JP2000329914A - Adhesive diffusion transflective reflector - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To develop a diffusion semi-transmissive reflector in which even if there is a defect such as a pinhole, unevenness or a scratch on the reflective surface, the defect does not cause a significant decrease in display quality. SOLUTION: The metal thin film in a semi-transmissive specular reflector having a half mirror (2) made of a metal thin film supported by a transparent base material (1) having a smooth surface contains transparent particles to improve light diffusivity. An adhesive diffusion transflective reflector coated with the adhesive layer (3) shown. [Effect] The light diffusion property is achieved by the adhesive layer covering the metal thin film, and the half mirror is used as a mirror surface to suppress the occurrence of defects such as pinholes, unevenness and scratches on the reflection surface. Abnormality of reflection due to the defective portion is less noticeable due to the diffusion effect of the reflected light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive-diffusion semi-transmissive reflection plate which has excellent visual characteristics of reflected light and is useful for a liquid crystal display device of a reflection / transmission type.

[0002]

BACKGROUND OF THE INVENTION As a diffusion-semi-transmission type reflection plate used in a reflection-transmission type liquid crystal display device, a metal vapor-deposited layer in which the rough surface is reflected on a transparent base material whose surface is roughened by a mat treatment or the like. A half mirror provided with a half mirror is being studied. This is a diffusion semi-transmissive reflection plate that incorporates pearl pigment into the transparent resin layer. By controlling the amount of pearl pigment and the layer thickness of the resin layer, it is possible to balance the characteristics such as high reflectivity with good film quality. Is difficult to maintain.

However, in the above-described method using a metal vapor deposition layer, a reflection surface such as pinholes and other irregularities and scratches inevitably generated in a thin metal vapor deposition layer in order to obtain a half mirror reflecting a rough surface. However, there is a problem that the defect is easily conspicuous as reflected in the reflected light and causes a significant reduction in display quality.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop a transflective reflector which does not cause a significant decrease in display quality even if the reflective surface has defects such as pinholes, unevenness and scratches. I do.

[0005]

The present invention relates to a semi-transmissive specular reflector comprising a half mirror made of a metal thin film supported by a transparent substrate having a smooth surface, the metal thin film containing a transparent particle and having a light diffusing property. It is intended to provide an adhesive diffusion semi-transmissive reflection plate characterized by being coated with the adhesive layer shown below.

[0006]

According to the present invention, defects such as pinholes, unevenness and scratches are generated on the reflection surface by forming the half mirror as a mirror surface by achieving light diffusion with the adhesive layer covering the metal thin film. Even if there is a defect such as a pinhole, it is reduced by the diffusion effect of the reflected light by the adhesive layer, so that the reflection abnormality due to the defective portion is not conspicuous and causes a deterioration in display quality of a liquid crystal display device or the like. Can be prevented.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The adhesive diffusion semi-transmissive reflector according to the present invention is a semi-transmissive specular reflector comprising a half mirror made of a metal thin film supported by a transparent substrate having a smooth surface, wherein the metal thin film is formed by transparent particles. And coated with a pressure-sensitive adhesive layer exhibiting light diffusion. Examples thereof are shown in FIGS. 1 is a transparent substrate, 2 is a half mirror made of a metal thin film, 3 is an adhesive layer, and 4 and 5 are a separator and a transparent coloring layer as required.

The transparent substrate can be formed of a suitable transparent substance such as glass or polymer capable of supporting a half mirror made of a metal thin film, and the material for forming the transparent substrate is not particularly limited. By the way, examples of the polymer include polyolefin and various synthetic rubbers, polycarbonate and polystyrene, polyimide and polyamide, cellulose polymer and polyvinyl alcohol, polyacrylate and polymethacrylate, polyurethane and polyurethane acrylate, polyvinyl chloride and polyester. And epoxy resins and epoxy acrylates.

The surface of the transparent substrate on which the metal thin film is provided is preferably as smooth as possible from the viewpoint of stably forming a mirror half mirror in which pinholes and the like are prevented. The thickness of the transparent substrate can be appropriately determined according to the purpose of use, etc., but generally, the thinner it is, the more preferable it is.
It is 0 μm to 1 mm, especially 30 to 500 μm. The transparent substrate may be made of a laminate such as a film made of the same or different materials.

The metal thin film is formed as a half mirror, and is formed by, for example, reflecting light on a transparent base material through a transparent protective layer as necessary by a suitable thin film forming method such as a vacuum evaporation method or a sputtering method. In addition, it can be carried out by providing it with a thickness that allows transmission. In that case, in the present invention, a half mirror composed of a metal thin film that can function as a semi-transmissive mirror reflection layer is achieved by forming the metal thin film as a half mirror on a smooth surface of a transparent base material. .

As the metal, one or more suitable metals can be used, and there is no particular limitation. Generally, a metal having a high reflectivity such as aluminum, silver, gold or chromium, copper or tin, zinc or indium, palladium or platinum, or an alloy thereof is used. Above all, aluminum, silver and the like are preferably used from the viewpoint of the wavelength characteristic of the reflected light.

The half mirror can be formed as a multilayer film composed of one or two or more metal thin films. The thickness of the half mirror is 80% in view of the balance between light reflectance and transmittance.
The thickness is preferably 0 nm or less, particularly preferably 1 to 500 nm, particularly preferably 10 to 200 nm, but is not limited thereto.

The above-mentioned transparent protective layer is provided as necessary for the purpose of preventing the reflectance of the half mirror from lowering due to oxidation of the metal thin film and the like, and can be provided on one side or both sides of the metal thin film. When the metal thin film 2 is formed of a silver vapor deposition layer as illustrated in FIG. 2, it is preferable to provide transparent protective layers 21 and 22 on the front and back surfaces. In forming the transparent protective layer, an appropriate light-transmitting material according to the related art, for example, the transparent polymer exemplified as the above-mentioned transparent substrate can be used.

The semi-transmissive specular reflector to be formed has a transmittance of 5% for all rays in order to achieve good visibility in the transmission mode and the reflection mode in which the transmittance and the reflectance are balanced.
It is preferable to adjust the reflectivity to 30% and the reflectivity to 90% to 50%. The metal thin film and the transparent protective layer may be provided with an appropriate antireflection layer made of, for example, a low-refractive-index transparent film or a multilayer thin film using, for example, magnesium fluoride or a fluorine-based resin.

As shown in the drawing, the metal thin film 2 forming the half mirror is covered with an adhesive layer 3, and the adhesive layer in the present invention is intended to adhere to another member such as a liquid crystal cell. In addition, for the purpose of diffusing reflected light and transmitted light through a semi-transmissive mirror-like reflecting surface made of the metal thin film 2, the particles are made to show light diffusivity by containing transparent particles.

In the formation of the adhesive layer, an appropriate transparent substance having an adhesive property can be used, and there is no particular limitation. In general, pressure-sensitive adhesives such as rubber-based polymers, acrylic-based polymers, vinyl alkyl ether-based polymers and silicone-based polymers, polyester-based polymers and urethane-based polymers, amide-based polymers and ether-based polymers are used. Above all, an acrylic pressure-sensitive adhesive mainly composed of a poly (meth) acrylic acid alkyl ester which is excellent in transparency, weather resistance, heat resistance and the like is preferably used.

As the transparent particles to be contained in the pressure-sensitive adhesive layer, one or more kinds of appropriate inorganic or organic particles can be used. Incidentally, examples thereof include inorganic particles that may be conductive, such as silica, glass, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide.

Acrylic polymer, polyacrylonitrile, polyester, epoxy resin, melamine resin, urethane resin, polycarbonate, polystyrene, silicone resin, benzoguanamine, melamine
Organic particles composed of a crosslinked or uncrosslinked polymer such as a benzoguanamine condensate or a benzoguanamine-formaldehyde condensate are exemplified.

The particle size of the transparent particles to be used is 100 based on the average particle size in terms of light diffusivity and uniformity of the diffusion.
μm or less is preferred. In particular, in the case of forming a liquid crystal display device, the average particle size is set to 2. because the interference with display light and the wavelength dependency of diffusion are suppressed, and a display free from moiré and roughness due to interference with pixels is obtained. 5 to 40 μm, especially 5 times or more of the central wavelength (550 nm) of the visible region to 1/3 or less of the pixel size of the liquid crystal cell, and especially 3 in consideration of the general pixel size of color liquid crystal (100 μm × 300 μm). ~ 30
It is preferable to use μm transparent particles. The transparent particles generally have an arbitrary (true) spherical shape or a secondary aggregate thereof.

The pressure-sensitive adhesive layer containing transparent particles exhibits light diffusivity based on the difference in refractive index between the transparent particles and the polymer or the like forming the pressure-sensitive adhesive layer. From the viewpoint of achieving a bright display, it is preferable that the degree of diffusion be adjusted to 40 to 90% based on haze. Such haze can be advantageously achieved, for example, by using transparent particles having a refractive index ratio of 0.5 to 3, especially 0.7 to 2, especially 0.9 to 1.5 with respect to a polymer or the like forming an adhesive layer. However, the present invention is not limited to this.

The adhesive layer may be provided by a method of directly applying an adhesive mixed with transparent particles to a metal thin film or the like using an appropriate coating machine, or by applying an adhesive layer provided on a separator to the metal thin film according to the method. It can be carried out by an appropriate method such as a method of transferring to or the like. The thickness of the pressure-sensitive adhesive layer can be determined according to the degree of diffusion or the adhesive strength according to the purpose of use and the like.
m. The exposed surface of the adhesive layer is preferably protected by temporarily attaching the separator 4 or the like until it is put to practical use as shown in the figure.

The adhesive diffusion semi-transmissive reflection plate according to the present invention comprises:
The present invention can be used for various applications conforming to a conventional transflective reflector, such as formation of a reflective / transmissive liquid crystal display device. In the present invention, it is preferable that the diffuse reflectance is adjusted to 50 to 95% from the viewpoint of achieving a wide viewing angle and a bright display by suppressing the specular reflection component.

In the above description, the reflected light and the transmitted light through the half mirror made of a metal thin film sometimes have different spectral characteristics. Incidentally, a half mirror made of a silver film has a spectral characteristic in which reflected light is strong in yellow and transmitted light is strong in blue. In such a case, the color balance in display is different between the reflection mode using reflected light and the transmission mode using transmitted light.

In the present invention, as shown in FIG. 2, a transparent colored layer 5 for equalizing the color tone of the transmitted light of the half mirror with the color tone of the reflected light is disposed on the light transmitting side of the semi-transmissive mirror reflector. It is also possible to compensate for the difference in color balance. Such a transparent colored layer has one or two or more layers that correct the difference in the color tone of the transmitted light based on the difference in the spectral characteristics of the reflected light and the transmitted light via the half mirror and equalize the color tone of the reflected light. It can be formed by an appropriate light-transmissive colored layer composed of a colored film or a colored coating film, especially a color filter.

[0025]

EXAMPLE 1 A transparent protective layer was formed on a smooth surface of a polyester film having a thickness of 50 μm, and thereafter a silver vapor deposition layer was provided on the surface, a half mirror having pinholes was provided, and a transparent protective layer was provided thereon. To form a semi-transmissive specular reflector having a transmittance of all rays of 15% and a reflectance of 70%, and the transparent protective layer having a refractive index of 1.4.
4. A 30% by weight silicone-based particle having an average particle size of 4 μm, coated with an acrylic pressure-sensitive adhesive layer having a haze of 85% and a thickness of 25 μm, to form an adhesive diffusion transflective reflector having a diffuse reflectance of 58%. Obtained.

The above-mentioned adhesive diffusion transflective type reflection plate is adhered and arranged on the back of a commercially available super twist type liquid crystal display device to form a liquid crystal display device for both reflection and transmission, and vertical light is made incident on the liquid crystal display device side. However, the pinholes of the silver deposited film were not visible, and the display quality was excellent in both the reflection and transmission modes, but the color balance was different between the reflection mode and the transmission mode. In addition, the liquid crystal display device is operated at 40 ° C. and 92%
When subjected to a humidification endurance test for 500 hours at RH, no change occurred in the reflection / transmission characteristics.

Example 2 An adhesive diffusion semi-transmissive reflector was prepared in the same manner as in Example 1 except that a yellow film having a transmission B value of 8.6 and a total light transmittance of 40% was laminated on the back of the semi-transmissive specular reflector. Then, a liquid crystal display device was formed using the same. As a result, while exhibiting the same characteristics as in Example 1, the blue color of the transmitted light was canceled and the difference in color balance between the reflection mode and the transmission mode disappeared, and the same color tone was achieved. Was done.

Example 3 An adhesive diffusion semi-transmissive type according to Example 1, except that the adhesive layer was replaced with a layer having a refractive index of 1.54 and a thickness of 125 μm containing 10% by weight of epoxy particles having an average particle diameter of 50 μm. When a reflection plate was obtained and a liquid crystal display device was formed using the reflection plate, the display became difficult to see due to interference with the pixels.

Example 4 The pressure-sensitive adhesive diffusion layer was prepared in the same manner as in Example 1 except that the pressure-sensitive adhesive layer was replaced with a layer having a thickness of 25 μm containing 10% by weight of melamine-based particles having a refractive index of 1.57 and an average particle diameter of 1.2 μm. When a transmissive reflection plate was obtained and a liquid crystal display device was formed using the reflection plate, a display having a strong yellowness due to the wavelength dependence of diffusion was difficult to see.

Example 5 An adhesive diffusion semi-transmissive reflection plate having a diffuse reflectance of 40% was obtained in the same manner as in Example 1 except that the thickness was 10 μm and the haze was 30%, and a liquid crystal display was used. When the device was formed, the display was poor in the degree of diffusion and the surrounding reflection was extremely difficult to see.

Example 6 A semi-transmissive mirror reflector having a total light transmittance of 15% and a reflectance of 70% was formed in the same manner as in Example 1 except that no transparent protective layer was provided on the front and back of the silver deposition layer. Diffuse reflectance is 58%
And a liquid crystal display device was formed using the same and subjected to a humidification durability test at 40 ° C., 92% RH and 500 hours. It became.

Example 7 An acrylic adhesive layer was provided in the same manner as in Example 1 except that a transflective mirror reflector having a transmittance of all rays of 2% and a reflectance of 90% was used, and a diffuse reflectance of 62%. When an adhesive diffusion semi-transmissive reflection plate was obtained and a liquid crystal display device was formed using the same, the transmitted light was poor and the display in the transmission mode was dark, and it was necessary to greatly increase the brightness of the backlight.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a cross-sectional view of another embodiment.

[Explanation of symbols]

 1: Transparent substrate 2: Half mirror made of a metal thin film 21, 22: Transparent protective layer 3: Adhesive layer 4: Separator 5: Transparent colored layer

Continued on front page F term (reference) 2H042 BA02 BA12 BA15 BA20 DA01 DA02 DA04 DA07 DA11 DA12 DA17 DB00 DC02 DE04 2H091 FA14Z FB08 FC02 FD14 FD23 GA01 GA17 LA16 LA19 LA20 2K009 AA12 BB02 BB11 CC42

Claims (6)

[Claims] 1. A semi-transmissive specular reflection plate comprising a half mirror made of a metal thin film supported by a transparent substrate having a smooth surface, wherein the metal thin film is formed by an adhesive layer containing transparent particles and exhibiting light diffusion. An adhesive diffusion transflective reflector characterized by being coated. 2. The adhesive diffusion semi-transmissive reflection plate according to claim 1, wherein the adhesive layer contains transparent particles having an average particle size of 2.5 to 40 μm. 3. The transflective specular reflector according to claim 1, wherein the semi-transmissive specular reflector has a transparent protective layer on the front and back of the silver deposition layer, and has a total light transmittance of 5 to 30% and a total light reflectance of 90 to 50%. Adhesive diffusion transflective reflector. 4. The pressure-sensitive adhesive layer according to claim 1, wherein
An adhesive diffusion transflective reflector exhibiting a haze of 90%. 5. The method according to claim 1, wherein the diffuse reflectance is 5
An adhesive diffusion semi-transmissive reflection plate having 0 to 95%. 6. The adhesive diffusion semi-transmissive reflection device according to claim 1, further comprising a transparent coloring layer on the light transmission side of the semi-transmissive specular reflection plate, the transparent coloring layer making the color tone of the transmitted light of the half mirror equal to the color tone of the reflected light. Board.