WO2014204134A1 - Thin polarizing plate and method for manufacturing same - Google Patents

Abstract

The present invention relates to a method for manufacturing a thin polarizing plate, comprising the steps of: attaching an unstretched polyvinyl alcohol-based film onto an unstretched base material film by means of an attractive force or an adhesive to thereby form a film laminated body; stretching the film laminated body; attaching a first protective film to the polyvinyl alcohol-based film of the stretched film laminated body; and separating a base film and the polyvinyl alcohol-based film to which the first protective film is attached.

Description

Thin polarizer and its manufacturing method

The present invention relates to a thin polarizing plate and a method of manufacturing the same, and more particularly, to a method of manufacturing a thin polarizing plate including a polarizer having a thin thickness of 10 μm or less, and capable of manufacturing various kinds of polarizing plates in one process. It is about.

The polarizer used in the polarizing plate is an optical element for making natural light or arbitrary polarization into a polarized light in a specific direction, and is widely used in a display device such as a liquid crystal display device and an organic light emitting device (OLED). Currently, as a polarizer used in the display device, a polyvinyl alcohol polarizing film in which molecular chains containing an iodine compound or a dichroic dye are oriented in a constant direction is generally used.

The polyvinyl alcohol polarizing film is prepared by a method of dyeing and crosslinking iodine or dichroic dye on a polyvinyl alcohol-based film, and stretching in a predetermined direction, wherein the stretching process is an aqueous solution of boric acid or an iodine solution. It may be performed by wet stretching performed in solution or dry stretching performed in air. By the way, in this conventional manufacturing process, in order for extending | stretching to be performed without a breakage generation, it is required that the thickness of the polyvinyl alcohol-type film before extending | stretching exceeds 60 micrometers. This is because when the thickness of the polyvinyl alcohol-based film before stretching is 60 μm or less, the swelling degree of the polyvinyl alcohol-based film is increased, and the thinness of the polyvinyl alcohol-based film increases the modulus acting per unit area in the stretching process, thereby easily causing breakage.

On the other hand, according to the trend of thinning of display devices, polarizers are also required to have a thinner thickness. However, when using a polyvinyl alcohol-based film having a thickness before stretching of more than 60 ㎛ as in the prior art there is a limit in reducing the thickness of the polarizer. Therefore, studies have been attempted to fabricate thinner polarizers.

Korean Unexamined Patent Publication No. 2010-0071998 discloses a method of manufacturing a thin polarizing plate using a laminate prepared by coating a hydrophilic polymer layer on a substrate layer or co-extrusion of a substrate layer forming material and a hydrophilic polymer layer forming material. It is. However, in the case of coating or co-extrusion, since the separation of the polyvinyl alcohol layer and the base layer is not easy after stretching and a high peel force is required for the separation, the polyvinyl alcohol layer is damaged or deformed during the separation process. Problems tend to occur, and as a result, there is a problem that optical properties such as polarization degree of the polyvinyl alcohol film are inferior. In addition, when a coating method or a coextrusion method is used, the polyvinyl alcohol resin is manufactured by melting and extruding the polyvinyl alcohol resin or by applying the coating solution after coating and then applying the polyvinyl alcohol according to extrusion conditions, coating conditions or film forming conditions. The physical properties of the film tend to change, and not only the physical properties of the finally produced polyvinyl alcohol are lowered, but also it is difficult to realize uniform physical properties.

Therefore, it is necessary to manufacture the polarizing plate containing the thin polarizer which is thin but has the outstanding optical physical property.

The present invention is to solve the above problems, to provide a thin polarizing plate having excellent optical properties, excellent curl properties, and a manufacturing method thereof having a single transmittance of 40 to 45%, a polarization degree of 99.0% or more.

In one aspect, the present invention comprises the steps of attaching a non-stretched polyvinyl alcohol-based film using a attraction force or an adhesive on the unstretched base film to form a film laminate; Stretching the film laminate; Attaching a first protective film on the polyvinyl alcohol-based film of the stretched film laminate; And it provides a method for producing a thin polarizing plate comprising the step of separating the polyvinyl alcohol-based film and the base film to which the first protective film is attached.

In this case, the method of manufacturing a thin polarizing plate of the present invention may further include dyeing at least one of iodine and dichroic dye on the film laminate before the stretching of the film laminate.

In addition, the method of manufacturing a thin polarizing plate of the present invention may further include drying the stretched film laminate after the stretching of the film laminate.

In addition, the method of manufacturing a thin polarizing plate of the present invention, after the step of separating the polyvinyl alcohol-based film and the base film with the protective film, the second side to the side where the protective film of the polyvinyl alcohol-based film is not attached The method may further include attaching a protective film.

Alternatively, in the method of manufacturing the thin polarizing plate of the present invention, after the separating of the polyvinyl alcohol-based film and the base film with the protective film, the adhesive layer on the surface where the protective film of the polyvinyl alcohol-based film is not attached It may further comprise forming a.

In another aspect, the present invention is a polyvinyl alcohol polarizer having a thickness of 10㎛ or less; And a first protective film attached to one surface of the polyvinyl alcohol-based polarizer, and has a single transmittance of 40% to 45% and a polarization degree of 99.0% or more.

According to the production method of the present invention, in addition to manufacturing a thin polarizing plate excellent in optical properties, when attaching a polyvinyl alcohol-based film on both sides of the base film, the productivity is excellent, and a variety of forms of a polarizing plate in one process There is an advantage that can be prepared.

In addition, the thin polarizing plate manufactured according to the manufacturing method of the present invention is less curl, it is possible to minimize the light leakage phenomenon when applying the display device.

1 is a schematic diagram showing a method for measuring adhesion using a texture analyzer (Texture Analyzer).

2 is a view showing a state of a laminated film produced according to the method of Comparative Example 1.

3 is a photograph showing curl characteristics of a thin polarizing plate manufactured by the method of Example, Comparative Example 3 and Comparative Example 4.

Figure 4 is a photograph showing the side portion curl phenomenon of the film laminate after stretching of Comparative Example 6.

5 is a photograph showing a state of the film laminate after stretching in Example 2. FIG.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The inventors of the present inventors have conducted a long study to produce a polarizer having no optical breakage and excellent optical properties without breaking in the manufacturing process, and as a result, a polyvinyl alcohol-based film is attracted to the base film using an attractive force or an adhesive. It was found that the above object can be attained by drawing and attaching the same. In this regard, Korean Patent Application No. 10-2012-0130576 and Korean Patent Application No. 10-2012-0130577 There is a bar.

In addition, the inventors of the present invention, through the further research, in the method for producing a thin polarizer, the step of attaching the first protective film on the polyvinyl alcohol-based film before the separation of the base film and the polyvinyl alcohol-based film Next, when the base film and the polyvinyl alcohol-based film are separated, the base film and the polyvinyl alcohol-based film are not only separated more cleanly, but also a polarizing plate having excellent curl characteristics can be produced, and the productivity can be further improved. It was found and completed the present invention.

More specifically, the method of manufacturing a thin polarizing plate according to the present invention comprises the steps of: attaching a non-stretched polyvinyl alcohol-based film using a attraction force or an adhesive on an unstretched base film to form a film laminate; Stretching the film laminate; Attaching a first protective film on the polyvinyl alcohol-based film of the stretched film laminate; And separating the polyvinyl alcohol-based film and the base film to which the first protective film is attached.

First, an unstretched polyvinyl alcohol-based film is attached onto the unstretched base film by using attraction force or an adhesive to form a film laminate. In this case, the unstretched polyvinyl alcohol-based film may be attached to one side or both sides of the unstretched base film. In consideration of productivity and process stability, it is more preferable that a polyvinyl alcohol-based film is attached to both sides of the unstretched base film.

In this case, the unstretched base film is to prevent the polyvinyl alcohol-based film from breaking in the stretching process, preferably, may be a polymer film having a maximum draw ratio of 5 times or more under a temperature condition of 20 ℃ to 85 ℃. In this case, the maximum draw ratio means a draw ratio immediately before breakage occurs. On the other hand, the stretching may be dry stretching or wet stretching, in the case of wet stretching, the stretching ratio in the case of stretching in an aqueous boric acid solution having a boric acid concentration of 1.0 to 5% by weight.

Such base films include, but are not limited to, high density polyethylene films, polyurethane films, polypropylene films, polyolefin films, ester films, low density polyethylene films, high density polyethylene and low density polyethylene coextrusion films, high density polyethylene Ethylene vinyl acetate-containing copolymer resin film, acrylic film, polyethylene terephthalate film, polyvinyl alcohol film, cellulose film and the like.

Meanwhile, the base film used in the present invention may have a thickness of about 20 μm to 100 μm, preferably about 30 μm to 80 μm, and more preferably about 40 μm to 60 μm. When the thickness of the base film is less than 20 μm, breakage may occur due to insufficient support of the polyvinyl alcohol-based film in the stretching process of the film laminate, and when it exceeds 100 μm, the stretchability of the film laminate may be deteriorated. This is because it can prevent free width shrinkage during drying of the polyvinyl alcohol-based film, thereby inhibiting optical properties of the finally obtained polarizer.

In addition, the glass transition temperature of the base film is preferably lower than the glass transition temperature of the polyvinyl alcohol-based film, for example, it is preferably about 20 ℃ to 60 ℃, preferably 30 ℃ to 60 ℃. In general, considering that the glass transition temperature of the polyvinyl alcohol-based film is about 70 ° C. to 80 ° C., when the glass transition temperature of the base film satisfies the above numerical range, the base film is softer under the stretching temperature conditions. It can have a result, it is possible to stretch the polyvinyl alcohol-based film better. However, when the glass transition temperature of the base film is too low, breakage may occur during high magnification stretching, and the glass transition temperature of the base film is preferably 20 ° C. or higher. On the other hand, the glass transition temperature may be measured by a differential scanning calorimeter (DSC). For example, when a sample of about 10 mg is sealed in a dedicated pan of a differential scanning calorimeter (DSC) and heated to a constant temperature condition, the endothermic and calorific values generated by phase shifting are plotted according to the temperature. The temperature can be measured.

The base film may have a modulus at room temperature (25 ° C.) of about 200 MPa to 1500 MPa, preferably about 350 MPa to 1300 MPa. When the modulus of the base film exceeds 1500MPa, high magnification stretching may be difficult, and when less than 200MPa, breakage may occur in the stretching process. In this case, the modulus is fixed to both ends of the sample prepared according to JIS-K6251-1 standard, and then applied a force in a direction perpendicular to the thickness direction of the film to measure the stress per unit area according to the tensile rate (strain) The value obtained by this is referred to, and a tensile force meter (Zwick / Roell Z010 UTM) etc. can be used as a measuring instrument.

In addition, the base film may have a force at break point at room temperature (25 ° C.) of about 5N to about 40N, preferably about 10N to about 30N. In this case, the breaking force refers to a tensile force at the time when the base film is broken when the both ends of the film is fixed and a tensile force is applied in a direction perpendicular to the thickness direction of the film, for example, a tensile force meter (Zwick / Roell Z010 UTM) and the like can be measured. When the breaking force of the base film is out of the above numerical range, problems such as high magnification stretching may be difficult or breakage may occur in the stretching process.

Next, the unstretched polyvinyl alcohol-based film attached to the base film has a thickness of about 10 μm to 60 μm, preferably about 10 μm to 40 μm. When the thickness of the polyvinyl alcohol-based film exceeds 60㎛, it is difficult to achieve a thickness of 10㎛ or less even when stretched, when the thickness is less than 10㎛ tends to break during stretching.

On the other hand, the polyvinyl alcohol-based film is not limited to this, but the degree of polymerization is preferably about 1,000 to 10,000, preferably 1,500 to 5,000. This is because when the degree of polymerization satisfies the above range, the molecular motion is free and can be mixed flexibly with iodine or dichroic dye.

Meanwhile, as the polyvinyl alcohol-based film of the present invention, a commercially available polyvinyl alcohol-based film may be used. For example, PS30, PE30, PE60 manufactured by Gurere, M2000, M3000 M6000, etc. may be used.

On the other hand, in the present invention, the base film and the polyvinyl alcohol-based film is attached by a weak attraction force generated on the surface of the base film and the unstretched polyvinyl alcohol-based film without a separate medium, or may be attached via an adhesive Can be.

When the base film and the unstretched polyvinyl alcohol-based film are attached by the attraction force, the base film and the unstretched polyvinyl alcohol-based film may be treated by surface treatment on one or both surfaces of the base film or the polyvinyl alcohol-based film. In this case, the surface treatment may be performed through various surface treatment methods well known in the art, for example, corona treatment, plasma treatment, or surface modification treatment using a strong base aqueous solution such as NaOH or KOH.

When the base film and the polyvinyl alcohol-based film are attached by using an adhesive, the thickness of the adhesive layer before stretching may be about 20 nm to 4000 nm, preferably about 20 nm to 1000 nm, and more preferably about 20 nm to 500 nm. On the other hand, the thickness of the adhesive layer after the stretching of the film laminate may be about 10nm to 1000nm, preferably 10nm to 500nm, more preferably 10nm to 200nm. When the thickness of the adhesive layer before and after stretching satisfies the above range, it is advantageous to peel the polyvinyl alcohol-based film without damage after the stretching and drying process.

On the other hand, the adhesive, the material is not particularly limited, various adhesives known in the art can be used without limitation. For example, the adhesive layer may be formed of an aqueous adhesive or an ultraviolet curable adhesive.

When the adhesive layer is formed of an aqueous adhesive, the aqueous adhesive preferably includes an amine metal compound crosslinking agent in an acetacetyl group-containing polyvinyl alcohol-based resin. More specifically, the adhesive may be an aqueous solution containing 100 parts by weight of a polyvinyl alcohol-based resin containing an acetacetyl group and 1 to 50 parts by weight of an amine metal compound crosslinking agent.

According to the researches of the present inventors, when the base film and the polyvinyl alcohol-based film are attached using a general water-based adhesive, the water resistance is poor and the adhesive melts due to moisture infiltration in the stretching and cleaning process. Adhesion occurs non-uniformly, and as a result, there was a problem that the incidence of breakage during stretching is increased. In this case, after bonding the polyvinyl alcohol film and the base film, a large amount of fine wrinkles in the form of cracks are generated on the surface due to the difference in the swelling degree of the base film and the polyvinyl alcohol film. The phenomenon also appeared to occur. This is believed to be due to the non-uniform adhesion of the base film and the polyvinyl alcohol-based film due to melting by exposure to moisture in the case of the conventional adhesive. However, when using an aqueous adhesive containing an amine-based metal compound crosslinking agent in an acetacetyl group-containing polyvinyl alcohol-based resin as in the present invention, crosslinking of the acetacetyl group of the amine-based metal compound and the polyvinyl alcohol-based resin at the time of curing the adhesive Since the reaction occurs, the water resistance of the adhesive layer after curing is remarkably improved, and as a result, the problem due to the lack of water resistance of the conventional polyvinyl alcohol-based adhesive can be solved.

Meanwhile, the polymerization degree and saponification degree of the polyvinyl alcohol-based resin are not particularly limited as long as they contain acetacetyl group, but the polymerization degree is 200 to 4,000, and the saponification degree is preferably 70 mol% to 99.9 mol%. Considering flexible mixing with the containing material according to the freedom of molecular movement, the degree of polymerization is 1,500 to 2,500, and the degree of saponification is more preferably 90 mol% to 99.9 mol%. In this case, the polyvinyl alcohol-based resin preferably comprises 0.1 to 30 mol% of the acetacetyl group. In the above range, the reaction with the amine-based metal compound crosslinking agent may be smooth, and may be sufficiently significant for the water resistance of the desired adhesive.

The amine-based metal compound crosslinking agent is a water-soluble crosslinking agent having a functional group having reactivity with the polyvinyl alcohol-based resin, preferably in the form of a metal complex containing an amine ligand. Possible metals include zirconium (Zr), titanium (Ti), hafnium (Hf), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), osmium (Os), Transition metals such as rhodium (Rh), iridium (Ir), palladium (Pd) and platinum (Pt) are possible, and ligands bound to the central metal are primary amines, secondary amines (diamines), tertiary amines or ammonium hydrides. As long as it contains at least 1 or more amine groups, such as a lockside, it is all possible.

In the adhesive, the solid content of the polyvinyl alcohol-based resin containing the acetacetyl group is preferably about 1% by weight to about 10% by weight. If the solid content of the polyvinyl alcohol-based resin is less than 1% by weight, the water resistance is not sufficiently secured, so that the effect of lowering the breakage rate in the stretching process is less. If the content is more than 10% by weight, the workability is deteriorated. This is because damage may occur on the alcohol-based film surface.

On the other hand, the pH of the adhesive is preferably 4.5 to 9 or so. When the pH of an adhesive agent satisfy | fills the said numerical range, it is because it is more advantageous in storage property and durability in a high humidity environment.

On the other hand, the pH of the adhesive can be adjusted by the method of containing an acid in the aqueous solution, wherein the acid used for pH adjustment can be used both strong and weak acid. For example, nitric acid, hydrochloric acid, sulfuric acid or acetic acid and the like can be used.

The thickness of the adhesive layer formed by the above adhesive is about 80 nm to 200 nm, preferably about 80 nm to 150 nm before stretching the film laminate, and after stretching the film laminate, about 10 nm to 100 nm, preferably 10 nm to It is preferable that it is about 80 nm. When the thickness of the adhesive layer satisfies the above range, the adhesive force between the polyurethane film and the polyvinyl alcohol-based film is maintained at an appropriate level, so that the breakage rate in the stretching process is lowered and the polarizer surface damage during peeling can be minimized. to be.

In the case of the said adhesive agent, a crosslinking reaction occurs between the amine type metal compound and the acetacetyl group of polyvinyl alcohol-type resin at the time of hardening, and the water resistance of the adhesive layer after hardening becomes very excellent. Therefore, when the polymer film and the polyvinyl alcohol-based film are laminated using the adhesive, the phenomenon in which the adhesive dissolves in water during wet stretching can be minimized, and thus it can be particularly useful when performing wet stretching. .

Meanwhile, the adhesive layer may be formed of an ultraviolet curable adhesive, for example, a first epoxy compound having a glass transition temperature of homopolymer of 120 ° C. or more, a second epoxy compound having a glass transition temperature of homopolymer of 60 ° C. or less and It may be formed of an ultraviolet curable adhesive containing a cationic photopolymerization initiator. Specifically, the UV-curable adhesive is 100 parts by weight of the first epoxy compound having a glass transition temperature of the homopolymer of 120 ℃ or more, 30 to 100 parts by weight of the second epoxy compound having a glass transition temperature of the homopolymer of 60 ℃ or less and cationic photopolymerization It may include 0.5 to 20 parts by weight of the initiator.

As used herein, an epoxy compound refers to a compound having one or more epoxy groups in a molecule, preferably a compound having two or more epoxy groups in a molecule, and is in the form of a monomer, a polymer, or a resin. The concept includes all of the compounds. Preferably the epoxy compound of the present invention may be in the form of a resin.

On the other hand, as the first epoxy compound, if the glass transition temperature of the homopolymer is an epoxy compound of 120 ℃ or more can be used without particular limitation, for example, the alicyclic epoxy compound and the glass transition temperature of the homo polymer is 120 ℃ or more and / Or aromatic epoxy may be used as the first epoxy compound of the present invention. Specific examples of the epoxy compound having a glass transition temperature of homopolymer of 120 ° C or higher include 3,4-epoxycyclohexylmethyl-3,4'-epoxycyclohexanecarboxylate, vinylcyclohexenedioxide dicyclopentadiene dioxide, and bisepoxycyclo. A pentyl ether, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, etc. are mentioned. On the other hand, the first epoxy compound is more preferably the glass transition temperature of the homopolymer is about 120 ℃ to 200 ℃.

Next, the second epoxy compound may be used without particular limitation as long as the glass transition temperature of the homopolymer is an epoxy compound of 60 ° C. or less. For example, an alicyclic epoxy compound, an aliphatic epoxy compound, or the like may be used as the second epoxy compound.

In this case, as the alicyclic epoxy compound, it is preferable to use a bifunctional epoxy compound, that is, a compound having two epoxies, and more preferably use a compound in which the two epoxy groups are both alicyclic epoxy groups. It is not limited.

As an aliphatic epoxy compound, the epoxy compound which has an aliphatic epoxy group which is not an alicyclic epoxy group can be illustrated. For example, polyglycidyl ether of aliphatic polyhydric alcohol; Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Polyglycidyl ethers of polyester polyols of aliphatic polyhydric alcohols and aliphatic polyhydric carboxylic acids; Polyglycidyl ethers of aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of polyester polycarboxylic acids of aliphatic polyhydric alcohols and aliphatic polyhydric carboxylic acids; Dimers, oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate; Or oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate with other vinyl monomers, preferably polyglycidyl of aliphatic polyhydric alcohols or their alkylene oxide adducts. Ether may be used, but is not limited thereto.

As the aliphatic polyhydric alcohol, for example, an aliphatic polyhydric alcohol having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms or 2 to 4 carbon atoms may be exemplified. Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neo Pentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8- Aliphatic diols such as octanediol, 1,9-nonanediol and 1,10-decanediol; Alicyclic diols such as cyclohexanedimethanol, cyclohexanediol, hydrogenated bisphenol A and hydrogenated bisphenol F; Trimethylol ethane, trimethylol propane, hexitols, pentitols, glycerin, polyglycerol, pentaerythritol, dipentaerythritol, tetramethylol propane and the like can be exemplified.

In addition, as the alkylene oxide in the above, alkylene oxide of 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms can be exemplified, for example, ethylene jade Seeds, propylene oxide or butylene oxide and the like can be used.

Moreover, as said aliphatic polyhydric carboxylic acid, For example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sumeric acid, azelaic acid, sebacic acid, dodecane diacid, 2-methyl succinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentaneic acid, 2-methyloctanoic acid, 3,8-dimethyldecanediic acid, 3,7-dimethyldecanediic acid, 1,20-eicosamethylenedica Carboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1,4-dicarboxymethylenecyclohexane, 1,2,3-propanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2, 3,4-cyclobutanetetracarboxylic acid and the like can be exemplified, but is not limited thereto.

Preferably, the second epoxy compound of the present invention may include one or more glycidyl ether groups, for example, 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-butanediol diggle Cydyl ether, 1,6-hexanediol diglycidyl ether, neopentyl diglycidyl ether, resorcinol diglycidyl ether, diethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, One selected from the group consisting of trimethylolpropanetriglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and o-cresyl glycidyl ether The above can be used as the second epoxy compound of the present invention.

On the other hand, it is more preferred that the second epoxy compound has a glass transition temperature of about 0 ° C to 60 ° C of the homopolymer.

Meanwhile, the present invention is not limited thereto, but in the present invention, it is preferable to use a combination of the first epoxy compound including at least one epoxidized aliphatic ring group and the second epoxy compound including at least one glycidyl ether group as the epoxy compound. Particularly preferred.

On the other hand, when a film laminated body is formed by attaching a polyvinyl alcohol-type film to both surfaces of a base film, the said film laminated body is extended | stretched. In this case, the stretching is preferably carried out so that the thickness of the polyvinyl alcohol-based film is less than 10㎛, for example, the thickness of the polyvinyl alcohol-based film is 1㎛ to 10㎛, 3㎛ to 10㎛ or 1㎛ It is preferable to carry out so that it becomes about 5 micrometers.

In addition, the stretching is preferably performed so that the width shrinkage of the polyvinyl alcohol-based film is about 30% to 80%, preferably about 60% to 80%. This is because when the width shrinkage ratio of the polyvinyl alcohol-based film satisfies the numerical range, excellent optical properties can be obtained.

On the other hand, in the present invention, the stretching conditions are not particularly limited, for example, the stretching may be carried out at a draw ratio of 5 times to 15 times at a temperature of 20 ℃ to 85 ℃, more preferably 40 It may be carried out at a draw ratio of 5 to 12 times at a temperature of ℃ to 80 ℃.

In this case, the stretching may be performed by wet stretching or dry stretching. However, when the wet stretching is performed, since the surface adhesion of the base film and the polyvinyl alcohol-based film is stronger than the dry stretching, the stretching can be performed stably without a separate bonding means. On the other hand, the wet stretching is preferably carried out in an aqueous boric acid solution, wherein the boric acid concentration of the aqueous boric acid solution is preferably about 1.0 to 5.0 wt%.

When the stretching is performed in the aqueous boric acid solution as described above, the breakage rate of the PVA film is lowered due to the boric acid crosslinking, thereby increasing process stability and controlling wrinkles of the PVA film, which is easily generated during the wet process. In addition, there is an advantage that stretching is possible at low temperatures compared to dry stretching.

On the other hand, in general, the manufacturing process of the polarizing element is a process of washing with water, swelling, dyeing, washing, stretching, complementary color, drying and the like, in the case of the present invention, the washing and stretching process is preferably carried out in an aqueous boric acid solution. More preferably, in the cleaning process, the boric acid concentration may be about 0.1 to 2.5 wt%, preferably about 0.5 to 2.0 wt%, and in the stretching process, the boric acid concentration is about 1.0 to 5.0 wt%, preferably 1.5 to It may be about 4.5 wt%.

On the other hand, the stretching step, at least one of the step of dyeing iodine and / or dichroic dye on the polyvinyl alcohol-based film and / or cross-linking the dyed iodine and / or dichroic dye to the polyvinyl alcohol-based film It may be performed together with the above steps.

For example, by performing the stretching in an aqueous solution containing iodine and / or dichroic dyes and boric acid, the dyeing, crosslinking and stretching processes can be performed simultaneously. Alternatively, after performing the dyeing step by immersing the film laminate in an aqueous solution containing iodine and / or dichroic dye before the stretching step, the film laminate with the dyeing completed is immersed in an aqueous solution of boric acid, and stretched in an aqueous solution of boric acid. By carrying out, the crosslinking step and the stretching step may be performed together.

On the other hand, the adhesion between the stretched polyvinyl alcohol-based film and the stretched base film after the stretching of the film laminate is 2N / 2cm or less, preferably, about 0.1 to 2N / 2cm, more preferably about 0.1 to 1N / 2cm. Can be. This is because when the adhesion between the stretched base film and the stretched polyvinyl alcohol film satisfies the above range, surface damage can be minimized during the separation process. According to the production method of the present invention, when the adhesive layer is formed between the polyvinyl alcohol-based film and the base film, not only the polyvinyl alcohol-based film and the base film but also the adhesive layer are stretched together. The thickness is reduced to a level of 10 to 50% compared to before stretching, and as a result, the adhesion force between the polyvinyl alcohol-based film and the base film is lowered to 2N / 2 cm or less, thereby making it easy to separate. On the other hand, the adhesive force is the adhesive force measured when the sample films of 2cm length is attached, a specific measuring method is shown in FIG. In the present invention, the adhesion between the films, as shown in Figure 1, after fixing the polyvinyl alcohol film (A) of the film laminate with a sample holder (H), with respect to the surface direction of the film laminate Peel strength measured by peeling the polyvinyl alcohol film (A) from the base film (B) by applying a force in a vertical direction, wherein the measuring instrument is a texture analyzer (Stable Micro Systems, Inc.) TA-XT Plus) was used.

On the other hand, after stretching the film laminate as described above, if necessary, further comprising the step of drying the stretched film laminate. At this time, the drying is preferably 20 to 100 ℃, more preferably about 40 to 90 ℃, it is preferably carried out for 1 to 10 minutes at the above temperature. The drying process prevents the PVA polarizer from deteriorating the physical properties of the PVA polarizer by water removal in the PVA surface and water by removing moisture from the PVA, and induces the width shrinkage of the polyvinyl alcohol film stretched during the drying process. It serves to improve the polarization degree of the polarizer by increasing the orientation of the complex composed of iodine.

After the film laminate is stretched through the above process, the first protective film is attached onto the polyvinyl alcohol-based film of the stretched film laminate. When a polyvinyl alcohol film is affixed on both surfaces of a base film, a 1st protective film can be affixed on each polyvinyl alcohol-type film.

In this case, as the first protective film, various films used in the art as a polarizer protective film or a retardation film, and a film for improving brightness may be used without limitation, for example, a polyester polymer, a styrene polymer, Cellulose polymer, polyether sulfone polymer, polycarbonate polymer, acrylic polymer, polyolefin polymer, polyamide polymer, polyimide polymer, sulfone polymer, polyether sulfone polymer, polyether ether ketone polymer, poly At least one selected from the group consisting of phenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxy methylene polymers, epoxy polymers and mixtures of these polymers This can be used. On the other hand, when a polyvinyl alcohol-type film is affixed on both surfaces of a base film, the 1st protective film attached to each polyvinyl alcohol-type film may be the same and may differ. When attaching different first protective films to both surfaces of the film laminate, there is an advantage that a polarizing plate including different protective films can be manufactured in one process.

Meanwhile, the attachment of the first protective film may be performed using an adhesive, and in this case, the adhesive may be used using an adhesive or pressure-sensitive adhesive for a polarizing plate well known in the art. At this time, the pressure-sensitive adhesive or adhesive may be appropriately selected in consideration of the material of the first protective film to be used, for example, in the case of using a cellulose-based film as the first protective film, such as a polyvinyl alcohol-based adhesive An adhesive can be used, and when an acrylic film, a cycloolefin film, etc. are used for a 1st protective film, the photocuring or thermosetting adhesives, such as an acrylic adhesive and an epoxy adhesive, can be used.

Then, the polyvinyl alcohol-based film and the base film to which the first protective film is attached are separated. The separating step may be performed by applying a weak peeling force to the polyvinyl alcohol-based film or the base film to which the first protective film is attached, thereby leaving both films. At this time, the peel force is preferably 2N / 2cm or less, for example, may be 0.1 to 2N / 2cm, 0.1 to 1N / 2cm or so. In the present invention, since the adhesion between the base film and the polyvinyl alcohol-based film is low, and the adhesive force between the first protective film and the polyvinyl alcohol-based film is relatively high compared to the adhesion between the polyvinyl alcohol-based film and the base film When a weak peel force is applied, the polyvinyl alcohol-based film and the base film are cleanly separated. In addition, since the peeling force required to separate the polyvinyl alcohol-based film and the polymer film is very weak compared to the case of lamination using a coating or co-extrusion, the two films can be easily separated without any other process or equipment. In the separation process, the damage of the polyvinyl alcohol-based film is small and shows very good optical performance.

When the separation step is completed, a polarizing plate having a first protective film attached to one surface of a polyvinyl alcohol-based film having a thickness of 10 μm or less is obtained. When a polyvinyl alcohol-type film is affixed on both surfaces of a base film, two polarizing plates can be obtained by one process. The thin polarizing plate having the first protective film attached to one surface thus obtained has a step of forming an adhesive layer on the surface on which the first protective film of the polyvinyl alcohol-based film is not attached and / or the first protective film of the polyvinyl alcohol-based film. Attaching the second protective film to this unattached surface may be further performed.

In this case, the adhesive layer forming step, the adhesive layer is one selected from the group consisting of acrylic copolymer, epoxy resin, polyurethane resin, silicone resin, polyether resin, polyamide resin and polyvinyl alcohol resin. The pressure-sensitive adhesive composition may be applied to a surface on which the first protective film of the polyvinyl alcohol-based film is not attached, and then cured by irradiation with light or heat.

Meanwhile, the second protective film attaching step may be performed by using an adhesive, and in this case, the adhesive may be performed using an adhesive or an adhesive for a polarizing plate well known in the art. At this time, the pressure-sensitive adhesive or adhesive may be appropriately selected in consideration of the material of the first protective film to be used, for example, in the case of using a cellulose-based film as the second protective film, such as a polyvinyl alcohol-based adhesive An adhesive can be used, and when an acrylic film, a cycloolefin film, etc. are used as a 2nd protective film, the photocuring or thermosetting adhesives, such as an acrylic adhesive and an epoxy adhesive, can be used.

On the other hand, as the second protective film, various films used in the art as a polarizer protective film or a retardation film can be used without limitation, for example, polyester polymer, styrene polymer, cellulose polymer, poly Ether sulfone type polymer, polycarbonate type polymer, acrylic type polymer, polyolefin type polymer, polyamide type polymer, polyimide type polymer, sulfone type polymer, poly ether sulfone type polymer, polyether ether ketone type polymer, polyphenylene sulfide type It is preferably made of one or more selected from the group consisting of polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxy methylene polymers, epoxy polymers and mixtures of these polymers. Do.

On the other hand, as described above, when the polyvinyl alcohol-based film is attached to both sides of the base film, two thin polarizing plates can be produced through one process, and the productivity is excellent, and on both sides of the film laminate In case of attaching different kinds of first protective films, there is an advantage that two kinds of products can be produced through one process.

In addition, when the adhesive layer is formed on the other surface of the polyvinyl alcohol-based film having the first protective film, a single-sided polarizing plate including the protective film may be produced on only one surface of the polyvinyl alcohol-based film. In the case of attaching, since a double-sided polarizing plate can be produced, there is an advantage that a polarizing plate of various kinds can be produced through the manufacturing method of the present invention.

On the other hand, the method of manufacturing a thin polarizing plate of the present invention as described above, sheet-to-sheet (sheet-to-sheet) process, sheet-to-roll process or roll well known in the art It may be carried out through a roll-to-roll process or the like. At this time, the sheet-to-sheet process is a method using a sheet-like film cut to a predetermined size with a raw film (ie, polyvinyl alcohol-based film, base film, protective film, etc.), the sheet-to-roll process As a raw material film, the roll type film by which the long film was wound is used, and the other raw material film says the method of using the sheet | leaf type film cut | disconnected to a fixed size. In addition, a roll-to-roll process is a method of using a rolled film as a raw film. In view of the continuity and productivity of the process, it is particularly preferred to use a roll-to-roll process among these.

For example, in the polarizing plate manufacturing method of the present invention, the base film and the polyvinyl alcohol-based film have an adhesion force of 2 N / 2 cm or less while unwinding the polyvinyl alcohol-based film and the base film from the base film roll and the polyvinyl alcohol-based film roll. Attaching using an attractive force or an adhesive to form a film laminate, and stretching the film laminate; Attaching the first protective film unrolled from the first protective film roll onto the polyvinyl alcohol-based film of the stretched film laminate; And separating the polyvinyl alcohol-based film and the base film to which the first protective film is attached.

At this time, the base film and the polyvinyl alcohol-based film is attached, and then re-wound in a roll shape, then unwind the film laminate from the re-wound film laminate roll may be introduced into the stretching process, or without rewinding It can be directly put into the stretching process.

In addition, in the separating step, a peeling means (for example, a peeling roll) is inserted between the base film and the polyvinyl alcohol-based film to separate the interface between the base film and the polyvinyl alcohol-based film, and then separated from the base film. It can be carried out by a method of winding the polyvinyl alcohol-based film in a roll with each other.

Thus, when manufacturing a polarizing plate by a roll-to-roll system, a long rolled polarizing plate can be obtained.

The polarizing plate of the present invention prepared by the above method has a thickness of 10 μm or less, for example, 1 μm to 10 μm, 3 μm to 10 μm, or 1 μm to 5 μm polyvinyl alcohol polarizer; And a first protective film attached to one surface of the polyvinyl alcohol polarizer, and, if necessary, further include an adhesive layer and / or a second protective film on an opposite surface of the surface on which the first protective film is attached. Can be.

Even if the polarizing plate of the present invention has a thin thickness, the unitary transmittance is about 40 to 45%, and the polarization degree is 99.0% or more, 99.5% or more, more preferably 99.7% or more, and is excellent in optical characteristics.

Moreover, the polarizing plate of this invention is excellent also in the uniformity of the polarization degree to the width direction. Specifically, in the polarizing plate of the present invention, the standard deviation of the degree of polarization measured at ten points positioned at equal intervals along the width direction of the polarizing plate is 0.002% or less.

In addition, the polarizing plate of the present invention hardly generates curl, and has excellent flatness. More specifically, when the polarizing plate of the present invention is placed on a flat surface, the distance between the four corners of the polarizing plate and the bottom surface is measured, and the arithmetic mean value of the measured values is obtained, the value is very flat to 5 mm or less. Have

On the other hand, the polarizing plate of the present invention, in addition to the first protective film, the second protective film or the adhesive layer may further include other functional optical layer, such as brightness enhancement film, primer layer, hard coating layer, anti-glare layer or anti-reflection layer. have. The formation method of these optical layers is not specifically limited, The well-known method well known in the art can be used.

The polarizing plate of the present invention has a very thin thickness compared to the conventional polarizing plate and has excellent optical properties, and thus may be usefully used in display devices such as liquid crystal display panels and organic light emitting display devices.

Example 1

After attaching the PVA film to both sides of the 60-μm-thick thermoplastic polyurethane substrate through attraction, a laminate was formed, and a thin polarizer manufacturing experiment was conducted through a wet stretching process. As the PVA film, M3000 grade 30 μm PVA was used. The PVA film was subjected to a swelling process in a 25 ° C. pure solution for 15 seconds, followed by a dyeing process for 60 seconds in a 0.3 wt% concentration and a 25 ° C. iodine solution. Thereafter, after washing for 15 seconds in a solution of 1 wt% boric acid and 25 ° C., a 7-fold stretching process was performed in a solution of 2.5 wt% boric acid and 52 ° C. After stretching, the process was complementary in a 5 wt% KI solution, followed by drying in an 80 ° C. oven for 5 minutes. After drying, the thickness of the PVA film was about 6-8 micrometers. After the drying process, 40 μm triacetyl cellulose (TAC) film was placed on each side of the PVA polarizer attached to both sides of the substrate, laminated with a laminator through a PVA-based water-soluble adhesive, and dried in an 80 ° C. oven for 5 minutes. Thereafter, the PVA polarizer having the TAC laminated on one side was peeled off from both sides of the substrate to secure the PVA polarizer having the TAC attached to one side. And place a 40㎛ triacetyl cellulose (TAC) film on the other side of the PVA polarizer without TAC attached, laminated with a laminator through a PVA-based water-soluble adhesive and dried for 5 minutes in an 80 ℃ oven TAC / PVA / TAC A thin polarizing plate of the structure was prepared.

Comparative Example 1

PVA film (M-grade, Nippon Synthetic Co., Ltd., average polymerization degree: 2400 average saponification degree: 99mol%) was dissolved in 100 ° C pure water to form a PVA aqueous solution, and then a lip coater was placed on a 200 μm-thick PET (NOVA-Clear SG007 grade of MCC). It was coated using and dried for 10 minutes in an oven at 80 ℃ to form a laminated film. At this time, the thickness of the said PVA film was 10 micrometers. The laminated film was subjected to a swelling process for 15 seconds in a 25 ° C. pure solution, followed by a dyeing process for 60 seconds in a 0.3 wt% concentration and a 25 ° C. iodine solution. Thereafter, 1 wt% boric acid and a washing process for 15 seconds in a 25 ℃ solution, and then a 5.5-fold stretching process in a boric acid 2.5 wt%, 52 ℃ solution. After stretching, the process was complementary in a 5 wt% KI solution, followed by drying in an 80 ° C. oven for 5 minutes. However, during the stretching process, the PVA coating layer was peeled off, making it impossible to produce a thin PVA film. 2 shows the state of the film laminate produced according to the method of Comparative Example 1.

Comparative Example 2

PVA film (M-grade, Nippon Synthetic Co., Ltd., average polymerization degree: 2400 average saponification degree: 99mol%) was dissolved in 100 ° C pure water to form a PVA aqueous solution, and then a lip coater was placed on a 200 μm-thick PET (NOVA-Clear SG007 grade of MCC). It was coated using and dried for 10 minutes in an oven at 80 ℃ to form a laminated film. At this time, the thickness of the said PVA film was 10 micrometers. The laminated film was subjected to a swelling process in a 1.0 wt% aqueous solution of boric acid at 25 ° C. for 15 seconds, followed by a dyeing process for 60 seconds in a 0.3 wt% iodine concentration, 3.0 wt% boric acid concentration, and a 25 ° C. iodine solution. Thereafter, 1 wt% boric acid and a washing process for 15 seconds in a 25 ℃ solution, and then a 5.5-fold stretching process in a boric acid 2.5wt%, 60 ℃ solution. After stretching, the process was complementary in a 5 wt% KI solution, followed by drying in an oven at 100 ° C. for 8 minutes. The thickness of the PVA film after drying was about 4-4.5 micrometers. After the drying process, 40 μm triacetyl cellulose (TAC) film was placed on each side of the PVA polarizer attached to both sides of the substrate, laminated with a laminator through a PVA-based water-soluble adhesive, and dried in an 80 ° C. oven for 5 minutes. Thereafter, the PVA polarizer having the TAC laminated on one side was peeled off from both sides of the substrate to secure the PVA polarizer having the TAC attached to one side. And place a 40㎛ triacetyl cellulose (TAC) film on the other side of the PVA polarizer without TAC attached, laminated with a laminator through a PVA-based water-soluble adhesive and dried for 5 minutes in an 80 ℃ oven TAC / PVA / TAC A thin polarizing plate of the structure was prepared. The optical properties of the prepared thin polarizing plate were measured with a JASCO V-7100 Spectrophotometer.

Comparative Example 3

Without using a base material, Japan Synthetic Co., Ltd. M3000 grade 30㎛ PVA film used in the Example was stretched alone 6 times under the same stretching conditions as the process conditions of Example to finally prepare a polarizing device having a thickness of 13㎛. A 40 μm triacetyl cellulose (TAC) film was placed on both sides of the polarizer, and laminated with a laminator through a PVA-based water-soluble adhesive, followed by drying in an oven at 80 ° C. for 5 minutes to prepare a polarizing plate having a TAC / PVA / TAC structure. .

Comparative Example 4

Without using a base material, Nippon Synthetic M6000 grade 60 μm PVA film used in the examples was stretched alone 6 times under the same stretching conditions as in the process conditions of the example to finally prepare a general polarizer having a thickness of 22 μm. A 40 μm triacetyl cellulose (TAC) film was placed on both sides of the polarizer, and laminated with a laminator through a PVA-based water-soluble adhesive, followed by drying in an oven at 80 ° C. for 5 minutes to prepare a polarizing plate having a TAC / PVA / TAC structure. .

Experimental Example 1 Comparison of Optical Properties

The simple transmittance (Ts), orthogonal transmittance (Tc), polarization degree (DOP), simple colors a, b, and orthogonal colors a and b of the thin polarizing plate prepared in Example 1 and the thin polarizing plate prepared in Comparative Example 2 It was measured with a JASCO V-7100 Spectrophotometer. The measurement results are shown in the following [Table 1].

Table 1

	Ts (%)	Tc (%)	DOP (%)	Group colors		Orthogonal colors
				a	b	a	b
Example	42.55	0.0647	99.8275	-0.03	2.05	2.40	-1.41
Comparative Example 2	34.97	0.1259	99.4971	-0.07	0.56	2.12	-3.01

According to the above [Table 1], in the case of the Example, although the transmittance (Ts) is higher than Comparative Example 2, it can be seen that it has a better optical performance by showing a higher degree of polarization results.

On the other hand, when manufacturing a thin polarizer in a coating method under the same manufacturing process conditions as in Example 1, as shown in Figure 2, the coated PVA film is peeled off, it was impossible to manufacture the thin polarizer itself. As in Comparative Example 2, when boric acid is added in the swelling and dyeing process and the stretching temperature is increased, the PVA film may be manufactured by using a coating method, but a decrease in transmittance was involved. It was not possible to produce a polarizer satisfying the condition of more than 99.0% of the degree of polarization at the transmittance of 40 to 43%.

Experimental Example 2-Curling Property Comparison

Curl characteristics of the polarizing plates produced by Example, Comparative Example 3 and Comparative Example 4 were visually observed. 3 shows a photograph of each polarizer. 3, in the case of the polarizing plates manufactured by Examples, it can be confirmed that the curl is less than that of the polarizing plates prepared by Comparative Examples 3 and 4.

Experimental Example 3-Evaluation of Uniformity of Polarization Degree

For each of the polarizers prepared by Example 1 and Comparative Example 2, the polarization degree was measured at ten points located at equal intervals along the width direction of the polarizer, and then the standard deviation value of the measured polarization degree was calculated. Polarization degree was measured by JASCO V-7100 Spectrophotometer. The measurement results are shown in the following [Table 2].

TABLE 2

location	% Polarization
	Example 1	Comparative Example 2
One	99.8284	99.5641
2	99.8263	99.4421
3	99.8255	99.4336
4	99.8279	99.4832
5	99.8293	99.6104
6	99.8291	99.5826
7	99.8281	99.4859
8	99.8272	99.4091
9	99.8256	99.4426
10	99.8271	99.5173
Average	99.8275	99.4971
Standard Deviation	0.0014	0.0692

Example 2

A 4% by weight aqueous solution was prepared by dissolving polyvinyl alcohol (average degree of polymerization 2000, degree of 94%, Japanese Synthetic) containing acetacetyl group (5% by weight) in pure water. Titanium amine complex crosslinking agent (product name: TYZOR TE, DuPont) was added in a ratio of 6.7 parts by weight per 100 parts by weight of polyvinyl alcohol and mixed with stirring to prepare an adhesive A.

After applying the adhesive A on both sides of a 40 μm-thick thermoplastic polyurethane substrate, M2000 grade 20 μm PVA film manufactured by Nippon Synthetic Fiber was laminated and passed through a laminator to form a film laminate. The prepared film laminate was swelled in a 25 ° C. pure solution for 15 seconds and then dyed for 60 seconds in a 0.3 wt% concentration and 25 ° C. iodine solution. Thereafter, after washing for 15 seconds in a solution of 1 wt% boric acid and 25 ° C., a 7-fold stretching process was performed in a solution of 2.5 wt% boric acid and 52 ° C. After stretching, the process was complementary in a 5 wt% KI solution, followed by drying in an 80 ° C. oven for 5 minutes. After drying, the thickness of the PVA film was about 7.5 μm. After the drying process, 40 μm triacetyl cellulose (TAC) film was placed on each side of the PVA polarizer attached to both sides of the substrate, laminated with a laminator through a PVA-based water-soluble adhesive, and dried in an 80 ° C. oven for 5 minutes. Thereafter, the PVA polarizer with TAC laminated on one side was peeled off from both sides of the base film with a peel force of 0.7 N / 2 cm to obtain a PVA polarizer with TAC attached to one side. And place a 40㎛ triacetyl cellulose (TAC) film on the other side of the PVA polarizer without TAC attached, laminated with a laminator through a PVA-based water-soluble adhesive and dried for 5 minutes in an 80 ℃ oven TAC / PVA / TAC A thin polarizing plate of the structure was prepared.

Comparative Example 5

After applying a polyvinyl alcohol-based adhesive (trade name: JC25, manufacturer: JAPAN VAM & POVAL Co., Ltd.) of commercially available solid content of 4 wt% on both sides of a 40 μm-thick thermoplastic polyurethane substrate, M2000 grade 20 μm of Japan Synthetic The PVA film was laminated and passed through a laminator to form a film laminate. The prepared film laminate was swelled in a 25 ° C. pure solution for 15 seconds and then dyed for 60 seconds in a 0.3 wt% concentration and 25 ° C. iodine solution. Thereafter, after washing for 15 seconds in a solution of 1 wt% boric acid and 25 ° C., a stretching process was performed 7 times in a solution of 2.5 wt% boric acid and 52 ° C., but breakage occurred during stretching.

Comparative Example 6

After applying a polyvinyl alcohol-based adhesive (trade name: JC25, manufacturer: JAPAN VAM & POVAL Co., Ltd.) of commercially available solid content of 4 wt% on both sides of a 40 μm-thick thermoplastic polyurethane substrate, M2000 grade 20 μm of Japan Synthetic The PVA film was laminated and passed through a laminator to form a film laminate. The prepared film laminate was swelled in a 25 ° C. pure solution for 15 seconds and then dyed for 60 seconds in a 0.3 wt% concentration and 25 ° C. iodine solution. Thereafter, 1 wt% of boric acid was washed for 15 seconds in a solution of 25 ° C., followed by 6 times stretching in a solution of 2.5 wt% of boric acid and a 52 ° C., followed by a complementary process in a KI solution of 5 wt%, and dried in an 80 ° C. oven for 5 minutes. .

In this case, no breakage occurred in the stretching and washing step, but a phenomenon in which the side part of the film laminate dried after the stretching occurred. Figure 4 is a photograph showing the state of the film laminate after stretching of Comparative Example 6. On the other hand, Figure 5 is a photograph showing the state of the film laminate after stretching of Example 2. As shown in FIGS. 4 and 5, the film laminate of Comparative Example 6 had side curl after stretching, whereas this phenomenon did not occur in the film laminate of Example 2. FIG.

[Description of the code]

H: Holder

A: polyvinyl alcohol film

B: base film

MD: Longitudinal stretching direction

Claims (20)

1. Attaching the unstretched polyvinyl alcohol-based film on the unstretched base film using attraction or an adhesive to form a film laminate;

   Stretching the film laminate;

   Attaching a first protective film on the polyvinyl alcohol-based film of the stretched film laminate; And

   The method of manufacturing a thin polarizing plate comprising the step of separating the polyvinyl alcohol-based film and the base film to which the first protective film is attached.
2. The method of claim 1,

   The unstretched polyvinyl alcohol-based film has a thickness of 10㎛ to 60㎛ manufacturing method of a thin polarizing plate.
3. The method of claim 1,

   The adhesive is a method for producing a thin polarizing plate which is an adhesive comprising a polyvinyl alcohol-based resin containing an acetacetyl group and an amine-based metal compound crosslinking agent.
4. The method of claim 1,

   The stretching of the film laminate is a method of producing a thin polarizing plate is carried out at a temperature of 20 ℃ to 85 ℃.
5. The method of claim 1,

   The stretching of the film laminate may be performed by dry stretching or wet stretching.
6. The method of claim 1,

   The stretching of the film laminate is a method of producing a thin polarizing plate is carried out in boric acid aqueous solution of boric acid concentration of 1% by weight to 5% by weight.
7. The method of claim 1,

   The stretching of the film laminate may be performed such that the thickness of the polyvinyl alcohol-based film is 10 μm or less.
8. The method of claim 1,

   The stretching of the film laminate may be performed at a draw ratio of 5 to 15 times.
9. The method of claim 1,

   Separating the polyvinyl alcohol-based film and the base film with the protective film is a method of manufacturing a thin polarizing plate is performed by applying a peel force of 2N / 2cm or less.
10. The method of claim 1,

    And dyeing at least one of iodine and dichroic dye on the film laminate before the stretching of the film laminate.
11. The method of claim 1,

    And drying the stretched film laminate after the stretching of the film laminate.
12. The method of claim 1,

    After separating the polyvinyl alcohol-based film and the base film to which the protective film is attached, a thin polarizing plate further comprising the step of attaching a second protective film on the surface of the polyvinyl alcohol-based film is not attached to the protective film Method of preparation.
13. The method of claim 1,

    After the step of separating the polyvinyl alcohol-based film and the base film to which the protective film is attached, the manufacturing of a thin polarizing plate further comprising the step of forming an adhesive layer on the surface is not attached to the protective film of the polyvinyl alcohol-based film Way.
14. The method of claim 1,

    The base film is a method of producing a thin polarizing plate is a film having a maximum draw ratio of 5 times or more in the temperature range of 20 ℃ to 85 ℃.
15. The method of claim 1,

    The base film may be a high density polyethylene film, polyurethane film, polypropylene film, polyolefin film, ester film, low density polyethylene film, high density polyethylene and low density polyethylene coextrusion film, copolymer resin containing ethylene vinyl acetate in high density polyethylene, acrylic A method for producing a thin polarizing plate comprising at least one member selected from the group consisting of a film, a polyethylene terephthalate film, a polyvinyl alcohol film and a cellulose film.
16. The method of claim 1,

    The first protective film is a polyester polymer, a styrene polymer, a cellulose polymer, a polyether sulfone polymer, a polycarbonate polymer, an acrylic polymer, a polyolefin polymer, a polyamide polymer, a polyimide polymer, a sulfone polymer , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxy methylene polymer, epoxy A method for producing a thin polarizing plate, which is produced from one or more selected from the group consisting of a series polymer and a mixture of these polymers.
17. The method of claim 12,

    The second protective film is a polyester polymer, a styrene polymer, a cellulose polymer, a polyether sulfone polymer, a polycarbonate polymer, an acrylic polymer, a polyolefin polymer, a polyamide polymer, a polyimide polymer, a sulfone polymer , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxy methylene polymer, epoxy A method for producing a thin polarizing plate, which is produced from one or more selected from the group consisting of a series polymer and a mixture of these polymers.
18. Polyvinyl alcohol polarizer having a thickness of 10 μm or less; And

    It includes a first protective film attached to one surface of the polyvinyl alcohol polarizer,

    Thin polarizing plate having a single transmittance of 40% to 45% and a polarization degree of 99.0% or more.
19. The method of claim 18,

    A thin polarizing plate having a standard deviation of the degree of polarization measured at ten points at equal intervals along the width direction of the thin polarizing plate of 0.002% or less.
20. The method of claim 18,

    The arithmetic mean of the distances between the four edges and the bottom surface of the polarizing plate measured with the thin polarizing plate on a flat surface is 5 mm or less.

Images