WO2006035695A1

WO2006035695A1 - Hexavalent chromium-free surface treating method and hexavalent chromium-free lead-containing copper-base metal material

Info

Publication number: WO2006035695A1
Application number: PCT/JP2005/017597
Authority: WO
Inventors: Youji Hayakawa
Original assignee: Hayakawa Valve Production Co., Ltd.
Priority date: 2004-09-28
Filing date: 2005-09-26
Publication date: 2006-04-06
Also published as: JP4463278B2; JPWO2006035695A1

Abstract

A product made from a lead-containing metal material wherein dissolution of lead from the finished product is surely prevented while suppressing dissolution of hexavalent chromium to zero and improving the corrosion resistance of the surface, thereby surely preventing discoloration or the like. Specifically disclosed is a hexavalent chromium-free surface treating method comprising a chromic acid treatment step wherein the surface of a lead-containing metal material is treated with a chromic acid for dissolving and removing lead in the surface; a hexavalent chromium-removing step for completely removing hexavalent chromium as a coating over the surface of the lead-containing metal material which is formed in the previous chromic acid treatment step by using a reduction aqueous solution containing a reducing agent for the chromic acid; and a surface-modifying step for modifying the surface of the lead-containing metal material from which hexavalent chromium has been removed. This surface treating method can be applied to nickel-chromium (NiCr) plating or industrial chromium (Cr) plating for various metals other than lead-containing metal materials and plastic (various resin) materials, or products for various uses which are made from materials subjected to various surface treatments using hexavalent chromium.

Description

Specification

Hexavalent chromium-free surface treatment method and hexavalent chromium-free lead-containing copper-based metal material

TECHNICAL FIELD [0001] The present invention relates to a hexavalent chromium-free surface treatment method for various metal materials including lead-containing copper-based metal materials or other base materials, and a hexavalent chromium-free bell-containing copper-based metal material. Brackets 'joints' Lead-containing copper-based metal materials such as free-cutting brass (pure copper and various copper alloys) used as materials for plumbing and other water supply products, and surface treatment during the surface treatment of chrome-plated copper-based metal materials The hexavalent chromium-free surface treatment method for various metal materials such as lead-containing copper-based metal materials and other base materials that can completely remove the hexavalent chromium remaining on the surface and also enable surface modification thereof, and It relates to a copper-based metal material containing a chromium-free bell. Background art

[0002] Conventionally, water supply fittings such as faucet fittings, joints, and piping parts are generally manufactured by forging or forging a copper alloy such as bronze or brass, and shaping it into a desired shape by cutting, polishing, etc. Forged products or forged products, or chrome plated forged products or chrome plated forged products in which nickel chrome plating is applied to a shaped or forged product after shaping.

[0003] In addition, as a copper alloy for water supplies, a lead-containing copper alloy in which lead is added to a copper alloy (especially brass) in order to improve the machinability of the copper alloy during cutting during the manufacturing process ( In particular, free-cutting brass) is used. However, due to recent trends in environmental regulations, the elution of lead in water supplies after commercialization has become a problem, and lead removal or lead-free (NPb) surface treatment technology has been developed to remove lead from water supplies. Has been.

For example, there is a technique described in Patent Document 1 as a document related to NPb surface treatment.

Patent Document 1: JP 2000-96269

[0004] Patent Document 1 discloses a treatment method for preventing lead elution by performing chromate treatment on the surface of a lead-containing copper alloy material and forming a chromate film. According to this treatment method, the lead-containing copper alloy is immersed in a chromate solution to which phosphoric acid has been added. According to this treatment method, lead-containing copper is produced by the synergistic effect of chromic acid and phosphoric acid contained in the chromate solution. The chemical reaction that dissolves the alloy and the chemical reaction that forms the chromate film occur, and the lead remaining on the surface of the lead-containing copper alloy material is also dissolved and removed. If the lead-containing copper alloy material surface after the removal of lead is protected, corrosion of the lead-containing copper alloy due to long-term water corrosion does not cause internal lead to dissolve, and lead elution can be reduced over a long period of time. Has been.

Disclosure of the invention

Problems to be solved by the invention

[0005] However, with the technology described in Patent Document 1, it is possible to remove lead on the surface of the copper alloy by NPb treatment and reduce the elution of lead due to productization power. A chromate film will be formed. This chromate film is a gel-like complex hydrated oxide film (XCr O -YCrO · ΖΗ Ο) mainly composed of hexavalent chromium (C +) and trivalent chromium (Cr ³⁺ ).

2 3 3 2 With excellent anti-corrosion performance, part of hexavalent chromium is incorporated into the film as it is hexavalent, and has both anti-fouling and self-healing capabilities. However, because hexavalent chromium is an environmentally hazardous substance and is harmful to the human body, such as suspected carcinogenicity, Japan has a strong alternative film or surface treatment to replace the chromate film mainly in Europe and the United States. Various alternative technologies have been proposed. Hexavalent chromium, like lead, is designated as a specified hazardous substance by the Restriction of Use of Specific Hazardous Substances (RoHS) Directive that is enforced on July 1, 2006. Therefore, the development of surface treatment technology without elution of the final product strength hexavalent chromium is desired.

[0006] In addition to water supplies, nickel-chrome (NiCr) plating and industrial chromium (Cr) plating for various metals and plastics (various grease) used in automobiles, building materials, furniture, hardware, etc., or In various surface treatments using hexavalent chromium, chromate treatment may be performed for the purpose of improving corrosion resistance and preventing discoloration (anticorrosion). However, as mentioned above, there has been a growing interest in environmental issues in recent years, domestic and overseas laws and regulations, especially the European Union (EU) hazardous substance regulations applied from July 2006, electrical and electronic Due to the Restriction on the Use of Specific Hazardous Substances Used in Equipment (RoHS) Directive and accompanying voluntary regulations, hexavalent chromium, which is an environmentally hazardous substance from the final product, will not be eluted in these fields. The development of surface treatment technology is urgently required. [0007] Currently, alternative technologies for chromate treatment with hexavalent chromium include (1) chromate treatment using trivalent chromium, (2) treatment for applying an additional coating layer to the chromate layer using trivalent chromium, ( 3) Inorganic non-chromate treatment, (4) Organic non-chromate treatment, etc. have been proposed. Of these, inorganic nonchromate treatments include titanium, zirconium, molybdenum, manganese, and cerium surface treatments, and organic nonchromate treatments use silane coupling agents as the main component. Processing is proposed.

[0008] Here, as a chromate treatment technique using trivalent chromium, for example, there is a technique described in Patent Document 2.

Patent Document 2: JP 2004-60051

[0009] Patent Document 2 discloses a steel plate that can be widely applied to household appliances 'building materials' for automobiles, etc., has excellent corrosion resistance after heating, and has zero elution of hexavalent chromium, which is an environmentally hazardous substance. It is disclosed. In this technology, partially reduced chromic acid, phosphoric acid compound, and nitric acid compound are essential components, and there is a predetermined relationship between the chromium reduction rate (X) of partially reduced chromic acid and the concentration of each component in the bath. The composition is applied to the steel plate and dried.

[0010] However, the chromate treatment using trivalent chromium including the technique of Patent Document 2 has a problem that the cost is higher and the corrosion resistance is lower than that of the hexavalent chromate treatment. In the technique described in Patent Document 2, an all-trivalent chromium film is formed on the surface. Over time, the trivalent chromium constituting the film becomes hexavalent chromium by reaction with the outside. The possibility of alteration cannot be denied. Furthermore, the technology described in Patent Document 2 relates to the surface treatment for steel materials, and in particular, the elution of lead, which is also an environmentally hazardous substance, in the surface treatment of lead-containing copper-based metals prior to the elution of hexavalent chromium. There is no disclosure or suggestion about the point to prevent this. On the other hand, with other alternative technologies, that is, non-chromate treatment technology, the surface treatment equipment and processes that have been used up to now cannot be used as they are, and the capital investment is very expensive.

[0011] In particular, a water faucet device such as a mixing faucet or a single lever faucet or various valve devices, etc., which has a complicated internal structure combining a number of parts, A large number of small gaps (small gaps) and complex-shaped gaps (complex shape gaps) are formed. Also, there are many small cracks on the inner surface, and small pins There are holes. Therefore, there is a high possibility that the eluted chromium remains in these minute gaps, complicated gaps, cracks, pinholes, and the like. Therefore, unless these remaining hexavalent chromium is completely removed, hexavalent chromium may be eluted or leached with the use of the faucet device.

[0012] Therefore, the present invention relates to various metals that use nickel chrome (NiCr) plating and industrial chromium (Cr) plating, or hexavalent chromium of various metals such as lead-containing metals and plastics (various grease) materials. In products of various uses that have surface treatment, lead-containing metal materials can reliably prevent the elution of lead after commercialization, and in all cases, the elution amount of hexavalent chromium should be zero. In the case of metal materials such as copper-based metal materials, various metal materials such as lead-containing copper-based metal materials and other base materials that improve surface corrosion resistance and can reliably prevent discoloration, etc. And providing a hexavalent chromium-free surface treatment method and a hexavalent chromium-free bell-containing copper-based metal material. Means for solving the problem

[0013] A hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 1 includes a chromic acid treatment step of treating the surface of the lead-containing metal material with chromic acid and eluting and removing lead on the surface portion; A hexavalent chromium removing step for completely removing hexavalent chromium as a film component formed on the surface of the lead-containing metal material in the chromic acid treatment step with a reducing aqueous solution containing an acid reducing agent; A surface modification treatment step for modifying the surface of the lead-containing metal material from which the valent chromium has been removed.

[0014] Here, in the case of a metal material having a space or an exposed portion inside, such as a pipe material, the surface of the lead-containing metal material includes not only its outer surface but also its inner surface. For example, in the case of using brass faucet fittings or water pipe parts as lead-containing metal materials, the chromic acid etching is applied not only to the external surface but also to the internal surface or the exposed internal surface. The process of the process, the process of the hexavalent chromium removal process, and the process of the surface modification process are performed. In addition, the internal surface of the lead-containing metal material also includes minute gaps, complex-shaped gaps, cracks, pinholes, etc., and the chromic acid etching is also applied to such minute gaps, complex-shaped gaps, cracks, pinholes, etc. The process of the process and the process of the hexavalent chromium removing process are performed by the process of the surface modification process. [0015] A hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 2 is characterized in that, in the configuration of claim 1, the hexavalent chromium removing step includes the step of containing the lead in an aqueous solution of a reducing agent for chromic acid. The surface of the lead-containing metal material is reduced by immersing the metal material for a predetermined time.

[0016] The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 3 is characterized in that, in the configuration of claim 1 or 2, the hexavalent chromium removing process power is added to the aqueous solution of the reducing agent for chromic acid. The hexavalent chromium on the surface of the lead-containing metal material is reduced to trivalent chromium by immersing the contained metal material for a predetermined time. Further, the hexavalent chromium removing step and the surface modification treatment step are performed. In the meantime, a water washing step of completely separating and removing trivalent chromium remaining on the surface of the lead-containing metal material by water washing is provided.

[0017] The hexavalent chromium-free treatment method for a lead-containing metal material according to claim 4 is the method according to any one of claims 1 to 3, wherein the reducing agent for chromic acid is sodium hyposulfite or sodium nitrite. , Sodium thiosulfate, sodium sulfite, or a mixture thereof.

[0018] A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 5 is the structure according to any one of claims 1 to 4, wherein the surface modification treatment step comprises phosphoric acid and nitric acid. By immersing the lead-containing metal material for a predetermined time in a chemical conversion treatment tank storing a mixed acid aqueous solution contained as a main material, a phosphate film is formed on the surface of the lead-containing metal material.

[0019] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 6 includes etching the surface of the base material of the lead-containing copper-based metal material with chromic acid, Hexavalent chromium as a coating component formed on the base surface of the lead-containing copper-based metal material in the chromic acid etching step by an chromic acid etching step for eluting and removing lead from the surface portion and an aqueous solution of a reducing agent for chromic acid A hexavalent chromium removing step that completely removes hexavalent chromium, and a surface modifying treatment step that modifies the substrate surface of the lead-containing copper-based metal material from which hexavalent chromium has been removed.

[0020] Here, the surface of the lead-containing copper-based metal material includes the internal surface in addition to the external surface in the case of a metal material having a space or an exposed portion inside such as a tube material. For example, lead-containing copper When metal faucets such as brass fittings or water pipe parts are used as the metal material, not only the external surface but also the internal surface or the exposed internal surface are treated with the chromic acid etching process or the The hexavalent chromium removal process and the surface modification process are performed.

[0021] A hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 7 is the configuration according to claim 6, wherein the hexavalent chromium removing step includes the lead-containing metal material in an aqueous solution of a reducing agent for chromic acid. The base surface of the lead-containing copper-based metal material is reduced by immersing the copper-based metal material for a predetermined time.

[0022] The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 8 is characterized in that, in the configuration of claim 6 or 7, the hexavalent chromium-removing step force is contained in an aqueous solution of a reducing agent for chromic acid. A hexavalent chromium on the surface of the lead-containing copper-based metal material is reduced to trivalent chromium by immersing the contained copper-based metal material for a predetermined time, and further, the hexavalent chromium removing step and the surface A water washing step is provided between the reforming treatment step and the trivalent chromium remaining on the surface of the lead-containing metal material completely separated by water washing.

[0023] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 9 includes a chromium plating step for forming a chromium plating layer on the lead-containing copper-based metal material, and a product interior of the lead-containing copper-based metal material. Alternatively, a coating formed on the surface of the lead-containing copper-based metal material in the chromic acid etching step or the chrome plating step by a chromic acid etching step for eluting and removing lead from the exposed internal metal portion and an aqueous solution of a reducing agent for chromic acid A hexavalent chromium removing step for completely removing hexavalent chromium as a component, and a surface modifying treatment step for modifying the surface of the lead-containing copper-based metal material from which hexavalent chromium has been removed.

[0024] Here, the chrome plating step and the chromic acid etching step are usually performed simultaneously. That is, the lead-containing copper-based metal material as the object to be processed is subjected to a chrome plating process and at the same time an etching process using chromic acid. In addition, the surface of the lead-containing copper-based metal material includes the inner surface in addition to the outer surface in the case of a metal material having a space or an exposed portion inside such as a pipe material. For example, when a faucet fitting made of brass or the like or a water pipe component is used as a lead-containing copper-based metal material, nickel plating and chromium plating are formed only on the outer surface, and the inner surface (inside the product) Internal metal exposure with exposed brass substrate Part. Therefore, the treatment of the chromic acid etching step is performed on the exposed internal surface portion to prevent the elution of lead from the inside or the exposed internal surface portion of the lead-containing copper-based metal material. Furthermore, the hexavalent chromium removing step is performed not only on the outer surface of the lead-containing copper-based metal material, but also on the inner surface thereof, that is, the inside of the product or the exposed portion of the inner metal. That is, a hexavalent chromium film is formed inside the product of the lead-containing copper-based metal material or in the exposed internal metal part due to the chromium plating treatment or the chromic acid etching treatment. This treatment is applied not only to the external surface (plated surface) of the lead-containing copper-based metal material but also to the inside of the product or the exposed internal surface (base surface). Furthermore, the treatment in the surface modification treatment step is performed not only on the outer surface (plated surface) of the lead-containing copper-based metal material but also on the inside of the product or the exposed inner surface (base surface).

[0025] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 10 is characterized in that, in the configuration of claim 9, the hexavalent chromium-removing process power is contained in an aqueous solution of a reducing agent for chromic acid. The surface of the lead-containing copper-based metal material is reduced by immersing the copper-based metal material for a predetermined time.

[0026] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 11 is characterized in that, in the configuration of claim 9 or 10, the hexavalent chromium removing step force is contained in an aqueous solution of a reducing agent for chromic acid. By immersing the lead-containing copper-based metal material for a predetermined time, the hexavalent chromium on the surface of the lead-containing copper-based metal material is reduced to trivalent chromium. Further, the hexavalent chromium removing step and the surface A water washing step for completely separating and removing trivalent chromium remaining on the surface of the lead-containing metal material by water washing between the reforming treatment step, whereby the surface of the lead-containing copper-based metal material is The surface of the chromium plating layer should be a zero-valent chromium surface, such as a chromium plating layer.

[0027] A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 12 is the structure of claim 11, wherein the hexavalent chromium removing step is maintained at a predetermined temperature and a predetermined concentration. By immersing the lead-containing copper-based metal material in an aqueous solution of a reducing agent for a predetermined time, the hexavalent chromium on the surface of the lead-containing copper-based metal material is completely removed to obtain a zero-valent chromium surface. It is.

[0028] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 13 is characterized in that the claim 6 Alternatively, in the configuration of 9, the hexavalent chromium on the surface of the lead-containing copper-based metal material is immersed in the aqueous solution of the reducing agent for chromic acid for a predetermined time in the hexavalent chromium removing step. Chromium is reduced to trivalent chromium, separated from the surface strength of the lead-containing copper-based metal material, and released or released into the aqueous solution. On the other hand, between the hexavalent chromium removal step and the surface modification treatment step, A water washing step is provided for completely separating and removing trivalent chromium remaining on the surface of the lead-containing copper-based metal material by water washing.

[0029] A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 14 is the structure according to any one of claims 6 to 13, wherein the reducing agent for chromic acid is sodium hyposulfite or nithion. One of sodium acid, sodium thiosulfate, sodium sulfite, or a mixture thereof.

[0030] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 15 is the structure according to any one of claims 6 to 14, wherein the surface modification treatment step comprises phosphoric acid and nitric acid. The lead-containing copper-based metal material is formed on the surface of the lead-containing copper-based metal material by immersing the lead-containing copper-based metal material for a predetermined time in a chemical conversion treatment tank storing an aqueous solution of mixed acid contained as a main material. .

[0031] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 16 is the structure according to any one of claims 6 to 14, wherein the surface modification treatment step includes phosphoric acid at a concentration of about 2. By immersing the lead-containing copper-based metal material for a predetermined time in an aqueous solution of mixed acid containing phosphoric acid and nitric acid as main materials so that the concentration of nitric acid is about 0.5 to 2%. The phosphoric acid film is formed on the surface of the lead-containing copper-based metal.

[0032] The lead-containing copper-based metal material according to claim 17 is a hexavalent chromium-free lead-containing copper-based metal material that is used without being subjected to plating. After elution and removal by the chromic acid etching treatment, hexavalent chromium formed on the surface of the lead-containing copper-based metal material by the chromic acid etching treatment is completely removed by a reduction treatment with a reducing agent aqueous solution for chromic acid. The phosphoric acid film is formed on the surface of the lead-containing copper-based metal material.

[0033] The surface of the lead-containing copper-based metal material includes the inner surface in addition to the outer surface in the case of a metal material having a space or an exposed portion inside, such as a tube material. For example, lead-containing copper When metal faucet fittings or parts for water pipes are used as the metal material, not only the outer surface but also the inner surface or exposed portion of the inner surface, the chromate etching treatment and the hexavalent Chromium removal treatment is performed, and the phosphoric acid film is formed.

[0034] The lead-containing copper-based metal material according to claim 18 is a hexavalent chromium-free lead-containing copper-based metal material that is used with a texture, and is an exposed internal surface portion or product of the lead-containing copper-based metal material The lead inside is eluted and removed by the chromic acid etching process, and hexavalent chromium formed on the plating surface of the lead-containing copper-based metal material by the chromic acid etching process is reduced by an aqueous reducing agent solution for chromic acid. After complete removal, a phosphoric acid film is formed on the plating surface of the lead-containing copper-based metal material.

[0035] Here, the surface of the lead-containing copper-based metal material includes the internal surface in addition to the external surface in the case of a metal material having a space or an exposed portion inside such as a tube material. For example, when brass-equipped faucets and water pipe parts are used as lead-containing copper-based metallic materials, the two-inch Kelmeki or chrome plating is formed only on the outer surface and the inner surface (product The internal chromic acid etching process is applied to the internal surface exposed part to expose the internal or internal surface of the lead-containing copper-based metal material. In addition, the hexavalent chromium removal treatment is applied not only to the external surface of the lead-containing copper-based metal material, but also to its internal surface, that is, the internal part of the product or the internal metal exposed part. In other words, a hexavalent chromium film is formed inside the product of the lead-containing copper-based metal material or in the exposed internal metal part in accordance with the chromium plating treatment or the chromic acid etching treatment. The removal treatment is applied not only to the external surface (plated surface) of the lead-containing copper-based metal material, but also to the inside of the product or the exposed internal surface (base surface). In addition to the external surface (plated surface) of lead-containing copper-based metal materials, it is also applied to the inside of the product or the exposed internal surface (base surface).

[0036] The hexavalent chromium-free surface treatment method according to claim 19 is a hexavalent chromium-free surface treatment method for a base material on which a hexavalent chromium film is formed by surface treatment using chromium. A hexavalent chromium film is formed on the surface by the reducing agent aqueous solution containing the reducing agent for chromic acid. The hexavalent chromium film on the surface of the substrate is completely removed.

[0037] Here, in the case of a base material having a space or an exposed portion inside, such as a tube material, the surface of the base material includes the internal surface in addition to the external surface. For example, when faucet fittings or parts for water pipes made of brass or the like are used as the base material, the hexavalent chromium is removed not only on the outer surface but also on the inner surface or the exposed inner surface. Will be given.

[0038] As the substrate, any substrate can be used as long as a hexavalent chromium film is formed on the surface by a surface treatment using chromium. For example, as a base material, a metal material such as an iron-based metal material or a copper-based metal material on which a hexavalent chromium film is formed on the surface by a surface treatment such as chromic acid etching treatment, chromate treatment, or chromium plating treatment may be used. it can. As the metal material, use a metal material as it is (that is, a non-metal product that does not have a metal surface), or a metal product that has a metal surface such as hard chrome or nickel chrome metal. Can do. Further, as the base material, in addition to the metal material, a non-metal material such as a resin material such as a thermoplastic synthetic resin or a thermosetting synthetic resin, or leather can be used. That is, the present invention can be applied to leather products and plastic products to which chrome plating is applied. Alternatively, as a base material, a coated product can be used in addition to the metal product. Furthermore, the present invention can be applied to various products such as faucet fittings and water supplies as well as automobile parts.

[0039] The hexavalent chromium-free surface treatment method according to claim 20 is a hexavalent chromium-free surface treatment method for a base material on which a hexavalent chromium film is formed by surface treatment using chromium. A hexavalent chromium removal step of completely removing the hexavalent chromium film on the surface of the base material on which the hexavalent chromium film is formed by a reducing agent aqueous solution containing a reducing agent for chromic acid; And a surface modification treatment step for modifying the surface of the base material from which is removed.

[0040] Here, in the case of a base material having a space or an exposed portion inside, such as a tube material, the surface of the base material includes not only its external surface but also its internal surface. For example, when faucet fittings or parts for water pipes made of brass or the like are used as the base material, the hexavalent chromium removing process is performed not only on the outer surface but also on the inner surface or the exposed inner surface. The treatment and the surface modification treatment step are performed. [0041] As the base material, any material can be used as long as a hexavalent chromium film is formed on the surface by a surface treatment using chromium. For example, as a base material, a metal material such as an iron-based metal material or a copper-based metal material on which a hexavalent chromium film is formed on the surface by a surface treatment such as chromic acid etching treatment, chromate treatment, or chromium plating treatment may be used. it can. As the metal material, use a metal material as it is (that is, a non-metal product that does not have a metal surface), or a metal product that has a metal surface such as hard chrome or nickel chrome metal. Can do. Further, as the base material, in addition to the metal material, a non-metal material such as a resin material such as a thermoplastic synthetic resin or a thermosetting synthetic resin, or leather can be used. That is, the present invention can be applied to leather products and plastic products to which chrome plating is applied. Alternatively, as a base material, a coated product can be used in addition to the metal product. Furthermore, the present invention can be applied to various products such as faucet fittings and water supplies as well as automobile parts.

The invention's effect

[0042] Since the hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 1 is configured as described above, in a product using lead-containing metal as a raw material, the elution of lead after commercialization is ensured. It can be prevented, and the elution amount of hexavalent chromium can be reduced to zero, and the corrosion resistance of the surface can be improved to prevent discoloration and the like.

[0043] The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 2 includes, in addition to the effect of claim 1, a hexavalent chromium removal step! By completely removing chromium, the elution amount of hexavalent chromium can be reduced to zero.

[0044] The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 3 is based on the effect of claim 1 or 2, and the surface of the lead-containing metal material is removed during the hexavalent chromium removal step. By reducing hexavalent chromium, hexavalent chromium becomes trivalent chromium. In addition, trivalent chromium adhering to the surface of the lead-containing metal material is further separated and removed from the surface of the lead-containing metal material by washing with water in the water-washing process, so that the elution amount of hexavalent chromium is zero. be able to.

[0045] In addition to the effect of any one of claims 1 to 3, the hexavalent chromium-free method for treating a lead-containing metal material according to claim 4 is more effective in the hexavalent chromium removing step. Reduction processing can be performed. [0046] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 5 is based on the effect of any one of claims 1 to 4, and the lead-containing metal material in the surface modification treatment step. A strong phosphoric acid film can be reliably formed on the surface.

[0047] Since the hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 6 is configured as described above, in a green product made of lead-containing copper-based metal, Elution can be prevented with certainty, and the elution amount of hexavalent chromium can be reduced to zero, and the corrosion resistance of the substrate surface can be improved to prevent discoloration and the like.

[0048] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 7 is based on the effect of claim 6, and the lead-containing copper-based metal material is used in the hexavalent chromium removal step. By completely removing hexavalent chromium from the substrate surface, the elution amount of hexavalent chromium can be made zero.

[0049] The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 8 is based on the effect of claim 6 or 7, and the lead-containing copper-based metal material is used in the hexavalent chromium removal step. By reducing hexavalent chromium on the substrate surface, hexavalent chromium becomes trivalent chromium. In addition, trivalent chromium force adhering to the substrate surface of lead-containing copper-based metal materials. Further, the surface force of the lead-containing copper-based metal material is completely separated and removed by washing in the water washing process, so that the elution amount of hexavalent chromium Can be set to zero.

[0050] Since the hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 9 is configured as described above, in a plating product made of lead-containing copper-based metal, Elution can be prevented with certainty, and the elution amount of hexavalent chromium can be reduced to zero, and the corrosion resistance of the plating surface can be improved to prevent discoloration and the like.

[0051] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 10 is based on the effect of claim 9, and the lead-containing copper-based metal material is used in the hexavalent chromium removal step. By completely removing the hexavalent chromium on the surface, the elution amount of hexavalent chromium can be made zero.

[0052] In addition to the effect of claim 9 or 10, the hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 11 adds the hexavalent surface of the lead-containing copper-based metal material in the hexavalent chromium removal step. By reducing chromium, hexavalent chromium becomes trivalent chromium. In addition, the trivalent chromium force adhering to the surface of the lead-containing copper-based metal material. Furthermore, the surface force of the lead-containing copper-based metal material is completely separated and removed by rinsing in the water washing process, thereby reducing the elution amount of hexavalent chromium. Can be zero wear.

[0053] In addition to the effect of claim 11, the hexavalent chromium-free surface treatment method according to claim 12 completely removes hexavalent chromium from the surface of the lead-containing copper-based metal material in the hexavalent chromium removal step. However, the elution amount of hexavalent chromium can be made zero by making the surface of the lead-containing copper-based metal material a chromium surface.

[0054] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 13 is based on the effect of claim 6 or 9, and the lead-containing copper-based metal is used in the hexavalent chromium removal step. By completely removing hexavalent chromium from the surface of the material and making the surface of the lead-containing copper-based metal material a chromium surface, the elution amount of hexavalent chromium can be made zero. That is, the trivalent chromium adhering to the surface of the lead-containing copper-based metal material is completely separated and removed by the water washing process, and the surface of the lead-containing copper-based metal material is made of only chromium plating and has no hexavalent chromium or trivalent chromium. It can be a perfect chrome surface, ie a zero-valent chrome surface.

[0055] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 14 is based on the effect of any one of claims 6 to 13, and is more effective in the hexavalent chromium removal step. Hexavalent chromium can be reduced.

[0056] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 15 is based on the effect of any one of claims 6 to 14, and the lead-containing copper-based metal material in the surface modification treatment step. A strong phosphoric acid film can be reliably formed on the surface of the metal material.

[0057] A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 16 is based on the effect of any one of claims 6 to 14, and the lead-containing copper-based metal material in the surface modification treatment step. A strong phosphoric acid film can be more reliably formed on the surface of the metal material.

[0058] Since the lead-containing copper-based metal material according to claim 17 is configured as described above, the lead-containing copper-based metal material is used for products made of lead-containing copper-based metal (boron) that is used without being plated. In addition to being able to reliably prevent the elution of lead after commercialization, the elution amount of hexavalent chromium can be reduced to zero, and the corrosion resistance of the substrate surface can be improved to prevent discoloration and the like. .

[0059] Since the lead-containing copper-based metal material according to claim 18 is configured as described above, in a product made of lead-containing copper-based metal (mesh product) used as a material, Elution of lead can be reliably prevented, and the elution amount of hexavalent chromium can be reduced to zero. It is possible to improve the corrosion resistance of the plating surface and reliably prevent discoloration and the like.

[0060] Since the hexavalent chromium-free surface treatment method according to claim 19 is configured as described above, in a product made of a base material having a hexavalent chromium film formed on the surface by a surface treatment using chromium. The elution amount of hexavalent chromium after commercialization can be made zero.

[0061] Since the hexavalent chromium-free surface treatment method according to claim 20 is configured as described above, in a product made of a base material having a hexavalent chromium film formed on the surface by a surface treatment using chromium. Thus, the elution amount of hexavalent chromium after commercialization can be made zero, and the corrosion resistance of the surface can be improved to prevent discoloration and the like.

Brief Description of Drawings

FIG. 1 is a process diagram showing a series of steps of a hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 1 of the present invention.

[FIG. 2] FIG. 2 is a schematic diagram showing changes in the surface state of the lead-containing copper-based metal material by the hexavalent chromium-free surface treatment method for the lead-containing copper-based metal material according to Embodiment 1 of the present invention. a) shows a state in which a hexavalent chromium film is formed on the surface of the tin-containing copper-based metal material in the chromic acid etching process, and (b) shows a surface of the lead-containing copper-based metal material in the hexavalent chromium removal process. (C) shows the surface strength of the lead-containing copper-based metal material in the water washing process after the hexavalent chromium removal process. (D) shows a state in which a phosphate film is formed on the surface of the base material of the lead-containing copper-based metal material in the surface modification treatment step.

FIG. 3 is a process diagram showing a series of steps of a hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 2 of the present invention.

[FIG. 4] FIG. 4 is a schematic diagram showing changes in the surface state of the lead-containing copper-based metal material according to the hexavalent chromium-free surface treatment method for the lead-containing copper-based metal material according to Embodiment 2 of the present invention. a) shows the state of the super bright nickel plating formed on the surface of the lead-containing copper-based metal material in the ultra-bright nickel plating process, and (b) shows the super-bright nickel plating of the lead-containing copper-based metal material in the bright nickel plating process. (C) shows a state in which a bright nickel plating is formed on the surface. In the chromium plating process, a chromium plating is formed on the bright nickel plating surface of the lead-containing copper-based metal material, and in the chromium etching process, the chromium plating surface is formed. Hexavalent chromium film (D) shows the state in which the hexavalent chromium film on the plating surface of the lead-containing copper-based metal material has been reduced in the hexavalent chromium removal process, and (e) shows the state after the hexavalent chromium removal process. The chromium plating surface strength of lead-containing copper-based metal materials in the water-washing process The state in which trivalent chromium was washed with water and became a zero-valent chromium surface. The state where the phosphoric acid film was formed on the chrome plating surface is shown.

Explanation of symbols

S1: Alkali cleaner ultrasonic cleaning process, S2: First water cleaning process after alkaline cleaner ultrasonic cleaning

53: Second water washing process after ultrasonic cleaning of alkaline cleaner

54: Chromic acid etching process (chromic acid treatment process)

S5: First recovery process, S6: Second recovery process, S8: Hexavalent chromium removal process

S9: Water washing process after hexavalent chromium removal, S 10: Surface modification treatment process

S11: First water washing process after the surface modification treatment process

S12: Second water washing process after the surface modification process

S15: Hot water washing process, S16: Drying process

S21: Alkaline cleaner ultrasonic cleaning process

522: First water washing process after ultrasonic cleaning of alkaline cleaner S22

523: Second water washing process after ultrasonic cleaning of alkaline cleaner

S24: (1) Electrolytic degreasing process, S25: (+) Electrolytic degreasing process

S26: First washing process after electrolytic degreasing, S27: Second washing process after electrolytic degreasing

S28: First active acid treatment process

S29: Washing process after the first active acid treatment, S30: Super bright nickel plating process

S31: First recovery process after super bright nickel plating

S32: Second recovery process after super bright nickel plating

S33: Bright nickel plating process, S34: Recovery process after bright nickel plating

535: First water washing process after bright nickel plating

536: 2nd water washing process after bright nickel plating S37: Second active acid treatment step, S38: Water washing step after second active acid treatment

539: Chromic acid activation treatment process (chromic acid treatment process)

540: Chrome plating process (chromic acid etching process)

S41: First recovery process after chrome plating

S42: Second recovery process after chrome plating

S44: Hexavalent chromium removal process, S45: Water washing process after hexavalent chromium removal

S46: Surface modification process

547: First water washing process after the surface modification process

548: Second water washing process after surface modification treatment process

S50: Hot water washing process, S52: Drying process

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described.

Throughout the embodiments, the same members, elements or parts are denoted by the same reference numerals, and the description thereof is omitted.

[0065] Embodiment 1 (substrate surface treatment)

Hereinafter, a hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 1 of the present invention will be described. FIG. 1 is a process diagram showing a series of steps of a hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing changes in the surface state of the lead-containing copper-based metal material according to the hexavalent chromium-free surface treatment method for the lead-containing copper-based metal material according to Embodiment 1 of the present invention. (B) shows a hexavalent chromium film on the surface of the lead-containing copper-based metal material in the hexavalent chromium removal process. (C) shows a state in which the trivalent chromium is washed with water in the water washing process after the hexavalent chromium removal process. Shows a state in which a phosphoric acid film was formed on the surface of the lead-containing copper-based metal material in the surface modification process.

[0066] The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 1 includes a lead-containing copper-based metal material formed into a predetermined shape by forging or the like, for example, a free-cutting brass flush fitting In addition to preventing the elution of lead from the surface of the fabricated product's base material and making it lead-free, it also prevents the elution of hexavalent chromium from the surface of the base material, making it free of hexavalent chromium, A film is formed to improve corrosion resistance (discoloration prevention function, etc.). Specifically, the hexavalent chromium-free surface treatment method for the lead-containing copper-based metal material according to Embodiment 1 is performed as shown in FIG. 1 in the alkaline cleaner ultrasonic cleaning step Sl and after the alkaline cleaner ultrasonic cleaning. 1st water washing process S2, 2nd water washing process S3 after alkali cleaner ultrasonic cleaning, chromic acid etching process S4 as chromic acid treatment process, 1st recovery process S5, 2nd collection process S6, hexavalent chromium removal process S7, water washing process after hexavalent chromium removal S8, surface modification treatment process S9, surface modification treatment process S1 first water washing process after S9 S10, surface modification treatment process It consists of the second water washing step Sl 1 after S9, the hot water washing step SI 2 and the drying step SI 3. Hereinafter, each process will be described.

[0067] [Alkaline cleaner ultrasonic cleaning process]

First, the lead-containing copper-based metal material is cleaned of the substrate surface (including the exposed internal surface) by ultrasonic cleaning with an alkaline cleaner in the alkaline cleaner ultrasonic cleaning step S1. At this time, since the lead component contained in the base surface portion of the lead-containing copper-based metal material dissolves in both alkali and acid, the alkali-cleaner in this alkaline cleaner ultrasonic cleaning process performs the lead-containing copper-based metal material. Most of the lead components present on the surface of the material are eluted and removed.

[0068] [Washing process]

The lead-containing copper-based metallic material is subjected to the alkaline cleaner ultrasonic cleaning process S1 in the alkaline cleaner ultrasonic cleaning process S1, then pulled up from the alkaline cleaner ultrasonic cleaning tank, and the first time after the alkaline cleaner ultrasonic cleaning. It is sent to the water washing step S2, and after being immersed in the first water washing tank for a predetermined time, it is pulled up, and further sent to the second water washing step S3 after the alkaline cleaner ultrasonic washing, and the second water washing tank. After being dipped in a predetermined time, it is pulled up. As a result, the surface of the substrate (internally exposed surface) is contained in the alkaline cleaner ultrasonic cleaning liquid adhering to the surface of the lead-containing copper-based metal material (including the exposed internal surface) or the alkaline cleaner ultrasonic cleaning liquid. In the first and second rinsing tanks, the elution lead components adhering to (including) are sequentially removed by rinsing to clean the surface of the lead-containing copper-based metal material. [0069] [chromic acid etching process (chromic acid treatment process)]

Next, the lead-containing copper-based metal material is immersed in a chromic acid etching tank storing a chromic acid etching solution (aqueous solution) at a predetermined temperature for a predetermined time in the chromic acid etching process S4 as the chromic acid treatment process. . Specifically, as the chromic acid etching solution in the chromic acid etching step S4, for example, an aqueous solution of chromic anhydride (CrO 2) is used. Chromic acid

Three

The bath composition of the etchant is, for example, that only chromic anhydride (CrO) is added to water (H 2 O).

2 3 Mixed at a fixed ratio, or chromic anhydride (CrO) and sulfuric acid (water)

twenty three

H 2 SO 4) can be mixed at a predetermined ratio. Or chromic acid etching

twenty four

In step S4, other chromic acid etching solutions for copper and copper alloys (for example, dichromate aqueous solution, fluorine compound, etc.) can also be used. At this time, since the chromic acid aqueous solution contained in the chromic acid etching solution is strongly acidic, the entire surface of the lead-containing copper-based metal material (including the exposed internal surface) is dissolved and contained in the surface. It also dissolves lead components. As a result, the remainder of the lead component existing on the base surface portion of the lead-containing copper-based metal material is eluted and removed in the chromic acid etching solution.

[0070] [Recovery process]

After the chromic acid etching step S4, the lead-containing copper-based metal material is lifted from the chromic acid etching tank, sent to the next first collection step S5, and immersed in the first collection water tank for a predetermined time. Pulled up, sent to the next second recovery step S6, crushed for a predetermined time in the second recovery tank, and then lifted. As a result, the chromic acid etching solution (including chromic acid) adhering to the surface of the lead-containing copper-based metal material (including the exposed internal surface) is sequentially recovered in the first recovery water tank and the second recovery water tank, The substrate surface of the lead-containing copper-based metal material is completely cleaned. At this time, a gel-like hexavalent chromium film containing hexavalent chromium (Cr ⁶⁺ ) is inevitably formed on the substrate surface of the lead-containing metal material (the outer substrate surface and the inner substrate surface).

[0071] The change of the base surface of the lead-containing copper-based metal material (Cu) due to the reaction at this time is schematically explained. As shown in Fig. 2 (a), the chromic acid etching process S4 to the recovery processes S5, S6 In this case, a gel-like composite hydrated oxide film (XCrO—YCrO · ΖΗΖΗ) is formed on the surface of the lead-containing copper-based metal material (Cu). Note that after the chromic acid etching step S4, Romic acid etching tank power A large amount of chromic acid etching solution adheres to the surface of the raised tin-containing copper-based metal (Cu). However, the chromic acid etchant adhering to the substrate surface of lead-containing copper-based metal (Cu) is removed in the first and second recovery tanks in the first and second recovery steps S5 and S6. And released into the water.

[0072] [Reaction Formula]

Alternatively, at this time, it can be considered that the hexavalent chromium film is formed on the surface of the lead-containing copper-based metal material by the following reaction formula, for example.

(1) CrO + H O H CrO

3 2 2 4

(2) 2H CrO H Cr O + H O

2 4 2 2 7 2

(3) Cr O ² — + 14H ++ 3Cu 2Cr ³⁺ + 3Cu ²⁺ + 7H O

2 7 2

(4) Cr ³⁺ + 3H O Cr (OH) + 3H +

twenty three

(5) 2Cr (OH) + CrO ² — + 2H + Cr (OH) + Cr (OH) -CrO -HO

3 4 3 4 2

[0073] [Washing process]

After the two recovery steps S5 and S6, the lead-containing copper-based metal material is sent to the water washing step S7, crushed in the water washing tank for a predetermined time, and then pulled up. As a result, the chromic acid etching solution and other deposits remaining on the surface of the lead-containing copper-based metal material (including the exposed surface inside) are removed by washing with a water-washing tank, and the surface of the lead-containing copper-based metal material is removed. Furthermore, it is completely cleaned. The water washing step S7 can be omitted as necessary.

[0074] [Hexavalent chromium removal process]

After the recovery process S5, S6, the water washing process S7, the lead-containing copper-based metal material is pulled up from the water washing tank, and in the hexavalent chromium removal process S8, the reducing tank that stores the reducing agent aqueous solution at a predetermined temperature ( Dipped in a reducing bath) for a predetermined time. Examples of the reducing agent for chromic acid in the reducing bath of the hexavalent chromium removal step S8 include sodium hyposulfite (Na 2 S 2 O 3) and sodium nitrite (

2 2 5

Na S O), sodium thiosulfate (Na S O), sodium sulfite (Na SO), etc.

2 2 4 2 2 3 2 3

Can. In addition, as sodium hyposulfite (Na S O), for example, Daito Chemical Co., Ltd.

2 2 5

You can use the product name Sorbis of the formula company. In addition, sodium nitrite (Na

2

S O) is, for example, the product name Hydrosulfite Conk of Guangei Chemical Industry Co., Ltd.

twenty four

Can be used. And sodium hyposulfite, sodium dithionite, etc. 1 A sodium sulfite aqueous solution having a predetermined concentration in which seeds or more are dissolved can be prepared to make a reducing bath. For example, an aqueous reducing agent solution can be prepared by stirring and dissolving sodium nitrite at a rate of about 5 to 10 gZl in water. Note that the concentration of the reducing agent in the reducing bath can be in the range of several gZi to several lOgZi, and is preferably determined as appropriate depending on the combination of components to be used. Preferably, the reducing agent concentration in the reducing bath is in the range of about 2-5%, more preferably in the range of about 3-5%. Alternatively, as described above, the reducing agent concentration in the reducing bath is preferably about 5 to 10 gZl. The temperature of the reducing bath can be room temperature, but it is preferable to adjust the temperature appropriately depending on the reaction rate. Furthermore, the immersion time of the lead-containing copper-based metal material in the reduction bath can be in the range of about 20 to 30 seconds, but it is preferable to adjust the temperature appropriately depending on the reaction rate. Here, it is also preferable to adjust the pH of the reducing bath.For example, in the case of sodium hyposulfite (Na 2 SO 4),

2 2 5

Add sulfuric acid (H 2 SO 4) to the original bath and adjust the pH so that the pH is in the range of 2 to 3.

twenty four

Good. Alternatively, for example, in the case of sodium dithionite (Na 2 S 2 O 3), the reducing bath is neutral p

2 2 4

Power capable of exerting reducing power as H It is also possible to adjust the pH of the reducing bath to be alkaline so that the reducing power can be exerted strongly.

[0075] When the lead-containing copper-based metal material is immersed in the reducing bath in the hexavalent chromium removing step S8, the lead-containing copper-based metal material is formed on the substrate surface (including the exposed surface inside) in the chromic acid etching step S4. Hexavalent chromium as a film component is completely removed. Specifically, when a lead-containing copper-based metal material is immersed in a reducing bath, the hexavalent chromium (Cr ⁶⁺ ) film on the surface of the lead-containing copper-based metal material is caused by the reducing agent for chromic acid in the reducing bath. It is reduced to trivalent chromium (Cr ³⁺ ), and the surface force of the lead-containing copper-based metal material is separated and released into the reduction bath. The trivalent chromium (Cr ³⁺ ) released from the surface strength of the lead-containing copper-based metal material and released into the reduction bath is finally adjusted to a neutral pH range with the reducing agent aqueous solution in the reduction bath. Etc., it can be recovered by precipitation in the reducing agent aqueous solution in the reducing bath.

[0076] The change of the substrate surface of the lead-containing copper-based metal material (Cu) due to the reaction at this time is schematically explained. As shown in Fig. 2 (b), the substrate of the lead-containing copper-based metal material (Cu) Gel-like composite hydrated oxide film (XCr O -YCrO · ΖΗ Ο) formed on the surface, that is, hexavalent chromium

2 3 3 2

The film is reduced with a reducing agent for chromic acid in the hexavalent chromium removing step S7, and trivalent chromium (Cr (O), and is presumed to be attached to the surface of the lead-containing copper-based metal (Cu).

Three

The That is, at this time, there is no hexavalent chromium on the surface of the lead-containing copper-based metal material (Cu), and the surface force of the lead-containing copper-based metal material (Cu) is completely removed. And!

[0077] [Washing process]

The lead-containing copper-based metal material is reduced in the hexavalent chromium removal step S8, then pulled up from the reduction tank, and immediately sent to the water washing step S9 after the hexavalent chromium removal, to the water washing tank for a predetermined time. It is pulled up after being immersed. As a result, trivalent chromium (Cr ³⁺ ) attached to the surface of the lead-containing copper-based metal material (including the exposed internal surface), for example, acid chrome (Cr 2 O 3)

2 3 It is removed in the tank and the base surface of the lead-containing copper-based metal material is cleaned. The changes in the surface of the lead-containing copper-based metal material (Cu) due to the reaction at this time can be schematically explained as shown in Fig. 2 (c). The adhering trivalent chromium (Cr 2 O 3)

twenty three

All of the surface strength of the lead-containing copper-based metal material (Cu) is completely separated and released into the water by washing in the washing tank in the washing step S9. That is, not only hexavalent chromium does not exist at all on the surface of the lead-containing copper-based metal material (Cu), but also all trivalent chromium is removed and no longer exists.

[0078] [Reaction Formula]

In the hexavalent chromium removal step S8, sodium hyposulfite (Na 2 S 2 O 3) as a reducing agent

When 2 2 5 is used, sodium bisulfite (Na S O)

2 2 5

HSO), for example, by the following reaction formula:

Three

It is assumed that chromium (4CrO ² or 4H CrO) is reduced to trivalent chromium (2Cr (SO)).

4 2 4 4 3

Tochidaru.

4CrO ² — + 6NaHSO + 3H SO 2Cr (SO) + 3Na SO + 10H O

4 3 2 4 4 3 2 4 2

[0079] Further, in the hexavalent chromium removing step S8, sodium hyposulfite (Na 2 S 2 O 3) is used as a reducing agent.

When it is put into the aqueous solution in the reduction tank as it is, the hexavalent chromium (4CrO ² or 4H CrO) on the surface of the lead-containing copper-based metal material is converted to trivalent chromium (2Cr ( S

4 2 4

o) It can be thought that it will be reduced to).

4 3

4H CrO + 3Na SO + 3H SO 2Cr (SO) + 3Na SO + 7H O [0080] At this time, hexavalent chromium (Cr ^{b +} ) was sulfated into sodium hydrogen sulfite (NaHSO) in a reduction bath.

3 Even if acid (H 2 SO 4) is added to adjust the pH to between 2 and 3, as the above reaction proceeds

twenty four

The pH in the reducing bath increases and the reaction may stop near neutrality. This is sulfuric acid (H SO

twenty four

) Dissociates into 2H + and SO ² in the reducing agent aqueous solution and supplies protons (H +).

Four

Proceeds to the right (→;), and the reaction stops when the supply of protons ends. Therefore, in this case, it is preferable to monitor the pH of the reducing bath and periodically add sulfuric acid to maintain the pH between pH 2-3.

[0081] Water treatment process

In the recovery steps S5 and S6, hexavalent chromium is present in the water in the recovery tank. In the hexavalent chromium removing step S8, trivalent chromium is present in the reducing agent aqueous solution in the reducing tank. Furthermore, in the washing step S9, trivalent chromium exists in the water of the washing tank. Therefore, although not shown, a wastewater treatment process is required for the drainage of the recovery tank, reduction tank, and washing tank. That is, in the case of the recovery tank, hexavalent chromium is contained in the water, so the reducing agent such as sodium hyposulfite is added to the waste water to make it water-soluble, and the hexavalent chromium is reduced to trivalent chromium. Then, add sodium hydroxide (NaOH) to the wastewater to adjust the pH of the wastewater to a neutral range, or add a flocculant etc. to the wastewater to coagulate and precipitate trivalent chromium in the wastewater. Let Then, the supernatant portion of the wastewater (does not contain trivalent chromium !, clean water) and the precipitate portion are separated and taken out for reuse or disposal. In the case of the reducing tank and water washing tank, trivalent chromium is contained in the reducing agent aqueous solution and in the water. Therefore, sodium hydroxide (NaOH) is added to the wastewater to make the pH of the wastewater neutral. Adjust or add a coagulant to the wastewater to coagulate and precipitate the trivalent chromium in the wastewater. Then, the supernatant part of the wastewater (clean water not containing trivalent chromium) and the precipitate part are separated and taken out and reused or discarded. For example, in the case of the above reaction formula (a) or (b), chromium sulfate dissolved in an aqueous reducing agent solution (2Cr (SO 2)

4 3

) Is neutralized with sodium hydroxide (NaOH), etc., and precipitated in solution as sodium hydroxide, and then filtered off. The filtrate is drained and the precipitate (chromium hydroxide) It can be disposed of as waste, such as by dehydration.

[0082] [Surface modification treatment step]

After the water washing step S9, the lead-containing copper-based alloy material is sent to the surface modification treatment step S10, By the acid film treatment, the base surface (including the exposed internal surface) of the lead-containing copper-based metal material from which hexavalent chromium has been removed is modified. Specifically, in the surface modification treatment step S10, the lead-containing copper-based alloy material is immersed in a chemical conversion treatment tank that stores a mixed acid aqueous solution at a predetermined temperature for a predetermined time. As the mixed acid aqueous solution of the chemical conversion treatment layer in the surface modification treatment step S10, for example, a mixed acid aqueous solution in which phosphoric acid to orthophosphoric acid (H 3 PO 4) and nitric acid (HNO 3) are dissolved as main materials is used.

3 4 3

Can. From the viewpoint of good formation of a phosphoric acid film, the concentration of phosphoric acid is preferably in the range of about 2 to 5%. The nitric acid concentration is preferably in the range of about 0.5 to 2%. That is, nitric acid in a mixed acid aqueous solution is used for the purpose of promoting or promoting the formation of a phosphoric acid film on the surface of a lead-containing copper-based metal by phosphoric acid by exerting a chemical polishing function or the like. However, if the concentration of nitric acid is less than about 0.5, it will not be able to perform its full function.On the other hand, if the nitric acid concentration exceeds about 2%, it may affect the appearance of the final product of lead-containing copper-based metals. is there. Furthermore, if the concentration of phosphoric acid and mixed acid is set within the above range, not only the lead-containing copper-based metal material is not subjected to plating, but also a phosphoric acid film is applied to the surface of the substrate, and the lead-containing copper-based metal material is nickel-coated. Even when a plating or nickel chrome plating is applied to form a phosphoric acid coating on the surface of the plating, a good phosphoric acid coating can be applied to the surface and the appearance of the final product can be maintained well. On the other hand, the temperature of the chemical conversion bath may be, for example, in the range of about 40-60 ° C or about 40-80 ° C. Furthermore, the immersion time of the lead-containing copper-based metal material in the chemical conversion bath can be, for example, in the range of about 20 seconds to 3 minutes or about 30 seconds to 3 minutes. The temperature of the chemical conversion treatment bath and the immersion time of the lead-containing copper-based metal material are determined relative to each other. When the temperature of the chemical conversion treatment bath is set high, the immersion time of the lead-containing copper-based metal material is set short. When the temperature of the chemical conversion treatment bath is set low, it is preferable to set the immersion time of the lead-containing copper-based metal material long. For example, when the temperature of the chemical conversion treatment tank is about 40 ° C., the immersion time can be about 3 minutes, and when the temperature of the chemical conversion treatment layer is about 60 ° C., the immersion time can be about 20 seconds.

By immersing the lead-containing copper-based metal material in the chemical conversion treatment tank storing an aqueous solution of a mixed acid containing phosphoric acid (orthophosphoric acid) and nitric acid at a predetermined concentration, the lead-containing metal material is immersed on the surface of the substrate. A phosphate film with a predetermined thickness is formed, and the desired functions such as anti-corrosion and discoloration prevention functions are exhibited. Note that the mixed acid aqueous solution in the chemical conversion treatment tank contains phosphoric acid and In addition to nitric acid, an inorganic dispersion such as silica may be added as an additive. The change in the substrate surface of the lead-containing copper-based metal material (Cu) due to the reaction at this time is schematically explained. As shown in Fig. 2 (d), the substrate surface of the lead-containing copper-based metal material (Cu) (six It is presumed that the lead-containing copper-based metal (Cu) and phosphoric acid react with each other to form a predetermined phosphoric acid coating (H PO) on the base surface where no valent chromium or trivalent chromium exists. The

3 4

Alternatively, it may be considered that the surface modification treatment (i-formation treatment) of the copper or copper alloy in the surface modification treatment step S10 is performed as follows. First, as a first step, the surface of copper or copper alloy is melted by nitric acid contained in the mixed acid aqueous solution, and immediately after that, an oxide film is formed on the surface of copper or copper alloy. This acid film is considered to be acid cuprous (Cu 2 O).

2

The Further, the reaction at this time is considered to proceed as shown in the following reaction formula.

4Cu + 4HNO → 4Cu ²⁺ + 2H O + 30 + 4NO † →

3 2 2

2Cu 0 + 2H 0 + 20 + 4NO †

2 2 2

Next, as a second stage, reaction with phosphoric acid proceeds on the surface of copper or copper alloy. Although the details of the reaction with phosphoric acid are unknown, it is considered that some of the phosphate trihydrate is formed, and the reaction proceeds as shown in the following reaction formula.

6Cu + 4H PO + 30 → 2Cu (PO) + 6H O →

3 4 2 3 4 2 2

2 (Cu (PO) 6Η O)

3 4 2 2

[0085] [Washing process]

The lead-containing copper-based metal material is subjected to a phosphoric acid film treatment in the surface modification treatment step S10, then lifted from the chemical conversion treatment tank, and sent to the first water washing step S11 after the surface modification treatment step S10. Then, after being soaked in the washing tank for a predetermined time, it is pulled up, and further, sent to the second washing step S12 after the surface modification treatment step S10, and after being immersed in the washing tank for a predetermined time, it is pulled up. As a result, the mixed acid components adhering to the surface of the lead-containing copper-based metal material (including the exposed internal surface) are sequentially removed by water washing in the water washing tank of the water washing step S11 and the water washing tank of the water washing step S12. The surface of the lead-containing copper-based metal material is cleaned.

[0086] [Discoloration prevention treatment process]

Next, the lead-containing copper-based metal material is sent to the discoloration prevention treatment step S13 after the faucet steps S11 and S12, and stored in a discoloration prevention treatment tank storing a discoloration prevention agent such as an antifungal aqueous solution for a predetermined time. After being immersed, the substrate surface (including the exposed internal surface) is treated with anti-corrosion and discoloration. Examples of the antifungal agent or corrosion 'anti-discoloration agent at this time include, for example, benzotriazole (CH

6 5

N) can be used. This benzotriazole reacts with copper or copper alloys.

Three

Has become an insoluble Cu-benzotriazole complex. Here, the structural formula of Cu benzotriazole is CuC H N, and the structural formula of Cu + benzotriazole is Cu (

6 4 3

C H N). The discoloration prevention treatment step S13 is omitted as necessary.

6 3 3 2

I'll do it for you.

[0087] [Washing process]

The lead-containing copper-based metallic material is pulled up from the discoloration prevention treatment tank after the discoloration prevention treatment step S13, sent to the water washing step S14, and then pulled up after being immersed in the washing bath for a predetermined time. As a result, the discoloration inhibitor component adhering to the surface of the lead-containing copper-based metal material (including the exposed internal surface) is removed by washing in the water-washing tank, and the surface of the lead-containing copper-based metal material is cleaned. The water washing step S14 can be omitted when necessary, such as when the discoloration preventing treatment step S13 is omitted.

[0088] [Hot water washing process and drying process]

The lead-containing copper-based metal material was also washed out after the water washing step S14 after the discoloration prevention treatment step S13, and the color change prevention treatment tank was also lifted, sent to the hot water washing step S15, and immersed in the water washing bath for a predetermined time. Raised later. As a result, the discoloration inhibitor component adhering to the surface of the lead-containing copper-based metal material (including the exposed internal surface) is completely removed by washing in the water-washing tank, and the surface of the lead-containing copper-based metal material is completely removed. To be cleaned. Furthermore, after the lead-containing copper-based metal material is washed in the hot water washing step S15, it is lifted from the hot water washing tank, sent to the drying step S16, and forcedly dried by hot air or the like.

[0089] Thus, in the hexavalent chromium-free surface treatment method for lead-containing copper-based metallic materials according to Embodiment 1, hexavalent chromium exists in the form of stable ions, both acidic and alkaline. Focusing on the properties, in the hexavalent chromium removal step S8, the lead-containing copper-based metal material is immersed in the reducing agent aqueous solution in the reduction tank, and the hexavalent chromium on the substrate surface is reduced to trivalent chromium and dissolved in the reduction tank. The hexavalent chromium on the surface of the lead-containing copper-based metal material is selectively dissolved and removed by making it come out. Furthermore, the base surface of the lead-containing copper-based metal material after removal of hexavalent chromium remains unchanged In the surface modification treatment step S10, the lead-containing copper-based metal material is immersed in a mixed acid aqueous solution in the chemical conversion treatment tank to form a phosphate film on the substrate surface.

[0090] [Effect]

The hexavalent chromium-free surface treatment method for lead-containing copper-based metal materials according to Embodiment 1 can reliably prevent elution of lead after commercialization in a base product made of lead-containing copper-based metal materials. In addition, the elution amount of hexavalent chromium can be made zero, and the corrosion resistance of the substrate surface (including the internal exposed surface) can be improved to prevent discoloration and the like. In particular, pinholes and cracks that exist on the surface of internal substrates such as faucet fittings that contain lead-containing metal materials, or small gaps (micro gaps) that exist between internal parts, etc. Since the hexavalent chromium film that tends to remain in the gaps is completely removed by powerful pinholes, cracks, smile gaps, and complex shape gap forces, the faucet that is the lead-containing similar metal material of this embodiment The possibility of elution or leaching of hexavalent chromium with the use of equipment, etc. can be completely prevented. In particular, the hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 1 can completely remove hexavalent chromium, which is an environmentally hazardous substance, and has excellent corrosion resistance. It can be suitably used as a surface treatment method for alloys and the like. In addition, a conventional surface treatment plant for water supplies can be used as it is, and the cost is not increased.

[0091] Embodiment 2 (Metsuki surface treatment)

Hereinafter, a hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 2 of the present invention will be described. FIG. 3 is a process diagram showing a series of steps of a hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 2 of the present invention. FIG. 4 is a schematic diagram showing changes in the surface state of the lead-containing copper-based metal material by the hexavalent chromium-free surface treatment method for the lead-containing copper-based metal material according to Embodiment 2 of the present invention. (B) shows the state of super bright nickel plating formed on the surface of the lead-containing copper-based metal material in the bright nickel plating process. (C) shows the state where the nickel plating is formed. In the chromium plating process, when the chromium plating is formed on the surface of the bright nickel plating of the lead-containing copper-based metal material, the nickel plating is also formed on the surface of the chromium plating. Hexavalent chromium film formed (D) shows the state in which the hexavalent chromium film on the plating surface of the lead-containing copper-based metal material has been reduced in the hexavalent chromium removal process, and ( _e ) shows the lead content in the water washing process after the hexavalent chromium removal process. (F) shows the state in which the trivalent chromium was washed with water from the chrome plating surface of the copper-based metal material and became a zero-valent chrome surface. The state where the film is formed is shown.

[0092] A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to Embodiment 2 includes a lead-containing copper-based metal material formed into a predetermined shape by forging or the like, for example, a free-cutting brass flush fitting In nickel-chromium plating products, lead elution is prevented from the chromium plating surface to make it lead-free, and hexavalent chromium from the chromium plating surface is also prevented from elution, making it hexavalent chromium-free. An acid film is formed to improve corrosion resistance (discoloration prevention function, etc.). Specifically, the hexavalent chromium-free surface treatment method for the lead-containing copper-based metal material according to Embodiment 2 is performed as shown in FIG. 3 in the alkaline cleaner ultrasonic cleaning step S21, the first after the alkaline cleaner ultrasonic cleaning. 2nd water washing process S22, alkaline cleaner 2nd water washing process after ultrasonic cleaning S23, (-) Electrolytic degreasing process S24, (+) Electrolytic degreasing process S25, 1st water washing process after electrolytic degreasing S26, electrolysis 2nd water washing process S27 after degreasing, 1st active acid treatment process S28, 1st water washing process after active acid treatment S29, super bright nickel plating process S 30, first after super bright nickel plating Second recovery process S31, second recovery process after super bright nickel plating S32, bright nickel plating process S33, recovery process after bright nickel plating S34, first water washing process S35 after bright nickel plating, Second after bright nickel plating Water washing step S36 for the second, acid treatment step S37 for the second time, water washing step S38 after the second active acid treatment, chromic acid activation treatment step S39 for the chromic acid treatment step, chrome plating step S40, after chrome plating First recovery step S41, second recovery step after chromium plating S42, hexavalent chromium removal step S43, water washing step after hexavalent chromium removal S44, surface modification treatment step S45, surface modification treatment step S 45 It consists of a subsequent first water washing step S46, a surface modification treatment step S45, a second water washing step S47, a hot water washing step S48, and a drying step S49.

[0093] [Alkali cleaner ultrasonic cleaning process]

The lead-containing copper-based metal material is first treated with an alkali cleaner ultrasonic cleaning step S21. The substrate surface (including the exposed internal surface) is cleaned by ultrasonic cleaning with a force recleaner. At this time, since the lead component contained in the base surface portion of the lead-containing copper-based metal material dissolves in both alkali and acid, the alkali-cleaner in this alkaline cleaner ultrasonic cleaning process performs the lead-containing copper-based metal material. Most of the lead components present on the surface of the material are eluted and removed.

[0094] [Washing process]

The lead-containing copper-based metal material is subjected to the alkaline cleaner ultrasonic cleaning process in the alkaline cleaner ultrasonic cleaning step S21, and then sent to the first water cleaning step S22 after the ultrasonic cleaning of the alkali cleaner, in the first water washing tank. Then, it is pulled up after being soaked for a predetermined time, and further sent to the second water washing step S23 after ultrasonic cleaning of the alkali cleaner, and after being soaked in the second water washing tank for a predetermined time, it is pulled up. As a result, alkaline cleaner components adhering to the substrate surface (including the exposed internal surface) of the lead-containing copper-based metal material, and elution lead components adhering to the substrate surface in the form contained in the alkaline cleaner, etc. The surface of the lead-containing copper-based metal material is cleaned in the tank and the second washing tank.

[0095] [Electrolytic degreasing step-active acid treatment step-water washing step]

Next, the lead-containing copper-based metal material is subjected to electrolytic degreasing treatment in order in (1) electrolytic degreasing step S24 and (+) electrolytic degreasing step S25. Next, the lead-containing copper-based metal material is immersed in the third and 34th water rinsing tanks in the first water washing step S26 and the second water washing step S27 after electrolytic degreasing, and the substrate surface is sequentially washed. The Next, in the first active acid treatment step S28, the lead-containing copper-based metal material is subjected to an acid activation treatment with an active acid to remove smut and the like on the substrate surface. Next, the lead-containing copper-based metal material is immersed in a fifth washing tank in the washing step S29 after the first active acid treatment, and the substrate surface is washed.

[0096] [Super bright nickel plating process-second active acid treatment process-water washing process]

Next, in the lead-containing copper-based metallic material, in the super bright nickel plating process S30, as shown in FIG. 4 (a), super bright nickel plating is formed on the substrate surface (only the outer surface). Next, the lead-containing copper-based metallic material is sent to the first recovery step S31 after the super bright nickel plating, dipped in the first recovery water tank for a predetermined time and then pulled up, and then the second recovery step. S3 2 and then pulled up after being immersed in the second recovery water tank for a predetermined time. As a result, the plating bath components adhering to the plating surface of the lead-containing copper-based metal material are sequentially recovered in the first recovery water tank and the second recovery water tank, and the plating surface of the lead-containing copper-based metal material is completely cleaned. It is Next, the lead-containing copper-based metal material is sent to the bright nickel plating step S33, and as shown in FIG. 4 (b), a bright nickel plating is formed on the surface of the super bright nickel plating. Next, the lead-containing copper-based metal material is sent to the recovery step S34 after bright nickel plating, and after being immersed in the third recovery tank for a predetermined time, it is pulled up to clean the surface of the bright nickel plating. Is done. Furthermore, the lead-containing copper-based metal material is sent to the first water washing step S35 and the second water washing step S36 after bright nickel plating, and is sequentially immersed in the sixth and seventh water washing tanks to produce light. The surface of the nickel plating is cleaned and completely cleaned. Next, the lead-containing copper-based metal material is sent to the second active acid treatment step S37, where the surface of the bright nickel plating is subjected to an acid activation treatment with the active acid, and the organic matter adsorbed on the bright nickel plating surface, etc. Is removed. Next, the lead-containing copper-based metal material is dipped in the eighth washing tank in the second washing step S38 after the active acid treatment, and the plating surface (outer surface) and the inner surface (non-sticking element). The ground) is washed.

[Chromic acid activation treatment process to chrome plating process · chromic acid etching treatment process (chromic acid treatment process)]

Next, the lead-containing copper-based metal material is subjected to a chromic acid activation treatment in the chromic acid activation treatment step S39, and the surface of the lead-containing copper-based metal material (the outer plating surface and the inner substrate surface) is treated by nickel plating. The attached oxide film and organic impurities are removed, and the surface (the outer surface and the inner surface) is cleaned. Next, the lead-containing copper-based metal material is subjected to a chrome plating process in a chrome plating process S40, and at the same time, a chromic acid etching process using a chromic acid etching solution (aqueous solution) at a predetermined temperature (for example, room temperature). That is, the chromium plating process S40 includes a chromic acid etching process. At this time, since the chromic acid aqueous solution contained in the chromic acid etching treatment solution is strongly oxidizable, the plating part of the lead-containing copper-based metal material (the plating part on the outer surface) or the base material of the lead-containing copper-based metal material While dissolving the entire surface part (internal substrate surface part), the lead component contained in the plating part and substrate surface part is also dissolved. As a result, the plating part of the lead-containing copper-based metal material and the substrate surface part Or the remainder of the lead component present on the inner surface of the product and the exposed internal metal is eluted and removed in the chromic acid etching solution. At the same time, the lead-containing copper-based metal material is subjected to chromium plating on the surface of the bright nickel plating by the chromium plating process S40.

[0098] [Recovery process]

After the chromic acid activation treatment process S39 and the chrome plating process (chromic acid etching process) S40, the lead-containing copper-based metal material is sent to the first recovery process S41 after the chrome plating, and is sent to the fourth recovery tank for a predetermined time. It is pulled up after being immersed, sent to the next second collection step S42, and after being immersed in a fifth recovery water tank for a predetermined time, it is pulled up. As a result, the chromic acid activation treatment liquid (including chromic acid) or the chromic acid etching treatment liquid force (including chromic acid) adhering to the outer plating surface and the inner substrate surface of the lead-containing copper-based metal material is added to the fourth recovery water tank and the fifth recovery water tank. Sequentially recovered, the outer plating surface and the inner substrate surface of the lead-containing copper-based metal material are completely cleaned. At this time, a gel-like hexavalent chromium film containing hexavalent chromium (Cr ⁶⁺ ) is inevitably formed on the outer plating surface and the inner substrate surface of the lead-containing metal material.

[0099] The changes in the outer plating surface and the inner substrate surface of the lead-containing copper-based metallic material (Cu) due to the reaction at this time are schematically explained. As shown in FIG. 4 (c), the chromic acid activation treatment step S39 From the chrome plating process (chromic acid etching process), a chromium plating (Cr) layer is formed on the outer plating surface of the lead-containing copper-based metal material (Cu) that has undergone S40. In addition, at the time of the recovery steps S41 and S42, the chrome plating (Cr) surface as the outer plating surface of the lead-containing copper-based metallic material (Cu) and the inner substrate surface as the inner surface are subjected to gel-like complex hydration oxidation. Physical coating (XCr O -YCrO

twenty three

• ZH O) film is formed. In particular, pinholes on the inner substrate surface

3 2

For small gaps (micro gaps) or complex gaps (complex gaps) existing between racks or internal parts, etc., a strong gel-like complex hydrated oxide film (XCr O · ΥΟτΟ · Ζ

2 3 3

皮膜 Ο) film is formed and tends to remain. In addition, the outer metal of lead-containing copper-based metal (Cu).

2

The chromic acid etching solution remaining on the surface of the surface and the inner substrate is removed in the recovery tank and released into water in the recovery steps S41 and S42.

[0100] [Reaction formula]

Alternatively, at this time, the hexavalent chromium film is formed by, for example, lead-containing copper-based gold by the following reaction formula: It can also be considered that it is generated on the surface of the metallic material.

(11) CrO + H O H CrO

3 2 2 4

(12) 2H CrO H Cr O + H O

2 4 2 2 7 2

(13) Cr O ² — + 14H + + 3Cu ^ 2Cr ³⁺ + 3Cu ²⁺ + 7H O

2 7 2

(14) Cr ³⁺ + 3H O Cr (OH) + 3H +

twenty three

(15) 2Cr (OH) + CrO ² "+ 2H ⁺ ^ Cr (OH) + Cr (OH) -CrO -HO

3 4 3 4 2

[0101] [Washing process]

After the two recovery steps S41 and S42, the lead-containing copper-based metal material is sent to the water washing step S43, and after being sunk in the ninth water washing tank for a predetermined time, it is pulled up. As a result, the chromic acid etching solution and other deposits remaining on the outer plating surface and the inner substrate surface (internally exposed surface) of the lead-containing copper-based metal material are washed away by the ninth water-washing tank and lead-containing. The surface of the copper-based metal material is more thoroughly cleaned. The water washing step S43 can be omitted if necessary.

[0102] [Hexavalent chromium removal process]

After the washing step S41, S42 in the recovery step S43, the lead-containing copper-based metal material is pulled up in the ninth washing tank power, and in the hexavalent chromium removal step S44, a reducing tank that stores a reducing agent aqueous solution at a predetermined temperature ( Dipped in a reducing bath) for a predetermined time. As the reducing agent for chromic acid in the reduction bath of the hexavalent chromium removal step S44, for example, the same one as in Embodiment 1 can be used, and one or more of them can be dissolved. A sodium sulfite aqueous solution having a concentration can be prepared as a reducing bath. Various conditions such as the concentration of the reducing agent in the reduction bath, the temperature of the reduction bath, and the immersion time can be the same as in the first embodiment.

[0103] When the lead-containing copper-based metal material is immersed in the reducing bath in the hexavalent chromium removal step S44, the lead-containing copper-based metal material is treated in the chromic acid activation treatment step S39 and the chromium plating step (chromic acid etching step) S40. Hexavalent chromium as a film component formed on the outer plating surface and the inner substrate surface (inner exposed surface) is completely removed. Specifically, when a lead-containing copper-based metal material is immersed in a reducing bath, a hexavalent chromium (Cr ⁶⁺ ) film is formed on the outer plating surface and inner substrate surface (inner exposed surface) of the lead-containing copper-based metal material. , Reduced by the reducing agent for chromic acid in the reducing bath to become trivalent chromium (Cr ³⁺ ), and the outer plating surface and inner surface of the lead-containing copper-based metal material Separated from the surface (internally exposed surface) and released into the reduction bath. As a result, a chromium film composed of zero-valent chromium (Cr ^Q ), that is, a chromium plating film of metallic chromium (Cr), is formed on the outer plating surface and inner substrate surface (internally exposed surface) of the lead-containing copper-based metal material. Is formed. Of course, zero-valent chromium (Cr ^Q ) or metallic chromium does not contain hexavalent chromium at all, and the outer plating surface and internal substrate surface (internally exposed surface) of lead-containing copper-based metallic materials are completely hexavalent chromium. It is free. The trivalent chromium (Cr ³⁺ ) released from the outer plating surface and the inner substrate surface (internally exposed surface) of the lead-containing copper-based metal material and released into the reduction bath is finally reduced in the reduction bath. By adjusting the pH of the aqueous solution to a neutral range, it can be recovered by precipitation in the reducing agent aqueous solution in the reducing bath.

[0104] Outer plating surface and inner substrate surface of lead-containing copper-based metallic material (Cu) by reaction at this time

When the change of (externally exposed surface) is schematically explained, as shown in Fig. 4 (d), it was formed on the outer plating surface of lead-containing copper-based metal (Cu) and on the internal substrate surface (internally exposed surface). Gel-like composite hydrated oxide film (XCr O -YCrO · ΖΗ Ο), that is, hexavalent chromium

2 3 3 2

The film is reduced by the reducing agent for chromic acid in the hexavalent chromium removal step S42 to form trivalent chromium (C r O), and the outer plating surface and inner substrate surface of the lead-containing copper-based metal material (Cu).

twenty three

Presumably attached to the (externally exposed surface). That is, at this time, hexavalent chromium does not exist at all on the outer plating surface and internal substrate surface (internally exposed surface) of the lead-containing copper-based metal material (Cu), and the lead-containing copper-based metal material (Cu) It can be said that hexavalent chromium was completely removed from the outer plating surface and the inner substrate surface (inner exposed surface). In particular, at this time, hexavalent chromium that tends to remain in pinholes and cracks existing on the surface of the inner substrate, or small gaps (micro gaps) or complex gaps (complex shape gaps) existing between internal parts. As the coating of the pinhole, crack, smile gap or complex shape gap force is completely removed, hexavalent chromium is used in conjunction with the faucet device made of the lead-containing similar metal material of this embodiment. Can be completely prevented from leaching or leaching.

[0105] [Washing process]

The lead-containing copper-based metal material is reduced in the hexavalent chromium removal step S44, then lifted from the reduction tank, and immediately sent to the water washing step S45 after the hexavalent chromium removal, and then passed to the tenth water washing tank for a predetermined time. Raised after being crushed. As a result, the outside of the lead-containing copper-based metal material Trivalent chromium ( _cr ³⁺ ), for example, acid chromium (Cr 2 O ³ ) adhering to the plating surface and internal exposed surface (substrate surface), is removed by rinsing in the tenth rinsing tank, and lead-containing copper-based metal

twenty three

The outer surface of the material and the exposed internal surface (base surface) are cleaned. The changes in the outer plating surface and internal exposed surface (substrate surface) of the lead-containing copper-based metal material (Cu) due to the reaction at this time can be explained schematically as shown in Fig. 4 (e). All the trivalent chromium (Cr 2 O 3) adhering to the outer surface of the material (Cu) and the exposed internal surface (base surface)

twenty three

Washing process By washing in the washing tank in S45, the lead-containing copper-based metal (Cu) is completely separated from the outer plating surface and the inner exposed surface (substrate surface) and released into water. That is, at this time, not only hexavalent chromium is present on the outer plating surface and the internally exposed surface (base surface) of the lead-containing copper-based metal material (Cu), but all trivalent chromium is also removed and completely present. It will be in a state that does not. In particular, at this time, trivalent chromium that tends to remain in pinholes and cracks existing on the surface of the inner substrate, or small gaps (micro gaps) or complex gaps (complex shape gaps) existing between internal parts, etc. , Powerful pinholes, cracks, smile gaps and complex shape gap forces are completely removed, so trivalent chromium is eluted with the use of the faucet device that is a lead-containing similar metal material of this embodiment. Or the possibility of leaching can be completely prevented.

[0106] [Reaction Formula]

In the hexavalent chromium removal step S44, sodium hyposulfite (Na S O

2 2 5

) Sodium hyposulfite (Na S O)

2 2 5

HSO), for example, according to the following reaction formula:

Three

4 2 4 4 3

Tochidaru.

4CrO ² — + 6NaHSO + 3H SO 2Cr (SO) + 3Na SO + 10H O

4 3 2 4 4 3 2 4 2

[0107] In the hexavalent chromium removing step S43, sodium hyposulfite (Na 2 S 2 O 3) is used as a reducing agent.

When it is put into the aqueous solution in the reduction tank as it is, the hexavalent chromium (4CrO ² or 4H CrO) on the plating surface of the lead-containing copper-based metal material is converted to trivalent chromium (2Cr ( S

4 2 4

o) It can be thought that it will be reduced to).

4 3

4H CrO + 3Na SO + 3H SO 2Cr (SO) + 3Na SO + 7H O [0108] Water treatment process]

In the recovery steps S41 and S42, hexavalent chromium is present in the water in the recovery tank. In the hexavalent chromium removing step S44, trivalent chromium is present in the reducing agent aqueous solution in the reducing tank. Furthermore, in the washing step S45, trivalent chromium is present in the water of the washing tank. Therefore, although not shown, the wastewater treatment process as described in the first embodiment is required for the drainage of the recovery tank, the reduction tank, and the washing tank.

[Surface modification treatment process]

After the water washing step S45, the lead-containing copper-based alloy material is sent to the surface modification treatment step S46, where the outer metal surface and internal exposure of the lead-containing copper-based metal material from which hexavalent chromium has been removed by the phosphoric acid film treatment. The surface (base surface) is modified. Specifically, in the surface modification treatment step S46, the lead-containing copper-based alloy material is immersed in a chemical conversion treatment tank in which a mixed acid aqueous solution having a predetermined temperature is stored for a predetermined time. As the mixed acid aqueous solution in the chemical conversion treatment layer in the surface modification treatment step S46, for example, the same solution as in Embodiment 1 can be used. Various conditions such as the concentration of phosphoric acid and nitric acid in the mixed acid aqueous solution, the bath temperature, and the immersion time can be the same as in the first embodiment.

[0110] By immersing the lead-containing copper-based metal material in the chemical conversion treatment tank storing an aqueous solution of a mixed acid containing phosphoric acid (orthophosphoric acid) and nitric acid at a predetermined concentration, the lead-containing metal material A phosphoric acid film with a predetermined film thickness is formed on the surface of the plating, and exhibits the expected functions such as anti-corrosion function and anti-discoloration function. The changes in the outer plating surface and the internal exposed surface (substrate surface) of the lead-containing copper-based metal material (Cu) due to the reaction at this time can be explained schematically as shown in Fig. 4 (f). On the outer plating surface of the material (Cu) (the outer plating surface where there is no hexavalent chromium and trivalent chromium), the chromium plating reacts with phosphoric acid to form a predetermined phosphoric acid film (H PO). It is guessed. Similarly, lead-containing copper-based metal (Cu)

3 4

As described in Embodiment 1, a predetermined phosphate film (HP) is also applied to the internal exposed surface or substrate surface (internally exposed surface or substrate surface in which hexavalent chromium and trivalent chromium are not present at all).

Three

O) is formed.

Four

[0111] [Reaction formula]

The phosphoric acid film is formed on the surface of the lead-containing copper-based metal material by, for example, the following reaction formula. When it is done, you can ignore it.

(16) 6H PO + 2Cr ^ 2Cr (H PO) + 3H

3 4 2 4 3 2

(17) Cr (H PO) CrPO + 2H PO

2 4 3 4 3 4

[0112] According to the above reaction formulas (16) to (17), the zero-valent chromium film on the outer surface of the lead-containing copper-based metal material reacts with phosphoric acid, and finally the lead-containing copper-based metal material It is thought that a chromium phosphate (CrPO) and orthophosphoric acid (HPO) film is formed on the outer surface of (Cu).

4 3 4

Tochidaru.

[0113] Alternatively, it is considered that the surface modification treatment (i-formation treatment) of the copper or copper alloy in the surface modification treatment step S46 is performed as the following reaction formula as described in the first embodiment. You can also do this. (l) 4Cu + 4HNO → 4Cu ²⁺ + 2H O + 30 + 4NO † →

3 2 2

2Cu 0 + 2H 0 + 20 + 4NO †

2 2 2

(2) 6Cu + 4H PO + 30 → 2Cu (PO) + 6H O →

3 4 2 3 4 2 2

2 (Cu (PO)-6H O)

3 4 2 2

[0114] [Washing process]

The lead-containing copper-based metal material is subjected to a phosphoric acid film treatment in the surface modification treatment step S46, then lifted from the chemical conversion treatment tank, and sent to the first water washing step S47 after the surface modification treatment step S46. After being soaked in the eleventh rinsing tank for a predetermined time and then pulled up, it is further sent to the second rinsing step S48 after the surface modification process S46 and after being soaked in the twelfth rinsing tank for a predetermined time. Be raised. As a result, the mixed acid component force adhering to the plating surface and internally exposed surface (base surface) of the lead-containing copper-based metal material is removed by sequential water-washing in the two water-washing steps S47 and S48, and the lead-containing copper-based metal material The plating surface and internal exposed surface (base surface) are cleaned.

[0115] [Discoloration prevention treatment process]

Next, after these two faucet steps S47, S48, the lead-containing copper-based metal material is sent to the discoloration prevention treatment step S49, where it is stored in a discoloration prevention treatment tank storing a discoloration prevention agent such as an antifungal aqueous solution. After immersing for a predetermined time, the plating surface and the internal exposed surface (base surface) are treated to prevent or discolor. As an antifungal agent or a corrosion / discoloration inhibitor at this time, for example, benzotriazole (CHN) can be used as in the first embodiment. Discoloration prevention treatment Step S49 can be omitted as necessary.

[0116] [Washing process]

The lead-containing copper-based metal material is pulled up from the discoloration prevention treatment tank after the discoloration prevention treatment step S49, sent to the water washing step S50, and after being immersed in the water washing tank for a predetermined time, it is pulled up. As a result, the discoloration inhibitor component adhering to the plating surface and internal exposed surface (base surface) of the lead-containing copper-based metal material is removed by washing in a water washing tank, and the plating surface and internal exposed surface of the lead-containing copper-based metal material are removed. The substrate surface is cleaned. The water washing step S50 can be omitted when necessary, such as when the anti-discoloration treatment step S49 is omitted.

[0117] [Washing and drying process]

The lead-containing copper-based metal material is lifted from the discoloration prevention treatment tank after the water washing step S50 after the discoloration prevention treatment step S49, and sent to the hot water washing step S51 and rinsed with water in the same manner as in the first embodiment. Then, it is sent to the drying step S52 and forcedly dried with hot air or the like. As a result, the discoloration inhibitor component, etc. adhering to the outer skinned surface and the internal exposed surface (base surface) is removed in the hot water bath, and the outer plating surface and the internal exposed surface (base surface) are completely removed. To be cleaned.

[0118] Thus, in the hexavalent chromium-free surface treatment method for lead-containing copper-based metallic materials according to Embodiment 2, hexavalent chromium exists in the form of stable ions, both acidic and alkaline. Focusing on the properties, in the hexavalent chromium removal step S44, the lead-containing copper-based metal material is immersed in the reducing agent aqueous solution in the reduction tank, and the hexavalent chromium on the outer plating surface and the internal exposed surface (base surface) is trivalent chromium. The hexavalent chromium is selectively dissolved and removed from the outer plating surface and the inner exposed surface (substrate surface) of the lead-containing copper-based metal material by reducing it to elution in the reduction tank. Furthermore, in the surface modification treatment step S45, a lead-containing copper-based metal material is immersed in a mixed acid aqueous solution in a chemical conversion treatment tank to form a phosphate film on the outer plating surface and the inner exposed surface (substrate surface). Further improve the corrosion resistance (discoloration resistance) of the outer plating surface and internal exposed surface (base surface) of the lead-containing copper-based metal material after removal.

[0119] [Effect]

The hexavalent chromium-free surface treatment method for lead-containing copper-based metal materials according to Embodiment 2 reliably prevents lead elution after commercialization in metal products made of lead-containing copper-based metal materials. In addition, the elution amount of hexavalent chromium can be reduced to zero, and the corrosion resistance of the outer plating surface and the inner exposed surface (base surface) can be further improved to prevent discoloration and the like. In particular, pinholes and cracks that exist on the surface of internal substrates such as faucet fittings that are lead-containing, similar metal materials, or small gaps (micro gaps) that exist between internal parts, etc. The hexavalent chromium film that tends to remain on the pinholes, cracks, smile gaps and complex shape gap force is completely removed. As a result, it is possible to completely prevent the possibility of elution or leaching of hexavalent chromium. In particular, the embodiment

The hexavalent chromium-free surface treatment method for lead-containing copper-based metallic materials according to No. 2 can completely remove hexavalent chromium, which is an environmentally hazardous substance, and also provides a surface treatment method for environmentally-adapted copper alloys that have excellent corrosion resistance. Can be suitably used. In addition, conventional surface treatment plants for water supplies can be used as they are, and costs do not increase.

Industrial applicability

In addition to materials such as faucet fittings / joints * pipe parts, the present invention can be widely applied to surface treatment applications for materials such as automobile parts-building materials 'home appliances' hardware, and the like.

Claims

The scope of the claims

[1] A chromic acid treatment process in which the surface of a lead-containing metal material is treated with chromic acid, and lead on the surface is eluted and removed.

A hexavalent chromium removing step of completely removing hexavalent chromium as a film component formed on the surface of the lead-containing metal material in the chromic acid treatment step with a reducing agent aqueous solution containing a reducing agent for chromic acid;

And a surface modification treatment step of modifying the surface of the lead-containing metal material from which hexavalent chromium has been removed.

[2] The hexavalent chromium removing step is characterized in that the lead-containing metal material surface is reduced by immersing the lead-containing metal material in an aqueous solution of a reducing agent for chromic acid for a predetermined time. The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 1.

[3] The hexavalent chromium removing step reduces the hexavalent chromium on the surface of the lead-containing metal material to trivalent chromium by immersing the lead-containing metal material in an aqueous solution of a chromic acid reducing agent for a predetermined time. Is what

Furthermore, a water washing step for completely separating and removing trivalent chromium remaining on the surface of the lead-containing metal material by water washing is provided between the hexavalent chromium removing step and the surface modification treatment step. 3. A hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 1 or 2.

[4] The reducing agent for chromic acid according to any one of claims 1 to 3, wherein the reducing agent comprises one or a mixture of sodium hyposulfite, sodium thionite, sodium thiosulfate, and sodium sulfite. Any method of hexavalent chromium-free treatment of lead-containing metal materials as described in item 1.

[5] In the surface modification treatment step, the lead-containing metal material is immersed in a chemical conversion treatment tank storing a mixed acid aqueous solution containing phosphoric acid and nitric acid as main materials for a predetermined time. The hexavalent chromium-free surface treatment method for a lead-containing metal material according to any one of claims 1 to 4, wherein a phosphoric acid film is formed on the surface of the material.

[6] A chromic acid etching process in which the base surface of the lead-containing copper-based metal material is etched with chromic acid, and lead is eluted and removed from the base surface portion of the lead-containing copper-based metal material; A hexavalent chromium removing step of completely removing hexavalent chromium as a film component formed on the substrate surface of the lead-containing copper-based metal material in the chromic acid etching step with an aqueous solution of a reducing agent for chromic acid;

A surface modification treatment process for modifying the base surface of the lead-containing copper-based metal material from which hexavalent chromium has been removed;

A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material.

[7] The hexavalent chromium removing step reduces the base surface of the lead-containing copper-based metal material by immersing the lead-containing copper-based metal material in an aqueous solution of a reducing agent for chromic acid for a predetermined time. The method for treating a hexavalent chromium-free surface of a lead-containing metal material according to claim 6, wherein:

[8] The hexavalent chromium removing step includes immersing the lead-containing copper-based metal material in an aqueous solution of a reducing agent for chromic acid for a predetermined time, whereby the hexavalent chromium on the base surface of the lead-containing copper-based metal material is obtained. Is reduced to trivalent chromium,

Furthermore, a water washing step is provided between the hexavalent chromium removal step and the surface modification treatment step, in which the trivalent chromium remaining on the surface of the lead-containing metal material is completely separated and removed by washing. The method for treating a hexavalent chromium-free surface of a lead-containing metal material according to claim 6 or 7.

[9] A chromium plating process for forming a chromium plating layer on a lead-containing copper-based metal material,

A chromic acid etching step for eluting and removing lead in the product of the lead-containing copper-based metal material or the exposed portion of the internal metal;

A hexavalent chromium removing step of completely removing hexavalent chromium as a film component formed on the surface of the lead-containing copper-based metal material in the chromic acid etching step or the chromium plating step with an aqueous solution of a reducing agent for chromic acid;

A surface modification process for modifying the surface of the lead-containing copper-based metal material from which hexavalent chromium has been removed;

[10] The hexavalent chromium removing step reduces the surface of the lead-containing copper-based metal material by immersing the lead-containing copper-based metal material in an aqueous solution of a reducing agent for chromic acid for a predetermined time. 10. The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 9, wherein:

[11] The hexavalent chromium removing step includes immersing the lead-containing copper-based metal material in an aqueous solution of a reducing agent for chromic acid for a predetermined time, thereby removing hexavalent chromium on the surface of the lead-containing copper-based metal material. Which is reduced to trivalent chromium,

Furthermore, a water washing step for completely separating and removing trivalent chromium remaining on the surface of the lead-containing metal material by water washing is provided between the hexavalent chromium removing step and the surface modification treatment step. 11. The hexavalent chromium-free surface treatment method for a lead-containing metal material according to claim 9 or 10, wherein the surface of the lead-containing copper-based metal material is a zero-valent chromium surface made of chromium plating of the chromium plating layer.

[12] The hexavalent chromium removing step includes immersing the lead-containing copper-based metal material for a predetermined time in an aqueous solution of a reducing agent for chromic acid maintained at a predetermined temperature and a predetermined concentration. 12. The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 11, wherein the hexavalent chromium on the surface of the metal is completely removed to obtain a zero-valent chromium surface.

[13] In the hexavalent chromium removing step, the hexavalent chromium on the surface of the lead-containing copper-based metal material is trivalent by immersing the lead-containing copper-based metal material in an aqueous solution of a reducing agent for chromic acid for a predetermined time. While reduced to chromium and separated from the lead-containing copper-based metal material surface, it is released or released into the aqueous solution,

A water washing step is provided between the hexavalent chromium removal step and the surface modification treatment step to completely separate and remove trivalent chromium remaining on the surface of the lead-containing copper-based metal material by water washing. 10. A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 6 or 9.

[14] The reducing agent for chromic acid according to any one of claims 6 to 13, wherein the reducing agent comprises one or a mixture of sodium hyposulfite, sodium thionite, sodium thiosulfate, and sodium sulfite. The hexavalent chromium free treatment method for a lead-containing copper-based metal material according to any one of the above.

[15] The surface modification treatment step includes immersing the lead-containing copper-based metal material for a predetermined time in a chemical conversion treatment tank storing a mixed acid aqueous solution containing phosphoric acid and nitric acid as main materials. The hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to any one of claims 6 to 14, wherein a phosphoric acid film is formed on the surface of the copper-based metal material.

[16] The surface modification treatment step is a mixed acid containing phosphoric acid and nitric acid as main materials so that phosphoric acid has a concentration of about 2 to 5% and nitric acid has a concentration of about 0.5 to 2%. 15. The phosphate film is formed on the surface of the lead-containing copper-based metal by immersing the lead-containing copper-based metal material in an aqueous solution for a predetermined time. 2. A hexavalent chromium-free surface treatment method for a lead-containing copper-based metal material according to claim 1.

[17] A hexavalent chromium-free lead-containing copper-based metal material that is used without plating, wherein the lead on the surface of the lead-containing copper-based metal material is eluted and removed by chromic acid etching treatment, and the chromium The hexavalent chromium formed on the base surface of the lead-containing copper-based metal material by acid etching treatment is completely removed by reduction treatment with a reducing agent aqueous solution for chromic acid, and then the base surface of the lead-containing copper-based metal material A hexavalent chromium-free lead-containing copper-based metal material characterized by forming a phosphate film on the surface.

[18] A hexavalent chromium-free lead-containing copper-based metal material that is used with a coating,

The inner surface exposed part of lead-containing copper-based metal material or lead in the product is eluted and removed by chromic acid etching treatment, and the lead-containing copper-based metal material formed on the plating surface of the lead-containing copper-based metal material by the chromic acid etching treatment. Hexavalent chromium-free, characterized by forming a phosphate film on the plating surface of the lead-containing copper-based metal material after completely removing chromium by reduction treatment with a reducing agent aqueous solution for chromic acid Lead-containing copper-based metal material.

[19] A hexavalent chromium-free surface treatment method for a base material on which a hexavalent chromium film is formed by surface treatment using chromium,

A hexavalent chromium-free surface treatment characterized by completely removing the hexavalent chromium film on the surface of the base material on which the hexavalent chromium film is formed by a reducing agent aqueous solution containing a reducing agent for chromic acid. Method.

[20] Hexavalent coating of a base material on which a hexavalent chromium film is formed by surface treatment using chromium Rom-free surface treatment method,

A hexavalent chromium film removing step for completely removing the hexavalent chromium film on the surface of the base material on which the hexavalent chromium film is formed by a reducing agent aqueous solution containing a reducing agent for chromic acid; And a surface modification treatment step of modifying the surface of the base material from which the iron has been removed.