KR20130124648A

KR20130124648A - Optical film

Info

Publication number: KR20130124648A
Application number: KR1020120047913A
Authority: KR
Inventors: 황병우; 윤우석; 이미선
Original assignee: (주)세화피앤씨
Priority date: 2012-05-07
Filing date: 2012-05-07
Publication date: 2013-11-15

Abstract

The present invention relates to an optical film, more specifically, a base film; It is formed on one side of the base film, 10 to 50% by weight based on the weight of the titanium dioxide on the surface of titanium dioxide or the metal doped titanium dioxide doped with a metal component in the titanium dioxide having an average particle diameter range of 5 to 100nm 5 to 20 parts by weight of the curable binder solution and 10 to 40 parts by weight of the leveling agent solution, with respect to 100 parts by weight of the solution including the filler and the dispersant and the dispersion medium in the form of a titanium dioxide core-absorbable silicon dioxide shell in the form of porous silicon dioxide in the range It relates to a film comprising a coating layer containing a coating liquid containing a portion increased by drying after drying 500nm to 1μm on the basis of the dry film thickness, and the film containing the anti-staining coating layer of the present invention is increased and the anti-staining film of the titanium dioxide core-oil-absorbing silicon dioxide shell Filling material is applied to wet coating of single layer to reduce reflectance and increase transmittance. It absorbs and decomposes oil quickly and prevents stains. In addition, it can also be manufactured in a re-peelable multi-layer structure can extend the service life of the film.

Description

Optical film {OPTICAL FILM}

The present invention relates to an optical film, and more particularly to a base film; It is formed on one side of the base film, the average particle diameter ranges from 10 to 50% by weight based on the weight of titanium dioxide on the surface of titanium dioxide or metal-doped titanium dioxide doped with a metal component in the titanium dioxide To 100 parts by weight of a solution containing 5 to 30% by weight of a filler in the form of a titanium dioxide core-oil absorbent silicon dioxide shell, 0.2 to 1% by weight of a dispersant, and 69 to 94.8% by weight of a dispersion medium of the oil-absorbing silicon dioxide layer of The present invention relates to an optical film including an increase in transmittance and an anti-staining coating layer formed by coating a coating solution including 5 to 20 parts by weight of a curable binder solution and 10 to 40 parts by weight of a leveling agent solution, followed by drying after applying 500 nm to 1 μm of dry film thickness.

While viewing various displays, outdoor sunlight or indoor lighting is often reflected on the surface of the display, resulting in an inability to see the original image. The most efficient way to solve this inconvenience is to minimize the reflection of various external light generated on the display surface. In general, the reflection on the surface can be largely divided into a specular reflection and a diffuse reflection. Direct reflection refers to a reflection with the same incident angle and reflection angle with respect to the surface, which occurs on a surface that can be assumed to be a nearly perfect plane. On the other hand, diffuse reflection is reflection due to surface nonuniformity, and since the actual surface is not parallel to the average surface, it means that the reflected light is scattered according to the nonuniformity of the surface without reflecting the entire amount at the same angle as the incident angle. An AG coating (anti-glare coating) is to induce scattering of external light by giving the concave-convex shape to have a roughness of tens to hundreds of nanometers on the surface of the substrate. By forming a bumpy surface on the outermost side of the display to reduce direct reflection and diffuse reflection at various angles, it can be described as a method of obtaining the effect by reducing the intensity of reflected light entering the viewer's field of view at a particular angle. Anti-reflection coatings, unlike AG, which have a scattering effect through diffuse reflection, reduce the reflectance of the direct reflection itself. While the AG coating effectively distributes the reflection of external light, the image passing through the AG coating surface has the disadvantage of degrading the image clarity under the influence of the surface irregularities. AR coatings are used that reduce the reflectance of direct reflection. In general, AR coating is composed of two or more thin films having different refractive indices so that the wavelengths reflected at the interface of each thin film cause the interference to disappear. The AR effect can be mainly represented by optical properties such as average and minimum reflectance, and reflected wavelength patterns. The main factors affecting the optical properties are the refractive indices of the high and low refractive materials, the number of thin films, and the thickness of each layer. The larger the difference in refractive index between the two thin films, the lower the reflectance, the pattern of the reflected wavelength is shifted according to the thickness of the thin film, and as the number of thin films increases, the reflectance tends to be uniformly lower in the full-wavelength region of visible light. In order to increase the AR effect, it is ideal to increase the number of thin films and increase the difference in refractive index to lower the average reflectance as much as possible, but in reality, considering the process and material constraints, the lowest reflectance near 550 nm, which is the region of visible light sensitive to the human optic nerve, is achieved. Thin film design is shown.

Republic of Korea Patent Publication No. 10-2010-0112740, the high refractive index hard coating layer 20 and the low refractive index layer 30 are sequentially stacked on at least one surface of the base film 10, the low refractive index layer 30 The surface of has fine irregularities, the arithmetic mean roughness (Ra) of the irregularities is characterized in that 0.0001㎛ ~ 0.005㎛, and the low refractive index layer 30 is 3 to 15 parts by weight of hollow silica compared to 100 weight of the binder resin A low reflection film comprising is disclosed. Thus, a low-reflection film in which a hard coating layer and a low refractive index layer having a high refractive index controlled on the base film are laminated in a two-layer structure is provided, but the surface roughness of the hard coating layer and the low refractive index layer is controlled to be lower than that of a conventional low reflection film. Provided is a low reflection film capable of improving surface hardness, scratch resistance and fingerprint removal. In addition, the patent publication of the Republic of Korea Patent No. 516097 includes a high refractive index layer, a low refractive index layer and a core-shell nanoparticle layer continuously, the core of the core-shell nanoparticles constituting the core-shell nanoparticle layer is a nano metal particle And an outer surface forming the shell is made of silica or a low refractive index material.

However, the low-reflection film disclosed in the above document has a problem that the structure is complicated in a multi-layered structure, the light transmittance is lowered, and the film thickness is somewhat inevitable. In addition, when such a coating is formed on a touch screen panel or the like, contamination or stain due to touch becomes a problem. To prevent such stains, AG coating (Anti-glare coating) minimizes the area where oil is adsorbed on the surface, hides the stain with surface haze, or applies water-repellent / oil-repellent material with low surface energy to contaminate the coating surface. You can use this method to prevent this from sticking well. However, AG coating has a tendency of lowering transmittance and image clarity due to surface irregularities, and water / oil repellent coating has to use expensive materials, and fluorine compounds used as main materials are regulated as environmental pollutants. In addition, there is a disadvantage that the performance is drastically deteriorated with time.

Republic of Korea Patent Publication No. 10-2010-0112740 Republic of Korea Patent No. 516097

Therefore, the technical problem to be achieved by the present invention is to reduce the reflectance even in a single layer by wet coating using a nano-sized titanium dioxide core-oil-absorbing silicon dioxide shell type fillers to increase the transmittance and further adsorption, decomposition of oil It is to provide an optical film that can be maintained for a long time while preventing stains.

In order to achieve the above technical problem, the present invention is a base film; It is formed on one side of the base film, the average particle diameter ranges from 10 to 50% by weight based on the weight of titanium dioxide on the surface of titanium dioxide or metal-doped titanium dioxide doped with a metal component in the titanium dioxide To 100 parts by weight of a solution containing 5 to 30% by weight of a filler in the form of a titanium lipophilic silicon dioxide shell having a porous lipophilic silicon dioxide layer, 0.2 to 1% by weight of a dispersant, and 69 to 94.8% by weight of a dispersion medium. Permeability increase and stain formed by coating the coating solution containing 5 to 20 parts by weight of the curable binder solution composed of the curable binder and the solvent and 10 to 40 parts by weight of the leveling agent solution composed of the leveling agent and the solvent, followed by drying after applying 500 nm to 1 μm of the dry film thickness. It provides an optical film including a protective layer.

In addition, the present invention provides an optical film characterized in that it further comprises an adhesive layer on the other side of the base film.

In the present invention, the curable binder is a C1 ~ C6 hydrocarbon group R1 is a vinyl group, or a methacryloxy group, a mercapto group, an amino group or an epoxy group, R2 is a C1-C4 hydrocarbon group, R3 is a C1-C8 The hydrocarbon group or the acyl group, a and b provide an optical film, which is an alkoxysilane represented by the formula R1aR2bSi (OR3) 4-ab, or a hydrolyzate or partial hydrolyzate thereof, each being 0 or 1.

In addition, the present invention is that the curable binder solution is at least one selected from the group consisting of tetraethyl orthosilicate, methyltriethoxysilane, methyltrimethoxysilane, diethoxydimethylsilane and diethoxydiethylsilane Characterized in that the curable binder is composed of 5 to 20% by weight and 80 to 95% by weight of lower alcohol of C1 to C6 as a solvent.

In addition, the present invention, the base film; It is formed on one side of the base film, the average particle diameter ranges from 5 to 100nm and based on the weight of titanium dioxide on the metal-doped crystalline titanium dioxide surface doped with titanium dioxide or a metal component in the titanium dioxide To 100 parts by weight of a solution comprising from 5 to 30% by weight of a filler in the form of a titanium dioxide core-oil-absorbing silicon dioxide shell and 0.2 to 1% by weight of a dispersant and 69 to 94.8% by weight of a dispersion medium having a porous silicon dioxide layer in the% range. A n-permeability increase and anti-staining coating layer formed by applying a coating solution including 5 to 20 parts by weight of a curable binder solution and 10 to 40 parts by weight of a leveling agent solution, followed by drying; Increased transmittance in which n-adhesive layers are alternately laminated two or more times and multiple layers of the stain leaving coating layer-adhesive layer (where n is 10 or less) A natural number), and; Including the n + 1 adhesive layer on the other side of the base film, wherein the adhesive strength of the m-th adhesive layer of the multi-layer of the increased transmittance and the stain-resistant coating layer-adhesive layer is the m-1 adhesive layer (where m is 2 To provide an optical film characterized in that the weaker than the adhesive strength of n).

The optical film of the present invention is applied to the titanium dioxide core-lipophilic silicon dioxide shell form as a filler to reduce the reflectance even by wet coating of a single layer to increase the transmittance and to prevent staining through fast adsorption and decomposition of oil It can also be manufactured in a re-peelable multi-layer structure can extend the service life of the film.

1 is a structural schematic diagram for understanding the structure of an optical film according to the present invention
Figure 2 is a graph comparing the transmittance of the dry film coating thickness of the optical film according to the present invention
3 is a measurement image of the oleic acid contact angle of the optical film and the general hard coating film according to the present invention
Figure 4 is a graph measuring the color difference change by the methylene blue method of the optical film and the general hard coating film according to the present invention

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a structural schematic diagram for understanding the structure of an optical film according to the present invention. As can be seen in Figure 1, one embodiment of the optical film 100 according to the present invention is formed on one side of the base film 10, the base film 10, the average particle size is the primary particle size Is about 5 to 30nm and the size of the secondary particles dispersed in the dispersion medium is titanium dioxide in the range of 5 to 100nm, when the size of the particle is 100nm or more, light scattering occurs due to the particles cause whitening phenomenon and transmittance decreases The problem arises. Titanium dioxide core-oil-absorbing dioxide, which forms an oil-absorbing silicon dioxide layer in the range of 10 to 50% by weight based on the weight of titanium dioxide on the titanium dioxide or the metal-doped titanium dioxide surface doped with the metal component. 5 to 20 parts by weight of the curable binder solution and 10 to 40 parts by weight of the leveling agent solution, based on 100 parts by weight of the solution including 5 to 30% by weight of the filler in the form of silicon shell and 0.2 to 1% by weight of the dispersant and 69 to 94.8% by weight of the dispersion medium. It includes a coating solution containing a portion to increase the transmittance increase coating layer 20 formed by drying after coating the dry film thickness based on 500nm to 1μm.

In the present invention, the material of the base film 10 is not particularly limited, and any material that requires transparency, such as a known natural or synthetic resin material and, in some cases, glass, may be used.

In the coating solution constituting the transmittance increasing coating layer 20, a method for manufacturing titanium dioxide core-absorbing silicon dioxide shell-type titanium dioxide is iii) a titanium dioxide having an average particle diameter in the range of 5 to 100 nm or a metal component in the titanium dioxide. Preparing a titanium dioxide dispersion by dispersing the metal-doped titanium dioxide doped in an aqueous medium, ii) a silicon dioxide precursor to form a silicon dioxide precursor in the range of 10 to 50% by weight based on the weight of the titanium dioxide Mixing, dispersing, and aging the titanium dispersion to form an oil-absorbing silicon dioxide layer on the titanium dioxide or the metal-doped titanium dioxide; and iii) washing and solvent replacement with a dispersion medium three or more times using a centrifuge to obtain a colloid. It can be prepared by a method comprising the step of. Of course, the colloidal titanium dioxide core-absorbent silicon dioxide shell form of titanium dioxide may be manufactured in powder form through a drying and grinding process. In addition, the dispersion medium in the coating solution is not particularly limited, as long as it can disperse the filler and be sufficiently mixed with the curable binder and the leveling agent and is advantageous for drying. Preferred examples of the dispersion medium are C1 to C6 linear or branched alkyl or alkenyl alcohols or substituents thereof. The dispersing agent is at least one selected from the group consisting of polyacrylate, 1-vinyl pyrrolidone, polyoxyethylene stearate, EDTA, polyester-based polysiloxane, citric acid, cyclodextrin and disodium pyrophosphate. desirable. In the present invention, by using a high refractive index / low refractive composite material as a filler to form a low reflection (LR) coating layer with low reflectivity by forming only a single layer on one side of the base film to increase the light transmittance. The filler used for the low reflection coating layer may have a function of increasing light transmittance by lowering the reflectance even in a single layer by wet coating by supporting silicon dioxide, which is a low refractive material, in a shell form on nano-sized titanium dioxide, which is a high refractive material. In addition, it is possible to prevent a change in reflection angle and refractive index of light due to fingerprints or oil contamination on the surface of the display, thereby preventing aesthetics and impairing visibility. In the present invention, using titanium dioxide having a high refractive index but having a photocatalytic function as a core, the adsorbed oil or pollutants are decomposed by photochemical action to perform a self-cleaning action, and instead have a low refractive index and an oil absorption property. The lipophilic porous silicon dioxide shell absorbs the oil quickly by introducing the excited silicon dioxide into the shell-like material, minimizing surface reflection angle and refractive index change caused by the oil, making stains less likely to occur. The filler of the titanium dioxide core-oil absorbent silicon dioxide shell form of the present invention exhibits semipermanent stain prevention performance by increasing the light transmittance and decomposing the oil adsorbed continuously by the photochemical reaction of the titanium dioxide core.

The curable binder serves to bond the base film and titanium dioxide and titanium dioxide particles to which the transmittance increase and anti-stain coating solution of the present invention is applied and maintain the form of the transmittance increasing coating film, and when mixed with titanium dioxide does not reduce transparency Although not particularly limited, the lower the refractive index, the greater the antireflection effect, and thus, a silica binder having a low refractive index is advantageous as the binder. Preferred examples of the curable binder include photocurable or thermosetting organic monomers or oligomers, organic polymers, or polymer resins including acrylic resins, melamine resins, urethane resins, and polyester resins, and ultraviolet curable compositions. In addition, as the curable binder material, partial hydrolyzate and / or complete hydrolyzate of the organosilicon compound of the formula R1aR2bSi (OR3) 4-a-b may also be applied, wherein all symbols are defined above. Examples of the silicon compound include at least one member selected from the group consisting of tetraethyl orthosilicate, methyltriethoxysilane, methyltrimethoxysilane, diethoxydimethylsilane and diethoxydiethylsilane. It is preferable to dissolve in a solvent in the range of 5 to 20% by weight on the basis.

Further, in the coating composition, the ratio of titanium dioxide and the curable binder is 0.1 to 10, preferably 0.2 to 5, as a binder component of the titanium dioxide / curable binder. When the said ratio is 0.1 or less, a high transparency coating film cannot be obtained. On the other hand, when the ratio is 10 or more, the adhesion between the base material and the coating film deteriorates. The acid, amine, or metal oxide sol, such as silicon, aluminum, zirconium, cerium, iron, tungsten, and other various additives may be blended with the coating composition containing titanium dioxide of the present invention as needed.

The leveling agent is added for the smoothing of the coating liquid when the coating agent is applied to the base film, it is not particularly limited if there is no problem in mixing the filler solution and the curable binder. Preferred examples of the leveling agent in the present invention include siloxane-based materials such as polyether polysiloxane, polyacrylic polysiloxane, and poly dimethylsiloxane, and those dissolved in a solvent in the range of 0.1 to 10% by weight based on the total coating liquid. Do.

The optical film of the present invention is produced by applying the coating solution to a base film and then drying. The transmittance varies depending on the coating thickness of the coating solution, and when the thin film design is applied to show the lowest reflectance near 550 nm, which is a region of visible light sensitive to the human optic nerve, the highest transmittance is obtained at a coating thickness of 500 nm to 1 μm. In general, the thickness required for the permeability increasing film of the present invention is 800 nm, and the thickness of the coating solution may be obtained at about 500 nm to 1 μm nanometer based on the dry coating thickness. You can do this. After coating, drying is performed to increase the transmittance and to form an anti-stain coating layer. The drying is not particularly limited and is generally performed in the range of 80 ° C to 200 ° C.

The optical film 100 of the present invention may further include an adhesive layer 30 on the other side of the base film 10. Using the adhesive layer 30, the optical film 100 of the present invention, such as glass or plastic, may be attached to a desired place. A component constituting the adhesive layer 30 may be a general adhesive component such as silicone or acrylic adhesive, and may be selected and used according to the material or property of the surface to be attached.

In addition, in the optical film 100 of the present invention, the protective film 40, 40 'is further provided on the outside of the increase in transmittance and the anti-staining coating layer 20 and / or the adhesive layer 30 before the user uses the above-mentioned. The protective films 40 and 40 'may be removed and used.

Another example of the optical film of the present invention is a base film; It is formed on one side of the base film, the average particle diameter ranges from 5 to 100nm and based on the weight of titanium dioxide on the metal-doped crystalline titanium dioxide surface doped with titanium dioxide or a metal component in the titanium dioxide 5 to 20 parts by weight of a curable binder solution and 10 to leveling solution, based on 100 parts by weight of a solution including a filler and a dispersant and a dispersion medium in the form of a titanium dioxide core-absorbable silicon dioxide shell having a porous silicon dioxide layer in a% range. An n-permeability increase and anti-staining coating layer formed by applying and coating a coating liquid including 40 parts by weight, and an n-permeability increase layer formed on the n-th transmittance increase and stain-proof coating layer in order to increase the transmittance of alternating stacking two or more times sequentially and Multiple layers of a stain-resistant coating layer-adhesive layer (where n is a natural number of 10 or less); Including the adhesive layer on the other side of the base film, the adhesive strength of the m-th adhesive layer of the multi-layer of the increase in transmittance and the stain-resistant coating layer-adhesive layer of the m-1 adhesive layer (the m is 2 to n) of It is characterized by a weaker than the adhesive strength. As described above, the optical film of the present invention is mainly used for a display such as a touch panel, and in the case of a smartphone or a tablet PC, surface damage may occur due to scratches, etc., in addition to stains caused by contamination when the touch screen is used. There is no choice but to. If the optical film is manufactured in a multi-layer structure and the outermost surface is damaged, only the damaged surface portion is removed and a new surface is used, the service life of the film can be extended. It is preferable. However, in order to prevent the increase in the lower transmittance and the stain-proof coating layer from being peeled together when peeling to remove the outermost transmittance and the stain-resistant coating layer, the m of the multilayers of the stain-resistant coating layer-adhesive layer The adhesive strength of the adhesive layer is preferably weaker than that of the m-1 adhesive layer (wherein m is 2 to n). In the multilayer optical film, n is preferably a natural number of 10 or less, that is, a multilayer structure of 10 or less layers, more preferably 2 to 5. This is because the optical film of the multi-layer structure has a lower layer of light transmittance as the number of layers increases.

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention.

Example 1.

5% by weight of crystalline titanium dioxide (P25, Degussa, Germany) in anatase / rutile phase with an average particle diameter in the range of 21 nm, 1% by weight of tetraethyl orthosilicate as silicon dioxide precursor, 0.1% of nitric acid (60% HNO3) as catalyst Positive distilled water was allowed. Titanium dioxide with anatase crystals was stirred for 30 minutes with ultrasonic and magnetic stirrer in 1 ° C distilled water as a solvent, and tetraethyl orthosilicate was slowly added dropwise using a metering pump. During the addition, the temperature was kept at 1 ° C. and the dispersion was further carried out for 30 minutes by stirring and ultrasonic vibrator for 1 hour after the addition. The dispersed coating solution was aged for 1 hour with stirring at 70 ° C., cooled at room temperature, washed with ethanol three times at 10,000 rpm in a centrifuge, and solvent-substituted to form a colloid loaded with silicon dioxide in titanium dioxide having a colloidal crystalline state. The powder was recovered using a rotary evaporate.

Example 2.

5% by weight of titanium dioxide in the form of a titanium dioxide core-absorbable silicon dioxide shell prepared as in Example 1, 1% by weight of a water-soluble acrylic emulsion resin as a dispersant, and 60% by weight of 1-Methoxy-2-propanol as the remaining solvent And 70 parts by weight of a photocatalyst solution consisting of 34% by weight of 3-methoxy-3methyl butanol, 10 parts by weight of tetraethyl orthosilicate as a curable binder and 10 parts by weight of a curable binder solution consisting of 90% by weight of 2-Propanol as the remaining solvent and a leveling agent. BYK-346 (BYK Co., Ltd.) 5% by weight of the leveling agent solution consisting of 95% by weight of 2-Propanol as the remaining solvent was mixed to prepare a coating solution.

The coating solution thus prepared was coated on one surface of the PET base film using a microcomma coating apparatus so as to be 2 micrometers at 200 nanometers based on the dry coating thickness. After coating, drying is performed to increase the permeability and to form an anti-stain coating layer. Drying after coating layer formation was performed at 150 ° C. for 30 minutes. The transmittance increase and the transmittance of the anti-staining film thus prepared were measured. Figure 2 is a graph of transmittance according to the thickness change of the optical film prepared in this embodiment. As shown in FIG. 2, the transmittance varies depending on the thickness, and when the thin film design is designed to exhibit the lowest reflectance at a wavelength near 550 nm, which is a region of visible light sensitive to the human optic nerve, the highest transmittance is obtained at a coating thickness of 800 nm.

In addition, the contact angle was measured by dropping oleic acid on the film surface in order to confirm the anti-staining effect. 3 is a comparison of the oleic acid contact angle between the optical film and the general hard coating film after measurement, it can be seen that the contact angle of oleic acid in the optical film is very low compared to the normal hard coating. This maintains a low contact angle with the film surface, minimizing the change in the reflection angle and refractive index of the light caused by the oil, making the stain less visible. In order to confirm the decomposition effect of adsorption contaminants by photochemical reaction of titanium dioxide core, methylene blue decomposition was performed among the photocatalyst performance evaluation methods. Methylene blue at a concentration of 10 mg / L is dropped on the surface of a general hard coating film and an optical film and then covered with a coating film to prevent drying. Thereafter, ultraviolet rays of 1.0 mW / cm ² intensity were irradiated to measure color differences every 10 minutes. Figure 4 is a graph measuring the color difference change while irradiating ultraviolet rays for 1 hour. In the case of the general hard coating film, no color change of methylene blue was observed, but in the case of the optical film, the color difference ΔE * value decreases, indicating that methylene blue was decomposed by the photolysis reaction of titanium dioxide.

Embodiments of the invention described above should not be construed as limiting the technical specifications of the invention. The scope of protection of the present invention is limited only by the matters described in the claims, and those skilled in the art will be able to modify the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the scope of the present invention as long as they are obvious to those skilled in the art.

10: base film 20: increased transmittance and stain resistant coating layer
30: adhesive layer 40, 40 ': protective film
100: optical film

Claims

A base film;
It is formed on one side of the base film, the average particle diameter ranges from 5 to 100nm and based on the weight of titanium dioxide on the metal-doped crystalline titanium dioxide surface doped with titanium dioxide or a metal component in the titanium dioxide To 100 parts by weight of a solution comprising from 5 to 30% by weight of a filler in the form of a titanium dioxide core-oil-absorbing silicon dioxide shell and 0.2 to 1% by weight of a dispersant and 69 to 94.8% by weight of a dispersion medium having a porous silicon dioxide layer in the% range. An optical film comprising an increase in transmittance and an anti-staining coating layer formed by applying a coating solution including 5 to 20 parts by weight of a curable binder solution and 10 to 40 parts by weight of a leveling agent solution, followed by drying.

The method of claim 1,
The optical film, characterized in that the transmittance increase and the thickness of the anti-stain coating layer is 500nm to 1μm thickness in dry thickness.

The method of claim 1,
An optical film, characterized in that it further comprises an adhesive layer on the other side of the base film.

The method of claim 1,
The curable binder may be a C1 to C6 hydrocarbon group having a vinyl group or a methacryloxy group, a mercapto group, an amino group or an epoxy group, R2 is a C1 to C4 hydrocarbon group, and R3 is a C1 to C8 hydrocarbon group or acyl group. and a and b are alkoxysilanes represented by the formula R1aR2bSi (OR3) 4-ab, each of which is 0 or 1, or a hydrolyzate or partial hydrolyzate thereof.

5. The method of claim 4,
The curable binder is at least one selected from the group consisting of tetraethyl orthosilicate, methyltriethoxysilane, methyltrimethoxysilane, diethoxydimethylsilane and diethoxydiethylsilane.

A base film;
It is formed on one side of the base film, the average particle diameter ranges from 5 to 100nm and based on the weight of titanium dioxide on the metal-doped crystalline titanium dioxide surface doped with titanium dioxide or a metal component in the titanium dioxide To 100 parts by weight of a solution comprising from 5 to 30% by weight of a filler in the form of a titanium dioxide core-oil-absorbing silicon dioxide shell and 0.2 to 1% by weight of a dispersant and 69 to 94.8% by weight of a dispersion medium having a porous silicon dioxide layer in the% range. A n-permeability increase and anti-staining coating layer formed by applying a coating solution including 5 to 20 parts by weight of a curable binder solution and 10 to 40 parts by weight of a leveling agent solution, followed by drying; Increased transmittance in which n-adhesive layers were alternately laminated two or more times and multiple layers of the stain leaving coating layer-adhesive layer (where n is 10 or less) A natural number), and;
Including the n + 1 adhesive layer on the other side of the base film,
The transmittance increase and the adhesion strength of the m-th adhesive layer of the multiple layer of the stain-resistant coating layer-adhesive layer is weaker than the adhesive strength of the m-1 adhesive layer (the m is 2 to n).