1282016 发明, 发明 发明 发明: The present invention relates to an optical film comprising a substrate characterized in that at least one substrate surface has a coating containing inorganic particles. The optical film of the present invention can be used for a backlight reflector of a liquid crystal display to achieve an effect of enhancing the brightness of the liquid crystal display. [Prior Art] The imaging of a liquid crystal display (LCD) firstly uses a back light source to project a light source, which first passes through a polarizing plate and then passes through liquid crystal molecules. The way is to change the angle of the light that penetrates the liquid crystal, and then the light passes through the front color filter (c〇1〇rfilter) and the other polarizer. Therefore, as long as the voltage value of the stimulating liquid crystal molecules is changed, the intensity and color of the last appearing light can be controlled, and then the color combinations of different shades can be changed. The brightness of the LCD depends on the transmittance of the liquid crystal cell and the color filter. Another important factor is the brightness of the backlight. Therefore, if you want to bring back the brightness of the LCD surface, you should start by increasing the brightness of the backlight. The use of a monthly light source as an important component of the LCD display function and a source of brightness is very important for improving the brightness of the liquid crystal display. Prior to the present invention, the industry has tried various ways to improve the brightness of the LCD display from the backlight, and adjust the source of the lamp to increase the brightness of the display by increasing the number of lamps and/or increasing the lamp's original force rate. Faced with large size and power consumption, etc., it can be improved from the light guide plate, but it will face difficulties in the design of the light guide plate material. Applying a reflective film from the backlight can improve the emission efficiency of the light source and increase Brightness of emission. Therefore, an important component of a reflective film-based liquid crystal display, its reflectivity will affect the brightness of the display. In addition, because the light emitted by the backlight contains ultraviolet (UV), it is easy to cause the polymer in the reflective film. The yellowing of the resin causes the reflection effect to be weakened and the chromatic aberration of the LCD. The current solution is to apply a layer of ultraviolet absorber on the reflective film, but if the amount of the ultraviolet absorber is too small, the anti-yellowing effect is limited, and if the amount is increased, The degree of adhesion is reduced. The inventors of the present invention have found through extensive research that coating the surface of the reflective film with a coating containing inorganic particles is not a problem. The adhesion of the reflective film absorbs most of the UV light in the backlight, so it has anti-UV function, and can make the reflective film durable and reduce the thickness of the reflective film. Related design and mold, gp can make the brightness of the liquid crystal display can effectively solve the above disadvantages. SUMMARY OF THE INVENTION The main object of the present invention is to provide an optical film comprising a substrate characterized by at least a base The surface of the material has a coating of I inorganic particles. The other object is to provide a method for enhancing the brightness of a liquid crystal display. [Embodiment] The present invention provides an optical film '纟-substrate, which is characterized by one less The surface of the substrate has a coating layer containing inorganic particles. The type of the inorganic film used in the optical film of the present invention is not particularly limited to 1282016, as long as the inorganic particles have the property of absorbing ultraviolet rays. The type of inorganic particles, for example, but not limited to, zinc oxide cerium oxide, titanium dioxide, aluminum oxide, calcium sulfate, barium sulfate, calcium carbonate or a mixture thereof. The particle size is generally from 丨 to (7)^nanometer, preferably from 20 to 50 nm. The substrate used in the optical film of the present invention is well known to those skilled in the art. The substrate comprises at least one layer of a polymer resin. The polymer resin is not particularly limited, and is, for example but not limited to, a polyolefin resin such as polyethylene (PE) or polypropylene (polyvinyl acetate resin ( Polyester resin ), such as polyethylene terephthalate (PET); polyacrylate (p〇lyacryiateresin) resin, such as polymethyl methacrylate (PMMA); polycarbonate resin (p〇lycarb〇nate resin) , a poly-p-perurethane resin, or a mixture thereof. According to a preferred embodiment of the present invention, the optical film of the present invention is a polyester resin substrate, preferably polyethylene terephthalate. The substrate may optionally contain inorganic particles known to those skilled in the art, such as zinc oxide, cerium oxide, titanium dioxide, aluminum oxide, calcium sulfate, barium sulfate, calcium carbonate or mixtures thereof. According to one of the preferred embodiments of the present invention, the substrate of the present invention may be a multilayer substrate in which one or more layers contain the inorganic particles. Specifically, the present invention can be, for example, a three-layer substrate in which the inorganic particles are contained in the intermediate layer. The coating on the surface of the substrate of the present invention may optionally contain additives known to those skilled in the art, such as fluorescent whitening agents or ultraviolet light absorbers or mixtures thereof. 1282016 UV absorbers useful in the surface coating of optical films of the present invention are well known to those skilled in the art and are, for example, benzotriazoles, benzotdazines, and ketones. Benzophenones or saicylic acid derivatives. The type of the fluorescent whitening agent which can be used for the surface coating of the optical film of the present invention is not particularly limited and is known to those skilled in the art. These include, but are not limited to, benzazole xaz〇les, benzimidazoles or diphenylethylene bistriazines. The optical film of the present invention can be used as a reflective film. Therefore, the present invention further provides a method for enhancing the brightness of a liquid crystal display, which comprises using the above optical film as a reflective film of a backlight in a liquid crystal display to enhance the brightness of the liquid crystal display. efficacy. The following examples are intended to further illustrate the invention, but are not intended to limit the scope of the invention. Modifications and modifications readily achievable by anyone familiar with the technology are included in the disclosure of this specification and the scope of the attached patent application. Example 1 126.6 g of methacrylic resin (about 6 % by weight of solid content) was added to methyl ethyl ketone / toluene (45 g each), stirred (rotation speed 1 rpm), and then 75 nm lead oxide was sequentially added. 3 g of titanium dioxide/barium sulfate and 18. 4 g of a hardener (desmodur 3390, available from Bayer) to form 25 g of paint (solids 4 〇〇 / 〇). The coating was coated with κυχ-15〇 (purchased from Ding (7)) substrate 1282016, and after drying, a coating film of 1 〇pm was obtained, and after standing for 7 days, a weathering test was carried out (Q-panel, Q-panel) Company) to measure the change in the yellowing index value (Yellowing Index, 'ΥΓ) of the coating film at different exposure times. The results obtained are shown in Table 1 below. Example 2 The procedure of Example 1 was repeated except that the substrate was changed to E60L (purchased from Toray). The weathering test results of the obtained coating film are shown in Table 1 below. Comparative Example 1 The procedure of Example 1 was repeated except that 3 g of 75 nm lead oxide/titanium dioxide/sulfur was replaced by 3 g of an organic UV absorber (Tinuvin P, available from Ciba). The weathering test results of the obtained coating films are shown in Table 1 below. Table 1 Film thickness exposure 100 hr ΔΥΙ Exposure 200 hr ΔΥΙ Exposure 300 hr ΔΥΙ Exposure 500 hr ΔΥΙ Example 1 10 μηι 0.60 0.65 0.90 1.18 Example 2 10 μχη 0.61 ~~067~ 0.92 1.20 Comparative Example 1 10 μιη 3.74 6.05 7.95 9.34 • According to one data, an optical film made by adding inorganic particles to different substrates has the same anti-yellowing effect. 2. It is known from the data shown in Table 1 that the optical film to which the inorganic particles are added has a better anti-yellowing effect than the optical film generally containing a UV absorber. Thus, the optical film of the present invention can provide a wider range of applications.