KR20200011296A - Resin composition for polarizer protecting film, polarizer protecting film, and polarizer film using the same - Google Patents

Abstract

The present invention relates to a resin composition for a polarizer protective film, comprising: a crosslinking agent compound capable of making a crosslinking reaction with a water-dispersible binder resin having a silane-based functional group coupled to a branched chain terminal; and a thermal acid generator capable of inducing a crosslinking reaction. The present invention also relates to a polarizer protective film and a polarizing plate using the resin composition.

Description

Resin composition for polarizer protective film, polarizer protective film and polarizing plate using same {RESIN COMPOSITION FOR POLARIZER PROTECTING FILM, POLARIZER PROTECTING FILM, AND POLARIZER FILM USING THE SAME}

The present invention relates to a resin composition for a polarizer protective film that can exhibit excellent physical and optical properties and to prevent damage to the lower polarizing plate, and a polarizer protective film and a polarizing plate using the same.

Liquid crystal display (LCD) is one of the most widely used flat panel display. In general, a liquid crystal display device has a structure in which a liquid crystal layer is enclosed between a TFT (Thin Film Transistor) array substrate and a color filter substrate. When an electric field is applied to the electrodes on the array substrate and the color filter substrate, the arrangement of the liquid crystal molecules of the liquid crystal layer enclosed therebetween is changed, and the image is displayed using the array.

In the liquid crystal display device, since the light emitted from the light source passes through the light guide plate and the diffusion sheet, the luminance decreases, and thus the prism sheet is usually included in order to collect the light and raise the luminance. It is provided at the bottom. However, as the display is enlarged, sagging of the lower polarizing plate occurs, and damage occurs such that the lower polarizing plate is ground by the uneven structure of the prism sheet in contact with the lower polarizing plate. In order to solve this problem, a method of coating a hard coat layer on the protective film of the lower polarizer has been proposed, but there is a problem of an increase in process cost.

In accordance with such a necessity, there is still a need for development of a method for securing productivity and preventing price damage in the lower polarizing plate and increase of haze by the prism sheet while achieving price competitiveness in mass production.

The present invention relates to a resin composition for polarizer protective film that can exhibit excellent physical and optical properties and can prevent damage to the lower polarizing plate.

In addition, the present invention is to provide a polarizer protective film using the resin composition for polarizer protective film.

In addition, the present invention is to provide a polarizing plate using the polarizer protective film.

In order to solve the above problems, in the present specification, the water-dispersive binder resin is bonded to the functional group represented by the formula (1) to the branch chain terminal; A crosslinking agent compound represented by Formula 2; And it provides a resin composition for polarizer protective film comprising a thermal acid generator.

[Formula 1]

In Formula 1, at least one of R ₁ to R ₃ is one of a hydroxy group or an alkoxy group having 1 to 20 carbon atoms, the rest is one of hydrogen or an alkyl group having 1 to 20 carbon atoms,

[Formula 2]

In Formula 2, R ₄ , R ₆ , and R ₈ are each independently alkoxyalkyl group having 2 to 20 carbon atoms, and R ₅ , R ₇ , R ₉ are each independently hydrogen or hydroxyalkyl group having 1 to 20 carbon atoms. .

In the present specification, a polarizer protective film including a water-dispersed binder resin crosslinked through a crosslinking group represented by Formula 3 is provided.

[Formula 3]

In Formula 3, R ₁₁ , R ₁₃ , R ₁₅ are each independently an alkylene group having 1 to 10 carbon atoms, and R ₁₂ , R ₁₄ , R ₁₆ are each independently hydrogen, a hydroxyalkyl group having 1 to 20 carbon atoms, or One of the divalent functional groups represented by the following formula (4), R ₁₇ to R ₂₂ are each independently hydrogen, a hydroxy group, an alkyl group of 1 to 20 carbon atoms, or an alkoxy group of 1 to 20 carbon atoms,

[Formula 4]

In Formula 4, R ₂₃ is an alkylene group having 1 to 10 carbon atoms, and R ₂₄ to R ₂₅ are each independently hydrogen, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms.

In the present specification, the polarizer; Adhesive layer; And it provides a polarizing plate comprising the polarizer protective film described above.

Hereinafter, a resin composition for a polarizer protective film according to a specific embodiment of the present invention, a polarizer protective film and a polarizing plate using the same will be described in more detail.

Unless otherwise specified herein, the following terms may be defined as follows.

In the present specification, when a part "includes" a certain component, it means that it may further include other components, without excluding other components unless specifically stated otherwise.

In the present invention, terms such as first and second are used to describe various components, which terms are used only for the purpose of distinguishing one component from other components.

In the present specification, examples of the substituents are described below, but are not limited thereto.

In the present specification, the term "substituted" means that another functional group is bonded to the hydrogen atom in the compound, and the position to be substituted is not limited to a position where the hydrogen atom is substituted, that is, a position where a substituent may be substituted, and when two or more are substituted , Two or more substituents may be the same or different from each other.

As used herein, the term "substituted or unsubstituted" is deuterium; Halogen group; Cyano group; Nitro group; Hydroxyl group; Carbonyl group; Ester group; Imide group; Amide group; Primary amino group; Carboxyl groups; Sulfonic acid groups; Sulfonamide groups; Phosphine oxide groups; An alkoxy group; Aryloxy group; Alkyl thioxy group; Arylthioxy group; Alkyl sulfoxy groups; Aryl sulfoxy group; Silyl groups; Boron group; Alkyl groups; Cycloalkyl group; Alkenyl groups; Aryl group; Aralkyl group; Ar alkenyl group; Alkylaryl group; Alkoxy silyl alkyl group; Aryl phosphine group; Or substituted or unsubstituted with one or more substituents selected from the group consisting of heterocyclic groups including one or more of N, O, and S atoms, or two or more substituents connected to the substituents exemplified above. . For example, "a substituent to which two or more substituents are linked" may be a biphenyl group. That is, the biphenyl group may be an aryl group or may be interpreted as a substituent to which two phenyl groups are linked.

, 또는

는 다른 치환기에 연결되는 결합을 의미한다. In this specification,

, or

Means a bond connected to another substituent.

In the present specification, the alkyl group is a monovalent functional group derived from alkane, and may be linear or branched, and the carbon number of the linear alkyl group is not particularly limited, but is preferably 1 to 20 or 1 to 10. In addition, the branched alkyl group has 3 to 20, or 3 to 10 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n -Pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl , n-heptyl, 1-methylhexyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl- Propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, 2,6-dimethylheptan-4-yl and the like, but is not limited thereto. The alkyl group may be substituted or unsubstituted.

In the present specification, the alkylene group is a divalent functional group derived from an alkane, and the description of the aforementioned alkyl group may be applied except that these are divalent functional groups. For example, it may be a methylene group, an ethylene group, a propylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, a pentylene group, a hexylene group, or the like as a straight chain or branched type. The alkylene group may be substituted or unsubstituted.

In the present specification, the alkoxy group is a functional group in which the aforementioned alkyl group is bonded to one end of the ether group (-O-), and these are applicable to the description of the aforementioned alkyl group except that the functional group is bonded to the ether group (-O-). Can be. For example, it may be straight, branched or cyclic. Although carbon number of an alkoxy group is not specifically limited, It is preferable that it is C1-C20. Specifically methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, iso Pentyloxy, n-hexyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, cycloheptoxy, benzyloxy, p-methylbenzyl Oxy and the like, but are not limited thereto.

In the present specification, the alkoxyalkyl group is a functional group in which at least one hydrogen contained in the alkyl group is substituted with an alkoxy group, and the description of the alkyl group and the alkoxy group is as described above. Although carbon number of the said alkoxyalkyl group is not specifically limited, It is preferable that it is C2-C20. Examples of the alkoxyalkyl group include, but are not limited to, methoxymethyl, ethoxymethyl, methoxyethyl, ethoxyethyl, and the like.

In the present specification, the hydroxyalkyl group is a functional group in which at least one hydrogen contained in the alkyl group is substituted with a hydroxy group, and the description of the alkyl group is as described above. Although carbon number of the said hydroxyalkyl group is not specifically limited, It is preferable that it is C1-C20. Examples of the hydroxyalkyl group include, but are not limited to, hydroxymethyl, hydroxyethyl, and the like.

In this specification, a weight average molecular weight means the weight average molecular weight of polystyrene conversion measured by the GPC method. In the process of measuring the weight average molecular weight of polystyrene conversion measured by the GPC method, it is possible to use a detector and an analytical column, such as a conventionally known analytical device, a differential index detector, and the like. Conditions, solvents and flow rates can be applied. As specific examples of the measurement conditions, using a Waters PL-GPC220 instrument using a Polymer Laboratories PLgel MIX-B 300 mm length column, the evaluation temperature is 160 ° C. and 1,2,4-trichlorobenzene is used as the solvent. The flow rate is 1 mL / min, the sample is prepared at a concentration of 10 mg / 10 mL, then supplied in an amount of 200 μL, and the value of Mw can be determined using a calibration curve formed using a polystyrene standard. As for the molecular weight of the polystyrene standard, nine species of 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000 were used.

In the present invention, the term 'top surface' refers to a surface that is disposed to face the viewer when the polarizer is mounted on a device such as a liquid crystal display. And, 'top' means the direction toward the viewer when the polarizer is mounted on the device. Conversely, 'bottom' or 'bottom' refers to a face or direction disposed so as to face away from the viewer when the polarizer is mounted to the device.

Hereinafter, the present invention will be described in more detail.

I. Resin composition for polarizer protective film

According to one embodiment of the invention, the branched end of the water-dispersive binder resin bonded to the functional group represented by the formula (1); A crosslinking agent compound represented by Formula 2; And a resin composition for polarizer protective film comprising a thermal acid generator may be provided.

The polarizer exhibits the property of extracting only the light vibrating in one direction from the incident light while vibrating in various directions, and the polarizer protective film of the present invention is used for protecting the polarizer from the outside, and at least On one side, it is preferably used as a protective film for both sides of the polarizer.

Conventionally, a triacetyl cellulose (TAC) film is used as a polarizer protective film because of its excellent optical properties. However, since the TAC film has a weak surface hardness and is vulnerable to humidity, in recent years, polyester films, polyacrylate films, and the like have been used instead of TAC films, and in particular, in order to develop an optical film having excellent mechanical properties, a drawing process is required. The film produced is used a lot.

On the other hand, by using an acrylic film as a polarizer protective film, the adhesive strength is insufficient only when bonding with a polarizer, a functional coating layer is introduced to the acrylic film adhered to the polarizer to compensate for this. However, in the case of the stretched film, when the polymer is rearranged in the stretching process to further form a primer layer or the like on the stretched film, adhesion to the stretched film serving as the substrate is reduced.

In addition, there is still a problem that the adhesive strength is reduced when the polarizer is exposed to high temperature and high humidity environment for a long time. In particular, the primer layer is often formed using an aqueous dispersion resin due to environmentally friendly reasons. In this case, the hydrophilic group in the aqueous dispersion resin is more vulnerable to a high temperature and high humidity environment.

The present invention solves this problem, according to an embodiment of the present invention, to provide a polarizer protective film excellent in durability and mechanical properties even in high temperature and high humidity environment with high adhesion to the acrylic-based stretch film and the polarizer as the substrate. Can be.

(1) water dispersion binder resin

The resin composition for polarizer protective film of the embodiment may include a water dispersion binder resin. The water-dispersible resin is included as a main component of the resin composition for polarizer protective film in order to ensure basic adhesion between the polarizer protective film and the polarizer of the present invention.

The water-dispersion resin may be a polymer resin having water dispersibility, and may be used without limitation as long as the minimum film-forming temperature (MFFT) is lower than the stretching temperature in the stretching step described later. For example, it may include a water-dispersed polyurethane-based resin, a water-dispersed acrylic resin, a water-dispersed polyester-based resin or a combination thereof.

The water-dispersible resin forms a crosslinked structure by a crosslinking reaction with a crosslinking agent, which will be described later, and by this crosslinking structure, the water resistance adhesiveness and mechanical properties of the polarizer protective film of the present invention may be further improved.

The water dispersion binder resin may be contained in 50% by weight to 99.5% by weight, or 60% by weight to 99% by weight, or 70% by weight to 98.5% by weight based on the weight of the solid content contained in the resin composition for polarizer protective film. .

The water dispersion binder resin may be bonded to the functional group represented by the formula (1) to the branched ends. A chain growing through a polymerization reaction in the synthesis of the water-dispersive binder resin is called a main chain, and a chain extending in a branch shape from the main chain is called a branched chain or a side chain.

The water dispersion binder resin may contain a hydrophilic functional group represented by Chemical Formula 1 at a branched chain terminal, and may not only have water dispersing ability, but may also undergo a crosslinking reaction with a crosslinking agent described below. .

Specifically, in Chemical Formula 1, at least one of R ₁ to R ₃ is one of a hydroxyl group or an alkoxy group having 1 to 20 carbon atoms, and the hydroxyl group or the alkoxy group may implement a crosslinking reaction together with the water dispersing ability. More specifically, in Formula 1, two of R ₁ to R _{3 may} each be a hydroxy group or an alkoxy group having 1 to 20 carbon atoms, or all _three of R ₁ to R ₃ may be a hydroxyl group or an alkoxy group having 1 to 20 carbon atoms. .

As such, as Formula 1 contains at least two hydroxyl groups or alkoxy groups, the crosslinking density with the crosslinking agent is increased, thereby improving mechanical properties.

On the other hand, with respect to the aqueous dispersion binder resin, the content of the functional group represented by the formula (1) may be 6 mol% to 20 mol%. If the content of the functional group represented by the formula (1) is too small may not be sufficient crosslinking density for the water resistance, if the content of the functional group represented by the formula (1) is too high the crosslinking density is too high may not stretch the film, condensation There is a fear of generating haze at the time of crosslinking. From this point of view, the content of the functional group represented by Formula 1 is preferably in the above range.

(2) crosslinking agent compound

The resin composition for polarizer protective film of the embodiment may include a crosslinking agent compound represented by Chemical Formula 2 in addition to the above-described water dispersion binder resin. The crosslinker compound forms a crosslinked structure by crosslinking with a functional group of Formula 1 included in the above-described water dispersion binder resin, thereby improving the water resistance and mechanical strength of the polarizer protective film of the present invention.

Specifically, in Formula 2, R ₄ , R ₆ , R ₈ are each independently alkoxyalkyl group having 2 to 20 carbon atoms, R ₅ , R ₇ , R ₉ are each independently hydrogen or hydroxy having 1 to 20 carbon atoms One of the alkyl groups.

In Formula 2, a C 2-20 alkoxyalkyl group independently positioned at R ₄ , R ₆ , and R ₈ may be combined with a hydroxyl group or alkoxy group having 1 to 20 carbon atoms introduced into the structure of Formula 1 of the water-dispersed binder resin. It is possible to form a crosslinked structure through the reaction.

As such, the cross-linking agent compounds R _4, R _6, and progress a crosslinking reaction at various positions of R _8, R _4, R _6, form a three dimensional cross-linked structure of the forms through the position of R ₈ of formula (2) It is possible to form a high crosslinking density after crosslinking, thereby making it difficult to penetrate moisture into the polarizer protective film.

On the other hand, in Formula 2, R ₅ , R ₇ , R ₉ may be all hydrogen. Alternatively, in Formula 2, R ₅ , R ₇ , R ₉ may be all a hydroxyalkyl group having 1 to 20 carbon atoms. In Formula 2, even when R ₅ , R ₇ , and R ₉ are all hydroxyalkyl groups having 1 to 20 carbon atoms, the alkoxyalkyl group having 2 to 20 carbon atoms located at R ₄ , R ₆ , and R ₈ is the hydroxyalkyl group. As the reactivity is more excellent, the crosslinking reaction proceeds preferentially. If necessary, after all the C 2-20 alkoxyalkyl groups located at R ₄ , R ₆ , and R ₈ crosslink, the C 1-20 hydroxyalkyl groups located at R ₅ , R ₇ , R ₉ are also crosslinked. The reaction can proceed.

The crosslinking agent compound represented by Formula 2 is 2% by weight to 30% by weight, or 2% by weight to 25% by weight, or 3% by weight to 20, based on the weight of the water-dispersed binder resin contained in the resin composition for polarizer protective film. It may be contained in weight percent. The weight% of the crosslinking agent compound represented by Formula 2 may be obtained through Equation 1 below.

[Equation 1]

(Solid content of the crosslinking agent compound represented by Formula 2 contained in the resin composition for polarizer protective films) / (Solid content of water-dispersed binder resin contained in the resin composition for polarizer protective films) * 100.

That is, based on 100 parts by weight of the water-dispersible binder resin, 2 parts by weight to 30 parts by weight, or 2 parts by weight to 25 parts by weight, or 3 parts by weight to 20 parts by weight of the crosslinking agent compound represented by Chemical Formula 2 may be contained. .

When the content of the crosslinking agent compound is excessively high, as the degree of crosslinking of the polarizer protective film is excessively increased, flexibility may be difficult to stretch, and the coating property to the substrate may be increased due to an increase in the viscosity of the composition or a gelation reaction in the composition. This can be reduced.

On the other hand, if the content of the crosslinker compound is too small, it may be difficult to fully implement the mechanical strength improvement effect by increasing the degree of crosslinking of the polarizer protective film.

The weight average molecular weight of the crosslinker compound may be 200 g / mol to 400 g / mol, or 220 g / mol to 380 g / mol, or 250 g / mol to 350 g / mol. If the weight average molecular weight of the crosslinker compound is too large, it may be difficult to dissolve. If the weight average molecular weight of the crosslinker compound is too small, it may be vaporized at a high temperature for curing, and in this respect, the weight average molecular weight of the crosslinker compound may be in the above range. Is preferably.

(3) thermal acid generator

The resin composition for polarizer protective film of the embodiment may include a thermal acid generator. The thermal acid generator generates hydrogen ions (H ⁺ ) by heat, thereby inducing a crosslinking reaction between the water-dispersible binder resin and the crosslinking agent.

In particular, since the thermal acid generator can give an acid as a crosslinking reaction catalyst only when the heat treatment is performed at a high temperature of 100 ° C. or higher, the crosslinking reaction is suppressed in the resin composition for polarizer protective film of the embodiment, which is maintained at a temperature lower than 100 ° C. Reduced solubility in the composition due to unnecessary crosslinking can be minimized.

On the other hand, the resin composition for a polarizer protective film of the embodiment, as will be described later, since the polarizer protective film can be manufactured through a thermosetting process at a high temperature of 100 ℃ or more, the acid generated from the thermal acid generator during the thermosetting process By the cross-linking reaction of the water dispersion binder resin and the crosslinking agent may proceed.

Examples of the specific kind of the thermal acid generator are not particularly limited, and various materials used as the thermal acid generator in the related art may be applied without limitation. For example, examples of the ionic thermal acid generator include triphenylsulfonium, 1-dimethylthionaphthalene, 1-dimethylthio-4-hydroxynaphthalene, 1-dimethylthio-4,7-dihydroxynaphthalene, 4- Hydroxyphenyldimethylsulfonium, benzyl-4-hydroxyphenylmethylsulfonium, 2-methylbenzyl-4-hydroxyphenylmethylsulfonium, 2-methylbenzyl-4-acetylphenylmethylsulfonium, 2-methylbenzyl- Methane sulfonate, trifluoromethane sulfonate, camphor sulfonate, p-toluene sulfonate, hexafluorophosphonate, etc., such as 4-benzoyloxyphenyl methyl sulfonium, are mentioned. As an example of a nonionic thermal acid generator, a halogen containing compound, a diazomethane compound, a sulfone compound, a sulfonic acid ester compound, a carboxylic acid ester compound, a phosphate ester compound, a sulfonimide compound, a sulfone benzotriazole compound, etc. are mentioned. Examples of the halogen-containing compound include a haloalkyl group-containing hydrocarbon compound and a haloalkyl group-containing heterocyclic compound such as 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane and 2-phenyl-4,6 -Bis (trichloromethyl) -s-triazine, 2-naphthyl-4,6-bis (trichloromethyl) -s-triazine and the like. Examples of diazomethane compounds include bis (trifluoromethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (phenylsulfonyl) diazomethane and bis (p-tolylsulfonyl) dia Crude methane, bis (2,4-xyrylsulfonyl) diazomethane, bis (p-chlorophenylsulfonyl) diazomethane, methylsulfonyl-p-toluenesulfonyldiazomethane, cyclohexylsulfonyl (1 , 1-dimethylethylsulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, phenylsulfonyl (benzoyl) diazomethane and the like. Examples of the sulfone compound include β-ketosulfone compounds, β-sulfonyl sulfone compounds, and diaryldisulfone compounds such as 4-trisfenacyl sulfone, mesityl penacyl sulfone, bis (phenylsulfonyl) methane, and 4-chlorophenyl-4. -Methylphenyl disulfone compound, etc. are mentioned. Examples of the sulfonic acid ester compound include benzointosylate, pyrogallol trimesylate, nitrobenzyl-9,10-diethoxyanthracene-2-, such as alkyl sulfonic acid ester, haloalkyl sulfonic acid ester, aryl sulfonic acid ester and imino sulfonate. Sulfonate, 2,6-dinitrobenzylbenzenesulfonate, and the like. Examples of the carboxylic acid ester compound include carboxylic acid o-nitrobenzyl ester. More preferably, NACURE 2500 (King Industries) or XC128 (King Industries) etc. can be used.

The thermal acid generator contains 0.1 wt% to 10 wt%, or 0.2 wt% to 5 wt%, or 0.5 wt% to 2 wt%, based on the weight of the water dispersion binder resin contained in the resin composition for polarizer protective film. Can be. The weight% of the thermal acid generator may be obtained through Equation 2 below.

[Equation 2]

(Solid content of thermal acid generator contained in the resin composition for polarizer protective films) / (Solid content of water-dispersed binder resin contained in the resin composition for polarizer protective films) * 100.

That is, based on 100 parts by weight of the aqueous dispersion binder resin, 0.1 to 10 parts by weight, or 0.2 to 5 parts by weight, or 0.5 parts by weight to 2 parts by weight of the thermal acid generator.

When the content of the thermal acid generator is too large, the crosslinking reaction of the water dispersion binder resin and the crosslinking agent proceeds excessively during the thermosetting process of the resin composition for polarizer protective film, so that the crosslinking degree of the polarizer protective film is excessively increased, flexibility is increased. It may decrease, making stretching difficult.

On the other hand, when the content of the thermal acid generator is too small, the cross-linking reaction of the water dispersion binder resin and the crosslinking agent may be difficult to proceed sufficiently during the thermosetting process of the resin composition for polarizer protective film.

(4) Resin Composition for Polarizer Protective Film

The resin composition for polarizer protective film of the embodiment may include a water dispersion binder resin having a functional group represented by Formula 1 at a branched chain end thereof; A crosslinking agent compound represented by Formula 2; And it is a main feature to include both the thermal acid generator.

As will be described later, the resin composition for polarizer protective film of the embodiment includes a water-dispersive binder resin in which a functional group represented by Formula 1 is bonded to a branched chain end; The cross-linking compound and the cross-acid generator represented by the formula (2) are both included in the state of thermal curing process for film formation, and the cross-linking compound compound by the hydrogen ion (H ⁺ ) generated from the thermal acid generator during the heat curing process The crosslinking reaction between the functional groups represented by the formula (1) of the water-dispersible binder resin may proceed.

If it does not contain the thermal acid generator and a general acid catalyst is used, the crosslinking agent compound and the functional group represented by the formula (1) of the water dispersion binder resin also in the resin composition for polarizer protective film of the embodiment maintained at a temperature lower than 100 ℃ As the crosslinking reaction proceeds, solubility and coatability of the resin composition may decrease due to unnecessary crosslinking structure formation.

Therefore, as in the present invention, a water-dispersible binder resin having a functional group represented by Formula 1 bound thereto; A crosslinking agent compound represented by Formula 2; And only using a composition containing a thermal acid generator, in the resin composition for a polarizer protective film of the embodiment maintained at a temperature lower than 100 ℃ cross-linking reaction is inhibited, the cross-linking reaction may proceed only when heat treatment at a high temperature of 100 ℃ or more Since there is, while ensuring the solubility and coating properties of the resin composition for polarizer protective film, the polarizer protective film can implement improved mechanical properties through a high crosslinking density.

In particular, the thermal acid generator may include 2 parts by weight to 80 parts by weight, or 2 parts by weight to 70 parts by weight, or 2.4 parts by weight to 67 parts by weight, based on 100 parts by weight of the crosslinking agent compound.

When the content of the thermal acid generator is too high compared to the crosslinking agent compound, the crosslinking reaction of the water dispersion binder resin and the crosslinking agent proceeds excessively during the thermosetting process of the resin composition for polarizer protective film, and thus the crosslinking degree of the polarizer protective film is excessively increased. Accordingly, the stretching may be difficult due to the reduced flexibility, and the film properties may be degraded as the unreacted crosslinking agent remains.

On the other hand, when the content of the thermal acid generator is too small compared to the crosslinking agent compound, the crosslinking reaction of the water dispersion binder resin and the crosslinking agent may be difficult to proceed sufficiently during the thermosetting process of the resin composition for polarizer protective film.

On the other hand, the resin composition for polarizer protective film of the embodiment may further comprise water. That is, the water dispersion binder resin, the crosslinking agent compound and the thermal acid generator may be dissolved or dispersed in water to be used as a water dispersion solution or an aqueous solution, and the amount of water used here may be considered in terms of coating property and efficiency in subsequent thermosetting processes. Can be adjusted accordingly .

In addition, the resin composition for a polarizer protective film of the embodiment of the present invention, in addition to the above components, slip agents, curing aids, organic / inorganic fine particles, surfactants, antioxidants, UV stabilizers, leveling agents, antifouling agents, antistatic agents, UV absorbers It may further include additives commonly used in the art, such as antifoams, antiseptics. In addition, since the content can be variously adjusted within the range of not lowering the physical properties of the resin composition for polarizer protective film of the present invention, it is not particularly limited, for example, about 100 parts by weight of the total resin composition for polarizer protective film, 0.1 parts by weight to about 10 parts by weight.

Ⅱ. Polarizer Protective Film

According to another embodiment of the present invention, a polarizer protective film including a water dispersion binder resin crosslinked through a crosslinking group represented by Formula 3 may be provided. That is, in the polarizer protective film, the first water dispersion binder resin is bonded to one end of the crosslinking group represented by Formula 3, and the second water dispersion binder resin is formed at the other end of the crosslinking group represented by Formula 3 Can be combined to form a crosslinked structure. Accordingly, the polarizer protective film of another embodiment containing the crosslinked aqueous dispersion binder resin may implement improved mechanical properties through high crosslinking density.

Specifically, in Formula 3, R ₁₁ , R ₁₃ , R ₁₅ are each independently an alkylene group having 1 to 10 carbon atoms, R ₁₂ , R ₁₄ , R ₁₆ are each independently hydrogen, hydroxy having 1 to 20 carbon atoms It is either an alkyl group or a divalent functional group represented by the above formula (4), R ₁₇ to R ₂₂ are each independently hydrogen, a hydroxy group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms.

In Formula 4, R ₂₃ is an alkylene group having 1 to 10 carbon atoms, and R ₂₄ to R ₂₅ are each independently hydrogen, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. When the divalent functional group represented by Chemical Formula 4 is a hydroxyalkyl group having 1 to 20 carbon atoms in R ₁₂ , R ₁₄ , and R ₁₆ , it is formed through a crosslinking reaction with the functional group of Chemical Formula 1 contained in the water-dispersible binder resin Can be.

More specifically, in Formula 3, R ₁₂ , R ₁₄ , R ₁₆ may be all hydrogen. In Formula 3, R ₁₂ , R ₁₄ , and R ₁₆ may all be hydroxyalkyl groups having 1 to 20 carbon atoms. In Formula 3, R ₁₂ , R ₁₄ , and R ₁₆ may all be divalent functional groups represented by Formula 4. In Formula 3, two of R ₁₂ , R ₁₄ , and R ₁₆ may be a hydroxyalkyl group having 1 to 20 carbon atoms, and the other one may be a divalent functional group represented by Formula 4 above. Alternatively, in Formula 3, one of R ₁₂ , R ₁₄ , and R ₁₆ may be a hydroxyalkyl group having 1 to 20 carbon atoms, and the other two may be a divalent functional group represented by Formula 4 above.

On the other hand, when the content of the crosslinking group represented by Formula 3 is too small, it may be difficult to achieve sufficient mechanical properties by reducing the crosslinking degree of the polarizer protective film.

More specifically, the water-dispersive binder resin crosslinked through the crosslinking functional group represented by Chemical Formula 3 includes a water-dispersive binder resin having a functional group represented by Chemical Formula 1 bonded to a branched chain end; A crosslinking agent compound represented by Formula 2; And it may include a thermosetting of the resin composition for polarizer protective film containing a thermal acid generator. The thermosetting means a material obtained through a thermosetting step of the resin composition for polarizer protective film of the embodiment. All the contents of the resin composition for polarizer protective film is as described through the above embodiment.

On the other hand, the polarizer protective film may further include an ionic compound represented by the formula (5).

[Formula 5]

In Formula 5, R ₃₀ , R ₃₂ , and R ₃₄ each independently represent an alkyl group having 1 to 20 carbon atoms, and R ₈₁ , R ₃₃ , and R ₃₅ each independently represent one of hydrogen or a hydroxyalkyl group having 1 to 20 carbon atoms.

The ionic compound represented by Formula 5 may be generated as the crosslinking agent compound included in the resin composition for polarizer protective film of the embodiment proceeds with a deionization reaction with hydrogen ions (H ⁺ ) generated from a thermal acid generator. .

The ionic compound represented by Chemical Formula 5 reacts with the functional group of Chemical Formula 1 bonded to the branched chain end of the water-dispersive binder resin included in the resin composition for polarizer protective film of the embodiment to form a crosslinking functional group represented by Chemical Formula 3 can do.

The polarizer protective film has a final thickness of at least about 50 nm, or at least about 100 nm, or at least about 200 nm after drying, curing and stretching, and also at most about 5000 nm, or at most about 2000 nm, or at least about 1500 nm. Or about 900 nm or less. When the thickness of the polarizer protective film increases or decreases by a specific value, the physical properties measured in the polarizer protective film may also change by a certain value.

On the other hand, an example of a method of manufacturing the polarizer protective film is not limited to a large, for example, to form a coating film by applying a resin composition for polarizer protective film of the embodiment (step 1); Drying the coating film (step 2); A method including a step (step 3) of curing the dried coating film may be used.

Step 1 is a step of forming a coating film by applying the above-mentioned resin composition for polarizer protective film on a base film. The content of the resin composition for polarizer protective film includes all of the above-described information in the embodiment.

The method of applying the resin composition for the polarizer protective film on the base film is not particularly limited as long as it can be used in the technical field to which the present technology belongs, for example, bar coating method, knife coating method, roll coating method, blade coating method. , Die coating method, micro gravure coating method, comma coating method, slot die coating method, lip coating method, or solution casting method may be used.

The base film may be a TAC film, an acrylic film, a PET film, a cyclo-olefin film, and the like, preferably an acrylic film, but the present invention is not limited thereto.

According to one embodiment of the present invention, the acrylic film may be uniaxially stretched before applying the resin composition for polarizer protective film. At this time, the stretching direction is not particularly limited, and the stretching ratio may be stretched to be 1.1 times or more, 1.2 times or more, or 1.5 times or more, 5 times or less, or 3 times or less based on the length of the stretching direction.

The resin composition for polarizer protective films described above may be applied onto at least one surface of the unstretched or uniaxially stretched acrylic film.

Generally, in order to form a polarizer protective film, the method of apply | coating the resin composition for polarizer protective films on a stretched film, and drying and hardening is used. However, in the case of the stretched film, since the polymer is rearranged in the stretching process, the coating layer does not adhere well to the stretched film.

Accordingly, the acrylic stretched film and the polarizer protection by applying the resin composition for polarizer protective film on the acrylic film and stretching the acrylic film coated with the resin composition for polarizer protective film at high temperature while curing the resin composition for polarizer protective film. The polarizer protective film with high adhesiveness of a film can be provided.

The stretching may be carried out by heat treatment at a temperature of about 80 ° C. or more, or about 90 ° C. or more, or about 100 ° C. or more and about 200 ° C. or less, or about 180 ° C. or less, or about 160 ° C. or less. If the stretching temperature is too low, sufficient curing may not occur with respect to the resin composition for polarizer protective film, and if it is too high, thermal deformation of the acrylic base film may occur, and thus, the above temperature range is preferable.

The stretching direction is not particularly limited, and the stretching ratio is 1.05 times or more, or 1.2 times or more, or 1.5 times or more, 10 times or less, or 5 times or less, or 3 times or less based on the length of the stretching direction. Can be. When the draw ratio is less than 1.05 times, the effect of stretching may not be sufficiently achieved, and when the draw ratio is more than 10 times, the coating layer may be cracked, and it is preferable to draw in the draw ratio described above in this respect.

If the acrylic film is uniaxially stretched before applying the resin composition for polarizer protective film, the stretching direction after the coating is preferably stretched in a direction perpendicular to the stretching direction before application of the resin composition for polarizer protective film. . For example, when the acrylic film is stretched in the length (MD) direction before the resin composition for polarizer protective film is applied, it may be stretched in the width (TD) direction after the resin composition for polarizer protective film is applied.

In addition, when stretching before and after applying the resin composition for polarizer protective film, the total draw ratio is at least 1.1 times, or at least 1.2 times, or at least 1.5 times, based on the total stretching area of the acrylic film, 25 times It can extend | stretch so that it may be 10 times or less, or 7 times or less. When the draw ratio is less than 1.1 times, the effect of stretching may not be sufficiently achieved, and when the draw ratio is more than 25 times, the coating layer may be cracked, and it is preferable to draw in the draw ratio described above in this respect.

Step 2 is a step of drying the coating film formed by applying the resin composition for polarizer protective film on a substrate.

The drying step of the coating film may be carried out by heating means such as a hot plate, a hot air circulation furnace, an infrared furnace, or the like, and may be performed at a temperature of 50 ° C. to 120 ° C., or 50 ° C. to 110 ° C.

Step 3 is a step of curing the dried coating film by heat treatment. In this case, the heat treatment may be performed by a heating means such as a hot plate, a hot air circulation furnace, an infrared furnace, and the like, and may be performed at 130 ° C. to 300 ° C., or 130 ° C. to 200 ° C. temperature.

III. Polarizer

According to another embodiment of the invention, a polarizer; Adhesive layer; And it may be provided with a polarizing plate comprising a polarizer protective film of the other embodiment. More specifically, the polarizing plate is a polarizer; An adhesive layer laminated on at least one surface of the polarizer; And a polarizer protective film laminated on one surface of the adhesive layer. That is, an adhesive layer may be laminated in a sandwich structure between the polarizer and the polarizer protective film.

Information on the polarizer protective film includes the above-described information in another embodiment.

The polarizer exhibits a property of extracting only light vibrating in one direction from incident light while vibrating in various directions. This property can be achieved by stretching polyvinyl alcohol (PVA) absorbing iodine with strong tension. For example, more specifically, swelling soaking the PVA film in an aqueous solution, swelling, dyeing with a dichroic material imparting polarization to the swelled PVA film, stretching the dyed PVA film The polarizer may be formed through a stretching step of arranging the dichroic dye materials side by side in the stretching direction, and a complementary color step of correcting the color of the PVA film subjected to the stretching step. However, the polarizing plate of the present invention is not limited thereto.

In the polarizing plate, the polarizer protective film may be attached to one or both sides of the polarizer. In this case, the polarizing plate may be used as a lower polarizing plate of the LCD, and in the laminated structure in the LCD, the polarizer protective film of the present invention may be positioned below.

As described above, when the polarizing plate is laminated on the LCD with the polarizer protective film as the lower portion, the lower protective film of the polarizing plate is damaged due to the irregularities of the prism sheet or the diffusion film provided under the polarizing plate, thereby preventing the problem of increasing the haze, thereby providing excellent optical. It can exhibit physical properties.

The polarizer and the polarizer protective film of the present invention can be bonded by lamination using an adhesive or the like. Usable adhesives are not particularly limited as long as they are known in the art. For example, there are water-based adhesives, one-component or two-component polyvinyl alcohol (PVA) adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, or hot melt adhesives. It is not limited only to these examples.

The polarizing plate may further include a base film formed on one surface of the polarizer protective film. The thickness of the base film is not particularly limited, but a film having a thickness of about 10 μm to about 200 μm, or about 20 μm to about 100 μm after stretching may be used.

According to an embodiment of the present invention, the base film may use a TAC film, an acrylic film, PET film, cyclo-olefin film, etc., preferably an acrylic film, but the present invention is not limited thereto. .

The acrylic film is a film comprising an alkyl (meth) acrylate-based unit and a copolymer comprising a styrene-based unit, and an aromatic resin having a carbonate portion in the main chain, or an alkyl (meth) acrylate-based unit, a styrene-based unit, It may be a film comprising a 3 to 6 membered hetero ring unit substituted with at least one carbonyl group and a vinyl cyanide unit. In addition, it may be an acrylic resin having a lactone structure. However, the present invention is not limited thereto.

In addition, the acrylic film can be stretched together after applying the resin composition for polarizer protective film to the film in the unstretched state or uniaxially stretched state.

When laminating and adhering the polarizer protective film of the present invention to the polarizer, it is preferable that the surface where the base film is not formed is attached to the polarizer, and the base film is laminated so as to be positioned outward of the polarizing plate.

The above-described polarizer is described as an example applied to the LCD, but is not limited thereto, and may be utilized in various fields. For example, it can be used for mobile communication terminals, smart phones, other mobile devices, display devices, electronic blackboards, outdoor billboards, and various display units. According to an embodiment of the present invention, the polarizing plate may be a twisted nematic (TN), super twisted nematic (STN) liquid crystal, an in-plane switching (IPS), a super-IPS, a fringe field switching (FFS), or the like. May be a polarizing plate for the horizontal alignment mode, or may be a polarizing plate for the vertical alignment mode.

According to the present invention, a resin composition for a polarizer protective film that can exhibit excellent physical and optical properties and prevent damage to the lower polarizing plate, a polarizer protective film and a polarizing plate using the same can be provided.

The invention is explained in more detail in the following examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

<Example: Preparation of resin composition for polarizer protective film and polarizer protective film>

Examples 1 to 8

(1) Preparation of Resin Composition for Polarizer Protective Film

(1,3,5-triazine-2,4,6-triyl) tris ((methoxymethyl) azanediyl) tree of formula (a) as water-soluble resin, WS-4000 (Mitsui), imino crosslinking agent Methanol ((1,3,5-triazine-2,4,6-triyl) tris ((methoxymethyl) azanediyl) trimethanol), a NACURE 2500 (King Industries) in which form b is neutralized with Amine as a thermal acid generator The resin composition for polarizer protective film was prepared by mixing 7.0 g of pure water with the solid content of Table 1 below.

(2) Preparation of polarizer protective film

The polymethyl methacrylate resin was prepared using the T-die film making machine under 250 ° C conditions, to produce an unoriented film having a width of 800 mm and a thickness of 200 m. The unoriented film was stretched 1.8 times in the length (MD) direction at a temperature of 135 ° C. to prepare a uniaxially stretched film.

On the uniaxial stretched film, the resin composition for polarizer protective film was coated by a bar coating method, followed by hot air drying at a temperature of 100 ° C. for 30 seconds, and then at a temperature of 135 ° C. for 1 minute (TD). Stretched 2.5 times in the direction, to prepare a polarizer protective film having a thickness of about 280nm.

(3) Preparation of Polarizing Plate

The polarizer protective film prepared in (2) is directed to the polyvinyl alcohol (PVA) film and a UV-based adhesive is applied between the PVA film and the polarizer protective film to laminate the polarizer protective film on both sides of the PVA film. On the other hand, the ultraviolet-ray was irradiated and the polarizing plate which laminated | stacked the polarizer protective film on both surfaces of the PVA film was manufactured.

[Formula a]

[Formula b]

Example 9

Water-soluble resin WS-4000 (Mitsui), imino crosslinker N2, N4, N6-tris (methoxymethyl) -1,3,5-triazine-2,4,6-triamine (C) N2, N4, N6-tris (methoxymethyl) -1,3,5-triazine-2,4,6-triamine), NACURE 2500 (King Industries) in the form in which Formula b is neutralized with Amine as a thermal acid generator A polarizer protective film and a polarizing plate were manufactured in the same manner as in Example 1, except that the resin composition for polarizer protective film mixed with 6.2 g of pure water was used as the solid content of Table 1.

[Formula c]

Example 10

N-S, N4, N6-tris (methoxymethyl) -1,3,5-triazine-2,4,6-triamine of Chemical Formula c above N2, N4, N6-tris (methoxymethyl) -1,3,5-triazine-2,4,6-triamine) XC128 (King Industries) in which dodecylbenzensulfonic acid of formula d is neutralized with Amine as a thermal acid generator To prepare a polarizer protective film and a polarizing plate in the same manner as in Example 1, except that the resin composition for polarizer protective film mixed with 6.2 g of pure water in the solid content of Table 1 was used.

[Formula d]

<Comparative Example: Production of Resin Composition for Polarizer Protective Film and Polarizer Protective Film>

Comparative Example 1

(1,3,5-triazine-2,4,6-triyl) tris ((methoxymethyl) azanediyl) tree of formula (a) as water-soluble resin, WS-4000 (Mitsui), imino crosslinking agent Methanol ((1,3,5-triazine-2,4,6-triyl) tris ((methoxymethyl) azanediyl) trimethanol), a NACURE 2500 (King Industries), in which the above formula b is neutralized with Amine as a thermal acid generator A polarizer protective film and a polarizing plate were manufactured in the same manner as in Example 1, except that the resin composition for polarizer protective film mixed with pure water 5.0 g in the solid content of Table 1 was used.

Reference Example Preparation of Resin Composition for Polarizer Protective Film and Polarizer Protective Film

Reference Examples 1 to 6

(1,3,5-triazine-2,4,6-triyl) tris ((methoxymethyl) azanediyl) tree of formula (a) as water-soluble resin, WS-4000 (Mitsui), imino crosslinking agent Methanol ((1,3,5-triazine-2,4,6-triyl) tris ((methoxymethyl) azanediyl) trimethanol), a NACURE 2500 (King Industries), in which the above formula b is neutralized with Amine as a thermal acid generator A polarizer protective film and a polarizing plate were manufactured in the same manner as in Example 1, except that the resin composition for polarizer protective film mixed with 9.0 g of pure water was used as the solid content of Table 1 below.

<Experimental Example: Measurement of the physical properties of the polarizer protective film obtained in Examples, Comparative Examples and Reference Examples>

Physical properties of the polarizer protective films obtained in the Examples, Comparative Examples and Reference Examples were measured by the following methods, and the results are shown in Table 1 below.

1. Scratch resistance

The sample layer (50 mm X 50 mm) to which the vibration generator was connected was placed in contact with the coating layer of the polarizer protective films of the Examples and Comparative Examples and the diffusion sheet (LG Electronics, Ltd. ND146), and loaded under a weight of 200 g. Applied vibration intensity 2.8 Grms, frequency 20-60 Hz) was added for 240 seconds. Thereafter, the presence or absence of scratches and crevices on the surface of the coating layer of the polarizer protective film was evaluated under the following criteria. ◎ if there is no scratch or splitting occurs, O when extremely fine scratches or splitting occurs, △ when fine scratches or splitting occur, and X when clearly occurs.

2. Pencil Hardness

Pencil hardness was measured at a 500g load using a pencil hardness tester (hardness tester, manufacturer: Chungbuk Tech). According to ASTM 3363-74, the standard pencil (Mitsubishi) was maintained at an angle of 45 degrees while varying from 6B to 9H, and the surface of the polarizer protective film was scratched at a rate of 250 mm / min to observe the change of the surface. Each experimental value is described as the average value after 5 measurements.

Experimental Example Measurement Results of Examples, Comparative Examples and Reference Examples division Binder Resin Imino Family Association Thermal acid generator Scratch resistance Pencil hardness Kinds Solid content Kinds Solid content (% by weight of binder resin) Kinds Solid content (% by weight of binder resin) Example 1 WS-4000 3.0 g Formula a 0.09g
(3.0 wt%) Formula b 0.015 g
(0.5 wt%) O HB Example 2 WS-4000 3.0 g Formula a 0.09g (3.0% by weight) Formula b 0.030g
(1.0 wt%) O H Example 3 WS-4000 3.0 g Formula a 0.09g (3.0% by weight) Formula b 0.060 g
(2.0 wt%) O HB Example 4 WS-4000 3.0 g Formula a 0.15g (5.0% by weight) Formula b 0.015 g
(0.5 wt%) ◎ H Example 5 WS-4000 3.0 g Formula a 0.15g (5.0% by weight) Formula b 0.030g
(1.0 wt%) ◎ H Example 6 WS-4000 3.0 g Formula a 0.15g (5.0% by weight) Formula b 0.060 g
(2.0 wt%) ◎ H Example 7 WS-4000 3.0 g Formula a 0.60 g (20.0 wt.%) Formula b 0.015 g
(0.5 wt%) O H Example 8 WS-4000 3.0 g Formula a 0.60 g
(20.0 wt%) Formula b 0.030g
(1.0 wt%) O H Example 9 WS-4000 3.0 g Formula c 0.30 g
(10.0 wt%) Formula b 0.030g
(1.0 wt%) O H Example 10 WS-4000 3.0 g Formula c 0.30 g (10.0 wt.%) Formula d 0.030g
(1.0 wt%) O H Comparative Example 1 WS-4000 3.0 g - - - - X HB Reference Example 1 WS-4000 3.0 g Formula a 0.03 g (1.0 wt%) Formula b 0.030g
(1.0 wt%) △ HB Reference Example 2 WS-4000 3.0 g Formula a 0.03 g (1.0 wt%) Formula b 0.060 g
(2.0 wt%) △ H Reference Example 3 WS-4000 3.0 g Formula a 1.20 g (40.0 wt.%) Formula b 0.015 g
(0.5 wt%) △ HB Reference Example 4 WS-4000 3.0 g Formula a 0.03 g (1.0 wt%) Formula b 0.015 g
(0.5 wt%) △ H Reference Example 5 WS-4000 3.0 g Formula a 1.20 g (40.0 wt.%) Formula b 0.030g
(1.0 wt%) △ H Reference Example 6 WS-4000 3.0 g Formula a 1.20 g (40.0 wt.%) Formula b 0.060 g
(2.0 wt%) △ H

As shown in Table 1, the polarizer protective film obtained in the Example showed excellent scratch resistance and pencil hardness. On the other hand, the film of Comparative Example 1, in which the imino crosslinking agent and the thermal acid generator were not used, was evaluated as not suitable as a lower protective film of the polarizing plate due to the lack of scratch resistance and pencil hardness.

In addition, the films of Reference Examples 1 to 6 in which the imino crosslinking agent and the thermal acid generator were not used in the preferred mixing ratio were evaluated to be insufficient as scratch protection because they were not suitable as the lower protective film of the polarizing plate.

Claims (13)

A water-dispersible binder resin having a functional group represented by the following Chemical Formula 1 bonded to a branched chain terminal;
A crosslinking agent compound represented by Formula 2; And
Resin composition for polarizer protective film containing a thermal acid generator:
[Formula 1]

In Chemical Formula 1,
At least one of R ₁ to R ₃ is one of a hydroxy group or an alkoxy group having 1 to 20 carbon atoms, the rest is one of hydrogen or an alkyl group having 1 to 20 carbon atoms,
[Formula 2]

In Chemical Formula 2,
R ₄ , R ₆ and R ₈ are each independently alkoxyalkyl groups having 2 to 20 carbon atoms, and R ₅ , R ₇ and R ₉ are each independently hydrogen or one of hydroxyalkyl groups having 1 to 20 carbon atoms.
The method of claim 1,
Resin composition for a polarizer protective film containing 2 parts by weight to 80 parts by weight of the thermal acid generator relative to 100 parts by weight of the crosslinking agent compound.
The method of claim 1,
The crosslinking agent compound represented by Formula 2 is contained in 2% by weight to 30% by weight based on the weight of the water-dispersed binder resin contained in the resin composition for polarizer protective film, the resin composition for polarizer protective film.
The method of claim 1,
The weight average molecular weight of the crosslinking agent compound is 200 g / mol to 400 g / mol, the resin composition for polarizer protective film.
The method of claim 1,
The thermal acid generator is contained in 0.1% by weight to 10% by weight based on the weight of the water dispersion binder resin contained in the resin composition for polarizer protective film, the resin composition for polarizer protective film.
The method of claim 1,
Regarding the aqueous dispersion binder resin, the content of the functional group represented by Formula 1 is 6 mol% to 20 mol%, the resin composition for polarizer protective film.
The method of claim 1,
The water-dispersed binder resin is a resin composition for polarizer protective film comprising a water-based polyurethane resin, a water-based acrylic resin, a water-based polyester resin or a combination thereof.
Polarizer protective film comprising a water dispersion binder resin crosslinked via a crosslinking functional group represented by the formula (3):
[Formula 3]

In Chemical Formula 3,
R ₁₁ , R ₁₃ and R ₁₅ are each independently an alkylene group having 1 to 10 carbon atoms,
R ₁₂ , R ₁₄ , and R ₁₆ are each independently hydrogen, a hydroxyalkyl group having 1 to 20 carbon atoms, or a divalent functional group represented by the following general formula (4),
R ₁₇ to R ₂₂ are each independently hydrogen, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms,
[Formula 4]

In Chemical Formula 4,
R ₂₃ is an alkylene group having 1 to 10 carbon atoms,
R ₂₄ to R ₂₅ are each independently hydrogen, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms.
The method of claim 8,
The water-dispersible binder resin crosslinked through the crosslinking functional group represented by Formula 3,
A water-dispersible binder resin having a functional group represented by the following Chemical Formula 1 bonded to a branched chain terminal; A crosslinking agent compound represented by Formula 2; And a thermoset of the resin composition for polarizer protective film including a thermal acid generator, the polarizer protective film:
[Formula 1]

In Chemical Formula 1,
At least one of R ₁ to R ₃ is one of a hydroxy group or an alkoxy group having 1 to 20 carbon atoms, the rest is one of hydrogen or an alkyl group having 1 to 20 carbon atoms,
[Formula 2]

In Chemical Formula 2,
R ₄ , R ₆ and R ₈ are each independently alkoxyalkyl groups having 2 to 20 carbon atoms, and R ₈ , R ₇ and R ₉ are each independently hydrogen or one of hydroxyalkyl groups having 1 to 20 carbon atoms.
The method of claim 8,
The polarizer protective film further comprises an ionic compound represented by Formula 4, a polarizer protective film:
[Formula 5]

In Chemical Formula 5,
R ₃₀ , R ₃₂ and R ₃₄ are each independently an alkyl group having 1 to 20 carbon atoms, and R ₈₁ , R ₃₃ and R ₃₅ are each independently hydrogen or one of hydroxyalkyl groups having 1 to 20 carbon atoms.
The method of claim 8,
The polarizer protective film has a thickness of 50 nm to 5 ㎛, polarizer protective film.
Polarizer;
Adhesive layer; And
Polarizing plate comprising a polarizer protective film of claim 8.
The method of claim 12,
A polarizer further comprising a base film formed on one surface of the polarizer protective film.