JPS6229383B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a reflective mirror, which is formed by depositing an optical multilayer reflective coating using a vacuum plating method such as vacuum evaporation, sputtering, or ion plating, and an organic polymer film using a painting or printing method. It is applicable to automobiles, indoors, cosmetics, and interior and exterior building materials. Conventional rearview mirrors for automobiles and mirrors for home use and cosmetic use are as shown in the enlarged cross-sectional views of Figure 1 A and B.
A monometallic metal such as silver, aluminum, or chrome is deposited on the a-side of the base material by chemical plating or vacuum plating. That is, in Fig. 1A, Ag,
A metal reflective film (b) made of Al, Cr, etc. is formed, and a protective coating (c) is further applied thereon. Further, in FIG. 1B, the reflective metal film b is applied to the surface of the base material a, and a transparent protective film d is applied thereon to be used as a surface mirror. The conventional mirror described above can be coated relatively easily. by the way,
It is generally known that there are the following methods for forming thin films. 1. Vacuum evaporation method: This is a manufacturing method that is widely used. Powder or particulate materials are placed in a crucible, heated in a base atmosphere, and evaporated to deposit a thin film on a substrate. 2. Sputtering method: The same material as above is used as a target by melting or sintering, and it is sputtered with argon ions in a vacuum to deposit a thin film on a substrate. 3 Ion plating method = Ion plating on the substrate in vacuum
A negative bias voltage of approximately 100 to 600 V is applied to ionize the evaporated material and deposit a thin film on the substrate. 4. Gas phase reaction method: A method for producing oxide thin films, in which a highly volatile chloride is brought into contact with water vapor, carbon dioxide, etc., resulting in hydrolysis, and the resulting hydroxide is decomposed and deposited on a heated substrate. It is not widely used due to the risk of pollution. 5. Liquid phase reaction method = A method for producing an oxide thin film in the same manner as in 4. A metal alkoxide solution is applied to a substrate by spraying or dipping, and the solution is thermally decomposed to deposit a thin film. (Note) The above 1) to 3) are collectively referred to as the vacuum plating method. In the conventional reflecting mirrors shown in FIGS. 1A and 1B, a reflective coating can be easily formed, but with the metal reflective coating described above, the reflected light is used in a monochrome state. However, in recent years, reflective mirrors that are colored blue and have an excellent anti-glare effect and design have been adopted as automobile rear view mirrors. It is difficult to satisfy this requirement in terms of coloring and reflectance using the conventional methods described above. That is, if one were to create a blue reflecting mirror using the conventional method, the back mirror shown in Figure 1A would be made by mixing a blue dye (organic or inorganic) with a transparent glass substrate a and forming a metal film. It is necessary to either color the reflected light from b or, in the case of the surface mirror shown in Fig. 1b, to color the transparent protective film d blue as described above, but both require the mixing of dyes or pigments, and coloring is not possible. There are problems such as variations in color, poor weather resistance of dyes, etc., and difficulty in producing bright colors due to absorption. Furthermore, it is well known that multilayer films of nonmetals such as oxides, fluorides, and sulfides are used in lens coatings and interference filters as antireflection films for optical equipment. For example, a reflector that exhibits a blue color utilizes the interference color created by the light interference effect of the non-metallic film mentioned above.The reason why this method of reflecting mirrors was delayed in being adopted for automobile rear view mirrors is because of the conventional metal This is presumed to be because the cost is higher than that of a reflective film. The conventional example shown in Figure 1 C is a colored mirror that has been seen in German-made mirrors in recent years, and is considered to be a liquid phase reaction method as described in 5) above, in which a glass substrate a is immersed in a liquid and a multilayer film e is coated on both sides. A black coating film G was applied to the back surface of the film, but the detailed method is unknown. Furthermore, FIG. 1D shows an example in which a multilayer film f is formed by the methods 1) to 3) above. For example, the first layer _f1 is made of _TiO2 , the second layer _f2 is made of _MgF2 , and the third layer is made of TiO2. This is an example in which TiO ₂ is formed on fn. Basically, each thin film of oxide, fluoride, sulfide, etc. has its own unique refractive index.
When forming a single layer film with a higher refractive index than the substrate,
It is known that the reflectance is maximum at a wavelength position where the optical thickness of the film is an odd multiple of λ/4 (λ is the wavelength), and depending on the purpose, high refractive index with equal optical thickness A multilayer film is formed by stacking a film and a low refractive index film. In addition, since the non-metallic film is a transparent material with extremely low absorption compared to the metallic reflective film (Ag, etc.), some kind of absorber is required to use it as a colored reflector. A protective film g is applied. The protective film g of the reflecting mirror in the conventional method as described above is generally made of an organic polymer, and is coated on the non-metallic multilayer film, especially the TiO ₂ film obtained by vacuum plating. Then, the adhesion between the organic polymer protective film g and the TiO ₂ film deteriorates, and the organic polymer protective film g peels off from the TiO ₂ film, resulting in a problem that it is not suitable for practical use. In other words, amorphous titanium oxide obtained by the liquid phase reaction method has little peeling phenomenon, but titanium oxide obtained by the vacuum plating method is known to have an anatase crystal structure by X-ray analysis. This anatase-type titanium oxide has a unique photo-optical property of liberating active oxygen when exposed to light energy.
Therefore, it is presumed that the organic polymer protective film deteriorates due to oxidative decomposition and chain reactions thereof, and the organic polymer protective film peels off from the TiO ₂ film. In order to improve this adhesion, it is necessary to modify the organic polymer protective film, but this is expensive and technically difficult. Furthermore, in the method shown in Figure 1 (c) using the conventional liquid phase reflection method, the film has an amorphous structure and is softer than the vacuum plating method, so it is easily scratched, and the refractive index is low, so the reflectance is also low. Above, the reflected image becomes a superimposed image due to film deposition on both sides of the substrate due to immersion. Even if the film on the back side is removed to avoid this, the mirror will still be used as a front mirror, and there is a problem in that the slightest scratch or deposit will cause a noticeable change in color. The present invention is a method for manufacturing a durable, high-quality multilayer reflective mirror that improves the deterioration of the adhesion of the reflective coating, which is a drawback of the conventional reflective mirrors as described above, and also improves the scratch resistance of the mirror surface. We aim to provide the following. FIGS. 2 to 4 are enlarged partial cross-sectional views of a multilayer reflective mirror constructed by the manufacturing method of the present invention. First, FIG. 2 shows a typical example of the manufacturing method of the present invention, and is used as a symmetrical example for various durability tests to be described later. In Fig. 2, the basic configuration is to deposit and laminate a multilayer film L of (TiO ₂ +MgF ₂ +TiO ₂ ) by vacuum plating on a transparent substrate G such as glass or ceramic, and then add a stable oxide layer. A as SiO ₂ (or
A protective film C is formed by vapor-depositing Al ₂ O ₃ or a mixture of SiO ₂ and Al ₂ O ₃ and applying an organic polymer paint to the upper layer. To explain the process example in more detail, pre-treatment process of the base material: A 2 mm thick plate glass base material G is ultrasonically cleaned (300W manufactured by Kaiyo Denki) in a 2% solution of detergent (Idemitsu Kosan's T-Pol), and then washed with water - alcohol. Washing, draining, and drying with warm air (60℃). Vacuum plating process: The glass is attached to a vacuum device (BMC type), and the temperature of the glass is raised to 250℃ while evacuating with a vacuum pump.
Heat to ℃. Meanwhile, electron beam evaporation equipment (TEBG102UB)
TiO ₂ powder is heated at 6KV, 400mA using an electron beam of
Then, MgF ₂ was deposited alternately at 6 KV and 80 mA so that the optical film thickness, that is, λ/4, was the same, and then as oxide film A.
Vapor deposition of SiO ₂ is performed at 6KW and 200mA so that the optical film thickness becomes λ/2. The glass is a multilayer film with uniform thickness.
Rotate horizontally so that All evaporation materials use purity 99.9. Also, in this case λ=
Set at 480nm. Coating of protective film The deposited glass was taken out from the vacuum tank, cooled to room temperature, and then a commercially available paint (Tanabe Chemical's acrylic-liquid black paint PRX1000) was sprayed onto the coated surface and allowed to set. A protective film C is formed by baking and drying at 30°C for 30 minutes. In the above process, the particularly important point is that TiO ₂
The point is that a SiO ₂ layer is always provided between the film and the protective film C. In order to compare the durability of the reflector of the above example,
The following table shows the test data for the sample with _two SiO layers and the sample with _{the two} SiO layers omitted.

【table】

[Table] As is clear from the data in the table above, the effect of SiO ₂ is clearly visible. Figures 3A and 3B show other embodiments in which the present invention is applied to a rear mirror, and Figure 3A shows a case where the present invention is applied to a plate glass base material G.
_Two layers of TiO are deposited, a stable oxide A made of SiO ₂ is deposited on top of that to form a multilayer film, and a protective film C is added on top of that.
It is painted with. In Figure 3B, oxides other than TiO ₂ , fluorides, sulfides, etc. are vapor-deposited on the glass substrate G as the first layer, and the final layer is TiO _{2 .}
A multilayer film L is deposited thereon, the stable oxide film A is deposited thereon, and a protective film C is further applied. FIG. 4 shows an embodiment applied to a front mirror. That is, in Fig. 4A, a TiO ₂ layer is deposited on the surface of a plate glass substrate G, then SiO ₂ is deposited on the surface, and a protective film T as a clear top coat is further applied on the surface. . In FIG. 4B, a multilayer film L having TiO ₂ as the final layer is deposited, and the oxide film A and the clear protective film T are deposited thereon. In Figure 4 C, a multilayer film L with TiO ₂ as the first layer and the final layer is deposited on the surface of a plate glass substrate G, and a stable oxide film A made of SiO ₂ is deposited on top of it.
This is an example in which a clear protective film T is further applied thereon. Various other combinations are applicable including the case of the above-mentioned back mirror. FIG. 5 is a curve diagram comparing spectral reflectance.
The curves Ag and Cr are monochrome reflectance curves of conventional metal vapor deposited films, and the curve SH is blue based on the liquid phase reaction method described above. The curves of the multilayer film _reflector using the vacuum plating method of the present invention are E _xp 1 to 3, and E _{xp 1} is the case of the embodiment shown in FIG _. The back mirror with SiO ₂ and a protective film, E _{xp 2} , is a case where Al ₂ O ₃ is substituted for SiO ₂ in E _xp 1, and _the reflectance of both is Almost similar. E _xp 3 is
This is the case where the TiO ₂ single layer is λ/4, the mixing ratio of Al ₂ O ₃ and SiO ₂ is 1:3, and the thickness is also λ/4, but by adjusting the film thickness, it is the same as E _xp 1. can have the following characteristics. In addition, in the above-mentioned example, as a high refractive index material,
It is formed based on TiO ₂ , but in the middle there is
ZrO ₂ , CeO ₂ , or ZnS may also be used. Also, low refractive index materials
It may be AlF ₆ 3Na, MgF ₂ , CeF ₃ or SiO _{2 ,} etc., and a multilayer film L is formed by stacking these layers alternately so as to have an optimum film thickness according to the above-mentioned law, and then SiO ₂ or Al A stable oxide film A made of ₂ O ₃ or a mixture of both is vapor deposited, and a protective film C made of an organic polymer is applied thereon to form a mirror surface. In this case, it is still effective to control the optical thickness so that the thickness of the stable oxide film A becomes λ/4 or λ/2 as a low refractive index film.
Since the thickness of the stable oxide film A is not restricted by the required color tone, that is, the wavelength λ or the reflectance, even if a multilayer film is formed as a result, it can be selected appropriately. As described above, the method of manufacturing a multilayer reflector according to the present invention using glass or ceramic as a base material is to use a protective film (backing or clear top coat) after depositing a non-metallic film with TiO ₂ as the final layer. Since a stable oxide film made of SiO ₂ or Al ₂ O ₃ or a mixture of both is interposed between a certain organic polymer layer, interlayer adhesion between TiO ₂ and the protective film is significantly improved. A reflecting mirror with extremely high durability can be obtained. It also has good moisture resistance and hot water resistance, and can withstand even harsh environments. Next, in the manufacturing method of the present invention, since conventional organic polymer films and plastic materials can be used, no special process changes or formulations are required, resulting in low costs.
In addition, the vacuum plating method creates a crystalline structure (rutin type or anatase type) of the TiO ₂ film, so it is hard and scratch-resistant, and its refractive index is high, making it possible to increase the reflectance. can be produced, and the drawbacks of liquid phase reaction methods can be improved. As described above, the reflecting mirror obtained by the manufacturing method of the present invention has good weather resistance, scratch resistance, and abrasion resistance, and can reduce processing costs. It should be noted that, as a matter of course, the manufacturing method according to the present invention is not limited to the above-mentioned examples.

[Brief explanation of the drawing]

FIGS. 1A to 1D are partially enlarged cross-sectional views of a reflecting mirror constructed using a conventional construction method. Figure 2 is an enlarged cross-sectional view of a multilayer reflective mirror manufactured by the manufacturing method of the present invention;
Figures A and B are cross-sectional views showing another embodiment similarly applied to a back mirror, and Figures A, B, and C are cross-sectional views when applied to a front mirror. FIG. 5 is an explanatory diagram of various examples of spectral reflectance curves. G...Base material, A...Stable oxide film, L...Multilayer film,
C, T...Organic polymer protective film.

Claims (1)

[Claims] 1. A method for manufacturing a multilayer reflective mirror in which a reflective coating is formed on the surface of a base material made of glass or ceramic, the nonmetallic film having the final layer of titanium oxide (TiO ₂ ) layered on the base material by vacuum plating. A stable oxide film consisting of either silicon dioxide (SiO ₂ ) or alumina (Al ₂ O ₃ ), or a mixture of both (Al ₂ O ₃ ·SiO ₂ ) is also vacuum-deposited. A method for manufacturing a multilayer film reflecting mirror, comprising a second step of vapor deposition by a deposition method, and a third step of applying an organic polymer-based protective film on the surface of the stable oxide film.