JPH0699820B2 - How to form patina - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for stably forming patina with excellent adhesion to a substrate with good productivity.

<Prior art and its problems> The surface of copper used for roofing materials of shrines and Buddhist temples has been affected by oxygen, water vapor, carbon dioxide, sulfides or chlorides in the atmosphere for many years. With elegant and beautiful green patina {CuCO ₃・ Cu (OH) ₂ , CuSO ₄・ 3Cu (OH) ₂ , CuCl ₂・ 3Cu
It is well known that it is covered with (OH) _{2 and} other basic copper salts}, but this patina layer not only produces a profound and distinctive aesthetic, but also acts as an anticorrosion film, and thus patina. A covered copper roof, etc. will show durability for several hundred years.

Therefore, in recent years, "green-blue film-formed products" aiming at corrosion prevention of base materials and decorative or artistic effects by artificially generating natural green-blue in a short period of time have become Since it has also been found in ornaments and the like, there have been many proposals for a means for artificially forming a patina film close to nature.

These conventional artificial patina forming means are roughly classified as follows.

(A) Chemical conversion treatment method in which a chemical solution is contacted (for example, Japanese Patent Publication No. 57-
51468), and (B) a method of electrolytically treating in a chemical solution (for example, Japanese Patent Publication No. 55-12).
No. 117), (C) a chemical conversion treatment of a substrate, and then further coating (for example, the method proposed as JP-A-55-8491), (D) green A method of coating with a paint containing a blue-forming substance (for example, a method proposed in Japanese Patent Laid-Open No. 55-139467), (E) Adhesive of copper or copper alloy powder to the surface of a copper plate roughened by sandblasting And then applying an artificial patina generating solution such as ammonium chloride or ammonium sulfate (for example, the method proposed as Japanese Patent Publication No. 57-52425).

However, the above-mentioned artificial patina forming means is actually a) the patina generation rate is slow, b) the patina coating easily peels off, and the manufacturing facility is expensive, and c) the patina is stably formed. However, there are problems such as non-uniformity and poor color tone, d) poor adhesion of patina, e) a lot of man-hours for forming patina coating, and poor productivity. Moreover, in general, the base material is generally limited to copper or a copper alloy, and sufficient adhesion with the base material cannot be maintained unless the generated patina surface is protected by painting or the like. It also had the problem of. Moreover, the protection of patina from the paint film cannot be a fundamental solution to the above problem because the coating film composition is deteriorated by ultraviolet rays.

Therefore, the object of the present invention is to establish "a means capable of stably forming a patina film of uniform color tone having excellent adhesion in a short time regardless of the type of the base material". Was that.

(Means for Solving the Problems) The inventors of the present invention have conducted extensive studies from various viewpoints in order to achieve the above-mentioned object, and as a result, "the surface of the base material on which patina is formed is roughened if necessary. When a thin film made of copper or a copper alloy is formed on the surface of the base material after the surface is made flat, and then the thin film is subjected to a chemical conversion treatment and then a forced oxidation treatment is combined, the material is not affected by the material of the base material. It is possible to form a patina film of uniform color tone with excellent adhesion on the surface in a short time. "

The present invention has been made based on the above findings and the like, "After forming a thin film made of copper or a copper alloy on the surface of a base material to be formed patina, the thin film is subjected to chemical conversion treatment, followed by By performing forced oxidation treatment, it is possible to stably form patina with good appearance and excellent adhesion in a short time. ”

Here, the "base material for forming patina" is not only a metal material typified by copper or a copper alloy, but also a ceramic,
It does not matter whether it is roof tile, wood, synthetic resin, etc., and its material is not particularly limited.

Hereinafter, the present invention will be described in more detail and concretely together with its action and effect.

In the patina forming method according to the present invention, first, a "thin film made of copper or copper alloy" is formed on the surface of the base material. Although the thickness of the thin film is not particularly limited, it is usually 1 to 100 μm.
m, preferably about 5 to 40 μm. Of course, even if the film thickness is less than 1 μm, it is possible to form patina, but this is not preferable because cracks and the like are likely to occur in the thin film. On the other hand, when the film thickness exceeds 100 μm, it becomes difficult to obtain a satisfactory color tone, and it is not preferable in terms of production cost.

As the means for forming the above "thin film made of copper or copper alloy", known methods such as plating method, vacuum deposition method, sputtering method, ion plating method, and thermal spraying method can be applied. Therefore, it is necessary to select an appropriate thin film forming means according to the type of base material, etc., but it is a dry process, the processing is quick, a wide range of materials can be used, and there is a great adverse effect on the materials. It can be said that the "spraying method" which does not give the above is the most preferable means.

By the way, "flame spraying" and "arc spraying" are used for the spraying method.
There are various methods such as "plasma spraying", and it is known that powder or wire made of copper or copper alloy can be used as a spraying raw material, but in the present invention, there are special restrictions on the spraying method and the spraying raw material. There is no. However, even if the same material and the same equipment are used, different coatings will be formed if the method of thermal spraying (that is, the thermal spraying conditions) is different, so caution is required in this respect. For example, atmospheric conditions (oxygen-
The mixing ratio of acetylene, etc.), spraying distance, wire feed rate, etc. sensitively affect the hardness of the sprayed coating. In addition, the relative speed of the spray gun and the work piece, the film thickness per pass, the temperature of the work piece during thermal spraying (it is preferable to preheat the substrate to an appropriate temperature to increase the adhesion strength of the film) ), The factors such as the pressure and flow rate of gas and air that affect the characteristics of the thermal spray coating are very numerous.

In addition, it is generally said that "the sprayed coating has a large number of thin layers" even if the thermal sprayed coating has the same thickness as "the strength is stronger than that of a small number of thick layers". Need to consider. Also, increasing the spray thickness per pass causes overheating, so in the case of inner diameter spraying, in order to avoid overheating, the relative speed of the spray gun and the workpiece should be increased to increase the film thickness per pass. Special care should also be taken to reduce the thickness.

As described above, when forming a "thin film made of copper or copper alloy" by thermal spraying, it is necessary to appropriately select the thermal spraying conditions, etc., depending on the type of base material, the thickness of the thermal spray coating, the desired surface roughness, etc. There is.

On the other hand, "copper or copper alloy thin film" is formed by plating method, etc.
In the case of forming, the object can be achieved relatively stably by simply applying the known electrolytic solution composition, electrolysis conditions and the like.

The surface roughness of the “thin film made of copper or copper alloy” thus formed is not particularly limited, but if the surface roughness of the thin film is less than 3 μm, the degree of patina coloring is low,
On the other hand, if it exceeds 50 μm, the adhesion strength between the base material and the thin film tends to decrease, so that it is usually 3 to 50 μm, preferably 5 to 40 μm.

By the way, "a thin film made of copper or copper alloy" on the surface of the substrate
Roughening the surface of the base material prior to the formation of the base material improves the adhesion between the base material and the "thin film made of copper or copper alloy", and thus improves the adhesion of the patina film formed. It is extremely preferable. Therefore, before the thin film forming treatment of copper or copper alloy, the roughening treatment of the base material surface is performed as necessary to uniformly roughen the base material surface and temporarily activate the surface. Is planned.

As a method of roughening the surface of the base material, generally, two types are known, a chemical method (including an electrochemical method) and a physical method (mechanical method). Examples of the former are "method of immersing in acid or alkali (that is, etching treatment method)" and "electrolysis method", and examples of the latter are "blast method",
"Water jet method", "Power tool method", "Hand tool method"
Etc. can be mentioned. Therefore, when roughening the base material prior to forming the "copper or copper alloy thin film" according to the present invention, a roughening method is used depending on the type of the base material and the desired surface roughness of the green-blue formed product. Should be selected appropriately. For example, when the base material is a metal material, the surface of the base material can be roughened with high efficiency, and at the same time, rust and other corrosion products generated on the surface of the base material can be removed. It can be said that the “blast method” is suitable. Moreover, in the blast method, abrasives having various hardnesses and particle sizes such as silica sand, steel grid, steel shot, fused alumina (artificial corundum), alundum, carborundum, glass beads, and synthetic resin particles are used. Therefore, in addition to being able to appropriately select a suitable one according to the type of the substrate and the like, there is also an advantage that the surface roughness can be adjusted by the blast condition.

It should be noted that the blast method is classified according to various viewpoints. For example, from the viewpoint of an abrasive material spraying method, it can be classified into a “blast method using compressed air” and a “blast method using centrifugal force”. Further, depending on the dry and wet state of the abrasive to be sprayed, it can be classified into a "dry method" and a "wet method", but in the present invention, there is no particular limitation on the type or combination thereof.

The surface roughness of the substrate after the surface roughening treatment is 3 μm or more, preferably 10 to 30 μm. This is because if the surface roughness is less than 3 μm, the effect of improving the adhesion with the “thin film made of copper or copper alloy” is not remarkable. On the other hand, when the surface roughness exceeds 50 μm, the adhesion is good, but the strain generated in the base material (base material) becomes a problem, which is not realistic.

Now, in the present invention, after the "thin film made of copper or copper alloy" is formed on the surface of the substrate, the thin film is subjected to chemical conversion treatment.

Generally, "chemical conversion treatment" causes a metal to chemically react with a corrosive liquid (chemical conversion treatment liquid) adjusted to specific conditions to form a water-insoluble corrosion product layer adhered to the surface of the metal. The term "treatment" refers to the application of rust-prevention, coating base, lubrication base for plastic working, etc. by utilizing the physical or chemical properties of the corrosion product.

The chemical conversion treatment referred to in the present invention has almost the same concept. However, it can be said that the concept is different from the point that the forced oxidation treatment is performed after the chemical conversion treatment.

The chemical conversion treatment liquid used in the present invention does not matter as long as it forms a water-insoluble corrosion product layer on the surface of copper or a copper alloy. And as something like this,
Conventionally, solutions containing ammonium salts, hydrochloric acid, caustic soda, sulfides, sulfates, nitrates, acetates, carbonates, bicarbonates, alums, etc., and combinations of these (so-called artificial patina generating solution) Of course,
The solvent is not limited to water), but the following chemical conversion treatment liquid can be mentioned as a more specific example.

a) Aqueous solution of hydrochloric acid, nitric acid and ammonium sulfate with an alkali metal chloride and / or alkaline earth metal chloride added, b) Aqueous solution with cupric chloride added, c) Alkali metal chloride and / or alkaline earth metal Treatment with an aqueous solution of chloride (eg, NaCl, KCl, NH ₄ Cl, etc.) with copper sulfate added (in this case, an aqueous solution containing an alkali metal chloride and / or an alkaline earth metal chloride, followed by copper sulfate Similar results can be obtained by a two-step treatment of treating with an aqueous solution containing the same or a two-step treatment in which the order is the reverse of this).

As described above, in the present invention, there is no particular limitation on the type of chemical conversion treatment liquid, and these chemical conversion treatment liquids (the active ingredient concentration is not particularly limited, but usually 5 to 50% by weight, preferably 20 to (30% by weight) is applied to a "thin film made of copper or copper alloy", sprayed, or the like, or the thin film is immersed in the chemical conversion treatment solution.

This chemical conversion treatment forms a water-insoluble corrosion product layer on the "copper or copper alloy thin film". The corrosion product layer contains Cu, Cu ₂ O, CuO or Cu (OH) ₂ , CuCl, CuCl ₂ etc. may coexist in a complicated manner.

In this case, if the "thin film made of copper or copper alloy" is formed by thermal spraying, a chemical reaction is likely to occur, and better results can be obtained. This is because the thermal spray coating is a laminate of particles that have been rapidly cooled from high temperature and have collided with the surface of the base material, with residual stress due to thermal strain, oxides, and pores intervening. It is thought that it is because.

Next, the "thin film made of copper or copper alloy" which has been subjected to the chemical conversion treatment as described above is subjected to forced oxidation treatment to form a patina having excellent adhesion.

As a method of forced oxidation, "method of using oxidizing liquid",
There are “method using an oxidizing gas” and “method by electrolysis”, but it can be said that the “method using a gas” is preferable in consideration of easy handling of the base material and adhesion of patina.

Air and oxygen gas are generally used as the oxidizing gas, but ozone (O ₃ ) is the most preferable when considering the processing speed (that is, the formation rate of patina). The method of exposure to water is recommended. In this case, the ozone concentration is not particularly limited, and it is sufficient that ozone is mixed into the atmosphere by a normal ozone generator.

When the chemical conversion treated "copper or copper alloy thin film" is forcibly oxidized by ozone, the forced oxidation treatment may be performed before the chemical conversion treatment film formed by the chemical conversion treatment is dried. desirable. That is, when the chemical conversion treatment film is sufficiently oxidized (preferably immediately after chemical conversion treatment) in an ozone-containing atmosphere in the presence of sufficient moisture (moisture), a patina film having excellent adhesion is formed in a shorter time. be able to.

The formation mechanism of patina due to the "forced oxidation of the chemical conversion treated copper or copper alloy thin film" has not been clarified at present, but the patina produced by this treatment is chemically stable by X-ray diffraction cupric chloride {CuCl ₂ · 3Cu
(OH) ₂ } has been confirmed.

The forced oxidation treatment time of the chemical conversion treated copper or copper alloy thin film is
When ozone treatment (exposure to ozone-containing atmosphere) is taken as an example, it usually varies from about 10 to 60 if a commercially available ozone generator is used, although it depends on the ozone concentration and the amount of ozone-containing gas.
Minutes are enough. However, since the surface color changes in about 10 seconds with the treatment using a commercially available ozone generator,
It is considered that the reaction starts within this time.

After the forced oxidation treatment is completed, the substrate on which patina is formed is preferably subjected to curing that also serves as drying. In this curing, it is not particularly necessary to heat, and it is usually sufficient to carry out at room temperature for 2 to 24 hours.

In this way, it is possible to form a patina of uniform color tone with extremely excellent adhesion in a short time.

Next, the present invention will be described more specifically by way of examples.

<Example> Example 1 First, a degreased copper plate (360 mm width x 360 mm length x 0.3 mm) was preliminarily degreased.
(Thickness) was prepared and the surface of the copper plate was roughened by spray blasting using an alundum powder having a particle size of # 50 to # 250 at an air pressure of 1.5 to 5 kg / cm ² (gauge pressure).

Next, using a copper wire on the roughened surface of the copper plate, the thickness is 25 μm.
Sprayed film (copper) was formed.

The spraying conditions at this time are as follows: Spraying method: arc spraying (using a Metco 4RC type machine), spraying distance: 150 mm ± 80 mm, spraying gun speed: 40 m / min, pitch: 20-30 mm, working voltage: 35 V , Working current: 50A, Air gap: Fine, Air pressure: 80psi (5.6kg / cm ² ), Copper wire: 1.6mmφ × 2 pcs.

Then, cupric chloride 30 which is a chemical conversion treatment liquid on the copper sprayed film
Apply a weight% aqueous solution uniformly with a brush to perform chemical conversion treatment, and while the resulting film contains sufficient moisture, load it into an ozone oxidation box (0.2 m ³ ) and use an ozone generator {Koyotex Co., Ltd. ) Made by KW-701, O ₃ generation rate: about 9g / h
r}, ozone-containing air was blown in at a rate of 3 l / min for 15 minutes.

After this forced oxidation treatment, the copper plate on which patina was formed was taken out from the ozone oxidation box and cured for 8 hours at room temperature, which also served as drying.

Then, “pale blue formed by the method of the present invention described above”,
"Natural patina over 30 years", "commercial artificial patina"
Also, the state of each patina surface of "commercial artificial patina slate" was observed by SEM (scanning electron microscope).

This SEM observation photograph is shown in FIGS.

As is clear from the comparison of FIGS. 1 to 4, it was found that the patina formed by the method of the present invention is very similar in shape and particle size to the natural patina.

In addition, the patina formed by the method of the present invention exhibits a solid bluish green color tone, and even if the patina film is rubbed with a fingertip, no peeled substance is generated at all, and it is as excellent as or better than natural patina. It was confirmed that it had good adhesion.

Further, it was also confirmed by analysis by X-ray diffraction that the patina formed by the method of the present invention was basic cupric chloride {CuCl ₂ .3Cu (OH) ₂ } which is the main component of natural patina.

Moreover, SEM observations were carried out on the cross sections of "green patina formed by the method of the present invention" and "natural patina," respectively. As a result of the method of the present invention, as shown in FIG. Almost the entire cross section of the sprayed film that digs into the surface turned patina and firmly adhered to the base material, and it was clearly observed that fine pores were present in the sprayed film (patinated). , The natural patina shown in FIG. 6 was found to be very similar in structure, appearance and compactness.

Example 2 Similar to Example 1 except that the chemical conversion treatment was carried out in two steps, namely, contacting with an aqueous solution containing 10% by weight of sodium chloride (NaCl) and then contacting with an aqueous solution containing 20% by weight of copper sulfate. The formation of patina was carried out by the method.

The patina film thus obtained was uniform and had extremely excellent adhesion with no peeling.

In addition to these examples, various methods other than the thermal spraying method for forming a copper or copper alloy thin film, or various known chemical conversion treatment liquids (including those called artificial patina generation liquid), and as a forced oxidation means Tests in which various methods of applying various oxidizing liquids and oxidizing gases were combined in various ways, and it was confirmed that good results could be obtained in almost the same manner as in the above-mentioned Examples according to the method of the present invention.

<Summary of Effects> As described above, according to the present invention, it is possible to obtain patina having almost the same solid color tone as that of natural patina and having extremely excellent adhesion without any special equipment. It can be stably formed on a base material in a short time, and it can contribute to the concept expansion of creative ideas in a wide range of fields such as roofing materials as well as interior wall materials and decorations. This brings about a very useful effect.

[Brief description of drawings]

FIG. 1 is a photograph of a metal structure by a scanning electron microscope (magnification: about 8000 times) showing the state of the surface of “green-blue formed by the method of the present invention”. Figure 2 is a scanning electron microscope photograph of the metal structure showing the surface of the natural patina after 30 years (magnification: approx. 80
00 times). Fig. 3 is a photograph of a metal structure by a scanning electron microscope showing the condition of the surface of the "commercial artificial patina" (magnification: about 8000).
Times). FIG. 4 is a photograph of a metal structure by a scanning electron microscope showing the condition of the surface of the “commercial artificial green-blue slate” (magnification:
About 8,000 times). FIG. 5 is a metallographic photograph of a scanning electron microscope (magnification: about 300 times) showing a cross-sectional state of "green-blue formed by the method of the present invention". Figure 6 is a photograph of the metallographic structure of a natural patina with a scanning electron microscope showing the cross section of natural patina over 30 years (magnification: about 36
0 times).

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideo Tamanoi 2-10-1 Toranomon, Minato-ku, Tokyo Within Japan Mining Co., Ltd. (72) Inventor Minoru Sugiyama 1-2-7-2, Nishigotanda, Shinagawa-ku, Tokyo Koyo Construction Industry Co., Ltd. (72) Inventor Shingo Odawara 852 Imazu Asayama, Ichihara City, Chiba Prefecture Koyo Construction Industry Co., Ltd. Chiba Works (72) Inventor Katsuhito Nakagawa 852 Imazu Asayama City, Ichihara City, Chiba Koyo Construction Industry Co., Ltd. Chiba Works Within

Claims (4)

[Claims] 1. A method for forming patina, which comprises forming a thin film made of copper or a copper alloy on the surface of a base material on which patina is to be formed, subjecting the thin film to chemical conversion treatment, and subsequently subjecting it to forced oxidation treatment. . 2. The method for forming patina according to claim 1, wherein the forced oxidation of the chemical conversion treatment is performed by a treatment of exposing to an atmosphere containing ozone. 3. A surface of a substrate on which patina is formed is roughened, and then a thin film made of copper or a copper alloy is formed.
The method for forming patina according to claim 1 or 2. 4. The method for forming patina according to claim 1, wherein a thin film made of copper or a copper alloy is formed by thermal spraying.