KR101023181B1 - Optical film, protection film for polarizer film, polarizer plate fabricated therefrom, and display device employing thereof - Google Patents

Abstract

The present invention provides an optical film and a polarizer protective film comprising a copolymer comprising an alken monomer 0.1-30 mol%, an acrylate monomer 30-99 mol% and 0.1-50 mol% unsaturated organic acid monomer having one or more double bonds; It provides a polarizing plate and an image display device using the same.

Optical film, polarizer protective film, polarizer

Description

Optical film, polarizer protective film, polarizer using the same, and image display device using the same {OPTICAL FILM, PROTECTION FILM FOR POLARIZER FILM, POLARIZER PLATE FABRICATED THEREFROM, AND DISPLAY DEVICE EMPLOYING THEREOF}

1 is a hydrogen nuclear magnetic resonance spectrum ( ¹ H-NMR spectrum) of the ethylene-methyl methacrylate copolymer obtained in Comparative Example 1. FIG.

2 is IR of the ethylene-methyl methacrylate-methacrylic acid terpolymer obtained in Example 2. FIG.

3 is a TGA result for the ethylene-methyl methacrylate-methacrylic acid terpolymer obtained in Example 3;

4 is a scanning calorimetry (DSC) graph of the ethylene-methyl methacrylate-methacrylic acid terpolymer obtained in Example 4. FIG.

5 is a gel permeation chromatography (GPC) analysis of the ethylene-methyl methacrylate-methacrylic acid terpolymer obtained in Example 4. FIG.

6 is an IR graph of the ethylene-methyl methacrylate copolymer obtained in Comparative Example 1. FIG.

The present invention relates to an optical film, a polarizer protective film, a polarizing plate using the same, and an image display device using the same.

A polarizing plate generally has a structure in which a polyvinyl alcohol (PVA) -based molecular chain is oriented in a predetermined direction and includes an iodine compound or a dichroic polarizing material, or a dehydration reaction of a polyvinyl alcohol film or a polyvinyl chloride (PVC) film A polarizer having a polyene structure formed by the dehydrochlorination reaction of the present invention has a structure in which a triacetyl cellulose film (hereinafter referred to as a TAC film) is laminated with an aqueous adhesive composed of a polyvinyl alcohol-based aqueous solution as a protective film. .

 The polyvinyl alcohol film used as a polarizer and the TAC film used as a protective film for polarizers do not have sufficient heat resistance and moisture resistance. Therefore, when the polarizing plate made of the above films is used for a long time in an atmosphere of high temperature or high humidity, the polarization degree is lowered, the polarizer and the protective film are separated, or the optical properties are deteriorated. As described above, the polarizing plates that have been put to practical use thus far lack reliability of heat resistance and moisture resistance. In addition, the TAC film has a great change in the in-plane retardation (Rin) and the thickness direction retardation (Rth) in the existing in accordance with the ambient temperature / humidity environment changes, especially the change in the phase difference with respect to the incident light in the oblique direction. When a polarizing plate including a TAC film having such characteristics as a protective film is applied to a liquid crystal display device, there is a problem in that the viewing angle characteristic changes according to a change in the ambient temperature / humidity environment, thereby degrading image quality. In addition, the TAC film has a large dimensional change rate according to the change of the ambient temperature / humidity environment, and the photoelastic coefficient value is also relatively large, and the image quality is degraded due to the change of the phase difference locally after the durability evaluation in the heat and moisture resistant environment. Easy to be

Methacrylic (methacryl) resin is well known as a material for compensating for the various disadvantages of the TAC film. However, it is known that methacryl-based resins are brittle or cracked, which is a problem in the carrier property in the production of polarizers and is insufficient in productivity.

In order to solve this problem, a method of blending other resins or toughness modifiers with acrylic resins (Japanese Patent Laid-Open No. 2006-284881, Japanese Patent Laid-Open No. 2006-284882) or a method of co-extrusion and laminating other resins (Japanese Patent Laid-Open No. 2006-243681, Japanese Patent Laid-Open No. 2006-215463, Japanese Patent Laid-Open 2006-215465, and Japanese Patent Laid-Open No. 2007-017555) have been proposed. However, these methods do not sufficiently reflect the inherent high heat resistance and high transparency of the acrylic resin or have a complicated laminate structure.

The present invention is not only excellent in optical transparency and optical properties, but also in brittleness (brittleness) is improved, the change in the dimensional change rate and optical properties according to the environmental changes of the ambient temperature and humidity, the optical film excellent in durability and An object of the present invention to provide a high quality polarizer protective film, a polarizing plate, an image display device using the same.

In order to achieve the above object, the present invention includes a copolymer comprising 0.1 to 30 mol% of alkene monomers, 30 to 99 mol% of acrylate monomers and 0.1 to 50 mol% of unsaturated organic acid monomers having at least one double bond. It provides an optical film.

The present invention also provides a polarizer protective film comprising a copolymer comprising an alken monomer 0.1-30 mol%, an acrylate monomer 30-99 mol% and an unsaturated organic acid monomer 0.1-50 mol% having one or more double bonds. do.

In addition, the present invention includes a polarizer and a protective film provided on at least one side of the polarizer, the protective film is unsaturated unsaturated having at least one alken monomer 0.1-30 mol%, acrylate monomer 30-99 mol% and a double bond It provides a polarizing plate comprising a copolymer comprising 0.1 to 50 mol% of an organic acid monomer.

In addition, the present invention provides an image display device including the polarizing plate.

Hereinafter, the present invention will be described in detail.

The optical film according to the present invention is characterized in that it comprises a copolymer comprising 0.1-30 mol% of alkene monomers, 30-99 mol% of acrylate monomers and 0.1-50 mol% of unsaturated organic acid monomers having at least one double bond. do.

In the present invention, the copolymer refers to a copolymer formed by polymerization of an alkene monomer, an acrylate monomer and an unsaturated organic acid monomer, and for convenience, expresses its structure in terms of monomers, and actually monomers in the main chain of the copolymer. Of these, the double bond does not exist as it will be readily understood by those of ordinary skill in the art.

In the present invention, the alkene monomer is not particularly limited and may include alkenes such as 1-alkene having a double bond at the end of the carbon chain, 2-alkene having a double bond in the middle of the carbon chain, 3-alkene and the like. Can be.

Examples of 1-alkenes include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. Examples of the alkenes having a double bond in the middle of the carbon chain include 2-butene, 2-pentene, 2-hexene, 3-hexene, 2-heptene, 2-octene, 2-nonene and the like.

The content of the alkene monomer in the copolymer is 0.1 to 30 mol%, preferably 10 to 30 mol%. If the polymer is composed of only monomers including polar groups without alken monomers, there is a problem of brittleness when the film is formed. In particular, the content of the alkene monomer in the copolymer of 10 mol% or more is less prone to breakage when applied to the laminated film of the optical material.

In the present invention, the acrylate monomer is sufficient as long as it has a compound having a double bond between the carbonyl group of the ester group and the conjugated (conjugated) carbon and its substituent is not particularly limited. The acrylate-based monomers described herein are to be understood to include not only acrylates but also acrylate-based derivatives, and include concepts such as alkyl acrylates, alkyl methacrylates, alkyl butacrylates, and the like.

Specifically, examples of the acrylate-based monomer include a compound represented by the following formula (1):

In Formula 1,

R ₁ , R ₂ and R ₃ are the same as or different from each other, and each independently represent a hydrogen atom, a monovalent hydrocarbon group having 1 to 30 carbon atoms which may include a hetero atom; R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

As another example, the acrylate monomer may be an alkyl acrylate including a straight or branched alkyl group having 1 to 12 carbon atoms of alkyl, or an alkyl methacrylate including a straight or branched alkyl group having 1 to 12 carbon atoms of alkyl. Or alkyl butyacrylate containing a straight or branched alkyl group having 1 to 12 carbon atoms of alkyl.

The content of the acrylate monomer in the copolymer is 30 to 99 mol%, preferably 35 to 99 mol% or 40 to 99 mol%, more preferably 50 to 99 mol% or 50 to 95 mol%, most Preferably it is 50-90 mol%.

When the content of the acrylate-based comonomer, which is the polar monomer, increases, it is possible to prevent crystallinity, which is inherent in 1-alkenes such as alkenes, in particular ethylene, to prepare an amorphous copolymer. Such amorphous 1-alkene-acrylate-based copolymers were difficult to manufacture by the prior art. The amorphous copolymer can be used as an optical material because of its high transparency and excellent adhesiveness. In particular, the amorphous copolymer has many polar functional groups, and thus has excellent adhesion to metals, and thus is advantageous for application to electrical devices.

In the reaction, when the amount of the acrylate-based comonomer is less than 30 mol% based on the total amount of monomers, there is a problem in bonding and transparency, and when it exceeds 99 mol%, there is a problem of brittleness. In addition, in order to apply the copolymer to the laminated film for an optical material, the amount of the acrylate-based monomer is preferably adjusted to 95 mol% or less, more preferably 90 mol% or less in order to alleviate the fracture property during film formation.

In the present invention, the unsaturated organic acid monomer has one or more double bonds and refers to radical polymerization possible by the double bonds, and unless specifically specified otherwise having one or more double bonds, unless otherwise specified, a double bond It should be understood to have one or more.

It is preferable that the said unsaturated organic acid monomer has one or more carboxylic acid. The unsaturated organic acid monomer is more preferably an unsaturated carboxylic acid compound having a double bond between a carboxyl group and conjugated carbons, and their substituents are not particularly limited. Specifically, as the unsaturated organic acid monomer, monovalent or polyvalent carboxylic acids such as monovalent carboxylic acids such as acrylic acid and divalent carboxylic acids such as maleic acid may be preferably used, but are not necessarily limited thereto.

When the unsaturated organic acid monomer is acrylic acid, the acrylic acid is preferably an acrylic acid compound represented by the following formula (2), but other acrylic acid derivatives such as alkyl methacrylic acid may also be used:

In Chemical Formula 2,

R ₆ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

Examples of the divalent carboxylic acid include maleic acid and maleic acid derivatives substituted with at least one alkyl group.

The content of the unsaturated organic acid monomer in the copolymer is 0.1 to 50 mol%, preferably 0.1 to 30 mol%. When the unsaturated organic acid monomer is introduced as a component of the copolymer, the copolymer has a high glass transition temperature, and because of its excellent adhesiveness due to hydrophilic functional groups, it can be used as an optical material.

The copolymer composed of repeating units of the aforementioned monomers may include repeating units represented by the following Formula 3:

In Chemical Formula 3,

a, b and c are molar ratios, where a, b and c are not all zero,

R ₁ to R ₄ and R ₆ are as described above, and R ₅ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

The copolymer may be a random copolymer, in which case it may include various repeating units represented by the formula (3).

The copolymer has a glass transition temperature (Tg) in the range of 80 to 220 ° C, preferably in the range of 100 to 220 ° C. In order for the copolymer to be effectively used for an optical material, the copolymer preferably has a glass transition temperature of 100 ° C. or higher. In addition, the copolymer preferably has a number average molecular weight in the range of 5,000 to 400,000 or a weight average molecular weight in the range of 10,000 to 800,000, and the temperature (Td50) at which 50% of the initial weight of the copolymer is decomposed is 350 to 550 ° C. It is desirable to have a range.

The above-mentioned copolymer is a copolymer of the above-described monomers, so that the content of the polar group is very high so that the crystallinity of alkenes such as ethylene does not exist, and thus it is transparent even after processing into a polymer film or the like, and thus contains an unsaturated organic acid such as acrylic acid. It has a glass transition temperature and improves adhesiveness, and thus may be suitably used for the use of an optical film having a multilayer structure including a polarizing plate.

In addition, the alkene-acrylate-unsaturated organic acid copolymer described herein may be composed of one alkene, one acrylate and one unsaturated organic acid as its monomer component, as well as the alkene, acrylate And at least one of unsaturated organic acids may be composed of two or more kinds. In addition, without departing from the scope of the physical properties of the polymer and the object of the present invention, it may further comprise a comonomer. Examples of the comonomers include maleimide, methyl maleimide, ethyl maleimide, butadiene, styrene and the like.

The copolymer may be prepared by a method comprising polymerizing an alkene monomer, an acrylate monomer, and an unsaturated organic acid monomer having at least one double bond with a radical polymerization initiator in the presence of a Lewis acid or a metal oxide.

The metal oxide is conceptually included in the Lewis acid because it serves as a Lewis acid which provides an acid site in the polymerization reaction. However, compared to other Lewis acids in general, there is no change in structure or composition substantially after the polymerization reaction, and thus, there is an additional advantage that not only can be easily separated but also reused. It is called an oxide or a complex metal oxide.

The metal oxide is preferably a compound represented by the following formula (4):

M _x N _y O _z

In Chemical Formula 4,

M represents at least one selected from the group consisting of alkaline earth metals, transition metals, group 13, and group 14 metals;

N represents a Group 5 or 6 atom;

O represents an oxygen atom;

x, y and z are values determined by the oxidation state of M and N,

x> 0, y> 0, and z> 0.

More specifically, the metal oxide is aluminum oxide (Al ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), zinc oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), cesium oxide (CeO ₂ ), dysprosium oxide (Dy ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), europium oxide (Eu ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), Holmium oxide (Ho ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), ruthetium oxide (Lu ₂ O ₃ ), neodymium oxide (Nd ₂ O ₃ ), praseodymium oxide (Pr ₆ O ₁₁ ), samarium oxide (Sm ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), thorium oxide (Th ₄ O ₇ ), thorium oxide (Tm ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), tin oxide (SnO), and titanium oxide ( Metal oxides such as TiO ₂ ), dysprosium aluminate (Dy ₃ Al ₅ O ₁₂ ), yttnium aluminate (Y ₃ Al ₅ O ₁₂ ), aluminum titanate (Al ₂ O ₃ · TiO ₂ ), aluminum silicate (3Al ₂ O ₃ · 2SiO ₂ ), calcium titanate (CaTiO ₃ ), calcium zirconate (CaZrO ₃ ), iron Selected from the group consisting of complex metal oxides such as titanate (FeTiO ₃ ), magnesium aluminate (MgOAl ₂ O ₃ ), cesium aluminate (CeAl ₁₁ O ₁₈ ), Al ₂ (SO ₄ ) ₃ , and AlPO ₄ It is preferred that there is at least one.

The metal oxide can be recovered to near 100% even by a physical method using only a filtration device, and since the recovered metal oxide can be used for polymerization again, it is not only economical but also high-purity copolymer can be obtained. There is an advantage. The recovered metal oxide can generally be reused about 20 times.

The Lewis acid includes at least one metal cation selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, boron, aluminum, yttrium, zirconium, niobium, molybdenum, cadmium, rhenium, and tin. a Lewis acid is preferable to be formed, including, and halide, triflate (triflate), HPO ₃ ^2-, H ₃ PO ^{2 -,} CF ₃ COO ^-, C ₇ H ₁₅ OSO ^{2 -} and the group consisting of SO ₄ ^2- It is preferable to include at least one anion selected from. More specifically, it is preferable that they are aluminum trichloride, scandium triflate, zinc triflate, copper triflate, trifluoroboron, a mixture of two or more thereof.

In the method of preparing the copolymer, the metal oxide or the Lewis acid is preferably used in an amount of 0.01 to 200 mol% based on the acrylate comonomer.

By using the metal oxide or Lewis acid, it is possible to appropriately control and control the content of the monomers contained in the repeating unit in the copolymer produced according to the required physical properties. Particularly when the alkene monomer present in the gas phase under the reaction conditions such as ethylene or propylene is partially dissolved in the solvent to participate in the polymerization reaction, the metal oxide or Lewis acid is polymerized in an appropriate amount of the alkene monomer necessary for the required physical properties of the copolymer prepared. It may serve to control as possible, and also serves to make the polymerization reaction at a low temperature low pressure compared to the prior art.

It is preferable that it is a peroxide, an azo compound, etc. as said radical polymerization initiator. More specifically, examples of the peroxide compound include hydrogen peroxide, decanonyl peroxide, t-butyl peroxy neodecanoate, t-butyl peroxy pivalate, 3,5,5-trimethyl hexanoyl peroxide, diethyl peroxide t-butyl peroxy-2-ethyl hexanoate, t-butyl peroxy isobutyrate, benzoyl peroxide, t-butyl peroxy acetate, t-butyl peroxy benzoate, di-t-butyl peroxide, t Amyl peroxy neodecanoate, t-amyl peroxy pivalate, t-amyl peroxy-2-ethyl hexanoate, 1,1,3,3-tetramethyl butyl hydroperoxide, alkali metal persulfate, Perborate and percarbonate, and examples of azo compounds include azo compounds such as 2,2'-azo-bis (isobutyronitrile) (AIBN) (2,2'-azo-bis (isobutyronitrile)). Can be mentioned. Preferred initiators are azo compounds. Mixtures of such initiators may also be used.

The radical polymerization initiator can be added to the reaction stream in any suitable manner, such as in pure form, in dissolved form in a suitable solvent and / or in admixture with a monomer or comonomer feed stream. The radical polymerization initiator used in preparing the copolymer is preferably added in the range of 0.01 to 10 mol% based on the acrylate monomer, but is not necessarily limited thereto, and may be appropriately used if necessary.

The polymerization of the copolymer is preferably carried out in a solvent, in particular an organic solvent. Examples of such solvents are preferably, but not necessarily limited to, one or more solvents selected from the group consisting of toluene, chlorobenzene, n-hexane, heptane, tetrahydrofuran, ether, methanol, ethanol, chloroform, and methylene chloride. . That is, the solvent that can be used in the technical field of the present invention is not particularly limited.

In the polymerization reaction, the acrylate monomer and the unsaturated organic acid monomer are generally present in the liquid phase under the reaction conditions, so that they are dissolved in a solvent and participate in the polymerization reaction. Therefore, the reaction pressure is not particularly limited as long as the monomers included in the aforementioned copolymer may exist in the liquid phase under the reaction conditions.

On the other hand, since the alkene monomer is generally present in the gaseous state under the reaction conditions, especially in the case of ethylene and propylene, in order to contain the alkene monomer in an appropriate amount in the repeating unit of the copolymer of the present invention, the reaction conditions under pressure are required. If the alkene monomer is present in the liquid phase under the reaction conditions, the reaction pressure is not particularly limited.

The polymerization reaction is carried out under mild conditions of 200 atm and 150 ° C or less, preferably 50 atm or less and 100 ° C or less, unlike the prior art which requires harsh reaction conditions of at least 1000 atm and at least 100 ° C and high temperature and high pressure. The process can be simple, and the physical properties of the copolymer produced can be easily controlled. In addition, the metal oxide is particularly excellent in water safety, efficient and recyclable.

Specifically, the reaction conditions for the polymerization of the copolymer, when the alkene monomer is gaseous in the reaction conditions, the polymerization reaction is preferably made at a pressure of 5 to 200 atm and temperature conditions of 30 to 150 ℃, particularly preferably The reaction is carried out at a pressure of 20 to 50 atm and a temperature of 50 to 80 ℃.

One specific embodiment of the invention is 5 to 50 using ethylene or propylene as an alkene monomer, methyl methacrylate or methylacrylate as an acrylate monomer, methacrylic acid or acrylic acid as unsaturated organic acid monomer, and aluminum oxide as metal oxide. The polymerization is carried out using AIBN as a polymerization initiator at a pressure of atmospheric pressure and a temperature of 50 to 80 ° C.

The alkene-acrylate-acrylic acid terpolymer in the copolymer may be prepared by partially hydrolyzing the alkene-acrylate binary copolymer. Partial hydrolysis can be carried out under reaction conditions for conventional hydrolysis by appropriately selecting the type of acid or base catalyst and the reaction medium for hydrolysis. In this case, the content of acrylate in the alkene-acrylate binary copolymer used as raw material should be the sum of the content of acrylate and acrylic acid of the tertiary copolymer to be produced and is also required in the final terpolymer. Proper hydrolysis conditions must be set so that the monomer content ratio can be established. Such hydrolysis conditions may include the type of acid or base catalyst for hydrolysis, the type of reaction medium, the reaction temperature, the reaction pressure, the reaction time, and the like. By selecting the hydrolysis rate can be appropriately selected.

The method for producing the optical film according to the present invention using the copolymer described above is not particularly limited, and for example, a melt extrusion method, a calender film forming method, a solution cast film forming method, or the like can be used. The melt extrusion method is a method in which a copolymer is heated and melted in a cylinder, pressurized with a screw, and then discharged out from a die such as a T die. Referring to the melt extrusion temperature, the extruder internal temperature is 230 ° C, 240 ° C, 240 ° C, 245 ° C from the extruder inlet, and the die temperature is preferably 250 ° C. The said solution cast film forming method is a method of manufacturing a copolymer resin solution with an organic solvent, then forming into a film, drying a solvent, and winding up.

 In order to manufacture the optical film, general additives such as plasticizers, lubricants, impact modifiers, stabilizers, ultraviolet absorbers, and the like may be added to the copolymer resin. In particular, when the optical film according to the present invention is used as a protective film of the polarizer, in order to protect the polarizer and the liquid crystal panel from external ultraviolet rays, an ultraviolet absorber may be added to the copolymer resin. Although the kind of ultraviolet absorber is not specifically limited, The use of a benzotriazole type ultraviolet absorber and a triazine type ultraviolet absorber is preferable. Preferably Tinuvin P and Tinuvin 360 can be used. As the heat stabilizer, Iganox 259, Iganox 1010, or the like may be added.

Since the optical film including the copolymer as described above is manufactured using a copolymer resin having high light transmittance, glass transition temperature and toughness, the optical film has high optical transparency and excellent adhesion due to the high content of monomer having polar functional groups. Therefore, it is suitable for use as a laminated film such as a polarizing plate. In addition, the optical film according to the present invention not only has excellent optical properties, but also changes in dimensional change rate and optical properties according to temperature and humidity, and thus can be used as various optical films.

The present invention also provides a polarizer protective film comprising a copolymer comprising an alken monomer 0.1-30 mol%, an acrylate monomer 30-99 mol% and an unsaturated organic acid monomer 0.1-50 mol% having one or more double bonds. do.

The thickness of the polarizer protective film according to the present invention is preferably 20 to 200μm.

The polarizer protective film according to the present invention can modify the surface of the protective film to improve the adhesion. Modification methods include a method of treating the surface of the protective film by corona treatment, plasma treatment, UV treatment, and the like to form a primer layer on the surface of the protective film, and the above two methods may be used at the same time. Although the kind of primer is not specifically limited, It is preferable to use the compound which has a reactive functional group like a silane coupling agent.

In addition, the present invention includes a polarizer and a protective film provided on at least one side of the polarizer, the protective film is unsaturated unsaturated having at least one alken monomer 0.1-30 mol%, acrylate monomer 30-99 mol% and a double bond It provides a polarizing plate comprising a copolymer comprising 0.1 to 50 mol% of an organic acid monomer.

In the present invention, as the polarizer can be used without limitation what is known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or dichroic dye can be used. The polarizer may be prepared by dyeing iodine or dichroic dye on the PVA film, but a method of manufacturing the same is not particularly limited. In the present specification, the polarizer means a state not including a protective film, and the polarizing plate means a state including a polarizer and a protective film.

Adhesion of the polarizer and the protective film may be performed using an adhesive layer. The adhesive usable in lamination of the protective film and the polarizing plate is not particularly limited as long as it is known in the art. For example, there are one- or two-component polyvinyl alcohol (PVA) adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, and hot melt adhesives, but are not limited to these examples.

Among the adhesives, a polyvinyl alcohol adhesive is preferable, and in particular, it is preferable to use an adhesive containing a polyvinyl alcohol resin containing an acetacetyl group and an amine metal compound crosslinking agent. The adhesive for the polarizing plate may include 100 parts by weight of the polyvinyl alcohol-based resin containing the acetacetyl group and 1 to 50 parts by weight of the amine-based metal compound crosslinking agent.

The polyvinyl alcohol-based resin is not particularly limited as long as it can sufficiently adhere the polarizer and the transparent protective film, have excellent optical transparency, and there is no change in yellowing over time, but in particular, considering a smooth crosslinking reaction with a crosslinking agent, It is preferable to use polyvinyl alcohol-type resin containing an acetacetyl group.

Here, the polymerization degree and saponification degree of the polyvinyl alcohol-based resin is not particularly limited as long as it contains an acetacetyl group. Preferably, the polymerization degree is in the range of 200 to 4,000, and the saponification degree is 70 mol% to 99.9 mol%. It is good to be in range. Considering the flexible mixing with the containing material according to the freedom of molecular movement, the degree of polymerization is in the range of 1,500 to 2,500, and the degree of saponification is more preferably in the range of 90 mol% to 99.9 mol%. In this case, the polyvinyl alcohol-based resin preferably comprises 0.1 to 30 mol% of the acetacetyl group. This is because the reaction with the crosslinking agent may be smooth in the range of the acetacetyl group, and sufficiently pays attention to the water resistance and adhesion of the desired adhesive.

The amine-based metal compound crosslinking agent is a water-soluble crosslinking agent having a functional group having reactivity with the polyvinyl alcohol-based resin, preferably in the form of a metal complex containing an amine ligand. Possible metals include zirconium (Zr), titanium (Ti), hafnium (Hf), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), osmium (Os), Transition metals such as rhodium (Rh), iridium (Ir), palladium (Pd), and platinum (Pt) are possible, and ligands bound to the central metal are primary amines, secondary amines (diamines), tertiary amines and ammonium hydrides. It is possible to include at least one or more amine groups, such as locksides. Its amount is preferably adjusted in the range of 1 part by weight to 50 parts by weight based on 100 parts by weight of the polyvinyl alcohol-based resin. This is because it is possible to impart sufficiently significant adhesive strength to the desired adhesive within the above range, and to improve the pot life of the adhesive.

PH of the aqueous solution containing the polyvinyl alcohol-based resin containing the acetacetyl group and the amine-based metal compound crosslinking agent as the adhesive for the polarizing plate may be 9 or less.

Here, it is preferable that the pH of the adhesive aqueous solution containing the polyvinyl alcohol-based resin containing the acetacetyl group and the amine-based metal compound crosslinking agent is adjusted to 9 or less using a pH adjusting agent. More preferably, the pH can be adjusted in the range of 2 seconds and 9 or less, and more preferably in the range of 4 to 8.5.

The adhesion of the polarizer and the protective film is first coated with an adhesive using a roll coater, a gravure coater, a bar coater, a knife coater, or a capillary coater on the surface of a polarizing film or a PVA film that is a polarizing film. It may be carried out by a method of laminating the protective film and the polarizing film by heating or pressing at room temperature before it is completely dried. In the case of using a hot melt adhesive, a heat press roll should be used.

When using a polyurethane adhesive, it is preferable to use the polyurethane adhesive manufactured using the aliphatic isocyanate compound which is not yellowed by light. When using one-component or two-component dry laminate adhesives or adhesives with relatively low reactivity between isocyanates and hydroxyl groups, a solution type diluted with an acetate solvent, a ketone solvent, an ether solvent, or an aromatic solvent, etc. Adhesives can also be used. At this time, the adhesive viscosity is preferably low viscosity of 5000 cps or less. The adhesives are excellent in storage stability and preferably have a light transmittance of 90% or more at 400 to 800 nm.

A tackifier can also be used if it can exert sufficient adhesive force. The adhesive is preferably cured by heat or ultraviolet rays after lamination, and thus the mechanical strength is improved to the level of the adhesive. The adhesive strength is also large, and thus the adhesive strength is such that the adhesive cannot be peeled off without breaking of either film to which the adhesive is attached. It is preferable.

Specific examples of the pressure-sensitive adhesives that can be used include natural rubber, synthetic rubber or elastomer having excellent optical transparency, a vinyl chloride / vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate, modified polyolefin-based pressure-sensitive adhesive, and a curing type in which a curing agent such as isocyanate is added thereto. An adhesive is mentioned.

The polarizing plate of the present invention manufactured as described above can be used in various applications. Specifically, it can be preferably used for an image display device including a polarizing plate for liquid crystal display (LCD), an anti-reflective polarizing plate of an organic EL display device, and the like. In addition, the polarizing plate according to the present invention combines various optical layers such as retardation plates, light diffusing plates, viewing angle expanding plates, brightness enhancing plates, reflecting plates such as various functional films, for example, λ / 4 plates, λ / 2 plates, and the like. It can be applied to one composite polarizer.

The polarizing plate according to the present invention may be provided with a pressure-sensitive adhesive layer on at least one surface so as to be easily applied to an image display device. In addition, a release film may be further provided on the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer until the polarizing plate is applied to an image display device or the like.

In addition, the present invention provides an image display device including the polarizing plate.

For example, the present invention includes a light source, a first polarizing plate, a liquid crystal cell, and a second polarizing plate sequentially stacked, and at least one of the first and second polarizing plates is provided on at least one surface of the polarizer and the polarizer. It includes a film, wherein the protective film comprises a copolymer comprising 0.1 to 30 mol% of alkene monomers, 30 to 99 mol% of acrylate monomers and 0.1 to 50 mol% of unsaturated organic acid monomers having at least one double bond. A liquid crystal display device characterized in that it is a polarizing plate characterized by. The liquid crystal cell is a liquid crystal layer; A substrate capable of supporting this; And an electrode layer for applying a voltage to the liquid crystal. At this time, the polarizing plate according to the present invention is an in-plane switching mode (IPS mode), vertically aligned (VA mode), OCB (Optically Compensated Birefringence mode), twisted nematic mode (Twisted Nematic mode) TN mode) and FFS (Fringe Field Switching mode; FFS mode).

In the image display apparatus according to the present invention, the polarizer protective film according to the present invention may be arranged as an inner protective film on the liquid crystal cell side of the polarizing plate and / or at the same time as an outer protective film on the opposite side of the liquid crystal cell of the polarizing plate. .

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention and the scope of the present invention is not limited to the contents of the following examples.

The organic reagents and solvents required for the polymerization were purified by a standard method by Aldrich, and ethylene was polymerized after passing a high purity product of Applied Gas Technology through a water and oxygen filtration device.

In order to obtain a monomer content ratio in the copolymer, spectra were obtained using 500 MHz NMR manufactured by Varian. The glass transition temperature (Tg), which is a thermal property of the obtained polymer, was measured by DSC Q100 from TA Instrument, and Td_50 (50% pyrolysis temperature) was used as TGA of the same company.

Molecular weight and molecular weight distribution were obtained by gel permeation chromatography (GPC) analysis from Waters. The analytical temperature was 25 ° C., tetrahydrofuran (THF) was used as the solvent, and standardized with polystyrene to obtain the number average molecular weight (Mn) and the weight average molecular weight (Mw).

Ethylene-acrylate Copolymer

Comparative Example 1

The 125 mL high pressure reactor was evacuated and filled with argon. 28 mmol of methyl methacrylate and 28 mmol of alumina were added to an argon atmosphere reactor. And 0.084 mmol of initiator AIBN dissolved in toluene was added. Subsequently, after charging 35 bar of ethylene, the reactor temperature was raised to 75 ° C. and polymerization was performed for 18 hours.

Comparative Example 2

Polymerization was carried out in the same manner as in Comparative Example 1 except that alumina was not added.

The polymerization conditions and results of Comparative Example 1 and Comparative Example 2 are shown in Table 1 and Table 2. An NMR spectrum ( ¹ H-NMR spectrum) as a result of polymerization analysis of Comparative Example 1 is shown in FIG. 1, and an IR spectrum as a result of polymerization analysis of Comparative Example 1 is shown in FIG. 6.

Reaction dosage Polymerization condition [menstruum]
/ [Monomer]
(Volume ratio) [Mountain Lewis]
/ [MMA]
(mole rain) [Initiator]
/ [Monomer]
(mole rain) Ethylene
pressure
(bar) Temperature
(℃) time
(h) Comparative Example 1 9 One 0.003 35 75 18 Comparative Example 2 9 0 0.003 35 75 18

In Table 1, [monomer] means the volume or number of moles of MMA.

Tg (占 폚) Mn Mw PDI Td_50
(℃) Ethylene Content
(mole%) Comparative Example 1 92 29900 49000 1.64 433 14 Comparative Example 2 99 50500 71700 1.42 427 9.7

As a result of the experiment of Comparative Example 1, an ethylene-methyl methacrylate random copolymer having an ethylene content of 14 mole% was polymerized. Comparative Example 2 is a result of free radical polymerization in the state in which alumina is not added as compared with the polymerization conditions of Comparative Example 1, and a random copolymer containing 9.7 mol% having reduced ethylene content compared to Comparative Example 1 was polymerized. Since the ethylene content was reduced, the glass transition temperature was obtained higher than that of Comparative Example 1.

This result shows that the addition of alumina has an effect of increasing the ethylene content in the copolymer, and the glass transition temperature is lowered when the ethylene content is increased. These two polymers can be produced as a highly transparent optical film having good moldability because the ethylene content is more than 10mole%, but the glass transition temperature is less than 100 degrees has a disadvantage of lacking heat resistance to apply to the optical film. That is, the film formation is good by supplementing the fragile property of the acrylate by increasing the content of ethylene, but the application range is limited due to the low glass transition temperature.

1-alkene-acrylate-acrylic acid copolymer

Example 1

 The 125 ml Parr high pressure reactor was evacuated and filled with argon. 28 mmol of methyl methacrylate (MMA), 5.6 mmol of methacrylic acid (MAA), and 28 mmol of alumina were added to Lewis acid in an argon atmosphere reactor. And 0.056 mmol of initiator AIBN dissolved in toluene was added. Subsequently, after charging 35 bar of ethylene, the reactor temperature was raised to 65 ° C. and polymerization was performed for 18 hours.

After the polymerization, the polymerization solution was removed alumina through a filter, and precipitated in ethylene or hexane. The obtained polymer was dried at a temperature below Tg under reduced pressure for 24 hours.

Example 2

The polymerization was carried out in the same manner as in Example 1 except that the solvent amount and the MAA amount were adjusted. IR result of the obtained copolymer is shown in FIG.

Example 3

The polymerization was carried out in the same manner as in Example 1 except that the amount of MAA charged was adjusted. The TGA results for the obtained copolymer are shown in FIG. 3.

Example 4

Polymerization was carried out in the same manner as in Example 1 except that the alumina was not added and the amount of MAA was adjusted. Scanning calorimetry (DSC) graph and gel permeation chromatography (GPC) analysis of the obtained copolymer are shown in FIGS. 4 and 5, respectively.

As a result of Examples 1 to 4, an ethylene-MMA-MAA terpolymer having a glass transition temperature of 140 ° C. or more was synthesized. The low glass transition temperature problem, which is a disadvantage of the copolymer synthesized in the comparative example, was solved, and the 50% pyrolysis temperature measured by TGA was obtained as high as 450 degrees or more. The higher the ethylene content, the lower the glass transition temperature, and the higher the acrylic acid content, the higher the glass transition temperature, so that polymers suitable for the desired heat resistance and physical properties can be synthesized according to the polymerization conditions.

Example 5

The amount of MAA input was reduced to 0.1 mole ratio compared to MMA, and the amount of toluene, a reaction solvent, was increased. The polymerization temperature was 70 degrees, the concentration of the initiator was reduced to 0.001 mole ratio relative to the monomer and reacted for 6 hours. Alumina was used as the Lewis acid.

When the results of Example 5 and the results of Examples 1 to 4 are compared, the brittleness of the film is improved due to the high ethylene content, which is more preferable as the optical film. Compared with Comparative Example 1, despite the higher ethylene content, the higher Tg is due to the ternary copolymer containing MAA and Tg is 121 degrees, thereby securing heat resistance applicable to the LCD film processing process.

Example 6

As the Lewis acid, titanium oxide (Ti ₂ O ₃ ) was added instead of alumina, and polymerization was carried out in the same manner as in Example 5 except that the amount of the solvent added was reduced.

As a result of Example 6, the use of titanium oxide gave similar results as with alumina, and various metal oxides could be applied as Lewis acids.

Example 7

The polymerization was carried out in the same manner as in Example 6 except that maleic acid, which is a divalent acid, was added instead of the monovalent acid, MAA, as acrylic acid, and the amount of the solvent added was reduced.

As in the result of Example 7, divalent acid is also applicable, and the dosage can be adjusted to produce a polymer of the desired physical properties.

Example 8

The polymerization was carried out in the same manner as in Example 7, except that maleic anhydride was added instead of maleic acid. The obtained ethylene-methyl methacrylate-maleic anhydride ternary random copolymer was dissolved in tetrahydrofuran, poured into an aqueous hydrogen chloride solution, and then stirred at 50 ° C. for 24 hours to carry out a post reaction.

As a result of Example 8, it was confirmed by IR that maleic anhydride was changed to maleic acid (maleic acid) form through a hydrolysis reaction in the presence of an acid. After copolymerizing with maleic anhydride, it was confirmed that similar terpolymer copolymerization as in Example 7 was possible through post-reaction. By controlling the degree of hydrolysis reaction, it can also be changed to ethylene-methyl methacrylate-maleic anhydride-maleic acid quaternary random copolymer.

Example 9

The ethylene-methyl methacrylate copolymer polymerized in Comparative Example 1 was subjected to a hydrolysis reaction as in Example 8. A portion of methyl methacrylate was converted to methacrylic acid through a hydrolysis reaction in the presence of an acid, and IR was confirmed to form a hydroxyl group of the acid.

As a result of Example 9, Tg and heat distortion temperature (Td) were increased while being converted to ethylene-methyl methacrylate-methacrylic acid terpolymer, and there was no significant change in molecular weight. In this manner, the ternary copolymer can be synthesized through the hydrolysis reaction.

The polymerization conditions and results of Examples 1 to 9 are shown in Tables 3 and 4. Meanwhile, the IR spectrum of the polymerization analysis of Example 2 is shown in FIG. 2, the TGA spectrum of the polymerization analysis of Example 3 is shown in FIG. 3, and the DSC spectrum of the polymerization analysis of Example 4 is shown in FIG. 4. And GPC spectra, which are the results of polymerization analysis of Example 4, are shown in FIG. 5.

Reaction input Lewis Mountain Monomer input Initiator Polymerization condition [menstruum]
/ [Monomer]
(Volume ratio) [Alumina]
/ [MMA]
(mole rain) [Titanium oxide]
/ [MMA]
(mole rain) [MAA]
/ [MMA]
(mole rain) [Maleic acid]
/ [MMA]
(mole rain) [Maleic anhydride]
/ [MMA]
(mole rain) Ethylene
pressure
(bar) [AIBN]
/ [Monomer]
(mole rain) Temperature
(℃) time
(h) Example 1 9 One - 0.2 - - 35 0.002 65 18 Example 2 6 One - 0.25 - - 35 0.002 65 18 Example 3 9 One - One - - 35 0.002 65 18 Example 4 9 - - 0.25 - - 35 0.002 65 18 Example 5 15 One - 0.1 - - 35 0.001 70 6 Example 6 10 - One 0.1 - - 35 0.001 70 6 Example 7 10 One - - 0.1 - 35 0.001 75 6 Example 8 6 One - - - 0.25 35 0.002 65 18 Example 9 9 One - - - - 35 0.003 75 18

In Table 3, [monomer] means the volume or number of moles of MMA + MAA.

Polymer composition ratio (mole%) Properties MMA Ethylene MAA Maleic acid Tg (占 폚) Mn Mw PDI Td_50
(℃) transparency(%) Example
One 63 11 26 - 155 78600 195000 2.48 461 90 Example
2 55 13 32 - 146 61600 251000 4.08 456.5 90 Example
3 35 7 58 - 181 88400 192000 2.17 457 89 Example
4 57 2 35 - 156 59700 123000 2.05 461.9 90 Example
5 64 23 13 - 121 97000 207000 2.14 451 89 Example
6 72 17 11 - 128 81200 140000 1.72 442 91 Example
7 67 15 - 18 118 59100 91500 1.55 448 89 Example
8 65 8 - 27 123 96500 172000 1.78 400.7 90 Example
9 65 14 21 - 151 26200 45300 1.73 452 89

Examples 10-13

28 mmol of methyl methacrylate (MMA), 5.6 mmol of methacrylic acid (MAA), and 28 mmol of alumina were added to Lewis acid. And 0.056 mmol of initiator AIBN dissolved in toluene was added. Subsequently, the 1-alkene monomer shown in Table 5 was added to the reactor, and then the reactor temperature was raised to 65 ° C. and polymerization was performed for 18 hours.

After the polymerization, the polymerization solution was removed alumina through a filter, and precipitated in ethylene or hexane. The obtained polymer was dried at a temperature below Tg under reduced pressure for 24 hours. The physical property measurement results of the prepared copolymer are shown in Table 6 below.

Reaction dosage Lewis Mountain Monomer input Initiator Polymerization condition [menstruum]
/ [Quantity
sieve]
(volume
ratio) [Alu
Mina]
/ [MMA]
(mole
ratio) [Oxidation
zirconium]
/ [MMA]
(mole
ratio) [MAA]
/ [MMA]
(mole
ratio) [1-butene]
/ [MMA]
(mole
ratio) [1-hexene]
/ [MMA]
(mole
ratio) [One-
decen
e]
/ [MMA]
(mole
ratio) [AIBN]
/ Monomer]
(mole
ratio) Temperature
(℃) time
(h) Example 10 9 One - 0.1 5 - - 0.002 65 18 Example 11 6 One - 0.1 - 3 - 0.002 65 18 Example 12 9 - One 0.1 - 3 - 0.002 65 18 Example 13 9 One - 0.1 - - 3 0.002 65 18

In Table 5, [monomer] means the volume or number of moles of MMA + MAA.

Polymer composition ratio (mole%) Properties MMA 1-alkene MAA Tg (占 폚) Mn Mw PDI transparency(%) Example
10 74 9 17 138 96500 172000 1.78 90 Example
11 71 17 12 120 56700 84000 1.68 90 Example
12 74 12 14 131 64500 96600 1.79 89 Example
13 66 15 19 103 102000 165000 1.61 89

In the case of methyl methacrylate having the highest glass transition temperature among the acrylate-based vinyl monomers, the glass transition temperature is generally 110 ° C. upon homopolymerization. When ethylene is added to the acrylate-based polymer as a comonomer in order to overcome the disadvantages of film formation, a problem arises in that the heat resistance is lowered. However, the glass transition temperature must be 100 ° C or higher to withstand the heat of processing, so this problem can be solved by the addition of acrylic acid. In addition, acrylic acid contains a carboxyl group, which is a polar group, and thus increases adhesion when applied to an optical film.

Protective film production

Some compositions of the copolymers were coated to form a protective film and evaluated. The copolymers obtained through the Comparative Examples and Examples were dissolved in tetrahydrofuran (THF) at 30% by weight and then left for one day to remove gas from the solution. After the obtained polymer solution was applied to a glass plate, a film was formed at a constant rate using a film regulator maintained at an interval of 400 μm, and then dried in a 50 ° C. oven for one day. After drying, the thickness of the film was confirmed to be 80 μm.

 (Coefficient of Thermal Expansion)

Using the TMA (Mettler Toledo Co., Ltd.) TMA (manufactured by Mettler Toledo) was heated at a rate of 10 ℃ per minute dimensional change was measured, the coefficient of thermal expansion was calculated by the slope of 40 ℃ to 80 ℃ section.

(Moisture permeability measurement)

The moisture permeability was measured on 40 degreeC / 100% RH conditions with the moisture permeability measuring apparatus (PERMATRAN-W Model 398, a product made by Mocon).

(Retardation measurement)

Using Axometrics' Polarimeter (Axoscan), the planar retardation (Rin) and thickness retardation (Rth) of the prepared optical film were measured. Each retardation is defined by the following equation.

Rin = (nx-ny) x d, Rth = (nz-ny) x d

Here, nx, ny, nz means refractive index in each direction, and d means the thickness of a film.

(Photoelastic coefficient measurement)

A spring type tensioner was mounted on the Axoscan and the photoelastic coefficient was measured by measuring the retardation in the planar direction while applying a tensile force to the protective film.

The physical property measurement results of the prepared optical film are shown in Table 7 below. As a comparative example, the physical properties of the TAC film (FUJIFILM Corporation) were compared (Comparative Example 3).

Rin (nm) Rth (nm) Photoelastic coefficient (10 ^-12 m ² / N) Coefficient of thermal expansion (ppm / K) Breathable
(g / (m ² day)) Comparative Example 1 0.1 2.0 -3.2 113 76 Comparative Example 2 0.1 2.3 -3.4 101 83 Comparative Example 3 1.0 -50.0 12.7 57 720 Example 5 0.0 2.7 -0.6 71 200 Example 6 0.1 1.2 -0.6 72 211 Example 7 0.3 3.4 -0.5 87 203 Example 8 0.6 2.5 -0.6 81 207 Example 11 0.4 3.6 -0.5 74 221 Example 13 0.4 3.5 -0.6 73 217

In the case of Examples, the planar retardation (Rin) and the thickness retardation (Rth) were significantly smaller than those of Comparative Example 3, the photoelastic coefficient was small, and the moisture permeability was also low. Comparative Examples 1 and 2 showed relatively high values as compared with Examples or TAC films (Comparative Example 3) having different thermal expansion coefficients.

Polarizer manufacturers

(Polarizer manufacturing)

A polyvinyl alcohol (PVA) film (polymerization degree: 2400) having a thickness of 75 μm was immersed in an aqueous solution containing iodine (I ₂ ) and potassium iodide (KI), and then stretched five times. Subsequently, the film was introduced into a boric acid and potassium iodide aqueous bath to undergo crosslinking treatment, and dried at 80 ° C. for 5 minutes to prepare a polarizer.

(Polarizer Protective Film Surface Treatment)

In order to improve adhesion with the polarizer, the surface of the polarizer protective film was subjected to corona treatment and a silane primer was applied. As a silane-based primer, 3-aminotrimethoxy silane (3-aminotrimethoxy silane, Fluka) was dissolved in isopropyl alcohol (isopropylalcohol) and water in a solvent (95/5 weight ratio) at a concentration of 2% and stirred for 24 hours. After the corona treated protective film surface was coated using a wire bar (wire bar, # 5), and dried in an oven at 60 ℃ for 10 minutes. In the case of the TAC film of Comparative Example 3, it was immersed in 15% by weight aqueous sodium hydroxide solution for 5 minutes and dried in a 60 degree oven for 10 minutes to be surface treated.

 (Adhesive, polarizing plate production)

Polyvinyl alcohol (average degree of polymerization 2000, degree of 94%) containing acetacetyl group (5%) was dissolved in pure water to prepare an aqueous solution of 3.8%.

A zirconium amine compound (AC-7, manufactured by Daichi Kigenso Kagaku Kogyo) was dissolved in pure water to prepare an aqueous solution of 3.8%. This zirconium amine compound aqueous solution was added to the polyvinyl alcohol aqueous solution prepared above at the ratio of 20 weight part per 100 weight part of polyvinyl alcohol, and it mixed, stirring. 1 M hydrochloric acid aqueous solution was added to this mixed solution to adjust pH to 8.5 to prepare an adhesive.

Using the adhesive prepared above, after laminating the film prepared using the copolymer of Comparative Example and Example as a protective film on both sides of the polyvinyl alcohol-based polarizer, dried and bonded for 10 minutes at 80 ℃ oven To obtain a polarizing plate.

(Optical evaluation)

The single transmittance and orthogonal transmittance of the polarizing plate manufactured using the spectrophotometer (n & k spectrometer, n & k Technology Co., Ltd.) were measured.

The physical property measurement results of the prepared polarizing plate are shown in Table 8 below.

use
Protective film Group Permeability (%) Orthogonal Transparency
(%) Comparative Example 4 Comparative Example 1 42.3 0.012 Comparative Example 5 Comparative Example 2 42.0 0.013 Comparative Example 6 Comparative Example 3 42.4 0.011 Example 14 Example 5 41.8 0.014 Example 15 Example 6 42.6 0.013 Example 16 Example 7 41.9 0.015 Example 17 Example 8 41.7 0.013 Example 18 Example 11 42.3 0.016 Example 19 Example 13 42.4 0.016

The polarization characteristic after manufacturing a polarizing plate did not have a big difference with the comparative example which applied the TAC film.

The optical film according to the present invention has excellent optical transparency and optical properties, improved brittleness, less change in dimensional change and optical properties due to environmental changes in ambient temperature and humidity, and excellent durability. It can be usefully used in the application. In particular, the optical film may be used as a high quality polarizer protective film, thereby providing a high quality polarizing plate and an image display device having excellent durability such as heat resistance and moisture resistance.

Claims (17)

delete It includes a copolymer comprising 0.1 to 30 mol% of alkene monomers, 30 to 99 mol% of acrylate monomers and 0.1 to 50 mol% of unsaturated organic acid monomers having at least one double bond, The alkene monomer is an optical film comprising at least one selected from 1-alkene, 2-alkene and 3-alkene. The optical film of claim 2, wherein the acrylate-based monomer comprises a compound represented by Formula 1 below: [Formula 1]

In Formula 1, R ₁ , R ₂ and R ₃ are the same as or different from each other, and each independently represent a hydrogen atom, a monovalent hydrocarbon group having 1 to 30 carbon atoms which may include a hetero atom; R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The optical film of claim 2, wherein the unsaturated organic acid monomer is a monovalent carboxylic acid or a polyvalent carboxylic acid. The temperature according to claim 2, wherein the copolymer has a glass transition temperature of 80 to 220 ° C, a number average molecular weight of 5,000 to 400,000, a weight average molecular weight of 10,000 to 800,000, and 50% of the initial weight of the copolymer is decomposed (Td50). Is 350 to 550 ° C. The method of claim 2, wherein the copolymer is prepared by a method comprising the step of polymerizing an alkene monomer, an acrylate-based monomer and an unsaturated organic acid monomer having at least one double bond by a radical polymerization initiator in the presence of a Lewis acid or a metal oxide. Optical film. Using a copolymer containing 0.1-30 mol% of alkene monomers, 30-99 mol% of acrylate monomers and 0.1-50 mol% of unsaturated organic acid monomers having at least one double bond, The alkene monomer is a method for producing an optical film comprising at least one selected from 1-alkene, 2-alkene and 3-alkene. The polarizer protective film which consists of an optical film of any one of Claims 2-6. The polarizer protective film of claim 8, wherein at least one surface is treated to improve adhesion. The polarizer protective film of claim 9, wherein the treatment comprises at least one selected from corona treatment, plasma treatment, UV treatment, and primer layer formation. And a protective film provided on at least one surface of the polarizer and the polarizer, wherein the protective film is a polarizer protective film according to claim 8. The polarizing plate of claim 11, wherein an adhesive layer is provided between the polarizer and the protective film. The polarizing plate according to claim 11, further comprising an adhesive layer on at least one surface. A composite polarizing plate in which at least one optical layer selected from a phase difference plate, a light diffusing plate, a viewing angle expanding plate, a brightness enhancing plate, and a reflecting plate is laminated on the polarizing plate of claim 11. An image display device comprising the polarizing plate of claim 11. And a light source, a first polarizing plate, a liquid crystal cell, and a second polarizing plate in a stacked state, wherein at least one of the first polarizing plate and the second polarizing plate is a liquid crystal display device according to claim 11. 17. The liquid crystal display of claim 16, wherein the liquid crystal display device has an in-plane switching mode (IPS mode), a vertically aligned mode (VA mode), an OCB method (Optically Compensated Birefringence mode), and twisted nematic (Twisted) mode. Nematic mode (TN mode) or FFS (Fringe Field Switching mode; FFS mode) type image display device.

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