KR20020096349A - Polarizing plate for liquid cristal diplay - Google Patents

Abstract

PURPOSE: A polarization plate for a liquid crystal display device is provided to use cyclic ethylene/non-cyclic ethylene copolymer resin film having low gas and water permeability, thereby improving the humid/temperature-resistance of the polarization plate. CONSTITUTION: A polarization plate for a liquid crystal display device includes protecting layer attached to either front or rear surface, wherein the protecting layer is a cyclic olefin/non-cyclic olefin copolymer resin film formed by copolymerization under the existence of a metallocene catalyst.

Description

Polarizing plate for liquid crystal display {POLARIZING PLATE FOR LIQUID CRISTAL DIPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate for liquid crystal displays, and in particular, by using a cyclic ethylene-noncyclic ethylene copolymer resin film synthesized using a metallocene catalyst as a protective layer on at least one side of the polarizing element, it is excellent in moisture heat resistance and photoelasticity. The present invention relates to a polarizing plate for liquid crystal display with minimized phenomenon.

In general, one or two polarizers are used in a liquid crystal display (LCD), and the polarizer and the liquid crystal in the liquid crystal cell cause optical interaction to implement an image. Since the transmissive liquid crystal display uses a back light, it requires a backlight unit such as a light guide plate including a cold cathode fluorescent lamp and a reflective layer, a diffusion film, and a prism film, and the reflective liquid crystal display requires a reflective layer. On the other hand, the transflective liquid crystal display combining the two uses a transflective layer and a reflective layer on the backlight unit.

For example, in a transmissive twisted nematic (TN) liquid crystal display, one of the polarizers makes the back light linearly polarized, and the electrically driven TN liquid crystal serves to rotate the linearly polarized light. Therefore, the amount of light through another polarizer is adjusted according to the degree of rotation.

Recently, a high quality liquid crystal display device requires a polarizing plate having excellent optical characteristics, excellent durability, excellent adhesive reliability, and excellent additional functions.

Examples of conventional commercially available polarizing plates include iodine polarizing plates, dye-based polarizing plates, polyene-based polarizing plates, and the like. These polarizing plates are absorption type polarizing plates in which any component of the white light in the non-polarized state is absorbed by the conjugated structure of the oriented dichroic substance or the oriented polymer chain itself, and the other component perpendicular to the other is transmitted. Non-polarized light can be represented as the sum of the light of two components perpendicular to each other, so in the case of an absorbing polarizer, more than 50% of light is absorbed and disappears in the form of heat.

In general, an iodine polarizer exhibits polarization by being oriented by a polyvinyl alcohol (PVA) chain in which an iodine ion chain is stretched orientated, and the dye polarizer is also used in a PVA chain in which a dichroic dye is stretched orientated. By showing orientation, polarization is exhibited. On the other hand, the polyene-based polarizing plate exhibits polarization by forming polyene by dehydration of PVA film or dehydrochlorination of polyvinyl chloride (PVC) film.

However, the iodine-based or dye-based polarizing plates of the absorption type polarizing plates are based on the PVA matrix, which is a water-soluble polymer, so that even if the cross-linking treatment is performed during the manufacturing process, the polarizing device is vulnerable to heat and moisture. Is easy to occur. In high temperature and high humidity environments, shrinkage may occur in the stretching direction of the polarizing element, and mechanical strength is very weak even at room temperature in the stretching perpendicular direction of the polarizing element. On the other hand, in the case of an iodine-based polarizing device, the weak heat resistance and heat and humidity resistance of the iodine ion chain itself is a weak point.

Therefore, in order to secure dimensional stability, moisture resistance, heat resistance, etc. of the polarizing plate, it is common to form protective layers on both sides of the polarizing element.

Conventional commercially available polarizers mainly use triacetyl cellulose (TAC) as a protective layer. That is, the surface energy of the TAC film is increased to make it hydrophilic, and then a TAC film is laminated on both sides of the polarizer using a water-soluble adhesive to prepare a polarizing film. In general, the reason why the TAC film is used as a protective layer of the polarizing film is as follows.

First, the light transmittance is high, second, the birefringence is relatively low, and third, the hydrophilization by surface modification is easy, so that the lamination with the polarizer is easy.

However, the TAC to the protective layer of the polarizer has the following disadvantages.

First, since the TAC film has high moisture permeability, the durability of the polarizing plate is degraded under high temperature and high humidity. Second, the TAC film has a high gas permeability and is likely to deteriorate dichroic substances such as iodine by the permeated oxygen. Third, since the plasticizer is added to the TAC film, the heat resistance is inferior, and it melts during the surface alkali saponification process and causes appearance defects such as surface imprinting. Fourth, when using an adhesive containing a TAC film and acrylic acid, the TAC film may be decomposed by acrylic acid. Fifth, when the polarizing plate is attached to a large size LCD and left for a long time in a high temperature and high humidity environment, the photoelastic coefficient shows a photoelastic effect, thus showing a contrast ratio by position of the LCD image.

SUMMARY OF THE INVENTION In view of the problems of the prior art, an object of the present invention is to provide a polarizing plate for liquid crystal display, in which a film capable of improving moisture and heat resistance of a polarizing plate having low gas and moisture permeability is attached as a protective film on one side of the polarizing element. do.

Another object of the present invention is a film having a low photoelastic coefficient and a small change in birefringence in a high temperature and high humidity environment compared to a TAC film used in a conventional protective layer, so that a non-uniform contrast ratio is generated on one side of the polarizing element of the LCD image. It is to provide a polarizing plate for a liquid crystal display attached.

The present invention, in order to achieve the above object, in the polarizing plate for LCD comprising a polarizing element is attached to the protective layer on at least one surface of the front or rear,

Provided is a polarizing plate for liquid crystal display, wherein the protective layer is a film of a cyclic olefin-noncyclic olefin copolymer resin prepared by polymerization in the presence of a metallocene catalyst.

Hereinafter, the present invention will be described in detail.

This invention uses the cyclic olefin-noncyclic olefin copolymer resin film as a protective layer of the polarizing plate for liquid crystal displays. Advantages of such a cyclic olefin-acyclic olefin copolymer resin film are as follows. First, the light transmittance is the same as TAC, but the birefringence is excellent. Second, since the photoelastic coefficient is much lower than that of TAC, the birefringence change is small in a high temperature and high humidity environment, thereby minimizing the occurrence of non-uniform contrast ratios for each LCD image. Third, the moisture permeability is much lower than that of TAC, thereby improving durability of the polarizer under high temperature and high humidity.

(Polarization element type)

Polarizers to which the protective layer of the present invention is attached are iodine-based and dye-based polarizers in which iodine or dichroic dye is adsorbed and oriented to the swollen PVA film.

(Method of manufacturing polarizing element)

The polarizing device to which the protective layer of the present invention is attached was manufactured using various continuous processes such as swelling a PVA film with water or an aqueous solution of boric acid, dyeing with an iodine solution or a dye solution, and stretching in an aqueous solution of boric acid. However, the manufacturing method of the polarizing element is not limited to a specific method.

For example, in the case of an iodine polarizing device, a method of adsorbing iodine after stretching a PVA film, a method of adsorbing iodine on a PVA film and then stretching, and a method of simultaneously dyeing and stretching may be used. In the case of dyeing, the method of dividing two or more times, and in the case of stretching, a method of granting a different draw ratio for each of two or more sections may be applied.

Also in the case of the dye-based polarizing plate, a method of adsorbing a dichroic dye after stretching the PVA film, a method of adsorbing the dichroic dye to the PVA film and stretching, and a method of simultaneously dyeing and stretching may be used. In the case of dyeing, the method of dividing two or more times, and in the case of stretching, a method of granting a different draw ratio for each of two or more sections may be applied.

(Thermoplastic cyclic olefin-acyclic olefin copolymer resin)

The film of the protective layer adhered to the polarizing element of this invention is manufactured from resin copolymerized with a non-cyclic monomer, without opening the ring of a cyclic monomer using a metallocene catalyst.

Physical properties of such a cyclic olefin-acyclic olefin copolymer resin film are as follows. Permeability (%) is above 92%, photoelasticity (cm ² / kgf) is less than 0.04 cm ² / kgf, water permeability (g.mm) / (m ² .d) is 23 Less than 0.03 (g.mm) / (m ² .d) at 85% relative humidity at ℃, water absorption (%) measured at 23 ℃ for 24 hours, less than 0.01%, refractive index Is 1.54 or less. These physical properties are suitable for use as a polarizing plate protective layer.

In general, the monocyclic olefin can be polymerized without opening the ring by using a metallocene compound (for example, bis- (indenyl) -zirconium dichloride) as a catalyst.

In the film of the cyclic olefin-acyclic olefin copolymer resin attached to either side of the polarizing element of the present invention, the resin preferably contains at least 14 mol% (preferably 50 mol%) of norbornene-based monomer in the polymer. Do.

Each of the cyclic olefin monomer and the non-cyclic olefin monomer which can be used when preparing the cyclic olefin-acyclic olefin copolymer resin of the present invention may be represented by the following Chemical Formulas 1 to 8.

When the cyclic olefin monomer is copolymerized, at least one or more of the monomers of the following Chemical Formulas 1 to 7 are included in an amount of 0.01 to 99.9 wt% based on the total weight of the monomer to be copolymerized. The monomers represented by the following Chemical Formulas 1 to 6 are norbornene-based monomers, and the monomers represented by Chemical Formula 7 are cyclic monomers based on ethylene groups.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

In the formula 1 to 6,

R ¹ to R ⁸ may be each independently or the same at the same time in the same formula,

Hydrogen atom, aryl having 6 to 16 carbon atoms, or alkyl having 1 to 8 carbon atoms.

[Formula 7]

In formula (7), n is an integer of 2 to 10.

In addition, at least one noncyclic olefin monomer is included in an amount of 0.01 to 99.9% by weight based on the total weight of the monomers to be copolymerized to be polymerized. The acyclic olefin is preferably a compound represented by the following formula (8).

[Formula 8]

In the formula (8),

Each of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² , independently or simultaneously, is hydrogen or alkyl having 1 to 8 carbon atoms.

The polymerization temperature at the time of producing the cyclic olefin-noncyclic olefin copolymer resin is preferably 20 to 120 ° C, and the polymerization pressure is preferably 1 to 60 bar.

The catalyst used when preparing the cyclic olefin-acyclic olefin copolymer resin of the present invention is a metallocene catalyst, and a cocatalyst may be used together.

The cocatalyst is preferably aluminoxane, and such aluminoxane is a compound represented by the following formula (linear) or a compound represented by the formula (10).

[Formula 9]

[Formula 10]

In the formula of Formula 9 and Formula 10,

Each R ¹³ is alkyl, phenyl, or benzyl, having 1 to 6 carbon atoms,

n is an integer from 2 to 50.

In addition, the metallocene catalyst used is preferably a compound represented by the following formula (11).

[Formula 11]

In Formula 11,

M ¹ is titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb) or tantalum (Ta),

R ¹⁴ and R ¹⁵ are each independently or simultaneously hydrogen, halogen, alkyl of 1 to 10 carbon atoms, alkoxy of 1 to 10 carbon atoms, aryl of 6 to 10 carbon atoms, aryloxy of 6 to 10 carbon atoms, and 2 to 10 carbon atoms. Alkenyl, arylalkyl having 7 to 40 carbon atoms, alkylaryl having 7 to 40 carbon atoms, arylalkenyl having 8 to 40 carbon atoms,

R ¹⁶ and R ¹⁷ are each independently or simultaneously a mononuclear or polynuclear hydrocarbon radical capable of forming a sandwich structure with the central atom M ¹ ,

R ¹⁸ is , , , , , , , , , , , , , , , , , or Is,

Each of R ¹⁹ , R ²⁰ and R ²¹ , which are substituents defined in R ¹⁸ , independently or simultaneously, is hydrogen, halogen, alkyl of 1 to 10 carbon atoms, fluoroalkyl of 1 to 10 carbon atoms, of 1 to 10 carbon atoms. Fluoroaryl, aryl having 6 to 10 carbon atoms, alkoxy having 1 to 10 carbon atoms, aryloxy having 6 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms, arylalkyl having 7 to 40 carbon atoms, aryl alkenyl having 8 to 40 carbon atoms R ¹⁹ , R ²⁰ and R ²¹ may each have a ring structure.

M ² is silicon (Si), germanium (Ge), or tin (Sn).

Such a catalyst is preferably used as follows.

rac-ethylene-bis- (1-indenyl) -zirconium dichloride, isopropylene- (9-fluorenyl) -cyclopentadienyl-zirconium Isopropylene- (9-fluorenyl) -cyclopentadienyl-zirconium dichloride, rac-dimethylsilyl-bis- (1-indenyl) -zirconium dichloride (rac-dimethylsilyl-bis- (1-indenyl) -zirconium dichloride) rac-dimethylgermyl-bis- (1-indenyl) -zirconium dichloride (rac-dimethylgermyl-bis- (1-indenyl) -zirconium dichloride), rac-phenylmethylsilyl-bis- (1-indenyl)- Zirconium dichloride (rac-phenylvinylsilyl-bis- (1-indenyl) -zirconium dichloride), rac-phenylvinylsilyl-bis- (1-indenyl) -zirconium dichloride (rac-phenylvinylsilyl-bis- (1-indenyl) -zirconium dichloride), 1-silacyclobutyl-bis- (1'-indenyl) -zirconium dichloride (1-silacyclobutyl-bis- (1'-indenyl) -zirconium dichloride), rac-diphenylsilyl-bis- (1-indenyl) -hafnium di Rac-diphenylsilyl-bis- (1-indenyl) -halfnium dichloride, rac-phenylmethylsilyl-bis- (1-indenyl)-hafnium dichloride (rac-phenylmethylsilyl-bis- (1-indenyl)- halfnium dichloride), rac-dimethylsilyl-bis- (1-indenyl) -halfnium dichloride, rac-diphenylsilyl-bis- (1-indenyl) ) -Zirconium dichloride (rac-diphenylsilyl-bis- (1-indenyl) -zirconium dichloride), diphenylmethylene- (9-fluorenyl) -cyclopentadienyl-zirconium dichloride (diphenylmethylene- (9-flourenyl) -cyclopentandienyl-zirconium dichloride) or a mixture of two or more of them.

The cyclic olefin-acyclic olefin copolymer resin attached to one side of the polarizing element of the present invention uses at least one cyclic olefin (Formula 1 to 7) and at least one acyclic olefin (Acyclic 1-olefin of Formula 8) The polymerization takes place. The polymerization is carried out in a conventional cyclic olefin solution, the catalyst is dissolved in a solvent and the metallocene is preactivated by mixing with aluminoxane. The purpose of activating in advance is to increase the catalytic activity by contacting the metallocene and the aluminoxane solution before adding the catalyst and the promoter to the polymerization reactor. The time for activating the catalyst in advance is preferably 15 to 60 minutes.

The method of separating the copolymer after the polymerization is completed by first adding a filter medium with water to precipitate the catalyst and cocatalyst remaining in the polymerization reactant, and then removing the resultant by filtration and adding it to an anti-solvent. Phase separation of the polymer, followed by filtration to filter out the solid phase polymer, flash separation and thin film evaporator to recover the solvent and the unreacted monomer using a thin film to obtain the solid phase polymer. Can be.

Compounds of formula (7) which are monocyclic olefins may be substituted with aryl or alkyl radicals. Monocyclic olefins are preferably cyclopentene but may be polymerized using cycloheptene, indene, or cyclooctene.

The copolymer resin used in the present invention is preferably a copolymer of the polycyclic olefin of Formula 1 or Formula 2 and the acyclic olefin of Formula 8. In particular, a derivative in which a polycyclic olefin containing norbornene and tetracyclododecene is substituted with an alkyl having 1 to 6 carbon atoms may be used, and it is preferable to copolymerize it with ethylene.

Depending on the type of monomer in the polymerization process, a polycyclic bi-copolymer, bi-copolymer, ter-copolymer, and multi-copolymer may be obtained.

As described above, the preactivation of transition metal compounds (catalysts and cocatalysts) is generally done in solution. The concentration of aluminoxane in solution is generally from 1% by weight to saturation. Metallocene may be used in the same concentration, but it is preferable to use 10 ^-4 to 10 ^-2 mol per mol of aluminoxane. Preferred preactivation time is 15 to 60 minutes, at which time the temperature is 15 to 70 ° C.

In addition, the metallocene compound is generally preferably used from 10 ^-4 to 10 ^-6 mol per liter of the reactor volume based on the transition metal. Aluminoxane is preferably used 1 to 10 ^-4 mol per liter of the reaction volume on the basis of aluminum (Al).

The incorporation ratio of the monomers depends on various polymerization conditions such as reaction temperature, reaction pressure, catalyst concentration, promoter concentration, and the like. The bonding ratio of the cyclic monomer is preferably 10 to 80 mol%.

The average molecular weight of the cyclic olefin-noncyclic olefin copolymer prepared in this way will vary depending on the degree of hydrogenation reaction, catalyst concentration change, and temperature change. Molecular weight is measured using GPC (Gel Permeation Chromatography) (1,2,4-trichlorobenzene, 135 ℃, using a polystyrene reference material).

Generally the degree of dispersion M _w / M _n of such copolymers is from 2.0 to 3.5. The glass transition temperature (T _g ) of the copolymer is 80 to 190 ° C.

(Forming film: solution casting method, melt molding method)

The cyclic ethylene-acyclic ethylene copolymer resin used in the present invention can be molded into a film using a solution casting method, a melt molding method, or the like. In general, it is preferable to use a solution casting method to obtain a film having better optical properties, but since the norbornene-based monomer-ethylene copolymer resin is a resin having a small photoelastic coefficient compared to TAC, a film having a birefringence sufficiently small even by the melt molding method is used. Can be obtained.

The solution casting method dissolves or disperses the cyclic ethylene-acyclic ethylene copolymer resin in a solvent to prepare a solution having a suitable concentration, which is then placed on a carrier (metal drum, steel belt, Teflon belt, or PET film) such as a plate or roll. After application and drying, the film is molded by peeling from the carrier.

As the solvent used for dissolving the cyclic ethylene-acyclic ethylene resin, aromatic compounds such as benzene, toluene, and xylene are most preferred, but in some cases, solvents such as butyl acetate, tetrahydrofuran, ketone, and two or more of them It is also possible to use the mixed solvent which mixed these.

The resin concentration in the solution can be adjusted according to the thickness of the film to be obtained in the range of 10 to 50% by weight. When the concentration of the resin is too low, it is difficult to obtain a film having a desired thickness. When the concentration of the resin is too high, the film forming property is poor and the appearance of the film is poor.

Application of the resin solution can be applied to various methods such as T-die, doctor knife, Meyer bar, roll coat, die coat and the like.

Drying of the solvent is preferably carried out until the concentration of the residual solvent is 2 to 4% by weight or less. When the residual concentration of the solvent is high, there is a concern that the heat resistance of the film may be poor, such as deformation of the film due to evaporation of the residual solvent in a high temperature environment. Drying of the solvent is generally at least two stages of drying. First, the film on the plate or roll is first dried to a temperature of 20 to 90 ° C. to lower the residual solvent concentration to 7 to 12% by weight or less, and the film is peeled off from the plate or roll, and then the glass transition temperature of the resin at room temperature ( The temperature is raised to T _g ), followed by secondary drying until the residual solvent concentration is 2 to 4 wt% or less. At this time, when the drying temperature is too high, there is a problem that the sheet is foamed due to the volatilization of the solvent during drying.

As the melt molding method, an extrusion molding method such as a T-die method or an inflation method, a calender method, a hot press method, an injection molding method, or the like can be used. Most preferably, the norbornene-based monomer-ethylene copolymer resin film is molded by using a melt extrusion method using a T-die.

In order to use the cyclic ethylene-noncyclic ethylene copolymer resin film prepared in the present invention as a protective layer, most preferable physical properties such as mechanical strength, transparency, birefringence and the like can be obtained within a thickness range of 20 to 200 μm. When the thickness of the film is thin, the strength becomes excessively weak, whereas when the thickness of the film is thick, it cannot be used for optical applications due to low transparency, high birefringence, and poor appearance. In addition, in the case of the solution casting method, there is also a problem in that the thickness of the film is too thick, making it difficult to dry the solvent. In general, the TAC film is used in a thickness of at least 50 to 80 ㎛ or more in order to obtain sufficient strength and moisture resistance. On the contrary, the cyclic ethylene-noncyclic ethylene copolymer resin film was able to obtain strength and moisture resistance similar to TAC even with a thickness of about 30 to 50 μm.

(Polarizing plate for liquid crystal display)

In the polarizing plate for liquid crystal display of the present invention, a cyclic ethylene-acyclic ethylene copolymer resin film is pasted on at least one side of the polarizing element as a protective layer. In general, in order to prevent appearance, dimensional change and physical property change that may occur during the manufacturing process or long-term use of the polarizing plate, it is preferable to provide protective layers on both sides. When the protective layer is provided only on one side of the polarizing plate, a protective layer is provided outside the polarizing element in order to protect the polarizing element from the ambient humidity of the liquid crystal display, and the inside can be attached to the liquid crystal display glass using an adhesive.

In addition, one side of the polarizing element may be the cyclic ethylene-noncyclic ethylene copolymer resin film, but the other side may form a protective layer with a film of a different material. In this case, the other protective layer may be a conventional TAC film or a transparent film having high birefringence. When the birefringent transparent resin film is used as the other protective layer, the layer is directed outward of the liquid crystal display. When the conventional TAC film is used together as the other protective layer, the two layers are directed toward either the inside or the outside of the liquid crystal display depending on the purpose of use, such as reducing the photoelastic effect or improving moisture resistance.

The lamination of the polarizing element and the cyclic ethylene-cyclic ethylene copolymer resin film uses an adhesive method using an adhesive. In this case, the adhesive means that the adhesive force at the interface is very large, and thus the adhesive force does not peel without breaking of either film of the adhesive.

As a preferable adhesive agent, if it is an adhesive agent used for adhesion | attachment of a polyolefin, it can use for adhesion | attachment of a norbornene-type monomer-ethylene copolymer resin film. Examples thereof include dry laminate adhesives, styrene butadiene rubber adhesives, epoxy two-component curable adhesives, and the like, in which a polyurethane resin solution and a polyisocyanate resin solution are mixed. In particular, the adhesive is preferably low in viscosity, excellent in storage stability, and transparent. In addition, a film obtained by coating a hot melt adhesive on a norbornene-based monomer-ethylene copolymer resin film may be laminated using a polarizing element and a heat compression roll. The melting point of the hot melt adhesive is preferably 90 ° C. or higher.

In order to improve the adhesive strength, the primer layer suitable for the adhesive is coated on the surface of the cyclic ethylene-acyclic ethylene copolymer resin film, or corona treatment, plasma treatment, ion beam treatment, etc. You can also improve.

In addition, if sufficient adhesive strength can be exhibited, an adhesive may also be applied. It is preferable that the adhesive is sufficiently cured by heat or UV after lamination so that the mechanical strength is improved to the level of the adhesive, and the interfacial adhesive strength is also very large so that the adhesive does not peel off without breaking of either film of the adhesive. desirable. Such adhesives include natural rubbers having excellent optical transparency, synthetic rubbers or elastomers, vinyl chloride-vinyl acetate copolymers, polyvinyl alkyl ethers, polyacrylates, modified polyolefin resin-based adhesives, and curable adhesives having a curing agent such as isocyanate added thereto. Can be mentioned.

The present invention will be described in more detail with reference to the following examples. However, an Example is for illustrating this invention and is not limited only to these.

EXAMPLE

Preparation Example 1

(Synthesis of norbornene monomer-ethylene copolymer resin using metallocene catalyst)

After preparing a clean and completely dried 500 mL batch reactor in an argon atmosphere, 600 mL of a norbornene solution (80 wt%) dissolved in toluene was added thereto, and the reactor temperature was raised to 70 ° C.

In the thus prepared reactor, isopropylene- (9-fluorenyl) -cyclopentadienyl-zirconium dichloride (isopropylene- (9-fluorenyl) -cyclo pentadienyl-zirconium dichloride) as a catalyst and aluminoxane (MMAO) as a promoter were added. After the addition, the polymerization was carried out for 20 minutes while maintaining the ethylene pressure at 70 psi.

The obtained polymer solution was removed from the remaining metal compound in the solution, it was added to a polar solvent to phase-separate the polymer. After filtering the solid polymer through filtration, and dried under reduced pressure and temperature conditions of 80 ℃ for 15 hours to obtain a norbornene-based monomer-ethylene copolymer resin.

Example 1

(Polarizing Plate Manufacturer)

After the corona treatment of the 50 μm-thick film prepared from the norbornene-based monomer-ethylene copolymer resin prepared in Preparation Example 1, the styrene-butadiene rubber adhesive was used as a protective film on both sides of the PVA polarizer adsorbed and stretched with iodine. It was laminated using, and coated with an acrylic pressure-sensitive adhesive of about 25 m on one side to prepare a polarizing plate.

This polarizing plate was laminated | stacked on the glass substrate of thickness 1.2mm, and the durability evaluation sample was manufactured. The initial light transmittance of this sample was 43.5% and the polarization degree was 99.90%.

When the sample was treated at 60 ° C. and 90% relative humidity for 500 hours, the interlayer peeling of the polarizing plate was 0.1 mm, the light transmittance was increased by 0.3%, and the degree of polarization decreased by 0.05%.

This sample had a small change in birefringence in the above high temperature and high humidity environment, resulting in less non-uniform contrast ratio by sample position when observed in a polarizing plate orthogonal state.

Comparative Example 1

A TAC protective film having a thickness of 80 μm surface-treated with NaOH solution was laminated on both surfaces of the same polarizer as in Example 1, using a water-soluble PVA adhesive (5 wt% aqueous solution), and about 25 on one side thereof. An acrylic pressure-sensitive adhesive was coated to prepare a polarizing plate. This polarizing plate was laminated | stacked on the glass substrate of thickness 1.2mm, and the durability evaluation sample was manufactured. This sample had an initial light transmittance of 43.3% and a degree of polarization of 99.92%.

When this sample was processed at 60 degreeC and 90% of relative humidity for 500 hours, the interlayer peeling of the polarizing plate was 0.2 mm, the light transmittance increased by 0.5%, and the polarization degree decreased by 0.10%.

This sample had a large change in birefringence in the above high temperature and high humidity environment, resulting in a non-uniform contrast ratio by sample position when observed in a polarizer orthogonal state.

As described above, the cyclic ethylene-noncyclic ethylene copolymer resin film prepared by using the metallocene catalyst according to the present invention may improve moisture and heat resistance of the polarizing plate when used as a protective film of a polarizing device due to low gas and moisture permeability. In addition, the photoelastic coefficient is significantly lower than that of the TAC film used in the conventional protective layer, and the change in birefringence in the high temperature and high humidity environment is small, thereby minimizing the occurrence of non-uniform contrast ratios for each position of the LCD image.

Claims (11)

In the polarizing plate for LCD comprising a polarizing element having a protective layer attached to at least one side of the front or rear, A polarizing plate for liquid crystal display, wherein the protective layer is a film of a cyclic olefin-acyclic olefin copolymer resin produced by polymerization in the presence of a metallocene catalyst. The method of claim 1, A polarizing plate for liquid crystal display wherein the cyclic olefin is selected from the group of monomers represented by the following general formulas (1) to (7): [Formula 1] [Formula 2] [Formula 3] [Formula 4] [Formula 5] [Formula 6] In the formula 1 to 6, R ¹ to R ⁸ may be each independently or the same at the same time in the same formula, Hydrogen atom, aryl having 6 to 16 carbon atoms, or alkyl having 1 to 8 carbon atoms, [Formula 7] In formula (7), n is an integer of 2 to 10. The method of claim 1, Polarizing plate for liquid crystal display wherein the non-cyclic olefin is selected from the group of monomers represented by the following formula (8): [Formula 8] In the formula (8), Each of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² , independently or simultaneously, is hydrogen or alkyl having 1 to 8 carbon atoms. The method of claim 1, The copolymer has a weight ratio of the cyclic olefin and the non-cyclic olefin of 0.01 to 99.9: 99.9: 0.01 polarizing plate for liquid crystal display. The method of claim 1, The cyclic olefin-noncyclic olefin copolymer has a degree of dispersion (Mw / Mn) of 2.0 to 3.5, the glass transition temperature (Tg) of 80 to 190 ℃ polarizing plate for liquid crystal display. The method of claim 1, The cyclic olefin-noncyclic olefin copolymer resin film has a transmittance (%) of 92% or more, a photoelasticity (cm ² / kgf) of less than 0.04 cm ² / kgf, and a water permeability, ( g.mm) / (m ² .d)) is less than 0.03 (g.mm) / (m ² .d) at a relative humidity of 85% at 23 ° C., and water absorption (%) for 24 hours. It is less than 0.01% as a result of measuring at 23 degreeC, and the refractive index (refractive index) is 1.54 or less polarizing plate for liquid crystal displays. The method of claim 1, The cyclic olefin-noncyclic olefin copolymer resin film has a thickness of 20 to 200 ㎛ polarizing plate for liquid crystal display. The method of claim 1, The polarizing element and the cyclic olefin-acyclic olefin copolymer resin film is a polarizing plate for a liquid crystal display attached with an adhesive interposed. The method of claim 8, The adhesive is a polarizing plate for liquid crystal display, wherein the adhesive is selected from the group consisting of an adhesive for dry laminate of a polyurethane resin solution and a polyisocyanate resin solution, a styrene-butadiene rubber adhesive, an epoxy two-component curable adhesive, and a hot melt adhesive. The method of claim 1, The polarizing element and the cyclic olefin-acyclic olefin copolymer resin film is a polarizing plate for a liquid crystal display which is attached with an adhesive. The method of claim 10, The polarizing plate for liquid crystal display, wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive of a material selected from the group consisting of natural rubber, synthetic rubber, elastomer, vinyl chloride-vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate, and modified polyolefin resin system.