KR20100068178A - Polarizing plate and liquid crystal display device comprising the same - Google Patents

Abstract

PURPOSE: A polarizing plate and a liquid crystal display device including the same are provided to highly improve adhesion between a polarizer and a polyester-based polarizer protective film by forming a primer layer, including a urethane resin. CONSTITUTION: A primer layer(12) is formed between a polarizer(13) and a polyester-based polarizer protective film(11). A cellulose-based polarizer protective film(14) is stacked on the other side of the polarizer. The primer layer includes a polyester-based urethane resin and a heat reactive water-soluble urethane resin. The adhesive side of the primer layer is processed with a dry-surface treatment.

Description

POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY DEVICE COMPRISING THE SAME}

The present invention relates to a polarizing plate having excellent adhesion between the polarizer and the polyester-based polarizer protective film, as well as improved durability and wettability, and a liquid crystal display device having the polarizing plate.

The polarizing plate is an optical component used in various image display devices such as liquid crystal display devices, and is usually a polyvinyl alcohol (PVA) polarizer and the polarizer, which are elongated in a fixed direction and adsorbed and oriented with an iodine compound or a dichroic polarizing material. Consists of laminated polarizer protective film to protect both sides of the. In addition, a surface treatment layer such as a hard coating layer, an antiglare layer, an antireflection layer, a low reflection layer, an antistatic layer, and the like is further laminated on the polarizer protective film in order to visually sense the polarizing plate used on the viewing side of the image display apparatus.

Among them, a cellulose-based film such as triacetyl cellulose (TAC) having excellent optical properties is mainly used as a polarizer protective film, but it is relatively expensive to manufacture such a cellulose-based film, which leads to a low cost and smoothness of raw materials. There was a problem with supply and demand. In addition, in the case of bonding the cellulose-based film and the polarizer using the water-based adhesive, the process is complicated because a safing step must be performed before the bonding step in order to improve the adhesion thereof.

In order to solve this problem, the supply and demand of raw materials as a polarizer protective film is easier than other protective films, and since it is a product used for general purposes in industrial and industrial use, it can be easily manufactured by a conventional manufacturing method, and thus it can be manufactured at about 1/3 the price of a cellulose-based film. It has been proposed to use polyester films which can be supplied, in particular polyethylene terephthalate films. However, even when the polyester-based film and the polarizer are bonded using the water-based adhesive, the desired adhesion is not realized and there is a difficulty in manufacturing the polarizing plate.

Japanese Laid-Open Patent Publication No. 2003-119305 uses an optically easy-adhesive layer film having a coating layer comprising a polyester resin and an acrylic resin having a glass transition temperature (Tg) of -50 to 50 ° C on one side of a polyester resin. To improve adhesion to the substrate. In addition, Japanese Patent Laid-Open No. 1996-271733 and Korean Patent Laid-Open No. 2008-0043309 each disclose a film having a primer layer made of polyvinyl alcohol resin or an easy adhesive layer made of cellulose resin on one side of a polyester film. A method of facilitating bonding by the water-based adhesive of the polyester film and the polarizer is disclosed. Further, Japanese Laid-Open Patent Publication No. 2002-365432 discloses a method of improving adhesion by arranging a protective film on both sides of a polarizer in manufacturing a polarizing plate, and applying a polyvinyl alcohol-based adhesive therebetween.

Although the adhesion between the polarizer and the polarizer protective film was improved to some extent by the above method, the adhesion was still insufficient to obtain physical properties such as durability and wettability of a desired level.

The present invention aims to provide a polarizing plate that greatly improves the adhesion between them even when bonding the polarizer and the polyester-based polarizer protective film using an aqueous adhesive when manufacturing the polarizing plate, and improves durability and wettability.

In addition, another object of the present invention is to provide a liquid crystal display device having the polarizing plate.

In order to achieve the above object, the present invention provides a polarizing plate formed with a primer layer comprising a polyester-based urethane resin and a heat-reactive water-soluble urethane resin between the polarizer and the polyester-based polarizer protective film.

In addition, the present invention provides a liquid crystal display device having the polarizing plate on at least one side of the liquid crystal cell.

According to the present invention, by using a polyester-based film instead of the expensive cellulose-based film mainly used as a conventional polarizer protective film, the polarizer and the cellulose-based polarizer protective film must be passed in order to improve adhesion when bonding with an aqueous adhesive. By omitting the saponification process, the manufacturing process of the polarizing plate can be simplified and the manufacturing cost can be reduced, and the adhesiveness between the polarizer and the polyester film using the water-based adhesive is excellent as well as the durability and the wettability resistance between them. It is possible to provide a greatly improved polarizing plate.

The present invention relates to a polarizing plate having excellent adhesion between the polarizer and the polarizer protective film, and greatly improving durability and wettability, and a liquid crystal display device having the polarizing plate.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The polarizing plate of the present invention is characterized in that a primer layer comprising a polyester-based urethane resin and a heat-reactive water-soluble urethane resin is formed between the polarizer and the polyester-based polarizer protective film.

As shown in FIG. 1, in the polarizing plate according to the exemplary embodiment, a primer layer 12 is formed between the polarizer 13 and the polyester-based polarizer protective film 11, and the other of the polarizer 13 is formed. It is a polarizing plate of the structure in which the normal polarizer protective film 14 is laminated | stacked on the surface.

The polyester-based polarizer protective film 11 on the side where the primer layer 12 is formed is a polarizer protective film used in place of the expensive cellulose-based polarizer protective film used as a conventional polarizer protective film.

The polyester polarizer protective film 11 may be polymerized after esterification of terephthalate acid (TPA) and ethylene glycol (EG), or dimethyl terephthalate (DMT) and ethylene glycol. It is a polyester film which consists of resin manufactured by the method of polycondensation after esterification.

As the polyester film, a film made of a resin such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate or polybutylene terephthalate may be used, and preferably, a polyethylene terephthalate film is used.

The polyester film may be an unstretched, uniaxial or biaxially stretched film after melt extrusion of a polyester resin using a conventional method.

The polyester film may have a thickness of 10 to 500 μm, preferably 25 to 300 μm.

The primer layer 12 is formed between the polyester polarizer protective film 11 and the polarizer 13, and is a layer bonded to the polarizer 13 through an adhesive layer (not shown). In particular, when the PVA-based polarizer and the polyester-based film is bonded by the water-based adhesive, as a layer to further improve the adhesion between them to increase the adhesive force, a polyester-based urethane resin and a heat-reactive water-soluble urethane resin It is formed from the composition for forming a primer layer comprising a.

In addition, the primer layer 12 may be formed on the other side of the polyester-based polarizer protective film 11 as well as between the polyester-based polarizer protective film 11 and the polarizer 13.

The polyester urethane resin is prepared by polymerizing 2-hydroxymethyl-2-methyl-5-hydroxypropionic acid, 2-hydroxyethyl-2-ethyl-5-hydroxypropionic acid or a mixture thereof and a diisocyanate compound. The polyester component manufactured by copolymerizing a polyurethane component, a dicarboxylic acid, and a glycol compound is resin copolymerized by the normal polymerization method. The polyurethane component and the polyester component may be copolymerized in a weight ratio of 10:90 to 90:10, preferably in a weight ratio of 20:80 to 30:70. In the weight ratio range, the polyester-based urethane resin may have excellent bonding property with the polyester-based polarizer protective film, thereby improving adhesion between the polarizer and the polyester-based polarizer protective film.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,5-methylcarboxylic acid, and dimethylisophthalic acid; Alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and the like; And aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and the like, and may be used. Preferably, aromatic dicarboxylic acids are used.

The glycol compound may be ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentylglycol, 1,6-hexanediol, 1,2-cyclohexanemethanol, 1,3 Cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylene glycol, diethylene glycol, triethylene glycol, polyether glycol, polyethylene glycol and polytetramethylene glycol may be used. Preferably, ethylene glycol is used.

Examples of the diisocyanate compound include 2,4-hexamethylene diisocyanate, 2,6-hexamethylene diisocyanate, 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane, and these One or more selected from among derivatives may be used. Preferably, 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane and its derivatives are preferably used.

The thermally reactive water-soluble urethane resin reacts a polyester-based polyol with a polyisocyanate compound to produce a prepolymer composed of isocyanate groups at both ends, and reacts the prepolymer with bisulfite in water to form isocyanate groups at bisulfite. It is a resin having a blocked structure. In such a thermally reactive water-soluble urethane resin, bisulfite at both ends is dissociated by heat treatment, and an isocyanate group is regenerated. Through this, when bonding the polarizer and the polyester-based polarizer protective film by the water-based adhesive, sufficient curing is made by the reaction of the reactor containing the isocyanate group of the primer layer and active hydrogen of the water-based adhesive, the polarizer and the polyester-based polarizer protective film Can improve the adhesion.

The polyester-based polyol may be at least one selected from aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, phthalic acid, maleic acid, phthalic acid or adipic acid, ethylene glycol, diethylene glycol, propylene glycol, tetramethylene glycol, Those prepared by one or more condensation reactions selected from aliphatic diols such as pentamethylene glycol, hexamethylene glycol, neopentyl glycol, and the like can be used. It is preferable to use those prepared by the condensation reaction of phthalic acid or adipic acid with ethylene glycol.

Examples of the polyisocyanate compound include at least one selected from toluene diisocyanate, xylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate and trimethylhexamethylene diisocyanate. Can be used.

The bisulfite may be used at least one selected from sodium bisulfite, potassium bisulfite and ammonium bisulfite.

The polyester-based urethane resin and the heat-reactive water-soluble urethane resin can be used after being adjusted to an appropriate solid content by dispersing in water or a cosolvent of water and alcohol.

The weight ratio of the polyester-based urethane resin and the heat-reactive water-soluble urethane resin is 1: 2 to 5: 1, more preferably 1: 1 to 3: 1 polyester-based polarizer protective film 11 and the primer layer ( It is preferable at the point that adhesiveness with 12) and the blocking resistance of the polyester-based polarizer protective film 11 can be improved.

The composition for forming a primer layer together with the urethane mixed resin component as described above may include a resin component, particulates or nonionic surfactants, etc. which are commonly used according to required physical properties and uses. Specific examples of the resin component include acrylic resins, urethane resins, thermoplastic resins such as polyester resins, and thermosetting resins such as melamine resins, and among them, the coating film strength of the primer layer can be realized and the polyester film can be used. Melamine type thermosetting resin is preferable at the point which can improve adhesiveness. As the fine particles, silica-based colloids, alumina-based colloids, etc. may be mentioned as inert particles having an average particle size of less than 2 µm, preferably 10 to 300 nm. In addition, the kind of nonionic surfactant is not particularly limited, and may include kerylbenzenesulfonate, polypropylenebenzenesulfonate, sulfuric acid ester of stearic acid or sulfuric acid ester of resinol acid, and the like.

The primer layer 12 preferably has a thickness of 50 to 1,000 nm after drying in that the transmittance loss can be reduced in consideration of the optical characteristics of the polarizing plate.

In the present invention, the primer layer 12 may be a dry surface treated layer. In particular, it is preferable that the surface joined with the polarizer 13 is dry surface treated among both surfaces of the primer layer 12.

Dry surface treatment is a treatment usually carried out in order to activate the surface of the resin such as a film, coating layer, etc., for example, in addition to the discharge treatment such as corona discharge treatment, glow discharge treatment, plasma discharge treatment, flame treatment, ozone treatment, ultraviolet ray Known methods such as irradiation treatment, ionizing radiation treatment, roughening treatment and the like can be given. More specifically, the corona discharge treatment is a method of applying a high voltage to an electrode to generate corona discharge and activating a film disposed on the discharge surface. The corona discharge treatment can obtain an optimal result by changing the type of electrode, the distance between the electrode and the film, the voltage to be applied, the moving speed of the film to be processed, the output of the corona discharge, and the like. Plasma discharge treatment is a method of irradiating a surface of the resin with a plasma such as an inert gas or oxygen gas generated under reduced pressure or atmospheric pressure and activating the surface thereof, and an atmospheric pressure plasma discharge treatment is preferable in view of simplicity of operation and cost of the processing apparatus. . This plasma discharge treatment can treat the surface in various ways by varying the type of gas. In addition, ozone treatment is a method of activating the surface of the resin by exposure to ozone, and ultraviolet irradiation treatment is a method of activating the surface of the resin by irradiating ultraviolet rays, for example, an ultraviolet light source such as a hydrogen discharge tube, a xenon discharge tube, a mercury lamp, and a laser. The method of irradiating the ultraviolet-ray about wavelength 150-400 nm about 5 to 60 minutes using this can be used. Among these methods, corona discharge treatment is particularly preferable in view of ease of handling and excellent stability of quality after treatment.

In the case of dry surface treatment of the primer layer 12 by the corona discharge treatment, for example, the output of the corona discharge may be up to about 2 kW, preferably, in consideration of safety, it is preferably 1.5 kW or less, more preferably a primer. In order to eliminate the possibility of deterioration or coloring of the layer 12, if possible, it is good that it is 1.2 kPa or less. In addition, it is preferable that the moving speed of the primer layer 12 is 3-50 m / min, and it can also process by passing the primer layer 12 repeatedly through a corona discharge area | region for the uniform corona treatment of the surface. In addition, the amount of corona discharge is preferably 1,500 to 5,000 J / m 2.

As such, when the primer layer 12 is dry surface treated, the surface energy is increased and the contact angle with respect to the water-based adhesive becomes low. When the primer layer 12 is bonded to the polarizer 13 using the water-based adhesive, the surface of the primer layer 12 is The spreadability of the water-based adhesive can be improved and the adhesion between the polarizer 13 and the primer layer 12 can be further improved.

The dry surface-treated surface of the primer layer 12 preferably has a surface energy of 60 mN / m or more, more preferably 60 to 80 mN / m. Moreover, it is preferable that the contact angle with respect to an aqueous adhesive agent is 50 degrees or less, More preferably, it is 15-50 degrees. When it has such a characteristic, sufficient adhesive improvement effect will be acquired.

The polarizer 13 is an optical film which converts incident natural light into a desired single polarization state (linear polarization state), and a dichroic dye adsorbed or oriented to a film of polyvinyl alcohol-based resin can be used.

The polyvinyl alcohol-based resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate-based resin. As an example of 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, unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamide which has an ammonium group, etc. are mentioned, for example. The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may also be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used.

A polarizer is manufactured through the process of uniaxially stretching a film of such polyvinyl alcohol-based resin, dyeing with a dichroic dye to adsorb the dichroic dye, treating with an aqueous boric acid solution, and washing with water.

The polarizer protective film 14 is a film laminated on the other side of the polarizer 13, it is possible to use a conventional protective film excellent in transparency, mechanical strength, thermal stability, moisture shielding, isotropy and the like. For example, Cellulose-type films, such as diacetyl cellulose and a triacetyl cellulose; Polycarbonate film; Acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene films such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based films such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefins, ethylene propylene copolymers; Vinyl chloride film; Amide films such as nylon and aromatic polyamides; Imide film; Polyether sulfone-based film; Sulfone film; Polyethyl ketone film; Vinyl alcohol film; Polyoxymethylene film; An epoxy film etc. are mentioned, Among these, a cellulose film like triacetyl cellulose is preferable in consideration of polarization characteristics, durability, etc.

As a method of forming the primer layer 12 between the polyester polarizer protective film 11 and the polarizer 13, after forming the primer layer 12 on the polyester polarizer protective film 11, The method of bonding the primer layer 12 and the polarizer 13 using an adhesive agent can be used.

First, the method of forming the primer layer 12 on the polyester polarizer protective film 11 is not particularly limited as long as it is a method commonly used in the art. For example, the composition for forming a primer layer on at least one surface of the polyester-based polarizer protective film 11 is air knife, gravure, reverse roll, kiss roll, The primer layer 12 may be laminated by developing by directly applying the coating method using a bar coater, a mayer bar, or the like, followed by drying. In addition, the dried primer layer 12 may be subjected to a surface treatment using a dry surface treatment method as described above.

The polarizing plate may be manufactured by bonding the primer layer 12 and the polarizer 13 and the polarizer 13 and the polarizer protective film 14 formed or formed as described above through a water-based adhesive.

The water-based adhesive is not particularly limited as long as it can sufficiently bond the primer layer, the polarizer, and the polarizer protective film, and has excellent optical transparency and no change in yellowing over time, for example, polyvinyl alcohol-based resin and a crosslinking agent. The adhesive composition containing these is mentioned.

Examples of the polyvinyl alcohol-based resin included in the adhesive composition include a polyvinyl alcohol resin or a polyvinyl alcohol resin having an acetoacetyl group. Among them, the polyvinyl alcohol resin having an acetoacetyl group has a highly reactive functional group, It is preferable at the point which improves durability.

The polyvinyl alcohol-based resin is polyvinyl alcohol obtained by saponifying polyvinyl acetate and derivatives thereof; Saponified copolymers of vinyl acetate with copolymers having a copolymerizability; And modified polyvinyl alcohols obtained by acetalization, urethaneization, etherification, graftting and phosphate esterification of polyvinyl alcohols, and these may be used alone or in combination of two or more thereof. As a monomer which has the said copolymerizability, Unsaturated carboxylic acid, such as maleic anhydride, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and its ester; Α-olefins such as ethylene and propylene, (meth) allyl sulfonic acid (soda), sulfonic acid sodium (monoalkyl maleate), disulfonic acid sodium alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N- Vinylpyrrolidone, N-vinylpyrrolidone derivatives, and the like. The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but considering the adhesiveness, the average degree of polymerization is about 100 to 5,000, preferably 1,000 to 4,000, and the average degree of saponification is 85 to 100 mol%, preferably 90 to 100 mol%.

In addition, the polyvinyl alcohol-based resin containing the acetoacetyl group can be obtained by reacting the polyvinyl alcohol-based resin and diketene (diketene) by a known method. For example, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid and then adding diketene thereto, or dissolving the polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane beforehand It can obtain by the method of adding ten, or the method of directly contacting a diketene gas or a liquid diketene with polyvinyl alcohol. The polyvinyl alcohol-based resin containing acetoacetyl group 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 It is good that it is 2-7 mol%. When the degree of modification of the acetoacetyl group is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient and is inappropriate. If the degree of modification of the acetoacetyl group exceeds 40 mol%, the effect of improving the water resistance may be insignificant.

In the polarizing plate of the present invention, the polyester-based polarizer protective film 11 and the primer layer 12 may be applied to any surface based on the polarizer 13, but it is necessarily applied to only one side of the polarizer 13. desirable. When the polyester-based polarizer protective film 11 and the primer layer 12 are applied to both surfaces of the polarizer in the polarizing plate to which the water-based adhesive is applied, moisture is not evaporated during the thermosetting process so that the polyester-based polarizer protective film 11 ), And sufficient adhesion between the polarizer 13 and the polarizer 13 is not realized, and the polarizer 13 is damaged by moisture, and as a result, the initial excellent physical properties in polarization degree and transmittance decrease.

In the present invention, the functional surface treatment layer 15 may be further laminated on one surface of the polarizing plate. 2 and 3, the functional surface treatment layer 15 may be laminated on the polyester polarizer protective film 11 or may be laminated on the polarizer protective film 14.

The functional surface treatment layer 15 may be one or more layers selected from a hard coat layer, an antireflection layer, a low reflection layer, an antistatic layer, and an antiglare layer. In more detail, the hard coating layer is a layer for preventing cracks or damage from occurring on the surface of the polarizing plate, and is formed using an ultraviolet curable resin such as acrylic or silicone, and serves as a cured coating having excellent hardness and slip properties. The anti-reflection layer is for preventing external light from being reflected on the surface of the polarizing plate to hinder the visibility of transmitted light, and is a layer composed of a metal oxide thin film formed by a deposition or sputtering method. The low reflection layer is a layer formed from a coating liquid containing a low refractive index material. The antistatic layer is for preventing dust adhesion due to static electricity and the like and is a layer formed of an ultraviolet curable resin containing an antistatic agent. In addition, an anti-glare layer is a layer which formed fine unevenness | corrugation on the surface by roughening by sandblasting, embossing, etc., or application | coating of the coating liquid which contains transparent fine particles.

In the present invention, as shown in FIG. 4, the pressure-sensitive adhesive layer 16 and the release film 17 for bonding to the liquid crystal cell on the other surface where the functional surface treatment layer 15 is not formed are sequentially shown as shown in FIG. 4. It may be stacked.

The adhesive layer 16 is a layer formed from the adhesive composition containing an adhesive resin, a crosslinking agent, and a silane coupling agent.

As the pressure-sensitive adhesive resin, acrylic, silicone, rubber, urethane, polyester or epoxy copolymers can be used, and preferably acrylic copolymers are used.

As the acrylic pressure sensitive adhesive resin, a copolymer of a monomer having a functional group capable of crosslinking with a (meth) acrylate monomer having 1 to 14 carbon atoms of an alkyl group may be used as the acrylic copolymer.

Specific examples of the (meth) acrylate monomer having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate , n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl ( Meta) acrylate, n-tetradecyl (meth) acrylate, pentafluorooctylacrylate, 6- (1-naphthyloxy) -1-hexyl acrylate, and the like, and these may be used alone or in combination of two or more thereof. Can be used. The (meth) acrylate monomer having 1 to 14 carbon atoms is preferably included in an amount of 50 to 99% by weight based on the total monomer content (100% by weight) used to prepare the acrylic copolymer.

The monomer having a crosslinkable functional group reacts with a crosslinking agent to impart cohesive force or adhesive strength by chemical bonding so that cohesive force breakdown of the pressure sensitive adhesive does not occur under high temperature or humidity conditions. For example, a sulfonic acid group-containing monomer and a phosphate group Containing monomers, cyano group-containing monomers, vinyl esters, aromatic vinyl compounds, carboxyl group-containing monomers, acid anhydride group-containing monomers, hydroxy group-containing monomers, amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, epoxy group-containing monomers and ether groups A containing monomer etc. can be used and these can be used individually or in combination of 2 or more types. The monomer having a crosslinkable functional group is preferably included in an amount of 1 to 50% by weight based on the total monomer content (100% by weight) used for preparing the acrylic copolymer.

The acrylic copolymer composed of the above components can be prepared by conventional methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization and emulsion polymerization, and preferably by solution polymerization.

The acrylic copolymer has a weight average molecular weight (polystyrene equivalent) measured by gel permeation chromatography (GPC) method is usually 50,000 to 2,000,000, preferably 100,000 to 1,800,000, more preferably 500,000 to 1,500,000 to be.

The crosslinking agent is used to reinforce the cohesive force of the pressure-sensitive adhesive composition by appropriately crosslinking the acrylic pressure-sensitive adhesive resin, an isocyanate compound, an epoxy compound, a melamine-based resin, an aziridine-based compound, and the like may be used, and preferably an isocyanate compound or an epoxy compound is used. Can be used. These can be used individually or in combination of 2 or more types. The crosslinking agent is preferably included in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the acrylic adhesive resin (based on the solid content).

Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3 -Mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- Aminopropyl trimethoxysilane, 3-chloropropyl trimethoxysilane, etc. are mentioned, These can be used individually or in combination of 2 or more types. The silane coupling agent may be included in an amount of 0.005 to 5 parts by weight based on 100 parts by weight of the acrylic adhesive resin (based on the solid content).

The pressure-sensitive adhesive composition containing the above components, if necessary, in order to adjust the adhesive force, cohesion, viscosity, elastic modulus, glass transition temperature, antistatic property, etc. of the pressure-sensitive adhesive, tackifying resin, antioxidant, dye, pigment, antifoaming agent, caustic agent It may further include additives such as fillers, antistatic agents or light stabilizers.

The release film 17 is a film for protecting the pressure-sensitive adhesive layer, and if the film is commonly used in the art, its kind is not particularly limited. Specific examples include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethylacrylic Polyolefin type films, such as a rate copolymer and an ethylene-vinyl alcohol copolymer; Polyester-based films such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polyamide films such as polyacrylate, polystyrene, nylon 6 and partially aromatic polyamide; Polyvinyl chloride film; Polyvinylidene chloride film; Or polycarbonate films. These may be those which have been appropriately released by a release agent such as silicon-based, fluorine-based or silica powder.

In addition, the polarizing plate of the present invention may further be a surface protective film (not shown) for protecting the polarizing plate.

The surface protection film is a film in which an adhesive layer is formed on a base film.

The base film of the surface protection film is preferably a polyester film having sufficient strength to protect the polarizing plate and excellent transparency and not deteriorating optical properties, and these may be unstretched, uniaxially or biaxially stretched. have. The thickness of the base film is not particularly limited, but is preferably 6 to 200 μm, more preferably 20 to 100 μm. If the thickness is less than 6 μm, sufficient strength as the surface protection film may not be imparted. If the thickness is more than 200 μm, the thickness may be poor in handling during the production of the polarizing plate. In addition, the base film may be added with additives such as various stabilizers, ultraviolet absorbers, aggregates, antioxidants or plasticizers as necessary.

The pressure-sensitive adhesive layer of the surface protection film is formed from the pressure-sensitive adhesive, the type of pressure-sensitive adhesive is not particularly limited as long as it is commonly used in the art, acrylic, natural or synthetic rubber, silicone-based pressure-sensitive adhesive can be used. Among these, an acrylic pressure-sensitive adhesive having a weight average molecular weight of about 200,000 to 2,500,000 is preferable in terms of excellent transparency. The acrylic pressure-sensitive adhesive is based on acrylate ester monomers such as butyl acrylate, ethyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate alone or a mixture of two or more thereof, and carboxyl group, hydroxyl group, amino group, epoxy group, etc. Containing polar monomers such as methacrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate At least one selected from among may be a copolymerized resin.

The liquid crystal display of the present invention is characterized in that the polarizing plate is provided on at least one side of the liquid crystal cell.

In the present invention, the liquid crystal display device is well known to those skilled in the art of the present invention, and thus, detailed description of each configuration is omitted.

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.

Example 1

(1) PET film with a primer layer

The polyethylene terephthalate (PET) resin is cast through a T-die at about 280 ° C using a conventional method, and then stretched about 2-5 times in a longitudinal direction at 70-100 ° C to have a thickness of about A film having a thickness of 50 μm was obtained. A primer layer-forming composition comprising a polyester-based urethane resin and a heat-reactive water-soluble urethane resin (weight ratio of 2: 1) was applied onto the PET film by using a bar coater to have a thickness of 4-5 μm before drying. Then, the film was stretched 2-5 times in the transverse direction at 100-120 ° C., and then a PET film (SH40 manufactured by SKC) with a primer layer formed at 200-260 ° C. was obtained.

(2) Preparation of Polarizing Plate

A PVA film having a thickness of about 70 µm was dyed and stretched in an aqueous solution containing iodine and potassium iodide, crosslinked on an aqueous solution containing boric acid and potassium iodide, washed with water and dried to obtain a PVA polarizer having a thickness of about 30 µm.

A TAC film having a thickness of about 80 μm was bonded to one side of the PVA polarizer using a PVA-based water-based adhesive, and on the other side of the PVA polarizer, the primer layer and the polarizer of the PET film having the primer layer prepared in (1) were formed. Was bonded using an aqueous adhesive and then dried at 80 ° C. for 5 minutes. In addition, a pressure sensitive adhesive sheet having an acrylic pressure sensitive adhesive layer having a thickness of about 25 μm on a PET release film treated with a silicone release agent is laminated on a TAC film, and a PET surface protective film is bonded onto a PET film on which the pressure sensitive adhesive sheet is not laminated. Was prepared.

Example 2

In the same manner as in Example 1, (2) the surface of the primer layer of the PET film on which the primer layer was formed during the manufacturing of the polarizing plate was subjected to dry surface treatment using a corona discharge treatment. At this time, the corona discharge treatment was carried out under the condition that the discharge amount of 3,200J / ㎡ with an output of 0.8-1.2㎾.

Example 3

In the same manner as in Example 1, (2) the surface of the primer layer of the PET film on which the primer layer was formed during the manufacturing of the polarizing plate was subjected to dry surface treatment using a corona discharge treatment. At this time, the corona discharge treatment was carried out under the condition that the discharge amount of 2,100J / ㎡ with an output of 0.8-1.2㎾.

Comparative Example 1

In the same manner as in Example 1, but did not form a primer layer in (1) was used only PET film.

Comparative Example 2

In the same manner as in Example 1, (1) in the formation of the primer layer, instead of the polyester-based urethane resin and the heat-reactive water-soluble urethane resin, an aqueous dispersion acrylic resin was used.

Comparative Example 3

In the same manner as in Example 1, (1) a polyurethane-based resin was used in place of the polyester-based urethane resin and the heat-reactive water-soluble urethane resin in forming the primer layer.

Comparative Example 4

In the same manner as in Example 1, but (1) copolymerized polyethylene terephthalate resin was used instead of the polyester-based urethane resin and the heat-reactive water-soluble urethane resin when forming the primer layer.

Comparative Example 5

In the same manner as in Example 1, only the PET film was used without forming a primer layer in (1), and (2) the surface of the PET film bonded to the polarizer during the manufacture of the polarizing plate was subjected to corona discharge treatment.

Reference Example 1

It carried out similarly to Example 1, but did not use the PET film in which the primer layer of (1) was formed, and (2) TAC film was used for both surfaces of the polarizer at the time of manufacture of a polarizing plate.

division Polarizer
Protective film Primer layer ingredient Corona Discharge Treatment
(Discharge amount) Example 1 PET Polyester-based PU /
Thermal Reaction Water Soluble Urethane - Example 2 PET Polyester PU / Heat Resistant Urethane ○
(3,200J / ㎡) Example 3 PET Polyester PU / Heat Resistant Urethane ○
(2,100J / ㎡) Comparative Example 1 PET - - Comparative Example 2 PET Dispersion AC - Comparative Example 3 PET PU - Comparative Example 4 PET Co-PET - Comparative Example 5 PET /
Surface treatment - - Reference Example 1 TAC - -

Test Example

The physical properties of the polarizing plates prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2 below.

* Contact angle (°), surface energy (mN / m)

A drop shape analyzer (DSA100, KRUSS) was used, and the test solution was measured based on water and diiomethane (CH ₂ I ₂ ).

* Adhesion test

(1) Cutter evaluation: After making a scratch on the PET polarizer protective film of a polarizing plate using a cutter, the peeling degree of the interface between a PET polarizer protective film and a polarizer was observed and evaluated based on the following criteria.

(Circle): There is no peeling in an interface.

(Triangle | delta): Peeling at an interface generate | occur | produces to 1-10 mm (it is necessary to judge whether a product application is possible).

X: Peeling at an interface exceeds 10 mm (processing with NG).

(2) Fold evaluation: Cut out a 10 mm size scratch on the PET polarizer protective film of the polarizing plate using a cutter, fold the polarizing plate around the part, and observe the mixing of bubbles in the folded part, based on the following criteria. Evaluated.

(Circle): It cuts without bubble mixing.

(Triangle | delta): The mixing of bubbles generate | occur | produces to 1-10 mm (it is necessary to judge whether a product application is possible).

X: The mixing of bubbles exceeded 10 mm (treated with NG).

* Wet Resistance Test

The polarizing plate was cut into a size of 25 mm × 100 mm and eroded in warm water at 60 ° C. for 30 minutes, and then the shrinkage length and the degree of color fading of the polarizer were measured. Calculated.

* Durability Test

The polarizing plate was cut into a size of 100 mm × 100 mm, the release film of the pressure sensitive adhesive sheet was peeled off, and then bonded to soda glass. The conjugates were treated in an autoclave at 50 ° C. under 5 atmospheres for 20 minutes and then subjected to durability evaluation. At this time, heat resistance at 80 ℃, moisture heat resistance at 60 ℃, relative humidity 90%, cold resistance at -40 ℃ after each treatment for about 750 hours, and observed the peeling between the PET protective film and the polarizer, based on the following criteria Evaluated.

(Circle): No peeling (good or OK).

X: Exfoliation exists (defective, NG).

division Contact angle
(°) Surface energy
(mN / m) Adhesion Wet Resistance
(Mm) durability cutter
evaluation Folded
evaluation Heat resistant Heat resistance Cold Example 1 65.0 51.8 △ ○ 1.1 ○ ○ ○ Example 2 39.7 64.5 ○ ○ 0.7 ○ ○ ○ Example 3 47.1 61.8 ○ ○ 0.8 ○ ○ ○ Comparative Example 1 - - ○ × Not rated - - - Comparative Example 2 - - × × Not rated - - - Comparative Example 3 - - × ○ 2.1 × × ○ Comparative Example 4 - - × ○ 2.5 × × ○ Comparative Example 5 - - ○ × Not rated - - - Reference Example 1 20.1 73.9 ○ ○ 1.4 ○ ○ ○

As shown in Table 2, the polarizing plates of Examples 1 to 3 having a primer layer comprising a polyester-based polyurethane resin and a heat-reactive water-soluble urethane resin are formed between the polarizer and the polyester-based polarizer protective film according to the present invention. As compared with the polarizing plates of Comparative Examples 1 to 5, it was confirmed that not only the adhesion between the polarizer and the polyester polarizer protective film, but also the moisture resistance, heat resistance, heat resistance, heat resistance, and cold resistance were excellent. In particular, the polarizing plates of Examples 2 and 3, in which the bonding surface with the polarizer of the primer layer was dry surface treated, improved contact angle and surface energy characteristics, thereby improving adhesion and wettability. This resulted in the saponification process for improving the adhesion between the polarizer and the TAC film, with results equivalent to or higher than those in Reference Example 1 using the cellulose-based film (TAC film) with better contact angle and surface energy properties. By omitting the process, PET film, which can be supplied at a price of about one third of the TAC film, can be used to reduce the manufacturing cost of the polarizer.

1 to 4 are cross-sectional views of polarizing plates according to embodiments of the present invention, respectively.

Explanation of symbols on the main parts of the drawings

11: polyester-based film (PET film) 12: primer layer

13: polarizer 14: polarizer protective film (TAC film)

15: functional surface treatment layer 16: adhesive layer

17: release film

Claims (12)

A polarizing plate having a primer layer comprising a polyester-based urethane resin and a heat-reactive water-soluble urethane resin between the polarizer and the polyester-based polarizer protective film. The polarizing plate according to claim 1, wherein the polarizer and the primer layer are bonded through an aqueous adhesive. The polarizing plate according to claim 1, wherein the primer layer is a dry surface treated surface of the polarizer and the bonding surface. The polarizing plate according to claim 3, wherein the dry surface treatment is a corona discharge treatment. The polarizing plate of Claim 3 whose discharge amount of a corona discharge process is 1,500-5,000J / m <2>. The polarizing plate of claim 3, wherein the dry surface-treated surface of the primer layer has a surface energy of 60 mN / m or more and a contact angle with respect to the water-based adhesive of 50 ° or less. The film according to claim 1, wherein the polyester film, the cellulose film, the polycarbonate film, the acrylic film, the styrene film, the polyolefin film, the vinyl chloride film, or the amide film on the other side of the polarizer on which the primer layer is not formed. And a polarizer protective film laminated with a polarizer protective film selected from an imide film, a polyether sulfone film, a sulfone film, a polyethyl ketone film, a vinyl alcohol film, a polyoxymethylene film or an epoxy film. The polarizing plate according to claim 1, wherein the functional surface treatment layer is laminated on the polyester film. The polarizing plate according to claim 1, wherein the weight ratio of the polyester-based urethane resin and the heat-reactive water-soluble urethane resin is 1: 2 to 5: 1. The polarizing plate according to claim 1, wherein the polyester-based urethane resin is a resin in which a polyurethane component and a polyester component are copolymerized in a weight ratio of 10:90 to 90:10. The polarizing plate according to claim 1, wherein the heat-reactive water-soluble urethane resin is a resin composed of an isocyanate group blocked at both ends by bisulfite obtained by reacting a polyester-based polyol with a polyisocyanate. A liquid crystal display device comprising the polarizing plate of any one of claims 1 to 11 on at least one side of a liquid crystal cell.

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