CN1274881C - Method for removing lead from lead-containing copper alloy electroplated product with cylindrical part and water valve metal parts - Google Patents

Abstract

The present invention provides a lead removal method that reduces the amount of lead leached into water from the inner circumference of a cylindrical portion, enhances the aesthetics, and produces electroplated products at a low cost. The method comprises the following steps: a pretreatment step S1 of pre-treating a lead-containing copper alloy workpiece 50a having a water-permeable cylindrical portion 10; an electroplating step S2 of applying a nickel-chromium plating layer 20 to the outer circumference of the workpiece 50a after pretreatment step S1; and a lead removal step S3 of removing lead from the inner circumference of the cylindrical portion 10 after electroplating step S2.

Description

Method for removing lead from lead-containing copper alloy electroplated product with cylindrical part and water valve metal parts

technical field

The first invention relates to a method for removing lead from a lead-containing copper alloy electroplated product with a cylindrical part and a water valve metal part. The second party discloses a method for preventing lead leaching of lead-containing copper alloy products and a metal part of a water valve. The method for preventing lead leaching of lead-containing copper alloy products according to the second invention is suitable for a method of manufacturing water valve metal parts.

Background technique

For example, for waterway components such as water valve metal parts and water pipes, copper alloys such as bronze and brass are generally used from the perspective of corrosion resistance, and for water valve metal parts with particularly complicated shapes, from the viewpoint of machinability Use leaded copper alloys. The lead-containing copper alloy that constitutes the metal parts of the water valve is processed by casting and other processes, and then processed into a workpiece for the metal parts of the water valve with a cylindrical part through which water passes. Then, on this workpiece, mainly from the decorative considerations, the method of electroplating nickel-chromium will be used to form a nickel-chromium coating to make water valve metal parts.

The general electroplating nickel-chromium method all possesses each process as shown in Figure 13, promptly this workpiece is carried out the pretreatment process S1 of pretreatment, and after this pretreatment process S1, applies nickel-chromium to the outer peripheral surface of the workpiece. Electroplating process S2 of the plating layer.

More specifically, the pretreatment step S1 further includes a degreasing step S11 in which the workpiece is immersed in an alkaline solution to degrease the entire surface of the workpiece. The lye used here is usually an alkaline aqueous solution formed by dissolving sodium hydroxide or the like in water. The workpiece can be degreased according to the pH of the lye by immersing the workpiece in the lye. In addition, lead can also be corroded and removed by adjusting the pH of the lye. In the pretreatment process S1, in addition to the degreasing process S11, there are the following processes: the cathodic electrolysis process S12 in which the entire surface of the workpiece is further degreased with the workpiece as the cathode in the lye, and the entire surface of the workpiece is cleaned with acid solution. Activated acid activation step S13, and a water washing step between these steps.

In addition, the electroplating process S2 also has the following process: use a nickel plating electrolyte to apply a nickel plating process S21 on the outer peripheral surface of the workpiece after the pretreatment process S1, use a chromium plating electrolyte, and after the nickel plating process S21 A chromium plating process S22 in which a nickel-chromium layer is applied to the outer peripheral surface of the workpiece, and a water washing process provided between these processes.

In this way, the water valve metal fitting obtained in the form of a plated product can be used for passing water in the cylindrical part.

Contents of the invention

{1st invention}

However, in recent years, people are more and more afraid of the harm to human health caused by lead in water, so it is required to further reduce the amount of lead leaching into water from the inner wall of the electroplated product such as water valve metal parts. For this reason, in the above-mentioned existing general nickel-chromium electroplating method, lead removal should be easy to carry out, as long as in the degreasing process S11, immerse in the lye of high pH, before the electroplating process S2, lead is removed from the workpiece by corrosion. The entire surface is removed, but the entire surface of the workpiece is prone to unevenness. Therefore, even if the plating layer is applied to the outer peripheral surface of the workpiece by performing the subsequent electroplating step S2, unevenness is likely to occur on the outer periphery of the electroplated product, and the surface quality of the outer peripheral surface of the electroplated product is deteriorated. Therefore, the aesthetic effect of the plated product is lost.

If the aesthetic effect of the electroplating product is maintained by thickening the coating thickness of the outer peripheral surface of the workpiece, it will inevitably lead to high manufacturing costs.

This undesirable situation, to the workpiece that uses lead-containing copper alloy, all can appear in the electroplating product of band water-passing cylindrical part. Especially when the electroplated product is a water valve metal part with complex shape, the problem is even greater.

The first invention is made in view of the above-mentioned existing practical problems, and will provide a method for removing lead that can reduce the amount of lead dissolved in water from the inner wall of the cylindrical part, have an excellent aesthetic effect, and simultaneously produce electroplated products at low cost, as A major issue that should be addressed.

In the first invention, it is also a problem to be solved to reduce the amount of leaching of lead into water, to achieve an excellent aesthetic effect, and to be able to manufacture water valve metal parts at low cost.

The method for removing lead from a lead-containing copper alloy electroplated product with a cylindrical part of the first invention is characterized in that: the workpiece obtained after the electroplating process of applying a plating layer is carried out to the outer peripheral surface of a lead-containing copper alloy workpiece with a water-passing cylindrical part, and the process is carried out from the Lead removal process for removing lead from the inner peripheral surface of the cylindrical part.

In the lead removal method of the first invention, since the lead removal is performed after the electroplating process, the outer peripheral surface of the workpiece is protected, and the lead removal is not performed, but only the inner surface of the workpiece without the plating layer is removed. Therefore, no unevenness occurs on the outer peripheral surface of the workpiece, the coating is not damaged, and the outer peripheral surface of the coated product has excellent surface properties. Therefore, this electroplating product is beautiful and beautiful.

In addition, in the lead removal method of the first invention, in order to maintain the appearance of the electroplated product, it is not necessary to apply a thicker plating layer on the outer peripheral surface of the workpiece, so the requirement of low manufacturing cost can be realized.

In the lead removal method of the first invention, if the workpiece of the water valve metal part is used, the water valve metal part of the first invention as a plated product can be obtained. The water valve metal part is characterized in that it is composed of the following parts: a base part composed of a lead-containing copper alloy with a cylindrical part; the outer peripheral surface of the cylindrical part is integrated with the base part, and the lead concentration is approximately the same as that of the base part. An equal lead-containing layer; an electroplating layer formed on the outer peripheral surface of the lead-containing layer; a low-lead-containing layer formed integrally with the base part on the inner peripheral surface of the cylindrical part and having a lower lead concentration than the base part.

In the water valve metal fitting of the first invention, since the lead concentration contained in the low lead-containing layer on the inner peripheral surface of the cylindrical portion is low, even if water passes through the inner peripheral surface, lead is difficult to leach into the water. Therefore, when people drink the water supplied by the metal part of the water valve, the doubts about the impact on human health can be eliminated. In addition, when the water is discharged into rivers or sewers, it is also possible to reduce the impact on the environment.

In the water valve metal fitting of the first invention, since there is a lead-containing layer having a lead concentration substantially equal to that of the base portion on the outer peripheral surface of the cylindrical portion, and an electroplated layer is formed on the outer peripheral surface of the lead-containing layer, the lead-containing layer does not have unevenness. The metal parts of the water valve are still beautiful in appearance.

In addition, in the water valve metal part of the first invention, since the thickness of the electroplating layer does not need to be thickened, the manufacturing cost can be reduced.

In the lead removal method of the first invention, it is preferable to provide an inertization step of inertizing the cylindrical portion after the lead removal step. In this way, by means of the inertization process, the inner peripheral surface becomes inert, and the amount of lead leached from the low lead-containing layer can be further reduced.

In the lead removal method of the first invention, the lead removal step can be carried out by immersing the workpiece in an etching solution capable of corroding lead from the inner peripheral surface of the cylindrical portion. Because this corrosive solution can chemically react with the lead on the inner peripheral surface, leaching and removing the lead.

Acids or lyes are conceivable as corrosive liquids. However, copper reacts with acid, while lead is an amphoteric metal, which reacts to both acid and alkali, so it is better to use lye as corrosion solution, especially active lye. This active lye refers to lye with a pH range of 12-14. The use of lye with a pH within this range is likely to chemically react with the lead on the inner peripheral surface, so it is easier to dissolve and remove the lead. This active lye is mainly sodium carbonate, sodium hydroxide, sodium phosphate, sodium orthosilicate, sodium triphosphate, sodium orthosilicate, potassium hydroxide and other aqueous solutions.

The etchant preferably contains a surfactant. If the etching solution contains a surfactant, the surface tension of the etching solution can be lowered, so that the penetration and wettability of the etching solution to the inner peripheral surface of the cylindrical portion can be improved. Therefore, a chemical reaction between the lead contained in the inner peripheral surface and the corrosion solution easily occurs.

As the surfactant, anionic surfactants and nonionic surfactants can be used. Examples of anionic surfactants that can be used include sodium higher fatty acid, sulfated oil, sodium salt of higher alcohol sulfate, sodium alkylbenzene sulfate, sodium higher alkyl ether sulfate, sodium α-olefin sulfate, and the like. As the nonionic surfactant, for example, alkyl polyoxyethylene ether, alkylphenyl polyoxyethylene ether, fatty acid ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, and the like can be used.

Preferably, the corrosive solution also contains a chelating agent. Since the chelating agent chemically reacts with lead to form a water-soluble complex, the lead contained in the inner peripheral surface of the cylindrical portion can be easily removed.

As the chelating agent, for example, ethylenediamine, thiourea, tartaric acid, Rochelle's salt (potassium sodium tartrate tetrahydrate), EDTA, triethanolamine, etc. can be used.

Preferably, the corrosive liquid also contains an oxidizing agent. That is to say, if it is desired to remove the lead contained in the inner peripheral surface of the cylindrical portion with only one corrosive solution of active lye, the lead will be dissolved due to the following chemical reaction.

(1)

On the contrary, if the active lye corrosion solution contains an oxidizing agent, the oxidizing agent first reacts with lead as shown in the following reaction formula (2) to form lead oxide.

(2)

Then, the lead oxide is leached and dissolved in the alkaline corrosion solution, and the chemical reaction shown in the following reaction formula (3) occurs to form lead salt.

(3)

Compared with the reaction of the above-mentioned single reaction formula (1), there are two kinds of reaction methods of the above-mentioned reaction formula (1) and the reaction formula (2), and the reaction is carried out more rapidly. Lead contained in the inner peripheral surface of the cylindrical part is removed.

As the oxidizing agent, for example, sodium m-nitrobenzenesulfonate, sodium p-nitrobenzoate, hypochlorite, bleaching powder, hydrogen peroxide, potassium permanganate, persulfate, perchlorate and the like can be used.

In the lead removal method of the first invention, the electroplating step preferably includes a chromium plating step using a chromium electroplating solution containing chromic acid, and the inertization step preferably includes chromic acid in which the workpiece is immersed in a chromate solution containing chromic acid. Salt treatment process.

First, in the chromium plating process, due to the action of chromic acid in the chromium plating solution, chromic acid and lead undergo a chemical reaction as shown in reaction formula (4) to form lead chromate, because lead chromate is insoluble, so it becomes inert. Therefore, lead does not leach from the outer peripheral surface of the workpiece.

(4)

Thereafter, in the chromate treatment process carried out through the lead removal process, due to the action of chromic acid in the chromate solution, a chemical reaction as shown in the above reaction formula (4) occurs between chromic acid and lead to form chromic acid lead. In this way, even if a trace amount of lead is contained in the inner peripheral surface of the cylindrical portion of the workpiece, it will not be leached out. In addition, in both the chromium plating process and the chromate treatment process, due to the use of chromic acid, superiority in work can be obtained.

In this chromate treatment step, a chromate protective film (xCr ₂ O ₃ ·y CrO ₃ • zH ₂ O).

(5)

(6)

(7)

In the water valve metal parts obtained in this way, since the chromate protective film is formed on the inner peripheral surface of the low-lead-containing layer, the lead remaining on the inner peripheral surface of the cylindrical part is rendered inert by the action of the chromate protective film. melted and difficult to leach.

As the chromate solution, in addition to chromic acid, a solution containing sulfuric acid, etc. can be used, and a solution in which chromate, oxalic acid, acetic acid, hydrofluoric acid, nitric acid, etc. are added can also be used. The chromate agent used in galvanizing etc. is used as chromate solution.

The chromium plating solution used in the first invention preferably contains fluoride, because it is generally believed that the lead chromate formed in the chromium plating solution can be dissolved by 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, zirconate fluoride, stannate fluoride, fluoride Strontium, thallium fluoride, tantalate fluoride, nitrogen fluoride, iron fluoride, copper fluoride, sodium fluoride, niobium fluoride, nickel fluoride, barium fluoride, arsenic fluoride, boron fluoride, Fluorinated boric acid, magnesium fluoride, manganese fluoride, methyl fluoride, iodine fluoride, iodate fluoride, lithium fluoride, phosphorus fluoride, rhenium fluoride, etc. It is generally believed that fluoride such as silicon fluoride can 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.

(8)

Phosphoric acid is preferably contained in the chromate solution used in the first invention. Because it is generally believed that both chromic acid and phosphoric acid can effectively promote the chemical reaction of dissolving lead and the chemical reaction of forming a chromate protective film. Therefore, lead contained in the inner peripheral surface of the cylindrical portion can be effectively dissolved, and at the same time, a chromate protective film can be effectively formed on the inner peripheral surface. In addition, the following compounds can also be used instead of phosphoric acid, such as: ammonium phosphate, phosphate ester, potassium phosphate, calcium phosphate, iron phosphate, tri-n-butyl phosphate, tricresyl phosphate, triphenyl phosphate, sodium phosphate, ammonium dihydrogen phosphate , Potassium dihydrogen phosphate, magnesium phosphate, magnesium ammonium phosphate, lithium phosphate, phospholipids, phosphor bronze, phosphotungstic acid, phosphotungstate, phosphomolybdic acid, phosphomolybdate, etc.

In the water valve metal parts thus obtained, it is preferable not to contain lead in the low-lead layer. If no lead is contained in the low-lead-containing layer, lead will not leach into the water passing through the inner peripheral surface, and the lead on the inner surface is rarely leached through the low-lead-containing layer.

{Second Invention}

In recent years, the harm to human health caused by lead contained in water has become more and more daunting, and people demand to further reduce the amount of lead leaching from lead-containing copper alloy products such as water valve metal parts into water. Especially for water valve metal fittings with a cylindrical portion, it is required to reduce the amount of lead leached into water from the inner peripheral surface of the cylindrical portion.

The 2nd invention is made in view of the above-mentioned existing actual situation, and it will provide a method for preventing lead leaching from lead-containing copper alloy products that can easily reduce the amount of lead leached into water from lead-containing copper alloy products as a subject. In particular, the second invention provides a solution that can reduce the amount of lead leaching in water and can easily manufacture water valve metal parts as a problem to be solved.

In order to solve the above-mentioned problems, the present inventors conducted trial-and-error studies and found that if the workpiece of lead-containing copper alloy products is immersed in a treatment liquid such as aqueous phosphoric acid solution, a phosphorus-containing protective film can be formed on the surface of the workpiece, thereby solving the above-mentioned problem. Problem, so that the present invention has been accomplished.

That is to say, the method for preventing lead leaching of lead-containing copper alloy products according to the second invention is characterized in that it first prepares the workpiece of lead-containing copper alloy products and mainly adds a treatment solution of phosphoric acid or phosphate to water, and then the treatment solution The process of forming a protective film by contacting with a workpiece to form a phosphorus-containing protective film on the surface of the workpiece.

In the method for preventing lead leaching from lead-containing copper alloy products according to the second invention, the protective film formed in the protective film forming step can prevent lead leaching. Such a protective film is generally considered to be formed as follows when a treatment solution mainly composed of zinc dihydrogen phosphate (Zn(H ₂ PO ₄ ) ₂ ) and (H ₃ PO ₄ ) is used.

First, as soon as this treatment solution contacts the lead-containing copper alloy workpiece, as shown in the reaction formula (9), copper is dissolved in the treatment solution to generate copper ions due to the action of phosphoric acid.

(9)

And, if there is lead on the workpiece surface, as shown in reaction formula (10), due to the effect of phosphoric acid, lead will also be dissolved in the treatment solution to generate lead ions.

(10)

Here, zinc dihydrogen phosphate is partially dissociated in the treatment solution as shown in Reaction (11).

(11)

Therefore, it is generally believed that the copper ions and/or lead ions in the treatment solution will react as shown in the following reaction formula (12) and reaction formula (13), forming a phosphorus-containing protective film on the surface of the workpiece.

(12)

(13)

In addition, it is generally believed that, in addition to Zn ₂ Cu(PO ₄ ) ₂ and Zn ₂ Pb(PO ₄ ) ₂ , Zn ₃ (PO ₄ ) ₂ ·4H ₂ O and/or Zn(H ₂ PO ₄ ) ₂ No protective film made of active crystals. According to the experimental results of the present inventors, the protective film thus formed can prevent the leaching of lead.

In addition, in this method for preventing lead leaching, a solution in which phosphoric acid or phosphate is mainly added to water is used as a treatment liquid. Phosphoric acid or phosphate is almost non-toxic compared with the chromium plating solution containing chromic acid composed of hexavalent chromium for forming a chromium plating layer and the chromate solution containing chromic acid for inertization. Therefore, as for the washing liquid and the waste liquid which wash the workpiece after contacting the treatment liquid, these washing liquids can be treated by neutralizing and diluting them. Therefore, compared with the treatment methods of the chromate solution containing chromic acid disclosed in JP-A No. 2000-96269 and JP-A No. 2000-96270, the treatment of washing liquid and the like is relatively simple.

The phosphoric acid used in the second invention is a series of acids (P ₂ O ₅ ·nH ₂ O) formed by hydration of phosphorus pentoxide (P ₂ O ₅ ) in different degrees. For example, orthophosphoric acid (H ₃ PO ₄ (0.5P ₂ O ₅ ·1.5H ₂ O)), metaphosphoric acid (HPO ₃ (0.5P ₂ O ₅ ·0.5H ₂ O) and the like.

As the phosphate used in the second invention, zinc phosphate, manganese phosphate, iron phosphate, zinc calcium phosphate and the like can be used. Examples of the zinc phosphate-based phosphate include phosphate containing zinc dihydrogen phosphate (Zn(H ₂ PO ₄ ) ₂ ) as a main component. Others include sodium phosphate (Na(H ₂ PO ₄ ) ₂ , Na ₂ HPO ₄ , etc.), aluminum phosphate (Al(H ₂ PO ₄ ) ₃ , etc.), ammonium phosphate (NH ₄ H ₂ PO _{4 ,} etc.) and the like.

In the second invention, the concentration of phosphoric acid or phosphate in the treatment liquid is preferably in the range of 0.01 to 10.0% by mass. According to the experimental results of the present inventors, it is known that when the concentration of phosphoric acid or phosphate is in the range of 0.01 to 10.0% by mass, a phosphorus-containing protective film is easily formed on the surface of the workpiece.

In the method for preventing lead leaching according to the second invention, it is preferable to perform a lead removal step for removing lead from the surface of the workpiece before the protective film formation step. Thereby, a low-lead-containing layer having a low lead concentration can be formed on the surface of the workpiece before the protective film forming step, so that leaching of lead from the workpiece can be further prevented.

The lead removal process can be carried out by immersing in a corrosive solution that may corrode lead. Because the corrosive solution can promote a chemical reaction with the lead on the surface of the workpiece, dissolve the lead and remove it.

Acids and lyes are conceivable as corrosive fluids. However, since copper reacts with acid, and lead, which is an amphoteric metal, reacts with both acid and alkali, it is ideal to use lye as the corrosion solution. Active lye is especially desirable. This active lye refers to lye with a pH in the range of 12-14. If the lye with pH in this range is used, the chemical reaction between this active lye and the surface lead is more likely to occur, so it is easier to dissolve and remove the lead. This active lye mainly includes aqueous solutions such as sodium carbonate, sodium hydroxide, sodium phosphate, sodium silicate, sodium triphosphate, sodium orthosilicate, and potassium hydroxide.

This corrosive solution preferably contains a surfactant. If the corrosive solution contains a surfactant, the surface tension of the corrosive solution can be reduced, and the penetration and wettability of the corrosive solution to the surface can be improved. Therefore, the lead contained on the surface of the workpiece and the corrosive solution are likely to react chemically.

As the surfactant, anionic surfactants and nonionic surfactants can be used. Examples of anionic surfactants that can be used include sodium higher fatty acid, sulfated oil, sodium salt of higher alcohol sulfate, sodium alkylbenzene sulfate, sodium higher alkyl ether sulfate, sodium α-olefin sulfate, and the like. Examples of nonionic surfactants include alkyl polyoxyethylene ethers, alkylphenyl polyoxyethylene ethers, fatty acid ethylene oxide adducts, and the like.

Preferably, the corrosive solution also contains a chelating agent. Because the chelating agent can chemically react with lead to form a water-soluble complex, it is easy to remove the lead contained on the surface.

As the chelating agent, for example, ethylenediamine, thiourea, tartaric acid, Rochelle's salt (potassium sodium tartrate tetrahydrate), EDTA, triethanolamine, etc. can be used.

In addition, it is preferable that the corrosive liquid also contains an oxidizing agent. That is to say, if the lead contained on the surface is to be removed only by the active lye etching solution, for example, when sodium hydroxide is used as the etching solution, the lead will be dissolved due to the following chemical reaction.

(14)

On the contrary, if the active lye corrosion solution contains an oxidizing agent, first the oxidizing agent and lead undergo a chemical reaction as shown in the following reaction formula (15) to form lead oxide.

(15)

Then, the lead oxide is dissolved in the lye corrosion solution, and the chemical reaction shown in the following reaction formula (16) occurs to form lead salt.

(16)

Compared with the reaction of the above-mentioned single reaction formula (14), one of the two reactions of the above-mentioned reaction formula (15) and the reaction formula (16) is carried out more rapidly. Contains lead.

As the oxidizing agent, for example, sodium m-nitrobenzenesulfonate, sodium p-nitrobenzoate, hypochlorite, bleaching powder, hydrogen peroxide, potassium permanganate, persulfate, perchlorate and the like can be used.

The method for preventing lead leaching according to the second invention is particularly advantageous when the electroplated product is subjected to a lead removal process as a plated product having a nickel-chromium layer on the outer peripheral surface of the workpiece. That is to say, the outer peripheral surface of the electroplated workpiece is protected by the nickel-chromium coating to perform the lead removal process. Therefore, the outer peripheral surface of the workpiece is not affected in any way, and lead is only removed from the inner surface without the nickel-chrome plating. Therefore, unevenness will not occur on the outer peripheral surface of the workpiece, and the nickel-chromium plating layer will not be damaged, and the outer peripheral surface of the electroplated product will have 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, in this method for preventing lead leaching, it is not necessary to conceal the deteriorated surface properties caused by the lead removal process on the workpiece before plating, and it is not necessary 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 water valve metal fitting of the second invention is characterized in that it has a base made of a copper alloy with a water-passing cylindrical portion and at least on the inner peripheral surface of the cylindrical portion is formed with the base portion. Integrated phosphorous protective film.

In this water valve metal part, since at least a phosphorus-containing protective film is formed on the inner peripheral surface of the cylindrical part, even if the cylindrical part is passed through water, the lead contained in the base part will not leach out, so when people drink from In the case of water supply by the water valve metal part, it is also possible to eliminate the doubt of harmful effects on human health. In addition, when this water is discharged into rivers and sewers, the impact on the environment can be reduced.

The water valve metal fitting uses a solution mainly containing phosphoric acid or phosphate in water as a treatment liquid, and the management of the cleaning liquid is also very simple, and the manufacturing cost can be further reduced.

The water valve metal fitting of the second invention further has a lead-containing layer formed integrally with the base part on the outer peripheral surface of the cylindrical part, and has a lead concentration substantially equal to that of the base part; and a nickel-chromium plating layer formed on the outer peripheral surface of the lead-containing layer; The inner peripheral surface of the cylindrical part is integrated with the base part, and the lead concentration is lower than the low lead-containing layer of the base part; a protective film can also be formed on the surface of the low lead-containing layer. Thereby, since a low lead-containing layer having a low lead concentration can be formed on the inner peripheral surface of the cylindrical portion, it is possible to further prevent lead from leaching from the workpiece.

A brief description of the drawings

Fig. 1 is the process diagram of the electroplating method of Embodiment 1 of the first invention.

Fig. 2 is a cross-sectional view of the water valve metal part obtained by the electroplating method of Embodiment 1 of the first invention.

Fig. 3 is a process drawing of the electroplating method of Embodiment 2 of the first invention.

Fig. 4 is a process diagram of the electroplating method in Embodiment 3 of the first invention.

Fig. 5 is a process diagram of the electroplating method in Embodiment 4 of the first invention.

Fig. 6 is a cross-sectional view of a water valve metal part obtained by the electroplating method of Embodiment 4 of the first invention.

Fig. 7 is a perspective view of the water valve metal part of the first invention.

Fig. 8 is a process diagram of a method for preventing lead leaching in Embodiment 1 of the second invention.

Fig. 9 is a cross-sectional view of a metal fitting of a water valve obtained by the method for preventing lead leaching according to Embodiment 1 of the second invention.

Fig. 10 is a process diagram of a method for preventing lead leaching according to Embodiment 2 of the second invention.

Fig. 11 is a cross-sectional view of a metal part of a water valve obtained by the method for preventing lead leaching according to Embodiment 2 of the second invention.

Fig. 12 is a perspective view of the metal part of the water valve.

Fig. 13 is a process diagram of a nickel-chromium electroplating method in the prior art.

The best way to practice the invention

[the first invention]

Hereinafter, Examples 1 to 4 in which the first invention is embodied will be described 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 electroplating method. As shown in FIG. 7 , first, a workpiece 50 a for a water valve metal fitting obtained by machining a lead-containing copper alloy such as JIS CAC 406 (Bronze Type 6) produced by casting or the like is prepared. This workpiece 50a has a water-passing cylindrical portion 10 (see FIG. 2 ). Then, as shown in Figure 1, carry out following steps successively: workpiece 50a is carried out the pretreatment process S1 of pretreatment; After the process S2, the lead removal process S3 which removes the lead of the workpiece|work 50a is carried out.

The pretreatment step S1 is the same as the usual electroplating method shown in FIG. 13, including a degreasing step S11, a cathodic electrolysis step S12, an acid activation step S13, and a washing step (not shown) between these steps. Here, in the degreasing step S11, the workpiece 50a is immersed in an alkali solution having a pH of 11 for 5 minutes to degrease the entire surface of the workpiece 50a. The lye is an aqueous solution containing several g/l of sodium hydroxide, a surfactant, a chelating agent and an oxidizing agent, and its temperature is 40°C. In the cathodic electrolysis step S12, the entire surface of the workpiece 50a is further degreased in the same alkaline solution using the workpiece 50a as a cathode. In the acid activation step S13, the workpiece a is washed with a sulfuric acid aqueous solution at room temperature and pH 2 to activate the entire surface of the workpiece 50a. In addition, a water washing step (not shown) is provided between the above-mentioned steps S11 to S13, and the workpiece 50a is washed with water.

As shown in FIG. 1, the electroplating step S2 is also the same as the general electroplating method shown in FIG. 13, and includes a nickel plating step S21 and a chrome plating step S22. In the nickel plating step S21, a nickel plating layer is applied to the outer peripheral surface of the workpiece 50a using a nickel plating solution. In the chromium plating step S22, a chromium plating layer is applied to the outer peripheral surface of the workpiece 50a processed in the nickel plating step S21 using a chromium plating solution. In this chromium plating solution, 5 to 10 g/l of sodium silicofluoride is contained as a fluoride-containing compound. In the chromium plating step S22, since chromic acid is present in the chromium plating solution, the chromic acid and lead undergo a chemical reaction, and the lead contained in the inner peripheral surface of the cylindrical portion 10 is removed. It is generally believed that at this time, the lead chromate formed in the chrome plating solution is dissolved by the fluoride. In addition, between the above-mentioned S21 and S22, a water washing step (not shown) is provided to wash the workpiece 50a with water.

In particular, in Example 1, as shown in FIG. 1 , after the electroplating step S2 , there is also a lead removal step S3 . In the deleading process S3, the workpiece 50a treated in the electroplating process S2 is soaked in a pH 14 corrosion solution as an active alkaline solution for 10 minutes. The etching solution is an aqueous solution containing 50 g/l of sodium hydroxide at a temperature of 50°C. In this way, the corrosive liquid chemically reacts with the lead on the inner peripheral surface of the cylindrical portion 10 to leach and remove the lead. At this time, since the corrosive solution is an active lye, the copper of the leaded copper alloy does not react, but only the lead reacts. In addition, a water washing process (not shown) is also provided before and after the deleading process S3, and the workpiece 50a is washed with water.

By adopting the electroplating method of this embodiment 1, the electroplated product of the water valve metal part 50 of the embodiment 1 as shown in FIG. 7 can be obtained. As shown in Figure 2, this water valve metal part 50 includes: a base part 30 made of a leaded copper alloy with a water-passing cylindrical part 10; The lead-containing layer 30a whose concentration is substantially equal to that of the base part; the nickel-chromium plating layer 20 formed on the outer peripheral surface of the lead-containing layer 30a; low lead-containing layer 30b. When the water valve metal fitting 50 is used, the water W passes through the cylindrical portion 10 .

(comparative example 1)

The electroplating method of Comparative Example 1 is a general nickel-chromium electroplating method as shown in FIG. 13 , and the difference from the electroplating method of Example 1 is that no lead removal process is performed after the electroplating process S2. Other conditions are the same as in Example 1.

Using the electroplating method of Comparative Example 1, the water valve metal part 50 electroplated product of Comparative Example 1 can be obtained.

(comparative example 2)

The electroplating method of comparative example 2 is only in the degreasing process S11 of the general nickel-chromium electroplating method as shown in Figure 13, dipping is carried out in the high pH alkaline solution, the same as comparative example 1, does not carry out the deleading process after the electroplating process S2 S3.

The lye used in the degreasing process contains 50 g/l of sodium hydroxide, 2 g/l of sodium alkylbenzenesulfonate as a surfactant, 2 g/l of EDTA and 2 g/l of ethylenediamine as a chelating agent, And an aqueous solution of 2 g/l of sodium m-nitrobenzenesulfonate as an oxidizing agent, the temperature of which is 50°C. Other conditions are the same as in Example 1 and Comparative Example 1.

Using the electroplating method of Comparative Example 2, the water valve metal part 50 electroplated product of Comparative Example 2 was obtained.

(evaluate)

For the water valve metal parts 50 of Example 1 and Comparative Examples 1 and 2, the concentration of lead leached in water flowing through the cylindrical portion 10 was measured in accordance with JISS3200-7 (1997) "Utensils for Tap Water - Leachability Test Method" (ppb), while visually confirming the surface properties of the nickel-chromium plating layer 20. The results are listed in Table 1.

Table 1 Concentration of leached lead (ppb) The surface properties of the coating Example 7 ○ Comparative example 1 30～40 ○ Comparative example 2 12 x

As can be seen from Table 1, although the surface properties of the nickel-chromium plating layer 20 of the water valve metal part 50 of Comparative Example 1 are good, the concentration of leached lead increases because the lead removal step S3 is not performed after the electroplating step S2 in the electroplating method.

The water valve metal part 50 of Comparative Example 2, because in the degreasing step S11 of the electroplating method, carried out the immersion in the alkaline solution with high pH, so the concentration of leached lead has decreased to some extent, but the surface of the nickel-chromium plating layer 20 Bad traits.

On the contrary, in the water valve metal part 50 of Example 1, since the lead removal step S3 is performed after the electroplating step S2, the concentration of leached lead is extremely low, and the surface properties of the nickel-chromium plating layer 20 are good. This is because the electroplating method of embodiment 1 carries out the deleading process S3 after the electroplating process S2, so the nickel-chromium plating layer 20 on the outer peripheral surface of the workpiece 50a is protected and does not remove lead, and only from the workpiece 50a inner periphery without the nickel-chromium plating layer 20 remove lead. Therefore, no unevenness occurs on the outer peripheral surface of the workpiece 50a, and the nickel-chromium plating layer 20 is not damaged, so the outer peripheral surface of the water valve metal part 50 has a good surface texture, achieving a beautiful effect.

In addition, in the electroplating 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 appearance of the water valve metal fitting 50, so that the manufacturing cost can be reduced.

It can be seen that, according to the electroplating method of Embodiment 1, the amount of lead leaching into the water from the inner peripheral surface of the cylindrical portion 10 can be reduced, which has an aesthetic effect, and can manufacture an inexpensive water valve metal part 50 .

That is to say, the water valve metal fitting 50 of Embodiment 1 has a low concentration of lead in the low lead-containing layer 30b on the inner peripheral surface of the cylindrical portion 10, so even if the inner peripheral surface is passed through water, lead is difficult to leach out. in the water. For this reason, when the water supplied from the water valve metal part 50 is used for human drinking, it is possible to eliminate the concern of affecting human health. When the water is discharged into rivers and sewers, environmental pollution can also be reduced.

Example 2

In the electroplating method of Example 2, as shown in FIG. 3 , the deleading process S3 is performed on the stock water valve metal part 50 obtained through the general nickel-chromium electroplating process shown in FIG. 13 . Other conditions are identical with embodiment 1.

Using the electroplating method of Embodiment 2, the stock water valve metal part 50 meeting the lead leaching standard in the past can be processed into the same water valve metal part 50 as in Embodiment 1. Therefore, with this plating method, there is little need for special design changes within the plant to achieve compliance with the new lead leaching standards. Therefore, there is an effect that it is not necessary to increase the manufacturing cost in order to conform to the standard.

Example 3

In the electroplating method of Example 3, as shown in FIG. 4 , the lead removal process S3 is performed on the water valve metal part 50 obtained in Example 1 again. Other conditions are identical with embodiment 1.

Using the electroplating method of Example 3, even when stricter lead leaching standards are implemented, the water valve metal parts 50 meeting the standards can be obtained without any special modification of the factory design. If the conditions of the lead removal step S3 are strictly controlled, the low-lead-containing layer 30b of the cylindrical portion 10 may not be present, so this electroplating method can also achieve the effect of not having to increase the manufacturing cost to meet the standards.

Example 4

In the electroplating method of Example 4, as shown in FIG. 5 , after the lead removal step S3 , a chromate treatment step S4 as an inertization step is also performed.

In this 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 10 g/l of phosphoric acid, and its temperature is room temperature. Other compositions are identical with embodiment 1.

In the chromate treatment step S4, due to the action of chromic acid in the chromate solution, a chemical reaction between chromic acid and lead occurs, and lead contained in the inner peripheral surface of the cylindrical portion 10 is further removed. It is generally believed that at this time, both chromic acid and phosphoric acid can effectively promote the chemical reaction of lead leaching and the chemical reaction of forming a chromate protective film 40 (refer to FIG. 6 ). , Since all use chromic acid, it can exert excellent workability.

As shown in FIG. 6, the water valve metal fitting 50 of Example 4 obtained in this way is composed of the following parts: a base part 30 made of a lead-containing copper alloy with a cylindrical part 10 for passing water; The side is formed integrally with the base part 30, and the lead concentration is substantially equal to the lead-containing layer 30a of the base part 30; the nickel-chromium plating layer 20 formed on the outer peripheral surface side of the lead-containing layer 30a; the inner peripheral surface of the cylindrical part 10 and the base part 30 integrally formed with a low-lead-containing layer 30b having a lead concentration lower than that of the base portion 30; and a chromate protective film 40 formed on the inner peripheral surface of the low-lead-containing layer 30b.

In this water valve metal fitting 50, since the chromate protective film 40 is formed on the inner peripheral surface of the low-lead-containing layer 30b, the lead remaining on the inner peripheral surface of the cylindrical part 10 is inert by the chromate protective film 40 and is difficult to leach.

[the second invention]

Hereinafter, Examples 1 and 2 in which the second invention is embodied will be described together with Comparative Examples 1 and 2 with reference to the drawings.

Example 1

In the method for preventing lead leaching in Example 1, first, two kinds of lead-containing copper alloys as materials 1 and 2 below were prepared. Material 1 is bronze composed of 5% by mass of lead, 85% by mass of copper, 5% by mass of zinc, and 5% by mass of tin. Material 2 is brass composed of 2% by mass of lead, 63% by mass of copper, and 35% by mass of zinc.

Then, as shown in FIG. 12, by cutting these lead-containing copper alloy lumps, various workpieces 50a for water valve metal parts are respectively obtained. As shown in FIG. 9, the workpiece|work 50a has the cylindrical part 10 through which water passes. As shown in Figure 8, each workpiece 50a is carried out following steps successively: carry out the pretreatment process S1 of pretreatment; After this pretreatment process S1, apply the electroplating process S2 of nickel-chromium plating layer at the outer peripheral surface of each workpiece 50a; After the electroplating step S2, a protective film forming step S3 is performed to form a phosphorous-containing protective film on the surface of each workpiece 50a.

The pretreatment step S1 is the same as the general electroplating method shown in FIG. 13 , including a degreasing step S11, a cathodic electrolysis step S12, an acid activation step S13, and a washing step (not shown) between these steps. Here, in the degreasing step S11, each workpiece 50a is immersed in an alkali solution having a pH of 11 for 5 minutes to degrease the entire surface of each workpiece 50a. The lye is an aqueous solution containing several g/l of sodium hydroxide, a surfactant, a chelating agent and an oxidizing agent, and its temperature is 40°C. In the cathodic electrolysis step S12, the entire surface of each workpiece 50a is further degreased in the same alkaline solution using each workpiece 50a as a cathode. In the acid activation step S13, each workpiece a is washed with a sulfuric acid aqueous solution at room temperature and pH 2 to activate the entire surface of each workpiece 50a. In addition, between the above-mentioned steps S11 to S13, a water washing step (not shown) is provided to wash each workpiece 50a with water.

As shown in FIG. 8 , the electroplating step S2 is also the same as the general electroplating method shown in FIG. 13 , and includes a nickel plating step S21 and a chrome plating step S22 . In the nickel plating step S21, a nickel plating layer is applied to the outer peripheral surface of each workpiece 50a using a nickel plating solution. In the chromium plating step S22, a chromium plating layer is applied to the outer peripheral surface of each workpiece 50a processed in the nickel plating step S21 using a chromium plating solution. This chromium plating solution contains 5 to 10 g/l of sodium silicon fluoride as a fluoride. In this chromium plating step S22, since chromic acid is present in the chromium plating solution, the chromic acid and lead undergo a chemical reaction, and the lead contained in the inner peripheral surface of the cylindrical portion 10 is removed. It is generally believed that the lead chromate formed in the chrome plating solution is dissolved by fluoride at this time. In addition, between the above-mentioned S21 and S22, a water washing step (not shown) is provided to wash each workpiece 50a with water.

In the method for preventing lead leaching in Example 1, as shown in FIG. 8 , a protective film forming step S3 is further included after the plating step S2 . In the protective film forming step S3, the workpiece 50a after the electroplating step S2 is immersed in the treatment solution for 10 minutes.

The treatment liquid was an aqueous solution containing 0.9% by mass of phosphoric acid (H ₃ PO ₄ ), and its temperature was 50°C.

In this way, as shown in FIG. 9 , the treatment liquid reacts with the copper and/or lead on the inner peripheral surface of the cylindrical portion 10 to form a phosphorus-containing protective film 40 on the inner peripheral surface of the cylindrical portion 10 . In addition, before and after this protective film forming step S3, a water washing step (not shown) is also provided to wash each workpiece 50a with water.

Using the above method for preventing lead leaching, an electroplated water valve metal part 50 as shown in FIG. 12 can be obtained. As shown in FIG. 9 , these various water valve metal parts 50 include: a base part 30 made of a lead-containing copper alloy with a water-passing cylindrical part 10 formed with the base part 30 on the outer peripheral surface side of the cylindrical part 10 The lead-containing layer 30a which is integral and whose lead concentration is substantially equal to that of the base part 30, the nickel-chromium plating layer 20 formed on the outer peripheral surface of the lead-containing layer 30a is formed integrally with the base part 30 on the inner peripheral surface of the cylindrical part 10, and the lead concentration is the same as that of the base part. The lead-containing layer 30b substantially equal to the portion 30, and the phosphorus-containing protective film 40 formed on the inner peripheral surface of the lead-containing layer 30b. When the water valve metal fittings 50 are used, the water W passes through the cylindrical portion 10 .

Example 2

In the method for preventing lead leaching in Example 2, as in Example 1, workpieces 50a for water valve metal parts as shown in FIG.

The method for preventing lead leaching in Example 2 differs from the method for preventing lead leaching in Example 1 in that, as shown in FIG. The processing time of step S4 and the protective film forming step S3 are different.

In the deleading process S4, the workpieces 50a after the electroplating process S2 are placed in the corrosion solution of pH 14 as the active alkaline solution, and immersed for 3 minutes. The etching solution was a 5% by mass sodium hydroxide aqueous solution at a temperature of 50°C. The etchant chemically reacts with the lead on the inner peripheral surface of the cylindrical portion 10 to leach and remove the lead. At this time, because the corrosive solution is an active lye, it does not react with the copper of the lead-containing copper alloy, but only reacts with lead. In addition, before and after the deleading 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 removal step S4 is immersed in the treatment solution for 3 minutes. Other conditions are identical with embodiment 1.

Using the method for preventing lead leaching in Example 2, electroplated products of each water valve metal part 50 as shown in FIG. 12 were obtained in the same manner as in Example 1. As shown in FIG. 11 , each of the water valve metal parts 50 is composed of the following parts: a base part 30 made of a lead-containing copper alloy with a water-passing cylindrical part 10 formed with the base part 30 on the outer peripheral surface side of the cylindrical part. The lead-containing layer 30a which is integral and whose lead concentration is approximately equal to that of the base part 30, the nickel-chromium plating layer 20 formed on the outer peripheral surface side of the lead-containing layer 30a is formed integrally with the base part 30 on the inner peripheral surface of the cylindrical part 10, and the lead concentration The low-lead-containing layer 30c lower than the base portion 30, and the phosphorus-containing protective film 40 formed on the inner peripheral surface side of the low-lead-containing layer 30c.

(comparative example 1)

In the method for preventing lead leaching in Comparative Example 1, as in Example 1, workpieces 50a for water valve metal parts as shown in FIG.

However, in Comparative Example 1, only the general nickel-chromium plating method shown in FIG. 13 was used to apply the nickel-chromium plating, and no special method for preventing lead leaching was used. Other conditions are identical with embodiment 1.

The water valve metal part 50 electroplating product of Comparative Example 1 was obtained by using the electroplating method of Comparative Example 1.

(comparative example 2)

In the method for preventing lead leaching in Comparative Example 2, as in Example 1, workpieces 50a for water valve metal parts as shown in FIG.

However, the method for preventing lead leaching in Comparative Example 2 does not include the protective film forming step S3 in the method for preventing lead leaching in Example 2 as shown in FIG. 10 . In addition, in the deleading step S4, each workpiece 50a is immersed in an etching solution having a pH of 14, which is an active alkali solution, for 10 minutes, which is also different from Example 2. Other conditions are identical with embodiment 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.

(evaluate)

For the water valve metal fittings 50 of Examples 1 and 2 and Comparative Examples 1 and 2, the leaching of lead in water flowing through the cylindrical part 10 was measured in accordance with JISS3200-7 (1997) "Utensils for Tap Water—Leaching Performance Test Method". concentration (ppb). The results are listed in Table 2.

Table 2 Concentration of leached lead (ppb) Material 1 Material 2 Example 1 9 4 Example 2 5 1 Comparative example 1 60 13 Comparative example 2 20 4

As can be seen from Table 2, the water valve metal fitting 50 of Comparative Example 1 has a high concentration of leached lead because the protective film forming step S3 is not performed after the electroplating step S2. On the other hand, although the water valve metal fitting 50 of Comparative Example 2 is not subjected to the protective film forming step S3 after the electroplating step S2 , the lead removal step S4 is performed, so the leaching concentration of lead is low for the material 2 . However, for Material 1, the leaching concentration of lead was not reduced much. In addition, in order to reduce the concentration of leached lead to some extent, each workpiece 50a is immersed in the corrosion solution for a long time in the lead removal step S4.

On the contrary, in the water valve metal fitting 50 of Example 1, since the protective film forming step S3 was performed after the electroplating step S2, both materials 1 and 2 had a low concentration of leached lead. However, in Example 1, it is also preferable to immerse each workpiece 50a in the treatment liquid for a long time in order to reduce the leached lead concentration to some extent.

However, in the water valve metal part 50 of the second embodiment, since the lead removal step S4 and the protective film formation step S3 are performed after the electroplating step S2, the concentration of leached lead is extremely low. Furthermore, in Example 2, since the protective film forming step S3 is performed, in the lead removing step S4, it is sufficient to immerse each workpiece 50a in the corrosive solution for 3 minutes. That is to say, in embodiment 2, although two processes of deleading process S4 and protective film forming process S3 are carried out, their total required time is only 6 minutes, which is 10 minutes compared with the required time of deleading process S4 of comparative example 2. Minutes are relatively short, and it can be seen that the workability of Example 2 is superior.

In the water valve metal fittings 50 of Examples 1 and 2, the low concentration of leached lead is considered to be due to 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. to prevent lead leaching.

In addition, in the lead leaching prevention method of this embodiment 1 and 2, use the solution that mainly adds phosphoric acid or phosphate in water as treatment liquid, phosphoric acid or phosphate and the chromic acid-containing chromic acid bath that forms chromium plating layer are used and inert Compared with chromated chromate solution containing chromic acid, it is almost non-toxic. Therefore, the cleaning solution and the like can be treated by neutralizing and diluting the cleaning solution and the waste solution of each workpiece 50a after being washed and contacted with the treatment solution. Therefore, management of cleaning liquid and the like is easy.

Therefore, according to the methods for preventing lead leaching in Examples 1 and 2, the amount of lead leached into water from the inner peripheral surface of the cylindrical portion 10 can be reduced, and an inexpensive water valve metal fitting 50 can be manufactured.

Finally, in the water valve metal fittings 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, even if the inner peripheral surface is passed through water, it is difficult for lead to enter the water. For this reason, when the water supplied by the water valve metal part 50 is used for human drinking, the concern of affecting human health can be eliminated. In addition, when this water is discharged into rivers and sewers, it can also reduce environmental pollution.

(test)

From the lead-containing copper alloy of material 3 shown below, several workpieces 50a for water valve metal parts as shown in FIG. 12 were obtained as in Example 1. Material 3 is bronze composed of 5% by mass of lead, 85% by mass of copper, 5% by mass of zinc, and 5% by mass of tin.

As shown in FIG. 10, these workpieces 50a were treated in the same order as in Example 2 in the order of pretreatment step S1, electroplating step S2, lead removal step S4, and protective film formation step S3, and water samples 1 to 6 were obtained. An electroplated product of the valve metal part 50 .

(evaluate)

The lead leaching concentration (ppb) in the water flowing through the cylindrical portion 10 was measured for the water valve metal fittings 50 of these samples 1 to 6 according to the above-mentioned "Utensils for Water Service—Leaching Performance Test Method". At this time, the treatment conditions such as phosphoric acid concentration (mass %), treatment temperature (°C) and treatment time (seconds) of the protective film forming step S3 performed on the water valve metal fittings 50 of samples 1 to 6 were different. Other conditions are identical with embodiment 2. Taking the treatment conditions of the water valve metal part 50 of sample 1 as the standard, the results are listed in Table 3.

table 3 Sample No Phosphoric acid concentration (mass%) Processing temperature (℃) Processing time (seconds) 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

It can be known from Table 3: From the data of the water valve metal parts 50 of samples 1 to 3, the concentration of phosphoric acid is the most ideal at 0.9% by mass, and if it is between 0.01% and 10.0% by mass, the concentration of leached lead does not change much , good results can be obtained.

Although it is speculated that the higher the temperature of the treatment liquid, the better, but from the data of the water valve metal part 50 of sample 4, even if the temperature of the treatment liquid is lowered to 5°C, the concentration of the leached lead is almost unchanged and can reach a sufficient level. Effect. Therefore, the method of the present invention can also receive sufficient effect in winter.

In addition, it is generally speculated that the longer the treatment time, the better, but from the data of the water valve metal parts 50 of samples 5 and 6, it is known that even if the treatment time is as short as 5 seconds, the concentration of leached lead is almost unchanged, which can be get great results. Therefore, the method of the present invention can obtain sufficient effects even if the treatment is performed in a relatively short time.

The above embodiments and applications are illustrative. The first and second inventions can be implemented in various modified forms within the range not exceeding the main purpose.

Possibility of industrial use

With the lead removal method of the first invention, the amount of lead leached into water from the inside of the cylindrical portion can be reduced to achieve an aesthetic effect, and an inexpensive electroplated product can be produced.

The amount of lead leached into water from the lead-containing copper alloy can be easily reduced by the method for preventing lead leaching according to the second invention. Therefore, according to the method for preventing leaching of lead according to the second invention, it is possible to prevent leaching of lead and reduce manufacturing costs. In addition, the water valve metal fitting of the second invention can reduce the amount of leaching of lead into water. Furthermore, it can be manufactured easily.

Claims (11)

1, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion, it is characterized in that: at the periphery of the copper alloy containing lead workpiece that has the water flowing cylindrical portion, implement the electroplating work procedure of coating,, carry out from the deleading operation of the inner peripheral surface deleading of this cylindrical portion to the plated item that obtains thus.

2, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 1 is characterized in that: after the deleading operation, carry out the inerting operation with the inner peripheral surface inerting of cylindrical portion.

3, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 1 or 2 is characterized in that: the deleading operation is can carry out from the corrosive fluid of the inner peripheral surface corroding lead of cylindrical portion by being immersed in.

4, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 3 is characterized in that: corrosive fluid is the alkali lye of PH12-14.

5, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 2, it is characterized in that: its electroplating work procedure has and uses the chromium plating liquid contain chromic acid to carry out galvanized chromium plating operation, and its inerting operation has workpiece is immersed in chromate treating operation in the chromate solution that contains chromic acid.

6, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 5 is characterized in that: contain fluorochemical in the chromium plating liquid.

7, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 5 is characterized in that: contain phosphoric acid in the chromate solution.

8, the method for removing lead of the copper alloy containing lead plated item of band cylindrical portion as claimed in claim 1 is characterized in that: workpiece is to make the workpiece that the water valve metalwork is used.

9, a kind of water valve metalwork is characterized in that it is made of following each several part: the matrix part that the copper alloy containing lead of band water flowing cylindrical portion constitutes; This cylindrical portion periphery and this matrix part form one, lead concentration and this matrix part about equally contain lead layer; Contain the electrolytic coating of periphery formation of lead layer at this; Form one, the low lead layer that contains that lead concentration is lower than this matrix part at the inner peripheral surface of this cylindrical portion and this matrix part.

10, water valve metalwork as claimed in claim 9 is characterized in that: low contain in the lead layer not leaded.

11, as claim 9 or 10 described water valve metalworks, it is characterized in that: the low inner peripheral surface that contains lead layer is a chromate protective film.

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