JP2000241612A - Reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver reflecting film good in moisture proof and good in durability by providing a bedding layer and an intermediate layer with a new structure between a plastic substrate and the silver reflecting film, and providing a new structured protective film on the silver reflecting film. SOLUTION: As a plastic substrate 1, polycarbonate resin is used. In order from the surface of this plastic substrate 1, a bedding layer of a silicon oxide film 2, an intermediate layer of a copper film 3, a reflecting film of a silver film 4, a first protective layer of an aluminum oxide film 5, and a second protective layer of a titanium oxide film 6 and a silicon dioxide film 7 are formed. Adhesiveness of the plastic substrate 1 to the intermediate layer copper thin film 3 is improved by providing the silicon oxide film 2 on the substrate side of the copper film 3 of the intermediate layer, water proof of the reflecting film 4 to silver and adhesiveness of the plastic substrate 1 to the silver reflecting film 4 are ensured, and adhesiveness and anticorrosion of the reflecting film 4 are improved by alternately diffusing the silver of the reflecting film 4 and the copper of the intermediate layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection film used for optical products such as cameras, copiers, telescopes, microscopes, printers, and spectacle lenses.

[0002]

2. Description of the Related Art It is well known that a reflector having a high reflectance used for an optical product uses a metal thin film formed by a vacuum evaporation method as a reflection film. However, mirrors formed of silver or aluminum having high reflectivity as a metal material are widely used. However, in recent years, not only conventional glass but also plastic has been widely used as a substrate material for optical products, and the durability of a metal film, which is a reflective film, which has not been a problem with glass, has become a new issue. In particular, a metal film using silver with high reflectance evenly at all wavelengths has poor moisture resistance,
There has been a problem in that, over a long period of use, the oxidation progresses, the color changes to black and the reflectance decreases, and the adhesion of the silver film is deteriorated and the film itself peels.

In order to prevent the peeling of the film by improving the adhesion between the plastic substrate and the silver film, Japanese Patent No.
No. 893 discloses that a single layer of a sulfide such as zinc sulfide or chromium sulfide is provided as an underlayer, and other oxide films such as silicon oxide and aluminum oxide,
Alternatively, it has been proposed to use a nitride such as silicon nitride as the underlayer. In general, a protective film of zirconium oxide or aluminum oxide is provided on the silver reflective film to improve the durability of the silver reflective film. However, it is difficult to maintain good adhesion between the plastic substrate and the silver reflective film over a long period of time with the above-described single-layer structure underlayer. The durability of the silver reflection film was not sufficient due to moisture absorption and inflow of moisture at the interface.
Accordingly, Japanese Unexamined Patent Application Publication No. 5-127004 proposes a multilayer film in which an oxide serving as a dielectric is laminated as a base layer, or a multilayer film in which the dielectric and a metal such as chromium are laminated.

[0004]

However, in the reflecting mirror having the above-mentioned laminated structure, although a slight improvement in durability of the silver reflecting film is recognized, the adhesion between dielectrics is poor, or the reflection under the metal is poor. There is a problem that adhesion between the ground layer and the dielectric or between the metal base layer and the silver reflection film is poor, and the durability of the silver reflection film is insufficient and cannot withstand practical use.

Therefore, an object of the present invention is to provide a silver reflecting mirror having excellent moisture resistance and good durability.

[0006]

In order to solve the above problems and to achieve the object, according to the first aspect of the present invention, an underlayer and an intermediate layer having a new structure are provided between a plastic substrate and a silver reflection film. Further, the present invention is characterized in that the reflecting mirror is further provided with a protective film having a new configuration on the silver reflecting film. According to a second aspect of the present invention, the reflecting mirror according to the first aspect of the present invention is characterized in that a base layer of a silicon oxide film and an intermediate layer of a copper film are provided on a plastic substrate.

According to a third aspect of the present invention, in the reflecting mirror according to the first and second aspects, an aluminum oxide film as a first protective layer is provided on the silver reflecting film, and zirconium oxide is further provided thereon. , Silicon oxide, titanium oxide, hafnium oxide, tin oxide, antimony oxide, at least one single-layer film selected from tungsten oxide, or a multilayer formed by laminating a second protective layer consisting of two or more multilayer films It is characterized by being a protective layer.

According to a fourth aspect of the present invention, in the reflector according to any one of the first to third aspects, the thickness of the silicon oxide underlayer is not less than 20 angstroms and not more than 100 angstroms, and the copper intermediate layer is Film thickness of 1000
It is characterized in that it is not less than Angstroms and not more than 2000 Angstroms. Here, if the thickness of the silicon oxide is less than 20 angstroms, the adhesion between the plastic substrate and the copper film of the intermediate layer cannot be secured, and if it exceeds 100 angstroms, peeling occurs due to internal stress of the silicon oxide film. I will. The thickness of the copper of the intermediate layer is 1
If the thickness is less than 2,000 angstroms, a sufficient waterproof property cannot be obtained with respect to the silver reflection film. On the other hand, if it exceeds 2000 angstroms, the interlayer between the silver reflection film and the silver reflection film is unsuitable because of the internal stress of the copper film.

According to a fifth aspect of the present invention, in the reflecting mirror according to any one of the first to fourth aspects, the thickness of the aluminum oxide of the first protective layer is not less than 20 angstroms and not more than 100 angstroms, Zirconium oxide, silicon dioxide, titanium oxide, hafnium oxide, tin oxide, antimony oxide, and a thin film of any oxide selected from tungsten oxide formed thereon, having a thickness of 50 Å or more, a single layer or The thickness of the entire second protective layer having a multilayer structure is not less than 50 angstroms and not more than 1000 angstroms. Here, if the thickness of the aluminum oxide of the first protective layer is less than 20 angstroms, the adhesion between the silver reflective film and the second protective layer formed thereon cannot be ensured. Conversely, if the thickness exceeds 100 angstroms, Peeling occurs due to the internal stress of the aluminum oxide film. If the thickness of one layer of the second protective layer formed on the first protective layer is less than 50 angstroms, the smoothness of the film is poor and the color tone is likely to be poor in appearance. If the thickness exceeds 1000 angstroms, interference colors occur in each layer of the second protective layer, which is not suitable.

An embodiment of the present invention will be described below.
Thus, the present invention is not limited to the embodiment.

[0011]

FIG. 1 is a diagram showing a thin film configuration of a reflecting mirror according to an embodiment of the present invention. The plastic substrate 1 may be transparent or opaque, and may be a thermoplastic resin such as a polycarbonate resin, an acrylic resin, an acrylonitrile / styrene copolymer, a methyl methacrylate / styrene copolymer, or a polyolefin resin;
A thermosetting resin such as a polyurethane resin, an epoxy resin, or diethylene glycol bisallyl carbonate can be used. In the present embodiment, a polycarbonate resin is used. This plastic substrate 1
, A silicon oxide film 2 as a base layer, a copper film 3 as an intermediate layer, a silver film 4 as a reflective film, an aluminum oxide film 5 as a first protective layer, a titanium oxide film 6 and a silicon dioxide film 7 in this order. Is formed.

By providing the silicon oxide film 2 on the substrate side of the copper thin film 3 of the intermediate layer, the adhesion between the plastic substrate 1 and the copper thin film 3 of the intermediate layer is enhanced, and copper is used as the material of the intermediate layer 3. As a result, the waterproofness of the reflective film 4 to silver and the adhesion between the plastic substrate 1 and the silver reflective film 4 are ensured, and the silver of the reflective film 4 and the copper of the intermediate layer 3 are diffused with each other to adhere to the reflective film 4. And corrosion resistance are improved. A first protective layer 6 of aluminum oxide is provided on the reflective film 4 to secure adhesion between the second protective layer composed of the titanium oxide film 6 and the silicon dioxide film 7 and the reflective film 4. In order to improve the durability of the mirror and reduce surface reflection, a second protective layer comprising a combination of a titanium oxide film 6 as a high refractive index material and a silicon dioxide film 7 as a low refractive index material is provided. Since the silicon film has excellent scratch resistance, it is most suitable as the outermost protective layer.

Next, a method of manufacturing the reflecting mirror according to the present embodiment will be described in detail. First, a disc-shaped polycarbonate substrate having a diameter of 30 mm and a thickness of 1.0 mm is prepared,
It is installed on the rotating dome above the vacuum evaporation system. As an evaporation material for resistance heating, silicon oxide powder and granular copper and silver are separately placed on an evaporation source. As another evaporation source for heating an electron beam, silicon dioxide granules and granular aluminum oxide and titanium oxide are placed.

Next, the inside of the vapor deposition apparatus is evacuated by a vacuum pump to reduce the pressure to 1.33 × 10 −3 Pa. After reaching a desired degree of vacuum, oxygen gas is introduced to reduce the degree of vacuum to 1.33 × 1.
Lower to 0-2Pa. After that, first, a silicon oxide film was formed to a thickness of 50 Å by a resistance heating method, the introduction of oxygen gas was stopped, the degree of vacuum was maintained at 1.33 × 10 −2 Pa, then a copper film was formed to a thickness of 1500 Å, and silver was further formed. A 2000 angstrom film was formed. Here, when the thickness of silver is 50 Å or less, a half mirror having insufficient reflectivity is formed, and 2,000 Å has an appropriate thickness as a high reflection film. Then, 70 Å of aluminum oxide, 150 Å of titanium oxide, and 200 Å of silicon dioxide were formed by electron beam evaporation.
Films were formed in angstrom order.

The reflectance of the thin film formed by the above method is 98.
%Met. Further, a moisture resistance test was performed in which this film-formed sample was left in a thermo-hygrostat at an ambient temperature of 50 ° C. and a relative humidity of 90% for 20 hours. No peeling was observed in a subsequent tape peeling test. here,
For comparison, a mirror having exactly the same structure as that of the embodiment was manufactured without forming the intermediate layer 3 made of a copper film, and the same moisture resistance test was performed. Film peeling occurred at the edge of the thin film, and large peeling was observed in the tape peeling test.

[0016]

As described above, according to the present invention, a reflecting mirror having excellent adhesion to a plastic substrate and excellent durability can be obtained.

[Brief description of the drawings]

FIG. 1 shows a basic thin film configuration of the present invention 1. Base material (plastic) 2. Base layer (silicon oxide) 3. Intermediate layer (copper) 4. Reflective film (silver) 5 ... first protective layer (aluminum oxide) 6 ... second protective layer (titanium oxide) 7 ... second protective layer (silicon dioxide)

Claims (5)

[Claims] 1. A reflecting mirror in which a metal film is provided on a resin substrate, wherein the reflecting film is a silver thin film, and a base layer and an intermediate layer are provided between the substrate and the reflecting film in order from the substrate side, A reflector comprising a multilayer protective layer provided on the reflective film. 2. The reflecting mirror according to claim 1, wherein the underlayer is a silicon oxide film, and the intermediate layer is a copper film. 3. The reflecting mirror according to claim 1, wherein the first protective layer of the protective layer is an aluminum oxide film in order from the reflective film side, and the second protective film thereon is zirconium oxide. A reflecting mirror having a multilayer structure comprising at least one single-layer film selected from silicon dioxide, titanium oxide, hafnium oxide, tin oxide, antimony oxide, and tungsten oxide or two or more multilayer films. 4. The reflecting mirror according to claim 1, wherein the thickness of the silicon oxide film of the underlying layer to be formed is not less than 20 angstroms and not more than 100 angstroms, and the thickness of the copper film of the intermediate layer. A reflector having a film thickness of not less than 1000 angstroms and not more than 2000 angstroms. 5. The reflecting mirror according to claim 1, wherein a thickness of the aluminum oxide film of the first protective layer to be formed is not less than 20 angstroms and not more than 100 angstroms. The thickness of the second protective layer selected from among zirconium oxide, silicon dioxide, titanium oxide, hafnium oxide, tin oxide, antimony oxide, and tungsten oxide is 50 angstrom or more and is a film of the entire second protective layer. Thickness 1000
A reflector characterized by being less than angstrom.