2 cm, with the absorption axis (extension direction) of a polarizing plate as a long side, the sample was produced, and the dimension of the long side direction was measured correctly. Here, the sample exhibits a unique color uniformly over the entire surface due to iodine adsorbed to the polarizer. As shown in FIG. 2, (A) shows that the short side of the sample 1 is gripped by the gripper 5 before being immersed in warm water, and (B) shows that the gripped sample 1 It is a figure of the shrinked sample 4 after immersing about 80% of the longitudinal direction in the 60 degreeC hot water bath, and holding it for 4 hours. After the immersion is completed, the sample 4 is taken out of the water bath to wipe off moisture, and the shrinkage of the polarizer is measured. Specifically, the distance from the end 1a of the protective film in the center of the short side of the sample 1 to the end of the contracted polarizer 4 was measured, which was defined as the shrinkage length. In addition, in FIG. 2B, the polarizer 4 positioned in the middle of the polarizing plate contracts by hot water immersion, and a region 2 in which the polarizer 4 does not exist is formed between the two protective films. Further, by immersion of hot water, iodine elutes from the periphery of the polarizer 4 in contact with the warm water, whereby a portion 3 in which the color is missing is formed in the periphery of the sample 1. This discoloration degree was measured from the end of the contracted polarizer 4 at the center of the short side of the sample 1 to the region in which the color peculiar to the polarizing plate remained, which was defined as the iodine missing length. The total length of the shrinkage length and the iodine omission length was defined as the total erosion length X. That is, the total erosion length X is unique to the polarizing plate from the end 1a of the sample 1 at the center of the short side of the sample 1. The distance to the area where the color remains. It can be judged that the smaller the shrinkage length, iodine elimination length, and total erosion length X, the higher the adhesion (hot water resistance) in the presence of water.

◎: total erosion length (X) <1 mm

○: 1 mm ≤ total erosion length (X) <2 mm

△: 2 mm ≤ total erosion length (X) <5 mm

× 5 mm ≤ total erosion length (X)

(3) polarization degree

The polarization degree (Py) of the prepared polarizing plate was measured by using an ultraviolet visible spectrophotometer (V-7100 / VAP-7070, manufactured by Nippon Bunco Co., Ltd.) to measure the parallel transmittance (H ₀ ) and the orthogonal transmittance (H ₉₀ ) of the polarizing plate. After that, it was calculated based on the following Equation 1, and evaluated based on the following criteria. The transmittance | permeability is the Y value which corrected visibility by the 2 degree visual field (C light source) prescribed | regulated to JISZ 8701 (1982 edition).

[Equation]

Polarization degree (Py,%) = {(H ₀ -H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100

TABLE 3

As shown in Table 3, the first adhesive layer (water-soluble polyamide epoxy resin and acetoacetyl group-modified polyvinyl alcohol-based resin) laminated on one side of the polarizer according to the present invention, the acrylic protective film laminated on the adhesive layer It could be confirmed that the polarizing plate containing was excellent in adhesiveness and hot water resistance even under high temperature and high humidity conditions.

On the other hand, Comparative Example 1, which has a low total solid content of the adhesive composition, has low adhesiveness, and Comparative Example 2, which has a high content, has poor application such as uneven adhesion surface. In Comparative Example 3 having a high content of acetoacetyl group-modified polyvinyl alcohol-based resin, adhesiveness was lowered. In Comparative Example 4 in which the water-soluble polyamide epoxy resin was not used, the adhesiveness and the hot water resistance were lowered. In Comparative Example 5, in which the acetoacetyl group-modified polyvinyl alcohol-based resin was not used, the hot water resistance was lowered. In Comparative Examples 6 and 7 in which glyoxal was used instead of the water-soluble polyamide epoxy clock resin, the adhesiveness and the hot water resistance were lowered. In addition, in Comparative Example 8 using a carboxyl group-modified polyvinyl alcohol-based resin, adhesiveness and hot water resistance were lowered.

TABLE 4

As shown in Table 4, the first adhesive layer (water-soluble polyamide epoxy resin and acetoacetyl group-modified polyvinyl alcohol-based resin) laminated on one side of the polarizer according to the present invention, the propylene-based protective layer laminated on the adhesive layer It was confirmed that the polarizing plate including the film was excellent in adhesiveness and hot water resistance even under high temperature and high humidity conditions.

In Comparative Example 9 having a high content of acetoacetyl group-modified polyvinyl alcohol-based resin and Comparative Example 10 having a pH of the adhesive composition of about 4, adhesiveness was lowered. In Comparative Example 11 in which the water-soluble polyamide epoxy resin was not used, the adhesiveness and the hot water resistance were lowered. In Comparative Example 12 in which the acetoacetyl group-modified polyvinyl alcohol-based resin was not used, the hot water resistance was lowered. In Comparative Examples 13 and 14 in which glyoxal was used instead of the water-soluble polyamide epoxy clock resin, the adhesiveness and the hot water resistance were lowered. In addition, in Comparative Example 15 using a carboxyl group-modified polyvinyl alcohol-based resin, adhesiveness and hot water resistance were lowered.

Claims (10)

1. A polarizing plate comprising 1 to 100 parts by weight (based on solids content) of an acetoacetyl group-modified polyvinyl alcohol-based resin based on 100 parts by weight of a water-soluble polyamide epoxy clock resin, and comprising an adhesive composition having an pH of 5 or more.
2. The polarizing plate of claim 1, wherein the adhesive layer is made of an adhesive composition having a pH of 9 to 12.
3. The polarizing plate of claim 1, wherein the adhesive layer is made of an adhesive composition having a solid content of 3 to 20 parts by weight based on 100 parts by weight of a solvent.
4. The polarizing plate of claim 1, wherein the polarizing plate comprises a polarizer, an adhesive layer laminated on one surface of the polarizer, and an acrylic or propylene protective film laminated on the adhesive layer.
5. The polarizing plate according to claim 4, wherein the polarizing plate is further laminated with an acrylic, cellulose, polyolefin or polyester protective film on the other side of the polarizer by the adhesive composition.
6. The polarizing plate according to claim 4, wherein an acrylic, cellulose, polyolefin or polyester protective film is further laminated by an adhesive layer containing a water-soluble polyvinyl alcohol-based resin on the other side of the polarizer.
7. The polarizing plate according to claim 1, wherein the acetoacetyl group-modified polyvinyl alcohol-based resin includes 1 to 50 parts by weight (based on solids content) based on 100 parts by weight of the water-soluble polyamide epoxy resin.
8. The polarizing plate of claim 4, wherein the acrylic or propylene protective film surface laminated on the adhesive layer is treated by at least one method selected from the group consisting of corona, plasma, and primer.
9. The polarizing plate of claim 1, wherein the adhesive composition comprises a basic compound.
10. A liquid crystal display device comprising the polarizing plate of claim 1.

Images