KR102661102B1 - Coating composition, polarizer protecting film, manufacturing method of polarizer protecting film, polarizing plate comprising same and liquid crystal display device comprising same - Google Patents

Abstract

The present invention relates to a coating composition, a polarizer protective film, a method for manufacturing a polarizer protective film, a polarizing plate including the same, and a liquid crystal display device including the same.

Description

Coating composition, polarizer protective film, method of manufacturing the polarizer protective film, polarizer including the same, and liquid crystal display device including the same SAME}

The present invention relates to a coating composition, a polarizer protective film, a method for manufacturing a polarizer protective film, a polarizing plate including the same, and a liquid crystal display device including the same.

Based on recent developments in optical technology, various devices such as plasma display panels (PDP), liquid crystal displays (LCD), and organic light emitting diodes (OLED) are being developed to replace conventional cathode ray tubes. Display devices using this method have been proposed and are commercially available. Recently, the characteristics required for these display devices are becoming more sophisticated, and accordingly, the characteristics required for peripheral components such as optical films applied to display devices are also becoming more sophisticated.

Liquid crystal displays are widely used in everything from mobile phones and small portable electronic devices to large electronic devices such as personal computers and televisions, and are one of the flat panel displays whose uses are gradually expanding.

Since these liquid crystal displays are not self-luminous devices, a light source such as a backlight unit is usually placed on the back of a lower polarizer provided on the lower side of the liquid crystal cell, and the light emitted from the light source is transmitted through the liquid crystal cell to form liquid crystal molecules. The image is displayed by changing the arrangement.

Recently, as liquid crystal displays have become larger and slimmer, a lot of load is applied to the center of the liquid crystal cell when being transported or used, causing sagging of the lower polarizer, which causes the polarizer protective film of the lower polarizer attached to the liquid crystal cell. Damage such as grinding of the lower polarizer plate occurs when it comes into contact with the diffusion sheet on the surface of the backlight unit. To solve this problem, a method of coating a hard coating layer on the protective film of the lower polarizer has been proposed, but there is a problem of increased process costs.

In addition, during the manufacturing process of the polarizer protective film of the lower polarizer, friction between films occurs due to various reasons such as diversification of winding slitting width and increase in winding amount, resulting in the problem of the protective film being ground and damaged when manufacturing the polarizer protective film. It is happening.

According to this need, there is a need for the development of a method that can prevent damage to the lower polarizer due to the lower structure and increase in haze while ensuring productivity and price competitiveness during mass production.

Korean Public Gazette No. 2005-0101743

The present invention is intended to solve the problem of damage to the polarizer protective film of the lower polarizer, and includes a coating composition with excellent coating properties, a polarizer protective film with high surface hardness and scratch resistance, a polarizer having excellent physical and optical properties including the same, and A liquid crystal display device is provided.

An exemplary embodiment of the present application includes an anionic polyurethane resin; A polymer with an acid value of 200 mgKOH/g or more; and an oxazoline-based curing agent, wherein the coating composition includes 1 to 30 parts by weight of a polymer having an acid value of 200 mgKOH/g or more, based on 100 parts by weight of the coating composition.

Another exemplary embodiment includes preparing a base film; Applying the coating composition on at least one side of a base film; and drying the coating composition.

Another embodiment is a polarizer; and a polarizer protective film according to an exemplary embodiment of the present application on at least one surface of the polarizer.

Lastly, an exemplary embodiment of the present application includes a liquid crystal cell; an upper polarizer provided on the upper layer of the liquid crystal cell; a lower polarizer provided on the lower layer of the liquid crystal cell; and a backlight unit provided in a lower portion of the lower polarizer, wherein the lower polarizer includes a polarizer; and a polarizer protective film according to an exemplary embodiment of the present application disposed on one or both sides of the polarizer.

The present invention is intended to solve the problem of damage to the polarizer protective film of the lower polarizer, and includes a coating composition with excellent coating properties, a polarizer protective film with high surface hardness and scratch resistance, a polarizer having excellent physical and optical properties including the same, and We would like to provide a liquid crystal display device.

In particular, the coating composition according to the present invention contains a polymer with an acid value of 200 mgKOH/g or more, and the coating composition containing this is combined with an oxazoline-based curing agent to increase the splitting characteristics when used as a polarizer protective film in the future. You will have

In addition, when the polarizer protective film containing the coating composition is used as a protective film for the lower polarizer, the polarizer protective film may be damaged when it comes into contact with the diffusion sheet on the surface of the backlight unit due to sagging of the lower polarizer, which may cause device defects. It can prevent potential problems and exhibit excellent optical properties.

1 is a diagram illustrating a liquid crystal display device according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Additionally, the embodiments of the present invention are provided to explain the present invention in more detail to those with average knowledge in the relevant technical field.

The present invention relates to a polarizer protective film adjacent to a backlight unit of a lower polarizer provided in the lower layer of a liquid crystal cell in a liquid crystal display device, and the protective film included in the polarizer protective film includes an anionic polyurethane resin; A polymer with an acid value of 200 mgKOH/g or more; And a coating composition comprising an oxazoline-based curing agent, based on 100 parts by weight of the coating composition, 1 to 30 parts by weight of a polymer having an acid value of 200 mgKOH/g or more, and the polarizer protective film of the present invention has a splitting characteristic. It has excellent features.

Additionally, the polarizer protective film made with the coating composition of the present invention can prevent damage that may occur due to sagging of the lower polarizer.

Figure 1 shows an embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in Figure 1 includes a liquid crystal cell 20; an upper polarizer 10 provided on the upper layer of the liquid crystal cell 20; a lower polarizing plate 30 provided in the lower layer of the liquid crystal cell 20; and a backlight unit 40 provided in a lower part of the lower polarizer, wherein the lower polarizer 30 is provided with a polarizer protection film 34 on a side adjacent to the backlight unit.

In the present invention, the terms 'upper surface' and 'top' mean a surface or direction arranged to face the viewer, that is, the viewer's side, when the polarizer is mounted on a device such as a liquid crystal display. Conversely, 'bottom' and 'bottom' refer to the side or direction disposed to face the backlight unit, opposite to the viewer, when the polarizer is mounted on the device.

Hereinafter, the coating composition of the present invention, the polarizer protective film, the method for manufacturing the polarizer protective film, the polarizing plate including the polarizer protective film, and the liquid crystal display device including the polarizing plate will be described in more detail.

An exemplary embodiment of the present application includes an anionic polyurethane resin; A polymer with an acid value of 200 mgKOH/g or more; and an oxazoline-based curing agent, wherein the coating composition includes 1 to 30 parts by weight of a polymer having an acid value of 200 mgKOH/g or more, based on 100 parts by weight of the coating composition.

In an exemplary embodiment of the present application, the acid value of the polymer may be 200 mgKOH/g or more.

In another embodiment, the acid value of the polymer may be 200 mgKOH/g or more, preferably 203 mgKOH/g or more, and 500 mgKOH/g or less, preferably 450 mgKOH/g or less.

In another embodiment, the acid value of the polymer may be 200 mgKOH/g or more and 500 mgKOH/g or less, preferably 203 mgKOH/g or more and 450 mgKOH/g or less.

In particular, the coating composition according to the present invention contains a polymer with an acid value of 200 mgKOH/g or more, and the coating composition containing this is combined with an oxazoline-based curing agent to increase the splitting characteristics when used as a polarizer protective film in the future. You will have

In an exemplary embodiment of the present application, a coating composition is provided in which the anionic polyurethane resin is contained in an amount of 60 parts by weight or more and 95 parts by weight or less based on 100 parts by weight of the coating composition.

In another embodiment, the anionic polyurethane resin is present in an amount of 60 parts by weight or more and 95 parts by weight or less, preferably 65 parts by weight or more and 93 parts by weight or less, more preferably 75 parts by weight, based on 100 parts by weight of the coating composition. It may contain more than 90 parts by weight or less.

In an exemplary embodiment of the present application, a coating composition is provided in which the oxazoline-based curing agent is contained in an amount of 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the coating composition.

In another embodiment, the oxazoline-based curing agent is 1 part by weight or more and 20 parts by weight or less, preferably 3 parts by weight or more and 15 parts by weight or less, more preferably 5 parts by weight or more, based on 100 parts by weight of the coating composition. It may be 15 parts by weight or less.

As the anionic polyurethane resin and the oxazoline-based curing agent include the content in the coating composition, the polarizer protective film containing the anionic polyurethane resin has excellent hardness, excellent haze characteristics, and particularly excellent grinding characteristics. have it

In an exemplary embodiment of the present application, the acid value refers to the number of mg of potassium hydroxide required to neutralize free fatty acids and other acidic substances contained in 1g of fats and oils such as oil or beeswax.

In an exemplary embodiment of the present application, the polymer includes a monomer containing carboxylic acid; and a monomer containing phenol.

The polymer can be used if it contains a monomer containing carboxylic acid or phenol that can react with the oxazoline-based curing agent contained in the coating composition. In this case, the carboxylic acid (carboxylic acid) group and phenol group can be present in the monomer itself or introduced through ring-opening reaction, deprotection reaction, etc.

In an exemplary embodiment of the present application, the polymer is a (meth)acrylate-based monomer, a crotonic acid-containing monomer, aconitic acid-containing monomer, maleic anhydride-based monomer, anhydrous It may include one or more selected from the group consisting of a partial hydrolyzate of maleic acid, fumaric anhydride, and acetoxy styrene.

In an exemplary embodiment of the present application, the (meth)acrylate-based monomer includes both acrylate-based monomers and methacrylate-based monomers. For example, the (meth)acrylate-based monomer may be a copolymer of a (meth)acrylic acid ester-based monomer and a crosslinkable functional group-containing monomer.

The (meth)acrylic acid ester-based monomer is not particularly limited, but examples include alkyl (meth)acrylate. More specifically, monomers having an alkyl group having 1 to 12 carbon atoms include pentyl (meth)acrylate, n-butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethyl It may include one or more of hexyl (meth)acrylate, dodecyl (meth)acrylate, and decyl (meth)acrylate.

The crosslinkable functional group-containing monomer is not particularly limited, but may include, for example, one or more of a hydroxy group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, ) acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, or 2-hydroxypropylene glycol (meth)acrylate.

Examples of the carboxyl group-containing monomer include (meth)acrylic acid, 2-(meth)acryloyloxyacetic acid, 3-(meth)acryloyloxypropylic acid, 4-(meth)acryloyloxybutylic acid, and acrylic acid. Examples include duplex, itaconic acid, maleic acid, or maleic anhydride.

Examples of the nitrogen-containing monomer include (meth)acrylonitrile, N-vinyl pyrrolidone, or N-vinyl caprolactam.

The (meth)acrylate-based resin may also be additionally copolymerized with at least one of vinyl acetate, styrene, and acrylonitrile from the viewpoint of improving other functionalities such as compatibility.

In an exemplary embodiment of the present application, a coating composition is provided wherein the polymer has a weight average molecular weight of 1,000 g/mol or more and 5,000,000 g/mol or less.

The weight average molecular weight is one of the average molecular weights used as a standard for the molecular weight of certain polymer materials whose molecular weight is not uniform, and is a value obtained by averaging the molecular weights of the component molecular species of a polymer compound with a molecular weight distribution by weight fraction.

The weight average molecular weight can be measured through Gel Permeation Chromatography (GPC) analysis.

In an exemplary embodiment of the present application, the coating composition includes an aqueous wax dispersion; particulate; menstruum; dispersant; photoinitiator; ten-initial tense; crosslinking agent; and a tackifier. It provides a coating composition comprising at least one selected from the group consisting of.

In an exemplary embodiment of the present application, the wax aqueous dispersion includes polyethylene wax; Amide wax; Carnauba wax; And it provides a coating composition comprising at least one selected from the group consisting of Fischer-Tropsch wax.

In an exemplary embodiment of the present application, the wax aqueous dispersion may include Carnauba wax.

In an exemplary embodiment of the present application, the cross-linking agent may include a cross-linking compound, and the cross-linking agent may be an isocyanate-based cross-linking agent, and those known in the art may be used.

According to an exemplary embodiment of the present specification, the crosslinkable compound is hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate having 2 to 14 ethylene groups, trimethyl Allpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, 2-trisacryloyloxymethylethylphthalic acid, propylene group Acidic modifications of propylene glycol di(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate and di Compounds obtained by esterifying polyhydric alcohols, such as a mixture of pentaerythritol hexa(meth)acrylate (trade name: TO-2348, TO-2349, manufactured by Dong-A Synthetics Co., Ltd., Japan), with an αβ-unsaturated carboxylic acid; Compounds obtained by adding (meth)acrylic acid to compounds containing a glycidyl group, such as trimethylolpropane triglycidyl ether acrylic acid adduct and bisphenol A diglycidyl ether acrylic acid adduct; Ester compounds of compounds having a hydroxyl group or ethylenically unsaturated bond, such as phthalic acid diester of β-hydroxyethyl (meth)acrylate and toluene diisocyanate adduct of β-hydroxyethyl (meth)acrylate, and polyhydric carboxylic acid. , or adducts with polyisocyanates; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; and 9,9'-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, but is not limited to these and is known in the art. You can use common ones.

According to an exemplary embodiment of the present specification, the photoinitiator includes a triazine-based compound, a biimidazole compound, an acetophenone-based compound, an O-acyloxime-based compound, a thioxanthone-based compound, a phosphine oxide-based compound, a coumarin-based compound, and a benzope. It may be substituted with one or two or more substituents selected from the group consisting of non-based compounds.

Specifically, according to an exemplary embodiment of the present specification, the photoinitiator is 2,4-trichloromethyl-(4'-methoxyphenyl)-6-triazine, 2,4-trichloromethyl-(4'-meth Toxystyryl)-6-triazine, 2,4-trichloromethyl-(piflonyl)-6-triazine, 2,4-trichloromethyl-(3',4'-dimethoxyphenyl)-6 -Triazine, 3-{4-[2,4-bis(trichloromethyl)-s-triazin-6-yl]phenylthio} propanoic acid, 2,4-trichloromethyl-(4'-ethyl ratio) Triazine-based compounds such as phenyl)-6-triazine or 2,4-trichloromethyl-(4'-methylbiphenyl)-6-triazine; 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl biimidazole or 2,2'-bis(2,3-dichlorophenyl)-4,4',5 Biimidazole-based compounds such as 5'-tetraphenylbiimidazole; 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxy Toxy)-phenyl (2-hydroxy)propyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenyl acetophenone, 2-methyl-(4-methylthiophenyl)-2-mole Acetopes such as polyno-1-propan-1-one (Irgacure-907) or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one (Irgacure-369) Non-based compounds; O-acyloxime compounds such as Irgacure OXE 01 and Irgacure OXE 02 from Ciba Geigy; Benzophenone-based compounds such as 4,4'-bis(dimethylamino)benzophenone or 4,4'-bis(diethylamino)benzophenone; Thioxanthone-based compounds such as 2,4-diethyl thioxanthone, 2-chloro thioxanthone, isopropyl thioxanthone, or diisopropyl thioxanthone; 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide or bis(2,6-dichlorobenzoyl) propyl phosphine oxide phosphine oxide-based compounds such as; 3,3'-carbonylvinyl-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 3-benzoyl-7-(diethylamino)coumarin, 3-benzoyl-7-methoxy-coumarin or 10,10'-carbonylbis[1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-Cl] -Coumarin-based compounds such as benzopyrano[6,7,8-ij]-quinolizin-11-one can be used alone or in combination of two or more, but are not limited to this.

Additionally, the heat initiator may be one known in the art.

Solvents that can be used include alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, and butanol, alkoxy alcohol-based solvents such as 2-methoxyethanol, 2-ethoxyethanol, and 1-methoxy-2-propanol, acetone, Ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, and cyclohexanone, propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether , ether-based solvents such as diethylene glycol monomethyl ether, diethyl glycol monoethyl ether, diethyl glycol monopropyl ether, diethyl glycol monobutyl ether, diethylene glycol-2-ethylhexyl ether, benzene, toluene, xylene Aromatic solvents such as can be used alone or in combination.

According to one embodiment of the present invention, the coating composition may include a photocurable binder. If the coating composition includes a photocurable binder, a UV curing process may be added when curing the coating composition. At this time, the amount of ultraviolet irradiation in the UV curing process may be 20 to 800 mJ/cm ² . The light source for ultraviolet irradiation is not particularly limited as long as it can be used in the technical field to which this technology belongs. For example, a high-pressure mercury lamp, metal halide lamp, black light fluorescent lamp, etc. can be used.

The coating composition of the present invention has low viscosity and good coating properties, so it can be used as a solvent-free type without a solvent. However, the use of organic solvents is not excluded, and if necessary, a small amount of organic solvents commonly used in the art may be included. At this time, the organic solvent may be used in an amount of about 20 parts by weight or less based on 100 parts by weight of the coating composition.

Meanwhile, according to one embodiment of the present invention, the coating composition may further include organic fine particles or inorganic fine particles to improve the hardness of the stretched coating layer. The particle size of the organic or inorganic fine particles may be 10 ㎛ or less in terms of appropriate haze and coating thickness, more specifically 10 nm to 10 ㎛, preferably 50 nm to 5 ㎛, more preferably 100 nm to 3 ㎛. It can be.

The organic fine particles or inorganic fine particles are not limited as long as they are of the type used to form the coating layer.

The organic fine particles may be one or more selected from organic fine particles consisting of acrylic resin, styrene resin, epoxy resin, and nylon resin.

More specifically, the organic fine particles include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and t-butyl (meth)acrylate. ) Acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, Polyethylene glycol (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, styrene, p- Methylstyrene, m-methylstyrene, p-ethylstyrene, m-ethylstyrene, p-chlorostyrene, m-chlorostyrene, p-chloromethylstyrene, m-chloromethylstyrene, styrenesulfonic acid, p-t-butoxystyrene, m-t-butoxystyrene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl ether, allyl butyl ether, allyl glycityl ether, (meth)acrylic acid, maleic acid, unsaturated carboxylic acid, alkyl (meth) It may be one or more selected from the group consisting of acrylamide, (meth)acrylonitrile, and (meth)acrylate, but the present invention is not limited thereto.

In addition, the organic fine particles include polystyrene, polymethyl methacrylate, polymethyl acrylate, polyacrylate, polyacrylate-co-styrene, polymethyl acrylate-co-styrene, polymethyl methacrylate-co-styrene, Polycarbonate, polyvinyl chloride, polybutylene terephthalate, polyethylene terephthalate, polyamide-based, polyimide-based, polysulfone, polyphenylene oxide, polyacetal, epoxy resin, phenolic resin, silicone resin, melamine resin, benzoate. At least one selected from amine, polydivinylbenzene, polydivinylbenzene-co-styrene, polydivinylbenzene-co-acrylate, polydiallyl phthalate and triallyl isocyanurate polymer, or two or more co A polymer (copolymer) may be used, but the present invention is not limited thereto.

In addition, the inorganic fine particles may be one or more selected from the group of inorganic fine particles consisting of silicon oxide, titanium dioxide, indium oxide, tin oxide, zirconium oxide, and aluminum oxide, but the present invention is not limited thereto.

The total content of the organic and inorganic fine particles may range from 0.1 to 20 parts by weight, preferably from 0.5 to 10 parts by weight, based on 100 parts by weight of the coating composition. If the total content of the organic and inorganic fine particles is less than 0.1 parts by weight based on 100 parts by weight of the cationic curable composition, the effect of improving hardness and scratch resistance is minimal, and if it exceeds 20 parts by weight, the viscosity of the coating composition is reduced. As this increases, coating properties become poor and the haze value due to internal scattering becomes too large, which may lower the contrast ratio.

Meanwhile, the coating composition of the present invention contains, in addition to the above-described components, surfactants, antioxidants, UV stabilizers, leveling agents, antifouling agents, antistatic agents, UV absorbers, antifoaming agents, preservatives, etc. commonly used in the technical field to which the present invention pertains. Additional additives may be included. In addition, the content can be variously adjusted within a range that does not deteriorate the physical properties of the coating composition of the present invention, and is not particularly limited, but may be included, for example, from about 0.1 to about 10 parts by weight based on 100 parts by weight of the total coating composition. there is.

In an exemplary embodiment of the present application, preparing a base film; Applying the coating composition on at least one side of a base film; and drying the coating composition.

In an exemplary embodiment of the present application, a method of manufacturing a polarizer protective film is provided, wherein the step of drying the coating composition includes drying the coating composition in an oven at 100° C. for 1 minute.

In an exemplary embodiment of the present application, after drying the coating composition, the step of stretching the base film to which the coating composition is applied is further included, and the stretching ratio in the stretching step is based on the width direction (TD). It provides a method for manufacturing a polarizer protective film with a polarizer protective film of 1.05 to 10 times.

In an exemplary embodiment of the present application, the stretching temperature in the step of stretching the base film may be 100°C or higher and 180°C or lower, preferably 110°C or higher and 160°C or lower, and more preferably 120°C or higher and 160°C or lower. .

In an exemplary embodiment of the present application, a method for manufacturing a polarizer protective film is provided, further comprising stretching the base film before applying the coating composition on one surface of the base film.

By applying the coating before the final process through a process of uniaxially stretching the base film before applying the coating composition, the roll pass can be minimized and roll contamination can be prevented.

The method of applying the coating composition is not particularly limited as long as it can be used in the technical field to which this 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 can be used.

In particular, the step of applying the coating composition includes bar coating; gravure coating; Alternatively, a method for manufacturing a polarizer protective film comprising a slot die coating process is provided.

If the base film is uniaxially stretched before applying the coating composition, it is preferable that the stretching direction after coating is perpendicular to the stretching direction before applying the coating composition. For example, if the base film is stretched in the longitudinal (MD) direction before applying the coating composition, it can be stretched in the width (TD) direction after applying the coating composition.

In addition, when stretching is performed before and after applying the coating composition, the total stretching ratio is 1.1 times or more, 1.2 times or more, or 1.5 times or more, and 25 times or less, or 10 times or more, based on the total stretched area of the base film. It can be stretched to be 2 times or less, or 7 times or less. If the stretching ratio is less than 1.1 times, the stretching effect may not be sufficiently achieved, and if it exceeds 25 times, the coating layer may crack.

In an exemplary embodiment of the present application, a base film; and a protective film containing the coating composition or a cured product thereof on one surface of the base film.

The base film is not particularly limited, but may include polyester, polyethylene, cyclic olefin polymer (COP), cyclic olefin copolymer (COC), and polyacrylate. , PAC), polycarbonate (PC), polymethylmethacrylate (PMMA), polyimide (PI), or cellulose, etc. can be used.

In an exemplary embodiment of the present application, the thickness of the polarizer protective film may be 1 μm or more and 200 μm or less.

The thickness of the base film is not particularly limited, but considering the stretching process, a film having a thickness of about 50 to 1,000 μm, specifically 100 to 500 μm, can be used.

The forming method of the base film is also not particularly limited, and the unstretched base film can be prepared by an appropriate film forming method such as solution casting, melt extrusion, calendering, or compression molding.

When stretching the base film, polymers are rearranged during the stretching process, which causes a problem in that adhesion is reduced when an attempt is made to additionally form a functional coating layer on the stretched base film. Therefore, there is a plan to add a separate process such as forming a primer layer to ensure adhesion, or to include a functional compound that can improve adhesion in the coating layer. In this case, a separate process is added in the manufacturing process to increase productivity. There is a problem of this decline, and the physical and chemical properties of each film are different, making it difficult to develop a general-purpose primer. Additionally, adding functional compounds to the coating layer may also increase cost and decrease other physical properties.

Accordingly, the present invention solves this problem, and according to an embodiment of the present invention, it is possible to provide a polarizer protective film that has sufficient scratch resistance and can be reduced in thickness even without a separate primer layer.

According to an exemplary embodiment of the present invention, the coating composition according to the present application can be applied to one surface of the base film in an unstretched state.

In another exemplary embodiment, the base film may be uniaxially stretched before applying the coating composition.

In an exemplary embodiment of the present application, a polarizer; and a polarizer protective film according to an exemplary embodiment of the present application on at least one surface of the polarizer.

The polarizer exhibits the characteristic of being able to extract only light vibrating in one direction from the light that is incident while vibrating in various directions, and the polarizer protective film of the present invention is used to protect the polarizer from the outside, and at least one surface of the polarizer. It is preferably used as a lower protective film of the polarizer.

Meanwhile, as liquid crystal displays become larger and slimmer, the lower polarizer sags and the lower protective film of the lower polarizer comes into contact with the backlight unit, causing scratches.

Accordingly, the polarizer protective film obtained by the manufacturing method of the present invention exhibits excellent physical properties such as scratch resistance and high hardness due to the stretched coating layer, effectively protecting the lower polarizer, and is useful for polarizers for liquid crystal displays that are increasingly becoming thinner and larger. It can be applied easily.

At this time, the polarizer is not particularly limited, and a polarizer well known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye, is used.

A polarizer exhibits the characteristic of being able to extract only light vibrating in one direction from light that is incident while vibrating in various directions. These properties can be achieved by stretching polyvinyl alcohol (PVA), which has absorbed iodine, under strong tension. For example, more specifically, swelling the PVA film by soaking it in an aqueous solution, dyeing the swollen PVA film with a dichroic material that imparts polarization, and stretching the dyed PVA film. ) to form a polarizer through a stretching step of arranging the dichroic dye material side by side in the stretching direction, and a complementary color step of correcting the color of the PVA film that has undergone the stretching step. However, the polarizing plate of the present invention is not limited to this.

According to one embodiment of the present invention, the polarizer protective film can be attached to both sides of the polarizer.

When laminating and adhering the polarizer protective film of the present invention to a polarizer, it is preferable that the base film is attached to the polarizer.

According to another embodiment of the present invention, the polarizer protective film may be provided on only one side of the polarizer, and a general-purpose protective film commonly used to protect the polarizer may be provided on the other side.

At this time, the polarizer can be used as a lower polarizer of the LCD, and in the laminated structure within the LCD, the polarizer protective film of the present invention can be positioned at the bottom.

As described above, when a polarizing plate is laminated on an LCD with the protective film as the bottom, excellent optical properties can be achieved by preventing the problem of haze increasing due to damage to the lower protective film of the polarizing plate when it comes in contact with the backlight unit provided below the polarizing plate. .

The polarizer and the protective film can be bonded to each other by lamination using an adhesive or the like. Adhesives that can be used 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)-based adhesives, polyurethane-based adhesives, epoxy-based adhesives, styrene butadiene rubber (SBR-based) adhesives, or hot melt adhesives, but the present invention It is not limited to these examples.

When laminating and adhering the polarizer protective film of the present invention to a polarizer, it is preferable to attach it to the polarizer on the side on which the stretched coating layer is not formed, and to place the stretched coating layer on the outside of the polarizer.

The polarizer including the polarizer protective film of the present invention has been described as being applied to LCDs as an example, but is not limited thereto and can be utilized in various fields. For example, it can be used for mobile communication terminals, smartphones, other mobile devices, display devices, electronic whiteboards, outdoor electronic signboards, and various displays. According to an embodiment of the present invention, the polarizer may be a polarizer for TN (Twisted Nematic), STN (Super Twisted Nematic) liquid crystal, and may be used for IPS (In-Plane Switching), Super-IPS, FFS (Fringe Field Switching), etc. It may be a polarizing plate for horizontal alignment mode, or it may be a polarizing plate for vertical alignment mode.

In one embodiment of the present application, a liquid crystal cell; an upper polarizer provided on the upper layer of the liquid crystal cell; a lower polarizer provided on the lower layer of the liquid crystal cell; and a backlight unit provided on a lower portion of the lower polarizer, wherein the lower polarizer includes a polarizer; and a polarizer protective film according to an exemplary embodiment of the present application disposed on one or both sides of the polarizer.

In an exemplary embodiment of the present application, a liquid crystal display device is provided in which the polarizer protective film is disposed to face the backlight unit.

1 is a diagram showing a liquid crystal display device including a polarizer protective film obtained by the manufacturing method of the present invention.

The backlight unit includes a light source that irradiates light from the back of the liquid crystal panel. The type of the light source is not particularly limited, and general LCD light sources such as CCFL, HCFL, or LED can be used.

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, these examples are merely presented as examples of the invention, and the scope of the invention is not determined by them.

< Example >

< Manufacturing example 1>

Copolymerized with a composition of methyl methacrylate/ethyl acrylate/methyl methacrylic acid=60/10/30, Mw 18k, Tg 112℃ acid value=205 mgKOH/g 100 g of phosphorus polymer was dispersed in 859.3 g of distilled water, 40.7 g of trimethylamine was added dropwise, and the mixture was stirred at room temperature (25°C) for 18 hours to prepare colorless and transparent polymer solution 1.

< Manufacturing example 2>

100 g of Crayvalley's SMA3000 (Mw 9500, Mn 3800, Tg 125°C acid value 285 mgKOH/g) of styrene/maleic anhydride = 3/1 composition was dispersed in 843.5 distilled water and mixed with triethylamine. ) 56.5 g was added dropwise and stirred at 85°C for 3 days to prepare colorless and transparent polymer solution 2.

< Manufacturing example 3 >

Add 100g of Scripset® 520 (styrene/maleic anhydride=1/1, Mw 350,000, Tg 140~150℃ acid value 405 mgKOH/g) into 18197g of distilled water and add triethylamine to 80.3%. g was added dropwise and stirred at room temperature (25°C) for 3 hours and then stirred at 85°C for 18 hours to prepare polymer 3 dissolved in water.

< Manufacturing example 4 >

Add 100g of Aldrich's poly(octadecene-alt-maleic anhydride), octadec-1-ene/maleic anhydride=1/1, Mw 30k~50k, acid value 310~315 mgKOH/g) into 836.5g of distilled water and add triethylamine ( Polymer 4 dissolved in water was prepared by dropping 63.53 g of trimethylamine) and stirring at room temperature (25°C) for 18 hours.

< Manufacturing example 5 >

Composition of methyl methacrylate/ethyl acrylate/methyl methacrylic acid=45/35/20, Mw 80k, Tg 100℃ acid value=120 mgKOH/g) 100 g of the polymerized polymer was added to 859.6 g of distilled water, 23.8 g of trimethylamine was added dropwise, and the mixture was stirred at room temperature (25°C) for 18 hours to prepare colorless and transparent polymer 5 dissolved in water.

Example 1 to 10 and Comparative example 1 to 3

An unstretched film with a width of 800 mm and a thickness of 200 μm was manufactured using polymethyl methacrylate resin using a T-die film forming machine under 250°C conditions. The unstretched film was stretched 1.8 times in the longitudinal (MD) direction at a temperature of 135°C to prepare a uniaxially stretched film.

The coating composition was prepared by adding distilled water, organic particle dispersion, aqueous additive solution, water-soluble polyurethane dispersion (PU147 or WS4000), and oxazoline-based curing agent (WS700) in that order and stirring at room temperature for 1 hour (see Table 1). .

The above coating composition was coated on the surface of the uniaxially stretched film treated three times at 5V with a corona processor using bar coating method three times, dried at 100°C for 1 minute, and then applied to the surface at 130°C for width (TD). ) direction to prepare a protective film with a coating thickness of 0.3㎛ by stretching 2.5 times.

Example
One Example
2 Example
3 Example
4 Example
5 Example
6 Example
7 Example
8 Example
9 Example
10 Comparative example One Comparative example 2 Comparative example 3 PU147 85 80 75 90 80 80 84 85 75 - 90 90 90 WS4000 - - - - - - - - - 90 - - - WS700 10 10 10 10 5 10 15 5 15 5 10 10 10 Manufacturing example One 5 10 15 20 - - - - - - - - - Manufacturing example 2 - - - - 15 10 - - - 15 - - - Manufacturing example 3 - - - - - - One - - - - - - Manufacturing example 4 - - - - - - - 10 10 - - - - Manufacturing example 5 - - - - - - - - - - - 10 20 MP2701 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 ML160 5 5 5 5 5 5 5 5 5 5 5 5 5

In Table 1, each value represents a weight ratio.

In Table 1, MP2701 is Soken's 0.4㎛ (+) charged non-crosslinked acrylic particle, and ML160 is a carnauba wax emulsion.

<Method for measuring physical properties>

The physical properties of the polarizer protective films of the Examples and Comparative Examples in Table 1 were measured by the following method.

One) Scratch resistance (Gallim and Scratchability evaluation)

The coating layer and diffusion sheet of the polarizer protective film of the Examples and Comparative Examples of Table 1 were placed in contact with each other on a sample holder (50 mm 2.8 Grms, frequency 20-60Hz) was applied for 240 seconds. Afterwards, the scratch resistance was evaluated by determining whether scratches and cracks occurred on the coating layer of the polarizer protective film and the surface of the diffusion sheet. If no scratches or grinding occurred, it was marked as ◎, if there were grinding marks or scratches on the primer surface, it was marked as O, and if there were grinding marks or scratches on the primer surface, it was marked as X.

2) Adhesion

Based on ASTM D3359, on the coating layer of the polarizer protective film of the examples and comparative examples in Table 1, 100 (10 : Nichiban), peeled off, and counted the number of coating layers that fell together with the tape. If there were 0 to 5 missing cells, it was evaluated as 5B, and if there were 6 or more missing cells, it was evaluated as X.

3) Antiblocking castle

Antiblocking property was indicated as OK when 10 sheets of 5cm

The physical property measurement results for the polarizer protective films of the Examples and Comparative Examples in Table 1 are shown in Table 2 below.

Example
One Example
2 Example
3 Example
4 Example
5 Example
6 Example
7 Example
8 Example
9 Example
10 Comparative example One Comparative example 2 Comparative example 3 Coating thickness (㎛) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Haze( % ) 1.4 1.3 1.4 1.3 1.8 1.2 3.0 1.1 1.0 1.8 1.3 2.3 5.7 fork ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ O O O scratch ◎ O ◎ O O ◎ ◎ O O O X X X antiblocking OK OK OK OK OK OK OK OK OK OK OK OK OK adhesion 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B

In Table 2, if there are no grinding marks or scratches on the primer surface, it is marked as ◎, if there are grinding marks or scratches on the primer surface, it is marked as O, and if there are grinding marks or scratches on the primer surface, it is marked as X.

The present invention is intended to solve the problem of damage to the polarizer protective film of the lower polarizer, and provides a coating composition with excellent coating properties, a polarizer protective film with scratch resistance, a polarizer having excellent physical and optical properties including the same, and a liquid crystal display device. We would like to provide

As can be seen from Tables 1 and 2, the coating composition according to the present invention includes a polymer with an acid value of 200 mgKOH/g or more, and the coating composition containing this is combined with an oxazoline-based curing agent when used as a polarizer protective film. It was confirmed that it had characteristics that could increase the splitting characteristics.

In addition, when the polarizer protective film containing the coating composition is used as a protective film for the lower polarizer, the polarizer protective film may be damaged when it comes into contact with the diffusion sheet on the surface of the backlight unit due to sagging of the lower polarizer, which may cause device defects. It was confirmed that excellent optical properties could be achieved by preventing potential problems.

In the case of Comparative Examples 1 and 3 in Table 2 above, the polymer with an acid value of 200 mgKOH/g or more according to the present application was not included, and it was confirmed that the grinding characteristics and scratch resistance were poor. Accordingly, it was confirmed that it did not function as a polarizer protective film.

In the case of Comparative Example 2 of Table 2 above, which included a polymer with an acid value of less than 200 mgKOH/g, it was confirmed that the grinding characteristics and scratch resistance were similarly poor, and thus it was confirmed that it did not serve as a polarizer protective film. I was able to. In addition, in the case of Comparative Example 3 of Table 2, as in Comparative Example 2, a polymer with an acid value of less than 200 mgKOH/g was included, and scratch resistance was improved even when the content of the polymer with an acid value of less than 200 mgKOH/g was increased. It was confirmed that there was none. That is, the coating composition according to the present invention is characterized in that it contains a polymer with an acid value of 200 mgKOH/g or more, and it was confirmed that the polarizer protective film containing the same has excellent cracking characteristics and scratch resistance.

10: upper polarizer
20: liquid crystal cell
30: lower polarizer
34: Polarizer protective film
40: backlight unit

Claims (16)

Anionic polyurethane resin;
A polymer with an acid value of 200 mgKOH/g or more; and
Oxazoline-based curing agent;
A coating composition containing,
A coating composition comprising 1 to 30 parts by weight of a polymer having an acid value of 200 mgKOH/g or more, based on 100 parts by weight of the coating composition. In claim 1,
A coating composition in which the anionic polyurethane resin is contained in an amount of 60 parts by weight or more and 95 parts by weight or less based on 100 parts by weight of the coating composition. In claim 1,
A coating composition in which the oxazoline-based curing agent is contained in an amount of 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the coating composition. In claim 1,
The polymer includes a monomer containing carboxylic acid; And a coating composition comprising at least one selected from the group consisting of monomers containing phenol. In claim 1,
A coating composition wherein the polymer has a weight average molecular weight of 1,000 g/mol or more and 5,000,000 g/mol or less. In claim 1,
The coating composition includes an aqueous wax dispersion; particulate; menstruum; dispersant; photoinitiator; ten-initial tense; crosslinking agent; And a tackifier; a coating composition comprising at least one selected from the group consisting of. Preparing a base film;
Applying the coating composition of any one of claims 1 to 6 on at least one side of a base film; and
drying the coating composition;
Method for manufacturing a polarizer protective film comprising. In claim 7,
After drying the coating composition,
Further comprising stretching the base film to which the coating composition is applied,
A method of manufacturing a polarizer protective film wherein the stretching ratio in the stretching step is 1.05 to 10 times based on the width direction (TD). In claim 7,
The step of applying the coating composition includes bar coating; gravure coating; Or a method of manufacturing a polarizer protective film comprising a slot die coating process. In claim 7,
A method of producing a polarizer protective film further comprising stretching the base film before applying the coating composition on at least one surface of the base film. base film; and
A protective film comprising the coating composition of any one of claims 1 to 6 or a cured product thereof on one surface of the base film;
A polarizer protective film containing a. In claim 11,
The base film is polyester, polyethylene, cyclic olefin polymer (COP), cyclic olefin copolymer (COC), polyacrylate (PAC), poly A polarizer protective film containing polycarbonate (PC), polymethylmethacrylate (PMMA), polyimide (PI), or cellulose. In claim 11,
The polarizer protective film has a thickness of 1 μm or more and 200 μm or less. polarizer; and
A polarizing plate comprising the polarizer protective film of claim 11 on at least one surface of the polarizer. liquid crystal cell;
an upper polarizer provided on the upper layer of the liquid crystal cell;
a lower polarizer provided on the lower layer of the liquid crystal cell; and
It includes a backlight unit provided on a lower layer of the lower polarizer,
The lower polarizer is a polarizer; and the polarizer protective film of claim 11 disposed on one or both sides of the polarizer. In claim 15,
The liquid crystal display device wherein the polarizer protective film is disposed to face the backlight unit.