TW201525537A - Polarizing plate and liquid crystal display device having the same - Google Patents

Abstract

Provided is a cellulose acylate film for being used as an optical film, and more particularly, a cellulose acylate film used to manufacture a polarizing plate.

Description

Polarizing plate and liquid crystal display device having the same [Priority statement]

The present application claims the priority of the Korean Patent Application No. 10-2013-0160936, filed on Dec.

The following disclosure relates to a polarizing plate comprising a cellulose acylate film and an acrylic film, and a liquid crystal display device having the polarizing plate.

The polarizing plate generally has a structure in which a polarizer and a protective film are stacked using an aqueous adhesive layer made of a polyvinylalcohol based aqueous solution. As the polarizer, a polyvinyl alcohol film is generally used, and as the protective film, a triacetyl cellulose film (hereinafter, referred to as "TAC film") is used.

In the TAC film, the plane of the existing (in-plane) R _e and retardation in the thickness direction (thickness direction) of the retardation R _th line depends on ambient temperature and high-humidity environment significantly changed, and particularly, The change in the phase difference of the incident light in the inclined direction is large.

In the case where a polarizing plate having such a stacked structure is used under conditions of high temperature and high humidity for a long period of time, the degree of polarization may be deteriorated, the polarizer and the protective film may be separated from each other, or optical characteristics may be changed.

Further, in the case where a polarizing plate including a TAC film having the above characteristics as a protective film is applied to a liquid crystal display device, the characteristics of the view angle are changed depending on changes in ambient temperature and humidity environment, so that image quality may be deteriorated. .

As a material for compensating for various disadvantages of the above TAC film, it is known as an acrylic resin, but the acrylic resin does not have sufficient heat resistance, and has an in-plane retardation and a thickness direction retardation after stretching, making the acrylic resin unsuitable for use. As a protective film.

In order to solve this problem, a technique for reducing the thermal expansion coefficient (CTE) of an acrylic resin to a CTE similar to that of a TAC film by adjusting the molecular weight of the acrylic copolymer resin to cause formation of a glutaric anhydride structure has been disclosed in Korean Patent Early Public Publication No. 10-2012-0116840 (October 23, 2012).

A related art using an acrylic resin instead of a TAC film relates to a method of preparing an acrylic copolymer resin which hardly produces an in-plane phase difference and a thickness direction retardation after stretching, a photoelastic coefficient It is small and excellent in heat resistance, and can be used as a protective film for a polarizer.

The coefficient of thermal expansion (CTE) means that each unit temperature is in length, area, Or a change in volume, and the coefficient of linear thermal expansion is as defined below.

In general, conventional CTE is adjusted by stretching a film, but there is a limit in increasing the CTE of the TAC film by stretching, and there has been a demand for development of an additive for increasing CTE.

[prior technical paper] [Patent Document]

Korean Patent Early Publication No. 10-2012-0116840 (October 23, 2012)

An embodiment of the present invention is directed to providing a polarizing plate capable of reducing the occurrence of curl by increasing the thermal expansion coefficient of a cellulose oxide film to be similar to the coefficient of thermal expansion of a film using an acrylic resin. A specific additive is used to adjust the stretching rate.

Another embodiment of the present invention is directed to providing a method of making a film that adjusts the coefficient of thermal expansion of a cellulose film to be similar to the coefficient of thermal expansion of an acrylic film and provides an additive for use in manufacturing This film.

Another embodiment of the present invention is directed to providing a liquid crystal display device having the polarizing plate.

The present inventors have made efforts to suppress the occurrence of curl after the production of a polarizing plate by adjusting the thermal expansion coefficient of the cellulose oxide film so as to be made with the acrylic resin film. The coefficient of thermal expansion was similar, and it was found that the generation of the curl was suppressed by adjusting the additive and the expansion conditions within a specific range to adjust the thermal expansion coefficient of the cellulose oxide film, thereby completing the present invention.

In a general aspect, a polarizing plate comprises a deuterated cellulose film, a polarizer, and an acrylic film, and the systems are sequentially stacked, wherein a thermal expansion coefficient of the deuterated cellulose film and the acrylic film are The coefficient of thermal expansion satisfies Equations 1 and 2 below: (In Equation 1, CTE _ca is the coefficient of thermal expansion of the deuterated cellulose film in the transverse direction (TD), and CTE _ac is the coefficient of thermal expansion of the acrylic film).

[Equation 2] CTE _td > CTE _md (In Equation 2, CTE _td is a coefficient of thermal expansion (ppm/K) in the transverse direction (TD), and CTE _md is a coefficient of thermal expansion in the machine direction (MD) ( Ppm/K)).

In another general aspect, a liquid crystal display device includes a polarizing plate as described above.

Hereinafter, an aspect of the polarizing plate according to the present invention will be explained, but The invention is not limited to this.

In one aspect of the invention, a polarizing plate comprises a deuterated cellulose film, a polarizer, and an acrylic film, and the systems are sequentially stacked, wherein the thermal expansion coefficient of the deuterated cellulose film and the acrylic acid The coefficient of thermal expansion of the film satisfies Equations 1 and 2 below: (In Equation 1, CTE _ca is the coefficient of thermal expansion of the deuterated cellulose film in the transverse direction (TD), and CTE _ac is the coefficient of thermal expansion of the acrylic film).

[Equation 2] CTE _td > CTE _md (In Equation 2, CTE _td is the coefficient of thermal expansion (ppm/K) in the transverse direction (TD), and CTE _md is the coefficient of thermal expansion in the machine direction (MD) (ppm/K) )).

In the case of manufacturing a polarizing plate, in the case of using a deuterated cellulose film as a protective film, since a change in phase difference is caused under conditions of high temperature and high humidity, in order to solve this problem, a cellulose film and acrylic acid are prepared. The film systems are laminated with each other and then used. However, there is a problem in that after the polarizing plate is manufactured, curling occurs due to a difference in thermal expansion coefficient between the acrylic film and the cellulose-deposited film. Since the thermal expansion coefficient of the acrylic film is about 70 to 75 ppm/K, and the coefficient of thermal expansion of the unstretched triacetyl cellulose film is about 50 to 65 ppm/K, the inventors have studied to adjust the thermal expansion of the cellulose film. The coefficient is such that it is similar to the coefficient of thermal expansion of the acrylic film to avoid the occurrence of curl.

Thus, it can be evaluated that the generation of curl can be suppressed in the range in which the coefficient of thermal expansion of the cellulose-deposited film and the coefficient of thermal expansion of the acrylic film satisfy the equation 1. However, even if the coefficient of thermal expansion satisfies Equation 1, curling may occur in some cases.

Therefore, by carrying out the results obtained by the experiment of changing the conditions of the extension and the additive, the inventors have found that in the range in which the coefficient of thermal expansion of the cellulose-deposited film satisfies the following Equation 2, the generation of curl can be avoided. This achieves the invention.

[Equation 2] CTE _td > CTE _md (In Equation 2, CTE _td is the coefficient of thermal expansion (ppm/K) in the transverse direction (TD), and CTE _md is the coefficient of thermal expansion in the machine direction (MD) (ppm/K) )).

That is, in the present invention, it is confirmed that the coefficient of thermal expansion of the cellulose-deposited film and the acrylic film satisfies the range of Equation 1, and at the same time, the coefficient of thermal expansion of the cellulose-deposited film in the transverse direction is greater than The coefficient of thermal expansion in the longitudinal direction suppresses the generation of curl.

More preferably, the coefficient of thermal expansion satisfies the following Equation 3.

[Equation 3] CTE _{td -} CTE _md > 3ppm/K (in Equation 3, CTE _td is the coefficient of thermal expansion (ppm/K) in the transverse direction (TD), and the thermal expansion coefficient of CTE _md in the machine direction (MD) (ppm/K)).

More preferably, the coefficient of thermal expansion may satisfy the following Equation 4, and may exhibit more excellent physical properties.

[Equation 4] CTE _{td -} CTE _md > 15 ppm / K (in Equation 4, CTE _td is a coefficient of thermal expansion in the transverse direction (TD), and CTE _md is a coefficient of thermal expansion in the machine direction (MD)).

More preferably, the coefficient of thermal expansion satisfies the following Equation 5, and may exhibit more excellent physical properties.

[Equation 5] CTE _{td -} CTE _md > 35 ppm / K (in Equation 5, CTE _td is a coefficient of thermal expansion in the transverse direction (TD), and CTE _md is a coefficient of thermal expansion in the machine direction (MD).)

In one aspect of the present invention, when the thermal expansion coefficient of the cellulose-deposited film in the transverse direction is in the range of 60 to 105 ppm/K, in the case where the cellulose-deposited film and the acrylic film are laminated to each other, it is possible Does not produce curl. When the coefficient of thermal expansion is preferably in the range of 60 to 95 ppm/K, more preferably in the range of 65 to 90 ppm/K, since the coefficient of thermal expansion of the cellulose-deposited film is similar to the coefficient of thermal expansion of the acrylic film, it may exhibit superiority. effect.

The cellulose-degraded cellulose film according to the present invention may contain a deuterated cellulose resin as a base resin and one or two or more selected from the compounds represented by the following Chemical Formulas 1 to 3, thereby possibly adjusting the thermal expansion. The coefficient is within the desired range:

The deuterated cellulose resin used in the present invention is cellulose and acetic acid. The ester, all or a part of the hydrogen atoms of the hydroxyl group present at the positions 2, 3, and 6 of the glucose unit constituting the cellulose may be selected from an ethyl fluorenyl group, a propyl group, and a butyl group. Any one or two or more of the groups are substituted. More preferably, a deuterated cellulose resin in which all or a part of hydrogen atoms of the hydroxyl group at the positions 2, 3, and 6 of the glucose unit constituting the cellulose are substituted with an ethyl thio group may be used. Specific examples thereof include diacetyl cellulose, triethyl cellulose, and the like.

Degree of substitution of deuterated cellulose resin It is not limited but may preferably be from 2.0 to 3.0, more preferably from 2.5 to 2.9. The degree of substitution can be measured according to ASTM D-817-91. The molecular weight range of the deuterated cellulose resin is not limited, but its weight average molecular weight is preferably in the range of 200,000 to 350,000. Further, the molecular weight distribution Mw/Mn (Mw-based weight average molecular weight, and Mn coefficient amount average molecular weight) of the deuterated cellulose resin is preferably from 1.4 to 1.8, and more preferably from 1.5 to 1.7.

The compounds represented by Chemical Formulas 1 to 3 are used to adjust the coefficient of thermal expansion, And its content is not limited. As a specific example, it may be represented by Chemical Formulas 1 to 3 The compound is, based on 100 parts by weight of the deuterated cellulose resin, the total content of the compounds is 0.1 to 20 parts by weight, and the compound represented by Chemical Formula 1, the compound represented by Chemical Formula 2, and the compound represented by Chemical Formula 3 The mixing weight ratio is from 1 to 2:1 to 1.5:1.

Preferably, the cellulose-degraded cellulose film according to the present invention is used by a It is prepared by solvent casting of a cellulose dope solution. In the solvent casting method, a film is formed by casting a solution (doping solution) in which a deuterated cellulose resin is dissolved in a solvent onto a support and evaporating the solvent.

As a raw material of the deuterated cellulose doping solution, it is preferred to use bismuth chemical fiber Vitamin particles. In this case, preferably 90% by weight of the deuterated cellulose particles have an average particle size of from 0.5 to 5 mm. Further, it is preferred that at least 50% by weight of the deuterated cellulose particles have an average particle size of from 1 to 4 mm.

Preferably, the deuterated cellulose particles have a shape as close as possible to a sphere Preferably, the doping solution is prepared after drying the deuterated cellulose particles to have a water content of 2% by weight or less, more preferably 1% by weight or less.

In the cellulose-doped solution for solvent casting, according to Various types of additives may be added during the separate preparation process, for example, plasticizers, ultraviolet (UV) inhibitors, deterioration inhibitors, fine particles, peeling agents, infrared (IR) absorbers, An optically anisotropic controller or the like. The specific type of such an additive is not particularly limited as long as it is generally used in the art, and its content may be within a range in which the physical properties of the film are not deteriorated. The point in time at which the additive is added depends on the type of the additive. Add these additions The process of the addition can be carried out at the end of the preparation of the dope solution.

Plasticizers are used to improve the mechanical strength of the film, and in the use of plasticizers In this case, the drying process time of the film can be reduced. Any plasticizer may be used without limitation as long as it is usually used, and examples of the plasticizer may include a phosphoric acid ester, a carboxylic acid selected from a phthalic acid ester or a citrate ester. A carboxylic acid ester or the like. Examples of the phosphate ester may include triphenyl phosphate (TPP), 4-biphenyldiphenyl phosphate, tricresyl phosphate (TCP), and the like. Examples of the phthalic acid ester may include dimethyl phthalate (DMP), diethyl decanoate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), and diphenyl phthalate. Ester (DPP), diethylhexylphthalate (DEHP), and the like. Examples of the citric acid ester may include o-acetyltriethylcitrate (OACTE), o-acetyl tributyl citrate (OACTB), and the like. Examples of the other carboxylate may include butyl oleate, methyl acetyl lysine oleate, dibutyl sebacate, and various trimellitic acid esters. . Preferably, a phthalate ester (DMP, DEP, DBP, DOP, DPP, and DEHP) plasticizer can be used. The content of the plasticizer may be 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the deuterated cellulose resin.

Examples of UV inhibitors may include hydroxydiphenylketone (hydroxy) An benzophenone-based compound, a benzotriazole-based compound, a salicylic acid ester-based compound, a cyanoacrylate-based compound, and the like. Based on 100 parts by weight of deuterated cellulose The content of the resin, UV inhibitor may be from 0.1 to 3 parts by weight, more preferably from 0.5 to 2 parts by weight.

Examples of the deterioration inhibitor may include an antioxidant, a peroxide decomposing agent (peroxide decomposer), a free radical inhibitor, a metal deactivator, a deoxidizing agent, a light stabilizer (hindered amine, etc.), and the like. In particular, preferred examples of the deterioration inhibitor may include butylated hydroxy toluene (BHT) and tribenzylamine (TBA). The content of the deterioration inhibitor may be from 0.01 to 5 parts by weight, more preferably from 0.1 to 1 part by weight, based on 100 parts by weight of the deuterated cellulose resin.

Depressing the curl of the film as desired and advantageously maintaining the transport properties The (conveyance property), the fine particles added to prevent adhesion in the shape of the roll, or the scratch resistance may be selected from any one of an inorganic compound and an organic compound. For example, preferred examples of the inorganic compound may include cerium, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, cerium oxide, zirconium oxide, cerium oxide, cerium oxide, tin oxide, tin-cerium oxide, calcium carbonate. , talc, clay, calcined kaolin, calcined calcium citrate, hydrated calcium citrate, aluminum citrate, magnesium citrate, calcium phosphate and the like. More preferably, an inorganic compound containing cerium, zirconia or the like can be used. The fine particles have an average primary particle size of 80 nm or less, preferably 5 to 80 nm, and more preferably 5 to 60 nm, and most preferably 8 to 50 nm. In the case where the average primary particle is larger than 80 nm, the surface smoothness of the film may be damaged.

In addition, a wavelength dispersion regulator can be further added as needed (wavelength dispersion regulator) and the like. These additives may be used without limitation as long as they are generally used in the respective fields.

In addition, an optional retardation additive may be further added to increase or decrease the retardation as needed. Any of the delay additives can be used without limitation as long as it is generally used to adjust the retardation in the corresponding art. In general, a cellulose-degraded cellulose film to be applied to a VA module liquid crystal display device may contain an additive for increasing retardation, and a cellulose-degraded cellulose film to be applied to an IPS module liquid crystal display device may have a decrease. Delay additive. The content of the retardation additive in the film ranges from 1 to 15% by weight, more preferably from 3 to 10% by weight, and has excellent compatibility with the compound represented by Chemical Formula 1, so that a bleeding phenomenon does not occur and High quality images can be implemented.

Next, a method of manufacturing a cellulose oxide film according to the present invention will be explained. In order to produce a deuterated cellulose film according to the present invention, the following deuterated cellulose composition (that is, a doping solution) was prepared.

The deuterated cellulose composition according to an exemplary embodiment of the present invention may contain the compound represented by Chemical Formulas 1 to 3 such that the total content of the compounds is 0.1 to 20 by weight based on 100 parts by weight of the deuterated cellulose resin. Share. Further, the compounding weight ratio of the compound represented by Chemical Formula 1, the compound represented by Chemical Formula 2, and the compound represented by Chemical Formula 3 may be from 1 to 2:1 to 1.5:1. Further, the deuterated cellulose composition may further contain an additive as needed.

In the present invention, the doping solution may have a solid concentration of 15 to 25% by weight, preferably 16 to 23% by weight. In the case where the solid concentration of the doping solution is less than 15% by weight, the fluidity is too high, making it difficult to form a film, and in the case where the solid concentration is more than 25% by weight, it is difficult to completely dissolve the solid component.

In one aspect of the invention, the bismuth fiber is based on the total solids content The content of the plain resin may be 70% by weight or more, preferably 70 to 90% by weight, and more preferably 80 to 85% by weight. Further, deuterated cellulose can be used by mixing two or more kinds of deuterated cellulose having different degree of substitution, degree of polymerization, or molecular weight distribution from each other.

In the case of producing a film by a solvent casting method, it is used for preparing ruthenium The solvent of the cellulose composition (doping solution) is preferably an organic solvent. As the organic solvent, a halogenated hydrocarbon is preferably used, and examples of the halogenated hydrocarbon include a chlorinated hydrocarbon, methylene chloride, and chloroform. Among them, dichloromethane is the best.

Further, a solvent obtained by mixing an organic solvent of a non-halogenated hydrocarbon may be used as needed. Examples of the organic solvent of the non-halogenated hydrocarbon may include esters, ketones, ethers, alcohols, and hydrocarbons. Examples of the ester may include methyl formate, ethyl formate, propyl formate, amyl formate, methyl acetate, ethyl acetate, amyl acetate, and the like, and examples of the ketone may include acetone, methyl ethyl ketone, diethyl ketone, and diiso Butyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, etc., examples of the ether may include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-two Alkane (1,4-dioxane), 1,3-dioxolane, tetrahydrofuran, anisole, phenethylol, etc., and examples of the alcohol may include Methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, 2 - fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like.

More preferably, dichloromethane can be used as the main solvent, and alcohol can be used as the main solvent. Sub-solvent. Specifically, dichloromethane and alcohol can be mixed in a weight ratio of 80:20 to 95:5. Then use it.

Preparation of bismuth chemical fiber according to room temperature, high temperature, or low temperature dissolution method Vitamin composition.

The viscosity of the deuterated cellulose composition is preferably from 1 to 400 Pascal at 40 ° C. (Pa.s), preferably 10 to 200 Pascals.

The deuterated cellulose film can be produced by a general solvent casting method. More In bulk, the prepared doping solution (deuterated cellulose composition) is first stored in a storage tank, and the foam contained in the doping solution is defoamed. The defoamed doping solution is transported from a doped solution outlet via a pressurized quantitative gear pump that is rotatable according to a pressurized die A fixed amount of liquid is transferred with high precision, which is uniformly cast from a mold of a press mold (slit) on a continuously moving metal support, and is not completely The dried cast film is released from the metal support at a peeling point where the metal support is almost rotated. After the ends of the prepared web are inserted into a clip and transferred to a tenter while maintaining its width and dried, the dried material is transferred to a roll of a drying apparatus, dried, and It is then wound by a winder to have a predetermined length. Further, in the case of producing a cast film, the film may be stretched in the longitudinal direction and in the transverse direction in a uniaxial manner or a biaxial manner in a state where the amount of the remaining solvent is 10 to 40% by weight. Alternatively, after the cast film is fabricated, the film can be stretched in an off-line mode. The film may be extended in the machine direction or in the transverse direction or in a simultaneous scheme or a sequential scheme. The middle is extended in a two-axis manner. The elongation ratio is preferably from 100 to 110% in the machine direction (MD) and from 103 to 105% in the transverse direction (TD) (here, % means length %). Within the above-mentioned extension range, the desired coefficient of thermal expansion can be achieved, and a film having a higher coefficient of thermal expansion in the transverse direction (TD) than the coefficient of thermal expansion in the machine direction (MD) can be produced, and curling in the polarizing plate can be further suppressed. The production.

When extended, preferably at a temperature of lower than the glass transition temperature of the optical film containing the compound of Chemical Formula 1 (T _g) 100 ℃ below the glass transition temperature (T _g) within the range of 20 ℃. The space temperature may preferably be -50 ° C to 50 ° C, more preferably -30 ° C to 40 ° C, and most preferably -20 ° C to 30 ° C when the solution is applied. As the gas for cooling the space, general air, nitrogen, argon, or helium can be used. The relative humidity is preferably from 0 to 70%, more preferably from 0 to 50%.

a support (casting part) to which a deuterated cellulose solution is applied The temperature may preferably be -50 ° C to 130 ° C, more preferably -30 ° C to 25 ° C, and most preferably -20 ° C to 15 ° C. In order to cool the cast component, a cooling gas can be introduced into the cast component. A cooling device can be placed within the casting component to cool the space. In the cooling of space, it is important to avoid water contact with the cast parts. In the case of cooling with a gas, it is preferred to prepare the gas in a dry state.

Further, the surface treatment can be carried out on the cellulose film of bismuth as needed. One Surface treatment is generally performed to improve the adhesion of the cellulose oxide film. Examples of the surface treatment may include a glow discharge treatment, an ultraviolet irradiation treatment, a corona treatment, a flame treatment, and a saponification treatment. Treatment) and so on.

The thickness of the deuterated cellulose film is preferably from 20 to 140 μm, more preferably 20 Up to 80 microns.

Using a cellulose-deposited film according to the present invention as a polarizing plate protective film In the case of the surface treated deuterated cellulose film, the surface treatment may include a hydrophilizing treatment, a glow discharge treatment, a corona treatment, a flame treatment, an alkali saponification treatment, and the like.

In the polarizing plate according to the present invention, the polarizer may be a polyvinyl alcohol film.

Further, in the polarizing plate, a polarizing plate may be stacked using an aqueous adhesive layer made of a polyvinyl alcohol aqueous solution.

In the polarizing plate according to the present invention, the acrylic film may have a coefficient of thermal expansion of 70 to 75 ppm/K. The thermal expansion coefficient of the acrylic film is within the range of the thermal expansion coefficient of the general acrylic film, but is not limited thereto.

In the polarizing plate according to the present invention, the height of the curl from the bottom may be 30 mm or less. Within the above range, the polarizing plate can be applied as a polarizing plate.

In the present invention, the polarizing plate can be used as a protective film together with the fluorinated cellulose film and the acrylic film.

In general, since the liquid crystal lattice in the liquid crystal display device is located between two polarizing plates, the liquid crystal display device has four polarizing plate protective films. The deuterated cellulose film according to the present invention may be located on any of the four polarizing plate protective films, but it is suitable to use a deuterated cellulose film as a protective film between the polarizing plate and the liquid crystal lattice of the liquid crystal display device. a protective film placed on the opposite side of the cellulose-deposited film according to the present invention, That is, the acrylic film can form a transparent hard coat layer, an antiglare coating layer, an anti-reflective coating layer, and the like.

In the present invention, a liquid crystal display device having a polarizing plate is also included. in In this case, one or two or more sheets of the polarizing plate according to the present invention may be stacked and used.

The polarizing plate according to the present invention can be used for liquid crystals having various display modules Specific examples of the display module in the display device may include TN, IPS, FLC, AFLC, OCB, STN, ECB, VA, HAN, and the like. More specifically, the liquid crystal display device may be an IPS module liquid crystal display device.

In an aspect of the invention, the liquid crystal display device may include a liquid crystal crystal And a polarizing plate disposed on at least one surface of the liquid crystal lattice. In this case, the polarizing plate may include a stack of a deuterated cellulose film, a polarizer, and an acrylic film, wherein the deuterated cellulose film or the acrylic film may be stacked adjacent to the liquid crystal lattice.

As a more specific example, the liquid crystal display device can be sequentially stacked therein A liquid crystal display device in which a deuterated cellulose film, a polarizer, an acrylic film, and a liquid crystal lattice are stacked.

In another aspect, the liquid crystal display device can be stacked with 醯 in sequence A liquid crystal display device of a cellulose film, a polarizer, an acrylic film, a liquid crystal lattice, a cellulose telluride film, a polarizer, and an acrylic film.

In another aspect, the liquid crystal display device can be stacked with C sequentially A liquid crystal display device of an olefin film, a polarizer, a fluoridation cellulose film, and a liquid crystal lattice.

In another aspect, the liquid crystal display device can be stacked with C sequentially Oleic acid film, polarizer, bismuth cellulose film, liquid crystal lattice, acrylic film, polarizer, And a liquid crystal display device for deuterated cellulose film.

Hereinafter, the examples will be provided to explain the present invention in more detail. However, the invention is not limited to the following embodiments.

Hereinafter, the physical properties of the film were measured by the following measurement methods.

1) Degree of substitution

The degree of substitution was measured according to ASTM D-817-91.

2) Thickness of the film

A sample prepared in the examples and the comparative examples was cut at a size of 50 mm × 50 mm (length × width) to prepare a sample, and a thickness gauge (TESA manufactured by Tesa technology) was used. - μHITE Height Gauge) measures the thickness of these samples. The thickness was measured on the film sample by taking five points including its center point, and the average was calculated.

3) Thermal expansion coefficient

After preparing the MD/TD sample of the produced film in a size of 4 × 16 mm 2 , the test was carried out 7 times, and the average value thereof was used.

Equipment: TMA (thermo mechanical analysis) (Mettler Toledo)

Measurement method: Both ends of the prepared sample were fixed using a clamp and hung on the hook of the TMA. The change in length is measured while raising the temperature, whereby the corresponding slope is calculated when the sample is fixed on the clip, the effective length of the film is 10 mm, and the change in length is measured in the order of several ppm. CTE value.

Condition: The sample was placed at a constant temperature of 25 ° C for 10 minutes (purge gas: N ₂ ) and then heated at a heating rate of 5 ° C / min in a temperature range of 25 to 120 ° C, and at 40 ° The average CTE value was calculated over a temperature range of 80 °C.

4) Curl height

After manufacturing the polarizing plate, the manufactured polarizing plate was developed on a flat bottom to visually confirm whether or not curling occurred at the edge portion. The crimp height is measured using a ruler to the height of the portion of the curl generated from the bottom.

[Example 1]

1) Preparation of deuterated cellulose composition (doping solution)

The following composition was placed in a stirrer and dissolved at a temperature of 30 °C.

In the following composition, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3- 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol as UV absorption Agent.

After heating the obtained doping solution to 30 ° C, heated doping The solution was transferred via a gear pump, filtered through a filter having an absolute filtration accuracy of 0.01 mm, and then filtered again through a cartridge filtration device having an absolute filtration accuracy of 5 microns.

2) Manufacture of bismuth cellulose film

The doping solution obtained by the filtration process is cast on a mirror stainless steel support through a casting mold and released. The amount of residual solvent at the time of demolding was adjusted to 25% by weight. After demolding, the film was stretched in the longitudinal direction at a stretching rate of 100% in a stretching machine, attached to a tenter, and stretched again at a stretching rate of 103% in the transverse direction of the film. After the film leaves the tenter and the film is removed at the end portions of the left and right sides of each 150 mm. The end-cut film was dried by a drier, the ends of the dried film were cut by 3 cm, and a 70 micron high knurling process was performed on a portion 10 mm from the end portion. Subsequently, the film system was wound into a roll shape. The film produced had a dry thickness of 60 microns. The physical properties of the produced cellulose oxide film were measured and shown in Table 1 below.

3) Manufacture of polarizing plates

By laminating a cellulose oxide film on one surface of a PVA polarizing film and an acrylic film (LG Chemical Ltd., CTE: 74.34 ppm/K) on the other surface thereof to use the adhesive each other A polarizing plate having an overall thickness of 220 μm was produced by bonding.

Whether or not curling was formed in the manufactured polarizing plate was observed, and the height of the curl was measured and shown in Table 1 below.

[Example 2]

Using the same composition as in Example 1, a film was produced by the same method as in Example 1, except that the film was stretched at a stretching rate of 110% in the longitudinal direction at the time of film formation and then with an elongation of 105% in the transverse direction. Extend the film.

The dry thickness of the film produced was 60 microns. The physical properties of the produced cellulose oxide film were measured and shown in Table 1 below.

Further, after the polarizing plate was manufactured by the same method, whether or not curling was formed in the manufactured polarizing plate was observed, and the height of the curl was measured and shown in Table 1 below.

[Example 3]

A film was produced by the same method as in Example 1, except that only 10 parts by weight of the compound represented by Chemical Formula 1 was used in the preparation of the cellulose fluorite film.

The film produced had a dry thickness of 60 microns. The physical properties of the produced cellulose oxide film were measured and shown in Table 1 below.

Further, after the polarizing plate was manufactured by the same method, whether or not curling was formed in the manufactured polarizing plate was observed, and the height of the curl was measured and shown in Table 1 below.

[Example 4]

A film was produced by the same method as in Example 1, except that only 10 parts by weight of the compound represented by Chemical Formula 3 was used in the preparation of the cellulose-deposited film.

The film produced had a dry thickness of 60 microns. The physical properties of the produced cellulose oxide film were measured and shown in Table 1 below.

Further, after the polarizing plate was manufactured by the same method, whether or not curling was formed in the manufactured polarizing plate was observed, and the height of the curl was measured and shown in Table 1 below.

[Example 5]

A film was produced by the same method as in Example 1, except that the following composition was used instead of the composition of Example 1.

The film produced had a dry thickness of 60 microns. The physical properties of the produced cellulose oxide film were measured and shown in Table 1 below.

Further, after the polarizing plate was manufactured by the same method, whether or not curling was formed in the manufactured polarizing plate was observed, and the height of the curl was measured and shown in Table 1 below.

[Comparative Example 1]

Using the same composition as in Example 1, a film was produced by the same method as in Example 1, except that the film was stretched at a stretching ratio of 100.5% in the longitudinal direction at the time of film formation and then with an elongation of 105% in the transverse direction. Extend the film.

The film produced had a dry thickness of 60 microns. Measuring the manufacturing The physical properties of the cellulose film are shown in Table 1 below.

In addition, after manufacturing the polarizing plate by the same method, observe the manufactured Whether or not curling was formed in the polarizing plate, and the height of the curl was measured and shown in Table 1 below.

[Comparative Example 2]

The same composition as in Example 1 was used by the same method as in Example 1. The film was produced by stretching the film in the longitudinal direction at a 100% elongation rate and then extending the film at a rate of 120% in the transverse direction.

The film produced had a dry thickness of 60 microns. Measuring the manufacturing The physical properties of the cellulose film are shown in Table 1 below.

In addition, after manufacturing the polarizing plate by the same method, observe the manufactured Whether or not curling was formed in the polarizing plate, and the height of the curl was measured and shown in Table 1 below.

[Comparative Example 3]

The film was produced by the same method as in Example 1, except that the bismuth fiber was prepared. Only 10 parts by weight of the compound represented by Chemical Formula 2 was used for the film.

The film produced had a dry thickness of 60 microns. Measuring the manufacturing The physical properties of the cellulose film are shown in Table 1 below.

In addition, after manufacturing the polarizing plate by the same method, observe the manufactured Whether or not curling was formed in the polarizing plate, and the height of the curl was measured and shown in Table 1 below.

In Table 1, TPP refers to triphenyl phosphate (chemical formula 1), BDP refers to Biphenyl diphenyl phosphate (chemical formula 2), and DOT refers to dioctyl terephthalate (chemical formula 3).

As shown in Table 1, it can be understood that the cellulose film in the transverse direction is in the transverse direction. The coefficient of thermal expansion is higher than the coefficient of thermal expansion of the cellulose-deposited film in the longitudinal direction, the height of the crimp is further reduced, and the difference between the coefficient of thermal expansion of the cellulose-deposited film in the transverse direction and the coefficient of thermal expansion of the acrylic film In the case of the range of 0 to 30 ppm/K and at the same time, the coefficient of thermal expansion of the cellulose-deposited film in the transverse direction is higher than the coefficient of thermal expansion of the cellulose-deposited film in the longitudinal direction, the generation of curl is reduced.

In particular, as shown in Examples 1 and 2, it can be confirmed that it is in use. In the case of a mixture of TPP, BDP, and DOT, the CTE value in the lateral direction is further increased, and the height of the curl is further reduced.

In Comparative Examples 1 and 2, the same as Examples 1 and 2 were used. The additive, however, has a coefficient of thermal expansion in the transverse direction of the cellulose-deposited film which is lower than the coefficient of thermal expansion of the cellulose-deposited film in the longitudinal direction by changing the elongation. In the example of Comparative Example 1, it can be understood that even if the difference between the coefficient of thermal expansion of the fluorinated cellulose film in the transverse direction and the coefficient of thermal expansion of the acrylic film is 0.1, the coefficient of thermal expansion in the transverse direction is lower than that in the longitudinal direction. The coefficient of thermal expansion above results in a curl having a high height.

By laminating a cellulose film according to the present invention and an acrylic film The polarizing plate can satisfy the following physical properties: the height of the curl measured from the bottom is 30 mm or less.

Claims (13)

A polarizing plate comprising a cellulose acylate film, a polarizer, and an acrylic film sequentially stacked thereon, wherein the bismuth cellulose film is The coefficient of thermal expansion and the coefficient of thermal expansion of the acrylic film satisfy the following equations 1 and 2: In Equation 1, CTE _ca is the coefficient of thermal expansion of the deuterated cellulose film in the transverse direction (TD), and CTE _ac is the coefficient of thermal expansion of the acrylic film, [Equation 2] CTE _td > CTE _md in Equation 2 In the CTE _td , the coefficient of thermal expansion (ppm/K) in the transverse direction (TD), and the CTE _md is the coefficient of thermal expansion (ppm/K) in the machine direction (MD). The polarizing plate of claim 1, wherein the thermal expansion coefficient of the deuterated cellulose film satisfies the following Equation 3: [Equation 3] CTE _{td -} CTE _md > 3 ppm / K In Equation 3, CTE _td is in the transverse direction (TD) The coefficient of thermal expansion (ppm/K), and the CTE _md is the coefficient of thermal expansion (ppm/K) in the machine direction (MD). The polarizing plate of claim 1, wherein the thermal expansion coefficient of the cellulose fluorite film satisfies the following Equation 4: [Equation 4] CTE _{td -} CTE _md > 15 ppm / K in Equation 4, CTE _td is in the transverse direction (TD) The coefficient of thermal expansion (ppm/K), and the CTE _md is the coefficient of thermal expansion (ppm/K) in the machine direction (MD). The polarizing plate of claim 1, wherein the cellulose fluorite film has a coefficient of thermal expansion in a transverse direction (TD) of 60 to 105 ppm/K. The polarizing plate of claim 1, wherein the deuterated cellulose film comprises a deuterated cellulose resin and one or two or more selected from the compounds represented by Chemical Formulas 1 to 3: The polarizing plate of claim 5, wherein the deuterated cellulose film comprises the compound represented by Chemical Formulas 1 to 3, thereby based on 100 parts by weight of the deuterated cellulose resin, The total content of the compounds is from 0.1 to 20 parts by weight, and the compound weight ratio of the compound represented by Chemical Formula 1, the compound represented by Chemical Formula 2, and the compound represented by Chemical Formula 3 is from 1 to 2:1 to 1.5:1. The polarizing plate of claim 1, wherein the acrylic film has a coefficient of thermal expansion of 70 to 75 ppm/K. The polarizing plate of claim 1, wherein in the polarizing plate, the height of the curl from the bottom is 30 mm or less. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 8. The liquid crystal display device of claim 9, wherein the deuterated cellulose film, the polarizer, the acrylic film, and a liquid crystal cell are sequentially stacked in the liquid crystal display device. The liquid crystal display device of claim 9, wherein the deuterated cellulose film, the polarizer, the acrylic film, a liquid crystal lattice, the deuterated cellulose film, the polarizer, and the acrylic film are sequentially stacked on In the liquid crystal display device. The liquid crystal display device of claim 9, wherein the acrylic film, the polarizer, the bismuth cellulose film, and a liquid crystal lattice are sequentially stacked in the liquid crystal display device. The liquid crystal display device of claim 9, wherein the acrylic film, the polarizer, the deuterated cellulose film, a liquid crystal lattice, the acrylic film, the polarizer, and the deuterated cellulose film are sequentially stacked on In the liquid crystal display device.