KR101482406B1 - Aqueous Primer Composition, Optical Film comprising the same, Polarizing Plate and Liquid Crystal Display Device used thereof - Google Patents

Abstract

The present invention relates to a urethane resin composition comprising 100 parts by weight of a urethane resin; 1 to 100 parts by weight of polyvinyl alcohol; 0.1 to 10 parts by weight of water-dispersible fine particles and the balance water, an optical film containing the same, a polarizing plate using the same, and a liquid crystal display device.

Description

A water-based primer composition, an optical film containing the same, a polarizing plate using the same, and a liquid crystal display device using the liquid primer composition,

The present invention relates to a water-based primer composition, an optical film containing the same, a polarizer and a liquid crystal display using the same, and more particularly to a water-based primer composition which is excellent in adhesion to an acrylic film and does not impair optical properties and durability An optical film containing a primer composition, a polarizing plate using the same, and a liquid crystal display device.

[0002] A liquid crystal display (LCD) device is a display device that displays pixels by using a principle of selectively passing light by a change in polarization action according to the arrangement of liquid crystals positioned between polarizers. When a polarizing plate alone is applied to a liquid crystal display device without a separate optical film, there is a problem that brightness or contrast is considerably lowered or light leakage occurs when a screen is viewed in an oblique direction. In order to solve such a problem, a method of including an optical compensation film such as a retardation film or a viewing angle compensation film in a polarizing plate, or a method of including an optical compensation film between a polarizing plate and a liquid crystal panel has been used. As described above, optical compensation films such as a retardation film and a viewing angle compensating film are inserted between a polarizing plate and a liquid crystal display device to reduce color change of a liquid crystal display (LCD) device, to enlarge a viewing angle, and to improve luminance.

On the other hand, the optical compensation films can be classified into a stretched film obtained by stretching a polymer film to give an optically anisotropic property, and a liquid crystal film obtained by coating a polymerizable liquid crystal compound on a plastic substrate, drying it, and curing it by irradiating ultraviolet rays .

The stretched films and liquid crystal films used as optical films have optical anisotropy. At this time, the method of imparting optical anisotropy to the stretched film can be generally performed by a method of controlling the mixing ratio of the material having a positive retardation, the material having a negative retardation, and the stretching ratio of the polymer film used in the production of the polymer film. The liquid crystal film may be divided into a disc-type liquid crystal and a rod-type liquid crystal depending on the shape of the liquid crystal molecule. Among them, the liquid crystal film of the rod shape is planar, homeotropic, tilted, splay, and cholesteric. Therefore, a method of imparting optical anisotropy to the liquid crystal film can be generally performed by a method of controlling the orientation pattern.

On the other hand, in general, a conventional liquid crystal film is produced by forming an alignment film 2 on a TAC substrate 3 as shown in Fig. 1, orienting the alignment film by rubbing treatment or polarized light irradiation, And the liquid crystal layer 1 is formed by applying, drying, curing and fixing the liquid crystal compound. However, in this case, due to the weakness of moisture in the TAC film, it causes durability problem due to dimensional change during long-term use.

In order to overcome such disadvantages, attempts have been made to apply a film having a high resistance to moisture and a low phase difference property to a liquid crystal film, such as a cyclic olefin resin or an acrylic resin. Particularly, it is known that an acrylic-based film has advantages in terms of cost as well as optical characteristics and durability. However, unlike the triacetylcellulose (TAC) base material, the acryl-based film has a low roughness due to a high stretching ratio and a dense surface, making it difficult to penetrate the coating layer. As a result, There is a problem that adhesion between the layers is not good. In addition, in the case of the acrylic film, the solvent resistance is poor, and the acrylic film is damaged by the organic solvent contained in the alignment film composition, so that there is a problem that the alignment property is not exhibited well.

Therefore, it is urgent to develop a technique capable of producing an optical film having excellent adhesion to an alignment film and a liquid crystal layer while using an acrylic film as a base film, excellent in solvent resistance, and having excellent orientation characteristics.

Disclosure of Invention Technical Problem [8] The present invention provides an aqueous primer composition, an optical film containing the same, do.

In order to solve the above-described problems, a first aspect of the present invention is directed to a water-based primer composition comprising a primer layer formed on at least one surface of an acrylic film using an aqueous primer composition, wherein the aqueous primer composition comprises a urethane resin, a polyvinyl alcohol, Water, wherein 1 part by weight to 100 parts by weight of polyvinyl alcohol is added to 100 parts by weight of the urethane resin; And 0.1 to 10 parts by weight of the water-dispersible fine particles.

At this time, it is preferable that the solid content of the aqueous primer composition is about 1 to 50 parts by weight based on 100 parts by weight of the whole aqueous primer composition. In the aqueous primer composition, the weight average molecular weight of the urethane resin is preferably from 10,000 to 200,000 and preferably contains a carboxyl group. In addition, the urethane resin may be obtained by reacting a polyol and an isocyanate.

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A third aspect of the present invention provides a polarizing plate comprising the optical film.

A fourth aspect of the present invention provides a display device including the polarizer.

The acrylic film including the primer layer formed using the water-based primer composition of the present invention is excellent in adhesiveness with the orientation film and solvent resistance and can be usefully used as a base film of a liquid crystal film.

In addition, when the liquid crystal film is used as a polarizer protective film, the aqueous primer composition according to the present invention provides excellent adhesion between the polarizer and the acrylic film, thereby inhibiting optical properties such as light transmittance of the prepared polarizer It is advantageous to improve the durability without doing so.

1 shows a structure of a conventional optical film.
2 shows a structure of an optical film according to an example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for clarity.

According to a first aspect of the present invention, there is provided an acrylic film comprising a primer layer formed on at least one side of an acrylic film using an aqueous primer composition, wherein the aqueous primer composition comprises a urethane resin, polyvinyl alcohol, 1 to 100 parts by weight of polyvinyl alcohol relative to 100 parts by weight of the urethane resin; And 0.1 to 10 parts by weight of the water-dispersible fine particles. In the present specification, the content of the urethane resin, polyvinyl alcohol and water-dispersible fine particles means the solid content.

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The waterborne primer composition of the present invention is preferably water-soluble because it is not necessary to introduce explosion-proof equipment.

On the other hand, the weight average molecular weight of the urethane resin is preferably 10,000 to 200,000. When the weight-average molecular weight of the urethane resin satisfies the above-described numerical value range, there is an advantage that the adhesive strength is excellent and urethane synthesis is easy.

The urethane resin is preferably obtained by reacting a polyol with an isocyanate.

At this time, the polyol is not particularly limited as long as it has two or more hydroxy groups in the molecule, and any suitable polyol may be employed. For example, at least one selected from the group consisting of a polyester polyol, a polyether polyol, and a polycarbonate diol may be used in combination, but the present invention is not limited thereto.

In the aqueous primer composition of the present invention, among the examples of the polyol for obtaining the urethane resin, the polyester polyol is preferably obtained by reacting the polybasic acid component with the polyol component.

Herein, the polybasic acid component for obtaining the polyester polyol may be ortho-phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalene dicarboxylic acid, 2,5-naphthalene dicarboxylic acid, 2,6 Aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, biphenyl dicarboxylic acid and tetrahydrophthalic acid, oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, Aliphatic dicarboxylic acids such as sebacic acid, linolenic acid, maleic acid, fumaric acid, mesaconic acid and itaconic acid; Alicyclic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; Or reactive derivatives thereof such as acid anhydrides, alkyl esters, acid halides, and the like can be used in combination, but the present invention is not limited thereto.

Further, the polyol component for obtaining the polyester polyol may be selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, Diol, 1,6-hexanediol, 1,8-octanediol, 1-10-decanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxymethylmethane, diethylene glycol, tri Ethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, glycerin, 1,1,1-trimethylolpropane, , 2,5-hexatriol, pentaerythritol, glucose, sucrose, and sorbitol.

In the aqueous primer composition of the present invention, among the examples of the polyol for obtaining the urethane resin, it is preferable that the polyether polyol is obtained by ring-opening polymerization of an alkylene oxide with a polyhydric alcohol. The polyhydric alcohol may be used in combination of at least one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin and trimethylol propane, but is not limited thereto.

In the aqueous primer composition of the present invention, in the examples of the polyol for obtaining the urethane resin, the polycarbonate polyol may be one selected from the group consisting of poly (hexamethylene carbonate) glycol and poly (cyclohexanecarbonate) glycol , But is not limited thereto.

On the other hand, the isocyanate may be at least one selected from the group consisting of toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate ), Isophorone diisocyanate (IPDI), p-phenylene diisocyanate, 1,4-diisocyanate and xylene diisocyanate (XDI) may be used in combination, but the present invention is not limited thereto.

In the aqueous primer composition according to the present invention, the urethane resin preferably contains a carboxyl group. Here, the carboxyl group forms an anion moiety when dispersed in water-dispersed urethane, disperses it in water, and enhances adhesion with a polarizer.

As described above, the urethane resin containing a carboxyl group can be obtained by reacting the polyol and the isocyanate with a chain extender having a free carboxyl group. At this time, the chain extending agent having a carboxyl group may be, for example, dihydroxycarboxylic acid or dihydroxysuccinic acid, but is not limited thereto.

The dihydroxycarboxylic acid may be at least one compound selected from the group consisting of dimethylol alkanoic acids (dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolpentanoic acid) But is not limited thereto.

On the other hand, any suitable method may be employed for the production of the urethane resin. For example, a one-shot method in which the components are reacted at one time, and a multi-step method in which the components are reacted stepwise. When the urethane resin has a carboxyl group, the urethane resin is preferably prepared by a multistage method in order to easily introduce a carboxyl group. Further, any suitable urethane reaction catalyst may be used in the production of the urethane resin.

In the production of the urethane resin, other polyols, other chain extender, or a combination thereof may be added to the above components.

At this time, the other polyol is not limited as long as it has three or more hydroxyl groups, for example, sorbitol, glycerin, trimethylol ethane, trimethylol propane or pentaerythritol.

The other chain extender may be, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, , 6-hexanediol, propylene glycol and the like; Aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine and aminoethylethanolamine; Alicyclic diamines such as isophoronediamine and 4,4'-dicyclohexylmethanediamine; Aromatic diamines such as xylylenediamine and tolylene diamine, and the like, but are not limited thereto.

On the other hand, in order to improve the stability of the urethane resin in water during the production of the urethane resin, a neutralizing agent can be used. The neutralizing agent may be, for example, one kind selected from the group consisting of ammonia N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine and triisopropanolamine But the present invention is not limited thereto.

When the urethane resin is produced, it is preferable to use an organic solvent which is inert to the isocyanate and compatible with water. At this time, the organic solvent may be an ester solvent such as ethyl acetate and ethyl cellosolve acetate; Ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; And ether solvents such as tetrahydrofuran and dioxane tetrahydrofuran, but not limited thereto.

Next, the weight average molecular weight of the polyvinyl alcohol is preferably 2,000 to 40,000. When the weight average molecular weight of the polyvinyl alcohol satisfies the above-described numerical range, the solvent resistance is improved and the viscosity is not increased, so that coating and drying are easy.

The content of the polyvinyl alcohol may be 1 part by weight to 100 parts by weight, preferably 10 parts by weight to 100 parts by weight, more preferably 50 parts by weight to 100 parts by weight, based on 100 parts by weight of the urethane resin . When the content of polyvinyl alcohol satisfies the above-described numerical value range, the solvent resistance is improved, the adhesiveness with acrylic is good, the content of polyvinyl alcohol is not high, and viscosity is constant, so that leveling is easy during coating.

On the other hand, the polyvinyl alcohol is for improving the solvent resistance and is not particularly limited as long as it is commonly used in the technical field. For example, it may be a product of Japan Synthetic Chemistry of ^{Gohsefimer Z-100 ®, Z-} 200 ®, Z-200H ®, Z-210 ®, Z-220 ® or Z-320 ^®.

Next, the fine particles which can be used in the present invention may be any suitable fine particles, preferably water-dispersible fine particles. Specifically, both inorganic fine particles and / or organic fine particles can be used.

Here, the inorganic fine particles may be, for example, inorganic oxides such as silica, titania, alumina, zirconia or antimony, but are not limited thereto. The organic fine particles may be, for example, a silicone resin, a fluorine resin, a (meth) acrylic resin, a crosslinked polyvinyl alcohol or a melamine resin, but are not limited thereto.

Particularly, in the aqueous primer composition according to the present invention, the water-dispersible fine particles are preferably silica. The silica has an advantage of being more excellent in blocking inhibition ability, excellent in transparency, does not cause haze, has no coloring, and has less effect on the optical characteristics of the polarizing plate. In addition, since silica has good dispersibility and dispersion stability with respect to the aqueous primer composition, workability at the time of forming the primer layer can be more excellent.

On the other hand, the average diameter of the water-dispersible fine particles, that is, the average primary particle diameter may be, for example, 10 nm to 200 nm, 15 nm to 150 nm, or 20 nm to 100 nm. When the average diameter of the water-dispersible microparticles satisfies the above-described numerical value range, the occurrence rate of flocculation and precipitation of the water-dispersible particles in the water-based primer solution is lowered and the stability of the solution is excellent and the dispersion of the water- It is possible to prevent the aggregation of the particles, thereby preventing the haze from rising by scattering the light in the visible light region.

That is, by using the water-dispersible fine particles having the particle diameters in the above-mentioned range, the irregularities are appropriately formed on the surface of the primer layer, and the frictional force on the contact surface between the acrylic film and the primer layer and / . As a result, when the film on which the primer layer is formed is wound, the blocking ability can be further improved.

Since the primer composition of the present invention is an aqueous system, the water dispersible fine particles are preferably formulated as an aqueous dispersion. Specifically, when silica is employed as the water-dispersible fine particles, it is preferably blended as colloidal silica. As the colloidal silica, products commercially available in the technical field can be used as it is. Examples of the colloidal silica include SNOWTEX series manufactured by Nissan Chemical Industries, AEROSIL series manufactured by Air Products, epostar series of Japanese catalyst, soliostar RA series or Ranco LSH series can be used.

At this time, the content of the water-dispersible fine particles may be 0.1 to 10 parts by weight or 0.1 to 8 parts by weight based on 100 parts by weight of the urethane resin. When the content of the water-dispersible fine particles satisfies the above-described numerical value range, the rate of occurrence of blocking remarkably decreases and the haze decreases, and a film having excellent optical properties can be obtained.

Next, the water-based primer composition of the present invention does not specifically limit the solid content. However, the solid content may be, for example, from 1 part by weight to 50 parts by weight, preferably from 5 parts by weight to 30 parts by weight, more preferably from 10 parts by weight to 20 parts by weight, based on 100 parts by weight of the aqueous primer composition . When the solid content in the aqueous primer composition according to the present invention satisfies the above-described numerical value range, the adhesiveness is improved, the viscosity is not high, the leveling is good during coating, and the drying time is short. Here, the solid content refers to the solid content of the entire aqueous primer composition.

According to a second aspect of the present invention, there is provided an optical film comprising a primer layer formed on at least one surface of an acrylic film using the aqueous primer composition.

In the present invention, the optical film collectively refers to a film that performs an optical function, and has a light transmittance of not less than 50% in the case of a narrow transparent film having a light transmittance of 80% or more, as well as a film for performing a specific optical function, Or less.

The acrylic film usable in the present invention may be a single layer or a structure in which two or more films are laminated.

More specifically, the acrylic film may contain a (meth) acrylate resin. At this time, the film containing the (meth) acrylate resin can be obtained by molding a molding material containing, for example, a (meth) acrylate resin as a main component by extrusion molding.

The (meth) acrylate-based resin mainly contains a resin containing a (meth) acrylate-based unit. The (meth) acrylate-based resin is preferably a homopolymer resin composed of a (meth) , And a blend resin in which other resin is blended with the above-mentioned (meth) acrylate-based resin.

Here, the (meth) acrylate-based unit may be, for example, an alkyl (meth) acrylate-based unit. Here, the alkyl (meth) acrylate-based unit means both an alkyl acrylate-based unit and an alkyl methacrylate-based unit, and the alkyl (meth) acrylate-based alkyl group preferably has 1 to 10 carbon atoms , More preferably from 1 to 4 carbon atoms.

Examples of the monomer unit copolymerizable with the (meth) acrylate-based unit include an aromatic vinyl unit, a 3- to 6-membered heterocyclic unit substituted with a carbonyl group, an acrylic acid unit, and a glycidyl unit.

The aromatic vinyl-based unit may be, for example, styrene, alpha -methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4- dimethylstyrene, 2,5- , 2,4,6-trimethylstyrene, cis-? -Methylstyrene, trans-? -Methylstyrene, 4-methyl-? -Methylstyrene, 4-fluoro-? Methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2,3,4,5 , 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, octachlorostyrene, 2- At least one monomer selected from the group consisting of styrenes, styrenes, styrenes, styrenes, m-styrenes, 4-bromostyrenes, 2,4-dibromostyrenes, From But it may be also a unit, and the like. Of these, a unit derived from styrene or? -Methylstyrene is particularly preferable.

Meanwhile, the 3- to 6-membered heterocyclic unit substituted with the carbonyl group may be a unit derived from monomers such as lactone ring, glutaric anhydride, glutarimide, maleic anhydride, maleimide, and the like.

On the other hand, the resin that can be blended with the (meth) acrylate resin is not particularly limited and may be, for example, a phenoxy resin, a polycarbonate resin, or the like.

On the other hand, the method for producing the (meth) acrylate-based resin film is not particularly limited, and for example, the (meth) acrylate-based resin and other polymers and additives may be thoroughly mixed by any appropriate mixing method, (Meth) acrylate resin, other polymers, additives, and the like may be prepared as separate solutions and then mixed to form a homogeneous mixture solution, which may then be subjected to film molding have.

At this time, the thermoplastic resin composition is prepared by pre-blending the film raw material with any appropriate mixer such as, for example, an omni mixer, and extruding and kneading the resulting mixture. In this case, the mixer used for the extrusion kneading is not particularly limited, and any suitable mixer such as an extruder such as a single screw extruder, a twin screw extruder, or a press kneader can be used.

Next, the film forming method may be any suitable film forming method such as solution casting (solution casting), melt extrusion, calendering, or compression molding. Among these film forming methods, a solution casting method (solution casting method) or a melt extrusion method is preferable.

Examples of the solvent used in the solution casting method (solution casting method) include aromatic hydrocarbons such as benzene, toluene and xylene; Aliphatic hydrocarbons such as cyclohexane and decalin; Esters such as ethyl acetate and butyl acetate; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve and butyl cellosolve; Ethers such as tetrahydrofuran and dioxane; Halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride; Dimethylformamide; Dimethyl sulfoxide and the like. These solvents may be used alone or in combination of two or more.

Examples of the apparatus for carrying out the solution casting method (solution casting method) include a drum casting machine, a band casting machine and a spin coater. Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is preferably 150 to 350 占 폚, more preferably 200 to 300 占 폚.

At this time, when the film is formed by the T-die method, a T-die is attached to the tip of a known single-screw extruder or a twin-screw extruder, and a rolled film is obtained by winding a film extruded in a film form. At this time, uniaxial stretching can also be performed by stretching in the extrusion direction by appropriately adjusting the temperature of the winding roll. Further, simultaneous biaxial stretching, sequential biaxial stretching, and the like can also be carried out by stretching the film in a direction perpendicular to the extrusion direction.

On the other hand, the acrylic film may be either an unstretched film or a stretched film. In the case of a stretched film, it may be a uniaxially stretched film or a biaxially stretched film, and in the case of a biaxially stretched film, it may be a simultaneous biaxially stretched film or a sequential biaxially stretched film. When biaxially stretched, the mechanical strength is improved and the film performance is improved. By mixing other thermoplastic resins, the acrylic film can suppress an increase in retardation even when stretching, and can maintain optical isotropy.

In this case, the stretching temperature is preferably in the range of about the glass transition temperature of the thermoplastic resin composition as the raw material of the film, and is preferably (glass transition temperature-30 占 폚) to (glass transition temperature + 100 占 폚) Glass transition temperature-20 占 폚) to (glass transition temperature + 80 占 폚). If the stretching temperature is lower than (glass transition temperature - 30 占 폚), there is a possibility that a sufficient stretching magnification may not be obtained. On the other hand, if the stretching temperature exceeds (glass transition temperature + 100 deg. C), the resin composition may flow (flow), and stable drawing may not be performed.

The stretching ratio defined by the area ratio is preferably 1.1 to 25 times, more preferably 1.3 to 10 times. If the draw ratio is less than 1.1 times, there is a possibility that the toughness accompanying the draw may not be improved. If the stretching magnification exceeds 25 times, there is a possibility that the effect of increasing the stretching magnification may not be recognized.

Further, the stretching speed is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min in one direction. When the drawing speed is less than 10% / min, it takes a long time to obtain a sufficient drawing magnification, which may increase the manufacturing cost. If the stretching speed is higher than 20,000% / min, the stretched film may be broken.

On the other hand, in order to stabilize the optical isotropy and mechanical properties of the acrylic film, heat treatment (annealing) or the like may be performed after the stretching treatment. The heat treatment conditions are not particularly limited and any suitable conditions well known in the art may be employed.

Next, the acrylic film may be subjected to a surface treatment for improving the adhesion strength, if necessary. For example, at least one surface of the acrylic film may have at least one surface selected from the group consisting of alkali treatment, corona treatment, and plasma treatment Processing can be performed.

Meanwhile, the primer layer may be formed by coating the aqueous primer composition on at least one side of the acrylic film, which is formed by the aqueous primer composition of the present invention. The details of the water-based primer composition are the same as those described above, so a detailed description thereof will be omitted.

Meanwhile, the primer layer may be formed by a coating layer forming method generally used in the related art such as wire coating, bar coating, spin coating, etc., and the method of forming the primer layer is not particularly limited.

On the other hand, in the optical film of the present invention, the primer layer may be formed on only one side of the acrylic film or on both sides of the acrylic film. According to the studies of the present inventors, it has been shown that the aqueous primer composition of the present invention not only improves the adhesion between the alignment film and the acrylic film, but also can improve the adhesion between the polarizer and the acrylic film. Therefore, when the primer layer of the aqueous primer composition of the present invention is formed on both sides of the acrylic film, both the adhesive force between the polarizer and the acrylic film and the adhesive force between the acrylic film and the alignment film can be improved.

2, the optical film of the present invention further comprises an orientation film layer 2 and a liquid crystal layer 1 on a primer layer 4 formed on at least one side of the acrylic film 5 .

At this time, the alignment layer may be formed by applying various alignment film compositions known in the art, for example, compositions for a photo alignment film or a rubbing alignment film on a primer layer, and then rubbing or polarizing . The alignment film composition and the alignment film formation method usable in the present invention are not particularly limited, and various alignment film compositions and alignment film formation methods well known in the art can be used without limitation.

At this time, the method of applying the alignment film composition may be carried out by a method well known in the art, for example, a method such as wire coating, bar coating, spin coating and the like.

Further, after application of the alignment film composition, a drying process may be performed to remove the residual solvent, wherein the drying may be performed at 70 ° C to 150 ° C for at least 30 seconds. The drying temperature and time are not particularly limited, but if the above conditions are satisfied, the alignment film can be sufficiently dried without causing deformation of the substrate.

On the other hand, in the alignment treatment, a method such as rubbing alignment or photo alignment can be appropriately used depending on the kind of the alignment film to be used. In order to improve the alignment property, both rubbing alignment and photo alignment can be used if necessary. At this time, the rubbing orientation can be performed by a method such as rubbing the surface of the alignment layer with a cloth or the like, and the photo alignment can be performed by irradiating the polarized ultraviolet ray through the polarizing plate or the like between the alignment layer and the light source. At this time, the ultraviolet ray irradiation can be performed in the air or in a nitrogen atmosphere in which oxygen is shut off to increase the reaction efficiency. Typically, a medium or high pressure mercury ultraviolet lamp or metal halide lamp having an intensity of 80 w / cm or more can be used for ultraviolet irradiation.

On the other hand, in the case of the present invention, an alignment film composition comprising a photoreactive polymer, a polyfunctional monomer, an initiator and a solvent may be used as the alignment film composition, but the alignment film composition may further contain a crosslinking agent . More specifically, the alignment film composition of the present invention is not limited to this, but it is preferable that 0.05 part by weight to 10 parts by weight of the polyfunctional monomer, 0.05 to 10 parts by weight of the photoreactive polymer, 0.01 part by weight of the photoinitiator 0.01 By weight to 5 parts by weight and the balance solvent, and if necessary, may further include 0.01 to 2 parts by weight of a crosslinking agent.

As the polyfunctional monomer, a mixed polyfunctional monomer which is a mixture of a polyfunctional triazine monomer and a polyfunctional acryl monomer may be used. The mixing ratio of the triazine monomer and the acrylic monomer is not particularly limited in the mixed polyfunctional monomer of the polyfunctional triazine monomer and the polyfunctional acrylic monomer and as long as the triazine monomer and the acrylic monomer are used together, Mixed multifunctional monomers mixed in any ratio can be used.

The polyfunctional triazine monomer may be, for example, 1,3,5-triallyl-1,3,5-triazinerene-2,4,6-trione, 1,3,5- 1,3,5-triazine, 1,3,5-tris (2-oxinarylmethyl) -1,3,5-triazinene-2,4,6-trione, 2- {3 , 5-bis [2- (acryloyloxy) ethyl] -2,4,6-trioxo-1,3,5-triazin-1-yl} ethyl acrylate, and 3- At least one member selected from the group consisting of -S- (2- cyano-ethyl) -2,4,6-trioxo- (1,3,5) triazin-1-yl-propionitrile But is not limited thereto.

Further, the polyfunctional acrylic monomer may be, for example, triacrylate (particularly, pentaerythritol triacrylate, PETA), tetraacrylate (in particular, pentaerythritol tetraacrylate But is not limited to, at least one selected from the group consisting of pentaerythritol tetraacrylate (PETTA) and hexaacrylate (especially, dipentaerythritol hexaacrylate, DPHA) . On the other hand, the content of the mixed polyfunctional monomer may be 0.05 part by weight to 10 parts by weight based on the photo alignment layer composition. When the content of the polyfunctional acrylic monomer satisfies the above-described numerical value range, the interlayer adhesion between the photo alignment film and the base film is excellent, so that the problem of peeling of the photo alignment film can be prevented and excellent orientation property can be realized.

On the other hand, the photoreactive polymer may be, for example, a norbornene-based photoreactive polymer containing a cinnamate group. Examples of the norbornene-based photoreactive polymer include a polynorbornene cinnamate, a polynorbornene alkoxy cinnamate (the alkoxy group has 1 to 20 carbon atoms), a polynorbornene allyloyloxycinnamate, a poly But are not limited to, at least one selected from the group consisting of norbornene fluorinated cinnamate, polynorbornene chlorinated cinnamate, and polynorbornene dicinnamate. Further, the content of the photoreactive polymer may be 0.05 to 10 parts by weight, 1 to 10 parts by weight, or 0.1 to 10 parts by weight based on the photo alignment layer composition. When the content of the photoreactive polymer satisfies the above-described numerical value range, a photo alignment film having excellent orientation properties can be obtained.

The photoinitiator may be any solvent capable of inducing a radical reaction, and more preferably water-soluble. For example, IRGACURE 2959, 2-Hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone, supplied by Ciba-Geigy, 2-oxo-2-phenyl-acetoxy-ethoxy] -ethyl ester and oxy-phenyl-acetic acid (IRGACURE 500, 1-Hydroxy-cyclohexyl-phenyl- ketone + Benzophenone), IRGACURE 754 phenyl-acetic 2- [2-hydroxyethoxy] -ethyl ester or IRGACURE OXE02, 1- (1-6-benzoyl-9-ethyl-9H-carbazol-3-yl) ethylideneaminooxy) ethanone, But is not limited thereto. On the other hand, the content of the photoinitiator may be 0.01 to 5 parts by weight based on the photo alignment layer composition. When the content of the photoinitiator satisfies the above numerical range, the effect of the crosslinking reaction by the multifunctional monomer can be expected and the orientation of the liquid crystal is increased.

On the other hand, the solvent is not particularly limited as long as it can dissolve the polyfunctional monomer and the photoreactive polymer. Examples of the solvent include halogenated hydrocarbons such as chloroform, tetrachloroethane, trichlorethylene, tetrachlorethylene and chlorobenzene; Aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, and 1,2-dimethoxybenzene; Ketones such as acetone, methyl ethyl ketone, cyclohexanone, and cyclopentanone; Alcohols such as isopropyl alcohol and n-butanol; Cellosolve such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; , Water, or a mixture thereof may be used.

As the crosslinking agent, aldehyde, dialdehyde or isocyanate may be used. However, the crosslinking agent is not limited thereto. The aldehydes or dialdehydes may be, for example, acrylic aldehyde, oxaldehyde, 2-methylacrylaldehyde, 2-oxopropane or glutaraldehyde, but are not limited thereto. The isocyanate may be, for example, 2-isocyanatoethyl 2-methylacrylate, 1,4-diisocyanatobutane, 1,4-diisocyanatobenzene or 1,3-diisocyanatobenzene , But is not limited thereto. The crosslinking agent may be used alone or in a mixture of two or more.

Further, the content of the crosslinking agent may be 0 to 2 parts by weight, preferably 0.01 to 2 parts by weight, based on the total composition of the alignment film. When the content of the cross-linking agent satisfies the above-described numerical value range, it is possible to induce a sufficient cross-linking reaction to provide excellent moisture resistance, excellent solution stability and uniform applicability, and particularly excellent alignment power of the liquid crystal after the alignment treatment .

Next, the liquid crystal layer may be formed by a liquid crystal layer formation method well known in the art, for example, a method of applying a solution of a liquid crystal compound on an oriented alignment layer and then fixing the solution.

At this time, the application of the liquid crystal compound solution may be performed by a general method well known in the art, for example, a method such as wire coating, bar coating, spin coating and the like.

Further, after applying the liquid crystal compound solution, a drying process may be performed to remove the remaining solvent, and the drying may be performed at 25 ° C to 120 ° C for at least 1 minute or more. The drying temperature and time are not particularly limited, but from the viewpoints of improvement in liquid crystal orientation and prevention of occurrence of defects, it is more preferable to satisfy the above drying conditions.

On the other hand, the fixation is for fixing the orientation of the liquid crystal, and can be performed, for example, by polymerizing and curing the liquid crystal compounds through ultraviolet irradiation. At this time, the ultraviolet ray irradiation can be performed in the air or in a nitrogen atmosphere in which oxygen is shut off to increase the reaction efficiency. Typically, the ultraviolet irradiator may be a medium pressure or high pressure mercury ultraviolet lamp having a strength of 80 w / cm or more, or a metal halide lamp. A cold mirror or other cooling device may be provided between the substrate and the ultraviolet lamp so that the surface temperature of the liquid crystal layer may be within the temperature range having the liquid crystal state upon ultraviolet irradiation.

As the liquid crystal compound solution, liquid crystal compound solutions commonly used in the related art can be used without limitation. For example, a liquid crystal compound solution prepared by dissolving the polymerizable liquid crystal compound and the photoinitiator in an organic solvent, Can be used.

At this time, as the polymerizable liquid crystal compound, a material well known in the related art can be used as the material having an acrylate group capable of being polymerized by a photoreaction, but the present invention is not limited thereto. For example, a nematic or cholesteric liquid crystal phase at room temperature or high temperature, such as a cyanobiphenyl-based, cyanophenylcyclohexane-based, cyanophenyl ester-based, benzoic acid phenyl ester-based or phenylpyrimidine- And may be a low-molecular liquid crystal. These materials may be used alone or in a mixture of two or more. The content of the polymerizable liquid crystal compound in the liquid crystal compound solution is not particularly limited, but may be 5 to 70 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the liquid crystal compound solution. When the content of the polymerizable liquid crystal compound satisfies the above-described numerical range, the occurrence of stains is remarkably reduced, and the problem of the polymerizable liquid crystal compound precipitating due to a shortage of the solvent can be prevented.

The photoinitiator may be any of those well known in the art. For example, IRGACURE 907 or the like may be used. On the other hand, the content of the photoinitiator is preferably about 3 to 10 parts by weight based on 100 parts by weight of the polymerizable liquid crystal compound contained in the liquid crystal compound solution. When the content of the photoinitiator satisfies the above-described numerical range, it is possible to sufficiently cure by irradiating ultraviolet rays, and it is possible to prevent the liquid crystal alignment from being changed due to the influence of the photoinitiator.

In addition to the photoinitiator, a chiral agent, a surfactant, a polymerizable monomer or a polymer may be added to the liquid crystal compound solution as long as it does not interfere with the liquid crystal alignment.

Examples of the organic solvent used for preparing the liquid crystal compound solution include halogenated hydrocarbons such as chloroform, tetrachloroethane, trichlorethylene, tetrachlorethylene and chlorobenzene; Aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, and 1,2-dimethoxybenzene; Ketones such as acetone, methyl ethyl ketone, cyclohexanone, and cyclopentanone; Alcohols such as isopropyl alcohol and n-butanol; Cellosolve such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; But are not limited thereto. These may be used alone or in a mixture of two or more.

According to a third aspect of the present invention, there is provided a polarizing plate comprising the optical film according to the present invention. The polarizing plate of the present invention may include, for example, a polarizer and the above-described optical film of the present invention disposed on at least one side of the polarizer. More specifically, the polarizing plate of the present invention may include an optical film of the present invention in which an acrylic film, a primer layer, an orientation film layer, and a liquid crystal layer are sequentially laminated on at least one surface of a polarizer.

The polarizing plate of the present invention preferably has a light transmittance of 35% to 45% and a polarization degree of 98% or more.

According to a fourth aspect of the present invention, there is provided a display device including the polarizer.

The display device includes a liquid crystal display device or the like, but the type is not particularly limited as long as the optical film or the polarizing plate as described above is required. The display device has a configuration known in the art, except that it comprises a primer layer formed using an aqueous primer composition according to the present invention. For example, the display element may include a liquid crystal cell; And a liquid crystal display device including the polarizing plate and the backlight unit according to the present invention provided on both sides of the liquid crystal cell.

Example  One

(Riko corporation, solid content 20%) of polyvinyl alcohol aqueous solution (Nippon Synthetic Chemical Co., Ltd., 4.5% aqueous solution), 50 g of a urethane resin emulsion (CK-PUD-F (solid content 10% emulsion) Aqueous solution) were mixed to prepare an aqueous primer composition having a solid content ratio of urethane resin and polyvinyl alcohol of 1: 1. Then, the aqueous primer composition was coated on the corona-treated acrylic film (LG Chemical GP-film) to a thickness of about 1000 nm in # 9 bar and dried at 100 ° C for 5 minutes to prepare an acrylic film having a primer layer Respectively.

Next, a photoreactive polymer, 5-norbornene-2-methyl- (4-methoxy cinnamate), dipentaerythritol hexaacrylate, a multifunctional monomer, and a photo initiator, IGACURE OXE02 (Ciba-Geigy ) Was dissolved in cyclopentanone in a concentration of 2 parts by weight, 2 parts by weight and 0.5 part by weight, respectively, to prepare a photo alignment film composition.

Then, the photo alignment film composition was dried on the primer layer of the acrylic film, and then the film was coated with wire bar so that the thickness was 100 nm, followed by hot air drying in a drying oven at 70 캜 for 2 minutes. Then, a high-pressure mercury lamp of 80 W / cm intensity was used as a light source, and a wire grid polarizer of Moxtek Company was interposed between the light source and the alignment film so that polarized ultraviolet rays were emitted, and the alignment treatment was performed by exposing it once at a speed of 3 m / min. Cured by irradiation with ultraviolet rays, and subjected to a rubbing treatment in order to impart orientation to the surface of the cured alignment layer, thereby completing an alignment layer.

Next, 95 parts by weight of A-PLATE (a planar alignment liquid crystal mixture made of Merck's cyanobiphenyl-based, cyanophenylcyclohexane-based and cyanophenyl ester-based acrylate) and 90 parts by weight of a photo initiator, (Ciba-Geigy, Switzerland) was dissolved in toluene so that the solid content was 25 parts by weight per 100 parts by weight of the total solution. The polymerizable liquid crystal compound solution prepared by drying on the alignment layer was coated so as to have a thickness of 1 μm Dried in a 60 ° C drying oven for 2 minutes, and irradiated with a non-polarized UV light with a high-pressure mercury lamp of 80 W / cm intensity to cure the liquid crystal layer.

Example  2

An optical film was prepared in the same manner as in Example 1, except that the water-based primer composition was coated to a thickness of about 500 nm with # 5 bar.

Example  3

An optical film was prepared in the same manner as in Example 1, except that the aqueous primer composition was coated to a thickness of about 200 nm with # 3 bar.

Example  4

An optical film was prepared in the same manner as in Example 1, except that a primer layer was formed using an aqueous primer composition adjusted to have a solid content ratio of urethane resin and polyvinyl alcohol of 1: 0.5.

Example  5

An optical film was prepared in the same manner as in Example 1, except that a primer layer was formed using an aqueous primer composition adjusted to have a solid content ratio of urethane resin and polyvinyl alcohol of 1: 0.1.

Comparative Example  One

An optical film was produced in the same manner as in Example 1, except that a primer layer was formed using an aqueous primer composition containing no polyvinyl alcohol.

Comparative Example  2

An optical film was prepared in the same manner as in Example 1, except that a primer layer was formed using an aqueous primer composition containing no urethane resin.

Comparative Example  3

An optical film was prepared in the same manner as in Example 1, except that a primer layer was formed using an aqueous primer composition adjusted to have a solid content ratio of urethane resin and polyvinyl alcohol of 1: 4.

Experimental Example

1. Adhesion

The adhesion between the acrylic substrate and the alignment film and between the alignment film and the liquid crystal film was evaluated by a cross-cut test method defined by ASTM. The surface of the liquid crystal film was cross-cut at a distance of 1 mm with a knife in the same line shape as a checkerboard, and then a cellophane tape was attached thereon. The results are shown in Table 1 below. When O is fully attached, X refers to the case where it is partially peeled off or completely peeled off.

2. Orientation

The orientation of the liquid crystal layer formed on the photo alignment layer was visually confirmed, and the case where the alignment was not observed was indicated by X, and the case where there was some deviation but the alignment was indicated by & cir & The results are shown in Table 1.

division Primer Layer Thickness Whether water-dispersible fine particles are included The ratio of solid content of urethane resin to polyvinyl alcohol The polyvinyl alcohol weight ratio to 100 parts by weight of urethane Base film Adhesion Orientation Example 1 1000 nm include 1: 1 100 Acrylic film O O Example 2 500 nm include 1: 1 100 Acrylic film O O Example 3 200 nm include 1: 1 100 Acrylic film O O Example 4 1000 nm include 1: 0.5 50 Acrylic film O O Implementation 5 1000 nm include 1: 0.1 10 Acrylic film O O Comparative Example 1 1000 nm include 1: 0 0 Acrylic film O X Comparative Example 2 1000 nm include 0: 1 - Acrylic film X X Comparative Example 3 1000 nm include 1: 4 400 Acrylic film X O

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments, but various modifications and changes may be made without departing from the scope of the invention. To those of ordinary skill in the art.

1: liquid crystal layer
2: Orientation film
3: TAC film
4: Primer
5: Acrylic film

Claims (14)

A primer layer formed by using an aqueous primer composition on at least one surface of an acrylic film,
Wherein the aqueous primer composition comprises a urethane resin, polyvinyl alcohol, water-dispersible fine particles and water, wherein 1 to 100 parts by weight of polyvinyl alcohol is added to 100 parts by weight of the urethane resin; And 0.1 to 10 parts by weight of water-dispersible fine particles,
Wherein the polyvinyl alcohol has a weight average molecular weight of 2,000 to 40,000.
The optical film according to claim 1, wherein the solid content of the aqueous primer composition is 1 to 50 parts by weight based on 100 parts by weight of the aqueous primer composition.
The optical film according to claim 1, wherein the urethane resin has a weight average molecular weight of 10,000 to 200,000.
The optical film according to claim 1, wherein the urethane resin comprises a carboxyl group.
The optical film according to claim 1, wherein the urethane resin is obtained by reacting a polyol with an isocyanate.
delete The optical film according to claim 1, wherein the water dispersible fine particles are at least one inorganic fine particle selected from the group consisting of silica, titania, alumina, zirconia and antimony fine particles.
The optical film according to claim 1, wherein the water-dispersible fine particles are at least one organic fine particle selected from the group consisting of a silicone resin, a fluorine resin, a (meth) acrylic resin, a crosslinked polyvinyl alcohol and a melamine resin.
The optical film according to claim 1, wherein the water-dispersible fine particles have an average diameter of 10 nm to 200 nm.
delete The optical film according to claim 1, wherein the thickness of the primer layer is 50 nm to 1000 nm.
The optical element according to claim 1, further comprising: an alignment layer formed on the primer layer; And a liquid crystal layer formed on the alignment film layer.
A polarizing plate comprising the optical film of any one of claims 1 to 5, 7 to 9, 11 and 12.
A display device comprising the polarizer of claim 13.

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