JPH10193494A - Diffusion reflecting film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve undirectivity of paper whiteness by forming a metal deposition layer at an opposite side of a reflection using surface of a plastic film base material containing white pigment and specifying total ray permeability, and forming a corrosion inhibiting layer on the deposition layer, thereby enhancing diffusion reflectivity. SOLUTION: The diffusion reflecting film comprises metal deposition layers 2 formed on a reflection using surface and its opposite surface of a base material 1 and corrosion inhibiting layers 3 on the layers 2. As the material 1, a plastic film containing white pigment and having total ray permeability of 50% or less is used. The layer 2 is formed by a film forming method such as a vacuum deposition method, sputtering method or ion plating method. As the layer 2, sole silver, alloy of the silver and other metal, or laminate of silver and other metal is preferable. As the layer 3, paint made of thermoplastic resin, thermosetting resin, electron beam curable resin or ultraviolet curable resin is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffuse reflection film for a liquid crystal display, and more particularly to a paper white color diffusion reflection film having a high diffuse reflectance and excellent non-directionality. The diffuse reflection film of the present invention is suitable for use in a conventional reflection type liquid crystal display such as an STN type or a TFT type, or a reflection type liquid crystal display without a polarizing plate.

[0002]

2. Description of the Related Art Conventionally, as a reflective film, a polyethylene terephthalate film kneaded with a white pigment, a film obtained by depositing aluminum or silver on a matted polyethylene terephthalate film, a silver-deposited film, an aluminum-deposited film, an aluminum foil, an aluminum plate, stainless steel Boards and the like are used.

[0003]

However, such a conventional white pigment-kneaded polyethylene terephthalate film has a drawback that the diffuse reflectance is low and the paper whiteness is poor. What is paper whiteness?
It is based on the whiteness of barium sulfate used for the standard white plate, and this whiteness is necessary for liquid crystal displays. The higher the whiteness of the liquid crystal display screen, the better the screen is. That's why. Aluminum or silver deposited on a matted polyethylene terephthalate film (the deposited surface is used as a reflective surface)
And aluminum foil, aluminum plate, stainless steel plate, and the like have drawbacks such as directivity and poor paper whiteness because they have a metallic tone.

[0004]

The present invention has solved the above-mentioned problems of the conventional product. That is, a metal vapor-deposited layer (2) is formed on the opposite side of the reflective use surface of a plastic film substrate (1) containing a white pigment and having a total light transmittance of 50% or less, and the metal vapor-deposited layer (2) is further formed. The present invention is a diffuse reflection film having a corrosion prevention layer (3) formed thereon, and a plastic film substrate (1) containing a white pigment is made of titanium oxide, barium sulfate, magnesium sulfate, silicon oxide, carbonate One or more white pigments selected from magnesium and calcium carbonate are kneaded into plastic and contained in the film, or held on the film surface by coating, or contained in a form having both of the above. Wherein the metal-deposited layer (2) is selected from silver alone, an alloy of silver and another metal, and a laminate of silver and another metal. Is a diffuse reflective film in which the more than.

[0004] By depositing silver on the opposite side of the reflective surface of a plastic film substrate containing a white pigment and having a total light transmittance of 50% or less, opacity is imparted and silver becomes a highly reflective layer, and diffuse reflection is performed. As the rate increases, the paper white color is further emphasized. Further, the light reflected by the silver vapor deposition layer is multiple-reflected by the white pigment, and becomes light having a low directivity and diffused. Further, since the silver vapor deposition layer is susceptible to corrosion, a corrosion prevention layer is provided to impart durability, and all the problems of the conventional diffuse reflection film are eliminated, thereby providing a practicable diffuse reflection film.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the diffuse reflection film of the present invention (FIG. 1) will be described in detail. As the substrate (1) used in the diffuse reflection film of the present invention, any plastic film containing a white pigment and having a total light transmittance of 50% or less can be used. Further, a white plastic film to which an ultraviolet absorber, a whitening agent, an antistatic agent and the like are added to improve the performance can be used. 5 total light transmittance
0% or less is a preferable range, and more preferably 20% or less.
%, More preferably 15% or less. The lower limit is not particularly limited. The base resin of the plastic film is not particularly limited, but is preferably an acrylic film, a polycarbonate film, a polyarylate film, a polyethylene terephthalate film, a polyethylene naphthalate film, a fluorine film, or the like.

The white pigment contained in the substrate (1) includes titanium oxide, barium sulfate, magnesium sulfate,
White pigments such as silicon oxide, magnesium carbonate and calcium carbonate are preferred. The particle size is not particularly limited, but is preferably 50 μm or less. If the particle size is larger than 50 μm, it is not preferable because it may be kneaded into the plastic film or hinder the coating on the surface of the plastic film. The white pigment is kneaded into the plastic film, coated on the surface of the plastic film, or further coated on the kneaded plastic film. The addition amount is preferably such that the total light transmittance is 50% or less. If the total light transmittance is 50% or more, it is not preferable because metallic luster is produced and directivity and paper white color are weakened. These base materials (1) are more preferably those obtained by film-forming the plastic containing the white pigment,
The plastic may further contain air bubbles and other polymers to achieve further improvement in lightness and whiteness.

The thickness of the substrate (1) is not particularly limited, but is usually preferably in the range of 12 to 300 μm. When the thickness is less than 12 μm, the strength is insufficient and the workability is poor, which is not preferable. On the other hand, when the thickness is more than 300 μm, the strength is too strong and the workability is deteriorated, but the cost is increased and it is not economical or practical.

The metal deposition layer (2) used in the diffuse reflection film of the present invention is formed by a film forming method such as a vacuum deposition method, a sputtering method and an ion plating method. , Silver alone, an alloy of silver and another metal, and a laminate of silver and another metal are preferable. The thickness of the metal deposition layer (2) is not particularly limited, but is usually 10 nm.
It is appropriately selected from the range of about 200 nm. Thickness 1
At less than 0 nm, no reflection effect is observed, while
Even if it exceeds, the reflection effect is not further improved and the internal stress of the metal deposition layer increases and the adhesion strength with the base material tends to decrease, and the amount of silver used also increases, so it is economical Inferior and not preferred.

The corrosion prevention layer (3) employed in the diffuse reflection film of the present invention is not particularly limited, but may be, for example, a thermoplastic resin, a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin, or the like. Any coating material is used.
For example, amino resin, amino alkyd resin, acrylic resin, styrene resin, acryl-styrene copolymer, urea-melamine resin, epoxy resin, fluororesin, polycarbonate, nitrile cellulose, cellulose acetate, alkyd resin, A resin coating composed of a single or a mixture thereof such as a polyester resin and a polyamide resin is used. The corrosion prevention layer (3)
A metal coating layer (2) of a base material on which the metal coating layer (2) is formed by coating a coating obtained by diluting the corrosion prevention layer resin with a solvent;
It is formed by applying and drying (curing in the case of a curable resin) the entire surface on the side by a usual coating method such as a gravure coating method, a roll coating method, and a dip coating method. The thickness of the corrosion prevention layer (3) is not particularly limited, but is usually appropriately selected from the range of about 0.5 to 5 μm.
If the thickness is less than 0.5 μm, the surface of the substrate and the metal deposition layer cannot be uniformly coated, the effect of forming the corrosion prevention layer cannot be sufficiently exerted, and there is no value in forming the corrosion prevention layer, On the other hand, even if the thickness exceeds 5 μm, there is no great difference in the effect of the corrosion prevention layer, and the drying speed of the corrosion prevention layer becomes slow, which is not efficient.

[0010] The diffuse reflection film thus obtained has a metal deposition layer (2) formed on the surface of the substrate (1) opposite to the reflective surface, and further has a corrosion prevention layer (3) on the metal deposition layer (2). By forming (1), the paper becomes a paper white color having a high diffuse reflectance and excellent non-directionality, and is used for a diffuse reflection film for a liquid crystal display and the like. Hereinafter, the diffuse reflection film will be described in detail with reference to examples, but the invention is not limited thereto.

[0011]

【Example】

** Example 1 A 100 μm thick polyethylene terephthalate film (manufactured by Toray, trade name: Lumirror X-42) in which silicon oxide was kneaded to a total light transmittance of 46%, and silver was vacuum-deposited on the side opposite to the reflective surface. To form a metal evaporation layer having a thickness of 80 nm, and then apply a melamine-epoxy resin paint on the entire surface to form a corrosion prevention layer having a thickness of 1.5 μm.
A diffuse reflection film of the present invention was obtained. ** Example 2 Sputtering of silver on the opposite side of the reflective surface of a 50 μm thick polyethylene terephthalate film (manufactured by Teijin, trade name: Teijin Tetron film U2) into which titanium oxide was kneaded to make the total light transmittance 23%. An 80 nm-thick metal vapor-deposited layer was formed thereon, and then an acrylic resin was applied on the entire surface and dried to form a 1.5 μm-thick corrosion prevention layer, thereby obtaining a diffuse reflection film of the present invention.

** Example 3 Opposite the reflective surface of a 38 μm-thick polyethylene terephthalate film (diafoil, trade name: Diafoil W-400) into which titanium oxide has been kneaded to a total light transmittance of 14%. Silver with a thickness of 80 nm by sputtering
Was formed, and then an acrylic resin paint was applied on the entire surface and dried to form a corrosion prevention layer having a thickness of 1.5 μm, thereby obtaining a diffuse reflection film of the present invention. ** Practical Example 4 A coating liquid obtained by kneading titanium oxide into an acrylic resin paint was applied to the entire surface of a 5 μm-thick and dried to obtain a total light transmittance of 20%. The opposite side of the 55 μm-thick polyethylene terephthalate film was coated with silver. 80 nm thick by vacuum evaporation
Was formed, and then a melamine-epoxy resin paint was applied on the entire surface and dried to form a corrosion prevention layer having a thickness of 1.5 μm, thereby obtaining a diffuse reflection film of the present invention. .

** Comparative Example 1 A 100 μm-thick polyethylene terephthalate film (trade name: Lumirror X-42) having a total light transmittance of 46% was kneaded with silicon oxide to obtain a conventional diffuse reflection film. . ** Comparative Example 2 A 50 μm-thick polyethylene terephthalate film (manufactured by Teijin, trade name: Teijin Tetron Film U2) having a total light transmittance of 23% by mixing titanium oxide was obtained.

** Comparative Example 3 A 38 μm-thick polyethylene terephthalate film (manufactured by Diafoil, trade name: Diafoil W-400) obtained by kneading titanium oxide to a total light transmittance of 14% was obtained. Was. ** Comparative Example 4 A conventional dispersion coated with a 55 μm-thick polyethylene terephthalate film having a total light transmittance of 20% by applying a 5 μm-thick coating liquid obtained by kneading titanium oxide into an acrylic resin coating material and drying the entire surface. A reflective film was obtained.

Table 1 shows the results of examining the diffuse reflectance, whiteness, and directivity of the films thus obtained in Examples and Comparative Examples. <Evaluation method of diffuse reflectance> The diffuse reflectance was measured using a spectrophotometer (UV-3100PC) manufactured by Shimadzu Corporation, and the wavelength at 550 nm was read and examined. <Directivity evaluation method> The directivity is manufactured by Shimadzu Corporation.
Using a spectrophotometer (UV-3100PC), the absolute reflectance (550 nm) at angles of incidence of 5 °, 12 °, and 45 ° was read and examined. <Evaluation method of whiteness> The whiteness was manufactured by Shimadzu Corporation.
Using a spectrophotometer (UV-3100PC), CIE L *, a *, and b * of the diffuse reflected light were measured and examined.

[0016]

[Table 1] From Table 1, it can be seen that the example of the present invention has an improved diffuse reflectance, is non-directional and is excellent in paper white color as compared with the comparative example.

[0017]

The present invention contains a white pigment and has a total light transmittance of 50%.
Form a metal vapor deposited layer on the opposite side of the reflective surface of the following plastic film base material, and further form a corrosion prevention layer on top of this. A color diffuse reflection film for a liquid crystal display was obtained. The effect of the present invention is exhibited when the total light transmittance of the plastic film substrate is 50% or less, but is more preferably 15% or less, and surprisingly 0% of the total light transmittance (in the present invention). Measurement method)
It was found that the effect of the metal deposition layer was also obtained in the case of (1).

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing the configuration of the present invention.

[Explanation of symbols]

 (1): Plastic substrate (2): Metal deposition layer (3): Corrosion prevention layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C23C 14/20 C23C 14/20 A

Claims (3)

[Claims] 1. A white pigment containing a total light transmittance of 50%.
A metal film layer (2) is formed on the opposite side of the reflective film of the following plastic film substrate (1), and a corrosion prevention layer (3) is formed on the metal film layer (2). Diffuse reflection film. 2. A plastic film base material (1) containing a white pigment, wherein one or more white pigments selected from titanium oxide, barium sulfate, magnesium sulfate, silicon oxide, magnesium carbonate and calcium carbonate are added to the plastic. The diffuse reflection film according to claim 1, wherein the film is kneaded and contained in the film, held on the film surface by coating, or contained in a form having both of the above. 3. The diffusion according to claim 1, wherein the metal deposition layer (2) is at least one selected from silver alone, an alloy of silver and another metal, and a laminate of silver and another metal. Reflective film.