CN101855303A - Coating composition for antireflection, antireflection film and method for producing same - Google Patents

Abstract

This invention provides a coating composition for antireflection, comprising a low-refractive material with a refractive index of 1.2–1.45 and a high-refractive resin with a refractive index of 1.46–2, wherein the surface energy difference between the two materials is greater than 5 mN/m; an antireflection film prepared using the aforementioned coating composition; and a method for preparing the aforementioned antireflection film. According to this invention, an antireflection film with excellent abrasion resistance and antireflection properties can be prepared using a single composition via a one-step coating method, thereby reducing manufacturing costs.

Description

Coating composition for antireflection, antireflection film and method for producing same

technical field

The invention relates to a coating composition for antireflection, an antireflection film prepared by using the coating composition for antireflection and a method for preparing the antireflection film. More specifically, the present invention relates to a coating composition for antireflection in which although a single-layer coating is formed by a one-step coating method using a coating composition containing resins having different refractive indices from each other, in the A single-layer coating also exhibits phase separation to simultaneously provide anti-reflection properties and abrasion resistance; an anti-reflection film prepared using the coating composition for anti-reflection; and a method for preparing the anti-reflection film.

This application claims Korean Patent Application No. 10-2007-0115348 and No. 10-2007-0115329 filed on November 13, 2007 at the Korean Intellectual Property Office, Korean Patent Application No. 10-2007-0115967 and the priority of Korean Patent Application No. 10-2008-0035891 filed on Apr. 18, 2008, the disclosure of which is hereby incorporated by reference in its entirety.

Background technique

One purpose of surface treatments on the surface of a display is to improve image contrast by increasing the wear resistance of the display and reducing reflections of light emitted from external light sources. Reducing the reflection of external light can be achieved in two ways. One method is to induce diffuse reflection by using convex and concave shapes on the surface, and the other is to induce destructive interference by using a multi-coating design.

Anti-glare coatings employing concavo-convex shapes on the surface have been widely used in the related art. However, there are problems in deteriorating resolution in high-resolution displays and degrading sharpness of images due to diffuse reflection. In order to solve the above-mentioned problems, Japanese Patent Application Publication No. 11-138712 has disclosed a light diffusion film in which light is diffused in a film prepared using an organic filler having a different refractive index from that of a binder. However, this light-diffusing film requires improvement because it has problems of deterioration of brightness and contrast.

Methods of causing destructive interference of reflected light by multilayer coating design have been disclosed in Japanese Patent Application Publication Nos. 02-234101 and 06-18704. According to this method, antireflection characteristics can be obtained without distorting images. In this case, the reflected light of each layer should have a phase difference so that the reflected light interferes destructively, and the waveform of the reflected light should have an amplitude so that the reflectance can be the minimum reflectance during the destructive interference process. For example, when the incident angle with respect to the single-layer anti-reflection coating provided on the substrate is 0°, the following expression can be obtained.

[mathematical formula 1]

n _o n _s = n ₁ ²

2n ₁ d ₁ =(m+1/2)λ(m=0, 1, 2, 3...)

(n _o : Refractive index of air; n _s : Refractive index of substrate; n ₁ : Refractive index of film; d ₁ : Thickness of film; λ: Wavelength of incident light)

Generally, antireflection is effective if the refractive index of the antireflection coating is less than that of the substrate. However, considering the abrasion resistance of the coating, preferably, the refractive index of the anti-reflection coating is 1.3 to 1.5 times the refractive index of the substrate. In this case, the reflectance is less than 3%. However, when the anti-reflection coating is formed on a plastic film, it is impossible to meet the wear resistance requirements of the display. For this reason, it is necessary to place a few micrometers of hard coating underneath the anti-reflection coating. That is, the antireflection coating applying destructive interference includes a hard coat layer for enhancing abrasion resistance and 1 to 4 layers of antireflection coating layers formed on the hard coat layer. Therefore, the multilayer coating method obtains antireflection characteristics without image distortion. However, there still remains a problem of increased manufacturing cost due to multi-layer coating.

In recent years, methods have been proposed to make reflected light destructively interfere by designing single-layer coatings. The following method has been disclosed in Japanese Patent Application Publication No. 07-168006. According to this method, ultrafine particles dispersed in a liquid are coated on a substrate, and spherical fine particles are exposed on the surface so that a difference in refractive index is gradually generated between air (interface) and the particles. Therefore, antireflection characteristics can be obtained. However, since the shape and particle size of the ultrafine particles should be uniform, and the particles should be uniformly dispersed on the substrate, it is difficult to implement this method by the usual coating method. Also, since the amount of adhesive should be equal to or less than the predetermined amount in order to obtain a spherical shape on the surface of the film, this method results in very poor abrasion resistance. In addition, since the thickness of the coating should also be smaller than the diameter of the fine particles, it is difficult to obtain abrasion resistance.

Contents of the invention

technical problem

In order to solve the above-mentioned problems, an object of the present invention is to provide a coating composition for antireflection in which phase separation occurs in the coating although a coating composition is used to form a coating by a one-step coating method The anti-reflection property and abrasion resistance are provided at the same time, thereby improving process efficiency and reducing production cost; an anti-reflection film prepared by using the anti-reflection coating composition; and a method for preparing the anti-reflection film.

Technical solutions

In order to achieve the above object, the present invention provides a coating composition for antireflection, which comprises a low refractive material with a refractive index of 1.2 to 1.45 and a high refractive resin with a refractive index of 1.46 to 2, wherein the The difference in surface energy is 5 mN/m or more.

In addition, the present invention provides a method for preparing an anti-reflection film, which includes the following steps:

a) prepare a coating composition for antireflection, the composition comprises a low refractive material with a refractive index of 1.2 to 1.45 and a high refractive resin with a refractive index of 1.46 to 2, wherein the difference in surface energy between the two materials is 5mN/ more than m;

b) applying the coating composition to a substrate to form a coating;

c) drying the coating to phase separate the low and high refractive materials; and

d) Curing the dried coating.

The coating composition for anti-reflection may further include a fluorinated compound or a nanoparticle dispersion to facilitate phase separation of the low-refraction material and the high-refraction material.

In addition, the present invention provides an antireflection film comprising a single-layer coating comprising a low-refractive material having a refractive index of 1.2 to 1.45 and a high-refractive resin having a refractive index of 1.46 to 2, wherein the difference between the two materials is The surface energy difference is more than 5mN/m and the low refractive material and the high refractive material have a concentration gradient in the thickness direction.

Furthermore, the present invention provides a polarizer comprising a) a polarizing film, and b) an antireflection film according to the present invention applied to at least one side of the polarizing film.

In addition, the present invention provides a display device comprising the anti-reflection film or the polarizer.

Beneficial effect

By using the above-mentioned coating composition for antireflection and the method for producing the antireflection film, the present invention can provide an antireflection film including an antireflection layer having excellent antireflection characteristics and abrasion resistance, wherein the antireflection The reflective layer consists of a single layer coating. Since the antireflection film according to the present invention has excellent abrasion resistance and low refraction characteristics and can be prepared by a one-step coating method, processing efficiency can be improved and production cost can be reduced.

Description of drawings

FIG. 1 is a transmission electron microscope image showing a cross-sectional view of an antireflection film according to Example 1. Referring to FIG.

Detailed ways

Hereinafter, the present invention will be described in detail.

The coating composition for antireflection according to the present invention is characterized in that it comprises a low-refractive material with a refractive index of 1.2 to 1.45 and a high-refractive resin with a refractive index of 1.46 to 2, and the difference in surface energy between the two materials is More than 5mN/m. Phase separation may occur during the coating, drying, and curing processes due to surface energy differences between low and high refractive materials using the coating composition for antireflection. Therefore, even if a one-step coating method is performed using one composition, excellent antireflection characteristics and abrasion resistance can be provided.

In the present invention, the surface energy is measured in a cured product prepared by curing the material.

After the coating step is completed, due to the difference in surface energy between the low-refractive material and the high-refractive material, the low-refractive material gradually moves toward the upper portion of the coating, while the high-refractive material is located at the lower portion of the coating. In order to maximize phase separation and fix the position of phase separation in the drying and curing steps, it is preferable that the low-refractive material is a thermosetting material that is soft at room temperature and gradually solidifies according to temperature. In addition, the low-refractive material preferably has a surface energy of 25 mN/m or less, and more preferably 5 mN/m to 25 mN/m.

In the present invention, preferably, based on 100 parts by weight of the total coating composition, the content of the low refractive material is 5 to 80 parts by weight, and the content of the high refractive material is 10 to 90 parts by weight.

The low refraction-thermosetting material is a thermosetting material with a refractive index in the range of 1.2 to 1.45. For example, an alkoxysilane reactant, a urethane reactive compound, a urea reactive compound, an esterification reactant, etc. which may cause a sol-gel reaction may be used as the low refraction-thermosetting resin.

The alkoxysilane reactants are reactive oligomers that are processed by hydrolysis and condensation of alkoxysilanes, fluorinated alkoxysilanes, silane-based organic substituents under water and catalyst conditions. prepared by sol-gel reaction. The sol-gel reaction can adopt any method commonly used in the art. The sol-gel reaction including alkoxysilane, fluorinated alkoxysilane, catalyst, water, and organic solvent is performed at a reaction temperature of 0 to 150° C. for 1 to 70 hours. In this case, the reactive oligomer alkoxysilane preferably has an average molecular weight of 1,000 to 200,000 when measured by GPC (Gel Permeation Chromatography) using polystyrene as a reference material. The condensation reaction is performed at a temperature equal to or higher than room temperature after coating, so that the alkoxysilane reactant prepared as described above forms a network having a crosslinked structure.

The alkoxysilane is capable of imparting the required level of strength to the outermost film. Specifically, the alkoxysilane may be tetraalkoxysilane or trialkoxysilane. Meanwhile, the alkoxysilane is preferably selected from tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, glycidoxy At least one of propyltrimethoxysilane and glycidoxypropyltriethoxysilane, but not limited thereto.

The content of the basic monomeric alkoxysilane is preferably 5 to 50 parts by weight based on 100 parts by weight of the alkoxysilane reactant. If the content is less than 5 parts by weight, it is difficult to obtain excellent abrasion resistance. If the content is more than 50 parts by weight, it may be difficult to achieve low refractive characteristics of the alkoxysilane reactant and phase separation from the high refractive material.

The fluorinated alkoxysilanes lower the refractive index and surface tension of the coated film to facilitate phase separation from highly refractive materials. The fluorinated alkoxysilane is preferably a low refractive material having a low refractive index of 1.3 to 1.4 and a low surface tension of 10 to 15 mN/m. The fluorinated alkoxysilane is preferably one or more selected from tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane and heptadecafluorodecyltriisopropoxysilane species, but not limited to this.

In order to make the alkoxysilane reactant have a refractive index of 1.2 to 1.45 and facilitate phase separation from high refractive materials, based on 100 parts by weight of the alkoxysilane reactant, the content of the fluorinated alkoxysilane Preferably it is 10 to 70 parts by weight. If the content is less than 10 parts by weight, it may be difficult to achieve low-refractive properties and phase separation from high-refractive materials. If the content is more than 70 parts by weight, it may be difficult to ensure solution stability and scratch resistance.

The silane-based organic substituent can be chemically combined with the alkoxysilane, form a double bond with the high-refractive material to improve the compatibility of the low-refractive material and the high-refractive material, and enhance the alkoxysilane after phase separation. and adhesion to high refractive materials. Therefore, any compound can be used without limitation as long as it has the above-mentioned function. The silane-based organic substituent is preferably selected from vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltri-n-propoxysilane , vinyltri-n-pentoxysilane, vinylmethyldimethoxysilane, biphenylethoxyvinylsilane, vinyltriisopropoxysilane, divinylbis(β-methoxyethyl oxy)silane, divinyldimethoxysilane, divinyldiethoxysilane, divinyldi-n-propoxysilane, divinylbis(isopropoxy)silane, divinyldi-n- Pentyloxysilane, 3-Acryloxypropyltrimethoxysilane, 3-Methacryloxypropyltrimethoxysilane, γ-Methacryloxypropylmethyldiethoxysilane , one or more of γ-methacryloxypropylmethyldiethoxysilane, but not limited thereto.

In order to maintain the compatibility and stability of the alkoxysilane reactant in the coating solution, based on 100 parts by weight of the alkoxysilane reactant, the content of the silane-based organic substituent is preferably 0 to 50 wt. share. If the content is more than 50 parts by weight, it may be difficult to achieve low refractive characteristics and phase separation from high refractive materials. In addition, if the silane-based organic substituent is not added thereto, the low-refractive material has insufficient compatibility with the high-refractive material, and thus the coating solution may not be uniformly mixed.

The catalyst used in the sol-gel reaction is a component necessary to control the sol-gel reaction time. The catalyst is preferably an acid such as nitric acid, hydrochloric acid, sulfuric acid, and acetic acid, and more preferably hydrochloride, nitrate, sulfate, or acetate of zirconium or indium, but is not limited thereto. In connection with this, the catalyst is preferably used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the alkoxysilane reactant.

Water used in the sol-gel reaction is required for hydrolysis and condensation, and is used in an amount of 5 to 50 parts by weight based on 100 parts by weight of the alkoxysilane reactant.

The organic solvent used in the sol-gel reaction is a component that controls the molecular weight of the hydrolysis condensate. The organic solvent is preferably a solvent or a mixed solvent selected from alcohols, cellosolves, and ketones. In connection with this, the content of the organic solvent is preferably 0.1 to 50 parts by weight based on 100 parts by weight of the alkoxysilane reactant.

Meanwhile, the urethane reactive group compound may be prepared through a reaction between an alcohol and an isocyanate compound while using a metal catalyst. If a solution containing a metal catalyst, a polyfunctional isocyanate having two or more functional groups, and a polyfunctional alcohol having two or more functional groups is kept at a temperature equal to or higher than room temperature, a network containing a carbamate reactive group can be formed shape structure. In this case, a fluorine group may be introduced into alcohol or isocyanate to achieve low-refractive properties and promote phase separation from high-refractive materials.

Examples of the fluorine-containing polyfunctional alcohol may include 1H, 1H, 4H, 4H-perfluoro-1,4-butanediol,

1H, 1H, 5H, 5H-perfluoro-1,5-pentanediol,

1H, 1H, 6H, 6H-perfluoro-1,6-hexanediol,

1H, 1H, 8H, 8H-perfluoro-1,8-octanediol,

1H, 1H, 9H, 9H-perfluoro-1,9-nonanediol,

1H, 1H, 10H, 10H-perfluoro-1,10-decanediol,

1H, 1H, 12H, 12H-perfluoro-1,12-dodecanediol, fluorinated triethylene glycol, and fluorinated tetraethylene glycol, but not limited thereto.

Preference is given to using aliphatic isocyanates, cycloaliphatic isocyanates, aromatic isocyanates or heterocyclic isocyanates as isocyanate constituents for the preparation of the urethane-reactive compound. In particular, diisocyanates such as 1,6-hexamethylene diisocyanate, 1,3,3-trimethylhexamethylene diisocyanate, isophorone diisocyanate, toluene-2,6-diisocyanate and 4,4 '-dicyclohexane diisocyanate; or isocyanate with three or more functional groups, such as DN950 and DN980 (trade name) manufactured by DIC Corporation as the isocyanate component.

In the present invention, a catalyst may be used to prepare the carbamate reactive group compound. Lewis acids or Lewis bases can be used as catalysts. Specific examples of the catalyst may include tin octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin dimaleate, and dimethyl hydroxide Tin and triethylamine, but not limited thereto.

The content of isocyanate and polyfunctional alcohol used to prepare the urethane-reactive compound is preferably set such that the molar ratio (NCO/OH) of functional groups NCO groups to OH groups is preferably 0.5 to 2, and more preferably Preferably it is 0.75 to 1.1. If the molar ratio between functional groups is less than 0.5 or greater than 2, unreacted functional groups may increase. Therefore, there may be a problem that the strength of the film decreases.

The urea-reactive compound may be prepared by a reaction between an amine and an isocyanate. The urea-reactive compound may be prepared using an isocyanate, which is the same isocyanate used to prepare the urethane-reactive compound. Perfluoroamines having two or more functional groups can be used as the amine. A catalyst can be used in the present invention, if necessary. Lewis acids or Lewis bases can be used as catalysts. Specific examples of the catalyst include tin octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin hydrogen maleate, dimethyltin hydroxide, and triethylamine, but not limited to this.

Esterification reactants can be obtained through dehydration and condensation reactions between acids and alcohols. If the esterification reactant is also mixed in the coating solution, a film having a crosslinked structure can be formed. Preferably, a fluorine-containing acid having two or more functional groups is used as the acid. Specific examples thereof may include perfluorosuccinic acid, perfluoroglutaric acid, perfluoroadipic acid, perfluorosuberic acid, perfluoroazelaic acid, perfluorosebacic acid and perfluorolauric acid. Preferably, polyfunctional alcohols are used as the alcohols. Specific examples of the functional alcohol include 1,4-butanediol, 1,2-butanediol, 1,5-pentanediol, 2,4-pentanediol, 1,4-cyclohexanediol, 1,6-hexanediol, 2,5-hexanediol, 2,4-heptanediol, pentaerythritol, and trimethylolpropane, but not limited thereto. An acid catalyst such as sulfuric acid or an alkoxytitan such as tetrabutoxytitan may be used in the esterification reaction. However, materials used in the esterification reaction are not limited to the above-mentioned materials.

The high-refractive material is a resin having a refractive index of 1.45 to 2, which is relatively higher than that of the low-refractive material, and the difference in surface energy between cured products of the high-refractive material and the low-refractive material is More than 5mN/m. Preferably, the surface energy of the cured product of the high-refractive material is higher than that of the low-refractive material by more than 5 mN/m.

The high refraction material is preferably a high refraction ultraviolet curable resin. Materials for high-refractive UV-curable resins may contain acrylate resins, photoinitiators, solvents, and, if necessary, surfactants. Examples of the acrylate resin may include acrylate monomers, urethane acrylate oligomers, epoxy acrylate oligomers, and ester acrylate oligomers. UV curable resins can contain substituents such as sulfur, chlorine, and metals, or aromatic materials to achieve high refractive index. Examples thereof may include dipentaerythritol hexaacrylate, pentaerythritol tri/tetraacrylate, trimethylene propane triacrylate, ethylene glycol diacrylate, 9,9-bis(4-(2-acryloyloxyethoxy Phenyl)fluorine (refractive index: 1.62), bis(4-methacryloxyphenylthio)sulfide (refractive index: 1.689) and bis(4-vinylphenylthio)sulfide (refractive index: 1.695).One compound or a mixture of two or more of the above compounds can be used.

Based on 100 parts by weight of the high refraction material, the content of the acrylate resin is preferably 10 to 80 parts by weight. If the content is less than 10 parts by weight, there may be a problem that the scratch resistance and abrasion resistance of the coating film are lowered, and the viscosity of the coating solution is significantly lowered to prevent transfer to coating machines and substrates. If the content is more than 80 parts by weight, it is difficult to achieve phase separation from the low-refractive material due to the high viscosity of the coating solution, and there is a problem that the flatness of the coating film and the coating performance decrease.

The photoinitiator is preferably a compound degradable by UV, examples of which may include 1-hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal, hydroxy dimethyl acetophenone, benzoin, benzoin benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin butyl ether.

The photoinitiator is preferably used in an amount of 1 to 20 parts by weight based on 100 parts by weight of the high refractive material. If the content is less than 1 part by weight, proper curing may not occur. If the content is more than 20 parts by weight, the scratch resistance and abrasion resistance of the coating film may decrease.

Examples of the solvent may include alcohols, acetates, ketones, aromatic solvents, and the like. Specific examples of the solvent may include methanol, ethanol, isopropanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-isopropoxyethanol, methyl acetate , ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, cyclohexanone, toluene, xylene and benzene, but not limited thereto.

The solvent is preferably used in an amount of 10 to 90 parts by weight based on 100 parts by weight of the high refractive material. If the content is less than 10 parts by weight, it is difficult to achieve phase separation from the low-refractive material due to the high viscosity of the coating solution, and there is a problem that the flatness of the coating film may decrease. If the content is more than 90 parts by weight, there are problems that the scratch resistance and abrasion resistance of the coating film may decrease and the viscosity of the coating solution may significantly decrease to prevent transfer to coating machines and substrates.

The high refraction ultraviolet curable resin may further contain a surfactant. Examples of the surfactant may include leveling agents or wetting agents, specifically, fluorine compounds or silicone compounds, but are not limited thereto.

Based on 100 parts by weight of the high refraction material, the preferred amount of the surfactant is 5 parts by weight. If the content is more than 5 parts by weight, it is difficult to achieve phase separation from the low-refractive material, and there is a problem that adhesion to a substrate, scratch resistance and abrasion resistance of a coating film may decrease. Based on 100 parts by weight of the high refractive material, the surfactant is preferably added in an amount of 0.05 parts by weight or more in order to obtain a sufficient effect thereof.

After the drying and curing process is completed, the difference in refractive index of the cured products of the above-mentioned low-refractive material and high-refractive material is preferably 0.01 or more. In this case, the monolayer coating functionally forms a GRIN (Gradient Refractive Index) structure consisting of two or more layers, thereby obtaining an antireflection effect. In relation to this, when the cured low-refractive material has a surface energy of 25 mN/m or less, and the difference in surface energy between the low-refractive material and the high-refractive material is 5 mN/m or more, phase separation effectively occurs.

The coating composition for anti-reflection according to the present invention may further include at least one of a fluorinated compound and a nanoparticle dispersion to facilitate phase separation of the low-refractive material and the high-refractive material.

It is preferred that the fluorinated compound has a refractive index of 1.5 or less, a molecular weight smaller than that of the low-refractive material, and a surface energy between those of the high-refractive material and the low-refractive material. The preferred content of the fluorinated compound is 0.05 to 72 parts by weight based on 100 parts by weight of the total coating composition.

The fluorinated compound is a low-refractive-thermosetting resin such as fluorinated alkoxysilane, fluorinated alcohol, fluorinated isocyanate, fluorinated amine, and fluorine-containing acid having two or more functional groups, and is preferably selected from the exemplified Fluorinated compounds; one or more fluorinated acrylates (which are represented by the following general formulas 1 to 5) further containing C ₁ -C ₆ linear or branched hydrocarbon groups as substituents; such as fluorine-containing leveling agents , dispersants, surface modifiers, wetting agents, defoamers and compatibilizers, a variety of fluorinated additives and one or more materials in fluorinated solvents.

[Formula 1]

Wherein, R ₁ is -H or C ₁ -C ₆ hydrocarbon group, a is an integer from 0 to 4, and b is an integer from 1 to 3. The C ₁ -C ₆ hydrocarbon group is preferably methyl (—CH ₃ ).

[Formula 2]

Wherein, c is an integer from 1 to 10.

[Formula 3]

Wherein, d is an integer from 1 to 9.

[Formula 4]

Wherein, e is an integer from 1 to 5.

[Formula 5]

Wherein, f is an integer from 4 to 10.

It is preferable to use the fluorinated compound within the range of maintaining the low-refractive properties of the coating film, the strength of the coating film, and the adhesion to the display substrate, specifically, based on 100 parts by weight of the low-refractive material, the amount is 1 to 90 parts by weight.

It is preferable that the nanoparticle dispersion liquid contains nanoparticles with an average particle size of 1,000 nm or less, preferably 1 to 200 nm, and more preferably 2 to 100 nm, to obtain a transparent film without visible light scattering or diffusion. The nanoparticle dispersion preferably has a refractive index of 1.45 or less. The nanoparticle dispersion may further include a dispersion-enhancing chelating agent, fluorinated acrylate, solvent, and the like. The preferred content of the nanoparticle dispersion is 2 to 27 parts by weight based on 100 parts by weight of the total coating composition.

The nanoparticles can be metal fluorides, other organic/inorganic hollow and porous particles. Specifically, the metal fluoride is a particle having an average particle size of 10 to 100 nm, and includes a metal selected from NaF, LiF, AlF ₃ , Na ₅ Al ₃ F ₁₄ , Na ₃ AlF ₆ , MgF ₂ , NaMgF ₃ , and YF ₃ one or more.

The nanoparticles are preferably used within the range of maintaining the low refractive properties of the coating film, the strength of the coating film, and the adhesiveness to the display substrate. Based on 100 parts by weight of the nanoparticle dispersion, the preferred content of the nanoparticles is 5 to 70 parts by weight.

The dispersion-enhancing chelating agent is a liquid component for making the high-refractive material and the low-refractive material compatible with the nanoparticles, so that the nanoparticles are not easy to agglomerate and also prevent fogging of the coating film. Such dispersion enhancing chelating agents may be added if desired. The chelating agent for enhancing dispersion is preferably selected from Mg(CF ₃ COO) ₂ , Na(CF ₃ COO), K(CF ₃ COO), Ca(CF ₃ COO) ₂ , Mg(CF ₂ COCHCOCF ₃ ) ₂ , One or more materials selected from Na(CF ₂ COCHCOCF ₃ ), Zr(AcAc), Zn(AcAC), Ti(AcAc) and Al(AcAc), wherein AcAc is acetylacetone.

In addition, the solvent may preferably be DAA, AcAc, and Cellosolve, but is not limited thereto.

The dispersion-enhancing chelating agent is preferably used within a range of maintaining dispersibility of nanoparticles, strength of a coating film, and adhesion to a display substrate. Specifically, based on 100 parts by weight of the nanoparticle dispersion, the preferred amount of the dispersion-enhancing chelating agent is 10 to 80 parts by weight.

The fluorinated acrylate is used to make the high-refraction material and the low-refraction material compatible and to make the film have a certain strength through chemical combination, which can be selected from those represented by general formulas 1 to 5 and further contain C ₁ -C One or more materials in compounds with ₆ hydrocarbon groups as substituents. Based on 100 parts by weight of the nanoparticle dispersion, the preferred amount of the fluorinated acrylate is 80 parts by weight or less.

Examples of solvents for the nanoparticle dispersion may include alcohols, acetates, ketones or aromatic solvents, specifically methanol, ethanol, isopropanol, butanol, 2-methoxyethanol, 2- Ethoxyethanol, 2-butoxyethanol, 2-isopropoxyethanol, methyl acetate, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, cyclohexanone, toluene , xylene, benzene, etc. The solvent is preferably used in an amount of 10 to 90 parts by weight based on 100 parts by weight of the nanoparticle dispersion.

The present invention provides an anti-reflection film prepared by using the above coating composition for anti-reflection, and a method for preparing the anti-reflection film.

Preparation The method for preparing an anti-reflection film according to the present invention comprises the following steps:

a) preparing the above-mentioned coating composition for antireflection;

b) applying the coating composition to a substrate to form a coating;

c) drying the coating to phase separate the low and high refractive materials; and

d) Curing the dried coating.

In step b), the substrate may be glass, plastic sheet or film, and its thickness is not limited. Examples of plastic films may include cellulose triacetate films, norbornene cycloolefin polymer films, polyester films, polymethacrylate films, and polycarbonate films, but are not limited thereto.

In step b), the method of coating the coating composition can be such as rod coating, two-roll or three-roll reverse coating, gravure coating, die coating, micro gravure coating Various methods of coating method and continuous coating method (comma coating), the coating method can be selected according to the liquid phase or rheological properties of the substrate and coating solution without any restrictions.

The thickness of the coating is not particularly limited, but is preferably 0.5 to 30 μm, and a drying process for drying the solvent is performed after the coating process. After the drying process, if the thickness of the coating layer is less than 0.5 μm, the abrasion resistance cannot be sufficiently improved. If the thickness of the coating layer is greater than 30 μm, it is difficult to achieve phase separation of the low-refractive material and the high-refractive material, so that desired refractive characteristics cannot be obtained.

In step c), a drying process may be performed at a temperature of 40 to 150° C. for 0.1 to 30 minutes to remove the organic solvent from the coating composition and gradually cure the low-refractive material on the upper portion of the coating. If the temperature is lower than 40° C., the organic solvent cannot be completely removed and the degree of curing during UV curing decreases. If the temperature is above 150°C, curing may occur before the low refractive material is positioned on top of the coating.

In step d), a curing process may be performed by UV or heating according to the type of resin used. When both thermosetting and UV curing resins are used, the UV curing process is performed first, followed by the thermal curing process.

The UV curing process may be performed at a UV radiation dose of 0.01 to 2 J/cm ² for 1 to 600 seconds to make the coating have sufficient abrasion resistance. If the UV irradiation dose is not within the above range, uncured resin remains on the coating, so the surface becomes sticky and abrasion resistance cannot be ensured. If the UV radiation dose exceeds the above range, the amount of the UV curable resin increases too much, thus possibly hindering the curing of the thermosetting resin in the heat curing step.

Thermal curing may be performed at 20 to 200° C. for 1 to 72 hours. If the temperature is less than 20°C, the curing rate is too low to reduce the curing time. If the temperature is greater than 200°C, there may be problems with the stability of the coated substrate. The curing process is preferably carried out for 1 to 72 hours, and in order to maximize the scratch resistance of the coating, the thermosetting resin should be fully cured.

The antireflection film according to the present invention prepared using the above coating composition for antireflection includes a single-layer coating comprising a low-refractive resin with a refractive index of 1.2 to 1.45 and a high-refractive resin with a refractive index of 1.46 to 2. The refractive material preferably further comprises at least one of a fluorinated compound and a nanoparticle dispersion, wherein the difference in surface energy between the two materials is more than 5mN/m, and the low-refractive material and the high-refractive material already have a thickness in the thickness direction Concentration gradient. The anti-reflection film may further include a substrate applied on one side of the coating.

In the antireflection film, based on the total weight of the low-refractive material, the low-refractive material contained in the area corresponding to 50% in the thickness direction from the surface of the coating facing the air is preferably 70% or more, more preferably 85% or more, And most preferably 95% or more. The reflectance of the anti-reflection film according to the present invention is less than 3%, thereby exhibiting an excellent anti-reflection effect.

Furthermore, the present invention provides a polarizer including the above-mentioned antireflection film according to the present invention. Specifically, the polarizer according to the present invention comprises a) a polarizing film, and b) an antireflection film according to the present invention applied on at least one side of the polarizing film. A protective film may be provided between the polarizing film and the antireflection film. In addition, the substrate used to form the single-layer coating in the process of producing the antireflection film can actually be used as a protective film. The polarizing film and the antireflection film may be bonded to each other by an adhesive. Polarizing films known in the art can be used.

The invention provides a display device, which includes an anti-reflection film or a polarizer. The display device may be a liquid crystal display or a plasma display. The display device according to the present invention may have a structure known in the art except for the case where the antireflection film according to the present invention is provided. For example, in the display device according to the present invention, the anti-reflection film may be provided on the outermost surface of the display panel facing the viewer or on its outermost surface facing the backlight. In addition, a display device according to the present invention may include a display panel, a polarizing film provided on at least one face of the panel, and an anti-reflection film provided on an opposite side of the polarizing film toward a side of the panel.

best practice

Hereinafter, preferred examples are provided for better understanding of the present invention. However, these examples are for illustrative purposes only, and the present invention is not intended to be limited by these examples.

Example

Preparation Example

Preparation of low refraction-thermosetting material (Material A)

Evenly mix 15.3 parts by weight of DN 980 (produced by DIC Corporation) (wherein the average number of isocyanate functional groups is 3), 14 parts by weight of fluorine-containing difunctional alcohol 1H, 1H, 12H, 12H-perfluoro-1,12 - Dodecanediol, 0.7 parts by weight of dibutyltin dilaurate as a metal catalyst, and 35 parts by weight each of diacetone alcohol (DAA) and methyl ethyl ketone (MEK) as a solvent to prepare a low-refractive-thermosetting solution.

Preparation of Low Refractive-Thermoset Material (Material B)

10 parts by weight of tetraethoxysilane, 30 parts by weight of heptadecafluorodecyltrimethoxysilane, 20 parts by weight of methacryl trimethoxysilane, 10 parts by weight of water, 0.5 parts by weight of hydrochloric acid, A mixture of 40 parts by weight of ethanol and 40 parts by weight of 2-butanol was subjected to a sol-gel reaction at room temperature for 12 hours to prepare a low-refractive-thermosetting solution.

Preparation of Low Refractive-Thermoset Material (Material C)

25 parts by weight of fluoroalkylmethoxysilane, 20 parts by weight of tetraethoxysilane, 7 parts by weight of 3-methacryloxypropyl trimethoxysilane, 7.5 parts by weight of water, 0.5 parts by weight A mixture of parts by weight of nitric acid, 20 parts by weight of methanol, and 20 parts by weight of 2-butanol was subjected to a sol-gel reaction at room temperature for 24 hours to prepare a low-refractive-thermosetting solution.

Preparation of Low Refractive-Thermoset Material (Material D)

15 parts by weight of fluoroalkylmethoxysilane, 25 parts by weight of tetraethoxysilane, 12 parts by weight of 3-methacryloxytrimethoxysilane, 7.5 parts by weight of water, 0.5 parts by weight A mixture of nitric acid, 20 parts by weight of methanol and 20 parts by weight of 2-butanol was subjected to a sol-gel reaction at room temperature for 24 hours to prepare a low-refractive-thermosetting solution.

Preparation of High Refractive-UV Curable Material (Material E)

Evenly mix 28 parts by weight of dipentaerythritol hexaacrylate (DPHA) (as a multifunctional acrylate for improving the strength of the coating film), 2 parts by weight of Darocur 1173 as a UV initiator, and 35 parts by weight of each of Darocur 1173 as a solvent. Diacetone alcohol (DAA) and methyl ethyl ketone (MEK) were used to prepare high refraction-UV curing solutions.

Preparation of High Refractive-UV Curable Material (Material F)

Evenly mix 30 parts by weight of dipentaerythritol hexaacrylate (DPHA) (as a multifunctional acrylate for improving the strength of the coating film), 1 part by weight of Darocur 1173 as a UV initiator, 20 parts by weight of ethanol, 29 The high refraction-UV curing solution was prepared with n-butanol in parts by weight and acetylacetone (AcAc) in 20 parts by weight as a solvent.

Preparation of Low Refractive-Thermoset Material (Material G)

5 parts by weight of fluoroalkylethoxysilane, 37 parts by weight of tetramethoxysilane, 10 parts by weight of vinyltrimethoxysilane, 7.5 parts by weight of water, 0.5 parts by weight of nitric acid and 40 parts by weight of A mixture of methanol was subjected to a sol-gel reaction at room temperature for 24 hours to prepare a low-refractive-thermosetting solution.

Preparation of High Refractive-UV Curable Material (Material H)

Evenly mix 20 parts by weight of pentaerythritol tri/tetraacrylate (as a multifunctional acrylate for improving the strength of the coating film), 10 parts by weight of trimethylene propane triacrylate, and 1 part by weight of Darocur as a UV initiator. 1173, as the BYK 333 of 5 parts by weight of surfactant and the BYK371 of 4 parts by weight and the ethanol of 20 parts by weight as solvent, the n-butanol of 20 parts by weight and the methyl ethyl ketone (MEK) of 20 parts by weight to prepare high refraction-UV Solidification solution.

Example 1

30 parts by weight of low refraction-thermosetting material A and 70 parts by weight of high refraction-UV curable material E were uniformly mixed to prepare a coating composition for antireflection.

The prepared composition was coated on a cellulose triacetate film having a thickness of 80 μm using a wire bar (No. 5). The film was dried in a 60°C oven for 2 minutes and cured by irradiating a dose of 1 J/cm ² of UV, followed by thermal curing in a 120°C oven for 1 day. The final coating thickness was 1 μm, and the cross-section was observed under a transmission electron microscope, which is shown in Figure 1.

Referring to FIG. 1 , it is found that a high refraction material layer and a low refraction material layer are respectively formed in a layer structure on a substrate. When a layered structure is formed of materials having different refractive indices, more effective reflectance can be obtained compared to a single-layered structure.

Example 2

A film was prepared in the same manner as in Example 1 except that Material B was used instead of Material A as the low-refractive-thermosetting material.

Example 3

25 parts by weight of the low-refraction-thermosetting material C and 75 parts by weight of the high-refraction-UV-curable material F were uniformly mixed to prepare a compatible mixed solution, resulting in a coating composition.

The prepared coating composition was coated on a cellulose triacetate film having a thickness of 80 μm using a wire bar (No. 5). The film was dried in a 120°C oven for 2 minutes, and cured by irradiating a dose of 200 mJ/cm ² of UV, followed by thermal curing in a 120°C oven for 1 day. The final coating thickness is 1 μm.

Example 4

A compatible coating composition was prepared by uniformly mixing 30 parts by weight of low-refraction-thermosetting material A and 70 parts by weight of high-refraction-UV-curable material F. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 5

Uniformly mixed 20 parts by weight of low refraction-thermosetting material C, 75 parts by weight of high refraction-UV curable material F and 5 parts by weight of trifluoroethyl acrylate as a fluorinated compound to prepare compatible antireflection coating composition. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 6

Uniformly mixed 25 parts by weight of low refraction-thermosetting material A, 70 parts by weight of high refraction-UV curable material F and 5 parts by weight of trifluoroethyl acrylate as a fluorinated compound to prepare compatible antireflection coating composition. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 7

Uniformly mixed 25 parts by weight of low refraction-thermosetting material D, 70 parts by weight of high refraction-UV curable material F and 5 parts by weight of trifluoroethyl acrylate as a fluorinated compound to prepare compatible antireflection coating composition. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 8

Uniformly mixed 22 parts by weight of low-refraction-thermosetting material C, 70 parts by weight of high-refraction-UV curing material F and 8 parts by weight of tridecafluorooctyltriethoxysilane as a fluorinated compound to prepare a compatible Coating compositions for antireflection. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 9

Uniformly mix 26 parts by weight of low-refraction-thermosetting material C, 70 parts by weight of high-refraction-UV curing material F and 4 parts by weight of Fluorad FC4430 (3M) as a fluorinated compound to prepare compatible antireflection coating composition. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 10

A metal fluoride-dispersion was prepared by uniformly mixing 50 parts by weight of 10% MgF ₂ -dispersion, 30 parts by weight of magnesium trifluoroacetate, and 20 parts by weight of methyl ethyl ketone (MEK).

Uniformly mix 8 parts by weight of low-refraction-thermosetting material C, 75 parts by weight of high-refraction UV-curable material F and 17 parts by weight of the metal fluoride-dispersion liquid to prepare a compatible coating composition for antireflection . A coating film was prepared in the same manner as in Example 3 using this composition.

Example 11

A coating solution and a coating film were prepared in the same manner as in Example 10, except that Material A was used instead of Material C as the low-refractive-thermosetting material.

Example 12

Uniformly mix 25 parts by weight of the low refraction-thermosetting material D, 70 parts by weight of the high refraction-UV curable material F and 5 parts by weight of the metal fluoride-dispersion liquid prepared in Example 10 to prepare a compatible Antireflection coating composition. A coating film was prepared in the same manner as in Example 3 using this composition.

Example 13

10 parts by weight of NaMgF ₃ having an average particle size of 30 to 40 nm and 90 parts by weight of isopropyl alcohol (IPA) were uniformly mixed to prepare a metal fluoride-dispersion liquid. A coating solution and a coating film were prepared in the same manner as in Example 10 except for using this metal fluoride-dispersion liquid.

Example 14

A nanoparticle dispersion liquid was prepared by uniformly mixing 10 parts by weight of mesoporous silica having an average particle size of 20 nm and a porosity of 20% and 90 parts by weight of methanol. A coating solution and a coating film were prepared in the same manner as in Example 10 except for using this nanoparticle dispersion.

Comparative Example 1

Only the high refraction-UV curing material E was used as a material for forming a coating layer, and it was coated on a triacetate cellulose film having a thickness of 80 μm using a wire bar (No. 5). The film was dried in an oven at 60° C. for 2 minutes, and cured by irradiating a dose of 1 J/cm ² of UV to prepare a coating film. The thickness of the coating film was about 1 μm.

Comparative Example 2

Only the low-refraction-thermosetting material A was used as a material for forming the coating layer, and it was coated on a triacetate cellulose film having a thickness of 80 μm using a wire bar (No. 5). The film was thermally cured in an oven at 120° C. for 1 day to prepare a coating film. The thickness of the coating film was about 1 μm.

Comparative Example 3

Only the low-refractive-thermosetting material B was used as a material for forming the coating layer, and it was coated on a triacetate cellulose film having a thickness of 80 μm using a wire bar (No. 5). The film was thermally cured in an oven at 120° C. for 1 day to prepare a coating film. The thickness of the coating film was about 1 μm.

Comparative Example 4

Only the high refraction-UV curing material F was used as a material for forming a coating layer, and it was coated on a triacetate cellulose film having a thickness of 80 μm using a wire bar (No. 5). The film was dried in an oven at 120°C for 2 minutes, cured by irradiating UV with a dose of 200 mJ/cm ² , and placed in an oven at 120°C for 1 day. The thickness of the coating film was about 1 μm.

Comparative Example 5

Uniformly mixed 25 parts by weight of low-refraction-thermosetting material G, 70 parts by weight of high-refraction-UV curing material H and 5 parts by weight of trifluoroethyl acrylate as a fluorinated compound to prepare compatible antireflection coating composition. This composition was used in the same manner as in Example 3 to prepare a coating film.

Comparative Example 6

Uniformly mix 25 parts by weight of the low-refraction-thermosetting material G, 70 parts by weight of the high-refraction-UV curing material H and 5 parts by weight of the metal fluoride-dispersion prepared in Example 10 to prepare a compatible Antireflection coating composition. This composition was used in the same manner as in Example 3 to prepare a coating film.

Test Example

The low-refractive materials and high-refractive materials prepared in Preparation Examples were used to prepare cured products, and their refractive indices and surface energies were measured, which are shown in Table 1. Methods for preparing cured products from various materials are described below. The low-refraction-thermosetting material was coated on a cellulose triacetate film with a thickness of 80 μm using a wire rod (No. 5), and placed in an oven at 120° C. for 1 day. The high-refractive-UV-curable material was coated in the same manner as the low-refractive material, except that it was dried in an oven at 60°C for 2 minutes and irradiated with a UV-cured dose of 200 mJ/ ^cm2 . A prism coupler (Sairon Technology) was used to measure the refractive index, and a drop shape analysis system (Drop shape analysis system) DSA100 (KRUSS) was used to measure the surface energy, and water and diiodomethane (CH ₂ I ₂ ) were used as standard samples .

[Table 1]

The coating films prepared by the methods of Examples and Comparative Examples had a thickness of 1 μm. The anti-reflection films prepared in Examples and Comparative Examples were evaluated for abrasion resistance and optical characteristics including reflectance, transparency, and haze as follows:

1) Evaluation of scratch resistance

Each coating film was tested 10 times with steel wool (#0000) under a load of 1 kg, and then the occurrence of scratches was evaluated.

2) Evaluation of reflectivity

The back side of the coating film was treated with black, and then the reflectance was measured using a Solid Spec. 3700 spectrophotometer (Shimadzu) to determine the antireflection performance depending on the minimum reflectance.

3) Evaluation of transparency and haze

Transparency and haze of the coating films were evaluated using HR-100 (Murakami, Japan).

The evaluation results of reflectance, transparency and haze are shown in Tables 2 and 3 below.

[Table 2]

[table 3]

As shown in Tables 2 and 3, the coating films prepared in Examples 1 to 14 exhibited good scratch resistance to have excellent abrasion resistance, and exhibited excellent optical properties (including reflectivity, transparency and haze). Meanwhile, the coating films prepared in Comparative Examples 1 and 4 to 6 exhibited inferior optical characteristics (including transparency and haze) compared with those of Examples. Since the coating films prepared in Comparative Examples 2 and 3 exhibited poor scratch resistance, an additional hard coating process was required. Therefore, there arises a problem that processing efficiency decreases.

According to Examples and Comparative Examples, the antireflection film according to the present invention can be prepared by a one-step coating method, thereby improving processing efficiency and reducing production cost, and achieving excellent antireflection characteristics and abrasion resistance.

The present invention has been described with reference to preferred embodiments, and although specific terminology has been used in this application, the scope of the present invention is not limited to these specific embodiments, but should be understood on the basis of the appended claims .

Claims (22)

1. A coating composition for antireflection, comprising a low-refractive material with a refractive index of 1.2 to 1.45 and a high-refractive resin with a refractive index of 1.46 to 2, wherein the surface energy difference between the two materials is 5mN/ more than m. 2. The coating composition for antireflection according to claim 1, wherein the surface energy of the low refractive material is 25 mN/m or less. 3. The coating composition for antireflection according to claim 1, wherein the low refractive material is a thermosetting resin and the high refractive material is a UV curable resin. 4. The coating composition for antireflection according to claim 3, wherein the low refractive material comprises an alkoxysilane reactant, a carbamate reactive group compound, One or more of urea-reactive compound and esterification reactant. 5. The coating composition for antireflection according to claim 3, wherein the high refractive material comprises an acrylate resin, a photoinitiator and a solvent. 6. The coating composition for antireflection according to claim 1, wherein, based on 100 parts by weight of the total coating composition, the content of the high refractive material is 10 to 90 parts by weight and the low The content of the refraction material is 5 to 80 parts by weight. 7. The coating composition for antireflection according to claim 1, wherein a difference in refractive index of cured products of the low-refractive material and the high-refractive material is 0.01 or more. 8. The coating composition for antireflection according to claim 1, wherein the coating composition for antireflection further comprises at least one of a fluorinated compound and a nanoparticle dispersion. 9. The coating composition for antireflection according to claim 8, wherein the refractive index of the fluorinated compound is 1.5 or less, its molecular weight is smaller than that of the low refractive material, and its surface energy is at a high refractive index. Between the surface energy of the material and the low refractive material. 10. The coating composition for antireflection according to claim 8, wherein the nanoparticle dispersion liquid contains nanoparticles having an average particle size of 1,000 nm or less. 11. The coating composition for antireflection according to claim 8, wherein the nanoparticle dispersion has a refractive index of 1.45 or less. 12. The coating composition for antireflection according to claim 10, wherein the nanoparticle dispersion liquid further comprises a dispersion-enhancing chelating agent, a fluorinated acrylate, and a solvent. 13. The coating composition for antireflection according to claim 10, wherein the nanoparticles are metal fluorides or organic/inorganic hollow or porous particles. 14. A method for preparing an antireflection film, comprising the steps of: a) preparing the coating composition for antireflection according to any one of claims 1 to 13; b) applying the coating composition to a substrate to form a coating; c) drying the coating to phase separate the low and high refractive materials; and d) Curing the dried coating. 15. The method for preparing an anti-reflection film according to claim 14, wherein, in step b), the thickness of the dried coating is 1 to 30 μm. 16. The method for preparing an anti-reflection film according to claim 14, wherein, the low refractive material is a thermosetting resin and the high refractive material is a UV curable resin, and step d) comprises the following steps: d1) in the range of 0.1 to Curing the high refraction-UV curable resin by irradiating UV for 1 to 600 seconds at a dose of 2 J/cm ² ; and d2) curing the low refraction-thermosetting resin at a temperature of 20 to 200° C. for 1 to 72 hours. 17. An antireflection film, which is prepared using the coating composition for antireflection according to any one of claims 1 to 13, wherein the antireflection film comprises a single-layer coating, in which The low-refractive material and the high-refractive material in the layer coating have concentration gradients in the thickness direction. 18. The antireflection film according to claim 17, wherein the antireflection film is prepared by a method comprising the steps of: a) preparing a coating composition for antireflection, which contains a low Refractive resins and high-refractive materials with a refractive index of 1.46 to 2, and the difference in surface energy between the two materials is more than 5mN/m; b) applying the coating composition to a substrate to form a coating; c) drying the coating to phase separate the low and high refractive materials; and d) Curing the dried coating. 19. The antireflection film according to claim 17, wherein, based on the total weight of the low-refractive material, contained in an area corresponding to 50% in the thickness direction from the air-facing surface of the single-layer coating The low refractive material is more than 70%. 20. The antireflection film according to claim 17, wherein the reflectance is lower than 3%. 21. A polarizer comprising: a) a polarizing film; and b) the antireflection film of claim 17. 22. A display device comprising the antireflection film according to claim 17.

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