WO2015047012A1 - Optical film comprising primer layer containing polyester resin and polarizing plate using same - Google Patents

Abstract

The present invention relates to an optical film comprising: a base film; and a primer layer formed on at least one surface of the base film and containing a polyester resin and water-dispersive microparticles, the difference in the refractive index between the base film and the polymer layer being 0.03 or smaller, wherein the polyester resin contains polyester glycol formed by a reaction of polybasic acid and polyol, the polybasic acid containing an aromatic carboxylic acid compound and an aliphatic carboxylic acid compound at a mole ratio of 1:9 to 9:1. Superior adhesive strength and a small refractive index difference between the optical film and a functional coating layer lead to a reduction in the rainbow phenomenon, and excellent optical properties.

Description

Optical film comprising a primer layer containing a polyester resin and a polarizing plate using the same

The present invention relates to an optical film and a polarizing plate including the same, and more particularly, to an optical film including a primer layer including a polyester resin and having a refractive index difference between the base film and the primer layer of 0.03 or less, and a polarizing plate including the same. .

The polarizing plate has been commonly used as a structure in which a protective film is laminated using one or both surfaces of a polarizer made of polyvinyl alcohol (hereinafter referred to as 'PVA')-based resin dyed with dichroic dye or iodine. Conventionally, a triacetyl cellulose (TAC) film has been mainly used as a polarizer protective film, but such a TAC film has a problem in that it is easily deformed in a high temperature and high humidity environment. Accordingly, recently, protective films of various materials that can replace TAC films have been developed. For example, polyethylene terephthalate (PET), cycloolefin polymer (COP, cycloolefin polymer), and acrylic films may be used alone. Or a mixed use has been proposed.

Meanwhile, the polarizer protective film as described above may include various functional coating layers such as an antireflection layer and a hard coating layer on the opposite side of the surface to which the polarizer is attached for the purpose of antireflection, durability improvement, scratch prevention, and visibility improvement. Such functional coating layers are generally formed by applying a coating composition including a base resin, a solvent, an additive, and the like on a protective film and then curing the coating composition. However, depending on the type of protective film, the adhesive strength with such a functional coating layer may not be sufficient. In this case, the functional coating layer may be peeled off or damaged from the protective film, thereby degrading the performance of the polarizing plate.

In order to solve this problem, a method of performing surface treatment such as plasma treatment, corona treatment, or forming a primer layer on the surface of the protective film has been proposed. The adhesion between the film and the functional coating layer could not be sufficiently secured. For example, in the case of a urethane-based resin that has been proposed as a primer layer for a conventional protective film, the water resistance and solvent resistance is low, the adhesive strength is reduced due to moisture infiltration during long-term storage under high humidity, or a coating containing an organic solvent on the primer layer When applying the composition, the primer layer is dissolved due to the organic solvent included in the coating composition, there was a problem that the primer layer is detached from the film.

In addition, in the case of the functional coating layer for anti-reflection and scratch prevention, diffuse reflection is performed by using diffused silica with different sizes to give the anti-reflection function by lowering the reflectance, or by lowering the reflectance to 1% by using a layer having a low refractive index. It will give anti-reflection function. When using different sizes of silica or using a low refractive index layer, since the coating layer is transparent, there is a problem in that a rainbow phenomenon due to interference of light appears when the difference in refractive index between the primer layer and the acrylic film is large.

Accordingly, in order to solve the above problems, it is necessary to develop an optical film and a polarizing plate having excellent adhesive properties and excellent optical properties through a primer layer having excellent water resistance and solvent resistance.

In order to solve the above problems of the present invention, a primer layer containing a polyester resin excellent in water resistance, solvent resistance and adhesion on at least one surface of the base film, the difference in refractive index between the primer layer and the base film An optical film and a polarizing plate of 0.03 or less are provided.

According to one embodiment of the present invention, the present invention is a base film; And a primer layer containing a polyester resin and water-dispersible fine particles on at least one surface of the base film and having a refractive index difference of 0.03 or less, wherein the polyester resin is an aromatic carboxylic acid compound and an aliphatic carboxylic acid compound. It provides an optical film comprising a polyester glycol formed by the reaction of a polybasic acid and a polyol contained in a molar ratio of 1: 9 to 9: 1.

Meanwhile, the polyester resin may include a polyester acrylic resin formed by further copolymerizing an acrylic monomer to a polyester glycol formed by the reaction of a polybasic acid and a polyol, wherein the polyester glycol and the acrylic monomer are 2: It is preferable to copolymerize in the weight ratio of 8-7: 3.

On the other hand, the primer layer may additionally include an acrylic compound.

On the other hand, the base film preferably has a refractive index of 1.45 to 1.65, it may be an acrylic film.

According to another embodiment of the present invention, the present invention is a polarizer; And it provides a polarizing plate comprising the optical film according to the present invention on at least one surface of the polarizer.

According to another embodiment of the present invention, the present invention provides an image display device including the polarizing plate according to the present invention.

The optical film of the present invention, by using a primer layer containing a polyester resin and water-dispersible fine particles, can realize sufficient adhesion between the optical film and the functional coating layer, without additives such as a crosslinking agent, and can maintain a stable adhesion for a long time have.

In addition, by controlling the content ratio of the elements constituting the polyester resin, it is easy to control the refractive index difference between the base film and the primer layer to 0.03 or less, thereby reducing the rainbow phenomenon and providing an optical film and a polarizing plate excellent in optical properties. can do.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The inventors of the present invention have been studied to develop an optical film having excellent adhesion to the functional coating layer and excellent optical performance, and as a result, at least one surface of the base film includes a primer layer containing a polyester resin and water-dispersible fine particles, It came to develop the optical film of this invention whose refractive index difference of the said base film and a primer layer is 0.03 or less.

Since the optical film according to the present invention contains a polyester resin having excellent solvent resistance and water resistance as a main component as a primer layer, it is possible to minimize the damage of the base film by the organic solvent included in the functional coating layer composition, and the functional coating layer Adhesion of a base film is improved and peeling of a functional coating layer can be prevented effectively.

In addition, the difference in the refractive index between the base film and the primer layer is small, it is possible to minimize the occurrence of optical defects such as the rainbow phenomenon caused by the difference in reflectance between the base film and the primer layer.

On the other hand, the rainbow phenomenon refers to unevenness caused by interference of light generated by light reflection, and when the refractive index difference between the base film and the primer layer is large, the light reflected from the surface of the base film and the light reflected from the surface of the primer layer This occurs because the difference in reflectance of each wavelength of light generated by overlapping is large. This rainbow phenomenon weakens visibility and causes eye fatigue. Therefore, when the refractive index of a primer layer has a difference within 0.03 from the refractive index of a base film, the difference in reflectance for each wavelength is not large, and rainbow phenomenon can be suppressed.

More specifically, the optical film of the present invention; And a primer layer containing a polyester resin and water-dispersible fine particles on at least one surface of the base film and having a refractive index difference of 0.03 or less, wherein the polyester resin is an aromatic carboxylic acid compound and an aliphatic carboxylic acid compound. It is characterized by comprising a polyester glycol formed by the reaction of a polybasic acid and a polyol contained in a molar ratio of 1: 9 to 9: 1.

More specifically, in the present invention, the polyester resin refers to a resin containing an ester group formed by the reaction of carboxylic acid and alcohol in the main chain, preferably, may be a water-dispersible polyester resin, polybasic acid ( polyester glycols formed by the reaction of polybasic acid) with a polyol.

In this case, the polybasic acid component is an aromatic carboxylic acid compound and an aliphatic carboxylic acid compound, and the aromatic carboxylic acid compound and the aliphatic carboxylic acid compound are not only aromatic carboxylic acid and aliphatic carboxylic acid, but also reactive derivatives such as acid anhydrides, alkyl esters, acid halides, and the like. It may include. These can be used individually or in combination of 2 or more types. Among these, terephthalic acid, isophthalic acid, succinic acid and the like are particularly preferable. Moreover, when using isophthalic acid substituted by sulfonate as a basic acid, it is especially preferable at the point of water dispersibility.

More specifically, the aromatic carboxylic acid compound is not limited thereto, for example, ortho-phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6- Naphthalenedicarboxylic acid, biphenyldicarboxylic acid and tetrahydrophthalic acid.

In addition, the aliphatic carboxylic acid compound is not limited thereto, for example, oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, linoleic acid, maleic acid, Chain aliphatic carboxylic acids such as fumaric acid, mesaconic acid and itaconic acid; And cyclic aliphatic carboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.

In addition, as said polyol, if it has two or more hydroxyl groups in a molecule | numerator, it will not specifically limit, Arbitrary appropriate polyol can be employ | adopted. For example, as the polyol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6- Hexanediol, 1,8-octanediol, 1,10-decanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxymethylmethane, diethylene glycol, triethylene glycol, polyethylene glycol ( PEG), dipropylene glycol, polytetramethylene glycol (PTMG), polypropylene glycol (PPG), 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, glycerin, 1,1 Preference is given to at least one member selected from the group consisting of, 1-trimethylolpropane, 1,2,5-hexatriol, pentaerytriol, glucose, sucrose, and sorbitol. Moreover, when polydimethylol dimethylol alkanoic acid dimethylol acetic acid, dimethylol propionic acid, dimethylol butanoic acid, etc. which contain a carboxyl group are used individually or in combination of 2 or more types, it is especially preferable at the point of water dispersibility.

Meanwhile, the polyester glycol reacts the polybasic acid and the polyol in a molar ratio of 2.5: 1 to 1: 2.5, preferably in a molar ratio of 2.3: 1 to 1: 2.3, more preferably in a molar ratio of 2: 1 to 1: 2. Is preferably formed. This is because when the reaction molar ratio of the polybasic acid and the polyol is outside the above numerical range, an odor may occur or unsatisfactory coating may occur due to the unreacted monomer.

On the other hand, a feature of the present invention is an optical film having a refractive index difference between the base film and the primer layer of 0.03 or less, wherein the difference in refractive index is set to 0.03 or less by adjusting the composition ratio of the polybasic acid.

As described above, the polyester resin comprises a polyester glycol formed by the reaction of a polybasic acid and a polyol, the polybasic acid includes an aromatic carboxylic acid compound and an aliphatic carboxylic acid compound, wherein the polybasic acid is an aromatic carboxylic acid compound and an aliphatic It is preferable that the carboxylic acid compound is contained in a molar ratio of about 1: 9 to 9: 1. More preferably in a molar ratio of about 2: 8 to 8: 2. When the numerical range is satisfied, the refractive index difference between the base film and the primer layer may be adjusted to be 0.03 or less, and the surface may be evenly formed without tacky.

More specifically, when the content of the aromatic carboxylic acid compound is less than that of the aliphatic carboxylic acid compound, the refractive index of the primer layer decreases, and when the content of the aromatic carboxylic acid is large, the refractive index of the primer layer increases. That is, adjustment is possible so as to be close to the refractive index of the base film described below.

The refractive index (n) is a ratio of the speed (Cm) of the light passing through the medium to the speed (Cv) of the light in vacuum, as shown in Equation 1 below, when the light passes through the medium having high electron density, Since the attraction speed is slowed down, the refractive index increases. Specifically, since the aromatic ring has a structure in which π electrons are shared in 2p orbital, and electrons are high due to the structure in which electrons float on a flat aromatic ring, it is easy to interact with light irradiated compared to aliphatic. Therefore, as described above, when light passes through a medium having a large number of aromatic rings, the speed decreases and the refractive index increases.

[Equation 1]

n = Cv / Cm

On the other hand, the polyester resin may be further copolymerized with an acrylic monomer component, if necessary, to a polyester acrylic resin containing an acrylic unit together with the ester unit. In this case, the polyester unit serves to increase the adhesion of the substrate and the acrylic unit may further improve the solvent resistance.

The acrylic monomers usable in the present invention include, for example, alkyl (meth) acrylates, alkyl acrylates, epoxy (meth) acrylates, hydroxy alkyl acrylates, alkyl (meth) acrylic acids including alkyl groups, alkyl acrylic acids, It may be at least one selected from the group consisting of acrylates including sulfonates. At this time, the acrylate including the sulfonate is, for example, an acrylate including sodium 2-methyl-2-propene-1-sulfonate, an acrylate including sodium aryl sulfonate, 2-propene-1 Acrylates including sulfonates. On the other hand, when the epoxy acrylate monomer containing an epoxy group is copolymerized to the polyester resin among the acrylic monomers, the epoxy ring is dissociated at high temperature to generate an addition polymerization reaction between the epoxy rings and crosslinking to improve the high temperature durability of the polyester main chain. By doing so, there is an advantage that the high temperature stability is increased.

More preferably, the polyester resin of the present invention may include two or more kinds of acrylic monomers, most preferably an alkyl (meth) acrylate monomer and an epoxy (meth) such as glycidyl (meth) acrylate. ) Acrylate monomers may further be included.

In this case, when the acrylic resin is further included in the polyester resin as described above, that is, when the acrylic monomer is further copolymerized with the polyester glycol formed by the reaction of the polybasic acid and the polyol to form the polyester acrylic resin, the poly The weight ratio of the ester glycol and the acrylic monomer may be about 2: 8 to 7: 3, more preferably about 3: 7 to 7: 3. When the weight ratio of the polyester glycol to the acrylic monomer satisfies the above numerical range, properties such as adhesion and solvent resistance of the primer layer to the substrate are excellent, and in particular, the adjustment is performed so that the difference in refractive index between the base film and the primer layer is 0.03 or less. It is possible. When the weight ratio is 2: 8 or less, the coating property of the primer layer may be lowered. More specifically, the refractive index of the primer layer changes in proportion to the weight ratio of the polyester glycol to the acrylic monomer, so that the adjustment can be made to approach the refractive index of the base film described below. As described above, since the polyester contains an aromatic ring and the acrylic resin is composed of aliphatic, the less the content of the polyester, the less the aromatic ring that can interact with the light will have a lower refractive index.

In addition, the manufacturing method of the said polyester resin can employ | adopt any suitable method known in the art. For example, it may be prepared by a method of polycondensation after esterification of a polybasic acid and a polyol, or a method of polycondensation after an esterification reaction of a polybasic anhydride and a polyol, and more specifically, the methods may include (1) polyester A raw material mixing step of mixing a polymerization raw material for the polymerization of to obtain a raw material mixture, (2) an esterification step of esterifying the raw material mixture and (3) a polycondensation to obtain a polyester by polycondensing the esterified raw material mixture It may be achieved including a step of combining.

After preparing a polyester resin, the temperature is lowered to 100 degrees C or less, and the acrylic monomer which reacts with the acid or hydroxy functional group of a polyester is injected like a catalyst, and the terminal of polyester is acrylated. After dispersing this in water with high speed stirring, an initiator may be added to acrylic polymerization by emulsion polymerization, thereby preparing a polyester acrylic resin.

On the other hand, the polyester resin used in the present invention prepared through the above method may include all of the repeating units represented by the following [Formula 1] and [Formula 2].

[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2], R ₁ is substituted or unsubstituted C6-20 aryl, R ₅ is substituted or unsubstituted C1-20 alkyl or C5-20 cycloalkyl, R ₂ and R ₆ are each independently hydrogen, substituted or unsubstituted C1 ~ 20 alkyl, substituted or unsubstituted C6 ~ 20 aryl, or a substituted or unsubstituted C5 ~ 20 cycloalkyl, R _3, R _4, R _7, and R ₈ is each independently hydrogen, substituted or unsubstituted C 1-20 alkyl, substituted or unsubstituted C 6-20 aryl, substituted or unsubstituted C _5-20 cycloalkyl, carboxyl group, hydroxy group or sulfonate group.

In addition, the polyester resin may further include additional components in addition to the above components in a range that does not impair the physical properties of the present invention.

On the other hand, the primer layer containing the polyester resin and the water-dispersible microparticles more specifically, 100 parts by weight of the polyester resin; 1 to 20 parts by weight of water dispersible fine particles; And it can be formed by a primer composition comprising residual water. At this time, the 'residue' means the remaining content except the solid content in the primer composition.

More specifically, the water dispersible fine particles include 1 to 20 parts by weight of water dispersible fine particles with respect to 100 parts by weight of the polyester resin. When the content of the water dispersible fine particles satisfies the above range, it is preferable in terms of work running, winding, slipping and transparency.

The water-dispersible fine particles that can be used in the present invention may use any suitable fine particles, for example inorganic fine particles. Organic fine particles or a combination thereof can be used. Examples of the inorganic fine particles include inorganic oxides such as silica, titania, alumina, zirconia, antimony and the like. Examples of the organic fine particles include silicone resins, fluorine resins, (meth) acrylic resins, crosslinked polyvinyl alcohols, melamine resins, and the like.

Among the water-dispersible fine particles, silica is particularly preferable. This is because silica is more excellent in blocking inhibitory ability, has excellent transparency, does not generate haze, and there is no coloring, and therefore, the influence on the optical properties of the polarizing plate is smaller. In addition, since colloidal silica has good dispersibility and dispersion stability with respect to the primer composition, workability at the time of forming the primer layer is also excellent.

On the other hand, the water-dispersible fine particles have an average diameter (average primary particle diameter) of about 10 to 200 nm, more preferably about 20 to 70 nm. When the average diameter of the water-dispersible microparticles is smaller than 10 nm, the surface energy is increased, so that the dispersion and precipitation of the water-dispersible particles in the primer composition may be inhibited, and the stability of the solution may be inhibited. When the average diameter is larger than 200 nm, the water-dispersible particles may be Dispersion does not occur evenly in the primer composition, and when the particles aggregate, the size is larger than the visible light (400 nm to 800 nm) wavelength, so that light of 400 nm or more is scattered and the haze is increased. By using fine particles having a particle diameter in the above range, irregularities are appropriately formed on the surface of the primer layer, and in particular, the frictional force on the contact surface between the acrylic film and the primer layer and / or the primer layers can be effectively reduced. As a result, the blocking inhibiting ability can be further excellent.

Since the primer composition of the present invention is water-based, the fine particles are preferably blended into an aqueous dispersion. Specifically, when silica is used as the fine particles, it is preferably blended as colloidal silica. As a colloidal silica, the product marketed in the said technical field can be used as it is, For example, Snowtex series of Nissan Chemical Industries, Ltd., AEROSIL series of Air Products, the epostar series of Japan Catalyst, and the soliostar RA series, Ranco LSH series and the like can be used.

On the other hand, the primer layer of the present invention may further include an acrylic compound. In this case, the acrylic compound is preferably included in the blending with the polyester resin when the primer layer is prepared.

The acrylic compound may be an acrylic monomer or an acrylic resin. At this time, the acrylic monomer is not limited thereto, for example, alkyl (meth) acrylate, alkyl acrylate, epoxy (meth) acrylate, hydroxy alkyl acrylate, alkyl (meth) acrylic acid, including a carbonyl group, alkyl It may be at least one selected from the group consisting of acrylates including acrylic acid and sulfonate, and acrylic monomers used in the copolymer of polyester and acrylic may be used.

The acrylic resin may be an acrylic oligomer or a polymer resin prepared from the acrylic monomer.

On the other hand, the added acrylic compound is preferably contained in 10 to 90 parts by weight, more preferably 30 to 70 parts by weight based on 100 parts by weight of the polyester resin. When the content of the acrylic compound in comparison with the polyester resin satisfies the numerical range, since the refractive index difference with the base film can be adjusted to a desired range, the occurrence of rainbow may be reduced. In particular, it can adjust so that the refractive index difference of a base film and a primer layer may be 0.03 or less.

Next, the base film of this invention is demonstrated.

The base film may be a single layer or a structure in which two or more films are stacked, and in the case of a structure in which two or more films are stacked, the laminated films may be made of the same or different materials.

In the optical film of the present invention, the base film preferably has a refractive index of 1.45 to 1.65. More specifically, the acrylic film has a refractive index of about 1.45 to 1.55, and the ester film has a refractive index of about 1.55 to 1.65.

An object of the present invention is to adjust the refractive index of the primer layer so that the difference in refractive index between the base film and the primer layer is 0.03 or less, in order to suppress the rainbow phenomenon, the content of the aromatic carboxylic acid and aliphatic carboxylic acid constituting the polybasic acid as described above By adjusting or by additionally adjusting the weight ratio of the polyester glycol and the acrylic monomer constituting the polyester acrylic resin, the difference in refractive index with the base film can be adjusted to 0.03 or less. That is, when the base film is an acrylic film (about 1.5), the refractive index of the primer layer is adjusted to about 1.47 to 1.53, and when the base film is an ester film (about 1.6), the refractive index of the primer layer is about 1.57 to 1.63 I can regulate it.

The base film is preferably an acrylic film or an ester film, and most preferably an acrylic film. Here, the acryl-based film means a film containing a resin containing an acrylate-based unit and / or a methacrylate-based unit as a main component, and an acrylate as well as a homopolymer resin composed of an acrylate-based unit or a methacrylate-based unit. In addition to the system unit and / or the methacrylate unit, a film containing a copolymer resin copolymerized with other monomer units as a main component and a film formed of a blend resin in which another resin is blended with the acrylic resin as described above are included.

The monomer unit copolymerizable with the acrylic resin may include an aromatic vinyl unit, a 3 to 6 membered heterocyclic unit substituted with a carbonyl group, an acrylic acid unit, a glycidyl unit, and the like. In this case, the aromatic vinyl unit refers to a unit derived from, for example, styrene, alphamethyl styrene, etc., and the 3 to 6 membered heterocyclic unit substituted with the carbonyl group may include, for example, a lactone ring and glutaric anhydride. And a unit derived from glutarimide, maleimide, maleic anhydride and the like.

For example, the acrylic film may be a film including a copolymer including alkyl (meth) acrylate-based units and 3 to 10 membered heterocyclic units substituted with at least one carbonyl group. In this case, the 3 to 10 membered heterocyclic unit substituted with the carbonyl group may be a lactone ring, glutaric anhydride, glutarimide, maleic anhydride, maleimide, or the like.

As another example of the acrylic film, a film containing a blending resin obtained by blending an acrylic resin with an aromatic resin having a carbonate portion in a main chain thereof may be mentioned. At this time, the aromatic resin having a carbonate portion in the main chain may be, for example, polycarbonate resin, phenoxy resin and the like.

The method for producing the acrylic resin film is not particularly limited, and for example, the acrylic resin and other polymers, additives, etc. are sufficiently mixed by any suitable mixing method to prepare a thermoplastic resin composition, and then film-molded to produce the thermoplastic resin composition, Alternatively, the acrylic resin and other polymers, additives, etc. may be prepared in a separate solution and mixed to form a uniform mixed solution, and then film-molded.

The thermoplastic resin composition is prepared by, for example, extrusion kneading the resulting mixture after preblending the film raw material with any suitable mixer such as an omni mixer. In this case, the mixer used for extrusion kneading is not specifically limited, For example, arbitrary appropriate mixers, such as an extruder, such as a single screw extruder and a twin screw extruder, and a pressurized kneader, can be used.

As a method of the said film shaping | molding, arbitrary suitable film shaping | molding methods, such as the solution casting method (solution casting method), the melt extrusion method, the calender method, the compression molding method, are mentioned, for example. Among these film forming methods, a solution cast method (solution casting method) and a melt extrusion method are preferable.

As a solvent used for the said solution casting method (solution casting method), For example, aromatic hydrocarbons, such as benzene, toluene, 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, etc. are mentioned. These solvents may be used independently or may use 2 or more types together.

As an apparatus for performing the said solution casting method (solution casting method), a drum type casting machine, a band type casting machine, a spin coater, etc. are mentioned, for example. Examples of the melt extrusion method include a T-die method and an inflation method. Molding temperature becomes like this. Preferably it is 150-350 degreeC, More preferably, it is 200-300 degreeC.

When forming a film by the said T die method, a T die can be attached to the front-end | tip of a well-known single screw extruder or a twin screw extruder, the film extruded in film shape can be rolled, and a roll-shaped film can be obtained. Under the present circumstances, you may uniaxially stretch by adjusting the temperature of a winding roll suitably and extending | stretching in an extrusion direction. Moreover, simultaneous biaxial stretching, sequential biaxial stretching, etc. can also be performed by extending | stretching a film in the direction perpendicular | vertical to an extrusion direction.

The acrylic film may be any of an unoriented film or a stretched film. In the case of a stretched film, it may be a uniaxial stretched film or a biaxially stretched film, and in the case of a biaxially stretched film, it may be either a simultaneous biaxially stretched film or a successive biaxially stretched film. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved. By mixing another thermoplastic resin, an acryl-type film can suppress an increase of retardation even when extending | stretching, and can maintain optical isotropy.

It is preferable that extending | stretching temperature is a range near the glass transition temperature of the thermoplastic resin composition which is a film raw material, Preferably it is (glass transition temperature -30 degreeC)-(glass transition temperature +100 degreeC), More preferably, it is (glass transition Temperature -20 ° C) to (glass transition temperature + 80 ° C). If the stretching temperature is less than (glass transition temperature -30 ° C), there is a fear that a sufficient stretching ratio may not be obtained. On the contrary, when extending | stretching temperature exceeds (glass transition temperature +100 degreeC), the flow (flow) of a resin composition arises and there exists a possibility of not being able to perform stable extending | stretching.

The draw ratio defined by area ratio becomes like this. Preferably it is 1.1-25 times, More preferably, it is 1.3-10 times. If the draw ratio is less than 1.1 times, there is a fear that it does not lead to the improvement of the toughness accompanying stretching. When a draw ratio exceeds 25 times, there exists a possibility that the effect by raising a draw ratio may not be recognized.

The stretching speed is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min in one direction. If the stretching speed is less than 10% / min, it takes a long time to obtain a sufficient draw ratio, there is a fear that the manufacturing cost increases. When the stretching speed exceeds 20,000% / min, breakage of the stretched film may occur.

The acrylic film may be subjected to heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. The heat treatment conditions are not particularly limited and may employ any suitable conditions known in the art.

On the other hand, the ester film is a film made of polyester, preferably excellent in transparency, mechanical strength, optical isotropy and the like. Moreover, an ester type film is preferable at the point which can be manufactured by the melt-extrusion method which is a film-forming method which can be carried out at low cost instead of the film-forming method by the casting method like a triacetyl cellulose film.

Examples of the polyester of such an ester film include polyethylene terephthalate, polyethylene naphthalate, ethylene glycol-terephthalic acid-isophthalic acid copolymer polyester, ethylene glycol-hexamethylenedimetholol terephthalic acid copolymer polyester, and polyester-based thermoplastics. Known film-forming polyesters, such as an elastomer and a polyarylate, can be used, and polyethylene terephthalate is especially preferable. Moreover, as an ester type film, extending | stretching films, such as uniaxial stretching and biaxial stretching, are more advantageous than transparency of an unstretched film from a viewpoint of transparency and mechanical strength. In the case of a stretched film, in particular, a low optical anisotropy, that is, a good optical isotropy is preferable in terms of not disturbing polarization, and a biaxially stretched film is more preferable in this respect than a uniaxially stretched film.

The ester film can be used as a single layer or a laminate of two or more layers of the same kind or different types of polyester, in addition to the single layer film of the same type of polyester. Well-known additives, such as these, can be added suitably.

On the other hand, the optical film of the present invention can be prepared by coating the primer composition of the present invention on at least one side of the base film as described above to form a primer layer. In this case, the coating may be performed by a method well known in the art, for example, a method of applying and drying the primer composition on a base film using a bar coating method, a gravure coating method, a slot die coating method, or the like. Can be. In this case, the drying may be performed through a convention oven or the like, but is not limited thereto. Preferably, the drying is performed at a temperature of 100 ° C. to 120 ° C. for 1 minute to 5 minutes. The drying temperature is different depending on the coating step, in the case of the finished film can be carried out in the range not exceeding the glass transition temperature (Tg) of the film, and in the case of stretching, the drying is carried out at the stretching temperature simultaneously with the film Is carried out in a range not exceeding the decomposition temperature (Td).

On the other hand, it is preferable that the thickness of the said primer layer formed by the above method is 50 nm-2000 nm, More preferably, it is 100 nm-1500 nm, More preferably, it is 300 nm-1000 nm. If the thickness of the primer layer is less than 50nm, there is a problem that the adhesion is not sufficient, if it exceeds 2000nm there is a problem that the drying is not enough or the water-dispersible fine particles are buried in the primer layer to impart slip properties properly.

Furthermore, if necessary, surface treatment may be performed on at least one surface of the optical film to improve adhesion. The surface treatment method may be at least one selected from the group consisting of alkali treatment, corona treatment, and plasma treatment. have. In particular, when the optical film used for this invention is an acrylic film which does not contain a lactone ring, it is preferable to perform the said surface treatment.

On the other hand, after the primer layer is formed on at least one surface of the base film as described above, a functional coating layer such as a hard coating layer, an anti-reflection layer, etc. may be laminated on the primer layer.

In this case, the functional coating layer may be formed in various compositions according to the function to be given, for example, it may be formed by a composition for forming a functional coating layer containing a binder resin, fine particles, a solvent and the like.

For example, in the present invention, the functional coating layer forming composition may be a binder resin well known in the art, such as acrylic binder resin, urethane-based binder resin or a mixture thereof.

The type of the acrylic binder resin is not particularly limited and may be selected without particular limitation as long as it is known in the art. Examples of the acrylic binder resin may be an acrylate monomer, an acrylate oligomer, a mixture thereof, or the like. In this case, the acrylate monomer or acrylate oligomer preferably comprises at least one or more acrylate functional groups capable of participating in the curing reaction.

The kind of the acrylate monomer and the acrylate oligomer is not particularly limited, and may be used without particular limitation to those commonly used in the art.

In addition, as the acrylate oligomer, urethane acrylate oligomer, epoxy acrylate oligomer, polyester acrylate, polyether acrylate or a mixture thereof may be used. As said acrylate monomer, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hydroxy pentaacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, trimethylene propyl triacrylate, pro Foxylated Glycerol Triacrylate, Trimethyllopropane Ethoxy Triacrylate, 1,6-hexanedioldiacrylate, Propoxylated Glycerol Triacrylate, Tripropylene Glycol Diacrylate, Ethylene Glycol Diacrylate or Mixtures thereof and the like may be preferably used, but are not necessarily limited to these examples.

On the other hand, as the fine particles may be used organic fine particles, inorganic fine particles or a mixture thereof, the content of the fine particles is not limited thereto, but may be about 0.1 to 10 parts by weight based on 100 parts by weight of the binder resin. When the content of the fine particles satisfy the above numerical range, the haze value is sufficiently realized, and there is an advantage in that the coating property is good.

On the other hand, when using a mixture of organic fine particles and inorganic fine particles as the fine particles, the content of the inorganic fine particles is preferably within the range of 20 parts by weight to 80 parts by weight with respect to 100 parts by weight of the organic fine particles. When the amount of the inorganic fine particles satisfies the numerical range, there is an advantage in that the scratch resistance is excellent and the coating surface is good.

In addition, the inorganic fine particles may be used as a single selected from silica, silicon particles, aluminum hydroxide, magnesium hydroxide, alumina, zirconia, titania, or two or more thereof, but are not necessarily limited thereto.

The organic fine particles are polystyrene, polymethyl methacrylate, polymethyl acrylate, polyacrylate, polyacrylate-co-styrene, polymethylacrylate-co-styrene, polymethylmethacrylate-co-styrene, polycarbonate , Polyvinyl chloride, polybutylene terephthalate, polyethylene terephthalate, polyamide, polyimide, polysulfone, polyphenylene oxide, polyacetal, epoxy resin, phenol resin, silicone resin, melamine resin, benzoguamine, At least one selected from polydivinylbenzene, polydivinylbenzene-co-styrene, polydivinylbenzene-co-acrylate, polydiallylphthalate and triallyl isocyanurate polymer or two or more copolymers thereof ( copolymer) can be used.

On the other hand, the solvent is not limited thereto, but may be included in an amount of about 50 parts by weight to about 500 parts by weight based on 100 parts by weight of the binder resin. When the content of the solvent satisfies the numerical range, the coating property of the functional coating layer is excellent, the film strength of the coating film is excellent, and it is easy to prepare a thick film.

The kind of solvent usable in the present invention is not particularly limited, and an organic solvent may be used in general. For example, at least _{one selected} from the group consisting of C ₁ to C ₆ lower alcohols, acetates, ketones, cellosolves, dimethylformamide, tetrahydrofuran, propylene glycol monomethyl ether, toluene and xylene This can be used.

Here, the lower alcohols are one selected from methanol, ethanol, isopropyl alcohol, butyl alcohol, isobutyl alcohol and diacetone alcohol, and the acetates are methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate. And cellosolve acetate, and the ketones may be one selected from methyl ethyltone, methyl isobutyl ketone, acetylacetone, and acetone, but are not limited thereto.

On the other hand, the composition for forming a functional coating layer according to the present invention, if necessary, may further include a UV curing initiator added for the purpose of curing through UV irradiation. The UV curing initiator is selected from among 1-hydroxy cyclohexylphenyl ketone, benzyl dimethyl ketal, hydroxydimethylacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin butyl ether. It may be one single or a mixture of two or more selected, but is not limited thereto.

The UV curing initiator is preferably added in 0.1 parts by weight to 10 parts by weight with respect to 100 parts by weight of the binder resin. When the content of the UV curing initiator satisfies the numerical range, sufficient curing may occur and the film strength of the film may be improved.

In addition, the composition for forming a functional coating layer according to the present invention may further include one or more additives selected from a leveling agent, a wetting agent, and an antifoaming agent. The additive may be added in an amount of 0.01 parts by weight to 10 parts by weight based on 100 parts by weight of the binder resin.

In the present invention, the thickness of the functional coating layer is not limited thereto, but may be about 1 μm to 20 μm, and preferably about 1 μm to 4 μm. When the thickness of the functional coating layer satisfies the numerical range, it is possible to prevent the occurrence of cracks, while implementing sufficient functionality.

Meanwhile, the functional coating layer may be formed by applying a composition for forming a functional coating layer on a primer layer, followed by drying and / or curing, wherein the coating is well known in the art, for example, It can be made through wet coating such as roll coating, bar coating, spray coating, dip coating and spin coating. However, the coating method is not limited thereto, and various other coating methods used in the art may be used.

On the other hand, the drying and / or curing may be made by a method of irradiating heat and / or light to the functional coating layer composition composition applied on the primer layer, may proceed sequentially drying step and curing step, or may proceed simultaneously have. However, in consideration of process convenience and the like, the curing step is more preferably performed through a method of irradiating light such as UV.

On the other hand, the curing conditions may be appropriately adjusted according to the blending ratio or components of the composition for forming a functional coating layer, for example, in the case of electron beam or ultraviolet curing the irradiation amount of 200 mJ / ㎠ to 1,000 mJ / ㎠ for 1 second To about 10 minutes. In the electron beam or ultraviolet curing, when the curing time satisfies the numerical range, the binder resin may be sufficiently cured, and thus, mechanical properties such as wear resistance may be excellent, and durability of the transparent substrate layer may be improved.

The optical film of the present invention as described above is disposed on at least one side of the polarizer can be usefully used as a polarizer protective film. That is, the polarizing plate of the present invention is a polarizer; It may be configured to include the optical film of the present invention disposed on at least one surface of the polarizer.

More specifically, the polarizing plate of the present invention may be composed of a polarizer, a protective film disposed on at least one surface of the polarizer, an adhesive layer interposed between the polarizer and the protective film, wherein the protective film is a base film and the It may be an optical film of the present invention comprising a primer layer containing a polyester resin and water-dispersible fine particles on at least one side of the base film. In this case, specific contents related to the primer layer and the optical film are the same as described above.

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

Furthermore, the optical film or the polarizing plate of the present invention can be usefully applied to various image display devices such as liquid crystal display devices.

Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples are provided to aid the understanding of the present invention and thus do not limit the present invention.

Preparation Example 1 Preparation of Composition for Forming Functional Coating Layer

18 g of pentaerythritol triacrylate as a binder resin; 18 g dipentaerythritol pentaacrylate; 250 g of a hollow silica particle dispersion (manufacturer: catalyzed sand, a solution of hollow silica particles having a number average particle diameter of 50 to 60 nm dispersed in a solid content of 20% by weight) as organic fine particles; 10 g of a polyethersiloxane-based polymer (manufacturer: EVONIK, product name: TEGO Glide 450); And 4 g of a photopolymerization initiator (manufacturer: CIBA, trade name: Irgacure 184) were mixed and stirred for 30 minutes. Here, methyl isobutyl ketone (MIBK) was diluted to a solid content of 3% by weight to prepare a low reflection coating layer composition.

Preparation Example 2-Preparation of Polyester Resin

(1) Polyester resin A synthesis example

The 500 ml round bottom flask was replaced with nitrogen and ethylene glycol (EG), diethylene glycol (DEG), sodiumsulfonyl isophthalic acid (SSIPA), isophthalic acid (IPA), cyclohexanedi, as indicated in Table 1 below. Carboxylic acid (CHDA) was added at a molar ratio of 0.5: 0.5: 0.1: 0.2: 0.7 and the esterification reaction was carried out at 200 ° C. for 2 hours to drain the theoretical amount of water. Tetramethyl titanate, antimony acetate, thibutyltin oxide as a catalyst, trimethyl phosphate as a stabilizer, and water continued to flow out, followed by a polycondensation reaction for 150 minutes under a reduced pressure of 2.5 Torr or less at 255 ° C. A was prepared.

(2) Polyester resin B synthesis example

A 500 ml round bottom flask was replaced with nitrogen and ethylene glycol (EG), diethylene glycol (DEG), sodiumsulfonyl isophthalic acid (SSIPA), isophthalic acid (IPA), adipic acid (as shown in Table 1 below). AA) was added at a molar ratio of 0.5: 0.5: 0.1: 0.4: 0.5 and the esterification reaction was carried out at 200 ° C. for 2 hours to drain the theoretical amount of water. Tetramethyl titanate, antimony acetate, thibutyltin oxide as a catalyst, trimethyl phosphate as a stabilizer, and water continued to flow out, followed by a polycondensation reaction for 150 minutes under a reduced pressure of 2.5 Torr or less at 255 ° C. B was prepared.

(3) Polyester acrylic resin C synthesis example

The 500 ml round bottom flask was replaced with nitrogen and ethylene glycol (EG), sodium sulfonyl isophthalic acid (SSIPA), isophthalic acid (IPA), adipic acid (AA) as indicated in Table 1 below 1: 0.1: The molar ratio of 0.6: 0.3 was added and the esterification reaction was carried out at 200 ° C. for 2 hours to allow the theoretical amount of water to flow out. Tetramethyl titanate, antimony acetate, thibutyltin oxide as a catalyst, trimethyl phosphate as a stabilizer, and water continued to flow out, followed by a polycondensation reaction for 150 minutes under a reduced pressure of 2.5 Torr or less at 255 ° C. B was prepared. Then, glycidyl (meth) acrylate and methyl (meth) acrylate were added at a weight ratio of 2: 1, cooled, stirred at high speed in water, a reactant and a thermal initiator were added, and the temperature was raised to 80 ° C. for 2 hours. While polyester acrylic resin C was prepared. The weight ratio of polyester and acryl is 5: 5.

(4) Polyester Acrylic Resin D Synthesis Example

The 500 ml round bottom flask was replaced with nitrogen and ethylene glycol (EG), diethylene glycol (DEG), sodiumsulfonyl isophthalic acid (SSIPA), isophthalic acid (IPA) and adipic acid (as shown in Table 1 below). AA) was added at a molar ratio of 0.5: 0.5: 0.1: 0.1: 0.8 and the esterification reaction was carried out at 200 ° C. for 2 hours to drain the theoretical amount of water. Tetramethyl titanate, antimony acetate, and thibutyltin oxide were added as a catalyst, and trimethyl phosphate was added as a stabilizer, and water was continuously distilled out, followed by a condensation polymerization reaction under a reduced pressure of 2.5 Torr or less for 50 minutes. Then, glycidyl (meth) acrylate and methyl (meth) acrylate were added at a weight ratio of 2: 1, cooled, stirred at high speed in water, a reactant and a thermal initiator were added, and the temperature was raised to 80 ° C. for 2 hours. While polyester acrylic resin C was prepared. The weight ratio of polyester and acryl is 5: 5.

(5) Polyester Acrylic Resin E

The 500 ml round bottom flask was replaced with nitrogen and ethylene glycol (EG), sodium sulfonyl isophthalic acid (SSIPA), isophthalic acid (IPA), cyclohexanedicarboxylic acid (CHDA) as shown in Table 1 below 1: The molar ratio of 0.1: 0.4: 0.5 was added and the esterification reaction was carried out at 200 ° C. for 2 hours to allow the theoretical amount of water to flow out. Tetramethyl titanate, antimony acetate, thibutyltin oxide as a catalyst, trimethyl phosphate as a stabilizer were added, and water was continued to flow out. B was prepared. Then, glycidyl (meth) acrylate and methyl (meth) acrylate were added at a weight ratio of 2: 1, cooled, stirred at high speed in water, a reactant and a thermal initiator were added, and the temperature was raised to 80 ° C. for 2 hours. While polyester acrylic resin E was prepared. The weight ratio of polyester and acrylic is 6: 4.

Table 1

division	Suzy	Composition (molar ratio)						PES: Acryl (weight ratio)
		Polyol		Polybasic acid
		EG	DEG	ISSPA	IPA	CHDA	AA
A Synthesis Example	Polyester	0.5	0.5	0.1	0.2	0.7	-	-
B synthesis example	Polyester	One	-	0.1	0.4	-	0.5	-
C synthesis example	Polyester acrylic	One	-	0.1	0.6	-	0.3	5: 5
D Synthesis Example	Polyester acrylic	0.5	0.5	0.1	0.1	-	0.8	5: 5
E Synthesis Example	Polyester acrylic	One	-	0.1	0.4	0.5	-	6: 4

Example 1

After preparing a primer composition by mixing 40 parts by weight of the polyester resin A prepared as described above, 3 parts by weight of silica and 57 parts by weight of water, the primer composition was coated with # 7 bar on one surface of the corona-treated acrylic film, The film uniaxially stretched in the MD direction at 135 ° C. was uniaxially stretched in the TD direction to prepare an acrylic film having a primer layer formed at a thickness of 600 nm. The surface of the film was corona-treated on condition of 50 W / m <^2> / min.

After applying the composition for forming the functional coating layer prepared in Preparation Example 1 on the surface of the film of the prepared film using a bar coating so that the dry thickness is 4㎛ using a UV of 280mJ / cm ² It irradiated and hardened and the film in which the functional coating layer was formed was obtained.

Example 2

An acrylic film having a functional coating layer was prepared in the same manner as in Example 1 except that the primer composition was prepared using 40 parts by weight of polyester acrylic resin B instead of 40 parts by weight of polyester resin A.

Example 3

An acrylic film having a functional coating layer was prepared in the same manner as in Example 1 except that the primer composition was prepared using 40 parts by weight of polyester acrylic resin C instead of 40 parts by weight of polyester resin A.

Example 4

An acrylic film having a functional coating layer was prepared in the same manner as in Example 1 except that the primer composition was prepared using 40 parts by weight of polyester acrylic resin D instead of 40 parts by weight of polyester resin A.

Example 5

An acrylic film having a functional coating layer was prepared in the same manner as in Example 1 except that the primer composition was prepared using 40 parts by weight of polyester acrylic resin E instead of 40 parts by weight of polyester resin A.

Example 6

Except for blending 8 parts by weight of polyester resin A (30% solids), 30.5 parts by weight of acrylic resin MWX-002 (31.5% by Koh, YK, TAKAMAYSU), 3 parts by weight of silica and 58.5 parts by weight of water to prepare a primer composition. An acrylic film having a functional coating layer was prepared in the same manner as in Example 1.

Comparative Example 1

An acrylic film having a functional coating layer was prepared in the same manner as in Example 1, except that 40 parts by weight of polyepoxy resin Modepics 502F (ARAKAWA) was used instead of 40 parts by weight of polyester resin A.

Comparative Example 2

The same as in Example 1, except that the primer composition was prepared using 80 parts by weight of polyester acrylic resin HR0038 (containing 15% solids, 100% aromatic carboxylic acid as polybasic acid) instead of 40 parts by weight of polyester resin A An acrylic film with a functional coating layer was prepared by the method.

Comparative Example 3

Except that 40 parts by weight of polyester resin A instead of 40 parts by weight of polyester acrylic resin A-645GH (TAKAMATSU, solid content 30%, containing 100% aromatic carboxylic acid as a polybasic acid) to prepare a primer composition, An acrylic film with a functional coating layer was prepared in the same manner as in Example 1.

Experimental Example 1-Method for measuring the difference in refractive index between the base film and the primer layer

After coating the primer layer on the glass plate with 4㎛, the refractive index is measured by using the Prism coupler. The substrate changes modes and measures the refractive indices of the substrate films, respectively, and calculates the difference. At this time, the refractive index of the acrylic film which is a base film is 1.500, The measurement result was shown in [Table 2].

Experimental Example 2-Rainbow Existence

After the manufacture of the optical film according to the Example and Comparative Example, the hard coating treatment on one side of the other side was blackened to determine whether the rainbow occurs with the naked eye. Visual evaluation was performed under a three-wavelength lamp in the dark room. The measurement results are shown in [Table 2]. At this time, the evaluation criteria are as follows.

Top: Rainbow is not seen and uniform color

Medium: Rainbow phenomenon is soft and uniform color.

Bottom: Strong rainbow, strong color

Experimental Example 3-Method for measuring the adhesion of the functional coating layer.

Adhesion was evaluated to the extent that the functional coating layer fell off by attaching a tape after cutting the sheath at 1 mm intervals in the area of 10 × 10 in the functional coating layer. When the falling area is 0 to 20% or less, it is OK. When the falling area is more than 20%, NG was evaluated. The measurement results are as described in the following [Table 2].

TABLE 2

division	Primer refractive index	Refractive index difference	Rainbow	Adhesion
Example 1	1.520	0.020	Ha	OK
Example 2	1.525	0.025	Ha	OK
Example 3	1.515	0.015	Ha	OK
Example 4	1.511	0.11	Ha	OK
Example 5	1.523	0.023	Ha	OK
Example 6	1.520	0.020	Ha	OK
Comparative Example 1	1.560	0.06	River	NG
Comparative Example 2	1.627	0.127	River	OK
Comparative Example 3	1.563	0.036	River	OK

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations can be made without departing from the technical spirit of the present invention described in the claims. It will be obvious to those who have ordinary knowledge of.

Claims (13)

1. Base film; And

   In at least one surface of the base film containing a polyester resin and water-dispersible fine particles, the optical film comprising a primer layer having a refractive index difference of 0.03 or less,

   The polyester resin is an optical film comprising a polyester glycol formed by the reaction of a polyol and a polybasic acid containing an aromatic carboxylic acid compound and an aliphatic carboxylic acid compound in a molar ratio of 1: 9 to 9: 1.
2. The method of claim 1,

   The molar ratio of the aromatic carboxylic acid compound and aliphatic carboxylic acid compound is 2: 8 to 8: 2.
3. The method of claim 1,

   The aromatic carboxylic acid compounds include ortho-phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid and tetrahydrophthalic acid. At least one optical film selected from the group consisting of.
4. The method of claim 1,

   The aliphatic carboxylic acid compound may be an aliphatic carboxylic acid such as oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suveric acid, azelaic acid, sebacic acid, linoleic acid, maleic acid, fumaric acid, mesaconic acid, or itaconic acid. Carboxylic acid; Optical film which is at least 1 sort (s) chosen from the group which consists of cyclic aliphatic carboxylic acid, such as hexahydrophthalic acid, tetrahydrophthalic acid, 1, 3- cyclohexanedicarboxylic acid, and 1, 4- cyclohexanedicarboxylic acid.
5. The method of claim 1,

   The polyester resin is an optical film comprising a polyester acrylic resin formed by further copolymerizing an acrylic monomer to a polyester glycol formed by the reaction of a polybasic acid and a polyol.
6. The method of claim 5,

   The polyester glycol and an acrylic monomer are copolymerized in a weight ratio of 2: 8 to 7: 3.
7. The method of claim 1,

   The primer layer further comprises an acrylic compound.
8. The method of claim 1,

   The base film has an index of refraction of 1.45 to 1.65.
9. The method of claim 1,

   The base film is an optical film that is an acrylic film.
10. The method of claim 1,

    Optical film laminated a functional coating layer on the primer layer.
11. The method of claim 1,

    The said optical film is an optical film which is a protective film for polarizing plates.
12. Polarizer; And

    Claim 1 to 11 of the polarizing plate comprising the optical film of any one of claims 1 to 11 of the polarizer.
13. An image display device comprising the polarizing plate of claim 12.