KR100804851B1 - Double-faced pressure sensitive adhesive tape for shielding from light - Google Patents

Abstract

[assignment]

Provided is a light shielding double-sided adhesive tape having sufficient light shielding properties even without providing a metal deposition layer.

[Resolution]

A light-shielding double-sided adhesive tape for forming a pressure-sensitive adhesive layer on both sides of a laminate having a colored layer on at least one surface of a colored substrate.

Description

Double-faced pressure sensitive adhesive tape for shielding from light}

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structural example of the light-shielding double-sided adhesive tape of this invention.

<Description of the symbols for the main parts of the drawings>

1: Coloring Base

2: colored layer

3, 4: adhesive layer

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a double-sided adhesive tape, and in particular, a light-shielding double-sided adhesive tape suitable for preventing leakage of light from a backlight used in a liquid crystal display such as a mobile phone, a liquid crystal panel formed by adhering the adhesive tape, and a corresponding article. The present invention relates to a portable electronic device using an adhesive tape.

BACKGROUND With the miniaturization and energy saving of electronic devices such as mobile phones and PDAs (Personal Data Assistants), image display by liquid crystal panels is rapidly expanding. These liquid crystal displays have also been centered on the backlight type which irradiates light from the back of the liquid crystal panel in order to secure the brightness of the screen. In this case, a double-sided adhesive tape is used to fix the end of the liquid crystal panel or to prevent dust from invading. In order to prevent leakage of light from the end, a metal such as aluminum is deposited as the adhesive tape. The thing based on a plastic film is used (patent document 1). However, the deposition not only increases the manufacturing cost, but also because pinholes are easily generated in the deposited metal thin film, it is inevitable to deposit two or more layers, and the protective layer must be installed because the deposition layer is easily damaged. There was a flaw that it became.

[Patent Document 1]

Japanese Patent Publication No. 2002-23663

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said fault, when the colored layer is provided in the at least one surface of a colored base material, it can not only provide sufficient light-shielding property, but also provide a backlight, without providing a metal vapor deposition layer. The reflectance was also increased, and it was found that it was also possible to use light more efficiently, and the present invention was reached.

Therefore, the 1st objective of this invention is providing the light-shielding double-sided adhesive tape which has sufficient light-shielding property, even if a metal vapor deposition layer is not provided.

A second object of the present invention is to provide a light-shielding double-sided adhesive tape which is cheaper than conventionally, in which the laminated structure is simplified by making the layer functioning as a simple protective layer unnecessary.                         

It is a third object of the present invention to provide a liquid crystal panel in which backlight light is hard to leak.

Moreover, the 4th object of this invention is to provide the portable electronic device which a liquid crystal display screen is easy to see.

The above-mentioned various objectives of this invention provide the light-shielding double-sided adhesive tape for which the adhesive layer is provided on both surfaces of the laminated body which has a colored layer on at least one surface of a coloring base material, this tape It was achieved by a liquid crystal panel made by adhering to and a portable electronic device made using the tape.

It is preferable that the transmittance | permeability with respect to visible light of the whole light-shielding adhesive tape for light shielding is 0.01% or less, and from this viewpoint, it is preferable that the said colored base material and a colored layer are simultaneously black.

In addition, it is preferable that the light reflectance with respect to the light of 350-550 nm in either the said colored base material or the colored layer is 70% or more, From this viewpoint, it is preferable that the said colored base material is white and a colored layer is black. desirable.

(Example)

Although the coloring base material used by this invention can be suitably selected from a well-known thing, it is preferable to use a coloring plastic film from a viewpoint of intensity | strength. The plastic film used in this case is not particularly limited, but polyethylene terephthalate film (hereinafter abbreviated as PET film), stretched polypropylene film, acrylonitrile butadiene from the viewpoint of strength, cost, availability, or adhesion ease. -Styrene copolymer film, polystyrene, etc. are preferable, and PET film is especially preferable.

As a method of using a plastic film as a coloring substrate, a method of incorporating a colorant (dye or pigment) into a plastic before film molding, a method of coloring a layer by printing or painting on the surface of the plastic film, another colored plastic film, etc. on the plastic surface In the case of adhering or manufacturing the base film, other colored plastic films may be co-extruded and laminated, or a combination thereof, but from the viewpoint of ease of production and cost, in particular, a colorant (dye or pigment) is introduced into the plastic. The method is preferred. In this case, the coloring agent (dye or pigment) to be used may be appropriately selected from known ones, but it is preferable to use a pigment from the viewpoint of sufficient coloring.

Although there is no limitation in particular in the color of coloring, black is preferable from a light-shielding viewpoint, and white is preferable from a viewpoint of reflecting the light of a backlight. In addition, by imparting antistatic performance to the colored substrate, it is possible to prevent black mixing.

Although the thickness of a coloring base material can be designed suitably according to the material to be used, it is usually 15-100 micrometers, It is preferable that it is 20-50 micrometers especially from a viewpoint of the ease of handling of a product when it uses a tape.

The colored layer provided on at least one surface of the colored base material manufactured as mentioned above can be provided according to methods, such as printing, coating, adhesion of a colored film, or application of a colored adhesive. Although the color of this colored layer is not specifically limited, White is preferable from a viewpoint of reflecting the color of a backlight, and black is preferable from a light-shielding viewpoint. Moreover, in order to improve light-shielding property, it is also preferable to print or coat twice or more on one side of a coloring base material, or to provide a colored layer by printing or painting on both surfaces of a coloring base material. Moreover, the thickness of a colored layer is 0.5 micrometer-10 micrometers, Preferably it is 1.5-7 micrometers. If the colored layer is less than 0.5 mu m, sufficient light shielding properties cannot be obtained even if the coloring degree of the colored substrate is considerably high, and the strength of the colored layer is insufficient because the amount of the colorant to be used must be increased to secure sufficient light shielding properties. . Therefore, when making a colored layer thin, it is preferable to cover the said fault by providing a colored layer on both surfaces of a coloring base material suitably. Moreover, even if it exceeds 10 micrometers, it cannot be said that the shading performance further improves, and it is uneconomical.

Although the adhesive used by this invention can be suitably selected from the well-known adhesive used for the use of the tape of this invention, and the same kind of use, It is preferable to use an acrylic adhesive especially from a viewpoint of adhesive performance and versatility. In addition, you may make a colored adhesive layer add a coloring agent to this adhesive layer. In particular, by using the black adhesive layer, there is no fear that light leakage from the end of the pressure-sensitive adhesive layer occurs, which is preferable. In addition, you may add additives, such as an antistatic agent, to this adhesive layer in the range which does not impair adhesive performance.

Although the thickness of the adhesive layer provided on both surfaces of the laminated body of a coloring base material and a coloring layer may be 2-15 micrometers normally, it is preferable that it is about 5-12 micrometers especially. If it is less than 2 micrometers, adhesiveness may become inadequate, and when it exceeds 15 micrometers, since an adhesive may stick out at the time of use, it is unpreferable. On the surface of the pressure-sensitive adhesive layer, a well-known release sheet may be provided as appropriate. Thereby, the handleability of the double-sided adhesive tape of this invention before use can be made favorable. In addition, by using an antistatic release sheet, mixing of foreign matter can be prevented.

In the case where the double-sided tape of the present invention is used for a backlight type liquid crystal panel, it is preferable that the light transmittance with respect to visible light having a wavelength range of 400 to 700 nm, which is substantially free of light, is 0.01% or less. In particular, in the case where importance is placed on light shielding, it is preferable to make the colored substrate and the colored layer black. As a coloring agent, it is preferable to use black things, such as carbon black, for example.

From the viewpoint of making effective use of the light by reflecting the light of the backlight, it is preferable that the light reflectance when measured in the wavelength region of 350 to 550 nm of the colored layer or colored substrate surface on which the backlight first touches is 70% or more. . By doing in this way, backlight light at the time of using the adhesive tape of this invention for a backlight type liquid crystal panel can be used efficiently. From the viewpoint of increasing the reflectance, the colorant is preferably not black, and for example, a white colorant such as titanium oxide is preferably used.

From both viewpoints of light shielding and reflection of backlight light, it is preferable that a colored base material is white and a colored layer is black. Such a light shielding double-sided tape is used so that a white colored substrate is placed on the back side and a black colored layer is placed on the liquid crystal panel side.

The light-shielding double-sided adhesive tape of the present invention is used to fix the liquid crystal panel and the backlight module. Usually, it is used in the state which cut-out in frame shape according to the dimension of a liquid crystal panel or a backlight.

Hereinafter, although an Example further demonstrates this invention, this invention is not limited by it.

The light transmittance and the light reflectance were measured as follows using "UV-3101 PC" manufactured by Shimadzu Corporation.

Light transmittance: The average value of the transmittance | permeability when the visible light of wavelength range 400-700nm was irradiated to the light-shielding double-stick adhesive tape was made into the light transmittance.

Light reflectance: The average value of the reflectance at the time of irradiating visible light in the wavelength range of 350-550 nm from the colored base side of the light-shielding double-stick adhesive tape was made into the light reflectance.

Example 1

As a substrate, a gravure printing machine was used with a black ink for gravure printing ("LB claw" manufactured by Toyo Ink Seil Research Co., Ltd.) on one side of a white polyethylene terephthalate film having a thickness of 38 µm (80% or more of `` Lumir E20 '' manufactured by Toray Industries, Inc.). Was applied twice, and dried to form a colored layer having a thickness of 2 μm. Acrylic adhesive ("PA-T1" manufactured by Lintec Co.) was applied to the substrate side and the colored layer side so as to have a thickness of 10 µm after drying, respectively, and dried at 80 ° C. for 2 minutes to obtain a light-shielding double-sided adhesive tape. The light transmittance double-sided adhesive tape had a light transmittance of 0.001% and a reflectance of 80%.

When the obtained adhesive tape was used for fixing the liquid crystal panel and the backlight module of the cellular phone, the screen was bright and easy to see, and no leakage of the light of the backlight was observed at the end of the liquid crystal panel, which was extremely good.                     

Example 2

Repeated application and drying of black gravure printing ink ("LB Chloe" made by Toyo Ink Co., Ltd.) by gravure printing on one side of black polyethylene terephthalate film ("Lumier X30" made by Toray Corporation) of thickness 38micrometer as a base material And the colored layer of 2 micrometers in thickness was provided. Subsequently, an adhesive layer was provided as in Example 1 to obtain a double-sided adhesive tape for light shielding. The light transmittance of this light shielding double-sided adhesive tape was 0.001%.

When the obtained adhesive tape was used for fixing the liquid crystal panel and the backlight module of the cellular phone, the screen was bright and easy to see, and no leakage of the light of the backlight was observed, which was extremely good.

Example 3

A light-shielding double-sided adhesive tape for light shielding was obtained in the same manner as in Example 2 except that 10 parts by weight of carbon black was added to 100 parts by weight of the solid content of the acrylic pressure-sensitive adhesive used in Example 2. The light transmittance of this light-shielding double-sided adhesive tape was 0.001%.

When the obtained adhesive tape was used for fixing the liquid crystal panel of the cellular phone and the backlight module, the screen was bright and the leakage of light of the backlight was not observed, and it was extremely good.

Since the light-shielding double-sided adhesive tape of the present invention does not have a process for depositing a metal, there is no pinhole, and the light-shielding performance is sufficient, so it is not only inexpensive but also suitable as a tape for fixing the end of the backlight type liquid crystal panel. Moreover, the portable electronic device using the light-shielding double-sided adhesive tape of this invention is easy to see a liquid crystal display, and is inexpensive.

Claims (9)

A pressure-sensitive adhesive layer is formed on both surfaces of a laminate having a colored layer on at least one surface of a colored base material, and has a light transmittance of 0.01% or less in a wavelength region of 400 to 700 nm, wherein the colored layer is at least A double-sided adhesive tape for shading comprising two layers. delete The light-shielding double-sided adhesive tape according to claim 1, wherein the light reflectance in the wavelength region of 350 to 550 nm of the surface of either the colored substrate or the colored layer is 70% or more. The light-shielding double-sided adhesive tape according to claim 1, wherein the colored base material and the colored layer are all black. The light-shielding double-sided adhesive tape according to claim 1, wherein the colored base material is white and the colored layer is black. The light-shielding double-sided adhesive tape according to claim 4 or 5, wherein the pressure-sensitive adhesive layer provided on the black colored layer is a black adhesive layer. delete A light-shielding double-sided adhesive tape according to any one of claims 1 and 3 to 5 is attached to the liquid crystal panel. A portable electronic device comprising the light-shielding double-sided adhesive tape according to any one of claims 1 and 3 to 5.

Images