JPH04193958A - Formation of patina - Google Patents

Abstract

PURPOSE:To form patina excellent in adhesion by subjecting a copper thin film formed on the surface of a substrate by electrodeposition to chemical treatment and thereafter executing forced oxidation treatment. CONSTITUTION:The thin film of copper or a copper allay is formed by electrodeposition on the surface of a substrate on which patina shall be formed, and after that, the above thin film is subjected to chemical treatment and is successively subjected to forced oxidation treatment. In this way, patina having a deep color tone almost same as that of natural one and extremely excellent in adhesion can stably be formed on every kinds of substrates in a short time without requiring special equipment. This is applicable in a wide field not only for roof materials but also for building inside wall materials, ornaments or the like.

Description

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

<Conventional technology and its challenges> Over the years, the surface of copper, which has been used for the roofing of shrines and temples, has been exposed to oxygen and water vapor in the atmosphere.

An elegant and beautiful green patina (CuCOx ・Cu(OH)z.

Cu S Oa・3 Cu(OH)z, CuCfz・3
It is well known that copper salts (such as basic copper salts such as Cu- (OH) As a result, copper roofs covered in patina can last for hundreds of years.

Therefore, in recent years, "patina film-forming products" that artificially generate a natural-looking patina in a short period of time to prevent corrosion of base materials and have decorative or artistic effects have been developed, not only for roofs and materials but also for interior walls of buildings. It has come to be seen in ornaments and ornaments, and many proposals have been made to date on means of artificially forming a patina that is close to natural.

5 These conventional artificial patina formation means can be broadly classified as follows.

(A) Chemical conversion treatment method in which contact is made with a chemical solution (for example,
-51468, etc.).

(B) Method of electrolytic treatment in a chemical solution (for example,
12117, etc.).

(C) A method in which a base material is subjected to a chemical conversion treatment and then further coated (for example, a method proposed in JP-A No. 55-8491).

(D) A method of painting with a paint containing a green-blue-forming substance (for example, the method proposed in JP-A-55-139467).

(E) A method in which copper or copper alloy powder is adhered with an adhesive to the surface of a copper plate whose surface has been roughened by sand blasting, and then an artificial patina-generating liquid such as ammonium chloride or ammonium sulfate is applied (for example, 52425, etc.).

However, the above-mentioned artificial patina formation means are practically a) The rate of development of patina is slow.

b) The patina coating is easy to peel off, and manufacturing equipment costs a lot of money.

C) Unable to stably form green-blue color, resulting in non-uniformity and poor color tone.

d) Poor adhesion of patina.

e) Many man-hours are required to form the green-blue coating, resulting in poor productivity.

Problems such as these have been pointed out, and furthermore, the base material is generally limited to copper or copper alloy, and if the patina surface is not protected by painting etc. There was also the problem that sufficient adhesion could not be maintained. Moreover, the protection of patina by using a paint film cannot provide a fundamental solution to the above problem because the paint film composition deteriorates due to ultraviolet rays.

Therefore, the purpose of the present invention is to stably form a patina film with excellent adhesion and uniform color tone in a short time regardless of the type of substrate and without requiring special equipment. The aim was to establish a relatively inexpensive means of obtaining 1.

Means for Solving the Problems> The present inventors have achieved the above objects (as a result of intensive research from various viewpoints). forming a thin film consisting of, and then subjecting this thin film to a chemical conversion treatment,
If this is combined with a subsequent forced oxidation treatment, it is possible to form a uniformly colored verdigris film with excellent adhesion on the surface of the substrate in a short period of time, regardless of the material of the substrate.

b) If electrodeposition is used as a means of forming a thin film made of copper or copper alloy on the surface of a substrate, no special equipment is required to form the thin film, and the substrate can be easily handled. Not only is this advantageous in terms of cost, but the adhesion of the patina produced can be further improved by adjusting the electrodeposition conditions.

We were able to obtain this knowledge.

The present invention was completed based on the above-mentioned findings, etc., and includes the following: ``After a thin film made of copper or copper alloy is electrodeposited on the surface of a base material on which patina is to be formed, the thin film is subjected to chemical conversion treatment. By subsequently performing a forced oxidation treatment, it is possible to stably form a patina with sufficiently excellent adhesion and a good appearance in a short period of time.

Here, the "base material on which patina is to be formed" is not limited to metal materials such as copper and copper alloys, but may also be ceramics, roof tiles, wood 3 synthetic resins, etc.
The material is not particularly limited. However, if the base material is not a metal material, the surface must be pretreated by a known method such as electroless plating or sputtering to form a "thin film made of copper or copper alloy" by electrodeposition. Needless to say, it needs to be treated to make it conductive.

Hereinafter, the present invention will be explained in more detail and concretely along with its functions and effects.

In the patina formation method according to the present invention, a "thin film made of copper or copper alloy" is first formed on the surface of the base material on which patina is to be formed by electrodeposition.

The thickness of the thin film is not particularly limited, but is usually 1
It is good to set it to about 100 gm, preferably about 5 to 40 gm. Of course, it is possible to form a patina even if the film thickness is less than 1 gm, but in this case it is not preferable because cracks are likely to occur in the thin film. On the other hand, if the film thickness exceeds 1100 tr, it becomes difficult to obtain a satisfactory color tone and is also unfavorable in terms of production cost.

Of course, methods for forming a metallic thin film on the surface of the substrate include the electrodeposition method, the vacuum evaporation method, and the sputtering method.

Ion blating method, thermal spraying method, etc. are known, but
In the case of electrodeposition, as mentioned above, ``no special equipment is required to form a thin film made of copper or copper alloy,'' and ``the base material is easy to handle4. In addition to this, it is extremely advantageous because the adhesion of the patina produced subsequently can be further improved by adjusting the electrodeposition conditions.

In addition, in order to form a "copper or copper alloy thin film" by electrodeposition according to the present invention, for example, a known "acidic copper sulfate bath" is used.
Or electrolyte composition such as "alkaline copper cyanide bath",
It is possible to simply apply the electrolytic conditions as they are, but if possible, it would be better to use the electrolytic copper plating method proposed earlier by the present applicant (Patent Application No.
232866), i.e. current density near 5A
/dm or more, and the flow rate of the plating solution is 1 m/sec or more (the current density is preferably about 100 A/d rd, and the plating solution flow rate is more preferably about 1.5 m/sec). It is desirable to electrodeposit a thin film. This is because when a "copper or copper alloy thin film" is electrodeposited under the above conditions, the adhesion of the patina produced by subsequent processing becomes even better, making the patina layer firmly adhered to the base material more stable. This is because it can be formed into

The surface roughness of the "thin film made of copper or copper alloy" itself formed on the base material is not particularly limited, but if the roughness of the thin film surface is less than 3, the degree of patina will be low. On the other hand, if it exceeds 50 degrees, the adhesion strength between the base material and the thin film tends to decrease, so it is usually 3 to 50 degrees.
1, preferably 5 to 40 pieces.

By the way, "thin film made of copper or copper alloy" on the surface of the base material
Roughening the surface of the base material prior to the formation of the coating improves the adhesion between the base material and the "thin film made of copper or copper alloy", and thus the adhesion of the patina coating to be formed. This is extremely desirable. Therefore, before forming a thin film made of copper or copper alloy, the surface of the base material is roughened as necessary to prevent roughening of the base material surface and temporary surface activation. It will be planned.

Generally, two types of methods for roughening the surface of a substrate are known: a chemical method (including an electrochemical method) and a physical method (mechanical method). Examples of the former include "method of immersion in acid or alkali (i.e., etching method)" and "electrolytic method," and examples of the latter include "blasting method" and "
Examples include "water jet method", "moving crab method", "hand tool method", etc. Therefore, when roughening the surface of the base material prior to forming the "thin film made of copper or copper alloy" according to the present invention, It is necessary to appropriately select a surface roughening method depending on the type of the substrate and the desired roughness of the patina-forming high surface.

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 base material surface can be removed. It can be said that "blasting method" is suitable.

Moreover, in the blasting method, abrasive materials with various hardness levels such as silica sand, steel grisode, steel shonot, fused alumina (artificial corundum), alundum, carborundum, glass beads, synthetic resin particles, etc. are used as the abrasive material. is used, so it is possible to select a suitable one according to the type of base material etc.
Another advantage is that the surface roughness can be adjusted by changing the blasting conditions.

In addition, blasting methods are classified into types from various viewpoints. For example, from the viewpoint of the method, spraying of abrasive materials can be classified into "method of blasting using compressed air" and "method of blasting using centrifugal force." Further, depending on the dry and wet state of the abrasive to be sprayed, it can be classified into "dry method" and "wet method", but in the present invention, there are no particular restrictions on the types or combinations thereof.

The surface roughness of the base material after the surface roughening treatment is preferably 3 IXm or more, preferably 10 to 30 gIn. This is because when the surface roughness is less than 3 degrees, the effect of improving the adhesion with the "thin film made of copper or copper alloy" is not significant. On the other hand, if the surface roughness exceeds 50 -, although the adhesion will be good, it is not practical because distortion occurring in the base material may become a problem.

Now, in the present invention, once a "thin film made of copper or a copper alloy" is electrodeposited on the surface of a base material, the thin film is then subjected to a chemical conversion treatment.

In general, "chemical conversion treatment" involves chemically reacting the metal with a corrosive solution (chemical treatment solution) adjusted to specific conditions to form a layer of water-insoluble corrosion products that stick to the surface of the metal. Rust prevention is a process that utilizes the physical or chemical properties of corrosion products.

It has been applied to paint bases, lubricating bases for plastic working, etc.

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

The chemical conversion treatment liquid used in the present invention is not limited to any type as long as it forms a water-insoluble corrosion product layer on the surface of copper or copper alloy. And as such, traditionally ammonium salts.

Hydrochloric acid, caustic soda, sulfide 9gL salt, nitrate.

Solutions containing acetate, carbonate monobicarbonate, alum, etc., and combinations thereof (of course, this includes what is called an artificial patina-generating solution, and the solvent is not limited to water) is known, but more specific examples include the following chemical conversion treatment liquid.

a) An aqueous solution prepared by adding an alkali metal chloride and/or an alkaline earth metal chloride to hydrochloric acid, nitric acid and ammonium sulfate.

b) Aqueous solution with addition of cupric chloride.

C) Alkali metal chloride and/or alkaline earth metal chloride'! #(e.g. NaC!, K(j, NHaCl
) is treated with an aqueous solution containing copper sulfate (in this case, an aqueous solution containing an alkali metal chloride and/or alkaline earth metal chloride), followed by treatment with an aqueous solution containing copper sulfate, Similar results can be obtained by performing two-stage processing in the opposite order.)

As mentioned above, in the present invention, there is no particular restriction on the type of chemical conversion treatment liquid, and these chemical conversion treatment liquids (the active ingredient concentration is also not particularly limited, but are usually 5 to 50% by weight, preferably 20 to 50% by weight). The chemical conversion treatment is carried out by coating or spraying a "thin film made of copper or copper alloy" or by immersing the thin film in the chemical conversion treatment solution.

This chemical conversion treatment forms a water-insoluble corrosion product layer on the "thin film made of copper or copper alloy," but this corrosion product layer contains Cu, CuzO, CuO, or Cu(○
It is presumed that H)z, CuCZ, CuCZ2, etc. coexist in a complex manner.

In this case, the "thin film made of copper or copper alloy" formed by electrodeposition tends to undergo a chemical conversion reaction, and good results can be obtained.

This is thought to be due to the fact that the electrodeposited film has a relatively thick electrode potential because the bond between the metal U weaves is weak and it is almost amorphous.

Next, the "thin film made of copper and copper alloy" that has been chemically treated as described above is subjected to forced oxidation treatment to form a patina with excellent adhesion.

As a means of forced oxidation, "method using oxidizing liquid",
There are methods such as "method using oxidizing gas" and "method using electrolysis," but it can be said that "method using gas" is preferable when considering ease of handling of the base material, adhesion of patina, etc.

Air, oxygen gas, etc. are commonly used as oxidizing gases, but ozone (03) is the most preferable when considering processing speed (i.e. patina formation rate). An exposure method is recommended. In this case, there is no particular limit to the ozone concentration, and it is sufficient to mix ozone into the atmosphere using a normal ozone generator.

When a "thin film made of copper or copper alloy" that has been subjected to a chemical conversion treatment is forcibly oxidized with ozone, it is desirable to carry out the forced oxidation treatment before the chemical conversion film formed by the chemical conversion treatment dries. In other words, if the chemical conversion film is oxidized by placing it in an ozone-containing atmosphere in the presence of sufficient moisture (preferably immediately after the chemical conversion treatment), a patina film with extremely excellent adhesion will be formed in a shorter time. be able to.

The mechanism of formation of patina due to this "forced oxidation of chemically treated copper or copper alloy thin film" has not been clearly elucidated at present, but the patina produced by this treatment has been found to be chemically stable and basic by X-ray diffraction. Cupric chloride (CuC/z
- Confirmed to be 3 cu (OH) zl.

Forced oxidation treatment time for chemically treated copper or copper alloy thin film is:
Taking ozone treatment (treatment of exposure to an ozone-containing atmosphere) as an example, it will vary depending on the ozone concentration and the amount of ozone-containing gas, etc., but if a commercially available ozone generator is used, it will usually be about 10~
About 60 minutes is sufficient. However, since the surface color changes in about 10 seconds in treatment using a commercially available ozone generator, it is thought that the reaction starts in about this amount of time.

After the forced oxidation treatment is completed, the verdigris-forming substrate is preferably cured and dried. There is no particular need for heating in this curing, and it is usually sufficient to carry out the curing at room temperature for 2 to 24 hours.

In this way, it is possible to form a uniformly colored patina with extremely good adhesion in a short time.

Next, the present invention will be explained in more detail with reference to Examples.

<Example> Example 1 First, a pre-degreased copper plate (220mm width x 250ts
(length x 0.3 WM thickness) and air pressure 1.5 to 5 kg/ee using alundum powder with particle size #50 to #250.
The spraying at 1 (L) pressure was used to roughen the surface of the copper plate by blasting.

Next, using the copper plate (roughened surface) as a cathode and the lead plate as an anode, a copper sulfate solution (CuSO, -5H2O: 150 g
/β, H2SO4: 80g/') as the electrolyte, current density: 80 A/dr&.

Flow rate of plating solution: 1.5 m/sec.

Electrolysis was performed for 5 minutes at a liquid temperature of 55° C. to form a new copper thin film by electrodeposition on the surface of the copper plate.

Next, the copper thin film is coated with cupric chloride 30, which is a chemical conversion treatment solution.
% by weight aqueous solution is uniformly applied with a brush to perform chemical conversion treatment, and while the resulting film contains sufficient moisture, it is charged into an ozone oxidation box (0,2+y?) and placed in an ozone generator (Koyote Sox). ■ KW-70 heavy duty machine, 01 generation amount: Approximately 9 g/hrl, ozone-containing air is 3j!/+win
It was blown for 15 minutes at a rate of .

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

When the patina formed by the above treatment was observed, it was found that the patina had a deep bluish green tone, and even when the patina film was rubbed with a fingertip, no peeling occurred. It was confirmed that the adhesion was superior to that of natural patina.

Furthermore, analysis by X-ray diffraction confirmed that the patina formed by the method of the present invention is basic cupric chloride (Cu(lJz·3Cu(OH)z), which is the main component of natural patina.

Example 2 A copper plate was treated under the same conditions as in Example 1, except that the surface of the copper plate was roughened by "etching using a known chemical polishing solution" to form a patina.

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

In addition to these examples, electrodeposition methods under various conditions for forming copper or copper alloy thin films, various known chemical conversion treatment solutions (including those called artificial patina generation solutions), and various forced oxidation methods are also available. Tests were conducted using various combinations of methods for applying oxidizing liquids and oxidizing gases, and it was confirmed that in all cases, if the method of the present invention was followed, good results could be obtained that were almost the same as those in the above examples. Ta.

Summary of Effects> As explained above, according to the present invention, patina that exhibits almost the same deep color tone as natural patina and has extremely excellent adhesion can be applied to all types of patina without requiring any special equipment. It can be stably formed on a base material in a short time, and is expected to be applied not only to roofing materials, but also to a wide range of fields such as interior wall materials and decorative items, bringing extremely useful effects industrially. It can be done.

Claims (4)

[Claims] (1) Formation of a patina characterized by electrodepositing a thin film made of copper or copper alloy on the surface of a substrate on which a patina is to be formed, then subjecting the thin film to a chemical conversion treatment, and subsequently subjecting it to a forced oxidation treatment. Method. (2) Electrodeposition of thin films made of copper or copper alloys at current density:
The method for forming a patina according to claim 1, which is carried out while controlling the flow rate of the plating solution to be 75 A/dm^2 or more and a flow rate of the plating solution to be 1 m/sec or more. (3) The method for forming a patina according to claim 1 or 2, wherein the forced oxidation after the chemical conversion treatment is performed by exposing it to an ozone-containing atmosphere. (4) The method for forming a patina according to any one of claims 1 to 3, wherein the surface of the base material on which the patina is to be formed is roughened, and then a thin film made of copper or a copper alloy is formed by electrodeposition.