KR20210132808A - Coating composition, optical protecting film, manufacturing method of optical protecting film, polarizing plate comprising same and liquid crystal display device comprising same - Google Patents

Abstract

The present invention relates to a coating composition, an optical protective film, a method for manufacturing the optical protective film, a polarizing plate comprising the same, and a liquid crystal display including the same. In particular, the present invention is to provide a coating composition which is to solve the damage to the optical protective film of upper and lower polarizing plates and has excellent coating ability, the optical protective film having high surface hardness and scratch resistance, and a polarizing plate and a liquid crystal display having excellent physical and optical properties.

Description

Coating composition, optical protective film, manufacturing method of optical protective film, polarizing plate comprising same, and liquid crystal display including same TECHNICAL FIELD SAME}

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

Based on the recent development of optical technology, plasma display panel (PDP), liquid crystal display (LCD), organic light emitting diodes (OLED), Display devices using the method have been proposed and marketed. Recently, the characteristics required for these display devices are becoming more advanced, and accordingly, the characteristics required for peripheral components such as optical films applied to the display devices are also being advanced.

Liquid crystal displays are widely used from mobile phones and portable small electronic devices to large electronic devices such as personal computers and televisions, and their use is one of the flat panel displays that are gradually expanding.

Since such a liquid crystal display device is not a self-emission type device, a light source such as a backlight unit is placed on the back surface of a lower polarizing plate 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 transmit liquid crystal molecules. The image is displayed by changing the arrangement of

Recently, liquid crystal display devices have grown in size and are being transported as they are slimmed down, or a lot of load is applied to the middle of the liquid crystal cell during use, causing the lower polarizing plate to sag. When the backlight unit comes in contact with the diffusion sheet, the lower polarizing plate is damaged, and the like. In order to solve this problem, a method of coating a hard coating layer on the protective film of the lower polarizing plate has been proposed, but there is a problem of increasing the process cost.

One side of a general optical protective film used for LCD and OLED may include various functional coating layers such as an anti-reflection layer and a hard coating layer on the opposite side of the side to which the polarizer is attached for the purpose of preventing reflection, improving durability, preventing scratches, and improving visibility. In general, such a functional coating layer is formed by applying a composition including a base resin, a solvent, an additive, etc. on an optical protective film and then curing the composition.

However, in the case of the aqueous coating layer on the acrylic film to impart slip properties with the acrylic film used as the base film of the optical protection film, the functional coating layer is not coated well due to poor solvent resistance, or the film surface is melted and damaged when the functional coating layer is formed There are problems such as In addition, in the case of an acrylic base film, since the surface friction force is higher than that of films of other materials, the slip property during winding is poor, and workability is poor, and there is a problem in that a blocking phenomenon occurs in which the film and the film surface are stuck after winding. .

In addition, damage to the film may occur due to friction between the films due to various causes, such as a diversification of the winding slitting width and an increase in the winding amount during the manufacture of the optical protection film.

According to this necessity, there is a need to develop a method that can prevent damage and haze increase of the upper and lower polarizers caused by the lower structure while maintaining price competitiveness during mass production by securing productivity, and improving cracks and scratches in the process This is possible, and there is a demand for an optical protective film coating material having low refraction properties to improve chemical resistance and optical properties of the functional coating layer.

Korean Publication No. 2012-0107256

The present invention is to solve the damage to the polarizer protective film of the upper and lower polarizing plates, a coating composition having excellent coatability, an optical protective film having high surface hardness and scratch resistance, and excellent physical and optical properties including the same A polarizing plate and a liquid crystal display are provided.

An exemplary embodiment of the present application is a polyester urethane water dispersion binder resin comprising a urethane repeating unit formed through the reaction of an aliphatic isocyanate and a polyol having two or more NCO groups in the main chain; titanate-based crosslinking agent; And as a coating composition comprising water-dispersible fine particles, it provides a coating composition comprising 0.1 parts by weight or more and 10 parts by weight or less of the titanate-based crosslinking agent based on 100 parts by weight of the water-dispersible binder resin.

Another exemplary embodiment includes the steps of preparing a base film; applying the coating composition according to the present application on at least one surface of the base film; and drying the coating composition.

Another exemplary embodiment is a base film; and a protective film including a coating composition according to the present application or a cured product thereof on one surface of the base film.

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

Finally, an exemplary embodiment of the present application is a liquid crystal cell; an upper polarizing plate provided in the upper layer of the liquid crystal cell; a lower polarizing plate provided in the lower layer of the liquid crystal cell; and a backlight unit provided in a lower layer of the lower polarizing plate, wherein the upper and lower polarizing plates include: a polarizer; and an optical protective film according to the present application disposed on one or both surfaces of the polarizer.

In particular, the present invention is to solve the damage of the optical protective film of the upper and lower polarizing plates, a coating composition having excellent coating properties, an optical protective film having high surface hardness and scratch resistance, and excellent physical and optical properties including the same An object of the present invention is to provide a polarizing plate and a liquid crystal display having

In the coating composition according to the present invention, as the polyester urethane aqueous dispersion binder resin is formed through the reaction of an aliphatic isocyanate and a polyol having two or more NCO groups in the main chain, the protective film comprising the same later has a refractive index that satisfies a specific range, By lowering the difference in refractive index between the base film of the protective film and the functional coating layer positioned on the upper portion of the optical protective film, optical properties are excellent. In addition, the protective film including the coating composition according to the present application has excellent chemical resistance of the protective film as chemical resistance by a solvent is imparted to the functional coating layer.

In addition, as the coating composition according to the present application has the above composition and content, the friction coefficient is high and the specific gravity is low, so the solution stability of the composition is excellent. It is characterized by not

In addition, since the optical protective film including the coating composition is used as a protective film for the upper and lower polarizing plates, the optical protective film is damaged by contact with the diffusion sheet on the surface of the backlight unit due to the sagging of the lower polarizing plate, thereby preventing device failure. By preventing problems that may be caused, excellent optical properties can be exhibited.

Finally, the protective film including the coating composition according to the present application can prevent film breakage and damage due to friction between films that occur due to various causes such as diversification of winding slitting width and increase in winding amount. Therefore, it is possible to reduce the cost of defects and secure productivity.

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 embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiment of the present invention is provided in order to explain the present invention in more detail to those with ordinary knowledge in the art.

An exemplary embodiment of the present application is a polyester urethane water dispersion binder resin comprising a urethane repeating unit formed through the reaction of an aliphatic isocyanate and a polyol having two or more NCO groups in the main chain; titanate-based crosslinking agent; And a coating composition comprising water-dispersible fine particles, including 0.1 parts by weight or more and 10 parts by weight or less of the titanate-based crosslinking agent based on 100 parts by weight of the water-dispersible binder resin, and an optical protective film having excellent grinding properties, haze properties and slip properties has the ability to create

In particular, the optical protective film is composed of a base film and a protective film including the coating composition according to the present application, and a functional coating layer may be formed on the opposite side of the base film on which the protective film is laminated. The protective film included in the optical protective film has excellent optical properties by lowering the refractive index difference between the functional coating layer and the base film.

The present invention relates to an optical protective film adjacent to a backlight unit of a lower polarizing plate provided in a lower layer of a liquid crystal cell in a liquid crystal display device, and the protective film included in the polarizer protective film includes the coating composition according to the present application. The polarizer protective film of the present invention has a characteristic particularly excellent in breaking properties.

In addition, the optical protective film prepared from the coating composition of the present invention can prevent damage that may occur due to sagging of the lower polarizing plate, in particular.

1 shows an embodiment of a liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 1 includes a liquid crystal cell 20; an upper polarizing plate 10 provided in 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 layer of the lower polarizing plate, wherein the lower polarizing plate 30 is provided with an optical protective film 34 according to the present invention on a surface adjacent to the backlight unit, and the upper portion of the lower polarizing plate 30 An optical protective film 35 according to the present invention may be provided on the opposite surface of the polarizing plate 10 in contact with the liquid crystal cell 20 .

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

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

An exemplary embodiment of the present application is a polyester urethane water dispersion binder resin comprising a urethane repeating unit formed through the reaction of an aliphatic isocyanate and a polyol having two or more NCO groups in the main chain; titanate-based crosslinking agent; And as a coating composition comprising water-dispersible fine particles, it provides a coating composition comprising 0.1 parts by weight or more and 10 parts by weight or less of the titanate-based crosslinking agent based on 100 parts by weight of the water-dispersible binder resin.

In particular, the coating composition according to the present invention includes a urethane repeating unit formed through the reaction of a polyol and an aliphatic isocyanate having two or more NCO groups in the main chain of the water-dispersible binder resin. It can be adjusted, and thus has excellent optical properties. In addition, by applying a coating composition containing a specific composition and content, the surface hardness and slip property of the protective film including the same can be improved, and the coating composition itself has a high coefficient of friction and a low specific gravity, so that the composition has excellent solution stability, It is characterized in that when the protective film is formed through the coating composition, problems such as film separation do not occur.

In addition, the polyester urethane water dispersion binder resin according to the present invention has excellent chemical resistance characteristics because it contains a polyester type, and has excellent coating and stretchability characteristics because it contains a urethane type.

In an exemplary embodiment of the present application, the polyester urethane aqueous dispersion binder resin may include a urethane repeating unit formed through the reaction of an aliphatic isocyanate having two or more NCO groups in the main chain and a polyol.

The polyester urethane water dispersion binder resin comprising a urethane repeating unit formed through the reaction of an aliphatic isocyanate having two or more NCO groups in the main chain and a polyol may be expressed as a polyester urethane water dispersion binder resin having a unit derived from an aliphatic isocyanate. have.

That is, the polyester urethane water dispersion binder resin according to the present application has at least one unit derived from an aliphatic isocyanate in the resin, and a polyester urethane water dispersion binder resin having at least one unit derived from an aliphatic isocyanate in the resin. can be expressed as

In particular, the coating composition according to the present application uses an aliphatic isocyanate, which is hexamethylene diisocyanate (HMDI), isoprondiisocyanate (IPDI), dicyclohexylmethylene-4,4-diisocyanate (H12MDI) ( Dicyclohexylmethane-4,4'-diisocyanate), 2,2,4-trimethyl-1,6-hexane diisocyanate (2,2,4-Trimethyl-1,6-hexane diisocyanate, TMDI), pentamethylene diisocyanate ( PDI) and transcyclohexane-1,4-diisocyanate may be at least one selected from the group consisting of.

That is, the polyester urethane aqueous dispersion binder resin according to the present application has at least one unit derived from an aliphatic isocyanate in the resin, and unlike the case of using an aromatic isocyanate, it has a characteristic that can have a desired refractive index range.

The coating composition according to an exemplary embodiment of the present application is formed through the reaction of an aliphatic isocyanate and a polyol as described above, and the refractive index of the protective film including the same later satisfies a specific range, thereby protecting the base film and optical protection of the optical protective film By lowering the refractive index difference with the functional coating layer positioned on the upper part of the film, it has excellent optical properties. That is, when the aliphatic isocyanate is not used, the protective film including the same has a high refractive index, and when used as an optical protective film in the future, optical properties may be impaired due to a difference in refractive index with the lower layer.

In an exemplary embodiment of the present application, the polyol provides a coating composition that is at least one selected from the group consisting of polyester-based polyols, polycarbonate-based polyols, polyether polyols, and polyacrylic polyols.

In the exemplary embodiment of the present application, the polyol may be a polyester-based polyol.

In an exemplary embodiment of the present application, the polyester-based polyol can be obtained by reacting a polybasic acid component with a polyol component, and in this case, as the polybasic acid component, for example, ortho-phthalic acid, isophthalic acid, terephthalic acid, 1,4 -Aromatic dicarboxylic acids, such as naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6- naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetrahydrophthalic acid; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, linoleic acid, maleic acid, fumaric acid, mesaconic acid and itaconic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; or reactive derivatives such as acid anhydrides, alkyl esters, and acid halides thereof, but is not limited thereto, and these may be used alone or in combination of two or more.

In an exemplary embodiment of the present application, the polycarbonate-based polyol may be obtained by reacting a compound having a carbonate group with a polyol component, and in this case, the compound having a carbonate group is, for example, diphenyl carbonate, dialkyl carbonate, alkyl ren carbonate and the like.

In an exemplary embodiment of the present application, the polyether polyol can be obtained by adding an alkylene oxide to a polyol component by ring-opening polymerization.

In the exemplary embodiment of the present application, the polyol component is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any suitable polyol may be employed. For example, as the polyol, ethylene glycol, 1,2-propanonediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neolpentyl glycol, pentanediol, 1,6- Hexanediol, 1,8-octanediol, 1,10-decanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxymethylmethane, diethylene glycol, triethylene glycol, polyethylene glycol ( PEG), dipropylene glycol, polytetramethylene glycol (PTMG), polypropylene glycol (PPG), 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, glycerin, 1,1 , It may be at least one selected from the group consisting of 1-trimethylolpropane, 1,2,5-hexatriol, pentaerythriol, glucose, sucrose, and sorbitol.

In an exemplary embodiment of the present application, the polyester urethane aqueous dispersion binder resin includes an ester-based repeating unit and a urethane-based repeating unit, and the equivalent ratio of the polyol and the aliphatic isocyanate is, for example, 2:1 to 1:2 may be, preferably from 1.5:1 to 1:1.5, more preferably from 1.2:1 to 1:1.2. When the equivalence ratio satisfies the above numerical range, the appearance characteristics of the coating layer formed by using the coating composition including the same are very excellent, and properties such as adhesion to the substrate and solvent resistance can be further improved.

In an exemplary embodiment of the present application, the titanate-based crosslinking agent is tetraisopropyl titanate, tetranol butyl titanate, butyl titanate dimer, tetraoctyl titanate, titanium acetyl acetate, titanium tetraacetyl acetate, titanium ethyl At least one selected from the group consisting of acetacetate, titanate phosphate, titanium octylene glycolate, titanium ethyl acetacetate, titanium lactate, titanium triethanolaminate, titanium dodecylbenzenesulfonic acid, and titanium aminoethylaminoethanoate A coating composition is provided.

In an exemplary embodiment of the present application, the titanate-based crosslinking agent may be titanium triethanolaminate.

In an exemplary embodiment of the present application, 0.1 parts by weight or more and 10 parts by weight or less of the titanate-based crosslinking agent may be included based on 100 parts by weight of the water-dispersible binder resin.

In another exemplary embodiment, 0.1 parts by weight or more and 10 parts by weight or less of the titanate-based crosslinking agent based on 100 parts by weight of the water-dispersible binder resin, preferably 0.5 parts by weight or more and 10 parts by weight or less, more preferably 1 part by weight It may be more than 10 parts by weight or less.

As described above, since the coating composition according to the present application contains a titanate-based crosslinking agent in a specific amount, the friction coefficient is high and the specific gravity is low, so the solution stability of the composition is excellent. It does not occur, has excellent grinding properties and hardness, and has excellent solvent resistance.

In an exemplary embodiment of the present application, the water-dispersible fine particles provide a coating composition that is at least one selected from the group consisting of silica, titania, alumina, zirconia, a wax aqueous dispersion, and fluorine-based fine particles.

In an exemplary embodiment of the present application, the silica may have an average particle diameter of 10 nm or more and 500 nm or less.

In an exemplary embodiment of the present application, the silica may have an average particle diameter of 10 nm or more and 500 nm or less, and an average particle diameter of 10 nm or more and 300 nm or less, and preferably, an average particle diameter of 30 nm or more and 100 nm or less.

In the exemplary embodiment of the present application, spherical silica may be used as the silica, and a non-reactive surface treatment may be performed.

In particular, the silica may serve to increase the strength of the water-dispersed binder resin lacking in grinding characteristics or hardness. In addition, since silica is excellent in blocking inhibition ability and excellent in transparency, it hardly generates haze and there is no coloring, it has a small effect on the optical properties of the polarizing plate in the future. In addition, since colloidal silica has good dispersibility and dispersion stability with respect to the water-dispersible coating composition, workability at the time of forming the coating layer is also more excellent.

In an exemplary embodiment of the present application, the aqueous wax dispersion is polyethylene wax; amide wax; 1 selected from the group consisting of Carnauba wax, Fischer-Tropsch wax, Paraffin-wax, polypropylene (PP, Polypropylene) wax, HDPE (High density polyethylene) Wax, Ethylene bis (stearamide), and PTFE (Polytetrafluoroethylene) wax may include more than one.

In an exemplary embodiment of the present application, the fluorine-based fine particles are made of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF). It may include one or more selected from the group.

In an exemplary embodiment of the present application, the water-dispersible fine particles preferably have an average diameter (average primary particle diameter) of about 50 nm to 500 nm or about 100 nm to 300 nm. When the average diameter of the water-dispersible fine particles satisfies the above numerical range, the stability of the coating solution is excellent, and the haze is low because the dispersion is even in the solution. In addition, by using fine particles having a particle diameter in the above range, irregularities are appropriately formed on the surface of the coating layer, and in particular, the frictional force on the contact surface between the acrylic film and the coating layer, the contact surface between the coating layers, etc. can be effectively reduced. As a result, the blocking inhibitory ability may be more excellent.

In an exemplary embodiment of the present application, the water-dispersible fine particles provide a coating composition that is 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the water-dispersible binder resin.

In another exemplary embodiment, the water-dispersible fine particles are 1 part by weight or more and 20 parts by weight or less, preferably 5 parts by weight or more and 18 parts by weight or less, more preferably 10 parts by weight based on 100 parts by weight of the water-dispersible binder resin. It may be more than 15 parts by weight or less.

In the present application, when the water-dispersible fine particles include the content portion, it has a feature capable of preventing blocking or scratching during winding and running during the process.

In an exemplary embodiment of the present application, the weight average molecular weight of the fluorinated ethylene propylene (FEB, Fluorinated ethylene propylene) is 1x10 ⁴ g/mol or more and 1x10 ⁶ g/mol or less It provides a coating composition.

The weight average molecular weight is one of the average molecular weights for which the molecular weight is not uniform and the molecular weight of a certain polymer material is used as a reference, and is a value obtained by averaging the molecular weights of component molecular species of a polymer compound having a molecular weight distribution by weight fraction.

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

As the coating composition according to the present application contains fluorinated ethylene propylene (FEB) and the weight average molecular weight of the fluorinated ethylene propylene (FEB) has the above range, liquid dispersion stability is In particular, it has excellent characteristics.

According to an embodiment of the present invention, the coating composition may include a thermosetting binder. When the coating composition includes a thermosetting binder, a thermosetting step of at least a certain temperature is required during curing of the coating composition.

The coating composition may be used together with a photocuring initiator by applying a photocurable binder. In this case, a UV curing process may be additionally required after the drying step, and the UV irradiation amount of the UV curing process may be 20 to 800 mJ/cm ² . The light source of the ultraviolet irradiation is not particularly limited as long as it can be used in the technical field to which the present technology belongs, and for example, a high-pressure mercury lamp, a metal halide lamp, a black light fluorescent lamp, etc. may be used.

The coating composition of the present invention has a low viscosity and good coating properties, so that it can be used as a solvent-free type without a solvent. However, the use of an organic solvent is not excluded, and, if necessary, an organic solvent generally used in the art may be included in a small amount. In this case, 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.

Examples of usable organic solvents include alcohol solvents such as methanol, ethanol, isopropyl alcohol and butanol, alkoxy alcohol solvents such as 2-methoxyethanol, 2-ethoxyethanol, and 1-methoxy-2-propanol, and acetone. , methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, ketone solvents such as cyclohexanone, propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl Ether solvents such as ether, diethylene glycol monomethyl ether, diethyl glycol monoethyl ether, diethyl glycol monopropyl ether, diethyl glycol monobutyl ether, diethylene glycol-2-ethylhexyl ether, benzene, toluene, xyl An aromatic solvent such as ren may be used alone or in combination.

On the other hand, according to an embodiment of the present invention, the coating composition may further include organic or inorganic fine particles in order to improve the hardness of the stretched coating layer. The particle diameter of the organic or inorganic fine particles may be 10 μm or less in terms of haze and coating thickness, more specifically 10 nm to 10 μm, preferably 50 nm to 5 μm, more preferably 100 nm to 3 μm can be

The organic fine particles or inorganic fine particles are not limited as long as they are used for forming the coating layer.

The organic fine particles may be at least one selected from organic fine particles consisting of an acrylic resin, a styrene resin, an epoxy resin, and a nylon resin.

More specifically, the organic fine particles are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) 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, pt-butoxystyrene, mt-Butoxystyrene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl ether, allyl butyl ether, allyl glycytyl ether, (meth)acrylic acid, maleic acid, unsaturated carboxylic acid, alkyl (meth)acrylamide , (meth) may be at least one selected from the group consisting of 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, polyimide, polysulfone, polyphenylene oxide, polyacetal, epoxy resin, phenol resin, silicone resin, melamine resin, benzogu 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 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 be in the range of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the coating composition. When 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 cation-curable composition, the effect of improving hardness and scratch resistance is insignificant, and when it exceeds 20 parts by weight, the viscosity of the coating composition is The higher the coating property, the higher the haze value due to internal scattering, so that the contrast ratio may be lowered.

On the other hand, the coating composition of the present invention, in addition to the above components, surfactants, antioxidants, UV stabilizers, leveling agents, antifouling agents, antistatic agents, UV absorbers, defoamers, preservatives, etc. commonly used in the technical field to which the present invention belongs Additives may be further included. In addition, the content can be variously adjusted within the range that does not reduce the physical properties of the coating composition of the present invention, so is not particularly limited, for example, based on 100 parts by weight of the total coating composition, it can be included in about 0.1 to about 10 parts by weight. have.

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

In an exemplary embodiment of the present application, after the step of drying the coating composition, the method further comprises the step of stretching the base film to which the coating composition is applied, wherein the stretching ratio in the stretching step is based on the width direction (TD) It provides a method of manufacturing an optical 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 ℃ or more and 180 ℃ or less, preferably 110 ℃ or more and 160 ℃ or less, more preferably 120 ℃ or more and 140 ℃ or less. .

In an exemplary embodiment of the present application, before the step of applying the coating composition on one surface of the base film, it provides a method of manufacturing an optical protective film that further comprises the step of stretching the base film.

Through the process of uniaxially stretching the base film before the step of applying the coating composition, by coating before the final process, the roll pass can be minimized, and thus the 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 the present technology belongs, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a micro gravure coating method , a comma coating method, a slot die coating method, a lip coating method, or a solution casting method may be used.

In particular, the step of applying the coating composition is a bar (bar) coating; gravure coating; Or it provides a method of manufacturing an optical protective film comprising a slot die coating process.

If the base film is in a uniaxially stretched state before applying the coating composition, the stretching direction after coating is preferably stretching in a direction perpendicular to the stretching direction before application of the coating composition. For example, if the base film is stretched in the length (MD) direction before applying the coating composition, it may be stretched in the width (TD) direction after applying the coating composition.

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

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

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

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

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

In the case of stretching the base film, there is a problem in that when the polymer is rearranged in the stretching process to additionally form a functional coating layer on the stretched substrate film, adhesion is reduced. Therefore, there is a method of adding a separate process such as forming a primer layer to secure adhesion, or including a functional compound capable of enhancing 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 decrease, and there is a problem in that it is difficult to develop a general-purpose primer because the physical and chemical properties of each film are different. In addition, adding a functional compound to the coating layer may also have problems of increasing cost and lowering other properties.

Accordingly, the present invention solves this problem, and according to an embodiment of the present invention, it is possible to provide an optical protective film having sufficient scratch resistance and thinning possible even without a separate primer layer.

According to an exemplary embodiment of the present invention, the coating composition according to the present application may be applied on 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, the refractive index of the optical protective film is 1.40 or more and 1.50 or less.

In the coating composition according to the present invention, as the polyester urethane aqueous dispersion binder resin is formed through the reaction of an aliphatic isocyanate having two or more NCO groups in the main chain and a polyol, the protective film including the same has a refractive index that satisfies the above range, By lowering the difference in refractive index between the base film of the protective film and the functional coating layer positioned on the upper portion of the optical protective film, optical properties are excellent.

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

The polarizer vibrates in several directions and exhibits a characteristic of extracting only light vibrating in one direction from incident light, 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 In, preferably, it is used as a lower protective film of the polarizer.

On the other hand, as the liquid crystal display becomes larger and slimmer, the lower polarizing plate sags, and the lower protective film of the lower polarizing plate comes into contact with the backlight unit, thereby causing scratches.

Accordingly, the optical 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, thereby effectively protecting the lower polarizing plate, and increasing the thickness and size of the polarizing plate for liquid crystal display devices. can be usefully applied.

In this case, 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 a characteristic of extracting only light vibrating in one direction from incident light while vibrating in multiple directions. These properties can be achieved by stretching polyvinyl alcohol (PVA), which has absorbed iodine, with a strong tension. For example, more specifically, a step of swelling the PVA film by immersing it in an aqueous solution to swell, dyeing the swollen PVA film with a dichroic material that imparts polarization, 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 thereto.

According to an embodiment of the present invention, the optical protection film may be attached to both surfaces of the polarizer.

According to an embodiment of the present invention, the optical protection film may be attached to one surface of the polarizer.

When the optical protective film of the present invention is laminated and adhered to a polarizer, it is preferable that the base film is attached to the polarizer.

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

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 at the lower portion.

As described above, when the polarizing plate is laminated on the LCD with the protective film as the lower part, it comes into contact with the backlight unit provided under the polarizing plate and damages the lower protective film of the polarizing plate, thereby preventing the problem of increased haze and exhibiting excellent optical properties. .

The polarizer and the protective film may be adhered by lamination using an adhesive or the like. The usable adhesive is not particularly limited as long as it is 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-based (SBR-based) adhesives, or hot melt adhesives, but the present invention It is not limited only to these examples.

When the optical protective film of the present invention is laminated and adhered to the polarizer, the stretched coating layer is preferably laminated so as to be attached to the polarizer on the surface on which the stretched coating layer is not formed, and the stretched coating layer is positioned outside the polarizing plate.

The polarizing plate having the optical protective film of the present invention has been described as an example of application to LCD, but is not limited thereto, and can be utilized in various fields. For example, it can be used for mobile communication terminals, smart phones, other mobile devices, display devices, electronic boards, outdoor electric billboards, and various display units. According to an embodiment of the present invention, the polarizing plate may be a polarizing plate for TN (Twisted Nematic), STN (Super Twisted Nematic) liquid crystal, IPS (In-Plane Switching), Super-IPS, FFS (Fringe Field Switching), etc. It may be a polarizing plate for horizontal alignment mode, or a polarizing plate for vertical alignment mode.

In an exemplary embodiment of the present application, a liquid crystal cell; an upper polarizing plate provided in the upper layer of the liquid crystal cell; a lower polarizing plate provided in the lower layer of the liquid crystal cell; and a backlight unit provided in a lower layer of the lower polarizing plate, wherein the upper and lower polarizing plates include: a polarizer; and an optical protective film according to the present invention disposed on one or both surfaces of the polarizer.

In another exemplary embodiment, a liquid crystal cell; an upper polarizing plate provided in the upper layer of the liquid crystal cell; a lower polarizing plate provided in the lower layer of the liquid crystal cell; and a backlight unit provided in a lower layer of the lower polarizing plate, wherein the lower polarizing plate includes: a polarizer; and an optical protective film according to the present invention disposed on one or both surfaces of the polarizer.

In an exemplary embodiment of the present application, the optical protection film provides a liquid crystal display device that is disposed to face the backlight unit.

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

The backlight unit includes a light source irradiating light from the rear surface of the liquid crystal panel, and the type of the light source is not particularly limited, and a general LCD light source such as CCFL, HCFL, or LED may be used.

In an exemplary embodiment of the present application, an organic light emitting device (OLED) panel; and an optical film provided on the organic light emitting diode (OLED) panel, wherein the optical film may include an optical protection film according to the present application.

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

< manufacturing example >

< comparative example 1- Preparation of optical protective film>

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

After adding 10 g of a solution of a mixture of 645GH and N36 at a solid content of 80:20 as a water-dispersion resin as a water-dispersion resin, 15% of the content of ST-ZL when the solid content of the water-dispersion resin is set at 100 After the corresponding amount was added, distilled water was added to fix the final solid content at 7%. After 2hr mixing on the uniaxially stretched film, coating was performed with Mayer Bar 4#, and drying was performed in a drying oven at 100° C. for 1 minute.

Thereafter, the optical protective film having a coating thickness of about 280 nm was prepared by stretching 2.5 times in the width direction (TD) for 1 minute at a temperature of 135°C.

In Comparative Example 1, an optical protective film was prepared in the same manner as in Comparative Example 1, except that the composition and solid content parts by weight of Table 1 were used.

water dispersion
bookbinder Agent( phr ) Kinds content Kinds content comparative example One 645GH:N36
(80:20) ST-ZL 15 - - comparative example 2 PU-62 ST-ZL 15 - - comparative example 3 PU-62 ST-ZL 15 TC400 15 Example One PU-62 ST-ZL 15 TC400 10 Example 2 PU-62 ST-ZL 15 TC400 3 Example 3 PU-62 ST-ZL 15 TC400 2 Example 4 PU-62 ST-ZL 15 TC400 One

In Table 1, the composition included in the coating composition is shown in Table 2 below.

Kinds manufacturer Type etc PU-42 Lamberti (Italy) Ester Base Polyurethane dispersion - Pesresin 645GH (denoted as 645GH) Takamatsu oil & Fat co., ltd (Japan) Polyester Acryl dispersion - N36 Noroo paint (Korea) Polyurethane dispersion - ST-ZL Nissan chemical (Japan) Silica dispersion 80nm size TC-400 Matsumoto (Japan) Titanium Triethanol Aminate -

For the optical protective films of Examples 1 to 4 and Comparative Examples 1 to 3, haze, grinding properties, dynamic/static coefficient of friction, blocking area, and pencil hardness were measured, respectively, and the results are shown in Table 3 below It was like

splitting characteristics
(bad X<Δ<O good) refractive index pencil hardness solvent resistance comparative example One X 1.522 2B 4B comparative example 2 Δ 1.492 1B 1B comparative example 3 - 1.485 - - Example One Ο 1.487 HB 5B Example 2 Ο 1.491 HB 5B Example 3 Ο 1.491 HB 5B Example 4 Ο 1.492 HB 5B

1) divergence characteristics

On a sample holder (50 mm X 50 mm) connected to a vibration generator, the coating layer of the optical protective film of the present invention and another sheet having a embossed pattern (eg, diffusion sheet) or uncoated layer of the protective film are stacked and loaded with a weight of 500 g. After applying vibration (intensity of applied vibration of 2.8 Grms, frequency of 20-60 Hz) for 240 seconds in the state of was shown, and the order of the scratch and split characteristics was expressed as Ο > Δ > X.

2) Pencil hardness

Pencil hardness was measured at 500 g load using a pencil hardness tester (hardness tester, manufacturer: Chungbuk Tech). According to ASTM 3363-74, a scratch was applied to the surface of the stretched coating layer by maintaining a 45° angle while changing a standard pencil (Mitsubishi) to 6B to 9H, and the change of the surface was observed. Each experimental value was recorded as an average value excluding the maximum and minimum values after 5 measurements.

3) solvent resistance measurement

After coating the functional coating layer, a 10x10 incision was made with a width of 1mm, Nichiban tape (CT-24) tape was attached, and then the adhesion was evaluated to the extent that the coating layer fell. When the number of falling cells was 0, 5B, 1 to 5, 4B, 6 to 10, 3B, 11 to 20, 2B, 21 to 40, 1B, and 41 or more were indicated as 0B.

Preparation and coating conditions of the coating solution of the functional coating layer were as follows.

DPHA (dipentaerythritol hexaacrylate) 6.237

PETA (Pentaerythritol Hexaacrylate) 16.421

UA-306T (a reaction product of toluene diisocyanate and pentaerythritol triacrylate as a urethane acrylate, manufactured by Kyoeisha) 3.079

8BR-500 (photocurable urethane acrylate polymer, Mw 200,000, manufactured by Taisei Fine Chemical) 6.158

IRG-184 (initiator, Irgacure 184, Ciba) 1.026

Tego-270 (Tego leveling agent) 0.051

BYK350 (BYK company leveling agent) 0.051

2-butanol 25.92

IPA (isopropyl alcohol) 45.92

XX-103BQ (2.0 μm 1.515) (copolymerized particles of polystyrene and polymethyl methacrylate, manufactured by Sekisui Plastic) 0.318

XX-113BQ (2.0 μm 1.555) (copolymerized particles of polystyrene and polymethyl methacrylate, manufactured by Sekisui Plastic) 0.708

MA-ST (30% in MeOH) (a dispersion in which nano-silica particles with a size of 10 to 15 nm are dispersed in methyl alcohol, manufactured by Nissan Chemical) 0.342

The raw materials were mixed in each weight (g) to prepare a functional coating solution, coated with #12 mayer bar, dried at 60° C. for 2 minutes, and UV cured to form a hard coating layer (coating thickness 5 μm). An H bulb was used for the UV lamp, and the curing reaction was carried out under a nitrogen atmosphere. The amount of UV light irradiated during curing was 100mJ/cm ² .

4) Measurement of refractive index

After coating 5 μm on the glass substrate, the refractive index was measured using a prism coupler.

In the coating composition according to the present invention, as the polyester urethane water-dispersion binder resin is formed through the reaction of an aliphatic isocyanate and a polyol having two or more NCO groups in the main chain, the protective film comprising it later has a refractive index that satisfies a specific range, It was confirmed that the difference in refractive index between the base film of the protective film and the functional coating layer positioned on the upper portion of the optical protective film was lowered to have excellent optical properties. In addition, it was found that the optical protective film including the coating composition according to the present application has excellent chemical resistance of the protective film as chemical resistance by a solvent of the functional coating layer is imparted.

In addition, the optical protective film including the coating composition according to the present application can prevent film breakage and damage due to friction between films that occur due to various causes such as diversification of winding slitting width and increase in winding amount during manufacture. Therefore, it was confirmed that the defect cost reduction and productivity were secured.

In the case of Comparative Example 1, as the water-dispersion binder resin, a non-polyester urethane water-dispersion binder resin containing a urethane repeating unit formed through the reaction of an aliphatic isocyanate having two or more NCO groups in the main chain and a polyol was used, and the desired refractive index range It was confirmed that it was impossible to use because it could not achieve .

In the case of Comparative Example 2, the titanate-based crosslinking agent was not used, and in Comparative Example 3, the content of the titanate-based crosslinking agent based on 100 parts by weight of the water-dispersed binder resin was out of the content of the titanate-based crosslinking agent. It can be confirmed that the falling off, especially in the case of Comparative Example 3, it was confirmed that the agglomerate was generated immediately after mixing due to an excess of the crosslinking agent.

10: upper polarizing plate
20: liquid crystal cell
30: lower polarizer
34: optical protection film
35: optical protection film
40: backlight unit

Claims (18)

a polyester urethane water dispersion binder resin comprising a urethane repeating unit formed through the reaction of an aliphatic isocyanate having two or more NCO groups in the main chain and a polyol;
titanate-based crosslinking agent; and
A coating composition comprising water-dispersible fine particles,
The coating composition comprising 0.1 parts by weight or more and 10 parts by weight or less of the titanate-based crosslinking agent based on 100 parts by weight of the water-dispersible binder resin. The method according to claim 1,
The polyol is at least one selected from the group consisting of a polyester polyol, a polycarbonate polyol, a polyether polyol, and a polyacrylic polyol. The method according to claim 1,
The aliphatic isocyanate is hexamethylene diisocyanate (HMDI), isoprone diisocyanate (IPDI), dicyclohexylmethylene-4,4-diisocyanate (H12MDI) (Dicyclohexylmethane-4,4'-diisocyanate), 2,2,4 - consisting of trimethyl-1,6-hexane diisocyanate (2,2,4-Trimethyl-1,6-hexane diisocyanate, TMDI), pentamethylene diisocyanate (PDI) and transcyclohexane-1,4-diisocyanate One or more coating compositions selected from the group. The method according to claim 1,
The water-dispersible fine particles are at least one selected from the group consisting of silica, titania, alumina, zirconia, aqueous wax dispersion, and fluorine-based fine particles. The method according to claim 1,
The titanate-based crosslinking agent is tetraisopropyl titanate, tetranol butyl titanate, butyl titanate dimer, tetraoctyl titanate, titanium acetyl acetate, titanium tetraacetyl acetate, titanium ethyl acetacetate, phosphate titanate, titanium oxide A coating composition that is at least one selected from the group consisting of tylene glycolate, titanium ethyl acetate, titanium lactate, titanium triethanol aminate, titanium dodecylbenzenesulfonic acid, and titanium aminoethylaminoethanoate. 5. The method according to claim 4,
The silica is a coating composition that has an average particle diameter of 10 nm or more and 500 nm or less. The method according to claim 1,
The coating composition of the water-dispersible fine particles is 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the water-dispersible binder resin. preparing a base film;
Applying the coating composition of any one of claims 1 to 7 on at least one surface of the base film; and
drying the coating composition;
A method of manufacturing an optical protective film comprising a. 9. The method of claim 8,
After drying the coating composition,
Further comprising the step of stretching the base film to which the coating composition is applied,
A method of manufacturing an optical protective film wherein the stretching ratio in the stretching step is 1.05 to 10 times based on the width direction (TD). 9. The method of claim 8,
The step of applying the coating composition is a bar (bar) coating; gravure coating; Or a method of manufacturing an optical protective film comprising a slot die coating process. 9. The method of claim 8,
Before applying the coating composition on at least one surface of the base film, the method for producing an optical protective film further comprising the step of stretching the base film. base film; and
A protective film comprising the coating composition of any one of claims 1 to 7 or a cured product thereof on one surface of the base film;
An optical protective film comprising a. 13. The method of claim 12,
The base film is polyester, polyethylene, cyclic olefin polymer (COP), cyclic olefin copolymer (COC), polyacrylate (PAC), poly An optical protective film comprising carbonate (polycarbonate, PC), polymethylmethacrylate (PMMA), polyimide (polyimide, PI) or cellulose (cellulose). 13. The method of claim 12,
The optical protective film has a thickness of 50 nm or more and 10 μm or less. 13. The method of claim 12,
The optical protective film has a refractive index of 1.40 or more and 1.50 or less. polarizer; and
A polarizing plate comprising the optical protective film of claim 12 on at least one surface of the polarizer. liquid crystal cell;
an upper polarizing plate provided in the upper layer of the liquid crystal cell;
a lower polarizing plate provided in the lower layer of the liquid crystal cell; and
and a backlight unit provided in a lower layer of the lower polarizing plate,
The upper polarizing plate and the lower polarizing plate may include a polarizer; and the optical protection film of claim 12 disposed on one or both surfaces of the polarizer. 18. The method of claim 17,
wherein the optical protection film is disposed to face the backlight unit.

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