KR20000059818A - Producing method of the reflection preventive transparent sheet with a excellent antipollution - Google Patents

Abstract

PURPOSE: A method for preparing an antireflection film is provided, which antireflection film is hardly polluted by or a fingerprint or impurities, is used to a flat display apparatus, and is easily produced massively. CONSTITUTION: The method comprises the steps of preparing the coating solution which is made by mixing the UV curing resin composition consisting of a UV curing acryl urethane-based resin, a photopolymerization initiator and a solvent; the silica dispersion composition consisting of an acryl-based resin having intramolecular hydrophilic groups, silica particle, a dispersing agent and a solvent; and a diluent; coating a substrate sheet(1) with the coating solution; drying the coating; exposing the coating to UV to cure the coating to form UV curing resin layer(2) where silica particles(3) are dispersed; and coating the resin layer with a fluorine-based silane coupling agent to form the fluorine-containing layer(4).

Description

PROCESSING METHOD OF THE REFLECTION PREVENTIVE TRANSPARENT SHEET WITH A EXCELLENT ANTIPOLLUTION}

The present invention relates to a method for manufacturing an anti-reflective transparent sheet having excellent antifouling properties. In a flat panel display device, glare and screen scratches caused by reflection of external light are prevented. Not only that, but also to make it easy to remove contaminated material.

In general, an antireflection sheet due to diffuse reflection has a function of preventing glare due to reflected light by scattering light incident from the outside. In particular, in the case of the anti-reflection sheet used in the flat panel display device, since it is placed on the outermost surface of the display device, it is necessary to have a protective property against external stimulation and environmental changes. Therefore, it is important to have anti-reflective properties and scratch resistance and anti-fouling properties.

As a conventional anti-reflective processed workpiece, a mat-like workpiece (1) which gives irregularities to the surface of a substrate to give a roller with irregularities to give a diffuse reflection effect, and a diffused workpiece using a difference in compatibility or crystallinity of a resin (2) ), A workpiece (3) made of a thin coating of an inorganic compound is known. However, in order to manufacture the above (1), the film surface must be flexible, so that the scratch resistance of the surface of the substrate is inferior, and (2) changes in the compatibility and crystallization characteristics of the resin according to temperature change and solvent. There are disadvantages that can occur. In addition, the workpiece of (3) is formed by forming a thin monolayer or a multilayer inorganic thin layer on the surface of the substrate in accordance with the wavelength of the light beam, and the substrate that can be used is limited, and the process of thinning the inorganic substance requires additional apparatus and complexity. There is a disadvantage of losing.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a method for producing an anti-reflective sheet that can be mass-produced by a simple method, and particularly excellent antifouling properties.

1 is a cross-sectional view of the antireflective transparent sheet of the present invention

※ Explanation of Codes on Major Parts of Drawings

1. Transparent base material 2. UV curable resin layer

3. Silica particles 4. Fluorine-containing layer

The present invention is a UV curable resin composition, a silica dispersion composition and a coating liquid mixed with a diluent in an appropriate ratio is applied on a base sheet, and dried to make an ultraviolet curable resin layer in which silica particles are dispersed by irradiating ultraviolet rays to cure the coating film, Provided is an antireflective transparent sheet manufacturing method having excellent antifouling properties using a method of coating a fluorine-containing layer having a refractive index of 1.40 or less thereon.

In the present invention, the ultraviolet curable resin composition contains an ultraviolet curable acrylic urethane resin, a photopolymerization initiator, a solvent, and the like, and the silica dispersion composition is composed of an acrylic resin, a silica particle, a dispersant, a solvent, and the like containing a hydrophilic group in a molecule thereof. Diluent is an organic solvent added to adjust the viscosity and solids content of the coating solution. As a method of applying a coating liquid mixed with an ultraviolet curable resin composition, a silica dispersion composition and a diluent in an appropriate ratio on a base sheet, gravure coater, spray coater, slot orifice coater, etc., which are general solution coating methods, can be used. Since it can be used for continuous line, mass production is easy and it is advantageous in terms of cost. In the present invention, by applying a low refractive index fluorine compound on the ultraviolet curable resin layer in which silica particles are dispersed, a low reflection effect is added to the diffuse reflection effect by silica particles, and the fluorine-containing layer has waterproof, oil repellent, and antifouling properties. It is not easily contaminated with fingerprints or foreign objects, and also facilitates removal of contaminated material.

The ultraviolet curable acrylic urethane resin contained in the ultraviolet curable resin composition of the present invention is generally obtained by reacting an isocyanate monomer or a prepolymer with a polyester polyol and reacting an acrylate or methacrylate monomer containing a hydroxyl group thereto. This acrylic urethane-based resin is characterized by having a urethane bond in the molecular skeleton and an acryl group or a methacryl group derived from an acrylate or methacrylate monomer at an arbitrary position (effectively at the molecular end) in the molecule. Isocyanate monomers or prepolymers that react with the polyester polyols include isocyanate prepolymers polymerized with toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, diol or diamine and the like. Examples of the acrylate or methacrylate monomer having a hydroxyl group include 2-hydroxyethyl acrylate and 2-hydroxypropyl methacrylate. By using the above acrylic urethane-based resin, ultraviolet curing of the resin composition becomes possible and a cured film excellent in scratch resistance can be obtained.

In the UV curable resin composition, the photopolymerization initiator is used to increase the curability. For example, benzophenone, benzyl ketone, 2-chloro- thioxanthone, 2,4-diethyl-thioxanthone, benzoin ethyl Ether, diethoxyacetophenone, benzyl methyl ketal, 2-hydroxy-2-methylpropiophenone, 1-hydroxy-cyclohexyl phenyl ketone, and the like as sensitizers such as amines and urea compounds. It may be.

Solvents used in the UV curable resin composition should be inert to the material used as the substrate and have good compatibility with compositions such as resins. The solvent which can be used here is toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, etc., These solvents can be used individually or in mixture.

The silica dispersion composition of the present invention is composed of an acrylic resin, a silica particle, a dispersant, a solvent, and the like containing a hydrophilic group in a molecule to be mixed with an ultraviolet curable resin composition in order to impart a diffuse reflection effect to a transparent sheet. Acrylic resin is a film control agent to allow the resin composition to form a film and serves to reduce the influence of oxygen during ultraviolet curing. In addition, this acrylic resin acts as a thickener for maintaining the viscosity of the coating liquid at a predetermined level or more, and has a hydrophilic group in the molecule, thereby improving dispersion stability of the silica particles. As the acrylic monomer capable of forming such an acrylic resin, alkyl acrylate or methacrylate such as ethyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, methyl methacrylate and hydroxyethyl acrylate, Non-functional monomers such as acrylate or methacrylate having a hydroxyl group such as 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, vinyl acetate, styrene, acrylonitrile, acrylic acid, methacrylic acid, glycine Functional monomers such as dimethyl methacrylate. Acrylic resins using two or more of these monomers alone or in combination are possible, but in the present invention, it is preferable to use a monomer in which a hydrophilic group may be included in the acrylic resin molecule in order to increase dispersion stability of silica particles.

In the present invention, irregularities are formed in the cured film using silica particles, and a method in which a diffuse reflection effect is imparted by the irregularities is used. The silica particles used in the silica dispersion composition are composed of silicon dioxide, have amorphous, porous properties, and the particles are preferably spherical in shape. And it is suitable that the size of a silica particle is 1-15 micrometers. When the particle size is 1 μm or less, there is a disadvantage in that the surface area is increased with respect to the volume of the particle, and thus the surface energy increases, so that aggregation occurs easily, and the amount of silica particles must be increased in order to obtain a constant level of diffuse reflection effect. On the contrary, when the size of the silica particles is larger than 15 μm, the coating property is poor, the surface state of the coating film is rough, and the sharpness is poor. In many cases, the particles are agglomerated by sharing oxygen on the surface of the silica particles. In order to show excellent optical properties of the coating film after coating, the silica particles must be uniformly dispersed in the coating liquid. In order to improve the dispersibility of silica particles, there are milling methods such as ball mills and sand mills. Such milling methods are suitable when the size of the particles is larger than 15 μm, but when the size of the particles is small, Since there is a problem of re-agglomeration, the method of stirring and dispersing at high speed with a stirrer is used. After dispersion of the silica particles, the dispersion stability should be excellent so that the dispersed state of the particles can be kept constant. In the present invention, in order to prevent sedimentation of the silica particles, an acrylic resin containing a hydrophilic group in the molecule and a dispersant such as unsaturated polycarboxylic acid, unsaturated polyamine amide, polysiloxane copolymer, silicone oil and the like were used in the silica dispersion composition.

In the silica dispersion composition, the solvent may be used alone or mixed with isopropanol, methyl ethyl ketone, toluene, ethyl acetate, butyl acetate and the like.

The diluent used in the present invention is an organic solvent added to adjust the viscosity and solids content of the coating liquid, and toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, or the like can be used alone or in combination.

In addition to the components added to the above compositions, various additives may be added as long as the object of the present invention is not impaired, for example, pigments, dyes, antistatic agents and the like.

In order to manufacture the antireflective transparent sheet having excellent antifouling properties provided by the present invention, first, a transparent sheet coated with an ultraviolet curable resin layer in which silica particles are dispersed should be manufactured, and the method is as follows. First, the ultraviolet curable resin composition is prepared so as to be 20 to 80 wt% of the ultraviolet curable acrylic urethane resin, 0.1 to 10 wt% of the photopolymerization initiator, and 10 to 70 wt% of the solvent, and a diluent is prepared. The mixing ratio of the silica dispersion composition to the ultraviolet curable resin composition is determined according to the degree of the diffuse reflection effect of the desired transparent sheet. The addition amount of the diluent is determined so that the coating liquid has an appropriate viscosity (3-50 cps Brookfield viscosity at 25 ° C.) and a solid content (15-65 wt%). In this way, a coating liquid obtained by mixing a UV curable resin composition, a silica dispersion composition, and a diluent in an appropriate ratio is applied onto a base sheet. It is apply | coated so that the thickness of the film after drying may be 1-10 micrometers normally, and it irradiates an ultraviolet-ray after heat-drying, and hardens a film. As the base sheet, any film that is transparent and strong against UV rays such as polyester film, polycarbonate film, polyacryl film, and polyamide film can be used, and triacetate used as a protective film for a polarizing plate, which is a part of a liquid crystal display device. Cellulose films are also possible.

In order to give antifouling property and low reflection effect to the transparent sheet coated with the ultraviolet curable resin layer in which the silica particles are dispersed in the above-described manner, a fluorine-containing layer having a refractive index of 1.40 or less is formed by coating a fluorine-containing compound on the ultraviolet curable resin layer. . The fluorine-containing compound forming the fluorine-containing layer is prepared by fluorine-based silane coupling agent under an acid or alkali catalyst. The fluorine-based silane coupling agent used in the present invention selects one or two or more selected from the following formula (1).

Where X is CF _3- , CF ₃ -CF _2- , CF ₃ -CF ₂ -CF _2- , (CF ₃ ) ₂ -CFO-, or CF _3- (CF ₂ ) _y -CH ₂ -O y is an integer of 1 to 8, R is an alkyl group having 1 to 4 carbon atoms, Y is a methoxy, ethoxy, methoxyethoxy, chlorine atom, m is an integer of 0 to 12, x is 0 Or an integer of 1 to 2, n is an integer of 1 to 3, n + x = 3)

The fluorine-based silane coupling agent of Formula 1 has a refractive index in the range of 1.30 to 1.40, and specific examples thereof include trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltrichlorosilane, Heptafluoropropyltrimethoxysilane, Heptafluoropropyltriethoxysilane, Heptafluoropropylmethyldimethoxysilane, Heptafluoropropyltrichlorosilane, Heptafluoroisopropoxypropyltrimethoxysilane, Heptafluoro Isopropoxypropyltriethoxysilane, heptafluoroisopropoxypropyltrichlorosilane, tridecafluorohexylethyltrimethoxysilane, tridecafluorohexylethyltrichlorosilane, heptadecafluorooctoxypropyltrimeth Methoxysilane, heptadecafluorooctoxypropyl triethoxysilane, and the like.

The fluorine-containing compound of the present invention is obtained by dissolving the above fluorine-based silane coupling agent in an organic solvent at a concentration of 0.01 to 20% by weight, followed by hydrolysis by addition of an acid or an alkali such as hydrochloric acid, nitric acid, phosphoric acid, or amine. Suitable organic solvents here include hexane, cyclohexane, heptane, octane, methylcyclohexane, toluene, benzene, xylene, methanol, ethanol, isopropanol, butanol, pentanol, cyclohexanol, methylcyclohexanol, phenol, cresol, ethyl Ether, propyl ether, tetrahydrofuran, dioxane, acetone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, methyl benzoate, chloroform Hydrocarbons such as carbon tetrachloride, trichloroethane, cellosolve, cellosolve acetate, alcohols, ethers, esters, carboxylic acids, and halogen-substituted hydrocarbons. Especially isopropanol, butanol, normal hexane, toluene, etc. are good, and these organic solvents can be used individually or in mixture of 2 or more types.

Coating, spraying, and dipping methods of a fluorine-containing compound obtained by hydrolyzing a fluorine-based silane coupling agent using a knife coater, bar coater, gravure roll coater, etc., on a transparent sheet coated with an ultraviolet curable resin layer in which silica particles are dispersed. It is applied by, for example, and cured by heat drying to form a fluorine-containing layer. In this case, the fluorine-containing layer has a thickness ranging from 5 to 200 nm to impart a low reflection effect due to a low refractive index, thereby lowering the reflectance of the transparent sheet, and imparting water repellency, oil repellency, and antifouling properties to fingerprints and foreign substances. As it is not easily contaminated, it also acts as an anti-fouling film to remove contaminated material.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, and the method for evaluating the physical properties of the prepared transparent sheet is as follows. In other words, the light transmittance and reflectance of the sheet is measured by an ultraviolet-visible spectrophotometer (Beckman DU-70), and the antifouling property is a method of comparing the light transmittance and reflectance of the sheet before and after contamination. Transmittance and reflectance are measured after peeling the adhesive tape with rubber eraser 10 times on the anti-reflective film and applying force in the vertical direction to remove the tape.The surface hardness of the cured film is measured with a pencil hardness tester (JIS K 5401). Measure

<Example 1>

First, 48% by weight of the acrylic urethane resin (UCB: U3357), 2% by weight of the photoinitiator (Ciba Specialty Chemicals: Ipgacure-184), 50% of the mixed solvent of butyl acetate / methyl ethyl ketone in a ratio of 2/1 % Is uniformly mixed to prepare an ultraviolet curable resin composition. In addition, 45% by weight of an acrylic resin (hydrophilic product manufactured by BF Goodrich Co., Ltd .: Carbosset 526) containing a hydrophilic group in the molecule, 2% by weight of a dispersant (by-terra oil) manufactured by BYK, isopropyl alcohol / methyl ethyl ketone After adding all of the silica particles to the resin solution prepared by uniformly mixing 45% by weight of the mixed solvent in a ratio of 1/1, the stirrer was stirred at a high speed for 5 hours or more to prepare the silica dispersion composition. .

Toluene was uniformly mixed in a proportion of 30 parts by weight of the silica dispersion composition and 75 parts by weight of a diluent with respect to 100 parts by weight of the ultraviolet curable resin composition prepared above, and passed through a 10 μm filter to prepare a coating solution. The coating solution thus prepared was coated on a 125 μm thick polyester film using a gravure coater, dried at 90 ° C., and then irradiated with ultraviolet light using an ultraviolet light lamp (high pressure mercury lamp: 80 W / cm) to disperse the silica particles in an ultraviolet curable resin layer. This formed transparent sheet is manufactured. The solution of the fluorine-containing compound to be coated on the ultraviolet curable resin layer of this sheet is dissolved in an isopropanol and butanol mixed solution at a concentration of 0.05% by weight of fluorosilane coupling agent trifluoropropylmethoxysilane and hydrolyzed by adding hydrochloric acid. It is prepared by the method. This solution is coated with a gravure coater on the ultraviolet curable resin layer of the transparent sheet coated with the ultraviolet curable resin layer in which silica particles are dispersed, and dried at 110 ° C to form a fluorine-containing layer.

<Example 2>

Except for forming an ultraviolet curable resin layer containing silica particles dispersed in a coating liquid prepared by mixing 10 parts by weight of the silica dispersion composition and 65 parts by weight of toluene with a diluent based on 100 parts by weight of the ultraviolet curable resin composition of Example 1. Then, an antireflective transparent sheet was manufactured in the same manner as in Example 1.

<Example 3>

An antireflective transparent sheet was prepared in the same manner as in Example 1, except that heptadecafluorooctoxypropyltriethoxysilane was hydrolyzed as a fluorine-containing compound.

<Example 4>

An antireflective transparent sheet was prepared in the same manner as in Example 2, except that heptafluoroisopropoxypropyltrimethoxysilane was hydrolyzed as a fluorine-containing compound.

<Example 5>

An antireflective transparent sheet was prepared in the same manner as in Example 4, except that triacetate cellulose having a thickness of 80 μm was used as the transparent substrate.

<Comparative Example 1>

In the same manner as in Example 1, a transparent sheet coated with a silica-cured ultraviolet curable resin layer was prepared, and no fluorine-containing layer was formed on the sheet.

<Comparative Example 2>

In the same manner as in Example 2, a transparent sheet coated with a silica-cured ultraviolet curable resin layer was prepared, and no fluorine-containing layer was formed on the sheet.

The physical properties of the transparent sheets obtained in the above Examples and Comparative Examples were measured and shown in Table 1 below.

Before pollution After pollution Surface hardness Light transmittance reflectivity Light transmittance reflectivity Example 1 93.0 0.74 92.4 0.80 4H Example 2 93.9 0.76 92.4 0.81 4H Example 3 93.8 0.78 92.0 0.83 4H Example 4 93.1 0.73 92.6 0.78 4H Example 5 94.2 0.71 93.7 0.77 4H Comparative Example 1 89.8 1.92 81.5 2.72 4H Comparative Example 2 91.5 1.60 83.0 2.10 3H

As shown by the above examples and comparative examples, the anti-reflective transparent sheet according to the present invention exhibits low reflectance, has an excellent anti-reflective effect, and exhibits antifouling resistance and good scratch resistance, which are not contaminated. It is possible to manufacture an antireflective transparent sheet having excellent antifouling properties.

Claims (2)

On the base sheet, a coating solution is obtained by mixing an ultraviolet curable acrylic urethane resin, a photopolymerization initiator, a solvent-containing ultraviolet curable resin composition, an acrylic resin containing a hydrophilic group in a molecule, silica particles, a dispersant, a solvent-containing silica dispersion composition, and a diluent. After coating and drying, a method of curing the coating film by irradiating ultraviolet rays to form an ultraviolet curable resin layer in which silica particles are dispersed, and the fluorine-based silane coupling agent is hydrolyzed and coated with a fluorine-containing layer having a refractive index of 1.40 or less. Method for producing this excellent antireflective transparent sheet. The method for producing an antireflective transparent sheet having excellent antifouling properties according to claim 1, wherein the fluorine-containing layer is coated with a fluorine-containing compound obtained by hydrolyzing one or two or more of the fluorine-based silane coupling agents represented by the following Chemical Formula 1. . <Formula 1> Where X is CF _3- , CF ₃ -CF _2- , CF ₃ -CF ₂ -CF _2- , (CF ₃ ) ₂ -CFO-, or CF _3- (CF ₂ ) _y -CH ₂ -O y is an integer of 1 to 8, R is an alkyl group having 1 to 4 carbon atoms, Y is a methoxy, ethoxy, methoxyethoxy, chlorine atom, m is an integer of 0 to 12, x is 0 Or an integer of 1 to 2, n is an integer of 1 to 3, n + x = 3)