JP4119959B2 - Method for forming transparent protective film on colored film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a transparent protective film on a novel colored film such as purple or black.
[0002]
[Prior art]
In the precious metal jewelry industry, there is an urgent need to develop new products that meet consumer needs. At present, precious metal materials for decoration use gold, platinum, etc. due to the increase in real intentions, but these materials are limited to K18 golden and platinum white as colored metals. In the situation of individualization and differentiation, there is a limit in design.
[0003]
Therefore, it is possible to develop an original product by making use of the characteristics of the material and forming a new colored film without impairing the quality as a noble metal. As an example, a means has been developed in which aluminum is vapor-deposited on a gold product as shown in Japanese Patent Laid-Open No. 60-5872 and purple AuAl ₂ is produced by thermal diffusion at 600 ° C.
[0004]
However, in the conventional example and the material is limited to gold products, the thermal diffusion of gold and aluminum, purple AuAl ₂ non AuAl, by the formation of intermetallic compounds such as Au ₂ Al, suppressed tone of colored film There was a drawback of being able to.
[0005]
Furthermore, the above-mentioned vapor-deposited film has a problem in durability, has not yet been put into practical use, and is not a product.
[0006]
[Problems to be solved by the invention]
Accordingly, the present inventors have made extensive studies on a technique for forming a colored film by an ion plating method that has excellent adhesion and can form a hard film.
[0007]
As a result of various experiments using gold-aluminum alloy as an evaporation material, it has become possible to obtain reproducible formation conditions for a purple-colored film. The colored film consisting of has a problem that it is discolored within one hour in the artificial sweat test.
[0008]
On the other hand, various materials are used as transparent protective films for optics such as eyeglass lenses and camera lenses. However, a so-called durability that does not change color while having high hardness is indispensable as a coating for jewelry. In that respect, the transparent protective film with a film thickness of less than about 1 μm, which is usually used for the above-mentioned optics, causes discoloration of the purple colored film due to sweat or the like when used as an accessory. There was a drawback.
[0009]
Therefore, according to the method of forming a transparent protective film on the colored film of the present invention, a product having a bright purple colored film can be obtained by using a gold-aluminum alloy as an evaporation metal. The present invention seeks to provide a precious metal jewelry that is excellent in commercial value and has no drawbacks such as peeling or discoloration.
[0010]
[Means for Solving the Problems]
That is, in the method for forming a transparent protective film on the colored film of the present invention, the film thickness of the first layer is set to about 2 to 4 μm by the ion plating method in order to improve the corrosion resistance of the purple colored film made of a gold-aluminum alloy . A transparent protective film having a two-layer structure of aluminum oxide (Al ₂ O ₃ ) and silica (SiO ₂ ) having a thickness of about 1 to 1.6 μm is sequentially formed on the second layer. .
[0011]
The gold-aluminum alloy that can be suitably used in the present invention is preferably an alloy mainly composed of gold of about 80% gold and about 20% aluminum.
[0012]
Since the method for forming the transparent protective film on the colored film of the present invention is configured as described above, the noble metal jewelry formed with the obtained colored film has a bright purple color, and a new and highly decorative noble metal jewelry is obtained. It became possible to provide.
[0013]
Further, since the method for forming a transparent protective film on the colored film of the present invention is constituted as described above, a practically sufficient durable film can be obtained. In addition, the obtained film has a smooth and dense structure, and it is possible to obtain a product excellent in commercial value without defects such as rough skin and pinholes.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a method for forming a transparent protective film on a colored film of the present invention will be described in detail.
[0015]
【Example】
FIG. 1 shows an example of a noble metal jewelry having a colored film to be obtained by the present invention, and shows a ring having two colors. A light colored portion 2 on the surface of the ring 1 indicates gold, and a dark colored portion 3 indicates a noble metal having a purple film obtained by the present invention.
[0016]
The vapor deposition conditions for film formation are shown below.
(Deposition conditions)
Evaporated metal Au 99.99%, Al 99.99%
Substrate temperature 250 ° C
Temperature control time 30min
Jig rotation speed 10rpm
RF 250W
Bias 2000V
Argon pressure 2 × 10 ^-2 Pa
In that case, it experimented with the various evaporation material which changed the gold content of the gold aluminum alloy.
(Substrate sample)
50 × 100 × 0.2mm buffed brass plate (6.4 brass), surface roughness Ra = 0.03μm
40 × 100 × 2mm of glass plate
Each of these was degreased by alkaline degreasing by ultrasonic cleaning and acetone degreasing by the same cleaning, and dried.
(Evaporation material)
A: AuAl ₂ (78% Au)
B: Au75 / Al25
C: Au78 / Al22
D: Au80 / Al20
E: Au85 / Al15
F: Au90 / Al10
Vapor deposition was performed for 5 minutes under the above conditions, and the formed film was measured by spectral reflectance (by ICP emission spectroscopic analyzer ICPS-1000II manufactured by Shimadzu Corporation) and color coordinates. The results are shown in the graph of FIG.
[0017]
The known purple gold-aluminum alloy material A has light absorption near 550 nm and has a purple surface. On the other hand, the film formed by changing the composition of the gold-aluminum alloy has absorption near 550 nm when the gold content is 80% (D) to 85% (E), and has a color tone close to purple of the known purple gold-aluminum alloy material A. It was. Gold 75% (B) and 78% (C) had a white surface close to aluminum, and gold 90% (F) had a yellow film close to gold.
(Change of film due to evaporation time) The thickness of the film is less than 0.1 μm in practical use. Therefore, it was decided to look at the change in the film over time.
[0018]
a: 1 min
b: 8min
c: 13 min
d: 20 min
The film formed by time change was measured by spectral reflectance and color coordinates. The results are shown in the graph of FIG.
[0019]
As described above, as the deposition time passed 1 minute, 8 minutes, 13 minutes, and 20 minutes (the film thickness increased), the surface color changed and changed from white to purple to gray. This is due to the increased gold content on the surface due to the progress of evaporation. That is, when the composition of gold aluminum in the film deposited on the glass plate was analyzed by ICP, the gold content was 42% (a), 68% (b), 73.6% (c), 79.7% ( d). As a result, the deposition of the alloy material needs to be sufficiently considered because the deposition time greatly affects the film formation. Therefore, the deposition time of this alloy was set to about 13 minutes since the purple color became vivid for 8 minutes (b) to 13 minutes (c).
(Bias voltage) Evaporating conditions for film formation include factors such as electron beam current, bias voltage, and high-frequency output for sample dissolution. The electron beam current for melting the gold-aluminum alloy started at 200 mA, and at 400 mA, the output of the electron beam was too high and the temperature was too high. The high-frequency type ion plating may have an influence on the substrate current by applying a bias voltage or changing the high-frequency output due to its structure. Therefore, the relationship between the high-frequency output and the bias voltage and current when an 80% gold alloy was deposited on the evaporation material was examined. The result is shown in FIG.
[0020]
The bias current is increased by increasing the high-frequency output (150 to 300 W) and the bias voltage (500 to 2000 V). From this result, it is considered that by increasing the high frequency output and the bias voltage, the ionized particles are strongly struck on the substrate, and a denser film is formed.
[0021]
In view of the above results, increasing the bias voltage may cause the film to become denser, so the bias voltage was changed and the influence on the film was investigated. That is, under the above evaporation conditions, a bias voltage was applied from 1000 V to 2000 V to form a deposited film for 13 minutes, and the spectral reflectance of the film was measured. The result is shown in FIG.
[0022]
X: 1000V
Y: 1500V
Z: 2000V
As the bias voltage is increased in this way, the color tone is not changed, but the reflectance is improved and the vividness of the color is increased.
(High-frequency output) Under the above evaporation conditions, the high-frequency output was changed to 150 W and 250 W, and the spectral reflectance was measured for the film in the deposition for 13 minutes. The result is shown in FIG.
[0023]
A ₁ : 250W
A _2: 150W
As described above, by increasing the output to 250 W (A ₁ ), the color tone of the purple film was not changed, but the reflectance was improved as compared with 150 W (A ₂ ).
(Formation of transparent protective film)
After the formation of the colored film is completed, a transparent protective film of aluminum oxide (Al ₂ O ₃ alumina) is formed by reactive ion plating using aluminum as an evaporation material and oxygen gas as an ionization reaction gas. In the same manner, a transparent protective film of silica (SiO ₂ ) was formed.
[0024]
The conditions for forming the aluminum oxide and silica transparent protective film were as follows.
(Deposition conditions)
Vapor deposition material Aluminum oxide (Al ₂ O ₃ )
Silica (SiO ₂ )
Substrate material Optical glass (BK7)
Substrate temperature 200 ° C
High frequency power 0W, 150W, 300W
Bias voltage 0V, -500W
Gas pressure (O ₂ ) 8 × 10 ^-2 Pa
Deposition rate 100nm / min
The coating was formed using a high-frequency ion plating apparatus shown in FIG. Aluminum oxide (Al ₂ O ₃ ) and silica (SiO ₂ ) were used as the evaporation material, and optical glass (BK7) was used as the substrate material. The corrosion resistance evaluation was performed by immersing a sample in which a film made of a gold-aluminum alloy material was formed on a glass substrate and a transparent film was formed thereon on the following artificial sweat test solution.
(Artificial sweat test solution)
Sodium chloride 9.9 g / l
Sodium sulfide 0.8g / l
Urea 1.7 g / l
Lactic acid 1.1ml / l
Ammonia water 0.28ml / l
pH 4-6
Temperature 40 ± 1 ° C. For 24 hours, a colorimeter was used for measuring the color tone, SEM was used for observing the film surface and cross section, and XRD and XPS were used for structural analysis and surface analysis of the transparent film. The adhesion of the film was evaluated by a scratch test.
(Test results) Aluminum oxide and silica film formed at a substrate temperature of 200 ° C. were both amorphous and columnar transparent films. Silica generated internal stress as the film thickness increased, and cracking was observed at 1.7 μm. On the other hand, peeling of the aluminum oxide was not recognized even when the film thickness was 4.0 μm.
[0025]
The substrate temperature during film formation is preferably about 200 ° C., and in the case of film formation at a high temperature of about 600 to 800 ° C., there is a difference in expansion coefficient due to melting, discoloration, and temperature change in the brazing portion of the jewelry. There may be problems such as the occurrence of cracks due to an increase in stress.
[0026]
The corrosion resistance by the artificial sweat test is improved depending on the film thickness as shown in the results of FIG. When the film thickness is less than that of the antireflection film (less than 1 μm), the corrosion resistance effect of the transparent film is small, and a film thickness of 3 μm or more is required for aluminum oxide.
[0027]
With respect to the peel strength of the transparent film, when the film was formed under the conditions shown in FIG. 9 (high frequency power), 350 g of aluminum oxide and 400 g of silica were excellent in silica.
[0028]
The color tone of the sample in which the first layer of aluminum oxide (3.6 μm) and the second layer of SiO ₂ (0.9 μm) are formed on a gold-aluminum alloy material (AuAl ₂ ) film is as follows.
(Influence on color of transparent protective film)
Type of film xy Y
AuAl ₂ 0.330 0.302 27.19
SiO ₂ (0.9 μm) 0.343 0.304 22.27
/ Al ₂ O ₃ (3.6 μm)
Compared to the AuAl ₂ film, the lightness (Y) was lowered, but the chromaticity (x, y) was the same. In addition, the two-layer structure improves adhesion and corrosion resistance compared to the AuAl ₂ single layer film.
[0029]
FIG. 10 shows changes in spectral reflectance characteristics and reflected colors when the thickness of SiO ₂ is 1 μm and the thickness of Al ₂ O ₃ is changed. Similarly, FIG. 11 shows the corrosion resistance test results when the SiO ₂ film thickness is 1 μm and the Al ₂ O ₃ film thickness is changed. As a result, it was found that a product having high value as an accessory can be obtained by setting the first Al ₂ O ₃ layer to about 2 μm or more and the second SiO ₂ layer to about 1 μm or more.
[0030]
The noble metal jewelry formed with the purple film obtained in the above examples has a slightly lower brightness but exhibits a bright purple color, has little change in color tone, and is excellent in peel strength. There was no change over time.
[0031]
【The invention's effect】
Since the method for forming the transparent protective film on the colored film of the present invention is configured as described above, the method for forming the transparent protective film on the obtained colored film exhibits a bright purple color, which is novel and decorative. It became possible to provide high precious metal jewelry.
[0032]
Further, since the method for forming a transparent protective film on the colored film of the present invention is constituted as described above, a practically sufficient durable film can be obtained. In addition, the obtained film has a smooth and dense structure, and it is possible to obtain a product excellent in commercial value without defects such as rough skin and pinholes.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of a method for forming a transparent protective film on a colored film to be obtained in the present invention.
FIG. 2 is a graph showing a result obtained by performing vapor deposition for 5 minutes and measuring the formed film by spectral reflectance and color coordinates.
FIG. 3 is a graph showing a result of measuring a film formed by time change using spectral reflectance and color coordinates.
FIG. 4 is a graph showing the results of investigating the relationship between high-frequency output, bias voltage, and current when an 80% gold alloy is vapor-deposited on the evaporation material.
FIG. 5 is a graph showing the results of measuring the spectral reflectance of a film by applying a bias voltage from 1000 V to 2000 V to form a deposited film for 13 minutes.
FIG. 6 is a graph showing the result of measuring the spectral reflectance of a film formed by vapor deposition for 13 minutes while changing the high frequency output to 150 W and 250 W.
FIG. 7 is a circuit diagram showing a high-frequency ion plating apparatus for forming a film.
FIG. 8 is a graph showing corrosion resistance by artificial sweat test.
FIG. 9 is a graph showing the peel strength of a transparent film.
FIG. 10 is a graph showing changes in spectral reflectance characteristics and reflected color when the film thickness of SiO ₂ is 1 μm and the film thickness of Al ₂ O ₃ is changed.
11 is a graph showing the corrosion resistance test results when the film thickness of SiO ₂ is 1 μm and the film thickness of Al ₂ O ₃ is changed. FIG.
[Explanation of symbols]
1 Ring 2 Light color part 3 Dark color part

Claims (1)

In order to enhance the corrosion resistance of the purple colored film made of a gold-aluminum alloy, aluminum oxide (Al ₂ O ₃ ) having a thickness of 2 to 4 μm is formed on the first layer by an ion plating method, and the film thickness is 1 to 2 on the second layer . A method for forming a transparent protective film on a colored film, comprising sequentially forming a transparent protective film having a two-layer structure of silica (SiO ₂ ) having a thickness of 1.7 μm .

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