KR20090043931A - Optical films, phase difference films, and lcd comprising the same - Google Patents

Abstract

The present invention provides an optical film, a retardation film, and a method for producing the same, including a graft copolymer comprising two or more (meth) acrylic resins having different glass transition temperatures and a styrene or a derivative thereof, and the optical film or Provided is a liquid crystal display device including a retardation film.

Optical film, retardation film, glass transition temperature, (meth) acrylic resin, styrene

Description

Optical film, retardation film and liquid crystal display including the same {OPTICAL FILMS, PHASE DIFFERENCE FILMS, AND LCD COMPRISING THE SAME}

The present invention relates to an optical film, a retardation film, a method of manufacturing the same, and a liquid crystal display device of the optical film or the retardation film. Specifically, the present invention relates to an optical film, a retardation film and a manufacturing method thereof having improved mechanical properties, heat resistance, and optical properties, and a liquid crystal display device including the optical film or the retardation film.

A film made of styrene resin is a material showing optical anisotropy in which the refractive index increases in a direction orthogonal to the orientation direction when it is stretched and oriented, and a film having a positive thickness value retardation value (R _th ) by stretching it Known materials are suitable for preparing the In addition, the styrene-based resin has the advantage of excellent economic efficiency and transparency. However, there is a problem in that the heat resistance is insufficient, and the mechanical properties are inferior except in the case of using an expensive special monomer together.

It is an object of the present invention to provide an optical film and a retardation film having improved mechanical properties, heat resistance, and optical properties without using a high cost using a styrene resin. In addition, an object of the present invention is to provide a method for manufacturing the optical film and the retardation film as described above and a liquid crystal display device including the optical film or the retardation film.

In order to achieve the above object, the present invention provides an optical film including a graft copolymer comprising two or more (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof.

In addition, the present invention comprises the steps of (a) blending a resin having a styrene copolymer or a graft copolymer comprising two or more (meth) acrylic resins having different glass transition temperature, and (b) step (a) It provides a method for producing an optical film comprising the step of molding a film with a blending resin obtained in the.

The present invention also includes a graft copolymer comprising two or more kinds of (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof, and having a thickness direction retardation (R _th )> 0 and an in-plane retardation ( R _in ) ≠ 0 to provide a retardation film.

In addition, the present invention comprises the steps of (a) blending a graft copolymer comprising two or more (meth) acrylic resins having different glass transition temperatures and a resin having a styrene or a derivative thereof, (b) in the step (a) It provides a method of producing a retardation film comprising the step of forming a film with the obtained blending resin, and (c) uniaxially or biaxially stretching the film.

In addition, the present invention provides a liquid crystal display device including the optical film or the retardation film.

The optical film and the retardation film according to the present invention can provide a liquid crystal display device having excellent performance due to excellent mechanical properties, heat resistance and optical properties, as well as low cost and simple manufacturing.

Hereinafter, the present invention will be described in detail.

In the present invention, the graft copolymer including two or more kinds of (meth) acrylic resins having different glass transition temperatures is much better in mechanical properties and optical properties than conventional acrylic films. The graft copolymer is added to a resin having styrene or a derivative thereof to improve the mechanical properties of the film. In this specification, (meth) acrylic-type resin is interpreted as including both acrylic resin and methacryl-type resin.

It is preferable that two or more types of (meth) acrylic resins having different glass transition temperatures are not compatible with each other. It is preferable that at least 1 type of the said (meth) acrylic-type resin has a glass transition temperature less than 0 degreeC, and at least 1 type of the said (meth) acrylic-type resin has a glass transition temperature of 0 degreeC or more. The polymer chain constituting the main chain in the graft copolymer is preferably a (meth) acrylic resin having a glass transition temperature of less than 0 ° C.

The (meth) acrylic resin is not particularly limited, but may be prepared by polymerizing a (meth) acrylic monomer, and an additional comonomer may be further added if necessary.

As said (meth) acrylic-type monomer, it is good to have a C1-C12 alkyl group, Preferably it has a C2-C8 alkyl group, an alkylene group, or an aromatic substituent. Examples of the (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms include butyl acrylate, butyl methacrylate and 2-ethylhexyl acrylate. 2-ethylhexyl methacrylate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, t- T-butyl acrylate, t-butyl methacrylate, pentyl acrylate, pentyl methacrylate, n-octyl acrylate ), n-jade N-octyl methacrylate, isononyl acrylate, isononyl methacrylate, iso-nonyl methacrylate, n-tetradecyl acrylate, n-tetradecyl methacrylate, la A monomer selected from the group consisting of uryl acrylate, lauryl methacrylate, benzyl acrylate and benzyl methacrylate may be used, and these may be used alone or in mixture of two or more thereof. However, the present invention is not limited to these.

A (meth) acrylic acid ester monomer having a functional group may be added to prepare the (meth) acrylic resin, and specific examples thereof include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. Hydroxy, such as 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate (Meth) acrylic acid ester monomer comprising a; (Meth) acrylic acid ester monomers containing an epoxy such as 2-glycidyl (meth) acrylate; (Meth) acrylic acid ester monomers including carboxylic acids such as acrylic acid, methacrylic acid, acrylic acid dimer, itaconic acid, maleic acid, maleic anhydride, crotonic acid, β-carboxyethyl acrylate, etc. may be used, and these are 1 The species may be used alone or in a mixture of two or more thereof. However, the present invention is not limited only to these examples.

The (meth) acrylic resin may further include other monomers in addition to the aforementioned monomers. For example, a vinyl cyanide monomer, a maleimide monomer, a vinyl monomer including an aromatic ring, and the like may be further included.

The vinyl cyanide monomers include acrylonitrile and the like. The maleimide monomers include N-phenylmaleimide, N-cyclohexyl maleimide, N-methyl maleimide, N-butyl maleimide and the like. Vinyl monomers containing aromatic rings include styrene-based monomers, specifically styrene, α-methylstyrene, 3-methylstyrene, p-methylstyrene, p-ethylstyrene, one selected from the group of p-propylstyrene, 4- (p-methylphenyl) styrene, 1-vinylnaphthalene, p-chlorostyrene, m-chlorostyrene and p-nitrostyrene; or Although there are two or more compounds, the present invention is not limited thereto.

As the monomer capable of producing a (meth) acrylic resin having a glass transition temperature of 0 ° C. or higher among the monomers, all monomers having a glass transition temperature of 0 ° C. or higher of the homopolymer of each monomer may be used. In the present invention, methyl methacrylate (MMA) may be mainly used, and the content thereof preferably includes 50 mol% or more of methyl methacrylate in the (meth) acrylic resin.

In order to manufacture the (meth) acrylic resin having a glass transition temperature of 0 ° C. or more, a monomer having a glass transition temperature of less than 0 ° C. in addition to the monomer may be used as a comonomer, in which case the glass transition temperature of the copolymer is 0. The amount may be adjusted so as to be higher than or equal to ℃.

In addition, the monomer capable of producing a (meth) acrylic resin having a glass transition temperature of less than 0 ° C among the monomers may typically include butyl acrylate (BA). In addition, butyl (meth) acrylate and ethyl (meth) ) Acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) Acrylate, n-tetradecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, and the like, and these monomers are single or two or more kinds. Can be used in combination.

In particular, when the (meth) acrylic resin having a glass transition temperature of less than 0 ° C forms a main chain of the graft copolymer, a resin having a different glass transition temperature in the main chain of the copolymer, for example, a (meth) acrylic type having a glass transition temperature of 0 ° C or more In order for the resin to be graft polymerized, a method of introducing a functional group capable of reacting with radicals may be applied to the (meth) acrylic resin having a glass transition temperature of less than 0 ° C. At this time, in order to introduce a functional group capable of reacting with a radical to the (meth) acrylic resin having a glass transition temperature of less than 0 ° C, a (meth) acrylic acid ester monomer having a functional group in addition to the aforementioned (meth) acrylic monomer is added. It is preferable. Examples of the (meth) acrylic acid ester monomer having the functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxy. (Meth) acrylic acid ester monomers including hydroxy such as hexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate and 2-hydroxypropylene glycol (meth) acrylate; (Meth) acrylic acid ester monomers containing an epoxy such as 2-glycidyl (meth) acrylate; (Meth) acrylic acid ester monomers including carboxylic acids such as acrylic acid, methacrylic acid, acrylic acid dimer, itaconic acid, maleic acid, maleic anhydride, crotonic acid, β-carboxyethyl acrylate, etc. may be used, and these are 1 The species may be used alone or in a mixture of two or more thereof. However, the present invention is not limited only to these examples.

In order to prepare a (meth) acrylic resin having a glass transition temperature of less than 0 ° C., a monomer having a glass transition temperature of 0 ° C. or more in addition to the above monomer may be used as a comonomer, in which case the glass transition temperature of the copolymer is 0 ° C. The amount can be adjusted to be used below.

In the present invention, the graft copolymer comprising two or more kinds of (meth) acrylic resins having different glass transition temperatures is made of (meth) acrylic resins having a low glass transition temperature, and a (meth) having a high glass transition temperature. The acrylic resin may form a side chain or vice versa. In the present invention, the graft copolymer preferably has a structure in which a (meth) acrylic resin having a low glass transition temperature forms a main chain, and a (meth) acrylic resin having a high glass transition temperature forms a side chain. For example, the graft copolymer has a structure in which at least one (meth) acrylic resin having a glass transition temperature of less than 0 ° C forms a main chain, and at least one of the (meth) acrylic resins having a glass transition temperature of 0 ° C or more forms a side chain. Can be.

The graft copolymer preferably has a weight average molecular weight of 50,000 to 2 million, more preferably 50,000 to 500,000, a number average molecular weight of 10,000 to 1 million, more preferably 10,000 to 300,000. desirable.

In the graft copolymer, the content ratio of the (meth) acrylic resin having a glass transition temperature of less than 0 ° C. and the (meth) acrylic resin having a glass transition temperature of 0 ° C. or more is 95 to 5 to 5 to 95 in weight ratio. Preferably it is the thing of the range of 90 to 10 to 90.

In the present invention, the resin having the styrene or derivatives thereof is not particularly limited as long as it contains 30% by weight or more of styrene or derivatives thereof in the resin. Specifically, examples of usable in the present invention include polystyrene and SAN (styrene acrylonitrile copolymer).

In the present invention, the resin having the graft polymer and the styrene or derivatives thereof may be mixed in a weight ratio of 95: 5 to 5:95, preferably in a blended resin obtained after blending to exhibit desired physical properties. It is preferable to contain 20% by weight or more of styrene or a derivative thereof.

The present invention also includes a graft copolymer comprising two or more kinds of (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof and having a thickness direction retardation (R _th )> 0 and an in-plane retardation (R). _in ) ≠ 0 to provide a retardation film. It is preferable that the above retardation film is 30-200 micrometers in thickness. It is preferable that the surface direction retardation value of the said retardation film is 0-400 nm, and the thickness direction retardation value is 0-400 nm.

In the present specification, the thickness direction retardation R _th and the in-plane retardation R _in are defined as follows.

R _th = d {n _z- (n _x + n _y ) / 2}

R _in = d (n _x -n _y )

In the above formula, the refractive index in the x-axis direction is n _x , the refractive index in the y-axis direction is n _y , the thickness (d) direction refractive index is n _z , and the film thickness is d.

In the present invention, the optical film is (a) blending a resin having a graft copolymer and a styrene or a derivative thereof containing two or more (meth) acrylic resins having different glass transition temperatures, and (b) the It may be prepared by a method comprising the step of forming a film with the blending resin obtained in step (a).

In the manufacturing method of the optical film according to the present invention, the step (a) is a blending step, and blending conditions are not particularly limited, and an extrusion process generally applied may be applied.

The graft copolymer including two or more kinds of (meth) acrylic resins having different glass transition temperatures may include a1) preparing a first (meth) acrylic resin containing a first (meth) acrylic monomer, a2) 1) introducing a functional group capable of reacting with radicals into the main chain of (meth) acrylic resin, and a3) radically polymerizing a second (meth) acrylic monomer to the modified first (meth) acrylic resin obtained in step a2). The second (meth) acrylic resin having a glass transition temperature different from the first (meth) acrylic resin in the first (meth) acrylic resin may be prepared by a graft copolymerized graft copolymer. .

Step a1) is a step of preparing the first (meth) acrylic resin, in order to introduce a functional group capable of reacting with radicals in the main chain of the first (meth) acrylic resin in step a2), It is preferable to add a (meth) acrylic acid ester monomer having various functional groups to the first (meth) acrylic monomer to prepare a first (meth) acrylic resin. Preferred examples of the (meth) acrylic acid ester monomer having the functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6- (Meth) acrylic acid ester monomers including hydroxy such as hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate and 2-hydroxypropylene glycol (meth) acrylate; (Meth) acrylic acid ester monomers containing an epoxy such as 2-glycidyl (meth) acrylate; (Meth) acrylic acid ester monomers including carboxylic acids such as acrylic acid, methacrylic acid, acrylic acid dimer, itaconic acid, maleic acid, maleic anhydride, crotonic acid, β-carboxyethyl acrylate, and the like, but are limited to these examples only. It doesn't happen. The amount of the (meth) acrylic acid ester monomer having a functional group added at the time of preparing the first (meth) acrylic resin is preferably 0.1-50 mol%, more preferably 0.1-10 mol%.

Subsequently, step a2) is a step of introducing a functional group capable of reacting with radicals in the main chain of the first (meth) acrylic resin prepared in step a1). A -SH group can be introduced as a functional group that can react with the radical.

Specifically, in one embodiment of step a2), as a method of introducing a -SH group into the first (meth) acrylic resin, a hydroxyl group or a carboxyl group in the resin, a mercapto acid (Mmercaptoacetic acid), mercapto An alcohol, or mercaptoester, can be used which comprises esterifying, in the presence or absence of a catalyst. In this step, the amount of -SH group that can be introduced into the first (meth) acrylic resin may be introduced in various amounts depending on the reaction conditions. For example, the degree of esterification may be adjusted to 0.1-100 mol%, more preferably 50-100 mol% with respect to the functional groups of the entire hydroxyl group or carboxyl group, thereby introducing various concentrations of the -SH group.

As the catalyst that can be used in the step a2), an acid catalyst may be typically used. Examples of the acid catalyst usable include inorganic acids of sulfuric acid or hydrochloric acid, organic acids such as methanesulfonic acid and paratoluenesulphonic acid, and Lewis acids such as boronic acid. The acid catalyst used in step b) is not particularly limited in amount.

The first (meth) acrylic resin in which the mercapto group is introduced may act as a chain transfer agent in a subsequent radical polymerization process, and may serve to provide an active site for graft polymerization (Journal of Polymer Science 1959, p411-423).

In step a3), the second (meth) acrylic monomer is added to the modified first (meth) acrylic resin obtained in step a2) and subjected to radical polymerization, so that the first (meth) is added to the first (meth) acrylic resin. The graft copolymer to which the 2nd (meth) acrylic-type resin from which acrylic resin differs from glass transition temperature is graft-polymerized can be manufactured.

In the step a3), the amount of the modified first (meth) acrylic resin obtained in the step a2) may be controlled to vary from 1 to 50 parts by weight based on 100 parts by weight of the second (meth) acrylic monomer. . The second (meth) acrylic monomer means a (meth) acrylic monomer capable of providing a second (meth) acrylic resin having a different glass transition temperature from the first (meth) acrylic resin, and examples thereof are as described above. . In the method of manufacturing an optical film according to the present invention, the first (meth) acrylic resin is a (meth) acrylic resin having a glass transition temperature of less than 0 ° C, and the second (meth) acrylic resin is a (meth) having 0 ° C or more. It is preferable that it is acrylic resin.

Also in the step a3), a (meth) acrylic acid ester monomer having a functional group may be added in addition to the second (meth) acrylic monomer. Preferred examples of the (meth) acrylic acid ester monomer having a functional group are the same as those which can be used in the step (a).

As the radical polymerization in step a3), a method known in the art may be used, and the scope of the present invention is not limited by the polymerization method. For example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization are possible, but are not limited to these examples.

As the polymerization initiator, for example, an initiator activated by heat or an initiator activated by light may be used. Specifically, thermally activated initiators such as azo compounds such as azobis (isobutyronitrile), peroxide compounds such as benzoyl peroxide, benzophenone, benzoin ethyl ether and 2,2'-dimethoxy-2-phenyl Initiators activated by light such as acetophenone may be used, but are not limited to these examples. The amount of the polymerization initiator is not particularly limited, but in order to obtain an appropriate molecular weight of the resulting graft copolymer, it is generally used in a weight ratio of 0.01 to 5, more preferably 0.1 to 1 relative to the second (meth) acrylic monomer. Can be.

In addition, a chain transfer agent may be added to appropriately control the molecular weight. Suitable chain transfer agents are suitable such as methane-based or alpha methyl styrene dimers such as dodecyl methane, lauryl methane and the like.

Although the said polymerization reaction temperature has a some fluctuation | variation for balance with the other polymerization conditions, it can be 30-130 degreeC normally, Preferably it is 40-120 degreeC, More preferably, it can be 40-90 degreeC. In addition, although reaction time changes with reaction conditions, such as reaction temperature, a kind, or concentration of monomer, it can be made into 2 to 24 hours normally. Fillers, reinforcing agents, stabilizers, colorants and antioxidants may be further added as needed during the radical polymerization.

Examples of the solvent used in the polymerization include ethers such as tetrahydrofuran, diethyl ether and dioxane, hydrocarbons such as n-hexane, petroleum ether, toluene, benzene and xylene, methanol, ethanol and isopropanol, and the like. Ketones such as alcohols, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetonitrile, N, N-dimethyl formamide, dimethyl sulfoxide and the like. Each of these solvents may be used alone, or two or more thereof may be used in combination. It is preferable to perform the said polymerization reaction in inert gas atmosphere. As an inert gas, nitrogen gas, argon gas, etc. are mentioned, for example.

In the above method, the molecular weight of the graft copolymer and the graphene are controlled by controlling the amounts of precursors, polymerization initiators, and second (meth) acrylic monomers to introduce functional groups capable of reacting with radicals in the main chain of the first (meth) acrylic resin. The degree of heat and thermal stability can be controlled.

In the method of manufacturing an optical film according to the present invention, the step (b) may include a resin in which a graft copolymer including two or more (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof are blended. As a step of forming into a film, the above-mentioned blending resin may be prepared into an optical film by using a method such as extrusion molding, inflation molding, or solution softening, which is a method of preparing a general film.

When the film is produced by the extrusion method, a film of any thickness can be produced by passing a thin gap of the die called a T-die. At this time, in order to prevent appearance defects due to gas foaming, it is preferable to heat and dry the blending resin at a temperature in the range of 80 to 130 ° C in advance. Extrusion is preferably performed at a temperature sufficiently higher than the glass transition temperature at which the blending resin melt flows to suppress the orientation of the molecular chain. For cooling and solidifying the film in the molten state after passing through the die, a low temperature metal roller or a steel belt may be used.

When manufacturing a film by the solution softening method, the solvent which each resin can be soluble is selected, and a some solvent can be used as needed. Specific examples of the solvent that may be used in the solution softening method include methylene chloride, chloroform, chlorobenzene, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, and the like. no. In particular, a good solvent and a poor solvent for each resin may be combined to control the volatilization rate. During drying in the solution softening method, it is preferable that bubbles or internal voids are not formed in the film by setting heating conditions, and the concentration of the residual solvent is 0.1 wt% or less.

The optical film produced by the above method preferably has a thickness of 30 to 200 ㎛.

The retardation film according to the present invention may be manufactured by further performing the step of uniaxially or biaxially stretching the film after molding the film as in the method of manufacturing the optical film. In the present invention, by stretching the film containing the components as described above uniaxially or biaxially stretching the two axes differently to provide a retardation film having a thickness direction retardation (R _th )> 0, in-plane retardation (R _in ) ≠ 0 Can be. The retardation film as described above may provide the optical characteristics required in the liquid crystal display device, particularly the IPS type liquid crystal display device.

The stretching may be performed at a temperature of Tg-20 ° C. to Tg + 30 ° C. when the glass transition temperature of the blending resin is Tg. The glass transition temperature indicates a region from the temperature at which the storage modulus of the blending resin begins to decrease, and thus the loss modulus becomes larger than the storage modulus, at which the orientation of the polymer chain is relaxed and disappeared. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

The stretching speed can be appropriately adjusted according to the retardation to be obtained and the thickness of the film. Generally, extending | stretching is possible by making the extending | stretching speed calculated by the following formula into 50% / min-500% / min.

[expression]

Drawing speed (% / min) = {(width direction dimension after extending | stretching / width direction dimension before extending | stretching) -1} x100 (%) / time (min) required for extending | stretching.

In the manufacturing method of the retardation film according to the present invention, the draw ratio can be appropriately adjusted according to the retardation and the thickness of the film to be obtained, it is possible to stretch in the range of 10% to 100%.

In addition, the present invention provides a liquid crystal display device including the optical film or the retardation film. The liquid crystal display device includes a liquid crystal cell and a first polarizing plate and a second polarizing plate provided on both surfaces of the liquid crystal cell, and the optical film or the retardation film is provided as at least one protective film among the polarizing plates, or the polarizing plate It may be provided between at least one of them and the liquid crystal cell. One or two or more optical films or retardation films may be provided in the liquid crystal display. It is preferable that the liquid crystal display according to the present invention is in the IPS mode.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

Example 1

1. Preparation of Graft Copolymer

1) Preparation of First Acrylic Resin [A]

97.5 g of butyl acrylate, 2.5 g of 2-hydroxybutyl acrylate, 43 g of toluene, 0.2 g of initiator AIBN, and 0.12 g of 1-octylmerethane were added dropwise to an 80 ° C., 250 ml reactor over 1 hour, and further 3 hours The polymer was prepared by polymerization at 85 ° C. Unreacted monomer in the solution was measured by gas chromatography to confirm that the conversion was 98%. (Molecular weight: Mw = 95k, Mn = 39k)

2) Introduction of functional groups capable of reacting with radicals in the main chain of the first acrylic resin

Toluene 260g was further added to 140 g of the first acrylic resin [A] solution prepared in 1), 1 g of p-toluene sulfonic acid and 3.5 g of thioglycolic acid were added to reflux. The reaction was carried out for 4 hours. After the reaction was completed, the mixture was added dropwise into methanol to precipitate. Then, toluene was added to the precipitate, followed by heating to remove azeotropic methanol in the polymer. Through this process, the first acrylic resin [A '] polymer solution including SH was obtained.

3) Graft Polymerization

32 g of the modified first acrylic resin [A '] solution obtained in step 2) (TSC 40%), 79.17 g of MMA, 4.17 g of MA, and 0.26 g of AIBN were placed in a 250 mL polymerizer and maintained at 70 ° C. in a nitrogen atmosphere for 12 hours. The reaction proceeded. After the reaction was terminated, the above polymerization solution was precipitated in methanol to obtain graft copolymer 1.

2. Blending SAN Resin with Graft Copolymer

100 g of the graft copolymer 1 prepared in Example 1 and 300 g of SAN (LG Chemical (trade name: SAN80HF)) were uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins were mixed.

3. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 132㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 1 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 112 100 50 67 300 213 112 50 50 99 272 272 112 10 50 131 122 130

Example 2

1. Preparation of Graft Copolymer

1) Preparation of First Acrylic Resin [B]

70 g of butyl acrylate, 3 g of 2-hydroxybutyl acrylate, 27 g of styrene, 30 g of toluene and 0.3 g of initiator AIBN, 0.1 g of 1-octylmerethane were added dropwise to a 70 ° C., 250 ml reactor over 4 hours, and further 3 The polymer was prepared by polymerizing the time at 95 ° C. Unreacted monomer in the solution was measured by gas chromatography to confirm that the conversion was 98%. (Molecular weight: Mw = 170k, Mn = 62k)

2) Introduction of functional groups capable of reacting with radicals in the main chain of the first acrylic resin

200 g of toluene was further added to 200 g of the first acrylic resin [B] solution prepared in 1), and 1 g of p-toluene sulfonic acid and 6 g of thioglycolic acid were added thereto under reflux. The reaction was carried out for 4 hours. After the reaction was completed, the mixture was added dropwise into methanol to precipitate. Then, toluene was added to the precipitate, followed by heating to remove azeotropic methanol in the polymer. Through this process, the first acrylic resin [B '] polymer solution including SH was obtained.

3) Graft Polymerization

32 g of the modified first acrylic resin [B '] solution obtained in step 2) (TSC 40%), MMA 79.17 g, MA 4.17 g, and 0.26 g of AIBN were placed in a 250 mL polymerizer and maintained at 70 ° C. in a nitrogen atmosphere for 12 hours. The reaction proceeded. After the reaction was terminated, the above polymerization solution was precipitated in hexane to obtain graft copolymer 2.

2. Blending SAN Resin with Graft Copolymer

100 g of the graft copolymer 2 prepared in Example 2 and 300 g of SAN (LG Chemical (trade name: SAN80HF)) were uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins were mixed.

3. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 120㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 2 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 112 100 50 64 310 330 112 50 50 95 262 290 112 10 50 118 115 142

Example 3

1. Blending SAN Resin with Graft Copolymer

210 g of the graft copolymer 2 prepared in Example 2 and 90 g of SAN were uniformly mixed and extruded using a single extruder to prepare pellets in which two resins were mixed.

2. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 120㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 3 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 112 100 50 64 392 187 112 50 50 95 197 89 112 10 50 118 37 18

Example 4

1. Blending SAN Resin with Graft Copolymer

210 g of the graft copolymer 1 prepared in Example 1 and 90 g of SAN (LG Chemical (trade name: SAN80HF)) were uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins were mixed.

2. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 100㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 4 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 112 100 50 78 263 122 112 50 50 85 170 83 112 10 50 95 69 35

Example 5

1. Preparation of Graft Copolymer

1) Preparation of First Acrylic Resin [C]

77 g of butyl acrylate, 3 g of 2-hydroxybutyl acrylate, 20 g of styrene, 30 g of toluene, 0.3 g of initiator AIBN, and 0.08 g of 1-octylmerethane were added dropwise to a 70 ml, 250 ml reactor over 4 hours, further 3 The polymer was prepared by polymerizing the time at 95 ° C. Unreacted monomer in the solution was measured by gas chromatography to confirm that the conversion was 98%. (Molecular weight: Mw = 190k, Mn = 90k)

2) Introduction of functional groups capable of reacting with radicals in the main chain of the first acrylic resin

Toluene 400g was further added to 200 g of the first acrylic resin [C] solution prepared in 1), and 1 g of p-toluene sulfonic acid and 6 g of thioglycolic acid were added thereto under reflux. The reaction was carried out for 4 hours. After the reaction was completed, the mixture was added dropwise into methanol to precipitate. Then, toluene was added to the precipitate, followed by heating to remove azeotropic methanol in the polymer. Through this process, the first acrylic resin [C ′] polymer solution including SH was obtained.

3) Graft Polymerization

40 g (TSC 33%), MMA 79.17 g, MA 4.17 g, and AIBN 0.26 g of the modified first acrylic resin [C ′] solution obtained in step 2) were added to a 250 mL polymerizer and maintained at 70 ° C. in a nitrogen atmosphere for 12 hours. The reaction proceeded. After the reaction was terminated, the above polymerization solution was precipitated in hexane to obtain graft copolymer 3.

2. Blending SAN Resin with Graft Copolymer

100 g of the graft copolymer 3 prepared in Example 5 and 300 g of SAN (LG Chemical (trade name: SAN80HF)) were uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins were mixed.

3. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 110㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 5 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 112 100 50 68 300 310 112 50 50 90 250 280 112 10 50 110 110 138

Example 6

1. Blending SAN Resin with Graft Copolymer

200 g of the graft copolymer 3 prepared in Example 5 and 100 g of SAN (LG Chemical (trade name: SAN80HF)) are uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins are mixed.

2. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 120㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 6 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 112 100 50 68 410 200 112 50 50 97 200 95 112 10 50 115 69 35

Example 7

1. Preparation of Graft Copolymer

1) Preparation of First Acrylic Resin [C]

77 g of butyl acrylate, 3 g of 2-hydroxybutyl acrylate, 20 g of styrene, 30 g of toluene, 0.3 g of initiator AIBN, and 0.08 g of 1-octylmerethane were added dropwise to a 70 ml, 250 ml reactor over 4 hours, further 3 The polymer was prepared by polymerizing the time at 95 ° C. Unreacted monomer in the solution was measured by gas chromatography to confirm that the conversion was 98%. (Molecular weight: Mw = 190k, Mn = 90k)

2) Introduction of functional groups capable of reacting with radicals in the main chain of the first acrylic resin

Toluene 400g was further added to 200 g of the first acrylic resin [C] solution prepared in 1), 1 g of p-toluene sulfonic acid and 6 g of thioglycolic acid were added thereto under reflux. The reaction was carried out for 4 hours. After the reaction was completed, the mixture was added dropwise into methanol to precipitate. Then, toluene was added to the precipitate, followed by heating to remove azeotropic methanol in the polymer. Through this process, the first acrylic resin [C ′] polymer solution including SH was obtained.

3) Graft Polymerization

40 g (TSC 33%) of the modified first acrylic resin [C ′] solution, MMA 75.17 g, MA 4.17 g, CHMI 4 g, and AIBN 0.26 g obtained in step 2) were added to a 250 mL polymerizer and maintained at 70 ° C. in a nitrogen atmosphere. The reaction proceeded for 12 hours. After the reaction was terminated, the above polymerization solution was precipitated in hexane to obtain graft copolymer 4.

2. Blending SAN Resin with Graft Copolymer

100 g of the graft copolymer 4 prepared in Example 7 and 300 g of SAN (LG Chemical (trade name: SAN80HF)) were uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins were mixed.

3. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 110㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. Stretching conditions and retardation values of the prepared films are shown in Table 7 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 117 100 50 67 295 310 117 50 50 91 250 283 117 10 50 105 112 141

Example 8

1. Blending SAN Resin with Graft Copolymer

200 g of the graft copolymer 4 prepared in Example 7 and 100 g of SAN (LG Chemical (trade name: SAN80HF)) were uniformly mixed and extruded using a single extruder to prepare pellets in which the two resins were mixed.

2. Film manufacturing and stretching

The blended pellet 10g using a hot press to prepare a film having a thickness of 120㎛ at 240 ℃, 150bar conditions. This film was stretched under the following conditions to prepare a retardation film. The stretching conditions and the retardation values of the prepared films are shown in Table 8 below.

Drawing temperature (℃) Elongation (%) Drawing speed (mm / min) Film thickness (㎛) Planar phase difference (nm) Thickness Directional Phase Difference (nm) 117 100 50 68 420 210 117 50 50 97 205 97 117 10 50 118 67 35

Claims (29)

An optical film comprising a graft copolymer comprising two or more kinds of (meth) acrylic resins having different glass transition temperatures, and a resin having styrene or a derivative thereof. The optical film of claim 1, wherein the (meth) acrylic resin includes a (meth) acrylic monomer having or not having at least one substituent selected from an alkyl group having 1 to 12 carbon atoms, alkylene and aromatics. The method according to claim 2, wherein the (meth) acrylic resin is a (meth) acrylic acid ester monomer containing hydroxy; (Meth) acrylic acid ester monomers including epoxy; And a (meth) acrylic acid ester monomer having at least one functional group selected from the group consisting of a (meth) acrylic acid ester monomer including a carboxylic acid. The optical film of claim 2, wherein the (meth) acrylic resin further includes one or more monomers selected from the group consisting of vinyl cyanide monomers, maleimide monomers, and vinyl monomers including aromatic rings. 2. The glass transition temperature of claim 1, wherein at least one of two or more kinds of (meth) acrylic resins having different glass transition temperatures has a glass transition temperature of less than 0 ° C., and at least one of the (meth) acrylic resins has a glass transition temperature of 0 ° C. 3. Above, the (meth) acrylic resin having a glass transition temperature of less than 0 ° C. and the (meth) acrylic resin having a glass transition temperature of 0 ° C. or more are contained in a weight ratio of 95: 5 to 5:95. The optical film of claim 5, wherein the (meth) acrylic resin having a glass transition temperature of 0 ° C. or more comprises 50 mol% or more of methyl methacrylate (MMA). The (meth) acrylic resin having a glass transition temperature of less than 0 ° C is butyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, iso Propyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate, n-tetradecyl (meth) acrylate, 2-ethylhexyl (meth) acrylic An optical film comprising a (meth) acrylic monomer selected from the group consisting of latex, lauryl (meth) acrylate and benzyl (meth) acrylate. The (meth) acrylic resin having a glass transition temperature of less than 0 ° C. according to claim 5, comprising: a (meth) acrylic acid ester monomer containing hydroxy; (Meth) acrylic acid ester monomers including epoxy; And (meth) acrylic acid ester monomer having at least one functional group selected from the group consisting of (meth) acrylic acid ester monomers including carboxylic acids in an amount of 0.1 to 50 mol% in the (meth) acrylic resin. Optical film. The graft copolymer of claim 5, wherein at least one (meth) acrylic resin having a glass transition temperature of less than 0 ° C forms a main chain, and at least one of the (meth) acrylic resins having a glass transition temperature of 0 ° C or more forms a side chain. Optical film which is a structure. The optical film of claim 1, wherein the graft copolymer has a weight average molecular weight of 50,000 to 2 million, and a number average molecular weight of 10,000 to 1 million. The optical film of claim 1, wherein the resin having styrene or a derivative thereof contains 30 wt% or more of styrene or a derivative thereof. The optical film of claim 1, wherein a weight ratio of the graft copolymer and the resin having the styrene or a derivative thereof is 5:95 to 95: 5. The optical film of claim 1, wherein the optical film comprises 20 wt% to 95 wt% of styrene or a derivative thereof. a) blending a graft copolymer comprising two or more (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof, and (b) having the blending resin obtained in step (a) above. Claim 1 to 13, wherein the optical film manufacturing method of any one comprising the step of forming a film. A graft copolymer comprising two or more kinds of (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof, and having a thickness direction retardation (R _th )> 0 and an in-plane retardation (R _in ) ≠ 0 Phosphorus retardation film. The retardation film according to claim 15, wherein the (meth) acrylic resin includes a (meth) acrylic monomer having or without at least one substituent selected from an alkyl group having 1 to 12 carbon atoms, alkylene and aromatics. The method according to claim 16, wherein the (meth) acrylic resin is a (meth) acrylic acid ester monomer containing hydroxy; (Meth) acrylic acid ester monomers including epoxy; And a (meth) acrylic acid ester monomer having at least one functional group selected from the group consisting of a (meth) acrylic acid ester monomer including a carboxylic acid. The retardation film according to claim 16, wherein the (meth) acrylic resin further comprises at least one monomer selected from the group consisting of vinyl cyanide monomers, maleimide monomers and vinyl monomers including aromatic rings. The glass transition temperature of at least one of the two or more kinds of (meth) acrylic resins having different glass transition temperatures is less than 0 ° C, and at least one of the (meth) acrylic resins has a glass transition temperature of 0 ° C. Above, wherein the (meth) acrylic resin having a glass transition temperature of less than 0 ° C. and the (meth) acrylic resin having a glass transition temperature of 0 ° C. or more are contained in a weight ratio of 95: 5 to 5:95. The retardation film of claim 19, wherein the (meth) acrylic resin having a glass transition temperature of 0 ° C. or more includes 50 mol% or more of methyl methacrylate (MMA). The method according to claim 19, wherein the (meth) acrylic resin having a glass transition temperature of less than 0 ℃ butyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, iso Propyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate, n-tetradecyl (meth) acrylate, 2-ethylhexyl (meth) acrylic A retardation film comprising a (meth) acrylic monomer selected from the group consisting of latex, lauryl (meth) acrylate and benzyl (meth) acrylate. The method according to claim 19, wherein the glass transition temperature (meth) acrylic resin having a temperature of less than 0 ℃ (meth) acrylic acid ester monomer containing hydroxy; (Meth) acrylic acid ester monomers including epoxy; And (meth) acrylic acid ester monomer having one or more functional groups selected from the group consisting of (meth) acrylic acid ester monomers including carboxylic acids in 0.1 to 50 mol% in the (meth) acrylic resin. Phosphorus retardation film. 20. The method of claim 19, wherein the graft copolymer has a glass transition temperature of at least one (meth) acrylic resin of less than 0 ℃ form a main chain, the glass transition temperature of at least one (meth) acrylic resin of 0 ℃ or more forms a side chain. Retardation film which is a structure. The retardation film of claim 15, wherein the graft copolymer has a weight average molecular weight of 50,000 to 2 million, and a number average molecular weight of 10,000 to 1 million. The retardation film of claim 15, wherein the resin having styrene or derivatives thereof comprises 30% by weight or more of styrene or derivatives thereof. The retardation film of claim 15, wherein a weight ratio of the graft copolymer and the resin having the styrene or a derivative thereof is 5:95 to 95: 5. The retardation film of claim 15, wherein the retardation film comprises 20 wt% to 95 wt% of styrene or a derivative thereof. a) blending a graft copolymer comprising two or more (meth) acrylic resins having different glass transition temperatures and a resin having styrene or a derivative thereof, (b) a film having the blending resin obtained in step (a) Forming, and (c) the method of producing a phase difference film of any one of claims 15 to 27 comprising the step of uniaxially or biaxially stretching the film. A liquid crystal display device comprising the optical film of any one of claims 1 to 13 or the phase difference film of any one of claims 15 to 27.