KR20190027021A - Polarizing plate - Google Patents

Abstract

The present invention relates to a polarizing plate which is formed by a solvent casting method from a resin composition including an acrylic resin represented by chemical formula 1 and particles of a poly(methyl methacrylate) (PMMA) material, has an acryl film provided on one side surface of the polarizing plate and having a dynamic friction coefficient of 0.7 or less, and has a protective film provided on the other side surface of the polarizing plate and containing a mixed fatty acid cellulose ester having an acetyl group and a butyryl group or a triacetyl cellulose. Roll winding quality of a film is improved, and quality maintenance over time is possible. Therefore, a polarizing plate produced by using such a film also has excellent outer appearance quality. In the chemical formula 1, a and b are integers and 1 or greater. MMA-BMA Here, MMA represents a methyl methacrylate unit and BMA represents a butyl methacrylate unit.

Description

Polarizing plate {

A protective film comprising triacetyl cellulose or a mixed fatty acid cellulose ester having acetyl group and butyryl group is provided on one side of the polarizer and an acrylic film having high slippability and blocking property during solvent casting is secured, And a polarizing plate provided on the other surface of the polarizer and having excellent appearance quality.

2. Description of the Related Art In recent years, a liquid crystal display device which consumes a small amount of power and operates at a low voltage and is lightweight and thin has been widely used in information display devices such as a cellular phone, a monitor for a portable information terminal computer, and a television. Such an information display device is required to have reliability under a severe environment depending on its use. For example, in a car navigation system liquid crystal display device, the temperature and humidity inside the vehicle in which it is placed may become very high, and the temperature and humidity conditions required are more stringent than those of ordinary monitors for a television or a personal computer. In a liquid crystal display device, a polarizing plate is used to enable the display. In a liquid crystal display device requiring such a strict temperature and / or humidity condition, a polarizing plate constituting it is required to have high durability.

The polarizing plate usually has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film made of a polyvinyl alcohol resin in which a dichroic dye is adsorbed and oriented. Conventionally, triacetyl cellulose (TAC) is widely used for this protective film, and this protective film is bonded to the polarizing film through an adhesive composed of an aqueous solution of a polyvinyl alcohol resin. However, the polarizing plate in which the protective film made of triacetylcellulose is laminated has a high moisture permeability of triacetyl cellulose, so that when the polarizing plate is used for a long time under a high humid environment, the polarization performance deteriorates or the protective film and the polarizing film peel off have. In order to solve these problems, attempts have been made to use a (meth) acrylic resin film having a lower moisture permeability as a protective film of a polarizing plate than a triacetylcellulose film.

Conventional acrylic protective films have been manufactured by melt casting method. However, solvent casting method has many merits in terms of environment-friendliness such as thinning, mass production, and recycling of resin when manufactured. The solvent casting method is to melt the acrylic film in a solvent and extrude it into a T-die. Then, the solvent is dried in the belt to form a film. It is necessary to increase the impact strength by adding the optimized particles and secure the slip property for transporting the film. Process is possible. Also, the added particles should not be dissolved or deformed in the solvent.

Korean Patent No. 1265007 discloses a pressure-sensitive type polarizing plate in which light leakage of an image display device does not occur even by a change in use environment. In the pressure-sensitive adhesive type polarizing plate in which the acrylic polymer constituting the pressure-sensitive adhesive layer has an aromatic ring structure ) Acrylate monomer unit and its content is determined according to the value of the photoelastic coefficient X of the transparent protective film, and when the retardation value of the transparent protective film changes due to environmental changes such as heating, the pressure- It is proposed to adjust so as to cause a phase difference change of the opposite sign.

Korean Patent No. 1114354 discloses a protective film for an optical member having a pressure-sensitive adhesive layer containing a photopolymerizable acrylic polymer, an antistatic agent and a curing agent composition, which causes a crosslinking reaction by radicals generated in the initiator by light irradiation It is possible to omit the aging step at the time of curing and to simplify the manufacturing process, and furthermore, it is possible to reduce the amount of the photopolymerizable acrylic polymer and the polymerization initiator, Discloses a protective film excellent in antistatic property during peeling or use.

Korean Patent Laid-Open Publication No. 2015-0061591 discloses a composition comprising a first functional layer (low moisture-permeable layer) formed using a compound having a cyclic aliphatic hydrocarbon group and an ethylenically unsaturated double bond group, and a composition containing urethane acrylate thereon There is proposed a technique for obtaining a polarizing plate protective film having excellent interlayer adhesion and wind non-uniformity resistance by using a specific amount of a fluoroaliphatic group-containing copolymer having a second functional layer formed thereon and having a specific structure in the first functional layer .

Japanese Patent Application Laid-Open No. 2014-240905 discloses a protective film A, which has a film thickness and an elastic modulus within a specific range and contains an acrylic resin as a main component, in order to produce a polarizer excellent in adhesion to a polarizer, reworkability, planarity, A polarizer and a retardation film B composed mainly of a cellulose derivative having at least an ether bond and a substituent in a glucose skeleton are laminated in this order and both the film A and the film B are bonded via an ultraviolet curable adhesive.

On the other hand, since the acrylic protective film has a stacky characteristic, there is a problem in transportability such as breakage in transporting the film, and blocking property is deteriorated in long-term storage in a roll state, It is necessary to secure sufficient slip and blocking property for

Korea Patent No. 1265007 Korea Patent No. 1114354 Korean Patent Publication No. 2015-0061591 Japanese Laid-Open Patent Application No. 2014-240905

Disclosure of the Invention The present invention has been conceived in order to solve the above problems. It is an object of the present invention to provide an acrylic film having excellent slip and blocking properties, which is produced by a solvent casting method and improved in winding quality, on one side of a polarizer, And a protective film containing a mixed fatty acid cellulose ester having a t-butyryl group is provided on the other surface of the polarizer.

The present invention relates to an acrylic resin composition comprising 70 to 98 parts by weight of a methyl methacrylate unit and 2 to 30 parts by weight of butyl methacrylate based on 100 parts by weight of an acrylic resin represented by the following formula (1) Polymethylmethacrylate {PMMA; A protective film containing a triacetyl cellulose or a mixed fatty acid cellulose ester having acetyl group and butyryl group on an acrylic film formed by a solvent casting method from an acrylic resin composition composed of poly (methyl methacrylate)} particles on one side of a polarizer, Is a polarizing plate provided on the other surface of the polarizer.

[Chemical Formula 1]

a and b are integers of 1 or more.

MMA-BMA

Here, MMA represents a unit of methyl methacrylate (MMA), and BMA represents a unit of butyl methacrylate (BMA).

The polymethyl methacrylate (PMMA; Poly (methyl methacrylate)} particles have a diameter of 1 to 2.0 μm, and the content of the particles relative to the main dope liquid is preferably 100 to 1000 ppm.

In the present invention, it is preferable that the acrylic resin composition includes an acrylic film having a molecular weight of 50,000 g / mol to 2,500,000 g / mol.

In the present invention, it is preferable to use a mixture of a halogenated hydrocarbon and an alcohol as a solvent for solvent casting.

The polarizing plate of the present invention is characterized in that an acrylic film having a coefficient of dynamic friction of 0.7 or less of the acrylic film is provided on one side of the polarizer and a protective film containing triacetyl cellulose or a mixed fatty acid cellulose ester having an acetyl group and a butyryl group And a film is provided on the other surface of the polarizer.

The present invention relates to a polarizing plate comprising a polarizer and a protective film containing triacetyl cellulose or a mixed fatty acid cellulose ester having an acetyl group and a butyryl group, wherein an acrylic film having excellent slip and blocking properties is provided on one side of the polarizer, And is provided on one side to provide a polarizing plate excellent in appearance quality.

1 is a photograph showing a blocking evaluation of the protective film A of Example 1 of the present invention.
2 is a photograph showing a blocking evaluation of the protective film A of Comparative Example 1 of the present invention.
3 is a photograph showing a blocking evaluation of the protective film A of Comparative Example 2 of the present invention.
4 is a photograph showing blocking evaluation of protective film A of Comparative Example 3 of the present invention.

Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited to these.

The inventors of the present invention have conducted intensive studies to develop an acrylic film having excellent peelability of a film when a thin film acrylic film is produced by a solvent casting method. As a result, it has been found that the resin composition has an average molecular weight of 50,000 to 2,500,000 g / The present inventors have found that an acrylic protective film having improved slip and blocking properties and improved winding quality can be obtained. Thus, the present invention has been completed.

The polarizer of the present invention comprises an acrylic resin represented by the following general formula (1) and polymethylmethacrylate {PMMA; Film thickness of 20 to 60 占 퐉 formed from a resin composition containing particles of poly (methyl methacrylate)} and a mixed fatty acid cellulose ester having triacetyl cellulose or acetyl group and butyryl group. Is a polarizing plate having a total film thickness of 60 to 180 占 퐉 in which the protective film B of the protective film B is sandwiched between both surfaces of the polarizer (PVA), and the coefficient of dynamic friction of the protective film A is 0.7 or less.

[Chemical Formula 1]

a and b are integers of 1 or more.

MMA-BMA

Here, MMA represents a unit of methyl methacrylate (MMA), and BMA represents a unit of butyl methacrylate (BMA).

First, the acrylic resin of the present invention will be described. The acrylic resin of the present invention is a copolymer resin comprising a methyl methacrylate unit and a butyl methacrylate unit, wherein each of the monomer units is contained in the form of a repeating unit.

(Meth) acrylate (Methyl Methacrylate) unit, butyl methacrylate (butyl methacrylate) unit, 2 to 30 parts by weight, based on 100 parts by weight of the acrylic resin, in consideration of optical characteristics, transparency, compatibility, By weight. When the content of methyl methacrylate units is in the above range, excellent retardation and optical characteristics can be obtained. When the methylmethacrylate unit content is less than 70 parts by weight, the optical performance of the protective film deteriorates. When the methylmethacrylate unit content exceeds 98 parts by weight, the thickness uniformity of the protective film is lowered.

The content of the butylmethacrylate unit is preferably 2 to 30 parts by weight based on 100 parts by weight of the acrylic resin. When the content of the butyl methacrylate unit is within the above range, preferable optical properties can be obtained.

In the present invention, the addition of silica particles (R812 of EVOKIN Co., Ltd.) as a slip material to further add PMMA particles ensures slip and blocking properties. At this time, the diameter of the PMMA particles is preferably 1 to 2.0 占 퐉. When the diameter of the particles is less than 1 탆, the effect of the desired invention is not sufficiently exhibited, and when the diameter exceeds 2 탆, the quality of the protective film becomes poor. The content of the particles is preferably 100 to 1000 ppm based on the solid content of the main doping solution. If the content of the particles of the PMMA material of the present invention is 100 ppm or less, the blocking between the films is insufficient so that the stacked acrylic films are pressed together. If the content is more than 1000 ppm, the surface is too coarse and scratches may occur.

In the present invention, by adding nanoparticles which are insoluble in solvents and are not deformed in the acrylic resin, the impact strength of the film is improved, and film formation and film transfer are facilitated. As the impact strength improver of the present invention, core-shell rubber (CSR) or silica particles are preferably used. The diameter of the CSR is preferably 100 to 300 nm. When the diameter of the CSR is less than 100 nm, the effect of the intended invention is not sufficiently exhibited, and when the diameter exceeds 300 nm, the quality of the protective film becomes poor.

The content of the silica particles is preferably 0.005 part by weight to 0.1 part by weight based on 100 parts by weight of the main dope liquid, and the content of the core-shell rubber particles (CSR) is preferably 2 parts by weight or more and less than 10 parts by weight . When the content of the nanoparticles of the present invention is in the above range, a protective film excellent in both hardness and flexibility can be provided.

The core shell rubber may be one or more selected from the group consisting of styrene butadiene rubber, polybutadiene (PBD), and acrylic ester, It is preferable to include a graft copolymer having one or more core-shell structures selected from the group consisting of methyl methacrylate (MMA), styrene, and acrylic ester.

The resin composition of the present invention preferably has a molecular weight of 50,000 to 2,500,000 g / mol. If the molecular weight is less than 50,000 g / mol, the production efficiency of the film is lowered. If the molecular weight exceeds 2,500,000, the molding process is not easy. The glass transition temperature (Tg) of the resin composition of the present invention is preferably 120 ° C or more. Even if the glass transition temperature is lower than the above-mentioned range, handling becomes poor, which is not preferable.

The acrylic film of the present invention preferably has a film thickness of 20 to 60 탆. If the thickness of the protective film is less than 20 탆, sufficient retardation characteristics can not be exhibited. If the thickness of the protective film exceeds 60 탆, it is not suitable for use in a thin polarizing plate.

The acrylic film of the present invention preferably has an in-plane retardation Ro defined by the following equation (1) and a retardation Rth in the thickness direction of 10 nm or less under conditions of 23 deg. C and 55% RH.

[Equation 1]

Ro = (nx-ny) * d

Rth = {(nx + ny) / 2-nz} * d

Nx is the maximum refractive index in the horizontal direction in the plane of the film, ny is the maximum refractive index in the vertical direction in the film plane, and nz is the maximum refractive index in the thickness direction of the film.

When the in-plane and thickness retardation exceeds 10 nm, the performance as an isotropic optical film is deteriorated.

The acrylic film of the present invention preferably has a coefficient of dynamic friction of 0.7 or less. When the coefficient of dynamic friction is more than 0.7, the slip property of the film is poor.

Hereinafter, a preferred manufacturing method of the present invention will be described in detail.

Preparation of acrylic polymer resin

To prepare the protective film of the present invention, first, a copolymer resin solution of a methyl methacrylate monomer and a butyl methacrylate monomer is prepared. There is no particular limitation on the method for producing the copolymer of these monomers, and the copolymer can be produced according to a method for producing a copolymer resin well known in the art such as suspension polymerization, emulsion polymerization, bulk polymerization or solution polymerization.

Preparation of Dilute Solutions Containing Acrylic Resin and Nanoparticles

In the present invention, a film is produced by a solvent casting method (solution film forming method). In the solvent casting method, a solution (dope) obtained by dissolving an acrylic copolymer in a casting solvent is cast on a support, and the solvent is evaporated to form a film. The preparation of the dope is carried out by mixing the acrylic copolymer resin solution and the auxiliary additive in the casting solvent.

When a film is produced by a solvent casting method, an organic solvent is preferable as a solvent for preparing an acrylic resin composition (dope). As the organic solvent, it is preferable to use halogenated hydrocarbons, and halogenated hydrocarbons include chlorinated hydrocarbons, methylene chloride and chloroform, among which methylene chloride is most preferably used.

If necessary, organic solvents other than halogenated hydrocarbons may be mixed and used. Organic solvents other than halogenated hydrocarbons include esters, ketones, ethers, alcohols and hydrocarbons. Examples of the ester include methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acylate, ethyl acylate and pentyl acylate. Examples of the ketone include acetone, methyl ethyl ketone, diethyl ketone, di Isobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone and the like can be used. As the ether, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, Ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-butanol and the like can be used. 2-butanol, cyclohexanol, 2-fluoroethanol, 2,2,2, -trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like Lt; / RTI >

More preferably, methylene chloride may be used as the main solvent, and alcohol may be used as the minor solvent. Concretely, a mixed solvent in which the mixing ratio of methylene chloride and alcohol is in the range of 80:20 to 95: 5 is preferable. A solvent mixed with methylene chloride and methanol at a weight ratio of 85:15 is more preferred.

In the production of the acrylic protective film, auxiliary additives may further be used. To the acrylic copolymer solution (dope), auxiliary additives such as ultraviolet ray inhibitor, fine particles, infrared absorbing agent and exfoliating agent may be added in various manufacturing processes depending on the application. The specific kind of such additives can be used without limitation as long as they are commonly used in the field, and the content thereof is preferably used within a range that does not deteriorate the physical properties of the film. The timing of adding the additives depends on the type of additive. A step of adding an additive to the end of the doping treatment may be performed.

As the additive of the present invention, particles of PMMA material were used.

The acrylic resin composition thus obtained can be prepared by ordinary temperature, high temperature or low temperature dissolution.

Film forming process

In the solvent casting method of the present invention, an acrylic resin composition solution is poured on a metal support from a nozzle of a pressurizing die and allowed to stand for a predetermined time to form a semi-dry film. Thereafter, the semi-dried film is peeled from the metal support, transferred to a drying system, and dried to remove the solvent. Then, a uniaxial stretching process or a biaxial stretching process is performed on the dried film. This stretching process

It is possible to improve film uniformity and retardation value of the protective film.

Specifically, the acrylic resin composition solution thus obtained is cast on a support through a casting die to form an acrylic sheet. Here, the support serves to evaporate the solvent present in the casting stock solution and form a film as an acrylic film, while transferring the casting stock solution on the sheet extruded from the die. The support or the surface thereof is preferably made of a metal and has a mirror finished surface, and a steel belt such as a stainless steel belt is preferably used as the support. The surface temperature of the metal support is advantageous because it can accelerate the evaporation of the solvent present in the casting stock solution as the temperature is higher. However, if the temperature is too high, the casting stock solution tends to foam or deteriorate in planarity, But it is preferably 0 to 75 占 폚, more preferably 5 to 45 占 폚. As the support, a metal support in the form of a planar conveyor belt may be used.

The acrylic sheet thus formed is subjected to a stretching step in a tenter, and a glass transition temperature (Tg) of an acrylic flake is at least 110 ° C in the preheating step. The acrylic film of the present invention may be completed in the dryer under the above conditions after having been subjected to the stretching step in the tenter and then the left and right ends of the film whose surface has been damaged by the clip or pin of the tenter are removed.

In the case of using the tenter stretching device, it is preferable to use a device capable of controlling the holding length of the film from the left and right by the left and right gripping means of the tenter. The stretching operation may be carried out by dividing into a plurality of steps or biaxially stretching in the machine direction and the width direction. When biaxial stretching is carried out, simultaneous biaxial stretching may be carried out or may be performed stepwise. In this case, the stepwise means that the stretching in different stretching directions can be performed sequentially, the stretching in the same direction can be divided into multiple steps, and the stretching in the other direction can be added to any one of them. The simultaneous biaxial stretching may include stretching in one direction and relaxation of the other stretch by shrinking. The preferred stretching magnification of the simultaneous biaxial stretching can be in the range of 1.01 to 2.0 times in both the width direction and the longitudinal direction.

The drying means generally blows hot air on both sides of the web, but there is also a means of heating the micro web in place of the wind. Too rapid drying tends to impair the planarity of the finished film.

The acrylic film of the present invention produced by the above method has a coefficient of dynamic friction of 0.7 or less. The present invention is characterized in that the acrylic film is provided on one side of the polarizer, and triacetyl cellulose or There is provided a polarizing plate provided with a protective film containing a mixed fatty acid cellulose ester having an acetyl group and a butyryl group.

Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited by the following examples.

Example  One

≪ Step 1 >

Acrylic acid represented by the following formula (1) was used.

Here, the MMA unit is 95 parts by weight and the BMA unit is 5 parts by weight.

[Chemical Formula 1]

a and b are integers of 1 or more.

<Step 2> Preparation of Diluted Acrylic Polymer Solution Containing Nanoparticles

16.47 parts by weight of the above acrylic polymer solution, 3.69 parts by weight of CSR as nano particles, 0.01 part by weight of silica, and 65.18 parts by weight of methylene chloride and 14.31 parts by weight of methanol were mixed to prepare a diluted acrylic polymer solution containing nanoparticles . In addition to the silica (R812 from EVOKIN) as a slip material, 0.01 wt% of PMMA material particles were added to the entire dope solution. The particles of the PMMA material are MX150 from SOKEN, and the particle size is 1 to 2 탆.

&Lt; Step 3 > Production of protective film A

The dope solution was thoroughly mixed with an inline mixer. The composition of the dope was 65.18 parts by weight of methylene chloride, 14.31 parts by weight of methanol, 16.47 parts by weight of acrylic polymer, 3.69 parts by weight of CSR, 0.33 parts by weight of Tinvuin 928 (manufactured by BASF) 0.01 part by weight of the particles.

Thereafter, the dope liquid was uniformly plied to a stainless steel band support having a width of 2000 mm by using a belt smoothing device. The solvent was evaporated on the stainless steel band support and peeled off from the stainless band support. Then, both ends of the web were gripped with a tenter and stretched so that the stretching magnification in the TD direction was 1.5 times in a temperature environment of 130 占 폚. After the stretching, the stretching was maintained for a few seconds, the tensile force in the width direction was relaxed, the stretching was performed in the width direction, the stretching was continued for 35 minutes in a drying section set at 90 DEG C, An acrylic film having a thickness of 40 m and a knurling width of 10 mm and a height of 8 m was produced.

&Lt; Step 4 > Production of protective film B

Doped with the same conditions as in Example 1, but using triacetyl cellulose (TAC), and the stretching was carried out at a temperature of 180 ° C under 130% stretching.

&Lt; Step 5 > Production of polarizing plate

PVA was laminated using the protective films A and B to prepare a polarizing plate.

Comparative Example  One

A dope was prepared under the same conditions as in Example 1 except that the content of BMA in the acrylic resin was 0 wt% and only the R812 of EVOKIN, a silica particle as a slip material, was added and PMMA material particles were excluded.

Comparative Example  2

A dope was prepared under the same conditions as in Example 1 except that R812 of EVOKIN, a silica particle, was added as a slip material, and PMMA material particles were excluded.

Comparative Example  3

The dope was prepared under the same conditions as in Example 1, except that the content of BMA in the acrylic resin was 0 wt%.

One. Hayes  Measure

The haze of the films of Examples and Comparative Examples 1 to 3 was measured, and the results are shown in Table 1.

2. Coefficient of dynamic friction  Measure

The thus obtained films of the above-mentioned Examples and Comparative Examples 1 to 3 were measured for coefficient of dynamic friction, and the results are shown in Table 1.

3. Evaluation of Blocking

The thus obtained films of the above-described Examples and Comparative Examples 1 to 3 were evaluated for blocking by the following method, and the results are shown in Table 1 and Figs. 1 to 4.

end. Evaluation methods and conditions

- Acryl Air Heat / Gradient Tester (10ea) Measured by pressing on the bar (about 20X1cm) with a constant pressure (6kg / ㎠) to determine the degree of pressing of the film )

- Measurement environment: temperature 24 ± 2 ℃, humidity 30 ± 2%

I. Measuring instrument

- Heat Gradient Tester (One bar type, Pressure 6kg / ㎠)

4. Polarizing plate appearance quality evaluation

The appearance of the polarizing plates of Examples and Comparative Examples 1 to 3 was visually evaluated.

division unit Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Acryl resin - MMA MMA + BMA MMA MMA + BMA Slip material
Type / content ppm EVONIK R812
500ppm EVONIK R812
500ppm EVONIK R812
500ppm
+
SOKEN MX150
500ppm EVONIK R812
500ppm
+
SOKEN MX150
500ppm Surface property Haze % 0.36 0.33 0.31 0.30 Coefficient of friction
(Air / Belt) - 1.12 / 0.94 1.10 / 0.67 1.00 / 0.88 0.48 / 0.55 Roll winding quality Blocking Assessment
(6 kg / cm 2 * 10 min)
24 ° C / 30% Air
/ Belt Pressed Pressed Pressed Good without pressing Polarizer characteristic Protective film B - Made of triacetylcellulose (film thickness 60 mu m) Exterior quality - Scratch, struck, pressed Scratch, struck, pressed Scratch, struck, pressed Good

As shown in Table 1, when the film was formed by solvent casting using the acrylic resin and PMMA particles according to the present invention, the haze, the dynamic friction coefficient, and the blocking evaluation were excellent.

EVONIK R812, which is made of slip silica and has a small particle size, is slip-resistant. SOKEN MX150, which is a PMMA material and has a large particle size, is responsible for blocking properties. Acrylic films are very stacky, but some BMAs with long molecular chains can be included to reduce the stacky characteristics.

Accordingly, as these components are combined together, the acrylic film according to the present invention is excellent in slipperiness and blockability, and thus has good coiling quality,

It can be confirmed that the polarizing plate of the present invention produced using the acrylic film according to the present invention also has a good appearance quality.

Claims (5)

An acrylic resin composition comprising 70 to 98 parts by weight of a methyl methacrylate unit and 2 to 30 parts by weight of butyl methacrylate based on 100 parts by weight of an acrylic resin represented by the following formula (1) Acrylate {PMMA; A protective film containing a triacetyl cellulose or a mixed fatty acid cellulose ester having acetyl group and butyryl group on an acrylic film formed by a solvent casting method from an acrylic resin composition composed of poly (methyl methacrylate)} particles on one side of a polarizer, And a polarizer provided on the other surface of the polarizer.
[Chemical Formula 1]

a and b are integers of 1 or more.
MMA-BMA
Here, MMA represents a unit of methyl methacrylate (MMA), and BMA represents a unit of butyl methacrylate (BMA).
The method according to claim 1,
The polymethyl methacrylate {PMMA; Wherein the diameter of the particles of the poly (methyl methacrylate)} is 1 to 2.0 占 퐉 and the content of the PMMA material is 100 to 1000 ppm with respect to the main dope solution. The acrylic film is provided on one side of the polarizer, Wherein a protective film containing triacetyl cellulose or a mixed fatty acid cellulose ester having an acetyl group and a butyryl group is provided on the other surface of the polarizer.
The method according to claim 1,
Wherein the acrylic resin composition has a molecular weight of 50,000 g / mol to 2,500,000 g / mol. The acrylic film is provided on one side of the polarizer, and is protected with triacetyl cellulose or a mixed fatty acid cellulose ester having an acetyl group and a butyryl group And a film is provided on the other surface of the polarizer.
The method according to claim 1,
A protective film containing triacetyl cellulose or a mixed fatty acid cellulose ester having acetyl group and butyryl group is provided on one side of the polarizer, characterized in that the solvent of the solvent casting is mixed with a halogenated hydrocarbon and alcohol, And a polarizer provided on the other surface of the polarizer.
The method according to claim 1,
Wherein an acrylic film having a coefficient of dynamic friction of 0.7 or less is provided on one side of the polarizer, and a protective film containing triacetyl cellulose or a mixed fatty acid cellulose ester having an acetyl group and a butyryl group is provided on the other side of the polarizer Plane.

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