KR101463844B1 - Polarizing plate and image display device comprising the same - Google Patents

Abstract

The present invention relates to a polarizing plate and an image display device including the same and, more specifically. to a polarizing plate in which a water-based adhesive composition containing a polyallylamine resin, a cross linker, and alcohol is disposed and cured between a polarizer and a protective film. When the polarizing plate is wound on a cylindrical rod having a cross-section of a circle with a circumference of 10πmm in the direction of where a crack is exposed to the outside and folded in half after generating the crack in the protective film, the length of an air bubble mixture between an adhesive layer and the protective film is within 1mm, thereby the polarizing plate has excellent adhesion and air bubble mixture preventing capability.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate and an image display apparatus having the polarizing plate, and more particularly, to a polarizing plate having an adhesive layer excellent in adhesion between a polarizer and a protective film and an image display apparatus having the polarizing plate.

Polarizing plates used in various image display devices such as a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display (PDP), a field emission display (FED) and an OLED are generally made of polyvinyl alcohol alcohol, PVA) film comprises a polarizer in which an iodine compound or a dichroic polarizing material is adsorbed and oriented, a polarizer protective film is laminated on one side of the polarizer, and a polarizer protective film, a liquid crystal cell Layer structure in which a pressure-sensitive adhesive layer and a release film are laminated in this order.

2. Description of the Related Art In recent years, various types of image display devices have become larger and larger, and accordingly polarizers and polarizing plates used are also becoming larger. Therefore, the handling becomes more disadvantageous in the handling process in the process, and the amount of deformation generated under repeated high temperature and low temperature environments during use is further increased, and a polarizer excellent in durability is required.

The polarizer and the protective film are bonded by an adhesive interposed therebetween. When the adhesion between the polarizer and the protective film is poor, deformation may occur during handling or use during processing, and air bubbles may enter the inside.

However, PMMA having excellent hardness in addition to TAC or COP, which is conventionally used as a protective film, has been introduced under the conditions of high temperature and high humidity, and it is difficult to introduce a reactive group onto the surface of PMMA than TAC or COP. There is a problem of deterioration.

Korean Patent No. 0888572 discloses a water-based adhesive for a polarizing plate containing a polyvinyl alcohol-based resin containing an acetoacetyl group and a cross-linking agent, but the problem of still lowering the adhesive strength has not been sufficiently solved.

Patent Document 1: Korean Patent No. 0888572

The present invention provides a polarizing plate produced by using an aqueous adhesive composition excellent in adhesion and water resistance.

Further, the present invention provides a polarizing plate in which the problem of bubble entrainment does not occur at the time of bending.

Further, the present invention provides an image display apparatus including the polarizing plate.

1. A polarizing plate comprising a water-based adhesive composition comprising a polyallylamine resin, a crosslinking agent and an alcohol interposed between a polarizer and a protective film and cured,

The polarizing plate is wound around a cylindrical bar having a circular cross section with a circumference of 10 [pi] m around the periphery of the polarizing plate in a direction in which the crack is exposed to the outside and folds in half to form a protective film, Wherein a bubble inclusion length between protective films is within 1 mm.

2. The polarizer according to 1 above, wherein the polyallylamine-based resin has a weight average molecular weight of 1,000 to 70,000.

3. The composition according to 1 above, wherein the crosslinking agent is selected from the group consisting of an isocyanate compound, an epoxy compound, a peroxide compound, a metal chelate compound, an oxazolane compound, a melamine compound, a glyoxylate compound and an aziridine compound At least one polarizer.

4. The polarizer of claim 3, wherein the aziridine compound is opened to form a hydrogen bond with the hydroxyl group on the surface of the polarizer.

5. The aziridine compound according to item 3 above, wherein the aziridine compound is selected from the group consisting of trimethylolpropanetri [3- (1-aziridinyl) prionate], trimethylolpropanetris (2-methyl-1-aziridinepropionate) 1- (2-cyanoethyl) aziridine, 1- (benzylsulfonyl) aziridine, 1- (P- Tosyl) aziridine, and 1-phenylmethanesulfonyl aziridine.

6. The polarizing plate according to item 1, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, t-butanol and glycerol.

7. The polarizer according to 1 above, wherein the protective film is an acrylic resin protective film.

8. An image display device comprising the polarizing plate of any one of items 1 to 7 above.

The polarizing plate of the present invention is provided with a polarizer and a protective film with an aqueous adhesive layer excellent in adhesion and water resistance and excellent in the ability to prevent air bubbles.

The water-based adhesive of the present invention includes a crosslinking agent, and particularly when an aziridine compound crosslinking agent is used, it forms a hydrogen bond with a polarizer and has a better adhesive force and a bubble-entrapping ability.

The water based adhesive of the present invention exhibits an anchoring effect with a protective film including an alcohol. In particular, when an acrylic resin is used as a protective film, an amide bond with polyallylamine is formed, thereby providing excellent adhesion and bubble immersion preventing ability.

The present invention relates to a polarizing plate in which an aqueous adhesive composition comprising a polyallylamine resin, a crosslinking agent and an alcohol is interposed between a polarizer and a protective film and cured, wherein the polarizing plate generates a crack in the protective film, When the polarizing plate is wound on a cylindrical rod having a circular cross section having a circle circumference of 10 pi mm in the direction of exposing the polarizing plate in a direction in which the polarizing plate is folded in half so that the bubble inclusion length is within 1 mm between the adhesive layer and the protective film, And an image display device having the same.

Hereinafter, the present invention will be described in more detail.

In the polarizing plate of the present invention, the adhesive composition interposed between the polarizer and the protective film is an aqueous adhesive containing a polyallylamine resin, a crosslinking agent and an alcohol.

The polyallylamine-based resin is not particularly limited as long as it is a polyallylamine-based resin used in the art, and can be classified into a primary amine, a secondary amine, and a tertiary amine resin. Considering the adhesive force with the protective film, Amine resin is preferable. In addition, a homopolymer or copolymer may be used as the primary amine resin.

The kind of the polyallylamine-based resin according to the present invention is not particularly limited, but examples thereof include allylamine homopolymer resin, allylamine / dimethylallylamine copolymer resin, diallyl / dimethylammonium chloride / acrylamide copolymer resin, These may be used alone or in combination of two or more. Considering the physical properties such as adhesion and durability, it is preferable that the polymer is a homopolymer of polyallylamine.

A specific example of the polyallylamine-based resin may be a resin having a repeating unit represented by the following formula (1).

[Chemical Formula 1]

PAA-05, PAA-08, PAA-15C, PAA-25C, PAA-H-10C, PAA-01C, and PAA-01 of Nitto Bosa, which are commercially available as the polyallylamine- 15C, PAA-HCl-10S, and the like.

The weight average molecular weight of the polyallylamine resin according to the present invention is not particularly limited, but is preferably 1,000 to 70,000 in order to exhibit high adhesion between the polarizer and the protective film. When the weight average molecular weight is less than 1,000, it is difficult to obtain the desired adhesion. When the weight average molecular weight is more than 70,000, bubbles may be incorporated during the bonding process of the polarizer and the protective film.

The crosslinking agent serves to improve the adhesion and durability of the polyallylamine-based resin, the polarizer and the protective film, to maintain reliability at a high temperature, and to maintain the shape of the adhesive.

The crosslinking agent may be used alone or as a mixture of two or more of isocyanate compound, epoxy compound, peroxide compound, metal chelate compound, oxazolane compound, melamine compound, glyoxylate compound and aziridine compound have. Among them, an aziridine compound which is advantageous from the viewpoint of improvement in adhesiveness and durability is preferable.

The present invention specifically describes the aziridine-based compound crosslinking agent, which is a preferable crosslinking agent component, but the present invention is not limited thereto.

The aziridine compound can react with an aziridine functional group and a reactive group such as a hydrophilic group on the surface of the polarizer, and the adhesive composition containing the same can lower the surface energy of the film and is excellent in wettability to a nonpolar film such as an acrylic resin film. Therefore, even a film having a relatively smooth surface and a low surface energy can have high adhesion properties. Also, the aziridine compound crosslinking agent may be ring-opened to form a hydrophilic group, and the hydrophilic group may be hydrogen bonded to the hydroxy group on the surface of the optical film such as a polarizer. For this reason, the aziridine compound crosslinking agent can provide excellent adhesion. Further, the compound having a multifunctional aziridine improves the agglomeration effect in the adhesive layer to improve the blocking ability of bubble inclusion, and can exhibit improved water resistance.

The aziridine compound may be at least one selected from the group consisting of trimethylolpropane-tris- (beta-N-aziridinyl) propionate, trimethylolpropane tri [3- (1-aziridinyl) prionate], trimethylolpropane tris Methyl-1-aziridine propionate), 2- methyl aziridine, lithium L-aziridine-2-carboxylate, N-tosyl aziridine, 1- (2- cyanoethyl) aziridine, 1- Benzylsulfonyl) aziridine, 1- (P-tosyl) aziridine, 1-phenylmethanesulfonyl aziridine, etc. may be used alone or as a mixture of two or more thereof. In view of the solubility in water, trimethylolpropane tris (2-methyl-1-aziridine propionate) and trimethylolpropane tri [3- (1-aziridinyl) prionate] Propane tris (2-methyl-1-aziridine propionate) is more preferable.

The crosslinking agent may be contained in an amount of 3 to 25 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the polyallylamine resin (based on the solid content). When the content is less than 3 parts by weight, the water resistance of the polarizing plate is not sufficiently exhibited. When the content exceeds 25 parts by weight, there is a problem that the optical characteristics (transmittance and polarization degree) of the polarizing plate are lowered.

The alcohol used as an additive dissolves the surface of the protective film to penetrate the surface of the protective film to improve the adhesive strength and the ability to prevent air bubbles, which is particularly effective when the protective film is formed of an acrylic resin.

Further, when polymethylmethacrylate (PMMA) is used as the protective film in the acrylic resin film, the alcohol can form an amide bond between the amine group of the polyarylamine resin and the PMMA by forming the base environment, But it is possible to remarkably improve the intelligence of the air bubble intrusion.

In addition, alcohol has an excellent wetting property against an acrylic resin film and also has a leveling agent effect.

Examples of usable alcohols include methanol, ethanol, propanol, isopropanol, butanol, t-butanol, glycerol, etc. These solvents may be used alone or in admixture of two or more.

The alcohol may be contained in an appropriate amount so that the bubble entrainment length described later satisfies the range of the present invention. For example, 140 to 300 parts by weight, preferably 160 to 250 parts by weight, based on 100 parts by weight of the polyallylamine resin (based on the solid content). When the content is less than 140 parts by weight, the ability of the polarizing plate to prevent the incorporation of air bubbles may not be sufficiently manifested. When the content exceeds 300 parts by weight, gelation may occur.

The waterborne adhesive composition according to the present invention may contain additives such as a plasticizer, a silane coupling agent, an antistatic agent, a fine particle and a leveling agent, a basic substance, etc., which are generally used in the art within the range not hindering the object of the present invention Based on the total weight of the composition.

The water-based adhesive composition according to the present invention is preferably a liquid type in order to form a uniform adhesive layer on the surface of the polarizer or the protective film as the adherend. Such a liquid type adhesive may be a solution type or a dispersed liquid type of various solvents, and a solution type is preferable in view of the coated surface of the substrate, and a solution type or a dispersed liquid type in which water is used as a solvent is suitable in view of stability. Water may be included in an amount that is not particularly limited within the range that the adhesive composition has an appropriate viscosity in consideration of the coating property and the stability.

The thickness to which the adhesive composition is applied (before drying) is usually about 0.01 to 10 mu m, preferably 0.05 to 5 mu m, and most preferably 0.1 to 1 mu m. The thickness of the adhesive layer after drying is usually 0.001 to 5 mu m, preferably 0.01 to 2 mu m, more preferably 0.01 to 1 mu m. If the thickness of the adhesive layer exceeds 5 탆, the problem of appearance defects of the polarizing plate tends to occur.

In addition, the present invention provides a separate parameter capable of quantifying the bubble entrapment intelligence.

Specifically, when the polarizing plate of the present invention is formed into a cylindrical bar having a circular cross section with a circumference of 10 π mm in the direction in which the crack is exposed to the outside after the crack is generated in the protective film, the polarizing plate is folded in half, And the bubble entrainment length between the protective films is within 1 mm.

The bubble entrainment length means the length from the point where cracks are generated on the surface of the protective film to the farthest point of the bubble entrained portion.

If the bubble entrainment length exceeds 1 mm, the adhesive bonding the protective film and the polarizer may be detached due to an impact or force exerted from the outside when handling or using the polarizer, so that bubbles may be mixed.

The thickness of the polarizing plate protective film is not particularly limited because the polarizing plate of the present invention needs only to have a bubble entrapment length of 1 mm or less. The protective film may have an appropriate thickness if it has a bubble entrapment length in the above range.

The polarizer used in the polarizing plate of the present invention may be a polarizer commonly used in the art which is produced according to a process including swelling, dyeing, crosslinking, stretching, washing and drying of a polyvinyl alcohol film. The order and condition of each step is not particularly limited, and the boric acid content, drying temperature, time, etc. of the crosslinking bath may be appropriately adjusted so as to have the surface water contact angle.

The polyvinyl alcohol-based resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include acrylamide monomers having an unsaturated carboxylic acid type, an unsaturated sulfonic acid type, an olefin type, a vinyl ether type, and an ammonium group. The polyvinyl alcohol resin may also be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polymerization degree of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

Such a polyvinyl alcohol-based resin film is used as the original film of the polarizer. The method of forming the film of the polyvinyl alcohol-based resin is not particularly limited, and a known method can be used. The thickness of the original film is not particularly limited, and may be, for example, 10 to 150 mu m.

In the swelling step, the polyvinyl alcohol film is dipped in a swelling tank filled with an aqueous solution for swelling before dyeing to remove impurities such as dust and anti-blocking agent deposited on the surface of the polyvinyl alcohol film, and a polyvinyl alcohol film Is a step for improving physical properties of the polarizer by swelling to improve the drawing efficiency and to prevent uneven dyeing.

Water (pure water, deionized water) can usually be used as a swelling aqueous solution, and when a small amount of glycerin or potassium iodide is added thereto, the swelling of the polymer film and the processability can be improved.

The content of glycerin and potassium iodide is not particularly limited and may be, for example, 5 wt% or less and 10 wt% or less, respectively, in the total weight of the aqueous swelling solution.

The temperature of the swelling bath is not particularly limited, and may be, for example, 20 to 70 캜, preferably 25 to 55 캜. When the temperature of the swelling bath is 20 to 70 캜, the stretching and dyeing efficiency is excellent thereafter, and expansion of the film due to excessive swelling can be prevented.

The execution time (swelling bath immersion time) of the swelling step is not particularly limited, and may be, for example, 180 seconds or less, preferably 90 seconds or less. It is possible to prevent excessive swelling and saturation when the immersion time is 180 seconds or less, to prevent breakage due to softening of the polyvinyl alcohol film and to improve the polarization degree by making the adsorption of iodine uniform during the dyeing step have.

The swelling step is performed as needed, and can be omitted.

The dyeing step is a step of immersing the polyvinyl alcohol film in a dyeing bath filled with an aqueous solution for dyeing containing a dichroic substance, for example, iodine to adsorb iodine on the polyvinyl alcohol film.

The dyeing aqueous solution may comprise water, a water-soluble organic solvent or a mixed solvent thereof and iodine. The content of iodine may be 0.01 to 1 part by weight based on 100 parts by weight of water.

The dyeing aqueous solution may further contain iodide as a solubilizing aid for improving the dyeing efficiency.

The kind of iodide is not particularly limited and includes, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide and the like , And potassium iodide is preferred in view of high solubility in water. These may be used alone or in combination of two or more.

The content of iodide is not particularly limited and may be, for example, 0.5 to 20 parts by weight based on 100 parts by weight of water.

As the dichroic material, a dichroic dye may also be used. In this case, the dichroic dye may be contained in an amount of 1 * 10 ^-4 to 10 parts by weight, preferably 1 * 10 ^-3 to 1 part by weight, .

The temperature of the dye bath is not particularly limited and may be, for example, 5 to 45 캜, and preferably 10 to 35 캜.

The immersing time of the polyvinyl alcohol film in the dyeing tank is not particularly limited and may be, for example, 20 seconds to 30 minutes, preferably 2 to 10 minutes.

The crosslinking step is a step of immobilizing the adsorbed iodine molecules by immersing the dyed polyvinyl alcohol film in a crosslinking aqueous solution so that the dyeability due to physically adsorbed iodine molecules is not lowered by the external environment. Although dichroic dyes are not often eluted in a humidity environment, iodine molecules often dissolve or sublimate depending on the environment when the crosslinking reaction is unstable, and sufficient crosslinking reaction is required.

The aqueous solution for crosslinking may further comprise water as a solvent and a boron compound such as boric acid or sodium borate, and may further comprise an organic solvent mutually soluble with water.

The boron compound imparts rigidity to the polyvinyl alcohol film to suppress the occurrence of wrinkles in the process, thereby improving handleability and forming iodine orientation.

The content of the boron compound is not particularly limited and may be, for example, 2 to 15 parts by weight, and preferably 5 to 12 parts by weight based on 100 parts by weight of water.

The aqueous crosslinking solution may further contain a small amount of iodide to obtain the uniformity of the degree of polarization in the plane of the polarizer.

The iodide may be the same as that used in the dyeing step.

The content of iodide is not particularly limited and may be, for example, 0.1 to 15 parts by weight, and preferably 5 to 12 parts by weight based on 100 parts by weight of water. If the content of iodide is less than 0.1 parts by weight with respect to 100 parts by weight of water, the iodide ions in the film may escape to increase the transmittance and change the color of the polarizer. If the content of iodide is more than 15 parts by weight, Can be reduced.

The temperature of the crosslinking bath is not particularly limited and may be, for example, 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

The immersion time of the polyvinyl alcohol film in the crosslinking bath may be 60 seconds to 1,200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds.

The order of the stretching step is not particularly limited, and may be performed before, after, or after the dyeing step, and may be performed simultaneously with at least one step selected from the group consisting of a swelling step, a dyeing step and a crosslinking step .

The stretching ratio of the stretching step is not particularly limited, and may be, for example, such that the cumulative stretching ratio is 4 to 8 times. When the cumulative stretching ratio is within the above range, the effect of improving the durability of the polarizer can be maximized. In the present specification, "cumulative stretching ratio" represents the value of the product of the stretching ratio at each step.

The water washing step is a step of immersing the crosslinked and drawn polyvinyl alcohol film in a water bath filled with water for washing to remove unnecessary residues such as boric acid attached to the polyvinyl alcohol film in the previous steps.

The aqueous solution for washing may be water (deionized water).

The temperature of the water bath is not particularly limited and can be, for example, 5 to 60 ° C, and preferably 10 to 40 ° C.

The immersing time of the polyvinyl alcohol film in the water bath may be 1 to 120 seconds.

The wash step may be performed each time previous steps such as dyeing step, crosslinking step or stretching step are completed. The number of iterations may be one or more times, and the number of iterations is not particularly limited.

The drying step is a step of drying the washed polyvinyl alcohol film and further improving the orientation of molecules of iodine dissolved in the neck by the drying, thereby obtaining a polarizer excellent in optical characteristics.

Examples of the drying method include natural drying, air drying, heat drying, far-infrared drying, microwave drying, hot air drying and the like.

The drying temperature is not particularly limited and can be, for example, 30 to 100 ° C, preferably 50 to 80 ° C.

The drying time is not particularly limited and can be suitably performed so that the polarizer can be sufficiently dried, and can be performed, for example, for 1 to 10 minutes, preferably for 2 to 10 minutes.

The thickness of the polarizer manufactured through the above process may be 5 to 40 탆.

The protective film is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc., and is not specifically proposed. Specifically, an acrylic film, a cellulose film, a polyolefin film or a polyester film can be used.

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-based resins such as diacetyl cellulose and triacetyl cellulose; Polyolefin-based resins such as polyethylene, polypropylene, cyclo-based or norbornene structures, and ethylene-propylene copolymers; And the like.

The thickness of the protective film is preferably 10 to 200 占 퐉, and more preferably 10 to 150 占 퐉. Further, when the polarizer protective film is laminated on both sides of the polarizer, the same or different thickness can be maintained.

The protective film may be subjected to surface treatment if necessary. The surface treatment is carried out in order to facilitate bonding with the polarizer. For example, the surface treatment is carried out by dry treatment such as primer treatment, plasma treatment, corona treatment, chemical treatment such as alkali treatment (saponification treatment) Coating treatment and the like. The surface of the protective film not bonded to the polarizer may be subjected to a treatment for hard coat treatment, antireflection treatment, anti-sticking, diffusion or anti-glare treatment.

The polarizing plate of the present invention is excellent in adhesion to a polarizer irrespective of the kind of the protective film and the presence or absence of the surface treatment treatment. In particular, the present invention relates to a protective film (for example, an uncured cellulose-based protective film) on which chemical treatment such as alkali treatment (saponification treatment) is not performed, an acrylic or propylene- Excellent adhesion to protective film.

When the polarizer and the protective film are prepared, the protective film is bonded to at least one surface of the polarizer using the above-mentioned adhesive composition. The bonding method may be a conventional method in the art. For example, the bonding method may be applied to the bonding surface of the polarizer or the protective film using a flexible method, a Meyer bar coating method, a gravure coating method, a die coating method, a dip coating method, A method of applying the adhesive composition, and then bonding them together. The flexographic method is a method in which the polarizer or protective film is moved in a generally vertical direction, a horizontal direction, or an inclined direction between the two, while applying the adhesive composition to the joint surface. After applying the adhesive composition, a polarizer or a protective film is put on a nip roll or the like and bonded.

After bonding the polarizer and the protective film, a drying treatment can be carried out. The drying treatment is carried out, for example, by spraying hot air. The drying temperature is suitably selected in the range of 40 to 100 占 폚, preferably 60 to 100 占 폚. The drying time may be about 20 to 1,200 seconds. After drying, it is preferable to cure at a room temperature or a slightly higher temperature, for example, at a temperature of 20 to 50 DEG C for about 12 to 600 hours. The thickness of the adhesive layer after drying is usually 0.001 to 5 mu m, preferably 0.01 to 2 mu m, more preferably 0.01 to 1 mu m or less. If the thickness of the adhesive layer exceeds 5 탆, the problem of appearance defects of the polarizing plate tends to occur.

A surface treatment layer such as a hard coating layer, an antireflection layer, an antiglare layer, and an antistatic layer may be further laminated on the other side of the polarizer to which the polarizer protective film is bonded on one side. Further, an optical functional film may be further laminated by a pressure-sensitive adhesive layer. Examples of the optically functional film include an optical compensation film in which a liquid crystal compound or a polymer compound thereof is oriented on the surface of a base material, an optical compensation film that transmits polarized light of any kind and reflects polarized light of a property opposite to that, A retardation film including a cyclic polyolefin resin, an antireflection functional film having a concavo-convex shape on its surface, an additional film having a surface antireflection treatment, a reflection film having a reflective function on the surface, And a transflective film having both a reflecting function and a transmitting function.

The polarizing plate of the present invention can be provided in a manner embedded in an image display apparatus. The image display apparatus is not particularly limited as long as it is a device using a polarizing plate. For example, a liquid crystal display (LCD) of a reflection type, a transmission type and a transflective type and a liquid crystal display of various types such as TN type, STN type, OCB type, HAN type, VA type, A liquid crystal display (LCD) of a driving type can be exemplified. In addition to this, it is preferable to use an image display device such as a plasma display device (PDP), a field emission device (FED), an organic light emitting diode device, an inorganic light emitting diode device, Can be used.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Manufacturing example  : Polarizer  Produce

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

Example  One

(1) Adhesive composition

5 parts by weight of aziridine crosslinking agent (PZ-33, available from Nippon Catalyst Co., Ltd.) and 200 parts by weight of ethanol were added to 100 parts by weight (solids content) of an aqueous solution of polyallylamine resin having a weight average molecular weight of 1,000 To prepare an adhesive composition.

(2) Polarizer

The adhesive composition of the above (1) was coated on both sides of the polarizer on which the iodine adsorption orientation of the production example was oriented so as to have a dry film thickness of 0.1 mu m, and then the protective film was bonded using niprol. And then dried in a hot-air dryer at 80 ° C for 5 minutes to prepare a polarizing plate.

The protective film was prepared by using a saponified triacetyl cellulose protective film on one side and an acrylic protective film corona-treated on the other side.

Example  2 to 8 and Comparative Example  1 to 5

A polarizing plate was prepared in the same manner as in Example 1 except that the composition of the components was used as shown in Table 1 below.

After the produced polarizing plate was made into a specimen having a length of 20 cm in the MD direction, a length of 2.5 cm in the MD vertical direction and a thickness of 160 탆, a crack was generated in the protective film, The bubble inclusion length between the adhesive layer and the protective film was measured when the film was rolled up on a cylindrical bar having a circular cross section with a circumference of 10? Mm and folded in half, and the results are shown in Table 1 below.

division
(Parts by weight) Binder resin Cross-linking agent (content) Alcohol
(content) Bubble inclusion length Type (content) Mw Example 1 PAA-01 (100) 1,000 PZ-33 (5) Ethanol (200) 0.8mm Example 2 PAA-08 (100) 8,000 PZ-33 (5) Isopropanol (200) 0.7mm Example 3 PAA-15C (100) 15,000 CX-100 (5) The methanol (200) 0.6mm Example 4 PAA-25C (100) 25,000 CX-100 (5) Ethanol (200) 0.7mm Example 5 PAA-H-10C (100) 60,000 PZ-33 (5) The methanol (200) 0.4mm Example 6 PAA-25C (100) 25,000 CL-422 (10) Methanol (100) 0.9mm Example 7 PAA-25C (100) 25,000 CL-422 (10) Methanol (140) 0.6mm Example 8 PAA-25C (100) 25,000 CL-422 (10) Methanol (300) 0.4mm Comparative Example 1 Polyvinyl alcohol resin
(100) - Sodium glyoxylate (5) - 3mm or more Comparative Example 2 KCA101L (100) - CX-100 (5) - 3mm or more Comparative Example 3 KCA101L (100) - Sodium glyoxylate (5) - 3mm or more Comparative Example 4 KCA101L (100) - NaOH (5) - 3mm or more Comparative Example 5 PAA-15C (100) 15,000 CX-100 (5) - 3mm or more PAA-05C, PAA-15C, PAA-15C, PAA-25C, PAA-H-10C and PAA-15C (Nitobosa)

Polyvinyl alcohol resin: Acetoacetyl group-modified polyvinyl alcohol resin (Kosenol Z200, Nippon Synthetic Chemical Industry Co., Ltd.)

KCA101L: epichlorohydrin-modified methyldiallylamine resin (Senka Co., Ltd.)

CX-100: Trimethylpropane tris (2-methyl-1-aziridinepropionate) (DSM)

PZ-33: Pentaerythritol-tris- (? - (N-aziridinyl) propionate (Japan Catalysts)

CL-422: Trimethylolpropane-tris- (β-N-aziridinyl) propionate (VF-Chemtech)

Experimental Example

(1) Evaluation of adhesion

The polarizers prepared in Examples and Comparative Examples were allowed to stand at room temperature for 1 hour, and then the adhesiveness between the polarizer and the protective film was evaluated to such an extent that the blades were inserted when the blade of the cutter was pushed between the polarizer and the protective film.

◎: The cutter blade does not enter between the polarizer and the protective film.

○: The cutter blade enters 2 mm or less between the polarizer and the protective film

DELTA: The blade of the cutter enters between 2 mm and 5 mm or less between the polarizer and at least one protective film

X: The blade of the cutter enters the gap between the polarizer and at least one protective film without any difficulty

(2) Water temperature  evaluation

After leaving the polarizing plate prepared in the above Examples and Comparative Examples at 23 占 폚 and 55% relative humidity for 24 hours, a sample of 5 cm 占 2 cm was prepared with the absorption axis (stretching direction) as long sides. Then, the short sides of each sample were gripped, and 80% of the longitudinal direction was immersed in a water bath of 60 ° C for 4 hours, and then taken out to wipe out the water.

Since the polarizer shrinks due to immersion in hot water, the distance from the end of the protective film at the center of the short side of the sample to the shrunk polarizer was measured and made to be the shrink length.

In addition, since iodine eluted from the periphery of the polarizer due to hot water immersion and discolored, the distance from the end of the shrunk polarizer at the center of the short side of the sample to the uncolored portion was defined as the iodine dropout length.

The sum of the shrinkage length and the iodine dropout length was taken as the total erosion length. That is, the total erosion length is the distance from the end of the protective film at the center of the short side of the sample to the non-decolorized portion of the polarizer. The smaller the erosion length is, the better the water resistance is.

◎: total erosion length less than 2mm

○: total erosion length is 2 mm or more to less than 3 mm

△: total erosion length is 3 mm or more and less than 5 mm

X: Total erosion length is 5mm or more

(3) Peel force  evaluation

The polarizing plates prepared in Examples and Comparative Examples were allowed to stand at room temperature for 1 hour, and then bonded to a soda-lime glass with an acrylic pressure-sensitive adhesive. Thereafter, the autoclave was performed at a pressure of 2 atm, a temperature of 50 ° C, and a time of 20 minutes to remove bubbles generated during the bonding.

In a soda glass / pressure sensitive adhesive / corona treated norbornene resin film / monomer plasma treated polariser / corona treated polymethylmethacrylate resin film construction, a knife is placed between the corona treated polymethylmethacrylate resin film and the polarizer The 180 占 peeling force (measuring speed 300 mm / min) on the adhesive layer surface when the polarizer was peeled off was measured using an autograph.

division Adhesion
(Acrylic film) Adhesion
(Saponified TAC) Water resistance Peel force
(Acrylic film) (N / mm) Example 1 ◎ ◎ ○ 6.4 Example 2 ◎ ◎ ◎ 3.8 Example 3 ◎ ◎ ◎ 6.3 Example 4 ◎ ◎ ◎ 8.2 Example 5 ◎ ◎ ◎ 5.3 Example 6 ◎ ◎ ○ 4.3 Example 7 ◎ ◎ ◎ 9.4 Example 8 ◎ ◎ ◎ 5.1 Comparative Example 1 × ◎ × 0.1 or less Comparative Example 2 × ○ × 0.1 or less Comparative Example 3 × ○ × 0.1 or less Comparative Example 4 × ○ × 0.1 or less Comparative Example 5 ○ ○ ○ 1.4

As shown in Table 2, it can be seen that the polarizing plates of Examples 1 to 14 according to the present invention are excellent in adhesion and water resistance regardless of the protective film, unlike the comparative examples.

Claims (8)

A polarizing plate in which an aqueous adhesive composition comprising a polyallylamine-based resin, a crosslinking agent and an alcohol is interposed between a polarizer and a protective film and cured,
The aqueous adhesive composition comprises 140 to 300 parts by weight of the alcohol relative to 100 parts by weight of the polyallylamine resin (based on solid content)
The polarizing plate is wound around a cylindrical bar having a circular cross section with a circumference of 10 π mm in the direction in which the crack is exposed to the outside after the crack is formed in the protective film and folded in half to cut the protective film, Wherein a bubble inclusion length between protective films is within 1 mm.
[4] The polarizer according to claim 1, wherein the polyallylamine resin has a weight average molecular weight of 1,000 to 70,000.
[3] The method of claim 1, wherein the crosslinking agent is at least one selected from the group consisting of an isocyanate compound, an epoxy compound, a peroxide compound, a metal chelate compound, an oxazolane compound, a melamine compound, a glyoxylate compound, and an aziridine compound Polarizer.
[4] The polarizer according to claim 3, wherein the aziridine compound is opened to form a hydrogen bond with the hydroxyl group on the surface of the polarizer.
[4] The method of claim 3, wherein the aziridine compound is selected from the group consisting of trimethylolpropanetri [3- (1-aziridinyl) prionate], trimethylolpropane-tris- (beta-N-aziridinyl) propionate, (2-methyl-1-aziridine propionate), 2-methyl aziridine, lithium L-aziridine-2-carboxylate, N-tosyl aziridine, 1- Wherein the polarizing plate is at least one selected from the group consisting of benzylsulfinyl, benzylsulfinyl, aziridine, 1- (benzylsulfonyl) aziridine, 1- (P-tosyl) aziridine and 1-phenylmethanesulfonyl aziridine.
The polarizing plate according to claim 1, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, t-butanol and glycerol.
The polarizing plate according to claim 1, wherein the protective film is an acrylic resin protective film.
An image display apparatus comprising the polarizing plate of any one of claims 1 to 7.