CN1473209A - Method for removing lead from plated cylindrical article made of lead-containing copper alloy and metal fitting for hydrant, and method for preventing leaching of lead from article made of lead-contai - Google Patents
Method for removing lead from plated cylindrical article made of lead-containing copper alloy and metal fitting for hydrant, and method for preventing leaching of lead from article made of lead-contai Download PDFInfo
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- CN1473209A CN1473209A CNA018183026A CN01818302A CN1473209A CN 1473209 A CN1473209 A CN 1473209A CN A018183026 A CNA018183026 A CN A018183026A CN 01818302 A CN01818302 A CN 01818302A CN 1473209 A CN1473209 A CN 1473209A
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
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Abstract
A method for removing lead from a plated article made of a lead-containing copper alloy, which includes a pre-treatment step (S1) of subjecting a work piece (50a) being made of a lead-containing copper alloy and having a cylindrical part (10) to a pre-treatment, a plating step (S2) of plating a nickel-chromium layer (20) on the exterior surface of the work piece (50a) after the pre-treatment step (S1), and a lead-removing step (S3) of removing lead from the interior surface of the cylindrical part (10) after the plating step (S2). The method can be employed for producing at a low cost a plated article made of a lead-containing copper alloy which exhibits a reduced amount of lead dissolving out from the interior surface of its cylindrical part into water and also has excellent appearance.
Description
Technical Field
The first invention relates to a lead removing method for a lead-containing copper alloy plated article having a cylindrical portion and a water valve metal member. The second invention relates to a method for preventing lead leaching of a lead-containing copper alloy product and a water valve metal member. The method for preventing lead leaching of a lead-containing copper alloy article according to the second invention is suitably used for a method for manufacturing a metal fitting for a water valve.
Background
For example, for plumbing fixtures such as water valve fittings and water pipes, copper alloys such as bronze and brass are generally used from the viewpoint of corrosion resistance, and for water valve fittings having particularly complicated shapes, lead-containing copper alloys are generally used from the viewpoint of machinability. A lead-containing copper alloy constituting a fitting is subjected to a process such as casting, and then cut into a fitting having a cylindrical portion through which water passes. Then, on the workpiece, mainly for decorative consideration, a nickel-chromium coating is formed by adopting an electroplating nickel-chromium method to manufacture the water valve metal piece.
A general nickel-chromium plating method includes steps S1 of pretreating the workpiece and S2 of plating a nickel-chromium plating layer on the outer peripheral surface of the workpiece after the pretreatment step S1, as shown in fig. 13.
More specifically, the pretreatment step S1 includes a degreasing step S11 of immersing the workpiece in an alkaline solution to degrease the entire surface of the workpiece. The alkali solution used here is usually an aqueous alkaline solution prepared by dissolving sodium hydroxide or the like in water. And soaking the workpiece in the alkali liquor to degrease according to the pH value of the alkali liquor. In addition, lead can also be removed by corrosion by adjusting the pH of the alkali liquor. In the pretreatment step S1, in addition to the degreasing step S11, the following steps are performed: a cathode electrolysis step S12 of further degreasing the entire surface of the workpiece in an alkaline solution with the workpiece as a cathode, an acid activation step S13 of washing the workpiece with an acid solution to activate the entire surface of the workpiece, and a water washing step provided between these steps.
The plating step S2 also includes the following steps: a nickel plating step S21 of applying a nickel plating layer to the outer peripheral surface of the workpiece after the pretreatment step S1 using a nickel plating electrolyte, a chromium plating step S22 of applying a nickel-chromium layer to the outer peripheral surface of the workpiece after the nickel plating step S21 using a chromium plating electrolyte, and a water washing step provided between these steps.
In this way, the water valve metal fitting obtained as a plated product can be used with water in the cylindrical portion.
Summary of the invention { 1 st invention }
However, in recent years, people are increasingly afraid of damage to human health caused by lead contained in water, and therefore, there is a demand for further reduction in the amount of lead leached into water from the inner wall of the cylindrical portion of an electrolytic plating product such as a plumbing fixture. Therefore, in the above-described conventional general method for plating nickel chromium, lead removal should be easily performed by immersing the workpiece in an alkaline solution having a high pH in the degreasing step S11 and removing lead from the entire surface of the workpiece by etching before the plating step S2, but unevenness is easily generated on the entire surface of the workpiece. Therefore, even if the plating layer is applied to the outer peripheral surface of the workpiece in the subsequent plating step S2, the outer periphery of the plated product is likely to have irregularities, and the surface properties of the outer peripheral surface of the plated product are likely to be deteriorated. Therefore, the aesthetic effect of the plated article is lost.
If the thickness of the plating layer on the outer peripheral surface of the workpiece is increased to maintain the aesthetic appearance of the plated product, the manufacturing cost is inevitably increased.
This disadvantage is caused in the case of a workpiece using a lead-containing copper alloy, and a plated product having a cylindrical water-carrying portion is produced. The problem is even greater particularly when the electroplated article is a water valve metal part of complex shape.
The invention of claim 1 is made in view of the above-mentioned conventional practical problems, and it is an object of the invention to provide a lead removing method which can reduce the amount of lead dissolved into water from the inner wall of the cylindrical portion, can provide an excellent appearance, and can produce a plated product at a low cost.
The invention of claim 1 is also directed to provide a water valve metal fitting which can reduce the amount of lead leaching into water, has an excellent aesthetic effect, and can be manufactured at low cost.
The method for removing lead from a plated product of a lead-containing copper alloy with a cylindrical portion according to claim 1 is characterized in that: a lead removing step of removing lead from the inner peripheral surface of a lead-containing copper alloy workpiece having a water-passing cylindrical portion is performed on the workpiece obtained after a plating step of plating the outer peripheral surface of the workpiece.
The lead removing method of claim 1 is a method for removing lead after the plating step, and therefore, the plating layer on the outer peripheral surface of the workpiece is protected, and lead is removed only from the inner surface of the workpiece having no plating layer without removing lead. Therefore, the outer peripheral surface of the workpiece is not uneven, the plating layer is not damaged, and the outer peripheral surface of the plated product has excellent surface properties. Therefore, the electroplated product is beautiful and beautiful.
In addition, in the lead removing method according to claim 1, since it is not necessary to apply a thicker plating layer on the outer peripheral surface of the workpiece in order to maintain the appearance of the plated product, the manufacturing cost can be reduced.
In the lead removing method according to the invention 1, if a workpiece of the water valve metal member is used, the water valve metal member according to the invention 1 as a plated product can be obtained. The water valve metal piece is characterized by comprising the following parts: a base portion made of a lead-containing copper alloy having a cylindrical portion; a lead-containing layer formed integrally with the base portion on the outer peripheral surface of the cylindrical portion and having a lead concentration substantially equal to that of the base portion; a plating layer formed on the outer peripheral surface of the lead-containing layer; a low lead-containing layer having a lower lead concentration than the base portion is formed integrally with the base portion on the inner peripheral surface of the cylindrical portion.
In the water valve metal fitting according to claim 1, since the lead concentration in the lead-containing layer is low on the inner peripheral surface of the cylindrical portion, lead is less likely to leach into water even when water passes through the inner peripheral surface. Therefore, when people drink the water supplied by the water valve metal piece, the doubtful influence on the human health can be eliminated. In addition, when the water is discharged to rivers and sewers, the influence on the environment can be reduced.
In the fitting of claim 1, since the outer peripheral surface of the cylindrical portion has the lead-containing layer having a lead concentration substantially equal to that of the base portion, and the plating layer is formed on the outer peripheral surface of the lead-containing layer, the lead-containing layer does not have irregularities, and the fitting is beautiful in appearance.
In addition, the water valve metal fitting of claim 1 can be manufactured at low cost because the thickness of the plating layer does not need to be increased.
In the lead removing method according to claim 1, it is preferable to provide an inerting step of inerting the cylindrical portion after the lead removing step. In this way, the inner peripheral surface is rendered inert by the inerting step, and the amount of lead leached from the low lead-containing layer can be further reduced.
In the lead removing method according to claim 1, the lead removing step may be performed by immersing the workpiece in an etching solution capable of etching lead from the inner peripheral surface of the cylindrical portion. Since this corrosive liquid can chemically react with lead on the inner peripheral surface, lead is leached and removed.
Acid or alkali solutions can be used as the etching solution. However, copper reacts with acid, and lead is an amphoteric metal, which reacts with both acid and alkali, so that it is preferable to use an alkaline solution as the etching solution, and it is particularly preferable to use an active alkaline solution. The active alkali solution is an alkali solution with a pH value within a range of 12-14. The alkaline solution with the pH value within the range is easy to react with the lead on the inner peripheral surface, so that the lead can be easily dissolved and removed. The active alkali liquor is mainly aqueous solution of sodium carbonate, sodium hydroxide, sodium phosphate, sodium orthosilicate, sodium tripolyphosphate, sodium orthosilicate, potassium hydroxide and the like.
The etching solution preferably contains a surfactant. If the etching liquid contains a surfactant, the surface tension of the etching liquid can be reduced, and therefore, the permeability and wettability of the etching liquid to the inner peripheral surface of the cylindrical portion can be improved. Therefore, a chemical reaction between lead contained in the inner peripheral surface and the corrosive liquid is likely to occur.
As the surfactant, anionic surfactants such as sodium higher fatty acid, sulfated oils, sodium higher alcohol sulfate, sodium alkyl benzene sulfate, sodium higher alkyl ether sulfate, α -sodium olefin sulfate and the like can be used, and as the nonionic surfactant, alkyl polyoxyethylene ethers such as alkyl polyoxyethylene ethers, alkyl phenyl polyoxyethylene ethers, fatty acid ethylene oxide adducts, polypropylene glycol ethylene oxide adducts and the like can be used.
The etching solution preferably further contains a chelating agent. Since the chelating agent chemically reacts with lead to form a water-soluble complex, lead contained in the inner peripheral surface of the cylindrical portion can be easily removed.
As the chelating agent, there can be used, for example, ethylenediamine, thiourea, tartaric acid, rochelle salt (potassium sodium tartrate tetrahydrate), EDTA, triethanolamine and the like.
The etching solution preferably further contains an oxidizing agent. That is, if it is desired to remove lead contained in the inner peripheral surface of the cylindrical portion only by using an etching liquid such as an active alkali solution, lead is dissolved by the following chemical reaction.
On the contrary, if the active alkaline etching solution contains an oxidizing agent, the oxidizing agent and lead undergo a chemical reaction as shown in the following reaction formula (2) to form lead oxide.
Then, the lead oxide is leached out in the alkaline solution corrosive liquid, and a chemical reaction shown in the following reaction formula (3) occurs to form plumbate.
In the method of the two reactions of the above reaction formula (1) and reaction formula (2), the reaction proceeds more rapidly than in the reaction of the above single reaction formula (1), and therefore, the lead contained in the inner peripheral surface of the cylindrical portion can be removed more easily by the oxidizing agent contained in the active alkali corrosive liquid.
As the oxidizing agent, there can be used, for example, sodium m-nitrobenzenesulfonate, sodium p-nitrobenzoate, hypochlorite, bleaching powder, hydrogen peroxide, potassium permanganate, persulfate, perchlorate, etc.
In the lead removing method of claim 1, the plating step preferably further includes a chromium plating step using a chromium plating solution containing chromic acid, and the inerting step preferably further includes a chromate treatment step of immersing the workpiece in a chromate solution containing chromic acid.
First, in the chromium plating step, chromic acid and lead are chemically reacted as shown in the reaction formula (4) by the action of chromic acid in the chromium plating solution to form lead chromate, which is insoluble and therefore inert. Therefore, lead does not leach out from the outer peripheral surface of the workpiece.
Thereafter, in the chromate treatment step performed in the lead removal step, a chemical reaction as shown in the above reaction formula (4) occurs between chromic acid and lead due to the action of chromic acid in the chromate solution, and lead chromate is formed. Thus, even if a trace amount of lead is contained in the inner peripheral surface of the workpiece cylindrical portion, the lead does not leach out. In addition, in both of these chromium plating step and chromate treatment step, the use of chromic acid provides operational advantages.
In the chromate treatment step, a chromate protective film (xCr) is formed on the inner peripheral surface of the cylindrical portion by chemical reaction of the reaction formulae (5) to (7)2O3·y CrO3·zH2O)。
In the water valve metal fitting obtained in this way, since the chromate protective film is formed on the inner peripheral surface of the low-lead layer, the lead remaining on the inner peripheral surface of the cylindrical portion is rendered inert by the chromate protective film and is thus less likely to leach out.
As the chromate solution, for example, a solution containing sulfuric acid or the like may be used in addition to chromic acid, and a solution in which chromate, oxalic acid, acetic acid, hydrofluoric acid, nitric acid or the like is added may be used, and a chromate agent used for zinc plating or the like may be used as the chromate solution.
The chromium plating solution used in the invention 1 preferably contains a fluoride, because it is considered that lead chromate formed in the chromium plating solution can be dissolved by the fluoride. As the fluoride, zinc fluoride, aluminum fluoride, antimony fluoride, ammonium fluoride, sulfur fluoride, uranium fluoride, chlorine fluoride, osmium fluoride, cadmium fluoride, potassium fluoride, calcium fluoride, xenon fluoride, silver fluoride, chromium fluoride, silicon fluoride, germanium fluoride, cobalt fluoride, oxygen fluoride, cyanogen fluoride, bromine fluoride, fluorozirconate, stannate fluoride, strontium fluoride, thallium fluoride, tantalate fluoride, nitrogen fluoride, iron fluoride, copper fluoride, sodium fluoride, fluoroniobate, nickel fluoride, barium fluoride, arsenic fluoride, boron fluoride, boric fluoride, magnesium fluoride, manganese fluoride, methyl fluoride, iodine fluoride, iodate fluoride, lithium fluoride, phosphorus fluoride, rhenium fluoride, or the like can be used. It is believed that a fluoride such as silicon fluoride can chemically react with lead as shown in the following reaction formula (8) to form lead fluoride. Therefore, lead contained in the inner peripheral surface of the cylindrical portion can be removed.
The chromate solution used in the invention 1 preferably contains phosphoric acid. Since both chromic acid and phosphoric acid are believed to be effective in promoting the chemical reaction that dissolves lead and the chemical reaction that forms the chromate protective film. Therefore, lead contained in the inner peripheral surface of the cylindrical portion can be effectively dissolved, and the chromate protective film can be effectively formed on the inner peripheral surface. In addition, instead of phosphoric acid, the following compounds may also be used, such as: ammonium phosphate, phosphate esters, potassium phosphate, calcium phosphate, iron phosphate, tri-n-butyl phosphate, tricresyl phosphate, triphenyl phosphate, sodium phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, magnesium phosphate, ammonium magnesium phosphate, lithium phosphate, phospholipids, phosphor bronze, phosphotungstic acid, phosphotungstate, phosphomolybdic acid, phosphomolybdate, and the like.
In the water valve metal member thus obtained, it is preferable that the low lead-containing layer contains no lead. If lead is not contained in the low lead-containing layer, lead does not leach into water passing through the inner peripheral surface, and lead on the inner side surface rarely leaches through the low lead-containing layer. { invention 2 }
In recent years, there has been a growing fear of the harm to human health caused by lead contained in water, and there has been a demand for further reduction of the amount of lead leaching from lead-containing copper alloy products such as water valve metal parts into water. In particular, in the water valve metal fitting with the cylindrical portion, it is required to reduce the amount of lead leaching into the water from the inner peripheral surface of the cylindrical portion.
The invention of claim 2 has been made in view of the above conventional circumstances, and an object thereof is to provide a method for preventing lead leaching of a lead-containing copper alloy product, which can easily reduce the amount of lead leached into water in the lead-containing copper alloy product. The invention of claim 2 is intended to provide a water valve metal fitting which can reduce the amount of lead leached out from water and can be easily manufactured.
The present inventors have conducted diligent studies to solve the above problems and have found that a phosphorus-containing protective film can be formed on the surface of a workpiece made of a lead-containing copper alloy product by immersing the workpiece in a treatment liquid such as an aqueous phosphoric acid solution, and have completed the present invention.
That is, the method for preventing lead leaching of a lead-containing copper alloy product according to claim 2 is characterized by comprising a protective film forming step of preparing a workpiece of the lead-containing copper alloy product and a treatment liquid mainly containing phosphoric acid or a phosphate in water, and bringing the treatment liquid into contact with the workpiece to form a protective film containing phosphorus on the surface of the workpiece.
The method for preventing lead leaching of a lead-containing copper alloy product according to claim 2, wherein the protective film formed in the protective film forming step prevents leaching of lead. The protective film is mainly composed of zinc dihydrogen phosphate (Zn (H)2PO4)2) And (H)3PO4) In the case of a treatment liquid containing a main component, it is considered that the treatment liquid is produced as follows.
First, when such a treatment liquid comes into contact with a lead-containing copper alloy workpiece, copper is dissolved in the treatment liquid by the action of phosphoric acid to generate copper ions as shown in reaction formula (9).
Further, if lead is present on the surface of the work, lead is dissolved in the treatment solution by the action of phosphoric acid to generate lead ions as shown in the reaction formula (10).
Here, as shown in reaction scheme (11), zinc dihydrogen phosphate is partially dissociated in the treatment solution.
Therefore, it is considered that the copper ions and/or the lead ions in the treatment liquid undergo chemical reactions represented by the following reaction formulae (12) and (13), and a phosphorus-containing protective film is formed on the surface of the workpiece.
In addition, it is considered that Zn is excluded2Cu(PO4)2、Zn2Pb(PO4)2In addition, Zn is also formed3(PO4)2·4H2O and/or Zn (H)2PO4)2And a protective film made of inactive crystals. According to the results of experiments by the inventors, the protective film thus formed can prevent the leaching of lead.
In addition, in this lead leaching prevention method, a solution in which phosphoric acid or a phosphate is mainly added to water is used as the treatment liquid. Phosphoric acid or phosphate is less toxic than chromium plating solutions containing chromic acid consisting of hexavalent chromium and chromate-containing liquid phases containing chromic acid for inerting, which are used for forming chromium plating. Therefore, the washing liquid and the waste liquid which have been contacted with the treatment liquid and washed the workpiece can be treated by neutralizing and diluting the washing liquid and the waste liquid. Therefore, the treatment with a washing solution or the like is relatively simple as compared with the treatment methods of the chromate solution containing chromic acid disclosed in Japanese patent laid-open Nos. 2000-96269 and 2000-96270.
The phosphoric acid used in the invention 2 is phosphorus pentoxide (P)2O5) A series of acids (P) formed by hydration to different degrees2O5·nH2O). For example, orthophosphoric acid (H)3PO4(0.5P2O5·1.5H2O)), metaphosphoric acid (HPO)3(0.5P2O5·0.5H2O), and the like.
The phosphate used in the invention 2 may be zinc phosphate, manganese phosphate, iron phosphate, calcium zincphosphate, or the like. Examples of the zinc phosphate-based phosphate include zinc dihydrogen phosphate (Zn (H)2PO4)2) Phosphates as the main component, and the like. Other sodium phosphates (Na (H)2PO4)2、Na2HPO4Etc.), aluminum phosphate (Al (H)2PO4)3Etc.), ammonium phosphate (NH)4H2PO4Etc.) and the like.
The concentration of phosphoric acid or phosphate in the treatment solution of the invention 2 is preferably in the range of 0.01 to 10.0% by mass. According to the results of experiments by the present inventors, it has been found that when the concentration of phosphoric acid or phosphate is in the range of 0.01 to 10.0 mass%, a phosphorus-containing protective film is easily formed on the surface of a workpiece.
In the method for preventing lead leaching according to claim 2, it is preferable that a lead removing step of removing lead from the surface of the work is performed before the protective film forming step. This makes it possible to form a low lead-containing layer having a low lead concentration on the surface of the workpiece before the protective film forming step, and therefore, it is possible to further prevent lead from leaching from the workpiece.
The lead removing step may be performed by immersing the substrate in an etchant which may corrode lead. Because the corrosive liquid can promote chemical reaction with the lead on the surface of the workpiece, the lead is dissolved and removed.
Acid solutions and alkaline solutions can be used as the etching solution. However, since copper reacts with acid and lead, which is an amphoteric metal, reacts with both acid and alkali, it is preferable to use alkali solution as the etching solution. It is particularly desirable to use an active lye. The active alkali solution is an alkali solution with the pH value within the range of 12-14. If a pH in this range is used, the chemical reaction of the active lye with the surface lead occurs more readily and is therefore more readily soluble in removing lead. The active alkali solution mainly comprises sodium carbonate, sodium hydroxide, sodium phosphate, sodium silicate, sodium tripolyphosphate, sodium orthosilicate, potassium hydroxide and other aqueous solutions.
The etching solution preferably contains a surfactant. If the etching solution contains a surfactant, the surface tension of the etching solution can be reduced, and the surface permeability and wettability of the etching solution can be improved. Therefore, the lead contained in the surface of the workpiece and the corrosive liquid are easy to react chemically.
As the surfactant, anionic surfactants such as sodium higher fatty acid, sulfated oils, sodium higher alcohol sulfates, sodium alkyl benzene sulfates, sodium higher alkyl ether sulfates, α -sodium olefin sulfates and the like can be used, and nonionic surfactants such as alkyl polyoxyethylene ethers, alkyl phenyl polyoxyethylene ethers, fatty acid ethylene oxide adducts and the like can be used.
The etching solution preferably further contains a chelating agent. Since the chelating agent can chemically react with lead to form a water-soluble complex, lead contained in the surface can be easily removed.
As the chelating agent, there can be used, for example, ethylenediamine, thiourea, tartaric acid, rochelle salt (potassium sodium tartrate tetrahydrate), EDTA, triethanolamine and the like.
Further, the etching solution preferably further contains an oxidizing agent. That is, if only the active alkaline etching solution is used to remove lead contained on the surface, for example, in the case of using sodium hydroxide as the etching solution, lead is dissolved by the following chemical reaction.
On the contrary, if the active alkaline etching solution contains an oxidizing agent, the oxidizing agent and lead first undergo a chemical reaction as shown in the following reaction formula (15) to form lead oxide.
Then, the lead oxide is dissolved in the alkaline corrosion solution, and a chemical reaction shown in the following reaction formula (16) occurs to form a plumbate.
Since one of the reactions of the reaction formula (15) and the reaction formula (16) proceeds more rapidly than the reaction of the single reaction formula (14), the lead contained in the surface is more easily removed by the oxidizing agent contained in the active alkaline etching solution.
As the oxidizing agent, there can be used, for example, sodium m-nitrobenzenesulfonate, sodium p-nitrobenzoate, hypochlorite, bleaching powder, hydrogen peroxide, potassium permanganate, persulfate, perchlorate, etc.
The method for preventing lead leaching according to claim 2 is particularly advantageous when the lead removal step is performed on a plated product having a nickel-chromium layer plated on the outer peripheral surface of a workpiece. That is, the outer peripheral surface of the plated workpiece is subjected to a lead removing step in a state of being protected by the nickel-chromium plating layer. Therefore, the outer peripheral surface of the workpiece is not affected at all, and lead is removed only fromthe inner surface without the nickel-chromium plating. Therefore, the outer peripheral surface of the workpiece is not uneven, the nickel-chromium plating layer is not damaged, and the outer peripheral surface of the plated product has good properties. Therefore, the plated article has a beautiful appearance.
In addition, in this method for preventing lead leaching, since the lead removal step is not performed on the workpiece before plating, the surface properties of the workpiece before plating are not deteriorated. Therefore, the method for preventing lead leaching does not need to conceal deteriorated surface properties caused by the lead removal process performed on the workpiece before plating, and does not need to thicken the plating layer on the outer peripheral surface of the workpiece, so that the manufacturing cost can be further reduced.
On the other hand, the fitting according to the second aspect of the present invention is characterized by comprising a base body made of a copper alloy having a cylindrical part through which water passes, and a phosphorus-containing protective film integrally formed with the base body at least on the inner peripheral surface of the cylindrical part.
In this faucet fitting, since the phosphorus-containing protective film is formed at least on the inner peripheral surface of the cylindrical portion, lead contained in the base portion does not leach out even if water is passed through the cylindrical portion, and therefore, when water is supplied from the faucet fitting to a person drinking the faucet fitting, the concern of harmful effects on human health can be eliminated. In addition, the influence on the environment can be reduced when such water is discharged to rivers and sewers.
The water valve metal member uses a solution mainly containing phosphoric acid or phosphate as a treatment solution, and the cleaning solution is easyto manage, so that the manufacturing cost can be further reduced.
The fitting of claim 2 further comprising a lead-containing layer formed integrally with the base portion on the outer peripheral surface of the cylindrical portion, the lead concentration of the lead-containing layer being substantially equal to that of the base portion; a nickel-chromium plating layer formed on the outer peripheral surface of the lead-containing layer; a low lead-containing layer formed integrally with the base portion on the inner peripheral surface of the cylindrical portion, the low lead-containing layer having a lower lead concentration than the base portion; a protective film may be formed on the surface of the low lead-containing layer. This makes it possible to form a low lead-containing layer having a low lead concentration on the inner peripheral surface of the cylindrical portion, and therefore, lead leaching from the workpiece can be further prevented.
Brief description of the drawings
FIG. 1 is a process diagram of a plating method according to embodiment 1 of the present invention.
Fig. 2 is a cross-sectional view of a metal fitting for a water valve obtained by the plating method according to embodiment 1 of the present invention.
FIG. 3 is a process diagram of the electroplating method according to embodiment 2 of the present invention 1.
FIG. 4 is a process diagram of the electroplating method according to embodiment 3 of the present invention 1.
FIG. 5 is a process diagram of the electroplating method according to embodiment 4 of the present invention 1.
Fig. 6 is a cross-sectional view of a water valve metal member obtained by the plating method according to embodiment 4 of the present invention 1.
Fig. 7 is a perspective view of the water valve metal member of the invention 1.
Fig. 8 is a process diagram of the lead leaching prevention method of example 1 of the 2 nd invention.
Fig. 9 is a sectional view of a water valve metal member obtained by the method for preventing lead leaching of example 1 of the present invention 2.
Fig. 10 is a process diagram of the lead leaching prevention method of example 2 of the invention.
Fig. 11 is a sectional view of a fitting metal member for a water valve obtained by the method for preventing lead leaching according to example 2 of the present invention.
Figure 12 is a perspective view of the water valve metal member.
Fig. 13 is a process diagram of a prior art nickel-chromium plating process.
Best mode for carrying out the invention [ invention 1]
Examples 1 to 4 embodying the invention of claim 1 will be described below together with comparative examples 1 and 2 with reference to the drawings.
Example 1
In example 1, the lead removal method was embodied as part of the nickel-chromium plating method. As shown in fig. 7, first, a workpiece 50a for a water valve metal fitting made of a lead-containing copper alloy such as jisac 406 (bronze 6 series) produced by a method such as casting for cutting is prepared. The workpiece 50a has a cylindrical portion 10 (see fig. 2) through which water flows. Then, as shown in fig. 1, the following steps are sequentially performed: a pretreatment step S1 of pretreating the workpiece 50 a; a plating step S2 of applying a nickel-chromium plating layer to the outer peripheral surface of the workpiece 50a after the pretreatment step S1; after the plating step S2, a lead removing step S3 is performed to remove lead from the work 50 a.
The pretreatment step S1 includes a degreasing step S11, a cathode electrolysis step S12, an acid activation step S13, and a water washing step (not shown) provided between these steps, as in the case of the general plating method shown in fig. 13. In the degreasing step S11, the workpiece 50a is immersed in an alkaline solution having a pH of 11 for 5 minutes to degrease the entire surface of the workpiece 50 a. The alkali liquor is an aqueous solution containing sodium hydroxide in g/l, surfactant, chelating agent and oxidant at 40 deg.C. In the cathodic electrolysis step S12, the workpiece 50a is further degreased over its entire surface in the same alkaline solution with the workpiece 50a as a cathode. In the acid activation step S13, the entire surface of the workpiece 50a is activated by washing the workpiece a with an aqueous sulfuric acid solution having a pH of 2 at room temperature. A water washing step (not shown) is provided between the steps S11 to S13 to wash the workpiece 50a with water.
As shown in fig. 1, the plating step S2 also includes a nickel plating step S21 and a chromium plating step S22, as in the general plating method shown in fig. 13. In the nickel plating step S21, a nickel plating solution is used to apply a nickel plating layer to the outer peripheral surface of the workpiece 50 a. In the chromium plating step S22, a chromium plating solution is used to apply a chromium plating layer to the outer peripheral surface of the workpiece 50a treated in the nickel plating step S21. The chromium plating solution contains 5 to 10g/l of sodium silicofluoride as a fluoride. In the chromium plating step S22, since chromic acid is present in the chromium plating solution, chromic acid and lead chemically react witheach other, and lead contained in the inner peripheral surface of the cylindrical portion 10 is removed. It is considered that lead chromate formed in the chromium plating solution is dissolved by the fluoride at this time. Further, a water washing step (not shown) is provided between S21 and S22, and the workpiece 50a is washed with water.
In particular, as shown in fig. 1, example 1 further includes a lead removing step S3 after the plating step S2. In this lead removing step S3, the workpiece 50a treated in the plating step S2 is immersed in a pH14 corrosive solution as an active alkali solution for 10 minutes. The corrosive liquid is an aqueous solution containing 50g/l of sodium hydroxide and the temperature is 50 ℃. Thus, the corrosive liquid chemically reacts with lead on the inner peripheral surface of the cylindrical portion 10, and the lead is leached and removed. At this time, since the etching solution is an active alkali solution, copper of the lead-containing copper alloy does not react, but only lead reacts. A water washing step (not shown) is also provided before and after the lead removing step S3, and the workpiece 50a is washed with water.
By adopting the electroplating method of the embodiment 1, a water valve metal piece 50 electroplated product of the embodiment 1 as shown in fig. 7 can be obtained. As shown in fig. 2, the water valve metal member 50 includes: a base portion 30 made of a lead-containing copper alloy of the cylindrical portion 10 with water passing therethrough; a lead-containing layer 30a formed integrally with the base portion 30 on the outer peripheral surface of the cylindrical portion 10 and having a lead concentration substantially equal to that of the base portion; a nickel-chromium plating layer 20 formed on the outer peripheral surface of the lead-containing layer 30 a; and a low lead-containing layer 30b formed integrally with the base portion 30 on the inner peripheral surface of the cylindrical portion 10 and having a lower lead concentration than the base portion 30. When the water valve fitting 50 is used, water W passes through the cylindrical portion 10.
Comparative example 1
The plating method of comparative example 1 is a general nickel-chromium plating method as shown in fig. 13, and differs from the plating method of example 1 in that the lead removing step is not performed after the plating step S2. Other conditions were the same as in example 1.
By the plating method of comparative example 1, a plated product of the water valve metal fitting 50 of comparative example 1 can be obtained.
Comparative example 2
The plating method of comparative example 2 was carried out by immersing in a high pH alkaline solution only in the degreasing step S11 of the general nickel-chromium plating method shown in fig. 13, and the lead removing step S3 was not carried out after the plating step S2, as in comparative example 1.
The alkaline solution used in the degreasing step is an aqueous solution containing 50g/l of sodium hydroxide, 2g/l of sodium alkylbenzenesulfonate as a surfactant, 2g/l of EDTA and 2g/l of ethylenediamine as chelating agents, and 2g/l of sodium m-nitrobenzenesulfonate as an oxidizing agent, and the temperature is 50 ℃. Other conditions were the same as in example 1 and comparative example 1.
The plating method of comparative example 2 was used to obtain a plated product of the water valve metal fitting 50 of comparative example 2.
(evaluation)
The water valve metal 50 of example 1 and comparative examples 1 and 2 was visually checked for the surface properties of the nickel-chromium plating layer 20 by measuring the concentration (ppb) of lead leached in water flowing through the cylindrical portion 10 in accordance with JISS3200-7 (1997) "test method for leaching performance of tap water". The results are shown in Table 1.
TABLE 1
| Concentration of leached lead (ppb) | Surface properties of the coating | |
| Examples | 7 | ○ |
| Comparative example 1 | 30～40 | ○ |
| Comparative example 2 | 12 | × |
As is clear from table 1, the water valve metal 50 of comparative example 1 has good surface properties of the nickel-chromium plating layer 20, but the concentration of the leached lead is increased because the lead removing step S3 is not performed after the plating step S2 in the plating method.
In the water valve metal fitting 50 of comparative example 2, the concentration of the leached lead was somewhat lowered because the metal fitting was immersed in an alkaline solution having a high pH in the plating method degreasing step S11, but the surface properties of the nickel-chromium plating layer 20 were not good.
In contrast, in the water valve metal fitting 50 of example 1, since the lead removing step S3 is performed after the plating step S2, the concentration of leached lead is extremely low, and the surface quality of the nickel-chromium plating layer 20 is good. This is because in the plating method of example 1, since the lead removing step S3 is performed after the plating step S2, the outer circumferential surface of the workpiece 50a is protected from lead removal by the nickel-chromium plating layer 20, and lead is removed only from the inner circumferential surface of the workpiece 50a without the nickel-chromium plating layer 20. Therefore, the outer peripheral surface of the workpiece 50a is not uneven, and the nickel-chromium plating layer 20 is not damaged, so that the outer peripheral surface of the water valve metal piece 50 has good surface properties, and the effect of beautiful appearance is achieved.
In the plating method of example 1, it is not necessary to thicken the nickel-chromium plating layer 20 on the outer peripheral surface of the workpiece 50a in order to maintain the beauty of the water valve fitting 50, and therefore, the manufacturing cost can be reduced.
As described above, according to the plating method of example 1, the amount of lead leaching into water from the inner peripheral surface of the cylindrical portion 10 can be reduced, and the water valve metal 50 can be manufactured at low cost while providing an aesthetic effect.
That is, in the fitting 50 of example 1, since the concentration of lead in the low lead-containing layer 30b on the inner peripheral surface of the cylindrical portion 10 is low, lead is hardly leached into water even when water is passed through the inner peripheral surface. Therefore, when water supplied from the water valve metal member 50 is drunk by a person, the risk of affecting the health of the person can be eliminated. When the water is discharged to rivers and sewers, the pollution to the environment can be reduced.
Example 2
In the plating method of example 2, as shown in fig. 3, a lead removing step S3 is performed on the stock water valve metal 50 obtained by the general nickel-chromium plating step shown in fig. 13. Other conditions were the same as in example 1.
Using the electroplating method of example 2, a stock water valve metal 50 meeting past lead leach standards can be processed into the same water valve metal 50 as in example 1. Thus, with this plating method, compliance with new lead leaching standards can be achieved with little need for special changes in the design of the plant. This can achieve the effect of eliminating the need for an increase in manufacturing cost for the purpose of standard adaptation.
Example 3
In the plating method of example 3, as shown in fig. 4, the lead removing step S3 is performed again on the water valve metal fitting 50 obtained in example 1. Other conditions were the same as in example 1.
With the plating method of example 3, even when a more severe lead leaching standard is implemented, the factory design is hardly changed particularly, and a water valve metal 50 meeting the standard can be obtained. Since the low lead-containing layer 30b of the cylindrical portion 10 does not have to be provided if the conditions of the lead removal step S3 are strictlycontrolled, this plating method also has the effect of eliminating the need to increase the manufacturing cost to meet the standard.
Example 4
In the plating method of example 4, as shown in fig. 5, after the lead removing step S3, a chromate treatment step S4 is further performed as an inerting step.
In the chromate treatment step S4, the workpiece after the lead removal step S3 is immersed in a chromate solution for 1 minute. The chromate solution is an aqueous solution containing 20-100 g/l of anhydrous chromic acid and 10g/l of phosphoric acid, and the temperature is room temperature. The other composition was the same as in example 1.
In the chromate treatment step S4, a chemical reaction between chromic acid and lead occurs due to the action of chromic acid in the chromate solution, and lead contained in the inner peripheral surface of the cylindrical portion 10 is further removed. In this case, both chromic acid and phosphoric acid are considered to effectively promote the lead leaching chemical reaction and the chemical reaction for forming the chromate protection film 40 (see fig. 6), and further, chromic acid is used in both the chromium plating step S22 and the chromate treatment step S4, so that excellent workability can be exhibited.
As shown in fig. 6, the water valve metal fitting 50 of example 4 thus obtained is composed of: a base portion 30 made of a lead-containing copper alloy of the cylindrical portion 10 with water passing therethrough; a lead-containing layer 30a formed integrally with the base portion 30 on the outer peripheral surface side of the cylindrical portion 10 and having a lead concentration substantially equal to that of the base portion 30; a nickel-chromium plating layer 20 formed on the outer peripheral surface side of the lead-containing layer 30 a; a low lead-containing layer 30b formed integrally withthe base portion 30 on the inner peripheral surface of the cylindrical portion 10 and having a lower lead concentration than the base portion 30; and a chromate protective film 40 formed on the inner peripheral surface of the low lead-containing layer 30 b.
Since the chromate coating 40 is formed on the inner peripheral surface of the low lead layer 30b, the lead remaining on the inner peripheral surface of the cylindrical portion 10 is rendered inert by the chromate coating 40 and is thus less likely to be leached out. [ invention 2]
Examples 1 and 2 embodying the invention of claim 2 will be described below together with comparative examples 1 and 2 with reference to the drawings.
Example 1
In the method for preventing lead leaching of example 1, the following two lead-containing copper alloys 1 and 2 were first prepared. The material 1 was bronze composed of 5 mass% of lead, 85 mass% of copper, 5 mass% of zinc, and 5 mass% of tin. The material 2 was brass composed of 2 mass% of lead, 63 mass% of copper, and 35 mass% of zinc.
Then, as shown in fig. 12, the lead-containing copper alloy pieces were cut to obtain various workpieces 50a for a water valve metal fitting. As shown in fig. 9, the workpiece 50a has a cylindrical portion 10 through which water flows. As shown in fig. 8, the following steps are sequentially performed for each workpiece 50 a: a pretreatment step S1 for performing pretreatment; a plating step S2 of applying a nickel-chromium plating layer to the outer peripheral surface of each workpiece 50a after the pretreatment step S1; after the plating step S2, a protective film forming step S3 is performed to form a phosphorus-containing protective film on the surface of each workpiece 50 a.
The pretreatment step S1 includes a degreasing step S11, a cathode electrolysisstep S12, an acid activation step S13, and a water washing step (not shown) provided between these steps, as in the case of the general plating method shown in fig. 13. In the degreasing step S11, the work 50a is immersed in an alkaline solution having a pH of 11 for 5 minutes to degrease the entire surface of the work 50 a. The alkali liquor is an aqueous solution containing sodium hydroxide in g/l, surfactant, chelating agent and oxidant at 40 deg.C. In the cathode electrolysis step S12, the respective works 50a are further degreased in the same alkaline solution with the respective works 50a as cathodes. In the acid activation step S13, each workpiece a is washed with a sulfuric acid aqueous solution having a pH of 2 at room temperature, thereby activating the entire surface of each workpiece 50 a. In addition, a water washing step (not shown) is provided between the steps S11 to S13 to wash the workpieces 50 a.
As shown in fig. 8, the plating step S2 also includes a nickel plating step S21 and a chromium plating step S22, in the same manner as the general plating method shown in fig. 13. In the nickel plating step S21, a nickel plating solution is used to apply a nickel plating layer to the outer peripheral surface of each workpiece 50 a. In the chromium plating step S22, a chromium plating solution is used to apply a chromium plating layer to the outer peripheral surface of each workpiece 50a treated in the nickel plating step S21. The chromium plating solution contains 5 to 10g/l of sodium silicofluoride as a fluoride. In the chromium plating step S22, since chromic acid is present in the chromium plating solution, the chromic acid and lead chemically react with each other, and lead contained in the inner peripheral surface of the cylindrical portion 10 is removed. It is considered that lead chromate formed in the chromium plating solution at this time is dissolved by fluoride. Further, a water washing step (not shown) is provided between S21 and S22, and each workpiece 50a is washed with water.
As shown in fig. 8, the method for preventing lead leaching of example 1 further includes a protective film forming step S3 after the plating step S2. In the resist removal forming step S3, the workpiece 50a after the plating step S2 is immersed in the treatment solution for 10 minutes.
The treating fluid is phosphoric acid (H)3PO4)0.9 mass% aqueous solution at 50 ℃.
Thus, as shown in fig. 9, the treatment liquid reacts with copper and/or lead on the inner peripheral surface of the cylindrical portion 10, and a phosphorus-containing protective film 40 is formed on the inner peripheral surface of the cylindrical portion 10. A water washing step (not shown) is also provided before and after the protective film forming step S3, and each workpiece 50a is washed with water.
By the above method for preventing lead leaching, a plated product of the water valve metal fitting 50 shown in fig. 12 can be obtained. As shown in fig. 9, the various water valve hardware 50 include: the base portion 30 made of a lead-containing copper alloy of the cylindrical portion 10 with water passing therethrough, the lead-containing layer 30a formed integrally with the base portion 30 on the outer peripheral surface side of the cylindrical portion 10 and having a lead concentration substantially equal to that of the base portion 30, the nickel-chromium plated layer 20 formed on the outer peripheral surface of the lead-containing layer 30a, the lead-containing layer 30b formed integrally with the base portion 30 on the inner peripheral surface of the cylindrical portion 10 and having a lead concentration substantially equal to that of the base portion 30, and the phosphorus-containing protective film 40 formed on the inner peripheral surface of the lead-containing layer 30 b. When the water valve fittings 50 are used, water W passesthrough the cylindrical portion 10.
Example 2
In the method for preventing lead leaching in example 2, each of the workpieces 50a for a water valve metal fitting shown in fig. 12 was obtained from two lead-containing copper alloys of the materials 1 and 2, as in example 1.
The lead leaching prevention method of example 2 is different from the lead leaching prevention method of example 1 in that, as shown in fig. 10, the processing times of the lead removing step S4 and the protective film forming step S3 for removing lead from each workpiece 50a are different between the plating step S2 and the protective film forming step S3.
In the lead removing step S4, each work 50a subjected to the plating step S2 is immersed in an etching solution of pH14 as an active alkali solution for 3 minutes. The etching solution was a 5 mass% aqueous solution of sodium hydroxide at a temperature of 50 ℃. The corrosive liquid chemically reacts with lead on the inner peripheral surface of the cylindrical portion 10 to leach out and remove the lead. At this time, since the etching solution is an active alkali solution, it does not react with copper of the lead-containing copper alloy, but only with lead. Before and after this lead removing step S4, a water washing step (not shown) is also provided to wash each workpiece 50a with water.
In the protective film forming step S3, the workpiece 50a after the lead removing step S4 is immersed in the treatment solution for 3 minutes. Other conditions were the same as in example 1.
A plated product of each of the water valve metal fittings 50 shown in fig. 12 was obtained in the same manner as in example 1 by the lead leaching prevention method in example 2. As shown in fig. 11, each of the water valve metal members 50 is composed of: the base portion 30 made of a lead-containing copperalloy of the cylindrical portion 10 with water passing therethrough, the lead-containing layer 30a formed integrally with the base portion 30 on the outer peripheral surface side of the cylindrical portion and having a lead concentration substantially equal to that of the base portion 30, the nickel-chromium plated layer 20 formed on the outer peripheral surface side of the lead-containing layer 30a, the low lead-containing layer 30c formed integrally with the base portion 30 on the inner peripheral surface of the cylindrical portion 10 and having a lead concentration lower than that of the base portion 30, and the phosphorus-containing protective film 40 formed on the inner peripheral surface side of the low lead-containing layer 30 c.
Comparative example 1
In the method for preventing lead leaching of comparative example 1, each of the workpieces 50a for a water valve metal fitting shown in fig. 12 was obtained from two lead-containing copper alloys of the materials 1 and 2, respectively, in the same manner as in example 1.
However, in comparative example 1, only the general nickel-chromium plating method shown in fig. 13 was used to apply the nickel-chromium plating layer, and no special lead leaching prevention method was used. Other conditions were the same as in example 1.
A water valve metal fitting 50 plated product of comparative example 1 was obtained by the plating method of comparative example 1.
Comparative example 2
In the method for preventing lead leaching of comparative example 2, as in example 1, each of the workpieces 50a for the water valve metal fitting shown in fig. 12 was obtained from two lead-containing copper alloys of the materials 1 and 2.
However, the method for preventing lead leaching of comparative example 2does not include the protective film forming step S3 in the method for preventing lead leaching of example 2 shown in fig. 10. Further, the lead removing step S4 is different from example 2 in that each workpiece 50a is immersed in an etchant of pH14 as an active alkali solution for 10 minutes. Other conditions were the same as in example 2.
Using the method for preventing lead leaching of comparative example 2, a plated product of the water valve metal fitting 50 of comparative example 2 was obtained.
(evaluation)
The concentrations (ppb) of lead leached in the water flowing through the cylindrical portion 10 were measured for the valve metal fittings 50 of examples 1 and 2 and comparative examples 1 and 2, in accordance with JISS3200-7 (1997) "test method for leaching performance of tap water apparatus". The results are shown in Table 2.
TABLE 2
| Concentration of leached lead (ppb) | ||
| | | |
| Example 1 | 9 | 4 |
| Example 2 | 5 | 1 |
| Comparative example 1 | 60 | 13 |
| Comparative example 2 | 20 | 4 |
As is clear from table 2, the water valve metal 50 of comparative example 1 has a high lead concentration due to the absence of the protective film forming step S3 after the plating step S2. On the other hand, in the water valve metal fitting 50 of comparative example 2, although the protective film forming step S3 was not performed after the plating step S2, the lead removal step S4 was performed, and therefore the lead leaching concentration was low for the material 2. However, the lead leaching concentration is not reduced much for material 1. In addition, in order to reduce the concentration of the leached lead to a certain degree, each workpiece 50a is immersed in the etching solution for a long time in the lead removal step S4.
In contrast, in the water valve metal fitting 50 of example 1, since the protective film forming step S3 was performed after the plating step S2, the concentration of lead leached was low in both the materials 1 and 2. However, in example 1, in order to reduce the leached lead concentration to some extent, it is preferable to immerseeach workpiece 50a in the treatment liquid for a long time.
On the other hand, in the water valve metal fitting 50 of example 2, after the plating step S2, the lead removing step S4 and the protective film forming step S3 were performed, and therefore the concentration of lead leached out was extremely low. In example 2, since the protective film forming step S3 was performed, it is sufficient to immerse each workpiece 50a in the etching solution for 3 minutes in the lead removing step S4. That is, in example 2, although the lead removing step S4 and the protective film forming step S3 were performed, the total time required for these steps was 6 minutes, which was shorter than the 10 minutes required for the lead removing step S4 in comparative example 2, and the workability in example 2 was found to be superior.
The reason why the concentration of the lead leached out is low in the water valve metal 50 of examples 1 and 2 is considered that the phosphoric acid-containing protective film 40 formed on the inner peripheral surface of the cylindrical portion 10 in the protective film forming step S3 can prevent the lead leaching out.
In addition, in the lead leaching prevention methods of examples 1 and 2, a solution in which phosphoric acid or phosphate is mainly added to water is used as the treatment liquid, and phosphoric acid or phosphate has little toxicity compared with a chromic acid-containing chromium plating liquid for forming a chromium plating layer and a chromic acid-containing chromate liquid for performing inerting. Therefore, the cleaning liquid and the waste liquid of each workpiece 50a after being contacted with the treatment liquid are neutralized and diluted, and the cleaning liquid and the like can be treated. Therefore, the management of the cleaning liquid and the like is simple.
Therefore, according to the lead leaching prevention methods of embodiments1 and 2, the amount of lead leached out into water from the inner peripheral surface of the cylindrical portion 10 can be reduced, and an inexpensive water valve metal 50 can be manufactured.
Finally, in the fitting 50 of examples 1 and 2, since the phosphorus-containing protective film 40 formed on the inner peripheral surface of the cylindrical portion 10 can prevent lead from leaching, lead is less likely to enter water even if water is passed through the inner peripheral surface. Therefore, when the water supplied from the water valve fitting 50 is drunk by a person, the concern of influencing the health of the person can be eliminated. In addition, when the water is discharged to rivers and sewers, the pollution to the environment can be reduced.
(test)
Several pieces 50a of the same metal fitting for a water valve as shown in fig. 12 as in example 1 were obtained from a lead-containing copper alloy of material 3 shown below. The material 3 was bronze composed of 5 mass% of lead, 85 mass% of copper, 5 mass% of zinc, and 5 mass% of tin.
As shown in fig. 10, the work 50a was treated in the same manner as in example 2 in the order of the pretreatment step S1, the plating step S2, the lead removal step S4, and the protective film formation step S3, to obtain plated products of the water valve metal fittings 50 of samples 1 to 6.
(evaluation)
The lead leaching concentration (ppb) of water flowing through the cylindrical portion 10 was measured for the water valve metal fittings 50 of these samples 1 to 6 in accordance with the above-mentioned "apparatus for tap water — leaching performance test method". In this case, the processing conditions such as the phosphoric acid concentration (mass%), the processing temperature (c), and the processing time (sec) in the protectivefilm forming step S3 performed on the water valve metal 50 of the samples 1 to 6 are different. Other conditions were the same as in example 2. The results are shown in Table 3, using the processing conditions for the water valve metal 50 of sample 1 as a standard.
TABLE 3
| Sample number | Concentration of phosphoric acid (mass%) | Temperature of treatment (℃) | Time of treatment (second) | Concentration of leached lead (ppb) |
| 1 | 0.9 | 50 | 180 | 3 |
| 2 | 0.01 | 50 | 180 | 9 |
| 3 | 10.0 | 50 | 180 | 9 |
| 4 | 0.9 | 5 | 180 | 9 |
| 5 | 0.9 | 50 | 600 | 1 |
| 6 | 0.9 | 50 | 5 | 9 |
As can be seen from Table 3: from the data of the water valve metal 50 of samples 1 to 3, it is considered that the concentration of phosphoric acid is most preferable to be 0.9 mass%, and if it is 0.01 to 10.0 mass%, the concentration of lead in leaching does not change so much, and a good effect can be obtained.
Although it is estimated that the higher the temperature of the treatment liquid, the better, it is considered that the concentration of the leached lead hardly changes even if the temperature of the treatment liquid is lowered to 5 ℃ from the data of the water valve metal 50 of sample 4, and a sufficient effect can be obtained. Therefore, the method of the present invention can also achieve sufficient effects in winter.
It is generally estimated that the longer the treatment time, the better the treatment time, but it is found from the data of the water valve metal 50 of the samples 5 and 6 that the concentration of the leached lead hardly changes even in a short treatment time of 5 seconds, and a good effect can be obtained. Therefore, the method of the present invention can obtain sufficient effects even by a relatively short time of treatment.
The above embodiments and applications are examples. The inventions 1 and 2 can be implemented in various forms without departing from the main object thereof.
Possibility of industrial utilization
The method of removing lead according to claim 1 can produce an inexpensive plated product with a beautiful appearance by reducing the amount of lead leached into water inside the cylindrical portion.
With the lead leaching prevention method of claim 2, the amount of lead leached into water from the lead-containing copper alloy can be simply reduced. Therefore, the method for preventing lead leaching according to claim 2 can prevent lead leaching and reduce the manufacturing cost. In addition, the water valve metal fitting according to claim 2 can reduce the amount of lead leaching into water. And can be easily manufactured.
Claims (19)
1. A method for removing lead from a lead-containing copper alloy plated article having a cylindrical portion, characterized by comprising: and a lead removing step of removing lead from the inner peripheral surface of the cylindrical portion of the product obtained by subjecting the outer peripheral surface of the lead-containing copper alloy workpiece having the water-passing cylindrical portion to a plating step in which a plating layer is applied.
2. The method of lead removal of a lead-containing copper alloy plated article having a cylindrical portion according to claim 1, wherein: after the lead removing step, an inerting step is performed to inert the inner peripheral surface of the cylindrical portion.
3. The method of removing lead from a lead-containing copper alloy plated article having a cylindrical portion according to claim 1 or 2, wherein: the lead removing step is performed by immersing the cylindrical portion in an etching solution capable of etching lead from the inner peripheral surface of the cylindrical portion.
4. The method of removing lead from a lead-containing copper alloy plated article having a cylindrical portion according to claim 3, wherein: the corrosive liquid is active alkali liquid.
5. The method of lead removal of a lead-containing copper alloy plated article having a cylindrical portion according to claim 1, wherein: the plating step includes a chromium plating step of performing plating using a chromium plating solution containing chromic acid, and the inerting step includes a chromate treatment step of immersing the workpiece in a chromate solution containing chromic acid.
6. The method of removing lead from a lead-containing copper alloy plated article having a cylindrical portion according to claim 5, wherein: the chromium plating solution contains fluoride.
7. The method of removing lead from a lead-containing copper alloy plated article having a cylindrical portion according to claim 5, wherein: the chromate solution contains phosphoric acid.
8. The method of lead removal of a lead-containing copper alloy plated article having a cylindrical portion according to claim 1, wherein: the workpiece is used as a water valve metal piece.
9. A water valve metal piece is characterized by comprising the following parts: a base body portion made of a lead-containing copper alloy having a water-passing cylindrical portion; a lead-containing layer formed integrally with the base portion on the outer peripheral surface of the cylindrical portion and having a lead concentration substantially equal to that of the base portion; a plating layer formed on the outer peripheral surface of the lead-containing layer; a low lead-containing layer having a lower lead concentration than the base portion is formed integrally with the base portion on the inner peripheral surface of the cylindrical portion.
10. The water valve metal fitting of claim 9 wherein: the low lead-containing layer does not contain lead.
11. A water valve metal part as claimed in claim 9 or claim 10 wherein: the inner peripheral surface of the low lead-containing layer is a chromate protective film.
12. A method for preventing lead leaching of a lead-containing copper alloy product, characterized by comprising the following protective film forming steps: a method for producing a lead-containing copper alloy includes preparing a work made of a lead-containing copper alloy and a treatment liquid mainly containing phosphoric acid or a phosphate in water, bringing the work into contact with the treatment liquid, and forming a phosphorus-containing protective film on the surface of the work.
13. The method for preventing lead leaching of a lead-containing copper alloy product according to claim 12, wherein: the concentration of phosphoric acid or phosphate in the treatment liquid is 0.01 to 10.0 mass%.
14. The method for preventing lead leaching of a lead-containing copper alloy product according to claim 12 or 13, wherein: before the protective film forming step, a lead removing step of removing lead from the surface of the workpiece is performed.
15. The method for preventing lead leaching of a lead-containing copper alloy article according to claim 14, wherein: the lead removing step is performed by immersing the substrate in an etchant that can corrode lead.
16. The method for preventing lead leaching of a lead-containing copper alloy article according to claim 15, wherein: the corrosive liquid is active alkali liquid.
17. The method for preventing lead leaching of a lead-containing copper alloy article according to claim 16, wherein: the workpiece is an electroplated product with a nickel-chromium coating on the outer peripheral surface, and the electroplated product is subjected to a lead removing process.
18. A water valve metal article, comprising: a base body portion made of a lead-containing copper alloy having a water-passing cylindrical portion; a phosphorus-containing protective film formed integrally with the base portion at least on the inner peripheral surface of the cylindrical portion.
19. The water valve metal fitting of claim 18 wherein: the protective film is formed on the surface of the low lead-containing layer.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000332190 | 2000-10-31 | ||
| JP332190/2000 | 2000-10-31 | ||
| JP332190/00 | 2000-10-31 | ||
| JP32006/01 | 2001-02-08 | ||
| JP32006/2001 | 2001-02-08 | ||
| JP2001032006 | 2001-02-08 |
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| CN1274881C CN1274881C (en) | 2006-09-13 |
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| CN 01818302 Expired - Lifetime CN1274881C (en) | 2000-10-31 | 2001-10-29 | Method for removing lead from plated cylindrical article made of lead-containing copper alloy and metal fitting for hydrant, and method for preventing leaching of lead from article made of lead-contai |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP3866198B2 (en) |
| CN (1) | CN1274881C (en) |
| AU (1) | AU2001296025A1 (en) |
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| JP2005023338A (en) * | 2003-06-30 | 2005-01-27 | Inax Corp | Method of producing apparatus for city water made of lead-containing copper alloy |
| US8182879B2 (en) | 2004-03-05 | 2012-05-22 | Kitz Corporation | Method for preventing elution of nickel from water-contact instrument of copper alloy by formation of a protective film |
| JP5473781B2 (en) * | 2009-06-01 | 2014-04-16 | 株式会社Ｌｉｘｉｌ | Manufacturing method and processing method for lead-containing copper alloy water supply equipment |
| CN103143890A (en) * | 2013-03-04 | 2013-06-12 | 阮伟光 | Manufacturing method for low lead copper alloy bath utensil |
| JP6596876B2 (en) * | 2015-03-31 | 2019-10-30 | Ｔｏｔｏ株式会社 | Method of manufacturing water supply appliances with suppressed elution of lead and nickel |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1072683A (en) * | 1996-08-30 | 1998-03-17 | Toto Ltd | Treatment for preventing elution of lead from faucet fitting made of lead-containing copper alloy |
| JP3182765B2 (en) * | 1997-12-03 | 2001-07-03 | 東陶機器株式会社 | Lead elution reduction treatment method for lead-containing copper alloy, lead elution reduction plating method for lead-containing copper alloy, and lead-containing copper alloy water supply device |
| JP2000096269A (en) * | 1999-08-06 | 2000-04-04 | Toto Ltd | Treatment of lead-containing copper alloy for suppressing leaching of lead and implement for water service made of lead-containing copper alloy |
| JP2000096270A (en) * | 1999-08-06 | 2000-04-04 | Toto Ltd | Method for reducing elution of lead from lead-containing copper alloy and water service instrument made of lead- containing copper alloy |
-
2001
- 2001-10-29 JP JP2002539591A patent/JP3866198B2/en not_active Expired - Fee Related
- 2001-10-29 CN CN 01818302 patent/CN1274881C/en not_active Expired - Lifetime
- 2001-10-29 AU AU2001296025A patent/AU2001296025A1/en not_active Abandoned
- 2001-10-29 WO PCT/JP2001/009488 patent/WO2002036856A1/en active Application Filing
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101003899B (en) * | 2007-01-17 | 2010-05-19 | 泉州中宇卫浴科技实业有限公司 | Deleading technique for surface of lead brass and copper alloy |
| CN108085684A (en) * | 2017-11-23 | 2018-05-29 | 中国科学院近代物理研究所 | For going the chemical decoating liquid of copper removal surface niobium coating and strip method |
| CN108085684B (en) * | 2017-11-23 | 2019-10-08 | 中国科学院近代物理研究所 | For going the chemical decoating liquid and strip method of copper removal surface niobium coating |
| CN111247297A (en) * | 2018-09-27 | 2020-06-05 | Toto株式会社 | Water faucet part |
| CN111263832A (en) * | 2018-09-27 | 2020-06-09 | Toto株式会社 | Sanitary equipment component |
| US11795671B2 (en) | 2018-09-27 | 2023-10-24 | Toto Ltd. | Faucet fitting |
| CN112981408A (en) * | 2021-02-04 | 2021-06-18 | 九牧厨卫股份有限公司 | Lead removing agent and surface lead removing process of lead brass component |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2001296025A1 (en) | 2002-05-15 |
| JP3866198B2 (en) | 2007-01-10 |
| WO2002036856A1 (en) | 2002-05-10 |
| JPWO2002036856A1 (en) | 2004-03-11 |
| CN1274881C (en) | 2006-09-13 |
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