KR101879833B1 - A polarizing plate and liquid crystal display comprising the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate and a liquid crystal display including the polarizing plate, and more particularly, An adhesive layer comprising an adhesive composition laminated on one side or both sides of the polarizer and containing metal acylate in a range of 3 to 20 parts by weight based on 100 parts by weight of resin (based on solid content); And a polarizer protective film laminated on the adhesive layer, and a liquid crystal display device.
The polarizing plate and the liquid crystal display of the present invention are excellent in adhesion and water resistance (polarizing loss of a polarizer) to a polarizer and a polarizer protective film even under high temperature and high humidity conditions while maintaining optical characteristics equal to or more than the conventional ones, It is resistant to deterioration after being placed under dry heat and has excellent color durability.

Description

[0001] The present invention relates to a polarizing plate and a liquid crystal display including the polarizing plate.

The present invention relates to a polarizing plate having excellent water resistance (color separating phenomenon of a polarizer) and color durability while maintaining optical properties equal to or more than conventional ones, and a liquid crystal display including the same.

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

A polarizer using iodine as a dichroism pigment is an iodine polarizer, and a polarizer using a dichroic dye is a dye-based polarizer. The dual iodine polarizer is widely used because it has high transmittance and high polarization (high contrast) as compared with the dye type polarizer.

However, the iodine polarizer has better optical characteristics than the dye-based polarizer, but has a lower optical durability. For example, when the iodine polarizer or the polarizer including the polarizer is left under the dry heat, the transmittance decreases or the color separator of the polarizer occurs.

Furthermore, in recent years, the field of use of liquid crystal display devices has been expanding and peripheral technologies have been advanced, and the demand for the performance of polarizing plates has become more severe. Concretely, there is a demand for a polarizing plate having high contrast (high transmittance and high polarization degree) and excellent water resistance such as heat resistance and humidity resistance (polarizing phenomenon of polarizer).

On the other hand, Korean Patent No. 888572 contains a melamine crosslinking agent in polyvinyl alcohol resin to improve the water resistance. However, since the amount of the melamine crosslinking agent used for improving the water resistance is excessive and the amine content is high, the optical characteristics And the like.

In addition, Korean Patent Registration No. 914876 contains a zinc salt in a polyvinyl alcohol resin to improve the water resistance. However, since most of the zinc salt is an inorganic zinc salt, the pH of the zinc salt is increased to cause corrosion.

The present invention provides a polarizing plate having improved adhesive strength and water resistance (color discoloration of a polarizer) with respect to a polarizer and a polarizer protective film under high temperature and high humidity conditions while maintaining optical characteristics equal to or more than conventional, while improving the durability reliability The purpose is to do.

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

The present inventors have found that an adhesive composition containing a certain amount of a metal nitrate salt has an increased degree of crosslinking, and a polarizing plate including an adhesive layer composed of the adhesive composition is excellent in adhesive strength while maintaining optical characteristics equal to or more than conventional, And it was found that it has excellent adhesion with the polarizer protective film.

Accordingly, the present invention provides a polarizer comprising: a polarizer; An adhesive layer comprising an adhesive composition laminated on one side or both sides of the polarizer and containing metal acylate in a range of 3 to 20 parts by weight based on 100 parts by weight of resin (based on solid content); And a polarizer protective film laminated on the adhesive layer.

The metal nitrate may be contained in an amount of 5 to 15 parts by weight based on 100 parts by weight of the resin (based on the solid content).

The metal nitrate may be a nitrate of at least one metal selected from the group consisting of copper, zinc, cobalt, magnesium, iron, titanium, manganese, zirconium, aluminum, tin, vanadium, silver, calcium, chromium, nickel, have.

The adhesive composition may have a pH of 4 to 10.

The adhesive composition may contain 100 parts by weight of an acetoacetyl group-modified polyvinyl alcohol resin (based on solid content), 3 to 25 parts by weight of a crosslinking agent of a glyoxylate, and 3 to 20 parts by weight of a metal acetate.

The adhesive composition may further contain an alcohol, a leveling agent, or a mixture thereof.

The polarizer protective film may be a surface treated by a method selected from the group consisting of plasma, corona, primer, and alkali.

The present invention also provides a liquid crystal display device including the polarizer.

The polarizing plate of the present invention is excellent in adhesion strength while maintaining optical properties equal to or greater than those of the prior art, and is excellent in adhesive strength and water resistance (color discoloration of a polarizer) to a polarizer and a polarizer protective film under high temperature and high humidity conditions, There is an effect that can be.

Further, the polarizing plate of the present invention is useful for a liquid crystal display device which is deteriorated after being left under dry heat and is excellent in color durability, and is likely to be exposed to high temperatures such as for mobile phones or vehicles.

In addition, the present invention can be usefully used when a liquid crystal display device including a polarizing plate or a polarizing plate is transported through hot and humid areas such as a tropical region, a region adjacent to the sea, an equatorial region, or the like.

In addition, the present invention can be effectively used even when a backlight having a large amount of heat is used for better sharpness or when a distance between a polarizing plate and a backlight is reduced while a liquid crystal display is thinned.

Fig. 1 shows a test method for an inner temperature aqueous solution of a polarizing plate.

The present invention relates to a polarizing plate having excellent water resistance (color separating phenomenon of a polarizer) and color durability while maintaining optical properties equal to or more than conventional ones, and a liquid crystal display including the same.

Hereinafter, the present invention will be described in detail.

The polarizer of the present invention comprises a polarizer; An adhesive layer comprising an adhesive composition laminated on one side or both sides of the polarizer and containing metal acylate in a range of 3 to 20 parts by weight based on 100 parts by weight of resin (based on solid content); And a polarizer protective film laminated on the adhesive layer.

A polarizer is one in which a dichroic dye is adsorbed and oriented on a stretched polyvinyl alcohol-based film.

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.

The polarizer of the present invention is produced by continuously uniaxially stretching a polyvinyl alcohol-based film in an aqueous solution, staining with a dichroic dye and adsorbing, treating with an aqueous solution of boric acid, and washing and drying.

The uniaxial stretching of the polyvinyl alcohol film may be performed before dyeing, concurrently with dyeing, or may be performed after dyeing. If uniaxial stretching is carried out after dyeing, it may be carried out before the boric acid treatment, or may be carried out during the boric acid treatment. Of course, it is also possible to perform uniaxial stretching in a plurality of such steps. For uniaxial stretching, other rolls or rolls of different circumferences may be used. The uniaxial stretching may be either dry stretching in air or wet stretching in the state of being swollen with a solvent. The stretching ratio is usually 4 to 8 times.

As a step of dyeing a stretched polyvinyl alcohol film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol film in an aqueous solution containing a dichroic dye can be used. As the dichroic dye, iodine or a dichroic dye is used. It is preferable that the polyvinyl alcohol film is pre-immersed in water before dyeing to swell.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based film is dipped in an aqueous solution for dyeing usually containing iodine and potassium iodide may be used. Usually, the content of iodine in an aqueous solution for dyeing is 0.01 to 1 part by weight with respect to 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight with respect to 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 占 폚, and the immersion time (dyeing time) is usually 20 to 1,800 seconds.

When a dichroic dye is used as the dichroic dye, a method of dying and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is generally employed. The content of the dichroic dye in this aqueous solution is usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 part by weight, per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The dye aqueous solution used for dyeing usually has a temperature of 20 to 80 DEG C, and the immersion time for this aqueous solution is usually 10 to 1,800 seconds.

The step of treating the dyed polyvinyl alcohol film with boric acid can be carried out by immersing it in an aqueous solution containing boric acid. The content of boric acid in an aqueous solution containing boric acid is usually 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, it is preferable that the aqueous solution containing boric acid contains potassium iodide. The content thereof is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 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., and more preferably 60 to 80 ° C. The immersing time is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, Preferably 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol film is usually washed with water and dried. The washing treatment can be carried out by immersing the boric acid-treated polyvinyl alcohol-based film in water. The water temperature of the water treatment is usually 5 to 40 占 폚, and the immersion time is usually 1 to 120 seconds. After washing with water, the polarizer can be obtained. The drying treatment can be usually carried out using a hot air dryer or a far infrared ray heater. The drying treatment temperature is usually 30 to 100 占 폚, preferably 50 to 80 占 폚, 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 탆.

The adhesive layer serves to bond the polarizer and the polarizer protective film, and is composed of an adhesive composition containing a metal nitrate salt in the resin.

The resin may be at least one selected from the group consisting of isocyanate-based, polyvinyl alcohol-based, gelatin-based, vinyl polymer-based latex and water-soluble polyester. have. It is preferable to use a polyvinyl alcohol system in consideration of affinity with a polarizer and the like.

The polyvinyl alcohol resin may be a modified polyvinyl alcohol resin such as acetoacetyl group denaturation, carboxy group denaturation, methylol group denaturation, amino group denaturation, etc., and may be an acetoacetyl group denatured polyvinyl alcohol series resin having high reactivity The resin is more preferable.

The acetoacetyl group-modified polyvinyl alcohol-based resin can be obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. Specifically, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid and adding diketene thereto, a method of previously dissolving a polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane, Or a method in which a diketene gas or liquid diketene is directly contacted with a polyvinyl alcohol-based resin, or the like. The acetoacetyl group-modified polyvinyl alcohol resin is not particularly limited so long as the acetoacetyl group modification degree is 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, and most preferably 2 To 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, which is unsuitable. When the degree of modification of the acetoacetyl group exceeds 40 mol%, the effect of improving the water resistance may be insignificant.

The degree of saponification of the acetoacetyl group-modified polyvinyl alcohol-based resin is not particularly limited, but is preferably 80 mol% or more, and more preferably 85 mol% or more. When the degree of saponification of the polyvinyl alcohol-based resin contained in the adhesive composition is low, the sufficient water-solubility is difficult to manifest, so that the adhesiveness tends to become insufficient.

The polyvinyl alcohol used in producing the acetoacetyl group-modified polyvinyl alcohol-based resin is not particularly limited, but in order to exhibit high adhesiveness between the polarizing film and the protective film in the polarizing plate, the average degree of polymerization is in the range of 100 to 3,000 , And the average degree of saponification is preferably in the range of 80 to 100 mol%.

Examples of the products include Z-100, Z-200, Z-200H, Z-210, Z-220 and Z-320 (manufactured by Gohsefymer Japan Synthetic Chemicals).

The adhesive composition of the present invention preferably contains an acetoacetyl group-modified polyvinyl alcohol-based resin, a crosslinking agent of a glyoxylate, and a metal acetate.

The glyoxylate used as a crosslinking agent serves to improve the adhesion between the acetoacetyl group-modified polyvinyl alcohol resin and the polarizer and the polarizer protective film.

The glyoxylate may be an alkali metal salt or an alkaline earth metal salt of glyoxylic acid. The alkali metal salt and the alkaline earth metal salt of the above-mentioned glyoxylic acid can obtain substantially the same effect, and there is no particular limitation on their use. This is presumably because both the alkali metal and the alkaline earth metal are low in electronegativity and the carboxylic acid salt of the metal or the earth metal is similar in chemical properties. Further, since the moiety acting as a crosslinking agent of the acetoacetyl group-modified polyvinyl alcohol is an aldehyde group of the glyoxylate, it is predicted that the metal or the earth metal will exhibit the same effect.

Examples of the glyoxylate include alkali metal salts such as lithium glyoxylate, sodium glyoxylate and potassium glyoxylate, alkaline earth metal salts such as magnesium glyoxylate, calcium glyoxylate, strontium glyoxylate and barium glyoxylate, Can be used. In consideration of the solubility in water, an alkali metal salt is preferable, and sodium glyoxylate is particularly preferable.

These glyoxylates are 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 acetoacetyl group-modified polyvinyl alcohol-based resin (solid content basis) resin. When the content is less than 3 parts by weight, the water resistance of the polarizing plate is not sufficiently exhibited. When the content is more than 25 parts by weight, there is a problem that the optical characteristics (transmittance and polarization degree) of the polarizing plate are lowered.

The metal nitrate acts as a crosslinking aid for increasing the degree of crosslinking between the resin of the adhesive layer and the polarizer and the polarizer protective film to improve the adhesive strength and water resistance.

The metal acetate is specifically a nitrate of a metal selected from the group consisting of copper, zinc, cobalt, magnesium, iron, titanium, manganese, zirconium, aluminum, tin, vanadium, silver, calcium, chromium, nickel, Can be used. It is preferable to use at least one metal selected from the group consisting of zinc, cobalt, magnesium, titanium, zirconium, copper and silver, which is superior in terms of water resistance.

Such a metal nitrate is contained in an amount of 3 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol resin (based on the solid content).

If the content is less than 3 parts by weight, the water resistance of the polarizing plate may not be sufficiently exhibited because of the low degree of crosslinking. If the content is more than 20 parts by weight, gelation of the adhesive composition may occur.

The adhesive composition of the present invention preferably has a pH of 4 to 10. If the pH is less than 4, the water resistance of the polarizing plate can not be sufficiently exhibited. If the pH is more than 10, gelation of the adhesive composition occurs.

The adhesive composition preferably has a viscosity (20 ° C) in the range of 3 to 25 mPa · sec. If the viscosity is less than 3 mPa · sec, the water resistance of the polarizing plate can not be sufficiently exhibited. If the viscosity exceeds 25 mPa · sec, the optical characteristics of the polarizing plate deteriorate.

The adhesive composition may contain additives such as a plasticizer, a silane coupling agent, an antistatic agent, a fine particle, an alcohol, and a leveling agent which are generally used in the art within a range not hindering the desired effect. In particular, it is preferable to use an alcohol, a leveling agent or the like in order to improve the spreadability of the adhesive composition.

Such additives may be used in the range of 0.01 to 3 parts by weight based on 100 parts by weight of the resin (based on the solid content).

It is preferable that the adhesive composition is in a liquid form in order to form a uniform adhesive layer on the surface of the polarizer or the protective film as the adhesive. A solution type or a dispersed liquid type of various solvents can be used for such a liquid type adhesive, 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 from the viewpoint of stability.

For the purpose of shortening the drying process, a water / alcohol mixed solvent in which an alcoholic solvent having a boiling point lower than that of water is easily mixed with water in an adhesive solution may be used. The boiling point of the alcoholic solvent is preferably 100 占 폚 or lower, particularly 80 占 폚 or lower, or 70 占 폚 or lower.

The polarizer protective film is excellent in transparency, mechanical strength, heat stability, moisture shielding property, isotropy and the like, and is not specifically proposed. Specifically, acrylic, cellulose, polyolefin or polyester 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 polarizer protective film is preferably 10 to 200 占 퐉, and 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.

An easy joining process can be performed on the surface of the protective film to be bonded to the polarizer. Examples of the easy-to-bond treatment include a dry treatment such as a primer treatment, a plasma treatment and a corona treatment, a chemical treatment such as an alkali treatment (saponification treatment), and a coating treatment for forming an easy adhesive layer.

The thickness of the adhesive layer 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 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 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 the protective film is moved in the vertical direction, the horizontal direction, or the 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.

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

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be 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

An acetoacetyl modified polyvinyl alcohol resin (Kosenol Z200, Nippon Synthetic Chemical Industry Co., Ltd.) having a saponification degree of 99.2 mol% was dissolved in water (distilled water) to prepare an aqueous solution having a solid content of 5 wt%.

5 parts by weight of sodium glyoxylate (10% by weight aqueous solution) crosslinking agent and 5 parts by weight of zinc acetate (10% by weight aqueous solution) to be a crosslinking auxiliary were added to 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol resin aqueous solution, . The components were mixed on the basis of the solid content, and the pH of the adhesive composition was 6.1 and the viscosity (20 ° C) was 3.4 mPa · sec.

The adhesive composition was coated on both sides of the polarizer on which the iodine adsorption orientation of Production Example 1 was carried out so that the dry film thickness became 0.1 mu m, and then a triacetyl cellulose protective film (Konica Corp., KC8UX) was bonded using niprol. And then dried in a hot-air dryer at 80 ° C for 5 minutes to prepare a polarizing plate.

Example  2

A polarizing plate was produced in the same manner as in Example 1 except that an acrylic protective film (I-film manufactured by Zeon Corporation, Japan) was used instead of the triacetyl cellulose protective film.

Example  3 to 14 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.

Classification (parts by weight) Polyvinyl alcohol resin Cross-linking agent Metal nitrate Leveling agent pH Viscosity Example 3 100 Sodium glyoxylate (5) Magnesium acetate
(10) - 6.1 3.4 Example 4 100 Sodium glyoxylate (5) Magnesium acetate
(15) - 5.8 3.8 Example 5 100 Sodium glyoxylate (5) Magnesium acetate
(20) - 5.6 4.4 Example 6 100 Sodium glyoxylate (5) Magnesium acetate
(10) 3 5.9 4.2 Example 7 100 Sodium glyoxylate (5) Cobalt acetate
(10) - 7.4 4.4 Example 8 100 Sodium glyoxylate (5) Zirconium acetate
(10) - 4.3 3.4 Example 9 100 Sodium glyoxylate (5) Copper acetate
(10) - 9.2 4.1 Example 10 100 Sodium glyoxylate (5) Iron acetate
(10) - 7.2 4.3 Example 11 100 Sodium glyoxylate (5) Titanium acetate (10) - 4.5 4.2 Example 12 100 Sodium glyoxylate (5) Aluminum acetate
(10) - 4.2 4.4 Example 13 100 Sodium glyoxylate (5) Silver acetate
(10) - 5.1 4.9 Example 14 100 Sodium glyoxylate (5) Calcium acetate
(10) - 5.2 4.3 Comparative Example 1 100 Sodium glyoxylate (5) - - 4.7 3.4 Comparative Example 2 100 Sodium glyoxylate (5) Zinc chloride
(10) - 3.2 3.9 Comparative Example 3 100 Melamine crosslinking agent (5) - - 8.2 4.8 Comparative Example 4 100 Sodium glyoxylate (5) Magnesium acetate
(One) - 6.3 4.2 Comparative Example 5 100 Sodium glyoxylate (5) Magnesium acetate
(25) - 7.1 5.4 Polyvinyl alcohol resin: Acetoacetyl group-modified polyvinyl alcohol resin (Kosenol Z200, Nippon Synthetic Chemical Industry Co., Ltd.)
Leveling agent: ISA Superior, Surfynol 465 product
Viscosity (mPa · sec): Measured at 20 ° C
The content of each component is based on the solid content.

Experimental Example

The physical properties of the polarizer prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 2 below.

1. Adhesion (Cutter Evaluation)

The prepared polarizing plate was allowed to stand at room temperature for 1 hour, and then a cutter blade was inserted between each polarizing plate (between the polarizing plate and the polarizing plate protective film), and the way in which the blade was pushed was evaluated according to the following criteria .

[Assessment Methods]

A: The cutter blade does not enter any film.

○: When pushing the blade, it stops when the blade reaches 1 to 2 mm between at least one of the films.

DELTA: When pushing the blade, it stops when the blade reaches 3 to 5 mm between at least one of the films.

X: When pushing the blade, the blade is easily inserted between at least one of the films.

2. Water Resistance

The prepared polarizing plate was allowed to stand for 24 hours under an environment of 23 ° C and a relative humidity of 55%, and tested for water resistance at room temperature. First, the polarizing plate was cut into a rectangular shape of 5 cm x 2 cm with the absorption axis (stretching direction) of the polarizing plate as the long side to prepare a sample, and the dimension in the long side direction was measured accurately. Here, the sample exhibits uniform color uniformly over the entire surface due to iodine adsorbed on the polarizer. As shown in Fig. 1, (A) shows that the short side of the sample 1 is gripped by the grip portion 5 before immersion in the hot water, (B) Showing a shrunk sample 4 after immersing about 80% in the longitudinal direction in a hot water tank at 60 캜 for 4 hours. When the immersion is completed, the sample (4) is taken out of the water tank to wipe the moisture, and the degree of shrinkage of the polarizer is measured. Specifically, the distance from the end 1a of the protective film at the center of the short side of the sample 1 to the end of the polarizer 4 contracted was measured, and this was taken as the contraction length. 1B, the polarizer 4 positioned at the center of the polarizing plate shrinks due to the immersion of hot water, and a region 2 in which the polarizer 4 is not present between the two protective films is formed. In addition, iodine elutes from the peripheral portion of the polarizer 4 which is in contact with the hot water due to the hot water immersion, and a portion 3 in which the color is missing in the peripheral portion of the sample 1 is generated. The degree of discoloration was measured as the distance from the end of the shrunk polarizer 4 at the center of the short side of the sample 1 to the region where the color unique to the polarizing plate remained, and this was taken as the iodine drop length. The total erosion length X means the total erosion length X from the end 1a of the sample 1 at the center of the short side of the sample 1 to the total length of the sample 1 from the end 1a of the sample 1, This is the distance to the area where the color remains. It can be concluded that the smaller the shrinkage length, the iodine dropout length and the total erosion length (X), the higher the adhesiveness (water resistance at room temperature) in the presence of water.

[Assessment Methods]

?: Total erosion length (X) < 2 mm

?: 2 mm? Total erosion length (X) < 3 mm

?: 3 mm? Total erosion length (X) <5 mm

X: 5 mm? Total erosion length (X)

3. Optical characteristics (transmittance, polarization degree) (%)

The prepared polarizer was cut into a size of 4 cm x 4 cm to prepare a specimen. The specimen was attached to a measurement holder, and then the transmittance was measured using an ultraviolet spectrophotometer (V-7100, manufactured by JASCO). At this time, the polarization degree is defined by the following equation (1).

(Wherein T ₁ is the parallel transmittance obtained when the pair of polarizers are arranged in parallel with the absorption axis, and T ₂ is the orthogonal transmittance obtained when the pair of polarizers are arranged so that the absorption axes are perpendicular to each other) .

4. Color Durability

1) DELTA A700, DELTA orthogonal b evaluation

The spectral transmittance? (?) Of the polarizer was measured using a spectrophotometer (V7100, manufactured by Nippon Bunko KK). An orthogonal spectral transmittance spectrum was obtained from the measured spectral transmittance? (?), And A700 was obtained from the spectral transmittance spectrum using the orthogonal color b and the equation (2). Thereafter, the polarizer was allowed to stand in a dry atmosphere at 105 캜 for 30 minutes (durability test), and the spectral transmittance τ (λ) was measured again. The orthogonal spectral transmittance spectrum was obtained from the measured spectral transmittance τ A700 was obtained from the spectrum using the orthogonal color b and the following equation 2 to determine the difference between the orthogonal color b before and after the durability test as? Orthogonal b, and the difference between before and after the durability test of A700 as? A700.

In the formula, TMD, 700 denotes a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizing plates are arranged in parallel with the absorption axes, and TTD, 700 denotes a pair of polarizing plates arranged in a state in which the absorption axes are perpendicular to each other Lt; RTI ID = 0.0 &gt; 700nm &lt; / RTI &gt; wavelength)

2) ΔE evaluation

Using the orthogonal L, orthogonal a, and orthogonal b values from the spectral transmission spectrum, the difference between before and after the durability test was defined as? E using the equation (3).

(In the formula, L _0: the duration before the orthogonal value L, L _1: Durability after orthogonal L value, a _0: duration before orthogonal a value, a _1: Durability after orthogonal a value, b _0: duration before quadrature b value, b ₁ : quadrature b value after durability)

The variation in the optical characteristics and color evaluation is considered to be better as the value is smaller.

3) Rusty  evaluation

The prepared polarizers were perpendicular to each other and the backlight was turned on in the dark room to confirm the initial dark state. After standing for 30 minutes in a dry atmosphere at 105 ° C, the dark state was confirmed again, ) Were visually confirmed.

division Adhesion Water resistance Optical properties (%) Color Durability Transmittance Polarization degree ΔA700 Δ orthogonal b ΔE Rash occurrence
The presence or absence Example 1 ◎ ○ 43.4 99.999 0.54 0.12 0.41 radish Example 2 ◎ ◎ 43.4 99.999 0.43 0.14 0.43 radish Example 3 ◎ ◎ 43.5 99.999 0.34 0.1 0.21 radish Example 4 ◎ ◎ 43.7 99.999 0.33 0.1 0.2 radish Example 5 ◎ ◎ 43.5 99.999 0.35 0.1 0.2 radish Example 6 ◎ ◎ 43.5 99.999 0.65 0.23 0.45 radish Example 7 ◎ ◎ 43.5 99.999 0.33 0.1 0.2 radish Example 8 ◎ ◎ 43.4 99.999 0.58 0.22 0.39 radish Example 9 ◎ ◎ 43.5 99.999 0.33 0.1 0.21 radish Example 10 ◎ ○ 43.5 99.999 0.76 0.29 0.48 radish Example 11 ◎ ○ 43.3 99.999 0.28 0.1 0.13 radish Example 12 ◎ ○ 43.6 99.999 0.71 0.31 0.28 radish Example 13 ◎ ○ 43.4 99.999 0.22 0.1 0.12 radish Example 14 ◎ ○ 43.5 99.999 0.82 0.33 0.61 radish Comparative Example 1 ○ × 43.4 99.999 1.54 0.51 1.34 U Comparative Example 2 ○ △ 43.5 99.999 1.21 0.44 1.28 U Comparative Example 3 ◎ △ 43.0 99.998 1.62 0.53 1.45 U Comparative Example 4 ○ △ 43.5 99.999 1.49 0.48 1.31 U Comparative Example 5 - - - Gelation occurred - - - -

As shown in the above table, it was confirmed that the polarizing plates of Examples 1 to 14 including the adhesive layer containing a metal acetate salt according to the present invention had excellent adhesive strength, water resistance, optical characteristics (transmittance and polarization degree) and color durability there was.

Particularly, it can be confirmed that Examples 2 to 9 using magnesium, cobalt, zirconium and copper metal nitrates are excellent in water resistance.

On the other hand, it can be confirmed that Comparative Examples 1 to 4 are poor in water resistance and color durability as a whole, and Comparative Example 5 means that the properties can not be measured by gelation of the adhesive composition, which can not be used as an adhesive layer .

1: sample
1a: end of protective film
2: area where no polarizer exists
3: a portion where the color is missing in the peripheral portion of the sample
4: Polarizer
5:

Claims (8)

A polarizer;
An adhesive layer comprising an adhesive composition laminated on one side or both sides of the polarizer and containing metal acylate in a range of 3 to 20 parts by weight based on 100 parts by weight of resin (based on solid content); And
And a polarizer protective film laminated on the adhesive layer,
Wherein the metal acetate is a nitrate of a metal selected from the group consisting of copper, zinc, cobalt, magnesium and zirconium.
The polarizing plate according to claim 1, wherein the metal acetate is contained in an amount of 5 to 15 parts by weight based on 100 parts by weight of the resin (based on the solid content).
delete The polarizer of claim 1, wherein the adhesive composition has a pH of 4 to 10.
The adhesive composition according to claim 1, wherein the adhesive composition comprises 100 parts by weight of an acetoacetyl group-modified polyvinyl alcohol resin (based on solid content), 3 to 25 parts by weight of a crosslinking agent of a glyoxylate, and 3 to 20 parts by weight of a metal acetate salt .
The polarizer of claim 5, wherein the adhesive composition further comprises an alcohol, a leveling agent, or a mixture thereof.
The polarizer of claim 1, wherein the polarizer protective film is surface treated by a method selected from the group consisting of plasma, corona, primer and alkali.
A liquid crystal display device comprising the polarizing plate of any one of claims 1, 2, and 4 to 7.

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