KR20100000697A - Retardation film, fabrication method thereof, and liquid crystal display comprising the same - Google Patents

Abstract

PURPOSE: A retardation film is provided to ensure excellent optical characteristics including in-plane phase difference, thickness directional phase difference, and optical clarity, and good heat resistance, processability, and productivity. CONSTITUTION: A retardation film comprises an acryl-norbornene copolymer consisting of an acrylic monomer containing a benzene ring and a norbornene monomer. The acrylic monomer containing a benzene ring has a structure represented by chemical formula 1. In chemical formula 1, R1, R2 and R3 are independently hydrogen, C1-30 monovalent hydrocarbon group containing or not containing a hetero atom, epoxy group, or phenyl group; at least one of R1, R2 and R3 is a phenyl group; and R4 is hydrogen or C1-6 alkyl group.

Description

Retardation film, a manufacturing method thereof, and a liquid crystal display including the same {RETARDATION FILM, FABRICATION METHOD THEREOF, AND LIQUID CRYSTAL DISPLAY COMPRISING THE SAME}

The present invention relates to a retardation film, a method of manufacturing the same, and a liquid crystal display including the same.

Recently, display technologies using various methods such as plasma display panel (PDP) and liquid crystal display (LCD), which replace conventional CRTs, have been proposed and marketed based on the development of optical technology. Polymer materials for such displays are becoming more sophisticated. For example, in the case of liquid crystal displays, as thin film thickness, light weight, and large screen area are promoted, wide viewing angles, high contrast, suppression of image color tone change according to viewing angle, and uniformity of screen display have become particularly important problems.

Accordingly, various polymer films are used for polarizing films, retardation films, plastic substrates, light guide plates, and the like, and liquid crystals include twisted nematic (TN), super twisted nematic (STN), and VA (vertical alignment). ), Various types of liquid crystal display devices using IPS (in-plane switching) liquid crystal cells, etc. have been developed. All of these liquid crystal cells have an inherent liquid crystal array, have inherent optical anisotropy, and in order to compensate for this optical anisotropy, films have been proposed in which various kinds of polymers are drawn to give a retardation function.

For example, Japanese Unexamined Patent Application Publication No. 9-304619 is mentioned as an example using polycarbonate (PC) resin. However, when extending | stretching polycarbonate resin in this way, although sufficient retardation function can be provided as a retardation film, there exists a problem that it is difficult to manufacture the film which has a large retardation change rate according to extension degree, and has a more uniform stable phase difference.

As a method of solving such a problem, a method using a cyclic polyolefin resin (cyclic olefin polymer, COP) has been proposed (Japanese Patent Laid-Open No. 2001-350017, Japanese Patent Laid-Open No. 2004-51928). However, the cyclic polyolefin resin has a problem in that adhesiveness with other substrates and the like is inferior, and there is a problem in that a sufficient retardation is not generated as a retardation film because the retardation change rate is small due to extension.

Therefore, Japanese Patent No. 2886893 uses methyl methacrylate (MMA) as a main component, and extends styrene and maleic anhydride copolymer resin to use as retardation plates. As disclosed in this patent document, when an acrylic resin is used, a phase difference plate can be produced which is transparent and has no haze, and suitable for development of phase difference through stretching.

However, when the retardation film is produced as suggested in the above patent document, due to the properties of the acrylic resin composition, the film is brittle, problems arise in roll during film processing, There existed a problem that joining became difficult, the process process became difficult, and it was difficult to use with retardation film.

In addition, since the film is expensive and has a complicated manufacturing process, an acrylic copolymer having excellent heat resistance and transparency is being studied to solve this problem.

An object of the present invention is to provide a retardation film having excellent optical characteristics such as in-plane retardation, thickness retardation, optical transparency, and excellent heat resistance, processability, productivity, and the like, and a liquid crystal display device including the same.

Accordingly, the present invention provides a retardation film comprising an acrylic monomer containing a benzene ring and an acryl-norbornene copolymer comprising a norbornene monomer.

In addition, the present invention

1) preparing an unstretched film using an acryl-norbornene-based copolymer comprising an acrylic monomer and a norbornene-based monomer comprising a benzene ring, and

2) stretching the non-stretched film of step 1)

It provides a method for producing a retardation film comprising a.

Moreover, this invention provides the liquid crystal display device containing the said retardation film.

The retardation film according to the present invention is excellent in optical characteristics such as in-plane retardation, thickness direction retardation, optical transparency, and excellent in heat resistance, processability, productivity, and the like.

Hereinafter, the present invention will be described in detail.

The retardation film according to the present invention includes an acryl-norbornene-based copolymer comprising an acryl-based monomer including a benzene ring and a norbornene-based monomer.

In the retardation film according to the present invention, the acrylic monomer including the benzene ring may be represented by the following Formula 1, but is not limited thereto.

In Chemical Formula 1,

R ₁ , R _2, and R ₃ each independently represent a hydrogen, monovalent hydrocarbon group having 1 to 30 carbon atoms, an epoxy group, or a phenyl group containing or without a hetero atom, and R ₁ , R _2, and R ₃ At least one of is a phenyl group;

R ₄ represents hydrogen or an alkyl group having 1 to 6 carbon atoms.

More preferred compounds as the acryl-based monomer including the benzene ring include benzyl methacrylate, 2-phenylethyl methacrylate, 2-phenylpropyl methacrylate, 3-phenylpropyl methacrylate, 4-t-butylphenyl methacrylate, 4-methoxyphenyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxy 2- phenoxyethyl methacylate, and the like, but is not limited thereto.

In the retardation film according to the present invention, the content of the acrylic monomer including the benzene ring in the acryl-norbornene-based copolymer is preferably 20 to 90% by weight, more preferably 20 to 60% by weight. When the content of the acrylic monomer including the benzene ring is less than 20% by weight, the high transparency of the acrylic polymer may not be sufficiently expressed, may not sufficiently express the desired retardation value, and exceeds 90% by weight. In this case, there may be a problem of mechanical strength and heat resistance.

In the retardation film according to the present invention, the norbornene-based monomer is preferably a norbornene-based monomer represented by the following formula (2), but is not limited thereto.

In Chemical Formula 2,

m is an integer from 0 to 4;

R ₁ , R ₂ , R ₃ and R ₄ are the same as or different from each other, and each independently hydrogen; halogen; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkyl having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenyl of 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynyl having 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Cycloalkyl having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy Aryl having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or a polar group comprising at least one of oxygen, nitrogen, phosphorus, sulfur, silicon, and boron;

When R ₁ , R ₂ , R ₃ and R ₄ are not hydrogen, halogen, or a polar functional group, R ₁ And saturation of R _2, or R ₃ and R ₄ is connected is formed in the alkylidene group having 1 to 10 carbon atoms, or R ₁ or R ₂ is connected with any one of R ₃ and R ₄ each having 4 to 12 carbon atoms, Or an unsaturated aliphatic ring or an aromatic ring having 6 to 24 carbon atoms.

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Specifically, in Chemical Formula 2, the polar functional group is -R ₅ OR ₆ , -OR ₆ , -OC (O) OR ₆ , -R ₅ OC (O) OR ₆ , -C (O) OR ₆ , -R ₅ C (O) OR _6, -C (O) R ₆ , -R ₅ C (O) R ₆ , -OC (O) R ₆ , -R ₅ OC (O) R ₆ ,-(R ₅ O) _n -OR ₆ ,-(OR ₅ ) _n -OR ₆ , -C (O) -OC (O) R ₆ , -R ₅ C (O) -OC (O) R ₆ , -SR ₆ , -R ₅ SR ₆ , -SSR ₆ , -R ₅ SSR ₆ , -S (= O) R ₆ , -R ₅ S (= O) R ₆ , -R ₅ C (= S) R _6- , -R ₅ C (= S) SR ₆ , -R ₅ SO ₃ R ₆ , -SO ₃ R ₆ , -R ₅ N = C = S, -N = C = S, -NCO, -R ₅ -NCO, -CN, -R ₅ CN, -NNC (= S) R ₆ , -R ₅ NNC (= S) R ₆ , -NO ₂ , -R ₅ NO ₂ ,

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Is;

In the polar functional group,

R ₅ is the same as or different from each other, and each independently halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, Linear or branched alkylene having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from carbonyloxy, halocarbonyloxy, aryloxy, haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenylene having 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynylene having 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Cycloalkylene having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Arylene having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Alkoxylene having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy , Carbonyloxyylene having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy,

R ₆ , R ₇ and R ₈ are the same as or different from each other, and each independently hydrogen; halogen; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkyl having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenyl of 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynyl having 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Cycloalkyl having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Aryl having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Alkoxy having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy , Carbonyloxy of 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy,

n is each independently an integer of 1 to 10.

More specifically, as norbornene-based monomers, 2-norbornene (2-norbornene), 5-butyl-2-norbornene (5-butyl-2-norbornene), 5-methyl-2-norbornene (5-methyl -2-norbornene), 5-hexyl-2-norbornene, 5-decyl-2-norbornene, 5-phenyl-2-norbornene (5-phenyl-2-norbornene), 5-naphthyl-2-norbornene, 5-ethylidene-2-norbornene, vinyl novo Vinyl norbornene, 5-hydroxy-2-norbornene, 5-hydroxymethyl-2-norbornene, 5-methoxy- 5-methoxy-2-norbornene, 5-t-butoxycarbonyl-2-norbornene, 5-methoxy-carbonyl-2-norbornene 5-methoxy-carbornyl-2-norbornene, 5-carboxy-2-norbornene, 5-carboxymethyl-2-norbornene, 5-carborxymethyl-2-norbornene, 5-triethoxysilyl norbornene, 5-trichlorosilyl norbornene ornene), 5-trimethylsilyl norbornene, 5-chlorodimethylsilyl norbornene, 5-trimethoxysilyl norbornene, 5-methyldimethoxy Silyl norbornene (5-methyldimethoxysilyl norbornene), 5-dimethylmethoxy norbornene (5-dimethylmethoxy norbornene) and the like, but is not limited thereto.

In the present invention, the norbornene-based monomer is at least one norbornene (bicyclo [2,2,1] hept-2-ene), such as the formula (3) It means the monomer containing a unit.

In the retardation film according to the present invention, the content of the norbornene monomer in the acrylic-norbornene-based copolymer is preferably 10 to 80% by weight, more preferably 10 to 50% by weight.

When the content of the norbornene-based monomer is less than 10% by weight, norbornene-based monomer can not fully exhibit the role of contributing to the phase difference value expression, if it exceeds 80% by weight not only can not sufficiently express the mechanical strength and also Novo The reaction may not proceed smoothly due to the problem of low reactivity between the monomer and acrylic monomers.

In the retardation film according to the present invention, the acryl-norbornene-based copolymer may further include one or more comonomers such as maleic anhydride-based comonomer and acryl-based comonomer within a range that does not impair the object of the present invention. .

The maleic anhydride-based comonomer may be represented by the following Chemical Formula 4, but is not limited thereto.

In Formula 4, R ₁ And R ₂ each independently represent hydrogen or an alkyl group having 1 to 6 carbon atoms.

The content of the maleic anhydride-based comonomer added in the acrylic-norbornene-based copolymer is preferably 10 to 50% by weight.

To the acrylic comonomer is methyl methacrylate (methyl methacrylate), methacrylate (ethyl methacrylate), methacrylate (propyl methacrylate), n - butyl methacrylate (n -butyl methacrylate), t - butyl meta T -butyl methacrylate, cyclohexyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxymethyl methacrylate ), Methacrylic acid, oligomers thereof and the like can be used, but is not limited thereto.

The content of the acrylic comonomer added in the acrylic-norbornene copolymer is preferably more than 0 and 30% by weight or less.

In the retardation film according to the present invention, the acrylic-norbornene-based copolymer preferably has a glass transition temperature (T _g ) of 100 to 250 ° C, more preferably 115 to 250 ° C. The retardation film including the acryl-norbornene copolymer having a glass transition temperature (T _g ) of 100 to 250 ° C. may have excellent heat resistance.

In the retardation film according to the present invention, the acrylic-norbornene-based copolymer is preferably a random copolymer in which acrylic monomers and norbornene-based monomers are randomly connected in the main chain of the copolymer.

In the retardation film according to the present invention, the weight average molecular weight (Mw) of the acryl-norbornene-based copolymer is preferably 50,000 to 300,000, but is not limited thereto.

The retardation film according to the present invention may further include additives such as UV absorbers, plasticizers, retardation enhancers, and the like.

1 type of said UV absorbers may be used, and 2 or more types may be used together. The UV absorbers include, but are not limited to, triazine-based UV absorbers, triazole-based UV absorbers, and HALS (hindered amine light stabilizer) -based UV absorbers. The triazine-based UV absorber may be commercially available Tinuvin 360, Tinuvin 1577 (Ciba Chemicals), Cyasorb UV-1164, Cyasorb UV-2908, Cyasorb UV-3346 (Cytec), etc. Tinuvin 384, Tinuvin 1130, Cyasorb UV-2337, Cyasorb UV-5411 and the like can be used as a HALS-based UV absorber Cyasorb UV-3853 and the like can be used.

As the plasticizer, plasticizers such as phosphate ester, carboxylic acid ester, phthalic acid and phosphoric acid may be used, and more specifically, triphenyl phosphate, phthalic acid ester, dimethyl phthalate, diethyl phthalate, diphenyl phthalate, and the like. Can be. The content of the plasticizer can be added within the limits not impair the physical properties of the retardation film.

The retardation synergist may be added to control the phase difference of the retardation film, a material having an aromatic ring is mainly used, the number of the aromatic ring is not particularly limited, but preferably about 2 to 6 is suitable. For example, trans-stilbene, diphenylacetylene, trans, trans-1,4-diphenyl-1,3-butadiene (trans, trans-1,4-diphenyl-1, 3-butadiene, biphenyl, fluorine, dibenzofuran, 2,7-dibromofluorene, carbazole, N-vinyl N-vinyl carbazole and the like can be used.

The content of the retardation synergist may vary depending on the desired retardation value and the amount of the additive, and stretching conditions, so long as the optical properties of the retardation film are not impaired.

The content of the additive is preferably 0 to 30 parts by weight based on 100 parts by weight of the acrylic-norbornene-based copolymer.

In the retardation film according to the present invention, the in-plane retardation value represented by Equation 1 below is 20 to 50 nm, and the thickness direction retardation value represented by Equation 2 below is preferably -50 to -100 nm.

R _in = (n _x -n _y ) × d

R _th = (n _z -n _y ) × d

In Equation 1 and Equation 2,

n _x is a refractive index of the direction of the largest refractive index in the plane direction of the film,

n _y is a refractive index in the vertical direction in the n _x direction in the plane direction of the film,

n _z is the refractive index in the thickness direction,

d is the thickness of the film.

In addition, the method for producing a retardation film according to the present invention comprises the steps of 1) preparing an unstretched film using an acryl-norbornene-based copolymer comprising an acryl-based monomer and a norbornene-based monomer comprising a benzene ring, and 2) the 1 And stretching the non-stretched film of step).

In the method of manufacturing a phase difference film according to the present invention, the acryl-norbornene-based copolymer of step 1) may further include maleic anhydride-based comonomer, acryl-based comonomer, etc. in the copolymer, the acryl-norbornene-based Specific matters, such as the copolymer is the same as described above, the description thereof will be omitted.

In the method for manufacturing a phase difference film according to the present invention, the method for manufacturing the unstretched film of step 1) may use a solution casting method or an extrusion molding method.

The solution casting method is a method of manufacturing a film using a solution (dope) in which a material is dissolved in an organic solvent.

Examples of the organic solvent used in the solution casting method include halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, acetone, methyl ethyl ketone, di Ketones such as ethyl ketone, cyclohexanone, di-isopropyl ether, tetrahydrofuran, 1,3-dioxane, 1 Ethers such as 1,4-dioxane, esters such as methyl acetate and ethyl acetate, dimethyl formamide, dimethyl acetamide Amide systems, such as these, etc. are mentioned, It is not limited to this.

In the solution casting method, the dope may be prepared by a general method known in the art. The dope may be prepared by adding 10 to 50% by weight of the acrylic copolymer resin and solids such as additives with respect to the organic solvent and stirring the solution. The production temperature is not particularly limited and can be adjusted according to the characteristics of the organic solvent. This solution may be prepared even under pressurized conditions.

The order of addition of each component is not particularly limited and may be produced under an inert gas such as nitrogen gas. The prepared dope can be passed through a coat hanger type T-die, cast into a chrome plating casting drum or belt, dried on a drying roll and wound up to produce a film.

In addition to the solution casting method, a method of manufacturing the unstretched film of step 1) may be prepared by the following melt casting method.

Vacuum drying the acrylic-norbornene-based copolymer to remove moisture and dissolved oxygen, adding rubber components or other additives, and then replacing the raw material hopper to the extruder with a single or twin extruder. extruder), melt at high temperature to obtain raw material pellets, obtain the raw material pellets by vacuum drying, melt through a single extruder substituted with nitrogen from the raw material hopper to the extruder, pass through a coat hanger type T-die, and chrome plated casting rolls And a film can be manufactured through a dry roll etc.

The unstretched film prepared by the solution casting method or the extrusion molding method can obtain a desired phase difference through the 2) stretching process. The stretching step may be performed in the longitudinal direction (MD) stretching or in the transverse direction (TD) stretching, or both. When extending | stretching both a longitudinal direction and a lateral direction, after extending | stretching either one, you can extend in another direction and you may extend | stretch both directions simultaneously. Stretching can be extended in one step or stretched in multiple steps. When extending | stretching in a longitudinal direction, extending | stretching by the speed difference between rolls can be performed, and when extending | stretching in a lateral direction, a tenter is used. The rail starting angle of the tenter is usually within 10 degrees, thereby suppressing a boeing phenomenon occurring in the lateral stretching and regularly controlling the angle of the optical axis. It is also possible to achieve the same anti-boeing effect by multilateral stretching.

The above 2) stretching step will be described in detail.

The longitudinal uniaxial stretching method according to the present invention can be carried out by performing a preheating step, a stretching step and a heat treatment step, respectively, which can be carried out continuously. The longitudinal uniaxial stretching method may be performed using a manufacturing apparatus provided in the order of a preheating zone, a stretching zone and a heat treatment zone.

The preheating step refers to a step of already heating and softening so that the unstretched film can be well stretched in the subsequent stretching step.

In the preheating step, when the glass transition temperature of the non-stretched film is Tg, it is preferable to heat it so that it becomes a fixed temperature in the range of (Tg-30 degreeC)-Tg. The preheating time is preferably 1 to 10 minutes, more preferably 1 to 5 minutes, in order to suppress the deformation more than necessary. If the film is sufficiently preheated in the preheating step, the film is softened sufficiently and there is little variation in the retardation value at the time of stretching.However, preheating for a long time requires a high magnification of the film due to the softening degree of the film, and it is difficult to express sufficient birefringence. do.

In the stretching step proceeding after the preheating step, it is preferable to uniaxially stretch the film in the advancing direction of the film in the temperature range of (Tg-20 ° C) to (Tg + 20 ° C) of the unstretched film. Here, the stretching temperature, the stretching speed, and the draw ratio may be determined by the type, thickness, in-plane retardation value of the retardation film required, and the like. In such a longitudinal uniaxial stretching method, the stretching temperature is more preferably set to (Tg-10 ° C) to (Tg + 10 ° C) of the unstretched film. When the stretching temperature is lower than (Tg-20 ° C) of the unstretched film, the phase difference deviation of the stretched film obtained by concentrating stress when stretching is tended to be large, and when the temperature is higher than (Tg + 20 ° C), the molecular orientation is also high. Low is difficult to express birefringence.

In the manufacturing method of the retardation film which concerns on this invention, although the extending | stretching temperature in the said 2) extending | stretching step changes with kinds of resin to be used, it is preferable that it is usually 80-250 ^o C, and it is more preferable that it is 100-200 ^o C. It is even more preferred that it is 120 ~ 180 ^° C.

Although the draw ratio in said 2) extending | stretching step is set by the expression of the thickness of an unstretched film and an appropriate retardation value, 1.1-3 times is preferable normally. When the draw ratio is lower than 1.1 times, it is difficult to obtain a film having a sufficient retardation value due to the low birefringence expressed. When the draw ratio exceeds 3 times, the deviation of the retardation value of the stretched film becomes large, and neck in There is an increasing problem.

In the drawing step 2), the drawing speed is preferably 10 ~ 500% / min.

The ratio of the width to the length of the stretching section of the film in the stretching step is preferably less than 3, more preferably from 0.5 to 3, even more preferably from 0.5 to 1.5.

Further, in the heat treatment step performed after the preheating step and the stretching step, for the purpose of fixing the orientation of the longitudinal uniaxially stretched film, the temperature of the film is between (stretch temperature-50 ° C) and (stretch temperature-10 ° C). Cool to the range and heat treatment.

When manufacturing the retardation film according to the present invention described above using a manufacturing apparatus provided in the order of preheating zone, stretching zone and heat treatment zone, the film transferred into the preheating zone, stretching zone and heat treatment zone is continuously heated and Although stretched and heat treated to cool, some intermediate temperature region may inevitably occur at the boundaries of these zones. As a means for reducing this intermediate temperature range as much as possible, although not particularly limited, a narrow slit-shaped passage can be provided where the film moves between the zones. In addition, the other section can maintain the temperature of each zone by a method of shielding with a heat insulating partition wall, a shielding with an air curtain, or a combination thereof.

As described above, the retardation film prepared according to the method of the present invention preferably has an in-plane retardation value of 20 to 50 nm and a thickness direction retardation value of -50 to -100 nm.

In addition, the present invention provides a liquid crystal display device comprising one or two or more retardation films.

In particular, since the liquid crystal display according to the present invention may include a retardation film having an in-plane retardation value of 20 to 50 nm and a thickness direction retardation value of -50 to -100 nm, the VA mode liquid crystal display device is preferable, but only It is not limited.

A liquid crystal display including one or two or more retardation films will be described in more detail as follows.

In a liquid crystal display device comprising a liquid crystal cell and a first polarizing plate and a second polarizing plate respectively provided on both surfaces of the liquid crystal cell, a retardation film may be provided between the liquid crystal cell and the first polarizing plate and / or the second polarizing plate. have. That is, a retardation film may be provided between the first polarizing plate and the liquid crystal cell, and one retardation film is provided between the second polarizing plate and the liquid crystal cell, or between the first polarizing plate and the liquid crystal cell and between the second polarizing plate and the liquid crystal cell. 2 or more It may be provided.

The first polarizing plate and the second polarizing plate may include a protective film on one or both surfaces. The inner protective film may include a triacetate cellulose (TAC) film, a polynorbornene-based film made of ring opening metathesis polymerization (ROMP), and a hydrogenated cyclic olefin-based polymer that is ring-opened polymerized. ring opening metathesis polymerization followed by hydrogenation) may be a polymer film, a polyester film, or a polynorbornene-based film made by addition polymerization. In addition, a film made of a transparent polymer material may be used as a protective film, but is not limited thereto.

The present invention also provides an integrated polarizing plate including a polarizing film and including the retardation film according to the present invention on one or both surfaces of the polarizing film as a protective film.

When the retardation film according to the present invention is provided only on one surface of the polarizing film, the other surface may be provided with a protective film known in the art.

As the polarizing film, a film made of polyvinyl alcohol (PVA) containing iodine or dichroic dye may be used. The polarizing film may be prepared by dyeing iodine or dichroic dye on a PVA film, but a method of manufacturing the same is not particularly limited. In the present specification, the polarizing film means a state not including a protective film, and the polarizing plate means a state including a polarizing film and a protective film.

In the integrated polarizing plate of the present invention, the protective film and the polarizing film may be laminated by a method known in the art.

For example, the lamination of the protective film and the polarizing film may be made by an adhesive method using an adhesive. That is, first, an adhesive is coated on the surface of the PVA film, which is a protective film of the polarizing film or a polarizing film, using a roll coater, a gravure coater, a bar coater, a knife coater or a capillary coater. Before the adhesive is completely dried, the protective film and the polarizing film are laminated by heat pressing at room temperature or pressing at room temperature. In the case of using a hot melt adhesive, a heat press roll should be used.

Adhesives that can be used when the protective film and the polarizing plate are laminated include one-component or two-component PVA adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, or hot melt adhesives, but are not limited thereto. Do not. When using a polyurethane adhesive, it is preferable to use the polyurethane adhesive manufactured using the aliphatic isocyanate type compound which does not yellow 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 adhesive diluted with an acetate solvent, a ketone solvent, an ether solvent, or an aromatic solvent may be used. Can also be used. At this time, it is preferable that adhesive viscosity is a low viscosity type of 5,000 cps or less. It is preferable that the adhesives have excellent storage stability and 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. It is preferable that the adhesive is sufficiently cured by heat or ultraviolet rays after lamination, and thus the mechanical strength is improved to the level of the adhesive. It is preferable.

Specific examples of the pressure-sensitive adhesive that can be used include a natural rubber, a synthetic rubber or an elastomer having excellent optical transparency, a vinyl chloride / vinyl acetate copolymer, a polyvinyl alkyl ether, a polyacrylate or a 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.

In addition, the present invention provides a liquid crystal display including the integrated polarizer.

Even when the liquid crystal display device according to the present invention includes the aforementioned integrated polarizing plate, one or more retardation films according to the present invention may be further included between the polarizing plate and the liquid crystal cell.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto.

< Example >

The measurements of the present invention were evaluated by the following assay.

[Weight Average Molecular Weight]

The weight average molecular weight was measured by dissolving the prepared resin in tetrahydrofuran and then using gel osmosis chromatography (GPC).

[Glass transition temperature]

Glass transition temperature was measured using a DSC (Digital scanning calorimeter) of TA Instrument.

[Phase difference value]

The retardation value of the film was measured using AxoScan from Axometrics.

< Example  1>

An acrylic-norbornene copolymer resin having 45 wt% benzyl methacrylate, 20 wt% norbornene, 30 wt% maleic anhydride, and 5 wt% methyl methacrylate was prepared. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 122 degreeC and the weight average molecular weight was 290,000.

The prepared resin was prepared into a 10-50% solution using THF (tetrahydrofuran), and then a film was prepared by using a solution casting method. And the said film was extended | stretched 100-200% at glass transition temperature, and the phase difference value of the film was measured.

The composition content of the acrylic-norbornene-based copolymer is shown in Table 1 below, and the glass transition temperature, the weight average molecular weight, and the retardation value of the film of the acrylic-norbornene-based copolymer are shown in Table 2 below.

< Example  2>

An acrylic-norbornene-based copolymer resin was prepared, comprising 28% by weight of benzyl methacrylate, 20% by weight of norbornene, 40% by weight of maleic anhydride, 6% by weight of methyl methacrylate, and 6% by weight of methacrylic acid. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 139 degreeC and the weight average molecular weight was 85,000.

After preparing the film using the solution casting method, the resin thus prepared was stretched at the glass transition temperature, and the retardation value of the film was measured.

The composition content of the acrylic-norbornene-based copolymer is shown in Table 1 below, and the glass transition temperature, the weight average molecular weight, and the retardation value of the film of the acrylic-norbornene-based copolymer are shown in Table 2 below.

< Example  3>

An acrylic-norbornene copolymer resin having 54 wt% of 2-phenylethyl acrylate, 20 wt% of norbornene, 6 wt% of maleic anhydride, and 20 wt% of methyl methacrylate was prepared. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 120 degreeC and the weight average molecular weight was 112,000.

After preparing the film using the solution casting method, the resin thus prepared was stretched at the glass transition temperature, and the retardation value of the film was measured.

The composition content of the acrylic-norbornene-based copolymer is shown in Table 1 below, and the glass transition temperature, the weight average molecular weight, and the retardation value of the film of the acrylic-norbornene-based copolymer are shown in Table 2 below.

< Example  4>

An acrylic-norbornene copolymer resin of 45 wt% of 2-phenoxyethyl acrylate, 30 wt% of norbornene, 20 wt% of maleic anhydride, and 5 wt% of methyl methacrylate was prepared. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 119 degreeC and the weight average molecular weight was 102,000.

After preparing the film using the solution casting method, the resin thus prepared was stretched at the glass transition temperature, and the retardation value of the film was measured.

The composition content of the acrylic-norbornene-based copolymer is shown in Table 1 below, and the glass transition temperature, the weight average molecular weight, and the retardation value of the film of the acrylic-norbornene-based copolymer are shown in Table 2 below.

< Comparative example  1>

The same method as in Example 1 was used except that a copolymer resin having 59.5 wt% of benzyl methacrylate, 15 wt% of maleic anhydride, and 25.5 wt% of methyl methacrylate was used. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 91 degreeC and the weight average molecular weight was 200,000.

The prepared resin was not able to secure a sufficient impact resistance for film production did not produce a film.

The composition content of the copolymer is shown in Table 1 below, and the glass transition temperature, and the weight average molecular weight of the copolymer are shown in Table 2 below.

< Comparative example  2>

The same method as in Example 1 was used except that a copolymer resin having 25% by weight of norbornene, 25% by weight of maleic anhydride, 25% by weight of methyl acrylate, and 25% by weight of methyl methacrylate was used. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 113 degreeC and the weight average molecular weight was 98,000.

The composition content of the copolymer is shown in Table 1 below, and the glass transition temperature, weight average molecular weight, and retardation value of the film are shown in Table 2 below.

< Comparative example  3>

The same method as in Example 1 was used except that 50% by weight of norbornene and 50% by weight of methyl methacrylate were used. As a result of measuring the glass transition temperature and weight average molecular weight of manufactured resin, the glass transition temperature was 123 degreeC and the weight average molecular weight was 90,000.

The composition content of the copolymer is shown in Table 1 below, and the glass transition temperature, weight average molecular weight, and retardation value of the film are shown in Table 2 below.

BzMA: benzyl methacrylate,

Nb: norbornene,

MAH: maleic anhydride,

MMA: methyl methacrylate,

MAA: methacrylic acid,

MA: methyl acrylate,

2-PhEA: 2-phenylethyl acrylate,

2-PhxEA: 2-phenoxyethylacrylate.

Claims (19)

A retardation film comprising an acryl-norbornene-based copolymer comprising an acryl-based monomer including a benzene ring and a norbornene-based monomer. The retardation film of claim 1, wherein the acrylic monomer including the benzene ring is represented by the following Formula 1: [Formula 1]

In Chemical Formula 1, R ₁ , R _2, and R ₃ each independently represent a hydrogen, monovalent hydrocarbon group having 1 to 30 carbon atoms, an epoxy group, or a phenyl group containing or without a hetero atom, and R ₁ , R _2, and R ₃ At least one of is a phenyl group; R ₄ represents hydrogen or an alkyl group having 1 to 6 carbon atoms. The method of claim 1, wherein the acrylic monomer containing the benzene ring is benzyl methacrylate (benzyl methacrylate), 2-phenylethyl methacrylate (2-phenylethyl methacrylate), 3-phenylpropyl methacrylate (3-phenylpropyl methacrylate ), 4-t-butylphenyl methacrylate, 4-methoxyphenyl methacrylate, 4-methoxyphenyl methacrylate, 1-phenylethyl methacrylate, and Retardation film characterized in that it comprises at least one member selected from the group consisting of 2-phenoxyethyl methacrylate (2-phenoxyethyl methacylate). The retardation film according to claim 1, wherein the content of the acrylic monomer including the benzene ring in the acrylic-norbornene copolymer is 20 to 90 wt%. The retardation film of claim 1, wherein the norbornene-based monomer is represented by the following Chemical Formula 2. [Formula 2]

In Chemical Formula 2, m is an integer from 0 to 4; R ₁ , R ₂ , R ₃ and R ₄ are the same as or different from each other, and each independently hydrogen; halogen; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkyl having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenyl of 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynyl having 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Cycloalkyl having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy Aryl having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or a polar group comprising at least one of oxygen, nitrogen, phosphorus, sulfur, silicon, and boron; When R ₁ , R ₂ , R ₃ and R ₄ are not hydrogen, halogen, or a polar functional group, R ₁ And saturation of R _2, or R ₃ and R ₄ is connected is formed in the alkylidene group having 1 to 10 carbon atoms, or R ₁ or R ₂ is connected with any one of R ₃ and R ₄ each having 4 to 12 carbon atoms, Or an unsaturated aliphatic ring or an aromatic ring having 6 to 24 carbon atoms. The retardation film of claim 1, wherein a content of the norbornene monomer in the acryl-norbornene copolymer is 10 to 80 wt%. The retardation film of claim 1, wherein the acrylic-norbornene-based copolymer further comprises at least one comonomer selected from maleic anhydride-based comonomers and acrylic-based comonomers. The retardation film according to claim 7, wherein the content of the maleic anhydride comonomer added in the acrylic-norbornene-based copolymer is 10 to 50% by weight. The retardation film according to claim 7, wherein the content of the acrylic comonomer added in the acrylic-norbornene copolymer is greater than 0 and 30 wt% or less. The retardation film of claim 1, wherein the acrylic-norbornene-based copolymer has a glass transition temperature (T _g ) of 100 to 250 ° C. The retardation film of claim 1, wherein the acryl-norbornene-based copolymer is a random copolymer. The retardation film of claim 1, wherein a weight average molecular weight (Mw) of the acryl-norbornene-based copolymer is 50,000 to 300,000. The retardation film of claim 1, wherein the retardation film further comprises at least one additive selected from the group consisting of a UV absorber, a plasticizer, and a retardation synergist. The retardation film according to claim 1, wherein the in-plane retardation value represented by Equation 1 below is 20 to 50 nm, and the thickness retardation value represented by Equation 2 is -50 to -100 nm. : [Equation 1] R _in = (n _x -n _y ) × d [Equation 2] R _th = (n _z -n _y ) × d In Equation 1 and Equation 2, n _x is a refractive index of the direction of the largest refractive index in the plane direction of the film, n _y is a refractive index in the vertical direction in the n _x direction in the plane direction of the film, n _z is the refractive index in the thickness direction, d is the thickness of the film. 1) preparing an unstretched film using an acryl-norbornene-based copolymer comprising an acrylic monomer and a norbornene-based monomer comprising a benzene ring, and 2) stretching the non-stretched film of step 1) Method for producing a retardation film comprising a. The method of claim 15, wherein the preparation of the unstretched film of step 1) is performed using a solution casting method or an extrusion molding method. The liquid crystal display device containing one or two or more retardation films of any one of Claims 1-14. A polarizing film is included, The integrated polarizing plate characterized by including the retardation film of any one of Claims 1-14 as a protective film on one surface or both surfaces of the said polarizing film. A liquid crystal display device comprising the integrated polarizing plate of claim 18.