JPH052962B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a high surface reflection mirror having a surface reflection multilayer film used in optical products such as cameras, telescopes, and microscopes. [Prior Art] Silver, which has a high reflectance in the visible to near-infrared range, is generally used as a reflective material for high-reflection mirrors used in optical products. However, when using silver, there is a problem that a single layer film is inferior in terms of film adhesion, moisture resistance, sulfidation resistance, etc. For this reason, we adopted a multilayer film structure consisting of a single layer of silver, an underlayer, and a protective layer, which provides excellent film adhesion, moisture resistance,
Provides sulfidation resistance, etc. For example, as shown in FIG. 3, in a four-layer structure, a base layer 2e made of aluminum oxide is formed on a substrate 1e, a reflective layer 3e made of silver is formed on the base layer 2e, and a reflective layer 3e made of silver is further formed on the reflective layer 3e. An example in which an aluminum oxide layer 4e and a silicon dioxide layer 5e are sequentially formed as a protective layer ("Reflectance and
durability of Ag mirrors coated with thin
layers of Al ₂ 0 ₃ plus reactively deposited
silicon oxide,” Appl.0pt., 14 (1975), 2639)
There is. Further, as shown in FIG. 4, in a six-layer structure, a base layer 2f made of copper is formed on the substrate 1f, a reflective layer 3f made of silver is formed on the base layer 2f, and a protective layer 3f is further formed on the reflective layer 3f. An example in which an aluminum oxide layer 4f, a tantalum oxide layer 5f, a silicon dioxide layer 6f, and a tantalum oxide layer 7f are sequentially formed as layers ("Progress in the development of
durable silver−based high−reflectance
coating for astronomical telescopes,”
Appl.0pt., 24 (1985), 1164). All of the above methods are effective when glass is used as the substrate of the high surface reflection mirror. [Problem to be solved by the invention] In recent years, the technology for molding plastics such as polycarbonate and acrylic resin has developed, and plastics have the advantage of being easier to mold into complex shapes compared to glass, so their use as optical members has expanded. is also expanding. For example, it is desired that pentaprisms used in cameras be made of plastic to reduce costs, and products in which a hollow penta-shaped molded product is coated with a reflective film on its surface are also beginning to be used. However, when the substrate is made of plastic such as polycarbonate or acrylic resin, the same film structure as described above has poor film adhesion, moisture resistance, and sulfurization resistance, compared to when the substrate is made of glass. There is a problem that they are inferior in terms of gender, etc. Therefore, an object of the present invention is to provide a high surface reflection mirror that has excellent film adhesion, moisture resistance, sulfurization resistance, etc. even when the substrate is made of plastic such as polycarbonate or acrylic resin. . [Means for solving the problem] As a result of intensive research in view of the above purpose, the present inventors have:
Even when the substrate is made of plastic such as polycarbonate or acrylic resin, in order to obtain a high-reflection mirror with excellent film adhesion, moisture resistance, and sulfide resistance, it is necessary to use chromium sulfide as an underlayer to form a reflective layer with the substrate. Forming a protective layer of chromium sulfide on the reflective layer made of silver can prevent sulfur ions from entering the reflective layer. They discovered that it is possible to do this, and came up with the present invention. That is, the high surface reflection mirror of the present invention includes (a) a base layer made of chromium sulfide formed on the substrate surface;
(b) a reflective layer made of silver formed on the chromium sulfide base layer; (c) a protective layer made of chromium sulfide formed on the reflective layer (); and (d) on the protective layer (). It is characterized by having a protective layer ( ) formed on. [Function] Even when the substrate of a high surface reflection mirror is made of plastic such as polycarbonate or acrylic resin, a chromium sulfide base layer with high adhesion to the substrate is formed on the substrate, and the chromium sulfide base layer is When a reflective layer made of silver is formed on a ground layer, the film adhesion between the substrate and the reflective layer made of silver is strengthened, and film adhesion, moisture resistance, etc. are improved. Furthermore, by forming a protective layer () of chromium sulfide on the reflective layer made of silver, it is possible to prevent sulfur ions from entering the reflective layer. As a result, a highly reflective mirror with high film adhesion, moisture resistance, sulfidation resistance, etc. can be obtained. [Embodiment] FIG. 1 schematically shows a high surface reflection mirror according to an embodiment of the present invention. This high surface reflection mirror has a five-layer structure, and each layer is formed by vacuum evaporation, sputtering, or the like. In this embodiment, a case is shown in which the high surface reflection mirror is formed on a substrate 1a made of plastic such as polycarbonate or acrylic resin, but it goes without saying that it can also be formed on a glass substrate. A base layer 2a made of chromium sulfide is formed on the substrate 1a, a reflective layer 3a made of silver is formed on the chromium sulfide base layer 2a, a protective layer () 4a is formed on the reflective layer 3a, and a protective layer () 4a is formed on the reflective layer 3a. 4a
Protective layers (5a, 6a) are formed thereon. The base layer 2a is formed of chromium sulfide, which has high adhesion to the substrate 1a made of the above-mentioned plastic material. The thickness of the chromium sulfide base layer 2a is preferably 10 nm or more, particularly preferably 15 to 35 nm. When the film thickness of the chromium sulfide base layer 2a is less than 10 nm,
Insufficient adhesion. The reflective layer 3a made of silver formed on the chromium sulfide base layer 2a preferably has a thickness of 45 nm or more, particularly preferably 100 to 200 nm.
If the film thickness is less than 45 nm, complete reflection will not occur,
This is not preferable because it becomes a half mirror. The protective layer ( ) 4a formed on the reflective layer 3a made of silver is made of chromium sulfide in order to prevent sulfur ions from entering the reflective layer 3a. The protective layer ( ) 4a preferably has a thickness of 1 to 10 nm, particularly preferably 2 to 5 nm. If the film thickness is 11 nm or more, chromium sulfide has absorptive properties, resulting in a decrease in reflectance in the visible range, which is not preferable. Finally, in this example, 400 Adds reflection enhancement in the ~450nm wavelength range. For this purpose, the protective layer ( ) formed on the protective layer ( ) 4a is preferably formed of an aluminum oxide layer 5a (refractive index=1.63) and a zirconium oxide layer 6a (refractive index=1.95). The thickness of the aluminum oxide layer 5a is preferably 45 to 90 nm, particularly 60 to 70 nm. Moreover, the film thickness of the zirconium oxide layer 6a is 40~
Preferably it is 70 nm, especially 50-60 nm. The present invention will be explained in more detail with reference to the following examples. Example 1 In order to create a high surface reflection mirror having the configuration shown in FIG. 1, first, a layer of chromium sulfide was formed to a thickness of 15 nm on a substrate 1a made of polycarbonate by vacuum evaporation, and a chromium sulfide base layer was formed. It was set as 2a.
A reflective layer 3a made of silver and having a thickness of 100 nm was formed as a reflective material on this chromium sulfide base layer 2a by vacuum evaporation. Further, a protective layer 4a made of chromium sulfide and having a thickness of 3 nm was formed on the reflective layer 3a by vacuum evaporation. Furthermore, on the protective layer ( ) 4a,
As a protective layer (), an aluminum oxide layer 5a with a thickness of 66 nm and a zirconium oxide layer 6a with a thickness of 55 nm are used.
and were sequentially formed by vacuum evaporation to form a high surface reflection mirror. Comparative Example 1 In order to create a high surface reflection mirror with the configuration shown in Figure 2, a layer of chromium sulfide was first formed on a substrate 1h of polycarbonate to a thickness of 15 nm by vacuum evaporation, and then a chromium sulfide base layer was formed. It was set to 2 hours.
A reflective layer 3h made of silver and having a thickness of 100 nm was formed as a reflective material on this chromium sulfide base layer 2h by vacuum evaporation. Furthermore, as a protective layer, a reflective layer 3h
On top is an aluminum oxide layer 5h with a thickness of 66 nm and a film thickness of 66 nm.
A 55 nm zirconium oxide layer 6h was sequentially formed by vacuum evaporation to form a high surface reflection mirror. Comparative Example 2 In order to create a high surface reflection mirror with a four-layer structure as shown in FIG. 3, a base layer 2e made of aluminum oxide with a thickness of 30 nm was formed on a substrate 1e made of polycarbonate by vacuum evaporation. , a reflective layer 3e made of silver with a film thickness of 100 nm is formed on this base layer 2e by a vacuum evaporation method, and a reflective layer 3e is further formed on the base layer 2e.
As protective layers on e, an aluminum oxide layer 4e with a thickness of 30 nm and a silicon dioxide layer 5e with a thickness of 100 nm are formed.
were sequentially formed by a vacuum evaporation method. Comparative Example 3 In Fig. 4, copper is deposited on a substrate 1f made of polycarbonate using a vacuum evaporation method.
It was formed to have a thickness of 40 nm and was used as the base layer 2f. A reflective layer 3f made of silver with a thickness of 100 nm is formed on the base layer 2f as a reflective material by vacuum evaporation, and an aluminum oxide layer 4f with a thickness of 60 nm and an aluminum oxide layer 4f with a thickness of 75 nm are further formed on the reflective layer 3f as protective layers. a tantalum oxide layer 5f, a silicon dioxide layer 6f with a film thickness of 60 nm,
A tantalum oxide layer 7f having a thickness of 75 nm was successively formed by vacuum evaporation. The high surface reflection mirrors of Example 1 and Comparative Examples 1 to 3 were each left in a constant temperature room with a temperature of 40 ° C. and a humidity of 95% RH, and a peel test with cellophane tape was performed every 24 hours until 216 hours had passed. A moisture resistance test was conducted. In consideration of actual use, the time required for peeling is preferably 200 hours or more. The results are shown in Table 1.

[Table] Furthermore, regarding the high surface reflection mirror of Example 1, the spectral reflectance with respect to incident light at 45° was measured before and after the above moisture resistance test. The results are shown in Figure 5. According to the results, in Example 1, the spectral reflectance of 45° incident light hardly changed before and after the humidity test, and even after the humidity test, the spectral reflectance of the 45° incident light
More than 92% in the visible range of 700nm, wavelength 450~
A high reflectance of over 94% was obtained in the 700 nm region. Further, in the visible wavelength range of 430 to 700 nm, the rate of change in reflectance itself was 1%, and good results were obtained. Also, from the measurement results in Figure 5, the CIE (International Commission on Illumination) chromaticity coordinates are determined: x=0.3350, y=
0.3368, dominant wavelength 569.7nm, excitation purity 1.56%,
Since the luminous reflectance was 97% and the stimulus purity was 1.56%, it can be said that a nearly neutral reflective color tone was obtained. Furthermore, regarding the high surface reflectance mirrors of Example 1 and Comparative Example 1, the high surface reflectance mirrors of this example were installed 100 nm above the liquid level of a 10 wt% (NH ₄ ) ₂ S aqueous solution, and after 4 hours had elapsed. Later surface state change and wavelength
A sulfidation resistance test was conducted to examine changes in reflectance at 400 nm. The results are shown in Table 2.

〔Effect of the invention〕

As detailed above, in the high surface reflection mirror of the present invention, a chromium sulfide base layer is formed between the substrate and the silver reflective layer, and a chromium sulfide protective layer () is formed on the silver reflective layer. is formed. This strengthens the adhesion between the substrate and the reflective layer made of silver, and also prevents sulfur ions from entering the reflective layer. Therefore, the substrate is polycarbonate,
Even when it is made of plastic such as acrylic resin, it has excellent film adhesion, moisture resistance, sulfidation resistance, etc. Although the case where the reflective mirror is formed on a plastic substrate has been described above, the present invention is not limited thereto, and good effects can also be achieved when the reflective mirror is formed on a glass substrate.

[Brief explanation of drawings]

1 is a sectional view showing a high surface reflection mirror according to an embodiment of the present invention, FIG. 2 is a sectional view showing a high surface reflection mirror of Comparative Example 1, and FIG. 3 is a sectional view showing a surface high reflection mirror of Comparative Example 2. 4 is a sectional view showing a high surface reflection mirror of Comparative Example 3, and FIG. 5 is a sectional view showing a high surface reflection mirror according to an example of the present invention. 2 is a graph showing the spectral reflectance of 45° incident light before and after a stability test. 1a, 1e, 1f, 1h...Substrate, 2a, 2h
...Chromium sulfide base layer, 2e...Aluminum oxide base layer, 2f...Copper base layer, 3a, 3e, 3
f, 3h... Reflective layer, 4a... Protective layer (), 5
a, 6a...protective layer (), 4e, 4f, 5e,
5f, 5h, 6f, 6h, 7f...protective layer.

Claims (1)

[Claims] 1. A high surface reflection mirror comprising: (a) a base layer made of chromium sulfide formed on the substrate surface; (b) a reflective layer made of silver formed on the chromium sulfide base layer; , (c) a protective layer () made of chromium sulfide formed on the reflective layer; and (d) a protective layer () formed on the protective layer (). mirror. 2. The high surface reflection mirror according to claim 1, wherein the protective layer ( ) is formed of a transparent material multilayer film having at least an aluminum oxide layer and a zirconium oxide layer. 3. The surface high reflection mirror according to claim 2, wherein the chromium sulfide base layer has a thickness of 10 nm or more, the reflective layer made of silver has a thickness of 45 nm or more, and the protective layer () made of chromium sulfide has a thickness of 45 nm or more. Film thickness 1~
10 nm, and the protective layer () has a film thickness of 45 to 90 nm.
1. A high surface reflection mirror characterized by being formed of an aluminum oxide layer and a zirconium oxide layer with a thickness of 40 to 70 nm.