KR20160148951A - Adhesive tape for diffusion sheet - Google Patents

Abstract

The present invention provides an adhesive tape for a diffusion sheet, including a black-colored or printed substrate layer and a black-colored adhesive layer formed thereon. According to the present invention, the adhesive tape can prevent a bright line and a hot spot by completely preventing light from leaking in vertical and horizontal directions.

Description

Adhesive tape for diffusion sheet [0002]

The present invention relates to an adhesive tape for a diffusion sheet, and more particularly to an adhesive tape for preventing a bright line and a hot spot.

2. Description of the Related Art Generally, a liquid crystal display device (hereinafter referred to as "LCD device") uses various changes in liquid crystal transmittance according to an applied voltage to change various electrical information generated in various devices into visual information It is an electronic device.

Since the LCD device is a display device of various information and does not have a self-emission source, a separate device for illuminating the entire screen of the LCD device uniformly by placing a light source on the back side is required. In this case, Backlight unit (BLU).

The backlight unit is composed of a reflection plate, a backlight light source, a light guide plate, a light diffusion member (diffusion plate, diffusion sheet), a prism sheet and the like as necessary in order to make light of the light source uniform, As shown,

A reflective sheet 12, a light guide plate 13, a diffusion sheet 14, a prism sheet 15, and a protective sheet 16, as shown in Fig. As the light source 11, an LED light source is used. The light guide plate 3 serves to convert the LED light of the point light source into a surface light source. The reflective sheet 12 reflects the light emitted to the back surface of the light guide plate 13 toward the light guide plate 13 to improve the light efficiency. Light emitted from the light exit surface of the light guide plate 13 is incident on the diffusion sheet 14, and the diffusion sheet 14 diffuses or condenses the incident light to uniform the brightness and widen the viewing angle. On the other hand, the brightness of the light passing through the diffusion sheet 14 drops sharply. To compensate for this, one or two prism sheets 15 are used. The prism sheet 15 refracts the light emitted from the diffusion sheet 14 and concentrates the light incident at a low angle toward the front side, thereby raising the luminance in the effective viewing angle range. The protective sheet 16 functions to prevent scratches on the prism sheet 15 and re-magnify the viewing angle reduced by the prism sheet 15 within a predetermined range.

Currently, mobile devices are getting wider and brighter. As the amount of light increases compared with the previous product, light is leaked in a horizontal direction to an adhesive tape (tape for laminating tape) attached to a diffusion sheet to generate a bright line and a hot spot

Patent Publication 10-2009-0113200

Accordingly, an object of the present invention is to provide an adhesive tape for preventing a bright line and a hot spot.

The object of the present invention is achieved by an adhesive tape comprising a base layer colored or printed in black and a black colored adhesive layer formed thereon.

According to the present invention, it is possible to completely prevent light leaking in the vertical direction as well as in the horizontal direction, thereby preventing a bright line and a hot spot.

1 is a schematic drawing showing a structure of a backlight unit
2 is a view showing a structure of a pressure-sensitive adhesive sheet adhered to a conventional upper end portion (light-incoming portion) of a diffusion sheet
3 is a view showing the structure of a pressure-sensitive adhesive sheet adhered to the upper end (light-incoming portion) of the diffusion sheet of the present invention
4 is a photograph of a diffusion sheet to which a pressure-sensitive adhesive sheet of the present invention is applied
5 is a photograph showing changes in appearance of the light-diffusing sheet light-receiving portion with the adhesive tape of Examples and Comparative Examples of the present invention

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

2 shows a structure of a conventional adhesive sheet. Such a pressure-sensitive adhesive sheet is a sheet which is adhered to the top of the diffusion sheet (light-incoming portion) for banding, as shown in Fig. The base layer of the bottom layer is formed of a transparent base film 211 as shown in FIG. 2A, and the black ink 212 is printed on the upper layer. Alternatively, as shown in FIG. 2B, A resin (211 ') containing a colorant and colored with a black color of the substrate itself is used.

There is no particular limitation on the resin material constituting the substrate layer, but a polyethylene terephthalate film (hereinafter abbreviated as PET film), a stretched polypropylene film, an acrylonitrile butadiene- Styrene copolymer film, polystyrene and the like are preferable, and a PET film is particularly preferable.

The transmittance of the black printed or colored substrate layer should not be more than 0.01%. The black base film layer blocks vertical light generated from the light source.

Light was leaked to the pressure-sensitive adhesive layer 213 formed on the upper portion of the conventional base layer using a transparent pressure-sensitive adhesive, and bright lines and hot spots emerged from the prism.

In the present invention, the base layer of the bottom layer is formed of a transparent base film 311 as shown in FIG. 3A, black ink 312 is printed on the upper layer thereof, or black ink 312 is printed on a pigment Or a coloring material such as a dye is used so that the substrate 311 'colored with a black color is used.

There is no particular limitation on the resin material constituting the substrate layer, but a polyethylene terephthalate film (hereinafter abbreviated as PET film), a stretched polypropylene film, an acrylonitrile butadiene- Styrene copolymer film, polystyrene and the like are preferable, and a PET film is particularly preferable.

The transmittance of the black printed or colored substrate layer should not be more than 0.01%. This black base material film layer blocks vertical light generated from the light source.

In the present invention, as shown in FIG. 3, a black coloring agent layer can be formed by using a black pigment or a dye in the pressure-sensitive adhesive layer 313 to block the light spots. Therefore, the light emitted from the inclined plane of the LCD wedge can be blocked to reduce the bright lines and hot spots emitted from the prism.

The pressure sensitive adhesive to be used in the present invention is preferably an acrylic pressure sensitive adhesive in view of adhesion performance and versatility.

Particularly, a black coloring agent is added to the pressure-sensitive adhesive layer to prevent light from leaking from the end of the pressure-sensitive adhesive layer. The black pressure-sensitive adhesive layer blocks the light escaping horizontally.

In this case, 3 to 15 parts by weight of the black colorant is suitable for 100 parts by weight of the solid content of the acrylic pressure-sensitive adhesive. The transmittance of the black adhesive itself is 10% or less. In particular, when the black pressure-sensitive adhesive is laminated at 0.6 mm or more, the transmittance is 0.01% or less.

The thickness of the black pressure-sensitive adhesive layer applied to the substrate layer is suitably from 5 탆 to 80 탆. The product thickness (base layer + adhesive layer) is determined according to the height of the LED wedge to compensate the step of the LED wedge, and generally 30 to 250 탆 is used.

A product of Example 1 was prepared by applying 50 탆 of a black acrylic pressure-sensitive adhesive to 100 탆 of a black polyethylene terephthalate film to prepare a product of Comparative Example 1 by applying 50 탆 of a transparent acrylic pressure-sensitive adhesive to 100 탆 of a terephthalate film, To observe the light spots from the light source. The results are shown in photographs in Fig. FIG. 5A shows the result of using the pressure-sensitive adhesive sheet of Comparative Example 1, and FIG. 5B shows the results of using the pressure-sensitive adhesive sheet of Example 1 of the present invention.

As a result of using the black pressure-sensitive adhesive of the present invention, as shown in FIG. 5, it was possible to prevent light spots from the diffusion sheet and to reduce the bright lines and hot spots.

211, 211 ': substrate layer
212: black printed layer
213: transparent pressure-sensitive adhesive layer
214:
311, 311; : Substrate layer
312: black printed layer
313: Black pressure-sensitive adhesive layer
314:

Claims (6)

A pressure-sensitive adhesive tape comprising a substrate layer colored or printed in black and a black-colored pressure-sensitive adhesive layer formed thereon. The adhesive tape according to claim 1, further comprising a release layer formed on the pressure-sensitive adhesive layer. The adhesive tape according to claim 1, wherein the substrate layer is formed of a polyester resin. The pressure-sensitive adhesive tape according to claim 3, wherein the polyester resin is polyethylene terephthalate. The adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer comprises an acrylic pressure-sensitive adhesive. The pressure-sensitive adhesive tape according to claim 5, wherein the pressure-sensitive adhesive layer comprises 3 to 15 parts by weight of a colorant relative to 100 parts by weight of a solid content of the acrylic pressure-sensitive adhesive.

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