JPH02236286A - Copper product forming patina in early time and production thereof - Google Patents

Abstract

PURPOSE:To generate uniform patina over the entire surface in an earl time by forming a porous copper-based metallic layer on the surface of a product, the surface of which consists of the copper based metal. CONSTITUTION:The surface of the product, at least the surface of which consists of copper or copper alloy is subjected to an oxidation treatment and is then reduced to form the porous copper or copper alloy layer on the surface of the product. Falling down of rain fall is prevented by providing the porous layer on the surface of the copper product in such a manner. In addition, the porous surface has the equiv. water vapor pressure lower than the equiv. water vapor pressure of a flat surface for its capillarity and is, therefore, hardly driable. Further, frost setting arises with the lower humidity on the porous surface than on the flat surface and the time when the surface is longer and, therefore, the patina is generated in an extremely early period. The formation of the patina is accelerated by forming the porous layer to >=0.01mu thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a copper product whose at least the surface is made of copper or a copper alloy and which forms a patina at an early stage, and a method for manufacturing the same.

[Problems to be solved by conventional technology and inventions] Shrines. temples. Many of the roofs and exteriors of houses and other buildings, as well as art decorations, are made of copper or copper alloys, or have copper plating applied to their surfaces. This is because copper has excellent weather resistance and does not corrode and can withstand long-term use, but copper develops a patina on its surface, which gives copper products a solid and calm feel. This is the reason why copper is preferred as roofing material for buildings and works of art.

By the way, patina occurs naturally when copper products are exposed to the atmosphere, but its growth rate is extremely slow and it generally takes several years or more for the desired coating to form. It is true.

For this reason, the conventional method was to temporarily erode the surface of copper products by dousing them with inorganic acids such as sulfuric acid, nitric acid, or hydrochloric acid, and then treating the surface with sodium carbonate or other substances to artificially generate patina. Attempted. However, the verdigris film produced by this method is extremely thin and has brownish unevenness, has low productivity, and has drawbacks such as requiring large-scale wastewater facilities.

Therefore, as a measure to eliminate such defects, attempts have been made to apply a paint containing a copper compound of basic copper carbonate, copper sulfide, or copper oxide as a pigment to the surface of copper products instead of patina.

However, although this method has much higher productivity than the above-mentioned surface treatment methods, on the other hand, these coatings have very low weather resistance, and if used on copper roofs, for example, they will wear out within a year. The problem was that the paint peeled off, making the exterior look extremely ugly.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention is a copper product that accelerates the growth rate of patina that occurs on the surface of copper or copper alloy, and forms patina at an early stage when patina naturally occurs in a short period of time, and a method for manufacturing the same. was developed.

? The copper product of the present invention is characterized in that a bolus copper or copper alloy layer is formed on the surface of the product, at least the surface of which is made of copper or copper alloy, and the bolus copper or copper alloy layer has a thickness of 0.01 μm. Form it to a thickness greater than or equal to that.

Furthermore, the method for producing a copper product of the present invention includes forming a porous copper or copper alloy layer on the surface of the product by oxidizing the surface of the product, at least the surface of which is made of copper or copper alloy, and then subjecting it to reduction treatment. This is a characteristic feature.

[Effect]

The process by which patina is formed in nature is through condensation on the surface of copper products during rain or high humidity. CO₂ and SO₂ in the atmosphere dissolve into this dew condensation water and corrode the copper, resulting in a patina.

When this condensed water adheres to the surface of a copper product, for example, the surface of a roof board, if the surface is smooth, it becomes difficult for the rain water to be trapped and it quickly flows down or evaporates to dryness in a short period of time. , the amount of time copper is exposed to corrosive environments is reduced.

As a result, the corrosion reaction progresses slowly, so it takes a very long time to develop a patina.

Therefore, the present invention provides a porous layer on the surface of a copper product to prevent rainwater from flowing down, and due to capillarity, the porous surface has a lower equilibrium water vapor pressure than a flat surface, so it is less likely to dry. It is. Furthermore, condensation occurs on bolus surfaces at lower humidity than on flat surfaces, and because porous surfaces remain wet for much longer, patina develops much earlier.

A method for forming a bolus layer on the surface is to form a copper compound on the surface of a copper product and then perform a reduction treatment or dealloing.

Methods for forming a copper compound on the surface include (1) a method of forming by reaction with a chemical solution, (2) a method of electrolysis using an anode in a chemical solution, (3) a method of coating by a CVD method, (
4) There is a method of reacting in the gas phase (atmospheric oxidation, sulfidation, humid oxidation), and methods of reduction include (5) a method of reducing by reaction with a chemical solution, (6) a method of electrolyzing as a cathode in a chemical solution, (7) There is a method of thermal reduction in a reducing atmosphere. Further, dealloying includes, for example, dezincing treatment with brass (pickling after atmospheric oxidation), and any method may be used, but from the viewpoint of cost, methods 1 and 2 above are preferred. The method of performing the oxidation treatment in step 4 and then the reduction treatment in steps 5, 6, and 7 above is superior.

In addition, the thickness of the bolus layer was set to 0.01 μm or more because
This is because if the thickness is less than 0.01 μm, the generation of patina is not substantially accelerated, and the upper limit of the thickness is preferably 5 μm from the viewpoint of cost and film adhesion.

〔Example〕

The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

First, copper roofing board materials Nα1 to Nα4 as shown below were created.

Roofing material of the present invention 1 A phosphorus-deoxidized copper plate having a thickness of 0.45 mm was heat-treated at 500° C. for 1 hour in the atmosphere to form copper oxide on the surface. This was immersed in an aqueous solution of 0.5% IPA (isopropyl alcohol) at 80° C. for 30 seconds to form a bolus layer with a thickness of 0.2 μm on the surface.

Roofing sheet material of the present invention NIl2 The same phosphorus-deoxidized copper plate was immersed in Ebonol C Special (manufactured by Meltex) 150 g/l I[10°C bath for 2 minutes to form a chemical film mainly composed of copper oxide on the surface. This is 0. KC from IN! An aqueous solution was electrolyzed at 0.1^/drrf using a SUS anode as a counter electrode until it became copper-colored. The thickness of the porous layer was 0.5 μm.

Roofing sheet material of the present invention Nα3 The same phosphorus-deoxidized copper plate was used as 80 with N a OH=200g/l.
℃ as an anode in an aqueous solution, and a Q
．． Electrolysis was performed for 20 seconds at a current density of 5 A/dnf to form copper oxide on the surface, and then heat treatment was performed at 600° C. for 1 hour in a reducing atmosphere containing 4% H 2 and CO to reduce the material.

The thickness of the bolus layer was 0.08 μm.

Roofing sheet material Nα4 of the present invention The same deoxidized copper plate was plated with Cu-35%Zn to a thickness of 0.1 μm using a cyan bath in a normal plating process, and then
It was dezinced by immersing it in 3% dilute sulfuric acid at 0° C. for 1 minute to form a porous Cu layer with a thickness of about 0.1 μm on the surface. The above roofing sheet materials were exposed to coastal areas and mountainous areas, together with comparative roofing sheet material Nα5 made of untreated phosphorus-deoxidized copper plates, and the occurrence of patina was investigated. The results are shown in Table 1.

Comparison of Roof Sheet Materials of the Present Invention Roof Sheet Materials 4 Years 5 Years 6 Years 5 Years 12 Years 7 Years 9 Years 10 Years 9>15 Years As is clear from Table 1, the roof sheet materials of the present invention Nα1 to 4
Both of these patinas develop faster than the comparative roofing sheet material Nα5,
and uniform.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to produce a uniform patina on the entire surface of a copper product at an early stage, thereby achieving remarkable industrial effects.

Claims (3)

[Claims] (1) A copper product that quickly forms a patina, characterized in that a porous copper or copper alloy layer is formed on the surface of the product, at least the surface of which is made of copper or a copper alloy. (2) The copper product that quickly forms a patina according to claim (1), wherein the porous copper or copper alloy layer is formed to a thickness of 0.01 μm or more. (3) Early patina characterized by forming a porous copper or copper alloy layer on the surface of the product by oxidizing the surface of the product, at least the surface of which is made of copper or copper alloy, and then subjecting it to reduction treatment. A manufacturing method for forming copper products.