JPH06102837B2 - 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 (O
It is well known that it is covered with a basic copper salt such as (H) ₂ }, but this patina is not only heavy and gives a unique appearance, but also acts as an anticorrosion film. Broken copper roofs will have a durability of 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 It has also been found in ornaments and the like, and there have been many proposals for a means for artificially forming a patina film that is close to natural.

The conventional means for forming artificial patina are roughly as follows.

(A) Chemical conversion treatment method using a chemical solution (for example, Japanese Patent Publication No. 57-5146).
No. 8), (B) Electrolytic treatment in a chemical solution (eg Japanese Patent Publication No. 55-12)
No. 117), (C) a chemical conversion treatment of a base material, and then further coating (for example, the method proposed as JP-A-55-8491), (D) green blue A method of coating with a paint containing a forming substance (for example, a method proposed as JP-A-55-139467), (E) Bonding copper or copper alloy powder with an adhesive to the surface of a copper plate roughened by sandblasting After that, a method of applying an artificial green-blue generating solution such as ammonium chloride or ammonium sulfate (for example, the method proposed as JP-B-57-52425).

However, in practice, the above-mentioned artificial patina forming means is a) the patina generation rate is slow, b) the patina coating is easily peeled 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. Had the problem of. Moreover, the protection of patina from the paint film has not been a fundamental solution because deterioration of the coating composition due to ultraviolet rays occurs.

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 the thin film is subjected to chemical conversion treatment with a specific novel chemical conversion treatment liquid, and then subjected to a treatment of forcibly oxidizing this, the base material It is possible to form a patina film of uniform and solid color tone with excellent adhesion on the surface in a short time without being influenced by the material of the above. "

The present invention has been made based on the above findings and the like. “After forming a thin film of copper or a copper alloy on the surface of a base material on which patina is to be formed, the thin film is subjected to (a) alkaline metal chloride. And / or alkaline earth metal chloride to which aluminum powder is added, (b) aluminum chloride, (c) stannic chloride, (d) zinc chloride, (e) lead chloride, or one or two selected from By performing chemical conversion treatment with a treatment solution containing more than one species, and then forcibly oxidizing this, it is possible to stably form patina with excellent adhesiveness and appearance in a short time. ing.

Here, the "base material for forming patina" includes not only metal materials such as copper and copper alloys but also ceramics,
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 a means for forming the "copper or copper alloy thin film", known methods such as a plating method, a vacuum deposition method, a sputtering method, an ion plating method, and a 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 in order 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". There is a 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, when the "copper or copper alloy thin film" is formed by the plating method or the like, the object can be achieved relatively stably by simply applying the known electrolytic solution composition, electrolysis conditions, etc. .

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, prior to the thin film forming treatment made of copper or copper alloy, roughening treatment of the base material surface is performed as necessary to uniformly roughen the base material surface and temporarily activate the surface. 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 with various hardnesses and particle sizes such as silica sand, steel grid, steel shot, fused alumina (artificial corundum), alundum, carborundum, glass beads, synthetic resin particles, etc. 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, the dry and wet state of the abrasive to be sprayed can be classified into a "dry method" and a "wet method", but in the present invention, there is no particular limitation on the combination of the types.

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.

In the present invention, after a "thin film made of copper or copper alloy" is formed on the surface of a substrate, the thin film is subjected to a chemical conversion treatment using a specific novel chemical conversion treatment liquid which is one of the major features of the present invention. Processing is performed.

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, but is different from the one in which the chemical conversion treatment liquid is usually used, and is also unique in that the forced oxidation treatment is performed after the chemical conversion treatment.

The special chemical conversion treatment liquid used in the present invention is, as described above, (a) alkaline metal chloride and / or alkaline earth metal chloride to which aluminum powder is added, (b) aluminum chloride, (c) chloride chloride. A solution containing one or more selected from ditin, (d) zinc chloride, and (e) lead chloride (the solvent is generally water, but a solvent other than water may be used). In addition, substances such as alum, copper sulphate, and copper nitrate, which are so-called "green-blue generators", may be added to the above, and the present invention includes all of these.
These chemical conversion treatment liquids react with "a thin film made of copper or a copper alloy" to form cuprous chloride (CuCl), or they react with each other on or within the thin film to form chloride. Produces cuprous.

Hereinafter, the chemical conversion treatment according to the present invention will be described in detail with reference to a case where the object to be treated is “a thin film made of copper or a copper alloy formed on the substrate by thermal spraying” and the chemical conversion treatment liquid is “aluminum chloride aqueous solution”. As described above, when a thin film made of copper or a copper alloy is formed by a means other than thermal spraying, or when the chemical conversion treatment solution is the solution of the present invention other than an aluminum chloride aqueous solution, almost the same action and effect are obtained under substantially the same conditions. It has been confirmed that it will be played.

The concentration of aluminum chloride, which is a chemical conversion treatment liquid, is not particularly limited, but is usually 5 to 50% by weight, preferably 20 to
A 30% by weight aqueous solution is used, and the chemical conversion treatment is performed by a method such as coating or spraying this on a "thin film made of copper or copper alloy", or by immersing the thin film in the chemical conversion treatment solution.

When this treatment is performed, the "thin film made of copper or copper alloy" is whitened and gas is generated for a moment.

The mechanism of this reaction has not been clarified at present, but it is presumed that the following reactions are in progress.

a) Aluminum chloride is partially hydrolyzed.

AlCl ₃ + 3H ₂ O = Al (OH) ₃ + 3HCl (1) b) The generated hydrochloric acid reacts with copper or a copper alloy or an oxide formed on the surface.

2Cu + 2HCl = 2CuCl + H ₂ (2) Cu ₂ O + 2HCl = 2CuCl + H ₂ O (3) CuO + 2HCl = CuCl ₂ + H ₂ O (4) c) The generated CuCl partially causes a heterogeneous reaction.

2CuCl = CuCl ₂ + Cu (5) Actually, it is considered that various reactions (for example, the reverse reaction of the formula (4)) occur in addition to the reactions of the above formulas (1) to (5), After all, on the thin film, Cu, Cu ₂ O, CuO or Cu (OH) ₂ , C
It is presumed that uCl, CuCl ₂ , Al (OH) ₃ , and AlCl ₃ coexist in a complicated manner.

The reaction represented by the formula (2) does not occur in a normal state, but in the case of a sprayed coating, etc., it is a laminate of particles that are rapidly cooled from a high temperature and collide with the surface of the base material. It is considered that such a reaction occurs because residual stress, oxides, pores, etc. are present and the electrode potential of the film is more base than that of the same kind material in the normal state. Further, since the generation of gas was observed during the chemical conversion treatment, it can be said that the reaction of formula (2) is very likely to occur.

On the other hand, alkali metal chlorides (eg KCl, NaCl, etc.) and /
Or alkaline earth metal chlorides (eg MgCl ₂ , CaCl ₂ etc.)
In the chemical conversion treatment liquid in which the aluminum powder is added, the reaction of the following formula occurs when the aluminum powder is added.

_{6NaCl + 2Al + 6H 2 O =} 2AlCl 3 + 6NaOH + 3H 2 ... (6) Therefore, then is believed to have occurred substantially the same reaction as in chemical conversion treatment solution of aluminum chloride alone. Further, in this case, there is a possibility that a local battery is formed between aluminum and copper or "a lower oxide of copper" to accelerate the reaction.

Further, in the case of a chemical conversion treatment liquid to which a known patina generating agent such as alum, copper sulfate, copper nitrate or the like is added, a part thereof becomes a sulfate or a nitrate, but it is considered that the essential reaction is almost the same. In addition, alum, copper sulfate,
When copper nitrate or the like is added, the effect of subtly changing the color tone of the patina formed finally (after the forced oxidation treatment) can be obtained, but if it is added in an excessively large amount, the production speed of patina becomes slow. Therefore, in the case of adding the above-mentioned known green-blue generating agent, there is no particular limitation, but the addition amount should be adjusted to 1 to 15% by weight, preferably 1 to 5% by weight.

Next, the "thin film made of copper and copper alloy" that 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 "thin film made of copper or copper alloy" is forcibly oxidized by ozone, the forced oxidation treatment is preferably performed before the chemical conversion treatment film formed by the chemical conversion treatment is dried. 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 · 3C
u (OH) ₂ } has been confirmed. Therefore, it is speculated that the following reactions may be in progress.

B) Cuprous chloride becomes cupric chloride and copper hydroxide by ozone oxidation.

6CuCl + 3H ₂ O + O ₃ = 3CuCl ₂ + 3Cu (OH) ₂ (7) b) Copper and / or copper oxide becomes copper hydroxide by ozone oxidation or hydrolysis.

3Cu + 3H ₂ O + O ₃ = 3Cu (OH) ₂ (8) 3Cu ₂ O + 6H ₂ O + O ₃ = 6Cu (OH) ₂ (9) CuO + H ₂ O = Cu (OH) ₂ (10) c) With cupric chloride Copper hydroxide reacts to form basic cupric chloride (pale blue).

CuCl ₂ ＋ 3Cu (OH) ₂ ＝ CuCl ₂ · 3Cu (OH) ₂ (11) Of course, these reactions are not independent, but proceed in parallel at the same time, and finally they are chemically stable compounds. It is considered to be patina (basic cupric chloride).

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, the copper sprayed film is subjected to a chemical conversion treatment by uniformly applying a 30% by weight aqueous solution of aluminum chloride, which is a chemical conversion treatment liquid, with a brush, and while the product film contains sufficient moisture, an ozone oxidation box (0.2 m ³ ) and put it into an ozone generator (KW-701 model by Koyotex Co., Ltd., O ₃ generation rate: approx. 9 g /
hr} was blown with ozone-containing air 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 the 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. 5, the base material (copper plate) was roughened. Almost the entire cross-sectional area of the sprayed film that digs into the surface has become patina and has a structure that firmly adheres to the base material.
It is clearly recognized that fine pores are present in the thermal spray coating (patinated), and it is very similar in structure, appearance, and compactness to the case of natural patina shown in Fig. 6. understood.

Example 2 A patina was formed in the same manner as in Example 1 except that an aqueous solution of stannic chloride: 12% by weight was used as the chemical conversion treatment solution.

The patina film thus obtained had a strong blue color tone and was a uniform one with excellent exfoliation and excellent adhesion.

Example 3 A patina was formed in the same manner as in Example 1 except that a salt solution (NaCl concentration: 5% by weight) containing 5% by weight of aluminum powder was used as the chemical conversion treatment liquid.

The obtained patina film was uniform and had almost the same color tone as that of natural patina, and had extremely excellent adhesion.

Example 4 The same method as in Example 1 except that 5% by weight of alum {KAl ₃ (SO ₄ ) ₂ (OH) ₆ } crystals was added to an aqueous solution containing 30% by weight of aluminum chloride as a chemical conversion treatment solution. To form patina.

The obtained patina film was uniform and had good adhesion without peeling.

In addition to these examples, various tests other than the thermal spraying method for forming a copper or copper alloy thin film, and various tests using various oxidizing liquids and methods of applying an oxidizing gas as a forced oxidation means were tested. It was confirmed that, according to the method of the present invention, good results can be obtained in almost the same manner as in the above-mentioned examples.

<Summary of Effects> As described above, according to the present invention, it is possible to obtain a patina having almost the same solid color tone as that of natural patina and excellent adhesion to all types without requiring 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 the front page (72) Inventor Hideo Tamano 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 thin film made of copper or a copper alloy is formed on the surface of a base material on which patina is to be formed, and the thin film is then added to (a) alkaline metal chloride and / or alkaline earth metal chloride and aluminum powder. In addition, chemical conversion treatment with a treatment solution containing one or more selected from (b) aluminum chloride, (c) stannic chloride, (d) zinc chloride, and (e) lead chloride, and subsequently this A method for forming patina, which comprises subjecting the above to forced oxidation treatment. 2. The method for forming patina according to claim 1, wherein the forced oxidation after the chemical conversion treatment is performed by a treatment of exposing to an ozone-containing atmosphere. 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.