KR19980068299A - Manufacturing Method of Optical Acid Film for TFT-LCD - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light diffusing film used for manufacturing a backlight unit of a thin film transistor liquid crystal display (TFT-LCD) such as a notebook computer, a wall-mounted television, etc., and its main purpose is to obtain a clear image of a display than conventional ones. All.

Specifically, the present invention is a transparent or single or mixed resin selected from acrylic, urethane, epoxy, vinyl, polyester, and polyamide resins on one or both surfaces of a high transparency plastic film having a light transmittance of 85-95%. The present invention relates to a method for manufacturing a light diffusing film, which is prepared by coating a coating liquid composed of a white pigment and other additives, and the light diffusing film prepared by using the manufacturing method is used for TFT-LCD. It exhibits a useful ability to spread light uniformly while losslessly passing through the light transmitted through the prism film.

Description

Manufacturing Method of Light Diffusion Film for TFT-LCD

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing film used for manufacturing a backlight unit of a TFT-LCD, and more particularly, to a light diffusing film used for a thin film transistor liquid crystal display (TFT-LCD). The present invention relates to a method of manufacturing a light diffusing film, in which uniform light diffusion is induced while passing light irradiated from a light source lamp located at a side or a rear side to obtain a clear image, thereby obtaining a clear light image.

High light transmittance and high haze are the most important characteristics of a light diffusing film having a function of uniformly spreading the light irradiated from the light source lamp and passing through the prism film without loss.

In the conventional display method, the light guide plate has a role of light diffusion and has an advantageous aspect in terms of cost. However, in a thin film transistor liquid crystal display (TFT-LCD) which requires a clearer image, a light diffusion plate is applied to a conventional light guide plate. 4-270,302 and U.S. Patent No. 5, 289,351 have limitations, so the method of using a separate light diffusing film or light diffusing plate on the light guide plate is a backlight unit of TFT-LCD such as various notebook computers, personal computers, and wall-mounted televisions. It is being used for (back light unit).

The present invention is to provide a light diffusing film having a high total light transmittance and light diffusivity suitable for use for TFT-LCD, using a method of applying a coating liquid having a specific composition to a highly transparent plastic film .

The present invention relates to acrylic, urethane, and epoxy resins, such as polymethyl methacrylate or methacrylic acid ester copolymer, on one or both surfaces of a highly transparent plastic film having a light transmittance of 85 to 95% (more preferably, 90 to 94%). The present invention relates to a method for producing a light-diffusion film, comprising coating a coating liquid composed of a resin, a pigment, and an additive, alone or in a mixture of two or more thereof, among resins such as vinyl, polyester, polyamide and the like.

In the present invention, as the base material of the light diffusion film, a high transparency plastic film such as polyester film, polycarbonate film, polymethyl methacrylate film, polystyrene film can be used, and in particular, when the polyester film is used, the coating resin is polyester. Polyester type and urethane type which are resin which is excellent in adhesive force with a film are more preferable.

The pigment may be a transparent or white pigment, and as the transparent pigment, organic pigments such as acrylic resins, styrene resins, silicone resins and starches, and inorganic pigments such as synthetic silica, grass beads, and diamond may be used. As a white pigment, titanium oxide, zinc oxide, barium sulfate, calcium carbonate, magnesium carbonate, aluminum hydroxide, clay, etc. can be used, These pigments can be used individually or in mixture of 2 or more types.

In addition, it is important to control the ratio of the coating resin and the pigment in order to manufacture the light diffusing film used in the liquid crystal display having the desired optical properties, especially in order to produce a light diffusing film with a total light transmittance of 85% to 94%. It is preferable to use the ratio of the pigment with respect to resin in 30 to 50weight% of a range. If the weight ratio is less than 30% haze (HAZE) is low it is difficult to obtain excellent light diffusivity, if the weight ratio exceeds 50% total light transmittance is lowered to obtain a light diffusion film having a high light transmittance. In addition, in order to control the light transmittance, the thickness of the coating layer must be adjusted. In order to obtain a light transmittance of 85% to 94%, the thickness of the coating layer is between 3 and 30 mm (more preferably, 10 to 20 mm). good. When the thickness of the coating layer is less than 3mm, the adhesive strength with the polyester film is lowered. If the thickness of the coating layer exceeds 30mm, the total light transmittance is 85% or less, and the coating layer may be cracked, thereby preventing the desired light diffusion film from being produced.

A coupling agent may be used as an additive in the production of the light diffusing film to increase the adhesion between the base film and the pigment, and a composition value between 2 and 10% (more preferably, 4 to 8%) based on the weight of the coating resin. It is desirable to have. It is not effective when used less than 2% or over 10%. In this invention, a silane coupling agent is mainly used as a coupling agent.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Example 1

A coating liquid having the following composition was applied to one surface of the highly transparent polyester film (XG-500,100㎛), and then dried at 100 ° C. for 30 seconds, and the thickness of the coating layer was 20 A light diffusing film having a diameter was prepared and shown in Table 1 by measuring physical properties.

Composition of Coating Liquid

-Polyester resin (TOYOBO: VYLON 200): 25.0g

-Synthetic acrylic beads (SOKEN CHEMICAL: MX-150): 8.0g

-Silane Coupling Agent (OSI SPECIALTIES: A-189): 1.0g

Methyl ethyl ketone: 66.0 g

Example 2

The coating solution having the following composition was used in the same manner as in Example 1, and the physical properties thereof were shown in Table 1 below.

Composition of Coating Liquid

-Urethane-Polyester Resin (TOYOBO: UR-1400): 22.0g

-Synthetic acrylic beads (SOKEN CHEMICAL: MX-150): 4.0g

Synthetic silica pigment (FUJI-SILYSIA: SILYSIA 250): 4.0g

-Silane Coupling Agent (OSI SPECIALTIES: A-189): 1.0g

Methyl ethyl ketone: 72 g

Comparative Example 1

The coating solution having the following composition was used in the same manner as in Example 1, and the physical properties thereof were shown in Table 1 below.

Composition of Coating Liquid

-Urethane-Polyester Resin (TOYOBO: UR-1400): 24.0g

-Synthetic silica pigment (FUJI-SILYSIA: SILYSIA 250): 4.0g

-Silane Coupling Agent (OSI SPECIALTIES: A-189): 1.0g

Methyl ethyl ketone: 69.0 g

Comparative Example 2

The coating solution having the following composition was used in the same manner as in Example 1, and the physical properties thereof were shown in Table 1 below.

Composition of Coating Liquid

-Urethane-Polyester Resin (TOYOBO: UR-1400): 24.0g

-Synthetic silica pigment (FUJI-SILYSIA: SILYSIA 250): 4.0g

-Synthetic titanium oxide (Korea Titanium Co., Ltd .: KA-100): 2.0g

-Silane Coupling Agent (OSI SPECIALTIES: A-189): 1.0g

-Methyl ethyl ketone: 68 g

TABLE 1

Total light transmittance (%) HAZE Example 1 92.5 75.8 Example 2 88.6 91.1 Example 3 75.6 52.1 Example 4 62.3 57.3

The total light transmittance and haze were measured according to ASTM D1003, and are defined as follows.

As can be seen from the above examples and comparative examples, the light diffusing film for TFT-LCD manufactured according to the present invention has high total light transmittance and haze, and thus uniformly passes through the light transmitted from the light source lamp and passes through the prism film without loss. It has an excellent function of spreading.

Claims (4)

40 to 68% by weight of a single resin or two or more mixed resins selected from acrylic, urethane, epoxy, vinyl, polyester, and polyamide resins on one side or face of a highly transparent plastic film having a light transmittance of 85 to 95%. And a coating liquid composed of 30 to 50% by weight of transparent or white pigment and 2 to 10% by weight of other additives so that the thickness of the coating layer is 3 to 30 mm. The method of claim 1, wherein the highly transparent plastic film is selected from a polyester film, a polycarbonate film, a polymethyl methacrylate film, and a polystyrene film as a substrate. The method of claim 1, wherein the transparent pigment is selected from acrylic resin, styrene resin, silicone resin, starch, synthetic silica, glass beads, diamond. The method of manufacturing a light diffusing film for TFT-LCD according to claim 1, wherein a silane coupling agent is used as another additive.